On integral cohomology algebra of some oriented Grassmann manifolds

The integral cohomology algebra of $\widetilde G_{6,3}$ has been determined in the recent work of Kalafat and Yal\c{c}inkaya. We completely determine the integral cohomology algebra of $\widetilde G_{n,3}$ for $n=8$ and $n=10$. The main method used to describe these algebras is the Leray-Serre spectral sequence. We also illustrate this method by determining the integral cohomology algebra of $\widetilde G_{n,2}$ for $n$ odd.Comment: 19 page

Regional characteristics of individual housing units in Serbia from the aspect of applied building technologies

Individual housing units in Serbia have been studied from the aspect of applied technical solutions. Analyzed data have been collected during a field research in accordance with the current administrative regional division, and they represent a basis for definition of regional typology of individual housing units. Characteristic types of objects of each region’s typology have been further analyzed. Upon these analyses regional characteristics of individual housing units regarding applied construction types, building technologies and materials have been defined and presented. [Projekat Ministarstva nauke Republike Srbije, br. TR 36034: Investigation and Systematization of Serbian Housing in Context of Globalization and European Integration in the Framework of Quality and Living-Standard Improvement

Lokalizacija glavnih i pomoćnih otvora na mezijalnom i distalnom korenu prvih donjih molara

Introduction. Understanding the morphology of the root canal system, and especially its apical third, represents the basic precondition for the successful treatment of diseased pulp and the apical endodontium. Aim. The aim of this study was to precisely locate the main and ancillary foramina in the mesial and distal first lower molars. Method. One hundred extracted first lower molars, originating from persons of both sexes and three different age groups, were used in the study. Results. The analysis of the sampled molars’ apical third was carried out using a binocular magnifier and a digital X-ray scanner (Trophy). The results showed that the main mesial and distal root foramina were located mostly on the distal surface. The ancillary mesial and distal root foramina were located at the lingual end, in most cases. Statistical analysis demonstrated the congruence of results achieved using the binocular magnifier and digital x-ray in 100% of cases if the main foramen is located on the very top of the mesial root (χ2 =17.23; p lt 0.001), and in 92.9% of cases if the main foramen is localised on the very top of the distal root of the first lower molar (χ2 =12.07; p lt 0.001). Conclusion. The most common localisation of the main foramina for all age categories and in both mesial and distal roots is on the distal surface of the root. The greatest number of ancillary foramina was observed in the youngest age category, while they were localised most often on the lingual side of the mesial and distal root.Uvod Poznavanje morfologije korenskog kanalskog sistema zuba, a naročito njegove apeksne trećine, predstavlja osnovni preduslov za uspešno lečenje obolele pulpe i apeksnog endodoncijuma. Cilj rada Cilj rada je bio da se odredi tačna lokalizacija glavnih i pomoćnih otvora na mezijalnom i distalnom korenu prvih donjih stalnih molara. Metod rada Ispitano je 100 ekstrahovanih prvih donjih molara osoba oba pola, podeljenih u tri starosne kategorije. Analiza apeksne trećine uzoraka je urađena pomoću binokularne lupe i digitalnog rendgenografskog aparata (Trophy). Rezultati Dobijeni rezultati su pokazali da je najčešća lokalizacija glavnih otvora na mezijalnom i distalnom korenu bila na distalnoj strani. Pomoćni otvori na mezijalnom i distalnom korenu su najčešće bili lokalizovani na lingvalnoj strani korena. Statistička analiza je pokazala podudarnost rezultata dobijenih primenom binokularne lupe i digitalne rendgenografije kod 100% ispitanih zuba ako je glavni otvor lokalizovan na samom vrhu mezijalnog korena (χ2=17,23; p lt 0,001), odnosno kod 92,9% zuba kada je glavni otvor na samom vrhu distalnog korena prvog donjeg molara (χ2=12,07; p lt 0,001). Zaključak Najčešća lokalizacija glavnih otvora i kod mezijalnog i kod distalnog korena je na distalnoj površini korena u svim starosnim kategorijama. Najveći broj pomoćnih otvora uočen je u najmlađoj starosnoj kategoriji, a najčešće su bili lokalizovani na lingvalnoj strani mezijalnog i distalnog korena

