1 10 46 https://eprints.ibu.edu.ba/files/original/ade2f568548c50da88671751de1d9811.pdf 6570cefe0cdbb13adcd981ced48fd2a6 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal of Natural Sciences and Engineering Identifier An unambiguous reference to the resource within a given context 2637-2835 DOI Digital object identifier 10.14706 Publisher An entity responsible for making the resource available International Burch University Description An account of the resource Journal of Natural Sciences and Engineering (JONSAE) is a peer-reviewed, biannually published international journal focusing on empirical and theoretical research in all branches of Engineering and Natural Sciences. It is published on the behalf of Faculty of Engineering and Natural Sciences of International Burch University and aims to provide the best content regarding by publishing original research papers, review articles, special issues, feature articles, and book reviews. All manuscript submissions are subject to initial appraisal by the Editor, and, if found suitable for further consideration, to peer review by independent, anonymous referees. All peer review is double-blind and submission is online. The journal welcomes theoretical, applied, interdisciplinary and methodological work, with preference on empirical research, critical approach and problem-solving methods in manuscripts. Language A language of the resource English Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Analysis of High School Graduate Data Using Database Analytics Tools Author Author Ezana Ćeman, Ajdin Salihović, Samed Jukić Abstract A summary of the resource. It can be confidently stated that access to education is one of the most prized possessions available to us today. Although there are underlying factors such as the discrepancies in the education being provided worldwide, it is imperative that data scientists and all those interested take advantage of the data publicly available to draw necessary insights into how to better the education sector in our respective countries. The purpose of this research is to showcase various analytical insights into the 2020 New York State (NYS) high school graduation rate data using various advanced database systems techniques, specifically using SQL. With these analyses, further studies and conclusions can be drawn for local governments to implement into their plans to increase the quality of the schooling system, to aim for equality for all without regard to cultural and ethnic background, and to find discrepancies within the current system.</div> <quillbot-extension-portal></quillbot-extension-portal> Keywords Keywords. Database, data analysis, graduate, high school, New York State, SQL Identifier An unambiguous reference to the resource within a given context ISSN 2637-2835 DOI Digital object identifier 10.14706/JONSAE2021322 Publisher An entity responsible for making the resource available International Burch University Language A language of the resource English language Type The nature or genre of the resource Original research https://eprints.ibu.edu.ba/files/original/097f70db222c171be9a1b8c5a393af84.pdf b3ead4db3fc460f477e7d5dce620b6e5 PDF Text Text Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020217 Analysis of Transient and Voltage Stability of an 11-Busbar Testing System Alma Halilović1, Mirza Šarić1 1 International Burch University, Sarajevo, Bosnia and Herzegovina alma.halilovic@stu.ibu.edu.ba mirza.saric@ibu.edu.ba Abstract – A comprehensive treatment from the physical and mathematical perspective supply modelling, analysis, control and covers a range of topics including modelling, computation of load flow in the transmission grid, stability analysis of the transient state. It is widely accepted that transient stability is an important aspect in designing and upgrading electric power system. In utility planning, transient stability is studied by numerical simulation. It involves the study of the power system following a major disturbance. In order to study Electric Power System transient stability, the models to describe their components should be defined. The components are defined using the classical model, which is valid to time periods up to 2 seconds. This project contains 11 busbars, 1 synchronous generator, 3 loads and 8 transformers. This research is done in DIgSILENT PowerFactory software for network modeling and simulation by using Stability Analysis Functions (RMS) advanced feature. In this paper we are analyses the maximum rated power of distributed generation (DG) considering only the terms of voltage limit constraints, the N-1 operational criterion analysis and three-phase symmetrical fault analysis for N-1 criterion is examined. Keywords - high load, n-1 criterion, synchronous generator, transient stability analysis 1. Introduction Stability in Power Systems is one of the importances of a system that had increased. It is the most widely used from power blackouts. Today, usage of power systems interconnection had increased using of new technologies and controls, and the increased its usage in highly demanding situations. In order to maximize the system stability research on power system stability should be carried out. In order to design the perfect system to solve this problem a detailed study of the design should be performed. In the last years [1], due to the spread of electric generation facilities and economic factors, Electric Power Systems operate more closely to their limits. Thus, more than before, it is of crucial importance the existence of methods to assess the system stability. In [2] there are two kinds of stability problems: voltage stability and transient stability. This paper addresses the transient stability. Transient stability analysis of a power system is concerned with the system’s ability to remain in synchronism following a disturbance. Following a large disturbance, the synchronous alternator the machine power (load) angle changes due to sudden acceleration of the rotor shaft. The objective of the transient stability study is to ascertain whether the load angle returns to a steady value following the clearance of the �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020217 disturbance. The loss of synchronism develops in a very few seconds after the disturbance inception, among the phenomena transient stability is the fastest to develop. These challenging aspects motivate our choice to mainly concentrate on transient stability. The conventional transient stability measure of the system robustness to withstand a large disturbance is its corresponding critical clearing time (CCT). This is the maximum time duration that the disturbance may act without the system losing its capability to recover a steady-state operation. Another transient stability measure of great practical importance is the power (generation or transfer) limit. It is defined as the largest power sustainable without loss of synchronism, given the occurrence of a large disturbance and it’s clearing scenario. In [4], note that the measures imply consideration of three distinct phases: the pre-fault, the during-fault, and the post-fault one. In [5] faults need to be cleared within critical clearing time and after that system need to be able to regain stability. Some of the most important parameters influencing stability are fault clearance time, fault location, and type of the fault. 2. Literature Review Mania Pavella [3] identified three classes of approaches – Decision Tree, KNN and neural network - to transient stability and analyzed which can meet most stringent requirements of transient stability. It is found that stability could be achieved with the appropriate combinations of numerical, direct, and automatic learning techniques. Mirza Saric and Irfan Penava [5] in their research discussed theoretical background of induction generator, its simulation model, as well as dynamic response analysis procedure for a wind farm connected to real network. Thought their research they showed the importance of transient stability in case of integration of large renewable sources to the network. In terms of rotor angle, frequency and voltage stability issues the observed case of wind farm integration was not appropriate to connect to the network with induction generator as the rotor speed was too large, with sharp reduction of reactive power as voltage and active power equal to zero for period that are too long for system to operate in stable state. Innocent Davidson and Immanuel Mbangula [6] examined and analyzed the fault that appeared on the 330kV transmission line between Omburu sub-station and Ruacana power station where the blackout happened for 6 hours. The goal of this research was to investigate what fault occurred, what is the cause and solutions to prevent such fault occur again. The results from DIgSILENT PowerFactory are compared with data obtained from NamPower records and it is found that it was the single phase to ground fault. Ioanna Xyngi, Anton Ishchenko, Marjan Popov, and Lou van der Sluis [7] in their research described the transient stability analysis of a 10-kV distribution network with wind generators, microturbines, and CHP plants modeled in Matlab/Simulink and investigated faults that are simulated on various locations. They showed that in the network with distributed generators (DGs) the protection settings must be adjusted accordingly in order to have stable system as the undervoltage protection should be different for different DGs. �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020217 Diaz-Alzate, Candelo-Becerra and Villa Sierra [8] investigated and found a new way of managing and controlling transient stability based on relative angles. They showed how predefined thresholds of relative angles which they attained by offline simulations and the relative angles attained during the online operation with PMUs are useful in the process of monitoring as well as predicting transient stability under real-time operation. They performed analysis on New England with 39 busbars and IEEE with 118 busbars networks with different contingencies and control actions that are applied at predicted time. The relative angle and the predefined thresholds of the relative angle helped in monitoring and predicting of the systems instability with enough time to respond to oscillations that appeared in the system. 3. Methodology In this part we will show 3 different steps of methodology. In first step we will search and show what is the maximum power that satisfies standards of synchronous generator while checking the voltage profile. In the second step we will do N-1 operational criterion analysis for 6 different cases in this grid and found the new maximum power that satisfies the network. In the last step we will do three phase symmetrical fault analysis for N-1 criterion, with 4 different cases in it. (a) In the first part of the project the maximum rated power of a generator at BB13 (DG), considering only the voltage limit constraints is found, and then the three-phase symmetrical fault analysis is performed for the value of maximum power. We investigate fault duration period of 0.02 seconds. After the RMS simulation is done, voltage development, rotor angle, active and reactive powers are plotted for the further analysis. b) In the second step the n-1 criterion in terms of voltage profile development, as well as line and transformer loading, for 6 different cases for high load scenario, with maximum DG power was investigated. An operational criterion N-1 can be applied to the existing network, if there may be planned or unplanned congestion that may exist at a certain moment. If the criterion is satisfied, that means the system will be able to support a predefined contingency, operating after that, with a minimum performance. The N-1 criterion requires that the system can be able to tolerate the outage of any one component without disruption and does not concern itself with the probability of an outage. If an outage is highly unlikely, the criterion is still generally applied because system failure due to a lost component is unacceptable. The criterion is generally considered as the need to balance generation and load. For modeling network for 6 different scenarios, 6 lines from which the network is consisted are modeled with the following event that placed lines one by one out of service. The voltage on the critical busbar – point of coupling - was monitored along the way, as well as the voltage in the entire system, with the line and transformer loading, making sure that the voltage or line and transformer loading does not exceed the permitted limit specified by the standard EN 50160 for delivered power quality. Minimum upper limit for the voltage, as denoted in the EN 50160 standard, is 0.9 p.u., while maximum upper limit for the voltage is 1.1 p.u. Regarding the line and transformer loading the constraint limits determined by the standard EN 50160 is that it does not exceeds loading of 100 %. In such way the n-1 criterion is investigated and the maximum power for which the system is in the stable mode operation is found for each of the different scenarios when one by one line were out of service. For different events that �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020217 placed different line out of service, the system will be stable for different maximum power produced from generator. c) In the next part of the research the three-phase symmetrical fault is simulated and the rotor angle, active power, reactive power and voltage development for the following cases, for high load conditions and maximum DG power is to be reported in the results and discussion part of this research project. Three-phase symmetrical fault is simulated in the DIgSILENT PowerFactory software for network modeling and simulation, one second before, during and 5 seconds following the fault on 6 different lines for each of the case scenario. This research is done in DIgSILENT PowerFactory software for network modeling and simulation by using Stability Analysis Functions (RMS) advanced feature. First, the maximum power generation from synchronous generator is found by using the power flow option in the program where all voltage on all busbars, as well as line and transformer loading in the network, is checked so to satisfy EN 50160 standard limits. Next, in order to satisfy limits, set by EN 50160 standards in terms of voltage profile, line and transformer loading when 6 lines of which the system is consisted are modeled with an event that placed line one by one out of service. In such way, by using the power flow analysis function when lines are out of service the n-1 criterion is investigated. For the third part of the research, where three-phase symmetrical faults are simulated on each of the 6 lines that were investigated. The duration of the fault is for the analysis of the 4 case scenarios set on lines to be 0.02, 0.05, 0.5 and 5 seconds and then rotor angle, active power, reactive power and voltage development for the following cases, for high load conditions and maximum DG power are plotted in the graphs, and in such way the behavior of the system could be tracked. d) In the last part of this project the power factor is changed when line 2 is followed with an event that placed it out of service, thus when investigating the N-1 criterion. Values of power factor that are taken into consideration are 0.8, 0.9 and 1, both capacitive and inductive while the voltage development is analyzed and new maximum power of generator is determined in order to satisfy EN 50160 standard for voltage variation in the network for new values of power factor. 