Commercial purity and high purity titanium sheets were initially strained by a new technique, named as friction roll surface processing （FRSP）. Severe strain was imposed into the surface layer and strain gradient wa...Commercial purity and high purity titanium sheets were initially strained by a new technique, named as friction roll surface processing （FRSP）. Severe strain was imposed into the surface layer and strain gradient was formed through the thickness of the sheet. The microstructure and texture in as-strained state were investigated by optical microscopy and X-ray diffraction technique On the surface of the sheets, ultra-fine grains were found to have a sharp texture with a preferred orientation strongly related to the FRSP direction. The evolution of microstructure and crystallographic texture of FRSPed samples during recrystallization were also studied by electron back-scattered diffraction （EBSD） technique after being annealed at selected temperatures and time. The results indicated that the preferred orientations resulting from FRSP and annealing in the surface layer were formed during rolling and its recrystallization textures were reduced by FRSP. In addition, the texture evolved stably without change in main components during the annealing.展开更多
Reducing grain size(i.e.increasing the fraction of grain boundaries)could effectively strengthen nanograined metals but inevitably sacrifices the ductility and possibly causes a strengthening-softening transition belo...Reducing grain size(i.e.increasing the fraction of grain boundaries)could effectively strengthen nanograined metals but inevitably sacrifices the ductility and possibly causes a strengthening-softening transition below a critical grain size.In this work,a facile laser surface remelting-based technique was employed and optimized to fabricate a∼600μm-thick heterogeneous gradient nanostructured layer on an austenitic Hadfield manganese steel,in which the average grain size is gradually decreased from∼200μm in the matrix to only∼8 nm in the nanocrystalline-amorphous core-shell topmost surface.Atomic-scale microstructural characterizations dissected the gradient refinement processes along the gradient direction,i.e.transiting from the dislocations activities and twinning in sub-region to three kinds of martensitic transformations,and finally a multi-phase nanocrystalline-amorphous core-shell structural surface.Mechanical tests(e.g.nanoindentation,bulk-specimen tensile,and micro-pillar compression)were conducted along the gradient direction.It confirms a tensile strength of∼1055 MPa and ductility of∼10.5%in the laser-processed specimen.Particularly,the core-shell structural surface maintains ultra-strong(tensile strength of∼1.6 GPa,micro-pillar compressive strength of∼4 GPa at a strain of∼8%,and nanoindentation hardness of∼7.7 GPa)to overcome the potential strengthening-softening transition.Such significant strengthening effects are ascribed to the strength-ductility synergetic effects-induced extra work hardening ability in gradient nanostructure and the well-maintained dislocation activities inside extremely refined nanograins in the multi-phase nanocrystalline-amorphous core-shell structural surface,which are evidenced by atomic-scale observations and theoretical analysis.This study provides a unique hetero-nanostructure through a facile laser-related technique for extraordinary mechanical performance.展开更多
The microstructures of the nanocrystalline surface layer of a quenched and high temperature tempered 0. 4C- 1Cr steel induced by high-power surface processing （HPSP） technique were characterized by scan- ning eleetr...The microstructures of the nanocrystalline surface layer of a quenched and high temperature tempered 0. 4C- 1Cr steel induced by high-power surface processing （HPSP） technique were characterized by scan- ning eleetron microscopy and transmission electron microscopy. The results indicate that a nanocrystalline layer was fabricated on the surface of the steel 19 using HPSP treatment. The mean grain size in the surface layer is about 11 nm. The nanocrystallization of cementite is prior to that of the matrix phase, ferrite.展开更多
Natural granite stones play an important role in construction and contemporary design because they are often used for cladding,flooring and generally for street decor.Luster is one of the features which are worth focu...Natural granite stones play an important role in construction and contemporary design because they are often used for cladding,flooring and generally for street decor.Luster is one of the features which are worth focussing on in order to determine where and how exactly natural stones should be used.Luster is directly related to the aesthetic features of the stone.展开更多
The Mg-9Li-1Zn(LZ91)alloy was subjected to an ultrasonic surface rolling process(USRP)with varying passes for the purpose of modifying its surface state.The USRP transformed surface residual stress from initial tensil...The Mg-9Li-1Zn(LZ91)alloy was subjected to an ultrasonic surface rolling process(USRP)with varying passes for the purpose of modifying its surface state.The USRP transformed surface residual stress from initial tensile stress to compressive stress,decreasing the surface roughness and increasing the ratio of the β-Li phase.The USRPed LZ91 sample(3 passes)showed superior corrosion resistance,with the corrosion current density changing from 57.11 to 24.70μA cm^(-2),and the polarization resistance increasing from 576.3 to 1146.1Ωcm^(2).According to the corrosion procedure evaluations,in situ observation revealed that the LZ91 alloy initially experiences pitting,which subsequently develops into cracking.The substantial area coverage of the β-Li phase facilitates the formation of a protective film on the surface,effectively delaying localized corrosion.展开更多
Mantle plumes and surface erosion and sediment deposition affect the modes of continental lithospheric rupturing in extensional tectonic settings,modulating the evolution of rifting margins.However,their relative cont...Mantle plumes and surface erosion and sediment deposition affect the modes of continental lithospheric rupturing in extensional tectonic settings,modulating the evolution of rifting margins.However,their relative contributions to the overall evolution of rifting margins and possible roles in the formation of microcontinent are still elusive.Here,we use coupled geodynamic and surface processes numerical modeling to assess the extent to which surface processes may determine the formation of microcontinent during lithospheric stretching in presence or absence of a mantle plume underneath.Our modeling results indicate that fast extension rates and hillslope(i.e.,diffusion)erosion promote ridge jump events and therefore the formation of microcontinents.On the contrary,efficient fluvial erosion and far-reaching sediment transport(i.e.,stream power erosion)inhibits ridge jump events and the formation of microcontinents.The ridge jump event and overall evolution in our numerical models is consistent with the shift from the Mascarene Ridge to the Carlsberg Ridge that determined the formation of the Seychelles microcontinent.We therefore speculate that hillslope erosion,rather than fluvial erosion,was predominant during the formation of the Seychelles,a possible indication of overall dry local climate conditions.展开更多
