Finding conclusion stability for selecting the best effort predictor in software effort estimation

Background: Conclusion Instability in software effort estimation (SEE) refers to the inconsistent results produced by a diversity of predictors using different datasets. This is largely due to the “ranking instability” problem, which is highly related to the evaluation criteria and the subset of the data being used. Aim: To determine stable rankings of different predictors. Method: 90 predictors are used with 20 datasets and evaluated using 7 performance measures, whose results are subject to Wilcoxon rank test (95 %). These results are called the “aggregate results”. The aggregate results are challenged by a sanity check, which focuses on a single error measure (MRE) and uses a newly developed evaluation algorithm called CLUSTER. These results are called the “specific results.” Results: Aggregate results show that: (1) It is now possible to draw stable conclusions about the relative performance of SEE predictors; (2) Regression trees or analogy-based methods are the best performers. The aggregate results are also confirmed by the specific results of the sanity check. Conclusion: This study offers means to address the conclusion instability issue in SEE, which is an important finding for empirical software engineering.     

Increasing selective pressure towards the best compromise in evolutionary multiobjective optimization: The extended NOSGA method

Most current approaches in the evolutionary multiobjective optimization literature concentrate on adapting an evolutionary algorithm to generate an approximation of the Pareto frontier. However, finding this set does not solve the problem. The decision-maker still has to choose the best compromise solution out of that set. Here, we introduce a new characterization of the best compromise solution of a multiobjective optimization problem. By using a relational system of preferences based on a multicriteria decision aid way of thinking, and an outranked-based dominance generalization, we derive some necessary and sufficient conditions which describe satisfactory approximations to the best compromise. Such conditions define a lexicographic minimum of a bi-objective optimization problem, which is a map of the original one. The NOSGA-II method is a NSGA-II inspired efficient way of solving the resulting mapped problem.     

Finding the best conic approximation to the convolution curve of two compatible conics based on Hausdorff distance

We consider the convolution of two compatible conic segments. First, we find an exact parametric expression for the convolution curve, which is not rational in general, and then we find the conic approximation to the convolution curve with the minimum error. The error is expressed as a Hausdorff distance which measures the square of the maximal collinear normal distance between the approximation and the exact convolution curve. For this purpose, we identify the necessary and sufficient conditions for the conic approximation to have the minimum Haudorff distance from the convolution curve. Then we use an iterative process to generate a sequence of weights for the rational quadratic Bézier curves which we use to represent conic approximations. This sequence converges to the weight of the rational quadratic Bézier curve with the minimum Hausdorff distance, within a given tolerance. We verify our method with several examples.     

A convenient way to incorporate semantic actions in two-pass compiling schemes

We present a simple method for connecting semantic actions to parsers. Although applicable to any kind of parser it is especially suited for LR parsers. The method is based on the idea of separating syntax analysis and semantic processing and executing semantic actions by procedures, similar to those of a recursive descent compiler. The procedures are driven by structural information about the source program, which is collected during parsing. The method is applicable to L-attributed grammars. It can be incorporated easily into any existing parser.     

A knowledge-based approach to the analysis of loops

The paper presents a knowledge-based analysis approach that generates first order predicate logic annotations of loops. A classification of loops according to their complexity levels is presented. Based on this taxonomy, variations on the basic analysis approach that best fit each of the different classes are described. In general, mechanical annotation of loops is performed by first decomposing them using data flow analysis. This decomposition encapsulates closely related statements in events, that can be analyzed individually. Specifications of the resulting loop events are then obtained by utilizing patterns, called plans, stored in a knowledge base. Finally, a consistent and rigorous functional abstraction of the whole loop is synthesized from the specifications of its individual events. To test the analysis techniques and to assess their effectiveness, a case study was performed on an existing program of reasonable size. Results concerning the analyzed loops and the plans designed for them are given     

用Verilog语言实现蓝牙系统中的加密技术

蓝牙(Bluetooth)技术是一种大家熟知的无线联网技术,是全球电信和电子技术发展的焦点,也是目前无线个域网(WPAN)应用的主流技术。但是蓝牙技术的安全问题目前还具有很多争议。本文用Verilog对蓝牙加密技术中的核心加密电路进行了描述,在经过EDA软件的仿真、综合和验证之后,在FPGA上进行了实现。结果表明,实现后的电路芯片具有较快的运算速度。     

用Verilog语言实现蓝牙系统中的加密技术

蓝牙（Bluetooth）技术是一种大家熟知的无线联网技术，是全球电信和电子技术发展的焦点，也是目前无线个域网（WPAN）应用的主流技术。但是蓝牙技术的安全问题目前还具有很多争议。本文用Verilog对蓝牙加密技术中的核心加密电路进行了描述，在经过EDA软件的仿真、综合和验证之后，在FPGA上进行了实现。结果表明，实现后的电路芯片具有较快的运算速度。     

IT真功怎样练?

从事IT行业的相对收入是比较高的。这使得了解与不了解的，热爱与不热爱的，自己选择与被迫选择的，踏实立业与投机取巧的等等各路人马都聚集在IT战场厮杀，而真正投身IT事业的志士们生存环境却非常险恶。所以，当你准备选择IT职业作为人生的新起点时，为避免壮志未酬身先死，一定要练就能在IT业持续发展的真功夫。     

Exploiting the parallelism available in loops

Because a loop's body often executes many times, loops provide a rich opportunity for exploiting parallelism. This article explains scheduling techniques and compares results on different architectures. Since parallel architectures differ in synchronization overhead, instruction scheduling constraints, memory latencies, and implementation details, determining the best approach for exploiting parallelism can be difficult. To indicate their performance potential, this article surveys several architectures and compilation techniques using a common notation and consistent terminology. First we develop the critical dependence ratio to determine a loop's maximum possible parallelism, given infinite hardware. Then we look at specific architectures and techniques. Loops can provide a large portion of the parallelism available in an application program, since the iterations of a loop may be executed many times. To exploit this parallelism, however, one must look beyond a single basic block or a single iteration for independent operations. The choice of technique depends on the underlying architecture of the parallel machine and the characteristics of each individual loop     

