Kratkoročna prognoza potrošnje električne energije zasnovana na metodama veštačke inteligencije

The topic of this dissertation is a short-term load forecasting using artificial intelligence methods. Three new models with least squares support vector machines for nonlinear regression are proposed. First proposed model is a model with forecasting in two stages. This model use additioal feature, maximum daily load which is not known for day ahead. Forecating of maximum daily load is obtained in the first stage. This forecasted value is used in second stage, where forecasting of hourly load is done. Model with feature selection, using mutual information for selection criteria, is a second proposed model. This model tries to find an optimal feature set for a given problem. Forecasting model based on an incremental update scheme is a third proposed model. This model is based on the incremental update of the initial training set by adding new instances into it as soon as they become available and throwing out the old ones. Then the model is trained with new training set. By this approach the evolving nature of the load pattern is followed and the model performance is preserved and improved. For models evaluation, the forecasting of hourly loads for one year is done. Electrical consumption data for the City of Niš, which have about 260000 habitans and average daily demand of 182 MW, is used for testing. Double sesonal ARIMA and Holt-Winters as representatives of clasical models and artificial neural networks, least squares support vector machines and relevance vector machines as representatives of artificial models, are used for models evaluation. For a measure of accuracy, mean absolute percentage error, symetrical mean absolute percentage error, square root mean error and absolute percentage error are used. Obtained results show that the best model is model with incremental update scheme, followed by double sesonal ARIMA and artificial neural networks models. The worst results are obtained by relevance vector machines and double sesonal Holt-Winters models. It has been shown that the best model could be successfully used with the short-term load forecasting problem

Trajectory-based interpretation of laser light diffraction by a sharp edge

In the diffraction pattern produced by a half-plane sharp edge when it obstructs the passage of a laser beam, two characteristic regions are noticeable. There is a central region, where it can be noticed the diffraction of laser light in the region of geometric shadow, while intensity oscillations are observed in the non-obstructed area. On both sides of the edge, there are also very long light traces along the normal to the edge of the obstacle. The theoretical explanation to this phenomenon is based on the Fresnel-Kirchhoff diffraction theory applied to the Gaussian beam propagation behind the obstacle. Here we have supplemented this explanation by considering electromagnetic flow lines, which provide a more complete interpretation of the phenomenon in terms of electric and magnetic fields and flux lines, and that can be related, at the same time, with average photon paths.Comment: 13 pages, 5 figure

Microwave Assisted Esterification of Aryl/Alkyl Acids Catalyzed by N-Fluorobenzenesulfonimide

The susceptibility of the carbonyl group towards nucleophilic attack affords the construction of various organic compounds. Thus, investigations of carbonyl activation applying greener methodologies are highly important. In the present work, among the investigated N-halo compounds, N-fluorobenzenesulfonimide (NFSi) has been found as an efficient and selective catalyst in the reaction of direct esterification of aryl and alkyl carboxylic acids supported by microwave (MW) irradiation. The comprehensive esterification of different benzoic acids and mono-, di-and tri-carboxy alkyl derivatives was performed, whereby significant reaction time reductions were achieved. The presented method used NFSi as an easily manipulatable, non-metal, water-and air-tolerant catalyst, allowing simple synthetic and isolation procedures and energy saving, compared to conventional methodologies. Importantly, in contrast to esterification under thermal conditions, where N-halo compounds behave as pre-catalysts, in the MW-supported protocol, a distinct reaction mechanism has been proposed that assumes NFSi as a sustainable catalyst. Moreover, a scale-up of the industrially important derivative was performed

Antiproliferative and antimigratory effects of 3-(4-substituted benzyl)-5-isopropyl-5-phenylhydantoin derivatives in human breast cancer cells

In this study, a series of synthesized 3-(4-substituted benzyl)-5-isopropyl-5-phenylhydantoin derivatives as a potential antiproliferative and antimigratory agents were investigated. The possible antitumor mechanisms of investigated hydantoin derivatives were examined on human breast cancer cell line MDA-MB-231. The cells were treated with different concentrations of compounds (from 0.01 mu M to 100 mu M) during 24 h and 72 h. The proliferation index, nitric oxide production, apoptosis rate, and migration capacity were measured. The cell invasion potential was examined by measuring the level of MMP-9 and COX-2 gene expression. All tested compounds expressed antiproliferative activity and induced dose- and time-dependent increase in the level of nitrites. The investigated molecules significantly decreased cell survival rate, migration capacity and the expression levels of genes included in the process of tumor invasion. Obtained data suggest that the tested hydantoin derivatives express considerable antitumor activity by reducing cell division rate, elevating apoptosis level, and inhibiting the motility and invasiveness of breast cancer cells. The results obtained in this study indicate that investigated compounds express potential as a novel chemotherapeutic agents against breast cancer growth and progression. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of King Saud University

