电磁力诱导二次流对微流体混合效果影响的研究

设计了一种微流道中液体混合的方法, 基于电磁力的作用, 诱导微流道中二次流动 发生, 从而产生Dean涡, 使流道中流体出现往复运动及流体界面的弯曲延伸, 使不 同流体的接触面积大大地增加, 从而提高混合效率. 对3种结构的工况进行了比较. 建立了微流道混合系统的理论模型并进行了数值模拟,对流体混合过程进行了分析并对混合效率进行了评价. 进行了验证性的试验研究, 对模拟结果与试验结果进行了比较, 结果相吻合.     

挠性自适应结构振动控制的分析与实验研究

采用自适应结构的原理和方法,对压电元件用于挠性结构振动控制的一些问题进行了探讨。对压电驱动器与结构的匹配关系进行了理论分析,对模态传感/驱动器在挠性悬臂板结构中的布置方案进行了优化设计,并进行了结构的振动控制实验,从而验证了方法的有效性     

人体上肢运动学动力学建模与仿真技术的研究

根据多体动力学原理,以人体解剖学为基础,对人体上肢进行建模,推导了其动力学和运动学方程,建立了人体上肢四刚体四自由度动力学模型,运用多系统动力学软件ADAMS,结合UG建模功能,对人体上肢动力学和运动学特性进行了分析计算,对人体上肢收臂翻掌过程的运动进行了仿真,并将计算结果与实测数据进行了对比,验证了模型的正确性和有效性。     

海洋平台水动力系数识别及精度分析

论文利用新动态模型减缩方法对海洋平台结构进行自由度减缩,利用简化后的模型对水动力系数进行反演,改善了反演模型中解的不确定性,并对载荷反演中的病态问题进行了探讨,同时给出了反演结果的评估方法,为反演中测量数据的获取提供了依据,提高了反演结果的可靠性.     

建筑物周围流场格子Boltzmann仿真

基于格子BGK方程的三维15点格子Boltz-mann模型,对建筑物周围流场进行了数值仿真,对其流场的划分进行了分析,并对不同雷诺数下建筑物周围的流场进行了数值模拟计算,得到了比较满意的结果,为环境质量的评估提供了新的途径.     

聚合物粘结剂PVP、PAM和PVA结构与性能的分子动力学研究

在粉末打印骨支架的工艺中,粘结剂的性质是影响骨支架质量的关键因素。采用分子动力学的模拟方法对三种常用高分子粘结剂的体系进行了构建和模拟,从微观分子层面研究了聚合物粘结剂PVP,PAM和PVA的部分性质,比如密度、内聚能及力学性能,并对三种粘结剂的性能参数进行了比较,对其内在关系进行了揭示。此外,还通过建立粘结剂与羟基磷灰石的界面相互作用模型,对三种粘结剂与羟基磷灰石的界面结合能进行了计算和比较,分析了影响高聚物粘结特性的根本原因。这一工作不仅对常用粘结剂的基本性质进行了预估,而且对骨支架粉末粘结工艺中粘结剂的选择提供了理论依据。     

激光陀螺抖动系统振动特性的有限元分析

建立了激光陀螺抖动系统的三维有限元模型,对其振动特性进行了模态分析,并对该系统进行了模态实验测量,最后将模态分析的结果和实验测量结果进行了对比。对比结果表明,所建立的有限元模型合理,分析结果可靠,对该系统的改进设计具有重要意义。     

基于残余力向量法和改进遗传算法的结构损伤识别研究

提出了一种基于残余力向量法和改进遗传算法的结构损伤识别方法。文中首先对残余力向量法和遗传算法的基本理论进行了介绍。在无噪声的情况下,使用任意一阶模态数据,残余力向量法都能够对损伤进行准确定位。但是,振动测试数据中往往包含噪声,导致运用残余力向量法进行损伤识别完全不可行。考虑到这个问题,在常规模态分析的基础上,以节点的残余力向量构造用于遗传搜索优化的目标函数形式,然后利用改进的遗传算法重点进行了噪声条件下的结构损伤定位和定量研究。最后,本文用一个平面桁架模型进行了数值模拟,验证了所提出方法的有效性,并对方法应用中存在的一些问题进行了深入分析,得出了一些有益的结论。     

一种改进的冲量测试装置及其数据处理方法

对摆锤式片炸药比冲量测试装置及其数据处理方法进行了改进。首先,在对机械结构进行了改进设计的基础上,利用光栅测试系统测量摆动角度,并解决了测试时波形失真的问题,提高了装置的精密性和稳定性。然后,采用该装置研究了阻尼随摆动幅度的变化规律,并用实测数据进行了验证;提出了片炸药比冲量测试时的最大摆角修正方法,并进行了试验对比研究。结果表明:改进后的装置及其数据处理方法能够更加准确地测量片炸药的比冲量。     

力学科学处2010年重点项目结题审查情况的简要介绍

按照《国家自然科学基金重点项目管理办法》的有关规定:自然科学基金委应当自收到结题材料之日起90日内,组织同行专家对重点项目的完成情况进行审查. 为了促进重点项目之间的交流, 加强对比, 提高效率,数理科学部于2011年3月15日至16日在北京召开会议组织专家对2010年结题的重点项目进行了集中审查,会议采取分学科进行的方式. 力学科学处共有10项重点项目进行了结题审查(见表1).各项目负责人就研究计划的完成情况、取得的成果及水平, 以及人才培养, 国际合作与交流的成效等进行了汇报.评审专家进行了认真讨论, 形成了结题审查专家组评价意见.      