4. Results and Discussion A. Maximum Power from Generator in Terms of Voltage Profile In the first part the maximum voltage in the network is found by changing the power generated by the synchronous generator while checking the voltage profile of the network in order that voltage does not increase beyond allowed limits. In the Table III. main results of power flow in terms of voltage magnitude and angle at the busbar BB11 which is the point of coupling, are shown when network operates with no any faults occurring in the system. Maximum power generated from synchronous generator that satisfy the voltage limits set by EN 50160 standard is found to be 286 MW, while the maximum power that satisfy all criterions from the standard – voltage, line and transformer loading – is found to be 104 MW. �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020217 Fig. 1. Network Model from DIgSILENT PowerFactory software The power stability analysis of the given network is done in terms of three-phase symmetrical fault analysis for the maximum power which satisfies the allowed voltage limits and equals to 286 MW. The three cases are investigated where the duration of the fault is set to be 0.02 seconds in fist case, 0.05 seconds in second case and 0.2 seconds in third case. The results obtained when duration of fault is taken to be 0.02, which is expected to show the best results due to lowest fault duration, are shown in Fig.1. In the Fig 1. where the graphs of voltage of the busbar which is the point of coupling, angle of rotor of the synchronous generator, as well as active and reactive power of the synchronous generator are plotted. It can be seen from the graphs that for the maximum power that satisfy the EN 50160 standard only in terms of voltage profile, the system is unstable even for the very small periods of fault duration and it shows that for this high power of generator the network quite inadequate to operate. B. N-1 Operational Criterion Analysis Summary of results obtained when different lines in the network placed out of service are presented in the Table I. and dynamic response of voltage profile in Fig.2., as well as rotor angle in Fig.3. It can be observed which line is the most critical and which is maximum power for such line. The maximum power that satisfies the n-1 criterion for the entire network is found to be 93 MW, since it satisfys the n-1 criterion for the most critical line, which is little bit lower than the maximum power that satisfys the EN 50160 standard for delivered power quality when all lines are in service that is found to be 104 MW. The maximum power for line 1 and line 2 is 93 MW, thus, this value of generated power is compared with maximum power of all other lines in the system, while the voltage magnitude, as well as angle, does not change significantly. In the Table II. the line and transformer loading is compared for same lines for their maximum power and value of 93 MW, and as it can be seen, there is approximately more that 10% of difference in line loading and around 4% in transformer loading. From the results obtained it can be concluded that the most realiable solution is to consider value 93 MW as maximum power that satisfy N-1 criterion for entire network. �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020217 Table 1. Voltage developments for maximum power for each line in the network determined by N-1 criterion Out of service (BB11) Line 1 93 MW Line 2 93 MW Line 3 93 MW Line 3 105 MW Line 4 93 MW Line 4 105 MW Line 5 93 MW Line 5 100 MW Line 6 93 MW Line 6 105 MW UI, Magnitude MV 67,81801 67,1283 67,4659 68,03866 67,39707 67,94841 65,03935 65,13477 67,48871 68,16291 u, Magnitude p.u. 1,027546 1,017095 1,022211 1,030889 1,021168 1,029521 0,985445 0,98689 1,022556 1,032771 U, Angle deg 6,905885 6,473696 6,748108 8,197442 6,682203 8,111645 8,237019 9,947232 5,909104 7,01058 Table 2. Line and transformer loading for N-1 criterion in % N-1 criteria (BB11) Line 1 Line 2 Line 3 Line 4 Line 5 Line 6 Power Loading [%] line 2/1 93 MW 93 MW 93 MW 105 MW 93 MW 105 MW 93 MW 100 MW 93 MW 105 MW 97,9854 99,39992 87,84784 99,58101 87,93902 99,71524 91,17996 98,65325 87,81764 99,39667 Loading [%] Two-winding transformer (5) 93,85382 96,90187 81,66314 84,96854 81,74933 85,08491 84,81535 87,13317 81,63461 84,80878 Fig. 2. Dynamic response for 0.02 s fault duration on lines – Voltage Fig. 3. Dynamic response for 0.02 s fault duration on lines – Rotor Angle �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020217 C. Three Phase Symmetrical Fault Analysis for N-1 Criterion Since it has been shown that the system is unstable for the maximum power that satisfy EN 50160 standard in term of voltage variation, the three-phase symmetrical fault analysis is done after the N-1 criterion is satisfied for the observed network. The maximum power on the most critical line is previously found to be 93 MW by using the N-1 criterion, and in this part, this is the power for which the system is analyzed. The four cases are examined where the duration of the fault is set to be 0.02 seconds in the first, 0.05 seconds in the second, 0.5 seconds in the third and 5 seconds in the fourth case. Since the line 2 is shown to be most critical in the network after the N-1 criterion analysis done for this case, the result for this line are shown in the graph plotted after the RMS simulation done. In the Fig. 4. the dynamic response for 0.02 seconds fault duration on line 2 in terms of voltage profile is shown. As it can be seen from the graph, when the fault occurs in the system on the line 2, there is voltage drop at the time of fault occurrence and as the duration of the fault is 0.02 seconds, the system returns to be in the balance eventually. In the Fig. 5. there is rotor angle of synchronous generator, active and reactive power presented. As it can be observed from the figures, the system is for the 0.02 seconds fault duration stable and the network for power of 93 MW generated from synchronous generator is adequate and secure for operation as the system after some period reaches equilibrium state. The dynamic response in terms of voltage profile is same as for 0.02 s which is shown is Fig.3., while in Fig. 6. dynamic response of rotor angle of synchronous generator, active as well as reactive power is shown when duration of fault is taken to be 0.05 s for the three-phase symmetrical fault simulation. As it can be seen from Fig. 5. when the fault occurs in the system on the any line, there is voltage drop as the fault occurs on the line, after which, for all lines except line 1, system is stable and able to reach new equilibrium. Voltage dynamic response is same as in Fig.3 when the fault occurs in the system on line 1. There is the voltage drop where voltage drops to approximately zero for longer period than it was case on all other lines, and it will oscillate in the range from value slightly higher than 0 p.u. to approximately 0.35 p.u., with no signs that it will eventually come to the state of balance. However, observing the dynamic response of rotor angle, active and reactive power for the line 1 from Fig.7. for 0.05 s fault duration, the system is unstable to adequately operate since it is unable to attain equilibrium state again. In the Fig. 8. and Fig. 9. after the RMS simulation is done, the results obtained show that in terms of voltage development seen from the Fig. 8., at the time of fault occurrence there appears the voltage drop where the system goes back to the balanced state eventually. In the Fig. 9. the system response of rotor angle of synchronous generator, active and reactive power show that the system for the 0.5 seconds fault duration is stable and the network for power of 93 MW generated from synchronous generator is adequate and secure for operation in case for all analyzed lines except for line 2. Considering case when fault simulated on line 2 for 0.5 s, the dynamic response of voltage development, rotor angle, active and reactive power is similar as response in Fig. 8. while voltage dynamic response is shown in Fig. 10. There is a major voltage drop in the system which is the consequence of the fault that occurred on the line 2. The voltage, after it drops to value slightly higher than zero, is oscillating from that value to approximately 0.35 p.u. Since, also, all other �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020217 parameters continued to oscillate equally for all 10 seconds and t will not came back to the balanced state, thus, the system is denoted as unstable in terms of all parameters examined. Fig. 4. Dynamic response for 0.02 s fault duration on line 2 – Voltage Fig. 5. Dynamic response for 0.02 s fault duration on line 2 – Rotor Angle (blue), Active (purple) and Reactive Power (green) Fig. 6. Dynamic response for 0.05 s fault duration on lines – Rotor Angle (blue), Active (purple) and Reactive Power (green) In the Fig. 11. the results obtained from the three-phase symmetrical fault analysis when duration of fault is taken to be 5 seconds occurring on the line 2 is shown in terms of voltage profile and in Fig. 12. rotor angle response is shown. Since the duration of the fault on lines is taken to be 5 seconds, which represents too long period for a fault, it can be observed that there is the breakdown of the system in terms of rotor angle where the dynamic response is infinitely oscillating where the speed of the rotation is increasing causing system to �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020217 be out of balance. There is with the voltage drop at the time the fault occurs there is rise in the angle of rotor which starts to excessively rotate, and drop in active power to the respect of reactive power rise. At the time there is fault on the line 2 it can be observed that all analyzed parameters are oscillating in the smaller range, while at approximately 6th second, when the duration of the fault is over, there are greater oscillations where the system is unable to reach the equilibrium state and, instead, and reaches the state of complete breakdown. Fig. 7. Dynamic response for 0.05 s fault duration on line 1 – Rotor Angle (blue), Active (purple) and Reactive Power (green) Fig. 8. Dynamic response for 0.5 s fault duration on lines – Voltage Fig. 9. Dynamic response for 0.5 s fault duration on lines – Rotor Angle (blue), Active (purple) and Reactive Power (green) �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020217 Fig. 10. Dynamic response for 0.5 s fault duration on line 2 –Voltage Fig. 11. Dynamic response for 5 s fault duration on lines – Voltage Fig. 12. Dynamic response for 5 s fault duration on lines – Rotor Angle D. Voltage Control by Power Factor Correction for N-1 Criterion In the Table III. The results of voltage development on the BB11 busbar are presented when the power factor of the synchronous generator is varied. As the generator is operated under different power factor, there is a change in the active and reactive power production in order to maintain voltage within limits set by EN �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020217 50160 standards. The results obtained show how the voltage is regulated by power factor correction as the in the case of 0.8 capacitive power factor voltage magnitude for 93 MW falls below allowed limits, and new maximum power is determined to be 45 MW. As in the case of 0.8 inductive power factor the voltage goes beyond upper allowed limit in case when power production of 93 MW, and the new maximum power for stable operation is found to be 74 MW. In cases when power factor is 0.9 in both capacitive and inductive mode, the voltage on the critical busbar, as well in the entire network, stays within allowed limits and does not change significantly for both power of 93 MW and new found power. It can be then concluded that if the generator operates under power factor of 0.8 in both modes, there is less active power produced, while if it operates under power factor of 0.9 in both modes, as well as under power factor of 1, the maximum power of 93 MW previously determined satisfy N-1 criterion and offers stable and secure network operation. Considering results obtained and presented in Table IV., in terms of line and transformer loading, for power of 93 MW any power factor in either capacitive or inductive mode less than unity, the power of 93 MW will distort the network operation and stability. Thus, it can be concluded that considering only voltage constraints the system will be stable for power factor of 0.9 capacitive and inductive, while when line and transformer loading taken into consideration, there is all cases when power factor less than 1 new maximum power for unstable and unsecure network operation. Table 3. Voltage developments for different power factor Power factor BB11 Line 2 0.8 (45 MW) Line 2 0.8 (83 MW) Line 2 0.8 (74 MW) Line 2 0.8 (93MW) Line 2 0.9 (73MW) Line 2 0.9 (93MW) Line 2 0.9 (89MW) Line 2 0.9 (93MW) Line 2 1 (93MW) CAP CAP IND IND CAP CAP IND IND IND UI, Magnitude MV 59,59856 55,44239 72,79612 75,16263 60,93922 60,2638 72,12859 72,52091 67,06188 u, Magnitude p.u. U, Angle deg 0,903006 0,840036 1,102971 1,138828 0,923322 0,913088 1,092857 1,098802 1,016089 3,5407772 13,12576 1,038122 2,164138 7,032856 10,3019 3,275636 3,567566 6,509941 Table 4. Line and transformer loading for different power factor Power Factor CAP CAP IND IND CAP CAP IND IND IND 4. Line 2 0.8 Line 2 0.8 Line 2 0.8 Line 2 0.8 Line 2 0.9 Line 2 0.9 Line 2 0.9 Line 2 0.9 Line 2 1 Power 45MW 93MW 74MW 93MW 73MW 93MW 89MW 93MW 93MW Loading [%] line 2/1 40,80236 167,4764 92,47962 116,5894 98,69827 131,5861 99,38897 104,098 99,53208 Loading [%] Twowinding transformer 74,93822 123,1931 87,84803 98,82892 93,07358 109,3657 93,99311 96,17869 96,96105 Conclusion Voltage stability is the main problem concerning utilities due to the continuous growth and deregulation. In this paper, the network with 11 busbars is examined for a transient stability. Transient stability studies deal �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020217 with the effects of large and sudden disturbances that occurs within the network such as it is a fault, the sudden outage of a line or the sudden removal or application of load. It is very important to do the transient stability analysis of a system in order to ensure that the system can handle the transient condition which is followed by a major disturbance. Transient stability and voltage instability analysis done in this research for the network with high load conditions shows that for a smaller period of fault duration, the system can be denoted as stable, while in case when the fault duration is somewhat higher than 0.02 seconds, the system is unstable and not secure in operation being unable to attain the equilibrium state and synchronism considering all parameters analyzed – voltage development, rotor angle speed, active and reactive power. In cases when fault duration greater than 0.02 seconds, there is breakdown state appearing in the network after the fault where the rotor speed is increasing, thus, causing system to go unstable and out of synchronism. Also, during the fault, there is voltage drop, active power drop and reactive power rise, after which there is an oscillation which cannot reach equilibrium. When fault duration increased to 0.05 or 0.5 seconds, the system is unstable only when fault simulated on one line, while when fault duration is increased to 5 seconds, then for every line examined and analyzed for three-phase symmetrical fault, the system is unstable. REFERENCES [1] Kundur, P. (1994) Power System Stability and Control. USA: McGraw-Hill, Inc. [2] Sucena P., J. P. (2007) Redes de Energia Eléctrica: uma análise sistémica. 2ª edição. Lisboa, IST Press. [3] Mania P. (1997) Power System Stability and Control Comparative Analysis. IFAC Control of Industrial Systems, Belfort, France. [4] Lau, Mark A. and Kuruganty, Sastry P. (2010) "A Spreadsheet Illustration of the Transient Stability Analysis of Power Systems," Spreadsheets in Education (eJSiE): Vol. 3: Iss. 3, Article 6. Available at: http://epublications.bond.edu.au/ejsie/vol3/iss3/6 [5] Saric, M., & Penava, I. (2014, May). Transient stability of induction generators in wind farm applications. In 2014 14th International Conference on Environment and Electrical Engineering (pp. 230-235). IEEE. [6] Davidson I. and Mbangula I. (2014) Power System Modelling and Fault Analysis of NamPower’s 330 kV HVAC Transmission Line. Journal of Energy and Power Engineering 8 (pp. 1432-1442). [7] Xyngi I., Ishchenko A, Popov M., and van der Sluis L. (2009) Transient Stability Analysis of a Distribution Network With Distributed Generators. IEEE Transactions on Power Systems, vol. 24, no. 2. [8] Diaz-Alzate, A. F., Candelo-Becerra, J. E., & Villa Sierra, J. F. (2019). Transient Stability Prediction for Real-Time Operation by Thresholds. Energies, 12(5), 838. Monitoring the Relative Angle with Predefined � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal of Natural Sciences and Engineering Identifier An unambiguous reference to the resource within a given context 2637-2835 DOI Digital object identifier 10.14706 Publisher An entity responsible for making the resource available International Burch University Description An account of the resource Journal of Natural Sciences and Engineering (JONSAE) is a peer-reviewed, biannually published international journal focusing on empirical and theoretical research in all branches of Engineering and Natural Sciences. It is published on the behalf of Faculty of Engineering and Natural Sciences of International Burch University and aims to provide the best content regarding by publishing original research papers, review articles, special issues, feature articles, and book reviews. All manuscript submissions are subject to initial appraisal by the Editor, and, if found suitable for further consideration, to peer review by independent, anonymous referees. All peer review is double-blind and submission is online. The journal welcomes theoretical, applied, interdisciplinary and methodological work, with preference on empirical research, critical approach and problem-solving methods in manuscripts. Language A language of the resource English Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Analysis of Transient and Voltage Stability of an 11-Busbar Testing System Author Author Alma Halilović, Mirza Šarić Abstract A summary of the resource. A comprehensive treatment from the physical and mathematical perspective supply modelling, analysis, control and covers a range of topics including modelling, computation of load flow in the transmission grid, stability analysis of the transient state. It is widely accepted that transient stability is an important aspect in designing and upgrading electric power system. In utility planning, transient stability is studied by numerical simulation. It involves the study of the power system following a major disturbance. In order to study Electric Power System transient stability, the models to describe their components should be defined. The components are defined using the classical model, which is valid to time periods up to 2 seconds. This project contains 11 busbars, 1 synchronous generator, 3 loads and 8 transformers. This research is done in DIgSILENT PowerFactory software for network modeling and simulation by using Stability Analysis Functions (RMS) advanced feature. In this paper we are analyses the maximum rated power of distributed generation (DG) considering only the terms of voltage limit constraints, the N-1 operational criterion analysis and three-phase symmetrical fault analysis for N-1 criterion is examined. Keywords Keywords. high load, n-1 criterion, synchronous generator, transient stability analysis Identifier An unambiguous reference to the resource within a given context 2637-2835 Publisher An entity responsible for making the resource