Promoting the deep integration of advanced manufacturing and producer services is not only a key path for metropolitan to climb the global value chain,but also an important new driving force for optimizing urban spati...Promoting the deep integration of advanced manufacturing and producer services is not only a key path for metropolitan to climb the global value chain,but also an important new driving force for optimizing urban spatial structure.Based on the two dimen-sions of industrial linkage and spatial co-agglomeration from the perspective of industrial integration,taking Beijing,China as a case,using industrial input-output data,micro-enterprise spatial data,and methods such as industrial linkage model,standard deviation el-lipse,and spatial similarity coefficient,this study explores the coupling relationship between industrial linkage and spatial co-agglomer-ation of advanced manufacturing and producer services from 2007 to 2020.The results demonstrate that:1)the industrial linkage between advanced manufacturing and producer services in Beijing has an upward trend,in which the business services have the most significant improvement,in which the business services have the most improvement while the technology services have the most de-crease,but in general,the industrial linkage between the two industries shows a low level.2)Producer services were more spatially clustered than advanced manufacturing,and the degree of spatial co-agglomeration of the two also showed an increasing trend,with strong regional and industrial heterogeneity characteristics,among which the pairing industry involving commerce services and techno-logy services had a more obvious improvement.3)The coupling analysis found that the spatial dependence between advanced manufac-turing and producer services decreased,showing a weak positive correlation and a decreasing trend between industrial linkage and spa-tial co-agglomeration;the heterogeneity among subdivision pairs is prominent,and the strong correlation between industries does not mean that there is an inevitable spatial co-agglomeration.4)Based on the differences in coupling relationships and influence mechan-isms,four coupling modes are identified:H-H type,H-L type,L-L type,and L-H type.Finally,this study proposes three policy implica-tions for the integration of advanced manufacturing and producer services in metropolitan areas.展开更多
Globalization and informatization have accelerated city networking process over the world, which makes research on city network a hot topic in the fields of urban geography and economic geography. With Chinese economi...Globalization and informatization have accelerated city networking process over the world, which makes research on city network a hot topic in the fields of urban geography and economic geography. With Chinese economic structure adjustment and city economic growth, producer services have begun to play an increasingly important role in city-region networking. This paper employs the methodology of world city network to analyze and explain the spatial development characteristics of China's urban network system based on the data of nationwide producer services enterprise network. The research result indicated that the distribution of producer services network has a positive effect on the development of Chinese city networks. City network connectivity is closely related to the significance of city in producer services development, and the former will gradually decline with the drop of the latter. Accordingly, the 64 cities can be divided into the national central cities, regional central cities, sub-regional central cities and local central cities in accordance with their position and role in the nationwide producer services network. It is concluded that high-grade cities with quality producer services dominate the pattern of Chinese city networks and there emerges three spatial agglomerations of producer services enterprises in Changjiang (Yangtze) River Delta, Zhujiang (Pearl) River Delta and Beijing-Tianjin-Tangshan Economical Region. Moreover, the distribution of different producer services industry varies from city to city, which also affects the characteristics of network development.展开更多
As the Central Place Theory indicates, the centricity of a central city can influence the extension of its ser- vice. Since the service industry in the theory is mostly consumer services, it is worth studying the rela...As the Central Place Theory indicates, the centricity of a central city can influence the extension of its ser- vice. Since the service industry in the theory is mostly consumer services, it is worth studying the relationship between the producer services and the centricity of the city in the service society with producer services becoming a more im- portant part of the service industry. The paper takes the case of the Zhujiang (Pearl) River Delta (PRD), a developed region in China, to study the relationship between the developing level of producer services and the urban hierarchy. Based on the analysis about the spatial difference of the producer services in the nine cities of the PRD, and the divi- sion of the nine cities according to some economic indices, it is shown that there is a correlation between the develop- ing level of producer services and the urban hierarchy. Furthermore, two deductions about the future status of the pro- ducer services in the city and the location of the producer services in a large region can be made from this correlation between the developing level of producer services and the urban hierarchy.展开更多
