With the aid of multi-agent based modeling approach to complex systems, the hierarchy simulation models of carrier-based aircraft catapult launch are developed. Ocean, carrier, aircraft, and atmosphere are treated as ...With the aid of multi-agent based modeling approach to complex systems, the hierarchy simulation models of carrier-based aircraft catapult launch are developed. Ocean, carrier, aircraft, and atmosphere are treated as aggregation agents, the detailed components like catapult, landing gears, and disturbances are considered as meta-agents, which belong to their aggregation agent. Thus, the model with two layers is formed i.e. the aggregation agent layer and the meta-agent layer. The information communication among all agents is described. The meta-agents within one aggregation agent communicate with each other directly by information sharing, but the meta-agents, which belong to different aggregation agents exchange their information through the aggregation layer first, and then perceive it from the sharing environment, that is the aggregation agent. Thus, not only the hierarchy model is built, but also the environment perceived by each agent is specified. Meanwhile, the problem of balancing the independency of agent and the resource consumption brought by real-time communication within multi-agent system （MAS） is resolved. Each agent involved in carrier-based aircraft catapult launch is depicted, with considering the interaction within disturbed atmospheric environment and multiple motion bodies including carrier, aircraft, and landing gears. The models of reactive agents among them are derived based on tensors, and the perceived messages and inner frameworks of each agent are characterized. Finally, some results of a simulation instance are given. The simulation and modeling of dynamic system based on multi-agent system is of benefit to express physical concepts and logical hierarchy clearly and precisely. The system model can easily draw in kinds of other agents to achieve a precise simulation of more complex system. This modeling technique makes the complex integral dynamic equations of multibodies decompose into parallel operations of single agent, and it is convenient to expand, maintain, and reuse the program codes.展开更多
Different from the organization structure of complex projects in Western countries, the Liang Zong hierarchical organization structure of complex projects in China has two different chains, the chief-engineer chain an...Different from the organization structure of complex projects in Western countries, the Liang Zong hierarchical organization structure of complex projects in China has two different chains, the chief-engineer chain and the general-director chain,to handle the trade-off between technical and management decisions. However, previous works on organization search have mainly focused on the single-chain hierarchical organization in which all decisions are regarded as homogeneous. The heterogeneity and the interdependency between technical decisions and management decisions have been neglected. A two-chain hierarchical organization structure mapped from a real complex project is constructed. Then, a discrete decision model for a Liang Zong two-chain hierarchical organization in an NK model framework is proposed. This model proves that this kind of organization structure can reduce the search space by a large amount and that the search process should reach a final stable state more quickly. For a more complicated decision mechanism, a multi-agent simulation based on the above NK model is used to explore the effect of the two-chain organization structure on the speed, stability, and performance of the search process. The results provide three insights into how, compared with the single-chain hierarchical organization, the two-chain organization can improve the search process: it can reduce the number of iterations efficiently; the search is more stable because the search space is a smoother hill-like fitness landscape; in general, the search performance can be improved.However, when the organization structure is very complicated, the performance of a two-chain organization is inferior to that of a single-chain organization. These findings about the efficiency of the unique Chinese-style organization structure can be used to guide organization design for complex projects.展开更多
Regional cities in Japan are at the risk of experiencing big fire accidents or earthquakes every day.However,neither the number nor the capacity of shelters has increased because local governments might not consider t...Regional cities in Japan are at the risk of experiencing big fire accidents or earthquakes every day.However,neither the number nor the capacity of shelters has increased because local governments might not consider them owing to budget shortfall.By contrast,wide-area evacuation simulations can easily provide an antagonizing image of regional urban disasters.After a disaster,the city collapses and the evacuation routes are closed;consequently,evacuees feel anxious and they cannot move as usual.This anxiety behavior has not been considered in previous related studies and simulations.In this study,a wide-area evacuation simulation is developed;this model can not only calculate the possibility of blocking escape routes when the city is broken but also provide safe and more realistic evacuation plans before a disaster occurs by incorporating into the simulation the risk avoidance behaviors of evacuees from road blockage,such as“the route re-seeking behavior”and“the shelter re-selecting behavior”.展开更多
