Web services is one of the basic network services, whose availability evaluation is of great significance to the promotion of users’ experience. This paper focuses on the problem of availability evaluation of Web ser...Web services is one of the basic network services, whose availability evaluation is of great significance to the promotion of users’ experience. This paper focuses on the problem of availability evaluation of Web services and proposes a method for availability evaluation of Web services using improved grey correlation analysis with entropy difference and weight (EWGCA).This method is based on grey correlation analysis, and use entropy difference to illustrate the changes of availability, set weight to quantize availability requirements of different operations or transactions in services. Through simulation experiment in high load scenarios for Web services, the experiment result shows that our method can realize hierarchical description and overall evaluation for availability of Web services accurately in the case of smaller test sample volumes or uncertain data even in the field of big data.展开更多
Existing Web service selection approaches usually assume that preferences of users have been provided in a quantitative form by users. However, due to the subjectivity and vagueness of preferences, it may be impractic...Existing Web service selection approaches usually assume that preferences of users have been provided in a quantitative form by users. However, due to the subjectivity and vagueness of preferences, it may be impractical for users to specify quantitative and exact preferences. Moreover, due to that Quality of Service (QoS) attributes are often interrelated, existing Web service selection approaches which employ weighted summation of QoS attribute values to compute the overall QoS of Web services may produce inaccurate results, since they do not take correlations among QoS attributes into account. To resolve these problems, a Web service selection framework considering user's preference priority is proposed, which incorporates a searching mechanism with QoS range setting to identify services satisfying the user's QoS constraints. With the identified service candidates, based on the idea of Principal Component Analysis (PCA), an algorithm of Web service selection named PCA-WSS (Web Service Selection based on PCA) is proposed, which can eliminate the correlations among QoS attributes and compute the overall QoS of Web services accurately. After computing the overall QoS for each service, the algorithm ranks the Web service candidates based on their overall QoS and recommends services with top QoS values to users. Finally, the effectiveness and feasibility of our approach are validated by experiments, i.e. the selected Web service by our approach is given high average evaluation than other ones by users and the time cost of PCA-WSS algorithm is not affected acutely by the number of service candidates.展开更多
Eddy current pulsed thermography（ECPT） is an emerging Non-destructive testing and evaluation（NDT E） technique, which uses hybrid eddy current and thermography NDT E techniques that enhances the detectability fro...Eddy current pulsed thermography（ECPT） is an emerging Non-destructive testing and evaluation（NDT E） technique, which uses hybrid eddy current and thermography NDT E techniques that enhances the detectability from their compensation. Currently, this technique is limited by the manual selection of proper contrast frames and the issue of improving the efficiency of defect detection of complex structure samples remains a challenge. In order to select a specific frame from transient thermal image sequences to maximize the contrast of thermal variation and defect pattern from complex structure samples, an energy driven approach to compute the coefficient energy of wavelet transform is proposed which has the potential of automatically selecting both optimal transient frame and spatial scale for defect detection using ECPT. According to analysis of the variation of different frequency component and the comparison study of the detection performance of different scale and wavelets, the frame at the end of heating phase is automatically selected as an optimal transient frame for defect detection. In addition, the detection capabilities of the complex structure samples can be enhanced through proper spatial scale and wavelet selection. The proposed method has successfully been applied to low speed impact damage detection of carbon fibre reinforced polymer（CFRP） composite as well as providing the guidance to improve the detectability of ECPT technique.展开更多
当前,针对Web应用层的分布式拒绝服务攻击(distributed denial of service,DDoS)形式愈加严峻,但是对此类DDoS的缓解手段研究较少且技术不够成熟,并且主要聚集于攻击过程中的检测和流量清洗,而缺乏针对Web服务器资源消耗脆弱性的主动检...当前,针对Web应用层的分布式拒绝服务攻击(distributed denial of service,DDoS)形式愈加严峻,但是对此类DDoS的缓解手段研究较少且技术不够成熟,并且主要聚集于攻击过程中的检测和流量清洗,而缺乏针对Web服务器资源消耗脆弱性的主动检测手段.为此,提出了面向Web服务资源消耗脆弱性的检测模型和评测框架,能够检测Web服务资源消耗脆弱点,并且评测Web服务资源消耗脆弱程度,旨在Web服务受到攻击前预先分析和了解Web服务的资源消耗脆弱性安全问题,为网站安全性能优化和需要采取的防御手段提供支撑.通过对某网站的实际测评验证了本模型和框架的有效性,能够通过对实际应用的网站进行Web服务资源消耗脆弱性检测和评测,发现其Web服务资源消耗脆弱点.展开更多
Geographic information has a great potential to be re-used when supported by mechanisms for its discovery.Above all,the quality of a catalogue service is the key feature supporting users in the discovery process.So fa...Geographic information has a great potential to be re-used when supported by mechanisms for its discovery.Above all,the quality of a catalogue service is the key feature supporting users in the discovery process.So far,there have been in existence various methodologies dealing with the normalized evaluation of quality with respect to catalogue services.Their biggest weakness seems to be in the depth of quality testing,i.e.some influences are beyond the scope of evaluation of these methodologies with respect to quality in catalogue services.In this study,the quality of 45 catalogue services across Europe was verified with the proposed normalized evaluation methodology originating from documents within the INfrastruture for SPatial InfoRmation in Europe(INSPIRE)framework.This paper discusses the(statistical)influence of factors that may significantly change the results of catalogue service testing.The proposals for improving the existing INSPIRE normalized evaluation procedure are applicable for any spatial data infrastructure and/or Digital Earth component using the Open Geospatial Consortium Catalogue Service for the Web as a basis.展开更多
基金This research is supported by the National Natural Science Foundation of China (61370212), the Research Fund for the Doctoral Program of Higher Education of China (20122304130002), the Natural Science Foundation of Heilongjiang Province (ZD 201102) and the Fundamental Research Fund for the Central Universities (HEUCFZ1213, HEUCF100601).
