Using gradually regression analysis to establish the driving force model of utilized change of cultivated land in Gonghe County, and using path analysis, correlation analysis, partial correlation analysis and system d...Using gradually regression analysis to establish the driving force model of utilized change of cultivated land in Gonghe County, and using path analysis, correlation analysis, partial correlation analysis and system dynamics method to inspect the effect of driving changing on cultivated land change under different change situations. Driving factors, action mechanism and process of utilized change of cultivated land were analyzed from the county territory scale level. At last, some corresponding policies and measures were put forward.展开更多
Using path analysis, correlation analysis, partial correlation analysis and system dynamics method to study the driving force of cultivated land in Qinghai Lake Area, and using gradually regression analysis to establi...Using path analysis, correlation analysis, partial correlation analysis and system dynamics method to study the driving force of cultivated land in Qinghai Lake Area, and using gradually regression analysis to establish the driving force model of utilized change of cultivated land. Driving factors, action mechanism and process of utilized change of cultivated land were analyzed, and the differences during all factors were compared. The study provides some decision basis for sustainable utilization and management of land resources in Qinghai Lake Area.展开更多
Using Landsat TM data of 1988, 1998 and 2001, the dynamic process of the spatial-temporal characteristics of land use changes during 13 years from 1988 to 2001 in the special economic zone of Xiamen, China was analyze...Using Landsat TM data of 1988, 1998 and 2001, the dynamic process of the spatial-temporal characteristics of land use changes during 13 years from 1988 to 2001 in the special economic zone of Xiamen, China was analyzed to improve understanding and to find the driving forces of land use change so that sustainable land utilization could be practiced. During the 13 years cropland decreased remarkably by nearly 11304.95 ha. The areas of rural-urban construction and water body increased by 10 152.24 ha and 848.94 ha, respectively. From 1988 to 2001, 52.5% of the lost cropland was converted into rural-urban industrial land. Rapid urbanization contributed to a great change in the rate of cropland land use during these years. Land-reclamation also contributed to a decrease in water body area as well as marine ecological and environmental destruction. In the study area 1) urbanization and industrialization, 2) infrastructure and agricultural intensification, 3) increased affluence of the farming community, and 4) policy factors have driven the land use changes. Possible sustainable land use measures included construction of a land management system, land planning, development of potential land resources, new technology applications, and marine ecological and environmental protection.展开更多
Changes of cultivated land patterns caused by major water conservation projects are rarely reported. We selected the Three Gorges Reservoir area in China to study the change in area and landscape pattern of the cultiv...Changes of cultivated land patterns caused by major water conservation projects are rarely reported. We selected the Three Gorges Reservoir area in China to study the change in area and landscape pattern of the cultivated land in the head,central, and tail areas of the reservoir that took place between 1992 and 2015;we then studied the spatial distribution of the cultivated land in the three parts of the reservoir;finally, we studied the driving forces behind the changes in the cultivated land. The results derived are as follows.(1) During the construction of the Three Gorges Project(TGP, 1992–2015), the area of cultivated land around the reservoir decreased by30.23 million ha. This reduction occurred in phases:the most severe change in cultivated land occurred during the later stage of the project(2002–2010);only 0.62 million ha of cultivated land did not change between 1992 and 2015.(2) Spatial pattern analysis showed that the cultivated land in the three parts of the reservoir changed from a northern distribution to a southern distribution;thus, the area of cultivated land in the north decreased over the time period. The area of cultivated land in the head and tail areas decreased by varying degrees, while it increased in the central area over the 23 years, indicating that the change in cultivated land showed regional differences.(3) The TGP, the policy of reverting farmland to forest,and urbanization were the main driving factors for the change of cultivated land, but there were differences in their impacts at different stages.(4) According to the patch dynamics of the land cover change, the degree of change gradually intensified during the early and later stages of the project and then stabilized during the operational period. Our research provides scientific support for the protection of cultivated land resources and food security in the reservoir area and for the coordination of social and economic development, which is of great significance to sustainable development in the reservoir area.展开更多
The decrease of total cultivated area and the lower per capita available arable land resource are now serious problems in Shandong Province, a major agricultural province in China. These problems will become more seri...The decrease of total cultivated area and the lower per capita available arable land resource are now serious problems in Shandong Province, a major agricultural province in China. These problems will become more serious along with the further development of economy. In this paper, based on the statistical information at provincial and county levels, the changes of arable land in Shandong Province and their driving forces during the last 50 years are analyzed. The general changing trends of arable land and per capita available arable land are reducing, and the trends of decrease will continue when the economy is developing. The result of GIS spatial analysis shows that the change of the arable land use in Shandong Province has a regional difference. Eight variables having influences on cultivated land change are analyzed by principal component analysis. The results show that the dynamic development of economy, pressure of social system and progress of scientific techniques in agriculture are the main causes for cultivated land reduction. The principal factors which can be considered as driving forces for arable land change include per capita net living space, total population and per ha grain yield. By using regressive equation, along with analysis on population growth and economic development, cultivated areas in Shandong Province in 2005 and 2010 are predicted respectively. The predicted cultivated areas in Shandong will be 6435.47 thousand hain 2005 and 6336.23 thousand ha in 2010 respectively.展开更多
Based on the plastic deformation theory and energy method, the critical blank-holder forces (BHF) of wrinkling and fracture in the cylindrical cup deep-drawing are analyzed. The verify experiments were performed and c...Based on the plastic deformation theory and energy method, the critical blank-holder forces (BHF) of wrinkling and fracture in the cylindrical cup deep-drawing are analyzed. The verify experiments were performed and compared with the theory analysis results. The predictions agree well with the experiment results. Thus, the validated presenttheoretical analysis model may be applied to determinate the suitable BHF.展开更多
