In this present paper, a deterministic lot size model is developed for deteriorating items with incremental quantity discounts. It is assumed that shortages are permitted to occur and fully backlogged. A simple solut...In this present paper, a deterministic lot size model is developed for deteriorating items with incremental quantity discounts. It is assumed that shortages are permitted to occur and fully backlogged. A simple solution procedure is shown for determining the optimal order lot size and the optimal order cycle. A numerical example is used to illustrate how the solution procedure works.展开更多
This study investigates the electric energy shortages impact upon the residential sector in Riyadh city, the capital of the Kingdom of Saudi Arabia (KSA) resulting from severe power outages. The results reveal the ext...This study investigates the electric energy shortages impact upon the residential sector in Riyadh city, the capital of the Kingdom of Saudi Arabia (KSA) resulting from severe power outages. The results reveal the extent of hardship and high costs the residential will suffer and endure. These outages occur and extend for longer durations. To mitigate these consequences, a method is suggested known as “willingness-to-pay” to seek the ability and willingness of consumers to pay to avert these power outages and energy shortages. Two approaches have been developed and utilized. The first one is based on a consumer survey to estimate his perceived costs. Outages occur in specific periods and last for longer durations. The second approach focussed on developing a mathematical model to complement the survey approach as this model can decrease the size of the problem complexity associated with consumer lack of experience in evaluating and assessing the worth of service reliability and quality.展开更多
Electricity shortages present a significant constraint on manufacturers,who rely on electricity as an important input into production.In China,electricity supply has been growing rapidly.However,the rapid industrializ...Electricity shortages present a significant constraint on manufacturers,who rely on electricity as an important input into production.In China,electricity supply has been growing rapidly.However,the rapid industrialization sometimes makes the power supply still unable to meet the demand.Using a survey of 1673 Chinese manufacturing firms,this paper explores how firms response to electricity shortages and its impact on productivity.We find that self-generation of electricity and investment in Research and Development(R&D)have significant positive relationships with electricity shortages.Further investigations reveal that self-generation is the most common way to deal with electricity shortages.However,it aggravates productivity loss.Though investment in Research and Development can promote productivity,it cannot offset the negative impact of electricity shortages on productivity.Analyses on subsamples show heterogeneity in the impacts of electricity shortages across firms.In particular,large firms are more inclined to invest in R&D than small and medium-sized firms are.They are also the one who suffer significant productivity loss due to self-generation of electricity.Though it is possible for medium-sized firms to reduce productivity loss through R&D,they are not likely to invest in R&D as a response to electricity shortages.This study illustrates that firms can hardly have effective solutions to electricity shortages,and policy makers should take great efforts to increase electricity supply.展开更多
"Water,woater evenyuwhere,and nary a drop to drink!"Poetry becomes reality in China,as experts scramble to find new supplies of the preious liquid to slake the thirst of a growing population and industry.
