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Recent advances in graph-based search techniques derived from Kleinberg's work [1] have been impressive. This paper further improves the graph-based search algorithm in two dimensions. Firstly, variants of Kleinberg's techniques do not take into account the semantics of the query string nor of the nodes being searched. As a result, polysemy of query words cannot be resolved. This paper presents an interactive query scheme utilizing the simple web ontology provided by the Open Directory Project to resolve meanings of a user query. Secondly, we extend a recently proposed personalized version of the Kleinberg algorithm [3]. Simulation results are presented to illustrate the sensitivity of our technique. We outline the implementation of our algorithm in the Persona personalized web search system.

For distributed systems at large and e-commerce systems in particular, ratings play an increasingly important role. Rating confer reputation measures about sources. This paper reports our formalization of the rating process. This paper argues that rating shuold be context- and individual- dependent quantities. In contrast to existing rating systems in many e-commerce or developer sites, our approach makes use of personalized and contextualized ratings for assessing source reputation. Our approach is based on a Bayesian probabilistic framework.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2003., Includes bibliographical references (leaves [131]-139)., Many recent studies of trust and reputation are made in the context of commercial reputation or rating systems for online communities. Most of these systems have been constructed without a formal rating model or much regard for our sociological understanding of these concepts. We first provide a critical overview of the state of research on trust and reputation. We then propose a formal quantitative model for the rating process. Based on this model, we formulate two personalized rating schemes and demonstrate their effectiveness at inferring trust experimentally using a simulated dataset and a real world movie-rating dataset. Our experiments show that the popular global rating scheme widely used in commercial electronic communities is inferior to our personalized rating schemes when sufficient ratings among members are available. The level of sufficiency is then discussed. In comparison with other models of reputation, we quantitatively show that our framework provides significantly better estimations of reputation. "Better" is discussed with respect to a rating process and specific games as defined in this work. Secondly, we propose a mathematical framework for modeling trust and reputation that is rooted in findings from the social sciences. In particular, our framework makes explicit the importance of social information (i.e., indirect channels of inference) in aiding members of a social network choose whom they want to partner with or to avoid. Rating systems that make use of such indirect channels of inference are necessarily personalized in nature, catering to the individual context of the rater. Finally, we have extended our trust and reputation framework toward addressing a fundamental problem for social science and biology: evolution of cooperation., (cont.) We show that by providing an indirect inference mechanism for the propagation of trust and reputation, cooperation among selfish agents can be explained for a set of game theoretic simulations. For these simulations in particular, our proposal is shown to have provided more cooperative agent communities than existing schemes are able to., by Lik Mui., Ph.D.

The aim of this study is to prepare a range of activated carbons with specific textural properties from two solid waste materials, namely, waste tyres and waste bamboo construction scaffolding. A range of experimental parameters have been varied and studied to see how each parameter influences the textural properties of the activated carbons. The waste tyre and bamboo were first converted into chars by thermal treatment. Theromgravimetric analyses have been performed and analysed using multi-stage kinetic decomposition models. For the pyrolysis of waste tyre a five-step model gave the best correlation to experimental data and a six-step model gave the best correlation for bamboo pyrolysis. Compensation effect was observed in the pyrolysis of both materials. Tyre carbons (with or without acid treatment) were produced via carbon dioxide activation with BET surface areas in the range 59 to 1118 m2/g. Bamboo-derived carbons by thermal activation in the presence of hydrochloric, nitric and sulphuric acids have lower BET surface area from 183 to 554 m2/g. Other characteristion tests include micropore and mesopore surface areas and volumes, pH, and elemental compositions, particularly heteroatoms such as nitrogen and sulphur. They were correlated to the adsorption capacity which were in the range 0.399 to 0.914 mmol/g (tyre) and to 0.022 to 0.088 mmol/g (bamboo) for acid dyes. For basic dye like Methylene Blue, capacities were in the range 1.034 to 1.428 mmol/g (tyre) and 0.351 to 0.649 mmol/g (bamboo). Based on the surface coverage analysis, novel molecular orientation modelling of adsorbed dyes has been proposed and correlated with surface area and surface charge. For acid dyes, molecules were likely to be adsorbed over mesopore areas. For basic dye micropore area was critical. While modelling the dye adsorption equilibrium data, the Redlich-Peterson isotherm is preferred.