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Research Collection School Of Computing and Information Systems

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Articles 6301 - 6330 of 6884

Full-Text Articles in Physical Sciences and Mathematics

Medoid Queries In Large Spatial Databases, Kyriakos Mouratidis, Dimitris Papadias, Spiros Papadimitriou Aug 2005

Medoid Queries In Large Spatial Databases, Kyriakos Mouratidis, Dimitris Papadias, Spiros Papadimitriou

Research Collection School Of Computing and Information Systems

Assume that a franchise plans to open k branches in a city, so that the average distance from each residential block to the closest branch is minimized. This is an instance of the k-medoids problem, where residential blocks constitute the input dataset and the k branch locations correspond to the medoids. Since the problem is NP-hard, research has focused on approximate solutions. Despite an avalanche of methods for small and moderate size datasets, currently there exists no technique applicable to very large databases. In this paper, we provide efficient algorithms that utilize an existing data-partition index to achieve low CPU …

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Geogdl: A Web-Based Approach To Geography Examination, Ee Peng Lim, Dion Hoe-Lian Goh, Yin-Leng Theng Aug 2005

Geogdl: A Web-Based Approach To Geography Examination, Ee Peng Lim, Dion Hoe-Lian Goh, Yin-Leng Theng

Research Collection School Of Computing and Information Systems

The traditional educational approach with students as passive recipients has been the subject of criticism. A constructivist learner-centered approach towards education has been argued to produce greater internalization and application of knowledge compared to the traditional teacher-centered, transmission-oriented approach. Nevertheless, contemporary instructional design models argue for the use and integration of both approaches especially in complex learning tasks. This paper describes GeogDL, a Web-based application developed above a digital library of geographical resources for Singapore students preparing to take a national examination in geography. GeogDL is unique in that it not only provides an environment for active learning, it also …

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Wmxml: A System For Watermarking Xml Data, Xuan Zhou, Hwee Hwa Pang, Kian-Lee Tan, Dhruv Mangla Aug 2005

Wmxml: A System For Watermarking Xml Data, Xuan Zhou, Hwee Hwa Pang, Kian-Lee Tan, Dhruv Mangla

Research Collection School Of Computing and Information Systems

As increasing amount of data is published in the form of XML, copyright protection of XML data is becoming an important requirement for many applications. While digital watermarking is a widely used measure to protect digital data from copyright offences, the complex and flexible construction of XML data poses a number of challenges to digital watermarking, such as re-organization and alteration attacks. To overcome these challenges, the watermarking scheme has to be based on the usability of data and the underlying semantics like key attributes and functional dependencies. In this paper, we describe WmXML, a system for watermarking XML documents. …

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Tuning Tabu Search Strategies Via Visual Diagnosis, Steven Halim, Wee Chong Wan, Hoong Chuin Lau Aug 2005

Tuning Tabu Search Strategies Via Visual Diagnosis, Steven Halim, Wee Chong Wan, Hoong Chuin Lau

Research Collection School Of Computing and Information Systems

While designing working metaheuristics can be straightforward, tuning them to solve the underlying combinatorial optimization problem well can be tricky. Several tuning methods have been proposed but they do not address the new aspect of our proposed classification of the metaheuristic tuning problem: tuning search strategies. We propose a tuning methodology based on Visual Diagnosis and a generic tool called Visualizer for Metaheuristics Development Framework(V-MDF) to address specifically the problem of tuning search (particularly Tabu Search) strategies. Under V-MDF, we propose the use of a Distance Radar visualizer where the human and computer can collaborate to diagnose the occurrence of …

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Dispatching Vehicles In A Mega Container Terminal, Ebru K. Bish, Frank Y. Chen, Thin Yin Leong, Barry L. Nelson, Jonathan W. C. Ng, David Simchi-Levi Aug 2005

Dispatching Vehicles In A Mega Container Terminal, Ebru K. Bish, Frank Y. Chen, Thin Yin Leong, Barry L. Nelson, Jonathan W. C. Ng, David Simchi-Levi

