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Stanojevic L.P.,University of Nis | Radulovic N.S.,University of Nis | Djokic T.M.,The Academy of Criminalistic and Police Studies | Stankovic B.M.,University of Nis | And 3 more authors.
Industrial Crops and Products | Year: 2015

In this work the impact of four different techniques of Clevenger-type hydrodistillation (technique I-IV) on the yield, hydrodistillation kinetics and composition of the essential oils of Anethum graveolens L. seeds was investigated. The highest oil yield, after five consecutive hydrodistillation runs (3.74. ml/100. g of plant material), was achieved by the utilization of filtrated (from plant material) water used in the previous hydrodistillation run plus newly added water in the subsequent runs (technique III). The hydrodistillation of dill seeds took place in two stages: a rapid, early distillation of the oil followed by a much slower second phase. Two kinetics models were successfully used to interpret the hydrodistillation rate of the essential oil of dill. Independent of the technique used, the oil contained the same components but in differing amounts as inferred from detailed gas chromatography-mass spectroscopy (GC-MS) analyses. Carvone was found to be the major component in all obtained oils. © 2014 Elsevier B.V.. Source


Savic G.,University of Belgrade | Makajic-Nikolic D.,University of Belgrade | Randelovic D.,The Academy of Criminalistic and Police Studies | Randelovic M.,City of Nis Local Economic Development Office
Metalurgia International | Year: 2013

Upon the completion of the common first-year curriculum, under graduate university students may find it difficult to choose the most appropriate study program. This paper deals with a methodology that may help students select it on the basis of their first-year marks, i.e. their efficiency. We have used data on the students' marks from the official database at the Faculty of Organizational Sciences, University of Belgrade, to determine the weights of the first-year subjects in order to predict future students' success on each of the study programs, separately. The aggregated measure, as the combination of weights obtained by Data Envelopment Analysis (DEA) as an objective, and Analytical Hierarchical Process (AHP) as a subjective method is defined for determining the subject's weight. Furthermore, based on the weights assigned to subjects according to departments, we have selected subjects relevant for assessment of future students' success and recommended the appropriate study programs. Source


Randelovic D.,The Academy of Criminalistic and Police Studies | Randelovic M.,City of Nis Local Economic Development Office | Savic G.,University of Belgrade | Makajic-Nikolic D.,University of Belgrade
Metalurgia International | Year: 2013

The problem of determining weights of criteria appears in many contexts in multiple criteria decision making. For solving this task it is necessary to determine individual influence of each considered criterion. Each criterion can be either quantitative-when each of attributes can take different values or qualitative-in which case only ranking of weights of criterias is possible. The weights for each criterion could be provided by experiments, tests or as experts opinions. This paper presents methodology for obtaining an aggregated measure, in the form of arithmetic means, for quantitative decision making. The measure is obtained experimentally by combining statistical methodology-based on regression and factor analysis on one hand and operational research approaches-data envelopment analysis as an objective and analytical hierarchical process as subjective method. For practical demonstration of proposed method authors used data on the students' marks, from the official database at the Faculty of organizational sciences, University of Belgrade, to determine the weights of the first-year subjects in order to predict future students' success on each of the study programs, separately. Source

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