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Spatiotemporal landscape pattern changes and their effects on land surface temperature in greenbelt with semi-arid climate:A case study of the Erbil City,Iraq
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作者 Suzan ISMAIL Hamid MALIKI 《Journal of Arid Land》 SCIE CSCD 2024年第9期1214-1231,共18页
Urban expansion of cities has caused changes in land use and land cover(LULC)in addition to transformations in the spatial characteristics of landscape structure.These alterations have generated heat islands and rise ... Urban expansion of cities has caused changes in land use and land cover(LULC)in addition to transformations in the spatial characteristics of landscape structure.These alterations have generated heat islands and rise of land surface temperature(LST),which consequently have caused a variety of environmental issues and threated the sustainable development of urban areas.Greenbelts are employed as an urban planning containment policy to regulate urban expansion,safeguard natural open spaces,and serve adaptation and mitigation functions.And they are regarded as a powerful measure for enhancing urban environmental sustainability.Despite the fact that,the relation between landscape structure change and variation of LST has been examined thoroughly in many studies,but there is a limitation concerning this relation in semi-arid climate and in greenbelts as well,with the lacking of comprehensive research combing both aspects.Accordingly,this study investigated the spatiotemporal changes of landscape pattern of LULC and their relationship with variation of LST within an inner greenbelt in the semi-arid Erbil City of northern Iraq.The study utilized remote sensing data to retrieve LST,classified LULC,and calculated landscape metrics for analyzing spatial changes during the study period.The results indicated that both composition and configuration of LULC had an impact on the variation of LST in the study area.The Pearson's correlation showed the significant effect of Vegetation 1 type(VH),cultivated land(CU),and bare soil(BS)on LST,as increase of LST was related to the decrease of VH and the increases of CU and BS,while,neither Vegetation 2 type(VL)nor built-up(BU)had any effects.Additionally,the spatial distribution of LULC also exhibited significant effects on LST,as LST was strongly correlated with landscape indices for VH,CU,and BS.However,for BU,only aggregation index metric affected LST,while none of VL metrics had a relation.The study provides insights for landscape planners and policymakers to not only develop more green spaces in greenbelt but also optimize the spatial landscape patterns to reduce the influence of LST on the urban environment,and further promote sustainable development and enhance well-being in the cities with semi-arid climate. 展开更多
关键词 land use and land cover change landscape pattern land surface temperature GREENBELT remote sensing
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Surface Patterning of Metal Zinc Electrode with an In‑Region Zincophilic Interface for High‑Rate and Long‑Cycle‑Life Zinc Metal Anode 被引量:1
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作者 Tian Wang Qiao Xi +8 位作者 Kai Yao Yuhang Liu Hao Fu Venkata Siva Kavarthapu Jun Kyu Lee Shaocong Tang Dina Fattakhova‑Rohlfing Wei Ai Jae Su Yu 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第6期192-209,共18页
The undesirable dendrite growth induced by non-planar zinc(Zn)deposition and low Coulombic efficiency resulting from severe side reactions have been long-standing challenges for metallic Zn anodes and substantially im... The undesirable dendrite growth induced by non-planar zinc(Zn)deposition and low Coulombic efficiency resulting from severe side reactions have been long-standing challenges for metallic Zn anodes and substantially impede the practical application of rechargeable aqueous Zn metal batteries(ZMBs).Herein,we present a strategy for achieving a high-rate and long-cycle-life Zn metal anode by patterning Zn foil surfaces and endowing a Zn-Indium(Zn-In)interface in the microchannels.The accumulation of electrons in the microchannel and the zincophilicity of the Zn-In interface promote preferential heteroepitaxial Zn deposition in the microchannel region and enhance the tolerance of the electrode at high current densities.Meanwhile,electron aggregation accelerates the dissolution of non-(002)plane Zn atoms on the array surface,thereby directing the subsequent homoepitaxial Zn deposition on the array surface.Consequently,the planar dendrite-free Zn deposition and long-term cycling stability are achieved(5,050 h at 10.0 mA cm^(−2) and 27,000 cycles at 20.0 mA cm^(−2)).Furthermore,a Zn/I_(2) full cell assembled by pairing with such an anode can maintain good stability for 3,500 cycles at 5.0 C,demonstrating the application potential of the as-prepared ZnIn anode for high-performance aqueous ZMBs. 展开更多
关键词 Zn metal anode surface patterning Directional Zn deposition Aqueous Zn-I_(2)batteries
