Introduction/purpose: In the current literature, several dozens of vertex-degree-based (VDB) graph invariants are being studied. To each such invariant, a matrix can be associated. The VDB energy is the energy (= sum of the absolute values of the eigenvalues) of the respective VDB matrix. The paper examines some general properties of the VDB energy of bipartite graphs. Results: Estimates (lower and upper bounds) are established for the VDB energy of bipartite graphs in which there are no cycles of size divisible by 4, in terms of ordinary graph energy. Conclusion: The results of the paper contribute to the spectral theory of VDB matrices, especially to the general theory of VDB energy.
{"title":"Estimating vertex-degree-based energies","authors":"I. Gutman","doi":"10.5937/vojtehg70-35584","DOIUrl":"https://doi.org/10.5937/vojtehg70-35584","url":null,"abstract":"Introduction/purpose: In the current literature, several dozens of vertex-degree-based (VDB) graph invariants are being studied. To each such invariant, a matrix can be associated. The VDB energy is the energy (= sum of the absolute values of the eigenvalues) of the respective VDB matrix. The paper examines some general properties of the VDB energy of bipartite graphs. Results: Estimates (lower and upper bounds) are established for the VDB energy of bipartite graphs in which there are no cycles of size divisible by 4, in terms of ordinary graph energy. Conclusion: The results of the paper contribute to the spectral theory of VDB matrices, especially to the general theory of VDB energy.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86597781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction/purpose: To study the adequacy of applying numerical methods in the modal analysis of complex carrying structures of cranes. Methods: Comparative application of the analytical method and the numerical method - FEM. Results: Some comparative values of the modal parameters were obtained both analytically and numerically for the derived solution of a gantry crane carrying structure. Conclusion: It is shown that the numerical method can give a reliable general quality estimate of the structural behaviour of a complex carrying structure from the aspect of modal analysis.
{"title":"Comparison of the continuous model and the finite element model of the gantry crane carrying structure for modal analysis","authors":"R. Vasiljević","doi":"10.5937/vojtehg70-36051","DOIUrl":"https://doi.org/10.5937/vojtehg70-36051","url":null,"abstract":"Introduction/purpose: To study the adequacy of applying numerical methods in the modal analysis of complex carrying structures of cranes. Methods: Comparative application of the analytical method and the numerical method - FEM. Results: Some comparative values of the modal parameters were obtained both analytically and numerically for the derived solution of a gantry crane carrying structure. Conclusion: It is shown that the numerical method can give a reliable general quality estimate of the structural behaviour of a complex carrying structure from the aspect of modal analysis.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87295629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nikola Simić, Marjan Milenkov, Vladimir Milovanović, Vlada S. Sokolovic, P. Foltin, Balaž Takšas
Introduction/purpose: The paper presents a model of logistics support planning in the conditions of limited logistic resources based on the prioritization of customer requirements and resource allocation. Decisionmakers play a crucial role in the efficient and equitable allocation of resources as they prioritize among different user requirements. Methods: Requirement prioritization techniques that use nominal scale, ordinal scale, and ratio scale, and five methods for converting ranks into weighting coefficients have been applied to determine the degree of significance of user requirements. The Requirements triage method has been used for establishing relative priorities, while the heuristic algorithm determining the Kemeny median was used to consolidate individually ranked requests into a group rank. In order to balance opposing demands of users, consensus measures of group decision making were used. For obtaining an optimal planned solution of logistic support, the methods and techniques of resource allocation were applied. Results: A model for adaptive planning of logistics support in the conditions of limited resource capacities of the logistics system has been developed. Conclusion: The proposed model can be effectively applied in other areas of resource allocation.
