With the continuous promotion of computer technology, the application system of virtual simulation technology has been further optimized and improved, and has been widely used in various fields of social development, ...With the continuous promotion of computer technology, the application system of virtual simulation technology has been further optimized and improved, and has been widely used in various fields of social development, such as urban construction, interior design, industrial simulation and tourism teaching. China's three-dimensional animation production started relatively late, but has achieved good results with the support of related advanced technology in the process of development. Computer virtual simulation technology is an important technical support in the production of three-dimensional animation. In this paper, firstly, the related content of computer virtual simulation technology was introduced. Then, the specific application of this technology in the production of three-dimensional animation was further elaborated, so as to provide some reference for the improvement of the production effect of three-dimensional animation in the future.展开更多
A comprehensive analysis on the change of the total grain production and the temporal and spatial change of three main crops production（including wheat,maize and rice）,as well as the transfer trace of the center gra...A comprehensive analysis on the change of the total grain production and the temporal and spatial change of three main crops production（including wheat,maize and rice）,as well as the transfer trace of the center gravity of grain production in China were analyzed to reveal the overall developing trend of the grain production,explore the reasons and finally propose the corresponding suggestions and strategies to cope with the situation.展开更多
The vast area and marked variation of China make it difficult to predict the impact of climate changes on rice productivity in different regions.Therefore,analyzing the spatial and temporal characteristics of rice pot...The vast area and marked variation of China make it difficult to predict the impact of climate changes on rice productivity in different regions.Therefore,analyzing the spatial and temporal characteristics of rice potential productivity and predicting the possible yield increment in main rice production regions of China is important for guiding rice production and ensuring food security.Using meteorological data of main rice production regions from 1961 to 1970（the 1960s） and from 1996 to 2005（the 2000s） provided by 333 stations,the potential photosynthetic,photo-thermal and climatic productivities in rice crop of the 1960s and 2000s in main rice production regions of China were predicted,and differences in the spatial and temporal distribution characteristics between two decades were analyzed.Additionally,the potential yield increment based on the high yield target and actual yield of rice in the 2000s were predicted.Compared with the 1960s,the potential photosynthetic productivity of the 2000s was seen to have decreased by 5.40%,with rates in northeastern and southwestern China found to be lower than those in central and southern China.The potential photo-thermal productivity was generally seen to decrease（2.56%） throughout main rice production regions,decreasing most in central and southern China.However,an increase was seen in northeastern and southwestern China.The potential climatic productivity was observed to be lower（7.44%） in the 2000s compared to the 1960s,but increased in parts of central and southern China.The potential yield increment from the actual yield to high yield target in the 2000s were no more than 6×103 kg ha-1 and ranged from 6×103 to 12×103 kg ha-1 in most of the single-and double-cropping rice growing regions,respectively.The yield increasing potential from the high yield target to the potential photo-thermal productivity in 2000s were less than 10×103 kg ha-1 and ranged from 10×103 to 30×103 kg ha-1 in most of the single-and double-cropping rice growing regions,respectively.The potential yield increment contributed by irrigation was between 5×103 and 20×103 kg ha-1,and between 20×103 and 40×103 kg ha-1 in most of the single-and double-cropping rice growing regions,respectively.These findings suggested that the high yield could be optimized by making full use of climatic resources and through a reasonable management plan in rice crop.展开更多
Understanding crop patterns and their changes on regional scale is a critical re- quirement for projecting agro-ecosystem dynamics. However, tools and methods for mapping the distribution of crop area and yield are st...Understanding crop patterns and their changes on regional scale is a critical re- quirement for projecting agro-ecosystem dynamics. However, tools and methods for mapping the distribution of crop area and yield are still lacking. Based on the cross-entropy theory, a spatial production allocation model （SPAM） has been developed for presenting spa- tio-temporal dynamics of maize cropping system in Northeast China during 1980-2010. The simulated results indicated that （1） maize sown area expanded northwards to 48~N before 2000, after that the increased sown area mainly occurred in the central and southern parts of Northeast China. Meanwhile, maize also expanded eastwards to 127°E and lower elevation （less than 100 m） as well as higher elevation （mainly distributed between 200 m and 350 m）; （2） maize yield has been greatly promoted for most planted area of Northeast China, espe- cially in the planted zone between 42°N and 48°N, while the yield increase was relatively homogeneous without obvious longitudinal variations for whole region; （3） maize planting density increased gradually to a moderately high level over the investigated period, which reflected the trend of aggregation of maize cultivation driven by market demand.展开更多
With the rapid urbanization process,the space of traditional villages in China is undergoing significant changes.Studying the spatial evolution of traditional villages is significant in promoting rural spatial transfo...With the rapid urbanization process,the space of traditional villages in China is undergoing significant changes.Studying the spatial evolution of traditional villages is significant in promoting rural spatial transformation and realizing rural revitalization and sustainable rural development.Based on the traceability analysis of spatial production theory,this paper constructed an analytical framework for the spatial production evolution of traditional villages,analyzed the spatial evolution process and characteristics of traditional villages by using buffer analysis,spatial syntax,and other research methods,and revealed the characteristics of the spatial production evolution of traditional villages and the driving mechanism.The results show that:(1)The village spatial formation and development follow the village life cycle theory and usually develop from embryonic villages to diversified and integrated villages;(2)The evolution of village spatial production is characterized by the diversity of material space,the sublimation of daily life space,and the integration of social system space and generalization of emotional space;(3)The evolution of village spatial production from backward and poor village to ecologically well-off village is influenced by a combination of factors;(4)The village has formed a spatial structure of"people-land-scape-culture-industry",realized comprehensive reconstruction and spatial reproduction.The study results reflect the spatial evolution characteristics of traditional villages in mountainous areas in a more comprehensive way,which helps to promote the protection and development of traditional villages in mountainous areas and,to a certain extent,provides a reference for the development of rural revitalization.展开更多