The source region of the Yellow River, accounting for over 38% of its total runoff, is a critical catchment area,primarily characterized by alpine grasslands. In 2005, the Maqu land surface processes observational sit...The source region of the Yellow River, accounting for over 38% of its total runoff, is a critical catchment area,primarily characterized by alpine grasslands. In 2005, the Maqu land surface processes observational site was established to monitor climate, land surface dynamics, and hydrological variability in this region. Over a 10-year period(2010–19), an extensive observational dataset was compiled, now available to the scientific community. This dataset includes comprehensive details on site characteristics, instrumentation, and data processing methods, covering meteorological and radiative fluxes, energy exchanges, soil moisture dynamics, and heat transfer properties. The dataset is particularly valuable for researchers studying land surface processes, land–atmosphere interactions, and climate modeling, and may also benefit ecological, hydrological, and water resource studies. The report ends with a discussion on perspectives and challenges of continued observational monitoring in this region, focusing on issues such as cryosphere influences, complex topography,and ecological changes like the encroachment of weeds and scrubland.展开更多
The Zoige Basin,located in the eastern region of the Tibetan Plateau of China,is characterized by its climate sensitivity and complex surface environment.It is vital to understand the response of the surface processes...The Zoige Basin,located in the eastern region of the Tibetan Plateau of China,is characterized by its climate sensitivity and complex surface environment.It is vital to understand the response of the surface processes to environmental changes in the Zoige Basin since the last deglaciation,as well as the response of environmental changes and surface processes on the Tibetan Plateau relate to global changes.In August 2020,a field investigation was conducted in the Zoige Basin.A complete set of stratigraphic profile from the high platform at the front of the glacial-diluvial fan in the Maqu reach of the western basin was selected as the research subject.Optically stimulated luminescence(OSL)dating samples and sedimentary samples were collected from key layers and brought back to the laboratory for experimental analysis,and the surface processes and environment changes since the last deglaciation in the Zoige Basin were investigated through particle size analysis and OSL dating.The results showed that during the last glacial period before 14.5 kyr,a substantial glacial-alluvial fan composed of sand and gravel layers was formed by flash flood processes triggered by glacial meltwater and heavy precipitation.In the Bølling-Allerød warm period of 14.5–11.7 kyr,a warm and humid climate prevailed,with the formation of silty bog environments in the shallow depressions at the glacial-alluvial fan's forefront and the development of gray-green bog soil deposits.However,during the Younger Dryas period,an abrupt climate deterioration occurred,with the upper section of the gray-green bog soil layer in the shallow depression to experience folding and deformation due to surface freeze-thaw actions.During the early Holocene period from 11.7 kyr to 8.5 kyr,the climate was relatively dry,resulting in prevalent aeolian sand activitities.Coarse silt accumulated in the shallow depression,and sedimentary facies alternating between aeolian sand and bog soil deposits developed owing to strong wind patterns on the plateau surface.In the warm and humid period from 8.5 kyr to 3.1 kyr,increased weathering and pedogenesis enhanced clay content in sediments,which developed into the paleosol.In the late Holocene,starting from 3.1 kyr,the climate became relatively dry once more,with aeolian sand activity prevalent.The coarse silt that accumulated during the late Holocene transformed into subalpine meadow black soil because of rising temperature and humidity levels.These findings indicated that the developmental process of the high platform in the Maqu reach of the Zoige Basin,which was significant for understanding the environmental changes and surface processes in the source region of the Yellow River since the last deglaciation.展开更多
The problem of ship hull plate processing surface fairing with constraints based on B-spline is solved in this paper. The algorithm for B-spline curve fairing with constraints is one of the most common methods in plan...The problem of ship hull plate processing surface fairing with constraints based on B-spline is solved in this paper. The algorithm for B-spline curve fairing with constraints is one of the most common methods in plane curve fairing. The algorithm can be applied to global and local curve fairing. It can constrain the perturbation range of the control points and the shape variation of the curve, and get a better fairing result in plane curves. In this paper, a new fairing algorithm with constraints for curves and surfaces in space is presented. Then this method is applied to the experiments of ship hull plate processing surface. Finally numerical results are obtained to show the efficiency of this method.展开更多
Surface chemistry focuses on the investigation of the adsorption,migration,assembly,activation,reaction,and desorption of atoms and molecules at surfaces.Surface chemistry plays the pivotal roles in both fundamental s...Surface chemistry focuses on the investigation of the adsorption,migration,assembly,activation,reaction,and desorption of atoms and molecules at surfaces.Surface chemistry plays the pivotal roles in both fundamental science and applied technology.This review will summarize the recent progresses on surface assembly,synthesis and catalysis investigated mainly by scanning tunneling microscopy and atomic force microscopy.Surface assemblies of water and small biomolecules,construction of Sierpin′ski triangles and surface chirality are summarized.On-surface synthesis of conjugated carbo-and heterocycles and other kinds of carbon nanostructures are surveyed.Surface model catalysis,including single-atom catalysis and electrochemical catalysis,are discussed at the single-atom level.展开更多
