Recent experiments and analysis suggest that there are about 800 million publicly-indexable web pages. However, unlike books in a traditional library, web pages continue to change even after they are initially published by their authors and indexed by search engines. This paper describes preliminary data on and statistical analysis of the frequency and nature of web page modications. Using empirical models and a novel analytic metric of \up-to-dateness", we estimate the rate at which web search engines must re-index the web to remain current. Keywords: web dynamics, monitoring, document management 1 Introduction Since its inception scarcely a decade ago, the World Wide Web has become a popular vehicle for disseminating scientic, commercial and personal information. The web consists of individual pages linked to and from other pages through Hyper Text Markup Language (HTML) constructs. The web is patently decentralized. Web pages are created, maintained and modied at random t...

The problem of predicting a user's behavior on a web-site has gained importance due to the rapid growth of the world-wide-web and the need to personalize and influence a user's browsing experience. Markov models and their variations have been found well suited for addressing this problem. Of the different variations or Markov models it is generally found that higher-order Markov models display high predictive accuracies. However higher order models are also extremely complicated due to their large number of states that increases their space and runtime requirements. In this paper we present different techniques for intelligently selecting parts of different order Markov models so that the resulting model has a reduced state complexity and improved prediction accuracy. We have tested our models on various datasets and have found that their performance is consistently superior to that obtained by higher-order Markov models. Keywords: world wide web, web mining, Markov models, p...

Our access to information today is unprecedented in history. However, information depreciates in value as it gets older, and the problem of updating information to keep it current presents new design challenges for information providers and consumers. These issues lead to novel concepts and results in the context of the World Wide Web. We quantify what it means to for search engines to be \up-to-date" and estimate how often search engines must re-index the web to keep current with it changing pages and structure. Three weeks prior to the Soviet invasion of Czechoslovakia, Corona satellite imagery of the area showed no signs of imminent attack. By the time another round of imagery was available, it was too late to react; the invasion had already taken place. In a real sense, the information obtained by the satellite weeks earlier was no longer useful. The fact that information has a useful lifetime is well known in the intelligence community. On the other side of the Iron Curtain,...

... this article, we examine this issue by classifying and discussing a wide ranging set of Web metrics. We present the origins, measurement functions, formulations and comparisons of well-known Web metrics for quantifying Web graph properties, Web page significance, Web page similarity, search and retrieval, usage characterization and information theoretic properties. We also discuss how these metrics can be applied for improving Web information access and use.

Layered transmission has been proposed as a solution to video multicast over the Internet. Since the number of layers is limited, there are usually mismatches between the coarse-grained layer subscription rates and the heterogeneous and dynamic rate requirements from the receivers. Existing studies suggest that such mismatches can be reduced by the use of sender or/and receiver adaptations. In this paper, we present a formal study on the problem of sender adaptation, or dynamic layer rate allocation on the sender's side. Specifically, we study the optimization criteria for layer rate allocation, and propose a metric called Application-aware Fairness Index. This metric takes into consideration 1) the non-linear relation between the perceived video quality and the delivered bandwidth, and 2) the degree of fairness in terms of the receiver's satisfaction with heterogeneous bandwidth requirements. We then formulate the rate allocation into an optimization problem with the objective of maximizing the expected fairness index for all receivers in a session, and derive an efficient and scalable solution using dynamic programming. We further demonstrate that such an optimal sender rate allocation can be seamlessly integrated into an end-to-end adaptation protocol called HALM (Hybrid Adaptation Layered Multicast). This protocol takes advantage of the recent development in layered video coding, and is suitable for the current best-effort Internet.

Many modern information management tasks consist of an observer that must maintain current knowledge of a collection of changing information. The goal of this observer is to maintain acceptably accurate state estimates given limited observation resources, such as bandwidth, time, and storage. Good examples of such \observation problems" are found in any situation where bandwidth is limited and old observations become less useful over time. Two such examples are maintaining a search engine's index of the World Wide Web (WWW) and automated monitoring of multiple sensors. This thesis addresses the general observation problem by (1) devising a formal framework of what it means to be \up-to-date", (2) gathering empirical data about the web that allows us to apply this framework to an important setting, and (3) presenting algorithms for scheduling revisits to optimize formal performance measures. One year's worth of web page observations are analyzed to show how quickly and in what ways web ...

This document contains the draft version of the following paper: S.K. Gupta and A.K. Samuel. Integrating the market research with the product development process: A step towards design for profit. ASME Design for

A rational methodology is presented to predict the compressive strength of carbon/epoxy compression specimens and prototype production parts using the model presented by Barbero in the Journal of Composite Materials, Vol. 32, No.5/1998. The experimental technique is an adaptation of the optical method first proposed by Yurgartis (1987) and can be directly applied to actual development, quality control or failure investigation programs. There is very good agreement between actual and predicted compressive strength at –125F and room temperature. At 180F, the predicted strength is conservative. Aurora Flight Sciences provided the prototype production parts and partial funding under the “Material Characterization Study for UAV Wing Development” contract. The results of the material characterization study of two carbon/epoxy prepregs presented to Aurora Flight Sciences are also shown here. An extension of the method presented by Barbero is also proposed for laminates with average global misalignment, αG, in [+αG]n or [-αG]n stacking sequence. iii Acknowledgement I would like to express tremendous thanks to my advisor, Dr. Ever Barbero, for his guidance and support throughout this project. There were many difficult moments encountered in the testing program that could not be solved without Dr. Barbero’s help. Dr. Barbero drew upon many of his resources in order that we could complete the testing program. I would also like to thank Aurora Flight Sciences of West Virginia for allowing WVU MAE to take on the Material Characterization portion of the NASA program,

Static compilers use profiling to predict run-time program behavior. Generally, this requires multiple input sets to capture wide variations in run-time behavior. This is expensive in terms of resources and compilation time. We introduce a new mechanism, 2D-profiling, which profiles with only one input set and predicts whether the result of the profile would change significantly across multiple input sets. We use 2D-profiling to predict whether a branch’s prediction accuracy varies across input sets. The key insight is that if the prediction accuracy of an individual branch varies significantly over a profiling run with one input set, then it is more likely that the prediction accuracy of that branch varies across input sets. We evaluate 2D-profiling with the SPEC CPU 2000 integer benchmarks and show that it can identify input-dependent branches accurately. 1.

Many emerging distributed applications require the realtime processing of large amounts of data that are being updated continuously. Distributed stream processing systems offer a scalable and efficient means of in-network processing of such data streams. However, the large scale and the distributed nature of such systems, as well as the fluctuation of their load render it difficult to ensure that distributed stream processing applications meet their Quality of Service demands. We describe a decentralized framework for proactively predicting and alleviating hot-spots in distributed stream processing applications in real-time. We base our hot-spot prediction techniques on statistical forecasting methods, while for hot-spot alleviation we employ a non-disruptive component migration protocol. The experimental evaluation of our techniques, implemented in our Synergy distributed stream processing middleware over PlanetLab, using a real stream processing application operating on real streaming data, demonstrates high prediction accuracy and substantial performance benefits. 1.