In this study,NiO/SBA-15 was prepared by both direct and post synthesis methods.TEM images revealed that NiO particles aggregated in NiO/SBA-15 obtained with post synthesis method,regardless of NiO loading.However,NiO...In this study,NiO/SBA-15 was prepared by both direct and post synthesis methods.TEM images revealed that NiO particles aggregated in NiO/SBA-15 obtained with post synthesis method,regardless of NiO loading.However,NiO particles were monodispersed in NiO/SBA-15 with a NiO loading of less than 15 wt%by using the direct synthesis method.In this case,NiO particles aggregated when NiO loading was over 20 wt%.TPR analysis verified that with direct synthesis method the location boundary of NiO particles on outer and pore surface could be observed clearly,whereas that could not observed in the case of post synthesis method.This indicates that the type of synthesis method displays significant effect on the location of NiO particles dispersed into the SBA-15.Producer gas conversion was carried out using NiO/SBA-15 as catalysts,which were synthesized with different synthesis methods.The gas conversion including methanation occurred at low temperature(i.e.,300-400℃)and the reverse water gas shift(RWGS)reaction at hightemperature(i.e.,400-900℃).High temperatures facilitated CO conversion to CO with CO selectivity close to 100%,regardless of the synthesis method of the used catalyst.At low temperatures the dispersion type of NiO particles affectedthe CO,conversion reaction,i.e.,monodispersed Ni0 particles gave a CO selectivity of close to 100%,similar to thatobtained at high temperature.The aggregated NiO particles resuled in a CO selectivity of less than 100%owing to CH,formation,regardless of synthesis method of catalyst.Therefore,NiO/SBA-15 obtained with direct synthesis methodfavored RWGS reaction because of high CO selectivity.NiOSBA-15 obtained with post synthesis method is suited formethanation because of high CH selectivity,and the conversion of CO,to CHa through methanation increased withincreasing NiO loading.展开更多
The relationship between the government and the waste producer is always a representative and realistic issue,especially concerning the venous industry.This article is based on the true relationship between the govern...The relationship between the government and the waste producer is always a representative and realistic issue,especially concerning the venous industry.This article is based on the true relationship between the government and the waste producer,uses the methods from the evolutionary game theory,and analyzes the relationship between the government and the waste producer in detail.展开更多
Producer gas through gasification of biomass can be used as an alternate fuel in rural areas due to high potential of biomass resources in India.Experiments were conducted to study the performance of a diesel engine(f...Producer gas through gasification of biomass can be used as an alternate fuel in rural areas due to high potential of biomass resources in India.Experiments were conducted to study the performance of a diesel engine(four stroke,single cylinder,5.25 kW) with respect to its thermal efficiency,specific fuel consumption and diesel substitution by use of diesel alone and producer gas-cum-diesel(dual fuel mode).Three types of biomass,i.e.wood chips,pigeon pea stalks and corn cobs were used for generation of producer gas.A producer gas system consisting of a downdraft gasifier,a cooling cum cleaning unit,a filtering unit and a gas air mixing device was designed,fabricated and used to power a 5.25 kW diesel engine on dual fuel mode.Performance of the engine was reported by keeping biomass moisture contents as 8%,12%,16%,and 21%,engine speed as 1 600 r/min and with variable engine loads.The average value of thermal efficiency on dual fuel mode was found slightly lower than that of diesel mode.The specific diesel consumption was found to be 60%-64% less in dual fuel mode than that in diesel mode for the same amount of energy output.The average diesel substitution of 74% was observed with wood chips followed by corn cobs(78%) and pigeon pea stalks(82%).Based on the performance studied,the producer gas may be used as a substitute or as supplementary fuel for diesel conservation,particularly for stationary engines in agricultural operations in the farm.展开更多
The accuracy of predicting the Producer Price Index(PPI)plays an indispensable role in government economic work.However,it is difficult to forecast the PPI.In our research,we first propose an unprecedented hybrid mode...The accuracy of predicting the Producer Price Index(PPI)plays an indispensable role in government economic work.However,it is difficult to forecast the PPI.In our research,we first propose an unprecedented hybrid model based on fuzzy information granulation that integrates the GA-SVR and ARIMA(Autoregressive Integrated Moving Average Model)models.The fuzzy-information-granulation-based GA-SVR-ARIMA hybrid model is intended to deal with the problem of imprecision in PPI estimation.The proposed model adopts the fuzzy information-granulation algorithm to pre-classification-process monthly training samples of the PPI,and produced three different sequences of fuzzy information granules,whose Support Vector Regression(SVR)machine forecast models were separately established for their Genetic Algorithm(GA)optimization parameters.Finally,the residual errors of the GA-SVR model were rectified through ARIMA modeling,and the PPI estimate was reached.Research shows that the PPI value predicted by this hybrid model is more accurate than that predicted by other models,including ARIMA,GRNN,and GA-SVR,following several comparative experiments.Research also indicates the precision and validation of the PPI prediction of the hybrid model and demonstrates that the model has consistent ability to leverage the forecasting advantage of GA-SVR in non-linear space and of ARIMA in linear space.展开更多
