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Articles 7021 - 7050 of 7446

Full-Text Articles in Physical Sciences and Mathematics

An Efficient Known Plaintext Attack On Fea-M, Hongjun Wu, Feng Bao, Robert H. Deng Oct 2003

An Efficient Known Plaintext Attack On Fea-M, Hongjun Wu, Feng Bao, Robert H. Deng

Research Collection School Of Computing and Information Systems

Yi et al. have proposed a cipher called the fast encryption algorithm for multimedia (FEA-M). Recently Mihaljevi and Kohno pointed out that FEA-M is insecure. However, their attacks are not efficient: their chosen plaintext attack and known plaintext attack require 237-bit chosen plaintext and 260-bit known plaintext, respectively. In this paper we give an efficient known plaintext attack against FEA-M. Our attack requires only 228-bit known plaintext and about 233 XOR operations.

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Validating Digital Signatures Without Ttp’S Time-Stamping And Certificate Revocation, Jianying Zhou, Feng Bao, Robert H. Deng Oct 2003

Validating Digital Signatures Without Ttp’S Time-Stamping And Certificate Revocation, Jianying Zhou, Feng Bao, Robert H. Deng

Research Collection School Of Computing and Information Systems

In non-repudiation services where digital signatures usually serve as irrefutable cryptographic evidence for dispute resolution, trusted time-stamping and certificate revocation services, although very costly in practice, must be available, to prevent big loss due to compromising of the signing key. In [12], a new concept called intrusion-resilient signature was proposed to get rid of trusted time-stamping and certificate revocation services and a concrete scheme was presented. In this paper, we put forward a new scheme that can achieve the same effect in a much more efficient way. In our scheme, forward-secure signature serves as a building block that enables signature …

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An Efficient Public-Key Framework, Jianying Zhou, Feng Bao, Robert H. Deng Oct 2003

An Efficient Public-Key Framework, Jianying Zhou, Feng Bao, Robert H. Deng

Research Collection School Of Computing and Information Systems

Public-key certificates play an important role in binding the public key with the identity of the owner of the corresponding private key. A certificate might be revoked before its scheduled expiry date by the issuing CA. Efficient and timely distribution of certificate revocation information is a big challenge facing the PKI providers. Existing certificate revocation schemes place a considerable processing, communication, and storage overheads on the CA as well as the relying parties. To improve the current situation, we propose a revocation-free public-key framework, in which the maximum lifetime of a certificate is divided into short periods and the certificate …

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Security Remarks On A Group Signature Scheme With Member Deletion, Guilin Wang, Feng Bao, Jianying Zhou, Robert H. Deng Oct 2003

Security Remarks On A Group Signature Scheme With Member Deletion, Guilin Wang, Feng Bao, Jianying Zhou, Robert H. Deng

Research Collection School Of Computing and Information Systems

A group signature scheme allows a group member of a given group to sign messages on behalf of the group in an anonymous and unlinkable fashion. In case of a dispute, however, a designated group manager can reveal the signer of a valid group signature. Based on the Camenisch-Michels group signature scheme, Kim, Lim and Lee proposed the first group signature scheme with a member deletion procedure at ICISC 2000. Their scheme is very efficient in both communication and computation aspects. Unfortunately, their scheme is insecure. In this paper, we first identify an effective way that allows any verifier to …

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Variations Of Diffie-Hellman Problem, Feng Bao, Robert H. Deng, Huafei Zhu Oct 2003

Variations Of Diffie-Hellman Problem, Feng Bao, Robert H. Deng, Huafei Zhu

Research Collection School Of Computing and Information Systems

This paper studies various computational and decisional Diffie-Hellman problems by providing reductions among them in the high granularity setting. We show that all three variations of computational Diffie-Hellman problem: square Diffie-Hellman problem, inverse Diffie-Hellman problem and divisible Diffie-Hellman problem, are equivalent with optimal reduction. Also, we are considering variations of the decisional Diffie-Hellman problem in single sample and polynomial samples settings, and we are able to show that all variations are equivalent except for the argument DDH ⇐ SDDH. We are not able to prove or disprove this statement, thus leave an interesting open problem. Keywords: Diffie-Hellman problem, Square Diffie-Hellman …

