软件质量度量元的理想取值区间反推技术

针对软件质量度量元理想取值区间难以确定的问题,指出在推导一个度量元的理想取值区间时,应结合特定的（用户关心的）外部质量指标进行考虑,研究并提出了基于正交设计思想的度量元理想取值区间反推技术,该技术能够量化地给出度量元的理想取值区间,初步解决了度量元质量需求定义的问题。     

Manifold splines with a single extraordinary point

This paper develops a novel computational technique to define and construct manifold splines with only one singular point by employing the rigorous mathematical theory of Ricci flow. The central idea and new computational paradigm of manifold splines are to systematically extend the algorithmic pipeline of spline surface construction from any planar domain to an arbitrary topology. As a result, manifold splines can unify planar spline representations as their special cases. Despite its earlier success, the existing manifold spline framework is plagued by the topology-dependent, large number of singular points (i.e., |2g−2| for any genus-g surface), where the analysis of surface behaviors such as continuity remains extremely difficult. The unique theoretical contribution of this paper is that we devise new mathematical tools so that manifold splines can now be constructed with only one singular point, reaching their theoretic lower bound of singularity for real-world applications. Our new algorithm is founded upon the concept of discrete Ricci flow and associated techniques. First, Ricci flow is employed to compute a special metric of any manifold domain (serving as a parametric domain for manifold splines), such that the metric becomes flat everywhere except at one point. Then, the metric naturally induces an affine atlas covering the entire manifold except this singular point. Finally, manifold splines are defined over this affine atlas. The Ricci flow method is theoretically sound, and practically simple and efficient. We conduct various shape experiments and our new theoretical and algorithmic results alleviate the modeling difficulty of manifold splines, and hence, promote the widespread use of manifold splines in surface and solid modeling, geometric design, and reverse engineering.     

一种基于概念格的软件过程改进算法

概念格是一种优良的形式化分析工具,其具有的层次性和直观性,使之广泛应用于人工智能、数据挖掘、知识提取等领域。软件过程改善是软件工业化生产的一个关键,将概念格引入到了软件过程改善研究,提出了一种基于概念格的软件过程改进方法,并做了实验分析,证明了采用此方法对软件过程的改进具有推动作用。     

水下机械手运动学逆解的一种优化解法

本文给出一种运用约束最优化的变尺度法求解Schilling水下机械手运动学逆解的方法。这种方法不仅具有牛顿方法的快速性和理想的总体收敛性，通过迭代求取H阵，不存在奇异性问题，运用惩罚函数法选取步长，保证了从任意点进行搜索，同时有效地处理了约束的存在，这种方法较其它优化算法和搜索法有明显的快速性，在PⅡ550微机上的求解实验证明此算法完全可以用在此机械手运动学的实时求解中。     

高存储效率的MAP译码器网格信息更新实现方法

本文提出一种新型的高存储效率的最大似然译码(MAP)译码器网格信息更新实现方法,该方法可以降低Turbo码译码器状态阵列计算对存储器的需求.利用该实现方法可以使得MAP译码器的前向网格信息和后向网格信息共享同一存储器,而且前向和后向的网格信息更新以及MAP译码产生的外部信息同时进行计算;因此该法可以提高Turbo译码的运算速度、降低存储器开销,进而降低Turbo译码电路实现时的硅片面积.     

Satellite-Based Energy Balance for Mapping Evapotranspiration with Internalized Calibration (METRIC)—Applications

Recent satellite image processing developments have provided the means to calculate evapotranspiration (ET) as a residual of the surface energy balance to produce ET “maps.” These ET maps (i.e., images) provide the means to quantify ET on a field by field basis in terms of both the rate and spatial distribution. The ET images show a progression of ET during the year or growing season as well as its spatial distribution. The mapping evapotranspiration at high resolution with internalized calibration (METRIC) is a satellite-based image-processing procedure for calculating ET. METRIC has been applied with high resolution Landsat images in southern Idaho, southern California, and New Mexico to quantify monthly and seasonal ET for water rights accounting, operation of ground water models, and determination of crop coefficient populations and mean curves for common crops. Comparisons between ET by METRIC, ET measured by lysimeter, and ET predicted using traditional methods have been made on a daily and monthly basis for a variety of crop types and land uses. Error in estimated growing season ET was 4% for irrigated meadow in the Bear River basin of Idaho and 1% for an irrigated sugar beet crop near Kimberly, Id. Standard deviation of error for time periods represented by each satellite image averaged about 13 to 20% in both applications. The results indicate that METRIC and similar methods such as SEBAL hold substantial promise as efficient, accurate, and inexpensive procedures to estimate actual evaporation fluxes from irrigated lands throughout growing seasons.     

匹配位置对比特流随机性的影响研究

本文阐述了IP报文标识字段比特流随机性的评价标准,通过对大量实测报文进行统计分析证明了比特流的匹配位置对随机测度值有一定影响。结果表明,标识字段比特流随机测度值随着比特流长度的增加整体上呈递减趋势。对相同长度的比特流而言,右优先比特流随机测度值普遍最高,左优先比特流随机测度值普遍最低,其它位置比特流随机测度值普遍介于两者之间。     

软件过程中的度量数据收集方法研究

度量数据收集在软件过程改善实践中起着重要作用,但是往往在研究中受到忽视。介绍了软件过程数据收集方法和技术的发展历程,提出了软件过程度量数据收集方法的评价准则,给出了一个软件过程度量数据自动收集的框架,并且列举了四种实现方法。     

Metrics and techniques for quantifying performance isolation in cloud environments

The cloud computing paradigm enables the provision of cost efficient IT-services by leveraging economies of scale and sharing data center resources efficiently among multiple independent applications and customers. However, the sharing of resources leads to possible interference between users and performance problems are one of the major obstacles for potential cloud customers. Consequently, it is one of the primary goals of cloud service providers to have different customers and their hosted applications isolated as much as possible in terms of the performance they observe. To make different offerings, comparable with regards to their performance isolation capabilities, a representative metric is needed to quantify the level of performance isolation in cloud environments. Such a metric should allow to measure externally by running benchmarks from the outside treating the cloud as a black box. In this article, we propose three different types of novel metrics for quantifying the performance isolation of cloud-based systems.We consider four new approaches to achieve performance isolation in Software-as-a-Service (SaaS) offerings and evaluate them based on the proposed metrics as part of a simulation-based case study. To demonstrate the effectiveness and practical applicability of the proposed metrics for quantifying the performance isolation in various scenarios, we present a second case study evaluating performance isolation of the hypervisor Xen.     

On indexing metric spaces using cut-regions

After two decades of research, the techniques for efficient similarity search in metric spaces have combined virtually all the available tricks resulting in many structural index designs. As the representative state-of-the-art metric access methods (also called metric indexes) that vary in the usage of filtering rules and in structural designs, we could mention the M-tree, the M-Index and the List of Clusters, to name a few. In this paper, we present the concept of cut-regions that could heavily improve the performance of metric indexes that were originally designed to employ simple ball-regions. We show that the shape of cut-regions is far more compact than that of ball-regions, yet preserving simple and concise representation. We present three re-designed metric indexes originating from the above-mentioned ones but utilizing cut-regions instead of ball-regions. We show that cut-regions can be fully utilized in the index structure, positively affecting not only query processing but also the index construction. In the experiments we show that the re-designed metric indexes significantly outperform their original versions.