Maligni tumori kod Labrador retrivera koji se koriste za pronalaženje narkotika

The two corpses of police dogs, of Labrador retriever breed used for fi nding narcotics, were sent to the Scientific Veterinary Institute 'Novi Sad', and examined post-mortem, in order to determine the cause of death. Post-mortem examination revealed the presence of neoplastic changes in the mandibular region, pulmonary parenchyma and axillary region. The samples of neoplastic changes were sent to the Laboratory of Patohistology within the Faculty of Veterinary Medicine, University of Belgrade, in order to specify the diagnosis. Histopathology examination revealed an adenocarcinoma in lungs and haemangioendothelioma in axillary region. Is there any role of drug sniffing on the occurrence of neoplasia in Labrador retriever breed is still unknown, but it could be an important factor in the development of neoplasia in these dogs.Dva leša policijskih službenih pasa, rase Labrador retriver koji se koriste za pronalaženje narkotika, dostavljeni su u Naučni institut za veterinarstvo 'Novi Sad', kako bi se na osnovu patomorfološkog pregleda utvrdio uzrok smrti. Tokom obdukcije utvrđeno je prisustvo neoplastičnih promena u mandibularnoj regiji, plućnom parenhimu i aksilarnoj regiji. Uzorci promenjenog tkiva dostavljeni su na Fakultet veterinarske medicine, Univerziteta u Beogradu, u laboratoriju za patohistologiju kako bi se odredila tačna dijagnoza. Patohistološkim nalazom utvrđeno je prisustvo adenokarcinoma u plućima i hemangioendotelioma u predelu aksilarne regije. Kakvu ulogu može imati udisanje narkotika na pojavu neoplazmi kod Labrador retrivera još uvek nije poznato, ali se pretpostavlja da to može biti jedan od faktora u nastanku neoplastičnih promena kod ovih službenih pasa

Defining the optimum shape of the cross-flow turbine semi-spiral case by the Lagrange’s principle of virtual work

Određivanje optimalnog oblika strujnog prostora sa minimumom negativnih pojava (mrtva voda, nestacionarne pojave i dr) je vrlo važan zadatak inženjera hidrotehnike. U ovom radu se prikazuje metoda koja je zasnovana na Lagranžeovom principu virtuelnog rada. Metoda je primenjena pri oblikovanju uvodne komore Banki turbine.Determination of the optimal flow field boundary with minimum undesirable phenomena (dead water zones, unsteady fluid flow, etc) is a very important task in hydraulic engineering. This paper presents one method based on the Lagrange’s principle of virtual work. The method was used for defining intake case of cross-flow(Bunki) turbine

Fluid boundaries shaping using the method of kinetic balance

Fluid flow in curved channels with various cross-sections, as a common problem in theoretical and applied fluid mechanics, is a very complex and quite undiscovered phenomenon. Defining the optimum shape of the fluid flow boundaries, which would ensure minimum undesirable phenomena, like "dead water" zones, unsteady fluid flow, etc., is one of the crucial hydraulic engineering’s task. Method of kinetic balance is described and used for this purpose, what is illustrated with few examples

Defining the optimum shape of the cross-flow turbine semi-spiral case by the Lagrange’s principle of virtual work

Određivanje optimalnog oblika strujnog prostora sa minimumom negativnih pojava (mrtva voda, nestacionarne pojave i dr) je vrlo važan zadatak inženjera hidrotehnike. U ovom radu se prikazuje metoda koja je zasnovana na Lagranžeovom principu virtuelnog rada. Metoda je primenjena pri oblikovanju uvodne komore Banki turbine.Determination of the optimal flow field boundary with minimum undesirable phenomena (dead water zones, unsteady fluid flow, etc) is a very important task in hydraulic engineering. This paper presents one method based on the Lagrange’s principle of virtual work. The method was used for defining intake case of cross-flow(Bunki) turbine

Fluid boundaries shaping using the method of kinetic balance

Fluid flow in curved channels with various cross-sections, as a common problem in theoretical and applied fluid mechanics, is a very complex and quite undiscovered phenomenon. Defining the optimum shape of the fluid flow boundaries, which would ensure minimum undesirable phenomena, like "dead water" zones, unsteady fluid flow, etc., is one of the crucial hydraulic engineering’s task. Method of kinetic balance is described and used for this purpose, what is illustrated with few examples

STOCK MARKET TREND PREDICTION USING SUPPORT VECTOR MACHINES

The aim of the paper was to outline a trend prediction model for the BELEX15 stock market index of the Belgrade stock exchange based on Support Vector Machines (SVMs). The feature selection was carried out through the analysis of technical and macroeconomics indicators. In addition, the SVM method was compared with a "similar" one, the least squares support vector machines - LS-SVMs to analyze their classification precisions and complexity. The test results indicate that the SVMs outperform benchmarking models and are suitable for short-term stock market trend predictions