Algorithm for calculating influence of power transformer oil temperature change on the accuracy of allacoustic non-iterative partial discharge localization

Ovaj rad razmatra čisto akustičku metodu za lokalizaciju parcijalnog pražnjenja u energetskom transformatoru. Ova metoda se zasniva na matematičkom modelu koji koristi multilateraciju, princip vremenske razlike kašnjenja signala i neiterativni matematički algoritam. U ovom modelu pretpostavlja se da akustički signal prolazi jedino kroz transformatorsko ulje i da je brzina akustičkog signala konstantna. Brzina akustičkog signala u velikoj meri zavisi od temperature transformatorskog ulja što znači da se i temperatura transformatorskog ulja smatra konstantnom. U realnim uslovima, sa aspekta fizike, termodinamike fluida, konstrukcije transformatora itd., ova pretpostavka je najblaže rečeno velika. Upravo zato se u ovom radu istražuje uticaj promene temperature transformatorskog ulja (promene brzine akustičkog signala) na preciznost razmatrane metode. Za tu namenu, dizajniran je algoritam i implementiran u programskom jeziku Visual C#. Na osnovu sprovedenih simulacija stečena su nova saznanja o interakciji između temperature transformatorskog ulja i položaja akustičkih senzora. Ova interakcija dovela je do značajne razlike u preciznosti neiterativnog matematičkog algoritma za različite položaje akustičkih senzora pri promeni temperature transformatorskog ulja. Kako bi se uočena interakcija maksimalno iskoristila za unapređenje preciznosti razmatrane metode, predloženi su određeni koraci za dalje istraživanje i razvoj.This article investigates the all-acoustic method for partial discharge localization in a power transformer. This method is based on mathematical model that uses multilateration with Time Difference of Arrival (TDOA) principle and non-itterative mathematical algorithm. In this model, it is assumed that acoustic signal propagates only through transformer oil and that the velocity of acoustic signal is constant. Acoustic signal velocity is largely dependent on transformer oil temperature meaning that oil temperature is also considered to be constant. In reality if we look from the perspective of physics, thermo dynamics of fluids, transformer construction etc. this approximation is enormous. Therefore, influence of power transformer oil temperature change (velocity of acoustic signal change) on the accuracy of this method is investigated. For that purpose special algorithm is designed and implemented in Visual C# programming language. Based on conducted simulations, further knowledge is gained about interaction between transformer oil temperature and placement of acoustic sensors. This interaction produced significant disparity in noniterative algorithm's accuracy for different sensor positions with oil temperature change. In order to fully take advantage of noticed interaction, certain steps for further research and development are proposed

Improvement of the Teaching Process in the Field of Built Heritage Studies Through a Multidisciplinary Approach to the Revitalisation and Adaptation of Belgrade‘ s Industrial Heritage: Hangar of the Old Belgrade Airport

