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Metamaterial with negative index due to chirality

Physical Review B 2009年第3期79卷 035407-035407页

作者： E. Plum J. Zhou J. Dong V. A. Fedotov T. Koschny C. M. Soukoulis N. I. Zheludev Optoelectronics Research Centre University of Southampton Southampton SO17 1BJ United Kingdom Department of Electrical and Computer Engineering and Microelectronics Research Center Iowa State University Ames Iowa 50011 USA Department of Physics and Astronomy and Ames Laboratory Iowa State University Ames Iowa 50011 USA Institute of Optical Fiber Communications and Network Technology Ningbo University Ningbo 315211 China Institute of Electronic Structure and Laser—FORTH and Department of Materials Science and Technology University of Crete Greece

Recently it has been predicted that materials with exceptionally strong optical activity may also possess a negative refractive index, allowing the realization of superlenses for super-resolution imaging and data storage applications. Here we demonstrate experimentally and numerically that a chirality-induced negative index of refraction is possible. A negative index of refraction due to three-dimensional chirality is demonstrated for a bilayered metamaterial based on pairs of mutually twisted planar metal patterns in parallel planes, which also shows negative electric and magnetic responses and exceptionally strong optical activity and circular dichroism. Multilayered forms of the metamaterial are found to be suitable for use as ultrathin polarization rotators and circular polarizers for practical applications.

关键词： chirality circular dichroism metamaterials optical materials optical multilayers optical rotation polarisation refractive index

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Improved block-level continuous data protection mechanism

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Jisuanji Yanjiu yu Fazhan/computer Research and Development 2009年第5期46卷 762-769页

作者： Li, Xu Xie, Changsheng Yang, Jing Cao, Qiang Wei, Qinqi Wuhan National Laboratory for Optoelectronics College of Computer Science and Technology Huazhong Univ. of Sci. and Technol. Wuhan 430074 China Network and Information Center WISDRI Engineering and Research Incorporation Limited Company Wuhan 430223 China

With the rapid development of storage technology, continuous data protection (CDP) has become an important data protection and recovery method for modern data storage systems now. According to the merits and shortcomings of existing CDP mechanism, an improved mechanism based on TRAP-4 (timely recovery to any point-in-time) is provided. It reserves the basic data logging method of TRAP-4 first, and then inserts a few snapshot data into the recovery chain by a certain interval values d. This mechanism can not only avoid the latent recover chain crash problem, but also can shorten the data recovery time greatly. A quantitative mathematical model is used to analyze its performance and calculate an optimal d value for ST-CDP. This prototype system of block level ST-CDP mechanism has been implemented in a Linux block level device (MD RAID 5 device for Linux kernel). Contrastive experiments among three different CDP mechanisms are presented. The performance test results show that ST-CDP not only have lower storage space overhead and less infection to the storage system than those of the traditional snapshot mechanisms, but also have higher recovery efficiency and reliability than TRAP-4. It is affirmed that ST-CDP is an efficient continuous data protection mechanism with very low recovery cost.

关键词： Chains

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Prostate cancer localization with multispectral MRI based on Relevance Vector Machines

Prostate cancer localization with multispectral MRI based on...

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IEEE International Symposium on Biomedical Imaging

作者： S. Ozer M. A. Haider D. L. Langer T. H. van der Kwast A. J. Evans M. N. Wernick J. Trachtenberg I. S. Yetik Medical Imaging Research Center (MIRC) Electrical & Computer Engineering Department Illinois Institute of Technology Chicago IL USA Joint Department of Medical Imaging Princess Margaret Hospital University Health Network and Mount Sinai Hospital Toronto ONT Canada Institute of Medical Science University of Toronto Toronto ONT Canada Department of Pathology and Laboratory Medicine Toronto General Hospital Toronto ONT Canada

ISBN: (纸本)9781424439317

Prostate cancer is one of the leading causes of cancer death for men. However, early detection before cancer spreads beyond the prostate can reduce the mortality. Therefore, in vivo imaging techniques play an important role to localize the prostate cancer for treatment. Although magnetic resonance imaging (MRI) has been proposed to localize prostate cancer, the studies on automated localization with multispectral MRI have been limited. In this study we propose combining the pharmacokinetic parameters derived from DCE MRI with T2 MRI and DWI. We also propose to use relevance vector machines (RVM) for automatic prostate cancer localization, compare its performance to support vector machines (SVM) and show that RVM can produce more accurate and more efficient segmentation results than SVM for automated prostate cancer localization with multispectral MRI.