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Color as Material: Ceramic Surfaces in the Work of Gio Ponti in Milan (1927-1970)
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作者 Sara Di Resta 《Journal of Civil Engineering and Architecture》 2023年第11期564-573,共10页
The study is based on the analysis of the design and operational path conducted by the architect Gio Ponti on ceramic materials between the late 1920s and the early 1970s,with particular attention to applications in t... The study is based on the analysis of the design and operational path conducted by the architect Gio Ponti on ceramic materials between the late 1920s and the early 1970s,with particular attention to applications in the Milanese context.Milan represents the main laboratory for experimenting with the figurative,plastic and chromatic potential of modern ceramic surfaces.The analysis of archival documentation preserved at the CSAC Archive in Parma,the Gio Ponti Archives in Milan and the Archivio Progetti at the Iuav University of Venice allows for a deeper understanding of the design path at different scales,from the design of specific lines of ceramics for industry,to their application in buildings.The second part of the analysis is aimed at tracing the conservation problems of ceramic surfaces,with the aim of highlighting both the cultural and technical aspects that are affecting the conservation of this heritage.Connected to the latter aspect is a focus on the principal deterioration phenomena of modern ceramic surfaces related to different types of substrates,providing in-depth knowledge that opens up new strategies for their conservation. 展开更多
关键词 Ceramic surfaces modern architecture Gio Ponti MILAN deterioration patterns
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An overview of the spatial patterns of land surface processes over arid and semiarid regions 被引量:6
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作者 Jian Zeng Jie Shen Qiang Zhang 《Research in Cold and Arid Regions》 2010年第4期288-297,共10页
With data from the project Collaborative Observation of Semi-arid/Arid Regions in North China, collected during July and September 2008, the spatial patterns of land surface processes over arid and semiarid regions ha... With data from the project Collaborative Observation of Semi-arid/Arid Regions in North China, collected during July and September 2008, the spatial patterns of land surface processes over arid and semiarid regions have been investigated based on the ordinary Kriging interpolation approach. Generally, for the radiation processes, downward and upward short-wave radiation have a uniformly increasing trend with latitude, but the spatial patterns of long-wave radiation present notable regional differences: both upward and downward long-wave radiation increase with latitude in the west of North China, while in the east they vary inversely with latitude, suggesting surface temperature and clouds respectively have feedbacks to the long-wave radiation in the west and east of North China. The surface net radiation basically has a negative latitudinal trend. Long-wave radiation budget plays an important role in the spatial pattern of surface net radiation, particularly in the east of North China, although short-wave radiation budget largely determines the magnitude of surface net radiation. For the energy processes, latent and sensible heat flux varies conversely with latitude: more available land surface energy is consumed by evaporating soil water at lower latitudes while more is used for heating the atmosphere at higher latitudes. A soil heat flux maximum and minimum are found in Loess Plateau and Qinghai Plateau respectively, and a maximum is seen in the northeast China. 展开更多
关键词 land surface radiation processes land surface energy processes spatial pattern arid and semiarid regions
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Surface circulation patterns observed by drifters in the Yellow Sea in summer of 2001,2002 and 2003 被引量:6
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作者 庞重光 梁兼霞 +4 位作者 胡敦欣 王凡 陈永利 白虹 白学志 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2004年第3期209-216,共8页
In summer of 2001, 2002 and 2003, ten, six and seventeen satellite-tracked surface drifters with drogues centered at 15 and 4 m were deployed, respectively, in the southern Yellow Sea (YS). 23 drifters of them transmi... In summer of 2001, 2002 and 2003, ten, six and seventeen satellite-tracked surface drifters with drogues centered at 15 and 4 m were deployed, respectively, in the southern Yellow Sea (YS). 23 drifters of them transmitted useful data of at least 30 days. The wind-driven component of the drift was removed from the original drift velocity of drifters. The wind data used are from NCEP (National Center for Environmental Prediction), USA.Trajectories and drift velocities of the 23 drifters depicted the upper circulation structure in the southern YS.There exists an anti-cyclonic eddy with a mean speed and radius of 0.063 m/s and 50km in the central southern YS, whose center lingered within 35.3-36.0°N / 123.5-124.0°E. Showed by 6 drifters, a basin-scale elliptic cyclonic gyre with a mean speed of 0.114 m/s, long and short radius of 250 and 200 km surrounds the anti-cyclonic eddy. In the southwestern part of the southern YS has obvious frontal eddy activities within about100 km with a mean speed about 0.076 m/s. All the drifters passing Korean coast were staggering for more than10 days west of a protruding cape of central Korea. A small-scale cyclonic eddy centered at around 120.5°E/35.1°N with a mean speed of 0.048 m/s was observed in western part of the southern YS. 展开更多