{"title":"Logistics support planning model in the conditions of limited resources","authors":"Nikola Simić, Marjan Milenkov, Vladimir Milovanović, Vlada S. Sokolovic, P. Foltin, Balaž Takšas","doi":"10.5937/vojtehg70-33079","DOIUrl":"https://doi.org/10.5937/vojtehg70-33079","url":null,"abstract":"Introduction/purpose: The paper presents a model of logistics support planning in the conditions of limited logistic resources based on the prioritization of customer requirements and resource allocation. Decisionmakers play a crucial role in the efficient and equitable allocation of resources as they prioritize among different user requirements. Methods: Requirement prioritization techniques that use nominal scale, ordinal scale, and ratio scale, and five methods for converting ranks into weighting coefficients have been applied to determine the degree of significance of user requirements. The Requirements triage method has been used for establishing relative priorities, while the heuristic algorithm determining the Kemeny median was used to consolidate individually ranked requests into a group rank. In order to balance opposing demands of users, consensus measures of group decision making were used. For obtaining an optimal planned solution of logistic support, the methods and techniques of resource allocation were applied. Results: A model for adaptive planning of logistics support in the conditions of limited resource capacities of the logistics system has been developed. Conclusion: The proposed model can be effectively applied in other areas of resource allocation.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"98 6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87713019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction/purpose: Detailed theoretical and experimental studies have been carried out in order to investigate the problem of a phase stability in electrodynamically uncoupled Gunn oscillators. Methods: The influence of modulating pulse instabilities has been investigated by means of computer simulation in the framework of a nonlinear one-dimensional theoretical model of the GaAs Gunn diode semiconductor active region. Experimental observations were also conducted including microwave measurements and antenna far-field estimation. They confirm the main theoretical results and extend the key work conclusions. Results: It was shown that the initial phase of the microwave oscillation out of the Gunn oscillator is independent of internal noises of the semiconductor structure and can be fixed only by the modulating voltage pulse. Conclusion: Gunn-diodes based microwave oscillators were stabilized using the leading edge of the voltage pulse from the modulating power supply. These results open up serious prospects for designing antenna phased arrays based on Gunn oscillators without mutual feedback (electrodynamically independent).
{"title":"The phase stability of nanosecond Gunn oscillators","authors":"V. Kozhevnikov, A. Kozyrev, V. Konev, A. Klimov","doi":"10.5937/vojtehg70-36094","DOIUrl":"https://doi.org/10.5937/vojtehg70-36094","url":null,"abstract":"Introduction/purpose: Detailed theoretical and experimental studies have been carried out in order to investigate the problem of a phase stability in electrodynamically uncoupled Gunn oscillators. Methods: The influence of modulating pulse instabilities has been investigated by means of computer simulation in the framework of a nonlinear one-dimensional theoretical model of the GaAs Gunn diode semiconductor active region. Experimental observations were also conducted including microwave measurements and antenna far-field estimation. They confirm the main theoretical results and extend the key work conclusions. Results: It was shown that the initial phase of the microwave oscillation out of the Gunn oscillator is independent of internal noises of the semiconductor structure and can be fixed only by the modulating voltage pulse. Conclusion: Gunn-diodes based microwave oscillators were stabilized using the leading edge of the voltage pulse from the modulating power supply. These results open up serious prospects for designing antenna phased arrays based on Gunn oscillators without mutual feedback (electrodynamically independent).","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"102 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83951584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction: In 2020, the World Health Organization announced that Corona virus (Covid-19) is a global pandemic. Since then, social distancing and sterilization have become essential as precaution measures to decrease the infection. The risk of Covid virus spread led people, industries as well as governments to implement several approaches to control the transmission rate of the virus. During their daily life activities such as work, shopping, eating, etc. people touch a lot of surfaces and also open a large number of doors. This is considered to be one of the fastest ways to spread viruses because many people touch door handles which are generally rarely cleaned. Method: In this paper, the implementation of a cost-effective smart device has been presented. The device sprays ethanol onto a doorknob from an ethanol sterilizer after any person touches the knob. The sensor detects a hand touching the knob, after that a signal is sent to the Arduino for processing, and then after a 4.5-sec delay, the Arduino sends a signal to the water pump to pump ethanol alcohols through the nozzle directly to the knob. Results: The device shows precise and accurate results regarding the number of uses and the temperature of the surrounding ambient. Conclusion: The system is applicable in offices and public buildings. Due to its functionality, it can be of great assistance in decreasing the contamination of doorknobs.