关键词： Prostate cancer Magnetic resonance imaging Support vector machines Biomedical imaging Hospitals Needles Cancer detection Image segmentation Humans Neoplasms

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Fuzzy analytic hierarchy process-based utilities evaluation and adoption for DRM security policies

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Tongxin Xuebao/Journal on Communications 2009年第1 A期30卷 126-131页

作者： Zhang, Zhi-Yong Ye, Chuan-Qi Fan, Ke-Feng Zhang, Li-Li Niu, Dan-Mei Electronics Information Engineering College Henan University of Science and Technology Luoyang 471003 China Ministry of Education Key Laboratory of Computer Network and Information Security Xidian University Xi'an 710071 China Information Security Center for the State Key Laboratory of Network and Exchange Beijing Post and Telecom University Beijing 100158 China

The utility evaluation of DRM security policies based on fuzzy analytic hierarchy process (FAHP) and their game-theoretic adoptions were proposed from a novel perspective of the different level security and utilities' analyses. Based on the analytic hierarchy structure, the fuzzy estimation consistency matrix was employed to analyze the weights of optional security components and services, and then the gained weight values were further used for the computing of security policies' utilities and the accomplishing the game, finally yielding Nash equilibriums, that is, optimal policies profiles, as well as pre-conditions for participants. The use case for a group of the typical security policies shows that the result of the game includes two different groups of security policies profiles, as well as contents/services provider could effectively deploy a DRM system in term of the number of consumers purchasing digital contents, and average purchase, thus achieving the balance between the digital copyrights protection and real payoffs of participants.

关键词： Game theory

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A history based semantic aware access control model using logical time

A history based semantic aware access control model using lo...

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11th International Conference on computer and Information technology, ICCIT 2008

作者： Ravari, Ali Noorollahi Amini, Morteza Jalili, Rasool Jafarian, Jafar Haadi Network Security Center Computer Engineering Department Sharif University Of Technology Tehran Iran

ISBN: (纸本)9781424421367

With the advent of semantic technology' access control cannot be done in a safe way unless the access decision takes into account the semantic relationships among the entities in a semantic-aware environment. The SBAC model (Semantic Based Access Control model) considers this issue in its decision making process. However' time plays a crucial role in new computing environments'which is not supported in SBAC. In this paper' we propose the Temporal Semantic Based Access Control (TSBAC) model' as an extension of SBAC' which enhances the specification of user-defined authorization rules by constraining time interval and temporal expression over users' history of accesses. TSBAC uses logical time' rather than to real time' in its authorization rules. A formal semantics for temporal authorizations is provided and conflicting situations (due to the semantic relations of the SBAC model and a sub-interval relation between authorizations) are investigated and resolved in our proposed model. An architecture for the access control system based on TSBAC is presented.©2008 IEEE.

关键词： Access control models

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A temporal semantic-based access control model

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13th International computer Society of Iran computer Conference on Advances in computer Science and engineering, CSICC 2008

作者： Noorollahi Ravari, Ali Amini, Morteza Jalili, Rasool Network Security Center Computer Engineering Department Sharif University of Technology Tehran Iran

ISBN: (纸本)3540899847

With the advent of semantic technology, access control cannot be done in a safe way unless the access decision takes into account the semantic relationships between entities in a semantic-aware environment. SBAC model considers this issue in the decision making process. However, time plays a crucial role in new computing environments which is not supported in this model. In this paper we introduce temporal semantic based access control model (TSBAC), as an extension of SBAC model, which enhances the specification of user-defined authorization rules by constraining time interval and temporal expression over users' history of accesses. A formal semantics for temporal authorizations is provided and conflicting situations (due to the semantic relations of the SBAC model and a sub-interval relation between authorizations) are investigated and resolved in our proposed model. © 2008 Springer-Verlag.

