Статьи журнала - Сибирский аэрокосмический журнал
Все статьи: 3183
Статья научная
A method of synthesizing a digital controller for a solar energy conversion channel in a power supply system of a spacecraft is presented. The method is based on the initial functional diagram of the pulse converter and the method of switching discontinuous functions. In accordance with the technique, which is formally presented in the form of eight consecutively executed items, a block diagram of the shunt converter has been developed in the basis of switching func- tions, which is taken as an example for testing the technique. The shunt converter is one of the three energy conversion channels in modern power supply systems of a spacecraft. The block diagram showed that all nonlinearity of the system can be reduced to nonlinearities of two multiplication links and nonlinearity of a pulse-width modulator. The possibility and acceptability of joint linearization of each of the specified nonlinear multipliers with a pulse-width modulator at the selected operating point is shown. A linearized block diagram of the control object was obtained, after which the trans- formation and simplification of the block diagram to a convenient form for calculation was carried out. Using the trans- fer functions of the linearized block diagram, the logarithmic frequency characteristics were calculated analytically and the results of their comparison with the frequency characteristics obtained experimentally on a simulation model, which confirmed their identity in the working frequency domain, were presented. At the same time, the specified simulation model of a shunt pulse converter, built in the Simulink package of the Matlab design environment, took into account all the mentioned nonlinearities of the real converter. According to the obtained logarithmic characteristics, a classical synthesis of the analogue prototype correcting section was produced. The transition from the analog correcting section of the prototype to the implementation of the digital correcting section is shown. Simulation modeling of a closed-loop power supply system with a synthesized analog controller, in its mode of operation from a solar battery, confirmed the correctness of the methodology and the achievement of the goals. The results of the work are intended to create a new onboard energy conversion equipment for power supply systems of high-potential spacecrafts. The scope of application of the project results is space instrumentation.
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The method of the disk friction determining of low mass flow centrifugal pumps
Статья научная
Low mass flow centrifugal pumps are currently widely used in the energy supply system of liquid rocket engines, the engines of correction, docks, consisting of on-Board power sources on-Board sources power supply system of fuel components in the in gas generator systems for inflating fuel tanks, and in temperature control systems of aircraft and spacecraft. When designing low mass flow centrifugal pumps for aerospace purposes, methods for calculating and optimizing the flow rate are often used corresponding to the design methods of full-size centrifugal pumps, which limits the mode and design potential of pumps and affects their energy characteristics and reliability. Reliability requirements often lead to the need to reserve units and fuel-supply systems. Despite the large amount of research works, the issues of reliable design of low mass flow centrifugal pumps with high energy and operational parameters for spacecraft and aircraft remains an urgent task. The article analyses the operational parameters of low mass flow centrifugal pumps used in aircraft and spacecraft power systems. Taking into account working fluid used and the temperature range, it was found that a laminar rotational flow with Reynolds number characteristic Re = 103 ¸ 3×105 is realized in the lateral cavity between the impeller and the pump housing. The determination of power losses on disk friction of the impeller technique is developed taking into account design features and the applied schemes. Equations for determining the disk friction coefficients are consistent with the dependencies obtained by other authors. The obtained equations for the laminar rotational flow made it possible to determine the dependences for the resistance moment and the disk friction power of the impeller determining of a low mass flow centrifugal pump.
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The methods of modelling and the efficiency factors in investment projects
Статья научная
In this research we have classified the methods of investment project modeling, made a comparative analysis of the given methods, and studied their advantages, disadvantages, and the directions of application. The efficiency factors of the investment project are displayed, based on the developed of enterprise net profit algorithm calculation.
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The model of the corporation risk-oriented financial strategy under the crisis conditions
Статья научная
The decomposition model of the corporation financial strategies development and selection of the risk-oriented strategy in respect to the financial risks criteria is represented. The definition concept of the risk-oriented financial strategy is given.
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The modeling of the world socio-economic strategy as an optimal control problem
Статья научная
An approach to the modeling strategy of global social-economical development on the basis of the economic-mathematical optimum control model, considering interaction of the basic economic agents of the world social-economic system (WSES) - industrial, consumer, financial sectors, as well as the operating center (the world government) is described in this article. The task of optimizing the global social-economic development is formulated; the main principles of the analysis, restrictions and target criteria are analyzed.
