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Articles 6511 - 6540 of 6884

Full-Text Articles in Physical Sciences and Mathematics

Maca-P: A Mac For Concurrent Transmissions In Multi-Hop Wireless Networks, Arup Acharya, Archan Misra, Sorav Bansal Mar 2003

Maca-P: A Mac For Concurrent Transmissions In Multi-Hop Wireless Networks, Arup Acharya, Archan Misra, Sorav Bansal

Research Collection School Of Computing and Information Systems

This paper presents the initial design and performance study of MACA-P, a RTS/CTS based MAC protocol that enables simultaneous transmissions in multihop ad-hoc wireless networks. Providing such low-cost multihop and high performance wireless access networks is an important enabler of pervasive computing. MACA-P is a set of enhancements to the 802.11 DCF that allows parallel transmissions in many situations when two neighboring nodes are either both receivers or both transmitters, but a receiver and a transmitter are not neighbors. Like 802.11, MACA-P contains a contention-based reservation phase prior to data transmission. However, the data transmission is delayed by a control …

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Adaptive Transmission Power For Optimal Energy Reliable Multi-Hop Wireless Communication, Suman Banerjee, Archan Misra Mar 2003

Adaptive Transmission Power For Optimal Energy Reliable Multi-Hop Wireless Communication, Suman Banerjee, Archan Misra

Research Collection School Of Computing and Information Systems

We define a transmission power adaptation-based routing technique that finds optimal paths for minimum energy reliable data transfer in multi-hop wireless networks. This optimal choice of the transmission power depends on the link distance between the two nodes and the channel characteristics. Typical energy efficient routing techniques use a transmission power such that the received signal power at the destination minimally exceeds a desired threshold signal strength level. In this paper we argue that such a choice of the transmission power does not always lead to optimal energy routes, since it does not consider differences in the receiver noise levels. …

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Hierarchical Text Classification Methods And Their Specification, Ee Peng Lim, Aixin Sun, Wee-Keong Ng Mar 2003

Hierarchical Text Classification Methods And Their Specification, Ee Peng Lim, Aixin Sun, Wee-Keong Ng

Research Collection School Of Computing and Information Systems

Hierarchical text classification refers to assigning text documents to the categories in a given category tree based on their content. With large number of categories organized as a tree, hierarchical text classification helps users to find information more quickly and accurately. Nevertheless, hierarchical text classification methods in the past have often been constructed in a proprietary manner. The construction steps often involve human efforts and are not completely automated. In this chapter, we therefore propose a specification language known as HCL (Hierarchical Classification Language). HCL is designed to describe a hierarchical classification method including the definition of a category tree …

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Motion Analysis And Segmentation Through Spatio-Temporal Slices Processing, Chong-Wah Ngo, Ting-Chuen Pong, Hong-Jiang Zhang Mar 2003

Motion Analysis And Segmentation Through Spatio-Temporal Slices Processing, Chong-Wah Ngo, Ting-Chuen Pong, Hong-Jiang Zhang

Research Collection School Of Computing and Information Systems

This paper presents new approaches in characterizing and segmenting the content of video. These approaches are developed based upon the pattern analysis of spatio-temporal slices. While traditional approaches to motion sequence analysis tend to formulate computational methodologies on two or three adjacent frames, spatio-temporal slices provide rich visual patterns along a larger temporal scale. In this paper, we first describe a motion computation method based on a structure tensor formulation. This method encodes visual patterns of spatio-temporal slices in a tensor histogram, on one hand, characterizing the temporal changes of motion over time, on the other hand, describing the motion …

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Comparing The Routing Energy Overheads Of Ad-Hoc Routing Protocols, Sorav Bansal, Rajeev Shorey, Archan Misra Mar 2003

Comparing The Routing Energy Overheads Of Ad-Hoc Routing Protocols, Sorav Bansal, Rajeev Shorey, Archan Misra