关键词 satellite-tracked drifter trajectories drift velocity surface circulation pattern the Yellow Sea
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Relationships between the surface quality of a single crystal copper ingot and the process parameters of a heated mould continuous casting method 被引量:1
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作者 G.J.Xu Z.F.Ding +3 位作者 Y.T.Ding S.H.Kou G.L.Liu C.L.Feng 《China Foundry》 SCIE CAS 2004年第S1期62-66,共5页
The relationships between the surface quality of a single crystal copper ingot and the process parameters of heated mould continuous casting method were studied experimentally using our own design of horizontal heated... The relationships between the surface quality of a single crystal copper ingot and the process parameters of heated mould continuous casting method were studied experimentally using our own design of horizontal heated mould continuous casting apparatus, and the mechanism by which process parameters affect the surface quality of a single crystal copper ingot is analyzed in the present paper. The results show that the process parameters affect the surface quality of a pure copper ingot by affecting the position of the liquid-solid interface in the mould. The position of the liquid-solid interface in the mould must be controlled carefully within an appropriate range, which is determined through a series of experiments, in order to gain a single crystal copper ingot with good surface quality. 展开更多
关键词 heated mould continuous casting single crystal copper surface quality process parameter
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Numerical Investigation of Laser Surface Hardening of AISI 4340 Using 3D FEM Model for Thermal Analysis of Different Laser Scanning Patterns
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作者 Baha Tarchoun Abderrazak El Ouafi Ahmed Chebak 《Modeling and Numerical Simulation of Material Science》 2020年第3期31-54,共24页
<span style="font-family:Verdana;">Laser surface hardening is becoming one of the most successful heat treatment processes for improving wear and fatigue properties of steel parts. In this process, the... <span style="font-family:Verdana;">Laser surface hardening is becoming one of the most successful heat treatment processes for improving wear and fatigue properties of steel parts. In this process, the heating system parameters and the material properties have important effects on the achieved hardened surface characteristics. The control of these variables using predictive modeling strategies leads to the desired surface properties without following the fastidious trial and error method. However, when the dimensions of the surface to be treated are larger than the cross section of the laser beam, various laser scanning patterns can be used. Due to their effects on the hardened surface properties, the attributes of the selected scanning patterns become significant variables in the process. This paper presents numerical and experimental investigations of four scanning patterns for laser surface hardening of AISI 4340 steel. The investigations are based on exhaustive modelling and simulation efforts carried out using a 3D finite element thermal analysis and structured experimental study according to Taguchi method. The temperature distribution and the hardness profile attributes are used to evaluate the effects of heating parameters and patterns design parameters on the hardened surface characteristics. This is very useful for integrating the scanning patterns</span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">’</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> features in an efficient predictive modeling approach. A structured experimental design combined to improved statistical analysis tools </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> used</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> to</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> assess the 3D model performance. The experiments are performed on a 3 kW Nd:Yag laser system. The modeling results exhibit a great agreement between the predicted and measured values for the hardened surface characteristics. The model evaluation reveal</span></span></span><span><span><span>s </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">also its ability to provide not only accurate and robust predictions of the temperature distribution and the hardness profile as well an in-depth analysis of the effects of the process parameters.</span></span></span> 展开更多
