Short circuit faults are one of the most common disturbances in power systems that occur because of insulation failure due to a sudden overvoltage condition caused by lightning, switching operations, insulation contamination, etc. Medium voltage power distribution networks use different methods for grounding the neutral point. Influences of these grounding methods on the characteristics of single-phase short circuit fault are discussed in this paper on the example of substation “Bugojno”. Modeling and simulation are implemented in EMTP-RV (Electromagnetic Transient Program-Restructured Version) software. Data recorded by protection system during normal operation and three-phase short circuit fault in the substation are analyzed and used for comparison with simulation results to validate developed model of the observed part of power system. This validated model was then used to analyze the effects of neutral point grounding methods on the characteristics of single-phase short circuit fault.
Transient events, especially those related to the short circuit faults, are the main causes of power distribution lines outages. This paper is dedicated to the analysis of three-phase short circuit fault and its impact to the real 20 kV power distribution lines. One of the most important parts of Bosnia and Herzegovina's power system was monitored and analyzed. Short circuit currents and voltages were obtained by using the power distribution lines numerical protection system measurements from the moment of fault occurrence to the moment when the faulty line was switched off. Part of the power system of interest was modeled in EMTP-RV (Electromagnetic Transient Program - Restructured Version) software which is standardized software for transient analyses. Several simulations were conducted to perform fault analysis. Measured data and simulation results were compared.
Overvoltages are unpredictable and extremely dangerous for the electric power system. The causes of overvoltages are different, but lightning is considered as one of the most serious causes of overvoltages. High voltage substations are one of the main parts of the power system whose faults caused by overvoltages can lead to outage of large part of power system. Therefore, overvoltage protection of a high voltage substation is very important. In order to protect the substation as much as possible from the effects of the overvoltages, it is necessary to implement elements that can help reduce these effects, for example surge arresters. This paper presents the effects of the use of surge arresters in high voltage, gas SF6 insulated substation, modeled in the EMTP-RV (Electromagnetic Transient Program-Restructured Version) software. An accurate representation of lightning surge incoming in the substation is very important because it strongly affects the design of overvoltage protection system. In this paper parameters of lightning strikes are determined using Sigma Slp software.
The possibilities of using artificial neural networks (ANNs) for quick decision-making in the events of prolonged surges are presented in this paper considering that neural networks can establish non-linear relationships between the parameters of an ultra-high voltage transmission line. Research has been carried out based on theoretical models as well as practical problems aiming at the analysis of resonant overvoltages during their occurrence, development and existence. Determining of overvoltage characteristics was carried out in the presence of a significant number of fuzzy specified factors affecting the accuracy. The multilayer model, suitable for identifying the factors having the greatest impact on the occurrence, frequency and multiplicity of overvoltages in electrical networks, is applied. The resonant overvoltages were generated by connecting the autotransformer to the electrical bulk network. The results of determining the characteristics of resonant overvoltages using ANNs are presented in this paper. To achieve this goal, the following four tasks were formulated: (i) overvoltage characteristics using neural network methods were determined, (ii) neural network model corresponding to power line initial data was built, (iii) forecasted results were obtained, and (iv) the accuracy of constructed model was evaluated.
The Church of the Holy Archangels Michael and Gabriel located in Sarajevo is a national monument belonging to Eastern Orthodox cultural heritage. It is a very well-preserved sacral object considering the date of first mention is 1539 and it has been used to date for the religious purposes. On the other hand, deterioration of aging historical/religious buildings is inevitable process composed of cumulative, progressive and nonlinear factors. Hence, in order to maintain their best condition for as long as possible compliance with guidelines and procedures for cultural heritage preservation is needed. Climate control within historical/religious buildings surfaced as an important research area as indoor climate is changing in recent times. Humans have always shaped their environment by desire to enjoy concurrently the comfort of modern living as well as preserve the monuments for future generations. For example, use of heating systems in historical/religious buildings are creating new challenges for their preservation. This paper is an attempt towards the implementation of Internet of Things (IoT) system with focus on preservation of the national monument using a simulation of climate control in the Church of the Holy Archangels Michael and Gabriel.
