Land use/cover change, which in China is characterized by urbanization resulting in a decrease in arable land in the east along with a large area of grassland being cultivated in the west, has been accelerated by rapi...Land use/cover change, which in China is characterized by urbanization resulting in a decrease in arable land in the east along with a large area of grassland being cultivated in the west, has been accelerated by rapid economic development in the last years. All of the above changes will affect sustainable development in the next century. The Chinese Academy of Sciences is conducting a study of land use/cover change over the last ten years based on the integration of remote sensing and GIS technology to establish a multitemporal database covering all of China. Fundamental data for land use/cover for the year 1996 has already been developed by the Chinese Academy of Sciences. In order to reconstruct fundamental land use/cover data for the year 1986, a central data processing and analyzing system and a regional data acquisition, processing and analyzing system have been established and are joined together as a network. After the 1986 database is established, the comparative research on the reduction in arable land, urbanization, desertification, changes in forest and grassland, and lake and wetland land use/cover change will be carried out. In addition, a transect for a key regional comparative study was selected along the Changjiang (Yangtze) River. The driving forces of these changes also will be extracted. The result of this study will be not only make a contribution to global land use/cover change research, but will also support decision making for sustainable national development.展开更多
Although many methods of spatial analysis have been developed for a better understanding and modelling of urban space analysis, there is still a need for exploration of new analytical techniques for modelling urban sp...Although many methods of spatial analysis have been developed for a better understanding and modelling of urban space analysis, there is still a need for exploration of new analytical techniques for modelling urban spaces. Space Syntax models the spatial configurations of urban spaces by using a connectivity graph representation. Such a configuration of space identifies patterns that can be used to study urban structures and human behaviors. This paper tries to present a new methodology to investigate the urban spatial structure by using Space Syntax with the GIS information including land use, buildings’ characteristics and practical evaluations of the potential of the Space Syntax approach with GIS and multivariate analysis technique. Finally we try to offer some recommendations that attempt to improve the identified problems faced in Kitakyushu, Japan.展开更多
Spinal dural arteriovenous fistulas (SDAVF) account for about 70% of all spinal AV shunts. We re-port on a 56-year-old male patient with progressive neurological symptoms. Pre- and post-contrast MR imaging of the spin...Spinal dural arteriovenous fistulas (SDAVF) account for about 70% of all spinal AV shunts. We re-port on a 56-year-old male patient with progressive neurological symptoms. Pre- and post-contrast MR imaging of the spine, including contrast-enhanced MR angiography was done on a 1.5 T MR scanner. In addition a special (pre-contrast) 3D turbo-spin-echo sequence with variable flip angle evolution (SPACE) was performed providing a slice thickness of 0.9 mm. T2-weighted images showed extensive widened and tortuous vascular structures with typical flow voids intradurally due to dilated pial veins. The origin of the spinal dural arteriovenous fistula was found to be the radiculomeningeal artery at level D10/11 on the left side, visualized by the T2-weighted 3D SPACE sequence and CE MRA. After imaging the patient was referred to an interventional neuroradiology department for therapy. With the detailed information from MR imaging concerning the fistula level the interventional radiologist was able to find the fistula immediately and consequently treated it successfully by endovascular therapy. Interpreting the MR images of this obvious case of a SDAVF, SPACE sequence after post processing with 3D MPR software directly led to the location of the AV shunt at D10/11 on the left side, better than 3D contrast-enhanced MR angiography did. Therefore, SPACE can be a useful adjunct in further evaluation of spinal dural arteriovenous fistula and especially in defining fistula level.展开更多
