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Online gasoline blending with EPA Complex Model for predicting emissions

Stefan JANAQI, Mériam CHÈBRE, Guillaume PITOLLAT

《工程管理前沿（英文）》 2018年第5卷第2期页码 214-226 doi: 10.15302/J-FEM-2017022

摘要： The empirical Complex Model developed by the US Environmental Protection Agency (EPA) is used by refiners to predict the toxic emissions of reformulated gasoline with respect to gasoline properties. The difficulty in implementing this model in the blending process stems from the implicit definition of Complex Model through a series of disjunctions assembled by the EPA in the form of spreadsheets. A major breakthrough in the refinery-based Complex Model implementation occurred in 2008 and 2010 through the use of generalized disjunctive and mixed-integer nonlinear programming (MINLP). Nevertheless, the execution time of these MINLP models remains prohibitively long to control emissions with our online gasoline blender. The first objective of this study is to present a new model that decreases the execution time of our online controller. The second objective is to consider toxic thresholds as hard constraints to be verified and search for blends that verify them. Our approach introduces a new way to write the Complex Model without any binary or integer variables. Sigmoid functions are used herein to approximate step functions until the measurement precision for each blend property is reached. By knowing this level of precision, we are able to propose an extremely good and differentiable approximation of the Complex Model. Next, a differentiable objective function is introduced to penalize emission values higher than the threshold emissions. Our optimization module has been implemented and tested with real data. The execution time never exceeded 1 s, which allows the online regulation of emissions the same way as other traditional properties of blended gasoline.

关键词： emissions reformulated gasoline online control global optimization

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Integrated control strategies for railway vehicles with independently-driven wheel motors

FENG Jinzhi, LI Jun, Goodall R. M.

《机械工程前沿（英文）》 2008年第3卷第3期页码 239-250 doi: 10.1007/s11465-008-0053-y

摘要： This paper studies the development of integrated control strategies for railway vehicles with independently-driven wheel motors. First, a non-linear vehicle dynamic model and motor drive strategy are presented, which are followed by an investigation of the integrated control of stabilization, steering, and traction for the vehicle. Meanwhile a reformulated Kalman filter is developed and applied to estimate the required feedback by the control system. Finally, the effectiveness and practicality of the proposed integrated controller are examined and assessed by real-time simulation based on host-target computer technology provided by Matlab/Simulink.

关键词： development independently-driven non-linear stabilization reformulated