The prediction of the behavior of people in a disaster has a useful role to play in the design of urban structures such as department stores, schools, and office buildings. We focus on using emergency exit signs to ef...The prediction of the behavior of people in a disaster has a useful role to play in the design of urban structures such as department stores, schools, and office buildings. We focus on using emergency exit signs to effectively guide the evacuation of people on a floor with a dynamically changing layout. A multi-agent simulation is developed to simulate the behavior of evacuees on a floor. A mathematical model is constructed to obtain optimal sign locations to efficiently assist evacuation under the condition that obstacles are dynamically generated on the floor. The optimal sign locations are calculated by the mathematical model. Then, the developed simulation is performed to evaluate the effectiveness of the emergency exit signs and the behavior of evacuees on simple layout models using the calculated optimal sign locations.展开更多
Taking the Chinese city of Xiamen as an example,simulation and quantitative analysis were performed on the transmissions of the Coronavirus Disease 2019(COVID-19)and the influence of intervention combinations to assis...Taking the Chinese city of Xiamen as an example,simulation and quantitative analysis were performed on the transmissions of the Coronavirus Disease 2019(COVID-19)and the influence of intervention combinations to assist policymakers in the preparation of targeted response measures.A machine learning model was built to estimate the effectiveness of interventions and simulate transmission in different scenarios.The comparison was conducted between simulated and real cases in Xiamen.A web interface with adjustable parameters,including choice of intervention measures,intervention weights,vaccination,and viral variants,was designed for users to run the simulation.The total case number was set as the outcome.The cumulative number was 4,614,641 without restrictions and 78 under the strictest intervention set.Simulation with the parameters closest to the real situation of the Xiamen outbreak was performed to verify the accuracy and reliability of the model.The simulation model generated a duration of 52 days before the daily cases dropped to zero and the final cumulative case number of 200,which were 25 more days and 36 fewer cases than the real situation,respectively.Targeted interventions could benefit the prevention and control of COVID-19 outbreak while safeguarding public health and mitigating impacts on people’s livelihood.展开更多
In multi-agent system, agents work together for solving complex tasks and reaching common goals. In this paper, we propose a cognitive model for multi-agent collaboration. Based on the cognitive model, an agent archit...In multi-agent system, agents work together for solving complex tasks and reaching common goals. In this paper, we propose a cognitive model for multi-agent collaboration. Based on the cognitive model, an agent architecture will also be presented. This agent has BDI, awareness and policy driven mechanism concurrently. These approaches are integrated in one agent that will make multi-agent collaboration more practical in the real world.展开更多
Continuously growing populations and rapid economic development have led to the excessive use of forest resources,and the forest ecosystem is threatened.In response,forest ecological security(FES)has attracted attenti...Continuously growing populations and rapid economic development have led to the excessive use of forest resources,and the forest ecosystem is threatened.In response,forest ecological security(FES)has attracted attention.In this study,an integrated dynamic simulation model was constructed using the system dynamic method,and it was used to evaluate the FES in China from 1999 to 2014.A scenario analysis was then used to evaluate the changes in the FES under five forestry policy scenarios for the 2015–2050 period,including the baseline,afforestation policy,harvesting policies,management policy,investment policy,and a policy mix.The results showed that the evaluation values of the FES increased during the period from 1999 to 2002,the period from 2004 to 2010 and the year 2014,and they decreased in 2003 and during the period from 2011 to 2013.During the 2015–2050 simulation period,the FES improved continuously.In particular,China would enter a new stage when the economic systems,social systems and ecosystems were in harmony after 2040.To improve the FES and the current status of the FES,a scenario analysis showed the most suitable scenario to be Scenario 5 from 2015 to 2020 and Scenario 2 from 2021 to 2050.To relieve pressure,the most suitable scenario would be Scenario 5 from 2015 to 2040 and from 2046 to 2050,and the most suitable scenario would be Scenario 4 for 2041–2045.A policy mix(Scenario 5)would be most efficient under current conditions,while the effects of all the benefits of the forestry policies would weaken over the long term.The integrated method can be regarded as a decision support tool to help policy makers understand FES and promulgate a reasonable forestry policy.展开更多