The five central cities-Beijing,Tianjin,Shanghai,Guangzhou and Shenzhen-of the three most important strategic regions in China,namely Beijing-Tianjin-Hebei metropolitan region,the Yangtze River Delta and the Pearl Riv...The five central cities-Beijing,Tianjin,Shanghai,Guangzhou and Shenzhen-of the three most important strategic regions in China,namely Beijing-Tianjin-Hebei metropolitan region,the Yangtze River Delta and the Pearl River Delta,are taken as a comparative analysis on urban producer services' competitiveness,especially focusing on the comparative advantages and disadvantages of producer services in Beijing.Firstly,based on an integrated indicator system including one objective hierarchy,four standard hierarchies and 35 indicator hierarchies,the study applies factor analysis model and analytic hierarchy process model reformed by entropy technology to measure the comprehensive competitiveness of producer services in the above five cities.Secondly,Beijing has comparative advantages of capital resource,industrial base,scientific research resource and market scale,since it takes the first place of the five cities in the comprehensive competitiveness of producer services,the competitiveness of industrial development,business environment and living environment,only inferior to Shanghai in the competitiveness of talent capital.Thirdly,Beijing has comparative disadvantages in the level of producer services development,urban innovation capability and living environment.Finally,five proposals are put forth to enhance the competitiveness of producer services in Beijing,namely perfecting the system of laws and statutes,supporting the development of industry association,implementing scientific development planning,introducing preferential fiscal and taxation policies and strengthening human capital reserve.展开更多
On the basis of defining the producers in the supply chain of agricultural products,the SWOT analysis is adopted to analyze the advantages,disadvantages,opportunities and threats of producers in the supply chain of Ch...On the basis of defining the producers in the supply chain of agricultural products,the SWOT analysis is adopted to analyze the advantages,disadvantages,opportunities and threats of producers in the supply chain of Chinese agricultural products.The paper analyzes the advantages of producers in the supply chain of agricultural products from three aspects including land resources,technology level of producers and input costs.The disadvantages of producers in the supply chain of agricultural products are analyzed from three aspects including scale level,mechanization and technology level and profit level.The opportunities of producers in the supply chain of agricultural products are analyzed from the aspects of laws,policies,capitals and technologies.The threats confronted by the producers in the supply chain of agricultural products are analyzed from foreign producers,negotiation control of supply chain of agricultural chain,environment protection and quality safety standard.On the basis of the analysis,the relevant suggestions on facilitating the interests of producers in the supply chain of Chinese agricultural products are put forward,including fully displaying the advantages of land resources;improving the knowledge and technology level of supply chain of agricultural production;establishing the alliances of producers of agricultural products to expand production scale;improving the quality of agricultural products to satisfy the relevant safety quality standard and environmental protection standard.展开更多
The energizing of large power transformers has long been considered a critical event in the operation of an electric power system. When a transformer is energized by the utility, a typical inrush current could be as h...The energizing of large power transformers has long been considered a critical event in the operation of an electric power system. When a transformer is energized by the utility, a typical inrush current could be as high as ten times its rated current. This could cause many problems from mechanical stress on transformer windings to harmonics injection, and system protection malfunction. There have been numerous researches focusing on calculation and mitigation of the transformer inrush current. With the development of smart grid, distributed generation from independent power producers (IPPs) is growing rapidly. This paper investigates the inrush current due to black start of an IPP system with several parallel transformers, through a simulation model in DIgSILENT Power Factory software. The study demonstrates that a single genset is capable of energizing a group of transformers since the overall inrush current is slightly above the inrush of the transformer directly connected to the generator. In addition, a simple method is proposed to mitigate the inrush current of the transformers using an auxiliary transformer.展开更多
