In this paper, we propose a method for generating a single texture map for 3D model reconstructed by 3D scanner. Simple image projection results in visible seams on the surface of the scans, and all the analogues of t...
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The paper presents the results of experimental studies of crack resistance at the fusion boundary of the base material and the built-up layer in cylindrical specimens made of CuAl9Mn2 alloy using additive technology o...
The paper presents the results of experimental studies of crack resistance at the fusion boundary of the base material and the built-up layer in cylindrical specimens made of CuAl9Mn2 alloy using additive technology of powder laser surfacing. The aim of the study is to analyze possible changes in the mechanical properties of the base material at the fusion boundary under the action of high temperatures. On the basis of the experimental data it is obtained that the thermal action during laser powder surfacing has not a great impact on the crack resistance of both the base material and the built-up metal.
This paper presents the results of modeling and fabrication of silicon membranes for acoustic sensors with resonant frequency from 2 kHz to 60 kHz and pressures from 0.1 to 14 Pa. An analysis of the constructive and m...
This paper presents the results of modeling and fabrication of silicon membranes for acoustic sensors with resonant frequency from 2 kHz to 60 kHz and pressures from 0.1 to 14 Pa. An analysis of the constructive and mechanical parameters of monocrystalline silicon membranes is performed. The range of membrane edge length (6-20 mm) at a fixed thickness of 50 μm determined. The etching process of a silicon wafer by anisotropic wet etching was studied. A process flow for manufacturing silicon membranes is proposed. The results of experimental studies of amplitude-frequency characteristic of membranes are obtained.
Polycrystalline and oriented films of barium disilicide (BaSi2) with a thickness of up to 100 nm were formed on silicon (111) substrates by high-temperature (800 ° C) solid-phase (single-stage and two-stage) anne...
Polycrystalline and oriented films of barium disilicide (BaSi2) with a thickness of up to 100 nm were formed on silicon (111) substrates by high-temperature (800 ° C) solid-phase (single-stage and two-stage) annealing. The single phase of barium disilicide films and their semiconductor nature have been proven to be below 1.25 eV according to X-ray and optical spectroscopic methods. Two preferential orientations of the BaSi2 crystallites were detected and their orientation was determined in the films formed by two-stage annealing. According to the calculations of the parameters of the crystal structure of BaSi2 films, a compression of the unit cell volume from 2.7% to 5.13% was found, depending on the cooling time to room temperature. The stability of the films to laser radiation was studied by registering the Raman spectra with a variable power of laser radiation. The maximum power density of the laser beam (3⋅109 W/m2), which does not lead to the beginning of the destruction of these films, was determined.
Numerical modelling of heterogeneous combustion in porous media with phase transitions is considered. To describe the propagation of time-dependent one-dimensional waves of heterogeneous combustion of metal-containing...
Numerical modelling of heterogeneous combustion in porous media with phase transitions is considered. To describe the propagation of time-dependent one-dimensional waves of heterogeneous combustion of metal-containing mixtures, a mathematical model and a numerical method are proposed. The model is based on the assumption of interacting interpenetrating continua using classical approaches of the theory of filtration combustion and includes equations of state, continuity, momentum conservation and energy for each phase. The numerical method is based on a combination of explicit and implicit finite difference schemes. The carried out numerical calculations showed the efficiency of the proposed model and allowed one to detect the concentration of the condensed metal near the front of the combustion wave.
This paper proposes a flocking control algorithm for a team of autonomous underwater vehicles (AUVs) deployed for group motion in a network where only local communication exists among the participating AUVs. The contr...
