As mining activities expand deeper,deep high-temperature formations seriously threaten the future safe exploitation,while deep geothermal energy has great potential for development.Combining the formation cooling and ...As mining activities expand deeper,deep high-temperature formations seriously threaten the future safe exploitation,while deep geothermal energy has great potential for development.Combining the formation cooling and geothermal mining in mines to establish a thermos-hydraulic coupling numerical model for fractured formation.The study investigates the formation heat transfer behaviour,heat recovery performance and thermal economic benefits influenced during the life cycle.The results show that the accumulation of cold energy during the cold storage phase induces a decline in formation temperature.The heat recovery phase is determined by the extent of the initial cold domain,which contracts inward from the edge and decelerates the heat recovery rate gradually.With groundwater velocity increases,the thermal regulation efficiency gradually increases,the production temperature decreases,while the effective radius and thermal power increase first and then decrease.The injected volume and temperature significantly affect,with higher injection temperatures slowing thermal recovery,and the thermal regulation efficiency is more sensitive to changes in formation permeability and thermal conductivity.The heat extraction performance is positively correlated with all factors.The levelized cost of electricity is estimated at 0.1203$/(kW·h)during the cold storage.During the heat recovery,annual profit is primarily driven by cooling benefits.展开更多
In view of the high complexity of the objective world, an economic dependence between subsystems(paired and unpaired) is proposed, and then the maintenance cost and time under different economic dependences are formul...In view of the high complexity of the objective world, an economic dependence between subsystems(paired and unpaired) is proposed, and then the maintenance cost and time under different economic dependences are formulated in a simple and consistent manner. Selective maintenance problem under economic dependence(EDSMP) is presented based on a series–parallel system in this paper. A case study shows that the system reliability is promoted to a certain extent, which can validate the validity of the EDSMP model. The influence of the ratio of set-up cost on system performance is mainly discussed under different economic dependences. Several existing improvements of classical exhaust algorithm are further modified to solve a large sized EDSMP rapidly. Experimental results illustrate that these improvements can reduce CPU time significantly.Furthermore the contribution of each improvement is defined here, and then their contributions are compared thoroughly.展开更多
Effective source-load prediction and reasonable dispatching are crucial to realize the economic and reliable operations of integrated energy systems(IESs).They can overcome the challenges introduced by the uncertainti...Effective source-load prediction and reasonable dispatching are crucial to realize the economic and reliable operations of integrated energy systems(IESs).They can overcome the challenges introduced by the uncertainties of new energies and various types of loads in the IES.Accordingly,a robust optimal dispatching method for the IES based on a robust economic model predictive control(REMPC)strategy considering source-load power interval prediction is proposed.First,an operation model of the IES is established,and an interval prediction model based on the bidirectional long short-term memory network optimized by beetle antenna search and bootstrap is formulated and applied to predict the photovoltaic power and the cooling,heating,and electrical loads.Then,an optimal dispatching scheme based on REMPC is devised for the IES.The source-load interval prediction results are used to improve the robustness of the REPMC and reduce the influence of source-load uncertainties on dispatching.An actual IES case is selected to conduct simulations;the results show that compared with other prediction techniques,the proposed method has higher prediction interval coverage probability and prediction interval normalized averaged width.Moreover,the operational cost of the IES is decreased by the REMPC strategy.With the devised dispatching scheme,the ability of the IES to handle the dispatching risk caused by prediction errors is enhanced.Improved dispatching robustness and operational economy are also achieved.展开更多
This paper presents a modified sliding mode control for fractional-order chaotic economical systems with parameter uncertainty and external disturbance. By constructing the suitable sliding mode surface with fractiona...This paper presents a modified sliding mode control for fractional-order chaotic economical systems with parameter uncertainty and external disturbance. By constructing the suitable sliding mode surface with fractional-order integral, the effective sliding mode controller is designed to realize the asymptotical stability of fractional-order chaotic economical systems. Comparing with the existing results, the main results in this paper are more practical and rigorous. Simulation results show the effectiveness and feasibility of the proposed sliding mode control method.展开更多
