期刊文献+
共找到48篇文章
< 1 2 3 >
每页显示 20 50 100
Morphological Evolution of Self-Assembled Sodium Dodecyl Sulfate/Dodecyltrimethylammonium Bromide@Epoxy-β-Cyclodextrin Supramolecular Aggregates Induced by Temperature
1
作者 Qingran Meng Wenwen Xu +2 位作者 Zuobing Xiao Qinfei Ke Xingran Kou 《Journal of Renewable Materials》 EI CAS 2024年第4期629-641,共13页
Bio-based cyclodextrins(CDs)are a common research object in supramolecular chemistry.The special cavity structure of CDs can form supramolecular self-assemblies such as vesicles and microcrystals through weak interact... Bio-based cyclodextrins(CDs)are a common research object in supramolecular chemistry.The special cavity structure of CDs can form supramolecular self-assemblies such as vesicles and microcrystals through weak interaction with guest molecules.The different forms of supramolecular self-assemblies can be transformed into each other under certain conditions.The regulation of supramolecular self-assembly is not only helpful to understand the self-assembly principle,but also beneficial to its application.In the present study,the self-assembly behavior of epoxy-β-cyclodextrin(EP-β-CD)and mixed anionic and cationic surfactant system(sodium dodecyl sulfate/dodecyltrimethylammonium bromide,SDS/DTAB)in aqueous solution was studied.Morphological and particle size characterization found that the SDS/DTAB@EP-β-CD complex,as the basic building unit,self-assembled into worm-like micelles at lower temperatures and vesicles at higher temperatures.Nuclear magnetic resonance(NMR)and Fourier transform infrared spectroscopy(FT-IR)analysis revealed that the driving force for the formation of vesicles and worm-like micelles was the hydrogen bonds between EP-β-CD molecules,while water molecules played an important role in promoting vesicle formation between SDS/DTAB@EP-β-CD units.Herein,the mechanism of the morphologic transformation of SDS/DTAB@EP-β-CD supramolecular aggregates induced by temperature was elucidated by exploring the self-assembly process,which may provide an excellent basis for the development of delivery carriers. 展开更多
关键词 Epoxy-β-cyclodextrin SDS/DTAB SELF-ASSEMBLY TEMPERATURE morphological evolution
下载PDF
Mechanism of the Impact of Floods and Typhoons on the Morphological Evolution of the Yangtze Estuary
2
作者 JIAO Jian DING Lei +4 位作者 HAN Yu-fang SUN Jie-ying YANG Xiao-yu HUANG Yu-ming DOU Xi-ping 《China Ocean Engineering》 SCIE EI CSCD 2023年第3期447-457,共11页
In the last two decades,the Yangtze Estuary has undergone significant changes under the influence of reduced sediment inflow and estuary engineering.This study investigates the influence of floods and typhoons on sedi... In the last two decades,the Yangtze Estuary has undergone significant changes under the influence of reduced sediment inflow and estuary engineering.This study investigates the influence of floods and typhoons on sediment concentration and the morphological evolution of shoals and channels in the Yangtze Estuary.The analysis is conducted through the utilization of topographic data measured pre-and post-flood events and observations of hydro-sedimentary changes during typhoons.By using a generalized estuary mathematical model,this study examines the interplay between varying tidal ranges,tidal divisions,runoff volumes,and regulation projects on the erosion and deposition of shoals and channels in bifurcated estuaries.The results show that due to the implementation of river and waterway regulation projects,the impact of the 2020 flood on the main channel and shoal was significantly less than that of the1998 flood.The swing amplitude of the South Branch main channel decreased.However,local river sections such as the Southern Waterway of Baimao Shoal exhibited erosion.During typhoons,sediment concentration in the 20 cm above the bottom increased significantly and was closely related to wave processes,with a weakened correlation to tidal dynamics.After typhoons,high shoals in South Passage above 0 m were silted up,while the terrain on one side of the tail of Jiuduan Shoal in the downstream deep-water area was generally scoured due to strong wave action.The generalized mathematical model of the bifurcated estuary revealed that M2 tidal component contributed most to the ero sion and deposition evolution of estuary shoals and channels,with floods exhibiting characteristics of sedime ntation on shoals and erosion on channels.With the implementation of a branch rectification project,branch resistance increased,diversion decreased,and the riverbed changed from pre-project erosion to post-project sedimentation,with an increase in erosion in non-project branches. 展开更多
关键词 the Yangtze Estuary FLOOD TYPHOON morphological evolution
下载PDF
Impacts of human activities on morphological evolution in the Modaomen Estuary, China
3
作者 Tiehan Liao Haigang Zhan +1 位作者 Xing Wei Weikang Zhan 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2023年第5期79-92,共14页
