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111.
Continuously Variable Transmission (CVT) is one of the most promising automotive transmission technologies because of its
continuously variable gear ratio and reduced shift shock. CVT is different from Manual Transmission and Automatic Transmission,
and it is possible to operate the power source in its high efficiency region with CVT in the drive train. Several types of
CVT exist that can be categorized based on the mechanism of power transmission, such as the belt pulley, traction drive, and
hydrostatic types. This paper investigates the belt pulley CVT, which consists of a thrust actuator, driver pulley, belt,
driven pulley, and preload spring of the output shaft. A complete CVT is constructed, and based on that a simulation program
that analyzes the static performance of a CVT is implemented in Matlab/Simulink. From these simulation results, methods for
improving the efficiency of the CVT are discussed. The coefficient of the torque capacity factor is proposed as affecting
the matching between a power source and a CVT, and methods for improving the matching effect are also investigated. 相似文献
112.
D. H. Kim J. M. Lee E. H. Park J. H. Song S. I. Park 《International Journal of Automotive Technology》2011,12(3):409-416
A comprehensive study evaluating the performance of biobutanol-blended gasoline in passenger cars was conducted because biobutanol
is considered a better biofuel than bioethanol as it has no water solubility and it has a higher caloric value, giving it
a higher energy value. Several kinds of samples—suboctane gasoline, 8 volume percentage and 16 volume percentage biobutanol—blended
gasoline, and a 10 volume percentage MTBE-blended market sample (as the oxygencontaining gasoline)-were tested to evaluate
the engine performance in terms of the detergency of the intake valves and combustion chambers, power, emissions, and fuel
efficiency. Additionally, the toxicity of the emissions from these biobutanolblended samples was tested in order to assess
the viability of biobutanol as one of the competitive potential substitutes for MTBE as an oxygenator in the near future.
The results show that biobutanol-blended gasoline samples had relatively better detergency, relatively higher power, and similar
levels of emissions compared with those of MTBE-blended gasoline. Formaldehyde was emitted from all of the samples at almost
the same levels and within the error range, whereas biobutanolblended gasoline samples emitted approximately three times the
amount of acetaldehyde than did the suboctane gasoline. This study shows that biobutanol is one of the best alternative bioalcohol
fuels for use in the near future. 相似文献
113.
W.-H. Cho J.-G. Ih S.-H. Shin J.-W. Kim 《International Journal of Automotive Technology》2011,12(3):443-450
In this paper, a method to establish a decision criterion to evaluate the quality of small window motors using sound quality
(SQ) metrics is suggested. Although the sound level radiated from the motor is relatively small compared to other sounds in
a car, the sound from an abnormal motor gives an uncomfortable feeling and the impression of abnormal operation, which can
lead to customer complaints. To construct an objective decision criterion, the correlation between the SQ metrics and the
subjective decision on the passing or failure of the motor were investigated. Four representative SQ metrics, viz., loudness,
sharpness, roughness, and fluctuation strength, were calculated for the collected samples. It was observed that the loudness
and roughness of the motor sample group classified as abnormal was higher than those of the normal motors. For a single figure
rating for motor quality, an evaluation index for the motor sound was generated by combining the correlated SQ metrics with
proper weightings. Evaluation results on the specimens that were not employed in generating the quality evaluation index showed
a reasonable agreement with the subjective test at 73%. The suggested quality check method can replace the current subjective
decision procedure to identify the faulty motors. 相似文献
114.
Y. Kim S. Choi J. Lee W. Yoo J. Sohn 《International Journal of Automotive Technology》2011,12(4):521-527
In this study, a large bus is tested to measure its dynamic response by the single-lane change test and the rapid stop test.
A full car model is established by ADAMS/Car for computer simulation. For multibody modeling of a large bus, user-defined
templates are used in the simulation. Simulation results of the single-lane change test and the rapid braking test are compared
to the results of the physical experiments, in which several sensors are installed to measure the vehicle’s responses. The
results obtained from the simulation show good agreement with the tests’ results. A dynamic model for the MR(magnetic-rheological)
damper is also developed by employing the Magic Formula model, which is widely used in the nonlinear modeling of a tire. Bump
simulation of a full car with the MR damper is carried out to verify the performance of the MR damper. The comparison of the
simulation results obtained with the MR damper model to the results obtained with the traditional passive damper model showed
improved response of the vehicle with the MR damper. 相似文献
115.
