Dragana Makajić-Nikolić

A Conjoint-based approach to student evaluations of teaching performance

In recent years, the need for greater accountability and improvement in teachings quality has become a major issue in higher education. The results of student evaluation of teaching are increasingly used to make judgments about teaching quality, career advancement, and the funding of teaching itself. An important component of any such student evaluation is the communication of rating results in a manner that allows for fair and meaningful interpretations and comparisons of results by a wide range of evaluation users. In this paper, an approach for a more objective evaluation of university teachers is proposed, one which is based on previously obtained conjoint analysis data concerning criteria importance from a students point of view. Therein, an illustrative example is given to demonstrate the efficiency and practical usage of such a proposed approach.

Police officer scheduling using goal programming

Purpose – The purpose of this paper is to develop a methodology for automatically determining the optimal allocation of police officers in accordance with the division and organization of labor. Design/methodology/approach – The problem is defined as the problem of the goal programming for which the mathematical model of mixed integer programming was developed. In modeling of the scheduling problem the approach police officer/scheme, based on predefined scheduling patterns, was used. The approach is applied to real data of a police station in Bosnia and Herzegovina. Findings – This study indicates that the determination of monthly scheduling policemen is complex and challenging problem, which is usually performed without the aid of software (self-rostering), and that it can be significantly facilitated by the introduction of scheduling optimization approach. Research limitations/implications – The developed mathematical model, in its current form, can directly be applied only to the scheduling of police o...

Minimal cut sets of a coherent fault tree generation using reverse Petri nets

This paper proposes a new method for minimal cut sets generation of a coherent fault tree (FT) without repeated events. The approach is based on a special type of Petri nets – reverse Petri net (RPN) which can be generated directly from the FT. Using RPN properties and state equation, we have shown that the problem of finding all minimal cut sets becomes the following direct reachability problem: to find all dead markings reachable from marking of RPN. All minimal cut sets are then obtained as leaves of the reachability graph of a RPN. An algorithm to determine all leaves of the reachability graph is presented in the paper. The algorithm requires special numeration of the places and transitions of RPN which enables the generation of only one spanning tree of the reachability graph. Since the number of minimal cut sets in a complex system can be very large and a complexity problem occurs, we here propose an approach for solving this problem based on cutting the reachability tree of RPN.

An Optimization-Simulation Approach to Chance Constraint Programming

A stochastic programming problem with a number of random parameters in the set of constraints is considered. An iterative optimization-simulation approach is applied as solving method. It consists of two phases: optimization phase, which includes solving a deterministic counterpart of the original chance-constrained problem, and a simulation phase in which the original constraints are checked using Monte Carlo simulation. One iteration corresponds to one scenario. If the decision maker is not satisfied with results, new scenario is generated in which the deterministic values of stochastic parameters are changed in the direction that will provide a more robust solution. Deterministic counterpart in the new scenario is formulated depending on the result of previous iteration. For that purpose, different heuristics are considered. The main goal is to provide a good insight on the optimization problem under uncertainty by performing relatively small number of iterations. General approach and results of the proposed framework will be illustrated on an advertisement placement example.DOI: http://dx.doi.org/10.5755/j01.itc.47.2.18712

The model of risk assessment of greywater discharges from the Danube River ships

Having in mind the immense value of the Danube River and knowing that risk assessment of its pollution is one of the key elements for ecology and the health of people in its region, in this paper we emphasized the importance of risk assessment of ship-generated wastewater – particularly in the case of greywater discharges. Although, a number of methods for measuring and analysing different environmental risks have been developed, previous research shows that the failure mode and effect analysis (FMEA) method is applicable in solving environmental issues. Therefore, we conducted our research with the main purpose to develop a model of FMEA method application for assessing the risks of ship-generated greywater discharges based on estimated data for total quantity of greywater, the size of the exposed population to the pollution of greywater and the possibilities of this pollution detection. Risk analysis was performed on official data for nine ports on the Danube River on inland waterways of the Republic of Serbia. Based on the obtained results, we concluded that measures, recommendations and risk prevention strategies for ship-generated greywater discharges should go into two major directions: (1) decreasing the pollution caused by greywater discharges; (2) increasing the number of water quality monitoring stations.

The effects of economic activities diversification on development: The perspective of Serbia

Each economy specializes in certain economic activities depending on the development level and availability of resources. During their development, countries undergo sectoral transformation. In order to achieve a higher level of economic development, it is necessary for a country to diversify its economic activities and determine which economic activities should be invested in. The aim of this paper is to analyse the effects of economic structure and diversification activities on the development of Serbia for the period 2007-2012. Optimization model has been used to present diversification of activities. Furthermore, the efficiency frontier is used to show returns, risks and correlation among activities. The results show that the economic activities - Mining and quarrying, Public administration and defence, Compulsory social security, Other service activities, Financial and insurance activities, Arts, entertainment and recreation should be drivers of economic growth, because they provide a balance between growth and security regarding GVA in economic activities.