Research Collection School Of Computing and Information Systems

We consider a container terminal discharging and uploading containers to and from ships. The discharged containers are stored at prespecified storage locations in the terminal yard. Containers are moved between the ship area and the yard using a fleet of vehicles, each of which can carry one container at a time. The problem is to dispatch vehicles to the containers so as to minimize the total time it takes to serve a ship, which is the total time it takes to discharge all containers from the ship and upload new containers onto the ship. We develop easily implementable heuristic algorithms …

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Evaluation Of Time-Varying Availability In Multi-Echelon Inventory System With Combat Damage, Hoong Chuin Lau, Huawei Song Aug 2005

Evaluation Of Time-Varying Availability In Multi-Echelon Inventory System With Combat Damage, Hoong Chuin Lau, Huawei Song

Research Collection School Of Computing and Information Systems

The models for multi-echelon inventory systems in existing literatures predominantly address failures due to reliability in peacetime. In wartime or even peacetime operational scenarios, unexpected combat damage can cause a large number of systems to be heavily damaged, to the extent that they become irreparable. In this paper, we study a multi-echelon spare parts support system under combat damage, discuss the replenishment policy and propose an approximate method to evaluate the time-varying system performance operational availability considering the effect of passivation. Experiments show our model works well and efficiently against simulation.

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Deposit-Case Attack Against Secure Roaming, Guomin Yang, Duncan S. Wong, Xiaotie Deng Jul 2005

Deposit-Case Attack Against Secure Roaming, Guomin Yang, Duncan S. Wong, Xiaotie Deng

Research Collection School Of Computing and Information Systems

A secure roaming protocol involves three parties: a roaming user, a visiting foreign server and the user’s home server. The protocol allows the user and the foreign server to establish a session key and carry out mutual authentication with the help of the home server. In the mutual authentication, user authentication is generally done in two steps. First, the user claims that a particular server is his home server. Second, that particular server is called in by the foreign server for providing a ‘credential’ which testifies the user’s claim. We present a new attacking technique which allows a malicious server …

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Emd-Based Video Clip Retrieval By Many-To-Many Matching, Yuxin Peng, Chong-Wah Ngo Jul 2005

Emd-Based Video Clip Retrieval By Many-To-Many Matching, Yuxin Peng, Chong-Wah Ngo

Research Collection School Of Computing and Information Systems

This paper presents a new approach for video clip retrieval based on Earth Mover's Distance (EMD). Instead of imposing one-to-one matching constraint as in [11, 14], our approach allows many-to-many matching methodology and is capable of tolerating errors due to video partitioning and various video editing effects. We formulate clip-based retrieval as a graph matching problem in two stages. In the first stage, to allow the matching between a query and a long video, an online clip segmentation algorithm is employed to rapidly locate candidate clips for similarity measure. In the second stage, a weighted graph is constructed to model …

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Multibiometrics Based On Palmprint And Handgeometry, Xiao-Yong Wei, Dan Xu, Chong-Wah Ngo Jul 2005

Multibiometrics Based On Palmprint And Handgeometry, Xiao-Yong Wei, Dan Xu, Chong-Wah Ngo

Research Collection School Of Computing and Information Systems

This paper described our approach of multibiometrics in a single image. Firstly, a new method for capturing the key points of hand geometry is proposed. Then, we described our new method of palmprint feature extracting. By using projection transform and wavelet transform, this method considered both the global feature and local detail of a palmprint texture and proposed a new kind of palmprint feature. We also proposed a twice segmentation method for handgeometry feature extraction. In the processing of feature matching, we analyzed the weakness of the traditional Euclidian Square Norm method, and introduced an improved method. The experimental results …

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Co-Clustering Of Time-Evolving News Story With Transcript And Keyframe, Xiao Wu, Chong-Wah Ngo, Qing Li Jul 2005

Co-Clustering Of Time-Evolving News Story With Transcript And Keyframe, Xiao Wu, Chong-Wah Ngo, Qing Li

Research Collection School Of Computing and Information Systems

This paper presents techniques in clustering the same-topic news stories according to event themes. We model the relationship of stories with textual and visual concepts under the representation of bipartite graph. The textual and visual concepts are extracted respectively from speech transcripts and keyframes. Co-clustering algorithm is employed to exploit the duality of stories and textual-visual concepts based on spectral graph partitioning. Experimental results on TRECVID-2004 corpus show that the co-clustering of news stories with textual-visual concepts is significantly better than the co-clustering with either textual or visual concept alone.

