1,721,099 research outputs found
Design of a lightweight chassis for the land speed record vehicle Buckeye Bullet 2
No full textThe design of a novel chassis solution for a land speed record streamliner, the Buckeye Bullet 2, which represents an evolution of the vehicle that recently set various records in the electric vehicle classes is addressed in this paper. Various architectures for a lightweight solution are investigated considered. The reference chassis design of the Buckeye Bullet consists of a steel space frame structure, for which alternative candidate solutions are investigated. These include several combinations of aluminium honeycomb sandwich panels and carbon fibre composite skins and a composite monocoque structure. A high-speed streamliner requires a chassis that is stiff in both torsion and bending, especially in transversal direction, in order to avoid undesired vibrations that can compromise vehicle handling. Thus, the various solutions are compared on the basis of mass, stiffness and eigenfrequencies. Finally, this paper investigates chassis strength with respect to torsional and bending loads that produce critical stresses for the reference structure and for operative loads
A Two-step Optimization Method for the Preliminary Design of a Hybrid Electric Vehicle
No full textIn the present investigation an innovative procedure to design a Hybrid Electric Vehicle (HEV) is proposed. The procedure is based on two steps: optimization and decision-making. Both steps re-quire a multi-objective approach due to the high number of goals to be taken into account in the de-sign of a complex system like a HEV.
The method has been applied to the preliminary design of the powertrain and the tuning of the con-trol strategy of a series hybrid vehicle, simulated with a Matlab-Simulink code. The hardware pa-rameters included the number of axles in the vehicle, the number of electric motors per axle, the type and quantity of energy storage system devices (batteries and/or electrochemical capacitors). The control parameters are related to the fuel economy conversion factors and the maximum and minimum state of charge allowed to the secondary energy storage systems.
Several attributes of performance and fuel consumption evaluated with respect to seven driving cy-cles were considered as optimization goals
A two-step optimisation method for the preliminary design of a hybrid electric vehicle
No full textIn the present investigation an innovative procedure to design a hybrid electric vehicle (HEV) is proposed, based on two steps: optimisation and decision-making. Both steps require a multi-objective approach due to the many goals to be taken into account in the design of a complex system like an HEV. The method has been applied to the preliminary design of the powertrain and tuning of the control strategy of a series hybrid vehicle, simulated with a Matlab-Simulink code. The hardware parameters included the number of axles in the vehicle, number of electric motors per axle, and type and quantity of energy storage system devices (batteries and/or electrochemical capacitors). The control parameters are related to fuel economy conversion factors and the maximum and minimum state of charge allowed to the secondary energy storage systems. Several attributes of performance and fuel consumption evaluated with respect to seven driving cycles were considered as optimisation goals. © 2008, Inderscience Publishers
Fast algorithm for on-board torque estimation
No full textElectronic Throttle Control systems substitute the driver in commanding throttle position, with the driver acting on a potentiometer connected to the accelerator pedal. Such strategies allow precise control of air-fuel ratio and of other parameters, e.g. engine efficiency or vehicle driveability, but require detailed information about the engine operating conditions, in order to be implemented inside the Electronic Control Unit (ECU). In order to determine throttle position, an interpretation of the driver desire (revealed by the accelerator pedal position) is performed by the ECU. In our approach, such interpretation is carried out in terms of a torque request that can be appropriately addressed knowing the actual engine-vehicle operating conditions, which depend on the acting torques. Estimates of the torque due to in-cylinder pressure (indicated torque), as well as the torque required by the vehicle (load torque), must then be available to the control module. The estimation procedure should be at the same time sufficiently precise and fast in order to comply with the driver requests in real time. In this paper we present a signal processing procedure to estimate the cycle mean values of both the indicated and load torque, based on a frequency analysis of the engine block vibrations signal. The algorithm that has been developed tries to meet the precision and quickness requirements for on board implementation; this goal has been reached using only two frequency components of the engine block vibrations. The quality of the estimation methodology has been initially tested on an engine test cell, using a two cylinder small diesel engine and showing a good agreement between measurements and estimations, even under strong speed and load transients. The procedure is scheduled to be validated on-board a production vehicle. Copyright © 1999 Society of Automotive Engineers, Inc
Development and experimental validation of a low-frequency dynamic model for a Hybrid Electric Vehicle
Full text linkThis paper describes the development and experimental validation of a high-fidelity Hybrid Electric Vehicle (HEV) simulator that enables testing and calibration of energy management and driveline control strategies. The model is capable of predicting longitudinal vehicle responses that affect energy consumption and drivability in the low-to-mid frequency region (up to 10 Hz). The simulator focuses primarily on the drivetrain dynamics, while the dynamics of the actuators are represented by simplified models. The vehicle simulator is validated by a number of experiments that include electric only, engine only and hybrid operating conditions. The test vehicle has a through-the-road parallel hybrid architecture that utilises a dual electric machine configuration. Experimental results confirm that important driveline phenomena such as shunt, shuffle, torque holes and other transient disturbances related to operating mode changes are accurately predicte
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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