Browsing by Author "Wasfy, Tamar"

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    Charge optimization of lithium-ion batteries for electric-vehicle application
    (2015-03-02) Pramanik, Sourav; Anwar, Sohel; Wasfy, Tamar; Li, Lingxi
    In recent years Lithium-Ion battery as an alternate energy source has gathered lot of importance in all forms of energy requiring applications. Due to its overwhelming benefits over a few disadvantages Lithium Ion is more sought of than any other Battery types. Any battery pack alone cannot perform or achieve its maximum capacity unless there is some robust, efficient and advanced controls developed around it. This control strategy is called Battery Management System or BMS. Most BMS performs the following activity if not all Battery Health Monitoring, Temperature Monitoring, Regeneration Tactics, Discharge Profiles, History logging, etc. One of the major key contributor in a better BMS design and subsequently maintaining a better battery performance and EUL is Regeneration Tactics. In this work, emphasis is laid on understanding the prevalent methods of regeneration and designing a new strategy that better suits the battery performance. A performance index is chosen which aims at minimizing the effort of regeneration along with a minimum deviation from the rated maximum thresholds for cell temperature and regeneration current. Tuning capability is provided for both temperature deviation and current deviation so that it can be tuned based on requirement and battery chemistry and parameters. To solve the optimization problem, Pontryagin's principle is used which is very effective for constraint optimization with both state and input constraints. Simulation results with different sets of tuning shows that the proposed method has a lot of potential and is capable of introducing a new dynamic regeneration tactic for Lithium Ion cells. With the current optimistic results from this work, it is strongly recommended to bring in more battery constraints into the optimization boundary to better understand and incorporate battery chemistry into the regeneration process.
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    DYNAMIC ANALYSIS AND SIMULATIONS OF A BACKHOE
    (Office of the Vice Chancellor for Research, 2012-04-13) Ahmadi Ghoohaki, Shahriar; Wasfy, Tamar
    A backhoe is a type of excavating equipment that is used in most digging processes in the construction industry. Increasing the speed of digging, the load capacity and the stability of the vehicle during the digging operation are required in order to reduce the backhoe operating costs. The overall objec-tive of this project is to develop a high-fidelity flexible multibody dynamic model of the backhoe by using Pro/Engineer and a finite element multibody dynamics code called DIS. Pro/Engineer is used to create the geometry of the major moving components of the backhoe including undercarriage, road wheels, idler pulleys, drive sprocket, track, main body, boom, stick, bucket and hydraulic actuators. The components of the backhoe are imported to DIS and connected using joints including spherical, revolute and prismatic joints. In addition, contact surfaces for the wheels, sprocket, track segments and bucket are defined. A discrete element model (DEM) for the sand that is excavated by the backhoe is used. In the DEM model sand is modeled using discrete particles with appropriate normal, tangential friction and adhesion contact force models. The model can be used to predict the digging force exerted by the hydraulic actuators. This is turn can be used to predict the allowable digging speed and load capacity. The model can also be used to predict the stability of the backhoe during digging.