Asymptotics of Quantum Mechanical Atom-Ion Systems

 We have analyzed and reduced a general (quantum-mechanical) atom-ion diatomic exchange energy formulation into fundamental mathematical forms, namely a particular class of single and double definite integrals. These are of importance in the charge exchange of molecular processes in atmospheric physics and eventually of interest to matters related to climate. These integrals have been evaluated in terms of asymptotic expansions, with precise schemes for their numerical evaluation. Dividends for algebraic aspects concerning identities of hypergeometric functions as well as summation techniques for divergent series are also discussed in this context. Received: September 7, 2001; revised version: May 3, 2002     

Diagnosis Modelling for Dependability Assessment of Fault‐Tolerant Systems Based on Stochastic Activity Networks

The growing demand for safety, reliability, availability and maintainability in modern technological systems has led these systems to become more and more complex. To improve their dependability, many features and subsystems are employed like the diagnosis system, control system, backup systems, and so on. These subsystems have all their own dynamic, reliability and performances and interact with each other in order to provide a dependable and fault‐tolerant system. This makes the dependability analysis and assessment very difficult. This paper proposes a method to completely model the diagnosis procedure in fault‐tolerant systems using stochastic activity networks. Combined with Monte Carlo simulation, this will allow the dependability assessment by including the diagnosis parameters and performances explicitly. Copyright © 2014 John Wiley & Sons, Ltd.     

Dependability analysis of semi-Markov systems

This paper presents a dependability analysis (Availability-Reliability-Maintainability, Mean times) for semi-Markov systems with finite state space, by a new method, based on algebraic calculus within a convolution algebra. This method permits us to obtain, by simple matrix calculus, closed form solutions of transition probabilities and dependability measures. It is a quite general method that does not need the semi-Markov kernel to be absolutely continuous. Thus we obtain, as an example, the classical availability formulae modelled by an alternating renewal process, by a simple algebraic calculus without probabilistic argument. A detailed application of the method is given.     

Study of Dependability Evaluation for Multi‐hierarchical Systems Based on Max–Min Composition

This article presents the model for calculating the performance of dependability for complex technical systems. According to ISO‐IEC 300, dependability is an overall indicator for the quality of service and considers simultaneously reliability, maintainability, and maintenance support. For a proper understanding of the quality of service for any technical system, it is important to define dependability performance at the level of single component as well as at the upper levels—levels of subsystems and entire system. As dependability indicators (reliability, maintainability, and maintenance support) have been defined as linguistic variables, the fuzzy max–min composition has been used for the dependability determination and integration of its indicators. A procedure for the synthesis of single components dependability performance to upper levels in complex technical system is proposed. Max–min composition is again used as a tool for fuzzy synthesis because it enables obtaining the comprehensive and synergetic effect in a process of dependability evaluation. A practical engineering example (mechanical systems at bucket wheel excavator) has been used to demonstrate the proposed dependability synthesis model. Copyright © 2012 John Wiley & Sons, Ltd.     

双模聚氨酯交联体系的力学性能

以端羟基聚丁二烯(HTPB)、环氧乙烷-四氢呋喃共聚醚(PET)以及聚叠氮缩水甘油醚(GAP)为粘合剂,多异氰酸酯(N100)、异佛尔酮二异氰酸酯(IPDI)为固化剂,三羟甲基丙烷(TMP)为交联剂,制备了PETS/PETL/N100、GAP/PETL/N100、GAP/PET/IPDI/TMP、GAP/HTPB/IPDI/TMP四种双模聚氨酯交联体系,研究了双模网络对聚氨酯弹性体力学性能的影响。结果表明,双模体系较之于短链单模体系,力学性能有了较大的改善。双模聚氨酯交联体系力学性能的提高主要是非仿射变形的结果,非仿射变形程度主要取决于交联点之间的氢键数。单组分固化反应速率的差异对双模体系的力学性能影响较大。     

分段光滑机械系统动力学的进展

含间隙、约束、摩擦、迟滞等分段光滑力学因素的机械系统动力学是振动工程界广泛重视的研究领域、本文综述了近十年来该领域的研究进展，包括：系统实验建模、周期运动数值解法，运动稳定性，分叉与混沌，以及工程应用，最后，指出若干值得研究的问题。     