China is now experiencing rapid urbanization. Powerful tools are required to assess its urban spatial policies before implemented toward a more competitive and sustainable development paradigm. This study develops a L...China is now experiencing rapid urbanization. Powerful tools are required to assess its urban spatial policies before implemented toward a more competitive and sustainable development paradigm. This study develops a Land Use Transport Interaction(LUTI) model to evaluate the impacts of urban land-use policies on urban spatial development. The model consists of four sub-models, i.e., transport, residential location, employment location and real estate rent sub-models. It is then applied to Beijing metropolitan area to forecast the urban activity evolution trend based on the land-use policies between 2009 and 2013. The modeling results show that more and more residents and enterprises in the city choose to agglomerate on outskirts, and new centers gradually emerge to share the services originally delivered by central Beijing. The general trend verifies the objectives of the government plan to develop more sub-centers around Beijing. The proposed activity-based model provides a distinct tool for the urban spatial policy makers in China. Further research is also discussed at the end.展开更多
Computer simulation was used for predictive analysis of the effects of weather and soil type on crop yield in the U.S. crop insurance program. The Environmental Policy Integrated Climate （EPIC） model was modified to...Computer simulation was used for predictive analysis of the effects of weather and soil type on crop yield in the U.S. crop insurance program. The Environmental Policy Integrated Climate （EPIC） model was modified to include hail weather events, which completed the modifications necessary to simulate the four most frequent causes of crop yield loss （hail, excessive wet, excessive cold, and excessive dry） associated with soil type in Kansas, USA. At the region level, per hectare yields were simulated for corn, wheat, soybean, and sorghum. We concluded that it was possible to predict crop yields through computer simulation with greater than 93% accuracy. The hail damage model test indicated EPIC could predict hail-soil-induced yield losses reasonably well （R^2 〉 0.6）. The investigation of soil type influence on dryland sorghum and wheat production indicated that Wymore silty clay loam soil and Kenorna silt loam produced the highest sorghum yields statistically; Kuma silt loam, Roxbury silt loam, Crete silty clay loam, and Woodson silt soils produced the second highest sorghum yields statistically; and Richfiled silt loam, Wells loam, and Canadian sandy loam produced the lowest sorghum yields. By contrast, wheat production showed less sensitivity to soil type variation. The less sensitive response of wheat yields to the soil type could be largely due to the unconsidered small-scale variability of soil features.展开更多
People power is the fundamental concept of democracy and power of the people is exercised though voting. People decide who should be elected to make decisions for them. However, if people do not properly participate i...People power is the fundamental concept of democracy and power of the people is exercised though voting. People decide who should be elected to make decisions for them. However, if people do not properly participate in the voting process and only two-thirds of all eligible voters participate in an election, the democratic institution loses its credibility and becomes vulnerable. This paper investigates various changes in voting institutions throughout the USAwith a simulation model that analyzes the efficacy of such methods to attain higher voter turnout.展开更多
This study tries to develop and use a small macroeconometric model to capture the main short-term macro dynamics and to forecast major macroeconomic variables of the Malawian economy. The results show that a reduction...This study tries to develop and use a small macroeconometric model to capture the main short-term macro dynamics and to forecast major macroeconomic variables of the Malawian economy. The results show that a reduction in the policy rate leads to a fall in the lending rate, but with an increase in money supply, and with an insignificant impact on output growth. The results suggest that monetary authorities in Malawi have to make a choice between the objectives of maintaining lower money supply and lowering the lending rate. The results also suggest that, despite the Reserve Bank of Malawi Act of 1989 stipulating that monetary authorities should pursue both price and high growth and employment objectives, our results reveal that price stability is the principal objective of monetary policy in the country. Suggesting that monetary authorities in the country should not only place more emphasis on the objective of stabilization and achieving low inflation, but also focus on supporting strong, sustained and shared growth. To some extent further suggesting that emphasis should be placed on policies and strategies aimed at structurally transforming the Malawian economy so that the monetary policies’ impact should translate into an increase in the country’s output and growth. Further suggesting enhanced effective coordination between fiscal and monetary policies.展开更多
One of the main objectives of artificial intelligence lies in the simulation of the behavior of living organisms;emotions are a fundamental part of life, and they cannot be left aside when simulating behavior. In this...One of the main objectives of artificial intelligence lies in the simulation of the behavior of living organisms;emotions are a fundamental part of life, and they cannot be left aside when simulating behavior. In this research, software is developed that simulates the behavior of birds with different characteristics. The latter interacts by considering different stimuli from the environment (external), and the internal state of the subject (objectives). To achieve this, a model of birds in the role of prey and predators is developed that focuses on the study of the interaction between these organisms that exhibit specific behaviors in their environment. This project is a seminal work that aims to represent the emotions of birds, and the latter caused by stimuli from a dynamic environment.展开更多