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Статья научная
The invariant system of information processing based on obtaining of the rectangular envelope by using a synchronous detector is considered. The indexes of the noise immunity of such system are calculated. It is supposed that the closest readings of the rectangular envelope are interfered with the additive noise whose readings are weakly correlated with each other. The quantitative estimation of the operation of such system is compared with the quantitative indexes of the known invariant system under non-correlativity of the noise readings.
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Статья научная
An algorithm of right-hand side and Jacobian formation of differential equations of chemical kinetics is described. Numerical simulation of the cesium cycle in the upper atmosphere is conducted by means of the L-stable method of the second order of accuracy with the control accuracy. The results of the computation are presented.
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Статья научная
The dynamics of personal services market development in the Krasnoyarsk Region is notable for lagging behind those of all-Russian ones. Besides, there is a lower growth rate of the personal services volume in 2008. Having sufficiently large potential, the market of personal services can be attractive to average and small-scale businesses. The share of personal services in total amount of paid services testifies to it in 2002. The decision of business and state regulation in the branch of personal services should be based on applied scientific research of the market taking into account current trends, in particular the market fragmentation.
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The possibilities for optimizing the functional system structure of civil aviation aircraft
Статья научная
This is an analysis of the traditional approach to systems with individual reserving reliability calculation usage. An alternative calculation method for these systems with an individual reserve system has been developed. Its application is demonstrated.
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Статья научная
The manufacture of parts and assembly units of the aerospace industry is characterized by a small product range, but a significant changeability of their shape and size. In these circumstances, the use of the elements of universal as- sembly devices (UAD) allows to reduce the number of special devices significantly. Based on the results of a complex research on the analysis of design and manufacturing technology of elements of UAD, and on the known principles of construction of group technologies the algorithm for the formation of technological groups of UAD details of the ”prism support” type was developed. The 3D-model of the complex details, the classification of surfaces proposed for it and the database on all 16 details of the group are the basis for the development of an algorithm for a route group technological process (GTP). In the new GTP and control program it is proposed to combine in one operation practi- cally all draft types of processing: milling, drilling, thread cutting on the multi-task machine with the palletization of complex details on a technological plate. The effectiveness of the constructive-technological decisions is confirmed by the reduction in the number of operations and equipment (from 7 to 4 machines) thus reducing the labor content and cost. The use of the developed techniques of development the GTP allows significant expansion of the possibilities for automation of technological preparation of production, simplifies the development of control programs, reduces the labor content of the preparation of technological documents and its translation into digital form.
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Статья научная
A generalized analysis of a high frequency key generator is conducted. This analysis allows the power indicators estimation of the generator in a wide frequency range, and in scheme parameters.
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The process of nanomodifying cast aluminum alloy ingots for components of aerospace vehicles
Статья научная
Currently, increasing attention has been paid to such a class of materials as nanopowders (NP) of chemical compounds, which are ultra-thin formations of not more than 100 nm in size. Such attitude to these materials is explained by the fact that they have unique physical, chemical and mechanical properties significantly different from the properties of materials of the same chemical composition in a massive state, and these properties can be transferred to some extent from them or with their participation to the products. The existing methods of introducing NP into metal melts could not be used due to their special properties in comparison with coarse powders, and therefore a new method of their introduction into the melt was developed, excluding direct contact of NP particles with oxygen and unhindered penetration of particles into the melt through the oxide layer. The essence of the method was as follows. In the aluminum container filled up with aluminum particles or deformable aluminum alloys D1 or D16 and various NP (nitrides, carbides, oxides, etc.), and this composition was pressed into the rod, with its help NP was introduced into the melt during casting of aluminum ingots and deformable aluminum alloys. The results of the study showed that this excludes the appearance of cracks in the ingots, as well as improves their technological and mechanical properties.
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Статья научная
In this article we have considered the possibilities of realizing diversity reception algorithms in hybrid fibers of wireless information transfer. At the heart of diverse reception algorithms lies the fact that when solving problems of optimal field processing, their correlation curves are definite for the description of the Gauss and any kind of stochastic fields.
