Aleksandar Krstev

Goce Delcev University · Department of Informatics

Moodle is one of the most famous e-learning platforms. It is often necessary to get knowledge about the use of a Moodle site by users. For this purpose, Moodle uses analytics tools. Sometimes these tools do not come standard with the platform and must be installed as plugins. The goal of our research is to explore the benefits of analytics and repo...

In this paper will be analyzed and compared the results of the electronic testing (e-testing) for the subject Mathematics 2 within University “Goce Delcev”– Stip using statistical data processing. Electronic testing covers the topic “Integral”. This topic is of great importance during the studies and for this topic students have previous knowledge...

In this paper, we give а connection between the mathematical notions and using the computer as educational support at university level. Specifically, mathematical notions used in integral calculations will be explained with help of computer program. The notions, indefinite and definite integral, their calculations and their applications can be easi...

The adsorption of copper ions from synthetic aqueous solutions on natural zeolite (clinoptilolite) was examined. In order to determine the rate of adsorption and the copper uptake at equilibrium, a se- ries of experiments were performed under batch conditions from single ion solutions. Equilibrium data were evaluated based on adsorption (Langmuir...

p> The kinetics of manganese adsorption onto natural zeolite (clinoptilolite) were studied with respect to initial metal ion concentration and adsorbent mass. In order to select the main rate-determining step in the overall uptake mechanism, a series of experiments were performed under batch conditions from single ion solutions. Data obtained from...

The kinetics of zinc adsorption onto natural zeolite (clinoptilolite) were studied with respect to initial metal ion concentration, adsorbent mass and initial pH value. In order to select the main rate-determining step in the overall uptake mechanism, a series of experiments were performed under batch conditions from single ion solutions. Data obta...

Flotation tailing dams affect the environment through the soil, water and air, and in that way they affect the plants and the animals as well as the people. This paper shows the quality of the soil according to the concentration of heavy metals in the surroundings of Sasa mine, more precisely, the Kocani valley which uses water from the dam Kaliman...

Assessing of costs in SMEs is a difficult endeavor. There are several factors that contribute. Many of these factors are of a technical nature, such as development costs or integration costs. A substantial part of the costs are caused by organizational factors such as changes in the introduction of an IT system on business processes or the cost of...

To improve kinetic flotation models, many first-order flotation kinetics models with distributions of flotation rate constants were redefined so that they could all be represented by the same set of three model parameters. As a result, the width of the distribution become independent of its mean, and parameters of the model and the curve fitting er...

The refractory or low grade lead/zinc domestic ores in Republic of Macedonia are investigated by conventional separation technology or flotation separation. In the mean time, investigations are directed to the new possibilities of leaching by microorganisms – bioleaching. The paper is result of these technologies and investigations carried out for...

To improve kinetic flotation models, many first-order flotation kinetics models with distributions of flotation rate constants were redefined so that they could all be represented by the same set of three model parameters. As a result, the width of the distribution become independent of its mean, and parameters of the model and the curve fitting er...

The improvement in the chalcopyrite copper Bucim mine are gone forward to renewed reagent regime, including and involving new reagents for increase d recovery of copper and gold. The optimization and mathematical linear models using gradient method Box and Wilson are good example for improvement of industrial recoveries in flotation circuit. In thi...

In this paper will be shown the application of information systems and technologies in production processes in modern conditions (production). The successful implementation of goals and objectives of the enterprise depends on its effective use of information resources. Information resources are the basis for their strategic success. Information...

Freight forwarding as a factor for growth of the economy, industry and in particular the trade of the Republic of Macedonia and abroad, requires adapting to new conditions resulting from the global economic crisis. The fact that freight forwarding is an integral part of logistics need: To improve performance and to adjust to new conditions (legisla...

The biomass as an organic product may be used as a fuel, bio fuel or the raw material in the industry. The bio fuel may occured as a plant or animal origin. These may be used by their direct combustion. The most effectively usefull method for biomass utilization is finalization in the pellet product as combustion product. The pellets have had appro...

In this paper mathematical methods and optimization tools that make possibilities for appropriate, fast and sure presentation of some complex circuits in the mineral processing technologies will be shown. Lagrange multipliers include the analytical methods of optimization, the constraints that appear in the form of equations. Such methods of optimi...

In this paper will be shown the general concept of the techno-economical development in R.Macedonia, as a result of the closed privatization and including the direct investment in the field of education, economy and other fields of interest. An explication of the state and public legislative in the high education (Bologna, EKTS, Curriculum of Busin...

The average recoveries from flotation process in the copper concentrate were ca. 90% for copper, 55-58% for gold, and 35-40% for silver. The average recoveries from leaching were ca. 92-93% for copper, 75-80% for gold, and 70-75% for silver. The average recoveries from bio-leaching were ca. 93-95 for copper, 75-85% for gold, and 75-85% for silver

The average recoveries from segregation-flotation-magnetic separation ca. 75-85% for nickel, from leaching ca85-90% for nickel and the average recoveries from bio-leaching with ca. 90-93% for nickel

Abstract: The refractory or low grade cooper domestic sulphide - chalcopyrite ores in Republic of Macedonia are investigated by conventional flotation separation. In the mean time, investigations are directed to the new possibilities of leaching by microorganisms – bioleaching. The paper is result of these technologies and investigations carried ou...

Abstract: The refractory or low grade nickel laterite domestic ores in Republic of Macedonia are investigated by conventional magnetic separation technology or segregation-flotation-magnetic separation, or production and smelting to ferronickel. In the mean time, investigations are directed to the new possibilities of leaching by microorganisms – b...

Informatisation, internationalization and globalization have dramatically changed retail sector; speeding up the retail processes, creating new sale formats, fastening the increase of income etc. During the last decade, logistics influenced the development of retailing by cutting down costs and increasing the service quality level. The main purpose...

Hydrological parameters have major impact to water, energy, civil engineering, industry and other commercial and non-economic branches. For the determination of the hydrological processes are: observed, measured and recorded data on hydrological phenomena. Our knowledge of these phenomena modes is the basis for good planning and management of water...

These investigations have developed an effective hydrometallurgical method to recover high-purity leadmetal and elemental sulfur from simulated galena synthetic mixtures eliminating sulfur gases and lead emissions, in contrast to the current high-temperature smelting technology. The method consists of different operations: oxidative leaching with p...

Dangerous and hazardous flotation tailings dams can be source of endangering of living environment. Intheir normal work and also in case of damages incidents in flotation tailings dams can be caused by natural catastrophe in the area or malfunctions due to unreliable work. Harmful chemicals, which can get to living environment at damages, can cause...

The work presented in this paper analyses the viability of using a cell-phone as students’ guidance for literature selection. The integrated cell-phone camera is used to recognize the book covers in the bookstores and libraries. The chosen solution is based on client-server architecture and the object recognition is based on local features. Detecti...

Mining industry was always considered as risky business. Uncertainties about ore body, volatile commodity prices, exchange rates, environmental issues, political/legislation risks make a capital investment puzzle for every decision maker throughout the industry. Major challenge of project evaluation is how to deal those risks/uncertainties. Several...

In this paper will be shown computer application of softwares Minteh-1, Minteh-2 and Minteh-3 in Visual Basic, Visual Studio for presentation of two-products for some closed circuits od grinding-clasifying processes. These methods make possibilities for appropriate, fasr and sure presentation of some complex circuits in the mineral processing techn...