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Hot Event Detection And Summarization By Graph Modeling And Matching, Yuxin Peng, Chong-Wah Ngo Jul 2005

Hot Event Detection And Summarization By Graph Modeling And Matching, Yuxin Peng, Chong-Wah Ngo

Research Collection School Of Computing and Information Systems

This paper proposes a new approach for hot event detection and summarization of news videos. The approach is mainly based on two graph algorithms: optimal matching (OM) and normalized cut (NC). Initially, OM is employed to measure the visual similarity between all pairs of events under the one-to-one mapping constraint among video shots. Then, news events are represented as a complete weighted graph and NC is carried out to globally and optimally partition the graph into event clusters. Finally, based on the cluster size and globality of events, hot events can be automatically detected and selected as the summaries of …

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Exploiting Belief Bounds: Practical Pomdps For Personal Assistant Agents, Pradeep Varakantham, Rajiv Maheswaran, Milind Tambe Jul 2005

Exploiting Belief Bounds: Practical Pomdps For Personal Assistant Agents, Pradeep Varakantham, Rajiv Maheswaran, Milind Tambe

Research Collection School Of Computing and Information Systems

Agents or agent teams deployed to assist humans often face the challenges of monitoring the state of key processes in their environment (including the state of their human users themselves) and making periodic decisions based on such monitoring. POMDPs appear well suited to enable agents to address these challenges, given the uncertain environment and cost of actions, but optimal policy generation for POMDPs is computationally expensive. This paper introduces three key techniques to speedup POMDP policy generation that exploit the notion of progress or dynamics in personal assistant domains. Policy computation is restricted to the belief space polytope that remains …

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Valuations Of Possible States (Vps): A Unifying Quantitative Framework For Evaluating Privacy In Collaboration, Rajiv T. Maheswaran, Jonathan Pearce, Pradeep Varakantham, Emma Bowring, Milind Tambe Jul 2005

Valuations Of Possible States (Vps): A Unifying Quantitative Framework For Evaluating Privacy In Collaboration, Rajiv T. Maheswaran, Jonathan Pearce, Pradeep Varakantham, Emma Bowring, Milind Tambe

Research Collection School Of Computing and Information Systems

For agents deployed in real-world settings, such as businesses, universities and research laboratories, it is critical that agents protect their individual users’ privacy when interacting with others entities. Indeed, privacy is recognized as a key motivating factor in design of several multiagent algorithms, such as distributed constraint optimization (DCOP) algorithms. Unfortunately, rigorous and general quantitative metrics for analysis and comparison of such multiagent algorithms with respect to privacy loss are lacking. This paper takes a key step towards developing a general quantitative model from which one can analyze and generate metrics of privacy loss by introducing the VPS (Valuations of …

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Approximate Strategic Reasoning Through Hierarchical Reduction Of Large Symmetric Games, Michael P. Wellman, Daniel M. Reeves, Kevin M. Lochner, Shih-Fen Cheng, Rahul Suri Jul 2005

Approximate Strategic Reasoning Through Hierarchical Reduction Of Large Symmetric Games, Michael P. Wellman, Daniel M. Reeves, Kevin M. Lochner, Shih-Fen Cheng, Rahul Suri

Research Collection School Of Computing and Information Systems

To deal with exponential growth in the size of a game with the number of agents, we propose an approximation based on a hierarchy of reduced games. The reduced game achieves savings by restricting the number of agents playing any strategy to fixed multiples. We validate the idea through experiments on randomly generated local-effect games. An extended application to strategic reasoning about a complex trading scenario motivates the approach, and demonstrates methods for game-theoretic reasoning over incompletely-specified games at multiple levels of granularity.

