共查询到20条相似文献,搜索用时 46 毫秒
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P. E. Tverdokhleb Yu. A. Shchepetkin 《Optoelectronics, Instrumentation and Data Processing》2007,43(3):292-298
A method is proposed for parallel (simultaneous) readout of information from threedimensional “coupled” Fourier holograms. The method is based on the principle of transformation of informational degrees of freedom of the optical signal with the use of moving diffraction gratings: the spectrum of spatial harmonics of superimposed holograms is transformed to a spectrum of time harmonics separated in terms of frequency. A method of formation of images of moving gratings with a prescribed orientation in the volume of the recording material is developed. Conditions of the frequency separation of the signals, resolution of the method over the material depth, and the number of detected bits as a function of grating parameters are obtained. 相似文献
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An indirect measurement method based on recording the phase difference of resonance vibrations of two symmetrical halves of the flow-carrying tube is used to quantify the mass flow rate of the current fluid in Coriolis mass flowmeters (CMFs). A variant of modeling the CMF vibration system is analyzed, which allows taking into account the influence of the dissipation of oscillations of a measuring tube with fluid flowing through it on the dependence between the mass flow rate of the fluid and the phase difference recorded by the sensor. The steady-state CMF vibration mode is considered as the result of the superposition of two principal vibrations of the measuring tube. The first principal coordinate corresponds to the deformation of the measuring tube along the lowest natural mode excited by an external driving force in the resonance mode. Vibrations of the other principal coordinate correspond to deformation in a natural mode corresponding to a higher natural frequency than the frequency of the exciting force. The relationship of the amplitudes of the principal coordinates is established on the basis of the gyroscopic coupling of the principal vibrations that occurs when a fluid flows through a tube. The coefficients of gyroscopic coupling are determined as a result of 3D finite-element simulation of the steady-state vibration mode of the measuring tube with a flowing fluid. The simulation is performed for five variants of the shape of the axis of the measuring tube, taking into account the distribution of the gyroscopic forces of the flowing fluid. Quantitative estimates of the influence of dissipative forces on the flowmeter readings are obtained on the example of dissipative forces of linear viscous friction. A comparison of the CMF simulation results for different tube axis shapes demonstrates how the phase shift arising in the vibration system is affected by the dissipation level and the proximity of the natural frequencies of the flowmeter measuring tube at a fixed mass flow rate of the fluid. 相似文献
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V. I. Erofeev N. V. Klyueva I. N. Soldatov 《Russian Journal of Nondestructive Testing》2007,43(4):256-262
The amplitude—frequency characteristics of the vibrations of the surface of a free elastic layer are determined. These vibrations are caused by propagating Lamb waves under the action of a normal surface load. The changes in the spectra of surface displacements and in the tangential-to-normal displacement-amplitude ratios during changes in the Poisson ratio are studied. Studying the spectrum of surface displacements of an elastic layer is of interest owing to the necessity of discriminating modal components of the wave field [1] and as one of possible methods for determining some of the parameters of a material. The ratio of the amplitudes of the horizontal and vertical displacements as a function of the frequency of a vibration source is sensitive to the Poisson ratio of the material and the conditions of the contact with the base. The amplitude-frequency characteristics of the surface displacements of an elastic isotropic layer are plotted and compared to those obtained in the case of a layer that is in contact with a rigid base. 相似文献
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A. I. Nazmutdinova V. N. Milich 《Optoelectronics, Instrumentation and Data Processing》2016,52(3):231-237
The problem of classification of space multispectral images of forest vegetation is considered. Features based on the wavelet transform and a classification method involving consideration of the importance of each feature are investigated. Dependence of the classification results on the wavelet function, the level of the transform, and the parameter of the classification method — the number of segments of the range of features — is given. Results of classification of multispectral images of six classes of forest vegetation in images obtained by a Rapid Eye shooting system are presented. 相似文献
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为提高加工精度,对立铣刀的应力场进行了有限元分析。通过铣削力试验,对不同切削参数下立铣刀的铣削力进行动态采集,利用UG中的建模模块进行立铣刀实体建模,根据切削力实验结果给出了边界条件,在立铣刀有限元模型上进行加载,利用UG有限元分析模块,获得了立铣刀切削过程中切入、切出的瞬时应力场云图,显示了切削中铣刀片应力场的变化规律。 相似文献
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利用协同优化方法实现复杂机械系统的设计优化 总被引:5,自引:0,他引:5
利用协同优化方法实现了四辊轧机机座的结构参数设计优化。根据多学科设计优化对复杂系统进行设计优化的思想,提出将复杂机械系统分解为若干个简单的子系统进行设计优化。协同优化是近年来发展较快的一种多学科设计优化算法,描述了应用于复杂工程系统优化设计的协同优化方法。在协同优化的系统级优化中,引入松弛变量,将一致性等式约束转化为不等式约束,松弛变量的取值影响系统级优化的收敛速度。通过对四辊轧机机座的结构参数设计优化,给出了利用协同优化方法进行复杂机械系统设计优化的一般思路,为解决更为复杂的机械系统的设计优化问题打下了基础。算例证明了协同优化算法解决复杂机械系统设计优化问题的有效性。 相似文献
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Zygmunt Towarek 《International Journal of Mechanical Sciences》1998,40(6):557-574