COVID-19, a contagious respiratory disease, presents immediate and unforeseen challenges to people worldwide. Moreover, its transmission rapidly extends globally due to its viral transmissibility, emergence of novel s...COVID-19, a contagious respiratory disease, presents immediate and unforeseen challenges to people worldwide. Moreover, its transmission rapidly extends globally due to its viral transmissibility, emergence of novel strains (variants), absence of immunity, and human unawareness. This framework introduces a revised epidemic model, drawing upon mathematical principles. This model incorporates a modified vaccination and lockdown approach to comprehensively depict an epidemics transmission, containment, and decision-making processes within a community. This study aims to provide policymakers with precise information on real-world situations to assist them in making informed decisions about the implementation of lockdown strategies, maintenance variables, and vaccine availability. The suggested model has conducted stability analysis, strength number analysis, and first and second-order derivative analysis of the Lyapunov function and has established the existence and uniqueness of solutions of the proposed models. We examine the combined effects of an effective vaccination campaign and non-pharmaceutical measures such as lockdowns and states of emergency. We rely on the results of this research to assist policymakers in various countries in eradicating the illness by developing more innovative measures to control the outbreak.展开更多
The recent electricity supply shortage in the People’s Republic of China(PRC)is driven by a disequilibrium in demand and supply.Energ y demand has picked up with the economy recovering and industry growing,strongly s...The recent electricity supply shortage in the People’s Republic of China(PRC)is driven by a disequilibrium in demand and supply.Energ y demand has picked up with the economy recovering and industry growing,strongly supported by solid merchandise export growth.At the same time,soaring coal prices have hit power producers curtailing growth in electricity supply.展开更多
The introduction of the new budget law is one of the most important achievements of the construction of national legal system. It is a landmark event in building financial system. The new budget law has made a lot of ...The introduction of the new budget law is one of the most important achievements of the construction of national legal system. It is a landmark event in building financial system. The new budget law has made a lot of breakthroughs and innovations in the budget managemenL to lead direction for further deepen fiscal reform. However, the modification of the budget law can only adopt the principle of limited modification, there are still many problems. This paper discusses the innovation and deficiency of the new budget law under the background of budget law modification, and makes suggestions to further improve the budget law.展开更多
Objective To analyze the causes of drug shortages in China and put forward some countermeasures and suggestions accordingly.Methods Based on the relevant data of 14 provinces that issued the lists of drug shortages fr...Objective To analyze the causes of drug shortages in China and put forward some countermeasures and suggestions accordingly.Methods Based on the relevant data of 14 provinces that issued the lists of drug shortages from 2018 to 2020,377 kinds of drugs were sorted out first,and then the features of shortage were analyzed descriptively.Finally,the degree and causes of shortage were studied based on field investigation and literature summary.Results and Conclusion Among the drugs in short supply across the country,69.2%of them were listed in the National Medical Insurance Catalogue,37.1%were essential drugs and 26.5%were low-price drugs.They were used for different diseases,and most were for treating nervous system and blood system.There were many reasons for drug shortages.For instance,any problems in supply chain(production,circulation,use)could lead to drug shortages,of which the production accounted for the largest proportion.This paper puts forward targeted measures to solve drug shortages from the aspects of unwillingness and inability of manufacturing enterprises in their production.展开更多
The present paper focuses an optimal policy of an inventory model for deteriorating items with generalized demand rate and deterioration rate. Shortages are allowed and partially backlogged. The salvage value is inclu...The present paper focuses an optimal policy of an inventory model for deteriorating items with generalized demand rate and deterioration rate. Shortages are allowed and partially backlogged. The salvage value is included into deteriorated units. The main objective of the model is to minimize the total cost by optimizing the value of the shortage point, cycle length and order quantity. A numerical example is carried out to illustrate the model and sensitivity analyses of major parameters are discussed.展开更多
