浮基多刚体系统动力分析

引入浮体势流流固耦合理论和多刚体力学的凯恩方法对浮基多刚体系统进行动力分析。考虑入射规则波的影响和上部作业物体进行回转作业、升降作业的影响,建立了浮基多刚体系统的运动方程,讨论了浮基多刚体系统运动方程在三类情况下的求解途径。     

基于凯恩方程的机器人动力学递推算法

本文在凯恩动力学方程的基础上,提出了一种新的机器人动力学递推算法。这种方法直观简练,可以不经拆链就能较方便地解决带有局部闭链结构的操作手动力学问题,尤其适用于计算机编程计算。本文用这种算法对2自由度4杆机构进行了计算,列出了它的动力学公式。     

Determination of the Band Offset of GalnP- GaAs and AllnP- GaAs Quantum Wells by Optical Spectroscopy

We report the determination of band offset ratios, using photoluminescence excitation measurements, for GaInP/GaAs and AlInP/GaAs quantum wells grown by gas-source molecular beam epitaxy. To reduce the uncertainty related to the intermixing layer at heterointerfaces, the residual group-V source evacuation time was optimized for abrupt GalnP/GaAs (AlInP/GaAs) interfaces. Based upon thickness and composition values determined by double-crystal x-ray diffraction simulation and cross-sectional transmission electron microscopy, the transition energies of GalnP/GaAs and AlInP/GaAs quantum wells were calculated using a three-band Kane model with varying band-offset ratios. The best fit of measured data to calculated transition energies suggests that the valence-band offset ratio (γ band discontinuity) was 0.63 ± 0.05 for GalnP/GaAs and 0.54 ± 0.05 for AlInP/GaAs heterostructures. This result showed good agreement with photoluminescence data, indicating that the value is independent of temperature.     

Location‐dependent generalization of road networks based on equivalent destinations

Suppose a user located at a certain vertex in a road network wants to plan a route using a wayfinding map. The user's exact destination may be irrelevant for planning most of the route, because many destinations will be equivalent in the sense that they allow the user to choose almost the same paths. We propose a method to find such groups of destinations automatically and to contract the resulting clusters in a detailed map to achieve a simplified visualization. We model the problem as a clustering problem in rooted, edge‐weighted trees. Two vertices are allowed to be in the same cluster if and only if they share at least a given fraction of their path to the root. We analyze some properties of these clusterings and give a linear‐time algorithm to compute the minimum‐cardinality clustering. This algorithm may have various other applications in network visualization and graph drawing, but in this paper we apply it specifically to focus‐and‐context map generalization. When contracting shortest‐path trees in a geographic network, the computed clustering additionally provides a constant‐factor bound on the detour that results from routing using the generalized network instead of the full network. This is a desirable property for wayfinding maps.     

Thumbnail galleries for procedural models

Procedural modeling allows for the generation of innumerable variations of models from a parameterized, conditional or stochastic rule set. Due to the abstractness, complexity and stochastic nature of rule sets, it is often very difficult to have an understanding of the diversity of models that a given rule set defines. We address this problem by presenting a novel system to automatically generate, cluster, rank, and select a series of representative thumbnail images out of a rule set. We introduce a set of ‘view attributes’ that can be used to measure the suitability of an image to represent a model, and allow for comparison of different models derived from the same rule set. To find the best thumbnails, we exploit these view attributes on images of models obtained by stochastically sampling the parameter space of the rule set. The resulting thumbnail gallery gives a representative visual impression of the procedural modeling potential of the rule set. Performance is discussed by means of a number of distinct examples and compared to state‐of‐the‐art approaches.     

基于自适应神经网络的低速AUV变质心控制

为克服低速情况下舵效低的问题,研究了自治水下航行器(AUV)的变质心控制方法.通过控制布置在AUV三个惯性主轴上的三个可移动质量块的运动,改变系统的质心,进一步改变了AUV受到的流体动力,从而实现对于AUV的控制.基于Kane的多刚体动力学理论推导变质心控制AUV的4刚体9自由度动力学模型,为设计AUV变质心控制系统奠定了基础.之后基于多输入多输出(MIMO)不确定非线性系统理论,设计自适应神经网络控制系统,并用李亚普诺夫稳定理论对该系统进行了稳定性分析.仿真验证了控制方法的合理性.     

弹性连杆的动力学建模与稳定性分析

考虑连杆弹性的曲柄滑块机构为受约束刚弹耦合机械系统，采用Kane方程，将连杆弹性变形用伽辽全法离散成空间函数和广义坐标的乘积，计及轴向缩短对连杆角速度的影响，推导出弹性连杆多自由度线性参激振动方程组。应用多尺度法并结合笛卡尔坐标变换，分析连杆第一阶弯曲模态的主参激共振，获得平凡响应稳定性临界曲线，并讨论阻尼比和惯性比等参数的影响。     

基于S7-300的连铸火焰切割系统

介绍唐山中厚板材有限公司炼钢工作部的连铸机的火焰切割机与切割定尺,及采取的有效改造措施,以满足稳定生产的要求。     

利用MATLAB5.3对马氏体相变表象晶体学B-M理论的计算

利用MATLAB5 3对马氏体相变晶体学表象理论中的B M理论做了计算。结果表明 :计算值与实验值基本相符 ,偏差小于 4°。更重要的是 ,它的编程比C和FORTRAN语言要简便得多。     

直升机载雷达动力学分析及振动抑制方法研究

安装在直升机桅杆顶部的雷达需要进行轻小型设计,同时又要适应严酷的力学环境,减重与提高系统的刚性通常是一对矛盾。为了在轻小型状态下提高系统抗力学环境的能力,需要对此类雷达进行动力学分析及主动振动抑制方法的研究。文中利用 Kane 方法推导了直升机载雷达的动力学理论模型,验证了模型的正确性,求解了直升机载雷达的振动变形情况,给出了主动抑振方法,求解了抑振效果,为直升机载雷达的主动振动抑制研究提供了理论基础。