The Loess positive and negative terrains （P-N terrains）, which are widely distributed on the Loess Plateau, are discussed for the first time by introducing its characteristic, demarcation as well as extraction metho...The Loess positive and negative terrains （P-N terrains）, which are widely distributed on the Loess Plateau, are discussed for the first time by introducing its characteristic, demarcation as well as extraction method from high-resolution Digital Elevation Models. Using 5 m-resolution DEMs as original test data, P-N terrains of 48 geomorphological units in different parts of Shaanxi Loess Plateau are extracted accurately. Then six indicators for depicting the geomorphologic landscape and spatial configuration characteristic of P-N terrains are proposed. The spatial distribution rules of these indicators and the relationship between the P-N terrains and Loess relief are discussed for further understanding of Loess landforms. Finally, with the integration of P-N terrains and traditional terrain indices, a series of un-supervised classification methods are applied to make a proper landform classification in northern Shaanxi. Results show that P-N terrains are an effect clue to reveal energy and substance distribution rules on the Loess Plateau. A continuous change of P-N terrains from south to north in Shaanxi Loess Plateau shows an obvious spatial difference of Loess land-forms and the positive terrain area only accounted for 60.5% in this region. The P-N terrains participant landform classification method increases validity of the result, especially in the Loess tableland, Loess tableland-ridge and the Loess low-hill area. This research is significant on the study of Loess landforms with the Digital Terrains Analysis methods.展开更多
The positive and negative terrains(P-N terrains) widely distributed across China's Loess Plateau constitute the dual structure characteristic of loess landforms. Analysis of loess P-N terrains at the watershed sca...The positive and negative terrains(P-N terrains) widely distributed across China's Loess Plateau constitute the dual structure characteristic of loess landforms. Analysis of loess P-N terrains at the watershed scale can serve to elucidate the structural characteristics and spatial patterns of P-N terrains, which benefits a better understanding of watershed evolution and suitable scales for loess landform research. The Two-Term Local Quadrat Variance Analysis(TTLQV) is calculated as the average of the square of the difference between the block totals of all possible adjacent pairs of block size, which can be used to detect both the scale and the intensity of landscape patches(e.g., plant/animal communities and gully networks). In this study, we determined the latitudinal and longitudinal spatial scale of P-N terrain patterns within 104 uniformly distributed watersheds in our target soil and water conservation region. The results showed that TTLQV is very effective for examining the scale of P-N terrain patterns. There were apparently three types of P-N terrain pattern in latitudinal direction(i.e., Loess Tableland type, Loess Hill type, and Transitional Form between Sand and Loess type), whereas there were both lower and higher values for P-N terrain pattern scales in all loess landforms in the longitudinal direction. The P-N terrain pattern alsoclearly presented anisotropy, suggesting that gully networks in the main direction were well-developed while others were relatively undeveloped. In addition, the relationships between the first scales and controlling factors(i.e., gully density, nibble degree, watershed area, mean watershed slope, NDVI, precipitation, loess thickness, and loess landforms) revealed that the first scales are primarily controlled by watershed area and loess landforms. This may indicate that the current spatial pattern of P-N terrains is characterized by internal force. In selecting suitable study areas in China' Loess Plateau, it is crucial to understand four control variables: the spatial scale of the P-N terrain pattern, the watershed area, the main direction of the watershed, and the loess landforms.展开更多
Local temperature changes in mountain areas are significantly affected by the uplifted mountain terrains. Understanding how temperature increase with mountain terrains is an important component in accurately modeling ...Local temperature changes in mountain areas are significantly affected by the uplifted mountain terrains. Understanding how temperature increase with mountain terrains is an important component in accurately modeling the spatial distribution of temperature. The study, after minimizing the effect of elevation and latitude, quantitatively simulated the temperature increase in the uplifted mountain terrains, described the characteristics in the spatial distribution of warming areas with different magnitudes, and identified the correlated indices of mountain bodies for warming. Selecting Yunnan Province in southwest China as the study area, we simulated the warming field on a baseline surface at the average elevation of 2000 m and average latitude of 24.96°. The results indicated that the warming magnitudes in different local areas varied with the change in the spatial locations, and the warming process concentrated in the mountainous regions. Throughout the entire study area, the warming field presented a general pattern of three terraces from the regions of high mountains to middle mountains and then low mountains. The areasof high warming magnitude mainly surrounded large mountain bodies and were distributed on the upper part. The areas of low warming magnitude clustered in the valleys and basins of the middle mountain region, mostly on the lower part of the large mountain bodies and its branches. The areas with zero warming magnitude occurred in the low mountains and broad valleys, which were distributed largely on the lower parts of the middle mountains and in most of the valleys. Quantified sampling analysis demonstrated good positive correlation between the warming magnitudes in uplifted mountain terrains and the volume index of the mountain body, as well as elevation difference, with the coefficients corresponding to 0.82 and 0.91, respectively.展开更多