BACKGROUND: The detection of motor evoked potential is utilized to explore neuromuscular finger coordination. The influence of transcranial magnetic stimulation on finger force has been investigated mainly on a singl...BACKGROUND: The detection of motor evoked potential is utilized to explore neuromuscular finger coordination. The influence of transcranial magnetic stimulation on finger force has been investigated mainly on a single finger, and only time-dependent increased target finger force has been detected in the finger force task. OBJECTIVE: To explore the neural mechanism of finger force coordination in the motor cortex by observing the influence of various finger coordination patterns and patterns of transcranial magnetic stimulation (TMS)-induced finger force changes. DESIGN, TIME AND SETTING: Neurophysiological and behavioral study was performed at the Biomedical Engineering Laboratory of Chongqing University from April to June 2008. PARTICIPANTS: A total of 10 healthy, university students, comprising 5 males and 5 females, aged 21-23 years, voluntarily participated in this study. All participants were right-handed, with normal or corrected vision. Individuals with upper limb complaints or other musculoskeletal disorders were excluded. METHODS: A target force-tracking task was conducted on the index finger, the index and middle fingers, and four fingers (index, middle, ring, and little), respectively. Target force trace in a single trial consisted of a 6-second ramp phase, a 20-second constant phase, and a 6-second drop phase. During experimentation, an unpredictable single-pulse TMS (120% motor threshold) was applied to the primary motor cortex (M1) in each phase. MAIN OUTCOME MEASURES: Changes in peak force induced by TMS were obtained for each finger pattern during each force-tracking phase. Differences in force changes were tested between different finger pattems with regard to ramp, constant, and drop phases of target force. RESULTS: Under ramp, constant, and drop phases of target force, the increase in magnetic stimulation-induced finger forces changes positively correlated with the number of fingers involved in the force tracking task. The magnetic stimulation-induced force changes from the index finger were less than the combination of the index and middle fingers or all four fingers under the corresponding target force, and the force changes from the combination of the index and middle fingers were less than all four fingers, Le., index finger 〈 index and middle fingers 〈 four fingers. CONCLUSION: Different neuromuscular mechanisms could be involved in finger force production for different finger combination patterns. Results from the present study suggested that independent motor neurons regulated individual finger force production.展开更多
Based on the remote sensing data of Landsat 5,landscape indexes were used to analyze the land use/cover changes of Xuzhou City during 1994 and 2005,in order to discover the inside driving system.Fourteen social drivin...Based on the remote sensing data of Landsat 5,landscape indexes were used to analyze the land use/cover changes of Xuzhou City during 1994 and 2005,in order to discover the inside driving system.Fourteen social driving forces were chosen according to the PCA theory,and the social driving forces of land use/cover change were analyzed with the help of SPSS software.The result indicated that population,economy,adjustment of agriculture structure were main impact factors of land use/cover changes.展开更多
In this paper, the effect of variable Blank-holder forces (VBHF) on the strain path during sheet metal forming has been investigated by numerical simulation and experiments. The formability of select aluminum alloy sh...In this paper, the effect of variable Blank-holder forces (VBHF) on the strain path during sheet metal forming has been investigated by numerical simulation and experiments. The formability of select aluminum alloy sheet was evaluated by theory prediction of forming limit curve based on the M-K method. The effect of different VBHF on the formability was presented. In order to verify the predictions of strain path, experiments are being carried out using a recently-built multi-points variable blank-holder forces hydraulic press. The results show that large side BHF with small comer BHF during rectangular box deep drawing can improve the formability of the selected aluminum alloy展开更多
The Three Gorges project accelerates economic development in the Three Gorges Reservoir Area.This paper aimed to investigate the distribution,changes and features of cultivated land in this area,analyze the forces dri...The Three Gorges project accelerates economic development in the Three Gorges Reservoir Area.This paper aimed to investigate the distribution,changes and features of cultivated land in this area,analyze the forces driving the changes in cultivated land area,and propose the countermeasures for cultivated land management.Transition matrix was used to analyze the features of cultivated land changes,and quantitative analysis and qualitative analysis were adopted to research the driving forces according to the features of cultivated land changes.Cultivated land in the Three Gorges Reservoir Area mainly lay to the northwest of the Yangtze River,especially the upper reaches.The areas of cultivated land increased from 1996 to 1999,then decreased from 2000 to 2006,and finally increased again from 2007 to 2009.The important forces driving changes in cultivated land included government policies,employment and food security,increasing construction land,agriculture structure adjustment,land rearrangement,inundation.During cultivated land management,firstly,it is necessary to insist on the principle of cultivated land protection,standardize land exploitation and strictly restrict the transformation of cultivated land into non-farming land.Secondly,land rearrangement must be implemented,which can not only increase the area of the cultivated land,but also improve the quality of the cultivated land.Thirdly,it is feasible to intensify eco-agriculture construction to increase the quantity and quality of cultivated land.Fourthly,it is helpful to improve the traditional agriculture production methods to promote cultivated land quality.Lastly,it is important to propagandize cultivated land protection and realize the enormous pressure of cultivated land shortage,making more people obligated to protect cultivated land.展开更多
This is the first report of the Barents Sea Ice Edge (BIE) project. The BIE position has varied between latitude 76<span style="white-space:nowrap;">°</span>N and above 82<span style=&...This is the first report of the Barents Sea Ice Edge (BIE) project. The BIE position has varied between latitude 76<span style="white-space:nowrap;">°</span>N and above 82<span style="white-space:nowrap;">°</span>N during the last 440 years. During the period 10,000 to 6000 years ago, Arctic climate was significantly warmer than today. We review various oceanic and atmospheric factors that may have an effect on the BIE position. The Gulf Stream beat with respect to alternations in flow intensity and N-S distribution plays a central role for the changes in climate and BIE position during the last millennium. This occurred in combination with external forcing from total solar irradiation, Earth’s shielding strength, Earth’s geomagnetic field intensity, Earth’s rotation, jet stream changes;all factors of which are ultimately driven by the planetary beat on the Sun, the Earth and the Earth-Moon system. During the last 20 years, we see signs of changes and shifts that may signal the end of the late 20<sup>th</sup> century warm period. The BIE position is likely to start advancing southward in next decade.展开更多