Smart cities,a new kind of urbanization,offer a means of achieving the condition in which environmental conservation and economic growth are mutually beneficial.As a result,it is important to think about whether and h...Smart cities,a new kind of urbanization,offer a means of achieving the condition in which environmental conservation and economic growth are mutually beneficial.As a result,it is important to think about whether and how the development of smart cities might support the high-quality growth of urban economies.Based on the panel data of 163 prefecture-level cities in China from 2009–2018,the green total factor productivity(GTFP)of each prefecture-level city is measured using the SBM-GML model,and the appropriate spatial econometric model is screened by various types of tests.The spatial effect of smart city construction on GFTP is studied,and it is concluded that the pilot cities have a significant positive spatial spillover effect.The decomposition econometric model also shows that the pilot cities have a significant positive spatial spillover effect,and it also indicating that the smart city construction can also drive the surrounding cities to jointly improve the quality of economic development.Finally,the robustness of the spatial effect of smart city policy is also verified by changing the spatial measurement model and the type of spatial weight matrix,which also shows that the results of the spatial spillover effect of smart city construction are reliable.展开更多
Based on annual pork yield of each province in 1996-2014,using Gini coefficient and spatial polarization index model,empirical analysis was carried out for spatial imbalance and polarization degree of swine production...Based on annual pork yield of each province in 1996-2014,using Gini coefficient and spatial polarization index model,empirical analysis was carried out for spatial imbalance and polarization degree of swine production distribution. Results indicate that there is high imbalance in spatial distribution of swine production. The imbalance takes on first rise then declines with fluctuation,largely because of inter-group gap. From the perspective of regions,the regions with balanced grain production have the highest imbalance in swine production,followed by main sales regions,and the main grain production regions have the lowest imbalance. The polarization index indicates that the overall polarization degree of the spatial distribution of swine production takes on a growing trend,and that of each functional region of grain production is also growing.展开更多
In this work,based on the role of pre-ionization of the non-uniform electric field and its effect of reducing the collisional ionization coefficient,a diffuse dielectric barrier discharge plasma is formed in the open ...In this work,based on the role of pre-ionization of the non-uniform electric field and its effect of reducing the collisional ionization coefficient,a diffuse dielectric barrier discharge plasma is formed in the open space outside the electrode structure at a lower voltage by constructing a three-dimensional non-uniform spatial electric field using a contact electrode structure.The air purification study is also carried out.Firstly,a contact electrode structure is constructed using a three-dimensional wire electrode.The distribution characteristics of the spatial electric field formed by this electrode structure are analyzed,and the effects of the non-uniform electric field and the different angles of the vertical wire on the generation of three-dimensional spatial diffuse discharge are investigated.Secondly,the copper foam contact electrode structure is constructed using copper foam material,and the effects of different mesh sizes on the electric field distribution are analyzed.The results show that as the mesh size of the copper foam becomes larger,a strong electric field region exists not only on the surface of the insulating layer,but also on the surface of the vertical wires inside the copper foam,i.e.,the strong electric field region shows a three-dimensional distribution.Besides,as the mesh size increases,the area of the vertical strong electric field also increases.However,the electric field strength on the surface of the insulating layer gradually decreases.Therefore,the appropriate mesh size can effectively increase the discharge area,which is conducive to improving the air purification efficiency.Finally,a highly permeable stacked electrode structure of multilayer wire-copper foam is designed.In combination with an ozone treatment catalyst,an air purification device is fabricated,and the air purification experiment is carried out.展开更多
In this article, our research aims to set up a geo-decisional system, more precisely we are particularly interested in the spatial analysis system of agricultural production in Madagascar. For this, we used the spatia...In this article, our research aims to set up a geo-decisional system, more precisely we are particularly interested in the spatial analysis system of agricultural production in Madagascar. For this, we used the spatial data warehouse technique based on the SOLAP spatial analysis tool. After having defined the concepts underlying these systems, we propose to address the research issues related to them from four points of view: needs study of the Malagasy Ministry of Agriculture, modeling of a multidimensional conceptual model according to the MultiDim model and the implementation of the system studied using GeoKettle, PostGIS, GeoServer, SPAGO BI and Géomondrian technologies. This new system helps improve the decision-making process for agricultural production in Madagascar.展开更多
For forward-looking array synthetic aperture radar(FASAR),the scattering intensity of ground scatterers fluctuates greatly since there are kinds of vegetations and topography on the surface of the ground,and thus the ...For forward-looking array synthetic aperture radar(FASAR),the scattering intensity of ground scatterers fluctuates greatly since there are kinds of vegetations and topography on the surface of the ground,and thus the signal-to-noise ratio(SNR)of its echo signals corresponding to different vegetations and topography also varies obviously.Owing to the reason known to all,the performance of the sparse reconstruction of compressed sensing(CS)becomes worse in the case of lower SNR,and the quality of the sparse three-dimensional imaging for FASAR would be affected significantly in the practical application.In this paper,the spatial continuity of the ground scatterers is introduced to the sparse recovery algorithm of CS in the threedimensional imaging for FASAR,in which the weighted least square method of the cubic interpolation is used to filter out the bad and isolated scatterer.The simulation results show that the proposed method can realize the sparse three-dimensional imaging of FASAR more effectively in the case of low SNR.展开更多
In response to the strategic call for the " Great Protection" of the Yangtze River Economic Belt and to fulfill the important historical tasks assigned by the state to the provinces and cities of the area,th...In response to the strategic call for the " Great Protection" of the Yangtze River Economic Belt and to fulfill the important historical tasks assigned by the state to the provinces and cities of the area,the Yangtze River Economic Belt is adjusting the agricultural industry structure,optimizing the input-output ratio,and ensuring stable and sustainable agricultural production. Based on the combination of the three-stage Data Envelopment Analysis( DEA) model and cluster analysis,this study examined the Yangtze River Economic Belt from 2008 to 2018 to measure its agricultural production efficiency and to analyze its temporal and spatial characteristics. Studies showed that exogenous environmental factors significantly( P < 5%) impacted agricultural production efficiency in the Yangtze River Economic Zone,and there were temporal and spatial differences. These included:(1) after excluding environmental factors,the overall agricultural production efficiency of the Yangtze River Economic Zone had improved. Sichuan Province and Jiangsu Province were at the forefront of efficiency,whereas the agricultural production efficiency of Shanghai had declined obviously.(2) The agricultural production efficiency of the Yangtze River Economic Belt varied year by year,with fluctuating development. The middle reaches of the Yangtze River had advanced agricultural production efficiency more than the upstream and downstream regions,and the agricultural production efficiency of the individual provinces did not match their economic and social development.(3) Increases in labor,land,irrigation,and other input factors increased agriculture production efficiency,and there was no correlation between fiscal investment,per capita gross domestic product( GDP) and agricultural production efficiency,while the disaster-affected area had a significantly negative impact on agricultural production efficiency.展开更多