To acquire a competitive advantage in the expanding market,manufacturing enterprises should be able to manage their supply chains as effectively as possible.It is now becoming popular to model supply chains as multi-a...To acquire a competitive advantage in the expanding market,manufacturing enterprises should be able to manage their supply chains as effectively as possible.It is now becoming popular to model supply chains as multi-agent systems and use discrete event simulation to learn more about their behaviors or investigate the implications of alternative configurations.In order to enhance the computational efficiency and keep the simulation credibility,this paper proposes a message-driving formalism for the simulation of multi-agent supply chain systems.Through the message-driving formalism,the problem of shared variables is addressed and the parallel operation of agents is implemented.Simulation experiments with a prototype implementation show that the message-driving formalism is able to provide credible results in significantly less simulation time.展开更多
Electricity systems are key to transforming today’s society into a carbon-free economy.Long-term electricity market mechanisms,including auctions,support schemes,and other policy instruments,are critical in shaping t...Electricity systems are key to transforming today’s society into a carbon-free economy.Long-term electricity market mechanisms,including auctions,support schemes,and other policy instruments,are critical in shaping the electricity generation mix.In light of the need for more advanced tools to support policymakers and other stakeholders in designing,testing,and evaluating long-term markets,this work presents a multi-agent reinforcement learning model capable of capturing the key features of decarbonizing energy systems.Profitmaximizing generation companies make investment decisions in the wholesale electricity market,responding to system needs,competitive dynamics,and policy signals.The model employs independent proximal policy optimization,which was selected for suitability to the decentralized and competitive environment.Nevertheless,given the inherent challenges of independent learning in multi-agent settings,an extensive hyperparameter search ensures that decentralized training yields market outcomes consistent with competitive behavior.The model is applied to a stylized version of the Italian electricity system and tested under varying levels of competition,market designs,and policy scenarios.Results highlight the critical role of market design for decarbonizing the electricity sector and avoiding price volatility.The proposed framework allows assessing long-term electricity markets in which multiple policy and market mechanisms interact simultaneously,with market participants responding and adapting to decarbonization pathways.展开更多
Since 2010,Chinese government has introduced a series of administrative policies to limit speculation in the housing market to stabilize price fluctuations and keep the housing market in a healthy state of development...Since 2010,Chinese government has introduced a series of administrative policies to limit speculation in the housing market to stabilize price fluctuations and keep the housing market in a healthy state of development.In order to investigate whether administrative policy can play its due role,this paper constructs a comprehensive bottom-up housing market heterogeneous households multiagent model(HHMAM)to undertake research on the differentiated effect of administrative policy in different cities.The empirical studies find that:1)Administrative policy that increases interest rates will cause housing prices to continue to decline in the long term,but they will resume a rising trend after reaching the lowest point;2)If the government cancels a property-purchasing limitation,housing prices will continue to rise;and 3)investors tend to invest in 1st-tier cities due to the high demand and greater likelihood of appreciation in these cities.展开更多
Based on the reality that 29 Chinese provinces have already implemented the policy allowing a couple to raise a second child if either parent is an only child, this paper provides an empirical study on the effect of t...Based on the reality that 29 Chinese provinces have already implemented the policy allowing a couple to raise a second child if either parent is an only child, this paper provides an empirical study on the effect of this policy on the financial status of the social pooling fund of basic pension insurance for urban employees. Our study suggests the followings. First, under the previous unchanged family planning policy, current deficits and cumulative deficits will occur in the social pooling fund in the year 2047 and 2063 respectively. Second, if lO% to 50% of qualified couples choose to raise a second child, the financial status of the social pooling fund will improve; relative to the previous unchanged family planning policy, the contribution ratio can decrease from 20% to the range between 18.06% and 19.57% without causing any changes to the original financial status of income and expenditure. Third, if the percentage of couples choosing to raise a second child rises to 60% to 100%, the contribution ratio can even decrease to the range between 16.55% and 17. 7% without causing any changes to the financial status as under the previous unchanged family planning policy. The above conclusions have all passed the sensitivity test. Therefore, the ＂two-child policy＂ for qualified couples is favorable to alleviating the payment pressures of pension insurance but the policy effectiveness is subject to fertility desire and the intensity of government implementation.展开更多
