The paper describes a functional scheme of a machine-tool for simultaneous abrasive machining of lenses with shallow high-accuracy executive surface. The machine-tools permits flexibly and within long range to control shape-formation process through changing such adjustment parameters as tool and rough workpiece frequency rotation, amplitude value of tool oscillatory motion, their diameters and number of double strokes per minute. While using the given machine-tool for machining process an operating force is directed along normal to the working surface and due to this there is a possibility to accelerate a shape-formation process of optical parts that leads to reduction of local errors on their executive surfaces. The paper considers a structure of the executive machine-tool mechanism which transfers translational motion to the tools and consists of rotational and rectilinear kinematic pairs forming a four-bar linkage and its crank is a guide link. A turning angle of the link is selected as a generalized coordinate of the executive mechanism. A relationship between the generalized coordinates and link positions of the executive machine-tool mechanism has been established in the paper and it permits to obtain analytical dependence between motions of input and output mechanism links with due account of its kinematic transfer function which represents in itself a ratio of angular output link speed to an angular velocity of the input link. An analysis of geometric parameters for backward-rotational motion of the top link in the proposed machine-tool has made it possible to obtain an expression to calculate a rod length of the executive mechanism which ensures symmetrical center position of the above-mentioned link relative to a symmetry axis of the bottom link. As an amplitude value of oscillatory motion for an out-put link in the executive mechanism is regulated in the machine-tool for two-sided lens machining while changing length of its input link (crank) an analytical relationship has been established between these geometric parameters and the rela- tionship provides a possibility purposefully to change a machining intensity in the central or edge zone of a part according to technological blank heredity in the context of allowance which is to be removed and which is distributed along its surface. 

A turning method with asymmetric oscillations of cutting tool has been proposed on the basis of the analysis of various methods for chip crushing in the process of structural steel lathe turning and the method makes it possible to ensure a stable crushing of discharge chips and to reduce roughness of the machined surfaces. Asymmetric vibrations are characte- rized by an asymmetry coefficient of the oscillation cycle, their frequency and amplitude and they are additionally transferred to the tool during the turning process. Kinematics of structural steel turning with imposition of directed asymmetric cutting tool oscillations created by a cam system on traditional cutting scheme has been considered in the paper. An equation of tool motion with asymmetric oscillations has been obtained on the basis of Fourier Series. An influence of the oscillatory tool motion amplitude and frequency on the process of discharge chip crushing has been determined in the paper. In order to re-duce a negative influence of the oscillation amplitude on the cutting process and quality of machined surfaces machining must be carried out with its minimum value. In this case it is necessary to ensure an optimum ratio of the tool oscillation frequency to the rotational speed of a workpiece. A formula has been derived for determination of this ratio according to a coefficient of oscillation cycle asymmetry and number of complete oscillation cycles per one revolution of the workpiece. It has been established that a theoretical value of the minimum tool oscillation amplitude is equal to half of the tool feed value per one revolution of the workpiece. If the optimum ratio of the tool oscillation frequency to workpiece rotation frequency has not been observed for chip crushing it is necessary to increase oscillation amplitude that may lead to an increase of roughness on machined surfaces. 

Over the past few decades reduction in pollutant emissions has become one of the main directions for further deve- lopment of engine technology. Solution of such problems has led to implementation of catalytic post-treatment systems, new technologies of fuel injection, technology for regulated phases of gas distribution, regulated turbocharger system and, lately, even system for variable compression ratio of engine. Usage of gaseous fuel, in particular gas-diesel process, may be one of the means to reduce air pollution caused by toxic substances and meet growing environmental standards and regulations. In this regard, an analysis of methods for organization of working process for a gas-diesel engine has been conducted in the paper. The paper describes parameters that influence on the nature of gas diesel process, it contains graphics of specific total heat consumption according to ignition portion of diesel fuel and dependence of gas-diesel indices on advance angle for igni-tion portion injection of the diesel fuel. A modern fuel system of gas-diesel engine ГД-243 has been demonstrated in the pa- per. The gas-diesel engine has better environmental characteristics than engines running on diesel fuel or gasoline. According to the European Natural & bio Gas Vehicle Association a significant reduction in emissions is reached at a 50%-substitution level of diesel fuel by gas fuel (methane) and in such a case there is a tendency towards even significant emission decrease. In order to ensure widespread application of gaseous fuel as fuel for gas-diesel process it is necessary to develop a new wor- king process, to improve fuel equipment, to enhance injection strategy and fuel supply control. A method for organization of working process for multi-fuel engine has been proposed on the basis of the performed analysis. An application has been submitted for a patent.