Forest ecosystem services contribute to human welfare, both directly and indirectly. Here the economic value of water conservation by Bazoft basin located in Zagros forests in western Iran was estimated, using simulat...Forest ecosystem services contribute to human welfare, both directly and indirectly. Here the economic value of water conservation by Bazoft basin located in Zagros forests in western Iran was estimated, using simulation models and Geographic Information System （GIS） as a tool for analyzing the effects of ecological factors on ecosystem services. Rainfall-runoff simulation was carried out by using Curve Number （CN） method in HEC-HMS model. The model requires the inputs of land cover, soil and short term rainfall and discharge data. The efficiency of simu-lated model was revised using observed data and doing calibration stages. The role of forest on water retention and surface runoff reduction by devising four hypothetical scenarios and then the effects of land use changes associated with these scenarios on rainfall-runoff behavior of the region were determined. The results show that under the case of scenario one which assumes that the entire of basin area is covered by forests, total outflow would be in the minimum amount and rainfall initial loss will increase. Forest hydrological services related to water retention was economically assessed using Replacement Cost Method. Valuation results show that each hectare of Bazoft forests can store 84.8 m3 water with 0.5 US$/m3 annual value. So the water retention value of each hectare of these forests will be 43US$. This could have positive economic consequences for the region and would help decision-makers in selecting appropriate and economically feasible development strategies.展开更多
This paper presents a finite-time economic model predictive control(MPC)algorithm that can be used for frequency regulation and optimal load dispatch in multi-area power systems.Economic MPC can be used in a power sys...This paper presents a finite-time economic model predictive control(MPC)algorithm that can be used for frequency regulation and optimal load dispatch in multi-area power systems.Economic MPC can be used in a power system to ensure frequency stability,real-time economic optimization,control of the system and optimal load dispatch from it.A generalized terminal penalty term was used,and the finite-time convergence of the system was guaranteed.The effectiveness of the proposed model predictive control algorithm was verified by simulating a power system,which had two areas connected by an AC tie line.The simulation results demonstrated the effectiveness of the algorithm.展开更多
This study aims to analysis the influence of economic growth(EG)and energy consumption(EC)on sulfur dioxide emissions(SE)in China.Accordingly,this study explores the link between EG,EC,and SE for 30 provinces in China...This study aims to analysis the influence of economic growth(EG)and energy consumption(EC)on sulfur dioxide emissions(SE)in China.Accordingly,this study explores the link between EG,EC,and SE for 30 provinces in China over the span of 2000-2019.This study also analyzes cross-sectional dependence tests,panel unit root tests,Westerlund panel cointegration tests,Dumitrescu-Hurlin(D-H)causality tests.According to the test results,there is an inverted U-shaped association between EG and SE,and the assumption of the Environmental Kuznets Curve(EKC)is verified.The signs of EG and EC in the fixed effect(FE)and random effect(RE)methods are in line with those in the dynamic ordinary least squares(DOLS),fully modified ordinary least squares(FMOLS)and autoregressive distributed lag(ARDL)estimators.Moreover,the results verified that EC can obviously positive impact the SE.To reduce SE in China,government and policymakers can improve air quality by developing cleaner energy sources and improving energy efficiency.This requires the comprehensive use of policies,regulations,economic incentives,and public participation to promote sustainable development.展开更多
Developing a green economy is key to achieving the 2030 Sustainable Development Goals. This paper uses the SBM-GML index, which includes non-desired outputs, to measure the trend of regional green economic efficiency ...Developing a green economy is key to achieving the 2030 Sustainable Development Goals. This paper uses the SBM-GML index, which includes non-desired outputs, to measure the trend of regional green economic efficiency changes and analyze the impact mechanism and realization path of industrial transformation on green economic efficiency. The research results show that advanced industrial structure has a positive influence on green economic efficiency nationwide, while energy utilization structure and energy utilization efficiency have positive partial intermediary effects in the influence path;industrial structure rationalization is also significantly positively related to green economic efficiency nationwide, and the mediating effect of energy utilization is positive. The impact of industrial transformation on green economic efficiency has regional heterogeneity, and the mediating effect of energy use also differs. Among them, the impact effect in the eastern region is basically consistent with the national sample, but is negative in the central and western regions. This paper proposes countermeasures in terms of adjusting the industrial structure, improving energy efficiency, and perfecting industrial and energy policies, which can provide theoretical and practical references for promoting the transformation and upgrading of regional industrial structure, optimizing energy utilization, and advancing the efficiency of the national and regional green economy.展开更多
The emerging virtual coupling technology aims to operate multiple train units in a Virtually Coupled Train Set(VCTS)at a minimal but safe distance.To guarantee collision avoidance,the safety distance should be calcula...The emerging virtual coupling technology aims to operate multiple train units in a Virtually Coupled Train Set(VCTS)at a minimal but safe distance.To guarantee collision avoidance,the safety distance should be calculated using the state-of-the-art space-time separation principle that separates the Emergency Braking(EB)trajectories of two successive units during the whole EB process.In this case,the minimal safety distance is usually numerically calculated without an analytic formulation.Thus,the constrained VCTS control problem is hard to address with space-time separation,which is still a gap in the existing literature.To solve this problem,we propose a Distributed Economic Model Predictive Control(DEMPC)approach with computation efficiency and theoretical guarantee.Specifically,to alleviate the computation burden,we transform implicit safety constraints into explicitly linear ones,such that the optimal control problem in DEMPC is a quadratic programming problem that can be solved efficiently.For theoretical analysis,sufficient conditions are derived to guarantee the recursive feasibility and stability of DEMPC,employing compatibility constraints,tube techniques and terminal ingredient tuning.Moreover,we extend our approach with globally optimal and distributed online EB configuration methods to shorten the minimal distance among VCTS.Finally,experimental results demonstrate the performance and advantages of the proposed approaches.展开更多
