The carbon tradingmarket can promote“carbon peaking”and“carbon neutrality”at low cost,but carbon emission quotas face attacks such as data forgery,tampering,counterfeiting,and replay in the electricity trading mar...The carbon tradingmarket can promote“carbon peaking”and“carbon neutrality”at low cost,but carbon emission quotas face attacks such as data forgery,tampering,counterfeiting,and replay in the electricity trading market.Certificateless signatures are a new cryptographic technology that can address traditional cryptography’s general essential certificate requirements and avoid the problem of crucial escrowbased on identity cryptography.However,most certificateless signatures still suffer fromvarious security flaws.We present a secure and efficient certificateless signing scheme by examining the security of existing certificateless signature schemes.To ensure the integrity and verifiability of electricity carbon quota trading,we propose an electricity carbon quota trading scheme based on a certificateless signature and blockchain.Our scheme utilizes certificateless signatures to ensure the validity and nonrepudiation of transactions and adopts blockchain technology to achieve immutability and traceability in electricity carbon quota transactions.In addition,validating electricity carbon quota transactions does not require time-consuming bilinear pairing operations.The results of the analysis indicate that our scheme meets existential unforgeability under adaptive selective message attacks,offers conditional identity privacy protection,resists replay attacks,and demonstrates high computing and communication performance.展开更多
Since the early 1980 s, the multi-cropping index for rice has decreased significantly in main double-cropping rice area in China, which is the primary double-cropping rice(DCR) production area. This decline may bring ...Since the early 1980 s, the multi-cropping index for rice has decreased significantly in main double-cropping rice area in China, which is the primary double-cropping rice(DCR) production area. This decline may bring challenges to food security in China because rice is the staple food for more than 60% of the Chinese population. It has been generally recognized that rapidly rising labor costs due to economic growth and urbanization in China is the key driving force of the ‘double-to-single' rice cropping system adaption. However, not all provinces have shown a dramatic decline in DCR area, and labor costs alone cannot explain this difference. To elucidate the reasons for these inter-provincial distinctions and the dynamics of rice cropping system adaption, we evaluated the influencing factors using provincial panel data from 1980 to 2015. We also used household survey data for empirical analysis to explore the mechanisms driving differences in rice multi-cropping changes. Our results indicated that the eight provinces in the study can be divided into three spatial groups based on the extent of DCR area decline, the rapidly-declining marginal, core, and stable zones. Increasing labor cost due to rapid urbanization was the key driving force of rice cropping system adaption, but the land use dynamic vary hugely among different provinces. These differences between zones were due to the interaction between labor price and accumulated temperature conditions. Therefore, increasing labor costs had the greatest impact in Zhejiang, Anhui, and Hubei, where the accumulated temperature is relatively low and rice multi-cropping index declined dramaticly. However, labor costs had little impact in Guangdong and Guangxi. Differences in accumulated temperature conditions resulted in spatially different labor demands and pressure on households during the busy season. As a result, there have been different profits and rice multi-cropping changes between provinces and zones. Because of these spatial differences, regionally appropriate policies that provide appropriate subsidies for early rice in rapidly-declining marginal zone such as Zhejiang and Hubei should be implemented. In addition, agricultural mechanization and the number of agricultural workers have facilitated double-cropping; therefore, small machinery and agricultural infrastructure construction should be further supported.展开更多
The coordinated development between touristization and urbanization is the key to optimizing regional industrial structure and building a long-term dynamic mechanism for urbanization. Based on constructing the measure...The coordinated development between touristization and urbanization is the key to optimizing regional industrial structure and building a long-term dynamic mechanism for urbanization. Based on constructing the measurement index system of touristization and urbanization level, the evaluation model on the coupled and coordinated degree is used in this paper to measure the inter-provincial pattern of the coupled and coordinated relationship between touristization and urbanization in 31 provinces and autonomous regions in China. The results show that the coupled and coordinated relationship between touristization and urbanization is significantly different in different regions, which presents a gradient decline pattern of the highest in the east, the lower in the middle and the lowest in the west. In the future, measures should be taken to promote the coordinated development between touristization and urbanization in accordance with the regional differences and actual development needs.展开更多