基金Aeronautical Science Foundation of China (2006ZA51004)
文摘With the aid of multi-agent based modeling approach to complex systems, the hierarchy simulation models of carrier-based aircraft catapult launch are developed. Ocean, carrier, aircraft, and atmosphere are treated as aggregation agents, the detailed components like catapult, landing gears, and disturbances are considered as meta-agents, which belong to their aggregation agent. Thus, the model with two layers is formed i.e. the aggregation agent layer and the meta-agent layer. The information communication among all agents is described. The meta-agents within one aggregation agent communicate with each other directly by information sharing, but the meta-agents, which belong to different aggregation agents exchange their information through the aggregation layer first, and then perceive it from the sharing environment, that is the aggregation agent. Thus, not only the hierarchy model is built, but also the environment perceived by each agent is specified. Meanwhile, the problem of balancing the independency of agent and the resource consumption brought by real-time communication within multi-agent system （MAS） is resolved. Each agent involved in carrier-based aircraft catapult launch is depicted, with considering the interaction within disturbed atmospheric environment and multiple motion bodies including carrier, aircraft, and landing gears. The models of reactive agents among them are derived based on tensors, and the perceived messages and inner frameworks of each agent are characterized. Finally, some results of a simulation instance are given. The simulation and modeling of dynamic system based on multi-agent system is of benefit to express physical concepts and logical hierarchy clearly and precisely. The system model can easily draw in kinds of other agents to achieve a precise simulation of more complex system. This modeling technique makes the complex integral dynamic equations of multibodies decompose into parallel operations of single agent, and it is convenient to expand, maintain, and reuse the program codes.
基金supported by the National Natural Science Foundation of China(7157105771390522)the Key Lab for Public Engineering Audit of Jiangsu Province,Nanjing Audit University(GGSS2016-08)
文摘Different from the organization structure of complex projects in Western countries, the Liang Zong hierarchical organization structure of complex projects in China has two different chains, the chief-engineer chain and the general-director chain,to handle the trade-off between technical and management decisions. However, previous works on organization search have mainly focused on the single-chain hierarchical organization in which all decisions are regarded as homogeneous. The heterogeneity and the interdependency between technical decisions and management decisions have been neglected. A two-chain hierarchical organization structure mapped from a real complex project is constructed. Then, a discrete decision model for a Liang Zong two-chain hierarchical organization in an NK model framework is proposed. This model proves that this kind of organization structure can reduce the search space by a large amount and that the search process should reach a final stable state more quickly. For a more complicated decision mechanism, a multi-agent simulation based on the above NK model is used to explore the effect of the two-chain organization structure on the speed, stability, and performance of the search process. The results provide three insights into how, compared with the single-chain hierarchical organization, the two-chain organization can improve the search process: it can reduce the number of iterations efficiently; the search is more stable because the search space is a smoother hill-like fitness landscape; in general, the search performance can be improved.However, when the organization structure is very complicated, the performance of a two-chain organization is inferior to that of a single-chain organization. These findings about the efficiency of the unique Chinese-style organization structure can be used to guide organization design for complex projects.
文摘Regional cities in Japan are at the risk of experiencing big fire accidents or earthquakes every day.However,neither the number nor the capacity of shelters has increased because local governments might not consider them owing to budget shortfall.By contrast,wide-area evacuation simulations can easily provide an antagonizing image of regional urban disasters.After a disaster,the city collapses and the evacuation routes are closed;consequently,evacuees feel anxious and they cannot move as usual.This anxiety behavior has not been considered in previous related studies and simulations.In this study,a wide-area evacuation simulation is developed;this model can not only calculate the possibility of blocking escape routes when the city is broken but also provide safe and more realistic evacuation plans before a disaster occurs by incorporating into the simulation the risk avoidance behaviors of evacuees from road blockage,such as“the route re-seeking behavior”and“the shelter re-selecting behavior”.
