新课改下高中信息技术教学改革的新思路探究

在目前新课改体制下的信息技术教学,从课堂的形式上看已经趋于多样化。但是,在这种体制下,我们该如何把最新的课程观念融入到最新的信息技术课的教学中,从而营造出一个效率较高的课堂,将是一个值得探讨的问题。本文针对新课改体制下的高中信息技术教学课堂中的问题,分析了新课改体制下的高中信息技术教学的新思路。     

无需随机预言的无证书聚合签名方案

现有的聚合签名方案大多数是在传统公钥密码体制或者基于身份的密码体制提出的,都存在证书的管理问题和密钥托管问题。最近Gong等人提出聚合签名是在无证书密码体制下的。然而,他们的方案是在随机预言模型下可证安全的。在无证书公钥密码体制的基础上提出了一个无需随机预言模型下的聚合签名方案。新方案不但具有不需要数字证书同时也不存在密钥托管问题的特点,并且还满足无证书聚合签名安全需求。此外与现存的无证书聚合签名方案相比,新方案在性能上具有明显的改进。     

基于二次域的密码系统的新设计

文中结合丢番图方程和非最大虚二次阶的特点,构造了一类新型非最大虚二次阶NIQO~*,证明了在其理想类群中很容易设计可证安全的二次域密码体制.同时,通过具体构造的签名体制和加密体制,说明了这类虚二次域密码体制很容易实现,解决了此前虚二次域密码体制难以实现的问题.同时,在随机预言模型假设下证明:1)如果NIQO~*类群中离散对数问题(CL-DLP)是困难的,那么文中构造的新签名体制在适应性选择消息攻击下是不可伪造的,即达到了UF-CMA安全性;2)如果NIQO~*类群中决定性Diffie-Hellman问题(CL-DDH)是困难的,那么新加密体制在适应性选择密文攻击下是明文不可区分的,即达到了IND-CCA2安全性.     

FHE-CF:基于密文展缩的全同态密码体制设计

为了解决云环境下密文处理的问题,构造了一个基于LWE问题的全同态加密体制FHE-CF。该体制没有采用传统的基于LWE问题的全同态密码体制设计中的重线性化技术,而是利用一种新的密文展缩技术来实现噪声的有效控制。在不引入新的未经论证的安全假设的前提下,可以获得KDM安全的自举加密体制,其安全性有了突破性提高。由于其KDM安全性,可以构造循环的密钥链,实现从分层全同态到全同态的过渡。还证明了所构造的全同态密码体制是RO模型下IND-CPA安全的。除了安全性上的优势外,该密码体制效率与当前最好的全同态密码体制相当。     

无线网络协议的安全分析与测试

无线网络是目前网络发展的一个方向和趋势。借助对无线局域网802.11协议及其加密体制的安全性进行分析,从理论上得出原有的802.11协议及其加密体制存在的诸多漏洞。在Linux下对802.11协议中的WEP体制进行攻击实验的测试,尤其是注入式攻击实验,从实际上证明原有802.11协议及其加密体制的脆弱性。     

密码体制的一种统一框架与快速高效公钥系统

本文基于对称密码体制和公钥密码体制的特点,提出了密码体制的一个统一的数学框架,在该框絮下,可把对称密码体制和公钥密码体制归结为该框架下的一种特殊情形。在此基础上我们构造出快速高效的公钥密码算法,并对该算法进行了安全性和效率分析。     

一个高效的基于证书的加密方案

基于证书的公钥密码体制有效克服了基于身份的公钥密码体制和传统公钥密码体制中存在缺陷,成为一种颇受关注的公钥体制.以SK-IBE方案和ElGamal公钥加密方案作为构件,提出了一个高效的基于线对和基于证书的加密方案,并在随机预言模型下给出了安全性证明.在p-BDHI假设下,该方案被证明是IND-CBE-CCA安全的.在效率方面,该方案仅在解密时计算一个线对,因此方案的总体性能是高效的,经对比分析,优于现有的其它CBE方案.     