Quantum technology establishes a foundation for secure communication via quantum key distribution （QKD）. In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. I...Quantum technology establishes a foundation for secure communication via quantum key distribution （QKD）. In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. In order to construct this network, it is economical to consider small-sized and low-cost QKD payloads, which can be assembled on satellites with different sizes, such as space stations. Here we report an experimental demonstration of space-to-ground QKD using a small-sized payload, from Tiangong-2 space lab to Nanshan ground station. The 57.9-kg payload integrates a tracking system, a QKD transmitter along with modules for synchronization, and a laser communication transmitter. In the space lab, a 50MHz vacuum＋weak decoy-state optical source is sent through a reflective telescope with an aperture of 200mm. On the ground station, a telescope with an aperture of 1200mm collects the signal photons. A stable and high-transmittance communication channel is set up with a high-precision bidirectional tracking system, a polarization compensation module, and a synchronization system. When the quantum link is successfully established, we obtain a key rate over 100bps with a communication distance up to 719km. Together with our recent development of QKD in daylight, the present demonstration paves the way towards a practical satellite-constellation-based global quantum secure network with small-sized QKD payloads.展开更多
The traditional space target detection methods mainly use the spatial characteristics of the star map to detect the targets, which can not make full use of the time domain information. This paper presents a new space ...The traditional space target detection methods mainly use the spatial characteristics of the star map to detect the targets, which can not make full use of the time domain information. This paper presents a new space moving target detection method based on time domain features. We firstly construct the time spectral data of star map, then analyze the time domain features of the main objects(target, stars and the background) in star maps, finally detect the moving targets using single pulse feature of the time domain signal. The real star map target detection experimental results show that the proposed method can effectively detect the trajectory of moving targets in the star map sequence, and the detection probability achieves 99% when the false alarm rate is about 8×10^(-5), which outperforms those of compared algorithms.展开更多
Rapid urbanization and population growth of the Amman Area were combined with land resource degradation when the city was heading for mounting urbanization from the early 1950s. The deterioration of natural resources ...Rapid urbanization and population growth of the Amman Area were combined with land resource degradation when the city was heading for mounting urbanization from the early 1950s. The deterioration of natural resources and green areas, was coupled with the creation of different urban public open spaces in the city. The transformation from large single-family houses to dense residential apartments was associated with social and behavioral changes among the inhabitants living in the dense apartments. Consequently, a large private sector has been developed to provide public and social spaces. Photo-interpretation and satellite images were used to map and characterize land use/cover changes have been occurred in the Amman area between 1953 and 2017. Maximum Likelihood Classification method was employed to identify land use/cover changes between 1986 and 20017, and GIS was utilized also to map examples of the recently emerged socio-economic open spaces. Excessive urban development in the last two decades, and the adoption of neo-liberal privatization policies by the government, enhanced social stratification and residential segregation. So, instead of encouraging outdoor activity and social interaction among all groups of Amman residents, the freedom of accessibility to major open spaces has been restricted within the same urban fabric, thus, the “two Ammans” paradigm, a “tale of two cities”, has been recently acknowledged.展开更多
To cope with seasonal changes in food availability,animals need to optimize their behaviors,including shifts in temporal activity patterns and spatial use in habitats.Most studies focused on the temporal activity patt...To cope with seasonal changes in food availability,animals need to optimize their behaviors,including shifts in temporal activity patterns and spatial use in habitats.Most studies focused on the temporal activity pattern or habitat use in two-dimensional(2D)space.However,studies on the simultaneous changes in temporal activity patterns and habitat use in three-dimensional(3D)space are limited.In this study,we used the great evening bat(Ia io)to investigate differences in the activity pattern and space use during the summer and autumn.We collected and analyzed the Global Positioning System(GPS)data and activity data obtained from accelerometers.The results showed that bats displayed seasonal variations in their movement patterns.Specifically,compared with summer,I.io individuals were found to extend their foraging duration and adopt a low-energy consumption pattern of activity in autumn.Furthermore,there was a notable increase in the vertical extent of the 3D habitat utilization range for these bats,although the 2D habitat size in autumn remained similar to that in summer.These changes manifested both temporally and spatially,potentially as a response to the reduced availability of insect resources from summer to autumn,and the arrival of migratory birds in autumn as an alternative food source.Our results suggest that I.io seasonally adjust their foraging strategies and spatial use from two to three dimensions.Our study provides important insights into the seasonal behaviour dynamics of bats during summer and autumn,which may contribute to understanding their ecological strategies and inform conservation efforts.展开更多
