Preview

Advanced Engineering Research (Rostov-on-Don)

Advanced search
Vol 13, No 7-8 (2013)

PHYSICAL AND MATHEMATICAL SCIENCES

5-14 415
Abstract

The simulation of stock price fluctuations is analyzed. The statistical criteria application allows drawing the conclusion on the investigated models’ validity. Alongside with well-known Kolmogorov-Smirnov and Anderson-Darling criteria, comparatively new Christoffersen and Berkowitz criteria are used to assess interval predictions. Berkowitz criterion is particularly effective when used to assess extreme price leaps within highly volatile periods, since it gives good results also for a small number of observations. It is shown that the customarily used time-series models with normal distribution and with Student distribution are applicable exclusively during relatively stable periods. Under the unstable conditions at the financial markets, models by means of which it is possible to describe a high probability of great price leaps are required. The time-series model with the heavy tailed distribution is studied. The recommendations on the portfolio management under the crisis time are provided on the basis of the performed calculations.

15-21 447
Abstract

Two finite element simulation algorithms for heterogeneous properties including the connectivity of mechanical and electrical fields are considered. In the first instance, heterogeneous mechanical and piezoelectric properties of the body are given in the form of analytical relationships in certain classes of functions. The second method assumes that the functions describing the heterogeneous properties are known in a discrete set of points. The changes caused by inhomogeneous properties are taken into account under the calculation of the element matrices. For this, in the second case, the interpolation of heterogeneous properties within the body is implemented in two ways: using thin-plate splines, and J. Meinguet’s splines. The proposed algorithms are implemented as modules of the ACELAN finite element complex. Examples of using the developed software for the calculation of the stress strain state of inhomogeneous elastic and electroelastic bodies are presented.

22-26 497
Abstract

The spatial contact problem with an unknown contact domain is investigated for a transversely isotropic elastic half-space the boundary of which is perpendicular to the planes of isotropy. For a circular punch, the contact zone, as a rule, is not a circle because the stiffness of the elastic solid boundary depends on the direction. The problem is reduced to an integral equation (IE) with respect to the contact pressure the kernel of which does not include quadratures. Galanov’s numerical method which makes it possible to determine simultaneously the contact zone and the contact pressure is used to solve the IE. The simple form of the IE kernel allows regularizing it by using a parameter which depends on mesh intervals as well as on anisotropy parameters. A well-known exact solution to a punch in the form of an elliptical paraboloid is used to verify the computer program. The numerical analysis has been made for different transversely isotropic materials contacting with conical and pyramidal punches.

TECHNICAL SCIENCES

27-34 421
Abstract

The problems associated with the possibility of the effective use of percussion-wave phenomena to create and implement advanced technological processes in industries are considered. Based on the analysis of vibrowave treatment process diagrams, the main steps of the method implementation are identified: deformation wave shaping, wave propagation, behavior, and affecting on the processed surface of the workpiece material. The experimental research on the wave processes under vibrowave part processing is resulted. It is shown that the skin hardening is affected by the deformation waves (their summation, dispersion into the environment, refraction), as well as by some part specifications of the waveguide devices and instruments. The most common vibrowave treatment process diagrams are performed, issues on their development are considered.

35-41 533
Abstract

It is shown that the creation of such technologies is caused by the necessity of making standard high-quality steel in composition and temperature. The secondary steel refining provides these conditions and, consequently, the efficient operation of the steel continuous casting plants. The commercially proven experimental results on the lime consumption effect on the slagging processes in the electric arc furnaces and on the further secondary refining in the ‘ladle-furnace’ units are presented. A flow chart of the complex processing Electric Arc Furnace Secondary Refining Steel Continuous Casting Plant is offered. It eliminates the increase of the slag oxidation degree under bottom blowing, aluminum loss in the bucket, and the increase of the oxygen concentration in the liquid steel. The proposed technology solutions to optimize the lime flow, slag adjustment, and to regulate the steel ladle stirring regime have permitted to raise the basic technical and economic indicators of the steelmaking at Oskolsky electrometallurgical works.

