基于FPGA的嵌入式NFS服务器的设计与实现

NFS是一种比较成熟的分布式网络文件系统,为数据存储、管理提供了良好的解决方案,一般运行在通用计算机中。随着嵌入式系统资源的不断丰富,小型、便捷、易于扩展的NFS服务器对于嵌入式平台越来越重要。采用软硬件协同设计的方法,设计实现了一个基于FPGA平台的嵌入式NFS,包括NFS服务组件、文件系统、硬盘控制器等模块。前两个模块运行在FPGA内嵌Micro Blaze处理器上,后一个模块用硬件描述语言设计实现。对设计在Xilinx的XUPV5_LX110T开发平台进行了调试验证。     

基于NFS的UNIX与Netware间数据传送

文中介绍在UNIX多用户系统与Novell网络服务器建立网络互连情况下 ,应用网络文件系统NFS使UNIX系统主机与Novell网络服务器之间实现数据的互备份。     

嵌入式Linux系统的移植及其根文件系统的实现

本文以AT91RM9200微处理器为实例,介绍了在基于ARM9核的硬件平台上构建带有根文件系统的嵌入式Linux系统的方法.简要叙述了嵌入式Linux系统的特点和组成之后,我们给出了启动加载程序U-boot的配置、Linux内核的裁剪移植、ramdisk根文件系统的制作以及应用NFS文件系统进行基本应用程序开发的方法.     

分布式网络文件系统的研究

分布式网络文件系统能够将文件资源有效整合,实现文件资源的存储与传输。首先对文件系统进行了需求分析,接着重点探讨了分布式网络文件系统的设计与实现,涉及到：文件存储与传输的设计、用户空间服务的实现以及文件视图终端的实现。     

μClinux的移植及应用程序固化方法

主要介绍了μClinux在LPC2294上的移植过程,详述了利用RAM DISK构建μClinux 根文件系统及添加应用程序的步骤,并通过测温程序验证了方法的正确性.最后介绍了在Red Hat 9中利用NFS(Net Files System) 调试应用程序的方法.本文μClinux的移植及其应用程序的固化方法已被应用于我公司自主研发的多轴运动控制系统的开发过程中.     

基于TEA加密算法在网络传输中保护文件数据安全的应用

数据在网络传输中的安全问题,是网络技术发展过程越来越值得重视的问题.TEA加密算法加解密速度快,实现简单、可靠,保证了文件在网络传输中数据的安全;使用C#语言实现可以加密任意格式和大小的文件.     

数字水印技术

1引言 随着信息技术和计算机网络的发展,越来越多的信息通过网络进行传输.网络的迅猛发展一方面促进了社会的进步和发展,另一方面又带来了许多新的问题,即版权问题和安全问题.如果一幅图片、一段影像或者语音、资料等在网上被随意复制或纂改,那就无法保护作者的权益以及所传送数据的安全了.     

电力光纤在线监测研究与应用研究

电力系统的生产安全以及正常运行要靠电力系统光纤传输网络运行的可靠性来保证.在现阶段我国电力电缆在线运行的过程中,仍然存在潜在故障难以检测以及故障处理手段滞后等问题.随着电力光缆通讯网络的大规模建设,光缆线路越来越长,网络结构越来越复杂,光缆的维护与管理问题也日渐突出.该文从电力光纤在线监测系统开发及应用的实际情况出发,提出了利用OTDR测试技术,结合GIS等相关技术,提出了一种电力系统光纤传输网络的在线监测方案.     

LINUX环境下宿主机与ARM开发板NFS服务的配置

搭建一个基于LINUX的宿主机开发环境,用交叉网线连接ARM嵌入式开发板与宿主机,通过NFS服务将宿主机的文件系统共事给开发板,以进行嵌入式开发。     

网络安全文件系统SecNFS中文件密码算法的选择与实现

当SecNFS作为安全网络文件系统使用时,文件服务器上存储的是文件的密文数据,客户端直接通过网络访问文件服务器上的文件,网络上传输的也只是文件的密文数据,所有文件数据的加／解密操作都在客户端内核中进行。每个文件都有自己的对称密钥,这个密钥使用用户的公钥加密存储在用户的访问控制文件中,用户只有通过自己的私钥解密文件密钥,才能对加密文件进行透明的读写操作。另外,对文件数据还提供完整性保护,在文件服务器或者在网络传输过程中对文件数据的任何篡改,都能被客户端察觉。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to