Inverse data envelopment analysis (DEA) determines the optimal level of inputs and/or outputs of decision-making units (DMUs) to reach efficiency targets. This paper presents a new inverse DEA model for determining minimum inputs for working capital management. The proposed model is employed in the Indian textile industry to calculate working capital efficiency. Given the working capital efficiency, the decision maker’s preferences will be estimating the change in inputs when outputs increase. Furthermore, unlike the standard inverse DEA model, this article discusses the inverse DEA model when negative ratio data exists. The DEA model requires additional attention when ratio data are present; therefore, a novel inverse DEA ratio model is proposed. The input targets obtained from the proposed model are less than the standard inverse DEA model. Also, the proposed model is a closer estimate of the production probability set for ratio data.
{"title":"An inverse Data Envelopment Analysis model to consider ratio data and preferences of decision-makers","authors":"D. Mahla, S. Agarwal, G. R. Amin, T. Mathur","doi":"10.1093/imaman/dpac009","DOIUrl":"https://doi.org/10.1093/imaman/dpac009","url":null,"abstract":"\u0000 Inverse data envelopment analysis (DEA) determines the optimal level of inputs and/or outputs of decision-making units (DMUs) to reach efficiency targets. This paper presents a new inverse DEA model for determining minimum inputs for working capital management. The proposed model is employed in the Indian textile industry to calculate working capital efficiency. Given the working capital efficiency, the decision maker’s preferences will be estimating the change in inputs when outputs increase. Furthermore, unlike the standard inverse DEA model, this article discusses the inverse DEA model when negative ratio data exists. The DEA model requires additional attention when ratio data are present; therefore, a novel inverse DEA ratio model is proposed. The input targets obtained from the proposed model are less than the standard inverse DEA model. Also, the proposed model is a closer estimate of the production probability set for ratio data.","PeriodicalId":56296,"journal":{"name":"IMA Journal of Management Mathematics","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42289881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. R. Bazargan-Lari, S. Taghipour, A. Zaretalab, M. Sharifi
This paper aims to quantify the effects of production disruptions and physical distancing constraints due to the pandemic in a parallel-machine production environment. The machines are non-identical and are utilized for producing a finite set of jobs (parts) in a plastic injection molding production. The production process is subject to random production downtime disruptions. A mixed-integer linear programming (MILP) model is developed for optimizing the joint production plan and schedule, which maximizes the production’s total benefit. The model is utilized to plan and schedule a set of 17 machines in a Canadian manufacturing company. To explore the effects of physical distancing and production disruptions on the production’s total net profit, four different scenarios for normal operation and production during the pandemic, with and without production downtimes, are considered. A genetic algorithm is utilized to solve the model. The results show that considering machines’ random breakdowns and physical distancing individually reduces the total profit of the production by 71.58% and 57.98%, respectively; while their joint effect results in a 88.54% reduction in the annual net profit.
{"title":"Planning and scheduling of a parallel-machine production system subject to disruptions and physical distancing","authors":"M. R. Bazargan-Lari, S. Taghipour, A. Zaretalab, M. Sharifi","doi":"10.1093/imaman/dpac010","DOIUrl":"https://doi.org/10.1093/imaman/dpac010","url":null,"abstract":"\u0000 This paper aims to quantify the effects of production disruptions and physical distancing constraints due to the pandemic in a parallel-machine production environment. The machines are non-identical and are utilized for producing a finite set of jobs (parts) in a plastic injection molding production. The production process is subject to random production downtime disruptions. A mixed-integer linear programming (MILP) model is developed for optimizing the joint production plan and schedule, which maximizes the production’s total benefit. The model is utilized to plan and schedule a set of 17 machines in a Canadian manufacturing company. To explore the effects of physical distancing and production disruptions on the production’s total net profit, four different scenarios for normal operation and production during the pandemic, with and without production downtimes, are considered. A genetic algorithm is utilized to solve the model. The results show that considering machines’ random breakdowns and physical distancing individually reduces the total profit of the production by 71.58% and 57.98%, respectively; while their joint effect results in a 88.54% reduction in the annual net profit.","PeriodicalId":56296,"journal":{"name":"IMA Journal of Management Mathematics","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41500310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The congestion of public hospitals for elective treatment in some countries and regions, such as Canada and Hong Kong where the free health policy is implemented, is a serious issue. The main reason is the excessive demand generated by the provision of free service. In response, the government can set appropriate service price and budget for public hospitals to moderate such demand. This is often referred to as the charging policy, implemented in countries such as China. A Stackelberg game is established for a health system consisting of a government, a public health provider and delay sensitive patients. The results show that when the customers' waiting cost is low (e.g., the market demand, the patients delay sensitivity, or the unit capacity cost is low), the free health policy outperforms the charging policy; otherwise, the charging policy is better. Moreover, we find that the equilibrium waiting time and the equilibrium price decrease with the market demand when the funder attaches more importance to patients’ welfare than the budget surplus and the total budget is sufficient.
