Development of a model for assessing the energy efficiency increase of solar collectors in dynamic operating conditions

U radu je izvršena detaljna analiza uticajnih faktora na energetsku efikasnost prijemnika sunčeve energije u dinamičkim uslovima rada. Identifikovani su parametri koji utiču na povećanje efikasnosti reprezentativnih tipova prijemnika koji se nalaze u komercijalnoj primeni. Promenom geometrijskih parametara konstrukcije i radnih parametara utvrđen je njihov uticaj na energetsku efikasnost a zatim je kreiran model za ocenu povećanja efikasnosti prijemnika sunčeve energije u dinamičkim uslovima rada

Development of a model for assessing the energy efficiency increase of solar collectors in dynamic operating conditions

U radu je izvršena detaljna analiza uticajnih faktora na energetsku efikasnost prijemnika sunčeve energije u dinamičkim uslovima rada. Identifikovani su parametri koji utiču na povećanje efikasnosti reprezentativnih tipova prijemnika koji se nalaze u komercijalnoj primeni. Promenom geometrijskih parametara konstrukcije i radnih parametara utvrđen je njihov uticaj na energetsku efikasnost a zatim je kreiran model za ocenu povećanja efikasnosti prijemnika sunčeve energije u dinamičkim uslovima rada

Mathematical Analysis of Criteria for Maintenance of Technical Systems in the Function of Achieving Sustainability

Achieving sustainable development requires strategic efforts involving the entire organization. Maintenance efforts also play an important role. Company management needs to understand and develop an appropriate strategy to achieve sustainable development by applying maintenance performance measurements. The aim of this paper is to present possible ways of analyzing and ranking the impact of certain criteria with respect to achieving sustainability. The paper uses the method of Structural Equation Modeling—SEM in order to determine the most influential variable on the sustainability of maintenance of technical systems. Based on the set theoretical system model, for all its variables in the model, statements were made that describe them, on which 136 respondents gave their views (from 1 to 5, Likert scale) in the territory of the Republic of Serbia. An intuitive F-DEMATEL method was also used to prioritize variables. A team of 10 experts in the field of maintenance of technical systems was compared the criteria A—Application of technical diagnostics, B—Management of maintenance resources, C—Maintenance process planning, and the dependent variable D—Sustainability of maintenance of technical systems. According to experts, the importance of the criteria coincides with the results obtained by a survey with 136 respondents

Optimizacija sadržaja nikla u punjenoj žici namenjenoj za zavarivanje mikrolegiranih čelika

This paper presents the results related to organizing production of flux-cored wire alloyed with Ni and Mo according to standard AWS A5.29 intended for the MAG welding process. On the experimental line for steel strip calibration and production of flux-cored wire two batches of flux-cored wire were produced with a constant Mo and Ni content at two levels (1.2% Ni in one and 2.6% Ni in the other batch). Experimental welding of steel plate samples was performed using the MAG process with two qualities of cored wire. Testing the structure and quality of the weld metal was done in order to optimize content of Ni in the alloyed flux-cored wire intended for welding fine grained micro-alloyed steels. Based on the analysis of test results of the microstructure and EDS analysis of the structure of welded samples and test results of tensile properties and impact energy, conclusions were made about the optimal content of Ni in the weld metal, and thus the choice of quality of flux-cored wire.U radu su dati rezultati vezani za osvajanje proizvodnje punjene žice legirane sa Ni i Mo prema standardu AWS A5.29 namenjeno za MAG postupak zavarivanja. Na eksperimentalnoj liniji za kalibraciju čelične trake i izradu punjene žice proizvedene su dve šarže punjene žice sa konstantnim sadržajem Mo i sadržajem Ni na dva nivoa (1.2%Ni kod jedne i 2.6%Ni kod druge šarže). Eksperimentalno zavarivanje uzoraka čeličnih ploča je izvedeno MAG postupkom sa dva kvaliteta punjene žice. Ispitivanje strukture i kvaliteta metala šava je izvedeno u cilju optimizacije sadržaja Ni u legiranoj punjenoj žici koja je namenjena za zavarivanje sitnozrnih mikrolegiranih čelika. Na osnovu analize dobijenih rezultata ispitivanja mikrostrukture i EDS analize strukture zavarenih uzoraka i rezultata ispitivanja zateznih karakteristika energije udara, dati su zaključci o optimalnom sadržaju Ni u metalu šava, a time i izboru kvaliteta punjene žice