Calculation of tidal changes reveals that the MS 7. 0 Lushan County,Sichuan,China,earthquake of April 20,2013 occurred at the minimum phase point of tidal force. It indicates that the seismogenic fault on which the ti...Calculation of tidal changes reveals that the MS 7. 0 Lushan County,Sichuan,China,earthquake of April 20,2013 occurred at the minimum phase point of tidal force. It indicates that the seismogenic fault on which the tidal force acts on is of thrust type. The outgoing long-wave radiation( OLR) is the energy radiating from the Earth as infrared radiation at low energy to space. According to the tidal cycle,abnormal OLR change is analyzed based on NOAA satellite data around the whole of China before and after the earthquake. The result shows that the OLR changed evidently with the tide force change.Temporally,the change went through the course: initial OLR rise → s trengthening →reaching abnormal peak → a ttenuation → r eturning to normal; in space,the abnormal area was distributed along the Longmenshan fault and evolved as: scattering→ c onvergent→ s cattering. The process is similar to the change process of rock breaking under stress loading. It indicates that the celestial tidal force can trigger earthquakes when the tectonic stress reaches the critical break point of an active fault and the OLR anomaly is proportional to the seismic tectonic stress change. It is of practical value to combine OLR and tidal force anomaly with earthquake precursor studies.展开更多
During the rapid urbanization period, the contradiction between demand for the construction land and the preservation of cultivated land for food security is getting more and more serious in China. With the urbanizati...During the rapid urbanization period, the contradiction between demand for the construction land and the preservation of cultivated land for food security is getting more and more serious in China. With the urbanization the rural settlement land is increasing instead of decreasing; This paper aims at.finding the driving forces for rural settlement land expanston. Based on land use change survey data (1996-2006) by the Ministry of Land and Resources P. R. C., this paper find, that per capita area for rural settlement land is more than per capita area for city; township and industrial land in each province except Tibet. Besides, rural settlement land area and per capita rural settlement land area are increasing while the rural poputation is decreasing in most provinces. The main problems of rural settlement land use are low efficiency, high vacancy rate, chaotic layout and illegal occupancy. Then the driving forces [br rural settlement land expansion, including economic development, family income, family scale, psychological factors, urbanization, transportation, lack of planning, limited circulation of dwelling-house land and imperfect sociat security, ate explored based on above analysis, Finalty, policy recommendations, in view of different influencing factors, are put forward to control the disorder expansion of rural setttement land.展开更多
This paper takes poverty-stricken countyas the basic unit, and selects net income per peasantto study the poverty status in Hebei Province during1986~2000.Temporal and spatial changes of poverty-stricken areas are ana...This paper takes poverty-stricken countyas the basic unit, and selects net income per peasantto study the poverty status in Hebei Province during1986~2000.Temporal and spatial changes of poverty-stricken areas are analyzed. The result shows thatpoverty-stricken areas in Hebei Province distributedconcentratedly and the areas decreased during1986~2000, the net income per peasant was on therise with an increasing speed in off-poverty countiesbeing slightly higher than that in poverty-strickencounties, but the growth rate was extremely unstable,rising slowly in off-poverty counties while droppingin poverty-stricken counties. The main driving forcesthat influenced temporal and spatial changes wereeconomic development of the whole province,ecological environment quality, infrastructureconditions and radiation of the key city. On thisbasis, some anti-poverty countermeasures suitable tolocal conditions are proposed.展开更多
Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science (LCS) in the study of global environmental change. Based on remotely sensed data of...Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science (LCS) in the study of global environmental change. Based on remotely sensed data of land use change with a spatial resolution of 1 km × 1 km on national scale among every 5 years, this paper designed a new dynamic regionalization according to the comprehensive characteristics of land use change including regional differentiation, physical, economic, and macro-policy factors as well. Spatial pattern of land use change and its driving forces were investigated in China in the early 21 st century. To sum up, land use change pattern of this period was characterized by rapid changes in the whole country. Over the agricultural zones, e.g., Huang-Huai-Hai Plain, the southeast coastal areas and Sichuan Basin, a great proportion of fine arable land were engrossed owing to considerable expansion of the built-up and residential areas, resulting in decrease of paddy land area in southern China. The development of oasis agriculture in Northwest China and the reclamation in Northeast China led to a slight increase in arable land area in northern China. Due to the "Grain for Green" policy, forest area was significantly increased in the middle and western developing regions, where the vegetation coverage was substantially enlarged, likewise. This paper argued the main driving forces as the implementation of the strategy on land use and regional development, such as policies of "Western Development", "Revitalization of Northeast", coupled with rapidly economic development during this period.展开更多
Land-use change is an important aspect of global environment change. It is,in a sense, the direct result of human activities influencing our physical environment. Supported bythe dynamic serving system of national res...Land-use change is an important aspect of global environment change. It is,in a sense, the direct result of human activities influencing our physical environment. Supported bythe dynamic serving system of national resources, including both the environment database and GIStechnology, this paper analyzed the land-use change in northeastern China in the past ten years(1990 ― 2000). It divides northeastern China into five land-use zones based on the dynamic degree(DD) of land-use: woodland/grassland ― arable land conversion zone, dry land ― paddy fieldconversion zone, urban expansion zone, interlocked zone of farming and pasturing, and reclamationand abandoned zone. In the past ten years, land-use change of northeastern China can be generalizedas follows: increase of cropland area was obvious, paddy field and dry land increased by 74. 9 and276. 0 thousand ha respectively; urban area expanded rapidly, area of town and rural residenceincreased by 76. 8 thousand ha; area of forest and grassland decreased sharply with the amount of1399. 0 and 1521. 3 thousand ha respectively; area of water body and unused land increased by 148. 4and 513. 9 thousand ha respectively. Besides a comprehensive analysis of the spatial patterns ofland use, this paper also discusses the driving forces in each land-use dynamic zones. The studyshows that some key biophysical factors affect conspicuously the conversion of different land-usetypes. In this paper, the relationships between land-use conversion and DEM, accumulated temperature(≥10℃) and precipitation were analysed and represented. We conclude that the land-use changes innortheast China resulted from the change of macro social and economic factors and local physicalelements. Rapid population growth and management changes, in some sense, can explain the shaping ofwoodland/grassland ― cropland conversion zone. The conversion from dry land to paddy field in thedry land ― paddy field conversion zone, apart from the physical elements change promoting theexpansion of paddy field, results from two reasons: one is that the implementation of market-economyin China has given fanners the right to decide what they plant and how they plant their crops, theother factor is originated partially from the change of dietary habit with the social and economicdevelopment. The conversion from paddy field to dry land is caused primarily by the shortfall ofirrigation water, which in turn is caused by poor water allocation managed by local governments. Theshaping of the reclamation and abandoned zone is partially due to the lack of environmentprotection consciousness among pioneer settlers. The reason for the conversion from grassland tocropland is the relatively higher profits of farming than that of pasturing in the interlocked zoneof farming and pasturing. In northeastern China, the rapid expansion of built-up areas results fromtwo factors: the first is its small number of towns; the second comes from the huge potential forexpansion of existing towns and cities. It is noticeable that urban expansion in the northeasternChina is characterized by gentle topographic relief and low population density. Physiognomy,transportation and economy exert great influences on the urban expansion.展开更多
