BOHR International Journal of Operations Management Research and Practices

Application of tabu search, TS, to solve a flow shop scheduling problem with changeover times in operations: A case study

Phong Nguyen Nhu, Thuy Nhi Nguyen Thi — Fri, 05 Jan 2024 00:00:00 +0000

Flow Shop Scheduling (FSS) Problems are NP-hard combinatorial optimization problems. It is quite difficult to achieve an optimal solution for FSS problems with mathematical modelling approaches because of its NP-hard structure. Tabu search (TS), a mega-heuristic algorithm, plays a major role in searching for near-optimal solutions for NP-hard optimization problems. This paper develops a TS model for solving a FSS problem with the objective to reduce total weighted tardiness time, and constraint on changeover time in operations. The performance of the TS model is compared with that of traditional EDD heuristics, being used. The result shows that the objective value has been reduced by 43%, from 215.95 to 123.07 (h). It indicates that the TS model is a good approach for FSS problems.

Application of genetic algorithm, GA, to solve a flow shop scheduling problem with changeover times in operations: a case study

Phong Nguyen Nhu, Kim Ngan Nguyen Thi , Thanh Huyen Tran Vo Thi — Fri, 01 Mar 2024 00:00:00 +0000

Flow Shop Scheduling (FSS) Problems are examples of combinatorial optimization issues that are classified as NP-hard. Because of the NP-hard structure of FSS problems, it can be extremely challenging to find mathematical modeling methodologies that will result in an optimal solution for these problems. The Genetic Algorithm (GA), which is a metaheuristic approach, is one of the most important factors in the process of locating near-optimal answers to NP-hard optimization issues. In this research, a GA model for addressing an FSS problem was developed with the goal of lowering the overall weighted tardiness time and placing a constraint on the operation changeover time. When compared with the performance of the standard heuristics EDD, being used in the company under study, the GA model’s performance was shown to be superior. Based on the findings, it can be shown that the objective value was cut by 43%, going from 215.95 (h) to 123.07 (h). This demonstrates that the GA model is an effective strategy for addressing FSS problems.

A bimodal supply chain game model for apparel enterprises considering consumer channel preferences

Zhoulei Pan, Hao Wan, Yihao Yin — Wed, 03 Apr 2024 00:00:00 +0000

Considering the consumer’s channel preference, this paper studies the pricing strategies of clothing manufacturers and retailers mainly selling online on traditional e-commerce platforms and live e-commerce platforms, and constructs two sales modes: direct selling mode and resale mode. Based on the Stackelberg game model, the optimal pricing and profit of direct selling mode and resale mode under centralized decision-making are solved, and the variables such as imported discount, consumer trust, and demand satisfaction are analyzed in detail. The results show that a large discount can’t guarantee the maximization of platform profits and a suitable discount can effectively improve the profits of retailers and manufacturers. Traditional platform retailers effectively improve consumers’ trust in goods, which is conducive to improving their own and manufacturers’ profits; When the cost paid by consumers when purchasing goods from different channels is different, the change of consumers’ shopping cost will directly affect the pricing of goods by the two platforms.

Applying fuzzy theory to develop linguistic control charts The pLCC model

Phong Nguyen Nhu, Tu Anh Nguyen Nhu — Fri, 12 Jan 2024 00:00:00 +0000

This paper studies an approach to use fuzzy set theory and possibility theory to construct control charts – a very important on-line process control tool used in quality control. The control chart is constructed based on linguistic data. The model aims to control the process simply and effectively. The quality characteristics are modeled by fuzzy variable. The status of quality characteristics is modeled by triangle fuzzy number. Fuzzy arithmetic is used to calculate the control chart’s center line. The control chart’s control limits are constructed according to Shewhart’s principle. The fuzzy variable’s standard deviation is calculated by a model developed by Kauffman and Gupta.

Further discussion on regulations of the logistic services in Vietnam–and construction issues for logistics in Ca Mau province

Fri, 01 Mar 2024 00:00:00 +0000

Purpose: This research paper aims to present discussion on regulations of the logistic services in Vietnam and a case study of logistics in Ca Mau province. By using the panel approach, our findings: As the role of logistics has been increasingly important and China is a big export partner of our country, in Ca Mau, according to the approved plan, Nam Can Seaport is a local general port (type II), including Nam Can ports on Cai Lon river for ships up to 5,000 tons and the study "Development of seaports for ships of up to 5,000 tons". large load capacity in the Hon Khoai island area in accordance with the needs and capacity of investors.

Testing the applicability of the low-cost carrier model in East African aviation market: A gravity demand model analysis

Samunderu Eyden, Posada Kandel — Mon, 05 Aug 2024 00:00:00 +0000

Although there exists extensive literature on the demand patterns and long-term sustainability of low-cost carriers from numerous perspectives and in different markets, no research has examined its applicability to the East African aviation context. Therefore, this study aims to fill this gap by examining whether the European low-cost model can be sustainable against the backdrop of the challenges and complexities of the East African aviation environment. This article draws its theoretical literature assessment from the pillar of European low-cost carriers and gives a scope of the underlining strategic implications of operating a low-cost carrier model. Against such a backdrop, the African aviation market’s operational complexities, challenges and opportunities, and demand patterns are presented in order to draw a conclusive evidence on whether a low-cost carrier in its current existence can be adopted in the East African market. Hypothetically, sufficient demand levels generally present the main barrier to operating an airline because, without revenue-paying passengers, operating costs cannot be covered. Subsequently, natural and latent demand levels on sample routes between the studied countries’ major cities are forecasted using gravity modeling in order to determine whether current and future demand levels are sufficient to justify direct point-to-point flights between city-pairs on an aircraft at a typical European low-cost seating density. The findings suggest that latent demand could be stimulated on most routes by reducing ticket costs, thus justifying direct point-to-point services between the studied city-pairs on a typical European low-cost configured aircraft. Some routes, however, showed resilience to demand stimulation through airfare reduction. The study also includes a survey analysis of the general travel behavior of coach passengers in the East African market in order to understand their likelihood of switching from road transportation to air transportation. The findings underpinned the results found in the theoretical demand modeling.