AC losses in multilayer superconducting tapes

ac losses have been investigated experimentally as well as theoretically in tapes having on the surface several normal conducting and/or superconducting layers. The superconducting layers under investigation have been Nb₃Sn on a niobium substrate and Nb₃Ge on a stainless steel substrate. It has been proved that the layered structure of the tapes is well reflected by the stepwise character of the ac losses dependence on the amplitude of the surface magnetic field. The magnetic flux passing through a surperconducting layer or surface barrier into the inside of the tape enhances the losses in the passed barrier or layer.     

Securing Recommender Systems Against Shilling Attacks Using Social-Based Clustering

Recommender systems (RS) have been found supportive and practical in e-commerce and been established as useful aiding services. Despite their great adoption in the user communities, RS are still vulnerable to unscrupulous producers who try to promote their products by shilling the systems. With the advent of social networks new sources of information have been made available which can potentially render RS more resistant to attacks. In this paper we explore the information provided in the form of social links with clustering for diminishing the impact of attacks. We propose two algorithms, CluTr and WCluTr, to combine clustering with "trust" among users. We demonstrate that CluTr and WCluTr enhance the robustness of RS by experimentally evaluating them on data from a public consumer recommender system Epinions.com.     

An asymptotically exact LMI solution to the robust discretisation of LTI systems with polytopic uncertainties and its application to sampled-data control

In this paper, the problem of robust discretisation of linear time-invariant (LTI) systems with polytopic uncertainties is introduced. More specifically, the main objective is to provide a systematic way to find an approximate discrete-time (DT) model of a continuous-time (CT) plant with uncertainties in polytopic domain. The system matrices of polytopic DT model to be found are expressed as parameter-dependent matrices which are homogeneous polynomials of arbitrary degree with respect to the uncertain variables in the simplex, and is obtained in such a way that the norm between the system matrices and the truncated power series of the exact DT model is minimised while preserving the polytopic structure of the original CT plant. The solution procedures proposed are presented in terms of single-parameter minimisation problems subject to linear matrix inequality (LMI) constraints which are numerically tractable via LMI solvers. Finally, examples are given to show the validity and effectiveness of the proposed techniques.     

Investigating ERP systems procurement practice: Hong Kong and Australian experiences

ContextIntegration of information systems is now commonly recognized to be a powerful strategic weapon that sharpens the competitive edge of a firm in today’s highly volatile business environment. Such integration can be achieved by replacing the disconnected and incompatible legacy applications by enterprise resource planning (ERP) systems. Along with the remarkable growth of the ERP market, we have seen a number of failure cases of ERP adoption. Such failure cases indicate that not all firms know how to adopt an ERP solution effectively.ObjectiveTo explore and identify crucial practices from real experiences in the Asia–Pacific region that may explain a firm’s success in ERP procurement, with an overt intention toward the formulation of useful lessons that inform practitioners and contribution to advances in software development practices in organizations.MethodA multiple-case design involving three Chinese firms based in Hong Kong and a local firm in Australia was employed. We collected, verified, and analyzed the information about the ERP procurement practice in each subject firm by means of semi-structured interviews, archive reviews, and member checks.ResultsWe summarized our results in the form of 10 lessons learned, together with observations of how culture seems to have played a part in shaping the practice.ConclusionOur results offer practical guidelines originated from real cases that are of use for practitioners to improve the ERP procurement process.     

Polarisation-independent vertically coupled microring resonatorfilter

A polarisation-independent microring resonator filter is proposed using a birefringent polymer overlay. The thickness of the polymer overlay is optimally designed and the polarisation-independent operation successfully demonstrated     

An uncertainty importance measure using a distance metric for the change in a cumulative distribution function

A simple measure of uncertainty importance using the entire change of cumulative distribution functions (CDFs) has been developed for use in probability safety assessments (PSAs). The entire change of CDFs is quantified in terms of the metric distance between two CDFs. The metric distance measure developed in this study reflects the relative impact of distributional changes of inputs on the change of an output distribution, while most of the existing uncertainty importance measures reflect the magnitude of relative contribution of input uncertainties to the output uncertainty. The present measure has been evaluated analytically for various analytical distributions to examine its characteristics. To illustrate the applicability and strength of the present measure, two examples are provided. The first example is an application of the present measure to a typical problem of a system fault tree analysis and the second one is for a hypothetical non-linear model. Comparisons of the present result with those obtained by existing uncertainty importance measures show that the metric distance measure is a useful tool to express the measure of uncertainty importance in terms of the relative impact of distributional changes of inputs on the change of an output distribution.     

Serum response of Escherichia coli strains causing dyspepsia and urinary tract infection: relation to alpha-hemolysin production and O type

A total of 109 alpha-hemolytic and 104 nonhemolytic Escherichia coli isolates from children with dyspepsia and urinary tract infections were investigated for resistance to the bactericidal activity of human serum. A significantly higher proportion of serum resistance was found in alpha-hemolytic E. coli isolates than in nonhemolytic isolates (P < 0.01). An association between the titer of alpha-hemolysin produced and serum resistance was found.