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41.
The concept of accessibility has been variously interpreted as being the “nearness to places,” the “nearness to activities” and more recently the “ease of participating in activities.” With each of these qualitative interpretations, there has also been a variety of quantitative definitions of accessibility. This paper shows that many of the proposed definitions of accessibility can in fact be gathered together to form a spectrum of accessibility measures. These measures differ with respect to the factors included in their formulation and their degree of behavioural interpretation. Existing measures of accessibility are shown to be deficient in one major aspect. That is, they assume that for any one measure of accessibility there is but one origin of trips. Thus, in estimating the accessibility of a point within a region it is assumed that all potential trips, which contribute to the accessibility of that point, start from that single point. In view of the considerable amount of evidence demonstrating the widespread, and increasing, occurrence of trip‐linking such a proposition must be viewed as being rather doubtful. In the light of this, the paper proceeds to develop a measure of accessibility which explicitly accounts for the linking of trips. The implications of this measure, compared to a conventional unlinked‐trip accessibility measure, are discussed as are some problems which are foreseen in the practical implementation of such a measure. 相似文献
42.
The Australian Railway Research and Development Organisation is conducting a study with one of its objectives being to determine factors affecting freight mode use. Part of this has included the development and calibration of freight mode choice models. This paper outlines the results obtained from the application of an Elimination‐by‐Aspects (EBA) model to this task. The paper describes the theoretical background to the EBA model, within the context of a general choice process, and then describes the results of the model when applied to three samples of shippers involved in regional freight transport. 相似文献
43.
The Second International Conference on New Survey Methods in Transport was held at Hungerford Hill, Australia in September 1983. The aims of the conference were to provide a focus for discussion of survey methodology and to establish bench‐marks with respect to the state of the art in various facets of transport surveys. The conference evolved around workshops in twelve key areas: sample design, survey needs for modelling, questionnaire design and piloting, perceptual studies, diary surveys, longitudinal studies, interactive survey methods, freight surveys, traffic surveys, total design concepts, response errors and data correction, and coding and computing. A number of plenary keynote papers were also presented describing the state of the art in cross‐sectional, longitudinal and interactive survey methods. Emerging from the conference discussions, six key issues were prominent; the gap between the state of the art, as espoused by researchers, and the state of practice, as employed by practioners; the differences in results obtained when employing different survey methods to collect essentially the same data; the emerging use of the telephone for the conduct of interview travel surveys; the interaction between survey methods and demand modelling and the disparate levels of sophistication in the two areas; the role of microcomputers in the design, conduct and analysis of transport surveys; and the need for practitioners to engage in controlled experimentation, so that methodological advances may continue to be made in the field of transport surveys. 相似文献
44.
Transportation - Urban utility cycling is being promoted widely due to various health, social, economic and environmental benefits. This study seeks to identify and rank which municipal-level... 相似文献
45.
The quenching of a metal component with a channel section in a water tank is numerically simulated. Computational fluid dynamics
(CFD) is used to model the multiphase flow and the heat transfer in film boiling, nucleate boiling and convective cooling
processes to calculate the difference in heat transfer rate around the component and then combining with the thermal simulation
and structure analysis of the component to study the effect of heat transfer rate on the distortion of the U-channel component.
A model is also established to calculate the residual stress produced by quenching. The coupling fluid-thermal-structural
simulation provides an insight into the deformation of the component and can be used to perform parameter analysis to reduce
the distortion of the component. 相似文献
46.
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48.
The effect of location,mobility and socio-demographic factors on task and time allocation of households 总被引:1,自引:0,他引:1
This paper investigates the role of location factors in task and time allocation at the household level. It is hypothesized
that, if time constraints are less binding as a result of living in an urban area or owning more cars, spouses engage more
often and longer in out-of-home activities and schedule their activities more independently. The hypotheses are tested with
logistic and Cox regression models of activity participation and time allocation on a data set collected in the Amsterdam–Utrecht
region in the Netherlands. Results suggest that the hypotheses are supported with respect to specific household activity scheduling
decisions. 相似文献
49.
Part I of this paper has argued that any meaningful evaluation of transport system safety must include a consideration of the exposure to accidents, and has demonstrated the use and limitations of several measures of exposure at intersections and along links of the network. To complement this treatment of site exposure, this part of the paper will describe the use of group exposure measures in the assessment of risks incurred by people within particular population groupings. The use of induced exposure measures is also briefly reviewed. 相似文献
50.
This paper introduces a new method for the prediction of ship maneuvering capabilities. The new method is added to a nonlinear
six-degrees-of-freedom ship motion model named the digital, self-consistent ship experimental laboratory (DiSSEL). Based on
the first principles of physics, when the ship is steered, the additional surge and sway forces and the yaw moment from the
deflected rudder are computed. The rudder forces and moments are computed using rudder parameters such as the rudder area
and the local flow velocity at the rudder, which includes contributions from the ship velocity and the propeller slipstream.
The rudder forces and moments are added to the forces and moments on the hull, which are used to predict the motion of the
ship in DiSSEL. The resulting motions of the ship influence the inflow into the rudder and thereby influence the force and
moment on the rudder at each time step. The roll moment and resulting heel angle on the ship as it maneuvers are also predicted.
Calm water turning circle predictions are presented and correlated with model test data for NSWCCD model 5514, a pre-contract
DDG-51 hull form. Good correlations are shown for both the turning circle track and the heel angle of the model during the
turn. The prediction for a ship maneuvering in incident waves will be presented in Part 2. DiSSEL can be applied for any arbitrary
hull geometry. No empirical parameterization is used, except for the influence of the propeller slipstream on the rudder,
which is included using a flow acceleration factor. 相似文献