共查询到20条相似文献,搜索用时 93 毫秒
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输气站场是天然气输送系统的重要组成部分,输送介质属于易燃易爆气体,管道系统结构复杂。通过对输气站场工艺系统分析和损伤模式识别,辨别出最可能存所在缺陷的管道位置,应用在线监测和检测技术,确定缺陷尺寸和扩展趋势,并预测含缺陷管道系统的使用寿命和最大承压能力,最终建立输气站场完整性检测评价体系。完整性检测评价系统为站场管道系统安全管理和预知性维修提供决策,对于保障输气站场的安全运行具有重要意义。 相似文献
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采用动态规划算法,利用SynerGEE Gas软件建立川气东送管道模型并进行优化分析,通过对比管道实际运行方案和动态规划算法优化方案,发现管道实际运行方案可优化空间较大,平均可减少电力能耗费用约3万元/d。同时验证了输气管道优化问题可以应用动态规划方法来解决。总结出管道优化运行的基本规律,对管道未来运行调度具有参考作用。 相似文献
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The private provision of public roads via the build-operate-transfer (BOT) mode has been increasingly used around the world. By viewing a BOT contract as a combination of road capacity, toll and government guarantee, this paper investigates optimal concession contract design under both symmetric and asymmetric information about the marginal maintenance cost of private investors. Under asymmetric information, the government guarantee serves as an instrument to induce a private investor to reveal his true cost information. Compared with the situation under symmetric information, the government will suffer a loss of social welfare; the private investor will charge a higher toll that increases in his reported marginal maintenance cost, and specify a lower capacity that decreases with the reported cost. The results also show that the private investor obtains extra information rent beyond the reservation level of return and the rent decreases with his reported cost. However, the resulting volume-capacity ratios of the BOT road under both information structures are the same. 相似文献
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Kofi Obeng 《Transportation》1988,15(4):297-316
This paper develops a conceptual framework for bus maintenance based on path analysis and applies it to forty-eight bus transit systems. The application determines the total, direct, and indirect effects of the variables identified as having significant causal links with maintenance cost per mile. These variables are identified using the stepwise regression method. The findings are that the wage rate and fleet size increase maintenance cost directly and indirectly. In terms of the standardized regression coefficients, fleet size has been found to be the most important factor affecting maintenance cost per mile, followed by the proportion of articulated buses, the wage rate and local subsidy in that order. The proportion of articulated buses has been found to reduce maintenance cost per mile directly and to increase it indirectly. The indirect path coefficient of the proportion of articulated buses is 0.1794 whereas the direct path coefficient is –0.351. Similarly local subsidy as a proportion of revenue increases maintenance cost per mile directly and reduces it indirectly. The corresponding path coefficients for the direct and indirect effects of local subsidy are 0.2553 and –0.1073. In addition population density and the peak-base ratio are positively and significantly associated with miles between roadcalls. The implications of these findings are briefly examined in this paper. Because the path analysis methodology allows the direct and indirect effects of a causal variable to be determined, it is recommended for policy analysis. 相似文献
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Road Pricing models with maintenance cost 总被引:2,自引:0,他引:2
According to the Federal Highway Administration of the United States, maintenance expenditure takes up more than 25% of road revenue disbursement and this percentage has been increasing gradually. The reason for the increment in maintenance cost is that there lacks incentives for road users to take this cost component into their driving behavior. That is, different classes of vehicles should be levied different levels of congestion tax due to the different degrees of damage on the highway if a road pricing policy is implemented. This paper intends to incorporate this concept into road pricing literature by introducing two types of vehicles. After the analysis of the problem, we find that different types of vehicles should be charged different tolls. The toll includes not only the travel delay cost of one's own vehicle and the other types of vehicles, but also the marginal maintenance cost that is dependent on the traffic flow. A set of numerical examples is provided to demonstrate the theoretical analyses. The result shows that both the welfare and cost coverage rate will increase when the road pricing mechanism takes the maintenance cost factor into account. 相似文献