FOREWORD

A good and resourceful manager has always been and will continue to be a key factor in a successful educational institution, both by shaping relationships with the environment and by functionally managing the resources of the educational institution. Skilled managers are professionals who are aware of their role in the functioning of the institution they manage and in realising its potential. Thus, they must keep up with the times, with the development of pedagogical science and the new principles for optimising pedagogical work at all levels of education.The special issue of Facta Universitatis, Series: Teaching, Learning and Teacher Education was prepared following the international scientific conference Management in Education - Contemporary Approaches and Perspectives, held on November 25, 2022 at the Pedagogical Faculty in Vranje, University of Niš, Serbia. The conference was organised by the Pedagogical Faculty in Vranje in cooperation with the Faculty of Education, University of Primorska, Slovenia; the Faculty of Teacher Education, University of Zagreb, Croatia; the Faculty of Pedagogy, University "St. Kliment Ohridski" Bitola, North Macedonia; St Kliment Ohridski Faculty of Pedagogy, SS Cyril and Methodius University in Skopje, North Macedonia and the Faculty of Philosophy, University of Niš, Serbia.The global market for knowledge and education requires the academic community to respond to current trends in educational management and institutions. Therefore, it is expected that the work presented at the conference will contribute to the promotion of areas that are important for the development and modernization of management in education. This is one of the leading areas of education that influences socio-economic development through the implementation of its basic functions: planning, organising, directing and controlling, analysing and measuring the results of educational services and performance.The conference brought together academics from nine countries and nineteen universities to raise awareness of the diverse global challenges related to the following topics: Contemporary Theoretical Concepts of Management - Implementation in Educational Institutions, Strategic and Developmental Management in Education - Factors for Efficiency of Educational Institutions, Strategic Planning in Education in Uncertain Conditions, Knowledge Management in Education, Leadership in Education, Styles and Competencies of Leaders, Management of Education in the Digital Age: the Role of ICT and other challenges and opportunities in Management in Education.By considering these topics of permanent importance, some possible answers were given to questions related to the function of management (both strategic and operational) in modern education, the challenges of the role of managers, the improvement of management technology, the quality of human resources in an educational institution, the process of training future managers and other important issues within the defined topics. In this sense, it was concluded that the need for capable managers who manage the creation of new values and ways of working with measurable business success is present in all areas of work. Modern management as a social technology, or as a way to implement a certain idea through the commitment of others, requires an educationally trained workforce, a leader with managerial skills who, during training, must sharpen their leadership skills and vision, both for the work they will perform and for the actual life they will lead

Work stress related lipid disorders and arterial hypertension in professional drivers: A cross-sectional study