Research Collection School Of Computing and Information Systems

We use simulations to study the comparative routing overheads of three ad-hoc routing protocols, namely AODV, DSDV and DSR. In contrast to earlier studies, we focus exclusively on the energy consumption and not on other metrics such as the number of routing packets. In particular, we study the `range effects' of the three protocols, i.e., how changes to the transmission power and transmission radius affect the overall energy consumed by routing-related packets. Due to the broadcast nature of the wireless medium, the energy spent in packet receptions is almost as important as the transmission power; using the number of transmissions …

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Meeting The Software Engineering Challenges Of Adaptive Mobile Applications, Rajesh Krishna Balan, Joao Pedro Sousa, Mahadev Satyanarayanan Feb 2003

Meeting The Software Engineering Challenges Of Adaptive Mobile Applications, Rajesh Krishna Balan, Joao Pedro Sousa, Mahadev Satyanarayanan

Research Collection School Of Computing and Information Systems

A critical factor for the commercial success of mobile and task-specific devices is the fast turnaround time of software development. However, developing software for mobile devices is especially hard since applications need to be aware of and adapt to changing resources such as bandwidth and battery.

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On Quantitative Evaluation Of Clustering Systems, Ji He, Ah-Hwee Tan, Chew-Lim Tan, Sam-Yuan Sung Jan 2003

On Quantitative Evaluation Of Clustering Systems, Ji He, Ah-Hwee Tan, Chew-Lim Tan, Sam-Yuan Sung

Research Collection School Of Computing and Information Systems

Clustering refers to the task of partitioning unlabelled data into meaningful groups (clusters). It is a useful approach in data mining processes for identifying hidden patterns and revealing underlying knowledge from large data collections. The application areas of clustering, to name a few, include image segmentation, information retrieval, document classification, associate rule mining, web usage tracking, and transaction analysis.

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Instance Based Attribute Identification In Database Integration, Ee Peng Lim, Cecil Chua, Roger Hsiang-Li Chiang Jan 2003

Instance Based Attribute Identification In Database Integration, Ee Peng Lim, Cecil Chua, Roger Hsiang-Li Chiang

Research Collection School Of Computing and Information Systems

Most research on attribute identification in database integration has focused on integrating attributes using schema and summary information derived from the attribute values. No research has attempted to fully explore the use of attribute values to perform attribute identification. We propose an attribute identification method that employs schema and summary instance information as well as properties of attributes derived from their instances. Unlike other attribute identification methods that match only single attributes, our method matches attribute groups for integration. Because our attribute identification method fully explores data instances, it can identify corresponding attributes to be integrated even when schema information …

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Performance Measurement Framework For Hierarchical Text Classification, Ee Peng Lim, Aixin Sun, Wee-Keong Ng Jan 2003

Performance Measurement Framework For Hierarchical Text Classification, Ee Peng Lim, Aixin Sun, Wee-Keong Ng

Research Collection School Of Computing and Information Systems

Hierarchical text classification or simply hierarchical classification refers to assigning a document to one or more suitable categories from a hierarchical category space. In our literature survey, we have found that the existing hierarchical classification experiments used a variety of measures to evaluate performance. These performance measures often assume independence between categories and do not consider documents misclassified into categories that are similar or not far from the correct categories in the category tree. In this paper, we therefore propose new performance measures for hierarchical classification. The proposed performance measures consist of category similarity measures and distance-based measures that consider …

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Advances In Mobile Commerce Technologies, Ee Peng Lim, Keng Siau Jan 2003

Advances In Mobile Commerce Technologies, Ee Peng Lim, Keng Siau

Research Collection School Of Computing and Information Systems

No abstract provided.