Thermal Barrier Coatings(TBCs)technology is key to improving the service temperature and the productivity of aircraft engines.The performance and failure life of TBCs are strongly influenced by surface integrity and m...Thermal Barrier Coatings(TBCs)technology is key to improving the service temperature and the productivity of aircraft engines.The performance and failure life of TBCs are strongly influenced by surface integrity and microstructure.Therefore,recognizing failure mechanisms and developing effective surface treatment processes are crucial for further improving the reliability and durability of TBCs.This paper explains the primary reasons for TBC failure,emphasizing on how integrity of surface and interface influences interfacial oxidation,high-temperature erosion,and Calcium-Magnesium-Alumina-Silicate(CMAS)corrosion.Furthermore,this paper completely and rigorously evaluates the research status of TBCs surface treatment processes,including the characteristics and effects of various processes,and describes the requirements and goals of pretreatment and post-treatment.In addition,a potential direction for the development and application of TBCs surface treatment is suggested.展开更多
The laser scanning and CCD image-transmitting measurement method and principle on acquiring 3-D curved surface shape data are discussed. Computer processing technique of 3-D curved surface shape(be called“ 3 - D surf...The laser scanning and CCD image-transmitting measurement method and principle on acquiring 3-D curved surface shape data are discussed. Computer processing technique of 3-D curved surface shape(be called“ 3 - D surface shape”for short) data is analysed. This technique in- cludes these concrete methods and principles such as data smoothing, fitting, reconstructing ,elimi- nating and so on. The example and result about computer processing of 3- D surface shape data are given .展开更多
1.Aims and scope.The international journal Research in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions...1.Aims and scope.The international journal Research in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions.Research in cold regions emphasize particularly on the cold-region-characterized physical,chemical and biological processes and their interactions,and on the response of cryosphere to global change and human activities as well as their effects on environment and the acclimatizable strategies;focus on the objects of glacier,snow,river,lake,sea ice,permafrost and seasonal frozen ground,and periglacial geomorphology,etc.;and think much of cold regions engineering and technology.Research in arid regions emphasize particularly on the arid-region-characterized physical,chemical and biological processes and their interactions,and on the response of arid regions to global change and human activities as well as their effects on environment and the acclimatizable strategies;focus on the objects of desert,oasis,loess,and aeolian landforms,etc.;and support integrated studies on mountain-desert-oasis system in arid watershed with water resources as masterstroke,so as to provide reliable technological support for water safety,ecology safety and food safety in arid regions.展开更多
1.Aims and scope The international journal Research in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions...1.Aims and scope The international journal Research in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions.Research in cold regions emphasize particularly on the cold-region-characterized physical,chemical and biological processes and their interactions,and on the response of cryosphere to global change and human activities as well as their effects on environment and the acclimatizable strategies;focus on the objects of glacier,snow,river,lake,sea ice,permafrost and seasonal frozen ground,and periglacial geomorphology,etc.;and think much of cold regions engineering and technology.展开更多
1.Aims and scope The international journal Research in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions...1.Aims and scope The international journal Research in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions.Research in cold regions emphasize particularly on the cold-region-characterized physical,chemical and biological processes and their interactions,and on the response of cryosphere to global change and human activities as well as their effects on environment and the acclimatizable strategies;focus on the objects of glacier,snow,river,lake,sea ice,permafrost and seasonal frozen ground,and periglacial geomorphology,etc.;and think much of cold regions engineering and technology.Research in arid regions emphasize particularly on the arid-region-characterized physical,chemical and biological processes and their interactions,and on the response of arid regions to global change and human activities as well as their effects on environment and the acclimatizable strategies;focus on the objects of desert,oasis,loess,and aeolian landforms,etc.;and support integrated studies on mountain-desert-oasis system in arid watershed with water resources as masterstroke,so as to provide reliable technological support for water safety,ecology safety and food safety in arid regions.展开更多
1.Aims and scope The international journal Research in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions...1.Aims and scope The international journal Research in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions.Research in cold regions emphasize particularly on the cold-region-characterized physical,chemical and biological processes and their interactions,and on the response of cryosphere to global change and human activities as well as their effects on environment and the acclimatizable strategies;focus on the objects of glacier,snow,river,lake,sea ice,permafrost and seasonal frozen ground,and periglacial geomorphology,etc.;and think much of cold regions engineering and technology.Research in arid regions emphasize particularly on the arid-region-characterized physical.展开更多
