TWO-DIMENSIONAL GMM-BASED CLUSTERING IN THE PRESENCE OF QUANTIZATION NOISE

In this paper, unlike to the commonly considered clustering, wherein data attributes are accurately presented, it is researched how successful clustering can be performed when data attributes are represented with smaller accuracy, i.e. by using the small number of bits. In particular, the effect of data attributes quantization on the two-dimensional two-component Gaussian mixture model (GMM)-based clustering by using expectation–maximization (EM) algorithm is analyzed. An independent quantization of data attributes by using uniform quantizers with the support limits adjusted to the minimal and maximal attribute values is assumed. The analysis makes it possible to determine the number of bits for data presentation that provides the accurate clustering. These findings can be useful in clustering wherein before being grouped the data have to be represented with a finite small number of bits due to their transmission through the bandwidth-limited channel.

Ensemble of radial basis neural networks with k-means clustering for heating energy consumption prediction

U radu je predložen i prikazan ansambl neuronskih mreža za predviđanje potrošnje toplote univerzitetskog kampusa. Za obučavanje i testiranje modela korišćeni su eksperimentalni podaci. Razmatrano je poboljšanje tačnosti predviđanja primenom k-means metode klasterizacije za generisanje obučavajućih podskupova neuronskih mreža zasnovanih na radijalnim bazisnim funkcijama. Korišćen je različit broj klastera, od 2-5. Izlazi članova ansambla su kombinovani primenom aritmetičkog, težinskog i osrednjavanja metodom medijane. Pokazano je da ansambli neuronskih mreža ostvaruju bolje rezultate predviđanja nego svaka pojedinačna mreža članica ansambla. PR Data used for this paper were gathered during study visit to NTNU, as a part of the collaborative project: Sustainable energy and environment in Western Balkans.For the prediction of heating energy consumption of university campus, neural network ensemble is proposed. Actual measured data are used for training and testing the models. Improvement of the prediction accuracy using k-means clustering for creating subsets used to train individual radial basis function neural networks is examined. Number of clusters is varying from 2 to 5. The outputs of ensemble members are aggregated using simple, weighted and median based averaging. It is shown that ensembles achieve better prediction results than the individual network

Various multistage ensembles for prediction of heating energy consumption

Feedforward neural network models are created for prediction of daily heating energy consumption of a NTNU university campus Gloshaugen using actual measured data for training and testing. Improvement of prediction accuracy is proposed by using neural network ensemble. Previously trained feed-forward neural networks are first separated into clusters, using k-means algorithm, and then the best network of each cluster is chosen as member of an ensemble. Two conventional averaging methods for obtaining ensemble output are applied; simple and weighted. In order to achieve better prediction results, multistage ensemble is investigated. As second level, adaptive neuro-fuzzy inference system with various clustering and membership functions are used to aggregate the selected ensemble members. Feedforward neural network in second stage is also analyzed. It is shown that using ensemble of neural networks can predict heating energy consumption with better accuracy than the best trained single neural network, while the best results are achieved with multistage ensemble

Multistage ensemble of feedforward neural networks for prediction of heating energy consumption

Feedforward neural network models are created for prediction of heating energy consumption of a university campus. Actual measured data are used for training and testing the models. Multistage neural network ensemble is proposed for the possible improvement of prediction accuracy. Previously trained feed-forward neural networks are first separated into clusters, using k-means algorithm, and then the best network of each cluster is chosen as a member of the ensemble. Three different averaging methods (simple, weighted, and median) for obtaining ensemble output are applied. Besides this conventional approach, single radial basis neural network in the second level is used to aggregate the selected ensemble members. It is shown that heating energy consumption can be predicted with better accuracy by using ensemble of neural networks than using the best trained single neural network, while the best results are achieved with multistage ensemble

