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Non-fragile h∞ order reduction of LTI controllers
, Article IEEE Control Systems Letters ; Volume 5, Issue 1 , 2021 , Pages 163-168 ; 24751456 (ISSN) ; Nobakhti, A ; Tavazoei, M. S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
The eigenvalue perturbation theorem is used to propose a convex fragility criterion with application to control system design. The criterion can be considered as a non-normality measure of the controller state-space matrix. Non-normality of a matrix is defined as its distance to the nearest real normal matrix within a convex normal subspace. Based on the criterion, an H∞ method for the order reduction of linear time-invariant (LTI) controllers is developed which leads to non-fragile reduced order controllers. 2020 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission
A Simultaneous Approach for Activity Type and Activity Duration of Disabled People
, M.Sc. Thesis Sharif University of Technology ; Samimi, Amir (Supervisor)
Abstract
Daily activity patterns that include type and duration of activities are modeled simultaneously in MDCEV models. Conventionally, however, a diverse range of econometric models are used to sequentially model the decisions. Focusing on the disabled individuals, we aimed at comparing the prediction power of the two methods. A three level Nested Logit along with a Hazard model represent the sequential approach, the performance of which is compared to the MDCEV method. A random forest model is applied during the activity type prediction by MDCEV model. With considering 6.35 percent error in random forest model, the results confirmed that simultaneous approach improves activity type prediction by...
Predictive Cordon Pricing to Reduce Air Pollution
, Ph.D. Dissertation Sharif University of Technology ; Poorzahedy, Hossain (Supervisor) ; Lindsey, Robin (Co-Supervisor)
Abstract
Traffic is a major contributor to emissions in many large cities with severe air pollution. Experience in London, Milan, and Stockholm shows that charging for the use of roads can be effective in reducing emissions, as well as congestion. This study examines the use of predictive cordon tolls based on weather forecasts to reduce ambient air pollution and congestion. Travelers choose their destinations inside or outside the cordon, and whether to drive or take public transport. Passenger vehicles are divided into three classes according to their emission characteristics, and higher tolls are imposed on more polluting vehicles. The Box model of emission dispersion is used to predict air...
Non-Fragile Order Reduction of Linear Controllers
, M.Sc. Thesis Sharif University of Technology ; Nobakhti, Amin (Supervisor) ; Tavazoei, Mohammad Saleh (Supervisor)
Abstract
Most of the robust or optimal controllers can produce extremely fragile controllers [1], in the sense that vanishingly small perturbations of the coefficients of the designed controller destabilize the closed-loop control system. Modern control methods, including robust control, lead to high order controllers.Often times a reduced order controller is implemented. As a result, need for low order control design reducing controller’s ensitivity is tangible. Based on studies carried out, properties of normal matrices can be employed to define a fragility measure. In this thesis, a new convex criterion measuring controller fragility is defined. Then, a more resilient reduced order controller can...