The paper presents an approach to reverse engineering of a relational database schema. The approach enables database schema extraction from the corresponding metadata stored in the data dictionary by executing a universal set of queries regardless of the source database management system. The concrete queries are generated by combining predefined templates with concrete metadata for the particular source system. Based on the proposed approach, we implemented a software tool and experimentally validated it. The implemented solution enables reverse engineering of relational databases managed by several contemporary database management systems.
As one of the world’s great legal systems, Islamic law is taught at many academic institutions, using different methodological approaches and within differen institutional frameworks. The subject of this study is the teaching of Islamic law at public universities in the countries of the former Yugoslavia. It is based on the analysis of teaching curricula, textbooks, and additional literature used for courses at graduate, postgraduate and doctoral levels.At almost all law schools in the former Yugoslav member states that were the subject of this study, Islamic law is taught within the framework of General Political and Legal History or Comparative Legal History/Traditions and Political and Legal History or National Legal History. Within these subjects, Islamic law is taught within a comparative historical and legal perspective and as part of previous positive law under the Ottoman state.The scope of Islamic legal studies varies by state, however. For example, at the law faculties of the universities of Sarajevo, Belgrade, and Skopje, it is broadly taught at all three levels, while at the universities of Ljubljana and Podgorica it is not taught at all. In Sarajevo, Belgrade and Skopje, Islamic law is taught together with other great legal systems in historical and contemporary context, modelled on contemporary approaches to the study of Islamic law and legal cultures in general at academic institutions around the world. Bearing in mind the turbulent history of these states, the marginalisation of religion (and so of religious law) during the socialist period, and the fact that these faculties educate secular legal experts, the extent to which Islamic law is taught at public universities is satisfactory for the profile of experts being educated by them.
Malignancy is one of the major public health problems in Bosnia and Herzegovina. Along with breakthroughs in specific oncological therapy, improving the quality of life of cancer patients and management of therapy-induced side effects need to be recognized as a priority in the comprehensive cancer patient care. Fertility loss after cancer treatment is a field requiring special attention due to its various consequences on patients themselves. Although oncofertility is well-recognized area of oncology, low- to middle-income countries are facing issues with its implementation in everyday practice. Increased awareness about fertility preservation is of high priority for all specialists who participate in the medical care of cancer patients. The absence of a systemic solution and lack of expertise led to the founding of Fertility Preservation Working Group of the Oncology Association of Bosnia and Herzegovina. We have made recommendations as an expert consensus with the ultimate goal of making the first step toward enhancement of oncofertility implementation in Bosnia and Herzegovina.
Two tetraketone derivatives, one previously reported and one novel, were synthesized, whose structures have been confirmed by elemental analyses, NMR, HPLC-MS, and IR spectroscopy. The crystal structures of synthesized tetraketones were determined using X-ray single-crystal diffraction. To analyze the molecular geometry and compare with experimentally obtained X-ray crystal data of synthesized compounds 1 (2,2'-((4-nitrophenyl)methylene)bis(5,5-dimethylcyclohexane-1,3-dione)) and 2 (2,2'-((4-hydroxy-3-methoxy-5-nitrophenyl)methylene)bis(5,5-dimethylcyclohexane-1,3-dione)), DFT calculations were performed with the standard 6-31G*(d), 6-31G**, and 6-31+G* basis sets. The calculated HOMO-LUMO energy gap for compound 1 was 4.60 eV and this value indicated that compound 1 is chemically more stable compared to compound 2 whose energy gap was 3.73 eV. Both compounds' calculated bond lengths and bond angles were in very good accordance to experimental values determined by X-ray single-crystal diffraction.
Munir Mujić, Rječnik klasičnih arapskih termina: gramatika, književnost, stilistika, metrika: arapsko-bosanski, Sarajevo: Centar za napredne studije, 2019. Str. 198, ISBN 978-9926-471-17-0.