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Multi-Agent Coalition Via Autonomous Price Negotiation In A Real-Time Web Environment, Hoong Chuin Lau, Wei Sian Lim Oct 2003

Multi-Agent Coalition Via Autonomous Price Negotiation In A Real-Time Web Environment, Hoong Chuin Lau, Wei Sian Lim

Research Collection School Of Computing and Information Systems

In e-marketplaces, customers specify job requests in real-time and agents form coalitions to service them. This paper proposes a protocol for self-interested agents to negotiate prices in forming successful coalitions. We propose and experiment with two negotiation schemes: one allows information sharing while the other does not.

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Adaptive Collusion Attack To A Block Oriented Watermarking Scheme, Yongdong Wu, Robert H. Deng Oct 2003

Adaptive Collusion Attack To A Block Oriented Watermarking Scheme, Yongdong Wu, Robert H. Deng

Research Collection School Of Computing and Information Systems

In this paper, we propose an adaptive collusion attack to a block oriented watermarking scheme [1]. In this attack, traitors conspire to selectively manipulate watermarked blocks to remove the watermark information. To this end, the traitors compare the watermarked blocks generated from the same original block. If two watermarked block are not equal, they average these two blocks to generate a pirated block. Then, replace the watermarked blocks with the pirated blocks so as to build a pirated image. The pirated image has no watermark but has much higher quality than watermarked images. We also give a theoretical analysis on …

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High-Performance Architectures For Ip-Based Multihop 802.11 Networks, Arup Acharya, Archan Misra, Sorav Bansal Oct 2003

High-Performance Architectures For Ip-Based Multihop 802.11 Networks, Arup Acharya, Archan Misra, Sorav Bansal

Research Collection School Of Computing and Information Systems

The concept of a forwarding node, which receives packets from upstream nodes and then transmits these packets to downstream nodes, is a key element of any multihop network, wired or wireless. While high-speed IP router architectures have been extensively studied for wired networks, the concept of a "wireless IP router" has not been addressed so far. We examine the limitations of the IEEE 802.11 MAC protocol in supporting a low-latency and high-throughput IP datapath comprising multiple wireless LAN hops. We first propose a wireless IP forwarding architecture that uses MPLS with modifications to 802.11 MAC to significantly improve packet forwarding …

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Automatic Video Summarization By Graph Modeling, Chong-Wah Ngo, Yu-Fei Ma, Hong-Jiang Zhang Oct 2003

Automatic Video Summarization By Graph Modeling, Chong-Wah Ngo, Yu-Fei Ma, Hong-Jiang Zhang

Research Collection School Of Computing and Information Systems

We propose a unified approach for summarization based on the analysis of video structures and video highlights. Our approach emphasizes both the content balance and perceptual quality of a summary. Normalized cut algorithm is employed to globally and optimally partition a video into clusters. A motion attention model based on human perception is employed to compute the perceptual quality of shots and clusters. The clusters, together with the computed attention values, form a temporal graph similar to Markov chain that inherently describes the evolution and perceptual importance of video clusters. In our application, the flow of a temporal graph is …

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Design Of Antiresonant-Reflecting Optical Waveguide-Type Vertical-Coupled Surface-Emitting Lasers Using Transfer Matrix Method, Chyng Wen Tee, C. C. Tan, S. F. Yu Sep 2003

Design Of Antiresonant-Reflecting Optical Waveguide-Type Vertical-Coupled Surface-Emitting Lasers Using Transfer Matrix Method, Chyng Wen Tee, C. C. Tan, S. F. Yu

Research Collection Lee Kong Chian School Of Business

A simple transfer matrix method is proposed to calculate the radiation losses of a cylindrical antiresonant-reflecting optical waveguide (ARROW). It is found that the planar approximation underestimates the radiation losses but overestimates the design tolerance of the ARROW-type vertical-cavity surface-emitting lasers (VCSELs). An iteration technique, which is incorporated with the transfer matrix method, is also developed to design ARROW-type VCSELs for minimum radiation losses in a more effective manner.

