The implementation of the Grain for Green Program is a great breakthrough in the history of China's ecological environment construction,which can control soil erosion effectively,increase land productivity and improv...The implementation of the Grain for Green Program is a great breakthrough in the history of China's ecological environment construction,which can control soil erosion effectively,increase land productivity and improve the ecological environment.To investigate the eco-environmental benefits brought by the Grain for Green Program,the spatiotemporal variations of vegetation cover in the growing season from 2000 to 2010 across the Hekou-Longmen (He-Long) region were analyzed by using remote sensing information,meteorological data and land use data.Moreover,the impacts of climate and human activities on vegetation change were evaluated objectively.Annual vegetation cover in the growing season increased very significantly.Increased vegetation cover occurred in 98.7% of the region,of which the area for vegetation cover improved slightly constituted 79.8% of the whole area.Vegetation moderately improved was mainly distributed in the south of the He-Long region,covering 9.6% of the area,and the area for vegetation basically unchanged concentrated in the middle and upper reaches of the Wuding River.Precipitation was found to be an important natural factor influencing vegetation cover change.The area of vegetation cover showing a significantly positive correlation with precipitation occupied 22.14% of the region.As driven by policies from the Grain for Green Program,forestland increased significantly and land use structure became more intensive.Human activities played a positive and effective role in the protection,restoration and improvement of vegetation in the places where vegetation cover was basically unchanged,even though precipitation declined greatly,and vegetation improved moderately with massive increases of forestland and grassland.展开更多
The diffusivity of hydrogen in two Ni3Al alloys (No.1 and No.2) has been measured in the temperature range of 100 degreesC to 420 degreesC using an ultrahigh vacuum gaseous permeation technique. The diffusivity data f...The diffusivity of hydrogen in two Ni3Al alloys (No.1 and No.2) has been measured in the temperature range of 100 degreesC to 420 degreesC using an ultrahigh vacuum gaseous permeation technique. The diffusivity data fall into two segments, in which the hydrogen diffusivity adheres to the Arrhenius form, respectively. From the hydrogen diffusivity, it is conjectured that the hydrogen diffusivity reflects the hydrogen transportation along the grain boundaries at lower temperature and the hydrogen transportation in the lattice at higher temperature. The intergranular fracture of Lit-type intermetallics induced by hydrogen at relative low temperature results from hydrogen transportation along the grain boundaries and not in the lattice.展开更多
In the seventies some scientific workers from France and Italy suggested that the grain boundary internal friction peak (named the K (e) over cap peak in the literature) widely accepted as a grain boundary process, is...In the seventies some scientific workers from France and Italy suggested that the grain boundary internal friction peak (named the K (e) over cap peak in the literature) widely accepted as a grain boundary process, is originated from the motion of lattice dislocations. Since this problem is one of fundamental importance, this controversy has drawn much international attention. Started from 1982, the Hefei research group made a critical analysis of the large amount of literature concerning this problem and,performed a series of crucial experiments to clarify the controversy. It is concluded that the irrelevant evidence suggested by the controverters comes from the farfetched interpretation and the mis-identification of the internal friction peaks appeared under various experimental conditions and different states of the specimens.展开更多
A thorough understanding of the vegetation succession in relation to both climatic changes and anthropogenic activities is vital for the formulation of adaptation strategies that address potential ecosystem challenges...A thorough understanding of the vegetation succession in relation to both climatic changes and anthropogenic activities is vital for the formulation of adaptation strategies that address potential ecosystem challenges.Various climatic factors such as temperature,precipitation,and solar radiation,as well as anthropogenic factors such as ecological engineering and population migration,will affect the conditions for vegetation.However,the relationships among various factors remain unclear and the response of vegetation to climate change and anthropogenic activities in the Loess Plateau of China has not been well established.This study investigated the spatio-temporal characteristics and relationships between vegetation coverage and climatic factors in the Loess Plateau for the period of 1985–2015.Further analysis separated the anthropogenic and climatic factors on vegetation succession based on residual analysis.The results showed that the normalized difference vegetation index(NDVI)followed a significant upward trend with annual change rates of 0.15%during 1985–2015.The trend of human-induced NDVI increase was consistent with the spatial distribution of increasing forest areas in the eastern part of the Loess Plateau.Eco-restoration projects were the main driving factors that promoted vegetation coverage on the Loess Plateau.Furthermore,these results demonstrated that migrants to cities in the Loess Plateau could relieve ecological pressures and promote vegetation restoration.Therefore,the government should strive to increase population mobility and restore vegetation to sustain this particularly fragile ecological environment.展开更多