In 2000 and 2001, 1-year-old seedlings of 7 economic tree species including chestnut, apricot, persimmon, peach, walnut, pear and apple were cultured in garden pots that had a diameter of 40 cm and were filled with cl...In 2000 and 2001, 1-year-old seedlings of 7 economic tree species including chestnut, apricot, persimmon, peach, walnut, pear and apple were cultured in garden pots that had a diameter of 40 cm and were filled with clean sand. The major components of exudates released from their roots were isolated and analysed by GC-MS. Totally 200 kinds of organic chemicals were isolated, of which 3 kinds i.e. naphthalene, dimethylbenzene and dibutyl phthalate were principally controlled pollutants according to 'Blacklist of Principal Environment Pollutants in China' and the standard of U.S. Environmental Protection Agency (EPA). The research result provided theoretical evidence for selecting low-pollution economic forest crops in the water source protection area in Miyun Reservoir.展开更多
The integration of linguistics and economics, economics of language, is a new peripheral subject based on theory of west ern human capital and educational economics. Catchwords which reflect many theories of economics...The integration of linguistics and economics, economics of language, is a new peripheral subject based on theory of west ern human capital and educational economics. Catchwords which reflect many theories of economics of language enter into people's scope of research. Study of catchword is of great significance for the enrichment of research of human language.展开更多
From the perspective of Language Economics,language education(including second language or foreign language education)is an economically valuable investment that has the function of promoting social development.Howeve...From the perspective of Language Economics,language education(including second language or foreign language education)is an economically valuable investment that has the function of promoting social development.However,there is an imbalance in the input and output of China’s college English education.From the perspective of language economics,this article focuses on the reform of College English courses in order to improve the efficiency of English teaching in common universities.展开更多
以国际权威期刊《Forest Policy and Economics》为例,选取其2007—2017年刊发的与中国林业经济问题相关的文献,从国际视角对中国林业经济问题进行梳理与总结。基于统计分析,刊发的文献总体呈现数量波动增长、内容多样化、合作形式国际...以国际权威期刊《Forest Policy and Economics》为例,选取其2007—2017年刊发的与中国林业经济问题相关的文献,从国际视角对中国林业经济问题进行梳理与总结。基于统计分析,刊发的文献总体呈现数量波动增长、内容多样化、合作形式国际化,研究区域具体化,定量分析为主等特点。从林产品贸易、森林资源经营管理、森林转型等主题展开对中国林业经济研究的论述,以期为我国相关学者全面把握中国林业经济前沿研究进展和发展趋势提供参考与借鉴。展开更多
Coal and gas are two important resources in China,and it is an effective way to recycle them with the method of co-extraction of coal and gas.In view of actual situation of China's co-extraction of coal and gas,th...Coal and gas are two important resources in China,and it is an effective way to recycle them with the method of co-extraction of coal and gas.In view of actual situation of China's co-extraction of coal and gas,this research adopts the science evaluation of gas extraction of coal by the method of quantitative evaluation,and preliminarily establishes the technical evaluation system of co-extraction of coal and gas.Technical evaluation system of co-extraction of coal and gas includes safety evaluation,economic evaluation and resource recovery evaluation in the process of mining coal and gas.In addition,this paper results in the selected evaluation parameters and target functions that are used in the three evaluation methods.The establishment of evaluation system for co-extraction of coal and gas plays an important theoretical significance and guiding role in co-extraction of coal and gas for China's coal enterprises.展开更多
Because forecasting a development program during the target selection phase of exploration for coalbed methane （CBM） is impossible, the conventional method that relies on a conceptual （or detailed） development pro...Because forecasting a development program during the target selection phase of exploration for coalbed methane （CBM） is impossible, the conventional method that relies on a conceptual （or detailed） development pro- gram cannot be used during the economic evaluation of CBM resources. Hence, this study focuses on establishing an economic evaluation model based on the characteristics of the target selection phase. The discounted cashflow method is applied to the construction of the model with the assumption that there is a uniform distribution of produc- tion wells. The computational error generated by the assumption is corrected by introducing a correction factor based on the production profile of single CBM wells. The case study demonstrates that the blocks lacking economic value can be screened out, and the most advantageous targets can be found by computing the resource values in the best- and worst-case scenarios. This technique can help to reduce wasted investments and improve the quality of decision-making in selecting targets for exploration.展开更多
This study aims to investigate the influence of rapid economic development on pollution at the municipal level in China.It constructs a Stochastic Impacts by Regression on Population,Affluence and Technology model(STI...This study aims to investigate the influence of rapid economic development on pollution at the municipal level in China.It constructs a Stochastic Impacts by Regression on Population,Affluence and Technology model(STIRPAT model) and uses comprehensive municipal data on industrial pollution and economic performance.The dataset contains 290 cities from2003 to 2016 as a sample for the panel data analysis.The study further separates the cities into two groups by their levels of economic development for heterogeneity analysis.It reveals that a low level of economic development would aggravate environmental pollution,and when the economy reaches a high level,this economic development will improve environmental quality.We also find that the relationships between foreign direct investment and industrial dust and sulfur dioxide(SO_2) discharge are significant,while the relationship between economic growth and effluent emission is not.The more developed subsample cities present an inverted U-shaped curve between industrial pollutant emission,GDP per capita,and foreign direct investment,while the less developed subsamples show no such relationship.Since the shape of these curves differs among regions,their turning points vary accordingly.Based on this finding,this study suggests that the governments of more developed cities should balance environmental pollution and economic development by enhancing environmental regulations and adjusting industrial structure.展开更多