We propose reliability and latency quantities as metrics to be used in the routing tree optimization procedure for Wi-Fi mesh networks. In contrast to state-of-the-art routing optimization methods, our proposal involves directly optimizing the data rates of individual mesh links according to underlying channel conditions such that reliability and latency requirements are satisfied for entire mesh paths. Moreover, to mitigate the channel contention problem that is common in Wi-Fi networks, we propose a multichannel (MC) assignment method. In this method, bandwidth is allocated to the individual mesh nodes based on the expected traffic load that they are expected to handle. Once the bandwidth for each node is determined, specific channels are assigned in a way to avoid co-channel interference. Furthermore, considerable efforts were spent for developing a system-level simulator that captures the features of the physical (PHY) layer and medium access layer defined in the IEEE 802.11 standard (Wi-Fi). Using this simulator, we were able to show that Wi-Fi mesh networks using the proposed routing metric based on reliability and latency quantities significantly outperform the state of the art. Finally, the mitigation of channel contention through the proposed MC assignment method results in further dramatic gains in performance.
Patients do not access physicians at random but rather via naturally emerging networks of patient flows between them. As mass quarantines, absences due to sickness, or other shocks thin out these networks, the system might be pushed to a tipping point where it loses its ability to deliver care. Here, we propose a data-driven framework to quantify regional resilience to such shocks via an agent-based model. For each region and medical specialty we construct patient-sharing networks and stress-test these by removing physicians. This allows us to measure regional resilience indicators describing how many physicians can be removed before patients will not be treated anymore. Our model could therefore enable health authorities to rapidly identify bottlenecks in access to care. Here, we show that regions and medical specialties differ substantially in their resilience and that these systemic differences can be related to indicators for individual physicians by quantifying their risk and benefit to the system. As mass quarantines, absences due to sickness, or other shocks thin out patient-physician networks, the system might be pushed to a tipping point where it loses its ability to deliver care. Here, the authors propose a data-driven framework to quantify regional resilience to such shocks via an agent-based model.
Time synchronization in communication networks is a common issue: in a sensor network it means that the order of data samples becomes uncertain, which can make it unusable. Dedicated signals and schemes for synchronization of sensor networks has hence been a well-researched topic for decades. Here we bring in an approach to synchronization which uses the sensory data. Drawing inspiration from sensor time synchronization using environmental noise, we consider synchronizing sensory nodes for structural health monitoring–if the physical quantity the sensors measure is correlated, propagating as a wave, or oscillating in regular fashion, it is intuitively clear how to put it to use. We discuss when structural health monitoring signals can aid synchronization; we also connect this synchronization scheme to the idea of using physical human-made structures as reservoirs for reservoir computing, formulating synchronization as a reservoir computing task.
Muon colliders provide a unique route to deliver high energy collisions that enable discovery searches and precision measurements to extend our under-standing of the fundamental laws of physics. The muon collider design aims to deliver physics reach at the highest energies with costs, power consumption and on a time scale that may prove favorable relative to other proposed facilities. In this context, a new international collaboration has formed to further extend the design concepts and performance studies of such a machine. This effort is focused on delivering the elements of a ∼ 10 TeV center of mass (CM) energy design to explore the physics energy frontier. The path to such a machine may pass through lower energy options. Currently a 3 TeV CM stage is considered. Other energy stages could also be explored, e.g. an s-channel Higgs Factory operating at 125 GeV CM. We describe the status of the R&D and design effort towards such a machine and lay out a plan to bring these concepts to maturity as a tool for the high energy physics community.
Essa, Ahmed, Ali, Othmani, Studije o islamskoj civilizaciji: muslimanski doprinos renesansi. Sarajevo: Centar za napredne studije, 2016. str. 294. ISBN 978-9958-022-34-0
Nema pronađenih rezultata, molimo da izmjenite uslove pretrage i pokušate ponovo!
Ova stranica koristi kolačiće da bi vam pružila najbolje iskustvo
Saznaj više