7304743
Proxy ecology - cooperative proxies with artificial life
In this paper, we propose a novel P2P cooperative proxy cache system using an individual-based model. We borrow the idea from an ecological system as well as economic systems to manage the cooperative proxies through data and information exchange among individual proxies. The data flow among proxy nodes creates artificial life for the cooperative proxies. The proxy servers with artificial life can automatically configure themselves into a virtual proxy graph. The aggregate effect of caching actions by individual peer proxies automatically distributes the Web document closer to the clients and balances the workload. Our simulation results show that the proposed proxy caching scheme tremendously improves the system performance. In addition, the individual-based design model ensures the simplicity and scalability of the cache system.
14997765
2PSM: an efficient framework for searching video information in a limited-bandwidth environment
Abstract. We present a novel technique, called 2-Phase Service Model, for streaming videos to home users in a limited-bandwidth environment. This scheme first delivers some number of non-adjacent data fragments to the client in Phase 1. The missing fragments are then transmitted in Phase 2 as the client is playing back the video. This approach offers many benefits. The isochronous bandwidth required for Phase 2 can be controlled within the capability of the transport medium. The data fragments received during Phase 1 can be used to provide an excellent preview of the video. They can also be used to facilitate VCR-style operations such as fast-forward and fast-reverse. Systems designed based on this method are less expensive because the fast-forward and fast-reverse versions of the video files are no longer needed. Eliminating these files also improves system performance because mapping between the regular files and their fast-forward and fast-reverse versions is no longer part of the VCR operations. Furthermore, since each client machine handles its own VCR-style interaction, this technique is very scalable. We provide simulation results to show that 2-Phase Service Model is able to handle VCR functions efficiently. We also implement a video player called {\em FRVplayer}. With this prototype, we are able to judge that the visual quality of the previews and VCR-style operations is excellent. These features are essential to many important applications. We discuss the application of FRVplayer in the design of a video management system, called VideoCenter. This system is intended for Internet applications such as digital video libraries.
7340804
Cooperative proxy caching for wireless base stations
This paper proposes a mobile cache model to facilitate the cooperative proxy caching in wireless base stations. This mobile cache model uses a network cache line to record the caching state information about a web document for effective data search and cache space management. Based on the proposed mobile cache model, a P2P cooperative proxy caching scheme is proposed to use a self-configured and self-managed virtual proxy graph (VPG), independent of the underlying wireless network structure and adaptive to the network and geographic environment changes, to achieve efficient data search, data cache and date replication. Based on demand, the aggregate effect of data caching, searching and replicating actions by individual proxy servers automatically migrates the cached web documents closer to the interested clients. In addition, a cache line migration (CLM) strategy is proposed to flow and replicate the heads of network cache lines of web documents associated with a moving mobile host to the new base station during the mobile host handoff. These replicated cache line heads provide direct links to the cached web documents accessed by the moving mobile hosts in the previous base station, thus improving the mobile web caching performance. Performance studies have shown that the proposed P2P cooperative proxy caching schemes significantly outperform existing caching schemes.
12807394
A novel data caching scheme for multimedia servers
Abstract In this paper, we propose a Bi-directional Fragmental Pipelining (BFP) technique and its variable buffer size data-caching scheme BFPV to reduce the disk I/O bandwidth requirement for multimedia servers. Our mathematical analysis shows that the BFP technique is superior to the traditional unidirectional pipelining technique in terms of memory buffer space requirement. We further demonstrate that the memory buffer management using BFPV is better than that of using the fixed buffer size approach BFPF. We have mathematically proved that BFPV saves more disk I/O bandwidth than BFPF does using the same memory buffer space. Our simulation results have quantitatively confirmed our analysis.
5981810
An efficient ontology comparison tool for semantic Web applications
With the growing access to heterogeneous and independent data repositories, determining the semantic difference of two ontologies is critical in information retrieval, information integration and semantic web applications. In this paper, we propose an ontology comparison tool based on a novel senses refinement algorithm, which builds a senses set to accurately represent the semantics of the input ontology. The senses refinement algorithm automatically extracts senses from the electronic lexical database WordNet (locally installed or online), removes unnecessary senses based on the relationship among the entity classes of the ontology, and specifies relations and constraints of the concepts in the refined senses set. The senses refinement converts the measurement of ontology difference into simple set operations based on set theory, thus ensures the efficiency and accuracy of the ontology comparison. Our experimental studies show that the proposed senses refinement algorithm outperforms the naive senses set construction algorithm in terms of efficiency and accuracy.