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Traditionally, asphalt pavement maintenance mainly considers pavement performance and cost and largely ignores the environment while substantial amount of environmental burdens are released in the process. In this study, a multi-objective optimization model was developed integrating the three elements in order to optimize the asphalt pavement maintenance plans at the project level. Pavement performance element was decided as the multiplier of pavement serviceability index and traffic volume. Cost element was represented by the net present value, including components of agency cost, vehicle operation cost and salvage value. Environmental element, integrating energy consumption, global warming potential, acidification potential and respiratory effects potential, was measured by the life cycle assessment model. A hypothetic asphalt pavement maintenance case study was conducted using the developed multi-objective optimization model and harvested 103 sets of feasible combinations of maintenance plans, each of which is non-dominated by the others. Trade-offs analysis was performed among the three objectives and visualized in both two- and three-dimension forms. It is found there is an opportunity of reducing the cost and environmental impacts to 80.3% and 77.8% and increasing the pavement performance to 146.6% compared to the base case. However, they are mutually compromised and cannot be reached simultaneously. The developed model reveals the quantitatively interactive relationship of the three objectives and helps optimize the asphalt pavement maintenance plans. 相似文献
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《Transportation Research Part A: Policy and Practice》2003,37(1):29-48
The aircraft maintenance scheduling is one among the major decisions an airline has to make during its operation. Though maintenance scheduling comes as an end stage in an airline operation, it has potential for cost savings. Maintenance scheduling is an easily understood but difficult to solve problem. Given a flight schedule with aircraft assigned to it, the aircraft maintenance-scheduling problem is to determine which aircraft should fly which segment and when and where each aircraft should undergo different levels of maintenance check required by the Federal Aviation Administration. The objective is to minimize the maintenance cost and any costs incurred during the re-assignment of aircraft to the flight segments.This paper provides a complete formulation for maintenance scheduling and a heuristic approach to solve the problem. The heuristic procedure provides good solutions in reasonable computation time. This model can be used by mid-sized airline corporations to optimize their maintenance costs. 相似文献
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高速公路养护作业成本控制对策 总被引:1,自引:0,他引:1
文章分析了高速公路养护作业在时间、空间和资源的使用方面受到诸多限制,从而呈现出高成本的特性,提出了高速公路养护作业成本的控制对策. 相似文献
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本文基于安徽省高速公路路面历史性能数据,采用多元线性回归模型建立了预防性养护措施路面性能发展模型,评价了各预防性养护措施的适用性。针对实际情况采用"等效面积法"评价路面养护效益,考虑到预防性养护措施寿命较短,本文提出二次养护效益费用比的概念,对典型的预防性养护措施的实施效果进行了评价,并对影响养护效益的因素进行了分析。 相似文献
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Arian Khaleghi Moghadam John Livernois 《Transportation Research Part D: Transport and Environment》2010,15(5):285-297
Mandatory inspection and maintenance programs require on-road vehicles to be tested regularly and repaired if they are not in compliance with air emission regulations. We estimate the abatement cost function for a representative inspection and maintenance program. This is done by constructing a model of the statistical process that leads to non-compliance, parameterizing the model, and then by simulating the total abatement cost function. The model predicts that the marginal abatement cost for a major representative program is so high that even a small reduction in the abatement target leads to substantial cost savings to motorists. In addition, even for quite high levels of the abatement target, the optimal minimum testing age is substantially higher and the frequency of testing is much lower than is common in many jurisdictions. 相似文献
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A fleet of vessels and helicopters is needed to support maintenance operations at offshore wind farms. The cost of this fleet constitutes a major part of the total maintenance costs, hence keeping an optimal or near-optimal fleet is essential to reduce the cost of energy. In this paper we study the vessel fleet size and mix problem that arises for the maintenance operations at offshore wind farms, and propose a stochastic three-stage programming model. The stochastic model considers uncertainty in vessel spot rates, weather conditions, electricity prices and failures to the system. The model is tested on realistic-sized problem instances, and the results show that it is valuable to consider uncertainty and that the proposed model can be used to solve instances of a realistic size. 相似文献