Jedan od glavnih izazova očuvanja graditeljskog nasleđa u 21. veku odnosi se na mogućnosti njegove zaštite, revitalizacije i adaptacije u skladu sa potrebama savremenog života, uz istovremeno očuvanje svih njegovih vrednosti i autentičnosti. To ne podrazumeva samo identifikovanje, afirmisanje i promovisanje njegovih urbanističko-arhitektonskih i estetskih vrednosti, već i seta kulturno-istorijskih vrednosti za čije prepoznavanje je neophodno sagledati graditeljsko nasleđe kroz multidisciplinarni pristup – u okviru šireg društvenog konteksta. Stoga se u nastavi na Univerzitetu u Beogradu – Arhitektonskom fakultetu teži uspostavljanju jedinstvenog multidisciplinarnog pristupa revitalizaciji i adaptaciji industrijskog nasleđa, uz istovremeno očuvanje svih njegovih vrednosti i autentičnosti. Ovaj rad predstavlja sistematski prikaz metodologije istraživanja industrijskog nasleđa, primenjene na studiji slučaja Hangara Starog aerodroma u Novom Beogradu, koji je prepoznat kao značajan spomenik industrijskog nasleđa i tehničke kulture 20. veka. Kroz analizu studentskih idejnih rešenja za revitalizaciju i adaptaciju objekta Hangara Starog aerodroma, dat je prikaz primenjene metodologije istraživanja, pristupa zaštiti, revitalizaciji i prezentaciji svih vrednosti i autentičnosti industrijskog nasleđa, kao i prikaz upotrebe spomenika tehničke kulture u savremenom kontekstu. Na taj način, ostvaren je kontinuitet trajanja industrijskog nasleđa i obezbeđen njegov opstanak za buduće generacije. Poseban doprinos rada ogleda se u predlozima za revitalizaciju i adaptaciju Hangara Starog aerodroma, čime je dat i značajan prilog unapređenju nastavnog procesa u oblasti proučavanja graditeljskog nasleđa na Univerzitetu u Beogradu – Arhitektonskom fakultetu.One of the main challenges in preserving built heritage in the 21st century relates to the possibilities of its revitalisation and adaptation following modern needs while protecting its values and authenticity. Protection of built heritage does not mean only the identification, affirmation and promotion of its urban-architectural and aesthetic values but also a set of cultural-historical values for which it is necessary to recognise built heritage through a multidisciplinary approach – within the broader social context. Therefore, the teaching process at the University of Belgrade – Faculty of Architecture aims to establish a unique multi-disciplinary approach to the industrial heritage's revitalisation and adaptation. This paper shows an industrial heritage research methodology systematic representation, applied to the case study of the Hangar of the Old Airport in New Belgrade as an important monument of industrial heritage and technical culture of the 20th century. Through student proposals for revitalisation and adaptation, the applied methodology, the approach for preservation, revitalisation and presentation of industrial heritage's values and the preservation of its authenticity, as well as a description of the use of industrial heritage's values, have been given; which ensured the continuity and survival of industrial heritage for future generations. A special contribution refers to the proposals for preserving the Hangar, which contributes to the teaching process improvement in the built heritage studies at the University of Belgrade – Faculty of Architecture

Examined in Theory – Applicable in Practice: Potentials of Sustainable Industrial Heritage Conservation in a Contemporary Context – The Case of Belgrade

The industrial heritage of the city of Belgrade is the focus of this research, which highlights the possibilities of preserving industrial heritage from the perspective of a contemporary context and sustainable development. Guided by theoretical principles on the preservation of cultural and industrial heritage, their values, authenticity and spirit of place, as well as the idea of the necessity of integrating industrial heritage into the contemporary context, this paper aims to examine the possibilities for the preservation of industrial heritage following theoretically established principles, with the introduction of new uses and sustainable solutions. The analysis of the case studies of Belgrade’s industrial heritage presented in this paper results from research conducted by the teachers, associates and students of the University of Belgrade, Faculty of Architecture. The research focuses on the possibilities of translating the principles of preserving cultural and industrial heritage from their theoretical definition to practical application. The students’ conceptual solutions for protection, revitalisation and presentation of the analysed case studies represent the research results. An important aspect of this paper is defining the criteria for valorising students’ conceptual solutions, which are aligned with the principles of preserving cultural heritage and establishing sustainable development. The valorisation of students’ conceptual solutions through a defined set of criteria indicates real possibilities for the simultaneous preservation of all the values of industrial heritage and its transformation into a social, ecological and economic resource of the contemporary city

Cardiac Arrest in a Patient with Ebstein’s Anomaly without Accessory Pathways

We describe a case report of a patient with cardiac arrest and Ebstein’s anomaly. This case report shows us necessity for arrhythmia evaluation and sudden death risk stratification even in asymptomatic patients. Prophylactic ICD im- plantation in this patient population is limited to observational studies and the selection of patients is impeded by the absence of randomized trials and weak predictors

