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71.
W. Fauriat C. Mattrand N. Gayton A. Beakou T. Cembrzynski 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(5):585-605
When assessing the statistical variability of fatigue loads acting throughout the life of a vehicle, the question of the variability of road roughness naturally arises, as both quantities are strongly related. For car manufacturers, gathering information on the environment in which vehicles evolve is a long and costly but necessary process to adapt their products to durability requirements. In the present paper, a data processing algorithm is proposed in order to estimate the road profiles covered by a given vehicle, from the dynamic responses measured on this vehicle. The algorithm based on Kalman filtering theory aims at solving a so-called inverse problem, in a stochastic framework. It is validated using experimental data obtained from simulations and real measurements. The proposed method is subsequently applied to extract valuable statistical information on road roughness from an existing load characterisation campaign carried out by Renault within one of its markets. 相似文献
72.
Passenger waiting time and information acquisition using automatic vehicle location for verification
Randolph W. Hall 《运输规划与技术》2013,36(3):249-269
Bus riders utilize a variety of information media to learn how to travel to their destinations and to learn when they should arrive at bus stops. As part of the OCTA (Orange County Transit Authority) Transit Probe evaluation, 1199 passengers were surveyed to measure relationships between information acquisition and waiting time. A unique aspect of the survey was that some of the data could be correlated with automatic‐vehicle‐location (AVL) measurements of bus lateness at stops. Insights are provided as to the types of information riders acquire based on the nature of the trip and demographic characteristics. Insights are also provided as to factors affecting perceived waiting time. We found age group, whether a person needs to arrive at a destination by a specific time, primary language, and whether the person is a first‐time user of the bus line to be significant causal factors. 相似文献
73.
Two major environmental problems currently affecting the Louisiana coastal zone are a high rate of wetland loss and high levels of surface water pollution. The application of secondarily treated wastewater to wetlands can be a means of dealing with both of these problems. The benefits of wetland wastewater treatment include improved surface water quality, increased accretion rates to balance a high relative water level rise due mainly to subsidence, improved plant productivity and habitat quality, and decreased capital outlays for conventional engineering treatment systems. Wetland treatment systems can, therefore, be designed and operated to restore deteriorating wetlands. Hydrologically altered wetlands, which are common in the Louisiana coastal zone, are appropriate for receiving municipal and some types of industrial effluent. While the U.S. Environmental Protection Agency has determined wetland wastewater treatment is effective in treating municipal effluent, it has discouraged the use of natural wetlands for this purpose. At the same time, funds are being used for the construction of artificial wetlands to treat municipal effluent. In the Louisiana coastal zone, however, wetlands are deteriorating and disappearing due to hydrological alteration and a high rate of relative sea level rise. If no action is taken, these trends will continue. Effluent discharge to existing wetlands should be incorporated into a comprehensive management plan designed to increase sediment and nutrient input into subsiding wetlands in the Louisiana coastal zone, improve water quality, and result in more economical waste‐water treatment. The authors believe that the Louisiana example serves as a model for other coastal areas especially in light of projections of accelerated sea level rise. 相似文献
74.
The public transport system of Karlsruhe, in particular its innovative services on jointly used heavy rail lines, has received substantial attention throughout the past 20 years. The discussion of the system and of its development has been rather limited in the past, mostly highlighting technical aspects. This paper provides an overview of the development, including the urban development, of the region and of the funding system. The ridership and financial development of the operator is documented in detail. Three case studies focus on the integration of the system development in the general political process of the region and demonstrate the limitations of the operator under its current ownership structures. 相似文献
75.
W. E. Scobie 《Maritime Policy and Management》2013,40(2):73-74
This paper describes a model which may be used in the evaluation of the relative effectiveness of policies used in the areas of ship chartering and the switching of combined carriers between the dry-cargo market and the tanker market. The policies for chartering and market switiching are expressed in the form of ‘desired proportions’ of the fleet operating in a particular charter-mode or a particular market. Graphical illustration of this form of expression of policies can be easily understood, so that alternative policies can be designed with relative case. The effectiveness of a particular from of policy under various freight market conditions can be determined from the model, the use of which is illustrated by its application to the deployment of the fleet of an hypothetical shipping company. It is assumed that the feedback connection between the company's actions and the market-place is negligible. 相似文献
76.
Neil W. Polhemus 《Transportation Research Part B: Methodological》1980,14(3):271-279
This article discusses the use of continuous autoregressive models to describe the behavior of traffic indices. From discretely sampled data, second-order differential equation models are constructed to represent dynamic traffic fluctuations as the response of a linear system to a stochastic forcing function. The results are compared to the more common M/G/∞ queueing model approach, and the analysis is demonstrated on time series of aircraft concentration in thirty-one enroute air traffic control sectors. 相似文献
77.
Ronald W. McQuaid 《Research in Transportation Economics》2009,25(1):19-28
This paper considers the length of time that parents are willing to travel to an existing or new job. Using data for over 12,000 parents it finds that many characteristics were associated with being less likely to be willing to travel to work for at least an hour (roundtrip). These include: being a women, those out of work, having children under 5, being a lone parent and using formal childcare. Professionals and associate professions were more willing to travel for longer periods. In terms of location, those in accessible small towns and rural areas were willing to travel more than those in larger urban areas and those in remote rural areas willing to travel most. Policy implications are also set out. 相似文献
78.
我叫大卫·泽洛斯特里克,是斯泰勒工业有限公司的董事长.斯泰勒工业有限公司是美国第一家拉臂钩制造商,成立于1990年,座落于美国爱荷华州的加纳区. 相似文献
79.
From a comparative study it is concluded that current design rules for the spherical pressure hull of manned submersible need to be updated and unified. In this paper, a series of spherical pressure hulls are calculated by nonlinear FEM. Based on these numerical results, the influence of critical arch length and the relationship of ultimate strength with t/R and structural imperfection are studied. Finally, empirical formulae for the ultimate strength of the titanium alloy spherical pressure hull of deep manned submersible based on numerical computations are given. The formulae can be used as the core equations to update current design rules. 相似文献
80.
Prediction of fatigue life and estimation of its reliability on the parts of an air suspension system 总被引:1,自引:0,他引:1
K. J. Jun T. W. Park S. H. Lee S. P. Jung J. W. Yoon 《International Journal of Automotive Technology》2008,9(6):741-747
Air suspension systems have been implemented in various commercial vehicles, such as buses and special purpose trucks, because
of the comfortable ride and easy height control. An evaluation of the durability of vehicle parts has been required for service
life and safety starting in the early stages of design. The cyclic load applied to the vehicle can cause fatigue failure of
parts, such as the suspension frame. This paper presents a method to predict the fatigue life of the suspension frame at the
design stage of the air suspension system used in a heavy-duty vehicle. To estimate the fatigue life using the SN method,
the Dynamic Stress Time History (DSTH) is necessary for the part of interest. DSTH can be obtained from the results of the
flexible body dynamic analysis using the Belgian road simulation and the Modal Stress Recovery (MSR) method. Furthermore,
the reliability of the predicted fatigue life can be evaluated by considering the variations in material properties. The probability
and distribution of the expected life cycle can be obtained using experimental design with a minimum number of simulations.
The advantage of using statistical methods to evaluate the life cycle is the ability to predict replacement time and the probability
of failure of mass-produced parts. This paper proposes a rapid and simple method that can be effectively applied to the design
of vehicle parts. 相似文献