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101.
介绍了一个用LabVIEW5 1开发的运载火箭地面测量发射模拟训练系统 ,该系统采用数据库驱动 ,将系统的面板操作、流程动态演示、在线帮助等训练功能集成 ,适用于不同型号的任务 ,具有良好的扩展性。 相似文献
102.
G. J. Gruber 《Journal of Nondestructive Evaluation》1980,1(4):263-276
Shape and size are the most important defect characteristics that need to be determined for the reliable prediction of the remaining service lifetime of a defective structure or part. The analytical and supporting experimental results presented in this paper concern a general, pattern recognition-based, ultrasonic defect identification and sizing method. The satellite-pulse technique (SPT) is based on the interpretation, in terms of defect types (shapes) and dimensions, of the separation in time of arrival between the readily detected specularly reflected pulse and its generally ignored tip-diffracted or tangentially scattered satellite contained in the received waveform. Calibration procedures were also developed that enable the ultrasonic examiner to read the time scale of the oscilloscope for equivalent crack depth or void diameter as appropriate. 相似文献
103.
利用宽频介电谱仪拓展热激励去极化电流模块测量介质材料的TSDC操作简单实用,它不仅容易把材料中的各种不同活化能或弛豫时间的荷电粒子区分开,并且能从TSDC谱中直接得出被测材料的介电性能以及相关微观参数,这为研究材料内部机理提供了一条捷径。 相似文献
104.
研究了纳秒脉冲在光子晶体光纤中的演化和传输.利用纳秒激光器产生脉宽为65ns、重复频率为150 kHz光脉冲,泵浦25 m的光子晶体光纤,获得了输出功率为0.76W、整个光谱范围超过1200 nm的超连续谱.在光谱展宽的初始阶段,光谱的展宽来源于调制不稳定性效应.随着泵浦功率的增加,发现四波混频效应对光谱短波部分的展宽起作用,受激拉曼散射效应对光谱长波部分的展宽起作用. 相似文献
105.
Miguel López-Portugués Jesús A. López-Fernández Jonatan Menéndez-Canal Alberto Rodríguez-Campa José Ranilla 《Journal of Parallel and Distributed Computing》2012
In this paper, we present a heterogeneous parallel solver of a high frequency single level Fast Multipole Method (FMM) for the Helmholtz equation applied to acoustic scattering. The developed solution uses multiple GPUs to tackle the compute bound steps of the FMM (aggregation, disaggregation, and near interactions) while the CPU handles a memory bound step (translation) using OpenMP. The proposed solver performance is measured on a workstation with two GPUs (NVIDIA GTX 480) and is compared with that of a distributed memory solver run on a cluster of 32 nodes (HP BL465c) with an Infiniband network. Some energy efficiency results are also presented in this work. 相似文献
106.
To get the scattering loss of the trapezoidal core waveguide, a new analysis model is presented based on the perturbation
equivalent method and modified effective-index method. Firstly, the trapezoidal core waveguide is successfully equivalent
to the rectangular one with both restricting the same optical field energy by adopting the perturbation method. Then, the
equivalent rectangular core waveguide is decomposed into two slab waveguides by employing the modified effective-index method.
The trapezoidal core waveguide scattering theory model is established based on the slab waveguide scattering theory. With
the sidewalls surface roughness in the range from 0 to 100 nm in the single model trapezodial core waveguide, optical simulation
shows excellent agreement with the results from the scattering loss model presented. The relationship between the dimension
and side-wall roughness with the scattering loss can be determined in the trapezoidal core waveguide by the scattering loss
model. 相似文献
107.
108.
Based on Biot's theory and considering the properties of a cavity, the boundary integral equations for the numerical simulation of wave scattering around a cavity with a circular cross-section embedded in saturated soil are obtained using integral transform methods. The Cauchy type singularity of the boundary integral equation is discussed. The effectiveness of the properties of soil mass and incident field on the dynamic stress concentration and pore pressure concentration around a cavity is analyzed. Our results are in good agreement with the existing solution. The numerical results of this work show that the dynamic stress concentration and pore pressure concentration are influenced by the degree of fluid-solid coupling as well as the pore compressibility and water permeability of saturated soil. With increased degree of fluid-solid coupling, the dynamic stress concentration improves from 1.87 to 3.42 and the scattering becomes more significant. With decreased index of soil mass compressibility, the dynamic stress concentration increases and its maximum reaches 3.67. The dynamic stress concentration increases from 1.64 to 3.49 and pore pressure concentration improves from 0.18 to 0.46 with decreased water permeability of saturated soil. 相似文献
109.
To remove haze rapidly and effectively, equivalence between Retinex model and Monochrome Atmospheric Scattering model is explored, and then a novel solution for the Monochrome Atmospheric Scattering model is proposed based on the variational Retinex. Firstly, a variational model for the atmosphere transmission map is constructed, so the transmission map estimation problem can be formulated as a Quadratic Programming optimization problem. Secondly, we calculate the transmission map and resolve the Monochrome Atmospheric Scattering model in each channel to get the Reflectance image; Finally, the Color Constancy is adopted to restore the color of the dehazed image. Experimental results show that the proposed method could remove haze rapidly and effectively, and has some advantages over other algorithms. 相似文献
110.
《西安电子科技大学学报(自然科学版)》2013,40(6):132-139
A barchan model is simulated by the theory of wind-blown sand dunes. Using the Kirchhoff Approximation based on the discrete element method, electromagnetic scattering coefficients are calculated for the cases of incident wave impinges on the single sand dune along the up-wind slope, the lee slope and the two-side slope face direction, respectively. A comparison of the backscattering coefficients and bistatic scattering coefficients for the four incident directions are made. Numerical results show that co-polarized backscattering coefficients of the lee slope have a local peak value when the incident angle is equal to the repose angle. Cross-polarized bistatic coefficient of the lee slope near the backscattering region is enhanced when the incident angle approaches the repose angle. Bistatic scattering coefficients of two-side slope faces have symmetry with respect to the azimuth angle in the incident plane. 相似文献