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121.
122.
Jacqueline Arriagada Antonio Gschwender Marcela A. Munizaga Martin Trépanier 《智能交通系统杂志
》2019,23(4):332-344
》2019,23(4):332-344
Bus bunching is a well-known phenomenon for operators, users and regulators of high-frequency bus services. Bus operations are usually affected by increasing differences in the time intervals (headways) between consecutive buses. The effect of this variability is that buses tend to group into bunches of two or more, which severely affects the quality of service and the operational efficiency. The aim of this paper is to analyze which factors are associated to the phenomenon, using massive data from high-frequency services available in Santiago (Chile) and common-route services in Gatineau (Canada). The data is obtained from the bus GPS and AFC systems and are processed to obtain headways between buses. Using data from one week, we develop models to explain the variation of the continuous and discrete indicators of bus bunching as a function of variables related to the operation, variables related to the demand structure, and variables related to the infrastructure. Some of the factors that contribute to increase bus bunching are: stops located toward the end of the route, high scheduled frequency, irregular bus dispatch headways, non-homogeneous fleet, high demand, and high variability of demand. The results are useful for the design of quality indexes to measure bunching in bus operations, and for the design and operation of bus routes, taking into consideration the potential bus bunching problems. 相似文献
123.
车胎压力监测系统简述及两种实现方案 总被引:3,自引:0,他引:3
车胎压力对汽车的安全行驶至关重要,保障车胎压力正常的汽车轮胎压力监测系统(TirePressureMonitoringSystem,TPMS)受到国内外汽车工业界越来越多的重视。本文对目前常用的两种TPMS实现方案:间接监测和直接监测方法做了详细的介绍,并对两种方法的性能指标做了全面的对比。 相似文献
124.
Atsuo Maki Naoya Umeda Martin Renilson Tetsushi Ueta 《Journal of Marine Science and Technology》2010,15(3):218-229
Making use of Melnikov’s method, a generalized formula for predicting the surf-riding threshold is developed as an extension
to the applications of Kan and Spyrou. A new analytical formula for calculating the surf-riding threshold of a ship in following
seas is also proposed in light of nonlinear dynamical system theory. By applying a continuous piecewise linear approximation
to the wave-induced surge force, a heteroclinic bifurcation point is obtained analytically with an uncoupled surge equation.
Results calculated using these formulae are presented, and they show good agreement with those obtained utilizing numerical
bifurcation analysis. Further, it was confirmed that the surf-riding threshold obtained using the proposed formulae agrees
reasonably well with that obtained experimentally for an unconventional vessel. 相似文献
125.
Transportation - Commuting between home and work is routinely performed by workers and any wellbeing impacts of commuting will consequently affect a large proportion of the population. This paper... 相似文献
126.
ABSTRACTAutomated vehicles (AVs) could completely change mobility in the coming years and decades. As AVs are still under development and gathering empirical data for further analysis is not yet possible, existing studies mainly applied models and simulations to assess their impact. This paper provides a comprehensive review of modelling studies investigating the impacts of AVs on travel behaviour and land use. It shows that AVs are mostly found to increase vehicle miles travelled and reduce public transport and slow modes share. This particularly applies to private AVs, which are also leading to a more dispersed urban growth pattern. Shared automated vehicle fleets, conversely, could have positive impacts, including reducing the overall number of vehicles and parking spaces. Moreover, if it is assumed that automation would make the public transport system more efficient, AVs could lead to a favouring of urbanisation processes. However, results are very sensitive to model assumptions which are still very uncertain (e.g. the perception of time in AVs) and more research to gain further insight should have priority in future research as well as the development of the models and their further adaptation to AVs. 相似文献
127.
We are living in a time of accelerating technological development, which affects us all in our professional and social lives. Using data obtained from a 2-day activity-travel-communication diary survey in the Utrecht?CAmersfoort?CHilversum region in the Netherlands, we enhance insight into the use of Information and Communication Technologies by professionals of different types. The multivariate analyses show that one quarter of the sample has traditional work arrangements with continuous work at one location and shows a relatively low use of electronic communication modes. Half the professionals are telecommuters-car commuters and have short face-to-face and email contacts or are telecommuters-public transport commuters who in contrast rely on emails and face-to-face contacts. The final quarter of the sample shows a highly fragmented temporal work pattern with intensive face-to-face and electronic contacts. 相似文献
128.
