网民政策态度形成机制研究——从"网议宁波"说起

近期,网民对一些公共政策多持否定态度,本文所引用的宁波公务员错时工作政策的案例即是如此.网民认为该政策是对公务员"新的隐形福利",公务员则认为是公众误读政策.本文运用扎根理论,通过分析网民的网上投票和评论帖,归纳出以网民为代表的公众政策态度形成机制;并采用社会分层理论和相对剥夺理论揭示形成这种政策"误读"的深层原因,提出"政策认知定势"和"政策沉淀"概念,以解释特定政策背景下公众对政策的认知模式.     

计算机编程在医学物理实验《转动惯量的测量》中的应用

通过对复杂的转动惯量计算过程进行程序化,并且利用条件判断实现对实验环节差错的识别,增强了学生对医学物理实验的兴趣,减轻了教师负担,提高了教学效率和效果,培养了学生解决实验问题的能力.     

Optimal design of Stewart platforms based on expanding the control bandwidth while considering the hydraulic system design

We proposed an optimal design method to expand the bandwidth for the control of large hydraulic Stewart platform. The method is based on generalized natural frequency and takes hydraulic oil into consideration. A Lagrangian formulation which considers the whole leg inertia is presented to obtain the accurate equivalent mass matrix. Using the model, the effect of leg inertia and the influence of design parameters on the generalized natural frequency are investigated. Finally, numerical examples are presented to validate and confirm the efficiency of the mathematical model. The results show that the leg inertia, especially the piston part plays an important role in the dynamics. The optimum diameter ratio of the base to the moving platform is between 2 and 3, and the optimum joint angle ratio of the base to the moving platform is about 1. The smaller joint angles and a longer leg stroke are favorable for raising system frequencies. The system oil should be preprocessed for large platforms with a requirement for good dynamic performance.     

一种发动机液力悬置动特性研究

基于流体力学理论,研究发动机液力悬置惯性通道内阻尼力,建立一种液力悬置力学模型和数学模型,进行动特性仿真,从流体力学的角度分析了液力悬置的结构参数对其动态特性的影响。     

三线摆测量刚体转动惯量及其误差分析

本文研究了三线摆法测量刚体转动惯量的误差影响因素并对误差的来源和原因进行了分析,在此基础上对实验操作提出了一些改进的方法,以提高实验的精度。     

刚体转动惯量测量的研究

在刚体转动惯量测量实验中,利用数字毫秒计时器计时,改进测量角加速度的原理和方法,大大提高实验的精确度和效率.     

A Nonlinear Dynamical Theory of Non-Classical Plates

In this paper, a new nonlinear formulation of plates, including shear and rotatory inertia and transverse normal stress effects, is developed by means of general assumptions, of which the von Karman-type formulation and some thick plate theories are special cases. To keep the formulation fairly general, the problem addressed in this paper simultaneously includes: the effects of shear deformation according to the geometric deformation similarity of the cross-section, the rotatory inertia, and the transverse normal stress. The three-dimensional compatible equations are applied to derive the basic equations. Numerical results are given for linear and non-linear analysis of plates. This Work was supported by the Natural Science Fundation of Shanghai for Returning Scholars     

定点转动刚体打击中心研究

从刚体定点转动的动力学方程出发，推导定点转动刚体打击中心位置的普遍表达式，并通过特例加以应用。     

利用杆模型计算圆盘转动惯量

以杆的转动惯量作为微元模型,用多种方法计算薄圆盘对过盘心且在盘面内的转轴的转动惯量．     

MEMS固体化学微推进阵列的微冲量测试技术

为了评价MEMS(Micro Electro Mechanical Systems)固体化学微推进阵列的推进性能,对其单元微冲量的精确测试显得尤为重要。在传统冲击摆的基础上,考虑微推进器推力和燃气射流冲击力之间的比例关系,设计了一套适用于MEMS固体化学微推进阵列单元微冲量的间接测试装置,并成功用于6×6规格(单元集成度为36个/cm²)微推进阵列的实际测试中。结果表明:典型实验数据下的待测微冲量为2.5442×10-4Ns,相对误差小于5%;实测8个单元的微冲量平均值为2.5574×10-4 N·s,相对偏差较小,具有很好的重复性。 