This article is dealing with international relations between EU and Russian Federation after falling of Berlin's wall and decline of communist regimes in countries of Eastern block. Author is trying ...to emphasize three periods. First period is from 1991. until 2000. During presidency of Boris Jeljcin in Russia. This period is reflected by declining of Russian power and stronger integration of Europe because of Treaties of Maastricht and Amsterdam. Second period is period of coming on power president Vladimir Putin and uprising of Russia. This period lasts until 2014. year, when relations were more-less stable, except conflict in Georgia. Third period is related to conflict in Ukraine in 2014. And energetic crisis in 2021. Conflict in Ukraine has shown that EU doesn't have force to stand from foreign policy of USA, which is reflected in actions of NATO. Author concludes article with hope that memory from two world wars will be enough strong for politicians from both sides to not let another world war, and they will find new ways to enhance international cooperation.
Traditionally, agent-based modelling and simulation relied on using utility function in agents' decision-making process. Some drawbacks in this process are identified, and a potential remedy to the ...issue is proposed. This paper introduces a methodological framework for building a hybrid agent-based model that aims to overcome some of the elaborated problems related to the usage of a utility function. In the proposed approach, a machine learning algorithm substitutes the utility function, thus providing a possibility to use various algorithms. The proposed methodological framework has been applied to a case study of churn in a telecommunications company. Three models have been created and used for simulation experiments, two using the proposed methodology and one using utility function. The pros and cons of different approaches are identified and discussed.
In this paper, we describe an approach to providing adaptivity in e-education courses. The primary goal of the paper is to enhance an existing e-education system, namely Moodle LMS, by developing a ...method for creating adaptive courses, and to compare its effectiveness with non-adaptive education approach. First, we defined the basic requirements of a course adaptation and the steps required to implement it. Based on the collected data, we identified the characteristic groups of students and then classified all participating students into these groups. The final adaptation of courses was performed in the distance education system of the University of Belgrade, in the Laboratory for e-business, Faculty of Organizational Sciences. Findings of the experimental study showed that the students' effectiveness and achievements in learning were higher when they attended courses adapted using the described method, in comparison to the non-adaptive e-learning courses.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this paper, electrochemical degradation of Reactive Black 5 (RB5) textile azo dye was examined in regard to different synthesis procedures for making PbO2–graphitic carbon nitride (g-C3N4) ...electrode. The reaction of PbOH3- with ClO− in the presence of different surfactants, i.e., cetyltrimethylammonium bromide (CTAB) and tetrabutylammonium phosphate (TBAP), under conventional conditions, resulted in the formation of PbO2 with varying morphology. The obtained materials were combined with g-C3N4 for the preparation of the final composite materials, which were then characterized morphologically and electrochemically. After optimizing the degradation method, it was shown that an anode comprising a steel electrode coated with the composite of PbO2 synthesized using CTAB as template and g-C3N4, and using 0.15 M Na2SO4 as the supporting electrolyte, gave the best performance for RB5 dye removal from a 35 mg/L solution. The treatment duration was 60 min, applying a current of 0.17 A (electrode surface 4 cm2, current density of 42.5 mA/cm2), while the initial pH of the testing solution was 2. The reusability and longevity of the electrode surface (which showed no significant change in activity throughout the study) may suggest that this approach is a promising candidate for wastewater treatment and pollutant removal.
The paper analyzed business efficiency (productivity, economy and
profitability) and business indicators (liquidity, solvency and
indebtedness) of PE ?National park Kopaonik?. The goal of the ...research is to
identify their values, with the purpose of determining the situation and
recognizing opportunities for possible improvement of certain segments in
the business of the analyzed PE. The subject of the research is the
financial reports of PE ?National park Kopaonik?, and the data generated
from them, based on which indicators of business success were determined.
En este estudio se investigaron las propiedades mecánicas (prueba de dureza Brinell) y eléctricas de algunas aleaciones de Ag-Ge-In ternarias seleccionadas. Los resultados obtenidos para las ...propiedades mecánicas y el análisis ANOVA, se sugiere un modelo matemático de cálculo para las propiedades de cada composición de aleaciones. Las microestructuras de aleaciones se han llevado a cabo mediante microscopía óptica y microscopía electrónica de barrido (SEM). Las fases presentadas en las microestructuras se han detectado mediante análisis de difracción de rayos X (XRD) y las composiciones mediante espectrometría de dispersión de energía (EDS). Los resultados determinados experimentalmente se comparan con los datos calculados. El cálculo de la sección isotérmica a 25 °C se realizó utilizando parámetros termodinámicos optimizados para los sistemas binarios constitutivos. Se obtuvo una buena concordancia general entre los valores experimentales y los calculados.
This paper examines the development and application of agent-based modelling and simulation in the analysis of customer behaviour on B2C e-commerce websites as well as in the analysis of the effects ...of various business decisions regarding online sales. The methodology of the agent-based simulation used in this paper may significantly enhance the speed and quality of decision-making in electronic trade. The models developed for this research aim to improve the use of practical tools for the evaluation of the B2C online sales systems in that they allow for an investigation into the outcomes of varied strategies in the e-commerce site management as regards customer behaviour, website visits, scope of sales, income earned, etc. An agent-based simulation model developed for the needs of this research is able to track the interactions of key subjects in online sales: site visitors-prospective consumers, sellers with different business strategies, and suppliers.