影响微电子机械系统成品率和可靠性和粘合力和磨擦力

章评述了影响微电子机械系统（MEMS）成品率和可靠性的粘合力和摩擦力问题。在用氢氟酸（HF）腐蚀牺牲层、释放多晶Si微结构、干燥时,由于Si片表面薄层水的表面张力使两片亲水、间隙在微米量级的Si片粘合起来,称为“释放有关粘合”。粘合也发生在封装后器件中,当输入信号过冲时,由于Si片表面的化学状态将Si片粘合起来,称为“使用中粘合”。解决粘合的最好办法是：在MEMS微结构的表面涂以抗粘合薄膜,将成品器件在干燥气氛下封装。介绍了抗粘合薄膜的制备工艺和目前存在的问题。相比之下,具有高速运动的MEMS,其摩擦力问题更为复杂。应和抗粘合薄膜,解决了粘合,也降低了摩擦力,但摩擦依然存在。摩擦带来磨损,降低器件可靠性和寿命。寻找既抗粘合、又耐磨的薄膜,是解决高速运动MEMS可靠性和寿命的一个关键。     

System Effectiveness Simulation Model with Nonparametric Dependability

The simulation model presented here is a useful extension of WSEIAC's system's effectiveness methodology. This model accepts information regarding uncertainty with the parametric estimates of the system's attributes. One of the system's attributes, defined as “dependability,” requires Markovian State Transition Process. Time-dependent queueing process and renewal theory application for this dependability matrix are avoided by resorting to a simulation technique. This dependability matrix requires reliability and repairability estimates, which are obtained based on a non-parametric approach. This approach is based on a test program with a very realistic environment where n identical units are placed on test for a mission duration T. At the end, the number of failed units r is noted. Units failed are not replaced. Times of failed units before failure are unknown. Based on these, the dependability matrix is generated, which results ultimately in generating a sampling distribution of system effectiveness of each subsystem and the overall system. This process is coded in FORTRAN IV.     

Preparation of the Disperse Systems of Sulfathiazole-Polyvinylpyhrolidone by Mechanical Activation

The potential value of solid-state dispersions of insoluble drugs in water-soluble matrices is known to bring about enhancement of solubility, dissolution rate and bioavailability of the drugs. The conventional methods of preparation of solid dispersions such as fusion or solvent technique are somewhat limited. The method of mechanical activation analogous to that which is employed in the mechanical alloying method may be used in preparation of dispersions of organic solids. In this paper, the method of mechanical activation is applied to obtain a solid-state dispersion of sulfathiazole in polyvinylpyrrolidone. The mechanical treatment of sulfathiazole with polyvinylpyrrolidone in a planetary ball mill transfers crystalline drug into amorphous state, the process being accompanied by formation of hydrogen bonds of sulfathiazole with matrice. The apparent solubility and rate of solvation of sulfathiazole were greatly increased if it was previously mechanically treated with polyvinyl -pyrrolidone. The release of sulfathiazole from solid dispersions with polymer to drug ratio of 1:3, 1:1, 3:1 was examined, a polymer to drug ratio of 3:1 gave the highest solubility.     

Preparation of the Disperse Systems of Sulfathiazole-Polyvinylpyhrolidone by Mechanical Activation

Abstract

The potential value of solid-state dispersions of insoluble drugs in water-soluble matrices is known to bring about enhancement of solubility, dissolution rate and bioavailability of the drugs. The conventional methods of preparation of solid dispersions such as fusion or solvent technique are somewhat limited. The method of mechanical activation analogous to that which is employed in the mechanical alloying method may be used in preparation of dispersions of organic solids. In this paper, the method of mechanical activation is applied to obtain a solid-state dispersion of sulfathiazole in polyvinylpyrrolidone. The mechanical treatment of sulfathiazole with polyvinylpyrrolidone in a planetary ball mill transfers crystalline drug into amorphous state, the process being accompanied by formation of hydrogen bonds of sulfathiazole with matrice. The apparent solubility and rate of solvation of sulfathiazole were greatly increased if it was previously mechanically treated with polyvinyl -pyrrolidone. The release of sulfathiazole from solid dispersions with polymer to drug ratio of 1:3, 1:1, 3:1 was examined, a polymer to drug ratio of 3:1 gave the highest solubility.     