There is a wide diversity of landforms in China. The topography of three major ter- races, decreasing in height stepwise from west to east, was formed by the early Miocene. With the commencement of the Great Northern ...There is a wide diversity of landforms in China. The topography of three major ter- races, decreasing in height stepwise from west to east, was formed by the early Miocene. With the commencement of the Great Northern Hemisphere Glaciations （GHGs） and the glacial-interglacial cycles in the Pleistocene, thick loess deposits accumulated in north China, and fluvial terraces were formed and lakes expanded and contracted in eastern and central China. The earliest evidence of hominins in China is dated to ~1.7 Ma; they occupied the monsoon-dominated region for a long interval, until the late Pleistocene, ~50 ka. In this study, we investigated a large area rich in the relics and artifacts of early man. The results indicate that the early humans occupied riverine areas, especially medium-sized fluvial basins, and lake shores. Even in the relatively recent geological past, the occupation and abandonment of settlements were directly forced by the shifting of sand dune fields in the desert-loess transi- tional zone, which in turn was closely associated with variations in the monsoon climate and vegetation patterns. Our observations indicate that landforms were one of the main determi- nants of early human behavior, in that loess tableland, large alluvial plains, desert-Gobi areas, and the Tibetan Plateau, were not suitable environments for early human settlement. We infer that the early humans in China adapted their behavior to specific landforms and landform processes. The monsoon climate, which shapes the large-scale step-like pattern of fluvial landforms, promotes vegetation coverage and dominates soil formation, provides a crucial context for early human adaptation. The adaptation of early humans to earth surface proc- esses in East Asia is investigated for the first time in this study. Future investigations will provide further information that will increase our understanding of the linkage between early human behavior and landform processes in East Asia.展开更多
This paper uses a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to study the interaction between land surface and atmospheric boundary layer processes. The scheme is composed of two main parts: atmospheric boundary la...This paper uses a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to study the interaction between land surface and atmospheric boundary layer processes. The scheme is composed of two main parts: atmospheric boundary layer processes and land surface processes. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feasibility of the model is well proved in this paper. The numerical simulation results from MSPAS show good agreement with reality. The scheme is used to obtain reasonable simulations for diurnal variations of heat balance, potential temperature of boundary layer, and wind field, and spatial distributions of temperature, specific humidity, vertical velocity, turbulence kinetic energy, and turbulence exchange coefficient over desert and oasis. In addition, MSPAS is used to simulate the interaction between desert and oasis at night, and again it obtains reasonable results. This indicates that MSPAS can be used to study the interaction between land surface processes and the atmospheric boundary layer over various underlying surfaces and can be extended for regional climate and numerical weather prediction study.展开更多
On 12 August 2004, Typhoon Rananim （0414） moved inland over China and stagnated over the Poyang Lake area, resulting in torrential rainfall and severe geologic hazards. The Advanced Weather Research and Forecasting ...On 12 August 2004, Typhoon Rananim （0414） moved inland over China and stagnated over the Poyang Lake area, resulting in torrential rainfall and severe geologic hazards. The Advanced Weather Research and Forecasting （ARW-WRF） model and its different land surface models （LSMs） were employed to study the impacts of land surface process on the inland behavior of Typhoon Rananim. Results show that simulations, coupled with LSMs or not, have no significant differences in predicting typhoon track, intensity, and largescale circulation. However, the simulations of mesoscale structure, rainfall rate, and rainfall distribution of typhoon are more reasonable with LSMs than without LSMs. Although differences are slight among LSMs, NOAH is better than the others. Based on outputs using the NOAH scheme, the interaction between land surtace and typhoon was explored in this study. Notably, typhoon rainfall and cloud cover can cool land surface, but rainfall expands the underlying saturated wetland area, which exacerbates the asymmetric distribution of surface heat fluxes. Accordingly, an energy frontal zone may form in the lower troposphere that enhances ascending motion and local convection, resulting in heavier rainfall. Moreover, the expanded underlying saturated wetlands provide plentiful moisture and unstable energy for the maintenance of Typhoon Rananim and increased rainfall in return.展开更多
Water is the important resource to guarantee the existence and development of oases in arid areas. To improve the utilization efficiency of water resources in Manas River Basin, this paper investigated the trends and ...Water is the important resource to guarantee the existence and development of oases in arid areas. To improve the utilization efficiency of water resources in Manas River Basin, this paper investigated the trends and periods of runoff based on the runoff and climate data for the past 50 years. Subsequently, with the socioeconomic and water resources data, we studied a comprehensive evaluation on the water security in this area. The results indicated that the stream flows in the three hydrological stations of Hongshanzui, Kensiwat and Bajiahu have sig- nificantly increased and undergone abrupt changes, with periods of 18 and 20 years. According to assessment, water security in the Manas River Basin was at an unsafe level in 2008. In criterion layer, the ecological security index and the index of supply-demand situation are both at the relatively secure level; the quantity index and so- cioeconomic index of water resources are at the unsafe level and basic security level, respectively. Therefore, in order to achieve sustainable economic and social development within the Manas River Basin, it is vital to take a series of effective measures to improve the status of water security.展开更多
基金support in part by Grant-in-aid for Scientific Research from the Japan Society for Promotion of Science under Contract No. 16560605
文摘Commercial purity and high purity titanium sheets were initially strained by a new technique, named as friction roll surface processing （FRSP）. Severe strain was imposed into the surface layer and strain gradient was formed through the thickness of the sheet. The microstructure and texture in as-strained state were investigated by optical microscopy and X-ray diffraction technique On the surface of the sheets, ultra-fine grains were found to have a sharp texture with a preferred orientation strongly related to the FRSP direction. The evolution of microstructure and crystallographic texture of FRSPed samples during recrystallization were also studied by electron back-scattered diffraction （EBSD） technique after being annealed at selected temperatures and time. The results indicated that the preferred orientations resulting from FRSP and annealing in the surface layer were formed during rolling and its recrystallization textures were reduced by FRSP. In addition, the texture evolved stably without change in main components during the annealing.