DEPOPULATION OF RURAL AREAS

This paper indicates the depopulation of the rural areas in Serbia during the period from 1961 to 2011. Based on the research on a number of indicators, there have been significant changes in the rural society and the rural areas in Serbia, primarily expressed through the processes of: depopulation, ageing and migrations that have affected socioeconomic and rural development. The theoretical framework for the sociological study of the villages was based on the monographic method for the qualitative and quantitative description of the village settlements and regions. The analytical method was used for the interpretation of cause and functional relations within the rural area. The analysis of documents, the official statistical data and publications (Population and households of Serbia according to the 2002 census, Population of Serbia at the beginning of the 21st century, Villages in Serbia; the changes in structure and the problem of sustainable development. Census of Population, Households and Dwellings in 2011 (Census of Agriculture 2012 related to the process of depopulation of the rural areas in Serbia were used for the research. The changes occurred in the rural areas of Serbia have resulted in the depopulation of many villages which are without inhabitants now. Today’s population structure in villages shows the trend of reducing the share of the young population and the increase in elderly population, all of which affect the demographic picture of the rural areas in Serbia. Such situation leads to the change in the structure of the working age population, with the further tendency of the village depopulation, especially in the mountainous areas where the fertile contingent has almost disappeared

Styles of behavior of secondary school students in conflict situations with peers

Učenici kаo budući kreаtori društvenih promenа trebalo bi u interpersonalnim odnosima da neguju kulturu dijаlogа i uvаžаvаnjа rаzličitosti. Sposobnost komunikаcije i sаrаdnje su veštine koje se uče i čijim ovlаdаvаnjem se može nаći аdekvаtаn nаčin postupаnjа u konfliktimа. Stilovi postupanja u konfliktima jesu saradnja, nadmetanje, udovoljavanje, izbegavanje i kompromis. Konstruktivnom razmenom mišljenja u konfliktu učenici se uče da brane svoje stavove, ali i da sagledavaju i uvažavaju tuđe. Ukoliko se ne razreše, konflikti mogu dovesti do nasilničkog ponašanja. Cilj rаdа je dа se ispitаju stilovi ponašanja učenikа srednje škole u konfliktnim situacijama sa vršnjacima. Uzorаk istrаživаnjа čini 195 učenikа prvog i drugog rаzredа srednje škole u Nišu. Zа prikupljаnje podаtаkа korišćen je Rаhimov inventаr orgаnizаcijskog konfliktа. Za obradu podataka upotrebljen je Pirsonov hi kvadrat test, t test i ANOVA. Rezultаti pokаzuju dа kod manje od polovine učenikа preovlаdаvа sаrаdnjа kаo stil ponаšаnjа u interаkciji sа vršnjаcimа. Pored sаrаdnje nаjčešće se konfliktu pristupа nаdmetаnjem, izbegаvаnjem i kompromisom, dok je udovoljаvаnje drugimа nаjmаnje zаstupljeno. Zаključuje se dа učenici u odnosimа sa drugimа uvаžаvаju sopstvene i tuđe potrebe, dа školski uspeh utiče nа stil postupаnjа u konfliktimа, dok pol učenikа ne utiče nа rаzlike u nadmetanju i udovoljavanju kao stilu postupаnjа u konfliktnim situacijama. Učenici čiji je školski uspeh odličan i vrlo dobar najčešće konfliktu pristupаju sаrаdnjom, dok učenici čiji je školski uspeh dobar i dovoljan nаjčešće pristupаju nаdmetаnjem. Realizacija programa vršnjačke medijacije u školi jedan je od načina prevencije konflikata. Kako rezultati pokazuju da učenici čiji je školski uspeh bolji adekvatnije postupaju u konfliktima, potrebno je angažovati ih kao vršnjačke medijatore koji će raditi na prevenciji vršnjačkih konflikataAs future creators of social changes, the students should nurture the culture of dialogue and respect for differences in interpersonal relationships. Communication and cooperation are the skills that can be learnt, and by mastering them one can find the appropriate way to behave in conflicts. Styles of behaviour in conflicts are cooperation, competition, pleasing, avoiding and compromise. By constructive exchange of opinion in conflicts, the students are taught to defend their attitudes and, in addition, to identify and respect other students’ attitudes. Unless they are resolved, the conflicts can lead to violent behaviour. The objective of this paper is to examine the styles of behaviour of secondary school students in conflict situations with peers. The sample of the research comprises 195 the first and second grade students of a high school in Niš. Rahim Organizational Conflict Inventory was used to collect data. Pearson’s Chi-square test, t test and ANOVA were used for data processing. The results indicate that cooperation, as a style of behaviour in interaction with peers, prevails in less than a half of students. Beside cooperation, the conflict is chiefly approached by competition, avoidance and compromise, whereas pleasing others is least represented. It can be concluded that in interactions, students respect their own and other people’s needs, that academic performance affects the style of behaviour in conflicts, whereas the students’ gender makes no difference to the competing and pleasing others as a style of behaviour in conflicts. The students who have excellent and very good academic performance mostly resolve conflicts by cooperation, whereas the students with good and sufficient academic performance mostly resolve conflicts by competition. Implementation of peer mediation programme in the school is one of the ways of preventing conflicts. Since the results indicate that students with better academic performance approach the conflicts more appropriately, it is necessary to engage them as peer mediators working on prevention of peer conflicts.Zbornik rezimea / 24. Međunarodna naučna konferencija "Pedagoška istraživanja i školska praksaBook of abstracts / 24th International Scientific Conference "Educational Research and School Practice