The morphology of the Modaomen Estuary(ME)has undergone drastic changes in recent decades,and quantifying the contribution of human activities and natural processes is crucial for estuary management.Using Landsat imag... The morphology of the Modaomen Estuary(ME)has undergone drastic changes in recent decades,and quantifying the contribution of human activities and natural processes is crucial for estuary management.Using Landsat images,chart data,and hydrological and meteorological data,this study analyzed the evolution of the shoreline and subaqueous topography of the ME and attempted to quantify the extent of the contributions of human activities.The results show that local human activities dominated morphological evolution in some periods.From 1973 to 2003,the shoreline advanced rapidly seaward,resulting in approximately half of the water area being converted into land.Human activity is critical to this process,with the direct contribution of local land reclamation projects reaching more than 85%.After 2003,the shoreline remained relatively stable,probably due to a decrease in land reclamation projects.Regarding the evolution of subaqueous topography,the shoals in the estuary were heavily silted and gradually disappeared during 1983–2003,and the waterways narrowed and deepened.The average siltation rate decreased from 15.43 mm/a to-1.02 mm/a,indicating that the ME changed from sedimentation to slight erosion.By detecting variations of sediment load,we found that upstream human activities reduced river sediment,while downstream human activities significantly increased sediment input to the ME,leaving little change in the actual sediment input to the ME for a relatively long period.In addition,based on the empirical relationship between the sediment input and siltation rate,local human activities influenced the shift in the siltation state more than upstream and downstream human activities did.These findings suggest that more attention should be paid to local human activities to improve the estuarine management in the ME. 展开更多
关键词 Modaomen Estuary morphological evolution human activity quantitative analysis
下载PDF
Impact of the cord-grass Spartina alterniflora on sedimentary and morphological evolution of tidal salt marshes on the Jiangsu coast,China 被引量:15
4
作者 WANG Aijun GAO Shu JIA Jianjun 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2006年第4期32-42,共11页
The tidal flats of the Wanggang area, on the Jiangsu coast, represent the largest continuously distributed coastal wetland in terms of area coverage in China, and the dynamics of tidal flat accretion and erosion is hi... The tidal flats of the Wanggang area, on the Jiangsu coast, represent the largest continuously distributed coastal wetland in terms of area coverage in China, and the dynamics of tidal flat accretion and erosion is highly complicated. The cord-grass Spartina alterniflora, which was introduced artificially into the Jiangsu coast, has significant influences on the regional tidal flat evolution in terms of deposition rate, spacial sediment distribution patterns and tidal creek morphology. On the basis of the data set of bed elevation and accumulation rate for different periods of time, the applicability of the Pethick - Allen model to the Jiangsu tidal salt marshes is discussed. In addition, caesium-137 dating was carried out for sediment samples collected from the salt marsh of the Wangang area. In combination with the caesium-137 analysis and the data collected from literature, the Pethick - Allen model was used to derive the accumulation rate in the Wanggang tidal flat for the various periods. The results show that the pattern of tidal flat accretion has been modified, due to more rapid accretion following the iatroduction of S. alterniflora to the region. Surficial sediment samples were collected from representative profiles and analyzed for grain size with a laser particle analyzer. The result shows that fine-grained sediment has been trapped by the plant, with most of the sediment deposited on the Suaeda salsa and Spartina angelica flats being derived from drainage creeks rather than the from gently sloping tidal flats. Remote sensing analysis and in situ observations indicate that the creeks formed in the S. alterniflora flat have a relatively small ratio of width to depth, a relatively high density, and are more stable than the other tidal flat creek systems in the study area. 展开更多
关键词 Spartina alterniflora tidal flat SEDIMENTATION morphological evolution Jiangsu coast
下载PDF
Effects of the Anthropogenic Activities on the Morphological Evolution of the Modaomen Estuary, Pearl River Delta, China 被引量:3
5
作者 贾良文 潘顺琪 吴超羽 《China Ocean Engineering》 SCIE EI CSCD 2013年第6期795-808,共14页