Taking Zhaoyu Historical City in Qixian County as an example,this paper explores the production process of tourism space in Zhaoyu Historical City in the context of consumption,based on Lefebvre's triadic dialecti...Taking Zhaoyu Historical City in Qixian County as an example,this paper explores the production process of tourism space in Zhaoyu Historical City in the context of consumption,based on Lefebvre's triadic dialectic theory.The study reveals that,driven by the development of tourism,subjects such as the government and planners possess absolute dominance over spatial representations,while residents demonstrate receptive and adaptive action strategies and social relations are reproduced,presenting a harmonious state.Further exploring the tourism community in the environmental performance of the subject of action,social relations,consumption demand,daily life practice,cultural capital,etc.,the daily life practice of the tourism community has transcended the original logic of tourism spatial production and has a certain extension.The mechanism analysis in this paper can help guide the healthy development of tourism space in the neighboring historical cities or communities and achieve the dual purpose of promoting the economic development of the community and heritage protection.展开更多
An integration processing system of three-dimensional laser scanning information visualization in goaf was developed. It is provided with multiple functions, such as laser scanning information management for goaf, clo...An integration processing system of three-dimensional laser scanning information visualization in goaf was developed. It is provided with multiple functions, such as laser scanning information management for goaf, cloud data de-noising optimization, construction, display and operation of three-dimensional model, model editing, profile generation, calculation of goaf volume and roof area, Boolean calculation among models and interaction with the third party soft ware. Concerning this system with a concise interface, plentiful data input/output interfaces, it is featured with high integration, simple and convenient operations of applications. According to practice, in addition to being well-adapted, this system is favorably reliable and stable.展开更多
Thornthwaite Memorial model and other statistic methods were used to calculate the climate-productivity of plants with the meteorological data from 1961 to 2007 at 9 stations distributed on Inner Mongolia desert stepp...Thornthwaite Memorial model and other statistic methods were used to calculate the climate-productivity of plants with the meteorological data from 1961 to 2007 at 9 stations distributed on Inner Mongolia desert steppe.The spatial and temporal variation characteristics of climate-productivity were analyzed by using the methods of the tendency rate of the climate trend,accumulative anomaly,and spatial difference and so on.The results showed that the climate-productivity kept linear increased trend over Inner Mongolia desert steppe in recent 47 years,but not significant.In spatial distribution,the climate-productivity reduced with the increased latitude.The climate-productivity in southwest part of Inner Mongolia desert steppe was growing while that in the southeast was reducing.The variation rate of the climate-productivity increased from the northwest part to the southeast part of Inner Mongolia desert steppe.In recent 47 years,the climate-productivity in southeast Jurh underwent the greatest decreasing extent,and the region was the sensitive area of the climate-productivity variation.展开更多
Rice＇s spatial-temporal distributions, which are critical for agricultural, environ- mental and food security research, are affected by natural conditions as well as socio-eco- nomic developments. Based on multi-sour...Rice＇s spatial-temporal distributions, which are critical for agricultural, environ- mental and food security research, are affected by natural conditions as well as socio-eco- nomic developments. Based on multi-source data, an effective model named the Spatial Production Allocation Model （SPAM） which integrates arable land distribution, administrative unit statistics of crop data, agricultural irrigation data and crop suitability data, was used to get a series of spatial distributions of rice area and production with 10-km pixels at a national scale -it was applied from the early 1980s onwards and used to analyze the pattern of spatial and temporal changes. The results show that significant changes occurred in rice in China during 1980-2010. Overall, more than 50% of the rice area decreased, while nearly 70% of rice production increased in the change region during 1980-2010. Spatially, most of the increased area and production were in Northeast China, especially, in Jilin and Heilongjiang; most of the decreased area and production were located in Southeast China, especially, in regions of rapidly urbanization in Guangdong, Fujian and Zhejiang. Thus, the centroid of rice area was moved northeast approximately 230 km since 1980, and rice production about 320 km, which means rice production moved northeastward faster than rice area because of the significant rice yield increase in Northeast China. The results also show that rice area change had a decisive impact on rice production change. About 54.5% of the increase in rice pro- duction is due to the expansion of sown area, while around 83.2% of the decrease in rice production is due to contraction of rice area. This implies that rice production increase may be due to area expansion and other non-area factors, but reduced rice production could largely be attributed to rice area decrease.展开更多
Despite the improvement in cultivar characters and management practices, large gaps between the attainable and potential yields still exist in winter wheat of China. Quantifying the crop potential yield is essential f...Despite the improvement in cultivar characters and management practices, large gaps between the attainable and potential yields still exist in winter wheat of China. Quantifying the crop potential yield is essential for estimating the food production capacity and improving agricultural policies to ensure food security. Gradually descending models and geographic infor- mation system （GIS） technology were employed to characterize the spatial variability of potential yields and yield gaps in winter wheat across the main production region of China. The results showed that during 2000-2010, the average potential yield limited by thermal resource （YGT） was 23.2 Mg ha-1, with larger value in the northern area relative to the southern area. The potential yield limited by the water supply （YGw） generally decreased from north to south, with an average value of 1.9 Mg ha-1 across the entire study region. The highest YGw in the north sub-region （NS） implied that the irrigation and drainage conditions in this sub-region must be improved. The averaged yield loss of winter wheat from nutrient deficiency （YGH） varied between 2.1 and 3.1 Mg ha-1 in the study area, which was greater than the yield loss caused by water limitation. The potential decrease in yield from photo-thermal-water-nutrient-limited production to actual yield （YGo） was over 6.0 Mg ha-1, ranging from 4.9 to 8.3 Mg ha^-1 across the entire study region, and it was more obvious in the southern area than in the northern area. These findings suggest that across the main winter wheat production region, the highest yield gap was induced by thermal resources, followed by other factors, such as the level of farming technology, social policy and economic feasibility. Furthermore, there are opportunities to narrow the yield gaps by making full use of climatic resources and developing a reasonable production plan for winter wheat crops. Thus, meeting the challenges of food security and sustainability in the coming decades is possible but will require considerable changes in water and nutrient management and socio-economic policies.展开更多