机械加工系统动态响应控制的研究

根据机械加工系统的动态响应，提出并将四自由度（４ＤＯＦ）机械系统传递函数φ０（ｓ）的２８个关系式简化为１２个关系式，且研制了１—４ＤＯＦ机械系统传递函数φ０（ｓ）新的简化应用软件。然后经机械系统φ０（ｓ）复合控制系统Ｗ０（ｓ）的计算机辅助设计，和计算机寻优中间参数Ｋｏｐｔ，得到了一个新的串联校正函数Ｇ（ｓ）＝ｆ［φ０（ｓ）、Ｋｏｐｔ、Ｗ０（ｓ）］。文中重点分析讨论了在人为扩大测试误差达３～３０％所得的不同的φ０（ｓ）情况下，寻优中间参数Ｋｏｐｔ范围，使Ｇ（ｓ）结果几无影响。最后以实例提出了相应的Ｇ（ｓ）的电路网络图．经过模拟仿真和数字仿真，结果表明加工跟踪调节时间由０．０６ｓ减为０．０２ｓ；机械加工振动位移量从０．３２９ｍｍ减小到０．０７μｍ，Ｇ（ｓ）也优于美国ＩＴＡＥ准则的ＰＩ校正，比其小３～４个数量级。     

机械系统动态优化设计的灵敏度分析法

本文用变分法理论,统一给出了机械系统动态优化设计中需要的伴随方程、末端条件和灵敏度系数公式。方法统一,形式规范。最后给出了两个实例计算。     

Dependability analysis of a very large volume neutrino telescope

This work considers a first order approximation to the dependability analysis of complex large scale installations. The dependability criterion used here is quantitative unavailability, and an appropriate unavailability model is presented. The model assumes that the system is symmetrical, has various levels of hierarchy, and components found in the same level are similar and function independently.The application example comes from very large volume neutrino telescopes installed under water or ice, consisting of several thousands of optical modules. The readout architecture of the detector has several levels of multiplexing including optical detection towers, branches and tower sectors. The paper presents results for various alternative detector layouts and distances of the detector from the onshore facilities. It also develops dependability requirements for major components and/or subsystems consistent with an overall system performance target. The results depict the dependence of the system unavailability on the number of optical modules and the alternative deep sea infrastructure configurations for transferring the measured signals.     

Dependability analysis of systems modeled by non-homogeneous Markov chains

The case of time non-homogeneous Markov systems in discrete time is studied in this article. In order to have measures adapted to this kind of systems, some reliability and performability measures are formulated, such as reliability, availability, maintainability and different time variables including new indicators more dedicated to electrical systems like instantaneous expected load curtailed and the expected energy not supplied on a time interval. The previous indicators are also formulated in the case of cyclic chains where asymptotic results can be obtained. The interest of taking into account hazard rate time variation, is to get more accurate and more instructive indicators but also be able to access new performability indicators that cannot be obtained by classical methods. To illustrate this, an example from an Electricité De France electrical substation is solved.     

Some Mechanical Characteristics of Structural Steels of Cooling Systems of Continuous Operation

Strength of Materials - The results of experimental research of low temperatures influence on mechanical characteristics of structural steels of long-term operation in chemically aggressive...     

含形状记忆合金智能材料系统的力学分析与设计研究

评述了含SMA智能材料系统的几个基础性的力学问题,包括本构关系、内耗和阻尼特性、力学分析方法、设计和最优设计等问题。结合已有的成果指出了有价值的研究内容。     

超支化聚合物/环氧树脂体系的固化行为及性能

利用傅立叶变换红外光谱(FT-IR)法研究了脂肪族聚酯型超支化聚合物/环氧树脂/酸酐固化体系的固化反应,并研究了不同代数及含量超支化聚合物对固化产物力学性能的影响。结果表明,超支化聚合物的引入能促进体系中酸酐基团的开环并产生游离羧酸,从而对体系的固化反应产生促进作用。较低含量超支化聚合物的引入即能较好地改善固化产物的力学性能,其中第三代HBP含量为3%时,固化物的拉伸强度提高20.54%、冲击强度提高71.14%、断裂伸长率提高41.02%。     

一类力学控制系统的齐次结构与局部能控性

利用力学控制系统的仿射联络模型的内在几何齐次结构和李代数结构,研究了系统的短时间局部能控性,其中,系统的拉格朗日函数取为系统的动能。证明了单输入力学控制系统在零速度点是短时间局部能控的充分必要条件是系统位形流形的维数为1,并且将这一结论推广到迷向耗散的单输入力学控制系统上。