Background/Aim. Occupational stress is a term used to define ongoing stress that is related to the workplace. The study was conducted to determine association of occupational stress index (OSI) and its aspects with arterial hypertension and lipid disorders using data from a cross-sectional survey of male professional drivers. Methods. The cross-sectional study was performed in 439 professional drivers divided into groups (city- and intercity bus drivers, truck and taxi drivers). The OSI and OSI aspects (high demands, strictness, underload, extrinsic time pressure, noxious exposure, avoidance and conflict) were calculated using the standardized questionnaire. Determination of serum lipids, blood pressure (BP) and cardiovascular risk factors were done. Results. A significant difference in prevalence of diagnosed hypertension and dyslipidemia was found along with a difference in total OSI and OSI aspects among examined subgroups of drivers. A total OSI was highest in city, high in intercity bus drivers, and the lowest one in truck and taxi drivers (82.79 ± 3.5, 81.28 ± 3.7, 73.75 ± 3.5, 71.61 ± 4.4, respectively; p < 0.01). Similar pattern showed triglycerides (TG), total cholesterol (TC) and LDL cholesterol and BP, while HDL-cholesterol showed reverse order (p < 0.01). Logistic regression analyses with multiple OSI aspects adjusted for age and years of exposure showed associations of total OSI with arterial hypertension [OR 5.5; 95% CI (2.24-7.95)] and dyslipidemia [OR 1.43 95% CI (1.09-2.80)]. Underload was the most important OSI aspect associated with the arterial hypertension [OR 1.18; 95% CI (1.04-2.58)] and elevated LDL cholesterol [1.26; 95 CI (1.19-2.1)]. A total OSI had a significant association with elevated LDL cholesterol [2.64; 95% CI (1.19- 7.7)], triglycerides [OR 3.27; 95% CI (1.20-5.1)] and low HDL cholesterol [OR 3.29; 95% CI (1.8-5.8)] (p < 0.01). Conclusion. The study provides the evidence for the significant association of total OSI and underload with lipid disorders and elevated blood pressure in professional drivers, which could be a possible link between job stress and coronary heart disease. Regular periodical examinations and workplace interventions aimed to decrease total OSI and underload are important aspects in primary prevention and additional reduction of cardiovascular risk. [Projekat Ministarstva nauke Republike Srbije, br. 43012 i br. 41018

Development for CO2 emissions reduction by the use of solar thermal collectors in the process of urban planning

Using RES is one of the most important characteristics of the sustainable and resilient development. Nowadays, need to minimize CO2 emissions is obligatory, especially in the sector of urban and architectural planning, since in Serbia approximately 50% of produced energy is spent in buildings. The CO2 emission, in urban structures, can and must be reduced at the different levels: building level, block, and city level. For the city of Kragujevac, based on urban parameters defined in General Urban Plan, typical urban block was chosen and typical building structure developed. Calculation were made, based on recommendations developed by the Ministry of mining and energy and Serbian regulations, for the energy needed for domestic hot water preparation. In this paper, the influences of architectural and urban parameters on the use of solar thermal collectors at the typical building and urban block level is investigated. Recommendations are prepared for principles of urban and architectural design in order to enable the use of collectors for domestic hot water preparation and in that way CO2 emission reduction. Developed methodology for the city of Kragujevac can be applied in defining design principles in whole the country and Balkans region, not only for the use of solar thermal collectors but also for the use of other RES

Possibilities for the use of geothermal energy in new residential buildings in Serbia, case study Urban Blocks in City of Kragujevac

Use of RES is an important element for achieving ambitious results for CO2 emission reduction in EU, emphasized and obligated by RES Directive, among other documents. In Serbia, as a candidate country and a signatory of Energy treaty, targets set by relevant documents reflect in benchmarks set by National Action Plan for Energy Efficiency, setting the level of reduction of energy consumption until 2018 for 9%, with more ambitious projections up to 2030. This calls for extensive research of possibilities for the use of renewable energy in buildings, its potentials and possible restrictions. Since the Directive states that low amount of energy required should be covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced on-site or nearby, an investigation of possibilities for application of geothermal ground probes for a typical residential urban block in the city of Kragujevac is presented. This enables analysis of limitations imposed by legal and physical conditions: planning guidelines, type of ground, functional requests and infrastructural capacities. Typology of characteristic urban block layouts for residential buildings is generated, leading to projections of possible area covered with ground probes and calculations of relevant energy needed for heating, based on current regulations on energy efficiency in buildings. From these calculations, percentage of defined energy needs from possible geothermal ground probes is defined, enabling estimation of geothermal energy potential for new residential building blocks

Application of sunspaces in fostering energy efficiency and economical viability of residential buildings in Serbia

