The paper contains calculation on durability of a reinforcement bars with a constructive and technological defect. The factors determining constructive and technological durability of reinforcing bars have been investigated in the paper. The paper demonstrates classification of reinforcement bar parts in accordance with danger of constructive and technological influences.

 

The paper presents methodology and results of investigations pertaining to profilograms of specimen surfaces being polished using electric pulse method and being made of steel 10 и 20Х13 with the help of correlative transformation. It has been established that in the process of polishing topography formation is initiated due to simultaneous surfacing of micro- and sub-micro-irregularities with equal probability and equal intensity. The obtained mechanism for topography formation is justified by the fact that break-down of gas-vapor shell takes place with equal probability as on the micro-profile top so in its cavities on the polished surface in the zones of accidental  non-homogeneity of electric field.

Welding is a crucial manufacturing process and widely used for manufacturing various products including ships, automobiles, trains and bridges. Welding distortions often occur in welded structures of thin plates due to relatively low stiffness and result in their warpage during assembly process and high manufacturing cost. Therefore, prediction and reduction of welding distortions are important in order to improve quality of welded structures. Welding distortion during the assembly process is caused not only by local shrinkage due to rapid heating and cooling. 3-D thermo-elastic-plastic finite element method (FEM) has been used to simulate single-bead-on-plate welding with 1 mm thickness. Experiments have been carried out to prove the simulated results. Comparison of the experimental results and FEM simulation results has confirmed that the proposed method efficiently  predicts level of  welding distortions while making single-bead-on-plate welding with 1 mm thickness.

The paper investigates influence of magnetic–electric grinding parameters on surface micro-relief formation. It has been established that while changing values of technological current and magnetic  density parameters, it is possible to control qualitative characteristics of a work-hardening coating.

 

The paper reveals how to obtain a parting coating with high sedimentation resistance. The parting coating is used for  oiling aluminum-alloy pressure-die casting moulds and obtained on the basis of high-molecular silicon polymers (polymethylsilicone fluid PMS300) with  addition of light vegetable oil soap stocks as an emulsion the weighing material and the stabilizing agent of an emulsion filling an stabilizing agent.

 

The paper considers an experimental evaluation of the influence of a plane periodic circular motion which is transferred to a blank on the intensity of its sawing and quality of its machined surface. Description of a modernized industrial sawing section has been given in the paper. The section is used for sawing various types of specimens (jasper, quartz glass, corundum) as under conventional machining conditions so while transferring them a circular motion along a closed path with a shape being like an ellipse. It has been established that in comparison with machining under conventional conditions transfer of such motion to a blank makes it possible significantly (by 2.5-3.9-fold) to improve sawing intensity and simultaneously to reduce Ra value of their sawed surfaces by 1.9-3.0-fold. The obtained results have allowed to make a qualitative description of a mechanism which reveals an influence of a blank circular motion on higher intensity of its sawing and quality of the machined surface.

The paper presents results of mathematical modelling of dynamic stability of flexible ultrasonic waveguides applied in engineering and medicine, particularly, in minimally-invasive surgery. By means of the Bubnov-Galerkin method an equation of parametric flexural vibrations of a waveguide is reduced to the Mathieu equation. Stability of the equation solutions is determined by values of its coefficients and may be represented graphically by means of the Ince-Strutt diagram. Parameters of the Mathieu equation determining the stability of its solution are determined by means of finite element method using ANSYS software and APDL programming language.

 

While taking an example of reconstruction and modernization of OJSC «Construction and Mounting Trust No.16, Novopolotsk» the paper substantiates solutions for complex production reconstruction. The production reconstruction is divided in three start-up facilities ensuring continuous finished-product output.

The paper investigates a dispersion separation process with due account of different factors: liquid phase concentration and its degree of dispersion, height of settling layer, concentration of surface-active substances in disperse medium, medium temperature. Water has been used as a disperse medium in the investigated dispersion system and toluol has been used as a liquid dispersion phase.