{"title":"Design and implementation of a smart sterilizing device to solve the doorknob contamination problem","authors":"Satam Abdulrahman, Mohammed Zaenal","doi":"10.5937/vojtehg70-37492","DOIUrl":"https://doi.org/10.5937/vojtehg70-37492","url":null,"abstract":"Introduction: In 2020, the World Health Organization announced that Corona virus (Covid-19) is a global pandemic. Since then, social distancing and sterilization have become essential as precaution measures to decrease the infection. The risk of Covid virus spread led people, industries as well as governments to implement several approaches to control the transmission rate of the virus. During their daily life activities such as work, shopping, eating, etc. people touch a lot of surfaces and also open a large number of doors. This is considered to be one of the fastest ways to spread viruses because many people touch door handles which are generally rarely cleaned. Method: In this paper, the implementation of a cost-effective smart device has been presented. The device sprays ethanol onto a doorknob from an ethanol sterilizer after any person touches the knob. The sensor detects a hand touching the knob, after that a signal is sent to the Arduino for processing, and then after a 4.5-sec delay, the Arduino sends a signal to the water pump to pump ethanol alcohols through the nozzle directly to the knob. Results: The device shows precise and accurate results regarding the number of uses and the temperature of the surrounding ambient. Conclusion: The system is applicable in offices and public buildings. Due to its functionality, it can be of great assistance in decreasing the contamination of doorknobs.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81556757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction/purpose: The running of the coupling constant in various Quantum Field Theories and a possible behaviour of the beta function are illustrated. Methods: The Callan-Symanzik equation is used for the study of the beta function evolution. Results: Different behaviours of the coupling constant for high energies are observed for different theories. The phenomenon of asymptotic freedom is of particular interest. Conclusions: Quantum Electrodynamics (QED) and Quantum Chromodinamics (QCD) coupling constants have completely different behaviours in the regime of high energies. While the first one diverges for finite energies, the latter one tends to zero as energy increases. This QCD phenomenon is called asymptotic freedom.
{"title":"Beta functions in the quantum field theory","authors":"Nikola Fabiano","doi":"10.5937/vojtehg70-32131","DOIUrl":"https://doi.org/10.5937/vojtehg70-32131","url":null,"abstract":"Introduction/purpose: The running of the coupling constant in various Quantum Field Theories and a possible behaviour of the beta function are illustrated. Methods: The Callan-Symanzik equation is used for the study of the beta function evolution. Results: Different behaviours of the coupling constant for high energies are observed for different theories. The phenomenon of asymptotic freedom is of particular interest. Conclusions: Quantum Electrodynamics (QED) and Quantum Chromodinamics (QCD) coupling constants have completely different behaviours in the regime of high energies. While the first one diverges for finite energies, the latter one tends to zero as energy increases. This QCD phenomenon is called asymptotic freedom.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82133163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction: The energy consumed for street lighting is a major expenditure in urban environments. According to the World Bank, it constitutes up to 65% of cities' electricity costs and 10% of their overall budgets. The demand for lighting is growing significantly due to rapid urbanization, thus eating up even more energy and money - unless smarter solutions are deployed to reduce costs. Method: In this paper, a model for street lighting was established, consisting of several lamp posts on both sides of the street. The model was the exact replica of the street lighing system inside the city of Kirkuk, Iraq. The number of objects passing along the street was monitored, both during and out of rush hours. This all was taken into account in the energy consumption calculation. The controller used for this model is Arduino UNO. The Arduino receives signals from 3 IR sensors, processes these signals, and then sends the action to the lamp posts. Fuzzy logic was applied in two cases: the first one is during the daylight, the second one is during the sunrise and the sunset, to control the intensity of the light of the lamp posts. Results: Both cases showed significant results regarding the reliability, efficiency, and countability of the system in decreasing the level of energy consumption. Conclusion: The system can be applicable for smart city projects. It is efficient, cost effective and shows reliable results in saving energy.
{"title":"Fuzzy-based smart system for controlling road lights","authors":"Ihab A. Satam","doi":"10.5937/vojtehg70-36670","DOIUrl":"https://doi.org/10.5937/vojtehg70-36670","url":null,"abstract":"Introduction: The energy consumed for street lighting is a major expenditure in urban environments. According to the World Bank, it constitutes up to 65% of cities' electricity costs and 10% of their overall budgets. The demand for lighting is growing significantly due to rapid urbanization, thus eating up even more energy and money - unless smarter solutions are deployed to reduce costs. Method: In this paper, a model for street lighting was established, consisting of several lamp posts on both sides of the street. The model was the exact replica of the street lighing system inside the city of Kirkuk, Iraq. The number of objects passing along the street was monitored, both during and out of rush hours. This all was taken into account in the energy consumption calculation. The controller used for this model is Arduino UNO. The Arduino receives signals from 3 IR sensors, processes these signals, and then sends the action to the lamp posts. Fuzzy logic was applied in two cases: the first one is during the daylight, the second one is during the sunrise and the sunset, to control the intensity of the light of the lamp posts. Results: Both cases showed significant results regarding the reliability, efficiency, and countability of the system in decreasing the level of energy consumption. Conclusion: The system can be applicable for smart city projects. It is efficient, cost effective and shows reliable results in saving energy.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"163 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76413394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction/purpose: A fixed point theorem of an order-preserving mapping on a complete partial b-metric space satisfying a contractive condition is constructed. Methods: Extension of the results of Batsari et al. Results: The fidelity of quantum states is used to construct the existence of a fixed quantum state. Conclusions: The fixed quantum state is associated to an order-preserving quantum operation.