The effect of wind environment is becoming increasingly important in analyzing and selecting sites for better naturalventilation of residential buildings, external comfort, and pollution dispersion. The mainpurpose of...The effect of wind environment is becoming increasingly important in analyzing and selecting sites for better naturalventilation of residential buildings, external comfort, and pollution dispersion. The mainpurpose of this study was to develop a setof methods for wind environment assessment in coastal concave terrains. This set of methods can be used to provide quantifiableindicators of preferable wind conditions and help site analysis. Firstly, a total of 20 types of coastal bays with concave terrains inEast Asia were characterized to find ideal locations. The selected areas were divided into five categories according to the mainterrain features. Then a sample database for the concave terrains was compiled for modelling comparisons. Secondly, a number ofkey wind variables were identified. Computational fluid dynamics （CFD） models of the typical coastal concave terrains identifiedas a result of the study were created, and the local wind environments were simulated with input from geographic informationsystem （GIS） and statistic package for social science （SPSS） analysis. A measure of wind suitability was proposed that takes windvelocity and wind direction into account using GIS. Finally, SPSS was used to find the relationship between wind suitability andkey terrain factors. The results showed that wind suitability was significantly associated with terrain factors, especially altitude.The results suggest that residential building sites should be selected such that their bay openings face the direction of the prevailingwind and that the opposite direction should be avoided.展开更多
The classification of thematic mapper imagery in areas with strong topographic variations has proven problematic in the past using a single classifier, due to the changing sun illumination geometry. This often results...The classification of thematic mapper imagery in areas with strong topographic variations has proven problematic in the past using a single classifier, due to the changing sun illumination geometry. This often results in the phenomena of identical object with dissimilar spectrum and different objects with similar spectrum. In this paper, an integrated classification method that combines a decision tree with slope data, tasseled cap transformation indices and maximum likelihood classifier is introduced, to find an optimal classification method for thematic mapper imagery of plain and highland terrains. A Landsat 7 ETM+ image acquired over Hangzhou Bay, in eastern China was used to test the method. The results indicate that the performance of the inte- grated classifier is acceptably good in comparison with that of the existing most widely used maximum likelihood classifier. The integrated classifier depends on hypsography (variation in topography) and the characteristics of ground truth objects (plant and soil). It can greatly reduce the influence of the homogeneous spectrum caused by topographic variation. This integrated classifier might potentially be one of the most accurate classifiers and valuable tool for land cover and land use mapping of plain and highland terrains.展开更多
In order to evaluate the impact of off-road terrains on the ride comfort of construction vehicles,a nonlinear dynamic model of the construction vehicles interacting with the terrain deformations is established based o...In order to evaluate the impact of off-road terrains on the ride comfort of construction vehicles,a nonlinear dynamic model of the construction vehicles interacting with the terrain deformations is established based on Matlab/Simulink software.The weighted root mean square(RMS)acceleration responses and the power spectral density(PSD)acceleration responses of the driver s seat heave,the pitch and roll angle of the cab in the low-frequency region are chosen as objective functions under different operation conditions of the vehicle.The results show that the impact of off-road terrains on the driver s ride comfort and health is clear under various conditions of deformable terrains and range of vehicle velocities.In particular,the driver s ride comfort is greatly affected by a soil terrain while the comfortable shake of the driver is strongly affected by a sand terrain.In addition,when the vehicle travels on a poor soil terrain in the frequency range below 4 Hz,more resonance peaks of acceleration PSD responses occurred than that on a rigid road of ISO 2631-1 level C.Thus,the driver s health is significantly affected by the deformable terrain in a low-frequency range.展开更多
In Pakistan,the solar analogue has been addressed but its surface geographical parameterization has given least attention.Inappropriate density of stations and their spatial coverage particularly in difficult peripher...In Pakistan,the solar analogue has been addressed but its surface geographical parameterization has given least attention.Inappropriate density of stations and their spatial coverage particularly in difficult peripheral national territories,little or no solar radiation data,non-satisfactory sunshine hours data,and low quality of ground observed cloud cover data create a situation in which the spatial modeling of Extraterrestrial Solar Radiation(ESR) and its ground parameterization got sufficient scope.The Digital Elevation Model (DEM) input into Geographic Information System (GIS) is a compatible tool to demonstrate the spatial distribution of ESR over the rugged terrains of the study domain.For the first time,distributed modeling of ESR is done over the rugged terrains of Pakistan,based on DEM and ArcGIS..Results clearly depict that the complex landforms profoundly disrupt the zonal distribution of ESR in Pakistan.The screening impact of topography is higher on spatial distribution of ESR in winter and considerably low in summer.The combined effect of topography and latitude is obvious.Hence,the model was further testified by plotting Rb (ratio of ESR quantity over rugged terrain against plane surface) against azimuth at different latitudes with different angled slopes.The results clearly support the strong screening effect of rugged terrain through out the country especially in Himalayas,Karakoram and Hindukush (HKH),western border mountains and Balochistan Plateau.This model can be instrumental as baseline geospatial information for scientific investigations in Pakistan,where substantial fraction of national population is living in mountainous regions.展开更多
