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
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.
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
Due to the effects of windless and sunless weather, new power systems dominated by renewable energy sources experience power supply shortages, which lead to severe electricity shortages. Because of the insufficient pr...Due to the effects of windless and sunless weather, new power systems dominated by renewable energy sources experience power supply shortages, which lead to severe electricity shortages. Because of the insufficient proportion of controllable thermal power in these systems, this problem must be addressed from the load side. This study proposes an orderly power utilization(OPU) method with load as the primary dispatching object to address the problem of severe electricity shortages. The principles and architecture of the new urban power grid(NUPG) OPU are proposed to complete the load curtailment task and minimize the effects on social production and daily life. A flexible load baseline division method is proposed that considers the effects of factors such as gross domestic product, pollutant emission, and carbon emission to increase the flexibility and applicability of the proposed method. In addition, an NUPG OPU model based on the load baseline is proposed, in which the electric quantity balance aggregator(EQBA) serves as a regular participant in the OPU and eliminates the need for other user involvement within its capacity range. The electric quantity reserve aggregator(EQRA) functions as a supplementary participant in the OPU and primarily performs the remaining tasks of the EQBA. The electric power balance aggregator primarily offsets the power fluctuations of the OPU. Case studies demonstrate the effectiveness and superiority of the proposed model in ensuring the completion of the load curtailment task, enhancing the flexibility and fairness of OPUs, and improving the applicability of the proposed method.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
Solar energy, as a renewable resource, is an effective solution to the current global energy shortage problem. To actively respond to the call for "carbon peak" and "carbon neutrality", solar cell ...Solar energy, as a renewable resource, is an effective solution to the current global energy shortage problem. To actively respond to the call for "carbon peak" and "carbon neutrality", solar cell industry has experienced unprecedented development. The full utilization of solar energy resources remains an urgent issue to be addressed.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
Countries worldwide are advocating for energy transition initiatives to promote the construction of low-carbon energy systems.The low voltage ride through(LVRT)characteristics of renewable energy units and commutation...Countries worldwide are advocating for energy transition initiatives to promote the construction of low-carbon energy systems.The low voltage ride through(LVRT)characteristics of renewable energy units and commutation failures in line commutated converter high voltage direct current(LCC-HVDC)systems at the receiving end leads to short-term power shortage(STPS),which differs from traditional frequency stability issues.STPS occurs during the generator’s power angle swing phase,before the governor responds,and is on a timescale that is not related to primary frequency regulation.This paper addresses these challenges by examining the impact of LVRT on voltage stability,developing a frequency response model to analyze the mechanism of frequency instability caused by STPS,deriving the impact of STPS on the maximum frequency deviation,and introducing an energy deficiency factor to assess its impact on regional frequency stability.The East China Power Grid is used as a case study,where the energy deficiency factor is calculated to validate the proposed mechanism.STPS is mainly compensated by the rotor kinetic energy of the generators in this region,with minimal impact on other regions.It is concluded that the energy deficiency factor provides an effective explanation for the spatial distribution of the impact of STPS on system frequency.展开更多
Chinese-built project delivers clean water to over 450,000 people in Tanzanian capital city For years,Hassan Juma has struggled to secure clean water for his family in Dar es Salaam’s southern suburb of Bangulo.Like ...Chinese-built project delivers clean water to over 450,000 people in Tanzanian capital city For years,Hassan Juma has struggled to secure clean water for his family in Dar es Salaam’s southern suburb of Bangulo.Like many in the sprawling coastal city,he has faced persistent water shortages and has been forced to rely on expensive private vendors to meet his household’s basic needs.展开更多