In view of the extensive growth of China's steel production in recent years, this paper analyzed the industrial development background and economic geography theory, and discussed the possible spatial interaction ...In view of the extensive growth of China's steel production in recent years, this paper analyzed the industrial development background and economic geography theory, and discussed the possible spatial interaction mechanism. Based on panel data of China's inter-provincial steel output from 2001 to 2015, using spatial econometric model, this paper also explored whether China's provincial steel production shows material orientation, market orientation and traffic orientation, and isolated spatial interactions of interprovincial steel output. The results showed that the inter-provincial steel production in China did show both material orientation, market orientation and traffic orientation and that there was a significant negative spatial interaction, indicating that there might be strong competition and a crowing-out effect between neighboring provinces, and that the smaller the spatial scope, the more significant the spatial interactions of steel production.展开更多
China's food security mainly depends on the core areas of food production.Under the dual constraints of resource scarcity and environmental degradation,improving the grain production efficiency of the main grain-p...China's food security mainly depends on the core areas of food production.Under the dual constraints of resource scarcity and environmental degradation,improving the grain production efficiency of the main grain-producing areas has become the fundamental way to strengthen the grain production capacity and improve the national food security capability,and to improve the efficiency of grain production in major grain-producing areas requires empirical support.This paper used the Super SBM model and the Malmquist index to measure the grain production efficiency of the main grain-producing areas from 2001 to 2020 from both static and dynamic perspectives,and compared the differences in grain production efficiency among different soil types and different provinces(autonomous regions)in the main grain-producing areas.The results showed that from 2001 to 2020,the grain production in the main grain-producing areas was in a relatively ineffective state,and the differences in grain production efficiency among different soil types and different provinces(autonomous regions)in the main grain-producing areas were obvious.The order of grain production efficiency in different soil types was black soil region>red-yellow soil region>paddy soil region>fluvo-aquic soil region,and the order of grain production efficiency of the provinces(autonomous regions)in the main grain-producing areas was Jilin>Heilongjiang>Inner Mongolia>Jiangxi>Hunan>Sichuan>Hubei>Jiangsu>Liaoning>Henan>Anhui>Shandong>Hebei.From 2001 to 2020,the total factor productivity of grain in the main grain-producing areas increased,but due to the trade-off between the technological progress and the growth of technical efficiency,the increase in the total factor productivity of grain in the main grain-producing areas was small,and the growth mainly came from the increase of input factors in this period.The total factor productivity of grain in Hebei,Heilongjiang,Liaoning,Jilin,Inner Mongolia,Shandong,Jiangsu,Henan and Anhui increased,but the increase was small,while the total factor productivity of grain in Jiangxi,Sichuan,Hunan and Hubei provinces declined.展开更多
Floating population plays an important role in the development of cities,regions,and countries.The economic growth path with Guangdong characteristics is inseparable from the support of highly educated groups.Studying...Floating population plays an important role in the development of cities,regions,and countries.The economic growth path with Guangdong characteristics is inseparable from the support of highly educated groups.Studying the long-term residence intention of the highly educated floating population is helpful for the city to attract and retain talents.From the perspective of social integration,using CMDS 2017 data and taking Guangdong Province for example,this paper studies the influencing factors of long-term residence intention through SPSS logistic regression,taking intra-provincial and inter-provincial floating population with a bachelor’s degree or above as sample.The main conclusions are:(1)Marital and childbearing status is the primitive influencing factor of long-term residence intention among intra-provincial and inter-provincial floating population.Samples with high income,under social insurance system,being female and having non-agricultural hukou,are tend to prefer long-term residence.Samples who connect with the locals and participate in social public welfare are more likely to stay.