17859913
Security in the online e-learning environment
This paper addresses the role of security in the collaborative e-learning environment, and in particular, the social aspects of security and the importance of identity. It represents a case study, completed in Nov 2004, which was conducted to test the sense of security that students experienced whilst using the wiki platform as a means of online collaboration in the tertiary education environment. Wikis, fully editable Web sites, are easily accessible, require no software and allow its contributors (in this case students) to feel a sense of responsibility and ownership. A comparison between two wiki studies will be made whereby one group employed user login and the other maintained anonymity throughout the course of the study. The results consider the democratic participation and evolution of the work requirements over time, which in fact ascertains the nonvalidity of administrative identification.
12866276
A Load Balancing Algorithm for Web Based Server Grids
Load balance is a critical issue in distributed systems, such as server grids. In this paper, we propose a Balanced Load Queue (BLQ) model, which combines the queuing theory and hydro-dynamic theory, to model load balance in server grids. Base on the BLQ model, we claim that if the system is in the state of global fairness, then the performance of the whole system is the best. We propose a load balanced algorithm based on the model: the algorithm tries its best to keep the system in the global fairness status using job deviation. We present three strategies: best node, best neighbour, and random selection, for job deviation. A number of experiments are conducted for the comparison of the three strategies, and the results show that the best neighbour strategy is the best among the proposed strategies. Furthermore, the proposed algorithm with best neighbour strategy is better than the traditional round robin algorithm in term of processing delay, and the proposed algorithm needs very limited system information and is robust.
41517658
Improving the Performance of Equalization in Communication Systems
In this paper, research on exploring the potential of several popular equalization techniques while overcoming their disadvantages has been conducted. First, extensive literature survey on equalization is conducted. The focus has been placed on several popular linear equalization algorithm such as the conventional least-mean-square (LMS) algorithm, the recursive least-squares (RLS) algorithm, the filtered-X LMS algorithm and their development. The approach in analysing the performance of the filtered-X LMS Algorithm, a heuristic method based on linear time-invariant operator theory is provided to analyse the robust performance of the filtered-X structure. It indicates that the extra filter could enhance the stability margin of the corresponding non filtered-X structure. To overcome the slow convergence problem while keeping the simplicity of the LMS based algorithms, an H2 optimal initialization is proposed.
42192006
Reducing the Bandwidth Requirements of P2P Keyword Indexing
This paper describes the design and evaluation of a federated, peer-to-peer indexing system, which can be used to integrate the resources of local systems into a globally addressable index using a distributed hash table. The salient feature of the indexing systems design is the efficient dissemination of term-document indices using a combination of duplicate elimination, leaf set forwarding and conventional techniques such as aggressive index pruning, index compression, and batching. Together these indexing strategies help to reduce the number of RPC operations required to locate the nodes responsible for a section of the index, as well as the bandwidth utilization and the latency of the indexing service. Using empirical observation we evaluate the performance benefits of these cumulative optimizations and show that these design trade-offs can significantly improve indexing performance when using a distributed hash table.
16723593
A parallel Euler approach for large-scale biological sequence assembly
Biological sequence assembly is an essential step for sequencing the genomes of organisms. Sequence assembly is very computing intensive especially for the large-scale sequence assembly. Parallel computing is an effective way to reduce the computing time and support the assembly for large amount of biological fragments. Euler sequence assembly algorithm is an innovative algorithm proposed recently. The advantage of this algorithm is that its computing complexity is polynomial and it provides a better solution to the notorious "repeat" problem. This paper introduces the parallelization of the Euler sequence assembly algorithm. Alt the Genome fragments generated by whole genome shotgun (WGS) will be assembled as a whole rather than dividing them into groups which may incurs errors due to the inaccurate group partition. The implemented system can be run on supercomputers, network of workstations or even network of PC computers. The experimental results have demonstrated the performance of our system.
