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Viewing 1 to 30 of 172839
2018-03-16
Journal Article
2018-01-9550
Niclas S. Andersson, Thomas Abrahamsson
To make better use of simulations in the automotive driveline design process there is a need for both improved predictive capabilities of typical system models and increased number of variant evaluations carried out during system concept design phase. A previously developed large-scale multibody rotor dynamical powertrain model that combines detailed linear-elastic finite element components and nonlinear joints is used to more accurately simulate system response modes and their variations across the operating-range. However, the total simulation time is too long to include extensive parameter evaluations during the rapid design iterations, which will have a negative influence on the total understanding of the designed system’s behaviour. Therefore this paper is about reducing such a large-scale model to one that runs faster, but without losing the ability to predict the most fundamental system characteristics.
2018-01-19
Journal Article
2018-01-9077
Arya Yazdani, Mehran Bidarvatan
Power split in Fuel Cell Hybrid Electric Vehicles (FCHEVs) has been controlled using different strategies ranging from rule-based to optimal control. Dynamic Programming (DP) and Model Predictive Control (MPC) are two common optimal control strategies used in optimization of the power split in FCHEVs with a trade-off between global optimality of the solution and online implementation of the controller. In this paper, both control strategies are developed and tested on a FC/battery vehicle model, and the results are compared in terms of total energy consumption. In addition, the effects of the MPC prediction horizon length on the controller performance are studied. Results show that by using the DP strategy, up to 12% less total energy consumption is achieved compared to MPC for a charge sustaining mode in the Urban Dynamometer Driving Schedule (UDDS) drive cycle.
2018-01-19
Journal Article
2018-01-9625
Michael Sabisch, Meredith Weatherby, Sandeep Kishan, Carl Fulper
Under contract to the EPA, Eastern Research Group analyzed light-duty vehicle OBD monitor readiness and diagnostic trouble codes (DTCs) using inspection and maintenance (I/M) data from four states. Results from roadside pullover emissions and OBD tests were also compared with same-vehicle I/M OBD results from one of the states. Analysis focused on the evaporative emissions control (evap) system, the catalytic converter (catalyst), the exhaust gas recirculation (EGR) system and the oxygen sensor and oxygen sensor heater (O2 system). Evap and catalyst monitors had similar overall readiness rates (90% to 95%), while the EGR and O2 systems had higher readiness rates (95% to 98%). Approximately 0.7% to 2.5% of inspection cycles with a “ready” evap monitor had at least one stored evap DTC, but DTC rates were under 1% for the catalyst and EGR systems, and under 1.1% for the O2 system, in the states with enforced OBD programs.
2018-01-19
Journal Article
2018-01-9675
Youssef Sabry, Mahmoud Aly, Walid Oraby, Samir El-demerdash
This study aims to take the first step in bridging the gap between vehicle dynamics systems and autonomous control strategies research. More specifically, a nested method is employed to evaluate the collision avoidance ability of autonomous vehicles in the primary design stage theoretically based on both dynamics and control parameters. An integrated model is derived from a half car mathematical model in the lateral direction, consisting of two degrees of freedom, lateral deviation and yaw angle, with a traction mathematical model in the longitudinal direction, consisting of two degrees of freedom, the longitudinal velocity and rolling velocity of the wheel. The integrated model uses a mathematical power train model to generate the torque on the wheel and connects the two systems via the magic formula tyre model to represent the tyre non-linearity during augmented longitudinal and lateral dynamic attitudes. These mathematical models are represented using MATLAB in the time domain.
2018-01-12
Technical Paper
2018-01-9626
Marcus Schmitz, Lena Rittger, Henning Kienast, Alexandra Neukum
Potential collisions with oncoming traffic while turning left belong to the most safety-critical situations with ~25% of all intersection crossing path crashes. A Left Turn Assist (LTA) was developed to reduce the number of crashes. Crucial for the effectiveness of the system is the design of the human machine interface, i.e. defining how the system uses the calculated crash probability in the communication with the driver. A driving simulator study was conducted evaluating a warning strategy for two use cases: firstly, the ego-vehicle comes to a stop before turning (STOP), and secondly, the driver moves on without stopping (MOVE). 40 drivers drove through three STOP and two MOVE scenarios. For the STOP scenarios, the study compared the effectiveness of an audio-visual warning with an additional brake intervention and a baseline. For the MOVE scenarios, the study analyzed the effectiveness of the audio-visual warning against a baseline.
2018-01-12
Journal Article
2018-01-9275
Hamed Kheshtinejad, Mirko Baratta, Danilo Laurenzano, Claudio Maino, Daniela Anna Misul
CNG is at present retaining a growing interest as a factual alternative to traditional fuels for SI engines, thanks to its high potentials in reducing the engine-out emissions. Increasing thrust into the exploitation of NG in the transport field is in fact produced by the even more stringent emission regulations that are being introduced into the worldwide scenario. The present paper aims at deeply investigating into the potentials of a heavy-duty engine running on CNG and equipped with two different injection systems, an advanced single point (SP) one and a prototype multi-point (MP) one. The considered 7.8-liter engine was designed and produced to implement a SP strategy and hence modified to run with a dedicated MP system. A thorough comparison of the engine equipped with the two injection systems has been carried out at steady state as well as at transient operations.
2018-01-12
Journal Article
2018-01-9677
Sabine Bonitz, Dirk Wieser, Alexander Broniewicz, Lars Larsson, Lennart Lofdahl, Christian Nayeri, Christian Paschereit
The flow around and downstream of the front wheels of passenger cars is highly complex and characterized by flow structure interactions between the external flow, fluid exiting through the wheel and wheelhouse and flow from the engine bay and the underbody. In the present paper the near wall flow downstream of the front wheel house is investigated. To visualize the surface pattern a new method is applied, which uses the traditional tuft visualization to capture image series of instantaneous flow patterns and is extended by a digital image processing component to obtain quantitative and time dependent information. Additionally, time resolved surface pressure measurements are reported. The data allows the calculation of the pressure distribution, the standard deviation, cross correlations and a spectral analysis. This paper shows how occurring flow structures propagate over the area studied, by investigating cross correlations of the pressure signal.
2017-12-15
Article
VW's compact SUV gets a touch of Porsche chassis expertise.
2017-12-15
WIP Standard
AMS2415K
This specification covers the requirements for electrodeposited and diffused lead and indium plate.
2017-12-15
WIP Standard
AMSC81562A
This specification covers the requirements for three types and three classes of mechanically deposited cadmium, tin-cadmium or zinc coatings on metallic surfaces by impacting (peen plating).
2017-12-14
WIP Standard
AS8660A
This specification covers one type of a nonmelting, heat stable silicone compound for use in high tension electrical connections, ignition systems and electronics equipment; for application to unpainted mating threaded or non-threaded surfaces, and as a lubricant for components fabricated from rubber. This compound is effective in the temperature range from -54°C (-65°F) to +204°C (+400°F) for extended periods and to 260°C (500°F) for short periods. This compound is identified by NATO symbol S-736 (see 6.5).
CURRENT
2017-12-14
Standard
AS21442B
SCOPE IS UNAVAILABLE.
2017-12-13
WIP Standard
AMS6953
This specification covers a titanium alloy in the form of sheet from 0.020 to 0.1874 inches (0.508 to 4.760 mm), inclusive, nominal thickness.
Viewing 1 to 30 of 172839