Rice(Oryza sativa L.) is the most important staple crop of China, and its production is related to both natural condition and human activities. It is fundamental to comprehensively assess the influence of terrain cond...Rice(Oryza sativa L.) is the most important staple crop of China, and its production is related to both natural condition and human activities. It is fundamental to comprehensively assess the influence of terrain conditions on rice production to ensure a steady increase in rice production. Although many studies have focused on the impact of one or several specific factors on crop production, few studies have investigated the direct influence of terrain conditions on rice production. Therefore, we selected Hunan Province, one of the major rice-producing areas in China, which exhibits complex terrain conditions, as our study area. Based on remote sensing data and statistical data, we applied spatial statistical analysis to explore the effects of terrain factors on rice production in terms of the following three aspects: the spatial patterns of paddy fields, the rice production process and the final yield. We found that 1) terrain has a significant impact on the spatial distribution of paddy fields at both the regional scale and the county scale; 2) terrain controls the distribution of temperature, sunlight and soil, and these three environmental factors consequently directly impact rice growth; 3) compared with the patterns of paddy fields and the rice production process, the influences of terrain factors on the rice yield are not as evident, with the exception of elevation; and 4) the spatial distribution of paddy fields mismatched that of production resources due to terrain factors. Our results strongly suggest that managers should scientifically guide farmers to choose suitable varieties and planting systems and allocate rice production resources in the northern plain regions to ensure food security.展开更多
Straightness error is an important parameter in measuring high-precision shafts. New generation geometrical product speeifieation（GPS） requires the measurement uncertainty characterizing the reliability of the resul...Straightness error is an important parameter in measuring high-precision shafts. New generation geometrical product speeifieation（GPS） requires the measurement uncertainty characterizing the reliability of the results should be given together when the measurement result is given. Nowadays most researches on straightness focus on error calculation and only several research projects evaluate the measurement uncertainty based on ＂The Guide to the Expression of Uncertainty in Measurement（GUM）＂. In order to compute spatial straightness error（SSE） accurately and rapidly and overcome the limitations of GUM, a quasi particle swarm optimization（QPSO） is proposed to solve the minimum zone SSE and Monte Carlo Method（MCM） is developed to estimate the measurement uncertainty. The mathematical model of minimum zone SSE is formulated. In QPSO quasi-random sequences are applied to the generation of the initial position and velocity of particles and their velocities are modified by the constriction factor approach. The flow of measurement uncertainty evaluation based on MCM is proposed, where the heart is repeatedly sampling from the probability density function（PDF） for every input quantity and evaluating the model in each case. The minimum zone SSE of a shaft measured on a Coordinate Measuring Machine（CMM） is calculated by QPSO and the measurement uncertainty is evaluated by MCM on the basis of analyzing the uncertainty contributors. The results show that the uncertainty directly influences the product judgment result. Therefore it is scientific and reasonable to consider the influence of the uncertainty in judging whether the parts are accepted or rejected, especially for those located in the uncertainty zone. The proposed method is especially suitable when the PDF of the measurand cannot adequately be approximated by a Gaussian distribution or a scaled and shifted t-distribution and the measurement model is non-linear.展开更多
With the global economy increasingly dependent on innovation,urban discourse has shifted to consider what kinds of spatial designs may best nurture innovation.We examined the relationship between the built environment...With the global economy increasingly dependent on innovation,urban discourse has shifted to consider what kinds of spatial designs may best nurture innovation.We examined the relationship between the built environment and the spatial heterogeneity of regional innovation productivity(RIP)using the example of China's Pearl River Delta(PRD).Based on a spatial database of 522546 patent data from 2017,this study proposed an innovation-based built environment framework with the following five aspects:healthy en-vironment,daily interaction,mixed land use,commuting convenience,and technology atmosphere.Combining negative binomial regression and Geodetector to examine the impact of the built environment on RIP,the results show that the spatial distribution of innovation productivity in the PRD region is extremely uneven.The negative binomial regression results show that the built environment has a significant impact on the spatial differentiation of RIP,and,specifically,that healthy environment,mixed land use,commuting convenience,and technology atmosphere all demonstrate significant positive impacts.Meanwhile,the Geodetector results show that the built environment factor impacts the spatial heterogeneity of RIP to varying degrees,with technology atmosphere demonstrating the greatest impact intensity.We conclude that as regional development discourse shifts focus to the knowledge and innovation economy,the innovation-oriented design and updating of built environments will become extremely important to policymakers.展开更多
We developed a sophisticated method to depict the spatial and seasonal characterization of net primary productivity (NPP) and climate variables. The role of climate variability in the seasonal variation of NPP exerts ...We developed a sophisticated method to depict the spatial and seasonal characterization of net primary productivity (NPP) and climate variables. The role of climate variability in the seasonal variation of NPP exerts delayed and continuous effects. This study expands on this by mapping the seasonal characterization of NPP and climate variables from space using geographic information system (GIS) technology at the pixel level. Our approach was developed in southeastern China using moderate-resolution imaging spectroradiometer (MODIS) data. The results showed that air temperature,precipitation and sunshine percentage contributed significantly to seasonal variation of NPP. In the northern portion of the study area,a significant positive 32-d lagged correlation was observed between seasonal variation of NPP and climate (P<0.01),and the influences of changing climate on NPP lasted for 48 d or 64 d. In central southeastern China,NPP showed 16-d,48-d,and 96-d lagged correlation with air temperature,precipitation,and sunshine percentage,respectively (P<0.01); the influences of air temperature and precipitation on NPP lasted for 48 d or 64 d,while sunshine influence on NPP only persisted for 16 d. Due to complex topography and vegetation distribution in the southern part of the study region,the spatial patterns of vegetation-climate relationship became complicated and diversiform,especially for precipitation influences on NPP. In the northern part of the study area,all vegetation NPP had an almost similar response to seasonal variation of air temperature except for broad crops. The impacts of seasonal variation of precipitation and sunshine on broad and cereal crop NPP were slightly different from other vegetation NPP.展开更多
文摘With the continuous promotion of computer technology, the application system of virtual simulation technology has been further optimized and improved, and has been widely used in various fields of social development, such as urban construction, interior design, industrial simulation and tourism teaching. China's three-dimensional animation production started relatively late, but has achieved good results with the support of related advanced technology in the process of development. Computer virtual simulation technology is an important technical support in the production of three-dimensional animation. In this paper, firstly, the related content of computer virtual simulation technology was introduced. Then, the specific application of this technology in the production of three-dimensional animation was further elaborated, so as to provide some reference for the improvement of the production effect of three-dimensional animation in the future.
