Normunds Kante, Mykola Kryshchuk and Jurijs Lavendels
The method of obtaining the plan of experiments in multidimensional space is considered in the paper. The method is based on assumptions of uniform distribution of charged particles in infinite space. To obtain the plan of experiments, the infinite multidimensional space is replaced with a hypercube whose surface models influence infinite space. The software is developed, and practical results in two-dimensional space are acquired. There are no basic problems to carry out calculations in multidimensional space.
The goal of the paper was to assess the strength of the fertilizer granules obtained by non-pressure granulation method. The granulation process was carried out in plate granulator, according to the three-level experiment plan. A mixture of raw materials prepared in a Polish factory of agrochemicals for agriculture and horticulture was used as a study material and water was used as a wetting liquid. Granulator design parameters and process parameters were treated as entrance sizes of the experiment. Three different angles of granulation blade were used in experiments. This paper presents: the results of study of equivalent diameter size and the impact of changes in the angle of granulating blade on the strength of obtained granulate. Pfost apparatus and a set of sieves used in granulometric sieve were utilized in this study. A relation was suggested P∞ = f(α, ϰ, n, ww, t). The results were presented in the form of graphs and tables. Conclusions were presented.
One of the flexibility parameters of semi-rigid joints is rotation capacity. Plastic rotation capacity is especially important in plastic design of framed structures. Current design codes, including Eurocode 3, do not posses procedures enabling designers to obtain value of rotation capacity. In the paper the calculation procedure of the rotation capacity for stiffened bolted flush end-plate beam-to-column connections has been proposed. Theory of experiment design was applied with the use of Hartley’s PS/DS-P:Ha3 plan. The analysis was performed with the use of finite element method (ANSYS), based on the numerical experiment plan. The determination of maximal rotation angle was carried out with the use of regression analysis. The main variables analyzed in parametric study were: pitch of the bolt “w” (120-180 mm), the distance between the bolt axis and the beam upper edge cg1 (50-90 mm) and the thickness of the end-plate tp (10-20 mm). Power function was proposed to describe available rotation capacity of the joint. Influence of the particular components on the rotation capacity was also investigated. In the paper a general procedure for determination of rotation capacity was proposed.
The research deals with improvement of methods and systems of controlling integrated power systems (IPSs) on the basis of intellectualization of decision-making support. Complex analysis of large-scale accidents at power facilities is performed, and their causes and damages are determined. There is substantiated topicality of building condition knowledge-bases as the foundation for developing decision-support systems in power engineering. The top priorities of the research include developing methods of building a knowledge base based on intensity models of control actions influencing the parameters of power system conditions and introducing the smart system into information contours of the automated dispatch control system (ADCS), as well as assessing practical results of the research. To achieve these goals, the authors apply methods of experiment planning, artificial intelligence, knowledge presentation, mathematical simulation, and mathematical statistics as well as methods of power systems studying. The basic research results include regression models of a power system sensitivity to control actions, methods of building a knowledge base based on the models of sensitivity matrices, a structure of the smart decision-support system, a scheme of introducing the decision-support system into the operating ADCS environment. The problem of building a knowledge base of the dispatch decision-support system on the basis of empirical data resulted from calculating experiments on the system diagram has been solved. The research specifies practical efficiency of the suggested approaches and developed models.
Marek Kułażyński, Krystyna Bratek and Jerzy Walendziewski
Optimization of an active phase composition in the low-temperature nitric oxide reduction catalyst
In the first research studies series a selection of the quantitative composition of catalyst active phase composition (iron, copper and manganese) deposited on mineral-carbon support was carried out. It was found on the basis of the selection studies series that the best results were attained when copper and manganese were used as catalyst components. The quantitative composition of the denitrogention catalyst was estimated using a statistical method of experiment planning and metals content changed in the range 0.5 - 1.5wt % for both metals. Catalyst activity in nitric oxide reduction by ammonia was determined in the dependence on an active phase composition in the temperature range 100 - 200°C, at GHSV (Gas Hour Space Velocity) 6 000 and 10 000 Nm3/m3h, NO concentration 400 ppm, NH3/NO ratio 1:1. A graphic presentation of the obtained results was made using the UNIPLOT program. The highest activity in nitric oxide reduction by ammonia presented copper - manganese catalysts prepared by the impregnation of mineral-carbon support with active metals salts solutions and calcination after each metal impregnation with copper (up to 1.5 wt %) and manganese (up to 1.5 wt %).
