Visualizing Co-Change Information with the Evolution Radar

Software evolution analysis provides a valuable source of information that can be used both to understand a system's design and predict its future development. While for many program comprehension purposes, it is sufficient to model a single version of a system, there are types of information that can only be recovered when the history of a system is taken into account. Logical coupling, the implicit dependency between software artifacts that have been changed together, is an example of such information. Previous research has dealt with low-level couplings between files, leading to an explosion of the data to be analyzed, or has abstracted the logical couplings to the level of modules, leading to a loss of detailed information. In this paper, we present a visualization-based approach that integrates logical coupling information at different levels of abstraction. This facilitates an in-depth analysis of the logical couplings, and at the same time, leads to a characterization of a system's modules in terms of their logical coupling. The presented approach supports the retrospective analysis of a software system and maintenance activities such as restructuring and redocumentation. We illustrate retrospective analysis on two large open-source software systems.     

Effect of loss and coupling on the resonance of metamaterial:An equivalent circuit approach

In this work we establish an equivalent circuit model to analyze the resonace of the metamaterial considering the loss of the unit cell and coupling effect between them. From this model, we find that metamaterial can be divided into three categories： weak, critical and strong couplings, depending on the values of the loss and coupling strength, where the different resonant properties are presented. The physical reason of the division is whether the loss in each unit cell can be offset by energy coupling from the adjunct unit cells. Full-wave electromagnetic simulations have also been carried out to verify the equivalent circuit analysis. Our circuit analysis provides a simple and effective way to understand the coupling of the metamaterial and gives guidance for the analysis and design of the metamaterial.     

新型阻尼车轮振动特性试验与仿真方法

采用仿真与试验相结合的方法分别对3种辐板形式车轮安装新型辐板屏蔽阻尼器前后的振动特性进行分析,结果表明:在安装辐板屏蔽阻尼器后,3种车轮在整个频域范围(0~6 400 Hz)内均具有良好的减振效果;斜型辐板和双S型辐板车轮较直型辐板车轮的径向振动与1节圆轴向振动更容易发生耦合;辐板屏蔽阻尼器在有效降低3种辐板形式车轮的径向振动和0节圆轴向振动的同时,还能够减小车轮径向振动与轴向振动的耦合.由阻尼车轮的减振特性可以预测,辐板屏蔽阻尼器能够有效降低车轮的滚动噪声和曲线啸叫噪声.     

MCM划分的自组织神经网络

本文在提出一个直接和间接相联模块间相似性的表示方法的基础上，提出了一个基于自组织神经网络的性能驱动ＭＣＭ划分的神经学习方法。算法求解如何在高层设计中将功能模块分配到ＭＣＭ芯片中。算法不仅考虑了模块间的相似关系，还考虑了ＭＣＭ的版图结构；具有芯片间连线数目最少和时钟周期最短双重优化目标；能使连线尽量产生在相邻近的芯片之间；能满足时延、散热和面积约束。文中还提出了一个层次神经网络模型和面积约束下的ＭＣ     

Bars on blocks: A cellular automata model of crime and liquor licensed establishment density

Criminologists have extensively researched the problems generated by licensed establishments. Violent offending and disorderly behavior resulting from pubs, taverns, dance clubs and bars are of particular interest to this field of study. The relative density of these liquor establishments has been found to be associated with the level of violence and disorder in surrounding areas. A complex systems approach can be used to further understand the dynamic interplay between licensed establishments, violent offending and disorder, and urban planning decisions. The model presented here utilizes cellular automata as the mathematical framework to view the varying impact of liquor licensing density on crime. This study uses a sample of liquor establishments and crime data from the City of Vancouver in British Columbia. The cellular automata model incorporates transition rules which govern the change of city blocks from low-risk blocks to high-risk blocks. The results represented by a 50 × 50 cellular grid show that high-risk blocks multiply when liquor licenses are grouped. Two scenarios are presented to contrast the impact of grouping high-risk blocks which contain more liquor establishments and dispersing such blocks. A third scenario demonstrates how increasing the positive influence in a grouped scenario stops high-risk blocks from taking over the entire grid. Future iterations of this model will incorporate census data, public transportation data, land use data and entertainment districts from other cities to further analyze the effect of licensed establishments on the distribution of crime.     

Advances in Modeling and Control of Tethered Unmanned Helicopters to Enhance Hovering Performance

The hovering capabilities of unmanned helicopters can be seriously affected by wind. One possible solution for improving hovering performance under such circumstances is the use of a tethered setup that takes advantage of the tension exerted on the cable that links the helicopter to the ground. This paper presents a more elaborate strategy for helicopter control in this augmented setup, that extends previous work on the subject by the authors. Particularly, a combination of classical PID control laws, together with model inversion blocks, constitutes the basis of the new controller. Additionally, feed-forward action for counteracting rotational couplings is also taken into account. The resulting nonlinear control structure considers also a viscoelastic model of the tether which accurately reproduce the behavior of real ropes. Several simulations under artificially generated wind influences are presented to endorse the validity of the new proposed controller.     