Martin Hassel Ingrid Bouwer Utne Jan Erik Vinnem 《WMU Journal of Maritime Affairs》2017,16(2):175-195
The Norwegian Petroleum Safety Authority (PSA) requires offshore petroleum operators on the Norwegian Continental Shelf (NCS) to perform risk assessments of impacts (allisions) between passing ships and offshore installations. These risk assessments provide a basis for defining the allision accidental load that the installation shall be designed for. Even though the risk of allision is small, the potential consequences can be catastrophic. In a worst-case scenario, an allision may result in the total loss of an installation. The ageing industry standard allision risk model, COLLIDE, calculates the risk of impacts between passing (non-field-related) ships and installations based on Automatic Identification System (AIS) data. Both the COLLIDE risk model and a new Bayesian allision risk model currently under development are highly sensitive to variations in vessels’ passing distances, especially close proximity passings. Allision risk assessments are typically performed during the design and development phase of an installation, which means that historical AIS data are used “as is”, disregarding future changes to the traffic pattern when the new installation is placed on a location. This article presents an empirical study of one of the most important variables used to calculate the risk of allision from passing vessels, namely passing distance. The study shows that merchant vessels alter course to achieve a safe passing distance to new surface offshore petroleum installations. This indicates that the results of current allision risk assessments are overly conservative. 相似文献
129.
Stefan Forster Robert Turnewitsch Martin Powilleit Stephan Werk Florian Peine Kai Ziervogel Michael Kersten 《Journal of Marine Systems》2009,75(3-4):360-370
Activities of the naturally occurring, short-lived and highly particle-reactive radionuclide tracer 234Th in the dissolved and particulate phase were measured at three shallow-water stations (maximum water depths: 15.6, 22.7 and 30.1 m) in Mecklenburg Bay (south-western Baltic Sea) to constrain the time scales of the dynamics and the depositional fate of particulate matter. Activities of particle-associated (> 0.4 μm) and total (particulate + dissolved) 234Th were in the range of 0.08–0.11 dpm L− 1 and 0.11–0.20 dpm L− 1, respectively. The activity ratio of total 234Th and its long-lived and conservative parent nuclide 238U was well below unity (range: 0.09–0.19) indicating substantial radioactive disequilibria throughout the water column, very dynamic trace-metal scavenging and particle export from the water column at all three stations. For the discussion the 234Th data of this study were combined with previously published water-column 234Th and particulate-matter data from Mecklenburg Bay (Kersten et al., 1998. Applied Geochemistry 13, 339–347). The resulting average vertical distribution of total 234Th/238U disequilibria was used to estimate the depositional 234Th flux to the sediment. There was a virtually constant net downward flux of 234Th of about 28 dpm m− 2 d− 1 leaving each water layer of one meter thickness. Thorium-234-derived net residence times of particulate material regarding settling from a given layer in the water column were typically on the order of days, but with maximum values of up to a couple of weeks. Based on an average ratio of particulate matter (PM) to particle-associated 234Th a net flux of about 145 mg PM m− 2 d− 1 was estimated to leave each water layer of one meter thickness. The estimated cumulative water-column-derived particulate-matter fluxes at the seafloor are higher by a factor of about 2 than previously published sediment-derived estimates for Mecklenburg Bay. This suggests that about half of the settling particulate material is exported from the study area and/or subject to processes such as mechanical breakdown, remineralisation and dissolution. Lateral particulate-matter redistribution and particle breakdown in the water column (as opposed to the sediment) seem to be favoured by (repeated) particle resuspension from and resettling to the seafloor before ultimate sedimentary burial. The importance of net lateral redistribution of particulate material seems to increase towards the seafloor and be particularly high within the bottommost few meters of the water column. 相似文献
130.
The widespread adoption of information and communication technologies (ICT) and flexible work arrangements have enabled people
to schedule their work activities in more flexible ways. New forms of working have already emerged. However, research about
flexible work schedules is still scarce. The aim of this study is to determine the factors impacting the propensity to adopt
a flexible work schedule, and establish how and to what extent the timing of work is influenced by ICTs, work, and sociodemographic
characteristics. The analysis suggests that work-related characteristics and ICT usage seem to be more important for work-schedule
flexibility than sociodemographic characteristics are. 相似文献