The issue of "who will grow grain in the future in China" attracts more and more attention. We estimate the structure of China's grain producers at present,and summarize the phenomena and reasons why pe...The issue of "who will grow grain in the future in China" attracts more and more attention. We estimate the structure of China's grain producers at present,and summarize the phenomena and reasons why peasants would not like to grow grain. We analyze the agricultural population at the time of China's total population peak around 2033,and we predict there will be a multi-producer structure of grain growing.The household contracts will be as the basis of grain operations then,and the quantity of small-scale households will decrease but still be huge.The degree of organization of rural households will increase and the role of cooperatives will be strengthened remarkably. We propose the " quality" requirements to ensure the grain production,and note different special groups will be the new forces on farming and grain growing.展开更多
The Guangdong-Hong Kong-Macao Greater Bay Area is witnessing a surge in economic development,showcasing robust resilience in the co-agglomeration of producer services and manufacturing industries,along with the increa...The Guangdong-Hong Kong-Macao Greater Bay Area is witnessing a surge in economic development,showcasing robust resilience in the co-agglomeration of producer services and manufacturing industries,along with the increasingly evident impact generated by such co-agglomeration.Based on the panel data collected from ten cities in the Guangdong-Hong Kong-Macao Greater Bay Area(excluding Zhaoqing)spanning from 2010 to 2020,we examined the formation mechanism for industrial co-agglomeration in the area from three dimensions:industrial correlation,spatial correlation,and policy guidance.Our analysis was based on a vertical correlation model and was validated using the seemingly unrelated regressions(SUR)method.The findings are as follows:(a)There currently exists no spatial correlation between the producer services and manufacturing sectors in the area,and the correlation between the two remains limited to the former providing specialized services to the latter.(b)Policy guidance has a positive impact on the location selection of industries within the area.By implementing a comprehensive range of favorable policies,local governments can provide effective and scientifically guided recommendations regarding the location of producer services and manufacturing sectors.Therefore,it is crucial to foster the collaboration between producer services and manufacturing sectors and further enhance the co-agglomeration between the two sectors.In addition,the government authorities should also strive to enhance its economic governance capacity,thereby facilitating the formation of such co-agglomeration.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.42371181)。
文摘Promoting the deep integration of advanced manufacturing and producer services is not only a key path for metropolitan to climb the global value chain,but also an important new driving force for optimizing urban spatial structure.Based on the two dimen-sions of industrial linkage and spatial co-agglomeration from the perspective of industrial integration,taking Beijing,China as a case,using industrial input-output data,micro-enterprise spatial data,and methods such as industrial linkage model,standard deviation el-lipse,and spatial similarity coefficient,this study explores the coupling relationship between industrial linkage and spatial co-agglomer-ation of advanced manufacturing and producer services from 2007 to 2020.The results demonstrate that:1)the industrial linkage between advanced manufacturing and producer services in Beijing has an upward trend,in which the business services have the most significant improvement,in which the business services have the most improvement while the technology services have the most de-crease,but in general,the industrial linkage between the two industries shows a low level.2)Producer services were more spatially clustered than advanced manufacturing,and the degree of spatial co-agglomeration of the two also showed an increasing trend,with strong regional and industrial heterogeneity characteristics,among which the pairing industry involving commerce services and techno-logy services had a more obvious improvement.3)The coupling analysis found that the spatial dependence between advanced manufac-turing and producer services decreased,showing a weak positive correlation and a decreasing trend between industrial linkage and spa-tial co-agglomeration;the heterogeneity among subdivision pairs is prominent,and the strong correlation between industries does not mean that there is an inevitable spatial co-agglomeration.4)Based on the differences in coupling relationships and influence mechan-isms,four coupling modes are identified:H-H type,H-L type,L-L type,and L-H type.Finally,this study proposes three policy implica-tions for the integration of advanced manufacturing and producer services in metropolitan areas.