This paper discusses the final investigation into the effect of fuel stratification on flame propagation. In previous works,
the characteristics under the no port-generated swirl condition and the low-swirl condition were considered. For this purpose,
the initial flame development and propagation were visualized under different axially stratified states in a modified optical
single-cylinder SI engine. The images were captured by an intensified CCD camera through the quartz window mounted in the
piston. Stratification was controlled by the combination of the port swirl ratio and injection timing. These were averaged
and processed to characterize the flame propagation. The flame stability was estimated by the weighted average of flame area
and luminosity. The stability was also evaluated through the standard deviation of flame area and propagation distance and
through the mean absolute deviation of the propagation direction. The results show that the LML is expanded remarkably under
the high-swirl cases up to the highest relative AFRs of 1.71 and 1.75 between 140 and 160CA. In addition, similar to the low-swirl
condition, the flame-flow interaction determines the direction of flame propagation, and the governing roles of the two factors
vary according to the swirl level; the flow is more important at the higher swirl conditions, and the flame is more important
at the lower swirl condition. Finally, fast and stable flame propagation can be achieved under the preferably stratified condition,
which is induced by the suitable combination of the high swirl and injection timing. 相似文献
116.
This paper establishes a link between an activity-based model for the Greater Toronto Area (GTA), dynamic traffic assignment,
emission modelling, and air quality simulation. This provides agent-based output that allows vehicle emissions to be tracked
back to individuals and households who are producing them. In addition, roadway emissions are dispersed and the resulting
ambient air concentrations are linked with individual time-activity patterns in order to assess population exposure to air
pollution. This framework is applied to evaluate the effects of a range of policy interventions and 2031 scenarios on the
generation of vehicle emissions and greenhouse gases in the GTA. Results show that the predicted increase of approximately
2.6 million people and 1.3 million jobs in the region by 2031 compared to 2001 levels poses a major challenge in achieving
meaningful reductions in GHGs and air pollution. 相似文献
117.
This paper examines the location choice associated with discretionary activities (in-home vs. out-of-home). These substitution
patterns are important in terms of travel demand as in-home activities do not necessitate travel while out-of-home activities
incur travel. Mixed logit models are estimated using an activity dataset (2003 CHASE data) to analyze the factors associated
with this choice at the individual activity-level. Results suggest that the attributes of an activity significantly contribute
to understanding the likelihood of engaging in out-of-home activities. Activity type interaction terms reveal the varying
influence that socio-demographics, activity attributes and travel have over four different activity types modeled. The results
reveal that the location choice (in-home vs. out-of-home) is sensitive to travel characteristics. As the travel time and cost
increases, an individual is less likely to engage in an activity out-of-home. Compared to passive and social activities, the
location of active activities is more sensitive to changes in travel attributes. 相似文献
118.
Evangelia N. KaselimiAuthor Vitae Theo E. NotteboomAuthor Vitae Athanasios A. PallisAuthor Vitae Sheila FarrellAuthor Vitae 《Research in Transportation Economics》2011,32(1):71-80
The decision on the scale of a port terminal affects the terminal’s managerial, operational and competitive position in all the phases of its life. It also affects competition structures in the port in which the terminal is operating, and has a potential impact on other terminals. Port authorities and terminal operators need to know the scale of the terminal when engaging in concession agreements. In economic theory the scale of a plant/firm is typically defined in relation to the Minimum Efficient Scale (MES), the long-run output where the internal economies of scale are fully exploited. However, there are a number of theoretical and empirical indications that in ports the scale of a terminal is commonly guided by a combination of the MES and other determining factors. The “preferred” scale is the result of a complex interaction between the MES, the port governance framework and objectives, the market size and structure, technological change and operational considerations, physical and geographical limitations, and the business patterns of shipping lines. This study analyses the factors resulting in a preferred container terminal scale that in most of the times is different from the MES. The analysis of the technical, market-related and governance-related factors is supported by theoretical and empirical insights that illustrate the presence of a range of actual ”preferred” scales of terminal concessions that usually are different, below or above, MES. 相似文献
119.
陈娥 《电力机车与城轨车辆》2022,(1):90-92
针对解析法无法对电机转子局部结构导致的损耗和励磁电流进行定量分析的问题,文章提出在采用解析法进行初步方案计算的基础上,引入电磁仿真技术,并以190 kW异步牵引电机为例,分析和计算了附加损耗以及空载电流随通风孔数量的变化,通过试验验证了采用电磁仿真技术的有效性. 相似文献
120.
Hub‐and‐spoke networking is a key feature of current aviation markets in which hubs, as connecting points, function to consolidate and redistribute flows. This indicates that observation of traffic on a segment does not necessarily convey information about the origin to destination routing of passenger journeys because of the unavoidable detours in the system. This paper examines the heterogeneity of the flow composition in domestic and international US markets, which in turn allows us to observe the variation of operations across major hubs. A modified Route Flow Estimator for origin–destination synthesis (or origin–destination matrix estimation) is designed to decompose the segment traffic into itinerary‐based passenger trips. Several public and commercial databases, which are easily accessible, are exploited (and reconciled) for the model in order to (i) generate possible trip itineraries using those segment markets, and (ii) link data‐driven operational conditions with the underlying segment flows. The results are validated with US domestic trip observations and empirical knowledge related to the air transportation system. Then, the variability of the hub operations is examined based on sensitivity tests using the model parameters. From the resolution of itinerary‐based estimates, we observe that major airports' hub operations are spatially uneven, particularly with respect to domestic and international connecting passengers. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献