The technique of determination of local atomic structure in the vicinity of absorbing atom in the case of the presence of strong correlation between fitting parameters is proposed. This technique is applied to three test signals simulating the Pt L3-edge EXAFS spectra of Pt/Ag bimetallic nanoparticles. The test results demonstrates the improvements in precision of determined parameters comparing with common technique.
Keywords: Extented X-ray Absorbtion Fine Structure, EXAFS, multiparameter curve fitting, correlation between fitting parameters, bimetallic nanoparticles, local atomic structures, CUDA
The article deals with the optimization of the process of disintegration of rock jaw crusher. The mathematical model that minimizes the costs of the process of crushing the rock.
Keywords: disintegration of rock, mathematical models, optimization
From the point of view of development of control systems, a significant disadvantage of indirect adaptive control systems of moving objects is the fact that the limiting the properties of such system are determined by the basic adaptive regulator. In other words, to solve the problem of adaptive control it is required to find a non-adaptive regulator, which solves the problem of marine autonomous vehicles. In this case, the adaptive controller replaces many controllers that solve the control of multiple objects in a non-adaptive domain. The paper presents method of direct adaptive control for marine autonomous vehicles. Nonlinear mathematical models are considered. The method is based on position-trajectory control approach. It is proved the designed by suggested method controller is a vector nonlinear PI-regulator. The regulator ensures asymptotical stability of the closed-loop control system.
Keywords: adaptive control, marine autonomous vehicles, position, trajectory
In this article is reviewed the nature of organic hybrid nanocomposites. Promising directions in the field of organic hybrid nanocomposite materials will be methods for the synthesis of multicomponent materials, as well as the type of "net net" and "host-guest". The fundamental problem with the chemistry and physics of nanocomposites is dependent "structure-property". Solving this problem will move from research materials to their purposeful design.
Keywords: nanocomposite sol-gel technology, synthesis, nanoparticles.
In this paper a modification of logic element DC LUT FPGA is proposed for the purpose of the acceleration of diagnostics. Simulation of proposed modification was performed in the system NI Multisim 10 by National Instruments Electronics Workbench Group. Evaluation of hardware costs is also given.
Keywords: logic element, DC LUT, FPGA, diagnosis, reliability
The basic virtue of the sowing apparatus of an overpressure is possibility of conducting of sowing on the big speeds and with high uniformity of dispensing of seeds. But the processes occurring in the sowing apparatus of an overpressure at dispensing of seeds, are insufficiently studied. In the article one of stages of process of dispensing by the overpressure sowing apparatus - transportation of a unit seed by dosing elements of a seed disc is observed. The forces acting on a seed in the course of transportation with a dosing element of a seed disc are defined. The gravity, centrifugal force, force of air drag and pressure force of air refers to to them. The scheme of forces is presented. As a consequence of theoretical research dependence of magnitude of an overpressure in the seed vessel from key parameters of work of the sowing apparatus of an overpressure has been defined. Graphs of theoretical dependence of pressure in the seed vessel from diameter of holes and a seed disc angle of rotation are built. The analysis of the gained results allows to draw following conclusions. The increase in diameter of holes of dosing elements of a seed disc leads to considerable decrease of the pressure necessary for transportation of a seed. At increase in an angular velocity of a seed disc pressure necessary for the secured transportation of a seed is augmented. The increase in an angle of rotation of a seed disc puts insignificant agency on pressure in the apparatus seed vessel.
Keywords: seeds, transportation, dispensing, forces, an overpressure, a dosing element, a nominal diameter, dependence.
In the article results of theoretical researches of the rotor scatterer of fertilizers are resulted. For elimination of adverse conditions shock interactings of particles of fertilizers with rotor vanes, possibility of application of curvilinear vanes is observed. The forces acting on a particle which moves on a curvilinear vane are justified. Schemes of act of forces and the scheme of interacting of particles of fertilizers with a curvilinear vane taking into account width of a torrent are presented. The transcendental equation numerical solution on a method the Runge-Kutty is resulted. The analysis of dependences of the kinematic operating modes of the scattering apparatus from design parametres of a curvilinear vane is carried out. The time of interacting of a particle of fertilizer with a surface of a vane taking into account its curvature and a slope is defined. Conclusions are drawn on possibility of lowering of crushing of particles of fertilizers at the expense of blow decrease in a normal direction.
Keywords: fertilizer, vane, rotor, curvature, angle of slope, speed, crushing
Nonstoichiometric tungsten oxides WO3–x and oxide alkaline tungsten bronzes have been studied because of their potential applications in electrochromic devices such as solar panel arrays and “smart windows”. Different phases of
WO3–x have been considered. In this part we present results of our research which clearly show that all Magneli phases of tungsten oxides WOx (namely W40O118, W20O58, W5O14, W18O49, W8O23, W3O8) and oxide tungsten bronzes MxMyWO3 at M-Li, Na, K, Rb, Cs. They are characterized by metal – like properties. Their band structures display an energy gap in the valence band just below the Fermi level.
We present results of our electrochemical synthesis of tungsten oxide bronzes in ionic melts of the polytungsten salts. Among the new state – of – the art methods for their manufacture, electrochemical synthesis in ionic melts, which makes considerably better use of existing technologies, is highly productive, based on the discharge of oxyanions of the polytungstates.
