Papers by Djordje Petrovic
Serbian Journal of Engineering Management, 2020
In this paper we applied twinning algorithm for product that are sold via e-commerce platform. To... more In this paper we applied twinning algorithm for product that are sold via e-commerce platform. To establish relatively homogenous product groups that were on sale on this e-commerce platform during the last year, it was necessary to form predictive mathematical model. We determined set of relevant variables that will represent group attributes, and we applied K-means algorithm, Market Basket model and Vector Distance model. Based on analysis of basic and derived variables, fixed number of clusters was introduced. Silhouette index was used for the purposes of detecting whether these clusters are compact. Using these cluster separations, we created models that detect similar products, and try to analyze probability of sales for each product. Analysis results can be used for planning future sales campaigns, marketing expenses optimization, creation of new loyalty programs, and better understanding customer behavior in general.
Facta Universitatis, Series: Mathematics and Informatics, 2019
Text mining to a great extent depends on the various text preprocessing techniques. The preproces... more Text mining to a great extent depends on the various text preprocessing techniques. The preprocessing methods and tools which are used to prepare texts for further mining can be divided into those which are and those which are not language-dependent. The subject matter of this research was the analysis of the influence of these methods and tools on further text mining. We first focused on the analysis of the influence on the reduction of the vector space model for the multidimensional represen-tation of text documents. We then analyzed the influence on calculating text similarity, which is the focus of this research. The conclusion we reached is that the implemen-tation of various text preprocessing methods in the Serbian language, which are used for the reduction of the vector space model for the multidimensional representation of text document, achieves the required results. But, the implementation of various text preprocessing methods specific to the Serbian language for the purpose o...
Computer Science and Information Systems, 2018
This document employs a statistical approach in exploring language and extracting linguistic form... more This document employs a statistical approach in exploring language and extracting linguistic forms there contained, so as to identify the linguistic forms which are most frequently used in legal documents. Thus retrieved data, as the second part of this paper shows, can be used to research information, analyze references and links, trace pathways between correlating legal documents and establish the relevance of legal documents on the grounds of their mutual correlation. The retrieved data can further be utilized in various other manners. The methodology of this research and thus attained information form a good basis and act as input data for numerous further analyses.
In this paper we applied twinning algorithm for product that are sold via e-commerce platform. To... more In this paper we applied twinning algorithm for product that are sold via e-commerce platform. To establish relatively homogenous product groups that were on sale on this e-commerce platform during the last year, it was necessary to form predictive mathematical model. We determined set of relevant variables that will represent group attributes, and we applied K-means algorithm, Market Basket model and Vector Distance model. Based on analysis of basic and derived variables, fixed number of clusters was introduced. Silhouette index was used for the purposes of detecting whether these clusters are compact. Using these cluster separations, we created models that detect similar products, and try to analyze probability of sales for each product. Analysis results can be used for planning future sales campaigns, marketing expenses optimization, creation of new loyalty programs, and better understanding customer behavior in general.
Objectives: The aims of this paper are: 1. To investigate spontaneous changes in fetal presentati... more Objectives: The aims of this paper are: 1. To investigate spontaneous changes in fetal presentation during the second half of gestation in guinea pig fetus, 2. to observe provoked changes of fetal presentation, by passive positioning fetus into an upside-down position and “sitting” position. Eight fetuses from singleton pregnancies were included. Experimental design: Ultrasound examinations (Toshiba Nemio SSA-550A apparatus) were started on the 26 th day of gestation (GD). Each fetus was examined 2-3 times in each 5-day interval until the end of gestation. First the spontaneous orientation of fetus was determined by tracking along the longitudinal and transversal axes of the fetus with the ultrasound probe. Then the fetus was brought into a head-down position relative to gravity for 5 minutes. The examination was repeated with the fetus in the head-up position. Results: In the period from the 26 th – 30 th GD in 7 of 21 observations spontaneous changes of presentation were observed....
Journal of Pain Research, 2016
Fetal pain remains a controversial subject both in terms of recognizing its existence and the tim... more Fetal pain remains a controversial subject both in terms of recognizing its existence and the time-frame within which it appears. This article investigates the hypothesis that pain perception during development is not related to any determined structures of the central nervous system (CNS), on the contrary, the process of perception could be made with any structure satisfying conditions that the perception of pain is the organization, identification, and interpretation of sensory information in order to represent and understand the environment. According to this definition, chronic decerebrate and decorticate experimental animals, anencephalic, and hydranencephalic patients demonstrate that the basic, most general, appropriate interaction with the environment can be achieved with a functional mesodiencephalon (brain stem, and diencephalon) as the hierarchically highest structure of the CNS during development. In intact fetuses, this structure shows signs of sufficient maturation starting from the 15th week of gestation. Bearing in mind the dominant role of the reticular formation of the brain stem, which is marked by a wide divergence of afferent information, a sense of pain transmitted through it is diffuse and can dominate the overall perception of the fetus. The threshold for tactile stimuli is lower at earlier stages of gestation. The pain inhibition mechanisms are not sufficiently developed during intrauterine development, which is another factor that leads to increased intensity of pain in the fetus. As a conclusion it could be proposed that the fetus is exposed to rudimentary painful stimuli starting from the 15 th gestation week and that it is extremely sensitive to painful stimuli.
Megatrend revija, 2016
The purpose of this paper is to determine whether there is a statistically significant influence ... more The purpose of this paper is to determine whether there is a statistically significant influence of characteristics of higher education institutions and scientific fields in which their study programs are accredited, on use of Internet resources and IT tools. The term 'use of Internet resources and IT tools' here refers to enhancing students' skills in use of internet resources, services and technologies on Internet, thus enabling them to create and place new content, services and technologies on the internet. This paper is based on data collected from 196 higher education institutions from Serbia, by a survey questionnaire. The research described in the paper was conducted in 2014. Data processing included a descriptive and correlative analysis. Based on this research, it can be concluded that there is a statistically significant influence of characteristics of higher education institutions on use of Internet resources and IT tools. Detailed research of the content of courses in higher education institutions that deal with internet and technologies surpasses the scope of this research and can be included in future research. This paper presents a new approach in research of influence of higher education institutions and their scientific fields' characteristics on use of Internet resources and IT tools in higher education. The results of this research can be used to improve educational strategies aiming to incorporate the internet use into the curricula of study programs in higher education institutions.
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Papers by Djordje Petrovic