The major results about magnetic petrology of Archearn high grade terrains in the world are reviewed in this article, focusing on the relationship between rock magnetism and deformation, and metamorphism and intensit...The major results about magnetic petrology of Archearn high grade terrains in the world are reviewed in this article, focusing on the relationship between rock magnetism and deformation, and metamorphism and intensity of magnetization of the lower continental crust. The important problems about the magnetic study of rocks for high grade terrains are advanced.展开更多
The research was carried out in Dar es Salaam’s Makongo and Goba neighbourhoods using an exploratory method covering 200 questionnaires,100 for Goba and 100 for Makongo respectively.There were two significant issues ...The research was carried out in Dar es Salaam’s Makongo and Goba neighbourhoods using an exploratory method covering 200 questionnaires,100 for Goba and 100 for Makongo respectively.There were two significant issues observed:To begin,data from 2003 to 2017 reveal a large increase in urbanisation in both locations.Furthermore,urbanisation led to an increase in hard surface areas,which,according to the analysis,contributed to an increase in surface runoff,which had detrimental consequences for hilly residential settlements,resulting in downstream floods,building destruction,and loss of life and properties.Few residents were aware of water harvesting methods as a technique to deal with surface runoff,but they were not aware that they might be used to harvest water for future use.Policy to harvest,retain and use rainwater is recommended,whereby each plot owner should contain water from his/her plot by harvesting,collecting and retaining it for home use such as farming,fish ponds and other uses.展开更多
In 2025,I had the honor of delivering keynote speeches at the conferences of the International Society for Diet and Activity Methods in Toronto,Canada,and the International Society of Behavioural Nutrition and Physica...In 2025,I had the honor of delivering keynote speeches at the conferences of the International Society for Diet and Activity Methods in Toronto,Canada,and the International Society of Behavioural Nutrition and Physical Activity in Auckland,Aotearoa,New Zealand.These opportunities prompted deep reflection on scientific research in general,and on physical activity and health research specifically.展开更多
In the field of hexapod robot control,the application of central pattern generators(CPG)and deep reinforcement learning(DRL)is becoming increasingly common.Compared to traditional control methods that rely on dynamic ...In the field of hexapod robot control,the application of central pattern generators(CPG)and deep reinforcement learning(DRL)is becoming increasingly common.Compared to traditional control methods that rely on dynamic models,both the CPG and the end-to-end DRL approaches significantly simplify the complexity of designing control models.However,relying solely on DRL for control also has its drawbacks,such as slow convergence speed and low exploration efficiency.Moreover,although the CPG can produce rhythmic gaits,its control strategy is relatively singular,limiting the robot's ability to adapt to complex terrains.To overcome these limitations,this study proposes a three-layer DRL control architecture.The high-level reinforcement learning controller is responsible for learning the parameters of the middle-level CPG and the low-level mapping functions,while the middle and low level controllers coordinate the joint movements within and between legs.By integrating the learning capabilities of DRL with the gait generation characteristics of CPG,this method significantly enhances the stability and adaptability of hexapod robots in complex terrains.Experimental results show that,compared to pure DRL approaches,this method significantly improves learning efficiency and control performance,when dealing with complex terrains,it considerably enhances the robot's stability and adaptability compared to pure CPG control.展开更多
Coverage is an important issue in the area of wireless sensor networks, which reflects the monitoring quality of the sensor networks in scenes. Most sensor coverage research focuses on the ideal two-dimensional （2-D...Coverage is an important issue in the area of wireless sensor networks, which reflects the monitoring quality of the sensor networks in scenes. Most sensor coverage research focuses on the ideal two-dimensional （2-D） plane and full three-dimensional （3-D） space. However, in many real-world applications, the target field is a 3-D complex surface, which makes conventional methods unsuitable. In this paper, we study the coverage problem in directional sensor networks for complex 3-D terrains, and design a new surface coverage algorithm. Based on a 3-D directional sensing model of nodes, this algorithm employs grid division, simulated annealing, and local optimum ideas to improve the area coverage ratio by optimizing the position coordinates and the deviation angles of the nodes, which results in coverage enhancement for complex 3-D terrains. We also conduct extensive simulations to evaluate the performance of our algorithms.展开更多
Chinese food aid nourishes over 188,000 Zambians In the arid terrain of Shang’ombo District,approximately 850 km west of Lusaka,Zambia’s capital,Charity Imbuwa received a Chinese food-aid pack and shared it with her...Chinese food aid nourishes over 188,000 Zambians In the arid terrain of Shang’ombo District,approximately 850 km west of Lusaka,Zambia’s capital,Charity Imbuwa received a Chinese food-aid pack and shared it with her children at their home near the Angola border.展开更多
