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The subscription index of catalogue
“Russia press” - 18945 semi-annual,
15621 – annual.
It is issued in February 2004.
6 numbers a year
Mechanical engineering and engineering science
L.G. Nartova, V.V. Bodryshev.
ENGINEERING SURFACE GEOMETRICAL MODELING OF CHOSEN CLASSES
In the work there is offered a generalized meth-od for complex surface geometrical modeling with regard to a wide class of problems with an engineering direction. This method is based on the investigation of the applicability of frame, surface or solid-state mod-els.
The investigations were based on the analysis of the practical application of frame, surface and solid-state models and their images on the basis of present-day software tools.
By the example of deciphering a problem of a cylindrical object flow with a gas supersonic flow ac-cording to an intensity parameter of a frame image the 3D image of the “image intensity” function with the use of MatLab and SolidWorks programs is formed. The results of a geometrical solution are compared and an optimum surface image is chosen.
The investigation for a specific version provides a visualization of a supersonic gas flow motion and finally offers recommendations for an optimum design of a product. The method described may be used in the course of designing objects having a gas or liquid flow, complex surfaces in the products of aircraft industry. It is approbated at lecturing subjects “Engineering and Computer Graphics”, “Descriptive Geometry”, and also in scientific and diploma works of students with specialties “Aircraft and Helicopter Manufacturing”, “Aircraft Engines”, “Computer design in Aircraft Manufacturing”.
Key words: geometric simulation, algorithm, flat interpretation, 3D samples, vector-scalar presentation of surfaces
M.P. Zhuravlyov, K.Yu. Kravchenko, D.M. Elkind.
VIBRATION RESISTANCE AT PROCESSING BY END MILLS
WITH VARIABLE PITCH
In this work there is carried out an investigation of tooth different pitches with the purpose to increase a technological system vibration resistance at processing by end mills with a variable pitch and using elements of an operation modal analysis (OMA).
An experiment is carried out in the course of which there are performed tests for the level definition of vibrations and resonance frequencies of technologi-cal system oscillations at cutting by an end mill with a constant and varied pitch. The work results show that the average level of vibrations at the work with a mill with a constant pitch is higher than at the work with a mill with a varied one. The existence of some own fre-quencies in one direction for a mill with a constant pitch of teeth is defined that is possible in the systems with a great number of degrees of mobility. At the same time for a mill with a varied pitch the oscillations were observed only at one frequency of own oscilla-tions in one direction. In this connection a possibility of resonance oscillations decreases. During the work of the mill with a varied pitch the vibration waves with different length appear on the surfaces of cutting. A developed physical model of a technological system oscillation process at the work with a mill with a varied pitch shows that with the increase of a circular pitch the resultant oscillation displacements decrease
Key words: vibration resistance, face milling, cutting, vibrations, self-oscillations, operation modal analysis
V.M. Kapralov, F.V. Osipov, N.T. Nguen.
ASSESSMENT EXPERIMENTS ON FATIGUE RESISTANCE OF STRUCTURAL
MATERIALS AND MACHINERY
IA part of any complexity may be presented as a combination of smooth elements and those with design concentrators of mechanical stresses. As a consequence to a first approximation it is possible to investigate smooth samples for the assessment of material fatigue properties. An optimum formation of experiments on the assessment of fatigue strength, reliability and resource of the machine under design is a complex and significant problem. To carry out experiments for fatigue there are used testing machines of different kinds. A type of a testing machine is defined reasoning from the purpose of the work and possibilities of an experimentalist.
Subject to the process of changes in time of stresses in a sample one differs fatigue tests at harmon-ic loading (symmetric, asymmetric cycle), biharmonic (application of two and more harmonics), program (change of stress amplitudes according to a certain program) and random at different types stochastic processes.
The problem of machine reliability increase at the expense of destruction elimination in consequence of structural material fatigue is urgent in most of branches mechanical engineering.
A topicality is particularly urgent in branches where accidents and breakdowns owing to the destruc-tion of significant parts result in disastrous effects (power engineering, cosmonautics, aircraft, transport of all kinds and so on). For correct assessment of reliabil-ity and resource of significant parts subjected to time loads the test conditions approach to operation condi-tions.
The purpose of this work is improvement of de-sign-experimental methods for the assessment of ma-chine reliability at the expense of test conditions ap-proximation to operation loads.
Key words: fatigue strength, structural materials, machinery, damage accumulation, random operation loads, life prediction
I.V. Doroshchenko, M.N. Pogulyaev, V.B. Popov, V.A. Saveliev, V.V. Todarev.
RESOURCE SAVING ELECTROMECHANICAL PLANTS FOR COMPLEX
EQUIPMENT TESTS AT TRANSPORT ENGINEERING ENTERPRISES
The possibilities of resource-saving technology use at the development of energy-saving electrome-chanical test desks allowing the fulfillment of load tests of complex motor-car and tractor machinery are con-sidered. The circuits of test desks formation which are the most promising from the point of view of energy-saving are shown. A possibility for the formation of loading devices able to carry out on a shaft a resis-tance moment invariant with respect to a speed of shaft rotation
Key words: electro-mechanical test desk, loading tests of engines, energy-saving, resource-saving
E.A. Petrovsky, K.A. Bashmur, K.S. Terasmes.
ASSESSMENT OF VALVING SYSTEM DESIGN RISK UNDER
CONDITIONS OF EXTREME OPERATION
A working order of a pipe fitting is a significant aspect in a trouble-free operation of technological ob-jects in oil and gas production. It particularly concerns a safety valve protecting equipment against overpres-sure.
