新型的重力无源导航系统

针对重力无源导航的特点,提出了一种由速率方位惯性平台、重力传感器、重力图、深度计和相对计程仪组成的新型重力无源导航系统,给出了速率方位惯性平台系统的导航算法、重力无源导航系统的最优滤波器、误差状态方程和测量方程.考虑到运动载体上重力传感器的输出特性,在最优滤波器的重力观测方程中引入了厄特弗斯效应.应用Matlab/Simulink工具对此重力无源导航系统进行了计算机仿真研究,仿真结果表明此重力无源导航系统的平台姿态角误差和定位误差小,能够满足水下运载体长期高精度导航的要求.又由于本系统采用了速率方位惯性平台,且把重力敏感器置于其上,省去了重力仪,所以与现有的重力无源导航系统相比成本较低.     

最小二乘法对地球内部物理特性的模拟

压强、密度及重力加速度是地球内部物质的最重要的物理参数,而“初步参考地球模型”（PREM）给出了这些物理特性的一些具体数值．通过运用最小二乘法拟合PREM数据,得到了地球内部压强、密度及重力加速度随半径变化的具体函数关系式．这些准确无误、简单明了的函数关系式为更深入的科研工作提供了方便．     

中国古代的比重与流体知识

中国古代对物质比重与流体的认识经历了从定性到定量的过程.《九章算术》等古代数学典籍记载了一些物质的比重值及收录了一些与比重有关的算题.古人以“势”来描述那些能浮于水面的物体的本性,并利用水能使“有势”的物体负载重物的性质设计了各种水上运输和交通工具等.古人还利用水的流量与时间的正比关系,设计了重要的计时仪器———漏刻.     

大坝与坝基稳定性分析研究

大坝与坝基的稳定一直是工程师密切关注的一个安全问题. 论文提出2种分析重力坝和坝基稳定的方法: 一种是基于刚体极限平衡原理的直接分析方法, 它将坝体和岩基作为不变形的刚体, 利用该方法可直接计算出可能滑动面的安全因数; 另一种是基于弹塑性理论的间接分析方法, 它采用非线性有限元方法分析大坝和坝基的应力和变形. 根据收敛和突变准则来确定稳定安全度.结果表明:工程建筑物的破坏不仅仅是由于施加荷载的原因,同时也与组成材料的性质有关.     

基于小波方法微重力预混V形火焰不稳定性分析

着重介绍了将小波图像处理方法运用于微重力燃烧实验, 通过对预混V形火焰的动态图像的分析处理, 提取有关燃烧火焰的结构及其变化信息, 实现了利用火焰连续的动态图像研究火焰结构和不稳定性的目标.     

基于客货运量的新疆城市等级体系分析

应用集中系数、区域非均衡系数、改进的重力模型对客货运量分别进行评价,并通过定性的方法对结果进行修正,得出结论:(1)新疆城市客货运的集中程度差异明显;(2)新疆客货运输的节点不一致,呈现出不同的变化趋势;(3)目前新疆基本形成以乌昌地区为中心,以"奎屯-乌苏"双核城市和喀什为次中心,以石河子、博乐、库尔勒、阿克苏、阜康为区域中心,其他城市为区域次中心的城市等级体系.     

对重力做功特点推导的改进

对高中物理“重力做功的特点”一节的推导过程做改进，突出重力的分力在不同路径上所做的功的总重相等这一得要特征。     

同层均匀物体的引力势

计算了密度同层均匀分布的球体和无限长圆柱体的引力势分布     

Algorithm for 2D irregular-shaped nesting problem based on the NFP algorithm and lowest-gravity-center principle

INTRODUCTION 2D irregular-shaped nesting problem is the problem of finding an efficient arrangement for pieces in a containing region without overlapping (Fig.1), and is aimed at maximizing use of material. Nesting problem is of great interest to garment, paper, ship building, and sheet metal industries since small improvement of layout can lead to large savings in material. Many effective solutions have been pro- posed for the case when pieces and containing region are both rectangular. …     

Students' Understandings of Gravity in an Orbiting Space-Ship

We report on an investigation of students' ideas about gravity after a semester of instruction in physics at university. There are two aspects to the study which was concerned with students' answers to a carefully designed qualitative examination question on gravity. The first aspect is a classification of the answers and a comparative study of the ways the problem was tackled by two large groups of students who had different backgrounds in physics and were exposed to different teaching styles. The second aspect is to investigate how students link concepts to solve the problem. We used a phenomenographic analysis of student responses to extract patterns of reasoning and alternative conceptions behind the solutions. We found no differences between the classes of answers given by students in the two courses. Our analysis also identifies a hierarchy in the complexity of the hypothetical reasoning pathways, which we interpret as reflecting the ways in which students may link concepts and resolve conflicts as they solve the problem. The hypothetical reasoning pathways may help educators to develop instructional material or lecture room dialogue in order to tease out key issues. An unexpected finding is that there is a discrepancy between our conclusion that the two groups of answers are similar and the distribution of marks awarded by the examiner – which implies that the quality of the answers is different for the two groups.