Objective To study how to improve and perfect the information platform and processing mechanism of drug shortages in China.Methods By searching the relevant policies from official websites of FDA,European Medicines Ag...Objective To study how to improve and perfect the information platform and processing mechanism of drug shortages in China.Methods By searching the relevant policies from official websites of FDA,European Medicines Agency(EMA),Health Canada(HC)and National Health Commission,the good experience of the United States,the European Union and Canada in the construction of information platform and processing mechanism of drug shortages was summarized for reference in China.Results and Conclusion China has initially established the processing mechanism of drug shortages,but the platform construction should be improved,and the information disclosure of drug shortages varies from province to province.We should improve the information platform of drug shortages,strengthen the disclosure and communication of information,enrich the processing tools and measures after the drug shortages occurs,and strengthen the cooperation with relevant associations and other non-governmental departments.展开更多
Based on the retail inventory operation of Heilan Home,this study incorporates the price factor into inventory environment involving trapezoidal time-varying products.A joint pricing and ordering issue with deteriorat...Based on the retail inventory operation of Heilan Home,this study incorporates the price factor into inventory environment involving trapezoidal time-varying products.A joint pricing and ordering issue with deteriorating items under partial backlogged shortages is firstly explored in a fixed selling cycle.The corresponding optimization model aiming at maximizing profit performance of inventory system is developed,the theoretical analysis of solving the model is further provided,and the modelling frame generalizes some inventory models in the existing studies.Then,a solving algorithm for the model is designed to determine the optimal price,initial ordering quantity,shortage time point,and the maximum inventory level.Finally,numerical examples are presented to illustrate the model,and the results show the robustness of the proposed model.展开更多
Here an optimal continuous Production Lot size(PLS) model is developed for deterio rating items with increasing time varying demand over a finite planning horizon.The production rate is dealt with as a decision variab...Here an optimal continuous Production Lot size(PLS) model is developed for deterio rating items with increasing time varying demand over a finite planning horizon.The production rate is dealt with as a decision variable.The deterioration rate is assumed to be a constant fraction of the on hand inventory level.Shortages are permitted in every production cycle and are not backlogged.Some properties for the optimal solution of the proposed model are shown.The solvting procedure is proposed to generate an optimal continuous production schedule. The corresponding models with no deterioration and no shortage are derived as the special cases.Numerical examples for illustrating the solvting procedure are employed for linearly increasing demand.展开更多
Nowadays,it is common for suppliers to be separated from their buyers by great distances.This means that,if some items in the lot turn out to be defective,the distance makes it uneconomical to order replacements from ...Nowadays,it is common for suppliers to be separated from their buyers by great distances.This means that,if some items in the lot turn out to be defective,the distance makes it uneconomical to order replacements from the original supplier.Moreover,both Type I and Type II errors may occur in the screening process for eliminating defective items and the combination of defective items and inspection errors may lead to shortages.Working with these assumptions,this paper develops two distinct models.Under the first model,defective items are repaired by a local repair shop subject to a repair charge and a mark-up margin.Under the second model,a local supplier replaces the defective with good ones,but at a higher cost.The expected total profit per cycle is developed,together with the expected cycle time,and,employing the renewal reward theorem,the objective function is derived,from which the optimum values are obtained for the order and shortage quantities.The paper presents numerical results and a discussion for both models.The study finds that repairing defective items generally leads to greater total profit than purchasing local replacements.展开更多
In a wholesale shop,the retailer is required to keep an inventory of various ranges of a product due to uncertainty in consumer preferences and behavior.Different Economic Order Quantity(EOQ)models for each variety of...In a wholesale shop,the retailer is required to keep an inventory of various ranges of a product due to uncertainty in consumer preferences and behavior.Different Economic Order Quantity(EOQ)models for each variety of a product are needed for optimum level of inventory.EOQ model decides how much stock a shopkeeper has to store,according to demand and deterioration of different items to optimize the inventory policy of multiple products.Items like fashion,food,vegetables,pharmaceuticals,etc.,deteriorate in the retailer’s warehouse during storage.An investment is required in preservation technology to significantly reduce the deterioration rate,reduce economic losses,and increase business competitiveness.Here,a multi-item deteriorating EOQ model with a fixed cycle duration has been developed incorporating the preservation technology.The demands for the items are a quadratic function of the selling price,and shortages are allowed.The main objective is to determine the optimal selling price,investment under preservation,the time length up to zero inventory,order quantity of the proposed inventory model such that the overall profit will be maximized.First,we prove that the optimal selling price and investment in preservation exist and are unique.Next,the total profit per unit time is a concave function of selling price and preservation technology investment.An algorithm is designed to obtain the optimum joint policy.A numerical example has been given to illustrate the model,and sensitivity analysis is conducted,which gives some managerial insights.展开更多