关键词 Laser surface Hardening 3D thermal Analysis Finite Element Modelling AISI 4340 Steel Laser Scanning patterns Taguchi Method ANOVA Nd:Yag Laser Source
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Spatial pattern of urban-rural integration in China and the impact of geography 被引量:2
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作者 Wei Pan Jing Wang +2 位作者 Yurui Li Shuting Chen Zhi Lu 《Geography and Sustainability》 CSCD 2023年第4期404-413,共10页
Urban-rural integration (URI) is a global challenge that is highly related to inequalities, poverty, economic growth, and other Sustainable Development Goals (SDGs). Existing research has evaluated the extent of URI a... Urban-rural integration (URI) is a global challenge that is highly related to inequalities, poverty, economic growth, and other Sustainable Development Goals (SDGs). Existing research has evaluated the extent of URI and explored its influencing factors, but urban-rural linkages are seldom incorporated in evaluation systems, and geographical factors are rarely recognized as the influencing factors. We construct a URI framework including regional economy, rural development, urban-rural linkage, and urban-rural gap. Based on a dataset consisting of 1,669 counties in China in 2020, we reveal the spatial pattern of URI and find a high correlation between the spatial pattern of URI and the relief degree of land surface (RDLS). Using structural equation modeling, we discover that topography has direct ( − 0.18, p < 0.001) and indirect ( − 0.17, p < 0.001) effects on URI. The indirect negative effects are mediated through the infrastructure, and the combination of localized advantages and modern technical conditions could mitigate the negative impact of topography. Finally, we identify 742 counties as lagging regions in URI, which can be clustered into eight types. Our findings could facilitate policy designing for those countries striving for integrated and sustainable development of urban and rural areas. 展开更多
关键词 Urban-rural integration Relief degree of land surface INFRASTRUCTURE Structural equation modelling Sustainable urban and rural development patterns Sustainable Development Goals
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Surface Water Pollution in the Yangtze River Delta:Patterns and Countermeasures 被引量:11
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作者 CHENZHENLOU XUSHIYUAN 《Pedosphere》 SCIE CAS CSCD 2002年第2期111-120,共10页
On the basis of field investigations, observations andexperimental data combined with environmental monitoring information,the status and the spatial and temporal patterns of surface waterpollution over the past ten y... On the basis of field investigations, observations andexperimental data combined with environmental monitoring information,the status and the spatial and temporal patterns of surface waterpollution over the past ten years in the Yangtze River Delta havebeen assessed. The water quality of large rivers is still very goodbut most of the medium-sized and small rivers have been veryseriously polluted. The appearance of black and odorous conditions inrivers in the urban areas has increased due to serious pollution byorganic matter with consequent high oxygen demand. Annual increasesin N and P concentrations in lakes have accelerated eutrophication.The water quality of river sin small towns is rapidly deteriorating.The main sources of surface water pollution include industrial anddomestic sewage, animal manures, chemical fertilizers in farmland,and polluted sediments in rivers and lakes. 展开更多
关键词 COUNTERMEASURES pollution patterns surface water the Yangtze RiverDelta
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The patterns of surface capillary-gravity short-crested waves with uniform current fields in coastal waters 被引量:3
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作者 Hu Huang Jia Fu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2006年第5期433-441,共9页
A fully three-dimensional surface gravitycapillary short-crested wave system is studied as two progressive wave-trains of equal amplitude and frequency, which are collinear with uniform currents and doubly-periodic in... A fully three-dimensional surface gravitycapillary short-crested wave system is studied as two progressive wave-trains of equal amplitude and frequency, which are collinear with uniform currents and doubly-periodic in the horizontal plane, are propagating at an angle to each other. The first- and second-order asymptotic analytical solutions of the short-crested wave system are obtained via a perturbation expansion in a small parameter associated with the wave steepness, therefore depicting a series of typical three-dimensional wave patterns involving currents, shallow and deep water, and surface capillary waves, and comparing them with each other. 展开更多
关键词 Short-crested waves Uniform currents patterns surface capillary-gravity waves Finite depth and deep water