available International Burch University, Sarajevo, Bosnia and Herzegovina Source A related resource from which the described resource is derived Journal of Natural Sciences and Engineering Date A point or period of time associated with an event in the lifecycle of the resource January, 2020 https://eprints.ibu.edu.ba/files/original/b07ea9e57cba6ae337bfd4515469085d.pdf 1aead1a15145473c159b69bbe91031a6 PDF Text Text Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020213 Biometrics Based Access Control System Mujo Hadžimehanović1, Dino Kečo1, Demir Korać1 1 International Burch University, Sarajevo, Bosnia and Herzegovina mujo.hadzimehanovic@stu.ibu.edu.ba dino.keco@ibu.edu.ba demir.korac@stu.ibu.edu.ba Abstract – Access control includes attendance checking and intrusion prevention. It is used to protect property, employees and other assets of a company or institution. Since attendance checking and intrusion detection are important segments of many educational institutions and other businesses as well, it is important to make these processes faster, easier and as convenient as possible. Lots of institutions are suffering from unreliable attendance checking methods, so we have decided to use biometrics, more precisely face recognition to automate and improve this overall process. As part of this study the full system has been implemented for recognition of people. As an example of usage in an educational institutions multiple photos will be recorded during the class session, so that in case of students leave class after the first shot, they will be removed from the attendance sheet. All recognized people will be stored in Mongo database as an array of features and later read from database and processed by using Python script for face recognition. All educational institutions are going to have benefits from this study. Benefits would be improving attendance management and security. Keywords - attendance, face, images, recognition 1. Introduction Technology is rapidly improving nowadays and everyday activities are adopting these improvements. Point is to automate these activities and not to lose time performing them. Attendance is a really important part in most organizations such as schools, faculties, companies etc. Today, attendance is performed in various ways. Best way to do it is biometrics. Biometrics is a bioengineering area which is an automated method for person recognition based on its physiological or behavioural characteristics. There are many biometric templates such as fingerprints, face, hand geometry, iris, voice or signature. System is going to use face biometric template because it is the fastest approach and requires no human intervention. This method is better than other biometric methods because these methods are time consuming. There are also lots of systems which are using RFID cards, location based attendance tracking systems, signature based etc. Negative things about these methods are that they can be faked. In RFID and location based systems employees are carrying RFID cards or GPS locators. So, other people can check instead of other employees. There are two main stages of face recognition process and they are face detection and face identification [1]. Recording employees' work hours and their activities, attendance of students in schools are really important components of every company or school. This process is maintained by using signature, fingerprint, iris, RFID or face recognition. System is going to use a camera which captures images of people entering the company or school building. Detected faces will be compared with pictures which are already in the database. If a person's picture is in the database attendance �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020213 will be checked automatically. Otherwise, the security system is going to be informed that an unrecognized person entered the building. So, this system can also be used as an intrusion detection system. 2. Literature Review Following section contains a presentation of all related work and their methods. Since they have large-scale data with massive noisy labels, X. Wu, R. He, Z. Sun, and T. Tan used a Light CNN framework [2]. Their Light CNN architecture contains Max-Feature-Map to suppress low activation neurons in all layers. Their model was trained on Celeb-1M dataset. In order to handle noisy labeled images, they proposed a semantic bootstrapping method to automatically re-label training data via pre-trained deep networks. For training purposes they used five types of databases. First type is commonly used Labeled Faces in the Wild which consists of ~13,250 images of ~5,750 people. At VR@FAR=0 for Light CNN-29, they achieved 97.50%, while results from all other methods were lower than 70%. Next type of the database are collections of images extracted from Youtube videos which contain YouTube Celebrities (YTC) and Celebrity1000 database. Precision achieved for these datasets is 94.18%. Third type are MegaFace, IJB-A and IJB-B datasets which are challenging and they got 85.13% precision. Cross-domain databases are the fourth type of database. It includes CACD - VS, Multi - PIE and the CASIA NIR - VIS 2.0 database. They achieved 98.55% on CACD, 95.0% on Multi-PIE and on CASIA VR@FAR=0.1% result is further improved from 94.03% to 94.77%. M. Arsenovic, S. Sladojevic, A. Anderla, and D. Stefanovic use Convolutional Neural Networks (CNNs) cascade to detect faces and CNN to generate embeddings of each face [3]. Fact is the best results for larger datasets are achieved by using CNNs, but in their production environment that was not the case. CNN gave the best results for smaller datasets. Accuracy of 95.02% was achieved on a dataset created by authors in the realtime environment. Five employees of the company took pictures of themselves and they used these pictures as a dataset. Model was trained with these 5 pictures. Active annotation and learning framework was used by H. Ye et al [4]. They are starting with face image training set without labels and train a deep neural network iteratively model created was used to choose examples for further manual annotation. After following active learning strategy, Value of Information criterion is derived to actively select candidate annotation images. This model reaches the coverage of 70.7% with a precision of 95%. MSR Image Recognition Challenge by J. Li et al introduces a knowledge base which has an idea to assign each face unique entity key and provide large dataset consisting of about 100,000 famous persons with around 100 images per person (MsCeleb) [5]. Method achieved coverage of 46.1% at 95% precision on the random dataset and 33% at 95% precision on the hard set of their challenge. Authors proposed a method consisting of two stages to learn robust human face representations for effective recognition of human faces. First stage in the training set is cleaning the noisy data because dataset is taken from the internet so images without faces can appear. In order to do so, a deep neural network was trained on existing dataset. �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020213 S. Chintalapati and M. V. Raghunadh used SVM and Bayesian classifier for automated attendance system based on face detection and recognition [6]. They proved that these classifiers are better when compared to other distance classifiers. This system automatically detects the student which enters the classroom and marks the attendance if recognizes him. One of the failures of the system is recognizing faces only up to 30 degrees angle variations. 3. Methods and Materials Dataset to be used is Labeled Faces in the Wild [7] which is a database of face photographs designed for studying the problem of unconstrained face recognition. It contains more than 13,000 pictures collected from the web. Each image has been labeled with the name of the person on it. There are 1680 different persons in images. Fig.1 shows samples from LFW dataset. Fig.1. Samples from dataset These images need to be processed in order to get numerical representation of faces which is called feature vector. Feature vector consists of various numbers in a specific order which can be: height or width of face, width of lips, nose height etc… Final output of processed image needs to be an array with features which is shown in Fig.2. All features are stored in the mongo database for speed improvement. Python script iterates in a folder which has dataset images and stores one by one in a database with image name and features. Face Recognition library with deep learning is going to be used for this project. Deep learning model has an accuracy of 99.38% on Labeled Faces in Wild dataset. Features of face recognition library are finding faces in pictures, finding facial features in pictures and identifying faces in pictures. Once installed face recognition gives us two command line programs: ● face_recognition - recognize face on image ● face_detection - detect face in image Face recognition process consists of two stages. This includes taking and preparing training dataset and integration into existing system. For testing purposes, data was collected at the university. These are images of students which were taken in the first year. Images are preprocessed and inserted into the mongo database by �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020213 using python script for inserting images. After insertion, facebook images of the same people were taken and tested by using python script for face recognition. Fig.2. Array of features 3.1 Data preprocessing Implemented system is going to use monitoring cameras at the entrance. It means that we could have some kind of network or other problems and taken images could be blurry, so we have to include such images in training dataset, Fig.3. Persons entering the building can be photographed from different angles, so these kind of photos should be included also in training dataset, Fig 4. �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020213 Fig.3. Original and Blurred image Fig.3 shows an example of original and blurred images. If we have perfect conditions we would have a picture like the original one, but if the system experiences network issues we might have a blurry image like the one represented. System has to be ready to respond accordingly to these kinds of issues. Python script was written using OpenCV [8] interface to generate blurry images out of the original ones. Fig.4. Image from front and side In Fig.5 we can see facial features drawn on picture of Pep Guardiola. Most important features are shown: eyes, nose, mouth and chin location. These features are used when recognizing people on images. Face recognition library contains script face_landmarks for detecting facial landmarks and positioning the face based on them. Fig.5. Facial features �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020213 3.2 Usage Workflow Application usage workflow is represented on Fig.6. Images need to be collected into a single folder, so that insertion helper scripts can be run. For multiple insertions we need to pass a folder of images to script, which iterates through these images, creates encodings and inserts them into database. Single insertion script accepts an image as a parameter, encodes it and inserts into a database. Last step is recognizing images, the script accepts an image which needs to be recognized and iterates through mongoDB collection and looks for matching images. Fig.6. Usage workflow 3.3 Face Recognition Library Face recognition library which we are using is built using dlib’s face recognition with deep learning. We can install library by using a python package installer. Once installed we are provided with two command-line programs : face_recognition and face_detection. Face recognition recognizes faces in a photograph or in a folder of photos. There should be two folders, one containing known people and second which contains photos of people which we want to recognize. Face recognition program is run with two parameters which are the names of these folders. Face detection program finds pixel coordinates of faces. It takes a folder with images as parameter and at the end prints one line for each face that was detected. There is also an option to speed up the overall process by doing a recognition with multiple CPU cores. For example if we have 8 core CPU, we can process 8 times as many images in the same amount of time. Dlib is a toolkit written in C++ and contains ML algorithms and tools for solving real world problems. The most important thing is that dlib is an open source library which enables anyone to use it anywhere, free of any charge. Some of the dlib’s features are Deep Learning, Multiclass SVM, Image Processing etc.. Our library uses Image Processing tool for face recognition built by using deep learning tools from dlib. �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020213 3.4 Helper Scripts There are multiple helper scripts which enable user to insert multiple or single image into database and recognize faces. The most important parts of scripts are represented in the following lines. insertMultiple.py for image in images: current_image = face_recognition.load_image_file("images/" + image) encodings = face_recognition.face_encodings(current_image) if len(encodings) > 0: current_image_encoded = encodings[0] num_of_images+=1 else: print("No faces found in the image " + image) num_of_not_found+=1 continue mydict = { "image": image, "encoding": current_image_encoded.tolist() } x = mycol.insert_one(mydict) print(image + " inserted") Code snippet above loads images from the folder, encodes them and inserts them into mongoDB. We have to provide the name of the folder which contains images and simply run the script. �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020213 faceRecognition.py unknown_image = face_recognition.load_image_file("image.jpg") unknown_face_encoding = face_recognition.face_encodings(unknown_image)[0] known_faces = [] names = [] for x in mycol.find(): known_faces.append(x['encoding']) names.append(x['image']) results = face_recognition.compare_faces(known_faces, unknown_face_encoding) for x in range(len(known_faces)): if results[x] == True: print("Recognized: " + names[x]) else: print("Failed: " + names[x]) Code represented above does face recognition. It takes an image of the person which we want to recognize, encodes it, loops through face encodings from the database and checks if a person exists in the database. 4. Results By using a custom dataset which was collected from our university. Students' images were taken and tested on created scripts. From these tests we have obtained accuracy of 90.9% when testing on images found on Facebook. There were some problems when recognizing people from different angles, but this can be material for further study. Images of people are not shown because they did not agree to publish their images. Since face_recognition python library has a pre-trained model there is no need for additional training. Improvement is that all images are inserted in mongoDB with image name and face encodings array. Fig.5 shows one part of mongoDB record. Python script for inserting images in mongoDB is written and it takes a folder with images and inserts one by one in the database. In our testing environment LFW dataset is used and all images are collected into a single folder. Number of images inserted in the database is 4014. There are also images on which faces are not recognized. Unrecognized images number is 21. So, if we take into consideration that 4014 images are inserted and 21 are unrecognized which means that more than 99% images were recognized. Example of such an image is shown in Fig.6. Execution time of the script is about 35 minutes for LFW Dataset. Final result of this research would be access control application. Application can be installed on Raspberry Pi which has a camera installed. All assets that are necessary for access control application to be fully functional can be installed on Raspberry. These are mongoDB, python and python libraries. Overall process is not so challenging, so that we do not need anything better than Raspberry Pi 3 B+ which is a model that we used while testing the application. �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020213 5. Conclusion The aim of this study was to make the attendance checking process a lot easier for companies and schools by using biometrics. Every employee or student would be recorded by camera at the entrance and recorded in the system. For educational institutions cameras will be installed in classrooms so that the system can make multiple shots during lessons. This research was successful because it made the recognition process faster by using a document based database which is really fast. This study will bring benefits for multiple groups. Benefit for schools is easier attendance recording and reducing waste of time at the beginning of the classes. Also students will not have a chance to avoid coming to classes because this system will not allow them to cheat. Similar benefit is for companies to track their employees coming and leaving time. Future research suggestions in this field are solving problems if a person is recorded from the side and possibly getting blurry images because of internet connection issues. REFERENCES [1] B. T. Liyew and P. Hazari, “A Survey on Face Recognition based Students Attendance System.” [2] X. Wu, R. He, Z. Sun, and T. Tan, “A Light CNN for Deep Face Representation With Noisy Labels,” IEEE Transactions on Information Forensics and Security, vol. 13, no. 11. pp. 2884–2896, 2018, doi: 10.1109/tifs.2018.2833032. [3] M. Arsenovic, S. Sladojevic, A. Anderla, and D. Stefanovic, “FaceTime — Deep learning based face recognition attendance system,” 2017 IEEE 15th International Symposium on Intelligent Systems and Informatics (SISY). 