基金Supported by National Scientific and Technological Supporting Project(2006BAD20B05)~~
文摘A comprehensive analysis on the change of the total grain production and the temporal and spatial change of three main crops production（including wheat,maize and rice）,as well as the transfer trace of the center gravity of grain production in China were analyzed to reveal the overall developing trend of the grain production,explore the reasons and finally propose the corresponding suggestions and strategies to cope with the situation.
基金supported by the Key Technologies R&D Program of China during the 12th Five-Year Plan period (2011BAD21B03)the National Basic Research Program of China (2009CB118608)the Priority Academic Program Development of Jiangsu Higher Education Institutions, China (PAPD)
文摘The vast area and marked variation of China make it difficult to predict the impact of climate changes on rice productivity in different regions.Therefore,analyzing the spatial and temporal characteristics of rice potential productivity and predicting the possible yield increment in main rice production regions of China is important for guiding rice production and ensuring food security.Using meteorological data of main rice production regions from 1961 to 1970（the 1960s） and from 1996 to 2005（the 2000s） provided by 333 stations,the potential photosynthetic,photo-thermal and climatic productivities in rice crop of the 1960s and 2000s in main rice production regions of China were predicted,and differences in the spatial and temporal distribution characteristics between two decades were analyzed.Additionally,the potential yield increment based on the high yield target and actual yield of rice in the 2000s were predicted.Compared with the 1960s,the potential photosynthetic productivity of the 2000s was seen to have decreased by 5.40%,with rates in northeastern and southwestern China found to be lower than those in central and southern China.The potential photo-thermal productivity was generally seen to decrease（2.56%） throughout main rice production regions,decreasing most in central and southern China.However,an increase was seen in northeastern and southwestern China.The potential climatic productivity was observed to be lower（7.44%） in the 2000s compared to the 1960s,but increased in parts of central and southern China.The potential yield increment from the actual yield to high yield target in the 2000s were no more than 6×103 kg ha-1 and ranged from 6×103 to 12×103 kg ha-1 in most of the single-and double-cropping rice growing regions,respectively.The yield increasing potential from the high yield target to the potential photo-thermal productivity in 2000s were less than 10×103 kg ha-1 and ranged from 10×103 to 30×103 kg ha-1 in most of the single-and double-cropping rice growing regions,respectively.The potential yield increment contributed by irrigation was between 5×103 and 20×103 kg ha-1,and between 20×103 and 40×103 kg ha-1 in most of the single-and double-cropping rice growing regions,respectively.These findings suggested that the high yield could be optimized by making full use of climatic resources and through a reasonable management plan in rice crop.
基金Foundation： National Natural Science Foundation of China, No.41171328, No.41201184, No.41101537 National Basic Program of China, No.2010CB951502
文摘Understanding crop patterns and their changes on regional scale is a critical re- quirement for projecting agro-ecosystem dynamics. However, tools and methods for mapping the distribution of crop area and yield are still lacking. Based on the cross-entropy theory, a spatial production allocation model （SPAM） has been developed for presenting spa- tio-temporal dynamics of maize cropping system in Northeast China during 1980-2010. The simulated results indicated that （1） maize sown area expanded northwards to 48~N before 2000, after that the increased sown area mainly occurred in the central and southern parts of Northeast China. Meanwhile, maize also expanded eastwards to 127°E and lower elevation （less than 100 m） as well as higher elevation （mainly distributed between 200 m and 350 m）; （2） maize yield has been greatly promoted for most planted area of Northeast China, espe- cially in the planted zone between 42°N and 48°N, while the yield increase was relatively homogeneous without obvious longitudinal variations for whole region; （3） maize planting density increased gradually to a moderately high level over the investigated period, which reflected the trend of aggregation of maize cultivation driven by market demand.
基金supported by the National Natural Science Foundation of China(Grant No.42061035)the Guizhou Provincial Program on Commercialization of Scientific and Technological Achievements([2022]010).
文摘With the rapid urbanization process,the space of traditional villages in China is undergoing significant changes.Studying the spatial evolution of traditional villages is significant in promoting rural spatial transformation and realizing rural revitalization and sustainable rural development.Based on the traceability analysis of spatial production theory,this paper constructed an analytical framework for the spatial production evolution of traditional villages,analyzed the spatial evolution process and characteristics of traditional villages by using buffer analysis,spatial syntax,and other research methods,and revealed the characteristics of the spatial production evolution of traditional villages and the driving mechanism.The results show that:(1)The village spatial formation and development follow the village life cycle theory and usually develop from embryonic villages to diversified and integrated villages;(2)The evolution of village spatial production is characterized by the diversity of material space,the sublimation of daily life space,and the integration of social system space and generalization of emotional space;(3)The evolution of village spatial production from backward and poor village to ecologically well-off village is influenced by a combination of factors;(4)The village has formed a spatial structure of"people-land-scape-culture-industry",realized comprehensive reconstruction and spatial reproduction.The study results reflect the spatial evolution characteristics of traditional villages in mountainous areas in a more comprehensive way,which helps to promote the protection and development of traditional villages in mountainous areas and,to a certain extent,provides a reference for the development of rural revitalization.
基金Jilin Province Social Science Project:Path Analysis and Empirical Research on Empowering Rural Industry Integration with Digital Economy in Jilin Province 2023B40Key Project of Education Science Planning in Jilin Province:Exploration of Talent Training Model for Economic Statistics Majors in Universities Based on OBE Theory-Taking Jilin Jianzhu University as an Example.ZD22028.