Keywords: oxide alkali bronzes, alkaline tungsten bronzes, tungsten, molybdenum, nonstoichiometry, tungsten oxides, electroconductivity, electrochromism
The properties of the water-soluble high-modulus silicate systems: based on alkali metal polysilicates called liquid glass and chain their transformation from lower to higher oligomers, with the subsequent formation of colloidal solutions - silica sol. The methods of preparation, properties and applications of water-soluble high-modulus silicate systems. The possibilities of their use as a binder and modifying agents for various nanostructured composite materials. The examples of promising areas of application of liquid glass and high modulus of aqueous solutions of silicates in construction and industry. In particular show the possibility of using liquid glass and aqueous solutions of silicates in the production of nanostructured silicate polymer. In space engineering for manufacturing water-destructed mandrels used in the manufacture of solid rocket motor casings and pressure vessels 'cocoon' of composite materials by winding. The application of the inorganic sol to obtain a nanocomposite ceramics and monolithic blocks of silicon oxide, which can be used in various fields of modern technology. The possibility of using silica sol as a binder for refractory ultra-lightweight shielding materials used to protect equipment from high impacts. The directions of development of the production of new acid-resistant materials and linings for protection of chemical equipment, parts and components operating in corrosive environments.
Keywords: Keywords: water glass, silicate polymer concrete, additives, silicates organic bases tetrafurfuriloksisilan, furfural alcohol, nanostructure composite materials, water-soluble silicates, silica sol, sol-gel transition, cured xerogel water-destructed mandr
In the article obtaining of cathodic coating MnO2 on condenser porous tantalum anode was researched. It was ascertained that formation of crystalline defects from hydrated MnO2 on MnO2 coating obtaining by known technology is possible. Such formations disturb tantalum capacitor cathode integrity. To determine the reasons of the crystal defects formation conveyed simultaneous thermal analysis of Mn(NO3)2x4H2O and Mn(NO3)2x6H2O with an analysis of the flue gases by FTIR spectroscopy. Based on the analysis results a mechanism of manganese nitrate thermolysis was suggested and the cause of the crystal defects on the surface after the coating of manganese dioxide removed from the furnace was ascertained. It was established that the thermolysis process is followed by the formation of such manganese nitrate intermediates as manganese hydroxynitrate, manganese oxyhydroxide and its further oxidation to manganese dioxide. Because of secondary processes leaking on the MnO2 cover manganese oxyhydroxide residual can react with water vapor and oxygen, that leads to the formation of crystalline defects. Such phenomenon has a negative impact on the chemical composition and integrity of the coating on the surface of the porous MnO2 tantalum capacitor anode. Also it has been found experimentally that manganese hydroxynitrate is formed from manganese nitrate in the form of microtubules on the porous tantalum vehicle surface.
Keywords: manganese dioxide, coating, manganese nitrate, thermolysis, crystalline defects, microtubules
The article suggests technique of optimization of tree cutting and skidding process via felling-skidding machines and felling-skidding-processing machines. The realization of this technique will allow reducing of time costs and raising of machine efficiency taking into account accessibility of stand cutting, relief features and technological working conditions.
Keywords: integrated machine, cutting, tree, timber harvesting, skidding.
Maximum power pointtracking algorithms are widely used in the solar converters in order to obtain maximum power from the solar array. The article provides a brief description of the work of these algorithms, description of the method of testing based on mathematical modeling using Matlab, Simulink and SimScape packages. The results of modeling and comparative analysis of the studied algorithms, its strengths and weaknesses revealed.
Keywords: maximum power point, maximum power point tracker, photovoltaic, buck converter, comparative study of algorithms, perturb and observe method, constant voltage method, constant current method, icremental conductance method
Fe-doped AlN nanorods were studied by means of x-ray absorption spectroscopy above the Fe K- and L2,3- edges. Theoretical simulations of the x-ray absorption spectra show that Fe atoms mainly substitute Al. A minor fraction of Fe interstitials or Fe-Al-N ternary alloy can be identified as well. Bader’s AIM analysis predicts that neutral substitutional FeAl defect is in 2+ charge state, though Al in pure AlN is in 3+ charge state. Fe L2,3 absorption spectra and photoluminescence data indicate the coexistence of Fe2+/Fe3+ in AlN:Fe nanorods so different charge states of substitutional FeAl should co-exist.
Keywords: diversification of management, production diversification, financial and economic purposes of a diversification, technological purposes of ensuring flexibility of production
The new way of multirate adaptation is considered. The main idea is the filter ability to change the order of the filter automaticaly by the appropriate algorithm.
The power on the filter output consists of two components. The first one is caused by the impulse response truncation, and the other is caused by weights fluctuations in the adaptive processing. More weights contribute more noise in adaptive signal processing. The result of adaptive procedure is the choice of the best filter orders in every channel of the multi-channel structure.
The main interest of this investigation is in the adaptation of the multirate adaptive filter with the flexible structural self-organization.
Due to the use of dynamical order adaptation procedure in the subbands, it is possible to reduce the total amount of the computational operations without quality reducing. Beside it, decreasing of the filter orders in the separate channel promotes considerable increase of the signal-to-noise ratio in the output signal. These statements are approved by experiments with the equalization problem.
Different results of the computer modeling are supplied with proper comments.
Keywords: adaptation, filter, multirate, signal, dynamical, order
ZnO nanorod arrays have been synthesized on silicon wafers by chemical vapor deposition (CVD) technique with different temperature modes, without metal catalyst. With this method vertically aligned ZnO nanostructures were grown at the quite low temperatures. Modification of the method allowed to place silicon substrates in areas with different ratios of concentrations of the molecules in the vapor phase. Photoluminescence spectroscopy and electron microscopy studies have shown that morphologies and optical properties of nanorods depends on different ratios of concentrations of the molecules in the vapor phase.
Keywords: ZnO nanorods,chemical vapor deposition (CVD), photoluminescence