2017, doi: 10.1109/sisy.2017.8080587. [4] H. Ye et al., “Face Recognition via Active Annotation and Learning,” Proceedings of the 2016 ACM on Multimedia Conference - MM ’16. 2016, doi: 10.1145/2964284.2984059. [5] J. Li et al., “Robust Face Recognition with Deep Multi-View Representation Learning,” Proceedings of the 2016 ACM on Multimedia Conference - MM ’16. 2016, doi: 10.1145/2964284.2984061. [6] S. Chintalapati and M. V. Raghunadh, “Automated attendance management system based on face recognition algorithms,” 2013 IEEE International Conference on Computational Intelligence and Computing Research. 2013, doi: 10.1109/iccic.2013.6724266. [7] “LFW Face Database : Main.” [Online]. Available: http://vis-www.cs.umass.edu/lfw/. [Accessed: 19-Jan-2019]. [8] “OpenCV library.” [Online]. Available: https://opencv.org/. [Accessed: 09-Jan-2019]. � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal of Natural Sciences and Engineering Identifier An unambiguous reference to the resource within a given context 2637-2835 DOI Digital object identifier 10.14706 Publisher An entity responsible for making the resource available International Burch University Description An account of the resource Journal of Natural Sciences and Engineering (JONSAE) is a peer-reviewed, biannually published international journal focusing on empirical and theoretical research in all branches of Engineering and Natural Sciences. It is published on the behalf of Faculty of Engineering and Natural Sciences of International Burch University and aims to provide the best content regarding by publishing original research papers, review articles, special issues, feature articles, and book reviews. All manuscript submissions are subject to initial appraisal by the Editor, and, if found suitable for further consideration, to peer review by independent, anonymous referees. All peer review is double-blind and submission is online. The journal welcomes theoretical, applied, interdisciplinary and methodological work, with preference on empirical research, critical approach and problem-solving methods in manuscripts. Language A language of the resource English Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Biometrics Based Access Control System Author Author Mujo Hadžimehanović, ​Dino Kečo,​ ​Demir Korać​ Abstract A summary of the resource. ​Access control includes attendance checking and intrusion prevention. It is used to protect property, employees and other assets of a company or institution. Since attendance checking and intrusion detection are important segments of many educational institutions and other businesses as well, it is important to make these processes faster, easier and as convenient as possible. Lots of institutions are suffering from unreliable attendance checking methods, so we have decided to use biometrics, more precisely face recognition to automate and improve this overall process. As part of this study the full system has been implemented for recognition of people. As an example of usage in an educational institutions multiple photos will be recorded during the class session, so that in case of students leave class after the first shot, they will be removed from attendance sheet. All recognized people will be stored in Mongo database as an array of features and later read from database and processed by using Python script for face recognition. All educational institutions are going to have benefits from this study. Benefits would be improving attendance management and security. Keywords Keywords. Keywords - attendance, face, images, recognition Identifier An unambiguous reference to the resource within a given context 2637-2835 Publisher An entity responsible for making the resource available International Burch University, Sarajevo, Bosnia and Herzegovina Source A related resource from which the described resource is derived Journal of Natural Sciences and Engineering Date A point or period of time associated with an event in the lifecycle of the resource January, 2020 https://eprints.ibu.edu.ba/files/original/d98c62dc674b330134eb6d0d5eec8c89.docx b7b81d52bcb066ce1b2d555ea001830b Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal of Natural Sciences and Engineering Identifier An unambiguous reference to the resource within a given context 2637-2835 DOI Digital object identifier 10.14706 Publisher An entity responsible for making the resource available International Burch University Description An account of the resource Journal of Natural Sciences and Engineering (JONSAE) is a peer-reviewed, biannually published international journal focusing on empirical and theoretical research in all branches of Engineering and Natural Sciences. It is published on the behalf of Faculty of Engineering and Natural Sciences of International Burch University and aims to provide the best content regarding by publishing original research papers, review articles, special issues, feature articles, and book reviews. All manuscript submissions are subject to initial appraisal by the Editor, and, if found suitable for further consideration, to peer review by independent, anonymous referees. All peer review is double-blind and submission is online. The journal welcomes theoretical, applied, interdisciplinary and methodological work, with preference on empirical research, critical approach and problem-solving methods in manuscripts. Language A language of the resource English Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Communication in Smart Homes with Emphasis wn Power Line Communication Author Author Ina Salihović Esma Musić Dejan Jokić Abstract A summary of the resource. Abstract: Power Line Communication (PLC) is a technology that allows consumers to use the already existing wiring infrastructure to exchange information. This paper overviews narrowband PLC in home automation, starting from the basics of power line communication and its advantages compared to wired and Wi-Fi automation systems, data modulation techniques, noise problems, frequency bands, all the way to regulations affecting PLC. The paper is finished off with an overview of three System on Chip (SoC) power line modems from a few different generations, Yitran’s IT800D from 2005, ON Semiconductor’s NCN49597 from 2012, and STMicroelectronics’s ST8500 from 2017. Keywords Keywords. Keywords: Power Line Communication, narrowband PLC, PLC modem, System on Chip Publisher An entity responsible for making the resource available International Burch University Source A related resource from which the described resource is derived Journal of Natural Sciences and Engineering https://eprints.ibu.edu.ba/files/original/fff93c2fec19e46968acdfcfd9b40033.pdf 44a32890c2f4fb1b9bf05cdfdc013750 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal of Natural Sciences and Engineering Identifier An unambiguous reference to the resource within a given context 2637-2835 DOI Digital object identifier 10.14706 Publisher An entity responsible for making the resource available International Burch University Description An account of the resource Journal of Natural Sciences and Engineering (JONSAE) is a peer-reviewed, biannually published international journal focusing on empirical and theoretical research in all branches of Engineering and Natural Sciences. It is published on the behalf of Faculty of Engineering and Natural Sciences of International Burch University and aims to provide the best content regarding by publishing original research papers, review articles, special issues, feature articles, and book reviews. All manuscript submissions are subject to initial appraisal by the Editor, and, if found suitable for further consideration, to peer review by independent, anonymous referees. All peer review is double-blind and submission is online. The journal welcomes theoretical, applied, interdisciplinary and methodological work, with preference on empirical research, critical approach and problem-solving methods in manuscripts. Language A language of the resource English Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Comparison Test of Sensitivity Between Next Generation Sequencing (NGS) Hotspot Panel and Droplet Digital PCR of KRAS G12 / G13 Mutation Author Author Azra Hajdarevic, LanaSalihefendic, RijadKonjhodzic, Adis Kandic, Ivana Ceko, DinoPecar, Muhamed Curic, Amina Kurtovic – Kozaric Abstract A summary of the resource. Cancer is an abnormal proliferation of cells that is characterized by the presence of genomic alterations including DNA mutations, deletions, insertions, translocations, inversions, and others. KRAS gene is one of the most mutated genes across different cancer types. The most common mutations in KRAS are found in codons 12 and 13 of KRAS protein, which are associated with a lack of response to anti- epidermal growth factor receptor (EGFR) antibody therapy. This study assessed and compared the performance between two diagnostic methods: droplet digital PCR (ddPCR) and next generation sequencing (NGS). The main goal was to determine KRAS G12 / G13 mutant allele fraction using NGS and to compare the accuracy toddPCR. A total of 28 samples of non – small cell lung cancer (NSCLC) and colorectal cancer (CRC) were analyzed using ddPCR and NGS methods. Our results show that even though both methods exhibited high rate of concordance and correlation, the study proved that ddPCR is more superior when it comes to detecting low frequency mutations. Even though strong correlation was observed, based on the values obtained, we concluded that ddPCR is more accurate, reliable, and sensitive in comparison with NGS. Keywords Keywords. ddPCR, KRAS mutation, NGS. Identifier An unambiguous reference to the resource within a given context ISSN 2637-2835 (Print) DOI Digital object identifier 10.14706/JONSAE2022413 Publisher An entity responsible for making the resource available International Burch University Type The nature or genre of the resource Original research https://eprints.ibu.edu.ba/files/original/4185b962c7b2e1090b65243b0dbbab63.pdf c9e429afa68c8df8f76a72e2686eb35b PDF Text Text Journal of Natural Sciences and Engineering, Vol. 2, No.2 (2020) DOI number: 10.14706/JONSAE2021311 Contemporary housing trends in Sarajevo Emina Mehic1 1-International Burch University, Sarajevo, Bosnia and Herzegovina emina.mehic@stu.ibu.edu.ba Abstract – Within the last 20 years, there has been witnessed a significant increase of the urban population of Sarajevo, as a result of economic and social migrations. Consequently, this has caused an increasing demand for new housing which is mainly profit-oriented without any beneficial social, environmental or cultural implication. Primary objective of this research is to analyze the current situation and to assess the quality of the buildings not only as a housing solution, but as a complex that unites the community who inhabits it. This research will be conducted in a qualitative manner in analysis and statistical approach over the data related to the urbanization, building standards and positive effects of the building. Newly built parts of settlements Otoka and Stup will be used as case studies, since these parts of the city are most influenced by the mass production of the new housing solutions. This paper stresses out the correlation between high demand for the new housing and decreased quality of the housing without respecting minimum spatial and environmental standards, without basic amenities, social infrastructure and recreational and cultural activities. There is a need for improvements in contemporary housing design that will reflect with positive impacts on social, environmental, economic and cultural aspects of urban living. Keywords - Contemporary housing trends, qualitative analysis, Otoka, Stup 1. Introduction City of Sarajevo is becoming a large construction site, meaning that more and more residential buildings and buildings in general are being built. For the past couple of years, the fast appearance of the entire residential settlements is noticeable. The parts of the city that are affected the most are Otoka and Stup. One of the most characteristic housing solutions are definitely residential settlements called Stup Nukleus, a newly built residential and business complex in Stup, municipality of Ilidža and Nova Otoka in Otoka, municipality of Novi Grad. With the urbanization of the capital city of Sarajevo extending rapidly. It is not a surprising phenomenon that more and more investors are seeking an opportunity for profit. In order to realize why the interest is so high in these specific parts of the city, history and urban plans for Sarajevo will give us a more precise point of view. Otoka is a settlement in the capital city of Bosnia and Herzegovina, Sarajevo, located in municipality Novi Grad. Otoka is closely coupled with the following: Buća Potok (North side), Čengić vila (East side), �Journal of Natural Sciences and Engineering, Vol. 2, No.2 (2020) DOI number: 10.14706/JONSAE2021311 Aneks (South-East side), Švrakino Selo (South side). Its residential core represents a chain of high-rise buildings (Streets: Žrtava Fašizma, Brčanska, Aleja Lipa). [2] The majority of residential buildings built in this part of the city was built by the government in early 70s when Otoka was considered one of the most prominent, modern and cleanest parts of the Sarajevo suburbia. The residential design of this part of the city was also advanced considering the other buildings. As shown on Figure 1, These were built during socialist regime, since significant attention was paid to environmental aspects of the settlement. There were designated areas for parks, elementary schools, preschools and shopping. [1] Originally residential settlements were built on the left side of Miljacka river, which before the 70's was mainly empty fields. Accordingly, there were no plans for extensive construction on the other side of the river, since the idea was to maintain Otoka Meandar as the green “lungs” of the city containing recreational areas and walking paths. The area to the North between two major traffic axis – Bulevar Meše Selimovića and Džemala Bijedića street were treated as industrial site. After the 1990’s war new buildings were erected in the Meandar area. “Stadium Otoka” was built in 1993 and it was additionally upgraded and renovated in 2011. “Istiklal Mosque” was also built in 2001, beside these two, Vistafon multipurpose hall and Olympic pool – two large scale projects were built in this period. Even though these are mainly sport and recreational buildings that provide social interaction and entertainment opportunities the green lungs of the city were seriously jeopardized. In the meantime, with the construction of the mentioned buildings industrial zones slowly started decaying and as the market needs and industry demand changed. The industrial companies that owned the area were destroyed in the shady privatization processes that followed the war. Industries that have survived the war and privatization, were allocated outside of the city. This created an opportunity to transform the entire industrial zone into residential settlement.