NTFS文件系统的研究

通过与FAT文件系统的比较，分析了NTFS文件系统在磁盘上的结构，并用具体实例研究了NTFS最重要的主文件表MFT元文件。     

嵌入式Linux根文件系统的构建与分析

Linux系统移植主要包括bootloader的移植、内核移植、根文件系统的移植等三大部分。在基于Linux的嵌入式系统的构建过程中,根文件系统是不可缺少的重要组成部分。重点对利用busybox构建根文件系统的过程进行了详细的讲解,包括busybox的配置过程,根文件系统的构建过程,Web服务器BOA的构建过程,网络视频服务器MJPG-streamer的构建过程,NFS挂载根文件系统的测试过程,以及三种文件系统Cramfs、JFFS2及Ramdisk的制作过程,将几种不同的文件系统的性能进行了对比分析。实验表明制作完成的三种文件系统能够正常使用,并且运行稳定。     

TB级存储系统测试及分析报告

通过调研国际上流行的商用和免费文件系统测试工具等，最终选定使用bonnie，bonnie＋＋，Iozone作为文件系统的串行测试工具；由于并行测试工具都是商用产品，研发了自己的并行测试程序。该程序是在研究串行Bonnie源程序的基础上，使用标准的并行编程语言MPI来实现的，见图1。     

一种基于STM32的NAND flash的块分配框架设计

STM32对大容量数据文件存储与管理问题可通过NAND flash来解决。而NAND flash的高效管理需要文件系统参与。NAND flash有特殊的块读写及擦除机制,一般的嵌入式文件系统组织结构并不完全兼容NAND flash。针对NAND flash的特点兼顾STM32的资源承受力要提出新的NAND flash块分配框架,框架通过块分配槽这种数据结构,在不使用块分配表与垃圾表的情况下,实现了NAND flash均衡负载与垃圾块的回收;同时通过节点分配栈与文件节点表的配合来提高STM32对文件的读写速度,空间利用率和系统性能。仿真实验和计算结果表明该块分配框架可有效提高NAND flash块的均衡负载与节省RAM空间。     

基于STM32的NAND flash的块分配框架设计

STM32对大容量数据文件存储与管理问题可通过NAND flash来解决;而NAND flash的高效管理需要文件系统参与;NAND flash有特殊的块读写及擦除机制,一般的嵌入式文件系统组织结构并不完全兼容NAND flash;针对NAND flash的特点兼顾STM32的资源承受力要提出新的NAND flash块分配框架,框架通过块分配槽这种数据结构,在不使用块分配表与垃圾表的情况下,实现了NAND flash均衡负载与垃圾块的回收;同时通过节点分配栈与文件节点表的结合来提高STM32对文件的读写速度,空间利用率和系统性能;仿真实验和计算结果表明该块分配框架可有效提高NAND flash块的均衡负载与节省RAM空间。     

基于嵌入式系统的TCP简化实现方法

介绍一种针对中小型嵌入式系统的TCP简化实现。该TCP的实现假定没有操作系统的支持，即：(1)仅使用mbuf模块提供的缓冲区管理功能；(2)基于单任务、单进程的8位／16位／32位处理器；(3)硬件可提供输入中断和时钟中断；(4)没有文件系统。(5)代码短小，以节省ROM空间；(6)使用较少的数据，以节省RAM空间；(7)假定连接对端不跨越路由器；RFC1122定义了TCP／IP实现的兼容性建议。对RFC1122的需求做了裁减。     

基于Windows NT平台的光盘阵列的设计

光盘阵列在多媒体系统等巨量存储领域具有广泛的应用前景。提出设计基于ＷｉｎｄｏｗｓＮＴ平台的光盘阵列的方法。此方法采用分层结构,将整个光盘阵列的实现分为文件系统驱动程序、阵列过滤器驱动程序、光盘驱动器分类驱动程序、ＳＣＳＩ端口驱动程序和ＳＣＳＩ小端口驱动程序五个层次,实现了模块化设计。利用此方法设计出的ＴＳ Ｏ１型光盘阵列,操作简便,实际达到的数据传输率与理论值接近     

存储技术的新突破——进化海量存储系统

本刊讯 由谢长生、曹强、吴非、谭志虎、万继光、黄建忠等人组成的“进化海量存储系统关键技术与实现方法”项目组针对海量网络存储系统，在数据组织方式和组织策略上提出了多项发明技术。针对存储系统物理和逻辑的组织方式是一种静态组织结构，不能很好地刻画处于不断变化之中的系统，提出了一种进化存储系统及其进化方法、自适应数据存储优化分布和存储设备数据再生进化方法，获得3项发明专利；还提出了一种存储系统数据分布及互转换和一种基于连续度聚类和时间序列的IO区域预取的方法，申请2项发明专利。针对数据存储安全性，提出了一种在内核态文件系统层的加密读写和一种用于存储系统的全局缓存管理的方法，申请2项发明专利。以上技术都已投入使用，从多角度提高了网络存储系统的性能，提供了多种关键技术缓解I／O瓶颈的方法。采用部分上述技术和方法形成的“采用零拷贝技术的多协议磁盘阵列控制器”为国内首款具有自主知识产权的磁盘阵列硬件控制器，并已成功应用于军用加固磁盘阵列和民用磁盘阵列系统中。     

基于Hadoop的快速并行视频处理方法

目前,基于 Hadoop视频处理的传统方法都是通过MapReduce从本地文件系统读取数据,利用帧字节流进行MapReduce间数据传输,这会产生大量的系统 IO,造成系统资源浪费。针对此问题,提出一种基于Hadoop平台的视频处理方法,实现Hadoop支持的视频类型扩展,设计了MapReduce 相关视频数据处理接口,使 Hadoop 可以更快速处理视频文件。通过在多台计算机组成的集群实验表明,该方法在运行时间上比传统方法缩短10%,IO读写量减少50%以上,提升了Hadoop视频文件的处理效率。     

航天器热试验查询统计系统的设计与实现

针对航天器真空热试验数据量大、数据利用率不高的特点,提出了一种基于数据库的试验数据查询统计方法方法,以改善现有的以文件系统为主的数据存储模式;通过对试验数据格式的分析和现有工作流程的优化,将试验数据查询系统分为系统管理、试验管理、策略管理和统计分析等四个大的功能模块,利用过滤算法自动生成试验工况点信息,并通过试验工况点自动生成单次试验的统计报告,进而实现对所有试验数据的综合查询统计功能;目前系统已应用于航天器热试验任务中,经过测试,系统功能和性能指标满足试验需求,解决了实际问题。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.