While urbanization has accelerated, the rural population in China has started decreasing in recent years. However, the expansion of rural settlement has not been sufficiently curbed. The questions of why this has happ...While urbanization has accelerated, the rural population in China has started decreasing in recent years. However, the expansion of rural settlement has not been sufficiently curbed. The questions of why this has happened and who has driven the land-use change(LUC) of rural settlement in China have aroused great interests among researchers. In this paper, it is suggested that population is not always a positive driving force for the LUC of rural settlement in China. Furthermore, socio-economic driving forces other than urbanization, population and industrialization are analyzed. On a national scale, the major driving forces are the per-capita rural housing area and the cultivated land area. On a regional scale, the main driving forces in the eastern China are the house-building capacity of rural households and the per-capita rural housing area; while in the central China, the main driving forces are rural housing investment, the proportion of primary industry employees in the rural working population, and the cultivated land area. For the western China, the main driving forces are rural register population and cultivated land area.展开更多
By selecting impact factors of driving force and formulating evaluation criteria of the impacts, the evaluation system of corresponding driving force impact of land use change was established. Taking Lu'an mining ...By selecting impact factors of driving force and formulating evaluation criteria of the impacts, the evaluation system of corresponding driving force impact of land use change was established. Taking Lu'an mining area as an example, the specific impact factors of coal mine were comprehensively evaluated and analyzed in order to carry out qualitative and quantitative analysis for the driving force of mining-land use change. The principal component analysis shows that the social and economic development in mining area from 2000 to 2007 demonstrates continuous accelerate trends, and the impacts of its overall driving force to land use change are increased gradually. The socio-economic factors have more impacts to mining-land use change than those of the natural resources. The main driving force of mining-land use change also include population, technological progress and policy.展开更多
Human activities have notably affected the Earth’s climate through greenhouse gases(GHG), aerosol, and land use/land cover change(LULCC). To investigate the impact of forest changes on regional climate under differen...Human activities have notably affected the Earth’s climate through greenhouse gases(GHG), aerosol, and land use/land cover change(LULCC). To investigate the impact of forest changes on regional climate under different shared socioeconomic pathways(SSPs), changes in surface air temperature and precipitation over China under low and medium/high radiative forcing scenarios from 2021 to 2099 are analyzed using multimodel climate simulations from the Coupled Model Intercomparison Project Phase 6(CMIP6). Results show that the climate responses to forest changes are more significant under the low radiative forcing scenario. Deforestation would increase the mean, interannual variability, and the trend of surface air temperature under the low radiative forcing scenario, but it would decrease those indices under the medium/high radiative forcing scenario. The changes in temperature show significant spatial heterogeneity. For precipitation, under the low radiative forcing scenario, deforestation would lead to a significant increase in northern China and a significant decrease in southern China, and the effects are persistent in the near term(2021–40), middle term(2041–70), and long term(2071–99). In contrast, under the medium/high radiative forcing scenario, precipitation increases in the near term and long term over most parts of China, but it decreases in the middle term, especially in southern, northern,and northeast China. The magnitude of precipitation response to deforestation remains comparatively small.展开更多
Based on the statistical data of land use change,from the perspective of sustainable use,we use literature inquiry,statistical analysis,GIS spatial analysis and dynamic degree model of land use,to analyze the land use...Based on the statistical data of land use change,from the perspective of sustainable use,we use literature inquiry,statistical analysis,GIS spatial analysis and dynamic degree model of land use,to analyze the land use change characteristics,land use amount and spatial distribution characteristics in Guangzhou City during 1996- 2012,and further elaborate the driving forces of land use change to get the basic law of land use change in Guangzhou City. The results show that the construction land was rapidly expanded,causing a significant reduction in arable land( from 129286 ha in 1996 to 84567 ha in 2012); in construction land,the land for residential,industrial and mining use and transportation land dramatically increased,and the single dynamic degree of transportation land was close to 7. 1%. In comparison with other developed cities,it is found that economic factors and policy factors are important factors affecting land use change in Guangzhou City,and the growth rate of economic density of land was high in Tianhe District and Yuexiu District. From the perspective of sustainable use,the future land use in Guangzhou City needs to better coordinate the relationship between various types of land,between socio-economic development and coordinated land use development,between environmental protection and land development and utilization. Through a series of land consolidation activities,it is necessary to strengthen the protection of farmland,improve the intensive and economical use of construction land,improve the ecological environment,and coordinate development of urban and rural areas,to ultimately achieve sustainable land use in Guangzhou City.展开更多
基金Supported by the National Social Science Fund(06XMZ014)~~
文摘Using gradually regression analysis to establish the driving force model of utilized change of cultivated land in Gonghe County, and using path analysis, correlation analysis, partial correlation analysis and system dynamics method to inspect the effect of driving changing on cultivated land change under different change situations. Driving factors, action mechanism and process of utilized change of cultivated land were analyzed from the county territory scale level. At last, some corresponding policies and measures were put forward.