基金Under the auspices of National Natural Science Foundation of China(No.40971094)
文摘Globalization and informatization have accelerated city networking process over the world, which makes research on city network a hot topic in the fields of urban geography and economic geography. With Chinese economic structure adjustment and city economic growth, producer services have begun to play an increasingly important role in city-region networking. This paper employs the methodology of world city network to analyze and explain the spatial development characteristics of China's urban network system based on the data of nationwide producer services enterprise network. The research result indicated that the distribution of producer services network has a positive effect on the development of Chinese city networks. City network connectivity is closely related to the significance of city in producer services development, and the former will gradually decline with the drop of the latter. Accordingly, the 64 cities can be divided into the national central cities, regional central cities, sub-regional central cities and local central cities in accordance with their position and role in the nationwide producer services network. It is concluded that high-grade cities with quality producer services dominate the pattern of Chinese city networks and there emerges three spatial agglomerations of producer services enterprises in Changjiang (Yangtze) River Delta, Zhujiang (Pearl) River Delta and Beijing-Tianjin-Tangshan Economical Region. Moreover, the distribution of different producer services industry varies from city to city, which also affects the characteristics of network development.
基金Foundation item: Under the auspices of National Natural Science Foundation of China (No. 40125003, No. 40601029)Natural Science Foundation of Guangdong Province (No. 06300790)
文摘As the Central Place Theory indicates, the centricity of a central city can influence the extension of its ser- vice. Since the service industry in the theory is mostly consumer services, it is worth studying the relationship between the producer services and the centricity of the city in the service society with producer services becoming a more im- portant part of the service industry. The paper takes the case of the Zhujiang (Pearl) River Delta (PRD), a developed region in China, to study the relationship between the developing level of producer services and the urban hierarchy. Based on the analysis about the spatial difference of the producer services in the nine cities of the PRD, and the divi- sion of the nine cities according to some economic indices, it is shown that there is a correlation between the develop- ing level of producer services and the urban hierarchy. Furthermore, two deductions about the future status of the pro- ducer services in the city and the location of the producer services in a large region can be made from this correlation between the developing level of producer services and the urban hierarchy.
文摘In this study,NiO/SBA-15 was prepared by both direct and post synthesis methods.TEM images revealed that NiO particles aggregated in NiO/SBA-15 obtained with post synthesis method,regardless of NiO loading.However,NiO particles were monodispersed in NiO/SBA-15 with a NiO loading of less than 15 wt%by using the direct synthesis method.In this case,NiO particles aggregated when NiO loading was over 20 wt%.TPR analysis verified that with direct synthesis method the location boundary of NiO particles on outer and pore surface could be observed clearly,whereas that could not observed in the case of post synthesis method.This indicates that the type of synthesis method displays significant effect on the location of NiO particles dispersed into the SBA-15.Producer gas conversion was carried out using NiO/SBA-15 as catalysts,which were synthesized with different synthesis methods.The gas conversion including methanation occurred at low temperature(i.e.,300-400℃)and the reverse water gas shift(RWGS)reaction at hightemperature(i.e.,400-900℃).High temperatures facilitated CO conversion to CO with CO selectivity close to 100%,regardless of the synthesis method of the used catalyst.At low temperatures the dispersion type of NiO particles affectedthe CO,conversion reaction,i.e.,monodispersed Ni0 particles gave a CO selectivity of close to 100%,similar to thatobtained at high temperature.The aggregated NiO particles resuled in a CO selectivity of less than 100%owing to CH,formation,regardless of synthesis method of catalyst.Therefore,NiO/SBA-15 obtained with direct synthesis methodfavored RWGS reaction because of high CO selectivity.NiOSBA-15 obtained with post synthesis method is suited formethanation because of high CH selectivity,and the conversion of CO,to CHa through methanation increased withincreasing NiO loading.
基金supported by the Innovation Foundation of Shanghai Municipal Education Commission (Grant No.09YS47)
文摘The relationship between the government and the waste producer is always a representative and realistic issue,especially concerning the venous industry.This article is based on the true relationship between the government and the waste producer,uses the methods from the evolutionary game theory,and analyzes the relationship between the government and the waste producer in detail.