In this work the influence of flexible soil foundation on the dynamic stability of the boom crane is presented. This analysis was made during the rotation of the boom, such that variable pressure on the soil and other deformations could be taken into account. The rheological deformation of the soil as a function of the changing strain in time has been described by an equation, which is the Duhamel integral. After accepting the discrete model of the considered system dynamic equations of motion were elaborated, which because of their nonlinearity and complexity were solved numerically. Appointed were the dynamic displacements of each of the supports for different rotational speeds of the boom, showing the influence of the rheological deformation of the soil on the behaviour of the whole crane. As well the trajectories of the motion of the weight hoisted were presented for different rotational speeds of the boom, which enabled the analysis of the precision of the positioning of the weight being hoisted (minimization of oscillation). 相似文献
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J. Lawrence Paul 《Journal of microscopy》1981,122(2):165-172
We outline the results of a computer program which calculates frequency distributions of functions of cross-sectional regions of convex planar-faced polyhedra, ‘sphero-polyhedra’, and populations of perturbed polyhedra. This is done by ‘cutting’ a computer representation of the figure by a large number of random planes. The procedure is applied to cubes, dodecahedra, truncated octahedra, and approximate β-tetrakaidecahedra. Certain aspects of the shape of the object, e.g. sharpness of corners, angularity, compactness, and degree of symmetry are related to aspects of the shape of the distribution curves, e.g. beginning and ending points of the curves, rate of rise of the peak, relative location of the peak, and height and width of the peak. 相似文献
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H. D. Mallon 《Journal of microscopy》1969,90(2):107-125
The mathematical analysis of a beam of polarized light into two constituent beams of plane-polarized light vibrating at right angles to each other and with a difference of phase, can be somewhat time-consuming. This paper describes a graphical method of solution, of reasonable accuracy, which can be carried out rapidly. The simple geometry of the representation of a polarized beam as a point on the surface of the Poincaré sphere is explained together with the stereo-graphic projection of the surface of the sphere on a diametral plane. Examples are given of the use of the stereogram in conjunction with the polarizing microscope for the determination of phase difference of a transparent crystal, for the determination of the state of polarization after transmission through a bire-fringent crystal and for the analysis of superimposed crystals. 相似文献
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G. S. Sadykhov 《Journal of Machinery Manufacture and Reliability》2014,43(4):327-332
A formula for calculation of inspection times of monitoring the technical condition of a hazardous industrial facility, as well as a formula for calculation of the number of operation intervals between monitoring events depending on certain values of parameters of reliability of the facility were demonstrated. In addition, the monotonic behavior of the duration of equally possible operational intervals between monitoring events for facilities with monotonic changes in fault occurrence intensity was defined. A monotonic behavior in values of probabilities of flawless performance of the facility within intervals between monitoring events with equal duration of operation and monotonic change in intensity of faults occurrence were demonstrated. 相似文献
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V. P. Sergienko M. Yu. Tseluev V. I. Kolesnikov A. P. Sychev V. A. Savonchik V. I. Yanuchkovskii 《Journal of Friction and Wear》2013,34(6):421-428
A dimensionless heat problem for a friction pair of a multidisc brake was formulated under conditions of a linear decrease in the friction power of discs with time. Thermal state of friction pairs of the multidisc brake under load and velocity conditions of the friction of the discs that simulate service brakings of a wheel tractor was experimentally and theoretically studied. The validity of a mathematical model of the temperature field in the discs of the brake has been experimentally confirmed and functional dependences of the maximum temperature of friction surfaces of the discs on values of the main performance parameters have been obtained. 相似文献
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V. E. Vil’deman M. P. Tretyakov 《Journal of Machinery Manufacture and Reliability》2013,42(2):166-170
The paper deals with the theoretical and experimental aspects of the study of the behavior of materials at the stage of supercritical deformation or work softening, consideration of which is important for the assessment of the durability of structures. The study results show the theoretical confirmation of the effect of the specimen configuration on the possibility of plotting the descending portions of deformation curves. It is shown that the equilibrium supercritical deformation of a material is possible if the stiffness of the loading system is sufficient. This is confirmed by the results of the uniaxial tension tests with unloading at various stages of elastoplastic and supercritical deformation. The method for interpreting experimental data obtained for the specimens of various dimensions under conditions of deformation localization are considered. 相似文献