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。     

Remote sensing of spring phenology in boreal regions: A free of snow-effect method using NOAA-AVHRR and SPOT-VGT data (1982-2004)

Measurements of spring phenological dates in boreal regions using NDVI can be affected by snowmelt. This impacts the analysis of interannual variations in phenology and the estimates of annual carbon fluxes. For these two objectives, snowmelt effect must be removed from the phenological detection. We propose a methodology for determining the date of onset of greening in the 1982-2004 period using SPOT-VEGETATION (VGT) and NOAA Advanced Very High Resolution Radiometer (AVHRR) data. From 1998 onwards, the date of onset of greening is taken as the date at which the Normalized Difference Water Index (NDWI), calculated from SPOT-VGT near and short-wave infrared bands, starts increasing. This index decreases with snowmelt but increases with vegetation greening. For the 1982-2001 period, the date of onset of greening is the date at which AVHRR-NDVI equals a pixel specific threshold (PST), determined using the results of the NDWI method in the years common to the two datasets. The methods are validated using in situ measurements of the dates of leaf appearance. RMSE of 6.7 and 7.8 days, respectively, is found using NDWI-VGT and PST-NOAA methodologies, and the difference between the two methodologies in the common years is small. Very importantly, the dates are not biased. The interannual variations of the 23-year spring phenology dataset on the study area in northern Eurasia are analysed. In average over the study area, an advance of 8 days and a delay of 3.6 days are, respectively, found over the periods 1982-1991 and 1993-2004. These results confirm and complete previous studies about the greening trend, remove the uncertainty due to snow, and may improve carbon budget calculations.     

集族等价与基于粒的下近似算子研究

基于覆盖的粗集是推广经典粗集理论的方法之一,有基于元素、基于粒和基于子系统的3类定义上下近似的途径,以往大多数的文献往往从基于元素的角度出发进行定义。为了研究基于粒的近似算子特别是下近似算子的性质,借鉴格论中既约元、可约元等概念,提出了集族约简的概念。从集族约简出发,探讨了集族等价的概念与性质,并设计了集族约简的算法,得到了两个集族等价是两个集族生成相同的下近似运算的充要条件这一结果,为进一步开展一般二元关系下基于粒的近似算子的公理化方法的研究做了初步的理论方面的准备工作。     

基于结构相似性与模板校正的织物瑕疵检测方法

针对复杂的具有周期性结构的织物瑕疵检测,提出一种基于结构相似性与模板校正的织物瑕疵检测方法。通过图案的周期性,得到图案单位模板大小,再对图像自动分割,同时应用基于模板校正的方法以减少晶格之间未对准的影响,并构建均值模板。通过计算所有晶格间的结构相似性,并将相似关系通过传递闭包的方式得到等价关系,再进行晶格间的聚类。之后通过阈值分割方法,完成瑕疵区域的检测。通过实验表明,改进后的算法检测效果较好,本文算法显著提高了样本的查准率。     

模糊直方图模型的运动目标跟踪

为改善跟踪系统对跟踪场景中目标色度和光照变化鲁棒性,提出基于模糊直方图的目标模型建立方法。首先,在色度论域内定义色度模糊等级,根据模糊隶属度函数建立目标区域模糊直方图,由此降低目标直方图模型对色度等级阈值的敏感性。然后,利用模糊直方图模型进行反向投影,建立跟踪场景的概率分布图。最后,利用Camshift方法实现目标的识别、定位与跟踪。仿真实验结果表明:与传统方法相比,采用模糊直方图模型的跟踪方法对色度漂移等干扰具有更好的适应性,目标在顺光、侧光以及逆光环境下移动时,该方法能够完成目标的准确定位与跟踪,单帧平均跟踪时间与基本Camshift方法相当,单帧最大跟踪时间小于40 ms,满足电视跟踪等系统实时性要求。     

定位GSM用户的一种方法

利用GSM协议的一个缺陷,提出一个对GSM用户定位的方法.当用户使用GSM移动电话时,攻击者修改GSM移动电话和基站之间在空中接口传输的一些信令报文子域,诱使GSM移动电话向基站明文传输IMSI和IMEI身份标识符.这种攻击方法能让通信双方对攻击没有察觉,从而保证攻击的隐蔽性.攻击者根据截获的IMSI和IMEI,以及用户所属区域的LAI即可实现对用户的定位.     

基于人工鱼群算法的孪生支持向量机

孪生支持向量机（twin support vector machine, TWSVM）是在支持向量机的基础上产生的机器学习算法,具有训练速度快、分类性能优越等优点。但是孪生支持向量机无法很好地处理参数选择问题,不合适的参数会降低分类能力。人工鱼群算法（artificial fish swarm algorithm, AFSA）是一种群智能优化算法,具有较强的全局寻优能力和并行处理能力。本文将孪生支持向量机与人工鱼群算法结合,来解决孪生支持向量机的参数选择问题。首先将孪生支持向量机的参数作为人工鱼的位置信息,同时将分类准确率作为目标函数,然后通过人工鱼的觅食、聚群、追尾和随机行为来更新位置和最优解,最后迭代结束时得到最优参数和最优分类准确率。该算法在训练过程中自动确定孪生支持向量机的参数,避免了参数选择的盲目性,提高了孪生支持向量机的分类性能。     

基于分类差异与信息熵对抗的无监督域适应算法

采用对抗训练的方式成为域适应算法的主流,通过域分类器将源域和目标域的特征分布对齐,减小不同域之间的特征分布差异。但是,现有的域适应方法仅将不同域数据之间的距离缩小,而没有考虑目标域数据分布与决策边界之间的关系,这会降低目标域内不同类别的特征的域内可区分性。针对现有方法的缺点,提出一种基于分类差异与信息熵对抗的无监督域适应算法(adversarial training on classification discrepancy and information entropy for unsupervised domain adaptation, ACDIE)。该算法利用两个分类器之间的不一致性对齐域间差异,同时利用最小化信息熵的方式降低不确定性,使目标域特征远离决策边界,提高了不同类别的可区分性。在数字标识数据集和Office-31数据集上的实验结果表明,ACDIE算法可以学习到更优的特征表示,域适应分类准确率有明显提高。     

依特征频率的安卓恶意软件异常检测的研究

Android系统由于开源性和可移植性等优点,成为市场占有率最高的移动操作系统。针对Android的各种攻击也层出不穷,面向Android的恶意软件检测已成为近些年移动安全领域非常重要的一个环节。面临的问题包括恶意软件收集困难,异常样本和正常样本比例不平衡。为了有效应对上述问题,提出了Droid-Saf框架,框架中提出了一种挖掘数据隐含特征的数据处理方案;把样本特征包含的隐藏信息当作新的特征;建模时将样本特征融入算法当中,建立动态的松弛变量。应用静态分析方法反编译apk,用改进的svdd单分类器分类,克服了恶意软件检测系统中非正常软件收集困难的不足,降低了异常检测的漏报率和误判率。实验结果验证了该算法的有效性和适用性。     

PGP邮件系统核心算法分析及安全性的改进

从PGP原理入手,对PGP邮件系统的核心算法MD5信息-摘要算法、RSA数字签名算法、IDEA加密算法的原理和安全性进行了详细的研究.提出了用RIPEMD-160摘要算法代替MD5摘要算法、用基于椭圆曲线的签名算法代替RSA签名算法的技术改进.并对改进算法后的PGP邮件系统性能进行理论分析和测试,得出它们具有很高的安全性和可靠性.这样使基于PGP技术的电子邮件系统更具安全性.