[6] [7] �Journal of Natural Sciences and Engineering, Vol. 2, No.2 (2020) DOI number: 10.14706/JONSAE2021311 Examining urbanization plans we can conclude that the first residential zone was expected to be at maximum 6-8 floor height, but today we can see that the floor height almost doubled and we can notice 12-13 story buildings. The building blocks that we are examining now in Nova Otoka were initially planned with a maximum height of 21 meter, but with the change of the regulatory plan in 2017, their height increased to 42m. However, even though the height of the buildings was increased the distances or the number of the pertaining facilities remained the same. Another important issue is vehicular congestion that is happening on a daily basis in this part of the city, because Otoka as mentioned is the geographical center of the city. It is a connection point from the hill settlements and the valley, with tram connection and the main road. Furthermore, once the Otoka settlement was previously built vehicle traffic was directed with neighbourhood lanes planned in a ring style around the perplexing which added to more secure conditions generally and decreased the congestion. Stup, shown on Figure 3., is a settlement in the capital city of Bosnia and Herzegovina, Sarajevo, located in the municipality Ilidža. Geographically it is located in the western part of the city further from the city centre. It is encompassed by the river Miljacka on the South, and on the North by the river Dobrinja. Neighboring settlements are Briješće, Alipašin most, Alipašino Polje, Olimpijsko selo, Nedžarići, Zračna luka Butmir, Ilidža, Pejton, Otes and Azići. This part of the city was quite rural since it was considered on the outskirts of the city, so mainly low-rise, single family houses and industrial buildings were located in this area. These were mainly owner-occupied housing and there were now larger scale buildings. Once the regulatory plan was provided, Stup area was separated into zones. One of the zones - Stup Nukleus was designated as a residential settlement zone comprising recreational and green areas. However, there were multiple missteps during the implementation of the plan itself. The Institute for Development Planning of �Journal of Natural Sciences and Engineering, Vol. 2, No.2 (2020) DOI number: 10.14706/JONSAE2021311 Sarajevo Canton hasn’t specifically stated the dimensions of the single buildings, but rather provided zones for approved buildings with pertaining area coverages and building indexes. On the other hand, the developer chose to ignore the regulations and building indexes and built the entire buildable area. This has 8caused very high building density, for instance we have several cases of 6-meter distance between two 13 story buildings. Regarding the historical narrative of Stup Nukleus the site in 1992 was owned by a farming cooperative. After the war, the area became privately owned. Construction of the Stup Nucleus residential settlement began in 2011. The Municipality of Ilidža drafted a Study on the socio-economic justification for the establishment of a public institution in the Stup II settlement in November 2017, which plans for the construction of the school to begin this year, but it never happened. The closest school to this settlement is currently Aleksa Santic Elementary School, located in the Aerodromskom naselju, which is more than one kilometer away, and access to it is very dangerous because of the frequent traffic, especially for younger children. Regarding the vehicular connection of Stup, it is connected to the main traffic axis- Džemala Bijedića street and it contains one of the biggest road loops that is connecting city to other magistral roads that are leading to Mostar, Zenica or Tuzla. With this being said, we can now incorporate the general characteristics of both settlements to create a detailed analysis of the new building construction trends and he future of building in the capital city of Sarajevo. [3] Figure 3. Stup in Yugoslavia, as spacious new settlement near to industrial zone [www.klix.ba] 2. Methodology The case study will show the quality, trends, potential problems and possible improvements for contemporary housing trends in Sarajevo. This will allow us to contain all necessary information that will be relevant for our research. The results will be used to give recommendations for the design of residential housing in the future. �Journal of Natural Sciences and Engineering, Vol. 2, No.2 (2020) DOI number: 10.14706/JONSAE2021311 3. Case study Urbanistic criteria: On Figure 4. below the regulatory plan of Stup Nukleus can be seen. Based on the urban typology and regulation plan proposed we will be able to bring up some conclusions and find relevant data that will affect the evaluation of the results. [9] Figure 4. Regulation plan of Stup Nukleus [Institute for Planning Development of Sarajevo Canton] Stup Nukleus was built in three separate phases and even though the majority of it was built during the first phase. The construction process started in 2001 and it consisted of 5 buildings with heights varying between 5 and 12 stories high. Smallest distance between these buildings is 6 meters and it is between the 10 story building and 7 story building which creates a big issue in terms of vistas, day light and extreme, almost inhuman density. [4] Buildings are taking around 7.471 m2 of the site area which is 20.245 m2. We can come to a conclusion that more than a third of the actual site is covered by the buildings. Furthermore, this brings us to the calculation of Urban Density Index (expressed through floor area ratio) which in this case equals 0,36902939. This is quite a lot taking into a consideration that buildings are over 10 stories high, creating the image of very high physical concentration and spatial congestion. �Journal of Natural Sciences and Engineering, Vol. 2, No.2 (2020) DOI number: 10.14706/JONSAE2021311 Figure 5. Regulation plan of Stup Nukleus in the first phase of development [Institute for Planning Development of Sarajevo Canton] The second phase, represented on the Figure 7., of Stup Nukleus development contained incredible amount of 11 buildings ranging from 6 to 13 floors high. The smallest distance between these buildings is 7,5 m. The total area covered by the buildings is 18. 455 m2 out of 51. 056 m2 of the total site area. The Urban Density Index (expressed through floor area ratio) for the second phase of Stup Nukleus is 0,3614658414 which is smaller than the first mentioned phase. [3] Figure 6. Regulation plan of Stup Nukleus in the second phase of development [Institute for Planning Development of Sarajevo Canton] �Journal of Natural Sciences and Engineering, Vol. 2, No.2 (2020) DOI number: 10.14706/JONSAE2021311 Figure 7. Completion of Stup Nucleus I [Tibra Pacifc] However, the situation on site is considerably worse than the first phase. Because the amount of extremely high buildings is much more pronounced than before and some parts of the site are simply incapable of receiving any daylight. There are also cases where the buildings are facing each other to extent of creating privacy issues. Figure 8. Construction of Stup Nucleus 2 in third phase of Stup Nucleus development [Tibra Pacific] The third phase contains similar situation like it is shown on regulatory plan bellow, it contains 4.508 m2. These one is still in development so it is hard to get the exact value for the UDI, it contains 3 buildings and 1the highest one is 9 floors high. �Journal of Natural Sciences and Engineering, Vol. 2, No.2 (2020) DOI number: 10.14706/JONSAE2021311 Figure 9. Regulation plan of Stup Nukleus in the third phase of development [Institute for Planning Development of Sarajevo Canton] On the other hand, when we talk about Nova Otoka we can notice 5 new buildings with two of them with the same height of 12 floors, which as mentioned before has doubled after the change of regulatory plan. The covered area of Nova Otoka is 10.601 m2 out of the total area of 26.930 m2, and one more building that is in further location, not in between these buildings has area of 2031 m2. [10] It is important to notice that the UDI in Nova Otoka is 0,3936502042. It is high, but there is a factory in between the buildings that is contains the rest of this field. This technically means that here the building density is almost close to ~ 0,86. For the general size of sit it is high and it takes large portion of space. Figure 10. Regulation plan of Otoka [Institute for Planning Development of Sarajevo Canton] �Journal of Natural Sciences and Engineering, Vol. 2, No.2 (2020) DOI number: 10.14706/JONSAE2021311 Environmental, social and cultural criteria: Based on the documentation and geographical analysis of the site, where Stup Nukleus is located we can conclude that there is no park in the close proximity of the complex, never the less there are no amenities for children or any similar project planned. The closest park that is intended for recreational and leisure purposes is 25 minutes walk from the complex and it is 1.9 km away. On the other hand, based on the analysis of Nova Otoka site we conclude that there is only one very small park within the complex, however the amenities for children are quite limited. Closest larger park that is intended for recreational and leisure purposes is 37 minutes walk from the complex and it is 3.3 km away. Considering the social aspects of the mentioned complexes we can notice a very bad trend of lack of care for the social interaction. It is important to mention the better position of Otoka compared to Stup that didn’t have any predispositions for social and cultural facilities, which Otoka inherited from socialist Yugoslav construction. After the careful examination of the site, we have concluded that Stup Nukleus has 5 privately owned coffee shops and 3 restaurants which based on the population and building density is not enough. [8] Beside these private commercial activities, there is no any sort of entertainment, recreational or cultural enforcing amenity in either one of the sites we are examining in this case study. [5] Architectural criteria: Stup Nukleus is commonly considered to be one of the worst complex built in Sarajevo in last two decades. The main issue we have discovered based on the interviews, was that the insufficient distance between buildings. [11] We will select the sample apartment from these buildings. The example that we used is the apartment with 2 bedrooms and has total of 58 m2. The selected type is the most common and the most repetitive type of the apartment in the entire complex. Regarding the layout and the dimensions of the rooms it is noticeable that from the lobby the living room with the kitchen and dining are accessible. The total area for these spaces is of 17,80 m2. From this space you can access the balcony 9,20 m2. To the left of the lobby there is a bathroom, area of 4,06 m2. The master bedroom is 14,37 m2 with access to the loggia. To the right of the front door is a pantry, area of 1,80 m2, while access to a smaller bedroom that has area 8,39 m2, from the living room. Some of these apartments are above the 7th floor. Which brings us to the next point and that is the disadvantages of Stup Nukleus buildings. This disadvantage is the insufficient amount of natural light. This issue is closely connected to the distance between buildings. The floors above the 7th floor, do have access to the natural light. Other parts are poorly designed and they get at most 3 hours of daylight. Looking upon the window to space ratio, we can notice that there is lack of windows throughout of the apartment, the rooms are small and they are really hard to fit any larger piece of furniture. As well on the floor plan you can see that the kitchen and bathroom are too small. Beside that, this apartment as you can see is facing the north side. This side is the side that gets the small amount of light in it. The issue is with �Journal of Natural Sciences and Engineering, Vol. 2, No.2 (2020) DOI number: 10.14706/JONSAE2021311 the air circulation from the kitchen to the only window in the left part of apartment that has to go through living and dining room. Figure 11. 58 m2 apartment in Stup Nucleus as average size apartment [www.olx.ba] On the other hand, as mentioned before, Nova otoka is also a project from the same construction company as Stup Nukleus complex and it is considered to be more contemporary and higher level than Stup. Since Nova Otoka was just recently completed, we were able to find more information about the technical execution of the construction and about building layout itself. This apartment is located on the west side of the complex and it is on 12th floor, meaning there is just one floor above it. [3] Further more As mentioned before Nova otoka is also a project from the same construction company as Stup Nukleus complex and it is considered to be more contemporary building than the previously mentioned building. Since Nova Otoka was just recently completed, we were able to find more information about the technical execution of the construction and about building it self. Floors facilities: two floors basement, ground floor and 12 residential floors. The basement floors are designed as parking spaces, ground floor contains offices, while the 12 floors above the ground floor are planned as housing units. The complex contains 12 floors, but the last 2 floors are two story penthouses. This complex apartment size varies from 32,49 m2 to 133,63 m2 where average area of the apartments is 65 m2. This apartment is located on first floor of 12 story building A. It is on South and facing the main road, which is very frequent and has high vehicle density during the day, especially the Otoka settlement due to the issues with traffic jams is know to be the start of the jams making vehicle concentration very high. �Journal of Natural Sciences and Engineering, Vol. 2, No.2 (2020) DOI number: 10.14706/JONSAE2021311 In order to make better comparison, we will select the similar size of the apartment from “Nova Otoka” complex, which has 57.16 m2. The apartment consists out of living room with connected kitchen and dining room with the total area of 22,64 m2. Master bedroom with area of 13,15 m2 is directly next to children bedroom: 7,10 m2 and within the lobby with area of 3,72 m2, across from the bedroom there is toilet with area of 4,24 m2 within the living room we can notice the balcony: 6,31 m2. Figure 12. 57 m2 apartment in Nova Otoka as average size apartment [www.olx.ba] Additionally, more significantly the shape, the rooms inside of the buildings are just not practical, because placing a bed in middle of the room, leaves around 70 cm of space that is accessible. This is a new practice and it proving to be bad and non-functional. Resident will always have a lack for space for wardrobes. 4. Conclusion Evaluating the situation and the data presented above, we can state that the analysis showed that most of these new complexes like the Stup Nukleus and Nova Otoka are built mainly for profit, without any concern for environmental, social or cultural benefits of such developments. There is lack of care for providing smart residential building solutions or on the other hand any basic social, recreational and cultural infrastructure resulting in inhuman, unsocial and quite hostile built environment without any sense of identity. A significant improvement can be done by adding areas like parks and playgrounds for children. Instead, the developers are opting for rather cruel profit machine that will bring money exclusively to the investors. There is a significant influence of scale, more precisely building density and distances between buildings on the overall quality of the studied complexes. One of the main issues especially noted in Stup Nukleus �Journal of Natural Sciences and Engineering, Vol. 2, No.2 (2020) DOI number: 10.14706/JONSAE2021311 is that there is an evident lack of daylight in between the buildings, especially where the distance between two buildings is not more than 8 meters. This is causing privacy issues, issues with vistas which can also lead to the further psychological issues. From the regulatory plan is very important to state that the density and the height of the buildings is not by any regulations or laws that are set in place. The case study has shown that the layout of the bedrooms within the buildings is highly questionable, based on their position and the size. The versatility, the flexibility and the functionality of certain spaces, bedrooms foremost, are dubious due to their limited size. [4] Furthermore, it is important to conclude with saying that there needs to be improvements and persistency of government to pursue the execution of the initially set regulatory plans. Moreover, there is an evident need for a clear set of residential standards in terms of room size, layout, orientation etc. These standards should be used and applied as regulatory mechanisms. This will prevent any future mistakes. On the other hand, the investors need to keep in mind all of the aspects of living, rather than just providing profitable housing solutions without any amenities. Lastly, the final users of the housing should be more aware of all the consequences and implications of the inadequate residential settlements, instead of focusing just on price per m2. 5. REFERENCES [1] Bošnjak, Katarina. “URBANI IDENTITET SARAJEVA.” AABH, 5 Nov. 2016 aabh.ba/urbani-identitet-sarajeva/. [2] “Općina Novi Grad Sarajevo.” Općina Novi Grad Sarajevo, 2015; www.novigradsarajevo.ba/index.php?option=com_content&view=article&id=17&Itemid=21. [3] Sarajevo, Canton. “Building Regulations and Laws for Canton Sarajevo”, 2017, propisi.ks.gov.ba [4] Bachelard, G. (1994). The Poetics of Space. Boston: Beacon Press books [5] Finci, J. (1962). Development of Disposition and Function in Residential Culture of Sarajevo. Sarajevo: [6] NP Oslobodjenje. Grabrijan, D., & Neidhardt, J. (1957). Architecture of Bosnia and the Way to Modernity. Ljubljana. [7] Ernst, J. Z., Vukicevic, B., Jakulj, T., & Ilich, W. (2017, August 22). Sarajevo Paradox: Survival throughout History and Life after the Balkan War. Retrieved from Columbia University: from http://www.columbia.edu/cu/ece/research/intermarium/vol6no3/ernst.pdf [8] Federalni zavod za statistiku. (n.d.). Retrieved from http://fzs.ba/index.php/popis-stanovnistva/popisstanovnistva-2013/preliminarni-rezultati-popisa-2013/ [9] “PACIFIC’ d.o.o. Kiseljak.” TIBRA, 2019, tibra-pacific.com/tibra_new/. [10] Otoka, Nova. “NOVA OTOKA.” NOVA OTOKA, 1 Aug. 2015, www.novaotoka.com/en/home.php [11] Općina Ilidža https://www.opcinailidza.ba/uploads/files/shares/REGULACIONI%20PLANOVI/Regulacioni%20plan 20Stup%20Nukleus.pdf � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal of Natural Sciences and Engineering Identifier An unambiguous reference to the resource within a given context 2637-2835 DOI Digital object identifier 10.14706 Publisher An entity responsible for making the resource available International Burch University Description An account of the resource Journal of Natural Sciences and Engineering (JONSAE) is a peer-reviewed, biannually published international journal focusing on empirical and theoretical research in all branches of Engineering and Natural Sciences. It is published on the behalf of Faculty of Engineering and Natural Sciences of International Burch University and aims to provide the best content regarding by publishing original research papers, review articles, special issues, feature articles, and book reviews. All manuscript submissions are subject to initial appraisal by the Editor, and, if found suitable for further consideration, to peer review by independent, anonymous referees. All peer review is double-blind and submission is online. The journal welcomes theoretical, applied, interdisciplinary and methodological work, with preference on empirical research, critical approach and problem-solving methods in manuscripts. Language A language of the resource English Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Contemporary housing trends in Sarajevo Author Author Emina Mehić Abstract A summary of the resource. Within the last 20 years, there has been witnessed a significant increase of the urban population of Sarajevo, as a result