42-48 511
Abstract

The aim of the paper is to analyze the existing techniques of producing copper and aluminum compounds. The subject matter was to study the possibility of using FSW for producing copper and aluminum compounds. The process of producing the copper and aluminum lap joints is described, welding conditions are discussed. The copper and aluminum overlap joints microstructure is investigated. The factors affecting the strength of copper and aluminum lap joints implemented through FSW are analyzed. The corrugation effect is investigated, and the remaining hole is studied to the strength of the welded joint. Stress distribution diagrams in the copper and aluminum lap joints are shown. The tests to the strength of various lap joints are resulted, the weld cut structure is analyzed, its processibility is estimated, and the joint strength improvement method is presented.

49-57 491
Abstract

A new cyclone apparatus enable to control the part specifications depending on the dust environment properties and characteristics is designed. This leads to the increase of the processing off-gas collection efficiency. The experimental study is resulted, and the geometrics of the diversiform cyclonic devices is related to the dedusting effectiveness. It is shown that the dedusting efficiency is higher in the inverted-cone cyclones (ICC) than in the cylinder devices. The ICC optimal design factors (the immersion depth of an exhaust branch pipe, and the cyclone working part/bunker volume ratio) raising the dust cleaning degree are found. The ICC with controlled parameters and with the gravity-discharge bin is offered. The developed ICC allows the considerable efficiency increase of the preliminary air cleaning from the metal- and woodworking production dust.

58-64 456
Abstract

The experimental results of the antifriction polymer composite coating strength in the active aquatic environments with pH index varied in the range of 1.68…12.45 are presented. The coating strength is defined by the adhesion strength of the zone ‘coating-host substrate’. The interlaminate strength at the bending angle of 180 degrees is chosen as a criterion of the adhesion strength. Adequate regression models which allow calculating the coating adhesion strength value and estimating its retained strength percentage are obtained. The study on the polymer coating creep strain contribution to the working clearance forming in the tribocoupling is resulted. The obtained results show the significant increase of the composite coating stiffness at the relatively light loads applied that is caused by the capillary condensation of the aquatic environments in the micropores, and by their further diffusion into the composite layer. All the obtained data give a good indication of the antifriction coating properties degradation in the acid and alkaline aquatic solutions, as well as of the probable the antifriction coating life-time reducing.

65-74 478
Abstract

The problem of creating the mechanism of an expert system fuzzy inference meant for decision-making on the combine process adjustment is considered. The fuzzy inference algorithm is based on the domain models of ‘prior configuration’ and ‘process adjustment’. Fuzzification, composition, and defuzzification are general stages of the problem solution. The problem-solving mechanism is based on the deductive scheme (for the prior configuration problem), and on the inductive one (for the process adjustment problem). The specific feature of the proposed problem-solving algorithm is the hypothesis testing of emerging combining process non-conformances under the machine parameter variations. In this case, the validity of the exception condition generation when an additional breakdown in the technological process occurs is checked. The developed fuzzy inference algorithm and the domain model based on the fuzzy expert knowledge permit to approach considerably the solution to the decision-making automation problem under the combine process adjustment in the field environment.

75-87 470
Abstract

The results of DFT research on the band structure of zigzag graphene nanoribbons N-ZGNR/h-BN(0001) with ferro- and antiferromagnetic ordering are presented. It is suitable as a potential base for new materials for spintronics. Equilibrium parameters of the graphene nanoribbon atomic structure and boron nitride top layer are determined as well as the equilibrium bond length   between atomic layers of the 8-ZGNR nanoribbon and the substrate h-BN(0001). Change regularities of the valence band electronic structure and of the energy gap induction in series 6-ZGNR 8-ZGNR 6-ZGNR/h-BN(0001) 8-ZGNR/h-BN(0001) graphene/h-BN(0001) are studied. Spin state features at Fermi level, as well as the roles of the edge effect and the effect of substrate in the formation of the band gap in 6(8)-ZGNR/h-BN(0001) system are discussed. It is shown that 340 meV energy gap appears in 6(8)-ZGNR/h-BN(0001) systems. The contribution of the graphene nanoribbon edge and substrate in opening this energy gap is differentiated. Local magnetic moments on the carbon atoms in graphene nanoribbons in the suspended state and on the substrate with ferro- and antiferromagnetic ordering are estimated. It is shown that the local magnetic moments on the carbon atoms in zigzag graphene nanoribbons 8-ZGNRs with ferro- and antiferromagnetic ordering give almost identical values. The edge carbon atoms possess the largest local magnetic moments (0,28) relative to other carbon atoms.

