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Articles 7081 - 7110 of 7446

Full-Text Articles in Physical Sciences and Mathematics

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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A Novel Approach For The Analysis Of High Frequency Vibrations, G. W. Wei, Yibao Zhao, Y. Xiang Oct 2002

A Novel Approach For The Analysis Of High Frequency Vibrations, G. W. Wei, Yibao Zhao, Y. Xiang

Research Collection Lee Kong Chian School Of Business

Despite much effort in the past few decades, the numerical prediction of high-frequency vibrations remains a challenging task to the engineering and scientific communities due to the numerical instability of existing computational methods. However, such prediction is of crucial importance to certain problems of pressing practical concern, as pointed out by Langley and Bardell (1998 The Aeronautical Journal102, 287-297). This paper introduces the discrete singular convolution (DSC) algorithm for the prediction and analysis of high-frequency vibration of structures. Both a beam and two-span plates are employed as test examples to demonstrate the capability of the DSC algorithm for high-frequency vibration …

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The Kpss Test With Seasonal Dummies, Sainan Jin, Sainan Jin Oct 2002

The Kpss Test With Seasonal Dummies, Sainan Jin, Sainan Jin

Research Collection School Of Economics

It is shown that the KPSS test for stationarity may be applied without change to regressions with seasonal dummies. In particular, the limit distribution of the KPSS statistic is the same under both the null and alternative hypotheses whether or not seasonal dummies are used.

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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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Cryptanalysis Of Some Hash Functions Based On Block Ciphers And Codes, Hongjun Wu, Feng Bao, Robert Huijie Deng Sep 2002

Cryptanalysis Of Some Hash Functions Based On Block Ciphers And Codes, Hongjun Wu, Feng Bao, Robert Huijie Deng

Research Collection School Of Computing and Information Systems

At PKC 2000, Inoue and Sakurai proposed some methods to design hash functions from block ciphers and codes (block codes and convolutional codes). They claimed that their hash functions are secure: 2(d-1)m/2 encryptions are necessary to find a collision, where d and m are the minimal distance of the code and the block size of block cipher, respectively. However, we show in this paper that a collision could be found with about a.2m encryptions, where a is a small number.

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Pickup And Delivery Problem With Time Windows: Algorithms And Test Case Generation, Hoong Chuin Lau, Zhe Liang Sep 2002

Pickup And Delivery Problem With Time Windows: Algorithms And Test Case Generation, Hoong Chuin Lau, Zhe Liang

Research Collection School Of Computing and Information Systems

In the pickup and delivery problem with time windows (PDPTW), vehicles have to transport loads from origins to destinations respecting capacity and time constraints. In this paper, we present a two-phase method to solve the PDPTW. In the first phase, we apply a novel construction heuristics to generate an initial solution. In the second phase, a tabu search method is proposed to improve the solution. Another contribution of this paper is a strategy to generate good problem instances and benchmarking solutions for PDPTW, based on Solomon' s benchmark test cases for VRPTW. Experimental results show that our approach yields very …

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A Label-Switching Packet Forwarding Architecture For Multi-Hop Wireless Lans, Arup Acharya, Archan Misra, Sorav Bansal Sep 2002

A Label-Switching Packet Forwarding Architecture For Multi-Hop Wireless Lans, Arup Acharya, Archan Misra, Sorav Bansal

Research Collection School Of Computing and Information Systems

A router in wired network typically requires multiple network interfaces to act as a router or a forwarding node. In an ad-hoc multi-hop wireless network on the other hand, any node with a wireless network interface card can operate as a router or a forwarding node, since it can receive a packet from a neighboring node, do a route lookup based on the packet's destination IP address, and then transmit the packet to another neighboring node using the same wireless interface. This paper investigates a combined medium access and next-hop address lookup based on fixed length labels (instead of IP …

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Dsc Analysis Of Rectangular Plates With Non-Uniform Boundary Conditions, Yibao Zhao, G. W. Wei Aug 2002

Dsc Analysis Of Rectangular Plates With Non-Uniform Boundary Conditions, Yibao Zhao, G. W. Wei

Research Collection Lee Kong Chian School Of Business

This paper introduces the discrete singular convolution (DSC) for the vibration analysis of rectangular plates with non-uniform and combined boundary conditions. A systematic scheme is proposed for the treatment of boundary conditions required in the proposed approach. The validity of the DSC approach for plate vibration is tested by using a large number of numerical examples that have a combination of simply supported, clamped and transversely supported (with non-uniform elastic rotational restraint) edges. The present results are in excellent agreement with those in the literature.

