The producing of lead and elemental sulfur by new technologies from galenite ores

These investigations have developed an effective hydrometallurgical method to recover high-purity lead metal and elemental sulfur from simulated galena synthetic mixures eliminating sulfur gases and lead emissions, in contrast to the current high-temperature smelting technology. The method consists of different operations: oxidative leaching with production of solution with residue containing elemental sulfur., electrowinning by the solution with metal production. The obtained results determined the optimal parameters for possible processing of natural domestic galena ores

Cable Distribution systems - an essential element of the global information society

Not long ago, before the advent of cable operators, here in Macedonia, especially in the smaller towns in this area in the developed countries was overwhelming. In Shtip were able to follow only two or three programs in the Macedonian Television. Later, in the nineties of the last century, there have been two more programs to private local television stations. Admission to these programs is done through external antennas. Nevertheless, due to the specific configuration of the terrain and tall buildings, it was not possible quality reception of TV programs in all parts of the city. On the other hand, this way of receiving television programs by external antennas (and several antennas for each family) and brings other problems. Among other things, in terms of aesthetic appearance of buildings resembling a "forest" of antennas. With the advent of cable operators, this picture changes significantly. At the beginning of its development, the cable operators only offered a service to its customers - analog TV. Today, cable operators offer more services, ie services, and are called Multi Service Operators (Multi service operator - MSO). They invest in quality and expensive equipment that receive and distribute to end users a number of TV and radio channels channels with high quality. Users however, relatively inexpensive monthly fee can enjoy the quality of TV channels, radio channels, internet, telephony and other interactive services. Today through KDS can carry more than 70 (seventy!) Analog television and radio programs as well as a much larger number of digital TV and radio channels. Additionally through KDS enables fast digital communication, access to high-speed, broadband Internet and fixed telephony. Modern cable distribution systems represents a form of electronic communication networks. Electronic communications networks other than cable can be partially or completely wireless

Reverse logistics – possibility, expectation and sustainability perspectives

Reversible logistics are complex to manage due to the uncertainty involved the range of quality products, product return time, and return volume. Product returns are usually from the first days of trading, originally marked as the starting point of reversible logistics (RL). In the eighties, many researchers1 tried to formulate definitions of reversible logistics, although they2 defined it in a very limited way, ie in the material movements from customers to manufacturers, which means that it is only in terms of product returns3. Reversible logistics itself has attracted the attention of academics since the early 1990s. Reversible logistics is considered to be much more complex than a traditional supply chain.4 It includes product return, source reduction, recycling, material replacement, material reuse, waste disposal and renovation, repair and recycling.5 Reversible logistics is also considered to be more complex to manage than advanced logistics6, as detailed activities in Reversible Logistics include the size, scope and impact on industry and the types of distribution channels7. Following the literature review, trends and some case studies in the world and in domestic research are identified, collection systems and directions for future and further research. The idea of ​​Reversible Logistics (RL) obviously shares similarities with the activities of the Circular Economy - repair, renovation, processing, recycling and reduction8. The purpose of Reversible Logistics (RL) is to reduce the raw material, the material for reuse and to respect the environment9, which fits into some activities and purposes of the Circular Economy (CE), although in a broader concept. The optimized Reverse Logistics (RL) demonstrated by world examples and different brands also lead to better supply chain visibility, leading to benefits. The optimized reverse logistics demonstrated by domestic examples Case Study 1 (for pellets) and Case Study 2 (for pallets) also lead to better supply chain visibility, leading to benefits

The recovery of the biomass waste for industrial pellets by recycling

The biomass as an organic product which may be used as a fuel - biofuel or the raw material in the industry. The bio-fuel may be occurred 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 appropriate parameters with geometry, caloric power, ash and dust. These wood products are rescent fuels produced by wood waste

Влијание на животната средина при експлоатација во јамите

Јавното претпријатие за подземна експлоатација на јаглен се наоѓа во состав на Електростопанство на Србија од 1990год. Во овој состав влегуваат осум рудници со тринаесет производни единични-јами. До 1990год. Рудниците беа самостојни претпријатија и ја претставуваа главната стопанска дејност, тогаш, а и сега во слабо развиените општини во Србија. Во текот на процесот на производство наидуваа на многу тешкотии кои произлегувале од сложените услови на експлоатација. Но и покрај доскорашните надворешни санкции, рудниците успешно работеа. Најголем пад на производството, за околу 20%, дојде 1994год. напрема 1990год. Но сепак произведените количини на јаглен тогаш допринеле да се подмират некои витални енергетски потреби (индустријата и домаќинствата). Сите рудници се наоѓаат во живописни предели и туристички места и објекти (Соко бања, Ресавска пештера, манастирите Манасија, Студеница, Раваница и др.). Наведениве факти ја потенцираат потребата за заштита на природата, како од еколошко така и од економско гледиште. Праксата покажала дека подземната експлоатација на јаглен има помалку влијание на животната средина во однос на останатата индустрија