(2)Personal age and city livability have a significant positive impact on the long-term residence intention of the inter-provincial highly educated floating population,but agricultural hukou and self-employed laborer status will weaken the long-term residence intention of this group.(3)Participation in townsmen/alumni association has a positive effect on the long-term residence intention of the intra-provincial highly educated floating population,and connection with outlanders also promotes the long-term residence intention of this group.(4)The long-term residence intention of inter-provincial highly educated floating population is usually based on reality,therefore they pay more attention to the development,changes,and livability of the destination city.However,the long-term residence intention of intra-provincial highly educated floating population is usually based on perception,so they pay more attention to whether they like the city.Compared with intra-provincial flows,inter-provincial flows have higher economic and emotional migration costs,more institutional barriers,and more life adaptation problems.Therefore,the government should introduce targeted measures to promote social integration and improve long-term residence intention.展开更多
To determine suitable thresholds for deficit irrigation of winter wheat in the well-irrigated area of the Huang-Huai-Hai Plain,we investigated the effects of different deficit irrigation lower limits and quotas on the...To determine suitable thresholds for deficit irrigation of winter wheat in the well-irrigated area of the Huang-Huai-Hai Plain,we investigated the effects of different deficit irrigation lower limits and quotas on the photosynthetic characteristics and grain yield of winter wheat.Four irrigation lower limits were set for initiating irrigation(i.e.,light drought(LD,50%,55%,60%and 50%of field holding capacity(FC)at the seedling-regreening,jointing,heading and filling-ripening stages,respectively),medium drought(MD,40%,50%,55%and 45%of FC at the same stages,respectively),adequate moisture(CK1,60%,65%,70%and 60%of FC at the same stages,respectively),heavy drought(CK2,35%,40%,45%and 40%of FC at the same stages,respectively))and five irrigation quota per event(30,60,90,120 and 180 mm)were set for each lower limit.We found that the increase of drought stress is conducive to normal photosynthesis of winter wheat leaves which is supported by the following findings.First,photosynthetic rate(Pn)of LD60 treatment was higher than that of LD30,LD90,LD120,LD180,MD30,MD60,MD90,MD120 and MD180.Then,Under the 90 mm irrigation quota treatment,the yield of winter wheat basically increased with the increase of irrigation’s lower limit.Moreover,With the increase in irrigation quota,the yield of winter wheat increased,and the water use efficiency(WUE)of winter wheat increased at first and then decreased.In addition,compared with the LD30,MD30,MD60,MD90,MD120,and MD180,the yield of winter wheat in LD60 treatment increased by about 3.23%(3-year average),32.3%,19.9%,11.7%,10.1%,and 14.6%.At the same time,the WUE with LD60 treatment of winter wheat was significantly higher than LD90,LD120,LD180,MD30,MD60,MD90,MD120,MD180 treatments.There was a positive correlation between soil volumetric water content and Pn and between yield and Pn.The key period for yield formation in winter wheat is 180 days after sowing.In conclusion,to achieve the dual goals of stable winter wheat yield and efficient utilization of water resources in this region,the suitable threshold for initiating deficit irrigation of winter wheat is the LD60 treatment.This conclusion provides data support for water-saving and stable yield of winter wheat in this area.展开更多
基金the National Fund Project No.62172337National Natural Science Foundation of China(No.61662069)China Postdoctoral Science Foundation(No.2017M610817).
文摘The carbon tradingmarket can promote“carbon peaking”and“carbon neutrality”at low cost,but carbon emission quotas face attacks such as data forgery,tampering,counterfeiting,and replay in the electricity trading market.Certificateless signatures are a new cryptographic technology that can address traditional cryptography’s general essential certificate requirements and avoid the problem of crucial escrowbased on identity cryptography.However,most certificateless signatures still suffer fromvarious security flaws.We present a secure and efficient certificateless signing scheme by examining the security of existing certificateless signature schemes.To ensure the integrity and verifiability of electricity carbon quota trading,we propose an electricity carbon quota trading scheme based on a certificateless signature and blockchain.Our scheme utilizes certificateless signatures to ensure the validity and nonrepudiation of transactions and adopts blockchain technology to achieve immutability and traceability in electricity carbon quota transactions.In addition,validating electricity carbon quota transactions does not require time-consuming bilinear pairing operations.The results of the analysis indicate that our scheme meets existential unforgeability under adaptive selective message attacks,offers conditional identity privacy protection,resists replay attacks,and demonstrates high computing and communication performance.