基金Supported by The Regional Sustainable Development of the Qing-TibetPlateau(2004)~~
文摘Using path analysis, correlation analysis, partial correlation analysis and system dynamics method to study the driving force of cultivated land in Qinghai Lake Area, and using gradually regression analysis to establish the driving force model of utilized change of cultivated land. Driving factors, action mechanism and process of utilized change of cultivated land were analyzed, and the differences during all factors were compared. The study provides some decision basis for sustainable utilization and management of land resources in Qinghai Lake Area.
基金Project supported by the Fujian Provincial Natural Science Foundation of China (No. D0210010).
文摘Using Landsat TM data of 1988, 1998 and 2001, the dynamic process of the spatial-temporal characteristics of land use changes during 13 years from 1988 to 2001 in the special economic zone of Xiamen, China was analyzed to improve understanding and to find the driving forces of land use change so that sustainable land utilization could be practiced. During the 13 years cropland decreased remarkably by nearly 11304.95 ha. The areas of rural-urban construction and water body increased by 10 152.24 ha and 848.94 ha, respectively. From 1988 to 2001, 52.5% of the lost cropland was converted into rural-urban industrial land. Rapid urbanization contributed to a great change in the rate of cropland land use during these years. Land-reclamation also contributed to a decrease in water body area as well as marine ecological and environmental destruction. In the study area 1) urbanization and industrialization, 2) infrastructure and agricultural intensification, 3) increased affluence of the farming community, and 4) policy factors have driven the land use changes. Possible sustainable land use measures included construction of a land management system, land planning, development of potential land resources, new technology applications, and marine ecological and environmental protection.
基金funded by the 135 Strategic Program of the Institute of Mountain Hazards and Environment, CAS (Grant No. SDS135-1703)Coupled relationship and regulation mechanism between rural livelihoods and ecosystem services in the Three Gorges Reservoir Area (No.41371539)
文摘Changes of cultivated land patterns caused by major water conservation projects are rarely reported. We selected the Three Gorges Reservoir area in China to study the change in area and landscape pattern of the cultivated land in the head,central, and tail areas of the reservoir that took place between 1992 and 2015;we then studied the spatial distribution of the cultivated land in the three parts of the reservoir;finally, we studied the driving forces behind the changes in the cultivated land. The results derived are as follows.(1) During the construction of the Three Gorges Project(TGP, 1992–2015), the area of cultivated land around the reservoir decreased by30.23 million ha. This reduction occurred in phases:the most severe change in cultivated land occurred during the later stage of the project(2002–2010);only 0.62 million ha of cultivated land did not change between 1992 and 2015.(2) Spatial pattern analysis showed that the cultivated land in the three parts of the reservoir changed from a northern distribution to a southern distribution;thus, the area of cultivated land in the north decreased over the time period. The area of cultivated land in the head and tail areas decreased by varying degrees, while it increased in the central area over the 23 years, indicating that the change in cultivated land showed regional differences.(3) The TGP, the policy of reverting farmland to forest,and urbanization were the main driving factors for the change of cultivated land, but there were differences in their impacts at different stages.(4) According to the patch dynamics of the land cover change, the degree of change gradually intensified during the early and later stages of the project and then stabilized during the operational period. Our research provides scientific support for the protection of cultivated land resources and food security in the reservoir area and for the coordination of social and economic development, which is of great significance to sustainable development in the reservoir area.
基金The National Natural Science Foundation of China, No.49971004
文摘The decrease of total cultivated area and the lower per capita available arable land resource are now serious problems in Shandong Province, a major agricultural province in China. These problems will become more serious along with the further development of economy. In this paper, based on the statistical information at provincial and county levels, the changes of arable land in Shandong Province and their driving forces during the last 50 years are analyzed. The general changing trends of arable land and per capita available arable land are reducing, and the trends of decrease will continue when the economy is developing. The result of GIS spatial analysis shows that the change of the arable land use in Shandong Province has a regional difference. Eight variables having influences on cultivated land change are analyzed by principal component analysis. The results show that the dynamic development of economy, pressure of social system and progress of scientific techniques in agriculture are the main causes for cultivated land reduction. The principal factors which can be considered as driving forces for arable land change include per capita net living space, total population and per ha grain yield. By using regressive equation, along with analysis on population growth and economic development, cultivated areas in Shandong Province in 2005 and 2010 are predicted respectively. The predicted cultivated areas in Shandong will be 6435.47 thousand hain 2005 and 6336.23 thousand ha in 2010 respectively.
基金This research was supported by the National Natural Science Foundation of China
文摘Based on the plastic deformation theory and energy method, the critical blank-holder forces (BHF) of wrinkling and fracture in the cylindrical cup deep-drawing are analyzed. The verify experiments were performed and compared with the theory analysis results. The predictions agree well with the experiment results. Thus, the validated presenttheoretical analysis model may be applied to determinate the suitable BHF.