文摘Reducing grain size(i.e.increasing the fraction of grain boundaries)could effectively strengthen nanograined metals but inevitably sacrifices the ductility and possibly causes a strengthening-softening transition below a critical grain size.In this work,a facile laser surface remelting-based technique was employed and optimized to fabricate a∼600μm-thick heterogeneous gradient nanostructured layer on an austenitic Hadfield manganese steel,in which the average grain size is gradually decreased from∼200μm in the matrix to only∼8 nm in the nanocrystalline-amorphous core-shell topmost surface.Atomic-scale microstructural characterizations dissected the gradient refinement processes along the gradient direction,i.e.transiting from the dislocations activities and twinning in sub-region to three kinds of martensitic transformations,and finally a multi-phase nanocrystalline-amorphous core-shell structural surface.Mechanical tests(e.g.nanoindentation,bulk-specimen tensile,and micro-pillar compression)were conducted along the gradient direction.It confirms a tensile strength of∼1055 MPa and ductility of∼10.5%in the laser-processed specimen.Particularly,the core-shell structural surface maintains ultra-strong(tensile strength of∼1.6 GPa,micro-pillar compressive strength of∼4 GPa at a strain of∼8%,and nanoindentation hardness of∼7.7 GPa)to overcome the potential strengthening-softening transition.Such significant strengthening effects are ascribed to the strength-ductility synergetic effects-induced extra work hardening ability in gradient nanostructure and the well-maintained dislocation activities inside extremely refined nanograins in the multi-phase nanocrystalline-amorphous core-shell structural surface,which are evidenced by atomic-scale observations and theoretical analysis.This study provides a unique hetero-nanostructure through a facile laser-related technique for extraordinary mechanical performance.
文摘The microstructures of the nanocrystalline surface layer of a quenched and high temperature tempered 0. 4C- 1Cr steel induced by high-power surface processing （HPSP） technique were characterized by scan- ning eleetron microscopy and transmission electron microscopy. The results indicate that a nanocrystalline layer was fabricated on the surface of the steel 19 using HPSP treatment. The mean grain size in the surface layer is about 11 nm. The nanocrystallization of cementite is prior to that of the matrix phase, ferrite.
基金part of a project promoted with the support of IGAG-CNR.
文摘Natural granite stones play an important role in construction and contemporary design because they are often used for cladding,flooring and generally for street decor.Luster is one of the features which are worth focussing on in order to determine where and how exactly natural stones should be used.Luster is directly related to the aesthetic features of the stone.
基金financially supported by the National Natural Science Foundation of China(No.52271091)the National Key Research and Development Program of China(No.2021YFB3701100)the Natural Science Foundation Project of Ningxia Province(No.2023AAC03324).
文摘The Mg-9Li-1Zn(LZ91)alloy was subjected to an ultrasonic surface rolling process(USRP)with varying passes for the purpose of modifying its surface state.The USRP transformed surface residual stress from initial tensile stress to compressive stress,decreasing the surface roughness and increasing the ratio of the β-Li phase.The USRPed LZ91 sample(3 passes)showed superior corrosion resistance,with the corrosion current density changing from 57.11 to 24.70μA cm^(-2),and the polarization resistance increasing from 576.3 to 1146.1Ωcm^(2).According to the corrosion procedure evaluations,in situ observation revealed that the LZ91 alloy initially experiences pitting,which subsequently develops into cracking.The substantial area coverage of the β-Li phase facilitates the formation of a protective film on the surface,effectively delaying localized corrosion.