The spatial distribution map of 65 mid-large gold-deposits hosted in the granite-greenstone terrains of the North China Craton is first drawn. These gold deposits mainly concentrate in the Mesozoic remobilized Yinshan...The spatial distribution map of 65 mid-large gold-deposits hosted in the granite-greenstone terrains of the North China Craton is first drawn. These gold deposits mainly concentrate in the Mesozoic remobilized Yinshan-Yanshan-Liaoning-Jilin intracontinental collisional orogenic belt, the northern Qinling and the Jiaodong Mesozoic collisional orogenic belts, and the Mesozoic intracontinental fault-magmatic belts developed along the Taihangshan and the Tan-Lu faults; their mineralizing time is predominantly Jurassic-Cretaceous, i.e. the Yanshanian. The metallogenic geodynamic background is exactly the compression-to-extension transition regime during continental collision.展开更多
A good understanding of the quality of digital elevation model(DEM)is a perquisite for various applications.This study investigates the accuracy of three most recently released 1-arcsec global DEMs(GDEMs,Copernicus,NA...A good understanding of the quality of digital elevation model(DEM)is a perquisite for various applications.This study investigates the accuracy of three most recently released 1-arcsec global DEMs(GDEMs,Copernicus,NASA and AW3D30)in five selected terrains of China,using more than 240,000 high-quality ICESat-2(Ice,Cloud and land Elevation Satellite)ALT08 points.The results indicate the three GDEMs have similar overall vertical accuracy,with RMSE of 6.73(Copernicus),6.59(NASA)and 6.63 m(AW3D30).While the accuracy varies considerably over study areas and among GDEMs.The results show a clear correlation between the accuracy and terrain slopes,and some relationship between the accuracy and land covers.Our analysis reveals the land cover exerts a greater impact on the accuracy than that of the terrain slope for the study area.Visual inspections of terrain representation indicate Copernicus DEM exhibits the greatest detail of terrain,followed by AW3D30,and then by NASADEM.This study has demonstrated that ICESat-2 altimetry offers an important tool for DEM assessment.The findings provide a timely and comprehensive understanding of the quality of newly released GDEMs,which are informative for the selection of suitable DEMs,and for the improvement of GDEM in future studies.展开更多
The effect of terrain shadow, including the self and cast shadows, is one ofthe main obstacles for accurate retrieval of vegetation parameters byremote sensing in rugged terrains. A shadow- eliminated vegetation index...The effect of terrain shadow, including the self and cast shadows, is one ofthe main obstacles for accurate retrieval of vegetation parameters byremote sensing in rugged terrains. A shadow- eliminated vegetation index(SEVI) was developed, which was computed from only red and nearinfrared top-of-atmosphere reflectance without other heterogeneous dataand topographic correction. After introduction of the conceptual modeland feature analysis of conventional wavebands, the SEVI was constructedby ratio vegetation index (RVI), shadow vegetation index (SVI) andadjustment factor (f (Δ)). Then three methods were used to validate theSEVI accuracy in elimination of terrain shadow effects, including relativeerror analysis, correlation analysis between the cosine of solar incidenceangle (cosi) and vegetation indices, and comparison analysis between SEVIand conventional vegetation indices with topographic correction. Thevalidation results based on 532 samples showed that the SEVI relativeerrors for self and cast shadows were 4.32% and 1.51% respectively. Thecoefficient of determination between cosi and SEVI was only 0.032 and thecoefficient of variation (std/mean) for SEVI was 12.59%. The results indicatethat the proposed SEVI effectively eliminated the effect of terrain shadowsand achieved similar or better results than conventional vegetation indiceswith topographic correction.展开更多
Some 5000 years ago,the Chinese“Yellow Emperor”used mobile navigation devices to help his soldiers to march in the heavy smog generated by his enemy in the battle against Chi You,according to the record in the legen...Some 5000 years ago,the Chinese“Yellow Emperor”used mobile navigation devices to help his soldiers to march in the heavy smog generated by his enemy in the battle against Chi You,according to the record in the legendary The Classic of Moun ta ins and Seas(also known as Shan Hai Jing,formerly romanized as the Shan-hai Ching).Since then,making robots cross various rough terrains is always a challenge people trying to tackle.Compared to the wheeled or tracked mo-bile robots,legged pla tforms demonstrate better flexibility and terrain adaptability at the cost of low speed and increased control complexity.展开更多
Tafoni are globally developed on cliffy slopes,and many of them are favorable places for the preservation of stone historical relics.However,the characteristics and formation processes of tafoni in the Loess Plateau a...Tafoni are globally developed on cliffy slopes,and many of them are favorable places for the preservation of stone historical relics.However,the characteristics and formation processes of tafoni in the Loess Plateau are yet to be understood.This paper studied the features of the tafoni on conglomerate slopes in Huoshizhai National Geopark of Ningxia Hui Autonomous Region and discussed its formation processes by field investigation and morphometry,insitu relative humidity(RH)measurement,salt chemistry and X-ray fluorescence spectrometer(XRF)experiments of 24 samples.The bedrock of the tafoni is dominated by reddish fluvial conglomerates of the Lower Cretaceous Heshangpu Formation with abundant chemically unstable components including feldspars,lithic fragments,and calcite cements.The RH values vary from 5%to 100%,but the backwalls of the tafoni have higher RH values than outer surfaces.The more moisture on the backwalls is possibly generated by water influx from the rock interior,resulting in more salt precipitation on the backwalls.As a result,the backwalls have been subject to predominant salt weathering.The dominant salts involved in salt weathering are probably derived from the dissolution of the salt interbeds in the basin,although the chemical dissolution of the unstable components such as feldspars,lithic fragments,and calcite cements might have produced small amounts of salts.The salt types dominantly include nitrates,sulfates,and halite.In the progression of tafoni,the moisture maintenance on the backwalls gives rise to the accretion of salts,which in turn enhance the weathering rates of the backwalls.As a result,the volumes of the tafoni have become enlarged owing to inward growth and coalescence of adjacent smaller ones.展开更多
