基于频繁执行路径扩展的软件胎记方法

小型程序能提取的频繁执行路径数量少,路径相对较短,程序功能相近时路径相似度高,不适于构造高可信性软件胎记。提出频繁执行路径扩展技术,通过影响分析方法,在SEQUITUR算法输出的DAG图上,查找频繁执行路径上每一节点的影响节点,把这些节点加入到路径后,形成扩展频繁执行路径。实验表明,保持扩展频繁执行路径调用关系形成的软件胎记,其可靠性不低于WPP胎记,当程序较小时,可信性高于WPP胎记。     

A New Approach for Parameter Estimation of Mixed Weibull Distribution: A Case Study in Spindle

In order to improve the accuracy and efficiency of graphical method and maximum likelihood estimation (MLE) in Mixed Weibull distribution parameters estimation, Graphical-GA combines the advantage of graphical method and genetic algorithm (GA) is proposed. Firstly, with the analysis of Weibull probability paper (WPP), mixed Weibull is identified to data fitting. Secondly, the observed value of shape and scale parameters are obtained by graphical method with least square, then optimizing the parameters of mixed Weibull with GA. Thirdly, with the comparative analysis on graphical method, piecewise Weibull and two-Weibull, it shows graphical-GA mixed Weibull is the best. Finally, the spindle MTBF point estimation and interval estimation are got based on mixed Weibull distribution. The results indicate that graphical-GA are improved effectively and the evaluation of spindle can provide the basis for design and reliability growth.     

Weibull model selection for reliability modelling

A large number of models have been derived from the two-parameter Weibull distribution and are referred to as Weibull models. They exhibit a wide range of shapes for the density and hazard functions, which makes them suitable for modelling complex failure data sets. The WPP and IWPP plot allows one to determine in a systematic manner if one or more of these models are suitable for modelling a given data set. This paper deals with this topic.     

n-fold Weibull multiplicative model

In this paper we study the n-fold multiplicative model involving Weibull distributions and examine some properties of the model. These include the shapes for the density and failure rate functions and the WPP plot. These allow one to decide if a given data set can be adequately modelled by the model. We also discuss the estimation of model parameters based on the WPP plot.     

HEVC并行解码器设计

新一代视频编码标准HEVC(High Efficiency Video Coding)主要面向高清及超高清视频编码,压缩效率相比之前的编码标准H.264有较大提高.但压缩效率的提高必然会带来计算的复杂化,为提高HEVC的解码效率,降低时延,提出了一种并行解码器架构.该并行解码器的设计是基于HEVC中熵片(Entropy slice)和波前并行处理(Wavefront Parallel Processing, WPP)技术的引入以及滤波器(Deblocking Filter)无相关性的特点.实验结果表明,该并行解码器能够充分利用硬件资源,提高解码效率.     

Models involving two inverse Weibull distributions

In this paper, we look at three models (mixture, competing risk and multiplicative) involving two inverse Weibull distributions. We study the shapes of the density and failure-rate functions and discuss graphical methods to determine if a given data set can be modelled by one of these models.     

Robust Estimation for Weibull Distribution in Partially Accelerated Life Tests with Early Failures

Maximum likelihood estimation (MLE) is a frequently used method for estimating distribution parameters in constant stress partially accelerated life tests (CS‐PALTs). However, using the MLE to estimate the parameters for a Weibull distribution may be problematic in CS‐PALTs. First, the equation for the shape parameter estimator derived from the log‐likelihood function is difficult to solve for the occurrence of nonlinear equations. Second, the sample size is typically not large in life tests. The MLE, a typical large‐sample inference method, may be unsuitable. Test items unsuitable for stress conditions may become early failures, which have extremely short lifetimes. The early failures may cause parameter estimate bias. For addressing early failures in the Weibull distribution in CS‐PALTs, we propose an M‐estimation method based on a Weibull Probability Plot (WPP) framework, which leads a closed‐form expression for the shape parameter estimator. We conducted a simulation study to compare the M‐estimation method with the MLE method. The results show that, with early‐failure samples, the M‐estimation method performs better than the MLE does. Copyright © 2015 John Wiley & Sons, Ltd.     

聚丙烯蜡对纸张表面疏水性的影响

用改性聚丙烯蜡(MWPP)乳液与羧基丁苯胶乳共混,将复合乳液应用于纸张表面施胶,研究不同改性的MWPP及其含量对纸张表面疏水性能的影响。利用偏光显微镜、原子力显微镜(AFM)和接触角测量仪测试丁苯-MWPP复合胶膜的表面性能。结果表明,MWPP在复合胶膜表面形成"海岛型"突起结构;当MWPP含量由0增加到5%时,复合乳液涂布的白纸板的表面水接触角从65.35°提高到114.83°;胶膜厚度对复合胶膜表面水接触角和表面能影响不大。