88-96 503
Abstract

The smoothing throttle operations in the DC-motor circuit of a thyristor drive are studied. The main mathematical and graphic dependences of the smoothing throttle Lс inductance modification on the control angle, and on the number of the thyristor converter (TC) phases are given. The situation of the technological machine (TM) executing mechanism (EM) low conveying speed and of the armature pulsating current zone (PCZ) reduction is considered. In this case, it is reasonable to determine the minimal induction value of the smoothing throttle (Lс) at the boundary control angle αboun equal to 50—60 electric degrees for the increase in the mechanical characteristic rigidity of the DC motor. Then, the throttle magnetic conductor condition is defined by the branches of the specific limit asymmetric hysteresis cycle characterizing the electromagnetic processes in the magnetic conductor under the influence of the unipolar current pulses. Thus, the efficiency of the throttle core usage is defined through the incremental induction, i.e. through the difference in the residual induction B(0) levels, and the magnetic conductor material saturation induction. The airgap injection (δ) stabilizes the core equivalent magnetic capacity which can be broken by heating the throttle magnetic conductor with the armature current, by the environmental temperature fluctuations, and by the operation conditions of the thyristor drive. At the minimum inductance Lc of a smoothing throttle (for a boundary angle αboun), effects of the stabilizing factors of the core equivalent magnetic capacity (with airgap δ) decrease, PCZ is excluded. This permits to reduce electric losses in the power contour of the TC — DC-motor system, and also to form the required rigidity of the DC-motor mechanical characteristics, and the TM EM movement steadiness in the anchor low rotation frequency zones.

97-105 476
Abstract

The minimum cut height at which a stable grain (wheat) outflow starts is calculated. The energy balance of the system is analyzed. The specific work done by the viscous and skin-friction forces under the grain outflow from the hopper is eventually defined. The dependence of this work on both the transported layer height and the outlet opening height is specified. The grain outflow velocity at various bottom tilt angles and the outlet height are determined experimentally. Besides, the specific work done by the friction forces under grain moving along the end sidewalls and the hopper bottom is calculated. The energy needed to destroy roofs at various bottom tilt angles is found. The obtained results could be used in bulk side-feeding mechanisms.

106-116 549
Abstract

The problem of a comparative evaluation of a new technique design under developing the engineering solution and documentation is set. The created fifth-generation mobile power unit (MPU) is compared to the modern machine-process units based on a modern tractor identical in a draught class. The problem is solved through a numerically-analytical method with the parameter synthesis of the multipurpose machine-process units. The problem solution is reduced to detailed calculations in both variants. A nine-field grain zonal rotation rich in green sowing is considered. The analysis has shown that the created MPU with a variable-speed tram drive, two hinged systems unified in load-carrying capacity, and two power-takeoff shafts, will provide unit cost reduction actually caused by the design at a minimum 500 Rub./ha. MPU specifications are as follows: 50 kN class, 220 kW capacity, 9000…9500 kg weight. The essential novelty that distinguishes a new MPU from the standard tractors is provided through the usage of complex multipurpose operations.

