基于逆问题求解的汽车操纵性能分析

采用人-车-路闭环系统操纵性能的客观评价方法，通过优化评价指标得到了双移线道路输入时驾驶员最优的预瞄时间和跟随阶数。针对原始的和经过优化的两个闭环系统，利用径向基函数神经网络建立了汽车侧向位移和其他响应之间的映射关系。将待跟踪路径输入两个训练好的神经网络，反解出汽车其他的响应，可以方便地比较两个闭环系统跟踪同一条路径时的操纵性能。仿真结果表明：这种方法能够避免由于闭环系统参数变化而跟踪不同行驶路径进而对汽车操纵性能的比较产生的不利影响；基于径向基网络的逆问题求解方法是可行的，并且具有求解精度高、运算速度快及抗干扰能力强等优点。     

Application of direct/inverse analysis to evaluate the structure integrity of concrete. Part I. Formulation for thermo-mechanical properties determination

Inverse analyses (IA) is used to model heat-flow characteristics in a continuum composed of two media. The process solves iteratively an optional number of design parameters. The solution also includes, (a) simulation of equipment and operator error due to data capture, and (b) sensitivity analysis of thermo-mechanical parameters.The analysis models test sample, which is sandwiched between a heating element and a reference material (of known thermal conductivity). This model is then validated by analysing actual thermographs recorded at the steady-state condition, the mean variation of which is subsequently used for IA.IA can then be applied in order to determine the best estimate of the thermo-mechanical properties of the sample in a particular controlled state of integrity or damage.     

Inverse method of identification for three-dimensional subsurface cracks in a half-space

A procedure is presented which is well suited for three-dimensional subsurface crack identification in a half-space through the inversion of measured surface displacements. The investigation began with the linear, forward problem of generating contour maps of surface deformation produced by a fracture of known geometry and loading which is embedded in a finite medium. The fundamental solutions for tensile and shear multipoles in a half-space provided an efficient mathematical representation of the three-dimensional fracture. The inverse problem of crack identification centers on the development of a hybrid of the Marquardt–Levenberg algorithm. Initial guesses for the constrained set of search variables were determined heuristically from the correspondences between crack geometry and loading and the resulting uplift at the free surface. Physical measurements of surface deformation were taken for a cube of transparent acrylic polyester in which a fracture was hydraulically pressurized. Displacements induced at the surface of the specimen, which were measured by laser interferometry, had a strong correlation with predictions of the computational model (coupled with a finite element discretization). Numerical tests demonstrate the robustness of the inverse methodology even in the presence of the random and systematic errors corresponding to the experimental interferometric measurements. This revised version was published online in August 2006 with corrections to the Cover Date.     

Event Reports

Eurographics '98 Conference, page 301
Eurographics '98 Awards, page 303
EG UK '98 Conference, page 304
Cover Competition Winners, page 306     

反相气相色谱法表征氟硅橡胶酸/碱性质

采用反相气相色谱法对氟硅橡胶表面的酸碱性质进行表征。通过已知酸、碱、中性12种探针分子对氟硅橡胶的表面测定，计算其表面自由能色散作用参数、酸性及碱性作用参数等一系列数据，经较为详细的分析证实：氟硅橡胶是一种两性偏酸的物质。该方法是一种简便、快速确定聚合物表面酸碱性质的方法。通过对氟硅橡胶表面酸碱性质的表征，对于探讨其增强、粘合机理、研制新型复合材料具有实际的指导意义。     

清江隔河岩库区重要滑坡预测模型的探讨

 为了掌握隔河岩库区主要滑坡体变形发展的动态和趋势，将近年来取得的安全监测资料，采用模型筛选、带权回归、参数优化及样条回归等方法，建立了有效的预测模型。     

考虑可信度的弥散度尺度效应分析

弥散度是表征含水层中介质弥散特征的重要参数, 具有尺度效应性质, 它反映了含水层介质空间结构的非均质性. 本文收集了大量国内外在不同试验尺度下和实验条件下分别运用解析方法和数值方法所得的纵向弥散度资料; 考虑各种资料数据的可信度, 将其分为Ⅰ、Ⅱ、Ⅲ级, 并以可信度为权重, 运用加权最小二乘法对纵向弥散度与试验尺度数据进行了分析. 通过给3级可信度资料赋予不同的权重, 计算出了3种权值方案(2:1.5:1、3:2:1、1:1:1)条件下纵向弥散度尺度效应的分维值, 得到不同空隙介质在不同计算方法条件下的纵向弥散度尺度效应分维值, 为弥散度参数初步估计提供依据.     

三角矩阵求逆的ASIC实现研究

通过分析上三角矩阵的求逆算法，提出了一种适合ASIC实现的心动阵列结构，并用VHDL语言对其进行描述，最后通过Synopsys的Design Compile和Cadence的NC—Sim对其做综合后仿真验证了其正确性。仿真结果表明这种并行结构能够正确计算出上三角矩阵的逆矩阵。     

Studies on Indian silk. II. Structure–property correlations

This second in a series of articles deals with studies on the structure and physical properties of five varieties of Indian silk: two mulberry (bivoltine and crossbreed) and three nonmulberry (tasar, muga, and eri). A detailed analysis of the microstructural parameters and mechanical properties was reported. Significant differences between and within the varieties with respect to microstructural parameters (crystallinity, density, birefringence, dichroic ratio, sonic modulus, etc.), as well as the effect of microstructural parameters on mechanical properties, were discussed. Some of the observations made on the inverse stress relaxation behavior of the different silk varieties were also reported. The extent of variation of these morphological parameters was found to correlate well with the mechanical properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1098–1115, 2004