Electrolyte-plasma treatment has become widespread in the industry as an alternative to traditional chemical, electrochemical and mechanical methods of improving the surface quality of products made of metallic materials. Advantages of

electrolyte-plasma treatment are a high intensity of microroughness smoothing, the use of low concentration salts solutions as electrolytes, the possibility of processing products of complex shape. The main disadvantage of this method is high power consumption, so the method can be considered in its classical form to the power-consuming. A possible way of reducing power consumption is treatment in unsteady modes that arise in the transition zone between a switching and stable electrolyte-plasma treatment process and is characterized by the periodic formation of a stable vapor-gas shell and a transition to an electrochemical process. The paper presents the results of a study of the influence of a high-gradient electric field under unsteady electrolyte-plasma treatment modes on the energy parameters of the process and the characteristics of the surface being treated. It is established that a high-gradient electric field has a significant effect on the decrease in specific power consumption, which is explained by a decrease in losses in the electrolyte and the influence of the field on the formation and maintenance of the vapor-gas shell. As a result of the study of the effect of a high-gradient electric field in unsteady EPT modes on characteristics of the surface layer was established that a significant impulse current density in the zone of predominantly electrochemical treatment leads to a selective etching of the surface and the formation of a characteristic micro relief of the surface with a developed porous microstructure with pore sizes from 0.3 to 2.5 microns. The most pronounced porous microstructure is provided at a voltage of 270–300 V and an additional inductance of 3.2 mH.

Titanium nickelide (nitinol) is one of prospective materials for production of special endo-prostheses and other parts and characterized with effect of shape memory. A specific feature of vascular endo-prostheses is the necessity to provide the required rigidity within the temperature interval from 15 to 42 оС. It has been established that titanium nickelide is able to provide the required rigidity but it depends on preliminary heat treatment parameters. So, it is important to determine rela-tions between rigidity of titanium nickelide wire and its preliminary heat treatment parameters for the given temperature in-terval. The aim of the work is to create devices that allow to estimate radial and flexural rigidity of elements made of flexible nitinol wire for manufacturing various medical products, including endo-prostheses of vessels – stents and stent grafts, filter traps. Laboratory digital scales and a specially developed dynamometer based on a cylindrical slotted spring and inductive displacement transducer have been used for measuring a load. The paper proposes possible variants of device designs used to monitor radial rigidity of blood vessel endo-prostheses, as well as to control flexural rigidity of endo-prosthesis elements and wire for their manufacture. The developed devices allow us to evaluate mechanical characteristics of samples under the desired temperature conditions. An introduction of the developed devices has permitted to carry out an operative control on radial and flexural stiffness of intravascular endo-prostheses elements both under conditions of research investigations and during technological process of their manufacture. Currently, the devices are used to specify heat treatment regimes for nitin-ol wire from various manufacturers while manufacturing vascular endo-prostheses. 