文摘Smart cities,a new kind of urbanization,offer a means of achieving the condition in which environmental conservation and economic growth are mutually beneficial.As a result,it is important to think about whether and how the development of smart cities might support the high-quality growth of urban economies.Based on the panel data of 163 prefecture-level cities in China from 2009–2018,the green total factor productivity(GTFP)of each prefecture-level city is measured using the SBM-GML model,and the appropriate spatial econometric model is screened by various types of tests.The spatial effect of smart city construction on GFTP is studied,and it is concluded that the pilot cities have a significant positive spatial spillover effect.The decomposition econometric model also shows that the pilot cities have a significant positive spatial spillover effect,and it also indicating that the smart city construction can also drive the surrounding cities to jointly improve the quality of economic development.Finally,the robustness of the spatial effect of smart city policy is also verified by changing the spatial measurement model and the type of spatial weight matrix,which also shows that the results of the spatial spillover effect of smart city construction are reliable.
基金Supported by Key Project of National Social Science Foundation(12&ZD048)
文摘Based on annual pork yield of each province in 1996-2014,using Gini coefficient and spatial polarization index model,empirical analysis was carried out for spatial imbalance and polarization degree of swine production distribution. Results indicate that there is high imbalance in spatial distribution of swine production. The imbalance takes on first rise then declines with fluctuation,largely because of inter-group gap. From the perspective of regions,the regions with balanced grain production have the highest imbalance in swine production,followed by main sales regions,and the main grain production regions have the lowest imbalance. The polarization index indicates that the overall polarization degree of the spatial distribution of swine production takes on a growing trend,and that of each functional region of grain production is also growing.
基金supported by the Fundamental Research Funds for the Central Universities(No.2022YJS094)。
文摘In this work,based on the role of pre-ionization of the non-uniform electric field and its effect of reducing the collisional ionization coefficient,a diffuse dielectric barrier discharge plasma is formed in the open space outside the electrode structure at a lower voltage by constructing a three-dimensional non-uniform spatial electric field using a contact electrode structure.The air purification study is also carried out.Firstly,a contact electrode structure is constructed using a three-dimensional wire electrode.The distribution characteristics of the spatial electric field formed by this electrode structure are analyzed,and the effects of the non-uniform electric field and the different angles of the vertical wire on the generation of three-dimensional spatial diffuse discharge are investigated.Secondly,the copper foam contact electrode structure is constructed using copper foam material,and the effects of different mesh sizes on the electric field distribution are analyzed.The results show that as the mesh size of the copper foam becomes larger,a strong electric field region exists not only on the surface of the insulating layer,but also on the surface of the vertical wires inside the copper foam,i.e.,the strong electric field region shows a three-dimensional distribution.Besides,as the mesh size increases,the area of the vertical strong electric field also increases.However,the electric field strength on the surface of the insulating layer gradually decreases.Therefore,the appropriate mesh size can effectively increase the discharge area,which is conducive to improving the air purification efficiency.Finally,a highly permeable stacked electrode structure of multilayer wire-copper foam is designed.In combination with an ozone treatment catalyst,an air purification device is fabricated,and the air purification experiment is carried out.
文摘In this article, our research aims to set up a geo-decisional system, more precisely we are particularly interested in the spatial analysis system of agricultural production in Madagascar. For this, we used the spatial data warehouse technique based on the SOLAP spatial analysis tool. After having defined the concepts underlying these systems, we propose to address the research issues related to them from four points of view: needs study of the Malagasy Ministry of Agriculture, modeling of a multidimensional conceptual model according to the MultiDim model and the implementation of the system studied using GeoKettle, PostGIS, GeoServer, SPAGO BI and Géomondrian technologies. This new system helps improve the decision-making process for agricultural production in Madagascar.
基金supported by the National Natural Science Foundation of China(61640006)the Natural Science Foundation of Shannxi Province,China(2019JM-386).
文摘For forward-looking array synthetic aperture radar(FASAR),the scattering intensity of ground scatterers fluctuates greatly since there are kinds of vegetations and topography on the surface of the ground,and thus the signal-to-noise ratio(SNR)of its echo signals corresponding to different vegetations and topography also varies obviously.Owing to the reason known to all,the performance of the sparse reconstruction of compressed sensing(CS)becomes worse in the case of lower SNR,and the quality of the sparse three-dimensional imaging for FASAR would be affected significantly in the practical application.In this paper,the spatial continuity of the ground scatterers is introduced to the sparse recovery algorithm of CS in the threedimensional imaging for FASAR,in which the weighted least square method of the cubic interpolation is used to filter out the bad and isolated scatterer.The simulation results show that the proposed method can realize the sparse three-dimensional imaging of FASAR more effectively in the case of low SNR.
基金Supported by the Strategic Leading Science and Technology Project (Class A)of Chinese Academy of Sciences (XDA23020101)the National Natural Science Foundation of China (41801129)。
文摘In response to the strategic call for the " Great Protection" of the Yangtze River Economic Belt and to fulfill the important historical tasks assigned by the state to the provinces and cities of the area,the Yangtze River Economic Belt is adjusting the agricultural industry structure,optimizing the input-output ratio,and ensuring stable and sustainable agricultural production. Based on the combination of the three-stage Data Envelopment Analysis( DEA) model and cluster analysis,this study examined the Yangtze River Economic Belt from 2008 to 2018 to measure its agricultural production efficiency and to analyze its temporal and spatial characteristics. Studies showed that exogenous environmental factors significantly( P < 5%) impacted agricultural production efficiency in the Yangtze River Economic Zone,and there were temporal and spatial differences. These included:(1) after excluding environmental factors,the overall agricultural production efficiency of the Yangtze River Economic Zone had improved. Sichuan Province and Jiangsu Province were at the forefront of efficiency,whereas the agricultural production efficiency of Shanghai had declined obviously.(2) The agricultural production efficiency of the Yangtze River Economic Belt varied year by year,with fluctuating development. The middle reaches of the Yangtze River had advanced agricultural production efficiency more than the upstream and downstream regions,and the agricultural production efficiency of the individual provinces did not match their economic and social development.(3) Increases in labor,land,irrigation,and other input factors increased agriculture production efficiency,and there was no correlation between fiscal investment,per capita gross domestic product( GDP) and agricultural production efficiency,while the disaster-affected area had a significantly negative impact on agricultural production efficiency.
