基于改进的平均跳距和估计距离的DV-Hop定位算法*

为了提高DV-Hop定位算法在不规则网络中的精确度,针对该算法的不足之处,提出了一种基于平均跳距和估计距离的改进的DV-Hop算法。该算法考虑了未知节点到参考节点的路径与参考节点间的路径可能存在重合或部分重合这一特性,对平均跳距进行修改,并利用误差对距离进行修正。仿真实验结果表明,在不规则网络环境下,改进算法的定位精度得到明显提高。     

Using disability data to estimate design exclusion

Exclusion auditing is a process that can quantitatively evaluate the inclusive merit of different products, or alternative design decisions. The results from such an audit can provide prioritised directions for product improvement and support the business case for reducing the capability levels required to use mainstream products. The 1996/1997 disability follow-up survey, conducted by the Office of National Statistics, is currently the most comprehensive data source for estimating design exclusion in the UK. In this paper, the data source is explained in detail, and a method is presented that uses this data to estimate the exclusion associated with several tasks that occur in series or in parallel, illustrated through worked examples. Having evaluated how many people are excluded, one can investigate why they were excluded, thus generating design insights into how they could be included. Data from the survey is also converted to a series of stylised graphs, which are intended to inspire designers to think about the relationship between the demands required to use a product and the resulting levels of population exclusion.     

一种基于GIS的居民出行空间及交通网络评估方法

传统的交通需求4阶段分析模型大多基于各类出行的起讫点调查（OD调查）,建立出行生成、出行分布、出行方式选择和流量分配的4阶段预测模式.由于缺乏关于出行者对道路及其周边相关评价等心理感知方面的考虑,从本质上,这是一种物质性的交通分析模型.基于人本主义思想,借助GIS工具,探讨了人本主义的交通调查和评估方法;最后选择小样本量的出行调查数据为实验,实现了居民微观行为空间、行为过程以及对沿路交通状况及土地利用特征的宏观综合模拟.     

Using site-specific data to estimate energy crop yield

The estimation of energy crop yields is important, to help the firms responsible for collecting them to estimate biomass production in a given area, for example. A Bayesian modelling framework for site-specific yield estimation is presented in this paper. The proposed approach is based on a hierarchical model describing between-site and within-site yield variability. Probability distributions are used to describe the uncertainty of model estimations. The model can be fitted to site-specific yield data, to obtain both average and site-specific yield estimates. Site-specific yield data may be obtained from measurements for crop species other than those for which estimations are required, or from past measurements on perennial crop species grown over a period of several years at a given site. These two options were illustrated in two case studies, in which our model was used to estimate the yields of several energy crops. In most situations, site-specific yield estimations were more accurate than average estimations.     

Using edit distance to analyze card sorts

Abstract: Card sorts are a knowledge elicitation technique in which participants are given a collection of items and are asked to partition them into groups based on their own criteria. Information about the participant's knowledge structure is inferred from the groups formed and the names used to describe the groups through various methods ranging from simple quantitative statistical measures (e.g. co‐occurrence frequencies) to complex qualitative methods (e.g. content analysis on the group names). This paper introduces a new technique for analyzing card sort data that uses quantitative measures to discover rich qualitative results. This method is based upon a distance metric between sorts that allows one to measure the similarity of groupings and then look for clusters of closely related sorts across individuals. By using software for computing these clusters, it is possible to identify common concepts across individuals, despite the use of different terminology.     

基于测距修正和位置校正的RSSI定位算法

在基于接收信号强度指示(RSSI)的无线传感器网络节点定位问题中,为了提高节点的定位精度,通过对无线电传播路径损耗模型的分析,提出了基于RSSI测距的改进距离估计公式。针对已有节点校正方法存在的不足,提出了将一次循环校正后所有校正坐标的质心作为新的节点位置的校正方法。实验结果表明,改进的距离估计公式有效地提高了节点间的距离精度,并在适当增加节点计算量前提下,节点位置校正使节点的定位精度更高,达到良好的定位效果。     

Using nonlinear approximation to estimate the parameters of plant time to failure

A method was proposed for construction of the generalized distributions employed in the graphs-analytical method which makes use of the experimental data to estimate the distribution parameters of the plant time to failure. The existence conditions for generalized distributions were formulated. The resources of the proposed approach were illustrated by way of analysis of the modeled sample data.     

Using cocitation information to estimate political orientation in web documents

This paper introduces a simple method for estimating cultural orientation, the affiliation of online entities in a polarized field of discourse. In particular, cocitation information is used to estimate the political orientation of hypertext documents. A type of cultural orientation, the political orientation of a document is the degree to which it participates in traditionally left- or right-wing beliefs. Estimating documents' political orientation is of interest for personalized information retrieval and recommender systems. In its application to politics, the method uses a simple probabilistic model to estimate the strength of association between a document and left- and right-wing communities. The model estimates the likelihood of cocitation between a document of interest and a small number of documents of known orientation. The model is tested on three sets of data, 695 partisan web documents, 162 political weblogs, and 198 nonpartisan documents. Accuracy above 90% is obtained from the cocitation model, outperforming lexically based classifiers at statistically significant levels.     

Using use case patterns to estimate reusability in software systems

The applicability of using use case patterns as a basis for software cost estimation in the early stages of software development is described. This required the construction of a use case patterns catalogue using a novel process. The catalogue has been analysed to estimate the potential reusability in different software applications. This has shown that 43% of system functions are generally application domain independent, whereas 57% are application domain dependent. Statistical tests showed that the level of specialisation in software systems could be as low as 20%, which supports the direction taken in this research to build a use case patterns catalogue as a basis for the development of use case based software cost estimation models.     