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Social Network Discovery By Mining Spatio-Temporal Events, Hady Lauw, Ee Peng Lim, Hwee Hwa Pang, Teck-Tim Tan Jul 2005

Social Network Discovery By Mining Spatio-Temporal Events, Hady Lauw, Ee Peng Lim, Hwee Hwa Pang, Teck-Tim Tan

Research Collection School Of Computing and Information Systems

Knowing patterns of relationship in a social network is very useful for law enforcement agencies to investigate collaborations among criminals, for businesses to exploit relationships to sell products, or for individuals who wish to network with others. After all, it is not just what you know, but also whom you know, that matters. However, finding out who is related to whom on a large scale is a complex problem. Asking every single individual would be impractical, given the huge number of individuals and the changing dynamics of relationships. Recent advancement in technology has allowed more data about activities of individuals …

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How Much You Watch, How Much You Pay, Yongdong Wu, Hwee Hwa Pang, Robert H. Deng Jul 2005

How Much You Watch, How Much You Pay, Yongdong Wu, Hwee Hwa Pang, Robert H. Deng

Research Collection School Of Computing and Information Systems

This paper presents a pay-video scheme that manages video stream, key stream and payment stream efficiently. In our scheme, the owner segments a video into fragments and encrypts them with independent keys. The keys are generated with a novel concept called as hash interval, where each hash interval discloses a range of numbers without disclosing any information on numbers outside of the range. The video fragments are then broadcast on one or more channels. A buyer can purchase the keys to decrypt any fragments and, within each fragment, any desired quality level. The accompanying payment protocol is integrated with the …

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Middleware Architecture For Evaluation And Selection Of 3rd Party Web Services For Service Providers, Dipanjan Chakraborty, Suraj K. Jaiswal, Archan Misra, Amit A. Nanavati Jul 2005

Middleware Architecture For Evaluation And Selection Of 3rd Party Web Services For Service Providers, Dipanjan Chakraborty, Suraj K. Jaiswal, Archan Misra, Amit A. Nanavati

Research Collection School Of Computing and Information Systems

This paper presents an architecture to facilitate efficient evaluation and selection of 3rd party Web services for service providers. Most service provider architectures have primarily focused on providing Web service front ends to legacy systems, aggregating and delivering services via workflows. These architectures primarily considered static business contracts between the service provider and its (Web-service enabled) business partners. This approach makes these architectures inflexible to variations in business requirement, partners' performance and customer requirements. Our architecture provides a flexible means for service providers to optimize business performance. Based on the historical performance, extant context, and optimising business rules, the appropriate …

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Strategic Assessment Of Information Security Maturity, Arcot Desai Narasimhalu, Dayasindhu Nagarajan, Raghavan Subramanian Jul 2005

Strategic Assessment Of Information Security Maturity, Arcot Desai Narasimhalu, Dayasindhu Nagarajan, Raghavan Subramanian

Research Collection School Of Computing and Information Systems

CXOs are becoming increasingly interested in the information security maturity of their enterprises. This paper presents a CXO dashboard that will allow better management of the information security resources in an enterprise.

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Synthesis Of Distributed Processes From Scenario-Based Specifications, Jun Sun, Jin Song Dong Jul 2005

Synthesis Of Distributed Processes From Scenario-Based Specifications, Jun Sun, Jin Song Dong

Research Collection School Of Computing and Information Systems

Given a set of sequence diagrams, the problem of synthesis is of deciding whether there exists a satisfying object system and if so, synthesize one automatically. It is crucial in the development of complex systems, since sequence diagrams serve as the manifestation of use cases and if synthesizable they could lead directly to implementation. It is even more interesting (and harder) if the synthesized object system is distributed. In this paper, we propose a systematic way of synthesizing distributed processes from Live Sequence Charts. The basic idea is to first construct a CSP specification from the LSC specification, and then …

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An Informatization Of Society Approach To E-Government: Analyzing Singapore’S E-Government Efforts, Calvin M. L. Chan, Yi Meng Lau Jul 2005

An Informatization Of Society Approach To E-Government: Analyzing Singapore’S E-Government Efforts, Calvin M. L. Chan, Yi Meng Lau

Research Collection School Of Computing and Information Systems

Despite the much publicized benefits of e-government, many countries are experiencing difficulty in yielding success in their e-government initiatives. Studies which adopt the national e-government initiatives as the unit of analysis remain largely rare. This paper aspires to provide an analysis of Singapore’s widely acclaimed success in the e-government effort at the national level to allow other countries to learn and gain from its experience. Using the ‘Conceptual Framework for the Informatization of Society’ in facilitating the data analysis, implications are drawn to offer insights for the considerations of e-government practitioners. Theoretical implications are also derived through positing that the …