Owing to the intensive human activities, the Modaomen Estuary has been significantly modified since 1950s, which has resulted in considerable changes of hydrodynamics and morphodynamics in the area. In this paper, the... Owing to the intensive human activities, the Modaomen Estuary has been significantly modified since 1950s, which has resulted in considerable changes of hydrodynamics and morphodynamics in the area. In this paper, the effects of the anthropogenic activities on the hydrodynamics and morphological evolution in the estuary at different stages are systematically assessed based on the detailed bathymetric data and field survey. The results show that the human activities have caused the channelization of the enclosed sea area in the Modamen Estuary;fast seaward movement of the mouth bar with high siltation;expansion of the channel volume due to channel deepening. The paper also highlights the main hydrodynamic changes in the estuary, including the rise of the water level;the distinguishing changes of tidal range before and after the 1990s (decrease and increase respectively); as well as the increase of the divided flow ratio. It is found that reclamation is the main factor promoting the transition of nature of the estuary from runoff dominant to runoff and wave dominant, and sand mining activities are mainly to strengthen the tidal dynamic and to low the water level. The results provide useful guidance for better planning of the future developments in the estuary and further research in the area. 展开更多
关键词 Modaomen Estuary anthropogenic activities morphological evolution RECLAMATION sand mining
下载PDF
Unraveling the morphological evolution mechanism of solid sulfur species in lithium-sulfur batteries with operando light microscopy 被引量:1
6
作者 Jingqiang Zheng Chaohong Guan +7 位作者 Huangxu Li Yangyang Xie Junxian Hu Kai Zhang Bo Hong Yanqing Lai Jie Li Zhian Zhang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2022年第10期460-468,I0012,共10页
Solid-liquid phase conversion between various sulfur species in lithium-sulfur(Li-S)batteries is a fundamental reaction of the sulfur cathode.Disclosing the morphological evolution of solid sulfur species upon cycling... Solid-liquid phase conversion between various sulfur species in lithium-sulfur(Li-S)batteries is a fundamental reaction of the sulfur cathode.Disclosing the morphological evolution of solid sulfur species upon cycling is of great significance to achieving high energy densities.However,an in-depth investigation of the internal reaction is still lacking.In this work,the evolution process of solid sulfur species on carbon substrates is systematically studied by using an operando light microscope combined with in situ electrochemical impedance spectra technology.The observation of phenomena such as bulk solid sulfur species can form and dissolve independently of the conductive substrates and the transformation of supercooled liquid sulfur to crystalline sulfur.Based on the phenomena mentioned above,a possible mechanism was proposed in which the dissolution reaction of solid sulfur species is a spatially free reaction that involves isotropic physical dissolution,diffusion of molecules,and finally the electrochemical reaction.Correspondingly,the formation of solid sulfur species tends to be a form of crystallization in a saturated solution rather than electrodeposition,as is commonly believed.Our findings offer new insights into the reaction of sulfur cathodes and provide new opportunities to design advanced sulfur cathodes for Li-S batteries. 展开更多
关键词 Lithium-sulfur batteries morphological evolution Supercooled liquid sulfur Operando light microscopy Liquid sulfur droplets
下载PDF
Morphological evolution of a large sand bar in the Qiantang River Estuary of China since the 1960s
7
作者 Junbao Huang Zhilin Sun Dongfeng Xie 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2022年第2期156-165,共10页
A large sand bar develops in the inner Qiantang River Estuary,China.It is a unique sedimentary system,elongating landwards by about 130 km.Based on long-term series of bathymetric data in each April,July,and November ... A large sand bar develops in the inner Qiantang River Estuary,China.It is a unique sedimentary system,elongating landwards by about 130 km.Based on long-term series of bathymetric data in each April,July,and November since the 1960s,this study investigated the morphological behavior of this bar under natural conditions and the influence of a large-scale river narrowing project(LRNP)implemented in the last decades.The results show that three timescales,namely the seasonal,interannual and decadal timescales,can be distinguished for the sand bar evolution.The first two are related to the seasonal and interannual variations of river discharge.During high discharge seasons or years,erosion took place at the upper reach and sedimentation at the lower reach.Consequently,the bar apex shifted seaward.The opposite development took place during low discharge seasons or years.The decadal timescale is related to LRNP.Due to the implementation of LRNP,the upper reach has experienced apparent erosion and currently a new equilibrium state has been reached;whereas the lower reach has been accumulated seriously and the accumulation still continues.Nonlinear relationships for how the bar apex location and elevation depend on the river discharge over various stages of LRNP have been established.Compared with the earlier stage of LRNP,the bar apex at present has shifted seaward by about 12 km and lowered by about 1 m.The sand bar movement has significant feedback on the hydrographic conditions along the estuary and has practical implications for coastal management. 展开更多