Since a critical report on China's medical system reform was issued in mid-2005, it has become a major bone of contention. In April 2007, the State Council, China's cabinet, decided that from this year,economi...Since a critical report on China's medical system reform was issued in mid-2005, it has become a major bone of contention. In April 2007, the State Council, China's cabinet, decided that from this year,economically developed provinces should single out one or two cities to experiment with the urban basic medical insurance system that focuses on serious diseases. Meanwhile,the Ministry of Health invited seven research institutions to independently work out medical reform schemes. Ministry sources said that the finalized scheme would come into effect later this year.But will these efforts help to ease the problem of high medical expenses in China? And is it true that current problems of China's medical system lie in the "over marketization" as some experts have pointed out? Professor Cai Jiangnan, from the School of Economics, Fudan University,and Professor Zhou Qiren,from the China Center for Economic Research, Peking University,put forward their different views on this issue, based on their long-term research of China 's medical system reform.展开更多
As the macroeconomic situation is still difficult and there is no substantial stimulus prompted by news,the aluminum prices have fluctuated widely between 16,000-17,000 yuan/ton.Recently,Henan Province announced limit...As the macroeconomic situation is still difficult and there is no substantial stimulus prompted by news,the aluminum prices have fluctuated widely between 16,000-17,000 yuan/ton.Recently,Henan Province announced limited production across the province during the heating season and the Ministry of Environmental Protection also declared that30%limited production during the heating season will not overlap the policy of展开更多
In this paper, we consider the general inventory problem for deteriorating items having time-varying demand and shortages. An optimal order policy is obtained for determining the number of reorders and the time of the...In this paper, we consider the general inventory problem for deteriorating items having time-varying demand and shortages. An optimal order policy is obtained for determining the number of reorders and the time of the reorder points and shortage points in order to minimize the total cost of system. Several fundamental theoretical results are established for this model. The corresponding cases for no-deterioration and no-shortage is also discussed. To illustrate the solution procedure,numerical examples are shown for the special case of linear increasing demand.展开更多
During the ongoing COVID-19 pandemic, vaccine shortages occur due to various types of constraints, including interruptions in production/supply, higher-than-expected demands, and a lack of resources such as healthcare...During the ongoing COVID-19 pandemic, vaccine shortages occur due to various types of constraints, including interruptions in production/supply, higher-than-expected demands, and a lack of resources such as healthcare capacity to administer vaccines. Scientifically informed epidemic models have been utilized as pivotal tools to optimize the immunization programs subject to vaccine shortages. The current paper reviews modelling methods to optimize the allocation strategies of vaccines with differential efficacies by using various model-based outcome measures. The models reviewed in this study are expected to be adopted and extended to make contributions on policy development for disease control under the vaccine shortage scenario.展开更多
With the continuous development of economic globalization,especially in the face of expanding COVID-19 pandemic,the supply shortage of suppliers will directly affect the ordering strategy of enterprises,which will cau...With the continuous development of economic globalization,especially in the face of expanding COVID-19 pandemic,the supply shortage of suppliers will directly affect the ordering strategy of enterprises,which will cause price fluctuations in the commodity market and corporate profits.We assume that the demand for the product in the market is constant,and the supply determines the product price.An EOQ model is constructed with a supply shortage under the additive supply.We find that the optimal order quantity is consistent with the classic EOQ without considering product price changes;after introducing the price function,we analyze the relationship between the product’s market price and the seller’s optimal profit and the supplier uncertainty.The research results show that the product’s market price will increase with the increase of the out-of-stock quantity.At the same time,the uncertainty will decrease,and the seller’s optimal profit will decrease as the average stock-out and uncertainty increase.展开更多
文摘In this present paper, a deterministic lot size model is developed for deteriorating items with incremental quantity discounts. It is assumed that shortages are permitted to occur and fully backlogged. A simple solution procedure is shown for determining the optimal order lot size and the optimal order cycle. A numerical example is used to illustrate how the solution procedure works.