Fenlong Technology has been applied to increase yield by 20%-50%,improve quality by 5%,and retain water by 100%in 40 kinds of crop cultivated land and saline-alkali land in 26 provinces of China.This paper clarified f...Fenlong Technology has been applied to increase yield by 20%-50%,improve quality by 5%,and retain water by 100%in 40 kinds of crop cultivated land and saline-alkali land in 26 provinces of China.This paper clarified for the first time the scientific theory system of Fenlong Technology using three-dimensional space resources"Fenlong Agricultural Nature Theory"and the development of the relative"limits"of agricultural growth,which provides a huge power support and natural force for expanding human living spaces.Through inventing and creating a scientific and technological system of farming tools,farming machinery,farming modes,and magic weapons for cultivation,Fenlong Technology can increase grain,promote ecological development,and greatly expand the living spaces of the Chinese nation and achieve sustainable development.Using Fenlong Technology,China has expanded from the current single"cultivated land agriculture"to the"big pattern agriculture"of Fenlong"cultivated land+saline land+degraded grassland+marginal land+desertified land+river water",flexibly used 147 million ha of"three-dimensional space resources"of land,and the newly increased food,meat,and fish can feed 300 million to 400 million people,increased the water storage by 100 billion m^(3),and reduced the collection of groundwater by 20 million to 60 billion m^(3).展开更多
Ghana is rich in forest resources, of whichTerminalia catappa, a wood species of common occurrence is one. Even though sometimes it is used for decorative purposes, however, it grows in the wild. It grows in almost al...Ghana is rich in forest resources, of whichTerminalia catappa, a wood species of common occurrence is one. Even though sometimes it is used for decorative purposes, however, it grows in the wild. It grows in almost all the regions of the country and does well in the tropics. The parts of the tree such as the leaves, fruits and seeds have been known to be very useful for medicinal and other uses. Some work on the strength properties of the leaves and other parts has also been done, however, strength properties of the wood are yet to be explored. In this study, its mechanical properties such as bending strength, compression parallel to the grain, and shear parallel to the grain properties were determined. The British (BS 373, 1957) and American Society of Testing Materials’ specifications (ASTM D143, 1983) using testing methods for small, clear specimens of wood were used in determining the properties. The results showed that at 18% moisture content the wood has a density of 520 kg/m<sup>3</sup> with a mean modulus of rupture of 86.04 Mpa, compressive strength parallel to the grain of 42.02 Mpa, modulus of elasticity of 10,500 Mpa, and shear strength parallel to the grain of 16.42 N/mm<sup>2</sup>. These strength properties are comparable to that of Strombosia glaucescens. Therefore, T. catappa can be used in applications where this species is used.展开更多
During the past decade, great efforts have been made to boost the land use trans- formation in the Loess Plateau, especially for reducing soil erosion by vegetation restoration measures. The Grain-for-Green project (...During the past decade, great efforts have been made to boost the land use trans- formation in the Loess Plateau, especially for reducing soil erosion by vegetation restoration measures. The Grain-for-Green project (GFG) is the largest ecological rehabilitation program in China, which has a positive impact on the vegetation restoration and sustainable devel- opment for the ecologically fragile region of west China. Based on the Landsat TM/ETM im- ages for three time periods (2000, 2005 and 2010), this study applied the GIS technology and a hill-slope analytical model to reveal the spatio-temporal evolutional patterns of returning slope farmland to grassland or woodland in Baota District, Yan'an city of Shaanxi province. Results showed that: (1) from 2000 to 2010, the area of farmland decreased by approximately 35,030 ha, which is the greatest decrease among all the land-use types, whereas grassland, woodland and construction land increased, of which grassland expanded rapidly by 26,380 ha (2) The annual variation rate of land-use dynamics was 1.98% during the period 2000-2010, of which the rate was 1.05% for the 2000-2005 period and 2.92% for the 2005-2010 period, respectively. Over the past decade, returning farmland to woodland or pastures was the main source of increased grassland and woodland, and the reduction of farmland contributed to the increase in grassland and woodland by 97.39% and 85.28%, respectively. (3) As the terrain slope increases, farmland decreased and woodland and grassland increased significantly. Areas with a slope ranging from 15° to 25° and less than 15° were the focus of the GFG project, accounting for 85% of the total area of farmland reduction. Meanwhile, the reduction in farmland was significant and spatially correlated with the increase in woodland and grass- land. (4) Between 2000 and 2010, the area of destruction of grass and trees in grasslands and woodlands for the reclamation of farmland was approximately 4596 ha. The area subject to the GFG policy was 4456 ha with a slope greater than 25° over the decade, but the area of farmland was still 10,357 ha in 2010. Our results indicate that there has still a great potential for returning the steep-slope farmlands to woodlands or grasslands in the Loess Plateau.展开更多