19315936
Lease Based Addressing for Event-Driven Wireless Sensor Networks
Sensor Networks have applications in diverse fields. They can be deployed for habitat modeling, temperature monitoring and industrial sensing. They also find applications in battlefield awareness and emergency (first) response situations. While unique addressing is not a requirement of many data collecting applications of wireless sensor networks it is vital for the success of applications such as emergency response. Data that cannot be associated with a specific node becomes useless in such situations. In this work we propose an addressing mechanism for event-driven wireless sensor networks. The proposed scheme eliminates the need for network wide Duplicate Address Detection (DAD) and enables reuse of addresses.
12677842
ADAM: another database of abbreviations in MEDLINE
MOTIVATION
Abbreviations are an important type of terminology in the biomedical domain. Although several groups have already created databases of biomedical abbreviations, these are either not public, or are not comprehensive, or focus exclusively on acronym-type abbreviations. We have created another abbreviation database, ADAM, which covers commonly used abbreviations and their definitions (or long-forms) within MEDLINE titles and abstracts, including both acronym and non-acronym abbreviations.


RESULTS
A model of recognizing abbreviations and their long-forms from titles and abstracts of MEDLINE (2006 baseline) was employed. After grouping morphological variants, 59 405 abbreviation/long-form pairs were identified. ADAM shows high precision (97.4%) and includes most of the frequently used abbreviations contained in the Unified Medical Language System (UMLS) Lexicon and the Stanford Abbreviation Database. Conversely, one-third of abbreviations in ADAM are novel insofar as they are not included in either database. About 19% of the novel abbreviations are non-acronym-type and these cover at least seven different types of short-form/long-form pairs.


AVAILABILITY
A free, public query interface to ADAM is available at http://arrowsmith.psych.uic.edu, and the entire database can be downloaded as a text file.
33519597
A system for managing remote procedure call transactions
Abstract This paper describes the design and implementation of a remote procedure call (RFC) transaction manager. The structures and constructions of RFC-based systems have been widely discussed, yet how to manage the RFC transactions by using these existing structures and constructions remains unclear. We have designed a system for managing RFC transactions based on our RFC transaction model. The system is designed at first to manage single RFC transactions. It is then expanded to manage parallel RFC transactions as well. Some properties of the system are described. We also present some descriptions of the preliminary implementation of our RFC transaction manager.
17849791
A tool for layered analysing and understanding of distributed programs
Distributed programs are harder to analyse and understand than sequential programs for a number of reasons. First, a distributed program consists of many entities at different levels of abstraction. Second, communication among the entities of a distributed program may happen concurrently and nondeterministically. To be able to analyse these entities and the communication events among them is therefore essential for understanding any distributed program. This paper describes a tool for assisting the analysis and understanding of distributed programs. The tool analyses the entities and communication events of a distributed program at four levels of abstraction. At the highest level, the tool displays the communication relationships between programs (e.g. server and client programs). At the second level, the communication between processes is displayed. At the third level, the communication between events is displayed. The fourth level is the lowest: it uses a text editor to show the relevant statements that carry out the communication. The tool has been used in the teaching of courses related to distributed computing since 1993.
1954273
An architecture for building reliable distributed object-based systems
This paper proposes an architecture for designing fault-tolerant distributed object systems. The proposed architecture attempts to bring advances in client-server, remote procedure call, reliable group communication, and object orientation technologies under a unified architecture to ease application developers' work of building reliable distributed systems. The resulting application systems should be enhanced with modularity and flexibility.
62686547
Estimation of the size and location of multiple area light sources
Most illuminant estimation algorithms worked on point light sources or directional light sources. Little attempt has been made, however, to estimate area light sources. In this paper, we present a novel scheme that estimates the size and location of multiple area light sources using a set of stereo images of a sphere with a shiny surface. The parameters of the area light source are estimated by a novel algorithm which minimizes the matching error between the corresponding specular patches. Experiments on real images show that our method is accurate and robust in estimating the parameters of the area light source.