To better promote forest resource management and strengthen the development of forest carbon sink marketization, this paper studied the accounting of forest carbon sinks from 2003 to 2008 based on a system of national...To better promote forest resource management and strengthen the development of forest carbon sink marketization, this paper studied the accounting of forest carbon sinks from 2003 to 2008 based on a system of national accounts （SNA） and data from the latest forest resources inventory in China. The study calculated the value of forest carbon stocks at a total of RMB 817.13 × 10^9 yuan in 2003 and RMB 839.93×10^9 yuan in 2008, with an average annual increase of 0.55 % from an increase in physical carbon sinks. The total value of forest carbon sinks in 2003 and 2008 was RMB 26.73×10^9 yuan and RMB 29.77×10^9 yuan, respectively, with an average annual growth of 2.18 %. From 2003 to 2008, both stock and flow value of forest carbon sinks increased, but the total net flow value of carbon sinks decreased. The growth rate for the environmentally adjusted Gross Domestic Product （eaGDP） for China＇s forest carbon sinks was 17.23 %, outstripping the average growth rate of 9.5 % for the GDP during the same period. The study alsoindicates that China＇s forest carbon sinks affects the GDP in the range of 0.25-0.26 %, and its economic potential is not relatively huge.展开更多
Solar PV is expected to become the most cost-competitive renewable energy owing to the rapidly decreasing cost of the system. On the other hand, hydropower is a high-quality and reliable regulating power source that c...Solar PV is expected to become the most cost-competitive renewable energy owing to the rapidly decreasing cost of the system. On the other hand, hydropower is a high-quality and reliable regulating power source that can be bundled with solar PV to improve the economic feasibility of long-distance transmitted power. In this paper, a quantification model is established taking into account the regulating capacity of the reservoir, the characteristics of solar generation, and cost of hydro and solar PV with long-distance transmission based on the installed capacity ratio of hydro–solar hybrid power. Results indicate that for hydropower stations with high regulating capacity and generation factor of approximately 0.5, a hydro–solar installed capacity ratio of 1:1 will yield overall optimal economic performance, whereas for hydropower stations with daily regulating capacity reservoir and capacity factor of approximately 0.65, the optimal hydro–solar installed capacity ratio is approximately 1:0.3. In addition, the accuracy of the approach used in this study is verified through operation simulation of a hydro–solar hybrid system including ultra high-voltage direct current(UHVDC) transmission using two case studies in Africa.展开更多
Power transmission across the sea is an important part of global energy interconnection(GEI).To support the construction of GEI and to serve the needs of future clean energy trans-sea transportation and offshore wind ...Power transmission across the sea is an important part of global energy interconnection(GEI).To support the construction of GEI and to serve the needs of future clean energy trans-sea transportation and offshore wind power development,this study a)analyzes the requirements of the GEI backbone network pertaining to direct current(DC)submarine cable technology,and b)defines the key technical and economic indices of ultrahigh-voltage direct current(UHVDC)submarine cable based on theoretical computations.The research is based on the thermoelectric coupling model and the finite element method.It is shown that the dielectric strength of the insulating materials of the±800 kV~±1100 kV/4000 MW^12000 MW UHVDC submarine cable(extrusion insulation)should be not less than 43~65 kV/mm,while the heat resistance is not less than 110°C.As the cost of submarine cable is 5~10 times higher than that of the overhead line,the project investment need to be decreased to a level within the economical carrying capacity to guarantee extensive applicability of the HVDC submarine cable technology.展开更多
This study was performed in five villages of Sandwip Upazila, Chittagong district with a view to identify the tree resources, utilization pattern and economic return of major fruit and timber tree species. Information...This study was performed in five villages of Sandwip Upazila, Chittagong district with a view to identify the tree resources, utilization pattern and economic return of major fruit and timber tree species. Information collected from a total of 60 households ranging from marginal, small, medium and large categories. Number of plant species increased with the increase of homestead area. A total of 33 plant species were recorded from the homegarden, of which 19 were fruit and 14 were timber tree species. Considerable number of vegetables was also planted under the shade of the homestead trees. The investment analysis showed that average benefit-cost ratios were greater than one, net present values were positive and internal rate of returns were more than 10%. Long term investment on horticulture and timber tree species is highly profitable if species like Artocarpus heterophyllus, Cocos nucifera, Tectona grandis and Swietenia macrophylla are planted.展开更多
基金financial support from the National Natural Science Foundation of China(Nos.52434006,52374151,and 51927808)。