Residential building sector in Serbia has changed dramatically over the last two decades. Large scale projects have given way to individual, private initiative resulting in smaller interventions rarely exceeding one lot. For this reason architectural concepts, building types, scopes and construction technology have been marginalized and fallen under the influence of market mechanisms and stringent local planning procedures. New regulations on energy efficiency have risen the standards for thermal insulation therefore increasing the thickness of building enclosure. This actually means that construction costs are increased and net built area, therefore expected profit, reduced. In order to provide the viable ground for both implementation of new regulations and economic benefits for investors, authors of energy efficiency regulations in Serbia have noted a whole set of solar systems, among which sunspaces that would not count as a part of gross area, provided that they contribute to the increase of energy performance of the building. This paper describes the case of a typical residential new construction in Belgrade that has applied the prescribed solutions and became the first building that has obtained the building permit by applying a sunspace as an efficient strategy for energy saving.This is the peer-reviewed version of the article: Ignjatović, Dušan, Milica Jovanović Popović, and Jasna Kavran. 2015. ‘Application of Sunspaces in Fostering Energy Efficiency and Economical Viability of Residential Buildings in Serbia’. Energy and Buildings, Renewable Energy Sources and Healthy Buildings, 98 (July): 3–9. [https://doi.org/10.1016/j.enbuild.2015.02.049

Razrešavanje komunikacionih konflikata u bežičnim senzorskim mrežama primenom RF tonova

This doctoral dissertation comprises a novel contention resolution mechanism for wireless sensor networks, based on the exchange of short radio-frequency (RF) tones among sensor nodes. Originality of the proposed mechanism comes from the new algorithm for successive elimination of nodes during the contention resolution phase. The algorithm is based on binary countdown mechanism and guaranties collision-free communication with minimum number of RF tones transmitted. The proposed technique, called TONE, has better performances in terms of energy efficiency and communication throughput, compared to existing binary countdown based contention resolution mechanisms. The application area of the TONE are Medium Access Control (MAC) protocols for wireless sensor networks. In this dissertation, the proposed TONE is applied in intracluster MAC protocol for star topologies, where reduces the average energy consumption during contention period for up to 44.5% compared to the baseline countdown mechanism. When aplied in receiver-driven TDMA MAC protocol, the proposed TONE achieves the same troughput as transmitter-driven TDMA MAC protocol with 3 times smaller energy consumption, and even 4.5 smaller energy consumption than receiver-driven TDMA MAC protocol with CSMA-based contention resolution mechanism. The proposed TONE is also applied in active period MAC protocols, where it increases normalized data troughput for more than 100% compared to existing active-tone MAC protocols, with reduction of energy consumption of up to 500%

Energy refurbishment of public buildings in Serbia

By harmonizing national legislation to European codes concerning energy efficiency in building sector, Serbia took commitment to improve energy efficiency of national government buildings. Following the Directive 2012/27/EU principles, refurbishment of this part of building stock is recognized as a leading example in long-term process of applying energy efficiency regulations at national level. In this respect, both national and local authorities are expected to perform systematization and current state assessment of respected building stock, followed by a proposal for their energy refurbishment. Basic feature of this part of Serbian building stock is represented by the fact that almost all buildings (from one occupied by central government, through localscale administration buildings, to educational and medical care institutions) are made long before thermal-protection regulations were introduced. That indicates overall divergence from adopted codes and predefined standards in energy efficiency. On the other hand, these buildings are often founded of high architectural value and protected as building heritage, what significantly reduces possible options and energy refurbishment scenarios. Initial steps in implementation of adopted energy efficiency principles were made in Serbia during 2015, when in cooperation of German international cooperation organisation – GIZ and Faculty of Architecture from Belgrade, work has started on assessment and energy certification of public buildings. First energy certificates (energy passports) for public buildings in Serbia were issued, starting from three most valuable buildings of national authorities: Government building, The National Assembly, and The Palace of Serbia. At the same time, aiming to investigate their energy refurbishment potentials, technical brochures are prepared, showing possible, code-related, options for further energy improvement of buildings thermal envelope. This paper will present results obtained during energy-assessment and energy-certification process of this particular buildings, showing at the same time their specificity, that pretty much traces possible category and range of proposed energy refurbishment scenarios