关键词 morphological evolution river discharge sand bar Qiantang River Estuary river narrowing project coastal management
下载PDF
MORPHOLOGICAL EVOLUTION DURING DIFFUSIVE HEALING OF INTERNAL CRACKS WITHIN GRAINS OF α-IRON
8
作者 张海龙 孙军 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2002年第5期516-527,共12页
Micron-sized internal cracks were introduced into rounded bars of pure iron by low cycle fatigue,and the cracks had irregular penny-shaped morphology with the critical diameter of about 30μm and the thickness of 0.5... Micron-sized internal cracks were introduced into rounded bars of pure iron by low cycle fatigue,and the cracks had irregular penny-shaped morphology with the critical diameter of about 30μm and the thickness of 0.5~1.5μm.The initi- ation and propagation of the cracks were investigated quantitatively as well as their location and geometry.After vacuum annealing of the samples fatigued,the mor- phology in a two-dimensional longitudinal section of cracks within grains had evolved from initially elliptical one into arrays of spherical voids controlled by surface diffu- sion.Furthermore,a typical morphology for a broken crack with a center spherical void surrounded by outer doughnut-like cavities was observed along a perpendicu- lar section of the specimen.Subsequently the spherical voids shrink and diminish gradually dominated by bulk diffusion.A physical model to heal an internal micro- crack was proposed,in particular for the various healing stages controlled by the related dominant diffusion mechanism and their dependencies upon the morphology and geometry of an original micro-crack in materials. 展开更多
关键词 fatigue micro-crack morphological evolution VOID DIFFUSION
下载PDF
Morphological Evolution of Nb_2O_5 in a Solvothermal Reaction: From Nb_2O_5 Grains to Nb_2O_5 Nanorods and Hexagonal Nb_2O_5 Nanoplatelets
9
作者 胡卫兵 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2009年第2期245-248,共4页
Novel Nb2O5 nanorods and polygonal Nb2O5 platelets were generated by a simple solvothermal technique. The geometry evolution of the resultant Nb2O5 from amorphous nanoparticles to crystallized particles, from polygona... Novel Nb2O5 nanorods and polygonal Nb2O5 platelets were generated by a simple solvothermal technique. The geometry evolution of the resultant Nb2O5 from amorphous nanoparticles to crystallized particles, from polygonal platelets to well-elongated nanorods was been studied in detail. The processing parameters, including the reaction temperature, reaction time, concentration of the precursors, and pH value of the solution, which affect the shape and size of the nanorods, were investigated. The Nb2O5 nanorods with different aspect ratios were examined by XRD, SEM and TEM. The experimental results show that Nb2O5 nanorod is the orthorhombic structure and well-crystallized. The growth of the nanorods follows their [001] direction. The successful generation of high quality Nb2O5 nanorods is not only important for transition metal oxide research, but also potentially important for further formation of new Nb-based 1-D nanostructures, such as NbS2 and NbN. 展开更多
关键词 SOLVOTHERMAL morphological evolution Nb2O5 nanomateraials
下载PDF
Morphological Evolution and Dynamic Mechanism of Hubei Village during 1949-2021
10
作者 FU Lianlin 《Journal of Landscape Research》 2021年第4期14-18,共5页
Since the reform and opening up,Shenzhen has experienced rapid urbanization.Modern urban landscape has replaced the original traditional village landscape,followed by the loss of urban features and the demise of tradi... Since the reform and opening up,Shenzhen has experienced rapid urbanization.Modern urban landscape has replaced the original traditional village landscape,followed by the loss of urban features and the demise of traditional villages.To change the phenomenon,with the help of town plan analysis method,the historical process of urban material form is looked back on.Combining the theory of evolution mechanism of urban spatial structure,and taking Hubei Village which is the only traditional village in the central district of Shenzhen as an example,the characteristics and causes of evolution of traditional villages in Shenzhen in different periods are analyzed,and the evolution characteristics of plane pattern are summarized.Moreover,the power source and characteristics of urban renewal in Shenzhen are pointed out from the perspective of government,market and social force,and the focus of promoting the renewal of traditional villages in the future is explored. 展开更多
关键词 morphological evolution Dynamic mechanism Hubei Village Traditional village
下载PDF
Alkaline zinc-based flow battery: chemical stability, morphological evolution, and performance of zinc electrode with ionic liquid
11
作者 Tianyong Mao Jing Dai +2 位作者 Meiqing Xin Deliang Zeng Zhipeng Xie 《Frontiers of Materials Science》 SCIE CSCD 2024年第1期113-121,共9页