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On Mining Group Patterns Of Mobile Users, Yida Wang, Ee Peng Lim, San-Yih Hwang Sep 2003

On Mining Group Patterns Of Mobile Users, Yida Wang, Ee Peng Lim, San-Yih Hwang

Research Collection School Of Computing and Information Systems

In this paper, we present a group pattern mining approach to derive the grouping information of mobile device users based on the spatio-temporal distances among them. Group patterns of users are determined by a distance threshold and a minimum duration. To discover group patterns, we propose the AGP and VG-growth algorithms that are derived from the Apriori and FP-growth algorithms respectively. We further evaluate the efficiencies of these two algorithms using synthetically generated user movement data.

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Ssm: Fast Construction Of The Optimized Segment Support Map, Kok-Leong Ong, Wee-Keong Ng, Ee Peng Lim Sep 2003

Ssm: Fast Construction Of The Optimized Segment Support Map, Kok-Leong Ong, Wee-Keong Ng, Ee Peng Lim

Research Collection School Of Computing and Information Systems

Computing the frequency of a pattern is one of the key operations in data mining algorithms. Recently, the Optimized Segment Support Map (OSSM) was introduced as a simple but powerful way of speeding up any form of frequency counting satisfying the monotonicity condition. However, the construction cost to obtain the ideal OSSM is high, and makes it less attractive in practice. In this paper, we propose the FSSM, a novel algorithm that constructs the OSSM quickly using a FP-Tree. Given a user-defined segment size, the FSSM is able to construct the OSSM at a fraction of the time required by …

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Solving Multi-Objective Multi-Constrained Optimization Problems Using Hybrid Ants System And Tabu Search, Hoong Chuin Lau, Min Kwang Lim, Wee Chong Wan, Hui Wang, Xiaotao Wu Aug 2003

Solving Multi-Objective Multi-Constrained Optimization Problems Using Hybrid Ants System And Tabu Search, Hoong Chuin Lau, Min Kwang Lim, Wee Chong Wan, Hui Wang, Xiaotao Wu

Research Collection School Of Computing and Information Systems

Many real-world optimization problems today are multi-objective multi-constraint generalizations of NP-hard problems. A classic case we study in this paper is the Inventory Routing Problem with Time Windows (IRPTW). IRPTW considers inventory costs across multiple instances of Vehicle Routing Problem with Time Windows (VRPTW). The latter is in turn extended with time-windows constraints from the Vehicle Routing Problem (VRP), which is extended with optimal fleet size objective from the single-objective Traveling Salesman Problem (TSP). While single-objective problems like TSP are solved effectively using meta-heuristics, it is not obvious how to cope with the increasing complexity systematically as the problem is …

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Towards A Role-Based Metadata Scheme For Educational Digital Libraries: A Case Study In Singapore, Dian Melati Md Ismail, Ming Yin, Yin-Leng Theng, Dion Hoe-Lian Goh, Ee Peng Lim Aug 2003

Towards A Role-Based Metadata Scheme For Educational Digital Libraries: A Case Study In Singapore, Dian Melati Md Ismail, Ming Yin, Yin-Leng Theng, Dion Hoe-Lian Goh, Ee Peng Lim

Research Collection School Of Computing and Information Systems

In this paper, we describe the development of an appropriate metadata scheme for GeogDL, a Web-based digital library application containing past-year examination resources for students taking a Singapore national examination in geography. The new metadata scheme was developed from established metadata schemes on education and e-learning. Initial evaluation showed that a role-based approach would be more viable, adapting to the different roles of teachers/educators and librarians contributing geography resources to GeogDL. The paper concludes with concrete implementation of the role-based metadata schema for GeogDL.