Colonization of sunflower seed with Alternaria alternata

Sunflower (Helianthus annuus L.) is one of the most important oilseed crops throughout the world, and in Serbia it is grown on about 160,000 to 210,000 ha. Alternaria alternata (Fr.) Keissler has been detected as the most frequent seed-borne pathogen, able to infect a wide variety of plant species in different countries. During a routine seed quality control and seed health testing analysis of sunflower seed in 2018-2019, according to ISTA Rules, Alternaria spp. infection was observed on an average of 18%. The aim of this study was the isolation and identification of Alternaria spp. based on their morphological characteristics and molecular analyses. Isolation of the pathogen was carried out by transferring infected seeds onto a potato dextrose agar (PDA), and subsequent incubation at 25°C. Seven days later, 21 isolates formed circular, smooth, grey to brownish-black colonies, with concentric zones of very intensive sporulation. Conidiophores were branched, solitary or in small groups, brown to olivaceous brown, ranging from 128 to 232 µm. All isolates were subcultured onto a PDA using a single spore technique

A versatile framework for resource-limited sentiment articulation, annotation, and analysis of short texts.

Choosing a comprehensive and cost-effective way of articulating and annotating the sentiment of a text is not a trivial task, particularly when dealing with short texts, in which sentiment can be expressed through a wide variety of linguistic and rhetorical phenomena. This problem is especially conspicuous in resource-limited settings and languages, where design options are restricted either in terms of manpower and financial means required to produce appropriate sentiment analysis resources, or in terms of available language tools, or both. In this paper, we present a versatile approach to addressing this issue, based on multiple interpretations of sentiment labels that encode information regarding the polarity, subjectivity, and ambiguity of a text, as well as the presence of sarcasm or a mixture of sentiments. We demonstrate its use on Serbian, a resource-limited language, via the creation of a main sentiment analysis dataset focused on movie comments, and two smaller datasets belonging to the movie and book domains. In addition to measuring the quality of the annotation process, we propose a novel metric to validate its cost-effectiveness. Finally, the practicality of our approach is further validated by training, evaluating, and determining the optimal configurations of several different kinds of machine-learning models on a range of sentiment classification tasks using the produced dataset

THE INFLUENCE OF BUSINESS INFORMATION SYSTEMS ON SERBIAN COMPANIES BUSINESS PERFORMANCES

Industrial era has been replaced with the information era of development. Under such influences of surroundings, all the companies have been forced to introduce information systems in their organizations in order to be competitive. Since Serbia technologically tags along the developed part of Europe and bearing in mind that adjusting to changes is the condition of success, this paper aims at answering the question: how many companies in Serbia have an information system, when and how was it introduced and which fields of business were integrated in that way? We came to the conclusion that all the interviewed business subjects use the information system to a greater or lesser extent and mostly for the needs of accounting, sales and supply and that in most cases all fields of business were integrated into a unique IS, which led to the notable savings in business

The Possibilities of Preservation, Regeneration and Presentation of Industrial Heritage: The Case of Old Mint “A.D.” on Belgrade Riverfront

This paper aims to explore industrial heritage of Belgrade that is located in the city center and therefore, has considerable potential for future architectural and urban development of the Serbian capital. The whole Belgrade riverfront area along the Sava and the Danube Rivers has a large number of abandoned industrial buildings that have significant value and need to be preserved and revitalized. This paper represents a research project conducted by lecturers at the Faculty of Architecture in Belgrade in the course History and Theory 1—Visual Culture in Architectural Theory and Practice. In order to provide productive research, we have employed the case study method based on the old Mint “A.D.”, which we have chosen as a characteristic example of Belgrade’s industrial heritage architecture. An important goal of this research is to provide professional information and raise public awareness about the importance and potential of industrial heritage for the future economic, cultural, social and tourist development of the city. This paper analyzes possibilities to comprehend the problems of the city’s industrial heritage protection regarding its historical and urban context, its genesis, authenticity, identity, cultural, architectural, economic, social, productive, creative and environmental values. According to that, the main goal of this research is concentrated on the sustainable preservation of specific cultural tangible and intangible values, spirit of the place, city identity and historic cityscape values that characterize industrial heritage in the social, cultural, natural and built environmental systems