文摘As mining activities expand deeper,deep high-temperature formations seriously threaten the future safe exploitation,while deep geothermal energy has great potential for development.Combining the formation cooling and geothermal mining in mines to establish a thermos-hydraulic coupling numerical model for fractured formation.The study investigates the formation heat transfer behaviour,heat recovery performance and thermal economic benefits influenced during the life cycle.The results show that the accumulation of cold energy during the cold storage phase induces a decline in formation temperature.The heat recovery phase is determined by the extent of the initial cold domain,which contracts inward from the edge and decelerates the heat recovery rate gradually.With groundwater velocity increases,the thermal regulation efficiency gradually increases,the production temperature decreases,while the effective radius and thermal power increase first and then decrease.The injected volume and temperature significantly affect,with higher injection temperatures slowing thermal recovery,and the thermal regulation efficiency is more sensitive to changes in formation permeability and thermal conductivity.The heat extraction performance is positively correlated with all factors.The levelized cost of electricity is estimated at 0.1203$/(kW·h)during the cold storage.During the heat recovery,annual profit is primarily driven by cooling benefits.
基金supported by the National Science Foundation of China (Grant No. 61305083)
文摘In view of the high complexity of the objective world, an economic dependence between subsystems(paired and unpaired) is proposed, and then the maintenance cost and time under different economic dependences are formulated in a simple and consistent manner. Selective maintenance problem under economic dependence(EDSMP) is presented based on a series–parallel system in this paper. A case study shows that the system reliability is promoted to a certain extent, which can validate the validity of the EDSMP model. The influence of the ratio of set-up cost on system performance is mainly discussed under different economic dependences. Several existing improvements of classical exhaust algorithm are further modified to solve a large sized EDSMP rapidly. Experimental results illustrate that these improvements can reduce CPU time significantly.Furthermore the contribution of each improvement is defined here, and then their contributions are compared thoroughly.
基金supported by the National Key Research and Development Project of China(2018YFE0122200).
文摘Effective source-load prediction and reasonable dispatching are crucial to realize the economic and reliable operations of integrated energy systems(IESs).They can overcome the challenges introduced by the uncertainties of new energies and various types of loads in the IES.Accordingly,a robust optimal dispatching method for the IES based on a robust economic model predictive control(REMPC)strategy considering source-load power interval prediction is proposed.First,an operation model of the IES is established,and an interval prediction model based on the bidirectional long short-term memory network optimized by beetle antenna search and bootstrap is formulated and applied to predict the photovoltaic power and the cooling,heating,and electrical loads.Then,an optimal dispatching scheme based on REMPC is devised for the IES.The source-load interval prediction results are used to improve the robustness of the REPMC and reduce the influence of source-load uncertainties on dispatching.An actual IES case is selected to conduct simulations;the results show that compared with other prediction techniques,the proposed method has higher prediction interval coverage probability and prediction interval normalized averaged width.Moreover,the operational cost of the IES is decreased by the REMPC strategy.With the devised dispatching scheme,the ability of the IES to handle the dispatching risk caused by prediction errors is enhanced.Improved dispatching robustness and operational economy are also achieved.
基金supported by the National Natural Science Foundation of China(Grant Nos.51207173 and 51277192)
文摘This paper presents a modified sliding mode control for fractional-order chaotic economical systems with parameter uncertainty and external disturbance. By constructing the suitable sliding mode surface with fractional-order integral, the effective sliding mode controller is designed to realize the asymptotical stability of fractional-order chaotic economical systems. Comparing with the existing results, the main results in this paper are more practical and rigorous. Simulation results show the effectiveness and feasibility of the proposed sliding mode control method.
文摘Forest ecosystem services contribute to human welfare, both directly and indirectly. Here the economic value of water conservation by Bazoft basin located in Zagros forests in western Iran was estimated, using simulation models and Geographic Information System （GIS） as a tool for analyzing the effects of ecological factors on ecosystem services. Rainfall-runoff simulation was carried out by using Curve Number （CN） method in HEC-HMS model. The model requires the inputs of land cover, soil and short term rainfall and discharge data. The efficiency of simu-lated model was revised using observed data and doing calibration stages. The role of forest on water retention and surface runoff reduction by devising four hypothetical scenarios and then the effects of land use changes associated with these scenarios on rainfall-runoff behavior of the region were determined. The results show that under the case of scenario one which assumes that the entire of basin area is covered by forests, total outflow would be in the minimum amount and rainfall initial loss will increase. Forest hydrological services related to water retention was economically assessed using Replacement Cost Method. Valuation results show that each hectare of Bazoft forests can store 84.8 m3 water with 0.5 US$/m3 annual value. So the water retention value of each hectare of these forests will be 43US$. This could have positive economic consequences for the region and would help decision-makers in selecting appropriate and economically feasible development strategies.