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Detection Of Slide Transition For Topic Indexing, Chong-Wah Ngo, Ting-Chuen Pong, Thomas S. Huang Aug 2002

Detection Of Slide Transition For Topic Indexing, Chong-Wah Ngo, Ting-Chuen Pong, Thomas S. Huang

Research Collection School Of Computing and Information Systems

This paper presents an automatic and novel approach in detecting the transitions of slides for video sequences of technical lectures. Our approach adopts a foreground vs background segmentation algorithm to separate a presenter from the projected electronic slides. Once a background template is generated, text captions are detected and analyzed. The segmented caption regions as well as background templates together provide salient visual cues to decide whether a slide is flipped and replaced. The partitioning of videos according to slide changes not only structure the content of video according to topics, but also facilitate the synchronization of video, audio and …

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Organizing And Personalizing Intelligence Gathering From The Web, Hwee-Leng Ong, Ah-Hwee Tan, Jamie Ng, Pan Hong, Qiu-Xiang Li Aug 2002

Organizing And Personalizing Intelligence Gathering From The Web, Hwee-Leng Ong, Ah-Hwee Tan, Jamie Ng, Pan Hong, Qiu-Xiang Li

Research Collection School Of Computing and Information Systems

In this paper, we describe how an integrated web‐based application, code‐named FOCI (Flexible Organizer for Competitive Intelligence), can help the knowledge worker in the gathering, organizing, tracking and dissemination of competitive intelligence (CI). It combines the use of a novel user‐configurable clustering, trend analysis and visualization techniques to manage information gathered from the web. FOCI allows its users to define and personalize the organization of the information clusters according to their needs and preferences into portfolios. These personalized portfolios created are saved and can be subsequently tracked and shared with other users. The paper runs through an example to show …

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Hcl: A Specification Language For Hierarchical Text Classification, Aixin Sun, Ee Peng Lim, Wee-Keong Ng Aug 2002

Hcl: A Specification Language For Hierarchical Text Classification, Aixin Sun, Ee Peng Lim, 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 paper, 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 …

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Integrating Local Search And Network Flow To Solve The Inventory Routing Problem, Hoong Chuin Lau, Q Liu, H. Ono Jul 2002

Integrating Local Search And Network Flow To Solve The Inventory Routing Problem, Hoong Chuin Lau, Q Liu, H. Ono

Research Collection School Of Computing and Information Systems

The inventory routing problem is one of important and practical problems in logistics. It involves the integration of inventory management and vehicle routing, both of which are known to be NP-hard. In this paper, we combine local search and network flows to solve the inventory management problem, by utilizing the minimum cost flow sub-solutions as a guiding measure for local search. We then integrate with a standard VRPTW solver to present experimental results for the overall inventory routing problem, based on instances extended from the Solomon benchmark problems.

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Digital Libraries To Knowledge Portals: Towards A Global Knowledge Portal For Secondary Schools In Singapore, Yin-Leng Theng, Dion Hoe-Lian Goh, Chu Keong Lee, Ee Peng Lim, Zehua Liu Jul 2002

Digital Libraries To Knowledge Portals: Towards A Global Knowledge Portal For Secondary Schools In Singapore, Yin-Leng Theng, Dion Hoe-Lian Goh, Chu Keong Lee, Ee Peng Lim, Zehua Liu

Research Collection School Of Computing and Information Systems

For digital libraries to remain relevant in the new millennium where the ability to manage knowledge is critical, this paper explores how digital libraries could strategically be evolved into knowledge portals to encapsulate knowledge creation, management, sharing and reusability, features evidently lacking in most conventional digital libraries. Two digital library scenarios of use in education are described and implemented as knowledge portals using G-Portal and the Greenstone software. We hope that the initial work carried out on these two portal-like DLs will eventually form part of a Global Knowledge Portal for Secondary Schools in Singapore. Keywords Digital libraries, information portals, …

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G-Portal : A Map-Based Digital Library For Distributed Geospatial And Georeferenced Resources, Ee Peng Lim, Dion Hoe-Lian Goh Jul 2002

G-Portal : A Map-Based Digital Library For Distributed Geospatial And Georeferenced Resources, Ee Peng Lim, Dion Hoe-Lian Goh