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A Generic Object-Oriented Tabu Search Framework, Hoong Chuin Lau, Wee Chong Wan, Xiaomin Jia Aug 2003

A Generic Object-Oriented Tabu Search Framework, Hoong Chuin Lau, Wee Chong Wan, Xiaomin Jia

Research Collection School Of Computing and Information Systems

Presently, most tabu search designers devise their applications without considering the potential of design and code reuse, which consequently prolong the development of subsequent applications. In this paper, we propose a software solution known as Tabu Search Framework (TSF), which is a generic C++ software framework for tabu search implementation. The framework excels in code recycling through the use of a welldesigned set of generic abstract classes that clearly define their collaborative roles in the algorithm. Additionally, the framework incorporates a centralized process and control mechanism that enhances the search with intelligence. This results in a generic framework that is …

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Performance Sensitivity And Fairness Of Ecn-Aware 'Modified Tcp', Archan Misra, Teunis Ott Aug 2003

Performance Sensitivity And Fairness Of Ecn-Aware 'Modified Tcp', Archan Misra, Teunis Ott

Research Collection School Of Computing and Information Systems

The paper discusses how Explicit Congestion Notification (ECN) can be used to devise a congestion control mechanism for the Internet, which is more rapidly reactive and allows best-effort flows to rapidly adjust to fluctuations in available capacity. Our ECN-mod protocol involves simple modifications to TCP behavior and leverages more aggressive marking-based router feedback.Simulations show that ECN-mod is better than TCP NewReno even for Web-style intermittent traffic sources, and makes the link utilization significantly less sensitive to the variation in the number of active flows. Simulations also show that, while ECN-mod flows obtain a larger portion of the available capacity than …

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Detection Of Documentary Scene Changes By Audio-Visual Fusion, Atulya Velivelli, Chong-Wah Ngo, Thomas S. Huang Jul 2003

Detection Of Documentary Scene Changes By Audio-Visual Fusion, Atulya Velivelli, Chong-Wah Ngo, Thomas S. Huang

Research Collection School Of Computing and Information Systems

The concept of a documentary scene was inferred from the audio-visual characteristics of certain documentary videos. It was observed that the amount of information from the visual component alone was not enough to convey a semantic context to most portions of these videos, but a joint observation of the visual component and the audio component conveyed a better semantic context. From the observations that we made on the video data, we generated an audio score and a visual score. We later generated a weighted audio-visual score within an interval and adaptively expanded or shrunk this interval until we found a …

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Video Clip Retrieval By Maximal Matching And Optimal Matching In Graph Theory, Yu-Xin Peng, Chong-Wah Ngo, Qing-Jie Dong, Zong-Ming Guo, Jian-Guo Xiao Jul 2003

Video Clip Retrieval By Maximal Matching And Optimal Matching In Graph Theory, Yu-Xin Peng, Chong-Wah Ngo, Qing-Jie Dong, Zong-Ming Guo, Jian-Guo Xiao

Research Collection School Of Computing and Information Systems

In this paper, a novel approach for automatic matching, ranking and retrieval of video clips is proposed. Motivated by the maximal and optimal matching theories in graph analysis, a new similarity measure of video clips is defined based on the representation and modeling of bipartite graph. Four different factors: visual similarity, granularity, interference and temporal order of shots are taken into consideration for similarity ranking. These factors are progressively analyzed in the proposed approach. Maximal matching utilizes the granularity factor to efficiently filter false matches, while optimal matching takes into account the visual, granularity and interference factors for similarity measure. …

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A Novel Scheme For Video Similarity Detection, Steven Hoi, Wei Wang, Michael R. Lyu Jul 2003

A Novel Scheme For Video Similarity Detection, Steven Hoi, Wei Wang, Michael R. Lyu

Research Collection School Of Computing and Information Systems

In this paper, a new two-phase scheme for video similarity detection is proposed. For each video sequence, we extract two kinds of signatures with different granularities: coarse and fine. Coarse signature is based on the Pyramid Density Histogram (PDH) technique and fine signature is based on the Nearest Feature Trajectory (NFT) technique. In the first phase, most of unrelated video data are filtered out with respect to the similarity measure of the coarse signature. In the second phase, the query video example is compared with the results of the first phase according to the similarity measure of the fine signature. …

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A Generic Object-Oriented Tabu Search Framework, Hoong Chuin Lau Jul 2003