基金the National Natural Science Foundation of China, No. 3077054630970758+1 种基金Chongqing Natural Science Foundation, No. 2006BB2043 2007BB5148
文摘BACKGROUND: The detection of motor evoked potential is utilized to explore neuromuscular finger coordination. The influence of transcranial magnetic stimulation on finger force has been investigated mainly on a single finger, and only time-dependent increased target finger force has been detected in the finger force task. OBJECTIVE: To explore the neural mechanism of finger force coordination in the motor cortex by observing the influence of various finger coordination patterns and patterns of transcranial magnetic stimulation (TMS)-induced finger force changes. DESIGN, TIME AND SETTING: Neurophysiological and behavioral study was performed at the Biomedical Engineering Laboratory of Chongqing University from April to June 2008. PARTICIPANTS: A total of 10 healthy, university students, comprising 5 males and 5 females, aged 21-23 years, voluntarily participated in this study. All participants were right-handed, with normal or corrected vision. Individuals with upper limb complaints or other musculoskeletal disorders were excluded. METHODS: A target force-tracking task was conducted on the index finger, the index and middle fingers, and four fingers (index, middle, ring, and little), respectively. Target force trace in a single trial consisted of a 6-second ramp phase, a 20-second constant phase, and a 6-second drop phase. During experimentation, an unpredictable single-pulse TMS (120% motor threshold) was applied to the primary motor cortex (M1) in each phase. MAIN OUTCOME MEASURES: Changes in peak force induced by TMS were obtained for each finger pattern during each force-tracking phase. Differences in force changes were tested between different finger pattems with regard to ramp, constant, and drop phases of target force. RESULTS: Under ramp, constant, and drop phases of target force, the increase in magnetic stimulation-induced finger forces changes positively correlated with the number of fingers involved in the force tracking task. The magnetic stimulation-induced force changes from the index finger were less than the combination of the index and middle fingers or all four fingers under the corresponding target force, and the force changes from the combination of the index and middle fingers were less than all four fingers, Le., index finger 〈 index and middle fingers 〈 four fingers. CONCLUSION: Different neuromuscular mechanisms could be involved in finger force production for different finger combination patterns. Results from the present study suggested that independent motor neurons regulated individual finger force production.
基金Sponsored by Natural Science Foundation of China(31200419)"11th five-year"science and technology of Jilin Province Education Department(2010-146)Science and Technology Foundation of Jilin Province Education Department,Natural Science Foundation of Changchun Normal University(2010-035)
文摘Based on the remote sensing data of Landsat 5,landscape indexes were used to analyze the land use/cover changes of Xuzhou City during 1994 and 2005,in order to discover the inside driving system.Fourteen social driving forces were chosen according to the PCA theory,and the social driving forces of land use/cover change were analyzed with the help of SPSS software.The result indicated that population,economy,adjustment of agriculture structure were main impact factors of land use/cover changes.
基金This research was supported by the National Natural Science Foundation of China
文摘In this paper, the effect of variable Blank-holder forces (VBHF) on the strain path during sheet metal forming has been investigated by numerical simulation and experiments. The formability of select aluminum alloy sheet was evaluated by theory prediction of forming limit curve based on the M-K method. The effect of different VBHF on the formability was presented. In order to verify the predictions of strain path, experiments are being carried out using a recently-built multi-points variable blank-holder forces hydraulic press. The results show that large side BHF with small comer BHF during rectangular box deep drawing can improve the formability of the selected aluminum alloy
基金supported by the Fundamental Research Funds for the Central Universities (Grant No. 2011YYL141)
文摘The Three Gorges project accelerates economic development in the Three Gorges Reservoir Area.This paper aimed to investigate the distribution,changes and features of cultivated land in this area,analyze the forces driving the changes in cultivated land area,and propose the countermeasures for cultivated land management.Transition matrix was used to analyze the features of cultivated land changes,and quantitative analysis and qualitative analysis were adopted to research the driving forces according to the features of cultivated land changes.Cultivated land in the Three Gorges Reservoir Area mainly lay to the northwest of the Yangtze River,especially the upper reaches.The areas of cultivated land increased from 1996 to 1999,then decreased from 2000 to 2006,and finally increased again from 2007 to 2009.The important forces driving changes in cultivated land included government policies,employment and food security,increasing construction land,agriculture structure adjustment,land rearrangement,inundation.During cultivated land management,firstly,it is necessary to insist on the principle of cultivated land protection,standardize land exploitation and strictly restrict the transformation of cultivated land into non-farming land.Secondly,land rearrangement must be implemented,which can not only increase the area of the cultivated land,but also improve the quality of the cultivated land.Thirdly,it is feasible to intensify eco-agriculture construction to increase the quantity and quality of cultivated land.Fourthly,it is helpful to improve the traditional agriculture production methods to promote cultivated land quality.Lastly,it is important to propagandize cultivated land protection and realize the enormous pressure of cultivated land shortage,making more people obligated to protect cultivated land.
文摘This is the first report of the Barents Sea Ice Edge (BIE) project. The BIE position has varied between latitude 76<span style="white-space:nowrap;">°</span>N and above 82<span style="white-space:nowrap;">°</span>N during the last 440 years. During the period 10,000 to 6000 years ago, Arctic climate was significantly warmer than today. We review various oceanic and atmospheric factors that may have an effect on the BIE position. The Gulf Stream beat with respect to alternations in flow intensity and N-S distribution plays a central role for the changes in climate and BIE position during the last millennium. This occurred in combination with external forcing from total solar irradiation, Earth’s shielding strength, Earth’s geomagnetic field intensity, Earth’s rotation, jet stream changes;all factors of which are ultimately driven by the planetary beat on the Sun, the Earth and the Earth-Moon system. During the last 20 years, we see signs of changes and shifts that may signal the end of the late 20<sup>th</sup> century warm period. The BIE position is likely to start advancing southward in next decade.
