Self-Consistent Approximation for Fluids and Lattice Gases

A self-consistent Ornstein–Zernike approximation (SCOZA) for the direct-correlation function, embodying consistency between the compressibility and the internal energy routes to the thermodynamics, has recently been quantitatively evaluated for a nearest-neighbor attractive lattice gas and for a fluid of Yukawa spheres, in which the pair potential has a hard core and an attractive Yukawa tail. For the lattice gas the SCOZA yields remarkably accurate predictions for the thermodynamics, the correlations, the critical point, and the coexistence curve. The critical temperature agrees to within 0.2% of the best estimates based on extrapolation of series expansions. Until the temperature is to within less than 1% of its critical value, the effective critical exponents do not differ appreciably from their estimated exact form, so that the thermodynamics deviates from the correct behavior only in a very narrow neighborhood of the critical point. For the Yukawa fluid accurate results are obtained as well, although a comparison as sharp as in the lattice-gas case has not been possible due to the greater uncertainty affecting the available simulation results, especially with regard to the position of the critical point and the coexistence curve.     

V形缝隙天线的研究

本文利用第二类尖劈并矢格林函数对任意夹角的Ｖ形缝隙天线进行了矩量法计算。Ｖ形缝开在Ｖ形金属板上，并且由双线从中间馈电。文中给出了缝隙口面场分布和天线Ｈ面方向图的理论计算结果和实验结果，两者基本吻合。文中最后给出了三种非Ｖ形弯曲缝隙的实验结果。     

Zernike矩不变性分析及其改进

在分析了Zernike矩不变性后,提出了一种基于图像整个区域形状描述算子的改进Zernike矩。改进的Zernike矩不仅具有旋转不变性,而且还具有改进前不具有的比例不变性。试验结果证明,和改进前的Zernike矩相比,改进后的Zernike矩具有更好的不变特征,可用作基于区域的形状描述算子。     

Maximum entropy pdfs and the moment problem under near-Gaussian conditions

This paper focuses on a class of continuous probability density functions (pdfs) that are generated by the maximum entropy method (mem), which are of potential interest in fluid dynamics. It discusses their properties and presents a method for obtaining approximate solutions to the moment problem that is associated with this class of pdfs. The method allows one to express pdf parameters in terms of constrained moments, alone. The results thus obtained hold for pdfs that represent small perturbations from a known pdf within this class. On combining these results with exact moment equations, one obtains successful approximations to the closure relations that are associated with these pdfs. The Gaussian pdf belongs in this class, and the method can be used to explore the near-Gaussian region.     

Plastic limit analysis of cylindrically orthotropic circular plates

The plastic limit analysis of cylindrically orthotropic circular plates is developed using a piecewise linear orthotropic yield criterion. The yield criterion is a modification of an isotropic formulation that consists of a series of weighted piecewise linear components. The piecewise linear yield criterion enables an analytical solution for the plastic limit load of cylindrically orthotropic circular plates. Plastic limit analysis for both simply supported and clamped circular plates under uniformly distributed load are carried out. Parametric studies are conducted to investigate the sensitivity of the plastic limit loads to material orthotropy and influences of orthotropic ratio and chosen yield criteria on the plastic limit loads of the circular plates are discussed. It is found that the plastic limit loads of the orthotropic circular plates are affected significantly by the orthotropic ratio. Enhancement of the circumferential yield moment will increase dramatically the plastic limit load of the plates. Moment and velocity fields of the plates in plastic limit state are also derived and discussed. The results obtained from the present study are helpful in understanding the failure mechanism of orthotropic circular plates and is useful for design.     

Recognition and inspection of two-dimensional industrial parts using subpolygons

A model-based scene analysis for the recognition of imperfect and possibly occluded two-dimensional (2D) industrial parts is described. The means of recognition leads reliably to the correct association of the sides making up the unknown object to those of the model. Both the scene polygon and the model are divided into pairs of complementary subpolygons. This is done by a cutting line drawn parallel and close to a selected side. The subpolygons from the object are compared to all possible subpolygons from the model. Invariant moments are used in the analysis. A matching process using clusters of mutually consistent features is used to hypothesize the identity of the object. Examples are given to illustrate the method.     

波前像差引导准分子激光角膜消融的研究及实现

波前像差引导的准分子激光角膜消融是屈光手术的新方法 ,本文研究目的用像差来引导屈光手术 ,使人眼的视力能够达到 2 0 / 10以上 ,并避免当前PRK、LASIK屈光手术前后像差增大而引起的对视觉质量的影响。分析人眼像差的概念和产生的原因 ,并用Zernike多项式表示 ,理论上定量地分析了Zernike多项式表示的波前像差与角膜切削深度的关系 ,研究了准分子激光切削角膜的机理 ,给出了准分子激光人眼像差矫正系统的原理框图 ,达到了矫正人眼像差的目的。     

圆锥破碎机频发故障的剖析

通过对大型选矿设备———圆锥破碎机的受力分析，说明其频发故障的部位和机理，为保证机器的正常运转，在设计、制造中应当注意的问题。     

工程参数录井在钻井工程中的应用

综合录井包括气测、钻时、钻井液、钻井工程参数等多方面录井技术，是及时发现异常情况的重要手段。其中工程参数录井能够利用多种参数及时分析钻进过程中钻头、钻具、钻井液、地层压力、循环系统等设备状态，并在事故发生前提供事故预报。     

一种基于Zernike矩的直线提取算法

提出了一种新颖的基于Zernike矩(ZMs)的直线提取算法。该算法首先是利用ZMs在局部坐标系中计算边缘点所在直线方程，然后通过坐标变换将直线方程变换到图像坐标系中，从而建立了边缘点和所在直线参数之间的一一映射关系，最后对于所求出的直线参数在参数空间对参数单元投票取阈值提取直线。实验表明，该算法速度快、精度高和抗干扰性强。