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Safety is one of the most critical themes in any large-scale railway construction project. Recognizing the importance of safety in railway engineering, practitioners and researchers have proposed various standards and procedures to ensure safety in construction activities. In this study, we first review four critical research areas of risk warning technologies and emergency response mechanisms in railway construction, namely, (i) risk identification methods of large-scale railway construction projects, (ii) risk management of large-scale railway construction, (iii) emergency response planning and management, and (iv) emergency response and rescue mechanisms. After reviewing the existing studies, we present four corresponding research areas and recommendations on the Sichuan–Tibet Railway construction. This study aims to inject new significant theoretical elements into the decision-making process and construction of this railway project in China. 相似文献
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Train speed profile optimization is an efficient approach to reducing energy consumption in urban rail transit systems. Different from most existing studies that assume deterministic parameters as model inputs, this paper proposes a robust energy-efficient train speed profile optimization approach by considering the uncertainty of train modeling parameters. Specifically, we first construct a scenario-based position–time–speed (PTS) network by considering resistance parameters as discrete scenario-based random variables. Then, a percentile reliability model is proposed to generate a robust train speed profile, by which the scenario-based energy consumption is less than the model objective value at
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We consider the problem of rescheduling trains in the case where one track of a railway section consisting of two tracks in opposing directions is closed due to construction activities. After presenting an appropriate model for this situation we derive a polynomial algorithm for the subproblem of finding an optimal schedule with minimal latenesss if the subsequences of trains for both directions outside the construction site are fixed. Based on this algorithm we propose a local search procedure for the general problem of finding good schedules and report test results for some real world instances. Received: December 8, 1999 / Accepted: May 2, 2001 相似文献
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A mathematical model is formulated for the operational reliability of intelligent transducers used at the Astrakhan Gas Reprocessing Plant. The parameters are obtained of the theoretical distribution law for the duration of failure-free operation of the transducers, their reliability function, and their failure intensity. 相似文献
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Modern and intelligent manufacturing systems have a prominent multistate feature. However, previous studies of reliability analysis of multistate manufacturing systems mostly focused on the basic reliability of manufacturing systems but disregarded their operating characteristics, which has hindered the development of Prognostics and Health Management technique for intelligent manufacturing systems. Therefore, an evaluation approach of mission reliability for multistate manufacturing systems based on operational quality data is proposed in this paper. First, from the systematic viewpoint of the composition and operational principle of the manufacturing system, the relationship among production task execution state, production equipment degradation state, and produced product quality state is expounded, and the connotation of the mission reliability of multistate manufacturing systems is defined. Second, an extended state task network (ESTN) is presented to organise operational quality data by considering the quality state of work in process (WIP). Third, a fusion model of operational quality data for manufacturing systems is established with the aid of the ESTN, and an operational quality data-oriented evaluation method of mission reliability is been put forward. Finally, a case study of a manufacturing system for a cylinder head is conducted to verify the proposed approach. 相似文献
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Condition-based maintenance (CBM) detects early signs of failure and dictates when maintenance should be performed based on the actual condition of a system. In this paper, we first review some of the recent research on CBM under various physical structures and signal data. Then, we summarize several kinds of prognostic models that use monitoring information to estimate the reliability of complex systems or products. Monitoring information also facilitates operational decisions in production planning, spare parts management, reliability improvement, and prognostics and health management. Finally, we suggest some research opportunities for the reliability and operations management communities to fill the research gap between these two fields. 相似文献
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The purpose of this paper is to delineate the research challenges of human–machine collaboration in risky decision-making. Technological advances in machine intelligence have enabled a growing number of applications in human–machine collaborative decision-making. Therefore, it is desirable to achieve superior performance by fully leveraging human and machine capabilities. In risky decision-making, a human decision-maker is vulnerable to cognitive biases when judging the possible outcomes of a risky event, whereas a machine decision-maker cannot handle new and dynamic contexts with incomplete information well. We first summarize features of risky decision-making and possible biases of human decision-makers therein. Then, we argue the necessity and urgency of advancing human–machine collaboration in risky decision-making. Afterward, we review the literature on human–machine collaboration in a general decision context, from the perspectives of human–machine organization, relationship, and collaboration. Lastly, we propose challenges of enhancing human–machine communication and teamwork in risky decision-making, followed by future research avenues. 相似文献
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Josef Kallrath 《OR Spectrum》2002,24(3):315-341
We describe and solve a real world problem in chemical industry which combines operational planning with strategic aspects.
In our simultaneous strategic & operational planning (SSDOP) approach we develop a model based on mixed-integer linear (MILP)
optimization and apply it to a real-world problem; the approach seems to be applicable in many other situations provided that
people in production planning, process development, strategic and financial planning departments cooperate.