基金supported by the National Natural Science Foundation of China(Grant 62103101)the Natural Science Foundation of Jiangsu Province of China(Grant BK20210217)+5 种基金the China Postdoctoral Science Foundation(Grant 2022M710680)the National Natural Science Foundation of China(Grant 62273094)the"Zhishan"Scholars Programs of Southeast Universitythe Fundamental Science(Natural Science)General Program of Jiangsu Higher Education Institutions(No.21KJB470020)the Open Research Fund of Jiangsu Collaborative Innovation Center for Smart Distribution Network,Nanjing Institute of Technology(No.XTCX202102)the Introduced Talents Scientific Research Start-up Fund Project,Nanjing Institute of Technology(No.YKJ202133).
文摘This paper presents a finite-time economic model predictive control(MPC)algorithm that can be used for frequency regulation and optimal load dispatch in multi-area power systems.Economic MPC can be used in a power system to ensure frequency stability,real-time economic optimization,control of the system and optimal load dispatch from it.A generalized terminal penalty term was used,and the finite-time convergence of the system was guaranteed.The effectiveness of the proposed model predictive control algorithm was verified by simulating a power system,which had two areas connected by an AC tie line.The simulation results demonstrated the effectiveness of the algorithm.
文摘This study aims to analysis the influence of economic growth(EG)and energy consumption(EC)on sulfur dioxide emissions(SE)in China.Accordingly,this study explores the link between EG,EC,and SE for 30 provinces in China over the span of 2000-2019.This study also analyzes cross-sectional dependence tests,panel unit root tests,Westerlund panel cointegration tests,Dumitrescu-Hurlin(D-H)causality tests.According to the test results,there is an inverted U-shaped association between EG and SE,and the assumption of the Environmental Kuznets Curve(EKC)is verified.The signs of EG and EC in the fixed effect(FE)and random effect(RE)methods are in line with those in the dynamic ordinary least squares(DOLS),fully modified ordinary least squares(FMOLS)and autoregressive distributed lag(ARDL)estimators.Moreover,the results verified that EC can obviously positive impact the SE.To reduce SE in China,government and policymakers can improve air quality by developing cleaner energy sources and improving energy efficiency.This requires the comprehensive use of policies,regulations,economic incentives,and public participation to promote sustainable development.
基金supported by National Natural Science Foundation of China [grant numbers 42371194]。
文摘Developing a green economy is key to achieving the 2030 Sustainable Development Goals. This paper uses the SBM-GML index, which includes non-desired outputs, to measure the trend of regional green economic efficiency changes and analyze the impact mechanism and realization path of industrial transformation on green economic efficiency. The research results show that advanced industrial structure has a positive influence on green economic efficiency nationwide, while energy utilization structure and energy utilization efficiency have positive partial intermediary effects in the influence path;industrial structure rationalization is also significantly positively related to green economic efficiency nationwide, and the mediating effect of energy utilization is positive. The impact of industrial transformation on green economic efficiency has regional heterogeneity, and the mediating effect of energy use also differs. Among them, the impact effect in the eastern region is basically consistent with the national sample, but is negative in the central and western regions. This paper proposes countermeasures in terms of adjusting the industrial structure, improving energy efficiency, and perfecting industrial and energy policies, which can provide theoretical and practical references for promoting the transformation and upgrading of regional industrial structure, optimizing energy utilization, and advancing the efficiency of the national and regional green economy.
基金supported by the National Natural Science Foundation of China(52372310)the State Key Laboratory of Advanced Rail Autonomous Operation(RAO2023ZZ001)+1 种基金the Fundamental Research Funds for the Central Universities(2022JBQY001)Beijing Laboratory of Urban Rail Transit.
文摘The emerging virtual coupling technology aims to operate multiple train units in a Virtually Coupled Train Set(VCTS)at a minimal but safe distance.To guarantee collision avoidance,the safety distance should be calculated using the state-of-the-art space-time separation principle that separates the Emergency Braking(EB)trajectories of two successive units during the whole EB process.In this case,the minimal safety distance is usually numerically calculated without an analytic formulation.Thus,the constrained VCTS control problem is hard to address with space-time separation,which is still a gap in the existing literature.To solve this problem,we propose a Distributed Economic Model Predictive Control(DEMPC)approach with computation efficiency and theoretical guarantee.Specifically,to alleviate the computation burden,we transform implicit safety constraints into explicitly linear ones,such that the optimal control problem in DEMPC is a quadratic programming problem that can be solved efficiently.For theoretical analysis,sufficient conditions are derived to guarantee the recursive feasibility and stability of DEMPC,employing compatibility constraints,tube techniques and terminal ingredient tuning.Moreover,we extend our approach with globally optimal and distributed online EB configuration methods to shorten the minimal distance among VCTS.Finally,experimental results demonstrate the performance and advantages of the proposed approaches.
