A new delay-dependent absolute stability criterion for a class of nonlinear neutral systems

This paper deals with absolute stability for a class of nonlinear neutral systems using a discretized Lyapunov functional approach. A delay-dependent absolute stability criterion is obtained and formulated in the form of linear matrix inequalities (LMIs). The criterion is valid not only for systems with small delay, but also for systems with non-small delay. Neither model transformation nor bounding technique for cross terms, nor free weighting matrix method is involved through derivation of the stability criterion. Numerical examples show that for small delay case, the results obtained in this paper significantly improve the estimate of the stability limit over some existing result in the literature; for non-small delay case, the ideal results can also be achieved.     

New stability criteria for linear systems with interval time-varying delay

This paper investigates robust stability of uncertain linear systems with interval time-varying delay. The time-varying delay is assumed to belong to an interval and is a fast time-varying function. The uncertainty under consideration includes polytopic-type uncertainty and linear fractional norm-bounded uncertainty. A new Lyapunov-Krasovskii functional, which makes use of the information of both the lower and upper bounds of the interval time-varying delay, is proposed to drive some new delay-dependent stability criteria. In order to obtain much less conservative results, a tighter bounding for some term is estimated. Moreover, no redundant matrix variable is introduced. Finally, three numerical examples are given to show the effectiveness of the proposed stability criteria.     

Sub-pixel confusion-uncertainty matrix for assessing soft classifications

The prevailing concerns on ecological and environmental issues, occurring especially at regional to global scales, have prompted significant advances on the use of remote sensing data for the estimation of land cover information at sub-pixel level. However, the quality of such classification products, as well as the performance of the classification protocol employed, are difficult to quantify. This paper had the objectives of 1) reviewing the existing alternatives, while identifying major drawbacks and desirable properties, for sub-pixel accuracy assessment based on cross-comparison matrices, and 2) developing theoretical grounds, for a more general accuracy assessment of soft classifications, that account for the sub-pixel class distribution uncertainty. It was found that, for a sub-pixel confusion matrix to exhibit a diagonalization characteristic that allows identifying a perfect matching case, the agreement measure must be constrained at pixel level, whereas a disagreement measure can take into account the sub-pixel distribution uncertainty, leading to an underspecified problem termed the sub-pixel area allocation problem. It was demonstrated that the sub-pixel area allocation problem admits a unique solution if, and only if, no more than one class is either over- or underestimated at each pixel. In this case, the sub-pixel confusion can be uniquely determined. When no unique solution exists, the space of feasible solutions can be represented by confusion intervals. A new cross-comparison matrix that reports the confusion intervals in the form of a center value plus-minus maximum error was proposed to account for the sub-pixel distribution uncertainty. The new matrix is referred to as sub-pixel confusion-uncertainty matrix (SCM). Sub-pixel accuracy measures were also derived from this matrix. The practical use of the SCM and derived indices was demonstrated in assessing an invasive species detection method and a fuzzy classification of urban land use/land cover through remote sensing procedures.     

Improving user assessment of error implications in digital elevation models

A digital representation of a terrain surface is an approximation of reality and is inherently prone to some degree of error and uncertainty. Research in uncertainty analysis has produced a vast range of methods for investigating error and its propagation. However, the complex and varied methods proposed by researchers and academics create ambiguity for the dataset user. In this study, existing methods are combined and simplified to present a prototype tool to enable any digital elevation model (DEM) user to access and apply uncertainty analysis. The effect of correlated gridded DEM error is investigated, using stochastic conditional simulation to generate multiple equally likely representations of an actual terrain surface. Propagation of data uncertainty to the slope derivative, and the impact on a landslide susceptibility model are assessed. Two frameworks are developed to examine the probable and possible uncertainties in classifying the landslide hazard: probabilistic and fuzzy. The entire procedure is automated using publicly available software and user requirements are minimised. A case study example shows the resultant code can be used to quantify, visualise and demonstrate the propagation of error in a DEM. As a tool for uncertainty analysis the method can improve user assessment of error and its implications.     

Choose your “buddy icon” carefully: The influence of avatar androgyny, anthropomorphism and credibility in online interactions

In both online and offline interactions, the visual representation of people influences how others perceive them. In contrast to the offline body, an online visual representation of a person is consciously chosen and not stable. This paper reports the results of a 2 step examination of the influence of avatars on the person perception process. Specifically, this project examines the reliance on visual characteristics during the online perception process, and the relative influence of androgyny, anthropomorphism and credibility. In the first step, 255 participants fill out a survey where they rated a set of 30 static avatars on their credibility, androgyny, and anthropomorphism. The second step is a between subjects experiment with 230 participants who interact with partners represented by one of eight avatars (high and low androgyny, and anthropomorphism by high and low credibility). Results show that the characteristics of the avatar are used in the person perception process. Causal modeling techniques revealed that perceptions of avatar androgyny influence perceptions of anthropomorphism, which influences attributions of both avatar and partner credibility. Implications of these results for theory, future research, and users and designers of systems using avatars are discussed.     

一次砝码国际比对

介绍了中国航空长城计量测试研究所质量校准实验室参加亚太地区国际实验室之间砝码比对的情况,给出了测量结果的不确定度分析。     

洛氏硬度标准装置不确定度的评定

详细给出了洛氏硬度标准装置不确定度的评定方法及步骤。     

接触定位式量块干涉仪测量不确定度的分析

分析了一台用于测量量块的激光干涉仪的测量不确定度。着重介绍了干涉信号质量,空气折射率及材料热膨胀等因素对测量不确定度的影响。     

Evaluating ecommerce websites cognitive efficiency: An integrative framework based on data envelopment analysis

This paper presents an integrative framework to evaluate ecommerce website efficiency from the user viewpoint using Data Envelopment Analysis (DEA). This framework is inspired by concepts driven from theories of information processing and cognition and considers the website efficiency as a measure of its quality and performance. When the users interact with the website interfaces to perform a task, they are involved in a cognitive effort, sustaining a cognitive cost to search, interpret and process information, and experiencing either a sense of satisfaction or dissatisfaction for that. The amount of ambiguity and uncertainty, and the search (over-)time during navigation that they perceive determine the effort size – and, as a consequence, the cognitive cost amount – they have to bear to perform their task. On the contrary, task performing and result achievement provide the users with cognitive benefits, making interaction with the website potentially attractive, satisfying, and useful. In total, 9 variables are measured, classified in a set of 3 website macro-dimensions (user experience, site navigability and structure). The framework is implemented to compare 52 ecommerce websites that sell products in the information technology and media market. A stepwise regression is performed to assess the influence of cognitive costs and benefits that mostly affect website efficiency.     

A new delay-dependent stability criterion for linear neutral systems with norm-bounded uncertainties in all system matrices

This paper deals with the problem of robust stability for a class of uncertain linear neutral systems. The uncertainties under consideration are of norm-bounded type and appear in all system matrices. A new delay-dependent stability criterion is obtained and formulated in the form of linear matrix inequalities (LMIs). Neither model transformation nor bounding technique for cross terms is involved through derivation of the stability criterion. Numerical examples show that the results obtained in this paper significantly improve the estimate of the stability limit over some existing results in the literature.