一种基于NAND FLASH的FAT文件系统的研究与实现

在研究NAND FLASH结构及特性的基础上,对NAND FLASH之上的FAT文件系统的实现进行了探讨,并运用了磨损均衡算法及坏块管理机制以延长FLASH的稳定性和使用寿命．实验结果表明,该系统具有较强的可靠性,所采用的磨损均衡算法及坏块管理机制简便有效．     

基于日志的闪存文件系统设计与实现

分析了嵌入式存储设备和文件系统的研究现状与存在问题,阐述了日志文件系统的基本原理,在此基础上设计了一个嵌入式Linux平台下适用于NAND芯片的日志文件系统,并对其主要数据结构和算法进行实现.通过描述该文件系统各模块接口、节点结构以及负载平衡和垃圾收集算法,显示出该系统相比其他同类产品具有存取速度快、芯片使用寿命长和稳定性高等优点.     

宽带材拉伸弯曲变形的理论模型

应用板弯曲理论,引入平面变形假设和横截面始终保持为平面假设,采用米塞斯屈服准则,建立了各向同性理想弹塑性金属带材的拉伸弯曲变形的一般解析分析方法和模型.它突破了基于初等梁弯曲理论建立的解析分析方法的局限性,得到了在过去同类研究中无法计算的带材厚度方向的应力和应变,实现了对带材拉伸弯曲变形过程更贴切的表征.通过以某冷轧带钢厂拉伸弯曲矫直机为算例的比较计算表明,本文所提出的带材拉伸弯曲变形的"板弯曲"模型比"梁弯曲"模型有更符合实际.     

多面函数法与移动法的加权综合模型在GPS水准中的应用

由于GPS水准的多种函数逼近模型有其使用的条件和范围，但在使用单一拟合模型逼近高程异常曲面时，不可避免会顾此失彼，使计算结果的精度和可靠性降低。为了提高似大地水准面的精度，本文提出了应用多面函数法与移动法的综合模型来逼近高程异常曲面的方法，其基本思想是：用相同的已测点的原始数据，分别采用多面函数法和移动法来逼近GPS网中未测点的高程异常值，然后在单一模型逼近结果的基础上进行加权综合。通过对实测数据的计算分析可发现，多面函数法与移动法的加权综合模型的逼近结果比单一模型的逼近结果有了较大的提高，因此可见综合模型对于局部平原地区解决GPS高程转化为正常高是有使用价值的。     

Influence of applied load on wear behavior of C/C-Cu composites under electric current

Using carbon fiber needled fabrics with Cu-mesh and graphite powder as the preform, Cu mesh modified carbon/carbon(C/C-Cu) composites were prepared by chemical vapor deposition (CVD) with C3H6 and impregnation-carbonization (I/C) with furan resin. C/C composites, as a comparison, were also prepared. Their microstructures and wear morphologies were observed by optical microscopy (OM) and scanning electron microscope (SEM), respectively. Wear behavior of C/C and C/C-Cu composites under different applied loads were investigated on a pin-on-disc wear tester. The results show that Cu meshes are well dispersed and pyrolytic carbon is in rough laminar structure. Both C/C and C/C-Cu composites had good wear properties. The current-carrying capacity of C/C-Cu composites increases and the arc discharge is hindered as the applied load increases from 40 N to 80 N. Both C/C and C/C-Cu composites had good wear properties. The mass wear rate of C/C-Cu composites under 80 N was only 4.2% of that under 60 N. In addition, C/C-Cu composites represent different wear behaviors because wear mechanisms of arc erosion, abrasive wear, adhesive wear, and oxidative wear are changing under different applied loads.     

A leveling mechanism for the platform based on booms-constraint control of aerial vehicle

In order to achieve an automatic leveling function for work platforms of aerial vehicles with mixed-booms ( MAV) in full elevating domain, an auto-leveling mechanism for the platform is pro-posed based on a control method of booms-constraint, where mixed-boom structures and elevating characteristics are considered.Three models of constraint strategies include non-constraint model, elevating constraint model and lowering constraint model, which is designed to meet the leveling re-quirements in full working extent.Through the hydro-mechatronic unified modeling, a virtual proto-type model is set up based on the auto-leveling mechanism, and leveling performances of the plat-form are studied during booms elevating to the maximum working height and extent.Simulation re-sults show that the control method of booms-constraint can realize auto-leveling of the platform under two typical working conditions, meanwhile a leveling deviation appears at the constrained point, but the platform inclination is adjusted in the permissible range.The control method does not only re-strict booms' freedom elevating to a certain extent, but also impacts the booms extending to the max-imum working range.Experimental results verify that the auto-leveling mechanism based on booms-constraint control is valid and rational, which provides an effective technology approach for develop-ment of the platform leveling of MAV.     

全站仪三角高程代替等级水准的应用研究

介绍了2种全站仪三角高程测量的方法,即传统法的三角高程和中间法三角高程,并计算得出了它们的理论精度与实际精度,并分析了这2种方法能够代替等级水准测量的可行性。     

提高沥青路面平整度的几个关键环节

介绍了摊铺机熨平板的浮动原理,分析了影响路面平整度的因素,对摊铺过程中自动找平装置的应用、摊铺机作业注意事项及关键环节进行了探讨。     

铁路隧道裂缝的变形测量

铁路隧道受到损坏，出现不同程度的裂缝、变形，将严重影响到隧道本身的使用安全，这就要求测绘人员必须根据实际情况选择合适的测量方案来满足工程的需要。结合工程实践，探讨了铁路隧道裂缝变形测量的有关问题。     

用全站仪进行三角高程测量的简易方法

简要介绍了三角高程测量的传统方法以及利用全站仪进行三角高程测量的简易方法,指出三角高程测量的简易方法大大减少了传统三角高程测量的误差来源,不仅施测速度快,而且精度高,值得推广。