基金supported by the science for earthquake resilience of China(No.XH15050)the Research on Determination and Announcement of the National Significant Seismic Monitoring and Protction Regions During 2015 to 2016(201508010)
文摘Calculation of tidal changes reveals that the MS 7. 0 Lushan County,Sichuan,China,earthquake of April 20,2013 occurred at the minimum phase point of tidal force. It indicates that the seismogenic fault on which the tidal force acts on is of thrust type. The outgoing long-wave radiation( OLR) is the energy radiating from the Earth as infrared radiation at low energy to space. According to the tidal cycle,abnormal OLR change is analyzed based on NOAA satellite data around the whole of China before and after the earthquake. The result shows that the OLR changed evidently with the tide force change.Temporally,the change went through the course: initial OLR rise → s trengthening →reaching abnormal peak → a ttenuation → r eturning to normal; in space,the abnormal area was distributed along the Longmenshan fault and evolved as: scattering→ c onvergent→ s cattering. The process is similar to the change process of rock breaking under stress loading. It indicates that the celestial tidal force can trigger earthquakes when the tectonic stress reaches the critical break point of an active fault and the OLR anomaly is proportional to the seismic tectonic stress change. It is of practical value to combine OLR and tidal force anomaly with earthquake precursor studies.
基金supported by Scientific and Technological Major Project in National Eleventh Five-Year Plan (Grant No. 2006BAJ05A04)
文摘During the rapid urbanization period, the contradiction between demand for the construction land and the preservation of cultivated land for food security is getting more and more serious in China. With the urbanization the rural settlement land is increasing instead of decreasing; This paper aims at.finding the driving forces for rural settlement land expanston. Based on land use change survey data (1996-2006) by the Ministry of Land and Resources P. R. C., this paper find, that per capita area for rural settlement land is more than per capita area for city; township and industrial land in each province except Tibet. Besides, rural settlement land area and per capita rural settlement land area are increasing while the rural poputation is decreasing in most provinces. The main problems of rural settlement land use are low efficiency, high vacancy rate, chaotic layout and illegal occupancy. Then the driving forces [br rural settlement land expansion, including economic development, family income, family scale, psychological factors, urbanization, transportation, lack of planning, limited circulation of dwelling-house land and imperfect sociat security, ate explored based on above analysis, Finalty, policy recommendations, in view of different influencing factors, are put forward to control the disorder expansion of rural setttement land.
文摘This paper takes poverty-stricken countyas the basic unit, and selects net income per peasantto study the poverty status in Hebei Province during1986~2000.Temporal and spatial changes of poverty-stricken areas are analyzed. The result shows thatpoverty-stricken areas in Hebei Province distributedconcentratedly and the areas decreased during1986~2000, the net income per peasant was on therise with an increasing speed in off-poverty countiesbeing slightly higher than that in poverty-strickencounties, but the growth rate was extremely unstable,rising slowly in off-poverty counties while droppingin poverty-stricken counties. The main driving forcesthat influenced temporal and spatial changes wereeconomic development of the whole province,ecological environment quality, infrastructureconditions and radiation of the key city. On thisbasis, some anti-poverty countermeasures suitable tolocal conditions are proposed.
基金National Basic Research Program of China, No.2009CB421105National Key Technology R&D Program, No.2006BAC08B00Knowledge Innovation Program of the CAS, No.KSCX1-YW-09-01
文摘Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science (LCS) in the study of global environmental change. Based on remotely sensed data of land use change with a spatial resolution of 1 km × 1 km on national scale among every 5 years, this paper designed a new dynamic regionalization according to the comprehensive characteristics of land use change including regional differentiation, physical, economic, and macro-policy factors as well. Spatial pattern of land use change and its driving forces were investigated in China in the early 21 st century. To sum up, land use change pattern of this period was characterized by rapid changes in the whole country. Over the agricultural zones, e.g., Huang-Huai-Hai Plain, the southeast coastal areas and Sichuan Basin, a great proportion of fine arable land were engrossed owing to considerable expansion of the built-up and residential areas, resulting in decrease of paddy land area in southern China. The development of oasis agriculture in Northwest China and the reclamation in Northeast China led to a slight increase in arable land area in northern China. Due to the "Grain for Green" policy, forest area was significantly increased in the middle and western developing regions, where the vegetation coverage was substantially enlarged, likewise. This paper argued the main driving forces as the implementation of the strategy on land use and regional development, such as policies of "Western Development", "Revitalization of Northeast", coupled with rapidly economic development during this period.
文摘Land-use change is an important aspect of global environment change. It is,in a sense, the direct result of human activities influencing our physical environment. Supported bythe dynamic serving system of national resources, including both the environment database and GIStechnology, this paper analyzed the land-use change in northeastern China in the past ten years(1990 ― 2000). It divides northeastern China into five land-use zones based on the dynamic degree(DD) of land-use: woodland/grassland ― arable land conversion zone, dry land ― paddy fieldconversion zone, urban expansion zone, interlocked zone of farming and pasturing, and reclamationand abandoned zone. In the past ten years, land-use change of northeastern China can be generalizedas follows: increase of cropland area was obvious, paddy field and dry land increased by 74. 9 and276. 0 thousand ha respectively; urban area expanded rapidly, area of town and rural residenceincreased by 76. 8 thousand ha; area of forest and grassland decreased sharply with the amount of1399. 0 and 1521. 3 thousand ha respectively; area of water body and unused land increased by 148. 4and 513. 9 thousand ha respectively. Besides a comprehensive analysis of the spatial patterns ofland use, this paper also discusses the driving forces in each land-use dynamic zones. The studyshows that some key biophysical factors affect conspicuously the conversion of different land-usetypes. In this paper, the relationships between land-use conversion and DEM, accumulated temperature(≥10℃) and precipitation were analysed and represented. We conclude that the land-use changes innortheast China resulted from the change of macro social and economic factors and local physicalelements. Rapid population growth and management changes, in some sense, can explain the shaping ofwoodland/grassland ― cropland conversion zone. The conversion from dry land to paddy field in thedry land ― paddy field conversion zone, apart from the physical elements change promoting theexpansion of paddy field, results from two reasons: one is that the implementation of market-economyin China has given fanners the right to decide what they plant and how they plant their crops, theother factor is originated partially from the change of dietary habit with the social and economicdevelopment. The conversion from paddy field to dry land is caused primarily by the shortfall ofirrigation water, which in turn is caused by poor water allocation managed by local governments. Theshaping of the reclamation and abandoned zone is partially due to the lack of environmentprotection consciousness among pioneer settlers. The reason for the conversion from grassland tocropland is the relatively higher profits of farming than that of pasturing in the interlocked zoneof farming and pasturing. In northeastern China, the rapid expansion of built-up areas results fromtwo factors: the first is its small number of towns; the second comes from the huge potential forexpansion of existing towns and cities. It is noticeable that urban expansion in the northeasternChina is characterized by gentle topographic relief and low population density. Physiognomy,transportation and economy exert great influences on the urban expansion.