Zinc-based flow battery is an energy storage technology with good application prospects because of its advantages of abundant raw materials,low cost,and environmental friendliness.The chemical stability of zinc electr... Zinc-based flow battery is an energy storage technology with good application prospects because of its advantages of abundant raw materials,low cost,and environmental friendliness.The chemical stability of zinc electrodes exposed to electrolyte is a very important issue for zinc-based batteries.This paper reports on details of chemical stability of the zinc metal exposed to a series of solutions,as well as the relationship between the morphological evolution of zinc electrodes and their properties in an alkaline medium.Chemical corrosion of zinc electrodes by the electrolyte will change their surface morphology.However,we observed that chemical corrosion is not the main contributor to the evolution of zinc electrode surface morphology,but the main contributor is the Zn/Zn^(2+)electrode process.The morphological evolution of zinc electrodes was controlled by using ionic liquids,1-ethyl-3-methylimidazolium acetate(EMIA),and 1-propylsulfonic-3-methylimidazolium tosylate(PSMIT),and the electrode performance was recorded during the morphological evolution process.It was observed that the reversible change of zinc electrode morphology was accompanied by better electrode performance. 展开更多
关键词 alkaline medium morphological evolution zinc-based flow battery new energy
原文传递
Evaporation Characteristics and Morphological Evolutions of Fuel Droplets After Hitting Different Wettability Surfaces 被引量:1
12
作者 Yanling Chen Liang Guo +5 位作者 Ningning Cai Wanchen Sun Yuying Yan Degang Li Han Wang Rong Xuan 《Journal of Bionic Engineering》 SCIE EI CSCD 2023年第2期734-747,共14页
To solve the wall-wetting problem in internal combustion engines,the physical and chemical etching methods are used to prepare different wettability surfaces with various microstructures.The evaporation characteristic... To solve the wall-wetting problem in internal combustion engines,the physical and chemical etching methods are used to prepare different wettability surfaces with various microstructures.The evaporation characteristics and morphological evolution processes of diesel and n-butanol droplets after hitting the various surfaces are investigated.The results show that the surface microstructures increase the surface roughness(Ra),enhancing the oleophilic property of the oleophilic surfaces.Compared with n-butanol droplets,the same surface shows stronger oleophobicity to diesel droplets.When a droplet hits an oleophilic property surface with a lower temperature,the stronger the oleophilicity,the shorter the evaporation time.For oleophilic surfaces,larger Ra leads to a higher Leidenfrost temperature(TLeid).The low TLeid caused by enhanced oleophobicity,dense microstructures and increased convex dome height facilitates droplet rebound and promotes the evaporation of the wall-impinging droplets into the cylinder.The evaporation rate of the droplets is not only related to the characteristics of the solid surfaces and the fuel droplets but also affected by the heat transfer rate to the droplets in different boiling regimes.The spreading diameter of a droplet on an oleophobic surface varies significantly less with time than that on an oleophilic surface under the same surface temperature. 展开更多
关键词 Fuel droplets WETTABILITY Evaporation time Leidenfrost temperature morphological evolutions
原文传递
Interacting effects of multiple factors on the morphological evolution of the meandering reaches downstream the Three Gorges Dam 被引量:3
13
作者 HAN Jianqiao ZHANG Wei +1 位作者 FAN Yongyang YU Mengqing 《Journal of Geographical Sciences》 SCIE CSCD 2017年第10期1268-1278,共11页
Elucidating the influence of dams on fluvial processes can inform river protection and basin management. However, relatively few studies have focused on how multiple factors interact to affect the morphological evolut... Elucidating the influence of dams on fluvial processes can inform river protection and basin management. However, relatively few studies have focused on how multiple factors interact to affect the morphological evolution of meandering reaches. Using hydrological and topographical data, we analyzed the factors that influence and regulate the meandering reaches downstream the Three Gorges Dam (TGD). Our conclusions are as follows. (1) The meandering reaches can be classified into two types based on their evolution during the pre-dam period: G1 reaches, characterized by convex point bar erosion and concave channel deposition (CECD), and G2 reaches, characterized by convex point bar deposition and concave channel erosion (CDCE). Both reach types exhibited CECD features during the post-dam period, (2) Flow processes and sediment transport are the factors that caused serious erosion of the low beaches located in the convex point bars. However, changes in the river regime, river boundaries and jacking of Dongting Lake do not act as primary controls on the morphological evolution