Research Collection School Of Computing and Information Systems

As the World Wide Web evolves into an immense information network, it is tempting to build new digital library services and expand existing digital library services to make use of web content. In this paper, we present the design and implementation of G-Portal, a web portal that aims to provide digital library services over geospatial and georeferenced content found on the World Wide Web. G-Portal adopts a map-based user interface to visualize and manipulate the distributed geospatial and georeferenced content. Annotation capabilities are supported, allowing users to contribute geospatial and georeferenced objects as well as their associated metadata. The other …

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A Digital Library For Geography Examination Resources, Lian-Heong Chua, Dion Hoe-Lian Goh, Zehua Liu, Ee Peng Lim, Rebecca Pei-Hui Ang Jul 2002

A Digital Library For Geography Examination Resources, Lian-Heong Chua, Dion Hoe-Lian Goh, Zehua Liu, Ee Peng Lim, Rebecca Pei-Hui Ang

Research Collection School Of Computing and Information Systems

We describe a Web-based application developed above a digital library of geographical resources for Singapore students preparing to take a national examination in geography. The application provides an interactive, non-sequential approach to learning that supplements textbooks.

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Fast Filter-And-Refine Algorithms For Subsequence Selection, Beng-Chin Ooi, Hwee Hwa Pang, Hao Wang, Limsoon Wong, Cui Yu Jul 2002

Fast Filter-And-Refine Algorithms For Subsequence Selection, Beng-Chin Ooi, Hwee Hwa Pang, Hao Wang, Limsoon Wong, Cui Yu

Research Collection School Of Computing and Information Systems

Large sequence databases, such as protein, DNA and gene sequences in biology, are becoming increasingly common. An important operation on a sequence database is approximate subsequence matching, where all subsequences that are within some distance from a given query string are retrieved. This paper proposes a filter-and-refine algorithm that enables efficient approximate subsequence matching in large DNA sequence databases. It employs a bitmap indexing structure to condense and encode each data sequence into a shorter index sequence. During query processing, the bitmap index is used to filter out most of the irrelevant subsequences, and false positives are removed in the …

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Leadership Antecedents Of Informal Knowledge Acquisition And Dissemination, Siu Loon Hoe, Steve Mcshane Jul 2002

Leadership Antecedents Of Informal Knowledge Acquisition And Dissemination, Siu Loon Hoe, Steve Mcshane

Research Collection School Of Computing and Information Systems

Knowledge management is emerging as one of the leading influences on an organisation’s survival and competitive advantage (Blumentritt & Johnston 1999). Knowledge management is concerned with the effective acquisition, sharing, storage and utilisation of knowledge (Huber 1991; Saffady 1998). Corporate leaders are increasingly aware of the notion that an organisation’s long-term survival depends on its ability to generate new knowledge and continuously learn from the environment. The importance of a superior organisational learning capability as a source of competitive advantage is a common refrain among both managers and scholars (e.g. Kohli & Jaworski 1990; Nonaka 1991; Quinn 1992; Slater & …

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Data Management In Location-Dependent Information Services: Challenges And Issues, Dik Lun Lee, Jianliang Xu, Baihua Zheng, Wang-Chien Lee Jul 2002

Data Management In Location-Dependent Information Services: Challenges And Issues, Dik Lun Lee, Jianliang Xu, Baihua Zheng, Wang-Chien Lee

Research Collection School Of Computing and Information Systems

Location-dependent information services have great promise for mobile and pervasive computing environments. They can provide local and nonlocal news, weather, and traffic reports as well as directory services. Before they can be implemented on a large scale, however, several research issues must be addressed.

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Combining Two Heuristics To Solve A Supply Chain Optimization Problem, Hoong Chuin Lau, Yuyue Song Jul 2002

Combining Two Heuristics To Solve A Supply Chain Optimization Problem, Hoong Chuin Lau, Yuyue Song

Research Collection School Of Computing and Information Systems

In this paper, we consider a real-life supply chain optimization problem concerned with supplying a product from multiple warehouses to multiple geographically dispersed retailers. Each retailer faces a deterministic and period-dependent demand over some finite planning horizon. The demand of each retailer is satisfied by the supply from some predetermined warehouse through a fleet of vehicles which are only available within certain time windows at each period. Our goal is to identify a combined inventory and routing schedule such that the system-wide total cost over the planning horizon is minimised. This problem in essence is an amalgamation of two classical …

