井下减速器传动方案分析

结合井下减速器的结构特点，分析了定轴轮系传动、2K-H型行星轮系传动、3K行星轮系传动、少齿差行星轮系传动4种传动方案，选择内齿作为输出轴的少齿差行星轮系传动方案更符合涡轮钻具的传动要求和井下工具结构特点。少齿差行星轮系的研制、开发、应用可降低涡轮钻具转速，提高扭矩，提高深井钻速。     

西安地铁区间隧道通过地裂缝带的施工方案

通过对西安地铁区间隧道通过地裂缝的特点分析,提出了几种地铁区间隧道通过地裂缝的方法,指出地铁结构采用这些方法能够适应地裂缝的变形发展,并在地裂缝活动的情况下维持地面交通和地铁的正常运营。     

Analysis and design of Hermite subdivision schemes

Published online: 14 May 2002     

三峡工程明渠提前截流方案及水力学试验研究

论述了三期明渠提前截流方案的综合比较分析及截流水力学试验研究成果。认为拟定的提前截流诸方案各有利弊 ,其截流难度较初设方案显著增加。对于截流“基本方案”及“比较方案”的成功实施 ,必须辅之以一定的工程技术措施降低截流难度     

大同煤矿集团公司供水处局域网的开发和应用

介绍了大同煤矿集团公司供水处处级局域网的设计原则及开发过程，对外级局域网1年来取得的管理效果、经济效益、社会效益进行了简明的阐述。     

三元乙丙橡胶卷材在地下防水工程中的应用

地下防水工程既是一项系统工程，又是一项隐蔽工程，如何选择防水材料和控制工程质量显得到关重要。本文结合工程实例，介绍了三元乙丙橡胶卷材在地下防水工程中的应用，分析了三元乙丙卷材的特点，提出了地下水的技术方案，施工操作要求，质量过程控制要点和施工注意项，本文对三元乙丙卷材的工程应用具有指导和借鉴意义。     

Performance of compression/absorption hybrid refrigeration cycle with propane/mineral oil combination

This paper discusses the feasibility of a vapor compression/absorption hybrid refrigeration cycle for energy saving and utilization of waste heat. The cycle employs propane as a natural refrigerant and a refrigeration oil as an absorbent. A prototype of the cycle is constructed, in which a compressor and an absorption unit are combined in series. The performance of the cycle is examined both theoretically and experimentally. Although the solubility of the propane with the oil is not enough as a working pair in the absorption unit, the theoretical calculation shows that the hybrid cycle has a potential to achieve a higher performance in comparison with a simple vapor compression cycle by using the waste heat. In the experiment, the prototype cycle is operated successfully and it is found that an improvement of an absorber is necessary to achieve the good performance close to the theoretical one. The application of an AHE (absorber heat exchanger) can reduce the heat input to a generator. Further examinations on some other combinations of refrigerant/refrigeration oil and additives are desirable.     

The ponding problem on elastic membranes: an analog equation solution

 In this paper, the nonlinear response of elastic membranes with arbitrary shape under partial and full ponding loads has been analyzed. Large deflections are considered, which result from nonlinear kinematic relations. The problem is formulated in terms of the displacements components and the three coupled nonlinear governing equations are solved using the analog equation method (AEM). The membrane may be prestressed either by prescribed boundary displacements or tractions. Using the concept of the analog equation the three coupled nonlinear equations are replaced by three uncoupled Poisson's equations with fictitious sources under the same boundary conditions. Subsequently, the fictitious sources are established using a procedure based on the BEM and the displacement components as well as the stress resultants at any point of the membrane are evaluated from their integral representations. In addition to the geometrical nonlinearity, the ponding problem is itself nonlinear, because the ponding load depends on the deflection surface that it produces. Iterative schemes are developed which converge to the equilibrium state of the membrane under the ponding loads. Several membranes are analyzed which illustrate the method and demonstrate its efficiency and accuracy. The method has all the advantages of the pure BEM, since the discretization and integration is limited only to the boundary. Received 28 July 2001     

Dynamics of novel hydrogen-bonded acidic fluorinated poly(amide-imide-silica) hybrids studied by solid-state NMR

Novel hydrogen-bonded acidic fluorinated poly(amide-imide-silica) hybrid materials, FPAI-SiO₂ (6E and 6F) series, were synthesized by a sol-gel process. The structures and spin relaxation of the hybrids were characterized by infrared (IR), and ²⁹Si and ¹³C nuclear magnetic resonance (NMR) spectroscopy. The abundant Q⁴ structures implied that in free catalyst the degree of condensation of tetramethoxysilane was enhanced by hydrogen-bonded acidic fluorinated poly(amide-imide). The dynamics on the local mobility of the hybrids was investigated by the time constant for energy exchange between ¹H and ²⁹Si spin system (T_SiH) and spin-diffusion path length (L) measurements. It was found that the faster T_SiH of 6E and 6F hybrids compared with the previous study of similar 6C and 6D hybrids implied that 6E and 6F hybrids had more aggregated structures even though the organic terminal segment changed from rigid imide to more flexible amide. The interactions of the charge transfer between donor and acceptor molecules or π-π aromatic stacking may be the dominant factors to affect the structures of 6E and 6F hybrids. Moreover, M¹ and D² segments of 6F hybrids had the same level mobility and the mobility of the 6F hybrids was little improved as the soft and flexible 1,3-bis(3-aminopropyl)-tetramethyl-disiloxane segment was incorporated in the dense structures of 6F hybrids. All of the L values of 6E and 6F hybrids were on the scale of 3.5-4.0 nm. The result also suggested that 6E and 6F hybrids had similar denser structures as 6D hybrids.     

基于数字签名方案的口令鉴别方案

本文在广义ＥｌＧａｍａｌ型签名方案上建立了许多口令鉴别方案，并且提出了文［１］的三个改进方案。利用这些方案，计算机系统不仅能监测和控制口令的使用，而且可以抗击许多对口令的伪造攻击。