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Surface property variations in flotation performance of calcite particles under different grinding patterns 被引量:6
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作者 XU Peng-yunq LI Jing +4 位作者 HU Cong CHEN Zhou YE Hong-qi YUAN Zhong-quan CAI Wen-ju 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第6期1306-1316,共11页
Based on the working principles of particle bed comminution, particles produced by high-pressure grinding rolls (HPGR) have surface properties different from particles produced by other grinding patterns, which exer... Based on the working principles of particle bed comminution, particles produced by high-pressure grinding rolls (HPGR) have surface properties different from particles produced by other grinding patterns, which exert great influence on mineral flotation. Flotation performances of calcite particles under different grinding patterns involving the use of HPGR, a jaw crusher, a dry ball mill, a wet ball mill, and a wet rod mill were studied using single mineral flotation tests. The surface properties of the particles under different grinding patterns were characterized to determine the flotation performance variation in terms of specific surface area, particle size distribution, AFM, XPS, and zeta potential. The results show that particles ground by HPGR exhibited improved flotation performance within the lower range of grinding fineness in both NaOL and dodecyl amine flotation systems compared to the particles prepared using other grinding patterns. Specific surface area, particle size distribution, surface roughness, Fe(III) contamination, binding energy, and zeta potential are greatly influenced by grinding patterns, which is the main cause of the flotation performance variation. 展开更多
关键词 CALCITE surface property grinding patterns high-pressure grinding rolls flotation performance
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Characteristics of the Summer Time Rainfall Patterns over China and the Indian Ocean Sea Surface Temperature Anomalies
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作者 彭模 韩雪 陈茂钦 《Meteorological and Environmental Research》 CAS 2010年第2期24-30,36,共8页
Using the monthly summer (June to August) precipitation data over China from 1979 to 1998,and the SST data in Indian Ocean of the overlapping periods,we have analyzed the spatial patterns as well as their temporal evo... Using the monthly summer (June to August) precipitation data over China from 1979 to 1998,and the SST data in Indian Ocean of the overlapping periods,we have analyzed the spatial patterns as well as their temporal evolution of the summer precipitation,along with the relationships between the precipitation over China and the SST in Indian Ocean,with the EOF and SVD methods respectively.The important results are:several canonical anomalous summer precipitation patterns have been identified.The summer SST in Indian Ocean is positively correlated with the simultaneous precipitation in the Yangtze River and Huai River Basin,while negatively with that in other parts of China. 展开更多
关键词 Precipitation in summer Rainfall pattern Sea surface temperature in Indian Ocean China
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Distribution Pattern of Heavy Metals in the Surface Sediments of the Jiaozhou Bay 被引量:6
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作者 陈正新 董贺平 +2 位作者 李绍全 袁红明 王保军 《Marine Science Bulletin》 CAS 2005年第2期41-56,共16页
Grain size analysis and chemical analysis of heavy metals are made for 312 surface samples of the Jiaozhou Bay. Nineteen samples of the waste water taken from the sewage discharge outlets along the eastern coast of th... Grain size analysis and chemical analysis of heavy metals are made for 312 surface samples of the Jiaozhou Bay. Nineteen samples of the waste water taken from the sewage discharge outlets along the eastern coast of the bay are also analyzed for heavy metals. Results show that heavy metals are richer in the east and poorer in the west of the bay. Sedimentary dynamic studies reveal that the distribution of heavy metals in the surface sediments of the Jiaozhou Bay is under the control of hydrodynamics. 展开更多
关键词 the Jiaozhou Bay surface sediments distribution pattern of heavy metals sedimentary dynamics
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Influence of the NAO on Wintertime Surface Air Temperature over East Asia:Multidecadal Variability and Decadal Prediction 被引量:5
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作者 Jianping LI Tiejun XIE +5 位作者 Xinxin TANG Hao WANG Cheng SUN Juan FENG Fei ZHENG Ruiqiang DING 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2022年第4期625-642,共18页