Mirror systems make it possible to reduce device dimensions and its weight while preserving high input aperture and these systems are characterized by a number of other advantages. Their significant disadvantage is a central screening of an entrance pupil that leads to lower image quality. The paper contains description of the investigations on afocal systems formed by eccentrically cut-out mirror paraboloids (off-axis mirrors) where aperture diaphragm is displaced in the meridian plane for a defined value and a central field point is located on the optical axis. The canonic Mersenne systems are accepted as base schemas (modules) for these compositions. The paper considers two types of such systems: visible increases – Г > 0 and Г < 0. Algorithms for calculation of centered afocal systems with two and four reflections have been written in the paper and the systems are free from spherical aberration, coma, astigmatism when an input pupil is located in superimposed focal planes of all parabolic mirrors. An aberration in curvature image has been additionally corrected in three-mirror quart-parabolic scheme which is a combination of two classical telescopic Mersenne systems. The paper presents schemes and calculation results. Two-mirror schemes with non-screened input pupil have been studied in the paper and in this case all the system remains centered and an aperture diaphragm is decentered for the distance Cm which is commensurable with the diaphragm size. The paper contains description of the investigated afocal schemes with four reflections from off-axis mirror paraboloids, a prepared algorithm for calculation, the obtained formulas for making combination of canonic afocal systems formed by two mirrors. Computer simulation in software environment Opal and Zemax has been carried out in the paper. Basic description has been prepared while using two alternative methods for the class of decentered systems and aberration characteristics and schematic solutions for telescopic systems without screening with two and four reflections have been ob-tained in the paper. Two-mirror afocal systems with low-powered magnification are of some interest for practical application as accessories for registering object lenses. 

The quality of services which are offered by urban passenger transport determines a living standard of country’s inhabitants. The executed analysis of methods for quality assessment of passenger transportation service by urban transport has shown that it is expedient to use complex indices for such assessment. The existing methods for quality assessment of urban passenger transport do not fully take into account subjective passengers’ evaluation of service quality criteria. The investigations conducted with the purpose to estimate significance of quality assessment criteria pertaining to urban pas-senger transport operation for passengers have made it possible to formalize importance of the given significance. A complex index of urban passenger transport quality has been prepared that includes such isolated quality indicators as pedestrian mo-tion component, waiting time, travel time, dynamic factor of capacity usage. It has been determined that it is possible to plan quality of passenger transportation while using transport process simulation. Influence of technological parameters on quality parameters can be determined with the help of the developed simulation model for quality assessment of transportation pro-cess on route of urban passenger transport. While using the simulation model regularities in changing a complex quality index of urban passenger transport have been analyzed according to number of transport facilities operating on route. Simulation results have shown that changes in number of transport facilities significantly exert an influence on the value of dynamic fac-tor of transport facility capacity usage, waiting time for transport facility and time travel. This leads to changes in quality of transportation process. Analysis of the obtained results has permitted to make a conclusion that every route with certain parameters has such rational number of transport facilities that ensures maximum efficiency of urban passenger transport with appropriate quality. It has been revealed that any change in number of transport facilities is described with a reasonable degree of accuracy by a nonlinear regression equation where parameters of transport facilities, passenger traffic flows and route are used as independent variables. 

The paper contains results of investigations pertaining to an influence of plasma jet parameters (current, spraying distance, consumption of plasma formation gas (nitrogen)), fractional composition of initial powder and degree of cooling with compressed air on anti-meteoric coating characteristics. Optimum modes (arc current 600 A; spray distance of 110 mm; consumption of plasma formation gas (nitrogen) – 50 l/min; fractional composition of zirconium dioxide powder <50 μm; compressed air consumption for cooling – 1 m³/min; p = 4 bar) make it possible to obtain anti-meteoric coatings based on zirconium dioxide with material utilization rate of 62 %, total ceramic layer porosity of 6 %. After exposure of compression plasma flows on a coating in the nitrogen atmosphere a cubic modification of zirconium oxide is considered as the main phase being present in the coating. The lattice parameter of cubic zirconium oxide modification is equal to 0.5174 nm. Taking into consideration usage of nitrogen as plasma formation substance its interaction with zirconium coating atoms occurs and zirconium nitride (ZrN) is formed with a cubic crystal lattice (lattice parameter 0.4580 nm). Melting of pre-surface layer takes place and a depth of the melted layer is about 8 μm according to the results of a scanning electron microscopy. Pre-surface layer being crystallized after exposure to compression plasma flows is characterized by a homogeneous distribution of ele-ments and absence of pores formed in the process of coating formation. The coating structure is represented by a set of lar- ge (5–7 μm) and small (1–2 μm) zirconium oxide particles sintered against each other. Melting of coating surface layer and speed crystallization occur after the impact of compression plasma flows on the formed coating. Cracking of the surface layer arises due to origination of internal mechanical stresses in the crystallized part. While using a scanning electron microscopy a detailed analysis of the surface structure has permitted to reveal a formation of a cellular structure with an average cell size of less than 1 μm in the crystallized portion and formation of the cells can be caused by speed crystallization of the melted layer.

