Browsing by Author "Dr. Munindar P. Singh, Chair"

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    A Distributed Parameter Liver Model of Benzene Transport and Metabolism in Humans and Mice - Developmental, Theoretical, and Numerical Considerations
    (2001-12-03) Gray, Scott Thomas; Dr. Munindar P. Singh, Chair; Dr. R. Michael Young, Member; Dr. Mona Singh, Member
    In the Clean Air Act of 1970, the U. S. Congress names benzene ahazardous air pollutant and directs certain government agencies toregulate public exposure. Court battles over subsequent regulations haveled to the need for quantitative risk assessment techniques. Models forhuman exposure to various chemicals exist, but most current modelsassume the liver is well-mixed. This assumption does not recognize (mostsignificantly) the spatial distribution of enzymes involved in benzenemetabolism. The development of a distributed parameter liver model that accountsfor benzene transport and metabolism is presented. The mathematicalmodel consists of a parabolic system of nonlinear partial differentialequations and enables the modeling of convection, diffusion, andreaction within the liver. Unlike the commonly used well-mixed model,this distributed parameter model has the capacity to accommodate spatialvariations in enzyme distribution. The system of partial differential equations is formulated in a weak orvariational setting that provides natural means for the mathematical andnumerical analysis. In particular, general well-posedness results ofBanks and Musante for a class of abstract nonlinear parabolic systemsare applied to establish well-posedness for the benzene distributedliver model. Banks and Musante also presented theoretical results for ageneral least squares parameter estimation problem. They included aconvergence result for the Galerkin approximation scheme used in ournumerical simulations as a special case. Preliminary investigations on the qualitative behavior of thedistributed liver model have included simulations with orthograde andretrograde bloodflow through mouse liver tissue. Simulation of humanexposure with the partial differential equation and the existingordinary differential equation model are presented and compared. Finally, the dependence of the solution on model parameters is explored.
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    A Referral-Based Recommender System for E-commerce
    (2001-08-21) Mo, Wentao; Dr. Munindar P. Singh, Chair; Dr. R. Michael Young, Member; Dr. Mona Singh, Member
    The thesis is intended to develop the technology and infrastructure to allow people to share knowledge with and learn from each other. A special kind of multiagent system, called multiagent referral system (MARS), is proposed. In MARS, each user is assigned a software agent, and software agents help automate the process of expertise location by a series of 'referral chains.' Unlike most previous approaches, our architecture is totally distributed and preserves the privacy and autonomy of their users. These agents learn models of each other in terms of expertise (ability to produce correct domain answers), and sociability (ability to produce accurate referrals).
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    Specifying and Verifying Compliance in Commitment Protocols
    (1999-07-18) Venkatraman, Mahadevan; Dr. Munindar P. Singh, Chair; Dr. Kuo-chung Tai, Member; Dr. Injong Rhee, Member
    Interaction protocols are specific, often standard, constraints on thebehaviors of autonomous agents in a multiagent system. Protocols areessential to the functioning of open systems, such as those that arisein most interesting web applications. A variety of common protocolsin negotiation and electronic commerce are best treated ascommitment protocols, which may be defined and analyzed interms of the creation, satisfaction, or manipulation of thecommitments among the participating agents.When protocols are employed in open environments, such as theInternet, they must be executed by agents that behave more or lessautonomously and whose internal designs are not known. In suchsettings, therefore, there is a risk that the participating agents mayfail to comply with the given protocol. Without a rigorous means toverify compliance, the very idea of protocols for interoperation issubverted. We develop an approach for verifying whether the behavior ofan agent complies with a given commitment protocol. Our approach requiresthe specification of commitment protocols in temporal logic, andinvolves a novel way of synthesizing and applying ideas fromdistributed computing and logics of program.