Design and Implementation of VPN Gateway Based on Linux Operating System

随着计算机网络技术的高速发展，利用广泛开放的网络环境进行全球通信已成为时代发展的趋势。但是，网络在提供开放和共享资源的同时，也不可避免的存在着安全隐患。安全问题已给网络经济造成严重的威胁，如何保护网络的安全，特别是通过网络传输的信息的安全，成为了人们关注的焦点。 目前，网络上最大的安全风险来自两方面：一方面信息在传输时被窥探或非法修改；另一方面公网对内网的非法访问和攻击。对此的解决措施主要在于加密技术和防火墙技术的应用。VPN（VirtualPrivateNetwork）网关就是一种综合以上两种技术的安全措施。VPN通过采用加密、认证、存取控制、协议封装等技术在Internet上构筑安全通道...Along with the rapid development of computer networks, global communications with Widespread. Inevitably open net environments have become the dominant trend in the future. But there are some potential security problems while the internet is providing open or shared resources. Currently security problems have threatened the so-called "net economy". How to protect the security of the internet, espe...学位：工程硕士院系专业：软件学院_工程硕士(软件工程)学号：X200523003

R&D, Human Capital, FDI and Total Productivity Factor

改革开放以来，中国经济经历了持续快速增长时期。许多学者对这种增长提出质疑，认为它是靠资本、劳动等要素的高投入、高消耗实现的，是要素驱动型的增长，因此，通过技术进步实现经济增长方式由粗放型向集约型的转变才是保持经济持续增长的根本出路。技术进步是经济增长的源泉为众多学者所证实，内生经济增长理论更是将技术进步视为经济体系的内部力量，认为它通过R&D投入和人力资本两条渠道推动经济增长，从而开辟了经济增长理论的新时代。作为衡量经济增长质量的重要指标，全要素生产率是技术进步对经济增长的综合反映，本文在内生经济增长理论的框架内，将Romer的R&D内生增长模型和Lucas的人力资本积累模型相结合，构造了内生...After reformation and opening, Chinese economy has been developing quickly and continuously for a long time. Some scholars put forward oppugning to this, and said that it was depended on high investment of capital, labor and so on, and it was driven by those factors. It is the only way to maintain economy growths that implementation economy grows way by extensive model to intensive model change by...学位：经济学硕士院系专业：经济学院经济研究所_区域经济学学号：2902009115151

A Kind of Web Spreadsheets Based on POI

互联网技术的飞速发展使得基于Web的应用越来越普遍,同时也更加复杂。基于Web的动态Excel表格就是一个典型的实例。随着开发技术的不断发展,一些开源项目凭借其公开、自由以及免费等众多优势产生了越来越大的影响,很多项目都采用了开源技术。文中介绍了一种开源的基于Java的Excel报表开发组件POI引擎,阐述了其表格显示原理。通过在Web上实现动态Excel表格,给出了一种典型应用,并结合一个实际项目中的例子进行了分析,探索出了一种开发Web动态Excel表格的方法。With the development of Internet,Web application has been more popular and complicated.Dynamic Web spreadsheets is a typical case.With the development of developing technology,some open source projects become more infective for open and free,and are implemented in many projects.This paper introduces a kind of open source implementing dynamic spreadsheets on Web based on POI engine,describes the display theory of POI.This paper gives a typical application,analyses with an example in a practical project and finds a way to develop dynamic spreadsheets.国家985二期信息创新平台项目(0000-X07204

Study of four-node rectangular spring element and its properties

弹簧元法是一种将单元离散为一系列弹簧的数值计算方法。不同的单元具有不同的离散方式,确定相应的离散弹簧的刚度系数表达式是弹簧元法的关键。将四节点矩形单元离散为6个基本弹簧,每个基本弹簧包括法向弹簧和切向弹簧两个派生弹簧,并用泊松弹簧和纯剪弹簧描述单元的泊松效应和剪切效应,用有限元的单元刚度矩阵标定各弹簧的刚度系数,实现了一种四节点矩形弹簧元的构造形式。该单元的同类弹簧具有相同的表达形式。法向与切向弹簧的刚度表达式中分别含有法向和切向弹簧刚度待定系数。通过改变待定系数的值可使该单元分别对应于有限元的常应变、双线性及Wilson非协调单元。将上述弹簧元方法进行理论推导,并应用于基于连续介质的离散单元法(CDEM)的核心计算进行简单算例验证,证明了提出方法的正确性。通过以上研究发现,四节点矩形弹簧元有以下特点:对于相同问题,不同单元有不同的计算精度;对于梁弯曲问题,应用该单元可显著提高离散单元法的求解精度;改变待定系数的值,可得到更高或者更低精度的单元

Discussion about Some Problems of Environment On-line Monitoring System

相对于传统的环境监测方式,环境在线自动监控作为一种先进技术,在环境应急反应、提高办事效率及管理水平等方面具有突出优势,但在实际应用过程中面临着在企业的推广有难度、监管方式尚需完善以及监测方法不统一等方面的问题。本文针对这些问题从管理模式、运营机制、管理方式以及监测方法等四个方面提出了相应的解决方案,以求通过这些措施的应用,确保环境自动监测系统在未来的环境管理中发挥更加重要的作用。Compared with traditional methods of environmental monitoring,environment on-line monitoring system has outstanding advantages in environmental emergency response,improve efficiency and management level.But there are some problems exist in the process of application,such as the promotion in enterprises,inadequate supervision and non-uniform monitoring methods.This article raised the corresponding measures to resolve these problems from management mode,operation mechanism,management and monitoring method and ensure environment on-line monitoring system will play a more important role in the future