基金financially supported by the National Science Foundation of China(No.41920104010)the China Postdoctoral Science Foundation(No.2024M762767)+3 种基金the Fundamental Research Funds for the Central University,CHD(No.300102264104)by the Postdoctoral Fellowship Program of CPSF(No.GZC20241444)supported by Fondazione Cariplo and Fondazione CDP(No.2022-1546_001)by the Italian Ministry of Education,MUR(Project Dipartimenti di Eccellenza,TECLA,Department of Earth and Environmental Sciences,University of Milano-Bicocca)。
文摘Mantle plumes and surface erosion and sediment deposition affect the modes of continental lithospheric rupturing in extensional tectonic settings,modulating the evolution of rifting margins.However,their relative contributions to the overall evolution of rifting margins and possible roles in the formation of microcontinent are still elusive.Here,we use coupled geodynamic and surface processes numerical modeling to assess the extent to which surface processes may determine the formation of microcontinent during lithospheric stretching in presence or absence of a mantle plume underneath.Our modeling results indicate that fast extension rates and hillslope(i.e.,diffusion)erosion promote ridge jump events and therefore the formation of microcontinents.On the contrary,efficient fluvial erosion and far-reaching sediment transport(i.e.,stream power erosion)inhibits ridge jump events and the formation of microcontinents.The ridge jump event and overall evolution in our numerical models is consistent with the shift from the Mascarene Ridge to the Carlsberg Ridge that determined the formation of the Seychelles microcontinent.We therefore speculate that hillslope erosion,rather than fluvial erosion,was predominant during the formation of the Seychelles,a possible indication of overall dry local climate conditions.
基金supported by the National Natural Science Foundation of China for Distinguished Young Scholars (Grant No.42325502)the 2nd Scientific Expedition to the Qinghai–Tibet Plateau (Grant No.2019QZKK0102)+3 种基金the West Light Foundation of the Chinese Academy of Sciences (Grant No.xbzg-zdsys-202215)the Science and Technology Research Plan of Gansu Province (Grant Nos.23JRRA654 and 20JR10RA070)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No.QCH2019004)iLEAPS (integrated Land Ecosystem–Atmosphere Processes Study)。
文摘The source region of the Yellow River, accounting for over 38% of its total runoff, is a critical catchment area,primarily characterized by alpine grasslands. In 2005, the Maqu land surface processes observational site was established to monitor climate, land surface dynamics, and hydrological variability in this region. Over a 10-year period(2010–19), an extensive observational dataset was compiled, now available to the scientific community. This dataset includes comprehensive details on site characteristics, instrumentation, and data processing methods, covering meteorological and radiative fluxes, energy exchanges, soil moisture dynamics, and heat transfer properties. The dataset is particularly valuable for researchers studying land surface processes, land–atmosphere interactions, and climate modeling, and may also benefit ecological, hydrological, and water resource studies. The report ends with a discussion on perspectives and challenges of continued observational monitoring in this region, focusing on issues such as cryosphere influences, complex topography,and ecological changes like the encroachment of weeds and scrubland.
基金Under the auspices of the National Natural Science Foundation of China(No.41971116,42271046,42277449)Fundamental Research Funds for the Central Universities(No.2020TS102)。
文摘The Zoige Basin,located in the eastern region of the Tibetan Plateau of China,is characterized by its climate sensitivity and complex surface environment.It is vital to understand the response of the surface processes to environmental changes in the Zoige Basin since the last deglaciation,as well as the response of environmental changes and surface processes on the Tibetan Plateau relate to global changes.In August 2020,a field investigation was conducted in the Zoige Basin.A complete set of stratigraphic profile from the high platform at the front of the glacial-diluvial fan in the Maqu reach of the western basin was selected as the research subject.Optically stimulated luminescence(OSL)dating samples and sedimentary samples were collected from key layers and brought back to the laboratory for experimental analysis,and the surface processes and environment changes since the last deglaciation in the Zoige Basin were investigated through particle size analysis and OSL dating.The results showed that during the last glacial period before 14.5 kyr,a substantial glacial-alluvial fan composed of sand and gravel layers was formed by flash flood processes triggered by glacial meltwater and heavy precipitation.In the Bølling-Allerød warm period of 14.5–11.7 kyr,a warm and humid climate prevailed,with the formation of silty bog environments in the shallow depressions at the glacial-alluvial fan's forefront and the development of gray-green bog soil deposits.However,during the Younger Dryas period,an abrupt climate deterioration occurred,with the upper section of the gray-green bog soil layer in the shallow depression to experience folding and deformation due to surface freeze-thaw actions.During the early Holocene period from 11.7 kyr to 8.5 kyr,the climate was relatively dry,resulting in prevalent aeolian sand activitities.Coarse silt accumulated in the shallow depression,and sedimentary facies alternating between aeolian sand and bog soil deposits developed owing to strong wind patterns on the plateau surface.In the warm and humid period from 8.5 kyr to 3.1 kyr,increased weathering and pedogenesis enhanced clay content in sediments,which developed into the paleosol.In the late Holocene,starting from 3.1 kyr,the climate became relatively dry once more,with aeolian sand activity prevalent.The coarse silt that accumulated during the late Holocene transformed into subalpine meadow black soil because of rising temperature and humidity levels.These findings indicated that the developmental process of the high platform in the Maqu reach of the Zoige Basin,which was significant for understanding the environmental changes and surface processes in the source region of the Yellow River since the last deglaciation.
基金Supported by Hi -tech Research and Development Program of China(No. 2001AA421200).
文摘The problem of ship hull plate processing surface fairing with constraints based on B-spline is solved in this paper. The algorithm for B-spline curve fairing with constraints is one of the most common methods in plane curve fairing. The algorithm can be applied to global and local curve fairing. It can constrain the perturbation range of the control points and the shape variation of the curve, and get a better fairing result in plane curves. In this paper, a new fairing algorithm with constraints for curves and surfaces in space is presented. Then this method is applied to the experiments of ship hull plate processing surface. Finally numerical results are obtained to show the efficiency of this method.