of economic and social migrations. Consequently, this has caused an increasing demand for new housing which is mainly profit-oriented without any beneficial social, environmental or cultural implication. Primary objective of this research is to analyze the current situation and to assess the quality of the buildings not only as a housing solution, but as a complex that unites the community who inhabits it. This research will be conducted in a qualitative manner in analysis and statistical approach over the data related to the urbanization, building standards and positive effects of the building. Newly built parts of settlements Otoka and Stup will be used as case studies, since these parts of the city are most influenced by the mass production of the new housing solutions. This paper stresses out the correlation between high demand for the new housing and decreased quality of the housing without respecting minimum spatial and environmental standards, without basic amenities, social infrastructure and recreational and cultural activities. There is a need for improvements in contemporary housing design that will reflect with positive impacts on social, environmental, economic and cultural aspects of urban living. Keywords Keywords. Contemporary housing trends, qualitative analysis, Otoka, Stup Identifier An unambiguous reference to the resource within a given context 2637-2835 DOI Digital object identifier 10.14706/JONSAE2021317 https://eprints.ibu.edu.ba/files/original/10c6cd6b9a20e1a1393d9fe312dc243a.pdf b3d96f84062dbe647100f3a16c384236 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal of Natural Sciences and Engineering Identifier An unambiguous reference to the resource within a given context 2637-2835 DOI Digital object identifier 10.14706 Publisher An entity responsible for making the resource available International Burch University Description An account of the resource Journal of Natural Sciences and Engineering (JONSAE) is a peer-reviewed, biannually published international journal focusing on empirical and theoretical research in all branches of Engineering and Natural Sciences. It is published on the behalf of Faculty of Engineering and Natural Sciences of International Burch University and aims to provide the best content regarding by publishing original research papers, review articles, special issues, feature articles, and book reviews. All manuscript submissions are subject to initial appraisal by the Editor, and, if found suitable for further consideration, to peer review by independent, anonymous referees. All peer review is double-blind and submission is online. The journal welcomes theoretical, applied, interdisciplinary and methodological work, with preference on empirical research, critical approach and problem-solving methods in manuscripts. Language A language of the resource English Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Depression and Anxiety Analysis and Prediction using Big Data Technologies Author Author Mersiha Ćeranić, Samed Jukić Abstract A summary of the resource. COVID-19 pandemic brought many changes in people’s lifestyles. Some of those changes hurt people's mental health in different age groups. This research is done to investigate which factors contributed most to the occurrence of depressive and anxiety symptoms during COVID-19 lockdown, and what type of people in terms of age, sex, level of education, place of living, was the most exposed to the appearance of mental health disorders. 1115 people (18-85 years old) from Poland joined the research process. They fulfilled online questionnaires which were used as a basis for further research of lockdown impact on mental health. Responses are evaluated by using ML tools predicting the group of participants with signs of depression and anxiety, based on their answers to the questionnaires, and the attributes of the participants. Based on the results given by the studies, the youngest population (age 18-29), which participated in the surveys, experienced more intense depression and anxiety symptoms than participants from other age groups. Keywords Keywords. Anxiety, covid-19, decision tree, depression, logistic regression, tableau, Weka. Identifier An unambiguous reference to the resource within a given context ISSN 2637-2835 DOI Digital object identifier 10.14706/JONSAE2021327 Publisher An entity responsible for making the resource available International Burch University Language A language of the resource English language Type The nature or genre of the resource Original research https://eprints.ibu.edu.ba/files/original/6f132e73da7a55449a2406e39a5fcb3b.pdf d10a56d18bf5288213375abc8cf94ffe PDF Text Text Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020216 Distribution of inherited thrombophilia markers in Bosnian-Herzegovinian population: a review of previous studies Nermin Đuzić1, Adna Ašić1 1 International Burch University, Sarajevo, Bosnia and Herzegovina nermin.djuzic@stu.ibu.edu.ba adna.asic@ibu.edu.ba Abstract – Thrombophilia is a condition that is associated with an individual’s risk for venous or arterial thrombosis, as well as a risk of adverse pregnancy outcomes. Gene variants that are the most commonly associated with inherited thrombophilia are F5 mutation 1691G>A (Factor V Leiden), F2 20210G>A (prothrombin mutation), MTHFR 677C>T, and PAI-1 variant 4G/5G. This paper aims to review currently available literature on the prevalence of heritable thrombophilia genetic markers and their association with thromboembolic events in Bosnia and Herzegovina. PubMed and PubMed Central databases of the National Center for Biotechnology Information (NCBI) and ResearchGate were searched to identify the most relevant studies. The results of the previously published studies show discrepancies when it comes to reported findings, thus implying that further research on this topic is necessary. It is suggested that new studies include greater sample size in order to confirm the correlation between the studied variants and conditions associated with heritable thrombophilia in the Bosnian-Herzegovinian population and to advance the understanding of these variants. Keywords - Bosnia and Herzegovina, Factor V Leiden, Inherited thrombophilia, MTHFR, PAI-1, Prothrombin mutation 1. Introduction Thrombophilia is a condition putting an individual at risk of venous or arterial thrombosis and is mainly divided into hereditary and acquired. Hereditary thrombophilia is associated with genetic mutations influencing the level or activity of proteins involved in coagulation cascade and includes both loss-offunction and gain-of-function mutations [1,2]. Three genetic markers are the most commonly studied as indicators of inherited thrombophilia. F5 gene variant 1691G>A, usually termed Factor V Leiden, gives rise to a peptide that is uncleavable by the activated protein C (APC) [3]. According to Inbal and Carp (2007), this mutation is responsible for 3-42% of pregnancy losses [4]. If present in homozygous state, this mutation increases a risk for venous thrombosis up to 50-100-fold. The second most studied variant is F2 20210G>A, also known as prothrombin mutation (PTM), that causes elevated levels of prothrombin and 25-fold increased risk of venous thrombosis as well as pregnancy loss [5]. MTHFR gene variant 677C>T codes for thermolabile variant of protein methylene tetrahydrofolate reductase which is a loss-of-function mutation and causes elevated levels of homocysteine in blood, the condition known as hyperhomocysteinemia, which is in turn considered a risk factor for venous thromboembolism [6-8]. The fourth variant indicative of inherited thrombophilia is 4G/5G in type 1 plasminogen activator inhibitor �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020216 (PAI-1) gene, which is a 4328G>T missense variant located 675 bp from the promoter that results in four or five guanine nucleotides in a row [9,10]. The protein product of this gene has a role in fibrinolysis and is associated with adverse pregnancy outcomes, such as intrauterine fetal death, intrauterine growth restriction, preeclampsia, recurrent miscarriage and placental abruption [11]. The aim of this paper is to provide a comprehensive review of the current knowledge regarding the prevalence of heritable thrombophilia markers and their correlation with thromboembolic events in Bosnia and Herzegovina (B&H) based on previously published population studies. 2. Methods In order to investigate associations between the abovementioned genetic variants and inherited thrombophilia that may lead to adverse primary outcomes, National Center for Biotechnology Information (NCBI) databases PubMed and PubMed Central (PMC), and ResearchGate were searched to discover relevant studies published previously. Included were original research papers published in peer-reviewed journals that matched the search of the following keywords: “Factor V Leiden”, “F5 1691G>A”, “prothrombin”, “F2 20210G>A”, “MTHFR 677C>T”, “PAI-1 4G/5G”, “polymorphism”, “thrombophilia”, “Bosnia and Herzegovina”. In order to enhance the search, Boolean “AND” and “OR” operators were used to investigate the association between two searched terms. 3. Prevalence of genetic markers of inherited thrombophilia in Bosnian-Herzegovinian population The search results offered a total of seven studies related to the topic of the prevalence of genetic markers of inherited thrombophilia in B&H, all of them being conducted as of 2013. The study of Karić and colleagues in 2013 was the first study which deals with prevalence of MTHFR 677C>T polymorphism in Bosnian-Herzegovinian population. They studied 102 men and 105 women, who were unrelated and healthy and originating from south-east B&H. At the time of blood sampling, the study participants ranged between 18 and 84 years with a mean age of 45.62 years. The results have shown that 44.44% were heterozygous and 11.11% were homozygous for the study allele. No significant difference was found in allele and genotype frequencies between male and female participants [12]. The first study aiming at analyzing Factor V Leiden prevalence in B&H was performed in 2013 by Valjevac and colleagues. A group of 67 women with mean age of 58.6 years (range 41 to 75 years) with no previous history of cardiovascular diseases and pregnancy loss was recruited and tested. The study failed to find any mutant allele, thus suggesting that, considering functional importance of this allele, there is a need to conduct more research on that topic, as the results of this study were heavily influenced with the small sample size [13]. �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020216 The prevalence of polymorphisms Factor V Leiden, prothrombin mutation and MTHFR 677C>T was studied by Adler and colleagues (2014). The study involved a cohort of 100 healthy unrelated individuals from B&H (82 females and 18 males) with the year range of 24-82 years and the mean of 58.8 years. The analyzed loci were in Hardy-Weinberg equilibrium with the following minor allele frequencies (MAF): 6% for Factor V Leiden, 6% for F2 20210A allele, and 37.5% for MTHFR 677T allele. The authors noted the drawback of a small sample size and imbalanced sex ratio. The study, however, demonstrated the coinheritance of thrombophilia markers, since nine participants had Factor V Leiden and MTHFR 677C>T mutant. Compared to 17 European countries, the prevalence of Factor V Leiden and F2 20210G>A variants was significantly higher in B&H [14]. Another study examined the prevalence of the same three variants and their association with deep venous thrombosis (DVT) in B&H [15]. The study group included 111 thromboembolic patients (59 females and 52 males ranging from 21 to 84 years) and 207 healthy controls (105 females and 102 males ranging from 18 to 84 years) with no history of venous thromboembolism (VTE). When it comes to Factor V Leiden prevalence, 18% of the study group patients were heterozygous and 2.7% were homozygous, while 3.86% of the control group participants were heterozygous for this variant, which a statistically significant difference between groups. Statistically significant difference was also found between men with DVT and the control group, as well as between women with DVT and the control women group. F2 20210G>A variant was detected in 2.7% of the study group patients and was absent in control group, which was not statistically significant. Frequencies of MTHFR C677T alleles and genotypes did not differ significantly between the two groups. Allele frequency and functional significance of Factor V Leiden variant detected in this study was in agreement with earlier studies in Caucasians [16-20]. Also, the results of this study were found consistent with the data from other neighboring countries [21-23]. The absence of functional significance of the studied MTHFR polymorphism was also in line with previously published literature [4,16,24,25]. Finally, the authors of this study found that 14.9% of the patients from the DVT group were compound heterozygotes for Factor V Leiden and MTHFR 677C>T variants, therefore proposing further studies that would aim to analyze whether such genotype combination might be a risk factor for DVT development [15]. A study of Mahmutbegović and colleagues (2017) enrolled 308 women, including 154 women who experienced pregnancy loss as the study group (mean age 33 ± 5.4 years) and 154 women with at least one live-born child and without pregnancy loss as the control group (mean age 31.4 ± 6.7 years) to investigate the correlation between three genetic markers and pregnancy loss. Detected allele frequencies were 3.9% in both study and control groups for Factor V Leiden, 1.9% and 1.6% in the study and control groups, respectively, for prothrombin mutation, and 35.7% and 29.9% in the study and control groups, respectively, for MTHFR 677C>T. Although allele frequencies obtained in this study were in accordance with allele frequencies obtained for other European countries, the authors, however, were not able to find the significant correlation between these three variants and pregnancy loss in Bosnian-Herzegovinian women, which may be due to small sample size of women with three or four pregnancy losses recorded [26]. �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020216 The prevalence of Factor V Leiden, prothrombin mutation, MTHFR 677C>T and PAI-1 4G/5G in BosnianHerzegovinian women and their correlation with recurrent pregnancy loss was studied by Jusić and colleagues (2018). The study group included 60 women with two or more consecutive pregnancy losses that occurred before 20th gestation week with the same partner and without history of known causes of pregnancy losses due to chromosomal abnormalities, chronic diseases, or infections. The control group was consisting of 80 women with one or more successful pregnancy outcomes and without any pregnancy complication which could lead to the pregnancy loss. The results have shown that Factor V Leiden and MTHFR 677C>T were proved to correlate with recurrent pregnancy loss, while prothrombin mutation and PAI-1 4G/5G were not found to be significantly associated with the pregnancy loss. Reported allele frequencies were as follows: 7.5% for study and 1.88% for control group for Factor V Leiden, 2.5% for study and 0.63% for control group for prothrombin mutation, 39.17% for cases and 25% for control group for MTHFR 677C>T, and 30% for study and 20% control group for PAI-1 4G/5G. The authors are reporting allele frequencies that were in agreement with previous findings for all study polymorphisms. However, the role of genetic factors for inherited thrombophilia in recurrent pregnancy loss is still a matter of debate, especially when it comes to MTHFR and PAI-1 variants studied. Therefore, the authors are suggesting further studies with larger study and control groups, as well as the need to prevent recurrent pregnancy loss by assessing the status of these variants and calculating individual risk and optimum therapy for each patient [27]. In the most recent study by Ašić and colleagues in 2019, the prevalence of common thrombophilia markers was studied in a population of 130 unrelated healthy Bosnian- Herzegovinians of both sexes, from different age groups, with no recorded history of thrombotic events and originating from different parts of the country. Seven markers most commonly associated with the risk of heritable thrombophilia were investigated, namely Factor V Leiden, F2 20210G>A, MTHFR 677C>T, MTHFR 1286A>C, PAI-1 4G/5G, PAI-1 -844G>A and F13 V35L. Whereas some of these markers were examined in previous studies as described above, this is the first study to include MTHFR 1286A>C, PAI-1 -844G>A and F13 V35L polymorphisms in the population of B&H. The results have shown that the two main thrombophilia markers Factor V Leiden and prothrombin mutation appeared with MAF values of 0.023 and 0.008 respectively. For the remaining four loci, reported MAF values were 0.331 for MTHFR 677C>T, 0.323 for MTHFR 1286A>C, 0.446 for PAI-1 4G/5G, 0.588 for PAI-1 -844G>A, and 0.315 for F13 V35L. This study provides the most extensive population data on the prevalence of main heritable thrombophilia risk factors in B&H and reported allele frequencies were consistent with those reported for other European populations [28]. 