Abstract This paper investigates the energy-efficient resource allocation algorithm for a massive multiple input multiple output (MIMO) system, in which each base station adapts the number of antennas to the daily load profile. Our paper examines the effect of two user location distribution (ULD) models, on the energy-efficiency (EE) of load adaptive masive MIMO system. We propose a resource allocation strategy to adapt the number of antennas based on tracking variations of ULD and cell loading maximizing the EE. We also evaluate impact of cell size, available bandwidth and output power level of the BS on EE at different cell loading.

Abstract Phase unbalance is a common issue encountered in LV electricity distribution networks, caused by uneven allocation of single-phase loads among phases. This paper analyses a part of a real LV distribution network, situated in Bosnia and Herzegovina. The impact of single-phase customers and single-phase charging of electric vehicles was analysed. To reduce unbalance and improve the voltage profiles, Phase Balance Optimization in DIgSILENT PowerFactory software was performed in six scenarios with different customer and electric vehicle unbalance. The goal was to find a method with the least number of changes in the customer and electric vehicle phase connection that fits within defined limits of voltage variations and voltage unbalance of a European norm for power quality (EN 50160). Results showed that all analysed scenarios were improved, with reference to voltage variation and voltage unbalance values, and were found acceptable by the limits from standard EN 50160.

Abstract In the past couple of years, the integration of electrical vehicles (EV) in the power system has been capturing the attention of many researchers, which has led to this being a frequently analysed topic in scientific papers and seminars. Some of the main parameters related to power quality that are observed, while integrating EVs, are voltage variations and voltage unbalance. The low-voltage rural network, of a small settlement located on the outskirts of Zavidovici, has been modelled for the purpose of this paper. Several cases were considered. As the first base case, an analysis was performed when there were no connected vehicles in the network, then the case with 20% penetration, 35% penetration, and 80% vehicle penetration. Practical analysis was done in DIgSILENT Power Factory software. It has been concluded that electrical vehicles cause a voltage drop in the network, while at the same time causing an increase in voltage unbalances.

Safety risk management in Bosnian-Herzegovinian underground coal mines is not based on a systematic approach and standardized risk management methods. Mostly there is a traditional approach present, i.e. reaction to incidents/accidents that happen. This paper aims to point out the need for proactive approach introduction with an emphasis on importance of ventilation systems failure mechanism simulation analysis in planning of people and property defense and rescue in crisis situations. Based on ventilation parameters measuring results for a given research site (brown coal mine), a model was developed on which a simulation analysis was performed for three characteristic ventilation failure cases: spontaneous oxidation at the longwall exit, collapse at the entrance to the longwall and methane outburst - preparation of a new excavation field. VnetPC and CFD “Fluent” software packages were used to simulate mine ventilation. Keywords: risk management, brown coal mine, safety, ventilation system, longwall, simulation analysis, VnetPC, Fluent.

Background: MRI techniques of the lumbar spine have not provided data on the effect of gravity on the spine and on the relationship of anatomic structures during its action. Because conventional MRI examinations of the spine are usually performed in the supine position these are often exacerbated by standing upright and are not evident in the supine position the loading conditions differ from those known to cause symptoms in patients with lumbar instability. Axial loading imaging may improve diagnostics in the clinical management of LBP and lead to appropriate treatment decisions. Objective: The aim of this study is to determine the significance of alMRI in detecting the morphologic changes of the lumbar spine caused by axial loading and to compare it with conventional MRI images of the lumbar spine without loading. Methods: The study was conducted as a prospective, descriptive clinical trial. Imaging was performed with a MRI 1.5 T in the head-first supine position. Imaging was performed in two acts: without load and under load. Loading for alMRI was performed with the DynaWell L-Spine device. The onset of loading was 10 minutes before the start of alMRI. The loading continued throughout the imaging procedure. The height of the IV, AP and LL diameters of IV, IV disk surface area, DSCA and width of the IV foraminas before and under load was measured. Results: After evaluating the changes in the height and size of the lumbar disks, the size of the DSCA, and the narrowing of the intervertebral foramina significant differences were found between the images before and after axial loading. Conclusion: alMRI provides information on morphological changes of all segments of the lumbar spine. This data represents significant information that can lead to more accurate and effective treatment of LBP.

Lightning parameters are needed in different engineering applications. For the prediction of the severity of transient voltages in power systems, an accurate knowledge of the parameters of lightning currents is essential. All relevant standards and technical brochures recommend that lightning characteristics should be classified according to geographical regions instead of assuming that these characteristics are globally uniform. Many engineers and scientists suggest that better methods for lightning current measurements and analyses need to be developed. A system for direct lightning current measurements installed on Mount Lovćen is described in this paper. Observed data were analyzed, and statistical data on parameters that are of interest for engineering applications were obtained, as well as correlations between various lightning parameters. Furthermore, a novel approach for classifying and analyzing lightning data from direct measurements based on empirical mode decomposition (EMD) is proposed. Matlab was used as a tool for signal processing and statistical analysis. The methodology implemented in this work opens possibilities for automated analysis of large data sets and expressing lightning parameters in probabilistic terms from the data measured on site.

