7602869
Intergenerational Partnerships in the Design of a Digital Library of Geography Examination Resources
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.
16103436
Web-Based Parallel Simulation of AGVs Using Java and JINI
The vision of Computational Grids promises an exciting future for the distributed simulation community. In this project we make a small but practical step toward the grand vision of distributed simulation by using certain prevailing Internet technologies to enable access of simulation services anytime and anywhere. Specifically, this project focuses on accessing distributed simulation of AGVs (Automated Guided Vehicle) in container port operations through the World Wide Web. The objectives are to explore and address relevant issues, evaluate various approaches, demonstrate a workable version. We initially construct the AGV simulation system in an indirect communication model and identify its merits and demerits. Then, we explore the use of JINI technology for an efficient and robust direct communication architecture.
315976
Resource Annotation Framework in a Georeferenced and Geospatial Digital Library
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 flexible 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 services, such as visualization and classification, can be provided over the annotations since they are treated as first class objects. This paper mainly focuses on the design of the resource annotation framework.
7550543
A digital library for geography examination resources
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.
207320245
Hidden Markov models with factored Gaussian mixtures densities
We present a factorial representation of Gaussian mixture models for observation densities in hidden Markov models (HMMs), which uses the factorial learning in the HMM framework. We derive the reestimation formulas for estimating the factorized parameters by the Expectation Maximization (EM) algorithm and propose a novel method for initializing them. To compare the performances of the proposed models with that of the factorial hidden Markov models and HMMs, we have carried out extensive experiments which show that this modelling approach is effective and robust.
16560725
rCOS: A refinement calculus of object systems
This article presents a mathematical characterization of object-oriented concepts by defining an observation-oriented semantics for a relational object-based language with a rich variety of features including subtypes, visibility, inheritance, type casting, dynamic binding and polymorphism. The language can be used to specify object-oriented designs as well as programs. We present a calculus that supports both structural and behavioural refinement of object-oriented designs. The design calculus is based on the predicate logic in Hoare and He's Unifying Theories of Programming (UTP).
2853015
On the capacity of hybrid wireless networks
This paper involves the study of the throughput capacity of hybrid wireless networks. A hybrid network is formed by placing a sparse network of base stations in an ad hoc network. These base stations are assumed to be connected by a high-bandwidth wired network and act as relays for wireless nodes. They are not data sources nor data receivers. Hybrid networks present a tradeoff between traditional cellular networks and pure ad hoc networks in that data may be forwarded in a multihop fashion or through the infrastructure. It has been shown that the capacity of a random ad hoc network does not scale well with the number of nodes in the system. In this work, we consider two different routing strategies and study the scaling behavior of the throughput capacity of a hybrid network. Analytical expressions of the throughput capacity are obtained. For a hybrid network of n nodes and m base stations, the results show that if m grows asymptotically slower than √n, the benefit of adding base stations on capacity is insignificant. However, if m grows faster than √n, the throughput capacity increases linearly with the number of base stations, providing an effective improvement over a pure ad hoc network. Therefore, in order to achieve nonnegligible capacity gain, the investment in the wired infrastructure should be high enough.
12789585
A Secure Agent Architecture for Sensor Networks
Advances in sensor and wireless technologies will enable thousands, or even millions of small but smart sensors to be deployed for a wide range of monitoring applications. The sensor networks must be dynamically configurable and adaptive in order to response actively to events. Security must also be built into sensor networks at the very initial design stage to prevent any potential threats. This paper presents a design of a generic software architecture based on tiny active agents for sensor networks. The architecture has built-in security components. This architecture will significantly benefit the dynamic and secure deployment and configuration tasks of large sensor networks for various applications.
34520117
Print vs. electronic resources: A study of user perceptions, preferences, and use
The arrival and proliferation of electronic resources and digital libraries have a number of significant impacts on the use of print resources and traditional libraries. This study explores the extent to which graduate students in a metropolitan university setting use print and electronic resources. Reading preferences and use of print and electronic resources vary among different disciplines. Graduate students seem to expect a hybrid of print and electronic resources. They desire to meet their information needs through a mix of print and online resources, even though reasons for supplementing another type of resource differ. Circumstances that affect the selection of use between digital libraries and traditional libraries are also discussed.