基于PHP技术的高校教材采发管理系统设计

教材管理水平是高校管理水平的一个重要组成,在高校教学改革中,从学年制向学分制转变的体制下,使得教材管理的难度大幅度增加。如何提高教材管理水平,是各个高校都面对的问题。本文利用PHP和MYSQL源代码的开放性和免费的特点,开发了适合学分制教学体制下高校自动化教材采发管理系统。     

一类无证书签名方案的构造方法

无证书密码体制(CL-PKC)是一类新型公钥密码体制.它保持了基于身份的密码体制(ID-PKC)不需要使用公钥证书的优点,又较好地解决了基于身份的公钥体制所固有的密钥托管问题.对无证书体制下安全高效的签名方案的设计方法的研究是受到高度关注的研究课题.文中给出了一类无证书签名方案的构造方法,并在一个很强的安全模型下对用该方法所构造的方案的安全性进行了证明.文中对新构造的方案与已有的一些同类方案的性能进行了比较.结果显示新方案在整体性能上有一定的优势.     

MHPM调制与相干解调器的仿真研究

利用有限的传输带宽获得更高的传输速率、提高信号的带宽利用率一直是通信研究的热点之一。调频体制被广泛应用于遥测、短距离传输等场合,为了获得比传统PCM/FM体制更高的带宽利用率,美国国防部使用MHPM作为ARTM Tier Ⅱ体制的选用信号。本文从MHPM信号的数学原理出发,在MATLAB环境下实现了MHPM的调制与相干解调器,并以ARTM Tier Ⅱ体制作为代表对其性能进行了仿真。仿真结果表明,ARTM Tier Ⅱ体制在误码性能和带宽利用率指标上均优于传统的PCM/FM体制。     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).     

基于Multisim8的元件模型的导入和应用

Multisim8是一款优秀仿真软件,使用该软件可对电路进行各种参数分析。我们在享受其便利的同时,也遇到因缺少元器件导致电路仿真无法进行的阻力。解决此问题的方法就是为元件建立仿真模型并新建或扩充已有的元器件库。在不熟悉Spice编程原理的情况下,我们可通过相关网址查找到元件厂商提供的元件模型,利用模型导入的方法来建立需要的新元件。通过对新元件应用电路的仿真分析,新元件完全符合要求。在此基础上,使用元件的导入与导出功能还可对新元件进行文件备份并实现新元件在不同用户间的资源共享。     

联合外形响应的深度目标追踪器

针对追踪器使用卷积网络提取出来的特征模板进行目标位置匹配时，易产生响应噪声的问题，本文提出一种联合外形响应和卷积响应的深度目标追踪方法。在当前帧中，由前一帧提供的目标信息先分别提取卷积特征和外形信息，然后获得相应的卷积位置响应和外形位置响应；最后利用外形位置响应对卷积位置响应进行修正，从而有效地抑制响应噪声。实验表明:这种方法具有较高的位置精度，能够提高目标跟踪的准确性。     

A method of defuzzification based on the approach of areas' ratio

The new method of defuzzification of output parameters from the base of fuzzy rules for a Mamdani fuzzy controller is given in the paper. The peculiarity of the method is the usage of the universal equation for the area computation of the geometric shapes. During the realization of fuzzy inference linguistic terms, the structure changes from the triangular into a trapezoidal shape. That is why the universal equation is used. The method is limited and can be used only for the triangular and trapezoidal membership functions. Gaussian functions can also be used while modifying the proposed method. Traditional defuzzification models such as Middle of Maxima − MoM, First of Maxima − FoM, Last of Maxima − LoM, First of Suppport − FoS, Last of Support − LoS, Middle of Support − MoS, Center of Sums − CoS, Model of Height − MoH have a number of systematic errors: curse of dimensionality, partition of unity condition and absence of additivity. The above-mentioned methods can be seen as Center of Gravity − CoG, which has the same errors. These errors lead to the fact that accuracy of fuzzy systems decreases, because during the training root mean square error increases. One of the reasons that provokes the errors is that some of the activated fuzzy rules are excluded from the fuzzy inference. It is also possible to increase the accuracy of the fuzzy system through properties of continuity. The proposed method guarantees fulfilling of the property of continuity, as the intersection point of the adjustment linguistic terms equals 0.5 when a parametrized membership function is used. The causes of errors and a way to delete them are reviewed in the paper. The proposed method excludes errors which are inherent to the traditional and non- traditional models of defuzzification. Comparative analysis of the proposed method of defuzzification with traditional and non-traditional models shows its effectiveness.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