The problem is related to the supply chain management of a multi-site production network in which production units are subject
to purchase, opening or shut-down decisions leading to an MILP model based on a time-indexed formulation. Besides the framework
of the SSDOP approach and consistent net present value calculations, this model includes two additional special and original
features: a detailed nonlinear price structure for the raw material purchase model, and a detailed discussion of transport
times with respect to the time discretization scheme involving a probability concept. In a maximizing net profit scenario
the client reports cost saving of several millions US$.
The strategic feature present in the model is analyzed in a consistent framework based on the operational planning model,
and vice versa. The demand driven operational planning part links consistently to and influences the strategic. Since the
results (strategic desicions or designs) have consequences for many years, and depend on demand forecast, raw material availability,
and expected costs or sales prices, resp., a careful sensitivity analysis is necessary showing how stable the decisions might
be wit h respect to these input data. 相似文献
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铁路改革是一个长期的过程,体制创新,技术创新、管理创新是改革的动力。本文着重铁路基础性改革与运输自动化的内需求研究。首先分析了铁路基础性改革的必然性和过程;其次从牵引动力,信息化等方面,分析了铁路运输自动化的发展过程;最后分析了铁路基础性改革与铁路运输自动化的相互关系。 相似文献
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龙雄燕 《制冷与空调(北京)》2004,4(6):89-91
在现代社会居住环境里,皆需考虑引入外界新鲜空气,同时排除部份室内空气.为了回收能量,空气处理设备装备了能量回收装置,能量回收型式的选择和机组的合理设计直接影响了回收效果. 相似文献
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Maintenance management has a direct influence on equipment reliability and safety. However, a large portion of traditional maintenance models and reliability analysis methods usually assumes that only perfect maintenance is performed on the system and the system will restore to as good as new regardless of the kind of preventive maintenance work‐order that is performed. This is not practical in reality and may result in an inaccurate parametric estimation. The research objective of this paper is to develop a maximum likelihood estimation method to obtain more accurately estimated parameters based on the operational data of manufacturing systems, taking into consideration the difference between perfect and imperfect maintenance work‐orders. Weibull distribution is specifically studied for this purpose. A practical case study based on industrial operational data from an automotive assembly line is performed to illustrate the implementation and efficiency of the proposed reliability estimation method. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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现阶段新能源汽车加速发展,充电设施也大规模建设,非车载充电机由于核心技术、关键器件的发展水平限制,生产企业技术设计、过程质控、成本因素等方面选择差异,存在轻载运行时效率低、损耗高的不足;随着非车载大功率充电方式的普及,非车载充电方式供电量将大幅攀升,其运行效率越来越受到关注。但目前在实际检测、验收、使用过程中,针对充电机运行效率的测试研究较少,不利于对充电机运行效率实施管控、促进电能利用效率提升。该文针对充电机运行效率开展测试验证研究,介绍NB/T 33001—2018技术标准对效率指标的要求,提出充电机运行效率测试技术方案,对典型充电机不同运行模式下的运行效率进行测试评估和验证,以期为充电机运行效率的有效管控、充电机运行效率的优化改进提供参考。 相似文献
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This study proposes an innovative flow management system that includes product (product and logistics) and process (human, information and decision) flow management. We identify three levels of ISO 9000 implementation (basic, advanced and supportive) as enablers, and operational performance as the outcome. The model was tested using the data-set collected from 133 ISO 9001 certified manufacturing companies in Australia. The results show that advanced implementation is positively related to both product and process flow management; supportive implementation is only positively related to process flow management while basic implementation has no significant effect on either product or process flow management. The results also show that both product and process flow management are positively related to operational performance. This study provides managerial guidelines for companies that wish to improve their innovation capabilities through ISO 9000 implementation and flow management. It also contributes to the ISO 9000 and flow management literature. 相似文献
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Governments at all levels are increasingly motivating the private sector to participate in infrastructure development using alternative project delivery methods to relieve financial burden. When designing contracts, governments usually offer incentives while requiring cost or time guarantee to balance project attractiveness to the private sector and fair protection of public interest. However, a practical and critical problem is how to properly design these provisions. Although previous studies have investigated the value of these provisions, a knowledge gap still exists with respect to methods of fairly and effectively designing such provisions. This study fills this gap by developing a methodology that analyzes the appropriateness of guarantee or warranty provisions for contracts. In this study, a contract reliability index is constructed, and a process of evaluating contract reliability is proposed. The New Mexico Highway 44 project, in which three warranty provision arrangements are investigated, is used as a case study to illustrate the analysis process. Results show that although a ceiling clause can effectively motivate the private sector to participate in the project, it sacrifices a significant amount of public benefits. By contrast, although a warranty option can protect public benefits, it cannot effectively incentivize the private sector. A combination of the ceiling clause and the warranty option will therefore result in improved contract provision design. The proposed methodology in this study is especially useful for governments in properly determining contract clauses in infrastructure development. 相似文献