Computer‐aided design of microstrip extracted‐pole lossy filter

In this article, computer‐aided design of a new type of microstrip lossy filter is described. The new type of lossy filter is realized by introducing resistive cross couplings into a microstrip extracted‐pole filter to achieve a flat passband. The high selectivity is achieved by introducing 2 transmission zeros using 2 extracted poles, which can be adjusted. An equivalent circuit model is established and its circuit parameters, which are useful for physical implementation of the filter, are determined in light of computer modeling. For demonstration, two 6‐pole filters centered at 2 GHz with fractional bandwidth (FBW) 6% and 20% are implemented. Experimental results, together with a theoretical comparison between different FBWs, and full‐wave electromagnetic simulation results are also presented.     

Visual task identification and characterization using polynomial models

Developing robust and reliable control code for autonomous mobile robots is difficult, because the interaction between a physical robot and the environment is highly complex, subject to noise and variation, and therefore partly unpredictable. This means that to date it is not possible to predict robot behaviour based on theoretical models. Instead, current methods to develop robot control code still require a substantial trial-and-error component to the software design process.This paper proposes a method of dealing with these issues by (a) establishing task-achieving sensor-motor couplings through robot training, and (b) representing these couplings through transparent mathematical functions that can be used to form hypotheses and theoretical analyses of robot behaviour.We demonstrate the viability of this approach by teaching a mobile robot to track a moving football and subsequently modelling this task using the NARMAX system identification technique.     

扫描图象的圆弧的定位识别算法

提出对扫描图象圆弧的定位算法。该算法分为两步：第一步对图象进行条块化,条块化就是把原图象的黑象素依据一定的条件合并若干个块;第二步就是在第一步的条件化基础上,提取候选圆弧链,进而对圆弧圆心,半径,弧的起始点和终止点进行准确定位。实验对圆弧的识别处理。     

一种基于子块图像互相关的虹膜识别方法

虹膜识别是一种新兴的生物特征身份识别方法,在场所或资源的安全控制等方面具有重要的应用价值。该文提出了一种基于子块图像互相关的虹膜识别方法。在特征提取时,把图像划分为许多子块,计算两幅虹膜图像的对应子块间的归一化相关系数,并把最小的几个归一化相关系数去除掉,然后求得剩下的归一化相关系数的均值及方差,作为两幅虹膜图像的联合特征。这能够有效地减小图像强度的局部畸变对虹膜识别的影响。为了实现模式的非线性划分,判别函数采用径向神经网络来构造。最后,进行了小样本实验,实验结果表明,这种基于子块图像互相关的虹膜识别方法是可行的。     

Multi-block Poisson grid generator for cascade simulations

High quality computational grids can greatly enhance the accuracy of turbine and compressor cascade simulations especially when time-dependent results are sought where vortical structures are convected through the computational domain. A technique for generating periodic structured grids for cascade simulations based on the Poisson equations is described. To allow for more complex geometries, the grid can be divided into individual zones or blocks. The grids are generated simultaneously in all blocks, assuring continuity of the grid lines and their slopes across the zonal boundaries. Simple geometric rules can be employed for enforcing orthogonality at block boundaries. The method results in grids with low grid distortion by allowing both, block boundaries and grid points on physical boundaries, to move freely. Results are presented for a linear turbine and a linear compressor cascade.     

Coupling-based criteria for integration testing

Integration testing is an important part of the testing process, but few integration testing techniques have been systematically studied or defined. The goal of this research is to develop practical, effective, formalizable, automatable techniques for testing of connections between components during software integration. This paper presents an integration testing technique that is based on couplings between software components. This technique can be used to support integration testing of software components, and satisfies part of the USA's Federal Aviation Authority's requirements for structural coverage analysis of software. The coupling-based testing technique is described, and the coverage criteria for three types of couplings are defined. Techniques and algorithms for developing coverage analysers to measure the extent to which a test set satisfies the criteria are presented, and results from a comparative case study are presented. © 1998 John Wiley & Sons, Ltd.     

Identification of Wiener–Hammerstein systems by a nonparametric separation of the best linear approximation

Wiener–Hammerstein models are flexible, well known and often studied. The main challenge in identifying a Wiener–Hammerstein model is to distinguish the linear time invariant (LTI) blocks at the front and the back. This paper presents a nonparametric approach to separate the front and back dynamics starting from the best linear approximation (BLA). Next, the nonparametric estimates of the LTI blocks in the model can be parametrized, taking into account a phase shift degeneration. Once the dynamics are known, the estimation of the static nonlinearity boils down to a simple linear least squares problem. The consistency of the proposed approach is discussed and the method is validated on the Wiener–Hammerstein benchmark that was presented at the IFAC SYSID conference in 2009.     