关键词： Semantics

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A strategy selection model for network survivability based on fuzzy matrix game

A strategy selection model for network survivability based o...

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9th International Conference on Web-Age Information Management, WAIM 2008

作者： Zhao, Guosheng Wang, Huiqiang Wang, Jian School of Computer Science and Technology Harbin Engineering University China Center of Computer Network and Information Harbin Normal University China

ISBN: (纸本)9780769531854

Survivability has emerged as a new phase for the development of network security technique, and how to improve the system survivability using effective strategy is an important problem. In this paper, by analyzing the fuzzy matrix game (FMG) theory and network survivability mechanism, a novel strategy selection model for network survivability based on FMG theory and its dynamic analysis method are presented from the macroscopically view. The result of instance analysis and validation show that the proposed method can provide guarantee conditions for network survivability effectively. © 2008 IEEE.

关键词： Game theory

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Detection and localization of facial profiles in color images

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Journal of Information and Computational Science 2008年第3期5卷 1037-1044页

作者： Wang, Jianguo Yang, Wankou Hua, Jizhao Yang, Jingyu School of Computer Science and Technology Nanjing University of Science and Technology Nanjing 210094 China Network and Education Center Tangshan College Tangshan 063000 China College of Information and Engineering Yangzhou University Yangzhou 225009 China

A novel coarse-to-fine facial profile detection and localization method in color images is proposed. First skin-tone regions are detected;Then removing some non-face regions by preprocessing rules;Thirdly the orientation of the facial profile is first detected, then extracting fiducial points on facial profile, finally these fiducial points are used to segment the facial profile based on the ratio relationship;At last final verification of the facial profiles is performed. Experiment results show the effectiveness of the proposed method.

关键词： Face recognition

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Caching Learning Units on Mobile Terminal Unit in a Mobile Learning System

Caching Learning Units on Mobile Terminal Unit in a Mobile L...

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IEEE International Symposium on IT in Medicine and Education

作者： Wang, Hong Liu, Hong Wang, Zhaowen Institute of Information Science and Engineering ShanDong Normal University China Institute of Computer Science and Technology ShanDong University China Network Information Center Shandong Jianzhu University China

ISBN: (纸本)9781424425105

In order to support large-scale mobile learning software running on the resource-limited mobile devices, a cache management on mobile terminal units in a mobile learning system based on Learning Unit (LU) is introduced. The generation-based algorithm in memory management according to the adaptive thinking is introduced Considering the different characteristics of the objects in the less-relied generation and the more relied generation, different allocating methods and garbage collecting algorithm are adopted These methods highly improve the efficiency of the cache management and avoid long-time problem in general garbage collecting algorithms. The experiment indicates that the cache management is reasonable and effectively supports the application of the mobile learning software for mobile terminal units.

关键词： Learning systems Mobile computing Large-scale systems Resource management Character generation Portable computers computer science education Systems engineering education Information science computer science

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Low power circuits for NoC-based SoC design

Low power circuits for NoC-based SoC design

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2008 9th International Conference on Solid-State and Integrated-Circuit technology, ICSICT 2008

作者： Song, Zhaohui Guangsheng, Ma. Song, Dalei School of Computer Science and Technology Harbin Engineering University Harbin 150001 China Computer Network Center Heilongjiang Electric Power Stuff University Harbin 150030 China College of Engineering Ocean University of China Qingdao 266001 China

ISBN: (纸本)9781424421855

In large-scale system-on-chips (SoCs), the power consumption on the communication infrastructure should be minimized for reliable, feasible, and cost-efficient implementations. An energy-efficient network-on-chip (NoC) is necessary for application to high performance SoC design. Various low-power circuits are designed, and implemented in each open system interconnection layer. Low-swing serial link and source-synchronous serial communication in physical layer and low-energy serial link coding in data-link layer are designed and realized on the NoC. Partially activated crossbar and Mux-Tree based round-robin scheduler are also designed to reduce the power consumption in network layer. Experiment on these low-power circuits demonstrate that the NoC power dissipation is reduced by 38%. © 2008 IEEE.

关键词： network-on-chip

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