基金supported by the National Natural Science Foundation of China(Nos.22225202,92356309,22132007,21991132,22172002)。
文摘Surface chemistry focuses on the investigation of the adsorption,migration,assembly,activation,reaction,and desorption of atoms and molecules at surfaces.Surface chemistry plays the pivotal roles in both fundamental science and applied technology.This review will summarize the recent progresses on surface assembly,synthesis and catalysis investigated mainly by scanning tunneling microscopy and atomic force microscopy.Surface assemblies of water and small biomolecules,construction of Sierpin′ski triangles and surface chirality are summarized.On-surface synthesis of conjugated carbo-and heterocycles and other kinds of carbon nanostructures are surveyed.Surface model catalysis,including single-atom catalysis and electrochemical catalysis,are discussed at the single-atom level.
基金the National Natural Science Foundation of China (Nos.52075362 and 51975399)the Central Government Guides Local Foundation for Science and Technology Development,China (Nos.YDZJSX2022A020 and YDZJSX2022B004).
文摘Thermal Barrier Coatings(TBCs)technology is key to improving the service temperature and the productivity of aircraft engines.The performance and failure life of TBCs are strongly influenced by surface integrity and microstructure.Therefore,recognizing failure mechanisms and developing effective surface treatment processes are crucial for further improving the reliability and durability of TBCs.This paper explains the primary reasons for TBC failure,emphasizing on how integrity of surface and interface influences interfacial oxidation,high-temperature erosion,and Calcium-Magnesium-Alumina-Silicate(CMAS)corrosion.Furthermore,this paper completely and rigorously evaluates the research status of TBCs surface treatment processes,including the characteristics and effects of various processes,and describes the requirements and goals of pretreatment and post-treatment.In addition,a potential direction for the development and application of TBCs surface treatment is suggested.
文摘The laser scanning and CCD image-transmitting measurement method and principle on acquiring 3-D curved surface shape data are discussed. Computer processing technique of 3-D curved surface shape(be called“ 3 - D surface shape”for short) data is analysed. This technique in- cludes these concrete methods and principles such as data smoothing, fitting, reconstructing ,elimi- nating and so on. The example and result about computer processing of 3- D surface shape data are given .
文摘1.Aims and scope.The international journal Research in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions.Research in cold regions emphasize particularly on the cold-region-characterized physical,chemical and biological processes and their interactions,and on the response of cryosphere to global change and human activities as well as their effects on environment and the acclimatizable strategies;focus on the objects of glacier,snow,river,lake,sea ice,permafrost and seasonal frozen ground,and periglacial geomorphology,etc.;and think much of cold regions engineering and technology.Research in arid regions emphasize particularly on the arid-region-characterized physical,chemical and biological processes and their interactions,and on the response of arid regions to global change and human activities as well as their effects on environment and the acclimatizable strategies;focus on the objects of desert,oasis,loess,and aeolian landforms,etc.;and support integrated studies on mountain-desert-oasis system in arid watershed with water resources as masterstroke,so as to provide reliable technological support for water safety,ecology safety and food safety in arid regions.
文摘1.Aims and scope The international journal Research in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions.Research in cold regions emphasize particularly on the cold-region-characterized physical,chemical and biological processes and their interactions,and on the response of cryosphere to global change and human activities as well as their effects on environment and the acclimatizable strategies;focus on the objects of glacier,snow,river,lake,sea ice,permafrost and seasonal frozen ground,and periglacial geomorphology,etc.;and think much of cold regions engineering and technology.
文摘1.Aims and scope The international journal Research in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions.Research in cold regions emphasize particularly on the cold-region-characterized physical,chemical and biological processes and their interactions,and on the response of cryosphere to global change and human activities as well as their effects on environment and the acclimatizable strategies;focus on the objects of glacier,snow,river,lake,sea ice,permafrost and seasonal frozen ground,and periglacial geomorphology,etc.;and think much of cold regions engineering and technology.Research in arid regions emphasize particularly on the arid-region-characterized physical,chemical and biological processes and their interactions,and on the response of arid regions to global change and human activities as well as their effects on environment and the acclimatizable strategies;focus on the objects of desert,oasis,loess,and aeolian landforms,etc.;and support integrated studies on mountain-desert-oasis system in arid watershed with water resources as masterstroke,so as to provide reliable technological support for water safety,ecology safety and food safety in arid regions.
文摘1.Aims and scope The international journal Research in Cold and Arid Regions,is devoted to publishing the latest research achievements in processes and the patterns of the Earth surface system in cold and arid regions.Research in cold regions emphasize particularly on the cold-region-characterized physical,chemical and biological processes and their interactions,and on the response of cryosphere to global change and human activities as well as their effects on environment and the acclimatizable strategies;focus on the objects of glacier,snow,river,lake,sea ice,permafrost and seasonal frozen ground,and periglacial geomorphology,etc.;and think much of cold regions engineering and technology.Research in arid regions emphasize particularly on the arid-region-characterized physical.