Data Processing Using Analytical Hierarchical Process in Real Circumstances

In the development of the industry of small and medium enterprises that are involved in one of the most specific activities such as working with products, materials it gives and seeks opportunities for optimizing the basic management activities in the work of a company. Today, many data are constantly generated that require proper processing and access to them, especially when it comes to supply chain management and business logistics. Standard processing techniques may not meet these requirements. The development of information technology and decision theory has contributed to the emergence of the application of modern-applicable methods and approaches to data processing and analysis. The way of processing data from traditional data processing tools are adapted for data processing and with the help of tools and mathematical methods that enable processing and analysis of big data that depend on several criteria such as time, resources, quality, and distance when it is about delivering work material. The identification and analysis of the problem to be solved, the determination of the possible solutions to the problem, the criteria according to which the possible solutions are evaluated, i.e., the alternatives and the choice of the best possible solution is a decision-making process. It is the choice of the best, from the most possible alternative solutions to the problem such as the problem of delivery of specific material such as leather considering the quality and price

Decision Making Using Sequential Equation Modelling Applied for Pellet Production

By means of learning experiences, students are expected to know, understand, and be able to demonstrate certain skills, behaviors, and attitudes. These learning experiences have been defined and described by several different learning theories. The 21th century the most common learning theories have been behavioral and cognitive learning theories. Behavioral learning theorists explain learning as relatively permanent change in “hierarchical, observable, and measurable behaviors” whereas cognitive learning theorists explain learning “as an internal change in mental associations”. The pellet production (PP) has the potential to improve the social, economic and environmental elements of the local community, as well as to expand the development of state economy growth. Work study examines community support for that development in the context of sustainable development. This topic is interesting for processing because it deals with specific and so far in Macedonia untreated problems and aspects arising from the relationship between the local community and the state efforts for better conditions for development and higher standard

Improvement of the Static Characteristics of Pilot Operated Pressure Relief Valves

Theoretical and experimental investigations of the static characteristics of pilot operated pressure relief valves is presented in this article. A mathematical model of pressure drop vs. flow depending of pilot operated pressure relief valves is developed. An experimental test stand was created for experimental investigation of the static characteristics and compared with each other which confirm the mathematical model. The results of solving the mathematical model and experimental investigation are presented in few diagrams. A few directions for improvement of the static characteristics are given, especially at the moment of opening of the main valve. Advantages and disadvantages of the static characteristics are discussed

Modelling with Structural Equation Modelling – Application and Issues

Structural equation modeling (SEM) is a comprehensive statistical modeling tool for analyzing multivariate data involving complex relationships between and among variables. SEM surpasses traditional regression models by including multiple independent and dependent variables to test associated hypothesizes about relationships among observed and latent variables. SEM explain why results occur while reducing misleading results by submitting all variables in the model to measurement error or uncontrolled variation of the measured variables. SEM provides a way to test the specified set of relationships among observed and latent variables as a whole, and allow theory testing even when experiments are not possible. Structural Equation Modeling (SEM) is a powerful collection of multivariate analysis techniques, which specifies the relationships between variables through the use of two main sets of equations: Measurement equations and structural equations. Measurement equations test the accuracy of proposed measurements by assessing relationships between latent variables and their respective indicators. The structural equations drive the assessment of the hypothesized relationships between the latent variables, which allow testing the statistical hypotheses for the study. Additionally, SEM considers the modeling of interactions, nonlinearities, correlated independents, measurement error, correlated error terms, and multiple latent independents each measured by multiple indicators. In this paper will be presented application of relationship between reverse logistics and circular economy using some SEM fit indexes. The process of validating the measurement model requires testing each cluster of observed variables separately to fit the hypothesized CFA model. The statistical test uses the most popular procedures of evaluating the measurement model: Chi-square CMIN (χ2), Goodness-of-Fit Index (GFI), and Percent Variance Explained

Matrix method for large scale systems analysis

The mathematical model of a pilot operated pressure relief valve is described by a large system of nonlinear differential and algebraic equations. To analyze the stability condition of the valve, linearization of the mathematical model and getting the transfer function, i.e., the characteristic equation of the system is necessary. Obtaining the transfer function with elimination of the intermediate parameters is very complex and sometimes impossible. In this paper, a state space matrix method is used to reduce the large system of equation and to get the transfer function of the system