With the expansion of the female player base and the increase in their purchasing power,the female-oriented game market has gradually risen.This paper employs the Uses and Gratifications Theory as a framework,using th...With the expansion of the female player base and the increase in their purchasing power,the female-oriented game market has gradually risen.This paper employs the Uses and Gratifications Theory as a framework,using the successful case of Love and Deep Space to explore how female players satisfy their specific social and psychological needs through gaming.The study finds that female-oriented games effectively meet the diverse needs of female players in terms of content design,interactive experiences,and community building,further promoting the prosperity and development of the female-oriented game market.展开更多
Analysis on the investigation and evaluation data of afforestation space suitability in Nanyang City reveals that there are a total of 47,394 issued land parcels,covering an area of 102,400 hm^(2).Among these,20,834 p...Analysis on the investigation and evaluation data of afforestation space suitability in Nanyang City reveals that there are a total of 47,394 issued land parcels,covering an area of 102,400 hm^(2).Among these,20,834 parcels are suitable for afforestation with an area of 35,300 hm^(2),while 7,220 parcels are planned for afforestation but not yet implemented,covering an area of 19,900 hm^(2).Additionally,there are 26,560 parcels classified as unsuitable for afforestation with an area of 67,100 hm^(2).There are also 13,614 parcels,with an area of 15,400 hm^(2),that meet the criteria for afforestation space but have not been included in the planning.In view of discrepancies in land type classification or being outside the original evaluation scope in the investigation of afforestation space suitability evaluation,corresponding recommendations have been proposed to provide valuable references for scientifically formulating territorial greening plans and reasonably reserving afforestation space.展开更多
目的对比高分辨率与低分辨率三维快速自转回波成像技术(3D-Sampling Perfection with Application-Optimized Contrasts by using Different Flip Angle Evolutions,3D-SPACE)序列在磁共振胰胆管水成像(Magnetic Resonance Cholangiopan...目的对比高分辨率与低分辨率三维快速自转回波成像技术(3D-Sampling Perfection with Application-Optimized Contrasts by using Different Flip Angle Evolutions,3D-SPACE)序列在磁共振胰胆管水成像(Magnetic Resonance Cholangiopancreatography,MRCP)中的应用效果。方法使用Siemens Avanto 1.5T磁共振扫描仪对44名受检者行胰胆管水成像,同时采用3D-SPACE的高分辨率与低分辨率序列扫描,两名高年资医师对成像效果进行评价和评分,评分的结果采用秩和校验进行统计学分析。结果高分辨率3D-SPACE原始图像对微小病变显示更清晰;低分辨率3D-SPACE成像时间更快;最大密度投影(Maximum Intensity Projection,MIP)重建图像质量无统计学差异(胆总管显示评分差异:P=0.899,左、右肝内胆管、主胰管显示评分差异:P=0.623)。结论对于配合程度较差的受检者应用低分辨率3D-SPACE更易获得较理想图像。展开更多
文摘Land use/cover change, which in China is characterized by urbanization resulting in a decrease in arable land in the east along with a large area of grassland being cultivated in the west, has been accelerated by rapid economic development in the last years. All of the above changes will affect sustainable development in the next century. The Chinese Academy of Sciences is conducting a study of land use/cover change over the last ten years based on the integration of remote sensing and GIS technology to establish a multitemporal database covering all of China. Fundamental data for land use/cover for the year 1996 has already been developed by the Chinese Academy of Sciences. In order to reconstruct fundamental land use/cover data for the year 1986, a central data processing and analyzing system and a regional data acquisition, processing and analyzing system have been established and are joined together as a network. After the 1986 database is established, the comparative research on the reduction in arable land, urbanization, desertification, changes in forest and grassland, and lake and wetland land use/cover change will be carried out. In addition, a transect for a key regional comparative study was selected along the Changjiang (Yangtze) River. The driving forces of these changes also will be extracted. The result of this study will be not only make a contribution to global land use/cover change research, but will also support decision making for sustainable national development.
文摘Although many methods of spatial analysis have been developed for a better understanding and modelling of urban space analysis, there is still a need for exploration of new analytical techniques for modelling urban spaces. Space Syntax models the spatial configurations of urban spaces by using a connectivity graph representation. Such a configuration of space identifies patterns that can be used to study urban structures and human behaviors. This paper tries to present a new methodology to investigate the urban spatial structure by using Space Syntax with the GIS information including land use, buildings’ characteristics and practical evaluations of the potential of the Space Syntax approach with GIS and multivariate analysis technique. Finally we try to offer some recommendations that attempt to improve the identified problems faced in Kitakyushu, Japan.