{"title":"Optimal pricing and budget decisions in public health systems with delay sensitive patients","authors":"Senlong Huang, DongBin Hu, Wuhua Chen","doi":"10.1093/imaman/dpac008","DOIUrl":"https://doi.org/10.1093/imaman/dpac008","url":null,"abstract":"\u0000 The congestion of public hospitals for elective treatment in some countries and regions, such as Canada and Hong Kong where the free health policy is implemented, is a serious issue. The main reason is the excessive demand generated by the provision of free service. In response, the government can set appropriate service price and budget for public hospitals to moderate such demand. This is often referred to as the charging policy, implemented in countries such as China. A Stackelberg game is established for a health system consisting of a government, a public health provider and delay sensitive patients. The results show that when the customers' waiting cost is low (e.g., the market demand, the patients delay sensitivity, or the unit capacity cost is low), the free health policy outperforms the charging policy; otherwise, the charging policy is better. Moreover, we find that the equilibrium waiting time and the equilibrium price decrease with the market demand when the funder attaches more importance to patients’ welfare than the budget surplus and the total budget is sufficient.","PeriodicalId":56296,"journal":{"name":"IMA Journal of Management Mathematics","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41650171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aspiring green agendas in conjunction with tremendous economic pressures are resulting in an increased attention to the environment and technological innovations for improving existing logistics systems. Last mile logistics, in particular, are becoming much more than a consumer convenience necessity and a transportation optimization exercise. Rather, this area presents a true opportunity to foster both financial and environmental sustainability. This paper investigates recent technological advancements and pending needs related to business and social innovations, emphasizing green logistics and city logistics concepts. We discuss various pertinent aspects, including drones, delivery robots, truck platooning, collection and pickup points, collaborative logistics, integrated transportation, decarbonization and advanced transport analytics. From a mathematical perspective, we focus on the basic features of the vehicle routing problem and some of its variants. We provide recommendations around strategies that may facilitate the adoption of new effective technologies and innovations.
{"title":"Last mile logistics: Research trends and needs","authors":"E. Demir, A. Syntetos, T. van Woensel","doi":"10.1093/imaman/dpac006","DOIUrl":"https://doi.org/10.1093/imaman/dpac006","url":null,"abstract":"\u0000 Aspiring green agendas in conjunction with tremendous economic pressures are resulting in an increased attention to the environment and technological innovations for improving existing logistics systems. Last mile logistics, in particular, are becoming much more than a consumer convenience necessity and a transportation optimization exercise. Rather, this area presents a true opportunity to foster both financial and environmental sustainability. This paper investigates recent technological advancements and pending needs related to business and social innovations, emphasizing green logistics and city logistics concepts. We discuss various pertinent aspects, including drones, delivery robots, truck platooning, collection and pickup points, collaborative logistics, integrated transportation, decarbonization and advanced transport analytics. From a mathematical perspective, we focus on the basic features of the vehicle routing problem and some of its variants. We provide recommendations around strategies that may facilitate the adoption of new effective technologies and innovations.","PeriodicalId":56296,"journal":{"name":"IMA Journal of Management Mathematics","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41800037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Assembly line balancing by workload smoothing is very common; it aims to appropriately assign tasks to the stations of an assembly line, to ensure as similar as possible workloads for the stations. A shortcoming of the mathematical models developed in the literature is the optimization of workload smoothing when only all potential stations are considered. Therefore, the obtained solution may not be the global optimal solution and also may not be effective for real world cases. To overcome this shortcoming, some new workload smoothing criteria and their related mixed integer linear mathematical models are developed for three different settings: (1) workload smoothing optimization, when all potential stations are considered, (2) workload smoothing and minimization of the number of stations are optimized simultaneously, (3) global workload smoothing optimization regardless of the number of considered stations. The proposed formulations are associated with fewer variables and constraints compared with models previously presented in the literature and lead to better results according to an extensive numerical study. The proposed models can be applied in practice for designing the assembly lines of, inter alia, automobile and electronic equipment production systems.