基金National Program on Key Basic Research Project(No.2015CB452706)
文摘Since the early 1980 s, the multi-cropping index for rice has decreased significantly in main double-cropping rice area in China, which is the primary double-cropping rice(DCR) production area. This decline may bring challenges to food security in China because rice is the staple food for more than 60% of the Chinese population. It has been generally recognized that rapidly rising labor costs due to economic growth and urbanization in China is the key driving force of the ‘double-to-single' rice cropping system adaption. However, not all provinces have shown a dramatic decline in DCR area, and labor costs alone cannot explain this difference. To elucidate the reasons for these inter-provincial distinctions and the dynamics of rice cropping system adaption, we evaluated the influencing factors using provincial panel data from 1980 to 2015. We also used household survey data for empirical analysis to explore the mechanisms driving differences in rice multi-cropping changes. Our results indicated that the eight provinces in the study can be divided into three spatial groups based on the extent of DCR area decline, the rapidly-declining marginal, core, and stable zones. Increasing labor cost due to rapid urbanization was the key driving force of rice cropping system adaption, but the land use dynamic vary hugely among different provinces. These differences between zones were due to the interaction between labor price and accumulated temperature conditions. Therefore, increasing labor costs had the greatest impact in Zhejiang, Anhui, and Hubei, where the accumulated temperature is relatively low and rice multi-cropping index declined dramaticly. However, labor costs had little impact in Guangdong and Guangxi. Differences in accumulated temperature conditions resulted in spatially different labor demands and pressure on households during the busy season. As a result, there have been different profits and rice multi-cropping changes between provinces and zones. Because of these spatial differences, regionally appropriate policies that provide appropriate subsidies for early rice in rapidly-declining marginal zone such as Zhejiang and Hubei should be implemented. In addition, agricultural mechanization and the number of agricultural workers have facilitated double-cropping; therefore, small machinery and agricultural infrastructure construction should be further supported.
基金supported by the National Natural Science Foundation of China(Grant No.41471131)the Training Program for 100 Young Academic Leaders of Nankai University
文摘The coordinated development between touristization and urbanization is the key to optimizing regional industrial structure and building a long-term dynamic mechanism for urbanization. Based on constructing the measurement index system of touristization and urbanization level, the evaluation model on the coupled and coordinated degree is used in this paper to measure the inter-provincial pattern of the coupled and coordinated relationship between touristization and urbanization in 31 provinces and autonomous regions in China. The results show that the coupled and coordinated relationship between touristization and urbanization is significantly different in different regions, which presents a gradient decline pattern of the highest in the east, the lower in the middle and the lowest in the west. In the future, measures should be taken to promote the coordinated development between touristization and urbanization in accordance with the regional differences and actual development needs.
文摘In view of the extensive growth of China's steel production in recent years, this paper analyzed the industrial development background and economic geography theory, and discussed the possible spatial interaction mechanism. Based on panel data of China's inter-provincial steel output from 2001 to 2015, using spatial econometric model, this paper also explored whether China's provincial steel production shows material orientation, market orientation and traffic orientation, and isolated spatial interactions of interprovincial steel output. The results showed that the inter-provincial steel production in China did show both material orientation, market orientation and traffic orientation and that there was a significant negative spatial interaction, indicating that there might be strong competition and a crowing-out effect between neighboring provinces, and that the smaller the spatial scope, the more significant the spatial interactions of steel production.
基金Supported by Science of China University Journals(CUJS2021-027)China Agricultural Journals Website 2021(CAJW2021-033)。
文摘China's food security mainly depends on the core areas of food production.Under the dual constraints of resource scarcity and environmental degradation,improving the grain production efficiency of the main grain-producing areas has become the fundamental way to strengthen the grain production capacity and improve the national food security capability,and to improve the efficiency of grain production in major grain-producing areas requires empirical support.This paper used the Super SBM model and the Malmquist index to measure the grain production efficiency of the main grain-producing areas from 2001 to 2020 from both static and dynamic perspectives,and compared the differences in grain production efficiency among different soil types and different provinces(autonomous regions)in the main grain-producing areas.The results showed that from 2001 to 2020,the grain production in the main grain-producing areas was in a relatively ineffective state,and the differences in grain production efficiency among different soil types and different provinces(autonomous regions)in the main grain-producing areas were obvious.The order of grain production efficiency in different soil types was black soil region>red-yellow soil region>paddy soil region>fluvo-aquic soil region,and the order of grain production efficiency of the provinces(autonomous regions)in the main grain-producing areas was Jilin>Heilongjiang>Inner Mongolia>Jiangxi>Hunan>Sichuan>Hubei>Jiangsu>Liaoning>Henan>Anhui>Shandong>Hebei.From 2001 to 2020,the total factor productivity of grain in the main grain-producing areas increased,but due to the trade-off between the technological progress and the growth of technical efficiency,the increase in the total factor productivity of grain in the main grain-producing areas was small,and the growth mainly came from the increase of input factors in this period.The total factor productivity of grain in Hebei,Heilongjiang,Liaoning,Jilin,Inner Mongolia,Shandong,Jiangsu,Henan and Anhui increased,but the increase was small,while the total factor productivity of grain in Jiangxi,Sichuan,Hunan and Hubei provinces declined.