4. Conclusion Previously conducted studies in B&H represent a small and rather heterogenous group of studies, including either population studies or case-control studies with the aims to report heritable thrombophilia marker prevalence in the population or their potential association with DVT, pregnancy loss or recurrent pregnancy loss. While initial preliminary studies offered surprisingly low or high MAF values for the most well-known genetic variants Factor V Leiden and F2 20210G>A, later studies reported allele and genotype prevalence �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020216 that is in line with reported data for most European populations. While DVT was found to be positively associated with Factor V Leiden variants [15], the data for obstetric complications are more controversial since two studies reported conflicting results. The first study reported no statistically significant association between Factor V Leiden, F2 20210G>A and MTHFR 677C>T and pregnancy loss [26], while the second one reported a significant increase in mutant allele frequency for Factor V Leiden and MTHFR 677C>T in women with recurrent pregnancy loss [27]. Therefore, it is strongly suggested that further studies assess the functional importance of the most important markers for inherited thrombophilias in B&H by clearly defining study and control groups in order to assess the potential association of these variants with conditions such as (recurrent) pregnancy loss and venous thromboembolism with the goal of assessing the importance of genetic testing in Bosnian-Herzegovinian population and establishing the groundwork for the personalized treatment of inherited thrombophilia and conditions connected to it. In that effort, larger study cohorts including individuals from all parts of the country will be necessary. REFERENCES [1] S. 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Pođanin, “Frequency and association of 1691 (G>A) FVL, 20210 (G>A) PT and 677 (C>T) MTHFR with deep vein thrombosis in the population of Bosnia and Herzegovina”, Balkan Journal of Medical Genetics, vol. 19, no. 1, pp. 43-50, 2016. [16] Z. Alfirevic, A. M. Simundic, N. Nikolac, N. Sobocan, I. Alfirevic, M. Stefanovic, and Z. Vucicevic, “Frequency of factor II G20210A, factor V Leiden, MTHFR C677T and PAI-1 5G/4G polymorphism in patients with venous thromboembolism: Croatian case-control study”, Biochemia Medica, vol. 20, no. 2, pp. 229-235, 2010. [17] E. Berge, K. B. F. Haug, E. C. Sandset, E., K. K. Haugbro, M. Turkovic, and P. M. Sandset, “The factor V Leiden, prothrombin gene 20210GA, methylenetetrahydrofolate reductase 677CT and platelet glycoprotein IIIa 1565TC mutations in patients with acute ischemic stroke and atrial fibrillation”, Stroke, vol. 38, no. 3, pp. 1069-1071, 2007. [18] T. Koster, J. P. Vandenbroucke, F. R. Rosendaal, H. de Ronde, E. Briët, and R. M. Bertina, “Venous thrombosis due to poor anticoagulant response to activated protein C: Leiden Thrombophilia Study”, The Lancet, vol. 342, no. 8886-8887, pp. 1503-1506, 1993. [19] L. Meglic, M. Stegnar, T. Milanez, M. Bozic, B. Peterlin, P. Peternel, and Z. Novak-Antolic, Factor V Leiden, prothrombin 20210G→A, methylenetetrahydrofolate reductase 677C→T and plasminogen activator inhibitor 4G/5G polymorphism in women with pregnancy-related venous thromboembolism”, European Journal of Obstetrics & Gynecology and Reproductive Biology, vol. 111, no. 2, pp. 157-163, 2003. [20] H. U. Pauer, T. Voigt‐Tschirschwitz, B. Hinney, P. Burfeind, C. Wolf, G. Emons, and J. Neesen, “Analyzes of three common thrombophilic gene mutations in German women with recurrent abortions”, Acta Obstetricia et Gynecologica Scandinavica, vol. 82, no. 10, pp. 942-947, 2003. �Journal of Natural Sciences and Engineering, Vol. 2, (2020) DOI number: 10.14706/JONSAE2020216 [21] T. Arsov, D. Miladinova, and M. Spiroski, “Factor V Leiden is associated with higher risk of deep venous thrombosis of large blood vessels”, Croatian Medical Journal, vol. 47, no. 3, pp. 433-439, 2006. [22] D. Coen, R. Zadro, L. Honovic, L. Banfic, A. S. Rukavina, “Prevalence and association of the factor V Leiden and prothrombin G20210A in healthy subjects and patients with venous thromboembolism”, Croatian Medical Journal, vol. 42, no. 4, pp. 488-492, 2001. [23] V. Djordjevic, L. J. Rakicevic, D. Mikovic, M. Kovac, P. Miljic, D. Radojkovic, and A. Savic, “Prevalence of factor V Leiden, factor V Cambridge, factor II G20210A and methylenetetrahydrofolate reductase C677T mutations in healthy and thrombophilic Serbian populations”, Acta Haematologica, vol. 112, no. 4, pp. 227-229, 2004. [24] C. Beyan, and E. Beyan, “MTHFR 677 CT gene polymorphism is not a risk factor for venous thromboembolism”, Çukurova Medical Journal, vol. 39, no. 1, pp. 189-190, 2014. [25] A. W. Tsai, M. Cushman, M. Y. Tsai, S. R. Heckbert, W. D. Rosamond, N. Aleksic, N.D. Yanez, B. M. Psaty, and A. R. Folsom, “Serum homocysteine, thermolabile variant of methylene tetrahydrofolate reductase (MTHFR), and venous thromboembolism: Longitudinal Investigation of Thromboembolism Etiology (LITE)”, American Journal of Hematology, vol. 72, no. 3, pp. 192-200, 2003. [26] E. Mahmutbegović, D. Marjanović, E. Medjedović, N. Mahmutbegović, S. Dogan, A. Valjevac, E. Czerska, A. Pawinska-Matecka, A. Madlani, and G. Adler, “Prevalence of F5 1691G> A, F2 20210G> A, and MTHFR 677C> T polymorphisms in Bosnian women with pregnancy loss”, Bosnian Journal of Basic Medical Sciences, vol. 17, no. 4, pp. 309-314, 2017. [27] A. Jusić, D. Balić, A. Avdić, M. Pođanin, and A. Balić, “The association of factor V G1961A (factor V Leiden), prothrombin G20210A, MTHFR C677T and PAI-1 4G/5G polymorphisms with recurrent pregnancy loss in Bosnian women”, Medicinski Glasnik (Zenica), vol. 15, no. 2, pp. 158-163, 2018. [28] A. Ašić, R. Salazar, N. Storm, S. Doğan, W. Höppner, D. Marjanović, and D. Primorac, ”Population study of thrombophilic markers and pharmacogenetic markers of warfarin prevalence in Bosnia and Herzegovina”, Croatian Medical Journal, vol. 60, no. 3, pp. 212-220, 2019. � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal of Natural Sciences and Engineering Identifier An unambiguous reference to the resource within a given context 2637-2835 DOI Digital object identifier 10.14706 Publisher An entity responsible for making the resource available International Burch University Description An account of the resource Journal of Natural Sciences and Engineering (JONSAE) is a peer-reviewed, biannually published international journal focusing on empirical and theoretical research in all branches of Engineering and Natural Sciences. It is published on the behalf of Faculty of Engineering and Natural Sciences of International Burch University and aims to provide the best content regarding by publishing original research papers, review articles, special issues, feature articles, and book reviews. All manuscript submissions are subject to initial appraisal by the Editor, and, if found suitable for further consideration, to peer review by independent, anonymous referees. All peer review is double-blind and submission is online. The journal welcomes theoretical, applied, interdisciplinary and methodological work, with preference on empirical research, critical approach and problem-solving methods in manuscripts. Language A language of the resource English Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Distribution of inherited thrombophilia markers in Bosnian-Herzegovinian population: a review of previous studies Author Author Nermin Đuzić, Adna Ašić Abstract A summary of the resource. Thrombophilia is a condition that is associated with an individual’s risk for venous or arterial thrombosis, as well as a risk of adverse pregnancy outcomes. Gene variants that are the most commonly associated with inherited thrombophilia are F5 mutation 1691G>A (Factor V Leiden), F2 20210G>A (prothrombin mutation), MTHFR 677C>T, and PAI-1 variant 4G/5G. This paper aims to review currently available literature on the prevalence of heritable thrombophilia genetic markers and their association with thromboembolic events in Bosnia and Herzegovina. PubMed and PubMed Central databases of the National Center for Biotechnology Information (NCBI) and ResearchGate were searched to identify the most relevant studies. The results of the previously published studies show discrepancies when it comes to reported findings, thus implying that further research on this topic is necessary. It is suggested that new studies include greater sample size in order to confirm the correlation between the studied variants and conditions associated with heritable thrombophilia in the Bosnian-Herzegovinian population and to advance the understanding of these variants. Keywords Keywords. Bosnia and Herzegovina, Factor V Leiden, Inherited thrombophilia, MTHFR, PAI-1, Prothrombin mutation Identifier An unambiguous reference to the resource within a given context 2637-2835 Publisher An entity responsible for making the resource available International Burch University, Sarajevo, Bosnia and Herzegovina Source A related resource from which the described resource is derived Journal of Natural Sciences and Engineering Date A point or period of time associated with an event in the lifecycle of the resource January, 2020 https://eprints.ibu.edu.ba/files/original/a9c60f561a4c20da19f9c16a5a311733.docx f620604759bfc76f080585af4886ce43 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal of Natural Sciences and Engineering Identifier An unambiguous reference to the resource within a given context 2637-2835 DOI Digital object identifier 10.14706 Publisher An entity responsible for making the resource available International Burch University Description An account of the resource Journal of Natural Sciences and Engineering (JONSAE) is a peer-reviewed, biannually published international journal focusing on empirical and theoretical research in all branches of Engineering and Natural Sciences. It is published on the behalf of Faculty of Engineering and Natural Sciences of International Burch University and aims to provide the best content regarding by publishing original research papers, review articles, special issues, feature articles, and book reviews. All manuscript submissions are subject to initial appraisal by the Editor, and, if found suitable for further consideration, to peer review by independent, anonymous referees. All peer review is double-blind and submission is online. The journal welcomes theoretical, applied, interdisciplinary and methodological work, with preference on empirical research, critical approach and problem-solving methods in manuscripts. Language A language of the resource English Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Effect of initial bacterial innoculum density on zones of inhibition in disk diffusion antibiotic susceptibility testing Author Author Aldijana Hadžić Nudžejma Kudić Monia Avdić Lejla Smajlović-Skenderagić Alisa Smajović Samra Međedović Abstract A summary of the resource. Abstract - The primary objective of this study was to show how the density of the initial bacterial inoculum effects the zone inhibition in Disk diffusion Bauer Kirby (BK) antibiotic susceptibility testing. In this study, three strains of Staphylococcus aureus were tested: a methicillin sensitive clinical strain, a methicillin resistant clinical strain and ATCC 25923. A series of decreasing initial inoculum densities of the three tested strains were prepared and poured onto Mueller Hinton agar plates. After overnight incubation the zones of inhibition around tested antibiotics from different inoculum densities were measured in mm. The results showed that inoculum density does have an effect on the zones of inhibition in BK antibiotic susceptibility testing of S.aureus where in the case of gentamycin sensitivity category change occurred. Correlation analysis showed that there is significant negative correlation between tested inoculum densities and zones of inhibition clinical methicillin sensitive strain of S.aureus after using oxacillin and gentamycin (Pearson coefficient were -0.917 and -0.892, respectively), and between tested inoculum densities and zones of inhibition clinical methicillin resistant strain of S.aureus after using ampicillin (Pearson coefficient was -0.960). Hence, initial bacterial inoculum density can be of high relevance in Bauer-Kirby disk diffusion testing and ought to be precisely determined in purpose of adequate therapy ordination. Keywords Keywords. Keywords: Staphylococcus aureus, susceptibility testing, McFarland standards, antibiotics, zones of inhibition. Publisher An entity responsible for making the resource available International Burch University Source A related resource from which the described resource is derived Journal of Natural Sciences and Engineering https://eprints.ibu.edu.ba/files/original/75d3d0af9ea8e10805ad5c3282bba357.pdf 7331ebb69ef6ccfd5bd7b7b6a4f1b3ca PDF Text Text Journal of Natural Sciences and Engineering, Vol. 1, (2019) DOI number: 10.14706/JONSAE2019114 Effect of metals on antibiotic sensitivity, growth, and biofilm-forming capacity of B. subtilis subsp. spizizenii Selma Cifric1 1 International Burch University, Sarajevo, Bosnia and Herzegovina selma.cifric@stu.ibu.edu.ba Abstract – B. subtilis is normally considered a soil organism, it can be also found in the animal and human gastrointestinal tract. Bacillus subtilis subsp. spizizenii is a type of Bacillus subtilis complex. It shares up to 99% of homology with B. subtilis CU1, which can be represented as a probiotic strain. Metal compounds found in soil or used in agriculture can easily enter the food chain and end up in our gut. Gram-positive bacteria (e.g. Bacillus spp.) have good adsorptive capacity for metals due to high peptidoglycan and teichoic acid content in cell walls. There is some evidence that certain metals inside the intestine play an important role in influencing growth and functionality of specific probiotic strains. Some of them have inhibitory, while others have an activating effect on bacteria. This study revealed that metal compounds increased antibiotic susceptibility of B. subtilis subsp. spizizenii. Higher concentrations of metal solutions inhibited growth of tested bacteria. Culture did not show affinity to form biofilms before or after addition of metal solutions. Keywords – antibiotic susceptibility, biofilms, MIC, metals. 1. Introduction Various bacteria reside in the gut or arrive there by food consumption. A microbiome is the overall collection of the genetic material of all microorganisms that live on or inside our body or collection of the genetic material of microorganisms in a particular environment (e.g., in your gut). Bacteria within our gut have an important role in digesting food, modulating the immune system, providing protection against harmful microbes, and more. Multiple factors including genotype, antibiotics, mode of delivery, dietary habits, lifestyle, social interactions and environmental factors shape the gut microbiota to make everyone’s microbiome unique [1, 2, 3]. Metal compounds can cause alterations in the composition of the gut microbiota. Usually, decrease in richness as well as the diversity of gut microbiota, is observed after exposure to metals [4, 5]. Gram-positive bacteria (e.g. Bacillus spp.) have good adsorptive capacity for metals due to high peptidoglycan and teichoic acid content in cell walls, in contrast to Gram-negative bacteria [6]. The phylum Firmicutes found in colon is mostly composed of gram-positive species, such as Clostridium and Bacillus. There is some evidence that certain metals inside the intestine play an important role in influencing growth and functionality of specific probiotic strains. Some of them have inhibitory, while others have an activating effect on bacteria. It has been concluded that many effects of metals are strain-specific [7]. �Journal of Natural Sciences and Engineering, Vol. 1, (2019) DOI number: 10.14706/JONSAE2019114 Bacillus subtilis is a gram positive and catalase positive rods. It is spore-forming bacteria. Although normally considered a soil organism, it is also found in the animal and human gastrointestinal tract [8]. Bacillus subtilis subsp. spizizenii is a type of Bacillus subtilis complex. It shares up to 99% of homology with Bacillus subtilis CU1, which can be represented as a probiotic strain that can have specific outcomes on the immune system of the elderly [9, 10]. Probiotics are commensal bacteria in the gut that have a health beneficial effect on the host organism. However, there are still a few unresolved questions regarding the safety of certain Bacillus strains, which is the main reason for their still limited application as probiotics [11, 12]. Biofilms are communities of bacteria joined together by a sticky extracellular matrix. This extracellular matrix is also responsible for adherent biofilms to various surfaces. Probiotic bacteria in the gut also use biofilm attachment to bind to the mucosa layer of the intestine. Biofilm attachment improves their survival rate. Specifically, biofilms provide protection against antibiotics and enzymes [13, 14, 15]. Antibiotics are antimicrobial agents active against bacteria. Their mode of action can be bactericidal or bacteriostatic. Application of antibiotics influences intestinal microbiota. It affects growth, diversity and antibiotic resistance of bacteria. Since Bacillus subtilis are partially considered as probiotic bacteria, normally found in the human gastrointestinal tract, this study will show their antibiotic susceptibility in the presence of metal compounds that can end up in our gut via food intake [16, 17]. In this paper, the effect of metal compounds on biofilm forming capacity, bacterial growth, and changes in antibiotic sensitivity is examined. It is assumed that metal compounds would increase antibiotic sensitivity and suppress growth. 2. Methods 1. Cultivation of B. subtilis subsp. spizizenii strain Bacillus subtilis subsp. spizizenii (ATCC 6633) was cultivated on solid and liquid media (trypticase soy broth (TSB) broth, TSB agar). After overnight incubation at 37 C, the turbidity of bacterial density is adjusted to 0.5 McFarland standard, as such was used for further tests. 