Background: The COVID-19 pandemic has generated significant symptoms of stress, anxiety, and depression among health care workers, which can negatively affect the health and well-being of individuals. Although the WHO stressed the importance of nurturing mental health in the context of the COVID-19 pandemic, a more significant response focused on this area was still lacking in most countries. Objective: The aim of the study was to examine the differences in the levels of depression, anxiety, and stress in healthcare professionals in relation to exposure to contact with COVID-19 positive patients, as well as to examine the differences and correlation of sociodemographic characteristics of health workers in the experience of symptoms of depression, anxiety and stress. Methods: The research included 266 respondents, and it used a socio-demographic questionnaire and the DASS-21 scale. Mann-Whitney U tests, Kruskal-Wallis test and Spearman correlation coefficient were used in data processing. Results: The prevalence of high to extremely high symptoms of depression was reported in 45.49% of employees, anxiety 63.91% and stress 23.22%. Those who have been in continuous contact with COVID-19 positive patients, or 27.07%, report experiencing high or extremely high symptoms of depression, 36.60%, high to extremely high symptoms of anxiety, and 22.18% high to extremely high symptoms of stress. Discussion: The degree of self-care and family care, education level, and work experience were found to be a statistically significant factor in experiencing symptoms of depression, anxiety, and stress. Workers who were more in contact with COVID19 patients reported a higher degree of symptom on the DASS-21 scale. Those employees with more work experience had previously encountered similar situations of uncertainty and pressure, had better developed defense mechanisms, and showed less pronounced symptoms. A higher level of education often implies a higher degree of involvement in active treatment around each patient, which results in more responsibility and pressure in a given situation. Conclusion: High levels of stress, anxiety and depression in healthcare workers can lead to repercussions in their work with patients. Therefore, the mental health of health workers should be put in focus, as a very important part of the public health problem during the COVID19 pandemic.

Abstract Simulation of unsteady flow of SF6 gas in a simplified high-voltage circuit breaker model describing the nozzle, contacts and their nearest surrounding is presented. SF6 is considered as viscous, compressible, real gas described by Redlich-Kwong model. Heat transfer is taken into account due to the gas compressibility. The heat source, triggered by the electric arc between the contacts, was out of the scope of the current research, thus it was not included in the simulations presented. Turbulence, caused by the gas viscosity, is described using realizable k-ε model. In the simulation model, one of the contact sides – electrodes, is considered as moving at prescribed velocity. The part of the space ‘swept’ by the moving electrode is considered as the gas with imposed artificially increased viscosity in order to imitate the rigid body behaviour. Thus, no moving parts of the computational mesh are used in the model. The conservation equations of mass, momentum and energy, given in integral form, are solved using a finite-volume method on unstructured computational grids.

Simple Summary Radionecrosis is a common and rising problem in neuro-oncology. Image interpretation and management of these patients has to be conducted in an interdisciplinary setting in order to offer the best medical care to patients with gliomas or brain metastases. In this article, we provide a state-of-the-art institutional guideline for the current morphological, functional, metabolic and evolving imaging tools to distinguish radionecrosis from tumor recurrence. We also discuss the therapeutic possibilities and give an outlook on future developments to tackle this challenging topic. Abstract Radiation necrosis represents a potentially devastating complication after radiation therapy in brain tumors. The establishment of the diagnosis and especially the differentiation from progression and pseudoprogression with its therapeutic implications requires interdisciplinary consent and monitoring. Herein, we want to provide an overview of the diagnostic modalities, therapeutic possibilities and an outlook on future developments to tackle this challenging topic. The aim of this report is to provide an overview of the current morphological, functional, metabolic and evolving imaging tools described in the literature in order to (I) identify the best criteria to distinguish radionecrosis from tumor recurrence after the radio-oncological treatment of malignant gliomas and cerebral metastases, (II) analyze the therapeutic possibilities and (III) give an outlook on future developments to tackle this challenging topic. Additionally, we provide the experience of a tertiary tumor center with this important issue in neuro-oncology and provide an institutional pathway dealing with this problem.

Abstract In this invited review article, we give a comprehensive account of the existing literature on the electronic properties of organic materials. The main focus of this article is the rich and extensive literature on the electronic transport in organic materials, particularly conjugated polymers, as they offer numerous advantages over inorganic materials. Consequently, they have found widespread application in photovoltaics, light-emitting displays, and even, more recently, in thermoelectric energy conversion. This literature review will be useful to researchers starting in the field of organic electronics as well as experts seeking to broaden their understanding of transport in polymers.

In their individual categories and entities, both American and Bosnian and Herzegovinian literatures are more transnational in the 21st century than ever before in the history of the literature of both countries, or even in the history of world literature. The transnationality of both has been manifested in many ways through the history of the world as seen as an open space for mobility in both literatures, being in many respects opposed to the closed spaces of the “imagined communities” of the nation-states these literatures “belong to” in the national context. In addition, transnational American and Bosnian-Herzegovinian literature has been created on both sides as a joined and mutual, permuting and open space/category in both literatures. Hence, there are individual systems and spaces of Transnational American Literature(s) and Transnational Bosnian and Herzegovinian Literature(s), and there is a mutual category and a joined entity of Transnational American and Bosnian and Herzegovinian Literature(s) as part of the generic system of both trans/national works of literature. The special aim of the article is to contribute to the field of the study of Contemporary Transnational American, Bosnian-Herzegovinian, and American-Bosnian-Herzegovinian works of literature, emphasizing how the identities of authors and/or their books and then their modes of mobility, can defamiliarize and resist conventions and canon of “imagined communities”. In that context, the article also aims to benefit contemporary trans/national literary and cultural studies in their specificity and uniqueness in the United States and Bosnia and Herzegovina. Broader the world, examining the processes through which American and Bosnian-Herzegovinian literature become members of the “World Republic of Letters” and how this process is experienced and vice versa