文摘Web services is one of the basic network services, whose availability evaluation is of great significance to the promotion of users’ experience. This paper focuses on the problem of availability evaluation of Web services and proposes a method for availability evaluation of Web services using improved grey correlation analysis with entropy difference and weight (EWGCA).This method is based on grey correlation analysis, and use entropy difference to illustrate the changes of availability, set weight to quantize availability requirements of different operations or transactions in services. Through simulation experiment in high load scenarios for Web services, the experiment result shows that our method can realize hierarchical description and overall evaluation for availability of Web services accurately in the case of smaller test sample volumes or uncertain data even in the field of big data.
基金Supported by the National Natural Science Foundation of China(No.90818004and61100054)Program for New Century Excellent Talents in University(No.NCET-10-0140)+1 种基金Excellent Youth Foundation of Hunan Scientific Committee(No.11JJ1011)Scientific Research Fundof Hunan Educational Committee(No.09K085and11B048)
文摘Existing Web service selection approaches usually assume that preferences of users have been provided in a quantitative form by users. However, due to the subjectivity and vagueness of preferences, it may be impractical for users to specify quantitative and exact preferences. Moreover, due to that Quality of Service (QoS) attributes are often interrelated, existing Web service selection approaches which employ weighted summation of QoS attribute values to compute the overall QoS of Web services may produce inaccurate results, since they do not take correlations among QoS attributes into account. To resolve these problems, a Web service selection framework considering user's preference priority is proposed, which incorporates a searching mechanism with QoS range setting to identify services satisfying the user's QoS constraints. With the identified service candidates, based on the idea of Principal Component Analysis (PCA), an algorithm of Web service selection named PCA-WSS (Web Service Selection based on PCA) is proposed, which can eliminate the correlations among QoS attributes and compute the overall QoS of Web services accurately. After computing the overall QoS for each service, the algorithm ranks the Web service candidates based on their overall QoS and recommends services with top QoS values to users. Finally, the effectiveness and feasibility of our approach are validated by experiments, i.e. the selected Web service by our approach is given high average evaluation than other ones by users and the time cost of PCA-WSS algorithm is not affected acutely by the number of service candidates.
基金Supported by National Natural Science Foundation of China(Grant No.51377015)China Post Doctor Project(Grant No.136413)Science&Technology Department of Sichuan Province,China(Grant No.2013HH0059)
文摘Eddy current pulsed thermography（ECPT） is an emerging Non-destructive testing and evaluation（NDT E） technique, which uses hybrid eddy current and thermography NDT E techniques that enhances the detectability from their compensation. Currently, this technique is limited by the manual selection of proper contrast frames and the issue of improving the efficiency of defect detection of complex structure samples remains a challenge. In order to select a specific frame from transient thermal image sequences to maximize the contrast of thermal variation and defect pattern from complex structure samples, an energy driven approach to compute the coefficient energy of wavelet transform is proposed which has the potential of automatically selecting both optimal transient frame and spatial scale for defect detection using ECPT. According to analysis of the variation of different frequency component and the comparison study of the detection performance of different scale and wavelets, the frame at the end of heating phase is automatically selected as an optimal transient frame for defect detection. In addition, the detection capabilities of the complex structure samples can be enhanced through proper spatial scale and wavelet selection. The proposed method has successfully been applied to low speed impact damage detection of carbon fibre reinforced polymer（CFRP） composite as well as providing the guidance to improve the detectability of ECPT technique.
文摘当前,针对Web应用层的分布式拒绝服务攻击(distributed denial of service,DDoS)形式愈加严峻,但是对此类DDoS的缓解手段研究较少且技术不够成熟,并且主要聚集于攻击过程中的检测和流量清洗,而缺乏针对Web服务器资源消耗脆弱性的主动检测手段.为此,提出了面向Web服务资源消耗脆弱性的检测模型和评测框架,能够检测Web服务资源消耗脆弱点,并且评测Web服务资源消耗脆弱程度,旨在Web服务受到攻击前预先分析和了解Web服务的资源消耗脆弱性安全问题,为网站安全性能优化和需要采取的防御手段提供支撑.通过对某网站的实际测评验证了本模型和框架的有效性,能够通过对实际应用的网站进行Web服务资源消耗脆弱性检测和评测,发现其Web服务资源消耗脆弱点.
基金funded by the project MUNI/A/0952/2013 entitled‘Analysis,evaluation and visualization of global environmental changes in the Component Earth’s Spheres’and Comenius University in Bratislava Science Park supported by the Research and Development Operational Programme funded by the ERDF Grant number:ITMS 26240220086.
文摘Geographic information has a great potential to be re-used when supported by mechanisms for its discovery.Above all,the quality of a catalogue service is the key feature supporting users in the discovery process.So far,there have been in existence various methodologies dealing with the normalized evaluation of quality with respect to catalogue services.Their biggest weakness seems to be in the depth of quality testing,i.e.some influences are beyond the scope of evaluation of these methodologies with respect to quality in catalogue services.In this study,the quality of 45 catalogue services across Europe was verified with the proposed normalized evaluation methodology originating from documents within the INfrastruture for SPatial InfoRmation in Europe(INSPIRE)framework.This paper discusses the(statistical)influence of factors that may significantly change the results of catalogue service testing.The proposals for improving the existing INSPIRE normalized evaluation procedure are applicable for any spatial data infrastructure and/or Digital Earth component using the Open Geospatial Consortium Catalogue Service for the Web as a basis.