文摘Producer gas through gasification of biomass can be used as an alternate fuel in rural areas due to high potential of biomass resources in India.Experiments were conducted to study the performance of a diesel engine(four stroke,single cylinder,5.25 kW) with respect to its thermal efficiency,specific fuel consumption and diesel substitution by use of diesel alone and producer gas-cum-diesel(dual fuel mode).Three types of biomass,i.e.wood chips,pigeon pea stalks and corn cobs were used for generation of producer gas.A producer gas system consisting of a downdraft gasifier,a cooling cum cleaning unit,a filtering unit and a gas air mixing device was designed,fabricated and used to power a 5.25 kW diesel engine on dual fuel mode.Performance of the engine was reported by keeping biomass moisture contents as 8%,12%,16%,and 21%,engine speed as 1 600 r/min and with variable engine loads.The average value of thermal efficiency on dual fuel mode was found slightly lower than that of diesel mode.The specific diesel consumption was found to be 60%-64% less in dual fuel mode than that in diesel mode for the same amount of energy output.The average diesel substitution of 74% was observed with wood chips followed by corn cobs(78%) and pigeon pea stalks(82%).Based on the performance studied,the producer gas may be used as a substitute or as supplementary fuel for diesel conservation,particularly for stationary engines in agricultural operations in the farm.
基金This work was supported by Hainan Provincial Natural Science Foundation of China[2018CXTD333,617048]The National Natural Science Foundation of China[61762033,61702539]+1 种基金Hainan University Doctor Start Fund Project[kyqd1328]Hainan University Youth Fund Project[qnjj1444].
文摘The accuracy of predicting the Producer Price Index(PPI)plays an indispensable role in government economic work.However,it is difficult to forecast the PPI.In our research,we first propose an unprecedented hybrid model based on fuzzy information granulation that integrates the GA-SVR and ARIMA(Autoregressive Integrated Moving Average Model)models.The fuzzy-information-granulation-based GA-SVR-ARIMA hybrid model is intended to deal with the problem of imprecision in PPI estimation.The proposed model adopts the fuzzy information-granulation algorithm to pre-classification-process monthly training samples of the PPI,and produced three different sequences of fuzzy information granules,whose Support Vector Regression(SVR)machine forecast models were separately established for their Genetic Algorithm(GA)optimization parameters.Finally,the residual errors of the GA-SVR model were rectified through ARIMA modeling,and the PPI estimate was reached.Research shows that the PPI value predicted by this hybrid model is more accurate than that predicted by other models,including ARIMA,GRNN,and GA-SVR,following several comparative experiments.Research also indicates the precision and validation of the PPI prediction of the hybrid model and demonstrates that the model has consistent ability to leverage the forecasting advantage of GA-SVR in non-linear space and of ARIMA in linear space.
基金supported by National Natural Science Foundation of China (Crant No. 40971101Grant No.40871069)+1 种基金Mega-project of Science and Technology Research for the 11th Five Year Plan of China (Crant No.2006BAJ05A06No.2006BAJ14B02)
文摘The five central cities-Beijing,Tianjin,Shanghai,Guangzhou and Shenzhen-of the three most important strategic regions in China,namely Beijing-Tianjin-Hebei metropolitan region,the Yangtze River Delta and the Pearl River Delta,are taken as a comparative analysis on urban producer services' competitiveness,especially focusing on the comparative advantages and disadvantages of producer services in Beijing.Firstly,based on an integrated indicator system including one objective hierarchy,four standard hierarchies and 35 indicator hierarchies,the study applies factor analysis model and analytic hierarchy process model reformed by entropy technology to measure the comprehensive competitiveness of producer services in the above five cities.Secondly,Beijing has comparative advantages of capital resource,industrial base,scientific research resource and market scale,since it takes the first place of the five cities in the comprehensive competitiveness of producer services,the competitiveness of industrial development,business environment and living environment,only inferior to Shanghai in the competitiveness of talent capital.Thirdly,Beijing has comparative disadvantages in the level of producer services development,urban innovation capability and living environment.Finally,five proposals are put forth to enhance the competitiveness of producer services in Beijing,namely perfecting the system of laws and statutes,supporting the development of industry association,implementing scientific development planning,introducing preferential fiscal and taxation policies and strengthening human capital reserve.