文摘This study investigates the electric energy shortages impact upon the residential sector in Riyadh city, the capital of the Kingdom of Saudi Arabia (KSA) resulting from severe power outages. The results reveal the extent of hardship and high costs the residential will suffer and endure. These outages occur and extend for longer durations. To mitigate these consequences, a method is suggested known as “willingness-to-pay” to seek the ability and willingness of consumers to pay to avert these power outages and energy shortages. Two approaches have been developed and utilized. The first one is based on a consumer survey to estimate his perceived costs. Outages occur in specific periods and last for longer durations. The second approach focussed on developing a mathematical model to complement the survey approach as this model can decrease the size of the problem complexity associated with consumer lack of experience in evaluating and assessing the worth of service reliability and quality.
基金supported by“Philosophy and Social Sciences Planned Project of Anhui Province,China”(Grant No.AHSKY2020D37).
文摘Electricity shortages present a significant constraint on manufacturers,who rely on electricity as an important input into production.In China,electricity supply has been growing rapidly.However,the rapid industrialization sometimes makes the power supply still unable to meet the demand.Using a survey of 1673 Chinese manufacturing firms,this paper explores how firms response to electricity shortages and its impact on productivity.We find that self-generation of electricity and investment in Research and Development(R&D)have significant positive relationships with electricity shortages.Further investigations reveal that self-generation is the most common way to deal with electricity shortages.However,it aggravates productivity loss.Though investment in Research and Development can promote productivity,it cannot offset the negative impact of electricity shortages on productivity.Analyses on subsamples show heterogeneity in the impacts of electricity shortages across firms.In particular,large firms are more inclined to invest in R&D than small and medium-sized firms are.They are also the one who suffer significant productivity loss due to self-generation of electricity.Though it is possible for medium-sized firms to reduce productivity loss through R&D,they are not likely to invest in R&D as a response to electricity shortages.This study illustrates that firms can hardly have effective solutions to electricity shortages,and policy makers should take great efforts to increase electricity supply.
文摘"Water,woater evenyuwhere,and nary a drop to drink!"Poetry becomes reality in China,as experts scramble to find new supplies of the preious liquid to slake the thirst of a growing population and industry.
文摘COVID-19, a contagious respiratory disease, presents immediate and unforeseen challenges to people worldwide. Moreover, its transmission rapidly extends globally due to its viral transmissibility, emergence of novel strains (variants), absence of immunity, and human unawareness. This framework introduces a revised epidemic model, drawing upon mathematical principles. This model incorporates a modified vaccination and lockdown approach to comprehensively depict an epidemics transmission, containment, and decision-making processes within a community. This study aims to provide policymakers with precise information on real-world situations to assist them in making informed decisions about the implementation of lockdown strategies, maintenance variables, and vaccine availability. The suggested model has conducted stability analysis, strength number analysis, and first and second-order derivative analysis of the Lyapunov function and has established the existence and uniqueness of solutions of the proposed models. We examine the combined effects of an effective vaccination campaign and non-pharmaceutical measures such as lockdowns and states of emergency. We rely on the results of this research to assist policymakers in various countries in eradicating the illness by developing more innovative measures to control the outbreak.
文摘The recent electricity supply shortage in the People’s Republic of China(PRC)is driven by a disequilibrium in demand and supply.Energ y demand has picked up with the economy recovering and industry growing,strongly supported by solid merchandise export growth.At the same time,soaring coal prices have hit power producers curtailing growth in electricity supply.
文摘The introduction of the new budget law is one of the most important achievements of the construction of national legal system. It is a landmark event in building financial system. The new budget law has made a lot of breakthroughs and innovations in the budget managemenL to lead direction for further deepen fiscal reform. However, the modification of the budget law can only adopt the principle of limited modification, there are still many problems. This paper discusses the innovation and deficiency of the new budget law under the background of budget law modification, and makes suggestions to further improve the budget law.
