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461.
462.
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
463.
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
464.
465.
The future tourism mobility of the world population: Emission growth versus climate policy 总被引:1,自引:0,他引:1
Ghislain Dubois Paul PeetersJean-Paul Ceron Stefan Gössling 《Transportation Research Part A: Policy and Practice》2011,45(10):1031-1042
Much of global passenger transport is linked to tourism. The sector is therefore of interest in studying global mobility trends and transport-related emissions. In 2005, tourism was responsible for around 5% of all CO2 emissions, of which 75% were caused by passenger transport. Given the rapid growth in tourism, with 1.6 billion international tourist arrivals predicted by 2020 (up from 903 million in 2007), it is clear that the sector will contribute to rapidly growing emission levels, and increasingly interfere with global climate policy. This is especially true under climate stabilisation and “avoiding dangerous climate change” objectives, implying global emission reductions in the order of −50% to −80% by 2050, compared to 2000. Based on three backcasting scenarios, and using techniques integrating quantitative and qualitative elements, this paper discusses the options for emission reductions in the tourism sector and the consequences of mitigation for global tourism-related mobility by 2050. It ends with a discussion of the policy implications of the results. 相似文献
466.
Ibrahim Elbadawy Mohamed Elsebay Mohamed Shedid Mohamed Fatouh 《International Journal of Automotive Technology》2018,19(2):233-243
Nanofluids, the fluid suspensions of nanomaterial, became a promising fluid that is invoked when heat transfer increase is required. Using of nanofluids as a coolant in the engine radiators is a crucial topic for the thermal engines manufactrers due to the expected enhancement in the cooling process. In this study, Two nanofluids (Al2O3/water and CuO/water) flowing in a flat tube of radiator are investigated numerically to evaluate thermal and flow performance. The resizing process for the radiator is performed by using nanofluid instead of water flow. A significant reduction in the radiator volume is achieved due to marked improvement in the heat transfer performance while, the required pumping power after this reduction in the volume is increased over that needed for base fluid. The normalized heat transfer (heat transfer to the pumping power) is found to be a function of both Reynolds number and nanofluid concentration ratio while the ratio of the normalized heat transfer is found to be dependent only on the nanofluid concentration ratio. These dependencies are formulated as general correlations. 相似文献
467.
Junho Cho Tae-Kyung Kim Kyu-Hong Kim Kwanjung Yee 《International Journal of Automotive Technology》2017,18(6):959-971
To reduce the aerodynamic drag, the performance of the underbody aerodynamic drag reduction devices was evaluated based on the actual shape of a sedan-type vehicle. An undercover, under-fin, and side air dam were used as the underbody aerodynamic drag reduction devices. In addition, the effects of the interactions based on the combination of the aerodynamic drag reduction devices were investigated. A commercial sedan-type vehicle was selected as a reference model and its shape was modeled in detail. Aerodynamic drag was analyzed by computational fluid dynamics at a general driving speed on highway of 120 km/h. The undercover reduced the slipstream area through the attenuation of the longitudinal vortex pair by enhancing the up-wash of underflow, thereby reducing the aerodynamic drag by 8.4 %. The under-fin and side air dam showed no reduction in aerodynamic drag when they were solely attached to the actual complex shape of the underbody. Simple aggregation of the effects of aerodynamic drag reduction by the individual device did not provide the accurate performance of the combined aerodynamic drag reduction devices. An additional aerodynamic drag reduction of 2.1 % on average was obtained compared to the expected drag reduction, which was due to the synergy effect of the combination. 相似文献
468.
Unghui Lee Jiwon Jung Seokwoo Jung David Hyunchul Shim 《International Journal of Automotive Technology》2018,19(1):191-197
Lane and road recognition are essential for self-driving where GPS solution is inaccurate due to the signal block or multipath in an urban environment. Vision based lane or road recognition algorithms have been studied extensively, but they are not robust to changes in weather or illumination due to the characteristic of the sensor. Lidar is a sensor for measuring distance, but it also contains intensity information. The road mark on the road is made to look good with headlight at night by using a special paint with good reflection on the light. With this feature, road marking can be detected with lidar even in the case of changes in illumination due to the rain or shadow. In this paper, we propose equipping autonomous cars with sensor fusion algorithms intended to operate in a different weather conditions. The proposed algorithm was applied to the self-driving car EureCar (KAIST) in order to test its feasibility for real-time use. 相似文献
469.
The secure socket layer/ transport layer security(SSL/TLS) handshake protocol uses public key cryptographic algorithms such as RSA for key establishment. Typically, public key cryptographic algorithm is computational intensive due to the modular multiplications. Therefore, SSL/TLS servers often become swamped while performing public key decryptions when the simultaneous requests increase quickly. A batch RSA decryption algorithm was proposed. The novel algorithm provides the reasonable response time and optimizes server performance significantly. The decryption speedup is proportional to the batch size b, for instance, the speedup factor is 4, while in Shacham's scheme the acceleration rate is only 2.5 when b = 4. 相似文献
470.
Ji Hyun Yang Sang Yeong Choi Kang Park 《International Journal of Automotive Technology》2018,19(5):915-922
This paper proposes a systematic framework for operability evaluation of remotely controlled ground combat systems (RGCS) in a simulated environment. The popular human-robot interaction metric used in unmanned vehicle systems is called fan-out (FO) and represents the maximum number of robots/vehicles that could be controlled by a single human operator. However, FO is inappropriate for systems with a lower level of automation where vehicles are remotely controlled by a human, such as RGCS. The theoretical background of the suggested framework is based on McRuer’s crossover model that was initially developed in the aviation domain for explaining pilot handling issues. In this study, an evaluation/analysis software prototype was developed, known as the RGCS operability evaluation tool in a simulated environment (ROPES). The ROPES was designed to be a simple tool for use by officers or researchers who only have intuitive understanding on the human adaptability. The ROPES includes two sub-modules; 1) an interactive interface for the configuration of the RGCS dynamic parameters and user interfaces and 2) a time-varying graphical display of system and human performance. Examples case studies demonstrate the advantage of the ROPES, and improvement points were identified for future development. 相似文献