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Descriptive Naming Of Context Data Providers, Norman H. Cohen, Paul Castro, Archan Misra Jul 2005

Descriptive Naming Of Context Data Providers, Norman H. Cohen, Paul Castro, Archan Misra

Research Collection School Of Computing and Information Systems

Much context data comes from mobile, transient, and unreliable sources. Such resources are best specified by descriptive names identifying what data is needed rather than which source is to provide it. The design of descriptive names has important consequences, but until now little attention has been focused on this problem. We propose a descriptive naming system for providers of context data that provides more flexibility and power than previous naming systems by classifying data providers into “provider kinds” that are organized in an evolving hierarchy of subkinds and superkinds. New provider kinds can be inserted in the hierarchy not only …

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Aggregate Nearest Neighbor Queries In Spatial Databases, Dimitris Papadias, Yufei Tao, Kyriakos Mouratidis, Chun Kit Hui Jun 2005

Aggregate Nearest Neighbor Queries In Spatial Databases, Dimitris Papadias, Yufei Tao, Kyriakos Mouratidis, Chun Kit Hui

Research Collection School Of Computing and Information Systems

Given two spatial datasets P (e.g., facilities) and Q (queries), an aggregate nearest neighbor (ANN) query retrieves the point(s) of P with the smallest aggregate distance(s) to points in Q. Assuming, for example, n users at locations q1,...qn, an ANN query outputs the facility p belongs to P that minimizes the sum of distances |pqi| for 1 is less than or equal to i is less than or equal to n that the users have to travel in order to meet there. Similarly, another ANN query may report the point p belongs to P that minimizes the maximum distance that …

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Breaking Public Key Cryptosystems On Tamper Resistant Devices In The Presence Of Transient Faults, Feng Bao, Robert H. Deng, Y. Han, A. Jeng, Arcot Desai Narasimhalu, T. Ngair Jun 2005

Breaking Public Key Cryptosystems On Tamper Resistant Devices In The Presence Of Transient Faults, Feng Bao, Robert H. Deng, Y. Han, A. Jeng, Arcot Desai Narasimhalu, T. Ngair

Research Collection School Of Computing and Information Systems

In this paper we present a method of attacking public-key cryptosystems (PKCs) on tamper resistant devices. The attack makes use of transient faults and seems applicable to many types of PKCs. In particular, we show how to attack the RSA, the E1Gamal signature scheme, the Schnorr signature scheme, and the DSA. We also present some possible methods to counter the attack.

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Learning Outcomes Oriented Assessment Methods In An Active Learning Environment, Arcot Desai Narasimhalu Jun 2005

Learning Outcomes Oriented Assessment Methods In An Active Learning Environment, Arcot Desai Narasimhalu

Research Collection School Of Computing and Information Systems

Singapore Management University uses interactive seminar style teaching in class rooms. Most of its students hail from Singapore and are generally new to active learning and constructive participation in the seminar style classes. This paper reports findings from a freshmen first term course titled IS 101: Seminar for ISM Majors.

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Efficient Anonymous Roaming And Its Security Analysis, Guomin Yang, Duncan S. Wong, Xiaotie Deng Jun 2005

Efficient Anonymous Roaming And Its Security Analysis, Guomin Yang, Duncan S. Wong, Xiaotie Deng

Research Collection School Of Computing and Information Systems

The Canetti-Krawczyk (CK) model uses resuable modular components to construct indistinguishability-based key exchange protocols. The reusability of modular protocol components makes it easier to construct and prove new protocols when compared with other provably secure approaches. In this paper, we build an efficient anonymous and authenticated key exchange protocol for roaming by using the modular approach under the CK-model. Our protocol requires only four message flows and uses only standard cryptographic primitives. We also propose a one-pass counter based MT-authenticator and show its security under the assumption that there exists a MAC which is secure against chosen message attack.