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The research of Raman spectra in CoxMn1-x solid solutions
Статья научная
Temperature dependence of Raman spectra in the frequency interval 100... 1 200 cm1 in the 100...300 K range temperature has been investigated in the substance of CoxMn1-xS solid solutions. A Raman spectra study has uncovered evidence of strong orbital fluctuations that manifest itself in kind of composite line shape at ω2 273...298 cm-1, arisen from splitting of phonon modes with different temperature dependences of the intensity below the orbital ordering transition.
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Статья научная
Today, protective coatings are applied to almost all parts and components of engineering products in order to ensure high performance properties of machines, with the lowest economic cost. The method of plasma spraying allows to apply heat-resistant coatings on a different kind of basis, in addition to a wide variety of materials. Therefore, rocket and space engineering is primarily interested in the method. In modern conditions of high rate of mechanical engineering development engineers must develop and put into operation products within the shortest possible period of time. As a rule, engineers select the modes of plasma spraying using the method of selecting the empirical relationship between the properties of the coatings and the values of the specified parameters of plasma spraying, which suggests conducting a huge number of experiments. That is why we see the need to find new methods for selecting the plasma spraying parameters, which are based on mathematical and analytical apparatus. We set the task to study and show the applicability and prospects of the proposed method. In the work we carried out the operations of spraying nichrome coating, at different values of the arc current. We studied the adhesive strength of the coatings obtained and their microstructure. We showed the relationship between the arc current and the adhesion of the coatings using their microstructure. These studies have made it possible to exclude a large number of experiments, which usually establish an empirical relationship between the values of the input parameters of the deposition process and the values of the characteristics of the coatings obtained. In the future, we assume that the database of such relationships will make it possible to fully use this method in engineering industries.
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Статья научная
The most important resource for improving the performance of parts is the reduction of the surface roughness. One of the promising ways to reduce the surface roughness is the abrasive extrusion processing. When developing the AEP technology, it is necessary to know the flow rate (pressure) of the WE, which depends on the viscosity of the latter. In turn, the viscosity of the WE is determined by its temperature. The temperature of the working environment at AEP can be calculated if the coefficients of thermal conductivity and thermal diffusivity of the WE are known. The working environment for AEP consists of two components, therefore, the coefficient of thermal conductivity can be calculated by known formulas. However, the calculation error is significant, therefore, the experimental determination of the abovementioned coefficients is required. The installations for the coefficients research have been presented, the methods of conducting experiments have been developed. After mathematical processing of the experiments results by means of the AdvanceGrapher v. 2.11, the dependences of the thermal conductivity and thermal diffusivity on the abrasive concentration have been obtained. The studies of the thermophysical properties of the working environment have shown that the values of thermal conductivity and thermal diffusivity of the WE are mainly determined by the concentration of abrasive grains in the working environment. The direct dependence of these coefficients on the degree of filling the working environment with abrasive grains has been established.
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The study of the engine-flywheel housing made by additive technology
Статья научная
The first commercial equipment for additive technology production with 3D-printing was made more than 30 years ago. In the mid 90-ies 3D-printing was used mainly in research activities. The wide spread of digital technology in the field of design, modeling, calculations and machining stimulated a rapid development of additive technology. To evaluate the application of the parts printed on a 3D-printer, there was conducted a research of the design of the reaction wheels engines. On the basis of the pre-designed 3D-model there were made two housings of powder materials - alloys АК9Ч and AlSi10Mg were constructed. The analysis of the stability of the geometry of the engine housings to thermal effects, susceptibility to mechanical loads in the model layout of the engine-flywheel was conducted. Outgassing in vacuum was defined and the microstructure of additively manufactured materials was researched. Test results proved the possibility of application of the additively manufactured housing made of selected alloys with sufficient mechanical strength in the composition of the engine-flywheel. There is obviously a need to continue the studies on the properties of materials used in additive technologies in order to compile a list of materials with their properties and application characteristics in the design of the engine- flywheel.
