Finite element modelling of skeletal muscles coupled with fatigue

In this study, Hill's muscle theory coupled with fatigue was proposed to describe mechanical behaviours of skeletal muscles. The force developed by a fatigued muscle was described by a muscle fatigue formula which was a time function of the activation α_a and the stretch λ. The modified Hill's muscle theory was hence incorporated into a three-dimensional (3D) finite element model using the PAK finite element code. In this paper, the theoretical derivation of the 3D muscle model was firstly described. After presenting the method of establishing the finite element programme, a case example of studying the mechanical response of a frog gastrocnemius muscle was used to illustrate the applicability of the proposed methodology. The effects of the muscle fatigue on the deformation as well as the stress and strain distribution of the frog muscle subject to a cyclic activation function have been determined. An experiment capturing the real-time shape change of a frog muscle was also conducted to assess the applicability of the proposed method. A comparison between the deformed shapes of the predictive model and the frog muscles was also made. It was shown that the method is capable of providing a reasonable model for describing the mechanical behaviour of skeletal muscles.     

塑料合金高弹性联轴器试验台的开发研究

对塑料合金高弹性联轴器的综合性能试验台进行了设计，阐述试验台的设计要求、设计思想和结构特点，并介绍试验台的总体布局和组成部分；液压系统是试验台的核心部分，重点对液压系统进行设计及说明。     

黑板型信息融合专家系统在水环境监测中的应用

现代水环境监测系统是一个具有现代高性能、多层次的复杂系统,这要求多个(种、异质)传感器在不同尺度上对水环境进行观测。探讨和分析了信息融合技术应用于水环境监测的特点,提出了一种运用专家系统和黑板理论的水环境监测信息融合结构框架。     

岩石液压致裂中几个问题的研究

论证了流体压力变化与岩石强度变化之间的关系，阐述了流体保持与释放的应力条件和构造环境，总结了两种围岩下的液压致裂模型及其流量方程。     

低频UWB SAR的冲击响应函数

提取系统的冲击响应函数(impulse response function,IRF)是测量雷达系统性能指标的前提,IRF来自理想点目标的雷达图像。对于低频超宽带合成孔径雷达(ultra wide band synthetic aperture radar,UWB SAR),参考点目标的电磁散射特性是频率和方位角的函数,不满足理想点目标的散射特性要求。本文从IRF的定义出发,结合低频UWBSAR系统处理模型,利用二维数字聚焦方法消除杂波的影响,同时利用低频电磁散射数值建模的方法计算参考点目标的电磁散射特性,最后给出了计算系统IRF的方法。     

聚醚多元醇钻井液研制及应用

以新研制的多功能聚醚多元醇SYP-1为主剂,对聚合物包被剂、防塌剂和降滤失剂进行了优选实验.在此基础上,研制了一种新型的聚醚多元醇钻井液.对聚醚多元醇钻井液的抑制性、流变性、滤失造壁性、润滑性以及对油气层的保护性能进行了室内评价实验,并分析了该钻井液的作用机理.在LN3-6H井和HD4-23H井进行的聚醚多元醇钻井液现场试验表明,在钻进过程中井壁稳定,井径规则,起、下钻畅通,井下安全,测井、下套管及固井作业顺利.室内实验和现场应用表明,聚醚多元醇钻井液具有优良的防塌性和润滑性,能有效地抑制岩屑分散,起到稳定井壁和保护油气层的作用,满足复杂地质条件下钻井的需要.     

Characterizing the deformation behavior of Tertiary sandstones

Tertiary sandstones possess deformational behavior different from hard rocks, especially the relatively larger amount of volumetric dilation during shearing. Such excess dilation contributes to the increase of crown settlement during tunnel excavation and accounts for several cases of tunnel squeezing within Tertiary sandstones. Therefore, the deformation behavior of Tertiary sandstones sampled from more than 13 formations was studied. To distinguish the volumetric deformation induced by hydrostatic stress or by shear stress as well as to decompose the elastic and the plastic components of strains, special experimental techniques, including pure shear tests and cycles of loading–unloading were applied.The experimental results reveal that the deformation of Tertiary sandstone exhibits the following characteristics: (1) significant amount of shear dilation, especially elastic shear dilation; (2) non-linear elastic and plastic deformation; (3) plastic deformation occurs prior to the failure state. Furthermore, features of plastic deformation were inferred from experimental results and, as a result, the geometry of plastic potential surface and the hardening rule were accordingly determined. A constitutive model, involving nonlinear elastic/plastic deformation and volumetric deformation induced by shear stress, is proposed. This proposed model simulates the deformational behavior for the shear-dilation-typed rocks reasonably well. Furthermore, tests on the versatility of the proposed model, including varying hydrostatic stress and stress paths, indicate that the proposed model is capable of predicting deformational behavior for various conditions.     

Continued fraction for formal laurent series and the lattice structure of sequences

Besides equidistribution properties and statistical independence the lattice profile, a generalized version of Marsaglia's lattice test, provides another quality measure for pseudorandom sequences over a (finite) field. It turned out that the lattice profile is closely related with the linear complexity profile. In this article we give a survey of several features of the linear complexity profile and the lattice profile, and we utilize relationships to completely describe the lattice profile of a sequence over a finite field in terms of the continued fraction expansion of its generating function. Finally we describe and construct sequences with a certain lattice profile, and introduce a further complexity measure.     

立足于实际的数字系统级诊断

本文主要提出了一个立足于当前实际的系统级诊断模型。在这模型下，系统级诊断变得很容易。模型基于下列假定：将系统划分成既具有自测试又具有测试其它单位能力的一种单位；其测试能力和测试结果用模糊数学来描述；自测试时在各种情况下均能给出正确的结果；测试其它单位时，除测试者本身具有严重故障外，也均能给出正确结果。     

应力腐蚀试验机数据处理系统

本文介绍了ＧＹＦ－３０低应变速率腐蚀试验机数据处理系统的原理及系统设计。