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A Semi-Supervised Active Learning Framework For Image Retrieval, Steven Hoi, Michael R. Lyu Jun 2005

A Semi-Supervised Active Learning Framework For Image Retrieval, Steven Hoi, Michael R. Lyu

Research Collection School Of Computing and Information Systems

Although recent studies have shown that unlabeled data are beneficial to boosting the image retrieval performance, very few approaches for image retrieval can learn with labeled and unlabeled data effectively. This paper proposes a novel semi-supervised active learning framework comprising a fusion of semi-supervised learning and support vector machines. We provide theoretical analysis of the active learning framework and present a simple yet effective active learning algorithm for image retrieval. Experiments are conducted on real-world color images to compare with traditional methods. The promising experimental results show that our proposed scheme significantly outperforms the previous approaches.

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Dsi: A Fully Distributed Spatial Index For Wireless Data Broadcast, Wang-Chien Lee, Baihua Zheng Jun 2005

Dsi: A Fully Distributed Spatial Index For Wireless Data Broadcast, Wang-Chien Lee, Baihua Zheng

Research Collection School Of Computing and Information Systems

Recent announcement of the MSN Direct Service has demonstrated the feasibility and industrial interest in utilizing wireless broadcast for pervasive information services. To support location-based services in wireless data broadcast systems, a distributed spatial index (called DSI) is proposed in this paper. DSI is highly efficient because it has a linear yet fully distributed structure that facilitates multiple search paths to be naturally mixed together by sharing links. Moreover, DSI is very resilient in error-prone wireless communication environments. Search algorithms for two classical location-based queries, window queries and kNN queries, based on DSI are presented. Performance evaluation of DSI shows …

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Conceptual Partitioning: An Efficient Method For Continuous Nearest Neighbor Monitoring, Kyriakos Mouratidis, Marios Hadjieleftheriou, Dimitris Papadias Jun 2005

Conceptual Partitioning: An Efficient Method For Continuous Nearest Neighbor Monitoring, Kyriakos Mouratidis, Marios Hadjieleftheriou, Dimitris Papadias

Research Collection School Of Computing and Information Systems

Given a set of objects P and a query point q, a k nearest neighbor (k-NN) query retrieves the k objects in P that lie closest to q. Even though the problem is well-studied for static datasets, the traditional methods do not extend to highly dynamic environments where multiple continuous queries require real-time results, and both objects and queries receive frequent location updates. In this paper we propose conceptual partitioning (CPM), a comprehensive technique for the efficient monitoring of continuous NN queries. CPM achieves low running time by handling location updates only from objects that fall in the vicinity of …

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On Assigning Place Names To Geography Related Web Pages, Wenbo Zong, Dan Wu, Aixin Sun, Ee Peng Lim, Dion Hoe-Lian Goh Jun 2005

On Assigning Place Names To Geography Related Web Pages, Wenbo Zong, Dan Wu, Aixin Sun, Ee Peng Lim, Dion Hoe-Lian Goh

Research Collection School Of Computing and Information Systems

In this paper, we attempt to give spatial semantics to web pages by assigning them place names. The entire assignment task is divided into three sub-problems, namely place name extraction, place name disambiguation and place name assignment. We propose our approaches to address these sub-problems. In particular, we have modified GATE, a well-known named entity extraction software, to perform place name extraction using a US Census gazetteer. A rule-based place name disambiguation method and a place name assignment method capable of assigning place names to web page segments have also been proposed. We have evaluated our proposed disambiguation and assignment …

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Evaluating G-Portal For Geography Learning And Teaching, Chew-Hung Chang, John G. Hedberg, Yin-Leng Theng, Ee Peng Lim, Tiong-Sa Teh, Dion Hoe-Lian Goh Jun 2005

Evaluating G-Portal For Geography Learning And Teaching, Chew-Hung Chang, John G. Hedberg, Yin-Leng Theng, Ee Peng Lim, Tiong-Sa Teh, Dion Hoe-Lian Goh

Research Collection School Of Computing and Information Systems

This paper describes G-Portal, a geospatial digital library of geographical assets, providing an interactive platform to engage students in active manipulation and analysis of information resources and collaborative learning activities. Using a G-Portal application in which students conducted a field study of an environmental problem of beach erosion and sea level rise, we describe a pilot study to evaluate usefulness and usability issues to support the learning of geographical concepts, and in turn teaching.

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