Strengthening the Social Sustainability of Super-Blocks: Belgrade's Emerging Urban Hubs

Focusing on the social aspect of sustainability, this article provides insight into the process of spatial and functional reconsideration of open public spaces in two selected super-blocks in Belgrade, Serbia. Although their spatial typology is similar, one of them was created during the 1960s in New Belgrade, a new administrative center of the city based on the principles of functionalism, while the other one was built during the 1970s, as a part of urban reconstruction conducted in the central areas of Belgrade (Vračar municipality). The beginning of the 21st century has brought new challenges to open public spaces, reflecting the post-transitional changes of the Serbian socio-economic context, as well as the contemporary urban needs of inhabitants. Consequently, both blocks have developed new gathering places for their local communities, although applying two different approaches, spontaneous/informal (New Belgrade) and formal (Vračar). Considering the specificities of both initiatives and the relationship between local communities and the open public spaces of super-blocks, the comparative analysis is conducted in order to identify the occurring social, spatial, and functional modifications, and the achieved level of social sustainability

Optimization of the extraction process from Thymus serpyllum L. herb, biological activities and encapsulation of extracts

Врста Thymus serpyllum L. (Lamiaceae) или мајчина душица представља вишегодишњу зељасту биљку богату полифенолима који показују антиоксидативни, антимикробни, антихипертензивни, спазмолитични, антиинфламаторни, антиканцерогени, антиалергијски и анксиолитични ефекат. Оптимизација процеса екстракције представља први корак у добијању максималног приноса активних принципа из биљних извора као безбедне и природне алтернативе синтетским компонентама. Нестабилност полифенола у току процеса производње, дистрибуције и чувања намирница, као и у условима гастроинтестиналног тракта, ограничава њихову активност и потенцијалне корисне ефекте на здравље људи. Инкапсулација полифенола доводи до превазилажења поменутих недостатака, ублажавања горког укуса полифенола и побољшања њихове биорасположивости и полувремена елиминације...Thymus serpyllum L. (Lamiaceae), well-known as wild thyme, is a perennial subshrub, abundant in polyphenols compounds, which possess antioxidant, antimicrobial, antihypertensive, antispasmodic, antiinflammatory, anticarcinogenic, anti-allergic and anxiolytic properties. The optimization of extraction represents the first step in obtaining the maximum yield of active compounds from plant sources, which are safe and natural alternative to synthetic components. Polyphenols instability during food processing, distribution or storage, and in the gastrointestinal tract, limits their activity and potential health benefits. The encapsulation of polyphenols can overcome the drawbacks of their instability, alleviate unpleasant tastes or flavors, and improve the bioavailability and half-life of the compounds..