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Trading Agents Competing: Performance, Progress And Market Effectiveness, Michael P. Wellman, Shih-Fen Cheng, Daniel M. Reeves, Kevin M. Lochner Jan 2003

Trading Agents Competing: Performance, Progress And Market Effectiveness, Michael P. Wellman, Shih-Fen Cheng, Daniel M. Reeves, Kevin M. Lochner

Research Collection School Of Computing and Information Systems

The annual trading agent competition offers agent designers a forum for evaluating programmed trading techniques in a challenging market scenario. TAC aims to spur research by enabling researchers to compare techniques on a common problem and build on each other's ideas. A fixed set of assumptions and environment settings facilitates communication of methods and results. As a multiyear event, TAC lets researchers observe trading agents' progress over time, in effect accelerating the evolution of an adapted population of traders. Given all the participant effort invested, it is incumbent on us to learn as much from the experience as possible. After …

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Semantic Exploration Of Lecture Videos, Edward Altman, Yu Chen, Wai Chong Low Dec 2002

Semantic Exploration Of Lecture Videos, Edward Altman, Yu Chen, Wai Chong Low

Research Collection School Of Computing and Information Systems

E-Learning is rapidly changing the way that universities and corporations offer education and training. In recent years, the acquisition and distribution of rich media content has been largely automated, However, existing applications are functionally and visually static and remain organized around the delivery media, rather than the knowledge representation and learning tasks of the student. The innovative approach of this system is the extraction of semantically meaningful structures in the lecture combined with text analysis to support task based queries. In this demonstration we will show this combination of pedagogical and content descriptions leads to novel forms of visualization and …

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Resource Annotation Framework In A Georeferenced And Geospatial Digital Library, Zehua Liu, Ee Peng Lim, Dion Hoe-Lian Goh Dec 2002

Resource Annotation Framework In A Georeferenced And Geospatial Digital Library, Zehua Liu, Ee Peng Lim, Dion Hoe-Lian Goh

Research Collection School Of Computing and Information Systems

G-Portal is a georeferenced and geospatial digital library that aims to identify, classify and organize geospatial and georeferenced resources on the web and to provide digital library services for these resources. Annotation service is supported in G-Portal to enable users to contribute content to the digital library. In this paper, we present a resource annotation framework for georeferenced and geospatial digital libraries and discuss its application in G-Portal. The framework is fiexible for managing annotations of heterogeneous web resources. It allows users to contribute not only the annotation content but also the schema of the annotations. Meanwhile, other digital library …

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A Data Mining Approach To Library New Book Recommendations, San-Yih Hwang, Ee Peng Lim Dec 2002

A Data Mining Approach To Library New Book Recommendations, San-Yih Hwang, Ee Peng Lim

Research Collection School Of Computing and Information Systems

In this paper, we propose a data mining approach to recommending new library books that have never been rated or borrowed by users. In our problem context, users are characterized by their demographic attributes, and concept hierarchies can be defined for some of these demographic attributes. Books are assigned to the base categories of a taxonomy. Our goal is therefore to identify the type of users interested in some specific type of books. We call such knowledge generalized profile association rules. In this paper, we propose a new definition of rule interestingness to prune away rules that are redundant and …

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On Clustering And Retrieval Of Video Shots Through Temporal Slices Analysis, Chong-Wah Ngo, Ting-Chuen Pong, Hong-Jiang Zhang Dec 2002

On Clustering And Retrieval Of Video Shots Through Temporal Slices Analysis, Chong-Wah Ngo, Ting-Chuen Pong, Hong-Jiang Zhang

Research Collection School Of Computing and Information Systems

Based on the analysis of temporal slices, we propose novel approaches for clustering and retrieval of video shots. Temporal slices are a set of two-dimensional (2-D) images extracted along the time dimension of an image volume. They encode rich set of visual patterns for similarity measure. In this paper, we first demonstrate that tensor histogram features extracted from temporal slices are suitable for motion retrieval. Subsequently, we integrate both tensor and color histograms for constructing a two-level hierarchical clustering structure. Each cluster in the top level contains shots with similar color while each cluster in bottom level consists of shots …

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Crystalclear: Active Visualization Of Association Rules, Hian-Huat Ong, Kok-Leong Ong, Wee-Keong Ng, Ee Peng Lim Dec 2002

Crystalclear: Active Visualization Of Association Rules, Hian-Huat Ong, Kok-Leong Ong, Wee-Keong Ng, Ee Peng Lim