117-131 468
Abstract

When evaluating a thermal state of the cutting zone, there is a need to define the thermal flow capacity on the tool contact areas which are determined by the tension magnitude. A review of the native and foreign research on the tension evaluation under cutting with account for the mechanical behaviour of the process materials, as well as the temperature, strain degree and rate is offered. Specialists in noncutting shaping have obtained experimental dependences that could be also used in machining — when the strain degree and rate can be calculated by the cutting theory formulae. The tension in the shear area can be determined indirectly — using the energy balance equation for the cutting process based on the experimental data on the cutting force components and corresponding speeds. As for the heat calculations, at first, analytic dependences defined on the base of the energy balance equation under cutting are recommended for the shear stress evaluation. Secondly, the dependences including relative shift value for the stress analysis should be used.

132-139 445
Abstract

The applicability of the acoustic emission method for monitoring the motor winding reimpregnation is proved. The dip infiltration technique is described. An acoustic emission monitoring model for the motor winding reimpregnation through the impregnation method by example of a plaster prototype is offered. Two project scenarios of bubbling and corresponding mathematical models are presented. In the first instance, bubbles entering the liquid collapse, as they are affected by the liquid hydrostatic load and surface tension forces. In the latter case, bubbles caused by the buoyancy force come to the top and collapse being affected by the intrinsic pressure. The acoustic emission impregnation control provides process quality improvement, precise determination of the process time. Thus, the residence time in the toxic area can be shortened, the shop hazard rating can be lowered (and consequently, costs of employee compensations and benefits can be optimized).

140-147 497
Abstract

To improve the operational conductometric steam quality control at the TPP, CHPP, and NPP, the technique for NaCl and NH4OH concentration in the saturated and superheated steam of the high- and supercritical pressure steam generators is developed, and a device for its implementation is offered. The error of determination in the range of the concentrations specific for the operated power plants is estimated. The equations describing the behavior of the thermodynamic dissociation constant, and limiting equivalent conductance of NH4OH in a wide range of state parameters that can be used in calculating the concentrations according to the proposed technique, as well as in water chemistry organization and management, are proposed. The assessment of the approximation error of dependences for the experimental data on the dissociation constants and limiting equivalent conductance is given.

SOCIAL SCINCES

148-155 426
Abstract

The guarantee of a steady social and economic development of the country is possible within the framework of the dynamically developing innovative progressive economy. Venture capital is an important factor of increasing the economic transformation efficiency achieved in many countries through the conversion of the national economy into the innovative way of development. In Russia, the importance of the venture financing development is connected with the fact that the domestic economy faces a burning issue of the capital sourcing for the development of innovation enterprises. The impulse of the venture capital development is considered to be the conflict resolution between its entities. The conflict resolution of the venture capital development and the innovative activity intensification depend in many respects on the formed institutional conditions in the country.

156-161 440
Abstract

The detailed functional-synergetic analysis of interdiscourse elements in the pragma-semantic system of the Business English discourse is considered. These elements catalyze self-organizing processes and generate new spontaneous functional qualities. Analysis of examples taken from both oral and written Business English situations proves that when semantic fields and structural peculiarities of Business English overlap with those of other types of the institutional communication, the pragma-semantic system is optimized, the communicative purpose is achieved easier despite the chaos at earlier stages of the system development, and the text acquires semantic versatility as a result of the interaction intensification between the discourse and the recipients’ consciousness which functions as a non-linear external environment. Manipulating the parameters of the functional system and conditioning constructive chaos increase the pragmatic potential of the business English rhetoric.

CONCISE INFORMATION

162-167 504
Abstract

In terms of the conceptual approach to the intelligent electronic documentation of mechatronic technological objects, the recommendations on the knowledge system database construction are given. The requirements with which databases of the intelligent electronic documentation of mechatronic objects shall comply are described, and the utilization of the relevant standards including S1000D is proved. An example of the database creation included in the knowledge system for improving the technological object performance quality is considered. The database structure and content are described. The structure of a database XML-document by the example of the multifunction processing center is given, and its nodes are described. A fragment of the database XML-document created in accordance with the above mentioned structure is illustrated. The database performance of the multifunction processing center is designed on the basis on the presented approach.



Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


ISSN 2687-1653 (Online)