{"title":"Fixed point theorem in a partial b-metric space applied to quantum operations","authors":"R. Tiwari, K. Saeed, Shoba Rani, N. Fabiano","doi":"10.5937/vojtehg70-37109","DOIUrl":"https://doi.org/10.5937/vojtehg70-37109","url":null,"abstract":"Introduction/purpose: A fixed point theorem of an order-preserving mapping on a complete partial b-metric space satisfying a contractive condition is constructed. Methods: Extension of the results of Batsari et al. Results: The fidelity of quantum states is used to construct the existence of a fixed quantum state. Conclusions: The fixed quantum state is associated to an order-preserving quantum operation.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79128812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction/purpose: Some sums of the polylogarithmic function associated with harmonic numbers are established. Methods: The approach is based on using the summation methods. Results: This paper generalizes the results of the zeta function series associated with the harmonic numbers. Conclusions: Various interesting series as the consequence of the generalization are obtained.
{"title":"Harmonic series with polylogarithmic functions","authors":"Vuk Stojiljković, N. Fabiano, Vesna Šešum-Čavić","doi":"10.5937/vojtehg70-35148","DOIUrl":"https://doi.org/10.5937/vojtehg70-35148","url":null,"abstract":"Introduction/purpose: Some sums of the polylogarithmic function associated with harmonic numbers are established. Methods: The approach is based on using the summation methods. Results: This paper generalizes the results of the zeta function series associated with the harmonic numbers. Conclusions: Various interesting series as the consequence of the generalization are obtained.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"50 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72419221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Kozhevnikov, A. Kozyrev, A. Kokovin, N. Semeniuk
Introduction/purpose: One of the key approaches to solving an entire class of modern plasma physics problems is the so-called "plasma approximation". The most general definition of the "plasma approximation" is a theoretical approach to the electric field calculation of a system of charges under the electric quasi-neutrality condition. The purpose of this paper is to compare the results of the numerical simulation of the kinetic processes of the quasi-neutral plasma bunch expansion to the analytical solution of a similar kinetic model but in the "plasma approximation". Methods: The given results are obtained by the methods of deterministic modeling based on the numerical solution of the system of Vlasov-Poisson equations. Results: The provided comparison of the analytical expressions for the solution of kinetic equations in the "plasma approximation" and the numerical solutions of the Vlasov-Poisson equations system convincingly show the limitations of the "plasma approximation" in some important cases of the considered problem of plasma formation decay. Conclusion: The theoretical results of this work are of great importance for understanding the shortcomings of the "plasma approximation", which can manifest themselves in practical applications of computational plasma physics.
{"title":"Kinetic simulation of vacuum plasma expansion beyond the \"plasma approximation\"","authors":"V. Kozhevnikov, A. Kozyrev, A. Kokovin, N. Semeniuk","doi":"10.5937/vojtehg70-37337","DOIUrl":"https://doi.org/10.5937/vojtehg70-37337","url":null,"abstract":"Introduction/purpose: One of the key approaches to solving an entire class of modern plasma physics problems is the so-called \"plasma approximation\". The most general definition of the \"plasma approximation\" is a theoretical approach to the electric field calculation of a system of charges under the electric quasi-neutrality condition. The purpose of this paper is to compare the results of the numerical simulation of the kinetic processes of the quasi-neutral plasma bunch expansion to the analytical solution of a similar kinetic model but in the \"plasma approximation\". Methods: The given results are obtained by the methods of deterministic modeling based on the numerical solution of the system of Vlasov-Poisson equations. Results: The provided comparison of the analytical expressions for the solution of kinetic equations in the \"plasma approximation\" and the numerical solutions of the Vlasov-Poisson equations system convincingly show the limitations of the \"plasma approximation\" in some important cases of the considered problem of plasma formation decay. Conclusion: The theoretical results of this work are of great importance for understanding the shortcomings of the \"plasma approximation\", which can manifest themselves in practical applications of computational plasma physics.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88794525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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