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151.
J. Kim J. Kang Y. Kim T. Kim B. Min H. Kim 《International Journal of Automotive Technology》2010,11(4):565-571
The power split type hybrid system transmits engine power by dividing it into the electrical unit and the mechanical unit.
Its power transmission efficiency is highest at the mechanical point (MP), where the full power is transmitted to the mechanical
unit. In this study, the equation for the MP was derived for the gear ratios of a general 4-node lever model. The MP characteristics
for the transmission ratio (TR) of the input split and compound split structures were examined using the equation derived.
Using the examined input split and compound split structures, a systematic design method for the dual mode power split transmission
was proposed. In the dual mode power split transmission, the MP could be positioned at the desired TR, and the input split
and compound split modes could be selectively used according to the clutch combination, which leads to the operation of the
vehicle within a high system efficiency range. 相似文献
152.
A. López J. Serrat C. Cañero F. Lumbreras T. Graf 《International Journal of Automotive Technology》2010,11(3):395-407
Detection of lane markings based on a camera sensor can be a low-cost solution to lane departure and curve-over-speed warnings.
A number of methods and implementations have been reported in the literature. However, reliable detection is still an issue
because of cast shadows, worn and occluded markings, variable ambient lighting conditions, for example. We focus on increasing
detection reliability in two ways. First, we employed an image feature other than the commonly used edges: ridges, which we
claim addresses this problem better. Second, we adapted RANSAC, a generic robust estimation method, to fit a parametric model
of a pair of lane lines to the image features, based on both ridgeness and ridge orientation. In addition, the model was fitted
for the left and right lane lines simultaneously to enforce a consistent result. Four measures of interest for driver assistance
applications were directly computed from the fitted parametric model at each frame: lane width, lane curvature, and vehicle
yaw angle and lateral offset with regard the lane medial axis. We qualitatively assessed our method in video sequences captured
on several road types and under very different lighting conditions. We also quantitatively assessed it on synthetic but realistic
video sequences for which road geometry and vehicle trajectory ground truth are known. 相似文献
153.
We investigated the effects of injection parameters such as injection pressure, ambient pressure, and ambient temperature
on spray characteristics. We calculated the turbulence occurring point (t
c
), defined as the time required to generate a vortex, and the deceleration point (t
b
), defined as the time when spray penetration begins to decelerate, to elucidate the breakup mechanism of the test injectors.
The spray velocity coefficient (Cv) was obtained to evaluate the spray characteristics. As the ambient pressure increases in the case of a slit injector, Cv decreases. We investigated the effects of nozzle tip shape according to injection pressure, ambient pressure, and fuel properties
on spray characteristics and provide a Cv value of 0.38 for the swirl injector with a spray angle of 60° and the slit injector under atmospheric conditions. The value
of Cv in the case of a slit injector was reduced by increasing the ambient pressure. Our results suggest that Cv of a swirl injector is constant regardless of changes in ambient pressure, injection pressure, and fuel properties. On the
other hand, Cv of a slit injector is altered by changes in ambient pressure. 相似文献
154.
D. Danardono K. S. Kim E. Roziboyev C. U. Kim 《International Journal of Automotive Technology》2010,11(3):323-330
A roller vane type liquefied petroleum gas (LPG) pump was developed for a liquid phase LPG injection (LPLi) engine. Most of
the LPG pumps used in the current LPLi engines are installed inside of the LPG tank, but this pump is intended to be installed
outside of the LPG tank to overcome the difficulty of fixing an in-tank pump. Because LPG has a low boiling point and high
vapor pressure, it usually causes cavitation in the pump and consequently deteriorates the flow rate of the pump. The purpose
of this work is to optimize the design of the roller vane pump in order to suppress cavitation and increase the fuel flow
rate by using a computational fluid dynamics (CFD) analysis. In order to achieve these goals, the intake port configuration
and the rotor of the roller vane pump were redesigned and simulated using STAR-CD code. Computation was performed for six
different models to obtain the optimized design of the roller vane pump at a constant speed of 2600 rpm and a constant pressure
difference between the inlet and outlet of 5 bar. The computation results show that an increased intake port cross-section
area can suppress cavitation, and the pump can achieve a higher flow rate when the rotor configuration is changed to increase
its chamber volume. When the inlet pressure difference is 0.1 bar higher than the fluid saturation pressure, the pump reaches
its maximum flow rate. 相似文献
155.
This paper presents a robust optimization design method based on Six Sigma quality control criteria to improve the design
of a powertrain mounting system (PMS). The powertrain is modeled as a rigid body having six degrees of freedom (DOF) connected
to a rigid base by four rubber mounts, and each mount is simplified as a three-dimensional spring-damper element in its local
coordinate system (LCS). The calculation method based on energy decoupling is used to estimate the decoupling ratios of a
PMS. The location and static stiffness of each mount and the orientations of the two anti-torsion mounts are selected as uncertain
design variables, and the nominal values of these design variables are optimized to obtain a robust Six Sigma design for a
PMS. The uncertain design variables are characterized by a perturbation or percent variation around their nominal values.
The generalized reduced gradient (LSGRG2) optimization method is employed to solve the robust optimization problem, and a
second-order Taylor series expansion is used to estimate the statistical properties of the performance constraints and objectives.
The optimization results show that the robust design ensures good robustness or high reliability for the natural frequencies,
decoupling ratios, and frequency separation constraints of a PMS. 相似文献
156.
