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11.
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A method is presented for the construction of fixed-order compensators to provide H∞ norm constraint for linear control systems with exogenous disturbances. The method is based on the celebrated bounded-real lemma that predicates the H∞ norm constraint via a Riccati inequality. The synthesis of fixed-order controllers whose dimensions are less than the order of a given plant, is demonstrated by a set of sufficient conditions along with a numerical algorithm. 相似文献
13.
A theory related to the statistics of the structure and properties of inhomogeneous materials has been proposed, dealing with the distribution of properties from sampling of inhomogeneous structures by line transects. It is demonstrated that the empirical cumulative distribution functions of the intercepts from the microstructural constituents and their variances are important fingerprints of the inhomogeneous structures.Simulated sampling of the images of the microstructure by line transects has been proposed as a powerful method for characterization the distribution of properties of inhomogeneous structures. One of the advantages of the method based on the expected values of the order statistics of the intercepts is that the probability bounds of the property are determined without prior knowledge of the functional relationship between the property and the intercepts from the structural constituents.The concept intercept variance has an important application in determining the minimum transect length that stabilizes the variation of the intercept at a low value. Additionally, the concept ‘intercept variance’ can be used for topological optimization of the microstructure regarding the risk of intercepting a large amount of the weaker constituent. Equations regarding the variance of the intercepted fraction characterizing transect lengths with a specified distribution have also been derived. 相似文献
14.
分析了喘振现象和其发生的原因,讨论了大功率压缩机设备变频节能和防喘振原理,研究了利用单片机为核心的补偿控制器,实现了对压缩机进行调速一旁路回流的控制摸式,并在应用中取得了良好收益。 相似文献
15.
Sung D. Kwon Sung J. Song Dong H. Bae Young Z. Lee 《Journal of Mechanical Science and Technology》2002,16(9):1084-1092
The frequency dependency of Rayleigh surface wave is investigated indirectly by measuring the angular dependency of the backward
radiation of the incident ultrasonic wave in two kinds of degraded specimens by scuffing or corrosion. Then, the frequency
dependency is compared with the residual stress distribution or the corrosion-fatigue characteristics for the scuffed or corroded
specimens, respectively. The width of the backward radiation profile increases with the increase of the variation in residual
stress distribution for the scuffed specimens. In the corroded specimens, the profile width decreases with the increase of
the effective aging layer thickness and is inversely proportional to the exponent, m, in the Paris’ law that can predict the
crack size increase due to fatigue. The result observed in this study demonstrates high potential of backward radiated ultrasound
as a tool for nondestructive evaluation of subsurface gradient of material degradation generated by scuffing or corrosion. 相似文献
16.
Recently, in our laboratory a closed form expression for the correlation function of the hard-sphere dimer fluid obtained
from Wertheims multidensity Ornstein-Zernike integral equation theory with Percus-Yevick approximation was presented by Kim
et al. [2001]. However, it is difficult to apply its expression to perturbation theory and vapor-liquid equilibria calculations,
since it is of very complex form. In this work, we present a simplified expression for the first shell of the radial distribution
function (RDF) of the hard-sphere dimer fluid using a series expansion of the analytical expression. The expansion is carried
out in terms of both the packing fraction and the radial distance. Expressions are also obtained for the coordination number
and its first and second derivatives as functions of radial distance and packing fraction. These expressions, which are useful
in perturbation theory, are simpler to use than those obtained from the starting equation, while giving good agreement with
the original expression results. Then we present an simplified equation of state for the square-well dimer fluid of variable
well width (λ) based on Barker-Henderson perturbation theory using its expression for the radial distribution function of
the hard-sphere dimer fluid, and test its expression with NVT and Gibbs ensemble Monte Carlo simulation data [Kim et al.,
2001]. 相似文献
17.
郭广海 《青岛科技大学学报(自然科学版)》2008,29(3)
采用多项式函数代替乌龟坐标的方法,给出静态球对称时空中黑洞事件视界和宇宙视界区域内标量场方程的解,并对事件视界附近势垒的性质进行了讨论。发现对带电量不同的时空,标量场辐射的形式亦有所不同;势垒随宇宙学常数的减小而变窄、变高。 相似文献
18.
19.
WANGWensheng XUBin 《半导体光子学与技术》1998,4(1):40-44,61
According to the theory of testing aspherical surface by normal aberration compensation method,the designing method of quasi-universal compensator is studied.On the basis of third-order aberration theory,after calculating and optimizing with an optical design program,the structure parameters of a compensator are obtained.This new compensator could be used in Twyman-Green interferometer,and in measurement of a certain range of paraboloid ellipsoid and hyperboloid.The compensation accuracy is more than 0.02λ. 相似文献
20.