Research Collection School Of Computing and Information Systems

Effective visualization is an important aspect of active data mining. In the context of association rules, this need has been driven by the large amount of rules produced from a run of the algorithm. To be able to address real user needs, the rules need to be summarized and organized so that it can be interpreted and applied in a timely manner. In this paper, we propose two visualization techniques that is an improvement over those used by existing data mining packages. In particular, we address the visualization of "differences" in the set of rules due to incremental changes in …

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Intergenerational Partnerships In The Design Of A Digital Library Of Geography Examination Resources, Yin-Leng Theng, Dion Hoe-Lian Goh, Ee Peng Lim, Zehua Liu, Natalie Lee-San Pang, Patricia Bao-Bao Wong, Lian-Heong Chua Dec 2002

Intergenerational Partnerships In The Design Of A Digital Library Of Geography Examination Resources, Yin-Leng Theng, Dion Hoe-Lian Goh, Ee Peng Lim, Zehua Liu, Natalie Lee-San Pang, Patricia Bao-Bao Wong, Lian-Heong Chua

Research Collection School Of Computing and Information Systems

This paper describes the engagement of intergenerational partners in the design of a digital library of geographical resources (GeogDL) to help prepare Singapore students for a national examination in geography. GeogDL is built on top of G-Portal, a digital library providing services over geospatial and georeferenced Web content. Scenario-based design and claims analysis were employed as a means of refinement to the initial design of the GeogDL prototype.

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Vdl: A Language For Active Mining Variants Of Association Rules, Kok-Leong Ong, Wee-Keong Ng, Ee Peng Lim Dec 2002

Vdl: A Language For Active Mining Variants Of Association Rules, Kok-Leong Ong, Wee-Keong Ng, Ee Peng Lim

Research Collection School Of Computing and Information Systems

The popularity of association rules has resulted in several variations being proposed. In each case, additional attributes in the data are considered so as to produce more informative rules. In the context of active mining, different types of rules may be required over a period of time due to knowledge needs or the availability of new attributes. The present approach is the ad-hoc development of algorithms for each variant of rules. This is time consuming and costly, and is a stumping block to the vision of active mining. We argue that knowledge needs and the changing characteristics of the data …

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Motion Retrieval By Temporal Slices Analysis, Chong-Wah Ngo, Chong-Wah Ngo, Hong-Jiang Zhang Dec 2002

Motion Retrieval By Temporal Slices Analysis, Chong-Wah Ngo, Chong-Wah Ngo, Hong-Jiang Zhang

Research Collection School Of Computing and Information Systems

In this papel; we investigate video shots retrieval based on the analysis of temporal slice images. Temporal slices are a set of2D images extracted along the time dimension of image sequences. They encode rich set of motion clues for shot similarity measure. Because motion is depicted as texture orientation in temporal slices, we utilize various texture features such as tensor histogram, Gabor feature, and the statistical feature of co-occurrence matrix extracted directly from slices for motion description and retrieval. In this way, motion retrieval can be treated in a similar way as texture retrieval problem. Experimental results indicate that the …

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The Capacity Of Multi-Hop Wireless Networks With Tcp Regulated Traffic, Sorav Bansal, Rajeev Shorey, Shobhit Chugh, Anurag Goel, Kapil Kumar, Archan Misra Nov 2002

The Capacity Of Multi-Hop Wireless Networks With Tcp Regulated Traffic, Sorav Bansal, Rajeev Shorey, Shobhit Chugh, Anurag Goel, Kapil Kumar, Archan Misra

Research Collection School Of Computing and Information Systems

We study the dependence of the capacity of multi-hop wireless networks on the transmission range of nodes in the network with TCP regulated traffic. Specifically, we examine the sensitivity of the capacity to the speed of the nodes and the number of TCP connections in an ad hoc network. By incorporating the notion of a minimal acceptable QoS metric (loss) for an individual session, we argue that the QoS-aware capacity is a more accurate model of the TCP-centric capacity of an ad-hoc network. We study the dependence of capacity on the source application (Telnet or FTP) and on the choice …

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Mining Of Correlated Rules In Genome Sequences, L. Lin, L. Wong, Tze-Yun Leong, P. S. Lai Nov 2002

Mining Of Correlated Rules In Genome Sequences, L. Lin, L. Wong, Tze-Yun Leong, P. S. Lai

Research Collection School Of Computing and Information Systems

With the huge amount of data collected by scientists in the molecular genetics community in recent years, there exists a need to develop some novel algorithms based on existing data mining techniques to discover useful information from genome databases. We propose an algorithm that integrates the statistical method, association rule mining, and classification rule mining in the discovery of allelic combinations of genes that are peculiar to certain phenotypes of diseased patients.