The acoustic design of exhaust mufflers has mainly focused on reducing the discharge noise from the tailpipe. However, the
noise that is transmitted through the muffler jacket and the endplate becomes important since the muffler reduces the amount
of discharge noise when it has an optimized design. It is known that the contribution to the overall exhaust noise of the
muffler shell is significant in the mid- and high-frequency ranges. The current problem is that there are no appropriate computational
tools at high frequencies. A simple method to analyze the 1/3-octave band of sound radiating from an arbitrary shape (like
a muffler) was employed to predict the band spectrum of the radiated noise. The calculation method included formulating the
boundary integral, which was modified into a quadratic form in order to enable the prediction of the intensity levels in a
band analysis. Monopole and dipole source terms in the conventional BEM were transformed into the auto- and cross-spectra
of the two vibrating sources, in which the cross-spectra could be eventually omitted by assuming that the correlation coefficients
were negligible. The method was adopted in an abrupt calculation of the shell noise in 1/3-octave band levels without nonuniqueness
problem. In comparison with the measured data, the simulation result showed roughly 3-dB errors at most of the field points,
excluding several special points that were normal to the shell and exhibited a maximum 5-dB error. 相似文献
157.
Modeling,parameter estimation and nonlinear control of automotive electronic throttle using a Rapid-Control Prototyping technique 总被引:1,自引:0,他引:1
An electronic throttle consists of a DC motor, spur gears, a return spring, a position sensor, power electronics and an electronic
control unit. Fast and precise position control of this electromechanical system is relatively difficult due to very high
friction and the strong nonlinearity of the spring. Simple application of linear control, such as PID, fails. In this paper,
two new controller structures suitable for different reference signal types are described. The key component of the position
controller is the friction compensator based on either/both feedforward or feedback principles. The quality of the resulting
behavior was measured using several criteria including the measure of control activity around the equilibrium position. The
control activity directly influences the vibration, the noise and the wear of the servo system. The proposed controllers demonstrated
superior behavior compared with other published structures. 相似文献
158.
M. S. Han S. O. Bang J. U. Cho S. Lee C. Cho 《International Journal of Automotive Technology》2013,14(1):61-66
The need for composites has been increasing in various industries because composites have good mechanical properties for their weight and superior stiffness and strength. The composites addressed in this study were multi-pore aluminum foam with a specific gravity of 1/10 composed of solid aluminum metal. This composite has excellent impact energy-absorption capability. In this study, impact tests on an aluminum foam core sandwich composite with a porous core were conducted to examine its mechanical properties. The specimen was a sandwich structure with an aluminum foam core, and different impact energies, such as 50J, 70J, and 100J, were applied to the specimen. Consequently, a maximum load of 5.5 kN occurred when the striker penetrated the upper face sheet in all experiments. The maximum load occurred at 4.2 ms for 50J, 3.5 ms for 70J, and 3.0 ms for 100J, indicating that the greater the impact energy was, the shorter the time was until the maximum load. After the maximum load occurred, that is, after the penetration of the upper face sheet, the striker penetrated 10 mm further, causing the core to be damaged in the 50J test, while the lower face sheet remained intact. In the 70J test, the striker penetrated the core and caused damage to the upper face sheet at 10 ms. Finally, in the 100J test, the striker penetrated both the upper face sheet and core and even the lower face sheet at 10 ms. Given the result above, the maximum load occurred when the striker penetrated the upper face sheet and the sandwich composite with aluminum foam core; the load then gradually decreased and then rapidly increased when the striker reached the lower face sheet, and the maximum load lasted slightly longer than the time required for the upper face sheet to be penetrated. 相似文献
159.
The increase in the world's trading capacity, which has been spurred by globalization, has caused problems in marine transportation, namely congestion. Despite the safety measures currently in place, marine accidents are still not being prevented. This study focuses on marine accidents in the Turkish Straits that have done serious harm to humans, the natural environment, and the economy. To reduce the negative impacts mentioned above, this study considered the most common types of accidents, their causes, and their results. For this purpose, 850 serious marine accidents, which took place in the Turkish Straits between the years of 2001 and 2010 (as recorded by the Undersecretaries for Maritime Affairs), have been analyzed and the data obtained have been systematically tabulated using analytic hierarchy process (AHP) methodology. According to the data, the most significant cause of marine accidents in the Turkish Straits is human error. This study proposes measures to ensure that ship personnel are competent, mentally and physically, to navigate narrow and dangerous waterways in order to minimize the amount of accidents caused by human error. 相似文献
160.
Özkan Uğurlu 《Maritime Policy and Management》2013,40(4):524-539
Navigation safety on coastal waters is an extremely important issue. Fatigue is an important factor threatening navigation safety. Considering that the vessel type is an oil tanker, such a threat is not posed only to the crew but also to the environment. Most of the tankers navigating coastal waters are in the small tanker category. Therefore, this study examined the working and resting hours of the deck officers in the oil tankers navigating coastal waters. The study utilized the ISF Watchkeeper 3 program for assessing and interpreting the working periods. The study reached the conclusion that the first and second officers in particular are working under unsuitable conditions. To improve the working conditions of the deck officers, effects of additional cargo officer on board was investigated. This study is in quality of recommendation. The study elucidated that the cargo officer practice determines the working and resting hours of deck officers, in the work on the oil tankers, and compliance with the related conventions. 相似文献