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ISBN:
(纸本)9783902734112
This paper proposes a flocking control algorithm for a team of autonomous underwater vehicles (AUVs) deployed for group motion in a network where only local communication exists among the participating AUVs. The control scheme is proposed with two levels where the inner level utilizes agreement or consensus protocol to derive reference positions for the follower AUVs whereas the outer loop employs a sliding mode controller (SMC) to reduce the tracking error to zero. SMC being a suitable candidate for handling is chosen because of its inherent robustness to any uncertainties and disturbances, it is intended to design a SMC to address the problem of handling uncertainties in the hydrodynamic parameters of the AUV dynamics and has been used to steer each AUV in the flock to their desired states. By exploiting the consensus protocol and SMC, it can be ensured that once an AUV comes into the neighbour zone (maximum range for information exchange for a member AUV outside which no communication is possible) cannot be separated from the group. Therefore, this controller structure is suitable for flocking of multiple AUVs where communication constraints play a vital role in efficient performance of control algorithms. The effectiveness of the proposed controller scheme is demonstrated through MATLAB simulation.
Formation of a chiral nanorelief appearing on the surface of plasmonic-active metals upon their ablation with vortex and spiral-shape beam was recently found to be mainly driven by the helical-shape temperature and co...
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Paper presents the results of studying the features of recording acoustic emission waves by fiber-optic sensors. Fiber-optic sensors are used as an elastic medium that receives acoustic emission waves. Optical fibers ...
Paper presents the results of studying the features of recording acoustic emission waves by fiber-optic sensors. Fiber-optic sensors are used as an elastic medium that receives acoustic emission waves. Optical fibers were built between the layers of the polymer composite material during the manufacturing process. The measuring system is constructed on the basis of an adaptive interferometer. Optical fibers are part of the interferometer optical scheme. The elastic wave acting on an optical fiber changes its optical density, changing the interference pattern of the optical beam. The work of the holographic interferometer based on the fact that the interference pattern, formed by the object and reference light beams, is a dynamic hologram that is constantly recorded in the photorefractive crystal during the elastic action on the fiber. Sensitivity of fiber-optic sensors based on an adaptive interferometer allows recording acoustic emission waves. The acoustic emission waves were generated by the Hsu-Nielsen source. A significant difference in the speed of sound is explained by the anisotropy of the properties of the composite material. The structure and density of the material's fibers in different directions are different. The wavelet transformation was used to form the signal front.
The paper presents a fault accommodation system for electric servo actuators of underwater manipulators. These actuators are described by nonlinear equations with variable parameters. It is assumed, that the following...
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ISBN:
(纸本)9783902734112
The paper presents a fault accommodation system for electric servo actuators of underwater manipulators. These actuators are described by nonlinear equations with variable parameters. It is assumed, that the following typical faults are possible in electric servo actuators: fault caused by changing of viscous friction moment and error in the sensor, which measures the position of output shaft of gear. The proposed system is based on using of diagnostic observers with residual signal feedback. It is proposed the methodology of synthesis of such observers for detection and identification of occurred faults. The accommodation to faults is ensured due to the generation of additional control signals based on identified value of faults. This provides the reliability of underwater working of manipulators at faults. The efficiency of the proposed system is confirmed by mathematical modelling.
The metal–silicon thin-film system is not isostructural and furthermore exhibits pronounced interdiffusion and chemical reactions. Therefore the growth of metallic films on silicon leads to a nanosize nonhomogenity o...
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The metal–silicon thin-film system is not isostructural and furthermore exhibits pronounced interdiffusion and chemical reactions. Therefore the growth of metallic films on silicon leads to a nanosize nonhomogenity of films and a high concentration of defects, especially at interface. The material also contains stressed transition layer, which can contain alloys and/or compounds (silicides). We have considered theoretical viewpoints and reviewed experimental data on the growth and properties of metallic nanofilms (including multilayered ones) on silicon, and also provided a brief review of their applications. The films consist either of atomic-sized, quabquantum sized and quantum sized layers. We have suggested a low temperature film growth technology based on freezing growing layers during deposition by maintaining a low temperature of the substrate and using an atomic beam with a reduced heat power. The technology uses a specially shaped deposition system in which the distance between the source and the substrate is comparable to their size or smaller. Furthermore, we use a special time sequence of deposition that provides for a reduced substrate surface temperature due to greater intervals between deposition pulses. This growth method of atomically thin films and multilayered nanofilms excludes interdiffusion between the layers, reduces three-dimensional growth rate and relatively increases lateral layer growth rate.
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