Dynamic of particular classes of time-delay systems defined over finite time interval

U ovoj doktorskoj disertaciji su razmatrani problemi dinamičke analize posebnih klasa sistema sa čistim vremenskim kašnjenjem, kao i njihovo ponašanje na konačnom. U uvodnom delu akcenat izlaganja stavljen je na proučavanje suštinskih osobina singularnih sistema, sistema sa kašnjenjem i singularnih sistema sa kašnjenje, kao i na njihove diskretene analogane. U tom smislu razmatrana su pitanja koja se tiču egzistencije i jedinstvenosti rešenja, problema impulsnih ponašanja i konzistentnih početnih uslova, kauzalnosti i funkcija početnih uslova razmatranog sistema. Detaljan pregled do sada postignutih rezultata na polju izučavanja neljapunovske stabilnosti oličene u konceptu stabilnosti na konačnom vremenskom intervalu i praktične stabilnosti na ove klase sisteme, iscrpno je dat u odgovarajućem poglavlju. Disertacija je prvenstveno posvećena osnovnom pianju koje je vezano za teoriju a posebno za primenu automatskog upravljanja u praksi, tj. za pitanje stabilnosti u tzv. neljapunovskom smislu, a to pitanje je bilo rešavano sa dva stanovišta: metode koji koristi deskriptivni prilaz i postupke koji se zasnivaju na primeni klasičnih algebarskih matričnih nejednakosti (Jensenova i Kopelova nejednačina), imajući u vidu da poslednje pomenuti prilaz redukuje probleme upravljanja na rešavanje jednostavnih algebarskih nejednačina, koje se lako sprovode standardnim numeričkim procedurama, a oba prilaza vode ka samo dovoljnim uslovima stabilnosti primenjenog koncepta, što je sasvim prihvatljivo sa inženjerske tačke gledišta. U prvom slučaju, za izvoĎenje dovoljnih uslova stabilnosti na konačnom vremenskom intervalu, korišćene su funkcionali tipa Ljapunov-Krsovski. Za razliku od nekih ranijih rezultata, ovi funkcionali ne moraju da zadovoljavaju neke stroge matematičke uslove, kao što je pozitivna odreĎeneost u celom prostoru stanja, kao i da ne poseduju negativnu odreĎenost njihovih izvoda duž kretanja sistema. U svim slučajevima od interesa, numeričkim primerima datim u ovoj disertaciji, dodatno je potvrĎena primena predloženih novih metodologija, kao i analitičko sračunavanje i iznalaženje uslova stabilnosti. Konačno, utvrĎeno je da su izvedeni dovoljni uslovi manje restriktivni u poreĎenju sa ranije izvedenim rezultatima. Analogni zaključci mogu se izvesti i za rezultate dobijene na polju izučavanja praktične stabilnosti. Još neki manje značajni doprinosi pruženi su u sferi proučavanja osobina robusnosti sistema i njihove stabilizacije...In this doctoral thesis the problems of dynamical analysis of particular class of control time delay systems were considered, as well as their behavior on finite and time intervals. Following the introduction disscusion emphasis has been put on the peculiar properties of singular, time delay and singular time delay systems, as well as on theirs discrete counterparts. In that sense the questions, concerning the existence and uniqueness of the solutions, the problems of impulsive behavior, consistent initial conditions, causality and functions of initial conditions of the system itself. On overview of the modern stability frameworks has been presented, starting from the so called non-Lyapunov concepts: finite time stability and practical stability in particular. A historical overview of ideas, concepts and results has been presented and the key contributions have been highlighted through key papers from the modern literature. This dissertation is mostly dedicated to the main question of control engineering, eg., to the question of stabilitly in Non-Lyapunov sense, two main lines of research were established: the qvasy descriptive methodology and the approach based on classical matrix algebraic inequalites (Jensen's and Coppel inequality), the latter being known to reduce control tasks to simple algebraic conditions easily solvable by numerical computation, in both casses leading to the sufficient stability conditions, only, what is more than acceptable for the engineering point ov view. In the first case for the derivation of the finite time stability sufficient conditions, the Lyapunov-Krassovski functionals were used. Unlike in the previously reported results, the functionals did not have to satisfy some strict mathematical conditions, such as positivity in the whole state space and possession of the negative derivatives along the system state trajectories. In all cases, of interest, the numerical examples presented in this study additionally clarified the implementation of the new methodologies, and the calculations and analitical determination of the stability conditions. Finally, it was found that the proposed sufficient conditions were less restrictive compared to the ones previously reported. The analogous results have been derived for practical stability. Some others contributions has been given through some disscussion of concept of stability robustness and stabilization procedure..