14951106
A grid-based system for microbial genome comparison and analysis
Genome comparison and analysis can reveal the structures and junctions of genome sequences of different species. As more genomes are sequenced, genomic data sources are rapidly increasing such that their analysis is beyond the processing capabilities of most research institutes. The grid is a powerful solution to support large-scale genomic data processing and genome analysis. This paper presents the Microbase project that is developing a grid-based system for genome comparison and analysis, and discusses the first implementation of the system (called MicrobaseLite). MicrobaseLite uses a scalable computing environment to support computationally intensive microbial genome comparison and analysis, employing state-of-the-art technologies of Web services, notification, comparative genomics and parallel computing. Microbase will support not only system-defined genome comparison and analysis but also user-defined, remotely conceived genome analysis.
14112050
Distributed particle simulation method on adaptive collaborative system
Abstract This paper presents a distributed N-body method based on an adaptive collaborative system model. The collaborative system is formed by the distributed objects on a distributed system. The system can be reconfigured during the computation to fully utilize the computing power of the networked hosts. The method is implemented in Java and RMI to support distributed computing in heterogeneous environment. A distributed tree structure is designed for communication-efficient computation of N-body method. The performance test shows satisfactory speedup and portability of the method on both homogeneous and heterogeneous clusters. The collaborative system model can be used in various applications and it is expandable to wide-area environment.
15800513
ClusterProbe: an open, flexible and scalable cluster monitoring tool
In this paper, we describe the ClusterProbe, an open, flexible, scalable, and Java-based cluster monitoring tool. The tool provides an open environment by developing a multiple-protocol communication interface that can be connected to various types of external accesses from the clients. ClusterProbe is flexible that the monitoring tool can be easily extended to adapt to the resource changes by using the Java-RMI mechanism. In addition, the design of ClusterProbe allows it to scale up to commodious capacity with its cascading hierarchical architecture. Several useful services are implemented based on ClusterProbe, including the visualization of cluster resource information in various form and cluster fault management. The tool has been used to assist the execution of a cluster-based search engine and a distributed N-body application. All experiments demonstrate high efficiency.
1335499
Dynamic configuration management in a graph-oriented Distributed Programming Environment
Dynamic configuration is a desirable property of a distributed system where dynamic modification and extension to the system and the applications are required. It allows the system configuration to be specified and changed while the system is executing. This paper describes a software platform that facilitates a novel approach to the dynamically configurable programming of parallel and distributed applications and systems. This platform is based on a graph-oriented model and it provides support for constructing reconfigurable distributed programs. We describe the design and implementation of a dynamic configuration manager for the graph-oriented distributed programming environment. The requirements and services for dynamic reconfiguration are identified. The architectural design of a dynamic configuration manager is presented, and a parallel virtual machine-based prototypical implementation of the manager, on a local area network of workstations, is described.
1423209
Scalable load balancing on distributed web servers using mobile agents
Distributed web servers on the immensely expanding Internet require high scalability and availability to provide efficient services to millions of clients on the web. To provide rapid responses to enormous number of client requests, load balancing is an important technique to evenly distribute the requests to web servers. In this paper, we propose a framework called Mobile Agent based LoaD balancing (MALD) that uses mobile agents technology to implement scalable load balancing on distributed web servers. The web servers can dispatch mobile agents to collect system-wide load information and accomplish load redistribution on all servers. Various load-balancing policies can be incorporated with versatile mobile agents in the framework. Compared with the traditional message-passing-based load-balancing methods, the mobile-agent-based approaches have the merits of high flexibility, low network traffic and high asynchrony. The performance evaluation demonstrates that the MALD framework provides a foundation to develop efficient load-balancing schemes on wide range of web server systems from cluster to the Internet.
14338621
A distributed object model for solving irregularly structured problems on cluster
This paper presents a distributed object model MOIDE (Multithreaded Object-oriented Infrastructure on Distributed Environment) for solving irregularly structured problems on cluster. The primary appeal of MOIDE is its flexible system structure that is adaptive to heterogeneous architecture of a cluster. MOIDE integrates the object-oriented and multithreaded methodologies to set up a unified computing environment. Both the shared-data access and remote messaging are incorporated in a two-layer communication mechanism for efficient inter-object communication with the common communication interface. MOIDE supports dynamic load balancing by its autonomous load scheduling technique. A runtime support system implements the MOIDE model as a platform-independent infrastructure for developing and executing irregularly structured applications. N-body, ray tracing, and conjugate gradient applications are implemented to illustrate the advantages of MOIDE model.