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Motion-Based Video Representation For Scene Change Detection, Chong-Wah Ngo, Ting-Chuen Pong, Hong-Jiang Zhang Nov 2002

Motion-Based Video Representation For Scene Change Detection, Chong-Wah Ngo, Ting-Chuen Pong, Hong-Jiang Zhang

Research Collection School Of Computing and Information Systems

In this paper, we present a new framework to automatically group similar shots into one scene, where a scene is generally referred to as a group of shots taken place in the same site. Two major components in this framework are based on the motion characterization and background segmentation. The former component leads to an effective video representation scheme by adaptively selecting and forming keyframes. The later is considered novel in that background reconstruction is incorporated into the detection of scene change. These two components, combined with the color histogram intersection, establish our basic concept on assessing the similarity of …

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Defending Against Redirect Attacks In Mobile Ip, Robert H. Deng, Jianying Zhou, Feng Bao Nov 2002

Defending Against Redirect Attacks In Mobile Ip, Robert H. Deng, Jianying Zhou, Feng Bao

Research Collection School Of Computing and Information Systems

The route optimization operation in Mobile IP Version 6 (MIPv6) allows direct routing from any correspondent node to any mobile node and thus eliminates the problem of "triangle routing" present in the base Mobile IP Version 4 (MIPv4) protocol. Route optimization, however, requires that a mobile node constantly inform its correspondent nodes about its new care-of addresses by sending them binding update messages. Unauthenticated or malicious binding updates open the door for intruders to perform redirect attacks, i.e., malicious acts which redirect traffic from correspondent nodes to locations chosen by intruders. How to protect binding update messages to defend against …

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Knowledge Discovery From Texts: A Concept Frame Graph Approach, Kanagasabai Rajaraman, Ah-Hwee Tan Nov 2002

Knowledge Discovery From Texts: A Concept Frame Graph Approach, Kanagasabai Rajaraman, Ah-Hwee Tan

Research Collection School Of Computing and Information Systems

We address the text content mining problem through a concept based framework by constructing a conceptual knowledge base and discovering knowledge therefrom. Defining a novel representation called the Concept Frame Graph (CFG), we propose a learning algorithm for constructing a CFG knowledge base from text documents. An interactive concept map visualization technique is presented for user-guided knowledge discovery from the knowledge base. Through experimental studies on real life documents, we observe that the proposed approach is promising for mining deeper knowledge.

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Predicting Bottleneck Bandwidth Sharing By Generalized Tcp Flows, Archan Misra, Teunis Ott, John Baras Nov 2002

Predicting Bottleneck Bandwidth Sharing By Generalized Tcp Flows, Archan Misra, Teunis Ott, John Baras

Research Collection School Of Computing and Information Systems

The paper presents a technique for computing the individual throughputs and the average queue occupancy when multiple TCP connections share a single bottleneck buffer. The bottleneck buffer is assumed to perform congestion feedback via randomized packet marking or drops. We first present a fixed point-based analytical technique to compute the mean congestion window sizes, the mean queue occupancy and the individual throughputs when the TCP flows perform idealized congestion avoidance. We subsequently extend the technique to analyze the case where TCP flows perform generalized congestion avoidance and demonstrate the use of this technique under the Assured Service model, where each …

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A Visual Tool For Building Logical Data Models Of Websites, Zehua Liu, Wee-Keong Ng, Feifei Li, Ee Peng Lim Nov 2002

A Visual Tool For Building Logical Data Models Of Websites, Zehua Liu, Wee-Keong Ng, Feifei Li, Ee Peng Lim

