The problem of increasing reliability of multi-version software of modern control systems for industrial automation was reduced to a problem of pseudo-Boolean optimization problem of knapsack type. For solving this problem, various methods were suggested.
Machines. Technologies. Materials.
Vol. 9 (2015), Issue 11
Table of Contents
The conditions are substantiated for the loss of thermodynamic stability of a tribosystem and for its adaptation with a decreasing wear rate at the moving frictional contact of parts from materials with an ultrafine-grained structure produced by equal-channel angular pressing. The regularities of the influence of the structure’s dispersion degree and the friction contact’s temperature on the tribotechnical characteristics of ultrafine-grained materials are established theoretically and experimentally.
The present article deals with monitoring the changes in the mechanical properties of composites with polymer matrix. The composite was formed from the PA matrix and glass fibers. The composite contains 10 – 30 % glass fibers. The mechanical properties, tensile strength and flexural strength were evaluated on samples of the composite before and after UV radiation on the sample. The largest decline endpoints was recorded in 500 hours of UV exposure. Light microscopy was evaluated distribution of glass fibers in the polymer matrix and the presence of cracks caused by UV radiation.
MODELING AND STUDY OF THE PROCESS OF BILLETS EXTRUSION WITH ADDITIONAL BACK- PRESSURE IN EQUAL CHANNEL STEP MATRIXpg(s) 20-22
This work is devoted to the study of stress-strain state and power parameters in the simulation of the process of extrusion billets with additional back-pressure in equal channel step matrix. Analyzing the obtained results we can conclude that the matrix without backpressure cannot achieve complete closing of internal defects of a deformable metal. The backpressure created by the increase of the roughness of the output channel of the matrix, has a beneficial effect on the stress-strain state of the metal, which in turn allows you to provide the best structured deformable metal
MODELING AND OPTIMIZATION OF ELECROCHEMICAL MACHINING OF 321-STAINLESS STEEL USING RESPONSE SURFACE METHODOLOGYpg(s) 23-27
This paper demonstrates a systematic approach for achieving comprehensive mathematical models for electrochemical machining (ECM) of 321-stainless steel based on the response surface methodology (RSM). Machining voltage, tool feed rate, electrolyte flow rate and concentration of NaNO3 solution were considered as the machining parameters while material removal rate (MRR) and surface roughness (Ra) were considered as the process responses. Experimental plan was performed by a central composite design (CCD).
The proposed mathematical models statistically have been evaluated by analysis of variance (ANOVA). Analysis shows that the RSM method has been appointed properly as the design of experiments (DOE) method for resolving curvature in ECM process responses. Also, the optimal machining parameter for single optimization of MRR and Ra is determined by desirability function. The results showed that the proposed approach is an effective and suitable way for modeling and optimization of the ECM machining process.
In this study hoop tensile properties of continuous fiber reinforced composites pipes are investigated. The test pipes were manufactured of glass fiber and epoxy resin by filament winding method with three different winding angle configurations (10°, 45° and 90°). Three specimens from each model of filament wound pipes with help of split-disk tests were tested and the hoop tensile strengths and modulus of elasticity were determined. From received results it is concluded that, mechanical properties of composite specimens are depended from winding angles in filament winding technology, whereas that bigger winding angle lead to higher hoop tensile properties of filament-wound tubular samples. The optimal values for the hoop tensile strength are obtained for the samples winded with 45° winding angle.
Various designs of equipment used in heat treatment furnaces are presented. The equipment is assembled from components varying in shape and size. In this case study it is composed of castings only. Castings are made from creep-resistant alloys, mainly cast austenitic steel and nickel alloys, using gravity poured sand molds. The design should allow for the simultaneous solidification of all thin-walled cast parts. The study focuses on the equipment for the heat treatment of parts of uncommon shape and size, or parts that require special heat treatment conditions. It is used for the charge formation in furnace and transport of this charge inside and outside the furnace. Different designs are illustrated. Their shape and size depends on the type of furnace, production volume, and the number and shape of heat-treated parts.
The paper considers the issues of qualimetric assessment of quality of reinforced steel. The dependences of the rate group of the mechanical properties from room profile. Built a regression equation characterizing the effects of deformation processing on the quality of rebar.
This article provides a way to detect fatigue cracks in welded gearwheel at reinforcement dimensional cutting mechanism (flying shears) of rolling mill by analyzing the direct spectrum of vibration. This method is progressive and allows through regular vibration measurements to assess equipment condition and predict performance.
The evaluation of yield stress -σS is frequently encounter in material testing. In this method there is necessity of manufacture of test-tube from tested material or detail and made tension test. There is destructive method. For many details there is not acceptable. In material testing there is interest to non-destructive evaluation of yield stress σS for the materials and details. In this paper is lock at possibility for non-destructive evaluation of yield stress σS by means measure Brinel’s hardness – HB or velocities of propagation of longitudinal and transversal ultrasonic waves – VL and VT in tested materials and details.
The importance of the Black Sea for modern Georgia is invaluable. It represents one of the important natural formations for the common geographical location of the country, resource potential, the main artery of recreational zone and foreign relations. Therefore, the security, economic welfare and future in general depend on effective use of economic potential of the Black Sea and its ecological condition.
The article deals with the ecological condition of the main problems of the Black Sea. Special attention is paid to international transport and energy projects. It is proved that the projects that have been implemented and planned the "Blue Stream" and "South Stream" (so called "Turkish Stream") represent potential threats to the Black Sea in terms of environmental deterioration. Modest conclusions are made in the article concerning the joint efforts of the Black Sea countries directed to support transport and energy projects, realization of which will impact ecological condition of the Black Sea. In the opinion of the authors, the "Nabucco" project represents the very transport- energetic project.
In Kosovo enterprises, the usage of CAD systems are limited, in the beginning as a result of higher prices of hardware and software equipment and afterwards as a result of the war events that Kosovo and their economy passed. This paper reports the results and conclusions drawn from a questionnaire survey concerning the use and implementation of computer-aided design (CAD) in the Kosovo furniture industry.
It was regarded as important to find out what impacts implementation has on the usage of CAD and whether companies in the furniture industry think the use of CAD could improve their product development. Less than half of all product-developing companies in the Kosovo furniture industry are using CAD today. The study found that the following factors are involved in successful implementation: management support, realistic budgeting, selection of system and effective, company-specific training. Most CAD users are satisfied with their system and think that it fulfills their needs. Many of the difficulties referred to by respondents can be related to the implementation phase, and they could be avoided. In general, the furniture industry considers that CAD improves their product development work.
E-learning, seen in the ergonomic aspect, is a complex and intense human activity that is subject to investigation and analysis in order to optimize it. The quality of education is seen as a trinity of its effectiveness, efficiency and satisfaction – criteria that are defined, studied and assessed using a specially developed, original methodology of the authors. These criteria were used to investigate BA, MA and Ph.D. students in two consecutive years.
We are witnessing the rapid growth of the energy prices and there are expectations that they will continue to grow in the future. Consequently, there is a constant need of energy efficiency improvements that could be achieved by decreasing of energy losses, smart and efficient energy utilization and conservation of energy resources.
The water supply systems are large energy consumers. So, the investments in the increasing of their energy efficiency will not only have an economic dimension, but also they could have large positive effect on the environment protection. In this paper, an analysis of the degree of efficient usage of the energy and the appropriate techno-economic analysis of the energy consumption for a real water supply system is presented. Few methods for increasing the energy efficiency of water supply pump stations and an analysis of the potential benefits of this method are proposed and discussed too.