基金Supported by the Innovation Fund Project for Graduate Student of Xihua University
文摘On the basis of defining the producers in the supply chain of agricultural products,the SWOT analysis is adopted to analyze the advantages,disadvantages,opportunities and threats of producers in the supply chain of Chinese agricultural products.The paper analyzes the advantages of producers in the supply chain of agricultural products from three aspects including land resources,technology level of producers and input costs.The disadvantages of producers in the supply chain of agricultural products are analyzed from three aspects including scale level,mechanization and technology level and profit level.The opportunities of producers in the supply chain of agricultural products are analyzed from the aspects of laws,policies,capitals and technologies.The threats confronted by the producers in the supply chain of agricultural products are analyzed from foreign producers,negotiation control of supply chain of agricultural chain,environment protection and quality safety standard.On the basis of the analysis,the relevant suggestions on facilitating the interests of producers in the supply chain of Chinese agricultural products are put forward,including fully displaying the advantages of land resources;improving the knowledge and technology level of supply chain of agricultural production;establishing the alliances of producers of agricultural products to expand production scale;improving the quality of agricultural products to satisfy the relevant safety quality standard and environmental protection standard.
文摘The energizing of large power transformers has long been considered a critical event in the operation of an electric power system. When a transformer is energized by the utility, a typical inrush current could be as high as ten times its rated current. This could cause many problems from mechanical stress on transformer windings to harmonics injection, and system protection malfunction. There have been numerous researches focusing on calculation and mitigation of the transformer inrush current. With the development of smart grid, distributed generation from independent power producers (IPPs) is growing rapidly. This paper investigates the inrush current due to black start of an IPP system with several parallel transformers, through a simulation model in DIgSILENT Power Factory software. The study demonstrates that a single genset is capable of energizing a group of transformers since the overall inrush current is slightly above the inrush of the transformer directly connected to the generator. In addition, a simple method is proposed to mitigate the inrush current of the transformers using an auxiliary transformer.
基金Supported by the National Key Technology R&D Program(2013BAD15B00)
文摘The issue of "who will grow grain in the future in China" attracts more and more attention. We estimate the structure of China's grain producers at present,and summarize the phenomena and reasons why peasants would not like to grow grain. We analyze the agricultural population at the time of China's total population peak around 2033,and we predict there will be a multi-producer structure of grain growing.The household contracts will be as the basis of grain operations then,and the quantity of small-scale households will decrease but still be huge.The degree of organization of rural households will increase and the role of cooperatives will be strengthened remarkably. We propose the " quality" requirements to ensure the grain production,and note different special groups will be the new forces on farming and grain growing.
基金This paper is funded by the National Social Science Foundation of China entitled“A Study on the Role of Digital Technology in Facilitating the Integration of Modern Services and Advanced Manufacturing Sectors”(21BJY144)Major project supported by the Key Research Base of Humanities and Social Sciences in Universities of the Ministry of Education entitled“An Exploration of the Paths for Promoting High-level Opening Up in Guangdong-Hong Kong-Macao Greater Bay Area and Corresponding Measures”(22JD790056)Key project of Universities in Guangdong Province entitled“Research on Mechanism and Effect of Co-agglomeration of Producer Services and Manufacturing in Guangdong-Hong Kong-Macao Greater Bay Area”(2019WZDXM029).
文摘The Guangdong-Hong Kong-Macao Greater Bay Area is witnessing a surge in economic development,showcasing robust resilience in the co-agglomeration of producer services and manufacturing industries,along with the increasingly evident impact generated by such co-agglomeration.Based on the panel data collected from ten cities in the Guangdong-Hong Kong-Macao Greater Bay Area(excluding Zhaoqing)spanning from 2010 to 2020,we examined the formation mechanism for industrial co-agglomeration in the area from three dimensions:industrial correlation,spatial correlation,and policy guidance.Our analysis was based on a vertical correlation model and was validated using the seemingly unrelated regressions(SUR)method.The findings are as follows:(a)There currently exists no spatial correlation between the producer services and manufacturing sectors in the area,and the correlation between the two remains limited to the former providing specialized services to the latter.(b)Policy guidance has a positive impact on the location selection of industries within the area.By implementing a comprehensive range of favorable policies,local governments can provide effective and scientifically guided recommendations regarding the location of producer services and manufacturing sectors.Therefore,it is crucial to foster the collaboration between producer services and manufacturing sectors and further enhance the co-agglomeration between the two sectors.In addition,the government authorities should also strive to enhance its economic governance capacity,thereby facilitating the formation of such co-agglomeration.
