Papers by Keyword: Quality

Abstract: The article examines the aspects of predicting the durability of equipment components assembled using polymer reinforcing compounds. A method for calculating the key parameters of joints that have a primary impact on the durability of friction units is presented.

Abstract: Research work was carried out on the test units with the conditions close to the industrial ones to study the material composition impact of the concentrates produced from various types of the Kachkanar titanium magnetite ores on the fluxed pellet metallurgical properties. In order to study the pellet properties with a small number of experiments the simplex-lattice design method was used. Data was quoted on variation of key quality parameters of pellets from particular concentrate types and their mixture at certain horizons throughout the bed height with regard to a conveyer-type roast machine. An expression was obtained for the weighted average strength of commercial pellets. According to the data obtained in the course of the experiments with certain concentrate types and their well-balanced mixtures the expressions were introduced as incomplete cubic polynomials describing the key quality parameter variations of the pellets from optional composition mixtures. The work results are of certain interest for the process engineers and specialists dealing with iron ore raw material preparation, as they allow forecasting of high quality fluxed pellet production from various material composition concentrates.

Abstract: The notion of quality is defined as the totality of the attributes and essential aspects by virtue of which one is what it is, distinguishing itself from the other things. The article has as its starting point the definition of quality according to SR EN ISO 9001:2015. This standard defines the quality like „the set of properties and features of a product or service that gives it the ability to meet the expressed and implied needs of the customers”. Our article treats three categories of expressed and implicit necessities: the expressed and implied needs of clients, as beneficiaries of Products/Work/Services (P/W/S); the expressed and implied necessities of an efficient production management; the expressed and implicit necessities of society as a whole. In the article we present and analyze the components of quality (decalogue of quality) and the correlations between them. The quality term involves two main aspects (components), namely: utility, expressed by degree of utility (this component quantifies the extent to which the P/W/S meets the customer's needs and consequently sells). Technical component (intrinsic), which refers strictly to the technical characteristics of P/W/S. It is obvious that there is mutual dependence between the two components of the concept of quality (biunivoc).

Abstract: Additives were selected and a method for modifying the structure of gypsum-containing materials for construction purposes and a method for their dispersion were developed. Based on the selected modifiers, effective compositions of composite gypsum-containing materials based on local and secondary raw materials were developed, and an increase in their strength and resistance to water was established.

Abstract: There is a crucial need to achieve a more sustainable management of the world's water resources due to serious water scarcity and water pollution. A whole series of problems are related to these needs, but the problem of water resources is one of the most prominent. This paper aims to point out certain solutions to address these issues, such as providing a framework for the concept of integrated management of water resources in Mehedinţi County. Water quality protection should be a permanent concern; therefore, every member of society must bring out his own conscious and responsible contribution. To this end, by all means of information or education, it is necessary to debate the social, economic and ecological importance of problems and actions in order to prevent and combat pollution of water resources.

Abstract: Throughout the history of modernization of welding processes, in many cases the research has focused on optimizing the location of energy in the welding area, with the continuous improvement of the quality of welded joints. The welding processes in shielding gas environment with fusible electrode (MIG-MAG) have achieved superior performances regarding the increase of the current density around of the welded joint, simultaneously with the increase of the universality degree of their application. This paper is based on researching the possibilities of concentrating energy in the welding area, seeking to obtain both more favorable energy yields and an increased quality of welded joints. In the paper are shown a some results obtained following a comparative study on 2 welding processes in MIG-MAG protective gas medium, differentiated mainly by the metal drop transfer mode: by spraying (Spray arc), respectively by synergistic transfer (Arc pulsed), applied for corner welding of alloy steel sheets.

Abstract: Technologically, ultrajet mesodiagnostics (UJM) consists of local hydroerosive indentation by ultrajets (UJ) of water on the surface of the analyzed object (OA) and the subsequent study of the results of this minimally invasive microdestructive effect on its surface layer. Obviously, mathematical models’ construction of the functional relationship between the informative-physical signs of hydroerosive UJ destruction and the surface layer’s state parameters of various OA, primarily their defectiveness, is very important for the development of this potentially promising technology for ensuring the quality of critical products, mainly aviation and other industries. In this regard, the work proposes a probabilistic UJM model, which consists of analyzing the kinetics of the formation of an aggregate set of eroded particles, as a process caused by a combination of appropriate necessary and sufficient conditions for its implementation. The former include the topographic features of the microdefectiveness’ characteristics of the surface layer material, and the latter consist of a certain variational-force hydrodynamic effect of the diagnostic UJ on it. This approach made it possible to obtain calculated data related to probabilistic distribution of the UJ-eroded particles’ sizes of hypothetical OA, as a coordinate function describing the microdefects’ concentration in its surface layer. These functions are close to the available results of experimental UJM of typical and promising materials used in the manufacture of machinery technology.