基金Foundation： National Natural Science Foundation of China, No.41472138, No.41401220, No.41472026 The CAS Strate- gic Priority Research Program Grant B, No.XDPB05 The Ministry of Science and Technology of China, No.2016YFA0600503
文摘There is a wide diversity of landforms in China. The topography of three major ter- races, decreasing in height stepwise from west to east, was formed by the early Miocene. With the commencement of the Great Northern Hemisphere Glaciations （GHGs） and the glacial-interglacial cycles in the Pleistocene, thick loess deposits accumulated in north China, and fluvial terraces were formed and lakes expanded and contracted in eastern and central China. The earliest evidence of hominins in China is dated to ~1.7 Ma; they occupied the monsoon-dominated region for a long interval, until the late Pleistocene, ~50 ka. In this study, we investigated a large area rich in the relics and artifacts of early man. The results indicate that the early humans occupied riverine areas, especially medium-sized fluvial basins, and lake shores. Even in the relatively recent geological past, the occupation and abandonment of settlements were directly forced by the shifting of sand dune fields in the desert-loess transi- tional zone, which in turn was closely associated with variations in the monsoon climate and vegetation patterns. Our observations indicate that landforms were one of the main determi- nants of early human behavior, in that loess tableland, large alluvial plains, desert-Gobi areas, and the Tibetan Plateau, were not suitable environments for early human settlement. We infer that the early humans in China adapted their behavior to specific landforms and landform processes. The monsoon climate, which shapes the large-scale step-like pattern of fluvial landforms, promotes vegetation coverage and dominates soil formation, provides a crucial context for early human adaptation. The adaptation of early humans to earth surface proc- esses in East Asia is investigated for the first time in this study. Future investigations will provide further information that will increase our understanding of the linkage between early human behavior and landform processes in East Asia.
基金supported by the National Natural Science Foundation of China (Grant No.40275004)the State Key Laboratory of Atmosphere Physics and Chemistry,and the City University of Hong Kong(Grant No.8780046)the City University of Hong Kong Strategic Research(Grant No.7001038)
文摘This paper uses a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to study the interaction between land surface and atmospheric boundary layer processes. The scheme is composed of two main parts: atmospheric boundary layer processes and land surface processes. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feasibility of the model is well proved in this paper. The numerical simulation results from MSPAS show good agreement with reality. The scheme is used to obtain reasonable simulations for diurnal variations of heat balance, potential temperature of boundary layer, and wind field, and spatial distributions of temperature, specific humidity, vertical velocity, turbulence kinetic energy, and turbulence exchange coefficient over desert and oasis. In addition, MSPAS is used to simulate the interaction between desert and oasis at night, and again it obtains reasonable results. This indicates that MSPAS can be used to study the interaction between land surface processes and the atmospheric boundary layer over various underlying surfaces and can be extended for regional climate and numerical weather prediction study.
基金financed by the National Grand Fundamental Research 973 Program of China (Grant No. 2009CB421504)the Natural Science Foundation of China (Grant Nos. 41175063,40975032,and 41275066)
文摘On 12 August 2004, Typhoon Rananim （0414） moved inland over China and stagnated over the Poyang Lake area, resulting in torrential rainfall and severe geologic hazards. The Advanced Weather Research and Forecasting （ARW-WRF） model and its different land surface models （LSMs） were employed to study the impacts of land surface process on the inland behavior of Typhoon Rananim. Results show that simulations, coupled with LSMs or not, have no significant differences in predicting typhoon track, intensity, and largescale circulation. However, the simulations of mesoscale structure, rainfall rate, and rainfall distribution of typhoon are more reasonable with LSMs than without LSMs. Although differences are slight among LSMs, NOAH is better than the others. Based on outputs using the NOAH scheme, the interaction between land surtace and typhoon was explored in this study. Notably, typhoon rainfall and cloud cover can cool land surface, but rainfall expands the underlying saturated wetland area, which exacerbates the asymmetric distribution of surface heat fluxes. Accordingly, an energy frontal zone may form in the lower troposphere that enhances ascending motion and local convection, resulting in heavier rainfall. Moreover, the expanded underlying saturated wetlands provide plentiful moisture and unstable energy for the maintenance of Typhoon Rananim and increased rainfall in return.
基金supported by the National Natural Science Foundation of China (41001066)the National Basic Research Program of China (Program 973) (2009CB421308)the Ministry of Water Resources’ Special Funds for Scientific Research on Public Causes (201101049)
文摘Water is the important resource to guarantee the existence and development of oases in arid areas. To improve the utilization efficiency of water resources in Manas River Basin, this paper investigated the trends and periods of runoff based on the runoff and climate data for the past 50 years. Subsequently, with the socioeconomic and water resources data, we studied a comprehensive evaluation on the water security in this area. The results indicated that the stream flows in the three hydrological stations of Hongshanzui, Kensiwat and Bajiahu have sig- nificantly increased and undergone abrupt changes, with periods of 18 and 20 years. According to assessment, water security in the Manas River Basin was at an unsafe level in 2008. In criterion layer, the ecological security index and the index of supply-demand situation are both at the relatively secure level; the quantity index and so- cioeconomic index of water resources are at the unsafe level and basic security level, respectively. Therefore, in order to achieve sustainable economic and social development within the Manas River Basin, it is vital to take a series of effective measures to improve the status of water security.