Application of waste liquor at a rate of 25% that contains the used quinone and is applied as an additive has shown that qualitative characteristics of the obtained desired product do not differ from a product while using fresh quinone for pulping of cellulose-containing vegetable raw material. For this reason process of obtaining the desired product (cellulose or semicellulose) becomes economically cost-efficient on the basis of calculation and with due account of ecology. While analyzing investigation results pertaining to production of wood pulp from vegetable raw material (sprucewood) it is possible to point out the fact that qualitative characteristics of the desired product have been improved due to addition of quinone in the process of alkaline wood pulping (sulphate and sodic). A number of research publications have described a positive influence of additives on alkaline delignification of vegetable raw material. It subsequently improves the quality of the desired product: reduction of lignin content in the product; an output increase in cellulose and hemicellulose, α-cellulose in cellulose; upgrading of physical and mechanical indices. All the above-mentioned elements and components contribute to better quality of the manufactured packing products. In this case formation of hazardous sulfur-containing compounds is fully excluded.

he paper considers a possibility to apply gravity models for calculation of intercity passenger transport corres- pondences which are implemented with the help of public transport. The Ukraine transportation system has been selected as an object of investigation and this approach extends application possibilities of the obtained results. Calibration coefficients used in calculation of the indicated correspondences are rather important and significant in case of forecasting passenger transport correspondences. Formalization of these factors is necessary for every transportation system if a calculation of pas-senger transport correspondences has been made for it. In this case searching for actual calibration parameters and other coef-ficients as components of gravitational models is a relevant objective of the given paper. Selection of the gravity model va- riant plays rather significant role in solution of this problem. The developed methods for calculation of passenger transport correspondences are proposed for their application in respect of various transport and trip types. The executed research works have made it possible to investigate a process pertaining to providing of services for passenger transportation while using public routes. The obtained characteristics on functioning of the studied system have allowed to assess the possibility for ap-plication of the known methods for calculation of passenger correspondences and analyze the quality of their application. Calibration coefficients have been empirically selected for calculation of the indicated correspondences while using method of gravity modeling. Formalization of previously unexplored parameters of gravity model component provides the possibility to apply the considered approach for calculation of passenger correspondences within the framework of the investigated trans-portion system. This makes it possible to plan and arrange interaction of various transport types and provides new data and knowledge on the studied system.

The paper considers a method for evaluation of transport flow parameters and determine an efficiency of variants concerning organization of traffic movement and provision of qualitative transportation. A method for evaluation of main traffic flow parameters while using a two-fluid mathematical model of Herman – Prigogine has been developed and it is based on passive processing of navigation data for road transport facilities on highways and urban road and street networks. The main advantages and novelty of the method (in contrast with the traditional usage of a mathematical model of Her- man – Prigogine on the basis of active processing of navigation data) are the following: a passive treatment of GPS-tracks and support of their formats that make it possible significantly improve quality and adequacy of the model results; cloud com-puting (usage of cloud storage for storing large bulk of data); presence of client mobile application for Android operating system which is used for data collection in addition to operation with already collected navigation data from navigation and information center and other sources; application for calculation and processing of modern web technologies; scalability and configurability of the system. Efficiency of the proposed algorithms, mathematical models for evaluation of transport flow parameters and system as a whole have been proved in the process of their approbation while using a set of tracks on main highways of Belarus