Information-theoretic framework for unsupervised activity classification

This article presents a mathematical framework based on information theory to compare multivariate sensory streams. Central to this approach is the notion of configuration: a set of distances between information sources, statistically evaluated for a given time span. As information distances capture simultaneously effects of physical closeness, intermodality, functional relationship and external couplings, a configuration can be interpreted as a signature for specific patterns of activity. This provides ways for comparing activity sequences by viewing them as points in an activity space. Results of experiments with an autonomous robot illustrate how this framework can be used to perform unsupervised activity classification.     

结合块旋转和马赛克拼图的生成式伪装方法

目的 搜索式无载体信息隐藏容量低,涉及大量载体密集传输;纹理合成无载体隐藏只能生成简单质地的纹理图像;马赛克拼图信息隐藏尽管能产生有意义图像,但需修改嵌入参数。针对以上问题,提出一种结合块旋转和马赛克拼图的生成式伪装方法。方法 将灰度图像进行圆形化并添加随机转角构建马赛克,通过随机坐标决定秘密信息的隐藏位置;在隐藏位置,根据密钥和放置位置来放置代表秘密比特串的圆形图像和施加认证转角,对于非隐藏位置则放置最接近圆形图像来掩盖秘密信息;将放置过程产生的偏差通过误差扩散分散给周围未处理像素。在提取时,结合质心旋转匹配提取秘密比特并进行转角认证。结果 采用圆形图像表达秘密信息而不涉及修改式嵌入,通过马赛克拼图产生有意义含密掩体,可通过质心旋转匹配提取秘密比特并进行转角认证。对密钥严格依赖,在遭受质量因子为50~80的JPEG压缩和随机转角攻击时,秘密信息可完整恢复,在遭受强度为8%~20%的椒盐噪声攻击时,提取信息的误码率低于5%,且对秘密信息的认证成功率均在80%以上。结论 所提方法具有较好的抗攻击能力,可抵御信道攻击且具备较高的安全性。     

广义Hough变换:多个圆的快速随机检测

以随机采样到的2个图像点及在此2点的中垂线上搜索第3个图像点来确定候选圆．当随机采样2个图像点时，通过剔除孤立、半连续噪声点减少了无效采样；当搜索候选圆的第3点时，剔除上述2种噪声点、非共圆点并给出快速确认候选圆是否为真圆的方法，尽可能减少无效计算．数值实验结果表明：文中算法能快速检测多个圆．在检测多个圆并且具有噪声的情况下，与随机圆检测算法相比，其检测速度快一个数量级．     

A320 模拟机遮光板的模块化设计与实现

提出了一种模拟机遮光板的模块化设计方法。该方法在归类系统功能的基础上,通过适当降低操作板与控制板模块间的相对依赖性连接,实现功能与结构的分离、模块的再分割以及数据在各模块间的通信,进而达到独立功能模块设计的目的。进一步,以模块间的通信为例,设计了独立的通信模块,通过加入斯密特触发器而有效抑制了由于通信乱码而致死机的频繁发生。在实际应用中,通过操作实验,证实了该模块化设计方法可大大提高模拟机遮光板通信的可靠性; 同时该方法也可用于模拟机前头顶板和中央操纵台的设计中。     

Line and circle formation of distributed physical mobile robots

The formation problem of distributed mobile robots was studied in the literature for idealized robots. Idealized robots are able to instantaneously move in any directions, and are equipped with perfect range sensors. In this study, we address the formation problem of distributed mobile robots that are subject to physical constraints. Mobile robots considered in this study have physical dimensions and their motions are governed by physical laws. They are equipped with sonar and infrared range sensors. The formation of lines and circles is investigated in detail. It is demonstrated that line and circle algorithms developed for idealized robots do not work well for physical robots. New line and circle algorithms, with consideration of physical robots and sensors, are presented and validated through extensive simulations. © 1997 John Wiley & Sons, Inc.     

A contribution to the real-time simulation of coupled finite element models of machine tools – A numerical comparison

In this paper the real-time simulation of finite element (FE) models of machine tools on a multi-processor architecture is presented. The simulation model is based on several FE component models that are connected by non-linear couplings. These couplings allow relative motions of the components in a wide range. The coupled linear FE models are decomposed at the non-linear coupling nodes and each component is solved locally. The linear structure of the components can be used for efficient simulation methods and the components can be distributed to several processors for a parallel computation. Methods that differ in numerical accuracy and stability, computational effort and real-time capacity will be presented. By means of a complex example, it will be illustrated that a parallel, stable computation can be realized time-deterministically.