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York University
Applied and Industrial Mathematics Seminar

Past Events: 2005


Covariance Contracting - Hydro-Electric Incentive Mechanisms in a Regulated Market

Hans J.H. Tuenter (Ontario Power Generation, Energy Markets.)
Friday May 8, from 1:30-2:30pm in N638

Abstract: We will start with an overview of electricity generation in Ontario, and then focus on the hydro-electric part of OPG's generation fleet, in particular the Sir Adam Beck complex at Niagara. As most hydro-electric generation in the province, this is a regulated asset and receives a fixed price for its production. This provides for more predictable earnings on these assets, as the price risk is eliminated. However, this also eliminates the economic driver to shape production to market prices. This is important, as additional generation made available at higher priced hours lowers the market-clearing price, and benefits the rate-payers of Ontario. We will describe a newly implemented incentive mechanism that provides revenue stability, but gives the same operational drivers as in a pure market-based environment. We conclude with a description of the stochastic op

Optimization in Fractal and Fractal-like Landscapes using Locust Swarms

Dr Stephen Chen (York)
Friday May 1st from 2:30-3:30pm in N638

Abstract: Locust swarms are a recently developed multi-optima particle swarm. They were explicitly developed for non-globally convex search spaces, and characteristics of these search spaces occur naturally in problems with fractal and fractal-like landscapes. On the 1000-dimensional “FastFractal” problem used in the 2008 IEEE Congress on Evolutionary Computation competition on Large Scale Global Optimization, Locust Swarms can perform better than all of the methods in the competition. Locust Swarms also perform very well on a real-world optimization problem that has a fractal-like landscape. The "fractalness" of this real-world landscape is observed with the help of a new metric that implicitly measures the lack of regularity and symmetry in a fitness landscape.

Viral Dynamics during Primary HIV-1 Infection: Effect of Time-dependent Virus Infectiousness

Dr Naveen Vaidya.
Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545 USA
April 15, 2009 at 2:30pm in CB 129.

Abstract: A recent experiment of SIV (Simian Immunodeficiency Virus) infection of macaque monkeys and a data analysis of HIV (Human Immunodeficiency Virus) infected individuals revealed that the infectiousness of virus varies over time during primary HIV-1 infection. We introduce a viral dynamics mathematical model with time-dependent virus infectiousness. The model fits well with the real data and is statistically significant for most of the patients. We provide the reproduction number and carry out the stability analysis of the model. We highlight possible adverse effects on viral dynamics and stability properties, caused by ignoring time-dependent infectiousness in HIV-1 viral dynamics models. The model is further extended to include the effects of antiretroviral therapy, and by using the optimal control formulation we observe how the time-dependent infectiousness affects the optimal schedule and outcomes of therapy.

Note: This is a joint work with Dr. Ruy Ribeiro and Dr. Alan S. Perelson, Los Alamos National Laboratory, Los Alamos, NM USA

 

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