基金Key Project of National Natural Science Foundation of China, No.40930531 National Youth Science Foundation of China, No.40801148 Anhui Provincial Natural Science Foundation. No. 090412062
文摘The Loess positive and negative terrains （P-N terrains）, which are widely distributed on the Loess Plateau, are discussed for the first time by introducing its characteristic, demarcation as well as extraction method from high-resolution Digital Elevation Models. Using 5 m-resolution DEMs as original test data, P-N terrains of 48 geomorphological units in different parts of Shaanxi Loess Plateau are extracted accurately. Then six indicators for depicting the geomorphologic landscape and spatial configuration characteristic of P-N terrains are proposed. The spatial distribution rules of these indicators and the relationship between the P-N terrains and Loess relief are discussed for further understanding of Loess landforms. Finally, with the integration of P-N terrains and traditional terrain indices, a series of un-supervised classification methods are applied to make a proper landform classification in northern Shaanxi. Results show that P-N terrains are an effect clue to reveal energy and substance distribution rules on the Loess Plateau. A continuous change of P-N terrains from south to north in Shaanxi Loess Plateau shows an obvious spatial difference of Loess land-forms and the positive terrain area only accounted for 60.5% in this region. The P-N terrains participant landform classification method increases validity of the result, especially in the Loess tableland, Loess tableland-ridge and the Loess low-hill area. This research is significant on the study of Loess landforms with the Digital Terrains Analysis methods.
基金supported by the National Natural Science Foundation of China (NO. 41201464, 41371424)the Fundamental Research Funds for the Central Universities of China (GK201703042)
文摘The positive and negative terrains(P-N terrains) widely distributed across China's Loess Plateau constitute the dual structure characteristic of loess landforms. Analysis of loess P-N terrains at the watershed scale can serve to elucidate the structural characteristics and spatial patterns of P-N terrains, which benefits a better understanding of watershed evolution and suitable scales for loess landform research. The Two-Term Local Quadrat Variance Analysis(TTLQV) is calculated as the average of the square of the difference between the block totals of all possible adjacent pairs of block size, which can be used to detect both the scale and the intensity of landscape patches(e.g., plant/animal communities and gully networks). In this study, we determined the latitudinal and longitudinal spatial scale of P-N terrain patterns within 104 uniformly distributed watersheds in our target soil and water conservation region. The results showed that TTLQV is very effective for examining the scale of P-N terrain patterns. There were apparently three types of P-N terrain pattern in latitudinal direction(i.e., Loess Tableland type, Loess Hill type, and Transitional Form between Sand and Loess type), whereas there were both lower and higher values for P-N terrain pattern scales in all loess landforms in the longitudinal direction. The P-N terrain pattern alsoclearly presented anisotropy, suggesting that gully networks in the main direction were well-developed while others were relatively undeveloped. In addition, the relationships between the first scales and controlling factors(i.e., gully density, nibble degree, watershed area, mean watershed slope, NDVI, precipitation, loess thickness, and loess landforms) revealed that the first scales are primarily controlled by watershed area and loess landforms. This may indicate that the current spatial pattern of P-N terrains is characterized by internal force. In selecting suitable study areas in China' Loess Plateau, it is crucial to understand four control variables: the spatial scale of the P-N terrain pattern, the watershed area, the main direction of the watershed, and the loess landforms.
基金supported by the National Natural Science Foundation of China (Grant No. 41561004)the Forestry Industry Research Special Funds for Public Welfare Projects of China (Grant No. 21404402-2)the Scientific and Technological Innovation Talent Project of Yunnan Province (Grant No. 2014HC014)
文摘Local temperature changes in mountain areas are significantly affected by the uplifted mountain terrains. Understanding how temperature increase with mountain terrains is an important component in accurately modeling the spatial distribution of temperature. The study, after minimizing the effect of elevation and latitude, quantitatively simulated the temperature increase in the uplifted mountain terrains, described the characteristics in the spatial distribution of warming areas with different magnitudes, and identified the correlated indices of mountain bodies for warming. Selecting Yunnan Province in southwest China as the study area, we simulated the warming field on a baseline surface at the average elevation of 2000 m and average latitude of 24.96°. The results indicated that the warming magnitudes in different local areas varied with the change in the spatial locations, and the warming process concentrated in the mountainous regions. Throughout the entire study area, the warming field presented a general pattern of three terraces from the regions of high mountains to middle mountains and then low mountains. The areasof high warming magnitude mainly surrounded large mountain bodies and were distributed on the upper part. The areas of low warming magnitude clustered in the valleys and basins of the middle mountain region, mostly on the lower part of the large mountain bodies and its branches. The areas with zero warming magnitude occurred in the low mountains and broad valleys, which were distributed largely on the lower parts of the middle mountains and in most of the valleys. Quantified sampling analysis demonstrated good positive correlation between the warming magnitudes in uplifted mountain terrains and the volume index of the mountain body, as well as elevation difference, with the coefficients corresponding to 0.82 and 0.91, respectively.