文摘The prediction of the behavior of people in a disaster has a useful role to play in the design of urban structures such as department stores, schools, and office buildings. We focus on using emergency exit signs to effectively guide the evacuation of people on a floor with a dynamically changing layout. A multi-agent simulation is developed to simulate the behavior of evacuees on a floor. A mathematical model is constructed to obtain optimal sign locations to efficiently assist evacuation under the condition that obstacles are dynamically generated on the floor. The optimal sign locations are calculated by the mathematical model. Then, the developed simulation is performed to evaluate the effectiveness of the emergency exit signs and the behavior of evacuees on simple layout models using the calculated optimal sign locations.
基金funded by Ministry of Science and Technology of the People’s Republic of China and the Beijing Organizing Committee for the 2022 Olympic and Paralympic Winter Games[2021YFF0306005]China-Africa Cooperation Program on Emerging and Re-emerging Infectious Diseases Control[No.2020C400032]
文摘Taking the Chinese city of Xiamen as an example,simulation and quantitative analysis were performed on the transmissions of the Coronavirus Disease 2019(COVID-19)and the influence of intervention combinations to assist policymakers in the preparation of targeted response measures.A machine learning model was built to estimate the effectiveness of interventions and simulate transmission in different scenarios.The comparison was conducted between simulated and real cases in Xiamen.A web interface with adjustable parameters,including choice of intervention measures,intervention weights,vaccination,and viral variants,was designed for users to run the simulation.The total case number was set as the outcome.The cumulative number was 4,614,641 without restrictions and 78 under the strictest intervention set.Simulation with the parameters closest to the real situation of the Xiamen outbreak was performed to verify the accuracy and reliability of the model.The simulation model generated a duration of 52 days before the daily cases dropped to zero and the final cumulative case number of 200,which were 25 more days and 36 fewer cases than the real situation,respectively.Targeted interventions could benefit the prevention and control of COVID-19 outbreak while safeguarding public health and mitigating impacts on people’s livelihood.
文摘In multi-agent system, agents work together for solving complex tasks and reaching common goals. In this paper, we propose a cognitive model for multi-agent collaboration. Based on the cognitive model, an agent architecture will also be presented. This agent has BDI, awareness and policy driven mechanism concurrently. These approaches are integrated in one agent that will make multi-agent collaboration more practical in the real world.
基金supported by the National Social Science Foundation of China(Grant No.15BGL130)the Social Science Youth Foundation of Beijing Municipal(Grant No.15JGC148)+1 种基金the Education Ministry of China(Grant No.13YJCZH131)the China’s State Forestry Administration(Grant No.ZDWT-2014-17)
文摘Continuously growing populations and rapid economic development have led to the excessive use of forest resources,and the forest ecosystem is threatened.In response,forest ecological security(FES)has attracted attention.In this study,an integrated dynamic simulation model was constructed using the system dynamic method,and it was used to evaluate the FES in China from 1999 to 2014.A scenario analysis was then used to evaluate the changes in the FES under five forestry policy scenarios for the 2015–2050 period,including the baseline,afforestation policy,harvesting policies,management policy,investment policy,and a policy mix.The results showed that the evaluation values of the FES increased during the period from 1999 to 2002,the period from 2004 to 2010 and the year 2014,and they decreased in 2003 and during the period from 2011 to 2013.During the 2015–2050 simulation period,the FES improved continuously.In particular,China would enter a new stage when the economic systems,social systems and ecosystems were in harmony after 2040.To improve the FES and the current status of the FES,a scenario analysis showed the most suitable scenario to be Scenario 5 from 2015 to 2020 and Scenario 2 from 2021 to 2050.To relieve pressure,the most suitable scenario would be Scenario 5 from 2015 to 2040 and from 2046 to 2050,and the most suitable scenario would be Scenario 4 for 2041–2045.A policy mix(Scenario 5)would be most efficient under current conditions,while the effects of all the benefits of the forestry policies would weaken over the long term.The integrated method can be regarded as a decision support tool to help policy makers understand FES and promulgate a reasonable forestry policy.