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The study of the flow in the vapour channel of short linear heat pipes
Статья научная
E-mail: seryakovav@yandex.ru The results of studies of flow of moist vapour in Laval-like vapour channels of short linear heat pipes (HPs) are pre- sented. The increase in heat transfer coefficient of short linear HPs, intended for creation of the cooling systems of heat-stressed designs of spacecraft, is carried out by making the HPs vapour channel forms similar to the shape of the Laval-like nozzle. Comparison of the heat transfer coefficients of short HPs with the standard cylindrical vapour channel and the channel, made in the form of the Laval-like nozzle with the equality of all dimensions, flat evaporator and the same amount of the working fluid, shows that the HPs with the vapour channel in the form of the Laval-like nozzle exceeds the heat transfer characteristics of the standard HPs with a cylindrical vapour channel under high ther- mal loads. The study of the flow and condensation in such shaped vapour channels of the short HPs at high thermal loads gives an opportunity to analyze in detail the advantages of using such HPs and make the conclusion about the necessity of wide introduction of such HPs for the cooling systems of the spacecraft. Capacitive sensors were addition- ally installed in cooled top covers of the HPs, and electromagnetic pulses with a frequency of 100 kHz were supplied to them from the external generator. At heating the HPs evaporator, starting from a certain thermal power threshold value, electromagnetic pulses became modulated. It is related to the formations of the boiling process in the capillary- porous evaporator and large amount of vapour over it and its discontinuous distribution. It was discovered that the frequencies of the pulsations are more and they occur at lower values of heat load at the evaporator in the HPs with a vapour channel of a Laval-like nozzle, compared to the HPs with the standard cylindrical vapour channel with equal overall dimensions.
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The system of management of personnel’s innovative potential at a high technology enterprise
Статья научная
Formation of a new economic space and increasing globalization provides new challenges and prospects for organizations, which are based on innovation. In the innovative economy competitiveness of enterprises is greatly influenced by the development of scientific knowledge and new technologies, both in production and in the field of management. Thus, a problem of work with innovation, creation and development of a well-functioning innovative environment and the mechanism of its maintenance arises. The solution of this problem mainly depends on the human factor, in particular, personnel’s innovative potential. Today management should focus on a person and his or her innovative potential as a main source of innovation and factors that contribute to a high level of innovative activity of enterprises. The paper analyzes the features of labour at high-technology enterprises, two categories of employees are distinguished, that is employees involved in direct production and employees involved in innovative activity. On the basis of these, we propose the system of management of personnel’s innovative potential, consisting of the following elements: objectives, tasks, functions, subjects of management, organizational forms, means, methods, techniques, motivation, assessment, development. The obtained results of the study are aimed at solving the strategic and tactical problems in the implementation of the strategy of innovative development of a high-technology enterprise with the help of the formation of an effective system of management of personnel’s innovative potential at an enterprise.
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The system of software-driven verification of network IP-cores in a reference system-on-chip
Статья научная
The article presents the application of network Intellectual Property cores (IP cores) software-driven verification method for network infrastructure devices in the system-on-chip microprocessor (SoC) used as verification environ- ment. The SoC used for verification is a reference system since it consists of previously fully verified and approved IP cores which interact in this system correctly and accurately. Software of a reference system generates test inputs and processes responses to them which are received from a verified device. Conclusions of executed or unexecuted tests are generated on the basis of the expected results. A set of expected results of input action is a reference model of a verified IP core. General architecture of a verification system of a network device IP core has a form of a classic test loop. The vari- ants of verification architecture given depend on the type of a verified network device: an individual network codec, a network protocol controller or a network switch. The presented architectures show the simplicity of software-driven verification. The test environment naturally results from the reference SoC model and test software developed in such high-level programming language as C/C++. When the software-driven verification of an IP core takes place in reference SoC environment, the test software con- sists of two types of tests: directed tests and restricted-random tests. Successive use of both the given types of tests and typical scenarios of network devices interaction which include request-reply packages transmission between network nodes provides high coverage of a verified IP core with test situations. To check fault tolerance function it is supposed to use the scenarios of network devices interaction in conditions of possible faults made by predetermined introducing of errors into packages transmitted over the network connections. Program tests which are developed and proved during the IP core model verification are completely ready to be used in hardware SoC prototype including the given IP core in the programmable logic device. The presented approach to functional verification was used for IP cores testing in SpaceWire network infrastruc- ture: a fault tolerance codec, a RMAP protocol controller and a routing switch.
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