In this paper,we investigate the influence of the winter NAO on the multidecadal variability of winter East Asian surface air temperature(EASAT)and EASAT decadal prediction.The observational analysis shows that the wi... In this paper,we investigate the influence of the winter NAO on the multidecadal variability of winter East Asian surface air temperature(EASAT)and EASAT decadal prediction.The observational analysis shows that the winter EASAT and East Asian minimum SAT(EAmSAT)display strong in-phase fluctuations and a significant 60-80-year multidecadal variability,apart from a long-term warming trend.The winter EASAT experienced a decreasing trend in the last two decades,which is consistent with the occurrence of extremely cold events in East Asia winters in recent years.The winter NAO leads the detrended winter EASAT by 12-18 years with the greatest significant positive correlation at the lead time of 15 years.Further analysis shows that ENSO may affect winter EASAT interannual variability,but does not affect the robust lead relationship between the winter NAO and EASAT.We present the coupled oceanic-atmospheric bridge(COAB)mechanism of the NAO influences on winter EASAT multidecadal variability through its accumulated delayed effect of~15 years on the Atlantic Multidecadal Oscillation(AMO)and Africa-Asia multidecadal teleconnection(AAMT)pattern.An NAO-based linear model for predicting winter decadal EASAT is constructed on the principle of the COAB mechanism,with good hindcast performance.The winter EASAT for 2020-34 is predicted to keep on fluctuating downward until~2025,implying a high probability of occurrence of extremely cold events in coming winters in East Asia,followed by a sudden turn towards sharp warming.The predicted 2020/21 winter EASAT is almost the same as the 2019/20 winter. 展开更多
关键词 winter East Asian surface air temperature North Atlantic Oscillation Atlantic Multidecadal Oscillation Africa-Asia multidecadal teleconnection pattern coupled oceanic-atmospheric bridge multidecadal variability
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Effect of Partially Coherent Light on the Contrast of Speckle Patterns Obtained Using Digital Image Processing of Speckle Photography 被引量:2
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作者 Nasser A. Moustafa Mohamad M. El-Nicklawy +1 位作者 Amin F. Hassan Amany K. Ibrahim 《Optics and Photonics Journal》 2013年第5期324-329,共6页
The paper is devoted to study theoretically, the effects of some parameters on the visibility of the speckle patterns. For this propose, a theoretical model for a periodic rough surface was considered. Using this theo... The paper is devoted to study theoretically, the effects of some parameters on the visibility of the speckle patterns. For this propose, a theoretical model for a periodic rough surface was considered. Using this theoretical model, the effects of grain height, its density, the band width and spectral distribution of the line profile (Gaussian and Lorentzian) illuminating a rough surface on the visibility of speckle pattern are investigated. An experimental setup was constructed to study the effect of surface roughness and coherence of the illuminating light beam on the contrast of speckle pattern. The general behavior of the experimental results, which agree with published data, is compatible with the new theoretical model. 展开更多
关键词 SPECKLE PATTERN surface ROUGHNESS PARTIALLY COHERENT Light
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Doubly periodic patterns of modulated hydrodynamic waves:exact solutions of the Davey-Stewartson system 被引量:1
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作者 J.-H. Li S.-Y. Lou K.-W. Chow 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2011年第5期620-626,共7页
Exact doubly periodic standing wave patterns of the Davey-Stewartson (DS) equations are derived in terms of rational expressions of elliptic functions.In fluid mechanics,DS equations govern the evolution of weakly n... Exact doubly periodic standing wave patterns of the Davey-Stewartson (DS) equations are derived in terms of rational expressions of elliptic functions.In fluid mechanics,DS equations govern the evolution of weakly nonlinear,free surface wave packets when long wavelength modulations in two mutually perpendicular,horizontal directions are incorporated.Elliptic functions with two different moduli (periods) are necessary in the two directions.The relation between the moduli and the wave numbers constitutes the dispersion relation of such waves.In the long wave limit,localized pulses are recovered. 展开更多
关键词 Free surface waves · Periodic patterns · DaveyStewartson equations
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Experimental Investigation of Laser Surface Hardening of AISI 4340 Steel Using Different Laser Scanning Patterns 被引量:1
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作者 Baha Tarchoun Abderrazak El Ouafi Ahmed Chebak 《Journal of Minerals and Materials Characterization and Engineering》 2020年第2期9-26,共18页