文摘Objective To analyze the causes of drug shortages in China and put forward some countermeasures and suggestions accordingly.Methods Based on the relevant data of 14 provinces that issued the lists of drug shortages from 2018 to 2020,377 kinds of drugs were sorted out first,and then the features of shortage were analyzed descriptively.Finally,the degree and causes of shortage were studied based on field investigation and literature summary.Results and Conclusion Among the drugs in short supply across the country,69.2%of them were listed in the National Medical Insurance Catalogue,37.1%were essential drugs and 26.5%were low-price drugs.They were used for different diseases,and most were for treating nervous system and blood system.There were many reasons for drug shortages.For instance,any problems in supply chain(production,circulation,use)could lead to drug shortages,of which the production accounted for the largest proportion.This paper puts forward targeted measures to solve drug shortages from the aspects of unwillingness and inability of manufacturing enterprises in their production.
文摘The present paper focuses an optimal policy of an inventory model for deteriorating items with generalized demand rate and deterioration rate. Shortages are allowed and partially backlogged. The salvage value is included into deteriorated units. The main objective of the model is to minimize the total cost by optimizing the value of the shortage point, cycle length and order quantity. A numerical example is carried out to illustrate the model and sensitivity analyses of major parameters are discussed.
文摘Objective To study how to improve and perfect the information platform and processing mechanism of drug shortages in China.Methods By searching the relevant policies from official websites of FDA,European Medicines Agency(EMA),Health Canada(HC)and National Health Commission,the good experience of the United States,the European Union and Canada in the construction of information platform and processing mechanism of drug shortages was summarized for reference in China.Results and Conclusion China has initially established the processing mechanism of drug shortages,but the platform construction should be improved,and the information disclosure of drug shortages varies from province to province.We should improve the information platform of drug shortages,strengthen the disclosure and communication of information,enrich the processing tools and measures after the drug shortages occurs,and strengthen the cooperation with relevant associations and other non-governmental departments.
基金supported by the Humanities and Social Science Foundation of the Education of Ministry of China(No.23YJA630105)the National Natural Science Foundation of China(No.11971349).
文摘Based on the retail inventory operation of Heilan Home,this study incorporates the price factor into inventory environment involving trapezoidal time-varying products.A joint pricing and ordering issue with deteriorating items under partial backlogged shortages is firstly explored in a fixed selling cycle.The corresponding optimization model aiming at maximizing profit performance of inventory system is developed,the theoretical analysis of solving the model is further provided,and the modelling frame generalizes some inventory models in the existing studies.Then,a solving algorithm for the model is designed to determine the optimal price,initial ordering quantity,shortage time point,and the maximum inventory level.Finally,numerical examples are presented to illustrate the model,and the results show the robustness of the proposed model.
文摘Here an optimal continuous Production Lot size(PLS) model is developed for deterio rating items with increasing time varying demand over a finite planning horizon.The production rate is dealt with as a decision variable.The deterioration rate is assumed to be a constant fraction of the on hand inventory level.Shortages are permitted in every production cycle and are not backlogged.Some properties for the optimal solution of the proposed model are shown.The solvting procedure is proposed to generate an optimal continuous production schedule. The corresponding models with no deterioration and no shortage are derived as the special cases.Numerical examples for illustrating the solvting procedure are employed for linearly increasing demand.
文摘Nowadays,it is common for suppliers to be separated from their buyers by great distances.This means that,if some items in the lot turn out to be defective,the distance makes it uneconomical to order replacements from the original supplier.Moreover,both Type I and Type II errors may occur in the screening process for eliminating defective items and the combination of defective items and inspection errors may lead to shortages.Working with these assumptions,this paper develops two distinct models.Under the first model,defective items are repaired by a local repair shop subject to a repair charge and a mark-up margin.Under the second model,a local supplier replaces the defective with good ones,but at a higher cost.The expected total profit per cycle is developed,together with the expected cycle time,and,employing the renewal reward theorem,the objective function is derived,from which the optimum values are obtained for the order and shortage quantities.The paper presents numerical results and a discussion for both models.The study finds that repairing defective items generally leads to greater total profit than purchasing local replacements.