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China is an early user of geothermal energy, and its direct use ranks first in the world. Recent national strategies and policies have enabled China’s geothermal energy industry to enter a new era with important development opportunities. This paper investigates the strengths, weaknesses, opportunities, and threats (SWOT) to China’s geothermal energy industry from political, economic, social, and technological (PEST) perspectives. SWOT–PEST analysis indicates that the resources, market, and technological foundation exist for the large-scale development of China’s geothermal energy industry. However, it experiences constraints, such as unclear resource distributions, incomplete development of government regulations, incomplete implementation of national policies, unclear authority between governmental administrative systems, and lack of uniform technical standards and codes. Therefore, future development strategies have been proposed to provide technical support and policy tools for geothermal energy development. The recommendations to ensure its healthy and sustainable development include improving resource exploration, rationalizing administration systems, enhancing policy guidance and financial support, and cultivating geothermal talent. 相似文献
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Cyber–physical systems (CPS) are intended to facilitate the tight coupling of the cyber and physical worlds. Their potential for enhancing the delivery and management of constructed facilities is now becoming understood. In these systems, it is vital to ensure bi-directional consistency between construction components and their digital replicas. This paper introduces the key features of CPS and describes why they are ideally suited for addressing a number of problems in the delivery of construction projects. It draws on examples of research prototypes developed using surveys, field experiments, and prototyping methodologies, to outline the key features and benefits of CPS for construction applications and the approach to their development. In addition, it outlines the lessons learned from developing various systems for the design, construction and management of constructed facilities, which include building component placement and tracking, temporary structures monitoring, and mobile crane safety. The paper concludes that the construction industry stands to reap numerous benefits from the adoption of CPS. It states that the future direction of CPS in construction will be driven by technological developments and the extent to which CPS is deployed in new application areas. 相似文献
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Hongwei Zhu Yuhang Liu Felix T. Eickemeyer Linfeng Pan Dan Ren Marco A. Ruiz-Preciado Brian Carlsen Bowen Yang Xiaofei Dong Zaiwei Wang Hongli Liu Shirong Wang Shaik M. Zakeeruddin Anders Hagfeldt M. Ibrahim Dar Xianggao Li Michael Grätzel 《Advanced materials (Deerfield Beach, Fla.)》2020,32(12):1907757
Passivation of interfacial defects serves as an effective means to realize highly efficient and stable perovskite solar cells (PSCs). However, most molecular modulators currently used to mitigate such defects form poorly conductive aggregates at the perovskite interface with the charge collection layer, impeding the extraction of photogenerated charge carriers. Here, a judiciously engineered passivator, 4-tert-butyl-benzylammonium iodide (tBBAI), is introduced, whose bulky tert-butyl groups prevent the unwanted aggregation by steric repulsion. It is found that simple surface treatment with tBBAI significantly accelerates the charge extraction from the perovskite into the spiro-OMeTAD hole-transporter, while retarding the nonradiative charge carrier recombination. This boosts the power conversion efficiency (PCE) of the PSC from ≈20% to 23.5% reducing the hysteresis to barely detectable levels. Importantly, the tBBAI treatment raises the fill factor from 0.75 to the very high value of 0.82, which concurs with a decrease in the ideality factor from 1.72 to 1.34, confirming the suppression of radiation-less carrier recombination. The tert-butyl group also provides a hydrophobic umbrella protecting the perovskite film from attack by ambient moisture. As a result, the PSCs show excellent operational stability retaining over 95% of their initial PCE after 500 h full-sun illumination under maximum-power-point tracking under continuous simulated solar irradiation. 相似文献
20.
Shizhen BAI Xinrui BI Chunjia HAN Qijun ZHOU Wen-Long SHANG Mu YANG Lin WANG Petros IEROMONACHOU Hao HE 《工程管理前沿(英文版)》2022,9(3):473
Promoting the growth of the lithium battery sector has been a critical aspect of China’s energy policy in terms of achieving carbon neutrality. However, despite significant support on research and development (R&D) investments that have resulted in increasing size, the sector seems to be falling behind in technological areas. To guide future policies and understand proper ways of promoting R&D efficiency, we looked into the lithium battery industry of China. Specifically, data envelopment analysis (DEA) was used as the primary approach based on evidence from 22 listed lithium battery enterprises. The performance of the five leading players was compared with that of the industry as a whole. Results revealed little indication of a meaningful improvement in R&D efficiency throughout our sample from 2010 to 2019. However, during this period, a significant increase in R&D expenditure was witnessed. This finding was supported, as the results showed that the average technical efficiency of the 22 enterprises was 0.442, whereas the average pure technical efficiency was at 0.503, thus suggesting that they were suffering from decreasing returns to scale (DRS). In contrast, the performance of the five leading players seemed superior because their average efficiency scores were higher than the industry’s average. Moreover, they were experiencing increasing scale efficiency (IRS). We draw on these findings to suggest to policymakers that supporting technologically intensive sectors should be more than simply increasing investment scale; rather, it should also encompass assisting businesses in developing efficient managerial processes for R&D. 相似文献