一种面向查询的多文档摘要方法

面向查询的多文档摘要技术有两个难点 第一,为了保证摘要与查询密切相关,容易造成摘要内容重复,不够全面;第二,原始查询难以完整描述查询意图,需进行查询扩展,而现有查询扩展方法多依赖于外部语义资源。针对以上问题,该文提出一种面向查询的多文档摘要方法,利用主题分析技术识别出当前主题下的子主题,综合考虑句子所在的子主题与查询的相关度以及子主题的重要度两方面因素来选择摘要句,并根据词语在子主题之间的共现信息,在不使用任何外部知识的情况下,进行查询扩展。在DUC2006评测语料上的实验结果表明,与Baseline系统相比,该系统取得了更高的ROUGE评价值,基于子主题的查询扩展方法则进一步提高了摘要的质量。     

An approach to the synthesis of fuzzy stabilization systems with a priori unknown model of an object

A method of synthesis of fuzzy stabilization systems for a broad class of dynamic objects under the assumption that the mathematical model of the object is not known a priori is proposed. The control is formulated in the form of a proportional law of adjustment as a function of a macro-variable; the square of the Euclidean norm of the phase variables is adopted as the macro-variable. An analogous variable characterizes the distance of the object from the equilibrium position. Despite the simplicity of the control law, its sign remains constant due to the fact that the macro-variable is positive-definite over the entire phase space. The switching times of the signals are determined by fuzzy identification of the system’s dynamic modes on the basis of measurement of the derivatives of the macro-variable.     

CCD camera modeling and simulation

In this paper we propose a modeling of an acquisition line made up of a CCD camera, a lens and a frame grabber card. The purpose of this modeling is to simulate the acquisition process in order to obtain images of virtual objects. The response time has to be short enough to permit interactive simulation. All the stages are modelised: in the first phase, we present a geometric model which supplies a point to point transformation that provides, for a space point in the camera field, the corresponding point on the plane of the CCD sensor. The second phase consists of modeling the discrete space which implies passing from the continous known object view to a discrete image, in accordance with the different orgin of the contrast loss. In the third phase, the video signal is reconstituted in order to be sampled by the frame grabber card. The practical results are close to reality when compared to image processing. This tool makes it possible to obtain a short computation time simulation of a vision sensor. This enables interactivity either with the user or with software for the design/simulation of an industrial workshop equipped with a vision system. It makes testing possible and validates the choice of sensor placement and image processing and analysis. Thanks to this simulation tool, we can control perfectly the position of the object image placed under the camera and in this way, we can characterise the performance of subpixel accuracy determining methods for object positioning.     

一种双优选的半监督回归算法

针对一些工业过程中存在的有标签样本少，而传统的半监督学习无法保证对无标签样本准确预测的问题，提出一种双优选的半监督回归算法。首先，确定有标签样本密集区中心，并计算无标签样本与该中心的相似度，实现对无标签样本的优选，同时根据有标签样本间相似度优选有标签样本；然后，利用高斯过程回归方法对选出的有标签样本建立辅学习器，以对优选出的无标签样本预测标签；最后，利用这些伪标签样本提升主学习器的预测效果。通过数值例子以及实际脱丁烷塔过程数据进行建模仿真，证明了所提方法在有标签样本较少的情况下有良好的预测性能。