RFOS - Repository of Faculty of Organizational Sciences Univ. of Belgrade
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On the causal relation between real world activities and emotional expressions of social media users
No full textSocial interactions through online social media have become a daily routine of many, and the number of those whose real world (offline) and online lives have become intertwined is continuously growing. As such, the interplay of individuals' online and offline activities has been the subject of numerous research studies, the majority of which explored the impact of people's online actions on their offline activities. The opposite direction of impact-the effect of real-world activities on online actions-has also received attention but to a lesser degree. To contribute to the latter form of impact, this paper reports on a quasi-experimental design study that examined the presence of causal relations between real-world activities of online social media users and their online emotional expressions. To this end, we have collected a large dataset (over 17K users) from Twitter and Foursquare, and systematically aligned user content on the two social media platforms. Users' Foursquare check-ins provided information about their offline activities, whereas the users' expressions of emotions and moods were derived from their Twitter posts. Since our study was based on a quasi-experimental design, to minimize the impact of covariates, we applied an innovative model of computing propensity scores. Our main findings can be summarized as follows: (a) users' offline activities do impact their affective expressions, both of emotions and moods, as evidenced in their online shared textual content; (b) the impact depends on the type of offline activity and if the user embarks on or abandons the activity. Our findings can be used to devise a personalized recommendation mechanism to help people better manage their online emotional expressions
Towards a Formal Specification of Production Processes Suitable for Automatic Execution
No full textTechnological advances and increasing customer need for highly customized products have triggered a fourth industrial revolution. A digital revolution in the manufacturing industry is enforced by introducing smart devices and knowledge bases to form intelligent manufacturing information systems. One of the goals of the digital revolution is to allow flexibility of smart factories by automating shop floor changes based on the changes in input production processes and ordered products. In order to make this possible, a formal language to describe production processes is needed, together with a code generator for its models and an engine to execute the code on smart devices. Existing process modeling languages are not usually tailored to model production processes, especially if models are needed for automatic code generation. In this paper we propose a research on Industry 4.0 manufacturing using a Domain-Specific Modeling Language (DSML) within a Model-Driven Software Development (MDSD) approach to model production processes. The models would be used to generate instructions to smart devices and human workers, and gather a feedback from them during the process execution. A pilot comparative analysis of three modeling languages that are commonly used for process modeling is given with the goal of identifying supported modeling concepts, good practices and usage patterns
Optimal Selection of Lightweight Cipher Algorithm and Topology Construction Protocol in Wireless Sensor Networks
No full textAn optimal selection of a WSN topology protocol and a suitable lightweight cipher algorithm is a highly important task, whose success ensures both the maximum utilization and the security of a wireless sensor network. This paper presents a method to determine the optimal combination of a WSN topology protocol and a lightweight cipher algorithm in the context of power consumption throughout an entire network. A selection method based on multi-attribute decision-making methods is proposed. These methods, used for the first time in a study of sensor networks, provide a ranking of the optimal combinations of topologies and encryption algorithms that meet the requirements of wireless sensor networks such as authentication, data integrity, reliability, availability, confidentiality, and energy efficiency
Factors that influence cultural tourists to use e-WOM before visiting Montenegro
