Dynamics of Flexible Multibody Systems Using Virtual Work and Linear Graph Theory

By combining linear graph theory with the principle of virtualwork, a dynamic formulation is obtained that extends graph-theoreticmodelling methods to the analysis of flexible multibody systems. Thesystem is represented by a linear graph, in which nodes representreference frames on rigid and flexible bodies, and edges representcomponents that connect these frames. By selecting a spanning tree forthe graph, the analyst can choose the set of coordinates appearing inthe final system of equations. This set can include absolute, joint, orelastic coordinates, or some combination thereof. If desired, allnon-working constraint forces and torques can be automaticallyeliminated from the dynamic equations by exploiting the properties ofvirtual work. The formulation has been implemented in a computerprogram, DynaFlex, that generates the equations of motion in symbolicform. Three examples are presented to demonstrate the application of theformulation, and to validate the symbolic computer implementation.     

Note: A resonant fiber-optic piezoelectric scanner achieves a raster pattern by combining two distinct resonances

The resonant fiber-optic piezoelectric scanner (RFPS) benefits imaging systems with compactness and flexibility, but previously its scanning manner was limited to non-raster patterns that suffer various deficiencies (e.g., nonuniform in terms of spatial coverage and sampling time). Here, we propose a method for the RFPS to achieve a raster pattern by producing different order resonances in the two orthogonal directions. Resonant frequencies of the RFPS are deduced by the Euler-Bernoulli beam theory, and investigated by finite element method. We experimentally fabricated a prototype RFPS, measured its properties to investigate the feasibility for raster scanning, and finally demonstrated the imaging ability.     

基于“卓越计划”的运输管理学教学改革研究

运输管理学是物流工程专业核心课程之一。今依据对物流企业的调研结果,从课程定位、教材选择、课堂内容及课堂教学方法等方面进行课程教学改革研究,提出教学内容的模块化、工作项目化及驱动任务设计等环节,构建多种手段并用的课程教学体系。结果表明,教学改革充分发挥了学生的积极性和创造力,为培养出高质量的物流工程技术人才打下了基础。     

载流导体的二维温度场的分析

为分析机电设备导体中电流引起的热分布问题,建立了机电设备的简化有限元模型,对导体进行了自适应网格划分,采用有限元方法求解热导微分方程,得到导体中热分布情况,可以估算导体的形状和尺寸,为机电设备选择合适的导体提供了一种有效的设计方法。     

ITO粉的Rietveld全谱图拟合定量相分析

对ITO粉样品用Rietveld全谱图拟合法进行了定量相分析，该样品由立方晶型的In2O3和少量的四方晶系的SnO2所组成。In2O3和SnO2质量百分含量分别为94．23％和5．77％。结果表明，用Rietveld法进行了定量相分析是非常有效和准确的。     

A TDOA location algorithm based on data fusion

A new positioning method in mobile networks is presented. Based on the data fusion technology, it processes multi-layer information fusion for the location estimates achieved by the Chan algorithm, which increases mobile positioning accuracy effectively by only using measured difference of arriving (TDOA) signals. The method is simple and practical, especially when the location estimates are corrupted by the non-line-of-sight (NLOS) error. It not only has high positioning accuracy, but also reduces the location failure probability. Results from computer simulation show that the proposed method is effective in various environments. __________ Translated from Journal of Dalian University of Technology, 2005, 45(1): 138–141 (in Chinese)     

低压省煤器在电站锅炉中的应用

针对排烟损失大的问题，某些电厂在电除尘器出口加装低压省煤器，用来加热凝结水或热网补水，从而吸收烟气热量，实际测试结果表明，对于节能降耗和保证安全运行均起到了重要作用。     

关于日语方位词省略成因的探讨

在日语句子中，“场所／物体（上位）词＋方位（下位）词”是处所表述的常用形式，但在表示动作结果留存的处所意义时，往往省略下位词，而仅用上位词表达。本文就这一语言习惯进行了探讨，认为它主要依据两个条件：其一，人们对下位处所的一致认识；其二，特定的谓语动词对下位处所起到补足作用。     

PDE造型方法在复杂曲面设计中的应用

研究了偏微分方程曲面造型方法在飞机外形设计中的应用.该飞机模型的机翼具有边条,因而给曲面造型带来一定的困难.本文应用周期PDE曲面片,构造出了机身与机翼之间G1光滑拼接的过渡面.同时,用PDE方法构造出机身与前小翼及尾翼间的过渡面.实践表明,PDE方法在光滑拼接过渡面的设计中简便实用.     

某型内燃机闭环控制减振的仿真研究

内燃机自身的振动是重型军用车辆主要的振动和噪声源,对其进行有效的振动控制十分重要.但由于内燃机系统结构的复杂性,研究其振动和噪声控制比较困难.针对某型内燃机系统,采用Matlab软件的Simulink工具,建立了整个系统的动力学仿真模型,并分别对该模型进行简谐、白噪声信号扰动下的减振控制研究,控制方法采用闭环数字PI策略.系统输出转矩和转速的曲线结果表明减振具有明显的效果.