1430542
Reconfigurable resource scheduling
We consider a class of scheduling problems that we refer to as reconfigurable resource scheduling. This class of problems is motivated by emerging applications that involve dynamically allocating a large number of shared resources to a variety of services. We design efficient online algorithms for certain problems in this class. Our goal is to obtain constant competitive online algorithms where the online algorithm is given a constant factor advantage in terms of the number of resources. The main problem considered in this paper is as follows. The input is a sequence of requests, each of which is a set of unit jobs. Each job has a category, and needs to be processed within a fixed delay bound from its arrival, or else it is dropped and we incur a category-specific drop cost. A job of a given category can only be executed on a resource configured for that category. A resource can be reconfigured at any time at a fixed reconfiguration cost. Our main result is a constant competitive online algorithm for this problem, which is obtained by the following layered approach. First, we reduce our main problem to the special case in which all jobs arrive at integral multiples of the delay bound. Second, we reduce the latter problem to the special case of unit delay. Third, we reduce the unit-delay problem to a caching problem that we refer to as file caching with remote reads. Our solution to this caching problem generalizes certain existing work in the area of file caching.
61852216
Cross-Evaluation: A new model for information system evaluation
In this article, we introduce a new information system evaluation method and report on its application to a collaborative information seeking system, AntWorld. The key innovation of the new method is to use precisely the same group of users who work with the system as judges, a system we call Cross-Evaluation. In the new method, we also propose to assess the system at the level of task completion. The obvious potential limitation of this method is that individuals may be inclined to think more highly of the materials that they themselves have found and are almost certain to think more highly of their own work product than they do of the products built by others. The keys to neutralizing this problem are careful design and a corresponding analytical model based on analysis of variance. We model the several measures of task completion with a linear model of five effects, describing the users who interact with the system, the system used to finish the task, the task itself, the behavior of individuals as judges, and the self-judgment bias. Our analytical method successfully isolates the effect of each variable. This approach provides a successful model to make concrete the “three-realities” paradigm, which calls for “real tasks,” “real users,” and “real systems.” © 2006 Wiley Periodicals, Inc.
18826555
Transparent silica glasses containing single walled carbon nanotubes
Organic/inorganic matrix nanocomposites have been created using an acid catalyzed, tetraethyl orthosilicate-based sol-gel technique with single-walled carbon nanotubes (SWNTs). By utilizing nanotubes functionalized with the dendron methyl 3,5-di(methyltrigycoloxy)benzylic alcohol (IPEG), ultrasonic blending in the sol phase prior to gelation yields excellent dispersion characteristics of the nanotube phase. The glasses were densified by heating to 600 °C yielding 80% of theoretical density with little change in the optical appearance or behavior. These materials exhibited intrinsic Rayleigh scattering, suggesting near ideal dispersion. Nonlinear optical transmission was observed for 1064 and 532 nm light suggesting that the matrix has a strong broad band coupling to the optical field. Such composites allow for a host of applications based on the novel confinement properties of carbon nanotubes in a robust inorganic host.
17387040
Automated judgment of document qualities
The authors report on a series of experiments to automate the assessment of document qualities such as depth and objectivity. The primary purpose is to develop a quality-sensitive functionality, orthogonal to relevance, to select documents for an interactive question-answering system. The study consisted of two stages. In the classifier construction stage, nine document qualities deemed important by information professionals were identified and classifiers were developed to predict their values. In the confirmative evaluation stage, the performance of the developed methods was checked using a different document collection. The quality prediction methods worked well in the second stage. The results strongly suggest that the best way to predict document qualities automatically is to construct classifiers on a person-by-person basis.
47269670
Motion estimation for content adaptive video compression
A multistage motion estimation scheme is proposed. The scheme extracts video characteristics by first performing an online video analysis separately for foreground and background regions. Motion parameters are extracted and passed to the next stage. The next stage includes a mathematical model for the block distortion surface (BDS) that enables the algorithm to accordingly adjust its search technique. The search is performed on a precise search area adaptive to the statistical property of the motion vector prediction error. Due to its self-tuning property, not only does the proposed scheme adapt to scenes by yielding better visual quality but it also yields a lower computational complexity, compared with the other predictive motion estimation algorithms on standard benchmark sequences