of the meandering reaches. (3) Flood discharges ranging from 20,000 to 25,000 m^3/s result in greater erosion of convex point bars. The point bars become scoured if the durations of these flows, which are close to bankfull discharge, exceed 20 days. In addition, the reduction in bedload causes the decreasing of point bar siltation in the water-falling period. (4) During the post-dam period, flood abatement, the increased duration of discharges ranging from 20,000 to 25,000 m^3/s, and a significant reduction in sediment transport are the main factors that caused meandering reaches to show CECD features. Our results are relevant to other meandering reaches, where they can inform estimates of riverbed change, river management strategies and river protection. 展开更多
关键词 reaches downstream dams meandering river morphological evolution Three Gorges Dam
原文传递
Morphological evolution of the channel-shoal system in the South Channel of the Changjiang Estuary during 1958–2018:Causes and future trends
14
作者 LUAN Hualong YAO Shiming +1 位作者 QU Geng LEI Wentao 《Journal of Geographical Sciences》 SCIE CSCD 2022年第11期2291-2310,共20页
The stability of estuarine channel-shoal systems is important for port utilization,navigation maintenance,habitat protection and ecosystem service functions.This paper uses the South Channel of the Changjiang(Yangtze ... The stability of estuarine channel-shoal systems is important for port utilization,navigation maintenance,habitat protection and ecosystem service functions.This paper uses the South Channel of the Changjiang(Yangtze River)Estuary as a typical example to investigate the channel-shoal adjustment mechanism and its future trend.The combined approaches of bathymetric data analysis and process-based modeling(Delft3D)are applied.Quantitative analysis of morphological changes indicates that the South Channel experienced remarkable channel-shoal adjustment during 1958–2018.Periodic evolution was identified,including shoal migration,incision and emergence under natural conditions before the mid-1980s.Since then,fluvial sediment decline and local human intervention have interrupted the periodic processes.After 1986,as river sediment discharge started to decline,the South Channel converted to net erosion,and both the mid-channel shoal at the bifurcation node and the tail of the Ruifeng Shoal showed significant scour.Process-based hydrodynamic simulations revealed that the northern rotation of the mainstream downstream of Wusong triggered the erosion of the Ruifeng Shoal,while unordered sand mining at the shoal tail in approximately 2002 enhanced shoal shrinkage.In addition,the self-adjustment of the transverse section shape resulted in abnormal accretion in 2002–2007.Afterward,the South Channel underwent overall erosion as sediment discharge decreased to a low level(<150 Mt/a).Five stages of channel-shoal pattern adjustment and accretion/erosion status during the past 60years were defined,i.e.,the accretion stage(1958–1965),remarkable channel-shoal adjustment stage(1978–1986),slow erosion stage(1986–1997),shoal scour and shrinkage stage(1997–2007)and overall channel-shoal erosion stage(2007–2018).Model prediction of the evolutionary trend indicates that overall erosion within the South Channel is most likely to continue in 2015–2050.Further adjustment of the South Channel under extremely low sediment discharge may threaten the riverbed stability and the sustainable development of this large-scale estuary.Future work on adaptive strategies for varying conditions is recommended. 展开更多
关键词 channel-shoal pattern morphological evolution process-based modeling South Channel Changjiang Estuary
原文传递
Analytical solution to one-dimensional mathematical model of flow and morphological evolution in open channels
15
作者 DING Yun LI ZuiSen +1 位作者 SHI YongZhong ZHONG DeYu 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2020年第12期2606-2616,共11页
The evolution of open-channel flow and morphology can be simulated by one-dimensional(1D) mathematical models. These models are typically solved by numerical or analytical methods. Because the behavior of variables ca... The evolution of open-channel flow and morphology can be simulated by one-dimensional(1D) mathematical models. These models are typically solved by numerical or analytical methods. Because the behavior of variables can be explained by explicit mathematical determinations,compared to numerical solutions,analytical solutions provide fundamental and physical insights into flow and sediment transport mechanisms. The singular perturbation technique derives a hierarchical equation of waves and describes the evolutionary nature of disturbances in hyperbolic systems. The wave hierarchy consists of dynamic,diffusion,and kinetic waves. These three types of waves interact with each other in the process of propagation. Moreover,the Laplace transform is implemented to transform partial differential equations into ordinary differential equations. Analytical expressions in the wave front are subtracted by the approximation of kinetic and diffusion models. Moreover,an analytical solution consists of a linear combination of the kinetic wave front and the diffusion wave front expressions,pursuing to describe the physical mechanism of motion in open channels as completely as possible. Analytical solutions are presented as a combination of exponential functions,hyperbolic functions,and infinite series. The obtained analytical solution was further applied to the simulation of flood path and morphological evolution in the Lower Yellow River. The phenomenon of increased peak discharge in the downstream reach was successfully simulated. It was encouraging that the results were in good agreement with the observed data. 展开更多
