For urban mass transit systems in the saturated passenger flow situation,the normal operation of trains might be disturbed by the unexpected disturbance.A large bunch of passengers might be stranded on platforms due t...
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For urban mass transit systems in the saturated passenger flow situation,the normal operation of trains might be disturbed by the unexpected disturbance.A large bunch of passengers might be stranded on platforms due to service gaps and the limited free capacity of *** this paper,we develop an automatic train regulation model which integrates two different regulation strategies and considers the pre-set automatic train operation(ATO) recommended speed *** specifically,a mixed integer programming(MIP) model is proposed which aims to jointly reduce the total train delay and the number of stranded *** consider a train holding strategy to futher balance the interval of two consecutive trains which can reduce the number of stranded passengers on the ***,a state-of-the-art mathematical solver CPLEX is adopted to solve the problem,which can obtain trade-off solutions in a reasonable ***,two experiments based on the operational data of the Beijing Subway Yizhuang Line are carried out to verify the effectiveness of the proposed approach.
Outsourcing is the contracting of various information systems' sub-functions by user firms to outside information systems vendors. A critical factor in the outsourcing process is the bidding and vendor selection m...
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Outsourcing is the contracting of various information systems' sub-functions by user firms to outside information systems vendors. A critical factor in the outsourcing process is the bidding and vendor selection mechanism. This paper describes the process of outsourcing and identifies the various stages involved. Subsequently, considering that cost reduction is a driving force of outsourcing for user-firms, this paper proposes a bidding mechanism to reduce expected outsourcing costs in the final bidding and vendor selection process. The paper studies outsourcing contracts of routine and repetitive activities such as maintenance and operation of telecommunication networks. A realistic scenario is studied, wherein multiple vendors bid for such contracts and where one vendor has cost and expertise advantages over other vendors and as a result tends to inflate bids. A mixed integer programming model is formulated for a multiple vendor scenario. In general, the results suggest a prescription that calls for the use of "carrot and stick" policies by the user firm. Subsidies (the carrot) need to be used as incentives for bidders to announce their most competitive bids. In addition, penalties (the stick) have to be levied in order to pressure bidders not to bid high.
Among generic technology management activities, rapid technology identification and selection stand as the significant determinants of technology adoption success in the digital transformation era. Especially for manu...
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Among generic technology management activities, rapid technology identification and selection stand as the significant determinants of technology adoption success in the digital transformation era. Especially for manufacturing SMEs in developing countries, rapid digital technologies are critical since they struggle to protect their competitiveness in global value chains threatened by digitalization. Previous studies introduce various multi-criteria decision-making model-based approaches to identify and select appropriate manufacturing technologies. However, these approaches were relatively rigid and required an advanced understanding of the technology for criteria and alternative settings and evaluation. Decision-makers need more flexible and scalable contextual frameworks for technology selection in digitalization. Since digital technologies offer both benefits and challenges, the decision-making models should reflect this dialectic nature of Industry 4.0 adoption and contextually optimize their decisions by combining multiple quantitative methods for technology identification and selection. Besides, case studies on digital technology selection are rare in manufacturing SMEs from developing country context in the literature. In this context, this study proposes a technology selection framework that utilizes the three dimensions (industry 4.0 technologies, benefits, and challenges) and combines AHP with a QFD-inspired intervention matrix and an optimization model by mixed integer programming (MIP). The proposed model is validated with a case study from the automotive supplier industry in Turkey with the data provided from interviews and a Delphi survey with 11 experts from the digitalization value chain of the selected industry. Case study results revealed that the highest benefits of industry 4.0 lie in process/quality efficiency improvement and reduced inventory. At the same time, data analytics and sensor technologies occurred as the most critical tools. Signific
ABSTRACT: Individuals involved in state water resource planning generally have avoided any development of a comprehensive public water planning investment model that would set the stage for quantitative recommendation...
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This paper describes the experience gained from a research collaboration between a group of researchers at the National University of Singapore and logistics executives in Sembcorp Logistics (formerly ST Logistics), i...
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This paper describes the experience gained from a research collaboration between a group of researchers at the National University of Singapore and logistics executives in Sembcorp Logistics (formerly ST Logistics), in the latter's effort to develop a marketing and strategic planning software tool to enhance its third party logistics (3PL) services in China. As China opened up its economy in the late 1980s, many Western consumer goods manufacturers set up plants or formed joint ventures in China in an attempt to capture this huge market. While the production process can be easily built on the existing technologies and can be efficient costwise, the distribution process is still a challenge because of the backward nature of the infrastructure and the bureaucratic roadblocks, resulting in very high supply chain transaction costs. Consequently, most manufacturers turn to third-party logistics providers (3PLs) who have the required logistics expertise to operate in China. One of the leading 3PLs in China is Shenzhen ST-Anda Logistics (ST-Anda), a joint venture between Sembcorp Logistics and China Merchant Holdings. It has an existing pan-China network of distribution centers. Recently, to improve services to their customers, ST-Anda started planning for the expansion of their logistics distribution network. An OR/MS modeling approach was taken to help them in this venture. International Federation of Operational Research Societies 2001.
This paper addresses the airplane passengers' seat assignment problem while practicing social distancing among passengers. We proposed a mixed integer programming model to assign passengers to seats on an airplane...
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This paper addresses the airplane passengers' seat assignment problem while practicing social distancing among passengers. We proposed a mixed integer programming model to assign passengers to seats on an airplane in a manner that will respect two types of social distancing. One type of social distancing refers to passengers being seated far enough away from each other. The metric for this type of social distancing is how many passengers are seated so close to each other as to increase the risk of infection. The other type of social distancing refers to the distance between seat assignments and the aisle. That distance influences the health risk involved in passengers and crew members walking down the aisle. Corresponding metrics for both health risks are included in the objective function. To conduct simulation experiments, we define different scenarios distinguishing between the relative level of significance of each type of social distancing. The results suggest the seating assignments that best serve the intention of the scenarios. We also reformulate the initial model to determine seat assignments that maximize the number of passengers boarding an airplane while practicing social distancing among passengers. In the last part of this study, we compare the proposed scenarios with the recommended middle-seat blocking policy presently used by some airlines to keep social distancing among passengers. The results show that the proposed scenarios can provide social distancing among seated passengers similar to the middle-seat blocking policy, while reducing the number of passengers seated close to the aisle of an airplane.
A balancing problem for paced tandem transfer lines with several spindle heads at each station is considered. A spindle head executes a block of operations. The set of all available spindle heads as well as the operat...
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Hospitals are paramount hubs for delivering healthcare services, with their Operating Rooms (ORs) as a pivotal and financially substantial component. Efficient surgery ward planning is crucial in healthcare institutio...
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A reduced turnaround time to obtain initial test results for detecting the bacterial agent that causes tuberculosis (TB) can significantly improve the management of this communicable disease. We propose a new facility...
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An inventory routing problem occurs when a company manages inventories both at production sites and consumption sites while also being in charge of the transportation of goods. We consider a maritime inventory routing...
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An inventory routing problem occurs when a company manages inventories both at production sites and consumption sites while also being in charge of the transportation of goods. We consider a maritime inventory routing problem where inventories are located at ports and a single product is transported between these ports using a heterogeneous fleet of vessels. As opposed to standard research on such maritime inventory routing problems, a model is developed that produces cyclic plans that are repeatable. Such plans are more costly than plans found using standard non-cyclic models, but the latter suffer from end-of-horizon effects due to being over-optimistic and making myopic decisions in accordance with an objective of minimizing costs.
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