Research on Image Recognition Basd on BP Neural Network

BP神经网络具有较强的容错性和自适应学习能力,因而在数字图像识别领域有着广泛的应用。本文在经典BP神经网络的基本算法的基础上,对BP算法的参数设置进行了优化,实现了一种基于分类的改进BP神经网络算法。通过探讨BP神经网络在数字图像分类识别中的应用,详细考察了各种参数对识别效果的影响。实验结果证明改进后的算法有很好的实用价值。Back-propagation neural network with high fault-tolerance and good adaptive learning ability,is found great applications in digital image recognition.This paper presents an improved algorithm through setting new parameters based on traditional BP algorithm,applies it to digital image recognition and analyzes the influence produced by improved parameters.The experimental result shows that the improved algorithm has a certain practical value.国家985二期信息创新平台项目(0000-X07204

模板法制备玻璃表面超亲水SiO2纳米柱阵列

以酸性SiO2溶胶作为涂层，通过阳极氧化铝模板压印法，在玻璃表面成功制备了规则排列的超亲水SiO2纳米柱阵列，考察了模板孔深和孔径对SiO2纳米柱阵列结构和性能的影响。结果表明，随着模板孔深的增加，长径比>10的纳米柱倾向于倒塌聚集，导致可见光透射比大幅下降；控制纳米柱长径比<10时，制备的直立纳米柱结构具有良好的透光性能，且随着模板孔径的减小，纳米柱直径减小，表面粗糙度增大，固体表面占比减小，亲水性逐渐增强。该方法可通过模板孔径调控SiO2纳米柱阵列的表面粗糙度和固体表面占比，使之呈现超亲水性和高透光性，为超亲水材料的制备提供了新的技术路线。福建省科技重大专项(2014HZ0005

Study on Corrosion Resistance of Zr-0.8Sn-1Nb-0.3Fe Alloy after Kr~+ Ion Irradiation

采用高压釜腐蚀实验研究了2种不同制备工艺下的Zr-0.8Sn-1Nb-0.3Fe合金(1#,2#)经360℃、5~25; dpa的Kr~+辐照后、在400℃/10.3 MPa过热蒸汽中的耐腐蚀性能,用透射电子显微镜(TEM)、扫描电镜(SEM)、; X射线衍射仪(XRD)分析合金腐蚀后氧化膜显微组织结构。结果表明,100; d腐蚀后,合金的腐蚀增重随着辐照剂量的增加而增加,由于1#合金中的第二相比2#合金更为细小、弥散,相同辐照剂量下,前者的腐蚀增重较低。腐蚀转折前; ,从蒸汽腐蚀侧到锆合金基体,氧化膜中的氧含量逐渐降低,靠近蒸汽侧的氧化膜主要由等轴晶形态的单斜ZrO_2组成,而基体界面处的氧化膜主要为柱状晶形; 态的四方ZrO_2和六方Zr_3O;腐蚀转折后,基体界面处的氧化膜呈"花菜"状生长,"花菜"尺寸大小与氧化膜生长速率的高低及不均匀生长趋势的大小; 呈对应关系。The corrosion resistance of Zr-0.8Sn-1Nb-0.3Fe alloys prepared by two; different processes was investigated in 400℃/18.6MPa superheated steam; by static autoclave after irradiated by 360℃ with Kr~+-irradiation of; 5~25 dpa. The microstructures of oxidation film after corrosion were; analyzed by TEM, SEM, and XRD. The results showed that the corrosion; weight-gain increased with the irradiation dose, while the weight-gain; of 1# alloy with smaller and more dispersive SPPs than 2# alloy was; lower under the same irradiation dose. Before corrosion turning, the; oxygen content in the oxidation film decreased from the steam-side to; the zirconium matrix. The oxidation film beside the steam-side was; mainly composed by equiaxied monoclinic ZrO_2 crystal, while near the; film/matrix interface by columnar quartet ZrO_2 crystal and hexagonal; Zr_3O crystal. After transition of corrosion weight, the film near the; interface grew like cauliflowers, and the size of cauliflowers were; corresponded to the growth rate and uneven growth trend of oxidation; film

Research of Artificial Neural Network Arithmetic Based on FPGA

[中文文摘]基于FPGA的神经网络实现方法已成为实际实时应用神经网络的一种途径。本文就十多年来基于FPGA的ANN实现作一个系统的总结,例举关键的技术问题,给出详细的数据分析,引用相关的最新研究成果,对不同的实现方法和思想进行讨论分析,并说明存在的问题以及改善方法,强调神经网络FPGA实现的发展方向和潜力及提出自己的想法。另外,还指出基于FPGA实现神经网络存在的瓶颈制约,最后对今后的研究趋势作出估计。[英文文摘]FPGA implementation of Artificial Neural Networks(ANNs)has been an approach of actual real-time neural network.This paper systematically reviews the progress that has been made in this research area over a decade,and lists the typical technology issues,shows detailed data analysis and newest research results,Simultaneously different implementation techniques and design are discussed,then existing problems and realizition constrains can be presented as well as improvement solutions,the development direction and potential of FPGA implement of ANN are proposed.Eventually future developments are expected.大学生创新性实验项目(2007年78号