基金Under the auspices of National Natural Science Foundation of China(No.41001108)China Clean Development Mechanism Fund(No.2031202400003)
文摘While urbanization has accelerated, the rural population in China has started decreasing in recent years. However, the expansion of rural settlement has not been sufficiently curbed. The questions of why this has happened and who has driven the land-use change(LUC) of rural settlement in China have aroused great interests among researchers. In this paper, it is suggested that population is not always a positive driving force for the LUC of rural settlement in China. Furthermore, socio-economic driving forces other than urbanization, population and industrialization are analyzed. On a national scale, the major driving forces are the per-capita rural housing area and the cultivated land area. On a regional scale, the main driving forces in the eastern China are the house-building capacity of rural households and the per-capita rural housing area; while in the central China, the main driving forces are rural housing investment, the proportion of primary industry employees in the rural working population, and the cultivated land area. For the western China, the main driving forces are rural register population and cultivated land area.
基金Project(MTKJ2010-377)supported by the Sci-tech Plan Project of China National Coal AssociationProject(B2006-18)supported by the Doctor Fund of Henan Polytechnic University
文摘By selecting impact factors of driving force and formulating evaluation criteria of the impacts, the evaluation system of corresponding driving force impact of land use change was established. Taking Lu'an mining area as an example, the specific impact factors of coal mine were comprehensively evaluated and analyzed in order to carry out qualitative and quantitative analysis for the driving force of mining-land use change. The principal component analysis shows that the social and economic development in mining area from 2000 to 2007 demonstrates continuous accelerate trends, and the impacts of its overall driving force to land use change are increased gradually. The socio-economic factors have more impacts to mining-land use change than those of the natural resources. The main driving force of mining-land use change also include population, technological progress and policy.
基金jointly supported by the National Natural Science Foundation of China under Grant No. 41975081the Research Funds for the Frontiers Science Center for Critical Earth Material Cycling Nanjing Universitythe Fundamental Research Funds for the Central Universities (Grant No. 020914380103)。
文摘Human activities have notably affected the Earth’s climate through greenhouse gases(GHG), aerosol, and land use/land cover change(LULCC). To investigate the impact of forest changes on regional climate under different shared socioeconomic pathways(SSPs), changes in surface air temperature and precipitation over China under low and medium/high radiative forcing scenarios from 2021 to 2099 are analyzed using multimodel climate simulations from the Coupled Model Intercomparison Project Phase 6(CMIP6). Results show that the climate responses to forest changes are more significant under the low radiative forcing scenario. Deforestation would increase the mean, interannual variability, and the trend of surface air temperature under the low radiative forcing scenario, but it would decrease those indices under the medium/high radiative forcing scenario. The changes in temperature show significant spatial heterogeneity. For precipitation, under the low radiative forcing scenario, deforestation would lead to a significant increase in northern China and a significant decrease in southern China, and the effects are persistent in the near term(2021–40), middle term(2041–70), and long term(2071–99). In contrast, under the medium/high radiative forcing scenario, precipitation increases in the near term and long term over most parts of China, but it decreases in the middle term, especially in southern, northern,and northeast China. The magnitude of precipitation response to deforestation remains comparatively small.
基金Supported by National Natural Science Foundation of China(41101078,41401191)General Humanities and Social Sciences Research Project of the Ministry of Education(13YJA790074)+6 种基金Guangdong Natural Science Foundation(S2013010014526)Innovation Project of Guangdong Provincial Department of Education(2014KTSCX090)Guangdong"Twelfth Five-Year Plan"Education and Research Project in 2013(2013JK134)General Research Project of Guangzhou Municipal Universities(2012A014)Guangzhou"Twelfth Five-Year Plan"Education Science Project(12A037)Guangzhou"Twelfth Five-Year Plan"Philosophy and Social Sciences Project in 2015(15Q28)College Students'Innovative Training Program of Guangdong Provincial Department of Education(201411078056,201411078057,201511-078019,CX2015025)
文摘Based on the statistical data of land use change,from the perspective of sustainable use,we use literature inquiry,statistical analysis,GIS spatial analysis and dynamic degree model of land use,to analyze the land use change characteristics,land use amount and spatial distribution characteristics in Guangzhou City during 1996- 2012,and further elaborate the driving forces of land use change to get the basic law of land use change in Guangzhou City. The results show that the construction land was rapidly expanded,causing a significant reduction in arable land( from 129286 ha in 1996 to 84567 ha in 2012); in construction land,the land for residential,industrial and mining use and transportation land dramatically increased,and the single dynamic degree of transportation land was close to 7. 1%. In comparison with other developed cities,it is found that economic factors and policy factors are important factors affecting land use change in Guangzhou City,and the growth rate of economic density of land was high in Tianhe District and Yuexiu District. From the perspective of sustainable use,the future land use in Guangzhou City needs to better coordinate the relationship between various types of land,between socio-economic development and coordinated land use development,between environmental protection and land development and utilization. Through a series of land consolidation activities,it is necessary to strengthen the protection of farmland,improve the intensive and economical use of construction land,improve the ecological environment,and coordinate development of urban and rural areas,to ultimately achieve sustainable land use in Guangzhou City.