基金The study was supported by Natural Science Foundation of Beijing to Wang Yuzhu (No. 6992013).
文摘In 2000 and 2001, 1-year-old seedlings of 7 economic tree species including chestnut, apricot, persimmon, peach, walnut, pear and apple were cultured in garden pots that had a diameter of 40 cm and were filled with clean sand. The major components of exudates released from their roots were isolated and analysed by GC-MS. Totally 200 kinds of organic chemicals were isolated, of which 3 kinds i.e. naphthalene, dimethylbenzene and dibutyl phthalate were principally controlled pollutants according to 'Blacklist of Principal Environment Pollutants in China' and the standard of U.S. Environmental Protection Agency (EPA). The research result provided theoretical evidence for selecting low-pollution economic forest crops in the water source protection area in Miyun Reservoir.
文摘The integration of linguistics and economics, economics of language, is a new peripheral subject based on theory of west ern human capital and educational economics. Catchwords which reflect many theories of economics of language enter into people's scope of research. Study of catchword is of great significance for the enrichment of research of human language.
文摘From the perspective of Language Economics,language education(including second language or foreign language education)is an economically valuable investment that has the function of promoting social development.However,there is an imbalance in the input and output of China’s college English education.From the perspective of language economics,this article focuses on the reform of College English courses in order to improve the efficiency of English teaching in common universities.
文摘以国际权威期刊《Forest Policy and Economics》为例,选取其2007—2017年刊发的与中国林业经济问题相关的文献,从国际视角对中国林业经济问题进行梳理与总结。基于统计分析,刊发的文献总体呈现数量波动增长、内容多样化、合作形式国际化,研究区域具体化,定量分析为主等特点。从林产品贸易、森林资源经营管理、森林转型等主题展开对中国林业经济研究的论述,以期为我国相关学者全面把握中国林业经济前沿研究进展和发展趋势提供参考与借鉴。
基金supported by the State Key Basic Research Program of China(No.2011CB201206)the Major Projectof the National Science and Technology of China(No.2011ZX05040-005)the National Natural Science Foundation of Youth Science Foundation(No.50904033)
文摘Coal and gas are two important resources in China,and it is an effective way to recycle them with the method of co-extraction of coal and gas.In view of actual situation of China's co-extraction of coal and gas,this research adopts the science evaluation of gas extraction of coal by the method of quantitative evaluation,and preliminarily establishes the technical evaluation system of co-extraction of coal and gas.Technical evaluation system of co-extraction of coal and gas includes safety evaluation,economic evaluation and resource recovery evaluation in the process of mining coal and gas.In addition,this paper results in the selected evaluation parameters and target functions that are used in the three evaluation methods.The establishment of evaluation system for co-extraction of coal and gas plays an important theoretical significance and guiding role in co-extraction of coal and gas for China's coal enterprises.
基金funded by the Beijing Natural Science Foundation (9144033)the National Social Science Fund for Major Projects (11&ZD164)
文摘Because forecasting a development program during the target selection phase of exploration for coalbed methane （CBM） is impossible, the conventional method that relies on a conceptual （or detailed） development pro- gram cannot be used during the economic evaluation of CBM resources. Hence, this study focuses on establishing an economic evaluation model based on the characteristics of the target selection phase. The discounted cashflow method is applied to the construction of the model with the assumption that there is a uniform distribution of produc- tion wells. The computational error generated by the assumption is corrected by introducing a correction factor based on the production profile of single CBM wells. The case study demonstrates that the blocks lacking economic value can be screened out, and the most advantageous targets can be found by computing the resource values in the best- and worst-case scenarios. This technique can help to reduce wasted investments and improve the quality of decision-making in selecting targets for exploration.
基金financially supported by the Major Program of National Social Science Foundation (No.16ZDA006)National Natural Science Foundation of China (Nos.71603193 and 71974151)Teaching and Research Project of Wuhan University (No.1201-413200127)。
文摘This study aims to investigate the influence of rapid economic development on pollution at the municipal level in China.It constructs a Stochastic Impacts by Regression on Population,Affluence and Technology model(STIRPAT model) and uses comprehensive municipal data on industrial pollution and economic performance.The dataset contains 290 cities from2003 to 2016 as a sample for the panel data analysis.The study further separates the cities into two groups by their levels of economic development for heterogeneity analysis.It reveals that a low level of economic development would aggravate environmental pollution,and when the economy reaches a high level,this economic development will improve environmental quality.We also find that the relationships between foreign direct investment and industrial dust and sulfur dioxide(SO_2) discharge are significant,while the relationship between economic growth and effluent emission is not.The more developed subsample cities present an inverted U-shaped curve between industrial pollutant emission,GDP per capita,and foreign direct investment,while the less developed subsamples show no such relationship.Since the shape of these curves differs among regions,their turning points vary accordingly.Based on this finding,this study suggests that the governments of more developed cities should balance environmental pollution and economic development by enhancing environmental regulations and adjusting industrial structure.