Regret to the best vs. regret to the average

We study online regret minimization algorithms in an experts setting. In this setting, the algorithm chooses a distribution over experts at each time step and receives a gain that is a weighted average of the experts’ instantaneous gains. We consider a bicriteria setting, examining not only the standard notion of regret to the best expert, but also the regret to the average of all experts, the regret to any given fixed mixture of experts, or the regret to the worst expert. This study leads both to new understanding of the limitations of existing no-regret algorithms, and to new algorithms with novel performance guarantees. More specifically, we show that any algorithm that achieves only $O(\sqrt{T})$ cumulative regret to the best expert on a sequence of T trials must, in the worst case, suffer regret $\varOmega(\sqrt{T})$ to the average, and that for a wide class of update rules that includes many existing no-regret algorithms (such as Exponential Weights and Follow the Perturbed Leader), the product of the regret to the best and the regret to the average is, in the worst case, Ω(T). We then describe and analyze two alternate new algorithms that both achieve cumulative regret only $O(\sqrt{T}\log T)$ to the best expert and have only constant regret to any given fixed distribution over experts (that is, with no dependence on either T or the number of experts N). The key to the first algorithm is the gradual increase in the “aggressiveness” of updates in response to observed divergences in expert performances. The second algorithm is a simple twist on standard exponential-update algorithms.     

FPGA设计中由于延迟产生的冒险现象分析及消除

在使用FPGA器件设计组合逻辑电路时，由于连线和逻辑单元的延迟作用，使输出信号出现毛刺，产生冒险现象，影响逻辑电路的稳定性。本文基于Verilog HDL，对硬件描述语言设计的组合逻辑电路中冒险现象产生的原因进行分析，介绍了通过加入采样脉冲和加入D触发器消除冒险现象的方法。并给出了实例程序、仿真波形及综合后的电路结构图。     

Finding a form to hold the act of queuing

In this paper, we present an initial appliance idea that is to reflect the practice of queuing. This is to enable exploration on how the act of queuing might evolve with new appliances and experiences. Based on the notion that a good appliance is one with limited functionality, we have worked on a limited number of excerpts from the act of queuing. By using interactional features from the field as material for design, these features are formed into the Queuing Display, which reflects issues on queuing as such.     

Finding the strongly rank-minimizing solution to the linear matrix inequality

Consideration is given to an nonstrict linear matrix inequality and associated Riccati equation that occurs on solving problems of analysis and synthesis of linear stationary discrete time systems. The strongly rank-minimizing solution to the considered linear matrix inequality also satisfies the associated Riccati equation. In this paper, a sufficient condition for finding this strongly rank-minimizing solution is represented.     

高精度汽车安全气囊最佳点火时刻预测算法

作为一种汽车的标准配备,安全气囊得到广泛使用.但是,由于安全气囊的误爆或漏爆所造成的事故却时有发生,造成不必要的人员伤亡和财产损失.为了确定汽车安全气囊的最佳点火时刻,论文将反向传播(BP)神经网络的泛化学习能力与自回归滑动平均(ARMA)模型的精确性相结合,提出了基于BP神经网络与ARMA模型的预测算法.论文给出了主要的设计及其仿真,从仿真结果看,所设计的控制算法能够很好的实现最佳点火时刻的精确预测,有助于提高汽车安全气囊的安全性能.     

将MATLAB函数转化为Visual Basic 程序可用的DLL的方法

文章详细介绍了MATLAB函数转化为VisualBasic程序可用的动态连接库（DLL）的方法,通过一个简单的例子重点介绍了编译环境的配置。算     

Four-arc approximation to ellipses: The best in general

So far, the four-arc approximations to an ellipse E are made under the condition that the major and minor axes keep strictly unchanged. In general, however, this condition is unnecessary. Then the fitting can be further improved. Considering a representative quadrant of E, we first draw two auxiliary circular arcs tangent to E at the axes but having a gap ε at their boundary, such that the small arc S lies outside the large arc L. Meanwhile the extreme errors of S and L w.r.t. E are ε and −ε respectively. Giving the radii of S and L a decrement −ε/2 and an increment ε/2 brings them to join smoothly. Thus, reducing the overall error to minimum, an analytic solution in implicit form is derived.     

A vector C and Fortran compiler for the FPS T-series: Experiences with compiling to occam I

We describe our implementation of C and Fortran preprocessors for the FPS T-series hypercube. The target of these preprocessors is the occam I language. We provide a brief overview of the INMOS transputer and the Weitek vector processing unit (VPU). These two units comprise one node of the T-series. Some depth of understanding of the VPU is required to fully appreciate the problems encountered in generating vector code. These complexities were not fully appreciated at the outset. The occam I language is briefly described. We focus on only those aspects of occam I which differ radically from C. The transformations used to preprocess C into occam I are discussed in detail. The special problems with the VPU both in terms of its (non)interface with occam I and in dealing with numerical programs is discussed separately. A lengthy discussion on the special techniques required for compilation is provided. C and Fortran are simply incompatible with the occam I model. We provide a catalogue of problems encountered. We emphasize that these problems are not so much with occam I but with preprocessing to occam I. We feel the CSP and occam I models are quite good for distributed processing. The ultimate message from this work should be seen in a larger context. Several languages—such as Ada and Modula-2—are being touted as the standards for the 1990s. These languages severely restrict parallel programming style; this may make saving dusty decks by preprocessing an impossibility.