No full textTežeći proširenju postojećeg znanja o obrascima ponašanja turista kulturnog turizma koji posjećuju Crnu Goru svrha istraživanja je utvrđivanje glavnih razloga koji motivišu turiste kulturnog turizma da koriste elektronsku preporuku kao izvor informisanja o ovoj destinaciji. Da bi se ispunio ovaj zadatak tokom 2019. godine dizajniran je strukturirani upitnik i sprovedeno terensko istraživanje na uzorku od 376 turista kulturnog turizma koji su koristili elektronske preporuke kako bi došli do više informacija o Crnoj Gori. Utvrđeno je dvadeset i sedam indikatora koji su grupisani u tri grupe faktora od uticaja i potom istraženi putem jednosmjerne analize varijanse i T-testa nezavisnih uzoraka. Pored ličnog stava ispitanika rezultati pokazuju da su određene demografske karakteristike kao i zemlja porijekla ispitanika igrali značajnu ulogu po pitanju njihove sklonosti ka korišćenju elektronske preporuke prije same posjete destinacije. Utvrđivanjem konkretnih razloga radi kojih turisti kulturnog turizma koriste elektronsku preporuku istraživanje pruža saznanja koja mogu biti korisna tokom oblikovanja budućih marketiniških strategija destinacije.Aiming to expend the existing knowledge regarding behavioural patterns of cultural tourists who are visiting Montenegro, the purpose of this research is to identify the main reasons that motivate cultural tourists to use e-WOM as a source of information about this destination. To fulfil this task a structured questionnaire was designed and a field research was carried out during 2019 among 376 cultural tourists who used e-WOM to gain more information about Montenegro. Twenty seven indicators were identified and grouped in three groups of factors of influence which were examined using one-way analysis of variance and independent sample T-test. Besides the respondents 'personal attitude, the research shows that certain demographic characteristics and the respondents' country of origin influenced their propensity in using e-WOM prior to visiting this destination. By identifying concrete reasons why cultural tourists use e-WOM, this study offers insights that can be useful in designing future destination marketing strategies
Reinstatement of the Extension Principle in Approaching Mathematical Programming with Fuzzy Numbers
No full textOptimization problems in the fuzzy environment are widely studied in the literature. We restrict our attention to mathematical programming problems with coefficients and/or decision variables expressed by fuzzy numbers. Since the review of the recent literature on mathematical programming in the fuzzy environment shows that the extension principle is widely present through the fuzzy arithmetic but much less involved in the foundations of the solution concepts, we believe that efforts to rehabilitate the idea of following the extension principle when deriving relevant fuzzy descriptions to optimal solutions are highly needed. This paper identifies the current position and role of the extension principle in solving mathematical programming problems that involve fuzzy numbers in their models, highlighting the indispensability of the extension principle in approaching this class of problems. After presenting the basic ideas in fuzzy optimization, underlying the advantages and disadvantages of different solution approaches, we review the main methodologies yielding solutions that elude the extension principle, and then compare them to those that follow it. We also suggest research directions focusing on using the extension principle in all stages of the optimization process
Financial literacy and the use of financial services in Serbia
No full textIndustrija finansijskih usluga oduvek privlači veliku pažnju potencijalnih investitora, zajmoprimaca, države i šire javnosti. Generalno, finansijske usluge postaju sve atraktivnije ali i složenije. Cilj ove studije jeste da analizira upotrebu finansijskih usluga u Srbiji. Smatramo da su finansijsko obrazovanje i finansijska pismenost preduslovi za korišćenje finansijskih mogućnosti. Istraživanja pokazuju da većina ljudi u Srbiji nije dobro informisana oko donošenja kvalitetnih finansijskih odluka. Potrebno je posebno analizirati razloge zbog kojih ljudi u Srbiji ne koriste finansijske proizvode i usluge u većoj meri. Kako bi utvrdili razlike u pogledu informisanosti i upotrebe finansijskih usluga, sproveli smo upitnik. Naši rezultati pokazuju da su ljudi koji imaju zaradu veću od 100.000 RSD bolje informisani ali nedovoljno motivisani da investiraju. Pojedinci sa srednjim nivoom primanja nemaju dovoljno poverenja i smatraju da nisu dobro informisani u pogledu različitih mogućnosti. Pored toga, rezultati pokazuju da su muškarci bolje informisani od žena. Cilj ovog rada jeste da pruži pregled upotrebe finansijskih usluga u Srbiji kako bi se poboljšao proces finansijskog odlučivanja i razumele različite finansijske mogućnostiFinancial services industry has always drawn a lot of attention, from possible investors, those who need financing, the government and general public. Globally, financial opportunities are becoming more attractive, but also more complex. The goal of this study is to analyze the use of financial services in Serbia. We argue that financial education and literacy are preconditions for the use of financial opportunities. Research