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The Case For Cyber Foraging, Rajesh Balan, Jason Flinn, Mahadev Satyanarayanan, Shafeeq Sinnamohideen, Hen-I Yang Jul 2002

The Case For Cyber Foraging, Rajesh Balan, Jason Flinn, Mahadev Satyanarayanan, Shafeeq Sinnamohideen, Hen-I Yang

Research Collection School Of Computing and Information Systems

In this paper, we propose cyber foraging: a mechanism to augment the computational and storage capabilities of mobile devices. Cyber foraging uses opportunistically discovered servers in the environment to improve the performance of interactive applications and distributed file systems on mobile clients. We show how the performance of distributed file systems can be improved by staging data at these servers even though the servers are not trusted. We also show how the performance of interactive applications can be improved via remote execution. Finally, we present VERSUDS: a virtual interface to heteregeneous service discovery protocols that can be used to discover …

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Security Analysis And Improvement Of The Global Key Recovery System, Yanjiang Yang, Feng Bao, Robert H. Deng Jul 2002

Security Analysis And Improvement Of The Global Key Recovery System, Yanjiang Yang, Feng Bao, Robert H. Deng

Research Collection School Of Computing and Information Systems

Key recovery is a technology that allows the owner of encrypted data or a trusted third party to recover encrypted data, mostly by reconstructing lost decryption key. In [HLG99], Harn et al proposed a Global Key Recovery System (GKRS) that combines the functions of the key recovery authorities and the public key certification authorities (CAs). Among other features, user-dominance, i.e., a user is allowed to select his own public-private key pair and especially a public element for verifying the validity of the public-private key pair, is considered extremely important by [HLG99] for wide acceptance of GKRS. In this paper, we …

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Avoiding Congestion Collapse On The Internet Using Tcp Tunnels, Boon Peng Lee, Rajesh Krishna Balan, Jacob Lillykutty, Winston Seah, A. L. Ananda Jun 2002

Avoiding Congestion Collapse On The Internet Using Tcp Tunnels, Boon Peng Lee, Rajesh Krishna Balan, Jacob Lillykutty, Winston Seah, A. L. Ananda

Research Collection School Of Computing and Information Systems

This paper discusses the application of TCP tunnels on the Internet and how Internet traffic can benefit from the congestion control mechanism of the tunnels. Primarily, we show the TCP tunnels offer TCP-friendly flows protection from TCP-unfriendly traffic. TCP tunnels also reduce the many flows situation on the Internet to that of a few flows. In addition, TCP tunnels eliminate unnecessary packet loss in the core routers of the congested backbones, which waste precious bandwidth leading to congestion collapse due to unresponsive UDP flows. We finally highlight that the use of TCP tunnels can, in principle, help prevent certain forms …

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Levy Solutions For Vibration Of Multi-Span Rectangular Plates, Y. Xiang, Yibao Zhao, G. W. Wei Jun 2002

Levy Solutions For Vibration Of Multi-Span Rectangular Plates, Y. Xiang, Yibao Zhao, G. W. Wei

Research Collection Lee Kong Chian School Of Business

This paper presents the Levy method to investigate the vibration behaviour of multi-span rectangular plates. The Levy method is applicable and analytical for rectangular plates with at least two parallel simply supported edges. The continuity at an interface between two spans is maintained by imposing both the essential and natural boundary conditions along the interface. The impact of the internal line supports on the vibration behaviour of the plates is investigated by varying both the number of internal lines and the line positions. Results for the vibration of two- and three-span rectangular plates are presented, in which the first-known exact …

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Cryptanalysis Of Some Hash Functions Based On Block Ciphers And Codes, Hongjun Wu, Feng Bao, Robert H. Deng Jun 2002

Cryptanalysis Of Some Hash Functions Based On Block Ciphers And Codes, Hongjun Wu, Feng Bao, Robert H. Deng

Research Collection School Of Computing and Information Systems

At PKC 2000, Inoue and Sakurai proposed some methods to design hash functions from block ciphers and codes (block codes and convolutional codes). They claimed that their hash functions are secure: 2(d-1)m/2 encryptions are necessary to find a collision, where d and m are the minimal distance of the code and the block size of block cipher, respectively. However, we show in this paper that a collision could be found with about alpha*2m encryptions, where alpha is a small number.

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