In the field of high pressure, costs and tempera-tures the installation of pulse-safety devices is prefera-ble. But, the complexity of their design and a substan-tial impact of a pulse valve sensitive element upon the whole correct work of a safety system in extreme con-ditions of operation increase design risks. With the purpose of their decrease there are considered possible circuits of the sensitive element standby in a pulse valve. By means of the method of reliability prediction on statistical models there are analyzed dependences of sensitive element failure probabilities as a spring and metal bellows in extreme conditions of operation. The conclusions on the application of a structural standby with a non-loaded reserve under definite conditions of operation and an optimum choice of structural materi-als for layers in multi-layer metal bellows are drawn
Key words: design risk, pulse valve, failure probability, metal bellows, redundancy
Informatics, computer engineering and management
PREVENTIVE ADAPTATION OF PRODUCTION CONTROL SYSTEM
AT INDUSTRIAL ENTERPRISES UNDER CONDITIONS
OF INNER AND OUTER ENVIROMENT CHANGES
The present day at many industrial enterprises there is a problem which consists in the following: dis-crepancy of management decision-making to the re-quired state of production caused high production costs, a high duration of production cycle and a non-observance of order terms. To solve this problem the author has offered, from the point of view of system positions, the peculiarity investigation of diverse dy-namic production at an industrial enterprise and its operational control. As a result there is developed a universal system for the operational management of dynamic diverse production and an integrated infor-mation system for its functioning. On the basis of sin-gle models the system allows planning, taking into account and controlling manufacturing products made as a single specimen, small batch production, medium batch production, and large batch production, and also in large quantities
Key words: industrial enterprise, operational management, information exchange, dynamic diverse production, integration, data base
K.A. Batenkov, N.I. Myasin, A.V. Korolyov, M.V. Ilyushin, E.A. Kozhin.
PULSE INTERFERENCE MEASUREMENTS IN DIGITAL USER LINES
Present-day measuring procedures of pulse in-terference are not perfect. The application of the MATLAB mathematical modeling environment and a personal computer (PC) allows creating an efficient complex for measuring the interference of a pulse character. Kinds of the pulse interference are similar in the form, but differ considerably in their peak values of the amplitude. Different kinds of home equipment generate noise impacts in view of peculiarities of their structural formation and an elemental base used. For the qualitative analysis the of the pulse interference impact upon a line of communication it is necessary to use a mathematical apparatus which allows estimating completely the degree of the interference impact. The data obtained must contribute to the development of engineering solutions and methods for the compensa-tion of the pulse interference impact upon digital user lines.
Key words: pulse interference, measuring complexes, digital user lines
Yu.A. Kropotov, A.A. Belov, A.Yu. Proskuryakov.
TIME SERIES PROCESSING USING WAVELET-TRANSFORMATIONS
FOR ACCURACY INCREASE IN INFORMATION PRESENTATION
The purpose of this work is development of the method for error decrease in information presentation in telecommunication systems of monitoring by means of filtering noise and fluctuations of levels in time se-ries counts. To solve this problem there is used a meth-od of wavelet processing. In particular, the decrease of time series fluctuation impact is carried out by means of the computation of approximating coefficients of the n-th level which corresponds to the fulfillment of multi-level statistical processing the values of time series counts and equivalent to a signal passage through a filter of low frequencies.
There was developed and investigated a simula-tor and its statistical parameters of processing with a wavelet transformation of time series counts. It is shown that time series wavelet processing and the ap-plication of approximation coefficients of wavelet-decomposition increase the accuracy of data presenta-tion. It is also ensured at the expense of noise compo-nent suppression through a method of thresholding upon detailing coefficients of decomposition.
In the paper there are shown investigations of the dependence of approximation coefficient correla-tion time upon a wavelet decomposition level. There was also investigated a depression dependence of noise components of time series count fluctuations of emis-sion at the processing with the wavelet decomposition with obtaining approximation coefficients of different levels.
The fulfilled analysis of the results of different criteria application and approaches to smoothing on the basis of threshold processing the detail coefficients of wavelet decomposition has shown that at smoothing time series there will be an optimum choice of an adaptive penalty threshold level. The presented results of smoothing with an adaptive penalty threshold have shown that the signal-noise ratio increased for more than 2.53dB in comparison with the initial one.
Key words: : time series, wavelet transformation, accuracy of information presentation, threshold processing, noise depression.
ELECTRONIC CIRCUIT FAILURE MODELING USING NEURAL NETWORKS
The object of researches is electronic circuits. For elements of the circuit there are defined character-istics of input and output signals in a working condition and at a state of non-operability. The subject of re-searches is a reliability of electronic circuits (EC). The purpose of the work consists in the automation of relia-bility tests at the expense of the failure simulation of electronic circuit elements with the aid of artificial neu-ral networks (ANN). There is developed a method for carrying out EC reliability tests with the use of automa-tion means. During tests one simulates different fail-ures of circuit elements. For element failure simulation there are used ANN trained fragments. The ANN fragments are trained with the use of the selection of input and output signals of the element in a working condition and at a state non-operability. For the signal formation of a working condition a signal generator is used. For the signal formation of a state of non-operability the signals from outputs of a noise genera-tor are added. To reduce time and costs for training there is offered for use the ANN of a special switch type which allows copying, replicating, modifying ANN, training and forming ANN from its fragments
Key words: : electronic circuits, failure modeling, working condition, state of non-operability, artificial neural networks.