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991.
992.
A predictive continuum dynamic user-optimal (PDUO-C) model is formulated in this study to investigate the dynamic characteristics of traffic flow and the corresponding route-choice behavior of travelers within a region with a dense urban road network. The modeled region is arbitrary in shape with a single central business district (CBD) and travelers continuously distributed over the region. Within this region, the road network is represented as a continuum and travelers patronize a two-dimensional continuum transportation system to travel to the CBD. The PDUO-C model is solved by a promising solution algorithm that includes elements of the finite volume method (FVM), the finite element method (FEM), and the explicit total variation diminishing Runge-Kutta (TVD-RK) time-stepping method. A numerical example is given to demonstrate the utility of the proposed model and the effectiveness of the solution algorithm in solving this PDUO-C problem. 相似文献
993.
Khandker M. Nurul Habib 《Transportation》2011,38(1):123-151
The paper presents a modeling framework for dynamic activity scheduling. The modeling framework considers random utility maximization
(RUM) assumption for its components in order to capture the joint activity type, location and continuous time expenditure
choice tradeoffs over the course of the day. The dynamics of activity scheduling process are modeled by considering the history
of activity participation as well as changes in time budget availability over the day. For empirical application, the model
is estimated for weekend activity scheduling using a dataset (CHASE) collected in Toronto in 2002–2003. The data set classifies
activities into nine general categories. For the empirical model of a 24-h weekend activity scheduling, only activity type
and time expenditure choices are considered. The estimated empirical model captures many behavioral details and gives a high
degree of fit to the observed weekend scheduling patterns. Some examples of such behavioral details are the effects of time
of the day on activity type choice for scheduling and on the corresponding time expenditure; the effects of travel time requirements
on activity type choice for scheduling and on the corresponding time expenditure, etc. Among many other findings, the empirical
model reveals that on the weekend the utility of scheduling Recreational activities for later in the day and over a longer
duration of time is high. It also reveals that on the weekend, Social activity scheduling is not affected by travel time requirements,
but longer travel time requirements typically lead to longer-duration social activities. 相似文献
994.
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
995.
996.
Sang-Yeob Kim Kyong-Hwan Kim Yonghwan Kim 《Journal of Marine Science and Technology》2012,17(1):47-58
This paper considers a comparative study on model-scale sloshing tests. There are two primary scopes of this study: the comparison
of sloshing pressure measured in 1/50-scale model tests at Seoul National University (SNU) with (1) the data measured at the
other facility for the same model, and (2) the data measured on a smaller scale model. For the comparative study, model tanks
are excited with the same irregular motions with Froude scale, and sloshing pressure signals are measured at the same locations.
The statistical quantities of 1/50-scale model tests are compared with those of other facility and 1/70-scale model tests.
In this study, it is found that peak pressure measured at SNU are slightly lower than those of other facility, and this difference
may be due to different sensor types and sensing diameters. 相似文献
997.
M.?Oguma Y.?J.?LeeEmail author S.?Goto 《International Journal of Automotive Technology》2012,13(1):33-41
Recently, biofuels have been actively introduced as transportation fuels in Asian countries. Common drivers to use biofuels
are energy security, fuel diversification, and the reduction of greenhouse gases. In addition, some Southeastern Asian countries
look forward to utilizing the abundant agricultural resources and providing stability for farmers. However, a compromised
quality of biofuels could cause vehicle trouble, which is why the quality standard of the fuels is very important. On the
other hand, the quality standard of biofuels differs from country to country and could cause vehicle trouble in some countries
and not others. These differing standards may become an obstacle to trade. In this situation, the harmonization of the biodiesel
standards in the East Asia Summit (EAS) region has been initiated by the ERIA biodiesel working group, in which members are
the specialists from each country. This review summarizes the introduction of biofuels in this region and the recent activities
regarding the harmonization of the fuel quality standard. Important background for this review is based on the results of
the ERIA biodiesel working group meeting. 相似文献
998.
A dynamic lumped-parameter gear model incorporating the effects of a time-varying and asymmetric mesh stiffness and a backlash nonlinearity is formulated to analyze the spur gear rattle response under the idling condition. The proposed theory assumes a rectangular time-varying mesh stiffness function. The phase shift between the mesh stiffness for forward and backward contacts is examined. Numerical studies are employed to examine the effects of engine torque fluctuations and tooth surface friction on the gear rattle response and the corresponding tooth impact behavior. Comparisons between the results from the time-invariant mesh stiffness model and the proposed time-varying mesh stiffness model reveal differences in the gear responses, especially when the mean rotational speed of the fluctuating gear pair is non-zero. The analysis reveals significant effects on the high frequency response components. However, the idling gear dynamics are relatively insensitive to tooth surface friction. 相似文献
999.
S. O. Kang S. O. Jun H. I. Park K. S. Song J. D. Kee K. H. Kim D. H. Lee 《International Journal of Automotive Technology》2012,13(4):583-592
This research aims to develop an actively translating rear diffuser device to reduce the aerodynamic drag experienced by passenger cars. One of the features of the device is that it is ordinarily hidden under the rear bumper but slips out backward only under high-speed driving conditions. In this study, a movable arc-shaped semi-diffuser device, round in form, is designed to maintain the streamlined automobile??s rear underbody configuration. The device is installed in the rear bumper section of a passenger car. Seven types of rear diffuser devices whose positions and protrusive lengths and widths are different (with the basic shape being identical) were installed, and Computational Fluid Dynamics (CFD) analyses were performed under moving ground and rotating wheel conditions. The main purpose of this study is to explain the aerodynamic drag reduction mechanism of a passenger car cruising at high speed via an actively translating rear diffuser device. The base pressure of the passenger car is increased by deploying the rear diffuser device, which then prevents the low-pressure air coming through the underbody from directly soaring up to the rear surface of the trunk. At the same time, the device generates a diffusing process that lowers the velocity but raises the pressure of the underbody flow, bringing about aerodynamic drag reduction. Finally, the automobile??s aerodynamic drag is reduced by an average of more than 4%, which helps to improve the constant speed fuel efficiency by approximately 2% at a range of driving speeds exceeding 70 km/h. 相似文献
1000.
If a driver passes over a pedestrian lying on the road and flees, it is considered a crime. In several cases, even if the
driver fled and was arrested, he/she often asserts that they did not know that the victim was a human being. However, the
investigation agency often believes that a driver can certainly recognize when he/she passes over a person. Accordingly, such
cases frequently lead to disputes due to the lack of criteria for recognizing when a driver was involved in run-over accidents.
In this study, tests were conducted both to identify if drivers can recognize whether their vehicles passed over a person
and to examine how they feel at the time. A silicon dummy, which was manufactured to have the same characteristic as the human
chest, was used in this study. According to the method specified in ISO2631, the vibration delivered to the driver was measured,
and eighteen participants drove a vehicle over the silicon dummy to experience how the vibrations felt. When the passenger
car for the test ran over the dummy at speeds ranging from 10 km/h to 60 km/h, all participants recognized the delivered vibration,
and the VDV that was delivered to the participants ranged from 1.81 m/s
1.75 to 2.38 m/s
1.75. The participants thought that the object they drove over was a stone or a piece of wood. This indicates that the driver
certainly can recognize the vibrations generated from passing over a human chest even though it feels like a solid object. 相似文献