Research Collection School Of Computing and Information Systems

Information sources over the WWW contain a large amount of data organized according to different interests and values. Thus, it is important that facilities are there to enable users to extract information of interest in a simple and effective manner. To do this, We propose the Wiccap Data Model, an XML data model that maps Web information sources into commonly perceived logical models, so that information can be extracted automatically according to users' interests. To accelerate the creation of data models, we have implemented a visual tool, called the Mapping Wizard, to facilitate and automate the process of producing Wiccap …

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Web Classification Using Support Vector Machine, Aixin Sun, Ee Peng Lim Nov 2002

Web Classification Using Support Vector Machine, Aixin Sun, Ee Peng Lim

Research Collection School Of Computing and Information Systems

In web classification, web pages from one or more web sites are assigned to pre-defined categories according to their content. Since web pages are more than just plain text documents, web classification methods have to consider using other context features of web pages, such as hyperlinks and HTML tags. In this paper, we propose the use of Support Vector Machine (SVM) classifiers to classify web pages using both their text and context feature sets. We have experimented our web classification method on the WebKB data set. Compared with earlier Foil-Pilfs method on the same data set, our method has been …

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Cache Invalidation And Replacement Strategies For Location-Dependent Data In Mobile Environments, Baihua Zheng, Jianliang Xu, Dik Lun Lee Oct 2002

Cache Invalidation And Replacement Strategies For Location-Dependent Data In Mobile Environments, Baihua Zheng, Jianliang Xu, Dik Lun Lee

Research Collection School Of Computing and Information Systems

Mobile location-dependent information services (LDISs) have become increasingly popular in recent years. However, data caching strategies for LDISs have thus far received little attention. In this paper, we study the issues of cache invalidation and cache replacement for location-dependent data under a geometric location model. We introduce a new performance criterion, called caching efficiency, and propose a generic method for location-dependent cache invalidation strategies. In addition, two cache replacement policies, PA and PAID, are proposed. Unlike the conventional replacement policies, PA and PAID take into consideration the valid scope area of a data value. We conduct a series of simulation …

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Safe Robot Driving, Chuck Thorpe, Romuald Aufrere, Justin David Carlson, David Duggins, Terrence W. Fong, Jay Gowdy, John Kozar, Robert Maclachlan, Colin Mccabe, Christoph Mertz, Arne Suppe, Chieh Chih Wang, Teruko Yata Sep 2002

Safe Robot Driving, Chuck Thorpe, Romuald Aufrere, Justin David Carlson, David Duggins, Terrence W. Fong, Jay Gowdy, John Kozar, Robert Maclachlan, Colin Mccabe, Christoph Mertz, Arne Suppe, Chieh Chih Wang, Teruko Yata

Research Collection School Of Computing and Information Systems

The Navlab group at Carnegie Mellon University has a long history of development of automated vehicles and intelligent systems for driver assistance. The earlier work of the group concentrated on road following, cross-country driving, and obstacle detection. The new focus is on short-range sensing, to look all around the vehicle for safe driving. The current system uses video sensing, laser rangefinders, a novel light-stripe rangefinder, software to process each sensor individually, and a map-based fusion system. The complete system has been demonstrated on the Navlab 11 vehicle for monitoring the environment of a vehicle driving through a cluttered urban environment, …

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Personalized Classification For Keyword-Based Category Profiles, Aixin Sun, Ee Peng Lim, Wee-Keong Ng Sep 2002

Personalized Classification For Keyword-Based Category Profiles, Aixin Sun, Ee Peng Lim, Wee-Keong Ng

Research Collection School Of Computing and Information Systems

Personalized classification refers to allowing users to define their own categories and automating the assignment of documents to these categories. In this paper, we examine the use of keywords to define personalized categories and propose the use of Support Vector Machine (SVM) to perform personalized classification. Two scenarios have been investigated. The first assumes that the personalized categories are defined in a flat category space. The second assumes that each personalized category is defined within a pre-defined general category that provides a more specific context for the personalized category. The training documents for personalized categories are obtained from a training …

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