转子系统随机支撑刚度参数的识别

基于Riccati摄动随机传递矩阵方法建立的转子系统特征值与随机参数变量间的函数关系,给出了转子系统随机参数的识别方法和详细步骤,可用于识别随机参数的均值和方差。以改装的Bently实验转子为研究对象,通过大量测试,识别出了转子系统的随机支撑刚度参数,建立了该转子系统的随机参数动力学模型。该模型可用于研究转子系统的随机参数动力学问题。     

On the invariant theory of nonholonomic systems with constraints of non-Chetaev type

This paper deals with the theory of the differential invariant and integral invariant for a nonholonomic system with constraints of non-Chetaev type. It gives the restricted conditions of virtual displacement in velocity space for nonholonomic constraints of non-Chetaev type and extends the Jourdain principle and the canonical equation for the system. It presents and proves generalized Noether theorem, and gives generalized energy integral and cyclic integral for the system. Finally, the basic integral variants for the system are extended and the integral invariant of Poincaré-Cartan and the universal integral invariant of Poincaré for the system are obtained.     

广义Hamilton系统的保结构算法

基于广义Hamilton系统微分方程解析解理论。给出了构造保持系统真解典则性的高阶显式积分格式的方法,并说明其可推广到广义Hamilton控制系统。该方法保持了原系统的几何定性特征,因而是稳定的。数值例子说明了算法的有效性。     

Conditions for the existence of a complete set of real modes for a damping vibration system

In this paper, a general damping system is transformed into an equivalent undamped system according to the transformation of general coordinates for a matrix function. The necessary and sufficient conditions for the transformability are presented, which become, after supplementing another condition as suggested, the conditions for decoupling the damping matrix of a general damping vibration system. So the Caughey's condition is insufficient for determining if a damping matrix of a general system can be decoupled.     

Method of large-scale system and analysis of three-axis stability of system partially filled with liquid

In the paper the method of large-scale system is investigated. The criteria of three-axis stability of a partially liquid-filled system are obtained by means of the method of large-scale system. Numerical results are given for a liquid-filled system with three-flywheels.     

Extensions of hyperbolic systems of balance laws

An algorithm is presented for the extension of a hyperbolic system of balance laws to a system of higher dimension, in such a manner that weak solutions of the original system form a subset of the weak solutions of the extended system. Hyperbolicity and the symmetry group of the original system survive the extension, and some information on the characteristic speeds of the extended system is obtained. Applying the method to isentropic fluid flow, a new form of model for two-fluid flow is obtained. PACS 52.30.Ex, 52.35.Tc AMS Subject clssification Primary 35L65, Secondary 76T99     

Stability for manifolds of equilibrium states of fractional generalized Hamiltonian systems

For a fractional generalized Hamiltonian system, in terms of Riesz derivatives, stability theory for the manifolds of equilibrium states is presented. The gradient representation and second order gradient representation of a fractional generalized Hamiltonian system are studied, and the conditions under which the system can be considered as a gradient system and a second order gradient system are given, respectively. Then, equilibrium equations, disturbance equations, and first approximate equations of a fractional generalized Hamiltonian system are obtained. A theorem for the stability of the manifolds of equilibrium states of the general autonomous system is used to a fractional generalized Hamiltonian system, and three propositions on the stability of the manifolds of equilibrium states of the system are investigated. As the special cases of this article, the conditions which a fractional generalized Hamiltonian system can be reduced to a generalized Hamiltonian system, a fractional Hamiltonian system and a Hamiltonian system are given, respectively, and the stability theory for the manifolds of equilibrium states of these systems are obtained. Further, a fractional dynamical system and a fractional Volterra model of the three species groups are given to illustrate the method and results of the application. Finally, by using the method in this paper, we construct a new kind of fractional dynamical model, i.e. the fractional Hénon–Heiles model, and we study its stability of the manifolds of equilibrium states.     

石油钻井旋转导向实验转台测试系统设计

设计了一种实验转台测试系统,主要用于在实验室环境下验证石油钻井旋转导向工具可行性并测试其性能参数。提出了总体方案,设计并完成了系统的关键组成部分：两轴手动转台、合力测试仪、惯性测量模块、信号处理系统,完成了计算参数和姿态误差角测试实验。实验结果表明,所设计的各部分工作正常,满足系统的总体要求。这为将来石油钻井导向工具的井下实验打下很好的基础。     

Stability for manifolds of equilibrium states of generalized Hamiltonian systems

For a generalized Hamiltonian system, stability for the manifolds of equilibrium states is presented based on Lyapunov’s stability theories. Equilibrium equations, perturbation equations and first approximate equations of the system are given. A theorem for the stability of manifolds of equilibrium states of general autonomous system is used to the generalized Hamiltonian system, and three propositions on the stability of manifolds of equilibrium states of the system are obtained. Two examples are given to illustrate application of the method and results.     

Special Mei symmetry and approximate conserved quantity of Appell equations for a weakly nonholonomic system

The weakly nonholonomic system is a nonholonomic system whose constraint equations contain a small parameter. The special Mei symmetry and approximate conserved quantity of Appell equations for a weakly nonholonomic system are studied. Appell equations for a weakly nonholonomic system are established and the definition and the criterion of the special Mei symmetry of the system are given. The structure equation of the special Mei symmetry for a weakly nonholonomic system and approximate conserved quantity deduced from the special Mei symmetry of the system are obtained. Finally, special approximate conserved quantity issues of Appell equations for a two freedom degrees weakly nonholonomic system are investigated using the results of this paper.