54104798
Data allocation algorithms for distributed video servers
13491789
Multimedia Support for Wireless W-CDMA with Dynamic Spreading
The emerging multimedia communication needs more support in operating systems in order to be successful over a wireless environment. The system needs to support a seamless integration (i.e., transparent application switching) of voice, audio and conventional data (e.g., e-mails, and ftp). It should also support multiple users with a guaranteed quality. In this paper, we investigate effective protocol design with dynamic spreading factors such that various QoS based on different traffic types can be provided. Increasing spreading factors can benefit the system because it will increase the desired signal strength linearly. The measured bit error rate can be reduced 75 times with a long spreading factor. By taking advantage of this benefit, we propose some middle-ware solutions to monitor the network load and switch the spreading factors dynamically based on the current load with multimedia traffic. These middle-ware solutions are implemented in mobile and base stations and experiments are performed to measure the actual system performance. The preliminary results indicate that our proposed system can always maintain a desired quality for all the voice connections. We further extend our protocol to guarantee a balanced support among different traffic types. While the voice communication is still guaranteed to be non-interrupted, the data traffic is proved to be served with reasonable response time by our proposed system.
14765514
Information Discovery, Extraction and Integration for the Hidden Web
In this paper, we report our initial investigations on the problems of automatically extracting data objects from a given hidden-web source (i.e., the web site with an HTML search form) and automatically assigning semantics to the extracted data. We also propose some future work to address the problem of information discovery and integration for hidden-web sources.
16046090
Nonlinear blind source separation using higher order statistics and a genetic algorithm
This paper presents a novel method for blindly separating unobservable independent source signals from their nonlinear mixtures. The demixing system is modeled using a parameterized neural network whose parameters can be determined under the criterion of independence of its outputs. Two cost functions based on higher order statistics are established to measure the statistical dependence of the outputs of the demixing system. The proposed method utilizes a genetic algorithm (GA) to minimize the highly nonlinear and nonconvex cost functions. The GA-based global optimization technique is able to obtain superior separation solutions to the nonlinear blind separation problem from any random initial values. Compared to conventional gradient-based approaches, the GA-based approach for blind source separation is characterized by high accuracy, robustness, and convergence rate. In particular, it is very suitable for the case of limited available data. Simulation results are discussed to demonstrate that the proposed GA-based approach is capable of separating independent sources from their nonlinear mixtures generated by a parametric separation model.
9285084
Tumor classification and marker gene prediction by feature selection and fuzzy c-means clustering using microarray data
BackgroundUsing DNA microarrays, we have developed two novel models for tumor classification and target gene prediction. First, gene expression profiles are summarized by optimally selected Self-Organizing Maps (SOMs), followed by tumor sample classification by Fuzzy C-means clustering. Then, the prediction of marker genes is accomplished by either manual feature selection (visualizing the weighted/mean SOM component plane) or automatic feature selection (by pair-wise Fisher's linear discriminant).ResultsThe proposed models were tested on four published datasets: (1) Leukemia (2) Colon cancer (3) Brain tumors and (4) NCI cancer cell lines. The models gave class prediction with markedly reduced error rates compared to other class prediction approaches, and the importance of feature selection on microarray data analysis was also emphasized.ConclusionsOur models identify marker genes with predictive potential, often better than other available methods in the literature. The models are potentially useful for medical diagnostics and may reveal some insights into cancer classification. Additionally, we illustrated two limitations in tumor classification from microarray data related to the biology underlying the data, in terms of (1) the class size of data, and (2) the internal structure of classes. These limitations are not specific for the classification models used.
35219345
Integrated architectural modeling and analysis for high-assurance command and control system design
A real-time architectural specification (RAS) approach and its application to command and control (C2) systems are presented. The objective is to establish a formal foundation that will enable us to integrate existing rich but fragmented formal techniques for system specification and verification into practical and scaleable formal engineering methods to support the design and development of highly reliable real-time distributed systems. The contribution of RAS is twofold; first, it provides a formal system that integrates the system's timing requirements and the propagation of the requirements into the process of architectural modeling and design and provides a systematic way to enforce that the requirements are met in every step of the design process. Second, it offers an incremental and more scalable approach for design modeling. These two features together make RAS a suitable model for the design of C2 systems. Based on these features, we further present an incremental method for verifying timing properties of a RAS model that helps to reduce the complexity of analysis both at a given design level or across different design levels.