This paper examines the level of payment for ecosystem services (PES) concept implementation in the financing of water-related forest ecosystem services (ES) in the Republic of Croatia, the ...Federation of Bosnia and Herzegovina (FB&H), the Republic of Slovenia, and the Republic of Serbia. The focus is on water-related forest ES recognised by the millennium ecosystem assessment (MEA). For the purpose of this paper, the term pure PES describes schemes that comply to all five conditions set by Wunder definition and term PES like for those schemes that miss some of those conditions. In the first step, the most important legislative documents related to forests, water, and environmental protection were selected. The second consists of a content analysis; focusing on the definition of ES; the definition of fees or payments; the establishment of ‘forest funds’, ‘water funds’, or ‘environmental funds’; and the way these funds were spent. Here we looked at the flow of funding into the forestry sector recognising forest management as the main water-related forest ES provider. Research revealed existence of well-established payments schemes in forestry in Croatia for almost 30 years and in FB&H for some 20 years which were assessed as closest to pure PES. In Serbia and Slovenia, there were no PES or PES like schemes in the forestry sector. In the water sector the well-established PES like payments schemes existing in all four countries. The environmental protection sector, however, rely more on the tax like rather than on the PES like schemes. Legislation in general recognised the link between forests and water, but this was much more evident in the forestry than in the water or environment sector. The role of the state is strongly pronounced in all countries studied, and was the main driving force behind all payments. However, this position of the state represents also the main obstacle for the development of pure PES schemes, together with underdeveloped private forestry and complex socio-economic conditions. Nevertheless, there is room for further development of pure PES and PES like schemes based on EU or global experiences.
The Gaussian Q-function has considerable applications in numerous areas of science and engineering. However, the fact that a closed-form expression for this function does not exist encourages finding ...approximations or bounds of the Q-function. In this paper, we determine analytically two novel interval upper bound Q-function approximations and show that they could be used efficiently not only for the symbol error probability (SEP) estimation of transmission over Nakagami-m fading channels, but also for the average symbol error probability (ASEP) evaluation for two modulation formats. Specifically, we determine analytically the composition of the upper bound Q-function approximations specified at disjoint intervals of the input argument values so as to provide the highest accuracy within the intervals, by utilizing the selected one of two upper bound Q-function approximations. We show that a further increase of the accuracy, achieved in the case with two upper-bound approximations composing the interval approximation, can be obtained by forming a composite interval approximation of the Q-function that assumes another extra interval and by specifying the third form for the upper-bound Q-function approximation. The proposed analytical approach can be considered universal and widely applicable. The results presented in the paper indicate that the proposed Q-function approximations outperform in terms of accuracy other well-known approximations carefully chosen for comparison purposes. This approximation can be used in numerous theoretical communication problems based on the Q-function calculation. In this paper, we apply it to estimate the average bit error rate (ABER), when the transmission in a Nakagami-m fading channel is observed for the assumed binary phase-shift keying (BPSK) and differentially encoded quadrature phase-shift keying (DE-QPSK) modulation formats, as well as to design scalar quantization with equiprobable cells for variables from a Gaussian source.
FDI Time Series Forecasts: Evidence from Emerging Markets Dobrota, Marina; Zornić, Nikola; Marković, Aleksandar
Management (Belgrade University, Faculty of Organizational Sciences),
01/2021, Letnik:
26, Številka:
2
Journal Article
Odprti dostop
Research Question: This paper investigates the trend and flow of foreign direct investments (FDI) in emerging markets, with the focus on FDI in Serbia in comparison with akin countries from the ...region. Motivation: FDI is an important factor of growth and prosperity in developing countries. It largely influences trade, productivity, and economic development of a receiving country. Based on UNCTAD’s World Investment Report of 2019, the share of global FDI in developing countries was 54 per cent, which was a record. Recently, Serbia has been recognized as one of the most popular destinations for FDI in Southeastern Europe. This motivated us to analyze the chances and possibilities of enlargement of FDI in Serbia, as well in other Balkan countries. Idea: The main idea of the paper is to analyze and estimate time series of FDI net inflows for Serbia. We strive to investigate whether FDI demonstrates the durable growth in the future period of time. Furthermore, we compare the state of Serbian FDI with the former Yugoslav countries, in search for disparities or similarities. Data: We observed the FDI net inflows that are measured in current US dollars, while the data were retrieved from the World Bank database. The earliest available time point is 1992, while the latest available year of observation is 2018. Tools: We estimated the FDI net flow time series using a list of suitable ARIMA models, and we have chosen the best model fit among them using AIC and BIC criteria. Findings: We have found that Serbia and North Macedonia show a mild growth in future investments. A significant percentage of the cumulative FDI inflows from EU companies have been invested precisely in Serbia, while in North Macedonia, fostering FDI has been promoted as one of the main instruments for employment and economic development. Oher Yugoslav countries tend to stagnate in the future period, which is in literature called a negative ‘Western Balkans’ effect on FDI. Contribution: Findings of the mild growth in FDI inflows in Serbia and North Macedonia contribute to the policy of attracting the FDI inflows in the countries of Southeastern Europe.
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