Brackish water(BW)irrigation may cause soil quality deterioration and thereby a decrease in crop yields.Here we examined the impacts of applying gasification filter cake(GFC),intercropping with Portulaca oleracea(PO),...Brackish water(BW)irrigation may cause soil quality deterioration and thereby a decrease in crop yields.Here we examined the impacts of applying gasification filter cake(GFC),intercropping with Portulaca oleracea(PO),and their combination on soil quality,nutrient uptake by plants and tomato yields under BW irrigation.The treatments evaluated included(i)freshwater irrigation(Control),(ii)BW irrigation,(iii)GFC application under BW irrigation(BW+GFC),(iv)intercropping with PO under BW irrigation(BW+PO),and(v)the combined application of GFC and PO under BW irrigation(BW+PO+GFC).Overall,the use of BW for irrigation resulted in a decline in both soil quality(assessed by a soil quality index(SQI)integrating a wide range of key soil properties including salinity,nutrient availability and microbial activities)and crop yields.Nevertheless,when subjected to BW irrigation,the application of GFC successfully prevented soil salinity.Additionally,the intercropping of PO decreased the soil sodium adsorption ratio and improved the absorption of nutrients by plants.As a result,the BW+GFC+PO treatment generally showed higher tomato yield as compared to other BW-related treatments(i.e.BW,BW+GFC and BW+PO).Compared to BW,the BW+GFC+PO treatment had an average increase of 24.7% in the total fruit yield of four Cropping Seasons.Furthermore,the BW+GFC+PO treatment consistently exhibited the highest fruit quality index(FQI).Taken together,the combined application of GFC and PO is effective in promoting soil quality and crop yields under BW irrigation.展开更多
In order to address the widespread data shortage problem in battery research,this paper proposes a generative adversarial network model that combines it with deep convolutional networks,the Wasserstein distance,and th...In order to address the widespread data shortage problem in battery research,this paper proposes a generative adversarial network model that combines it with deep convolutional networks,the Wasserstein distance,and the gradient penalty to achieve data augmentation.To lower the threshold for implementing the proposed method,transfer learning is further introduced.The W-DC-GAN-GP-TL framework is thereby formed.This framework is evaluated on 3 different publicly available datasets to judge the quality of generated data.Through visual comparisons and the examination of two visualization methods(probability density function(PDF)and principal component analysis(PCA)),it is demonstrated that the generated data is hard to distinguish from the real data.The application of generated data for training a battery state model using transfer learning is further evaluated.Specifically,Bi-GRU-based and Transformer-based methods are implemented on 2 separate datasets for estimating state of health(SOH)and state of charge(SOC),respectively.The results indicate that the proposed framework demonstrates satisfactory performance in different scenarios:for the data replacement scenario,where real data are removed and replaced with generated data,the state estimator accuracy decreases only slightly;for the data enhancement scenario,the estimator accuracy is further improved.The estimation accuracy of SOH and SOC is as low as 0.69%and 0.58%root mean square error(RMSE)after applying the proposed framework.This framework provides a reliable method for enriching battery measurement data.It is a generalized framework capable of generating a variety of time series data.展开更多
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.
基金This work was supported by the National Natural Science Foundation of China(No.51877049).
文摘Due to the effects of windless and sunless weather, new power systems dominated by renewable energy sources experience power supply shortages, which lead to severe electricity shortages. Because of the insufficient proportion of controllable thermal power in these systems, this problem must be addressed from the load side. This study proposes an orderly power utilization(OPU) method with load as the primary dispatching object to address the problem of severe electricity shortages. The principles and architecture of the new urban power grid(NUPG) OPU are proposed to complete the load curtailment task and minimize the effects on social production and daily life. A flexible load baseline division method is proposed that considers the effects of factors such as gross domestic product, pollutant emission, and carbon emission to increase the flexibility and applicability of the proposed method. In addition, an NUPG OPU model based on the load baseline is proposed, in which the electric quantity balance aggregator(EQBA) serves as a regular participant in the OPU and eliminates the need for other user involvement within its capacity range. The electric quantity reserve aggregator(EQRA) functions as a supplementary participant in the OPU and primarily performs the remaining tasks of the EQBA. The electric power balance aggregator primarily offsets the power fluctuations of the OPU. Case studies demonstrate the effectiveness and superiority of the proposed model in ensuring the completion of the load curtailment task, enhancing the flexibility and fairness of OPUs, and improving the applicability of the proposed method.
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Solar energy, as a renewable resource, is an effective solution to the current global energy shortage problem. To actively respond to the call for "carbon peak" and "carbon neutrality", solar cell industry has experienced unprecedented development. The full utilization of solar energy resources remains an urgent issue to be addressed.
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.