关键词 open channel mathematical model analytical solution Laplace transform morphological evolution
原文传递
Sediment source-to-sink process variations of sandy-muddy transitional beaches and their morphological indications
16
作者 Shaohua Zhao Feng Cai +4 位作者 Hongshuai Qi Jianhui Liu Chao Cao Gen Liu Gang Lei 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2023年第7期10-24,共15页
The clay mineralogy of 28 sandy-muddy transitional beach(SMT-Beach)sediments and surrounding mountain river sediments along the coasts of southeastern China was systematically investigated to reveal the sediment sourc... The clay mineralogy of 28 sandy-muddy transitional beach(SMT-Beach)sediments and surrounding mountain river sediments along the coasts of southeastern China was systematically investigated to reveal the sediment source-to-sink process variations of such beaches and their morphological indications.The results show that the clay mineral assemblages of these SMT-Beaches mainly comprise of almost equal illite(~30%),kaolinite(~28%),chlorite(~22%),and smectite(~20%)contents.From the surrounding mountain rivers to the SMT-Beaches,clay mineral assemblages show distinct spatial changes characterized by a large decrease(~40%)in kaolinite,whereas the other three clay minerals present relative increases,especially clear for smectite.The muddy sediment sources of SMT-Beaches inferred from the clay mineralogy are mainly derived from nearby mountain rivers coupled with long-distance transport and penetration of the Changjiang River.The sandy sediments of these beaches are predominantly sourced from nearby mountain rivers,the weathering products of surrounding rocks in both mainland and island environments,and erosion of the“Old Red Sand”and“Red Soil Platform”.However,the sandy sediment sources of the SMT-Beaches are largely reduced because of the remarkable decrease in the river fluvial supply associated with intensive human activities such as dam construction and coastal reclamation.Subsequently,the sandy sections of SMT-Beaches present clear erosion and have revealed by both time series remote sensing images and a compilation of published literature.In contrast,the muddy sediment supply of SMT-Beaches is temporarily stable and relatively constant,resulting in the landward migration of the mudflats with relative transgression or accumulation.These findings highlight that the natural evolution processes of SMT-Beaches have been greatly reshaped by intensive human activities. 展开更多
关键词 sandy-muddy transitional beach clay mineral sediment source human activity fluvial discharge morphological evolution
下载PDF
Morphological and Microstructural Evolution and Related Impurity Incorporation in Non-Polar a-Plane GaN Grown on r-Sapphire Substrates
17
作者 蒋仁渊 许晟瑞 +5 位作者 张进成 姜腾 江海清 王之哲 樊永祥 郝跃 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第9期154-157,共4页
Effects of the growth temperature on morphological and microstructural evolution of a-plane GaN films grown on r-plane sapphires by metal organic chemical vapor deposition are investigated by atomic force microscopy a... Effects of the growth temperature on morphological and microstructural evolution of a-plane GaN films grown on r-plane sapphires by metal organic chemical vapor deposition are investigated by atomic force microscopy and secondary ion mass spectroscopy (SIMS). Surface morphology, structural quality and related impurity incorpora- tion are very sensitive to the growth temperature. A significant difference of yellow luminescence is observed and attributed to the incorporation of carbon into GaN films, which is confirmed by SIMS analysis. Our results show that the sample with triangular-pit morphology has sample with pentagon-like pit morphology, which is significantly higher concentrations of oxygen than the other induced by the existence of an N-face in triangular pits. 展开更多
关键词 GAN morphological and Microstructural evolution and Related Impurity Incorporation in Non-Polar a-Plane GaN Grown on r-Sapphire Substrates
下载PDF
Feedback between tidal hydrodynamics and morphological changes induced by natural process and human interventions in a wave-dominated tidal inlet: Xiaohai, Hainan, China 被引量:2
18
作者 GONG Wenping SHEN Jian JIA Jianjun 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2009年第3期93-113,共21页
