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111.
水流中锚链阻力系数测量的实验设计 总被引:1,自引:0,他引:1
为了在水池内测出船模拖曳时锚链在水流中的阻力系数,设计了一套简单而有效的实验方案。考虑到锚链的柔软与笨重,故采取了三项措施:(1)将锚链相邻链环连接处点焊住,使其成一根直杆;(2)将该锚链水平悬挂于拖车之下,用拖车运行速度模拟流速,通过锚链悬挂绳与铅垂线的夹角来计算水流对锚链的作用力;(3)为了消除锚链两个端部对阻力测试的影响,用长、短锚链的阻力差值除以锚链长度差,既得到了单位长度锚链的阻力,又有效地解决了端部影响,进而计算出锚链阻力系数。 相似文献
112.
This paper presents a postulate for a new approach in the measurement of households’ satisfaction from durable consumer goods, based on a modified inflation expectation measurement method used in survey research. The authors examine the application of a three-step qualitative evaluation, followed by the quantification of responses using a modified Carlson and Parkin method adopted in the context of the free tangent law. 相似文献
113.
The existence of a continuous best approximation or of near best approximations of a strictly convex space by a subset is shown to imply uniqueness of the best approximation under various assumptions on the approximating subset. For more general spaces, when continuous best or near best approximations exist, the set of best approximants to any given element is shown to satisfy connectivity and radius constraints. 相似文献
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The main purpose of this work is to present two semi-analytical solutions for the von Mises elastoplasticity model governed by combined linear isotropic-kinematic hardening. The first solution (SOLε) corresponds to strain-driven problems with constant strain rate assumption, whereas the second one (SOLσ) is proposed for stress-driven problems using constant stress rate assumption. The formulas are derived within the small strain theory Besides the new analytical solutions, a new discretized integration scheme (AMε) based on the time-continuous SOLε is also presented and the corresponding algorithmically consistent tangent tensor is provided. A main advantage of the discretized stress updating algorithm is its accuracy; it renders the exact solution if constant strain rate is assumed during the strain increment, which is a commonly adopted assumption in the standard finite element calculations. The improved accuracy of the new method (AMε) compared with the well-known radial return method (RRM) is demonstrated by evaluating two simple examples characterized by generic nonlinear strain paths. 相似文献
116.
A novel model for lightly-doped-drain (LDD) MOSFETs is proposed, which utilizes the empirical hyperbolic tangent function to describe the I-V characteristics. The model includes the strong inversion and subthreshold mechanism, and shows a good prediction for submicron LDD MOSFET. Moreover, the model requires low computation time consumption and is suitable for design of MOSFETs devices and circuits. 相似文献
117.
IntroductionItiswell_knownthattheFritzJohnoptimalityconditionwithderivativeisoneofthemostimportantresultsofconstrainedoptimizationtheory .Ithasbeenextendedtovector_valuedfunctionsinabstractspacesunderweakefficiency[1].WiththehelpofakindofContingentderiv… 相似文献
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Kellie Brown John Cameron John Stears Wayne Hicky Roger Cormier Xiaoyi Bao Liang Chen 《Fiber and Integrated Optics》2001,20(5):427-442
With OC-192 communications systems being commercially available and higher bit rate systems in development, prudent telecommunications network administrators are testing their installed fibers to determine if they can be successfully used at 10 Gb/s and higher. Together with New Brunswick Telephone (NBTel), the Fiber Optics Group at UNB have tested various installed fibers and cables in the NBTel network for their losses at wavelengths of 1244, 1310, 1550, and 1625 nm, as well as for strain and polarization mode dispersion (PMD). Weather conditions, age, place of installation, and cable types have also been considered. Aging does not seem to affect the performance of the fibers. Although most fibers are high-speed system compatible when looking at attenuation measurements, about 40% of the fibers tested would not meet the 10 Gb/s OC-192 system manufacturer's design guidelines concerning PMD. 相似文献
120.
Stein流形上全纯函数积分公式的拓广 总被引:3,自引:0,他引:3
得到了Stein流形上一种全纯函数的积分式,这种公式的特点含有可供选择的参数m≥2的整数,当m=2时即为Stein流形上全纯函数的方B-M公式. 相似文献