基金The Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDA19040401National Key Research and Development Program,No.2016YFC0503506Programme of Bingwei Excellent Young Scientists of the Institute of Geographic Sciences and Natural Resources Research,CAS,No.2015RC202
文摘China is now experiencing rapid urbanization. Powerful tools are required to assess its urban spatial policies before implemented toward a more competitive and sustainable development paradigm. This study develops a Land Use Transport Interaction(LUTI) model to evaluate the impacts of urban land-use policies on urban spatial development. The model consists of four sub-models, i.e., transport, residential location, employment location and real estate rent sub-models. It is then applied to Beijing metropolitan area to forecast the urban activity evolution trend based on the land-use policies between 2009 and 2013. The modeling results show that more and more residents and enterprises in the city choose to agglomerate on outskirts, and new centers gradually emerge to share the services originally delivered by central Beijing. The general trend verifies the objectives of the government plan to develop more sub-centers around Beijing. The proposed activity-based model provides a distinct tool for the urban spatial policy makers in China. Further research is also discussed at the end.
基金supported by the Risk Management Agency Strategic Data Acquisition and Analysis Division Research Fund of United States Department of Agriculture (No.53-3151-2-00017)
文摘Computer simulation was used for predictive analysis of the effects of weather and soil type on crop yield in the U.S. crop insurance program. The Environmental Policy Integrated Climate （EPIC） model was modified to include hail weather events, which completed the modifications necessary to simulate the four most frequent causes of crop yield loss （hail, excessive wet, excessive cold, and excessive dry） associated with soil type in Kansas, USA. At the region level, per hectare yields were simulated for corn, wheat, soybean, and sorghum. We concluded that it was possible to predict crop yields through computer simulation with greater than 93% accuracy. The hail damage model test indicated EPIC could predict hail-soil-induced yield losses reasonably well （R^2 〉 0.6）. The investigation of soil type influence on dryland sorghum and wheat production indicated that Wymore silty clay loam soil and Kenorna silt loam produced the highest sorghum yields statistically; Kuma silt loam, Roxbury silt loam, Crete silty clay loam, and Woodson silt soils produced the second highest sorghum yields statistically; and Richfiled silt loam, Wells loam, and Canadian sandy loam produced the lowest sorghum yields. By contrast, wheat production showed less sensitivity to soil type variation. The less sensitive response of wheat yields to the soil type could be largely due to the unconsidered small-scale variability of soil features.
文摘People power is the fundamental concept of democracy and power of the people is exercised though voting. People decide who should be elected to make decisions for them. However, if people do not properly participate in the voting process and only two-thirds of all eligible voters participate in an election, the democratic institution loses its credibility and becomes vulnerable. This paper investigates various changes in voting institutions throughout the USAwith a simulation model that analyzes the efficacy of such methods to attain higher voter turnout.
文摘This study tries to develop and use a small macroeconometric model to capture the main short-term macro dynamics and to forecast major macroeconomic variables of the Malawian economy. The results show that a reduction in the policy rate leads to a fall in the lending rate, but with an increase in money supply, and with an insignificant impact on output growth. The results suggest that monetary authorities in Malawi have to make a choice between the objectives of maintaining lower money supply and lowering the lending rate. The results also suggest that, despite the Reserve Bank of Malawi Act of 1989 stipulating that monetary authorities should pursue both price and high growth and employment objectives, our results reveal that price stability is the principal objective of monetary policy in the country. Suggesting that monetary authorities in the country should not only place more emphasis on the objective of stabilization and achieving low inflation, but also focus on supporting strong, sustained and shared growth. To some extent further suggesting that emphasis should be placed on policies and strategies aimed at structurally transforming the Malawian economy so that the monetary policies’ impact should translate into an increase in the country’s output and growth. Further suggesting enhanced effective coordination between fiscal and monetary policies.
文摘One of the main objectives of artificial intelligence lies in the simulation of the behavior of living organisms;emotions are a fundamental part of life, and they cannot be left aside when simulating behavior. In this research, software is developed that simulates the behavior of birds with different characteristics. The latter interacts by considering different stimuli from the environment (external), and the internal state of the subject (objectives). To achieve this, a model of birds in the role of prey and predators is developed that focuses on the study of the interaction between these organisms that exhibit specific behaviors in their environment. This project is a seminal work that aims to represent the emotions of birds, and the latter caused by stimuli from a dynamic environment.