基金supported by the National Natural Science Foundation of China(Nos.51208466 and 51238011)the Science and Technology Research Program of Chinese Ministry of Housing and Urban-Rural Development(No.2014R2-036)+2 种基金the Humanities and Social Sciences Research Foundation of the Ministry of Education(No.17YJAZH136)the Natural Science Foundation of Zhejiang Province(No.LY16E0 80011)the Social Sciences Planning Project of Zhejiang Province(No.12JCSH02YB),China
文摘The effect of wind environment is becoming increasingly important in analyzing and selecting sites for better naturalventilation of residential buildings, external comfort, and pollution dispersion. The mainpurpose of this study was to develop a setof methods for wind environment assessment in coastal concave terrains. This set of methods can be used to provide quantifiableindicators of preferable wind conditions and help site analysis. Firstly, a total of 20 types of coastal bays with concave terrains inEast Asia were characterized to find ideal locations. The selected areas were divided into five categories according to the mainterrain features. Then a sample database for the concave terrains was compiled for modelling comparisons. Secondly, a number ofkey wind variables were identified. Computational fluid dynamics （CFD） models of the typical coastal concave terrains identifiedas a result of the study were created, and the local wind environments were simulated with input from geographic informationsystem （GIS） and statistic package for social science （SPSS） analysis. A measure of wind suitability was proposed that takes windvelocity and wind direction into account using GIS. Finally, SPSS was used to find the relationship between wind suitability andkey terrain factors. The results showed that wind suitability was significantly associated with terrain factors, especially altitude.The results suggest that residential building sites should be selected such that their bay openings face the direction of the prevailingwind and that the opposite direction should be avoided.
文摘The classification of thematic mapper imagery in areas with strong topographic variations has proven problematic in the past using a single classifier, due to the changing sun illumination geometry. This often results in the phenomena of identical object with dissimilar spectrum and different objects with similar spectrum. In this paper, an integrated classification method that combines a decision tree with slope data, tasseled cap transformation indices and maximum likelihood classifier is introduced, to find an optimal classification method for thematic mapper imagery of plain and highland terrains. A Landsat 7 ETM+ image acquired over Hangzhou Bay, in eastern China was used to test the method. The results indicate that the performance of the inte- grated classifier is acceptably good in comparison with that of the existing most widely used maximum likelihood classifier. The integrated classifier depends on hypsography (variation in topography) and the characteristics of ground truth objects (plant and soil). It can greatly reduce the influence of the homogeneous spectrum caused by topographic variation. This integrated classifier might potentially be one of the most accurate classifiers and valuable tool for land cover and land use mapping of plain and highland terrains.
基金The Science and Technology Support Program of Jiangsu Province(No.BE2014133)the Prospective Joint Research Program of Jiangsu Province(No.BY2014127-01)
文摘In order to evaluate the impact of off-road terrains on the ride comfort of construction vehicles,a nonlinear dynamic model of the construction vehicles interacting with the terrain deformations is established based on Matlab/Simulink software.The weighted root mean square(RMS)acceleration responses and the power spectral density(PSD)acceleration responses of the driver s seat heave,the pitch and roll angle of the cab in the low-frequency region are chosen as objective functions under different operation conditions of the vehicle.The results show that the impact of off-road terrains on the driver s ride comfort and health is clear under various conditions of deformable terrains and range of vehicle velocities.In particular,the driver s ride comfort is greatly affected by a soil terrain while the comfortable shake of the driver is strongly affected by a sand terrain.In addition,when the vehicle travels on a poor soil terrain in the frequency range below 4 Hz,more resonance peaks of acceleration PSD responses occurred than that on a rigid road of ISO 2631-1 level C.Thus,the driver s health is significantly affected by the deformable terrain in a low-frequency range.
文摘In Pakistan,the solar analogue has been addressed but its surface geographical parameterization has given least attention.Inappropriate density of stations and their spatial coverage particularly in difficult peripheral national territories,little or no solar radiation data,non-satisfactory sunshine hours data,and low quality of ground observed cloud cover data create a situation in which the spatial modeling of Extraterrestrial Solar Radiation(ESR) and its ground parameterization got sufficient scope.The Digital Elevation Model (DEM) input into Geographic Information System (GIS) is a compatible tool to demonstrate the spatial distribution of ESR over the rugged terrains of the study domain.For the first time,distributed modeling of ESR is done over the rugged terrains of Pakistan,based on DEM and ArcGIS..Results clearly depict that the complex landforms profoundly disrupt the zonal distribution of ESR in Pakistan.The screening impact of topography is higher on spatial distribution of ESR in winter and considerably low in summer.The combined effect of topography and latitude is obvious.Hence,the model was further testified by plotting Rb (ratio of ESR quantity over rugged terrain against plane surface) against azimuth at different latitudes with different angled slopes.The results clearly support the strong screening effect of rugged terrain through out the country especially in Himalayas,Karakoram and Hindukush (HKH),western border mountains and Balochistan Plateau.This model can be instrumental as baseline geospatial information for scientific investigations in Pakistan,where substantial fraction of national population is living in mountainous regions.
