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171.
William A. Podgorski Allan I. Krauter Richard H. Rand 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1975,4(1):9-41
The equations of motion are derived for a single wheel steerable pneumatic tire system. Included in this system are a built-in wheel wobble and wheel-tire irregularities which produce oscillation of the normal load. Special emphasis is placed on the dynamic characterization of the tire cornering force and aligning torque. The results show that the built-in wheel wobble causes a steady shimmy which is large when the wheel rotation frequency is close to the natural shimmy frequency. The results also show that a normal load oscillation which has a frequency approximately twice the natural shimmy frequency causes a decrease in shimmy stability. 相似文献
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Joachim L. Grenestedt Jun Cao William J. Maroun 《Journal of Marine Science and Technology》2008,13(1):63-70
A hybrid ship hull model made with a steel truss and composite sandwich panels was tested and analyzed with the goal of gaining
insight into how well this structural concept holds up after major damage. One of the ideas of the concept was to mount the
sandwich panels to the steel truss such that they can be blown out in a controlled fashion to ventilate a large internal blast.
The hull should be designed to have sufficient strength for the ship to reach a port safely even after such extensive damage.
A 6-m model of such a hybrid ship hull, consisting of a stainless steel truss and 60 composite sandwich panels, was manufactured
and mechanically tested. A number of panels were then removed one by one and the hull was retested to the design load after
each panel had been removed. The removed panels simulated major damage. After nine panels had been removed, from all the different
areas of the hull, it could still carry the design load, although with considerable nonreversible deformations of the hull
girder. The hull was eventually loaded to final failure, which occurred at 25% above the design load. 相似文献
176.
Individuals processing the information in a stated choice experiment are typically assumed to evaluate each and every attribute offered within and between alternatives, and to choose their most preferred alternative. However, it has always been thought that some attributes are ignored in this process for many reasons, including a coping strategy to handle ones perception of the complexity of the choice task. Nonetheless, analysts typically proceed to estimate discrete choice models as if all attributes have influenced the outcome to some degree. The cognitive processes used to evaluate trade-offs are complex with boundaries often placed on the task to assist the respondent. These boundaries can include prioritising attributes and ignoring specific attributes. In this paper we investigate the implications of bounding the information processing task by attribute elimination through ignoring one or more attributes. Using a sample of car commuters in Sydney we estimate mixed logit models that assume all attributes are candidate contributors, and models that assume certain attributes are ignored, the latter based on supplementary information provided by respondents. We compare the value of travel time savings under the alternative attribute processing regimes. Assuming that all attributes are not ignored and duly processed, leads to estimates of parameters which produce significantly different willingness to pay (WTP) to that obtained when the exclusion rule is invoked. 相似文献
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This paper proposes an elastic demand network equilibrium model for networks with transit and walking modes. In Hong Kong, the multi‐mode transit system services over 90% of the total journeys and the demand on it is continuously increasing. Transit and walking modes are related to each other as transit passengers have to walk to and from transit stops. In this paper, the multi‐mode elastic‐demand network equilibrium problem is formulated as a variational inequality problem where the combined mode and route choices are modeled in a hierarchical logit structures and the total travel demand for each origin‐destination pair is explicitly given by an elastic demand function. In addition, the capacity constraint for transit vehicles and the effects of bi‐directional flows on walkways are considered in the proposed model. All these congestion effects are taken into account for modeling the travel choices. A solution algorithm is developed to solve the multi‐mode elastic‐demand network equilibrium model. It is based on a Block Gauss‐Seidel decomposition approach coupled with the method of successive averages. A numerical example is used to illustrate the application of the proposed model and solution algorithm. 相似文献
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