Application of a Direct Stiffness Method to Wave Propagation in Multiphase Poroelastic Media

In this paper, it is demonstrated how a direct stiffness method for wavepropagation in multilayered saturated poroelastic media, based on integraltransform techniques, can be modified to account for a small amount of gasin the pores. Unsaturated media with small gas fractions can be treatedusing Smeulders extension of Biots poroelastic theory. The effect of thepresence of gas bubbles on the fluid bulk modulus and the dispersioncharacteristics of a water-saturated sand of Mol is demonstrated. Thedirect stiffness method is illustrated with a numerical example wheretransient wave propagation in a dry, saturated and unsaturated halfspaceis considered.     

Some extensions of the Lanczos-Ortiz theory of canonical polynomials in the Tau Method

Lanczos and Ortiz placed the canonical polynomials (c.p.'s) in a central position in the Tau Method. In addition, Ortiz devised a recursive process for determining c.p.'s consisting of a generating formula and a complementary algorithm coupled to the formula. In this paper a) We extend the theory so as to include in the formalism also the ordinary linear differential operators with polynomial coefficients with negative height

where denotes the degree of . b) We establish a basic classification of the c.p.'s and their orders , as primary or derived, depending, respectively, on whether or such does not exist; and we state a classification of the indices , as generic , singular , and indefinite . Then a formula which gives the set of primary orders is proved. c) In the rather frequent case in which all c.p.'s are primary, we establish, for differential operators with any height , a recurrency formula which generates bases of the polynomial space and their multiple c.p.'s arising from distinct , , so that no complementary algorithmic construction is needed; the (primary) c.p.'s so produced are classified as generic or singular, depending on the index . d) We establish the general properties of the multiplicity relations of the primary c.p.'s and of their associated indices. It becomes clear that Ortiz's formula generates, for , the generic c.p.'s in terms of the singular and derived c.p.'s, while singular and derived c.p.'s and the multiples of distinct indices are constructed by the algorithm.

     

Method of moments on semigroups

If ( _j ) is a sequence of measures onR ^k having momentss _n ( _j ) of all ordersnN ₀ ^k and if for eachnN ₀ ^k the sequence (s _{n j} )) _jN converges to somet _n R then some subsequence of ( _j ) converges weakly to a measure with moments of all orders satisfyings _n ()=t _n for allnN^0/k . Thisindeterminate method of moments and the continuity theorems in probability theory suggest a common generalization, dealing with a commutative semigroupS, with involution and a neutral element, and measures on the dual semigroupS ^* ofcharacters on S—hermitian multiplicative complex functions not identically zero. In this setting, a continuity theorem holds for measures on the set of bounded characters,⁽²⁾ and an indeterminate method of moments whenS is finitely generated.⁽²⁾ The latter result is generalized in the present paper to the case of arbitraryS. This leads to a generalization of Haviland's criterion for theK-moment problem, and to a continuity theorem for the so-called perfect semigroups.     

两部件冷备系统的可靠性分析及其最优更换策略

本文研究了两个不同部件、一个修理工组成的冷贮备可修系统,假定它们的寿命分布和维修分布均匀为指数分布,但故障后均不能修复如新时,我们利用几何过程和补充变量法求得了一些可靠性指标,并以故障次数为策略,以长期运行单位时间内的期望效益为目标函数,确定了最优的故障次数,便得目标函数达到最大值,从而保证了系统的可用度。     

一种新型的列阵反射镜调整架

 针对组束激光系统主放大器而设计的一种新型的列阵反射镜调整架, 克服了多个调整架结构松散的缺点, 满足了多路激光束之间间距较小的特殊要求;同时采用了柔性铰链机构及步进电机传动中联轴驱动一体机构,使整套系统具有调整精度高、稳定性好等特点。     

X射线荧光光谱-玻璃熔融制样法分析铁矿中主成分和微量成分

采用ｎ样品：ｍ熔剂为１∶２的低稀释比玻璃熔融技术、Ｘ射线荧光法测定铁矿中的主成分和微量成分、既提高了灵敏度又消除了不均质效应,与粉末压片方法相比,对硫的分析得到了更好的结果。使用基本参数程序建立了一新的校正方法来校正由于烧失量、烧增量、稀释比或熔剂挥发而导致的分析误差     

系数倍率双波长标准加入法同时测定铜和铁的研究

本文报道了一种同时测定铁和铜的新方法。在含有乳化剂ＯＰ的弱酸性介质中,显色剂１－（２－吡啶偶氮）－２－萘酚与铜,铁形成红色配合物,其最大吸收波长为５６０ｎｍ。本法选择５６０ｎｍ为测定波长,６００ｎｍ为参比波长,按系数倍率双波长标准加入法原理处理数据,实现了铜和铁的同时测定,并应用该法直接测定了铝合金中铜和铁的含量,结果满意。     

对方案聚合方法的两点改进

１引言Ｒｏｃｋａｆｅｌｌａｒ和Ｗｅｔｓ共同提出的方案聚合方法（ＳｃｅｎａｒｉｏＡｇｇｒｅｇａｔｉｏｎＭｅｔｈｏｄ,简称ＳＡＭ）［１］已被公认为是解决随机规划的行之有效的且具有极大潜力的好方法．这种方法与以前的逼近方法完全不同,它将含有多阶段条件期望值的复杂的优化问题分解为一系列相对简单的确定性的平行的子问题,把子问题的最优解“聚合”起来做为原问题最优解的估计值．许多计算结果表明［２］［３］,这种方法是独特的、可行的．然而正如两位杰出的作者在［１］中指出的,这种方法还有很大的改进余地,这也正是ＳＡ…     

变分不等式的几类求解方法

本文转为系统地分析和概述了变分不等式问题中几类占有重要地位的求解方法,包括方法产生的背景,主要结果及应用等,这几类算法分别为连续算法,（拟）牛顿型算法,一般迭代模型,投影算法,投影收缩算法等。     

一种用于线性规划算法的换基准则

本文就线性规划中的对偶单纯形法和运输问题中的表上作业法选取出基变量或者对基变量的准则进行改进,从而得出一种新的换基准则.按该方法进行优化运算,可以使算法的迭代次数减到最少,从而加快了运算速度.