Кафедри
Постійне посилання на розділhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/35393
Переглянути
3 результатів
Результати пошуку
Документ Mathematical model of server requests intensity description(Національний технічний університет "Харківський політехнічний інститут", 2020) Pustovoitov, Pavlo; Kostyk, Kateryna; Kompaniiets, Volodimir; Voronets, Vitalii; Haidar, HasanThe paper is devoted to the mathematical model development of non-stationary flow of requests from clients to the database in order to modulate the quality of service. The mathematical model of the queries number fluctuations to the database has the form of a regression equation and allows more accurate modeling of the connections pool size in the servlet. Connection pool is a pattern that helps to reduce responding time for queries to databases. To another hand the extra used memory wasting server resources. The task of calculating the optimal connection pool size could be solved by verity of mathematical apparatuses that demand information about intensity of stationary incoming queries flow. It is known, that real incoming queries flow is non-stationary. In the paper was suggested mathematical model of flow intensity fluctuations with daily and hourly harmonic vibrations. Statistics analyses of model adequacy was made, homogeneity of variances is checked, the significance of the coefficients of the regression equation was estimated. The obtained mathematical model describes fluctuations in the intensity of clients' requests to the servlet during the week. The mathematical model can be used to predict the load on the server or to build a simulation model of the query service system. The adequacy of the model is checked, the homogeneity of variances is checked, the significance of the coefficients of the regression equation is estimated, the adequacy of the regression equation is checked, the analysis of the autocorrelation of the residues is carried out. The results obtained in the article give further development for modeling process technologies in the field of information systems and can be used to calculate the load on the server with a non-stationary flow of requests from clients to the database.Документ Development of a combined technology for hardening the surface layer of steel 38Cr2MoAl(Технологический центр, 2017) Idan, Alaa Fadhil І; Akimov, Oleg; Kostyk, KaterynaDevelopment of new combined strengthening technologies for treatment of steel surface layer is a topical issue. Influence of conditions of combined hardening treatment on variation of properties of the surface layer of 38Cr2MoAl steel was studied. Experimental data have shown that thickness of the hardened layer of 38Cr2MoAl steel, depending on the process conditions of combined treatment, varied in the range 0.18 to 0.69 mm with the surface hardness being 10.5-12.5 GPa. Mathematical models of the hardened layer thickness and surface hardness were obtained depending on variation of velocity of the laser beam travel and duration of nitriding of steel following the combined treatment. In their structure, the models are regression equations. These regularities have practical technological significance and ensure prediction of values of the hardened layer thickness and surface hardness. Nomograms of simultaneous influence of velocity of the laser beam travel and duration of nitriding on thickness of the hardened steel layer and surface hardness were constructed. Nomograms make it possible to determine concrete conditions of hardening processing, starting from specified thickness of the hardened layer or the surface hardness of 38Cr2MoAl steel, respectively and also to solve inverse problems. This method is suitable for hardening hard-to-reach part sectios and local contact areas.Документ Development of an iron-based alloy with a high degree of shape recovery(Технологический центр, 2017) Ahmed, Sundus Mohammed; Akimov, Oleg; Kostyk, KaterynaWe examined a technological process for receiving an ironbased alloy with a shape memory effect, substantiated the choice of chemical composition of the alloy, and selected thermal treatment modes. Research results into scale resistance revealed at heating the samples in the temperature range of 600-1000 °C, surface oxidation was not observed. In the course of experiment on corrosion resistance of the alloy, we found that the alloy is corrosion resistant and is not inclined to change the weight when exposed to 10 % solution of sulfuric acid. Study into the microstructure confirmed the existence of dispersion hardening in the alloy after the aging regimes. Diffractogram of the alloy after hardening at a temperature of 1150 °C and cooling in the open air showed a surge that corresponds to γ-Fe, therefore, the content of residual austenite in the alloy is 100 %. Research results demonstrated that the degree of shape recovery of the proposed alloy is 78-97 %. The proposed alloy is plastic enough; it may undergo hot, warm and cold deformation in the open air. We constructed mathematical models of the impact of chemical composition of the alloy on tensile strength of the alloy and the values of a shape memory effect. The iron-based alloy with a shape memory effect can be obtained both under laboratory conditions and on industrial equipment.