基金funded by the Technology Project of State Grid Corporation of China(Research on Safety and Stability Evaluation and Optimization Enhancement Technology of Flexible Ultra High Voltage Multiterminal DC System Adapting to the Background of“Sand and Gobi Deserts”),grant number J2024003。
文摘Countries worldwide are advocating for energy transition initiatives to promote the construction of low-carbon energy systems.The low voltage ride through(LVRT)characteristics of renewable energy units and commutation failures in line commutated converter high voltage direct current(LCC-HVDC)systems at the receiving end leads to short-term power shortage(STPS),which differs from traditional frequency stability issues.STPS occurs during the generator’s power angle swing phase,before the governor responds,and is on a timescale that is not related to primary frequency regulation.This paper addresses these challenges by examining the impact of LVRT on voltage stability,developing a frequency response model to analyze the mechanism of frequency instability caused by STPS,deriving the impact of STPS on the maximum frequency deviation,and introducing an energy deficiency factor to assess its impact on regional frequency stability.The East China Power Grid is used as a case study,where the energy deficiency factor is calculated to validate the proposed mechanism.STPS is mainly compensated by the rotor kinetic energy of the generators in this region,with minimal impact on other regions.It is concluded that the energy deficiency factor provides an effective explanation for the spatial distribution of the impact of STPS on system frequency.
文摘Chinese-built project delivers clean water to over 450,000 people in Tanzanian capital city For years,Hassan Juma has struggled to secure clean water for his family in Dar es Salaam’s southern suburb of Bangulo.Like many in the sprawling coastal city,he has faced persistent water shortages and has been forced to rely on expensive private vendors to meet his household’s basic needs.
基金supported by the Key Research and Development Program of Ningxia(Grant No.2023BCF01046)。
文摘Brackish water(BW)irrigation may cause soil quality deterioration and thereby a decrease in crop yields.Here we examined the impacts of applying gasification filter cake(GFC),intercropping with Portulaca oleracea(PO),and their combination on soil quality,nutrient uptake by plants and tomato yields under BW irrigation.The treatments evaluated included(i)freshwater irrigation(Control),(ii)BW irrigation,(iii)GFC application under BW irrigation(BW+GFC),(iv)intercropping with PO under BW irrigation(BW+PO),and(v)the combined application of GFC and PO under BW irrigation(BW+PO+GFC).Overall,the use of BW for irrigation resulted in a decline in both soil quality(assessed by a soil quality index(SQI)integrating a wide range of key soil properties including salinity,nutrient availability and microbial activities)and crop yields.Nevertheless,when subjected to BW irrigation,the application of GFC successfully prevented soil salinity.Additionally,the intercropping of PO decreased the soil sodium adsorption ratio and improved the absorption of nutrients by plants.As a result,the BW+GFC+PO treatment generally showed higher tomato yield as compared to other BW-related treatments(i.e.BW,BW+GFC and BW+PO).Compared to BW,the BW+GFC+PO treatment had an average increase of 24.7% in the total fruit yield of four Cropping Seasons.Furthermore,the BW+GFC+PO treatment consistently exhibited the highest fruit quality index(FQI).Taken together,the combined application of GFC and PO is effective in promoting soil quality and crop yields under BW irrigation.
基金funded by the Bavarian State Ministry of Science,Research and Art(Grant number:H.2-F1116.WE/52/2)。
文摘In order to address the widespread data shortage problem in battery research,this paper proposes a generative adversarial network model that combines it with deep convolutional networks,the Wasserstein distance,and the gradient penalty to achieve data augmentation.To lower the threshold for implementing the proposed method,transfer learning is further introduced.The W-DC-GAN-GP-TL framework is thereby formed.This framework is evaluated on 3 different publicly available datasets to judge the quality of generated data.Through visual comparisons and the examination of two visualization methods(probability density function(PDF)and principal component analysis(PCA)),it is demonstrated that the generated data is hard to distinguish from the real data.The application of generated data for training a battery state model using transfer learning is further evaluated.Specifically,Bi-GRU-based and Transformer-based methods are implemented on 2 separate datasets for estimating state of health(SOH)and state of charge(SOC),respectively.The results indicate that the proposed framework demonstrates satisfactory performance in different scenarios:for the data replacement scenario,where real data are removed and replaced with generated data,the state estimator accuracy decreases only slightly;for the data enhancement scenario,the estimator accuracy is further improved.The estimation accuracy of SOH and SOC is as low as 0.69%and 0.58%root mean square error(RMSE)after applying the proposed framework.This framework provides a reliable method for enriching battery measurement data.It is a generalized framework capable of generating a variety of time series data.