文摘The major results about magnetic petrology of Archearn high grade terrains in the world are reviewed in this article, focusing on the relationship between rock magnetism and deformation, and metamorphism and intensity of magnetization of the lower continental crust. The important problems about the magnetic study of rocks for high grade terrains are advanced.
文摘The research was carried out in Dar es Salaam’s Makongo and Goba neighbourhoods using an exploratory method covering 200 questionnaires,100 for Goba and 100 for Makongo respectively.There were two significant issues observed:To begin,data from 2003 to 2017 reveal a large increase in urbanisation in both locations.Furthermore,urbanisation led to an increase in hard surface areas,which,according to the analysis,contributed to an increase in surface runoff,which had detrimental consequences for hilly residential settlements,resulting in downstream floods,building destruction,and loss of life and properties.Few residents were aware of water harvesting methods as a technique to deal with surface runoff,but they were not aware that they might be used to harvest water for future use.Policy to harvest,retain and use rainwater is recommended,whereby each plot owner should contain water from his/her plot by harvesting,collecting and retaining it for home use such as farming,fish ponds and other uses.
文摘In 2025,I had the honor of delivering keynote speeches at the conferences of the International Society for Diet and Activity Methods in Toronto,Canada,and the International Society of Behavioural Nutrition and Physical Activity in Auckland,Aotearoa,New Zealand.These opportunities prompted deep reflection on scientific research in general,and on physical activity and health research specifically.
基金supported by the Beijing Natural Science Foundation-Xiaomi Innovation Joint Fund(L243013)the National Natural Science Foundation of China(62172392).
文摘In the field of hexapod robot control,the application of central pattern generators(CPG)and deep reinforcement learning(DRL)is becoming increasingly common.Compared to traditional control methods that rely on dynamic models,both the CPG and the end-to-end DRL approaches significantly simplify the complexity of designing control models.However,relying solely on DRL for control also has its drawbacks,such as slow convergence speed and low exploration efficiency.Moreover,although the CPG can produce rhythmic gaits,its control strategy is relatively singular,limiting the robot's ability to adapt to complex terrains.To overcome these limitations,this study proposes a three-layer DRL control architecture.The high-level reinforcement learning controller is responsible for learning the parameters of the middle-level CPG and the low-level mapping functions,while the middle and low level controllers coordinate the joint movements within and between legs.By integrating the learning capabilities of DRL with the gait generation characteristics of CPG,this method significantly enhances the stability and adaptability of hexapod robots in complex terrains.Experimental results show that,compared to pure DRL approaches,this method significantly improves learning efficiency and control performance,when dealing with complex terrains,it considerably enhances the robot's stability and adaptability compared to pure CPG control.
基金supported by the National Natural Science Foundation of China(Nos.61373137,61572260,61373017,61373139,and 61572261)the Major Program of Jiangsu Higher Education Institutions(No.14KJA520002)Scientific&Technological Support Project of Jiangsu(No.BE2015702)
文摘Coverage is an important issue in the area of wireless sensor networks, which reflects the monitoring quality of the sensor networks in scenes. Most sensor coverage research focuses on the ideal two-dimensional （2-D） plane and full three-dimensional （3-D） space. However, in many real-world applications, the target field is a 3-D complex surface, which makes conventional methods unsuitable. In this paper, we study the coverage problem in directional sensor networks for complex 3-D terrains, and design a new surface coverage algorithm. Based on a 3-D directional sensing model of nodes, this algorithm employs grid division, simulated annealing, and local optimum ideas to improve the area coverage ratio by optimizing the position coordinates and the deviation angles of the nodes, which results in coverage enhancement for complex 3-D terrains. We also conduct extensive simulations to evaluate the performance of our algorithms.
文摘Chinese food aid nourishes over 188,000 Zambians In the arid terrain of Shang’ombo District,approximately 850 km west of Lusaka,Zambia’s capital,Charity Imbuwa received a Chinese food-aid pack and shared it with her children at their home near the Angola border.
文摘The spatial distribution map of 65 mid-large gold-deposits hosted in the granite-greenstone terrains of the North China Craton is first drawn. These gold deposits mainly concentrate in the Mesozoic remobilized Yinshan-Yanshan-Liaoning-Jilin intracontinental collisional orogenic belt, the northern Qinling and the Jiaodong Mesozoic collisional orogenic belts, and the Mesozoic intracontinental fault-magmatic belts developed along the Taihangshan and the Tan-Lu faults; their mineralizing time is predominantly Jurassic-Cretaceous, i.e. the Yanshanian. The metallogenic geodynamic background is exactly the compression-to-extension transition regime during continental collision.