文摘Spinal dural arteriovenous fistulas (SDAVF) account for about 70% of all spinal AV shunts. We re-port on a 56-year-old male patient with progressive neurological symptoms. Pre- and post-contrast MR imaging of the spine, including contrast-enhanced MR angiography was done on a 1.5 T MR scanner. In addition a special (pre-contrast) 3D turbo-spin-echo sequence with variable flip angle evolution (SPACE) was performed providing a slice thickness of 0.9 mm. T2-weighted images showed extensive widened and tortuous vascular structures with typical flow voids intradurally due to dilated pial veins. The origin of the spinal dural arteriovenous fistula was found to be the radiculomeningeal artery at level D10/11 on the left side, visualized by the T2-weighted 3D SPACE sequence and CE MRA. After imaging the patient was referred to an interventional neuroradiology department for therapy. With the detailed information from MR imaging concerning the fistula level the interventional radiologist was able to find the fistula immediately and consequently treated it successfully by endovascular therapy. Interpreting the MR images of this obvious case of a SDAVF, SPACE sequence after post processing with 3D MPR software directly led to the location of the AV shunt at D10/11 on the left side, better than 3D contrast-enhanced MR angiography did. Therefore, SPACE can be a useful adjunct in further evaluation of spinal dural arteriovenous fistula and especially in defining fistula level.
基金Supported by China Manned Space Program,Technology and Engineering Center for Space Utilization Chinese Academy of Sciences,Chinese Academy of Sciencesthe National Natural Science Foundation of China
文摘Quantum technology establishes a foundation for secure communication via quantum key distribution （QKD）. In the last two decades, the rapid development of QKD makes a global quantum communication network feasible. In order to construct this network, it is economical to consider small-sized and low-cost QKD payloads, which can be assembled on satellites with different sizes, such as space stations. Here we report an experimental demonstration of space-to-ground QKD using a small-sized payload, from Tiangong-2 space lab to Nanshan ground station. The 57.9-kg payload integrates a tracking system, a QKD transmitter along with modules for synchronization, and a laser communication transmitter. In the space lab, a 50MHz vacuum＋weak decoy-state optical source is sent through a reflective telescope with an aperture of 200mm. On the ground station, a telescope with an aperture of 1200mm collects the signal photons. A stable and high-transmittance communication channel is set up with a high-precision bidirectional tracking system, a polarization compensation module, and a synchronization system. When the quantum link is successfully established, we obtain a key rate over 100bps with a communication distance up to 719km. Together with our recent development of QKD in daylight, the present demonstration paves the way towards a practical satellite-constellation-based global quantum secure network with small-sized QKD payloads.
基金supported by the National High Technology Research and Development Program of China(No.2011AAXXX2035)the Third Phase of Innovative Engineering Projects Foundation of the Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences(No.065X32CN60)
文摘The traditional space target detection methods mainly use the spatial characteristics of the star map to detect the targets, which can not make full use of the time domain information. This paper presents a new space moving target detection method based on time domain features. We firstly construct the time spectral data of star map, then analyze the time domain features of the main objects(target, stars and the background) in star maps, finally detect the moving targets using single pulse feature of the time domain signal. The real star map target detection experimental results show that the proposed method can effectively detect the trajectory of moving targets in the star map sequence, and the detection probability achieves 99% when the false alarm rate is about 8×10^(-5), which outperforms those of compared algorithms.
文摘Rapid urbanization and population growth of the Amman Area were combined with land resource degradation when the city was heading for mounting urbanization from the early 1950s. The deterioration of natural resources and green areas, was coupled with the creation of different urban public open spaces in the city. The transformation from large single-family houses to dense residential apartments was associated with social and behavioral changes among the inhabitants living in the dense apartments. Consequently, a large private sector has been developed to provide public and social spaces. Photo-interpretation and satellite images were used to map and characterize land use/cover changes have been occurred in the Amman area between 1953 and 2017. Maximum Likelihood Classification method was employed to identify land use/cover changes between 1986 and 20017, and GIS was utilized also to map examples of the recently emerged socio-economic open spaces. Excessive urban development in the last two decades, and the adoption of neo-liberal privatization policies by the government, enhanced social stratification and residential segregation. So, instead of encouraging outdoor activity and social interaction among all groups of Amman residents, the freedom of accessibility to major open spaces has been restricted within the same urban fabric, thus, the “two Ammans” paradigm, a “tale of two cities”, has been recently acknowledged.