has shown that people in Serbia are not well informed about how to make sound financial decisions. The reasons why people in Serbia do not use financial products requires to a greater extent and services special attention. In order to test the differences between people in terms of how well informed they are and which services they use and why, we conducted a survey. Our results show that people with salaries higher than 100,000 RSD are well informed but not motivated to invest. Individuals with middle income do not have enough trust and think that they are not well informed about different opportunities. Additionally, we found that men are better informed than women. This paper aims to provide an overview of the use of financial services in Serbia in order to improve financial decision-making processes and understand the different financial opportunities
Prevalence and Metabolic Predictors for Early Diagnosed Prediabetes in Women with Previous Gestational Diabetes: Observational Cohort Study
No full textIntroduction: Women with previous gestational diabetes (pGD) are at higher risk of prediabetes (PD) after delivery. The aim of this study was to determine the prevalence of and predictors for PD among women with pGD. Methods: The study included 186 women with pGD treated by lifestyle modification. After delivery, the women were divided into group A (n = 80) with PD and group B (n = 106) with normal glucose tolerance (NGT), defined by the results of the 2-h oral glucose tolerance test at 4–12 weeks after delivery. We recorded age, body mass index (BMI) at conception and after delivery, fasting glucose (FG), glycated hemoglobin (HbA1c), total cholesterol (TC), triglycerides (Tg), low density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c) and the Tg/HDL-c ratio measured in the third trimester of pregnancy. Results: Of the 186 women with pGD enrolled in the study, 43% showed prediabetes at 4–12 weeks after delivery, with 13.9% of these women showing impaired FG (IFG), 12.9% showing impaired glucose tolerance (IGT) and 16.2% with IFG/IGT. The groups differed in terms of age and BMI at conception and after delivery. In the third trimester of pregnancy, HbA1c was higher in women in group A than in those in group B (mean ± standard deviation: 5.6 ± 0.4 vs. 5.2 ± 0.3%; p LT 0.001), while FG was comparable. Compared to women in group B, women in group A had higher TC (7.1 ± 0.8 vs. 6.6 ± 1.0 mmol/L), Tg (2.7 ± 0.9 vs. 2.1 ± 0.6 mmol/L) and LDL-c (4.7 ± 0.8 vs. 4.3 ± 1.0 mmol/L) (all p LT 0.001), lower HDL-c (1.0 ± 0.2 vs. 1.4 ± 1.0; p LT 0.001) and higher median Tg/HDL-c (5.4 [range 4.6–14.3] vs. 4.9 [range 1.1–11.5]; p LT 0.001). Univariate analysis found an association between prediabetes and age, BMI at conception and after delivery, HbA1c, TC, LDL-c, HDL-c, Tg and Tg/HDL-c ratio. Of these variables, the multivariate analysis showed age (odds ratio [OR] 1.19; p LT 0.001), HbA1c (OR 31.06; p LT 0.001), Tg (OR 4.09; p LT 0.001) and LDL-c (OR 2.00; p = 0.005) as predictors for prediabetes. Conclusion: High prevalence of early diagnosed PD in women with pGD was accompanied by advanced age and higher BMI at conception and after delivery. Moreover, age, HbA1c, Tg and LDL-c were predictors for PD
Jensen Functional, Quasi-Arithmetic Mean and Sharp Converses of Holder's Inequalities
No full textIn this article, we give sharp two-sided bounds for the generalized Jensen functional J(n)(f,g,h;p,x). Assuming convexity/concavity of the generating function h, we give exact bounds for the generalized quasi-arithmetic mean A(n)(h;p,x). In particular, exact bounds are determined for the generalized power means in terms from the class of Stolarsky means. As a consequence, some sharp converses of the famous Holder's inequality are obtained
A crowdsensing platform for real-time monitoring and analysis of noise pollution in smart cities
No full textThis paper presents a crowdsensing platform for real-time monitoring and analysis of noise pollution in smart cities. The aim is to develop a comprehensive methodology and scalable infrastructure for measuring noise using mobile crowdsensing, storing and analysis of gathered data. The developed system consists of: 1) a mobile application for participatory and opportunistic crowdsensing of noise data from different microlocations, preprocessing of collected data, and sending data to the cloud, 2) a big data infrastructure for storing data and real-time big data analysis, and 3) a web application for decision support. Further, we have created a methodology that lets us select priority microlocations not typically covered by stationary measuring. The system has been evaluated experimentally; more than 4000 measurements were collected at five microlocations in the city of Belgrade, Serbia. Data was analysed in order to find the patterns that could serve for decision support to different stakeholders