Laser surface transformation hardening becomes one of the most modern processes used to improve fatigue and wear properties of steel surfaces. In this process, the material properties and the heating parameters are th... Laser surface transformation hardening becomes one of the most modern processes used to improve fatigue and wear properties of steel surfaces. In this process, the material properties and the heating parameters are the factors that present the most significant effects on the hardened surface attributes. The control of these factors using predictive modeling approaches to achieve desired surface properties leads to conclusive results. However, when the dimensions of the surface to be treated are larger than the cross-section of the laser beam, various laser-scanning patterns are involved. This paper presents an experimental investigation of laser surface hardening of AISI 4340 steel using different laser scanning patterns. This investigation is based on a structured experimental design using the Taguchi method and improved statistical analysis tools. Experiments are carried out using a 3 kW Nd: YAG laser source in order to evaluate the effects of the heating parameters and patterns design parameters on the physical and geometrical characteristics of the hardened surface. Laser power, scanning speed and scanning patterns (linear, sinusoidal, triangular and trochoid) are the factors used to evaluate the hardened depth and the hardened width variations and to identify the possible relationship between these factors and the hardened zone attributes. Various statistical tools such as ANOVA, correlations analysis and response surfaces are applied in order to examine the effects of the experimental factors on the hardened surface characteristics. The results reveal that the scanning patterns do not modify the nature of the laser parameters’ effects on the hardened depth and the hardened width. But they can accentuate or reduce these effects depending on the type of the considered pattern. The results show also that the sinusoidal and the triangular patterns are relevant when a maximum hardened width with an acceptable hardened depth is desired. 展开更多
关键词 LASER surface HARDENING Process Experimental Investigation LASER Scanning patterns AISI 4340 STEEL Hardness Profile Hardened Depth Hardened WIDTH Design of Experiment Analysis of Variance
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Effects of Surface-Active Elements Sulfur on Flow Patterns of Welding Pool 被引量:3
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作者 Yuzhen ZHAO, Yongping LEI and Yaowu SHI School of Materials Science and Engineering, Beijing University of Technology, Beijing 100022, China 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2005年第3期408-414,共7页
A 3D mathematical model is developed to calculate the temperature and velocity distributions in a moving gas tungsten arc (GTA) welding pool with different sulfur concentrations. It has been shown that, the weld penet... A 3D mathematical model is developed to calculate the temperature and velocity distributions in a moving gas tungsten arc (GTA) welding pool with different sulfur concentrations. It has been shown that, the weld penetration increases sharply with increasing sulfur content. When sulfur content increases beyond 80 × 10-6, the increase in sulfur content does not have an appreciable difference on the welding pool size and shape, and the depth/width remains constant. Sulfur changes the temperature dependence of surface tension coefficient from a negative value to a positive value and causes significant changes on flow patterns. The increase in soluble sulfur content and the decrease at free surface temperature can extend the region of positive surface tension coefficient. As sulfur content exceeds 125×10-6, the sign of surface tension coefficient is positive. Depending upon the sulfur concentrations, three, one or two vortexes that have different positions, strength and directions may be found in the welding pool. The contrary vortexes can efficiently transfer the thermal energy from the arc, creating a deep welding pool. An optimum range of sulfur content is 20-150×10-6. 展开更多
关键词 surface-active elements SULFUR Plow patterns Depth/width
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Preparation of La-Ti Composite Oxide Nanocrystal and Examination of Their Surface Topography with Atomic Force Microscope
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作者 LiGU YuanLiangWANG +2 位作者 LiLingTANG JiuJinZHU JunHanWU 《Chinese Chemical Letters》 SCIE CAS CSCD 2003年第4期429-432,共4页
With sol-gel method, nanometer La-Ti composite oxide was successfully prepared at a low temperature (750~800C) using polyethylene glycol as dispersant. By means of atomic force microscope, the surface pattern, partic... With sol-gel method, nanometer La-Ti composite oxide was successfully prepared at a low temperature (750~800C) using polyethylene glycol as dispersant. By means of atomic force microscope, the surface pattern, particle size distribution, and specific surface area were studied. The compound particle surface appears as a smooth sheet, the mean size of the compound is 25.38 nm. On the specific surface, the particle erects at a height of 4.69 nm. The surface area is 58.90 nm2. The La-Ti composite oxide nanocrystal prefers to narrow and even particle size distribution and the homogeneity of surface topography. 展开更多
关键词 La-Ti composite oxide nanocrystal surface pattern atomic force microscope.