2. Determination of antibiotic susceptibility before the addition of metal supplements Bacteria is previously cultivated on TSB agar. Susceptibility to fifteen types of antibiotics will be performed using the standard Kirby-Bauer disk diffusion method [18]. Antibiotics (Liofilchem) are listed in Table 1 below. 3. Microbroth dilution method Microbroth dilution method will be used to determine the minimal dose of metal supplement necessary to inhibit the growth of bacteria (minimum inhibitory concentration - MIC). It is accomplished through the standardized broth microdilution assay procedure [19, 20]. 96-well microtiter plates were used. The metal salts were aseptically diluted in TSB broth in the following w/V solutions: 1%, 0.5%, 0.25%, 0.12%, 0.06%, 0.03%, 0.015%, 0.007%, 0.003%, 0.0018%, 0.0009%. The 96-well plate contained 100 ul of different concentrations of metal solutions (CuSO4, ZnSO4 x 7H2O, Fe(NO3)3, and Mg), 100 ul TSB broth, and 20 ul of B. subtilis subsp. spizizenii (0.5 McFarland standard). This test was done in triplets. The �Journal of Natural Sciences and Engineering, Vol. 1, (2019) DOI number: 10.14706/JONSAE2019114 purpose was to determine the exact concentration of each metal that inhibits bacterial growth. After overnight incubation at 37 C visible growth of bacteria is recorded and MICs have been determined. 4. Determination of biofilm forming capacity This test determines how different concentrations of CuSO4 - copper (II) sulfate pentahydrate (Sigma-Aldrich), ZnSO4 x 7H2O - zinc sulfate heptahydrate (Sigma-Aldrich), Fe(NO3)3 - iron (III) nitrate (Fisher Scientific), and magnesium complex (Twinlab - dietary supplement from local pharmacy) will facilitate the biofilm formation. This test will be performed using TCP method. The 96-well plate contained different concentrations of metals, TSB medium, and 20 ul of B. subtilis subsp. spizizenii (0.5 McFarland standard). The inoculated plate should be covered with a lid and incubated for 24 h at 37 C. After incubation the content of the plates is discarded and washed. Crystal violet assay is used as a method of indirect biofilm quantification. Each microtiter-plate well is stained with 120 ul of 0.1% crystal violet and set aside for 10 minutes. Microliter-plate is decanted again and washed with distilled water. The test is done in triplets [21, 22]. 5. Determination of antibiotic susceptibility after addition of metals Susceptibility to fifteen types of antibiotics (Table 1) after addition of metal solutions will be performed using the Kirby-Bauer disk diffusion method [18]. Table 1. List of fifteen antibiotic discs used for antibiotic susceptibility testing. Name of antibiotic Micrograms Abbreviation Cefoxitin 30 FOX30 Gentamicin 10 CN10 Oxacillin 1 OX1 Amoxicillin 10 AML10 Ceftazidime + clavulanic acid 40 CAL40 Ciprofloxacin 5 CIP5 Streptomycin 10 S10 Vancomycin 30 VA30 Erythromycin 15 E15 Ceftazidime 10 CAZ10 Amoxicillin-clavulanic acid 30 AUG30 Azithromycin 15 AZM15 Kanamycin 30 K30 Tetracycline 30 TE30 Ampicillin 2 AMP2 �Journal of Natural Sciences and Engineering, Vol. 1, (2019) DOI number: 10.14706/JONSAE2019114 3. Results After testing the effect of metal compounds on growth, antibiotic susceptibility, and biofilm forming capacity, the following results were obtained. Table 2 shows results obtained after performing antibiotic susceptibility test for B. subtilis subsp. spizizenii. It compares diameters of the inhibition zone (in millimeters), before and after addition of four different metal compounds. Table 2. Antibiotic susceptibility test for B. subtilis subsp. spizizenii. Diameter of the zone of inhibition is in millimeters. (* - partially bactericidal) B. spizizenii B. spizizenii + Mg B. spizizenii + ZnSO4 x 7H2O B. spizizenii + Fe(NO3)3 B. spizizenii + CuSO4 FOX30 25 28 27 28 24 CN10 20 22 21 20 21 OX1 15 18 18 17 15 AML1 0 9 12* 15* 14* 11 CAL40 0 0 0 0 0 CIP5 29 32 32 32 35 S10 19 20 18 19 19 VA30 18 21 20 20 20 E15 21 25 28 24 25 CAZ10 0 0 6 8 0 AGU30 21 23 25 24 22 AZM1 5 20 22 21 23 22 K30 22 24 24 23 24 TE30 26 31 29 30 27 AMP2 0 0 0 0 0 Since diameters of inhibition zones for fifteen antibiotics were measured manually, Figure 1 visualizes sizes of diameters and possible manual errors during the measurement process. �Journal of Natural Sciences and Engineering, Vol. 1, (2019) DOI number: 10.14706/JONSAE2019114 Figure 1. Antibiotic susceptibility to fifteen antibiotics measured by zone of inhibition (in millimeters). Results of microbroth dilution tests are presented in Table 3 and Figure 2. Table 3 shows how different concentrations of metal (w/V) solutions affect growth of B. subtilis subsp. spizizenii, while minimum inhibitory concentrations of metals are summarized in Figure 2. Table 3. Growth of B. subtilis subsp. spizizenii under different concentrations of metal solutions w/V solution 1% 0.5% 0.25% 0.12% 0.06% 0.03% 0.015% 0.007% 0.003% 0.0018% 0.0009% Mg Fe(NO3)3 CuSO4 ZnSO4 x 7H20 No growth No growth No growth No growth No growth No growth No growth No growth No growth Growth No growth No growth No growth Growth No growth No growth Growth Growth No growth No growth Growth Growth Growth No growth Growth Growth Growth Growth Growth Growth Growth Growth Growth Growth Growth Growth Growth Growth Growth Growth Growth Growth Growth Growth �Journal of Natural Sciences and Engineering, Vol. 1, (2019) DOI number: 10.14706/JONSAE2019114 Figure 2. Minimum inhibitory concentration (MIC) of metal compound for growth of B. subtilis subsp. spizizenii B. subtilis subsp. spizizenii did not show affinity to form biofilms before (visible to the naked eye) or after addition of metal solutions at any concentration (w/V). The limitation of this study might be that the optical density of each microplate was not measured using ELISA reader. 4. Discussion In order to test the antibiotic sensitivity and growth, for this particular experiment, different metals had been taken to test this effect. In this particular experiment, one of the metals that had been used was zinc sulfate, a specific solid that can have a colorless crystalline structure. In a historical approach, it is known that zinc could be found in soil where different plants are harvested, but in different areas there is something known as solid deficiency, where plants cannot develop properly and grow because of the lack of zinc. And in order for this to be corrected, people have experimented and found out that in order to correct this deficiency, zinc sulfate can be added to the soil in order to have the proper growth of different crops. Because these metals are used in order to grow crops, this may have a different effect when the crops are consumed as a food source. [23, 24, 25]. Copper (II) sulfate pentahydrate is most commonly described as an inorganic compound that could be found in copper in the form of salt. It is highly soluble in water. This type of salt has a usage as an additive in order to recover pentose sugars from the fronts of palm oils. It had been used as well to prove specific antimicrobial properties when working with specific types of bacteria, but most importantly here with Bacillus subtilis [26, 27]. Copper (II) sulfate is used as fungicide in agriculture, as an additive for fertilizers and food [28]. �Journal of Natural Sciences and Engineering, Vol. 1, (2019) DOI number: 10.14706/JONSAE2019114 Iron (III) nitrate, or in other words ferric nitrate, is a type of metal that can be used in many fields. This type of compound can be used to treat different sludges and wastewaters, it can be used to remove nitrogen from different plants and it can also be used in analytical chemistry [29, 30]. All three of metals aforementioned, zinc sulfate, copper (II) sulfate pentahydrate, and iron (III) nitrate, can be found in soil or are used in agriculture. In that way they can get into the food chain and enter the human gut. One of the most abundant minerals that are important for different metabolic processes in the human body is magnesium. It can be found in over 300 enzymes as a cofactor and it regulates different biochemical reactions that are processed in the human body. Usually, magnesium is provided as a type of dietary supplement, people consume it in order for their body to function properly, and different amounts of these minerals are given to people based on various factors [31]. For example, magnesium citrate helps with constipation, it acts as laxative, while magnesium aspartate is important for digestion of macronutrients [32]. B. subtilis subsp. spizizenii showed visible growth at 0.06% (w/V) magnesium solution (Table 3). Dietary supplement was used as a source of magnesium. No significant changes were recorded in antibiotic susceptibility tests in presence of Mg, except with amoxicillin. Addition of Mg solution slightly changed property of B. subtilis subsp. spizizenii. According to obtained results amoxicillin was partially bactericidal (a few colonies appeared within the inhibition zone) for tested bateria, in the presence of magnesium. Susceptibility to fifteen types of antibiotics (Table 1), before and after addition of metal solutions, will be performed using Kirby-Bauer disk diffusion method. This test showed that B. subtilis subsp. spizizenii is completely resistant to ampicillin (AMP2), as well as to ceftazidime+clavulanic acid (CAL40). Antibiotic sensitivity of B. subtilis subsp. spizizenii did not significantly change for the following antibiotics: gentamicin (CN10), streptomicin (S10), vancomycin (VA30), azithromycin (AZM15), kanamycin (K30), cefoxitin (FOX30), oxacillin (OX1), ciprofloxacin (CIP5). Change in diameter was less or equal to 3 mm. Note that diameters were measured manually, and manual errors (gross errors) should be taken into account. Difference in diameter of zone inhibition of erythromycin (E15) with addition of zinc sulfate heptahydrate and without metal solution is 7 mm. There was an increase in diameter size of the inhibition zone for tetracycline (TE30) and amoxicillin (AML10) in presence of magnesium, zinc sulfate heptahydrate, and iron (III) nitrate solutions, compared to diameters of inhibition zones before addition of metal compounds. Besides that, a few colonies of bacteria were observed within amoxicillin zones of inhibition. Amoxicillin was partially bactericidal for B. subtilis subsp. spizizenii, in presence of magnesium, zinc sulfate heptahydrate, and iron (III) nitrate solutions. �Journal of Natural Sciences and Engineering, Vol. 1, (2019) DOI number: 10.14706/JONSAE2019114 B. subtilis subsp. spizizenii without presence of metal solutions was resistant to ceftazidime (CAZ10). With addition of zinc sulfate heptahydrate, and iron (III) nitrate solutions, zones of inhibition were 6 and 8, respectively. Since B. subtilis subsp. spizizenii shares the biochemical similarities with Bacillus subtilis subsp. subtilis results for these two strains can be compared. There is up to 58 to 68% is the DNA relatedness between these two bacteria [10, 33, 34]. According to Silman et al. vancomycin showed great bactericidal effect for B. subtilis in general [35]. Our data shows that zones of inhibition obtained by vancomycin (VA30) are ~20 mm, while the largest zones of inhibition were recorded in presence of ciprofloxacin (CIP5) ranging from 32-35 mm in diameter (Figure 1). Sim et al. obtained similar results about CIP5 and TE30, where zones of inhibition were 32 and 31, respectively [36]. Bacterial growth was registered for all four metal compounds at different concentrations (Table 3). No bacterial growth was registered for Mg at the concentrations 0.1%, 0.5%, 0.25%, 0.12%, while bacterial growth occured at all other tested w/v solutions (Table 3). B. subtilis spizizenii growth occurred at all other w/v solutions of iron (III) nitrate except at the concentrations 0.1% and 0.5%. Growth of bacteria in the presence of copper (II) sulfate w/v solution occurred at concentrations 0.03-0.0009%. The lowest growth rate was observed in the presence of zinc sulfate heptahydrate solution, bacterial growth occurred only on concentrations 0.015-0.0009% (Table 3). The lowest concentration of chemical (drug, antimicrobial) that inhibits visible growth of microorganism (in this case bacteria) in overnight culture is known as minimum inhibitory concentration (MIC) [37]. After overnight incubation at 37 C MICs were recorded (Figure 2). Obtained MICs of metal solutions that inhibit growth of B. subtilis subsp. spizizenii are: magnesium 0.12%, iron (III) nitrate 0.50%, 0.06% copper (II) sulfate, 0.03% zinc sulphate heptahydrate. Considering that, growth of tested bacteria is slightly inhibited by iron (III) nitrate solution (bacteria is growing in presence of metal solution whose concentration is <0.50%), while it is tolerating much lower concentrations of zinc sulfate heptahydrate solution (<0.03%). For this experiment laboratory strain of B. subtilis subsp. spizizenii was used. This strain did not form biofilms at all. According to other studies, during domestication of laboratory strains of B. subtilis accumulation of mutation can occur which can lead to their inability to form well-structured biofilms. Compared to the laboratory strains, undomesticated strains of B. subtilis usually form rich and strong biofilms [38, 39]. 5. Conclusion B. subtilis complex is normally found in soil, however it is also found in the human gut as harmless bacteria. Further research is needed for its wider application on the probiotic market due to safety concerns. Metal traces can be found in soil, wastewaters, products used in agriculture, fungicides, etc. as �Journal of Natural Sciences and Engineering, Vol. 1, (2019) DOI number: 10.14706/JONSAE2019114 such they can easily enter our food chain and end up in the human gut. This study investigated how specific metal compounds influence growth, antibiotic susceptibility, and biofilm forming capacity of B. subtilis subsp. spizizenii. Based on the results that have been retrieved, we can conclude that higher concentrations of metal solutions inhibited growth of tested bacteria, while it showed good tolerance to majority of lower concentrations of metals. Generally, culture showed increased sensitivity against antibiotics after addition of metal solutions. B. subtilis subsp spizizenii used in this experiment was laboratory strain and was not able to form biofilms. No influence of metals was recorded there. 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Determination of minimum inhibitory concentrations. Journal of antimicrobial Chemotherapy, 48(suppl_1), 5-16. [38] Bate, A. R., Bonneau, R., & Eichenberger, P. (2016). Bacillus subtilis systems biology: applications of‐omics techniques to the study of endospore formation. The Bacterial Spore: from Molecules to Systems, 129-144. [39] McLoon, A. L., Guttenplan, S. B., Kearns, D. B., Kolter, R., & Losick, R. (2011). Tracing the domestication of a biofilm-forming bacterium. Journal of bacteriology, 193(8), 2027-2034. � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal of Natural Sciences and Engineering Identifier An unambiguous reference to the resource within a given context 2637-2835 DOI Digital object identifier 10.14706 Publisher An entity responsible for making the resource available International Burch University Description An account of the resource Journal of Natural Sciences and Engineering (JONSAE) is a peer-reviewed, biannually published international journal focusing on empirical and theoretical research in all branches of Engineering and Natural Sciences. It is published on the behalf of Faculty of Engineering and Natural Sciences of International Burch University and aims to provide the best content regarding by publishing original research papers, review articles, special issues, feature articles, and book reviews. All manuscript submissions are subject to initial appraisal by the Editor, and, if found suitable for further consideration, to peer review by independent, anonymous referees. All peer review is double-blind and submission is online. The journal welcomes theoretical, applied, interdisciplinary and methodological work, with preference on empirical research, critical approach and problem-solving methods in manuscripts. Language A language of the resource English Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Effect of metals on antibiotic sensitivity, growth, and biofilm-forming capacity of B. subtilis subsp. spizizenii Author Author Selma Cifric Abstract A summary of the resource. B. subtilis is normally considered a soil organism, it can be also found in the animal and human gastrointestinal tract. Bacillus subtilis subsp. spizizenii is a type of Bacillus subtilis complex. It shares up to 99% of homology with B. subtilis CU1, which can be represented as a probiotic strain. Metal compounds found in soil or used in agriculture can easily enter the food chain and end up in our gut. Gram-positive bacteria (e.g. Bacillus spp.) have good adsorptive capacity for metals due to high peptidoglycan and teichoic acid content in cell walls. There is some evidence that certain metals inside the intestine play an important role in influencing growth and functionality of specific probiotic strains. Some of them have inhibitory, while others have an activating effect on bacteria. This study revealed that metal compounds increased antibiotic susceptibility of B. subtilis subsp. spizizenii. Higher concentrations of metal solutions inhibited growth of tested bacteria. Culture did not show affinity to form biofilms before or after addition of metal solutions Keywords Keywords. antibiotic susceptibility, biofilms, MIC, metals Identifier An unambiguous reference to the resource within a given context 2637-2835 DOI Digital object identifier 10.14706/JONSAE2021323