{"title":"Straight assembly line balancing by workload smoothing: new results","authors":"Sadegh Niroomand;Bela Vizvari","doi":"10.1093/imaman/dpac005","DOIUrl":"https://doi.org/10.1093/imaman/dpac005","url":null,"abstract":"Assembly line balancing by workload smoothing is very common; it aims to appropriately assign tasks to the stations of an assembly line, to ensure as similar as possible workloads for the stations. A shortcoming of the mathematical models developed in the literature is the optimization of workload smoothing when only all potential stations are considered. Therefore, the obtained solution may not be the global optimal solution and also may not be effective for real world cases. To overcome this shortcoming, some new workload smoothing criteria and their related mixed integer linear mathematical models are developed for three different settings: (1) workload smoothing optimization, when all potential stations are considered, (2) workload smoothing and minimization of the number of stations are optimized simultaneously, (3) global workload smoothing optimization regardless of the number of considered stations. The proposed formulations are associated with fewer variables and constraints compared with models previously presented in the literature and lead to better results according to an extensive numerical study. The proposed models can be applied in practice for designing the assembly lines of, inter alia, automobile and electronic equipment production systems.","PeriodicalId":56296,"journal":{"name":"IMA Journal of Management Mathematics","volume":"34 2","pages":"285-306"},"PeriodicalIF":1.7,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67839949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To examine the familiar tradeoff between risk and return in financial investments, we use a rolling two-stage stochastic program to compare mean-risk optimization models with time series momentum strategies. In a backtest of allocating investment between a market index and a risk-free asset, we generate scenarios of future return according to a momentum-based stochastic process model. A new hybrid approach, time series momentum strategy controlling downside risk (TSMDR), frequently dominates traditional approaches by generating trading signals according to a modified momentum measure while setting the risky asset position to control the conditional value-at-risk (CVaR) of return. For insight into the outperformance of TSMDR, we decompose each strategy into two aspects, the trading signal and the asset allocation model that determines the risky asset position. We find that 1) weighted moving average can better capture the trend of the stock market than time series momentum computed as past 12-month excess return, 2) mean-risk strategies generally provide better returns whereas risk parity strategies have less investment risk and 3) controlling CVaR limits the investment risk better than controlling variance does.
{"title":"Portfolio rebalancing based on time series momentum and downside risk","authors":"Xiaoshi Guo;Sarah M Ryan","doi":"10.1093/imaman/dpab037","DOIUrl":"https://doi.org/10.1093/imaman/dpab037","url":null,"abstract":"To examine the familiar tradeoff between risk and return in financial investments, we use a rolling two-stage stochastic program to compare mean-risk optimization models with time series momentum strategies. In a backtest of allocating investment between a market index and a risk-free asset, we generate scenarios of future return according to a momentum-based stochastic process model. A new hybrid approach, time series momentum strategy controlling downside risk (TSMDR), frequently dominates traditional approaches by generating trading signals according to a modified momentum measure while setting the risky asset position to control the conditional value-at-risk (CVaR) of return. For insight into the outperformance of TSMDR, we decompose each strategy into two aspects, the trading signal and the asset allocation model that determines the risky asset position. We find that 1) weighted moving average can better capture the trend of the stock market than time series momentum computed as past 12-month excess return, 2) mean-risk strategies generally provide better returns whereas risk parity strategies have less investment risk and 3) controlling CVaR limits the investment risk better than controlling variance does.","PeriodicalId":56296,"journal":{"name":"IMA Journal of Management Mathematics","volume":"34 2","pages":"355-381"},"PeriodicalIF":1.7,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/8016797/10075382/10075383.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67839950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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