文摘Floating population plays an important role in the development of cities,regions,and countries.The economic growth path with Guangdong characteristics is inseparable from the support of highly educated groups.Studying the long-term residence intention of the highly educated floating population is helpful for the city to attract and retain talents.From the perspective of social integration,using CMDS 2017 data and taking Guangdong Province for example,this paper studies the influencing factors of long-term residence intention through SPSS logistic regression,taking intra-provincial and inter-provincial floating population with a bachelor’s degree or above as sample.The main conclusions are:(1)Marital and childbearing status is the primitive influencing factor of long-term residence intention among intra-provincial and inter-provincial floating population.Samples with high income,under social insurance system,being female and having non-agricultural hukou,are tend to prefer long-term residence.Samples who connect with the locals and participate in social public welfare are more likely to stay.(2)Personal age and city livability have a significant positive impact on the long-term residence intention of the inter-provincial highly educated floating population,but agricultural hukou and self-employed laborer status will weaken the long-term residence intention of this group.(3)Participation in townsmen/alumni association has a positive effect on the long-term residence intention of the intra-provincial highly educated floating population,and connection with outlanders also promotes the long-term residence intention of this group.(4)The long-term residence intention of inter-provincial highly educated floating population is usually based on reality,therefore they pay more attention to the development,changes,and livability of the destination city.However,the long-term residence intention of intra-provincial highly educated floating population is usually based on perception,so they pay more attention to whether they like the city.Compared with intra-provincial flows,inter-provincial flows have higher economic and emotional migration costs,more institutional barriers,and more life adaptation problems.Therefore,the government should introduce targeted measures to promote social integration and improve long-term residence intention.
基金supported jointly by the Natural Science Foundation of China (No.41807041)the Ninth Batch of Key Disciplines in Henan Province—Mechanical Design,Manufacturing and Automation (JG[2018]No.119).
文摘To determine suitable thresholds for deficit irrigation of winter wheat in the well-irrigated area of the Huang-Huai-Hai Plain,we investigated the effects of different deficit irrigation lower limits and quotas on the photosynthetic characteristics and grain yield of winter wheat.Four irrigation lower limits were set for initiating irrigation(i.e.,light drought(LD,50%,55%,60%and 50%of field holding capacity(FC)at the seedling-regreening,jointing,heading and filling-ripening stages,respectively),medium drought(MD,40%,50%,55%and 45%of FC at the same stages,respectively),adequate moisture(CK1,60%,65%,70%and 60%of FC at the same stages,respectively),heavy drought(CK2,35%,40%,45%and 40%of FC at the same stages,respectively))and five irrigation quota per event(30,60,90,120 and 180 mm)were set for each lower limit.We found that the increase of drought stress is conducive to normal photosynthesis of winter wheat leaves which is supported by the following findings.First,photosynthetic rate(Pn)of LD60 treatment was higher than that of LD30,LD90,LD120,LD180,MD30,MD60,MD90,MD120 and MD180.Then,Under the 90 mm irrigation quota treatment,the yield of winter wheat basically increased with the increase of irrigation’s lower limit.Moreover,With the increase in irrigation quota,the yield of winter wheat increased,and the water use efficiency(WUE)of winter wheat increased at first and then decreased.In addition,compared with the LD30,MD30,MD60,MD90,MD120,and MD180,the yield of winter wheat in LD60 treatment increased by about 3.23%(3-year average),32.3%,19.9%,11.7%,10.1%,and 14.6%.At the same time,the WUE with LD60 treatment of winter wheat was significantly higher than LD90,LD120,LD180,MD30,MD60,MD90,MD120,MD180 treatments.There was a positive correlation between soil volumetric water content and Pn and between yield and Pn.The key period for yield formation in winter wheat is 180 days after sowing.In conclusion,to achieve the dual goals of stable winter wheat yield and efficient utilization of water resources in this region,the suitable threshold for initiating deficit irrigation of winter wheat is the LD60 treatment.This conclusion provides data support for water-saving and stable yield of winter wheat in this area.