文摘Taking Zhaoyu Historical City in Qixian County as an example,this paper explores the production process of tourism space in Zhaoyu Historical City in the context of consumption,based on Lefebvre's triadic dialectic theory.The study reveals that,driven by the development of tourism,subjects such as the government and planners possess absolute dominance over spatial representations,while residents demonstrate receptive and adaptive action strategies and social relations are reproduced,presenting a harmonious state.Further exploring the tourism community in the environmental performance of the subject of action,social relations,consumption demand,daily life practice,cultural capital,etc.,the daily life practice of the tourism community has transcended the original logic of tourism spatial production and has a certain extension.The mechanism analysis in this paper can help guide the healthy development of tourism space in the neighboring historical cities or communities and achieve the dual purpose of promoting the economic development of the community and heritage protection.
基金Project(51274250)supported by the National Natural Science Foundation of ChinaProject(2012BAK09B02-05)supported by the National Key Technology R&D Program during the 12th Five-year Plan of China
文摘An integration processing system of three-dimensional laser scanning information visualization in goaf was developed. It is provided with multiple functions, such as laser scanning information management for goaf, cloud data de-noising optimization, construction, display and operation of three-dimensional model, model editing, profile generation, calculation of goaf volume and roof area, Boolean calculation among models and interaction with the third party soft ware. Concerning this system with a concise interface, plentiful data input/output interfaces, it is featured with high integration, simple and convenient operations of applications. According to practice, in addition to being well-adapted, this system is favorably reliable and stable.
基金Supported by The Inner Mongolia Natural Science Foundation (2009ms0603)Inner Mongolia Scientific Innovation Program (nmqxkjcx200706)Special Fund for Scientific Research in Central Public Welfare Institution Fundamental(Grassland Research Institute of Chinese Academy of Agricultural Science)
文摘Thornthwaite Memorial model and other statistic methods were used to calculate the climate-productivity of plants with the meteorological data from 1961 to 2007 at 9 stations distributed on Inner Mongolia desert steppe.The spatial and temporal variation characteristics of climate-productivity were analyzed by using the methods of the tendency rate of the climate trend,accumulative anomaly,and spatial difference and so on.The results showed that the climate-productivity kept linear increased trend over Inner Mongolia desert steppe in recent 47 years,but not significant.In spatial distribution,the climate-productivity reduced with the increased latitude.The climate-productivity in southwest part of Inner Mongolia desert steppe was growing while that in the southeast was reducing.The variation rate of the climate-productivity increased from the northwest part to the southeast part of Inner Mongolia desert steppe.In recent 47 years,the climate-productivity in southeast Jurh underwent the greatest decreasing extent,and the region was the sensitive area of the climate-productivity variation.
基金National Natural Science Foundation, No.41171382 National Basic Program of China （973 Program）, No.2010CB951502
文摘Rice＇s spatial-temporal distributions, which are critical for agricultural, environ- mental and food security research, are affected by natural conditions as well as socio-eco- nomic developments. Based on multi-source data, an effective model named the Spatial Production Allocation Model （SPAM） which integrates arable land distribution, administrative unit statistics of crop data, agricultural irrigation data and crop suitability data, was used to get a series of spatial distributions of rice area and production with 10-km pixels at a national scale -it was applied from the early 1980s onwards and used to analyze the pattern of spatial and temporal changes. The results show that significant changes occurred in rice in China during 1980-2010. Overall, more than 50% of the rice area decreased, while nearly 70% of rice production increased in the change region during 1980-2010. Spatially, most of the increased area and production were in Northeast China, especially, in Jilin and Heilongjiang; most of the decreased area and production were located in Southeast China, especially, in regions of rapidly urbanization in Guangdong, Fujian and Zhejiang. Thus, the centroid of rice area was moved northeast approximately 230 km since 1980, and rice production about 320 km, which means rice production moved northeastward faster than rice area because of the significant rice yield increase in Northeast China. The results also show that rice area change had a decisive impact on rice production change. About 54.5% of the increase in rice pro- duction is due to the expansion of sown area, while around 83.2% of the decrease in rice production is due to contraction of rice area. This implies that rice production increase may be due to area expansion and other non-area factors, but reduced rice production could largely be attributed to rice area decrease.
基金supported by the National High-Tech R&D Program of China(863 Program,2013AA100404)the National Natural Science Foundation of China(31301234 and 31271616)+1 种基金the National Research Foundation for the Doctoral Program of Higher Education of China(20120097110042)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(PAPD)
文摘Despite the improvement in cultivar characters and management practices, large gaps between the attainable and potential yields still exist in winter wheat of China. Quantifying the crop potential yield is essential for estimating the food production capacity and improving agricultural policies to ensure food security. Gradually descending models and geographic infor- mation system （GIS） technology were employed to characterize the spatial variability of potential yields and yield gaps in winter wheat across the main production region of China. The results showed that during 2000-2010, the average potential yield limited by thermal resource （YGT） was 23.2 Mg ha-1, with larger value in the northern area relative to the southern area. The potential yield limited by the water supply （YGw） generally decreased from north to south, with an average value of 1.9 Mg ha-1 across the entire study region. The highest YGw in the north sub-region （NS） implied that the irrigation and drainage conditions in this sub-region must be improved. The averaged yield loss of winter wheat from nutrient deficiency （YGH） varied between 2.1 and 3.1 Mg ha-1 in the study area, which was greater than the yield loss caused by water limitation. The potential decrease in yield from photo-thermal-water-nutrient-limited production to actual yield （YGo） was over 6.0 Mg ha-1, ranging from 4.9 to 8.3 Mg ha^-1 across the entire study region, and it was more obvious in the southern area than in the northern area. These findings suggest that across the main winter wheat production region, the highest yield gap was induced by thermal resources, followed by other factors, such as the level of farming technology, social policy and economic feasibility. Furthermore, there are opportunities to narrow the yield gaps by making full use of climatic resources and developing a reasonable production plan for winter wheat crops. Thus, meeting the challenges of food security and sustainability in the coming decades is possible but will require considerable changes in water and nutrient management and socio-economic policies.