基金supported by the National Natural Science Foundation of China[grant number 41201429,42171375].
文摘A good understanding of the quality of digital elevation model(DEM)is a perquisite for various applications.This study investigates the accuracy of three most recently released 1-arcsec global DEMs(GDEMs,Copernicus,NASA and AW3D30)in five selected terrains of China,using more than 240,000 high-quality ICESat-2(Ice,Cloud and land Elevation Satellite)ALT08 points.The results indicate the three GDEMs have similar overall vertical accuracy,with RMSE of 6.73(Copernicus),6.59(NASA)and 6.63 m(AW3D30).While the accuracy varies considerably over study areas and among GDEMs.The results show a clear correlation between the accuracy and terrain slopes,and some relationship between the accuracy and land covers.Our analysis reveals the land cover exerts a greater impact on the accuracy than that of the terrain slope for the study area.Visual inspections of terrain representation indicate Copernicus DEM exhibits the greatest detail of terrain,followed by AW3D30,and then by NASADEM.This study has demonstrated that ICESat-2 altimetry offers an important tool for DEM assessment.The findings provide a timely and comprehensive understanding of the quality of newly released GDEMs,which are informative for the selection of suitable DEMs,and for the improvement of GDEM in future studies.
基金China National Key Research and Development Plan[grant number 2017YFB0504203]China Scholarship Fund[grant number 201706655028]Natural Science Foundation of Fujian Province[grant number 2017J01658].
文摘The effect of terrain shadow, including the self and cast shadows, is one ofthe main obstacles for accurate retrieval of vegetation parameters byremote sensing in rugged terrains. A shadow- eliminated vegetation index(SEVI) was developed, which was computed from only red and nearinfrared top-of-atmosphere reflectance without other heterogeneous dataand topographic correction. After introduction of the conceptual modeland feature analysis of conventional wavebands, the SEVI was constructedby ratio vegetation index (RVI), shadow vegetation index (SVI) andadjustment factor (f (Δ)). Then three methods were used to validate theSEVI accuracy in elimination of terrain shadow effects, including relativeerror analysis, correlation analysis between the cosine of solar incidenceangle (cosi) and vegetation indices, and comparison analysis between SEVIand conventional vegetation indices with topographic correction. Thevalidation results based on 532 samples showed that the SEVI relativeerrors for self and cast shadows were 4.32% and 1.51% respectively. Thecoefficient of determination between cosi and SEVI was only 0.032 and thecoefficient of variation (std/mean) for SEVI was 12.59%. The results indicatethat the proposed SEVI effectively eliminated the effect of terrain shadowsand achieved similar or better results than conventional vegetation indiceswith topographic correction.
文摘Some 5000 years ago,the Chinese“Yellow Emperor”used mobile navigation devices to help his soldiers to march in the heavy smog generated by his enemy in the battle against Chi You,according to the record in the legendary The Classic of Moun ta ins and Seas(also known as Shan Hai Jing,formerly romanized as the Shan-hai Ching).Since then,making robots cross various rough terrains is always a challenge people trying to tackle.Compared to the wheeled or tracked mo-bile robots,legged pla tforms demonstrate better flexibility and terrain adaptability at the cost of low speed and increased control complexity.
基金financially supported by the National Natural Science Foundation of China(Grant No.42361002)the Fund of Ningxia Hui Autonomous Region(Grant No.2022AAC03665).
文摘Tafoni are globally developed on cliffy slopes,and many of them are favorable places for the preservation of stone historical relics.However,the characteristics and formation processes of tafoni in the Loess Plateau are yet to be understood.This paper studied the features of the tafoni on conglomerate slopes in Huoshizhai National Geopark of Ningxia Hui Autonomous Region and discussed its formation processes by field investigation and morphometry,insitu relative humidity(RH)measurement,salt chemistry and X-ray fluorescence spectrometer(XRF)experiments of 24 samples.The bedrock of the tafoni is dominated by reddish fluvial conglomerates of the Lower Cretaceous Heshangpu Formation with abundant chemically unstable components including feldspars,lithic fragments,and calcite cements.The RH values vary from 5%to 100%,but the backwalls of the tafoni have higher RH values than outer surfaces.The more moisture on the backwalls is possibly generated by water influx from the rock interior,resulting in more salt precipitation on the backwalls.As a result,the backwalls have been subject to predominant salt weathering.The dominant salts involved in salt weathering are probably derived from the dissolution of the salt interbeds in the basin,although the chemical dissolution of the unstable components such as feldspars,lithic fragments,and calcite cements might have produced small amounts of salts.The salt types dominantly include nitrates,sulfates,and halite.In the progression of tafoni,the moisture maintenance on the backwalls gives rise to the accretion of salts,which in turn enhance the weathering rates of the backwalls.As a result,the volumes of the tafoni have become enlarged owing to inward growth and coalescence of adjacent smaller ones.