The feedback between morphological evolution and tidal hydrodynamics in a wave-dominated tidal inlet, Xiaohai, China is investigated through data analysis and numerical model experiments. Historically, Xiaohai Inlet h... The feedback between morphological evolution and tidal hydrodynamics in a wave-dominated tidal inlet, Xiaohai, China is investigated through data analysis and numerical model experiments. Historically, Xiaohai Inlet had two openings, located at the north and south of Neizhi Island (a rocky outcrop), respectively. The evolution of Xiaohai Inlet was dominated by the natural process before 1972. In addition to the natural process, human interventions, including the closure of the north opening, 50% of freshwater reduction, and increase of land reclamation, have altered tidal hydrodynamics and morphological evolution since 1972. A series of numerical model simulations were conducted to investigate the influence of morphological changes on the hydrodynamics and the influence of human activities on the inlet evolution. The natural process has caused narrowing and shoaling of the inlet throat, development of the flood-tidal delta, and shoaling of the tidal channel inside the lagoon. Human interventions have accelerated these changes. Consequently, the tidal propagation from the offshore into the lagoon has been impeded and the tidal energy has been dissipated substantially. Tidal current has changed from ebb-dominant to flood-dominant in most parts of the inlet system whereas the inlet throat has remained as ebb-dominant, the tidal prism has decreased consistently, and sediment has continued to deposit inside the inlet. As a result, the changes of morphology, hydrodynamics, and sediment transport show a positive feedback. The human interventions have had both advantageous and adverse influences on the stability of the inlet. The closure of the North Opening has decreased the longshore sediment input to the inlet, and increased the tidal prism, ebb velocity, and sediment transport in the south opening, thus enhancing the inlet's stability. However, reducing the river discharge and landfill of the tidal flats has resulted in a decrease of the tidal prism, the ebb velocity, and the ability to export sediment, thus having the tendency to deteriorate the inlet's stability. A stability analysis based on a closure curve methodology has shown that Xiaohai Inlet is in a state of dynamic equilibrium at present. 展开更多
关键词 morphological evolution tidal hydrodynamics ELCIRC HAINAN China
下载PDF
Analysis of Evolution Features of Villages into Small Towns under the Influence of Tourism:A Case Study of Xizhou Town of Dali City
19
作者 WANG Yinyin BI Yanxia +1 位作者 ZHANG Youcai CHE Zhenyu 《Journal of Landscape Research》 2017年第1期25-29,36,共6页
Influence of tourism on society,economy and culture of traditional villages is shown gradually by physical form,promoting the evolution of villages into small towns. Based on the perspective of morphology,the changing... Influence of tourism on society,economy and culture of traditional villages is shown gradually by physical form,promoting the evolution of villages into small towns. Based on the perspective of morphology,the changing features of physical and social spatial form of three typical regions(Xizhou Village and its surrounding areas,Zhoucheng Village and its surrounding areas,and Renliyi Village) in Xizhou Town of Dali City during 1985-2010 were analyzed; the roles of tourism during the evolution process of villages into small towns were discussed; the evolution features of villages into small towns were summarized. It is concluded that tourism and economy related to tourism have played important roles in the enhancement of cohesion degree of an aggregation nucleus and have promoted the evolution process of vilages into small towns. 展开更多
关键词 Vilages morphological evolution Influence of tourism Tourism urbanization Xizhou Town of Dali City
下载PDF
Growth morphology and evolution of quasicrystal in as-solidified Y-rich Mg-Zn-Y ternary alloys 被引量:4
20
作者 WAN Diqing YANG Gencang CHEN Sulin ZHU Man ZHOU Yaohe 《Rare Metals》 SCIE EI CAS CSCD 2007年第5期435-439,共5页
A petal-like icosahedral quasicrystal with five branches,which is considered to be the representative morphology of the icosahedral quasicrystal,has been observed in the Y-rich Mg-Zn-Y ternary alloys. Moreover,the pol... A petal-like icosahedral quasicrystal with five branches,which is considered to be the representative morphology of the icosahedral quasicrystal,has been observed in the Y-rich Mg-Zn-Y ternary alloys. Moreover,the polygon-like morphology,another pattern of the icosahedral quasicrystal,has also been found in the Y-rich Mg-Zn-Y ternary alloys. The latter morphology results from the evolution of the former one. The growth mechanism of the petal-like morphology of the icosahedral quasicrystal was also discussed. Alloying composition,i.e.,Y element content,is a major factor inducing the morphology evolution of the icosahedral quasicrystal. 展开更多
关键词 Mg-Zn-Y ternary alloys icosahedral quasicrystal morphology evolution Y element
下载PDF
上一页 1 2 3 下一页 到第
使用帮助 返回顶部