A Generic Object-Oriented Tabu Search Framework, Hoong Chuin Lau

Research Collection School Of Computing and Information Systems

Presently, most tabu search designers devise their applications without considering the potential of design and code reuse, which consequently prolong the development of subsequent applications. In this paper, we propose a software solution known as Tabu Search Framework (TSF), which is a generic C++ software framework for tabu search implementation. The framework excels in code recycling through the use of a welldesigned set of generic abstract classes that clearly define their collaborative roles in the algorithm. Additionally, the framework incorporates a centralized process and control mechanism that enhances the search with intelligence. This results in a generic framework that is …

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Trifocal Morphing, Angus M. K. Siu, Ada S. K. Wan, Rynson W. H. Lau, Chong-Wah Ngo Jul 2003

Trifocal Morphing, Angus M. K. Siu, Ada S. K. Wan, Rynson W. H. Lau, Chong-Wah Ngo

Research Collection School Of Computing and Information Systems

Image morphing allows smooth transition between 2D images. However, one of the limitations of existing image morphing techniques is the lack of interaction - the viewpoints of the interpolated images are restrained to the line joining the optical centers of the source and the destination images. Another limitation of existing image morphing techniques is that shape warping often causes distortion due to barycentric mapping. In this paper, we present our trifocal morphing technique to address these problems. The new technique allows a user to change the viewpoint of the output images, i.e., increasing the degrees of freedom of interaction, and …

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Ladar-Based Detection And Tracking Of Moving Objects From A Ground Vehicle At High Speeds, Chieh-Chih Wang, Charles Thorpe, Arne Suppe Jun 2003

Ladar-Based Detection And Tracking Of Moving Objects From A Ground Vehicle At High Speeds, Chieh-Chih Wang, Charles Thorpe, Arne Suppe

Research Collection School Of Computing and Information Systems

Detection and tracking of moving objects (DATMO) in crowded urban areas from a ground vehicle at high speeds is difficult because of a wide variety of targets and uncertain pose estimation from odometry and GPS/DGPS. In this paper we present a solution of the simultaneous localization and mapping (SLAM) with DATMO problem to accomplish this task using ladar sensors and odometry. With a precise pose estimate and a surrounding map from SLAM, moving objects are detected without a priori knowledge of the targets. The interacting multiple model (IMM) estimation algorithm is used for modeling the motion of a moving object …

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Using Support Vector Machines For Terrorism Information Extraction, Aixin Sun, Myo-Myo Naing, Ee Peng Lim, Wai Lam Jun 2003

Using Support Vector Machines For Terrorism Information Extraction, Aixin Sun, Myo-Myo Naing, Ee Peng Lim, Wai Lam

Research Collection School Of Computing and Information Systems

Information extraction (IE) is of great importance in many applications including web intelligence, search engines, text understanding, etc. To extract information from text documents, most IE systems rely on a set of extraction patterns. Each extraction pattern is defined based on the syntactic and/or semantic constraints on the positions of desired entities within natural language sentences. The IE systems also provide a set of pattern templates that determines the kind of syntactic and semantic constraints to be considered. In this paper, we argue that such pattern templates restricts the kind of extraction patterns that can be learned by IE systems. …

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Adaptive Filters For Continuous Queries Over Distributed Data Stream, Chris Olston, Jing Jiang, Jennifer Widom Jun 2003

Adaptive Filters For Continuous Queries Over Distributed Data Stream, Chris Olston, Jing Jiang, Jennifer Widom

Research Collection School Of Computing and Information Systems

We consider an environment where distributed data sources continuously stream updates to a centralized processor that monitors continuous queries over the distributed data. Significant communication overhead is incurred in the presence of rapid update streams, and we propose a new technique for reducing the overhead. Users register continuous queries with precision requirements at the central stream processor, which installs filters at remote data sources. The filters adapt to changing conditions to minimize stream rates while guaranteeing that all continuous queries still receive the updates necessary to provide answers of adequate precision at all times. Our approach enables applications to trade …

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Strategyproof Mechanisms For Ad Hoc Network Formation, C. Jason Woodard, David C. Parkes Jun 2003

Strategyproof Mechanisms For Ad Hoc Network Formation, C. Jason Woodard, David C. Parkes

Research Collection School Of Computing and Information Systems

Agents in a peer-to-peer system typically have incentives to influence its network structure, either to reduce their costs or increase their ability to capture value. The problem is compounded when agents can join and leave the system dynamically. This paper proposes three economic mechanisms that offset the incentives for strategic behavior and facilitate the formation of networks with desirable global properties.