基金supported by the National Natural Science Foundation of China(32371562,32171489,32301289)Jilin Province Science and Technology Development Project(20250102310JC)Special Foundation for the National Science and Technology Basic Research Program of China(2021FY100301)。
文摘To cope with seasonal changes in food availability,animals need to optimize their behaviors,including shifts in temporal activity patterns and spatial use in habitats.Most studies focused on the temporal activity pattern or habitat use in two-dimensional(2D)space.However,studies on the simultaneous changes in temporal activity patterns and habitat use in three-dimensional(3D)space are limited.In this study,we used the great evening bat(Ia io)to investigate differences in the activity pattern and space use during the summer and autumn.We collected and analyzed the Global Positioning System(GPS)data and activity data obtained from accelerometers.The results showed that bats displayed seasonal variations in their movement patterns.Specifically,compared with summer,I.io individuals were found to extend their foraging duration and adopt a low-energy consumption pattern of activity in autumn.Furthermore,there was a notable increase in the vertical extent of the 3D habitat utilization range for these bats,although the 2D habitat size in autumn remained similar to that in summer.These changes manifested both temporally and spatially,potentially as a response to the reduced availability of insect resources from summer to autumn,and the arrival of migratory birds in autumn as an alternative food source.Our results suggest that I.io seasonally adjust their foraging strategies and spatial use from two to three dimensions.Our study provides important insights into the seasonal behaviour dynamics of bats during summer and autumn,which may contribute to understanding their ecological strategies and inform conservation efforts.
文摘With the expansion of the female player base and the increase in their purchasing power,the female-oriented game market has gradually risen.This paper employs the Uses and Gratifications Theory as a framework,using the successful case of Love and Deep Space to explore how female players satisfy their specific social and psychological needs through gaming.The study finds that female-oriented games effectively meet the diverse needs of female players in terms of content design,interactive experiences,and community building,further promoting the prosperity and development of the female-oriented game market.
文摘Analysis on the investigation and evaluation data of afforestation space suitability in Nanyang City reveals that there are a total of 47,394 issued land parcels,covering an area of 102,400 hm^(2).Among these,20,834 parcels are suitable for afforestation with an area of 35,300 hm^(2),while 7,220 parcels are planned for afforestation but not yet implemented,covering an area of 19,900 hm^(2).Additionally,there are 26,560 parcels classified as unsuitable for afforestation with an area of 67,100 hm^(2).There are also 13,614 parcels,with an area of 15,400 hm^(2),that meet the criteria for afforestation space but have not been included in the planning.In view of discrepancies in land type classification or being outside the original evaluation scope in the investigation of afforestation space suitability evaluation,corresponding recommendations have been proposed to provide valuable references for scientifically formulating territorial greening plans and reasonably reserving afforestation space.
文摘目的对比高分辨率与低分辨率三维快速自转回波成像技术(3D-Sampling Perfection with Application-Optimized Contrasts by using Different Flip Angle Evolutions,3D-SPACE)序列在磁共振胰胆管水成像(Magnetic Resonance Cholangiopancreatography,MRCP)中的应用效果。方法使用Siemens Avanto 1.5T磁共振扫描仪对44名受检者行胰胆管水成像,同时采用3D-SPACE的高分辨率与低分辨率序列扫描,两名高年资医师对成像效果进行评价和评分,评分的结果采用秩和校验进行统计学分析。结果高分辨率3D-SPACE原始图像对微小病变显示更清晰;低分辨率3D-SPACE成像时间更快;最大密度投影(Maximum Intensity Projection,MIP)重建图像质量无统计学差异(胆总管显示评分差异:P=0.899,左、右肝内胆管、主胰管显示评分差异:P=0.623)。结论对于配合程度较差的受检者应用低分辨率3D-SPACE更易获得较理想图像。