Eksperimentalna laboratorija za razvoj dodatnih i pomoćnih materijala za zavarivanje i lemljenje (2)

The development of new materials and their use in construction of modern devices and structures requires the development of fillers and auxiliary materials for their joining. Development and mastering of production of adequate quality fillers in addition to scientific knowledge requires possession of appropriate experimental equipment. The experimental laboratory that has the appropriate technological equipment and devices provides real opportunities for development and mastering of production of new quality fillers and auxiliary materials for welding and soldering.Razvoj novih materijala i njihova primena u izradi savremenih uređaja i konstrukcija zahteva razvoj dodatnih i pomoćnih materijala za njihovo spajanje. Razvoj i osvajanje proizvodnje odgovarajućih kvaliteta dodatnih materijala pored naučnih i stručnih saznanja zahteva i posedovanje odgovarajuće eksperimentalne opreme. Eksperimentalna laboratorija koja poseduje odgovarajuću tehnološku opremu i uređaje pruža realne mogućnosti za razvoj i osvajanje proivodnje novih kvaliteta dodatnih i pomoćnih materijala za zavarivanje i lemljenje

Applying brazing for repairing electrical contacts

„Applying brazing for repairing electrical contacts“, The 48th International October Conference on Mining and Metallurg

Eksperimentalna laboratorija za razvoj dodatnih i pomoćnih materijala za zavarivanje i lemljenje

The development of new materials and their use in construction of modern devices and structures requires the development of fillers and auxiliary materials for their joining. Development and mastering of production of adequate quality fillers in addition to scientific knowledge requires possession of appropriate experimental equipment. The experimental laboratory that has the appropriate technological equipment and devices provides real opportunities for development and mastering of production of new quality fillers and auxiliary materials for welding and soldering.Razvoj novih materijala i njihova primena u izradi savremenih uređaja i konstrukcija zahteva razvoj dodatnih i pomoćnih materijala za njihovo spajanje. Razvoj i osvajanje proizvodnje odgovarajućih kvaliteta dodatnih materijala pored naučnih i stručnih saznanja zahteva i posedovanje odgovarajuće eksperimentalne opreme. Eksperimentalna laboratorija koja poseduje odgovarajuću tehnološku opremu i uređaje pruža realne mogućnosti za razvoj i osvajanje proivodnje novih kvaliteta dodatnih i pomoćnih materijala za zavarivanje i lemljenje

Determining the adhesion / cohesion strength of plasma spray coatings using the Rockwell - c method

The plasma spray coatings are subject to high influence of surface loads, corrosion, and temperatures which cause damage in the form of separation of the coating from the substrate or flacking of the coating from the substrate edges. Adhesion is the main factor that opposes the influence of the external loads, and defines the quality of the bond of the coating with the substrate. Each type of coating has a determined quality of adhesion as per appropriate standard in order to meet functional properties during operation. There is no universal coating test for all types of the coatings, the test is chosen depending on the technology used for the production of the coating, the type of material from which it was made and its thickness. One of the many tests that are used for assessment of adhesion / cohesion strength of plasma spray coatings is the scratch test. The aim of this paper was to evaluate the cohesive / adhesive strength of the plasma spray Ni22Cr10Al1Yalloycoating. The testing was conducted using the Rockwell C diamond indenter with a tip radius of 200 µm. The results showed that the scratch test is an efficient method for assessment of adhesion and cohesion of plasma spray coatings