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Modeling Product Development As A System Design Game, C. Jason Woodard Jun 2003

Modeling Product Development As A System Design Game, C. Jason Woodard

Research Collection School Of Computing and Information Systems

A system design game is a model of a situation in which agents’ actions determine the structure of a system, which in turn affects the system’s value and the share of value that each agent may capture through bargaining or market competition. This paper describes a class of games in which agents design interdependent products, for example software programs, which may be complements or substitutes for each other. These relationships are epresented by an object called a design structure network (DSN). Depending on the modeler’s choice of allocation rules, agents may benefit from owning critical nodes in the DSN, corresponding …

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Parameter Optimization In The Regularized Shannon's Kernels Of Higher-Order Discrete Singular Convolutions, Wei Xiong, Yibao Zhao, Yun Gu May 2003

Parameter Optimization In The Regularized Shannon's Kernels Of Higher-Order Discrete Singular Convolutions, Wei Xiong, Yibao Zhao, Yun Gu

Research Collection Lee Kong Chian School Of Business

The δ-type discrete singular convolution (DSC) algorithm has recently been proposed and applied to solve kinds of partial differential equations (PDEs). With appropriate parameters, particularly the key parameter r in its regularized Shannon's kernel, the DSC algorithm can be more accurate than the pseudospectral method. However, it was previously selected empirically or under constrained inequalities without optimization. In this paper, we present a new energy-minimization method to optimize r for higher-order DSC algorithms. Objective functions are proposed for the DSC algorithm for numerical differentiators of any differential order with any discrete convolution width. Typical optimal parameters are also shown. The …

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Guest Editorial: Text And Web Mining, Ah-Hwee Tan, Philip S. Yu May 2003

Guest Editorial: Text And Web Mining, Ah-Hwee Tan, Philip S. Yu

Research Collection School Of Computing and Information Systems

Text mining and web mining are two interrelated fields that have received a lot of attention in recent years. Text mining [1, 2] is concerned with the analysis of very large document collections and the extraction of hidden knowledge from text-based data. Web mining [3] refers to the analysis and mining of all web-related data, including web content, hyperlink structure, and web access statistics.

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On Querying Geospatial And Georeferenced Metadata Resources In Gportal, Zehua Liu, Ee Peng Lim, Wee-Keong Ng, Dion Hoe-Lian Goh May 2003

On Querying Geospatial And Georeferenced Metadata Resources In Gportal, Zehua Liu, Ee Peng Lim, Wee-Keong Ng, Dion Hoe-Lian Goh

Research Collection School Of Computing and Information Systems

G-Portal is a web portal system providing a range of digital library services to access geospatial and georeferenced resources on the Web. Among them are the storage and query subsystems that provide a central repository of metadata resources organized under different projects. In GPortal, all metadata resources are represented in XML (Extensible Markup Language) and they are compliant to some resource schemas de.ned by their creators. The resource schemas are extended versions of a basic resource schema making it easy to accommodate all kinds of metadata resources while maintaining the portability of resource data. To support queries over the geospatial …

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Secure The Image-Based Simulated Telesurgery System, Yanjiang Yang, Zhenlan Wang, Feng Bao, Robert H. Deng May 2003

Secure The Image-Based Simulated Telesurgery System, Yanjiang Yang, Zhenlan Wang, Feng Bao, Robert H. Deng

Research Collection School Of Computing and Information Systems

Telemedicine services involve transmission of patient data over open computer network, and thus confront serious security challenges when the consequences are a matter of life and death. In this paper, we introduce an image-based simulated system for kyphoplasty telesurgery, wherein special attention is given to the fine-grained security implementation issues. Various security requirements are formalized and corresponding solutions are presented. Consequently, we implement the system to work in a secure way, while taking efficiency as a premier consideration.

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