基金funded by the funding from the Chinese Academy of Sciences(KZCX2-XB3-13,KZZD-EW-04-03)the National Science Foundation of China(41230852,41101265)and China Census for Water
文摘The implementation of the Grain for Green Program is a great breakthrough in the history of China's ecological environment construction,which can control soil erosion effectively,increase land productivity and improve the ecological environment.To investigate the eco-environmental benefits brought by the Grain for Green Program,the spatiotemporal variations of vegetation cover in the growing season from 2000 to 2010 across the Hekou-Longmen (He-Long) region were analyzed by using remote sensing information,meteorological data and land use data.Moreover,the impacts of climate and human activities on vegetation change were evaluated objectively.Annual vegetation cover in the growing season increased very significantly.Increased vegetation cover occurred in 98.7% of the region,of which the area for vegetation cover improved slightly constituted 79.8% of the whole area.Vegetation moderately improved was mainly distributed in the south of the He-Long region,covering 9.6% of the area,and the area for vegetation basically unchanged concentrated in the middle and upper reaches of the Wuding River.Precipitation was found to be an important natural factor influencing vegetation cover change.The area of vegetation cover showing a significantly positive correlation with precipitation occupied 22.14% of the region.As driven by policies from the Grain for Green Program,forestland increased significantly and land use structure became more intensive.Human activities played a positive and effective role in the protection,restoration and improvement of vegetation in the places where vegetation cover was basically unchanged,even though precipitation declined greatly,and vegetation improved moderately with massive increases of forestland and grassland.
文摘The diffusivity of hydrogen in two Ni3Al alloys (No.1 and No.2) has been measured in the temperature range of 100 degreesC to 420 degreesC using an ultrahigh vacuum gaseous permeation technique. The diffusivity data fall into two segments, in which the hydrogen diffusivity adheres to the Arrhenius form, respectively. From the hydrogen diffusivity, it is conjectured that the hydrogen diffusivity reflects the hydrogen transportation along the grain boundaries at lower temperature and the hydrogen transportation in the lattice at higher temperature. The intergranular fracture of Lit-type intermetallics induced by hydrogen at relative low temperature results from hydrogen transportation along the grain boundaries and not in the lattice.
文摘In the seventies some scientific workers from France and Italy suggested that the grain boundary internal friction peak (named the K (e) over cap peak in the literature) widely accepted as a grain boundary process, is originated from the motion of lattice dislocations. Since this problem is one of fundamental importance, this controversy has drawn much international attention. Started from 1982, the Hefei research group made a critical analysis of the large amount of literature concerning this problem and,performed a series of crucial experiments to clarify the controversy. It is concluded that the irrelevant evidence suggested by the controverters comes from the farfetched interpretation and the mis-identification of the internal friction peaks appeared under various experimental conditions and different states of the specimens.
基金Under the auspices of the National Key Research and Development Program of China(No.2017YFC0504701)National Natural Science Foundation of China(No.41971220,41701119,41471143)National Social Science Foundation of China(No.15ZDA021)
文摘A thorough understanding of the vegetation succession in relation to both climatic changes and anthropogenic activities is vital for the formulation of adaptation strategies that address potential ecosystem challenges.Various climatic factors such as temperature,precipitation,and solar radiation,as well as anthropogenic factors such as ecological engineering and population migration,will affect the conditions for vegetation.However,the relationships among various factors remain unclear and the response of vegetation to climate change and anthropogenic activities in the Loess Plateau of China has not been well established.This study investigated the spatio-temporal characteristics and relationships between vegetation coverage and climatic factors in the Loess Plateau for the period of 1985–2015.Further analysis separated the anthropogenic and climatic factors on vegetation succession based on residual analysis.The results showed that the normalized difference vegetation index(NDVI)followed a significant upward trend with annual change rates of 0.15%during 1985–2015.The trend of human-induced NDVI increase was consistent with the spatial distribution of increasing forest areas in the eastern part of the Loess Plateau.Eco-restoration projects were the main driving factors that promoted vegetation coverage on the Loess Plateau.Furthermore,these results demonstrated that migrants to cities in the Loess Plateau could relieve ecological pressures and promote vegetation restoration.Therefore,the government should strive to increase population mobility and restore vegetation to sustain this particularly fragile ecological environment.