Using the maximum likelihood method to estimate test complexity levels

Consideration was given to the problem of estimating the levels of complexity of the test tasks for the remote education system. It was assumed that the random responses of the subjects obey the logistic distribution and the levels of student readiness are not known in advance. An algorithm based on the methods of maximum likelihood and Broyden-Fletcher-Goldfarb-Shanno was proposed to calculate the task complexity. Strict concavity of the logarithmic likelihood function was established, and an example was considered.     

Using multiple radiometric correction images to estimate leaf area index

Ecological applications of remote-sensing techniques are generally limited to images after atmospheric correction, though other radiometric correction data are potentially valuable. In this article, six spectral vegetation indices (VIs) were derived from a SPOT 5 image at four radiometric correction levels: digital number (DN), at-sensor radiance (SR), top of atmosphere reflectance (TOA) and post-atmospheric correction reflectance (PAC). These VIs include the normalized difference vegetation index (NDVI), ratio vegetation index (RVI), slope ratio of radiation curve (K), general radiance level (L), visible-infrared radiation balance (B) and band radiance variation (V). They were then related to the leaf area index (LAI), acquired from in situ measurement in Hetian town, Fujian Province, China. The VI–LAI correlation coefficients varied greatly across vegetation types, VIs as well as image radiometric correction levels, and were not surely increased by image radiometric corrections. Among all 330 VI–LAI models established, the R ² of multi-variable models were generally higher than those of the single-variable ones. The independent variables of the best VI–LAI models contained all VIs from all radiometric correction levels, showing the potentials of multi-radiometric correction images in LAI estimating. The results indicated that the use of VIs from multiple radiometric correction images can better exploit the capabilities of remote-sensing information, thus improving the accuracy of LAI estimating.     

Using test case patterns to estimate software development and quality management cost

A novel process to discover test case patterns is proposed. This has led to the construction of a test case patterns catalogue. The catalogue has been analysed to estimate the potential reusability in different software applications. This has shown that 43% of system functions are generally application domain independent, whereas 57% are application domain dependent. Statistical tests showed that the level of specialisation in software systems could be as low as 20%, which supports the direction taken in this research to reuse test case patterns in software engineering activities, in particular, software cost estimation at the early sages of software development.

Using enterprise architecture analysis and interview data to estimate service response time

Insights into service response time is important for service-oriented architectures and service management. However, directly measuring the service response time is not always feasible or can be very costly. This paper extends an analytical modeling method which uses enterprise architecture modeling to support the analysis. The extensions consist of (i) a formalization using the Hybrid Probabilistic Relational Model formalism, (ii) an implementation in an analysis tool for enterprise architecture and (iii) a data collection approach using expert assessments collected via interviews and questionnaires. The accuracy and cost effectiveness of the method was tested empirically by comparing it with direct performance measurements of five services of a geographical information system at a Swedish utility company. The tests indicate that the proposed method can be a viable option for rapid service response time estimates when a moderate accuracy within 15% is sufficient.     

Using distance transform to solve real-time machine vision inspection problems

This paper describes novel solutions to two challenging real-time inspection tasks in machine vision. The first is fast surface approximation for volume and surface area measurements of irregularly shaped objects; the second is fast intensity gradient correction for surface inspection and evaluation of spherical objects. Both solutions apply a distance transform (DT) based on the distance of each image pixel from the object boundary. We describe both real-time machine vision inspection tasks and discuss their complexity. We show that the new solutions result in significant improvements in both accuracy and efficiency—despite the relative simplicity of the DT approach.     

基于补集零空间与最近空间距离的人脸识别

针对人脸识别中在分类器判别时没有充分利用类间差异的问题,提出一种补集零空间（CNS）算法,并进一步提出结合CNS算法与最近空间距离的人脸识别算法——补集零空间与最近空间距离算法（CNSD）。首先,在训练样本中,对每一种类别的人脸样本,构建其子空间并计算其补集的零空间;其次,计算测试样本与所有子空间和补集零空间的距离,找到最小的子空间距离与最大的补集零空间距离对应的类别,将其判别为测试样本的类别。算法在ORL与AR人脸数据集上进行了测试,当训练样本数较小时,CNS算法与CNSD算法识别率远高于最近邻分类器（NN）算法、最近空间距离（NS）算法、最近最远空间距离（NFS）算法;训练样本数较大时,CNS算法与CNSD算法识别率也略高于NN算法、NS算法、NFS算法。实验结果表明,所提算法能充分利用图像的类间差异,提高人脸识别的成功率。     

基于多摄像位的空间定位系统的研究与设计

基于多摄像位的空间定位即从来自多个摄像位的视频截图中获取物体的空间三维几何信息。本系统主要由三个部分构成,分别是:摄像机标定部分、立体匹配部分、基于点的三维重建部分。本文主要围绕这几个部分展开研究:首先,在摄像机参数标定中,采用正友的基于平面标定模板的摄像机标定方法,通过实验和计算获取摄像机的参数;其次,立体匹配部分采用了Burchfield算法,试验结果得到了视差图;最后,最后根据立体视觉基本原理,完成了三维坐标计算,得到了一个特定区域的点集信息(如球类)。本文最终设计并实现了一个应用于体育节目包装的基于多摄像位的空间定位系统。     

An interpretation of Mahalanobis distance in the dual space

Using the concept of a dual space, nk-dimensional vectors can be viewed as k points in an n-dimensional co-ordinate system. The relationships between the basic statistical properties of a k-variate sample and the geometrical properties of such a space are developed and the concept extended to two samples drawn from different populations, with derivation of the geometrical meaning of Mahalanobis distance. This geometrical approach provides valuable insight into why different feature subsets may or may not have high discriminatory potential, and shows that clustering in the dual space, or its subspaces, does not necessarily yield an effective feature selection technique.