基金supported by National Key Technology R&D Program of China(Project No.2009BAH48B03)
文摘To acquire a competitive advantage in the expanding market,manufacturing enterprises should be able to manage their supply chains as effectively as possible.It is now becoming popular to model supply chains as multi-agent systems and use discrete event simulation to learn more about their behaviors or investigate the implications of alternative configurations.In order to enhance the computational efficiency and keep the simulation credibility,this paper proposes a message-driving formalism for the simulation of multi-agent supply chain systems.Through the message-driving formalism,the problem of shared variables is addressed and the parallel operation of agents is implemented.Simulation experiments with a prototype implementation show that the message-driving formalism is able to provide credible results in significantly less simulation time.
基金the European Research Council,ERC grant agreement number 101044703(EUNICE)CUP D87G22000340006.European Union PNRR-Missione 4-Componente 2-Avviso 341 del 15/03/2022-Next Generation EU,in the framework of the project GRINS-Grow-ing Resilient,INclusive and Sustainable project(GRINS PE00000018-CUP C83C22000890001)European Union’s Horizon Europe programme under the Marie Skłodowska-Curie grant agreement number 101148367.
文摘Electricity systems are key to transforming today’s society into a carbon-free economy.Long-term electricity market mechanisms,including auctions,support schemes,and other policy instruments,are critical in shaping the electricity generation mix.In light of the need for more advanced tools to support policymakers and other stakeholders in designing,testing,and evaluating long-term markets,this work presents a multi-agent reinforcement learning model capable of capturing the key features of decarbonizing energy systems.Profitmaximizing generation companies make investment decisions in the wholesale electricity market,responding to system needs,competitive dynamics,and policy signals.The model employs independent proximal policy optimization,which was selected for suitability to the decentralized and competitive environment.Nevertheless,given the inherent challenges of independent learning in multi-agent settings,an extensive hyperparameter search ensures that decentralized training yields market outcomes consistent with competitive behavior.The model is applied to a stylized version of the Italian electricity system and tested under varying levels of competition,market designs,and policy scenarios.Results highlight the critical role of market design for decarbonizing the electricity sector and avoiding price volatility.The proposed framework allows assessing long-term electricity markets in which multiple policy and market mechanisms interact simultaneously,with market participants responding and adapting to decarbonization pathways.
基金supported by China Post-Doctoral Science Foundation under Grant No.2017M620940.
文摘Since 2010,Chinese government has introduced a series of administrative policies to limit speculation in the housing market to stabilize price fluctuations and keep the housing market in a healthy state of development.In order to investigate whether administrative policy can play its due role,this paper constructs a comprehensive bottom-up housing market heterogeneous households multiagent model(HHMAM)to undertake research on the differentiated effect of administrative policy in different cities.The empirical studies find that:1)Administrative policy that increases interest rates will cause housing prices to continue to decline in the long term,but they will resume a rising trend after reaching the lowest point;2)If the government cancels a property-purchasing limitation,housing prices will continue to rise;and 3)investors tend to invest in 1st-tier cities due to the high demand and greater likelihood of appreciation in these cities.
基金sponsored by the National Social Sciences Foundation Program,An Evaluation of the Impact of China’s Family Planning Policy Adjustment on the Sustainability of the Social Security Fund and A Study of the Relevant Countermeasures(Grant No.15XRK005,chaired by:Zeng Yi)
文摘Based on the reality that 29 Chinese provinces have already implemented the policy allowing a couple to raise a second child if either parent is an only child, this paper provides an empirical study on the effect of this policy on the financial status of the social pooling fund of basic pension insurance for urban employees. Our study suggests the followings. First, under the previous unchanged family planning policy, current deficits and cumulative deficits will occur in the social pooling fund in the year 2047 and 2063 respectively. Second, if lO% to 50% of qualified couples choose to raise a second child, the financial status of the social pooling fund will improve; relative to the previous unchanged family planning policy, the contribution ratio can decrease from 20% to the range between 18.06% and 19.57% without causing any changes to the original financial status of income and expenditure. Third, if the percentage of couples choosing to raise a second child rises to 60% to 100%, the contribution ratio can even decrease to the range between 16.55% and 17. 7% without causing any changes to the financial status as under the previous unchanged family planning policy. The above conclusions have all passed the sensitivity test. Therefore, the ＂two-child policy＂ for qualified couples is favorable to alleviating the payment pressures of pension insurance but the policy effectiveness is subject to fertility desire and the intensity of government implementation.