A sedimentometric analysis using the obtained dependences allows to determine the following main quantitative characteristics of the dispersion in every concrete case according to minimum number of experimental data: complete separation time, value of total and specific particle surface, polydispersity index, weighted-mean radius of particles and other characteristics

The paper presents solution of the problem pertaining to the action of surface normal loading on an elastic transversely isotropic base consisting of horizontal layers. The layers are considered as unbounded ones. The problem has been solved in 3D. A solution method has been on using of the Fourier transform. Analytical formulae for vertical displacements of the base surface have been obtained for the following cases: one layer on an elastic and absolutely rigid half-space. The paper contains examples of calculations.

The paper considers a microprocessor current directed protection of lines with adaptive elements and also presents investigations results of its technical modernization. An investigation of the technical modernization pertaining to the proposed protection has been executed while using computer program which is based on mathematical model of 10–35 kV distribution network with two power sources. The protection behaviour has been investigated not only at metallic short circuits but also at short circuits through transition resistance.

The investigations have revealed that solutions laid in the basis of the microprocessor current directed protection ensure higher indices of its technical modernization in comparison with the existing analog protection and also a selective action and correct operation in all operating modes of the protected line.

The paper considers possible provision of electric power to motorway service stations on the basis of comparison of a diesel power station and a wind power plant. Arguments in favour of wind power plants that prove an economic and technical efficiency of their application are given in the paper.

The paper proposes a simple approximate method for calculation of energy spectrum of  two-dimensional nanostructures on the basis of the X_a method and energy of valence electrons in the main and first excited state for Si₁₂ cluster. The calculations have proved that energy of the first optical transition is equal to 1,6 eV.

In order to improve position of the Republic of Belarus in the rating of the World Bank by a logistics index a problem pertaining to creation and development of complex logistics system which will allow to change radically the situation in the country’s market of services and to receive considerable foreign-currency resources in the Republic budget becomes rather actual one. Keeping in view this purpose it is necessary to raise efficiency of customs procedures, quality of transport infrastructure and information technologies, make international deliveries more accessible with due account of logistical environment development. The proposed measures must stimulate development of the national logistics system which permits quickly to develop transit transportations with minimum expenses

The paper considers conditions of market origin and its development as a special mode of economy based on commodity production and exchange. Specific features of the market economy as a type of economical system where money is a binding element of economic management entities have analyzed in the paper. The paper presents positive and negative market aspects that must be taken into account while selecting a strategic direction of society development.

The paper substantiates phases of specialists’ replacement ensuring innovation development of the national economy in Belarus, i.e. managers of innovation activity. Realization of replacement phases is presented within the system consisting of four blocks – objective, managing, controllable and providing. Analysis results of the current state of the innovation activity managers replacement system reveal main problems in interaction of its basic agents. The paper considers solution of specified problems in the context of formation of organizational and economic approaches to managing the innovation activity managers replacement system which presupposes modernization of organizational interrelations between state- run public authorities in the managing block and micro-incentive structures in the controllable block as well as the usage of the process approach in every phase of the replacement process.

 

The paper considers a problem of structural optimization of financial streams in the economic activities of the enterprises. The authors describe a general process of enterprise capital structure optimization while breaking it in stages and consider the most interesting financial stream theories. The paper presents for the first time «Combined optimization model». In order to develop the model the most commonly applied methods have been used, namely: an optimization  method on the basis of an average capital price, an optimization method on the basis of financial leverage effect and an optimization method on the basis of the average managing subject price. Alternative calculations of optimum structure of financial stream sources on the basis of the proposed «combined model» have been presented in corresponding tables. The authors also use for the first time such concepts as «a break-even point» and «a safety zone» in respect of enterprise financial streams while using a graphic method.

The paper considers main aspects pertaining to provision of energy security of thermal power stations. It has been shown that transition of electricity and heat generation to decentralized power supply circuit based on cogeneration plants favors to improvement of energy security.