文摘In a wholesale shop,the retailer is required to keep an inventory of various ranges of a product due to uncertainty in consumer preferences and behavior.Different Economic Order Quantity(EOQ)models for each variety of a product are needed for optimum level of inventory.EOQ model decides how much stock a shopkeeper has to store,according to demand and deterioration of different items to optimize the inventory policy of multiple products.Items like fashion,food,vegetables,pharmaceuticals,etc.,deteriorate in the retailer’s warehouse during storage.An investment is required in preservation technology to significantly reduce the deterioration rate,reduce economic losses,and increase business competitiveness.Here,a multi-item deteriorating EOQ model with a fixed cycle duration has been developed incorporating the preservation technology.The demands for the items are a quadratic function of the selling price,and shortages are allowed.The main objective is to determine the optimal selling price,investment under preservation,the time length up to zero inventory,order quantity of the proposed inventory model such that the overall profit will be maximized.First,we prove that the optimal selling price and investment in preservation exist and are unique.Next,the total profit per unit time is a concave function of selling price and preservation technology investment.An algorithm is designed to obtain the optimum joint policy.A numerical example has been given to illustrate the model,and sensitivity analysis is conducted,which gives some managerial insights.
文摘Since a critical report on China's medical system reform was issued in mid-2005, it has become a major bone of contention. In April 2007, the State Council, China's cabinet, decided that from this year,economically developed provinces should single out one or two cities to experiment with the urban basic medical insurance system that focuses on serious diseases. Meanwhile,the Ministry of Health invited seven research institutions to independently work out medical reform schemes. Ministry sources said that the finalized scheme would come into effect later this year.But will these efforts help to ease the problem of high medical expenses in China? And is it true that current problems of China's medical system lie in the "over marketization" as some experts have pointed out? Professor Cai Jiangnan, from the School of Economics, Fudan University,and Professor Zhou Qiren,from the China Center for Economic Research, Peking University,put forward their different views on this issue, based on their long-term research of China 's medical system reform.
文摘As the macroeconomic situation is still difficult and there is no substantial stimulus prompted by news,the aluminum prices have fluctuated widely between 16,000-17,000 yuan/ton.Recently,Henan Province announced limited production across the province during the heating season and the Ministry of Environmental Protection also declared that30%limited production during the heating season will not overlap the policy of
文摘In this paper, we consider the general inventory problem for deteriorating items having time-varying demand and shortages. An optimal order policy is obtained for determining the number of reorders and the time of the reorder points and shortage points in order to minimize the total cost of system. Several fundamental theoretical results are established for this model. The corresponding cases for no-deterioration and no-shortage is also discussed. To illustrate the solution procedure,numerical examples are shown for the special case of linear increasing demand.
文摘During the ongoing COVID-19 pandemic, vaccine shortages occur due to various types of constraints, including interruptions in production/supply, higher-than-expected demands, and a lack of resources such as healthcare capacity to administer vaccines. Scientifically informed epidemic models have been utilized as pivotal tools to optimize the immunization programs subject to vaccine shortages. The current paper reviews modelling methods to optimize the allocation strategies of vaccines with differential efficacies by using various model-based outcome measures. The models reviewed in this study are expected to be adopted and extended to make contributions on policy development for disease control under the vaccine shortage scenario.
文摘With the continuous development of economic globalization,especially in the face of expanding COVID-19 pandemic,the supply shortage of suppliers will directly affect the ordering strategy of enterprises,which will cause price fluctuations in the commodity market and corporate profits.We assume that the demand for the product in the market is constant,and the supply determines the product price.An EOQ model is constructed with a supply shortage under the additive supply.We find that the optimal order quantity is consistent with the classic EOQ without considering product price changes;after introducing the price function,we analyze the relationship between the product’s market price and the seller’s optimal profit and the supplier uncertainty.The research results show that the product’s market price will increase with the increase of the out-of-stock quantity.At the same time,the uncertainty will decrease,and the seller’s optimal profit will decrease as the average stock-out and uncertainty increase.