基金Special Fund Project for Innovation Driven Development of Guangxi(Gui Ke AA17204037)Key Science and Technology Project of Guangxi(Gui Ke AA16380017)Team Project of Guangxi Academy of Agricultural Sciences(2015YT60).
文摘Fenlong Technology has been applied to increase yield by 20%-50%,improve quality by 5%,and retain water by 100%in 40 kinds of crop cultivated land and saline-alkali land in 26 provinces of China.This paper clarified for the first time the scientific theory system of Fenlong Technology using three-dimensional space resources"Fenlong Agricultural Nature Theory"and the development of the relative"limits"of agricultural growth,which provides a huge power support and natural force for expanding human living spaces.Through inventing and creating a scientific and technological system of farming tools,farming machinery,farming modes,and magic weapons for cultivation,Fenlong Technology can increase grain,promote ecological development,and greatly expand the living spaces of the Chinese nation and achieve sustainable development.Using Fenlong Technology,China has expanded from the current single"cultivated land agriculture"to the"big pattern agriculture"of Fenlong"cultivated land+saline land+degraded grassland+marginal land+desertified land+river water",flexibly used 147 million ha of"three-dimensional space resources"of land,and the newly increased food,meat,and fish can feed 300 million to 400 million people,increased the water storage by 100 billion m^(3),and reduced the collection of groundwater by 20 million to 60 billion m^(3).
文摘Ghana is rich in forest resources, of whichTerminalia catappa, a wood species of common occurrence is one. Even though sometimes it is used for decorative purposes, however, it grows in the wild. It grows in almost all the regions of the country and does well in the tropics. The parts of the tree such as the leaves, fruits and seeds have been known to be very useful for medicinal and other uses. Some work on the strength properties of the leaves and other parts has also been done, however, strength properties of the wood are yet to be explored. In this study, its mechanical properties such as bending strength, compression parallel to the grain, and shear parallel to the grain properties were determined. The British (BS 373, 1957) and American Society of Testing Materials’ specifications (ASTM D143, 1983) using testing methods for small, clear specimens of wood were used in determining the properties. The results showed that at 18% moisture content the wood has a density of 520 kg/m<sup>3</sup> with a mean modulus of rupture of 86.04 Mpa, compressive strength parallel to the grain of 42.02 Mpa, modulus of elasticity of 10,500 Mpa, and shear strength parallel to the grain of 16.42 N/mm<sup>2</sup>. These strength properties are comparable to that of Strombosia glaucescens. Therefore, T. catappa can be used in applications where this species is used.
基金Foundation: National Natural Science Foundation of China, No.41130748
文摘During the past decade, great efforts have been made to boost the land use trans- formation in the Loess Plateau, especially for reducing soil erosion by vegetation restoration measures. The Grain-for-Green project (GFG) is the largest ecological rehabilitation program in China, which has a positive impact on the vegetation restoration and sustainable devel- opment for the ecologically fragile region of west China. Based on the Landsat TM/ETM im- ages for three time periods (2000, 2005 and 2010), this study applied the GIS technology and a hill-slope analytical model to reveal the spatio-temporal evolutional patterns of returning slope farmland to grassland or woodland in Baota District, Yan'an city of Shaanxi province. Results showed that: (1) from 2000 to 2010, the area of farmland decreased by approximately 35,030 ha, which is the greatest decrease among all the land-use types, whereas grassland, woodland and construction land increased, of which grassland expanded rapidly by 26,380 ha (2) The annual variation rate of land-use dynamics was 1.98% during the period 2000-2010, of which the rate was 1.05% for the 2000-2005 period and 2.92% for the 2005-2010 period, respectively. Over the past decade, returning farmland to woodland or pastures was the main source of increased grassland and woodland, and the reduction of farmland contributed to the increase in grassland and woodland by 97.39% and 85.28%, respectively. (3) As the terrain slope increases, farmland decreased and woodland and grassland increased significantly. Areas with a slope ranging from 15° to 25° and less than 15° were the focus of the GFG project, accounting for 85% of the total area of farmland reduction. Meanwhile, the reduction in farmland was significant and spatially correlated with the increase in woodland and grass- land. (4) Between 2000 and 2010, the area of destruction of grass and trees in grasslands and woodlands for the reclamation of farmland was approximately 4596 ha. The area subject to the GFG policy was 4456 ha with a slope greater than 25° over the decade, but the area of farmland was still 10,357 ha in 2010. Our results indicate that there has still a great potential for returning the steep-slope farmlands to woodlands or grasslands in the Loess Plateau.