基金supported by National Key Social Science Research Project(11&ZD042)Forestry Public Welfare Scientific Research Project of the State Forestry Administration in China(200904003)DAAD-K.C.Wong Postdoctoral Fellowship Programme,Germany
文摘To better promote forest resource management and strengthen the development of forest carbon sink marketization, this paper studied the accounting of forest carbon sinks from 2003 to 2008 based on a system of national accounts （SNA） and data from the latest forest resources inventory in China. The study calculated the value of forest carbon stocks at a total of RMB 817.13 × 10^9 yuan in 2003 and RMB 839.93×10^9 yuan in 2008, with an average annual increase of 0.55 % from an increase in physical carbon sinks. The total value of forest carbon sinks in 2003 and 2008 was RMB 26.73×10^9 yuan and RMB 29.77×10^9 yuan, respectively, with an average annual growth of 2.18 %. From 2003 to 2008, both stock and flow value of forest carbon sinks increased, but the total net flow value of carbon sinks decreased. The growth rate for the environmentally adjusted Gross Domestic Product （eaGDP） for China＇s forest carbon sinks was 17.23 %, outstripping the average growth rate of 9.5 % for the GDP during the same period. The study alsoindicates that China＇s forest carbon sinks affects the GDP in the range of 0.25-0.26 %, and its economic potential is not relatively huge.
基金supported by the Global Energy Interconnection Group’s Science & Technology Project “Global Clean Energy Potential Estimating Model: Methodology and Application” (524500180011)
文摘Solar PV is expected to become the most cost-competitive renewable energy owing to the rapidly decreasing cost of the system. On the other hand, hydropower is a high-quality and reliable regulating power source that can be bundled with solar PV to improve the economic feasibility of long-distance transmitted power. In this paper, a quantification model is established taking into account the regulating capacity of the reservoir, the characteristics of solar generation, and cost of hydro and solar PV with long-distance transmission based on the installed capacity ratio of hydro–solar hybrid power. Results indicate that for hydropower stations with high regulating capacity and generation factor of approximately 0.5, a hydro–solar installed capacity ratio of 1:1 will yield overall optimal economic performance, whereas for hydropower stations with daily regulating capacity reservoir and capacity factor of approximately 0.65, the optimal hydro–solar installed capacity ratio is approximately 1:0.3. In addition, the accuracy of the approach used in this study is verified through operation simulation of a hydro–solar hybrid system including ultra high-voltage direct current(UHVDC) transmission using two case studies in Africa.
基金supported by the Global Energy Interconnection Group Co.,Ltd.Science and Technology Project(Project No.101662224/Title:UHV large-capacity DC submarine cable key technology and roadmap research)the National Key R&D Program of China(2016YFB0900702)
文摘Power transmission across the sea is an important part of global energy interconnection(GEI).To support the construction of GEI and to serve the needs of future clean energy trans-sea transportation and offshore wind power development,this study a)analyzes the requirements of the GEI backbone network pertaining to direct current(DC)submarine cable technology,and b)defines the key technical and economic indices of ultrahigh-voltage direct current(UHVDC)submarine cable based on theoretical computations.The research is based on the thermoelectric coupling model and the finite element method.It is shown that the dielectric strength of the insulating materials of the±800 kV~±1100 kV/4000 MW^12000 MW UHVDC submarine cable(extrusion insulation)should be not less than 43~65 kV/mm,while the heat resistance is not less than 110°C.As the cost of submarine cable is 5~10 times higher than that of the overhead line,the project investment need to be decreased to a level within the economical carrying capacity to guarantee extensive applicability of the HVDC submarine cable technology.
文摘This study was performed in five villages of Sandwip Upazila, Chittagong district with a view to identify the tree resources, utilization pattern and economic return of major fruit and timber tree species. Information collected from a total of 60 households ranging from marginal, small, medium and large categories. Number of plant species increased with the increase of homestead area. A total of 33 plant species were recorded from the homegarden, of which 19 were fruit and 14 were timber tree species. Considerable number of vegetables was also planted under the shade of the homestead trees. The investment analysis showed that average benefit-cost ratios were greater than one, net present values were positive and internal rate of returns were more than 10%. Long term investment on horticulture and timber tree species is highly profitable if species like Artocarpus heterophyllus, Cocos nucifera, Tectona grandis and Swietenia macrophylla are planted.
