In designing a parallel hybrid electric vehicle, it is essential to select the optimal capacity of power sources and the optimal gear ratio of the torque coupler. The capacity of the power sources and the gear ratio of the torque coupler should be optimized simultaneously. However, since this process is excessively time-consuming, previous studies have selected the gear ratio of the torque coupler and then selected the capacity of power source. However, this approach cannot guarantee global optimization. In this paper, a feasible region is defined to satisfy the required performance of vehicle such as maximum speed, hill-climbing. and feasible points are selected inside the feasible region. In the conventional technique, the global optimal solution is obtained by simulating all feasible points. In the optimization technique, optimal points are simulated within the feasible region using several optimal search algorithms, such as the golden section search algorithm and the hillclimbing search algorithm. And using these algorithms, the number of simulations is reduced and the capacity of the power source and the gear ratio of the torque coupler are optimized simultaneously. Finally, the validity of the component sizing results is verified by comparing the global optimal solution obtained by applying the conventional technique with the solution obtained by applying the proposed optimization technique. 相似文献
Transportation - This paper presents estimation results for models of transport chain and shipment size choice, as well as an implementation of the estimated disaggregate models (for two commodity... 相似文献
A transient numerical model of a lithium ion battery (LiB) pack with air cooled thermal management system is developed and validated for electric vehicle applications. In the battery model, the open circuit voltage and the internal resistance map based on experiments are used. The Butler-Volmer equation is directly considered for activation voltage loss estimation. The heat generation of cells and the heat transfer from cells are also calculated to estimate temperature distribution. Validations are conducted by comparison between experimental results at the cell level and the pack level. After validations, the effects of module arrangement in a battery pack are studied with different ambient temperature conditions. The configuration that more LiB cells are placed near the air flow inlet is more effective to reduce the temperature deviation between modules. 相似文献
FTP75 driving cycle is used in many countries for evaluation of vehicle fuel economy. FTP75 has 3 phases, where the Phase 1 and the Phase 3 have a same velocity profile, but the Phase1, which is known as cold start phase, shows lower fuel efficiency than the Phase 3. In order to analyze the difference of fuel economy between Phase 1 and Phase 3, vehicle tests are performed. The test results show that the differences of fuel economy is ranging from 3.9% to 18.5%. The factors of the difference of fuel economy for gasoline automatic transmission vehicles are analyzed in this research. The key factors affecting the difference of fuel economy are engine friction loss, torque converter loss and accessory loss. The quantitative analysis of these factors is performed. 相似文献
A variety of automatic data collection technologies have been used to gather road and highway system data. The majority of these automatic data collection technologies are designed to collect vehicle-based data and either do not have the capability to collect other travel mode data (e.g., bicycles and pedestrians), or may need to be deployed differently to support this capability.
One type of wireless-based data collection system that has been deployed recently is based on Bluetooth technology. A key feature of Bluetooth-based data collection systems that makes travel mode identification feasible is that the Bluetooth-enabled devices within vehicles are also present on bicyclists and pedestrians. This research explores the effectiveness of applying cluster analysis methods when processing data collected via Bluetooth technology from vehicles, bicyclists, and pedestrians to automatically identify the associated travel modes. The results of several experiments utilizing multiple Bluetooth-based data collection units arranged linearly and in relatively close proximity on a simulated intersection demonstrate the potential of cluster analysis to accurately differentiate transportation modes from the collected data. 相似文献
A roof crush test has been utilized to reduce passengers’ injuries from a vehicle rollover. The Federal Motor Vehicle Safety Standards (FMVSS) 216 and the Insurance Institute for Highway Safety (IIHS) perform actual vehicle tests and evaluate the vehicle’s ratings. Nonlinear dynamic response structural optimization can be employed not only for achievement of a high rating but also minimization of the weight. However, the technique needs a huge computation time and cost because many nonlinear dynamic response analyses are required in the time domain. A novel method is proposed for nonlinear dynamic response structural optimization regarding the roof crush test. The process of the proposed method repeats the analysis domain and the design domain until the convergence criteria are satisfied. In the analysis domain, the roof crush test is simulated using a high fidelity model of nonlinear dynamic finite element analysis. In the design domain, a low fidelity model of linear static response structural optimization is utilized with enforced displacements that come from the analysis domain. Correction factors are employed to compensate the differences between a nonlinear dynamic analysis response and a linear static analysis response with enforced displacement. A full-scale vehicle problem is optimized with a constraint on the rigid wall force from the analysis in the design domain. 相似文献
HILS (Hardware In the Loop Simulation) and RBT (Requirement-Based Testing) are widely used to evaluate the performance and
reliability of automotive ECUs (Electronic Control Units). The HILS method is used to predict the behavior of ECU-installed
vehicles and to evaluate the performance of ECU controllers. RBT evaluates whether the embedded system satisfies the pre-defined
requirements. In this study, the behavior of a vehicle is regarded as a system requirement, and an embedded system test procedure
that evaluates the system requirement is proposed. In particular, a new method is introduced, which integrates HILS with RBT.