Abstract: The quality of the hot-rolled plate up to 36 mm thick was estimated by the percentage of rolled products, sorted due to the presence of a surface defect "Non-metallic inclusions", and internal defects, detected by ultrasonic plate control. The analysis of the data on the total sorting of hot-rolled plates demonstrated that the amount of sorting differs significantly on the melting from which each series of tubular metal casting commenced, compared to all the other melting in the series. The sorting of the sheets rolled from the metal of the first in a series of melting proved to be 1.9 times higher than that of the metal of all other melts. The main reason (in 68% of cases) of sorting is the presence of non-metallic inclusions on the surface of the plates. The effect of sorting of hot-rolled plates on non-metallic inclusions of various parameters has been studied: the duration of the intermediate ladle-heating; the length of time from the end of the heating of the intermediate ladle, prior to the beginning of the casting; lining temperatures of the intermediate ladle before the beginning of casting; duration of filling the intermediate ladle; the filling rate of the intermediate ladle with metal; mass of metal in the intermediate ladle before the beginning of casting into the crystallizer; chemical composition of metal; overheating of the metal over the liquidus point at the beginning, middle and end of the casting. On the sorting of flat products for non-metallic inclusions, of all the parameters considered, a statistically significant effect is due only to the overheating of the metal above the liquidus point, which varies in the range from 19 to 35 ° C. In order to obtain an acceptable quality of both the surface of slabs and the surface of hot-rolled plates for non-metallic inclusions, the first in a series of melts recommends overheating of the metal in the intermediate ladle above the liquidus temperature of 30-35 ° C.

Abstract: Biogas quality in many installation of anaerobic digester for processing organic waste are found not optimum, especially in developing country where understanding of anaerobic processing is not well known. The methane content in the biogas are usually low that make it not possible to be utilized as a fuel of the engine. Biogas Purification usually will be introduced as a solution. But this idea is about complicated for simple or small anaerobic digester. Other solution is suggested by using enrichment of biogas by using other fuel such as hydrogen or blended with city gas such as LPG gas. But for preparing hydrogen gas or commercial will also costly. This research introduces simple technique for biogas enrichment by using denatured alcohol. The biogas contents were found around 30% vol. methane (CH₄) and around 2% Carbon dioxide (CO₂). The price of denatured alcohol is relative cheap because the selling tax is not as much as drinking alcohol. Engine with bigger combustion (420 cc) chamber was prepared for this purpose to make possible to be fueled with biogas. The compression was set to reach 10 bar. The clearance of the both intake and exhaust valve was set in order to be possible to be running by using biogas. The biogas-air mixer was design for this purpose. The carburetor was set for use of denatured alcohol. It is found that the engine is running well by using biogas fuel that is enriched by using denatured alcohol. The emission was found better comparing using gasoline for the same engine. The fuel consumption is reported for future economic analyses.

Abstract: Extending the lifetime of energy facilities is extremely important today. This is especially true of nuclear power plants, the closure (or modernization) of which poses enormous financial and environmental problems. High-quality repair of reactors can significantly extend their service life. One of the critical parts is heat exchangers, the tubes of which quite often fail. Sealing, as a type of repair of heat exchanger tubes by the plugs, is promising provided that the joint quality is high. Practical experience in the use of welding to solve this problem has shown the need to search technological solutions associated with increasing the depth of penetration and reducing the area of thermal effect. The aim of the work was to develop a highly efficient technology for repair and extension of service life of heat exchangers of nuclear power plants based on the results of studying the technological features of laser welding of joints of dissimilar austenitic steels AISI 321 and AISI 316Ti in the vertical spatial position. Based on the results of the analysis of mechanical test data, visual and radiographic control, impermeability tests and metallographic studies of welded joints, the appropriate modes of laser welding of plugs have been determined. The principal causes of defects during laser welding of annular welded joints of dissimilar stainless steels are determined and techniques for their elimination and prevention of their formation are proposed. Based on the results of the research, technological recommendations for laser welding of plugs in the heat exchange tube of the collector are formulated, which significantly improves the technology of repair of steam generators of nuclear power plants and extends the service life of reactors.