Using the pad welding technique it is possible to regenerate machine parts or improve surface properties such as abrasion, corrosion and aging resistance. The regeneration process with the use of pad welding can be performed using the same equipment, which we use for welding. Metals and their alloys with required properties in the form of wire, rod or powder are selected for the additional material. To ensure optimum processing conditions and economic efforts should be made, while providing a high deposition efficiency for the small amount of metal in the pad weld substrate. The pad welding process for the test subject should be carried out by preheating to evaporate the moisture and reduce the porosity of the weld. This treatment is required depending on the carbon equivalent. This article is an introduction to a series of investigations that will allow you to choose the best parameters of pad welding GMA (gas metal arc) method, steel C45E with wire CASTOMAG 4554S. Steel samples were prepared and preheated to 300°C. Using the orthogonal experiment plan, the influence of selected parameters on the geometry and depth of fusion was determined. The analysis was based on current and wire feed speed. The test was carried out for three current values: 60, 75, 90 A and wire feed rate of 1.5, 2, 2.5 m/min. The purpose of the analysis was to select appropriate technological parameters. Obtaining the smallest share of the base material in the weld pad and impact assessment parameters for welding seam geometries. For the analysis of the results of multiple regression was used.
The changes in tree layer saplings, shrub, field and moss layer in Järvselja Nature Reserve virgin forest compartment (JS226) were analysed on the ground of data collected in 1955, 1985, 1993 and 2012. Four forest stands (sub-compartments) were studied; in every stand one 4 × 4 m sample area was established: area A1 represented Hepatica nobilis and Anemone nemoralis dominanted spruce stand, area A3 – drained transitional mire pine forest, area A4 – Mercurialis perennis-rich spruce stand and area A5 – Hepatica nobilis and Anemone nemoralis dominanted aspen stand. The number of tree layer saplings and shrub layer stems, as well as their species content have changed largely in all sample areas, being a bit more stable only on area A1. In field layer the abundance of initial dominant species changed remarkably in all areas or were replaced by other species in the course of succession. Changes in moss layer were the most striking in drained transition mire forest (area A3), where Pleurozium schreberi, Sphagnum centrale and S. capillifolium dominating in 1955 were replaced by S. centrale in 1993. The experiment planning in the current study is regrettably insufficient: to study forest communities succession using only one 4 × 4 m sample area in every stand does not allow to gather representative data about the vegetation structure and its variation limits. Moreover, in that way it is not possible to separate the time-induced successional trend from the drainage impact that has an obviously prevailing importance in forest compartment JS226 being surrounded by ditches.
In this article, the impact of selected parameters of heating using a gas torch on the hardness of hardened alloy steels C45 was presented. The staff of the ship’s engine room sometimes uses flame hardening during casual repairs of the machines weared as a result of operational extortions. The purpose of emergency repairs is to restore the possibility of work of ship machinery and equipment for the duration of the vessel’s journey. An acetylene-oxygen torch was used to heat the steel. As the analysed parameters of the technological process, the heating time and the distance between the nozzle and the workpiece were selected. The values of the mentioned parameters have been selected so that the temperature of hardened steel is in the range from 800 to 1250 °C. The following values of the adopted machining parameters were used: the heating time was 60, 85 and 110 seconds, while the distance of the torch nozzle was 10, 20 and 30 mm. After heating, the samples were cooled by immersing in water. The research was based on a randomized orthogonal experiment plan. The purpose of the quantitative assessment of the influence of heating parameters on the hardness of hardened C45 steel, done statistical analysis variance analysis, multiple regression and mathematical optimization by the Tagichi method. Conducted tests and statistical analysis showed a significant effect of selected parameters of flame heating on the hardness of hardened C45 steel. The greatest influence on the hardness of the steel is the distance between the nozzle and the workpiece. The highest value of hardness was obtained using the following parameters of flame hardening: nozzle distance 30 mm, heating time 60 seconds.
Magdalena Bucior, Lidia Gałda, Feliks Stachowicz and Władysław Zielecki
Precyzyjnej, Warszawa (in Polish).
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