基金Creative Research Groups of National Natural Science Foundation of China,No.41621061National Natural Science Foundation of China,No.41571493,No.31561143003
文摘Rice(Oryza sativa L.) is the most important staple crop of China, and its production is related to both natural condition and human activities. It is fundamental to comprehensively assess the influence of terrain conditions on rice production to ensure a steady increase in rice production. Although many studies have focused on the impact of one or several specific factors on crop production, few studies have investigated the direct influence of terrain conditions on rice production. Therefore, we selected Hunan Province, one of the major rice-producing areas in China, which exhibits complex terrain conditions, as our study area. Based on remote sensing data and statistical data, we applied spatial statistical analysis to explore the effects of terrain factors on rice production in terms of the following three aspects: the spatial patterns of paddy fields, the rice production process and the final yield. We found that 1) terrain has a significant impact on the spatial distribution of paddy fields at both the regional scale and the county scale; 2) terrain controls the distribution of temperature, sunlight and soil, and these three environmental factors consequently directly impact rice growth; 3) compared with the patterns of paddy fields and the rice production process, the influences of terrain factors on the rice yield are not as evident, with the exception of elevation; and 4) the spatial distribution of paddy fields mismatched that of production resources due to terrain factors. Our results strongly suggest that managers should scientifically guide farmers to choose suitable varieties and planting systems and allocate rice production resources in the northern plain regions to ensure food security.
基金supported by National Natural Science Foundation of China (Grant No. 51075198)Jiangsu Provincial Natural Science Foundation of China (Grant No. BK2010479)+2 种基金Innovation Research of Nanjing Institute of Technology, China (Grant No. CKJ20100008)Jiangsu Provincial Foundation of 333 Talents Engineering of ChinaJiangsu Provincial Foundation of Six Talented Peak of China
文摘Straightness error is an important parameter in measuring high-precision shafts. New generation geometrical product speeifieation（GPS） requires the measurement uncertainty characterizing the reliability of the results should be given together when the measurement result is given. Nowadays most researches on straightness focus on error calculation and only several research projects evaluate the measurement uncertainty based on ＂The Guide to the Expression of Uncertainty in Measurement（GUM）＂. In order to compute spatial straightness error（SSE） accurately and rapidly and overcome the limitations of GUM, a quasi particle swarm optimization（QPSO） is proposed to solve the minimum zone SSE and Monte Carlo Method（MCM） is developed to estimate the measurement uncertainty. The mathematical model of minimum zone SSE is formulated. In QPSO quasi-random sequences are applied to the generation of the initial position and velocity of particles and their velocities are modified by the constriction factor approach. The flow of measurement uncertainty evaluation based on MCM is proposed, where the heart is repeatedly sampling from the probability density function（PDF） for every input quantity and evaluating the model in each case. The minimum zone SSE of a shaft measured on a Coordinate Measuring Machine（CMM） is calculated by QPSO and the measurement uncertainty is evaluated by MCM on the basis of analyzing the uncertainty contributors. The results show that the uncertainty directly influences the product judgment result. Therefore it is scientific and reasonable to consider the influence of the uncertainty in judging whether the parts are accepted or rejected, especially for those located in the uncertainty zone. The proposed method is especially suitable when the PDF of the measurand cannot adequately be approximated by a Gaussian distribution or a scaled and shifted t-distribution and the measurement model is non-linear.
基金Under the auspices of National Natural Science Foundation of China(No.41871150)GDAS7 Project of Science and Technology Development(No.2021GDASYL-20210103004)+2 种基金National Key Research and Development Program(No.2019YFB2103-101)Special Construction Project of Guangdong-Hong Kong-Macao Greater Bay Area Strategic Research Institute(No.2020GDA-SYL-20200201001)Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0301)。
文摘With the global economy increasingly dependent on innovation,urban discourse has shifted to consider what kinds of spatial designs may best nurture innovation.We examined the relationship between the built environment and the spatial heterogeneity of regional innovation productivity(RIP)using the example of China's Pearl River Delta(PRD).Based on a spatial database of 522546 patent data from 2017,this study proposed an innovation-based built environment framework with the following five aspects:healthy en-vironment,daily interaction,mixed land use,commuting convenience,and technology atmosphere.Combining negative binomial regression and Geodetector to examine the impact of the built environment on RIP,the results show that the spatial distribution of innovation productivity in the PRD region is extremely uneven.The negative binomial regression results show that the built environment has a significant impact on the spatial differentiation of RIP,and,specifically,that healthy environment,mixed land use,commuting convenience,and technology atmosphere all demonstrate significant positive impacts.Meanwhile,the Geodetector results show that the built environment factor impacts the spatial heterogeneity of RIP to varying degrees,with technology atmosphere demonstrating the greatest impact intensity.We conclude that as regional development discourse shifts focus to the knowledge and innovation economy,the innovation-oriented design and updating of built environments will become extremely important to policymakers.
基金Project supported by the National High-Tech Research and Development Program (863) of China (No. 2006AA120101)the National Natural Science Foundation of China (Nos. 40871158 and 40875070)the Key Technologies Research and Development Program of China (No. 2006BAD10A01)
文摘We developed a sophisticated method to depict the spatial and seasonal characterization of net primary productivity (NPP) and climate variables. The role of climate variability in the seasonal variation of NPP exerts delayed and continuous effects. This study expands on this by mapping the seasonal characterization of NPP and climate variables from space using geographic information system (GIS) technology at the pixel level. Our approach was developed in southeastern China using moderate-resolution imaging spectroradiometer (MODIS) data. The results showed that air temperature,precipitation and sunshine percentage contributed significantly to seasonal variation of NPP. In the northern portion of the study area,a significant positive 32-d lagged correlation was observed between seasonal variation of NPP and climate (P<0.01),and the influences of changing climate on NPP lasted for 48 d or 64 d. In central southeastern China,NPP showed 16-d,48-d,and 96-d lagged correlation with air temperature,precipitation,and sunshine percentage,respectively (P<0.01); the influences of air temperature and precipitation on NPP lasted for 48 d or 64 d,while sunshine influence on NPP only persisted for 16 d. Due to complex topography and vegetation distribution in the southern part of the study region,the spatial patterns of vegetation-climate relationship became complicated and diversiform,especially for precipitation influences on NPP. In the northern part of the study area,all vegetation NPP had an almost similar response to seasonal variation of air temperature except for broad crops. The impacts of seasonal variation of precipitation and sunshine on broad and cereal crop NPP were slightly different from other vegetation NPP.