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Postmastectomy Scar Boost Irradiation Using HDR Surface Mould Brachytherapy by 3D Image-Based Volume Optimization
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作者 Neelakandan Vijayaprabhu Karunanithi Gunaseelan +3 位作者 Nagarajan Vivekanandan Nagamuthu Karthik Cholayil Shamsudheen K. S. Reddy 《International Journal of Medical Physics, Clinical Engineering and Radiation Oncology》 2013年第4期139-146,共8页
Introduction: During postmastectomy radiotherapy (PMRT), it is recommended to boost the postmastectomy surgical scar with additional 10 Gy in 5 fractions in the patients with close or positive surgical margins. The el... Introduction: During postmastectomy radiotherapy (PMRT), it is recommended to boost the postmastectomy surgical scar with additional 10 Gy in 5 fractions in the patients with close or positive surgical margins. The electron beam therapy, though cumbersome, is usually preferred since it has the desired rapid fall of a dose beyond R85. An alternative but easier and reproducible treatment method for PMRT surgical scar boost using 3D CT image-based HDR surface mould brachytherapy is introduced and analyses of the target coverage and dose nearby organs-at-risk (OARs) using this method are evaluated in this study. Methods and Materials: This study includes twelve patients (five left-sided and seven right-sided chest wall), who were planned and treated with CT-image based surface mould HDR brachytherapy for chest wall scar boost (CWB) using Catheter Flap SetTM (Varian Medical Systems, USA) that were given concurrently during external beam radiotherapy (EBRT) treatments. Since no guidelines are available for delineating clinical target volume (CTV) structure to be used for postmastectomy scar boost, the CTV in this study was a uniform 5-mm thick volume drawn at 5 mm beneath the skin (CTVhdr_evl) and its extent was made conforming to the boost area marked on the skin and made visible in CT images by radiopaque wires. Results: Prescribed dose (PD) to CTVhdr_evl is 7.5 Gy in 3 fractions, and 2.5 Gy per fraction. The CTVhdr_evl volume receives the PD with mean V100%, V98% and V95% values which are 98.57%, 99.63% and 100% respectively. The mean dose for heart (MHD) is 2.71 Gy in left-sided CWB and 1.80 Gy in right-sided CWB plans. Mean lung dose (MLD) is 2.48 Gy for ipsilateral lung and 0.76 Gy for contralateral lung. Maximum dose to contralateral breast is 4.93 Gy and the mean dose is 0.79 Gy. The mean percent dose to the skin volume overlying the CTVhdr_evl is 138.6% and 3.7% of skin volume received 200% of the PD. Conclusion: The 3D image-based HDR surface mould achieved good CTV coverage with acceptable doses to OARs. Patient preparation, treatment planning, and execution in this method are less cumbersome and reproducible. Thus surface mould using flap applicator can be used whenever postmastectomy surgical scar boost is required. 展开更多
关键词 POSTMASTECTOMY Radiation Surgical SCAR Boost HDR surface mould Catheter Flap
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