Using the proposed method, the behavior of an articulated vehicle equipped with an AWS (All Wheel Steering) ECU is evaluated
with RBT software. 相似文献
OSEK OS (Offene Systeme und deren Schnittstellen für die Elektronik in Kraftfahrzeugen Operating System) is an open, real-time
operating system standard for ECU software in vehicles. Because it was originally designed to be used in an extremely resource-constrained
environment, an OSEK-compliant operating system must incur low processing overhead and memory usage. Unfortunately, as OSEK
OS has evolved over time, it now specifies nontrivial kernel features along with multiple conformance classes and application
modes. This may lead to unwanted dynamic resource usage in a system using OSEK OS unless the standard is carefully interpreted
and designed into an OSEK OS implementation. In this paper, we analyzed the various kernel features of OSEK OS and their interactions
to identify areas in the standard that warrant further resource usage optimization. In particular, we attempted to reduce
the run-time memory footprint. Based on our analyses, we present two kernel mechanisms: (1) stack sharing among tasks and
(2) light-weight ready queue handling specialized for OSEK OS conformance classes. We also offer implementation methods for
the proposed mechanisms by extending OIL and associated tools. Finally, we show the effectiveness of the proposed mechanisms
via extensive experiments. Our mechanisms allow OSEK-based systems to use only 36% of the memory requirements of conventional
OSEK-based systems on average. 相似文献
A recent survey reported that many commuter-cyclists had enjoyed leisure bicycling on a regular basis prior to becoming a
commuter-cyclist. While bicycling for leisure, it is assumed that they considered various factors that led them to consider
becoming commuter-cyclists. This study began with the question of how long it would take for a leisure-cyclist to become a
commuter-cyclist, and it focused on the time that elapsed between leisure-cyclists transitioning to commuter-cycling. In order
to analyze the time frame, it was hypothesized that the probability that a leisure-cyclist would become a commuter-cyclist
at a certain time would be conditional on the duration that elapsed from the onset of leisure cycling till that time, which
represents the “snowballing” or “inertial” dynamics of duration. A robust methodology, which is known as the “hazard model,”
was adopted to accommodate such characteristics of a time period. In addition, various external covariates such as individual-specific
characteristics, variables associated with the current or previous commuting mode, supply variables regarding bicycle facilities,
and individual latent propensities were adopted to account for the duration of changes that would be generally applicable.
As a result, many useful results were derived that could be used in fomenting policies to promote cycling to work. It was
found that government should invest in establishing segregated lanes for leisure- and commuter-cyclists. It also turned out
that a long distance to work hinders a leisure-cyclist from progressing to commuter-cycling. According to the results, young
white-collar workers who live in high-rise apartments and enjoy intensive leisure-cycling in groups, are a good target toward
whom promotions for commuter-cycling should be focused. However, an unfortunate development was that, when compared with car-commuters,
it was found that transit-commuters are more likely to become commuter-cyclists. 相似文献