血管介入手术中的柔性虚拟力触觉系统研究     

冯安洋  陈笋  陈柏  耿令波  吴洪涛 《南京气象学院学报》2014,6(6):520-524

随着微创手术的发展,虚拟手术的应用前景越来越广阔.力反馈作为虚拟手术的核心技术,其实现的效果直接影响了虚拟手术的沉浸感.通过对经典包围盒碰撞检测算法进行研究比对,选择了球包围盒的碰撞检测算法,并建立了精确的反馈力计算模型,实现了介入血管中的柔性碰撞仿真.该仿真具有很高的实时性和精度.  相似文献   

Variability of Atlantic Meridional Overturning Circulation in FGOALS-g2简   总被引：3，自引：0，他引：3  

HUANG Wenyu  WANG Bin  LI Lijuan  DONG Li  LIN Pengfei  YU Yongqiang  ZHOU Tianjun  LIU Li  XU Shiming  XIA Kun  PU Ye  WANG Lu  LIU Mimi  SHEN Si  HU Ning  WANG Yong  SUN Wenqi  DONG Fang 《大气科学进展》2014,31(1):95-109

The variability of Atlantic Meridional Overturning Circulation （AMOC） in the pre-industrial control experiment of the Flexible Global Ocean-Atmosphere-Land System model, Grid-point Version 2 （FGOALS-g2） was investigated using the model outputs with the most stable state in a 512-yr time window from the total 1500-yr period of the experiment. The period of AMOC in FGOALS-g2 is double peaked at 20 and 32 years according to the power spectrum, and 22 years according to an auto-correlation analysis, which shows very obvious decadal variability. Like many other coupled climate models, the decadal variability of AMOC in FGOALS-g2 is closely related to the convection that occurs in the Labrador Sea region. Deep convection in the Labrador Sea in FGOALS-g2 leads the AMOC maximum by 3-4 years. The contributions of thermal and haline effects to the variability of the convection in three different regions [the Labrador, Irminger and Greenland-Iceland- Norwegian （GIN） Seas] were analyzed for FGOALS-g2. The variability of convection in the Labrador and Irminger Seas is thermally dominant, while that in the colder GIN Seas can be mainly attributed to salinity changes due to the lower thermal expansion. By comparing the simulation results from FGOALS-g2 and 11 other models, it was found that AMOC variability can be attributed to salinity changes for longer periods （longer than 35 years） and to temperature changes for shorter periods.  相似文献   

The variability of the East Asian summer monsoon and its relationship to ENSO in a partially coupled climate model     

Hui Ding  Richard J. Greatbatch  Wonsun Park  Mojib Latif  Vladimir A. Semenov  Xuguang Sun 《Climate Dynamics》2014,42(1-2):367-379

The variability of the East Asian summer monsoon (EASM) is studied using a partially coupled climate model (PCCM) in which the ocean component is driven by observed monthly mean wind stress anomalies added to the monthly mean wind stress climatology from a fully coupled control run. The thermodynamic coupling between the atmospheric and oceanic components is the same as in the fully coupled model and, in particular, sea surface temperature (SST) is a fully prognostic variable. The results show that the PCCM simulates the observed SST variability remarkably well in the tropical and North Pacific and Indian Oceans. Analysis of the rainfall-SST and rainfall-SST tendency correlation shows that the PCCM exhibits local air-sea coupling as in the fully coupled model and closer to what is seen in observations than is found in an atmospheric model driven by observed SST. An ensemble of experiments using the PCCM is analysed using a multivariate EOF analysis to identify the two major modes of variability of the EASM. The PCCM simulates the spatial pattern of the first two modes seen in the ERA40 reanalysis as well as part of the variability of the first principal component (correlation up to 0.5 for the model ensemble mean). Different from previous studies, the link between the first principal component and ENSO in the previous winter is found to be robust for the ensemble mean throughout the whole period of 1958–2001. Individual ensemble members nevertheless show the breakdown in the relationship before the 1980’s as seen in the observations.  相似文献   

Climate variability attributable to terrestrial and oceanic forcing in the NCAR CAM3-CLM3 Models     

Shanshan Sun  Guiling Wang 《Climate Dynamics》2014,42(7-8):2067-2078

Based on numerical experiments using the NCAR CAM3-CLM3 models, this paper examines the impact of soil moisture, vegetation, and sea surface temperature (SST) on the inter-annual variability of climate over land. For each element, two experiments are carried out, with the inter-annual variability preserved in one experiment and eliminated in the other. Differences in the standard deviation of the precipitation and air temperature at the inter-annual time scale are used to quantify the impacts from soil moisture dynamics, vegetation dynamics, and oceanic forcing. The impact of oceanic forcing is mainly limited to the Tropics, with the strongest signal in the equatorial zone, and moisture convergence is the key linkage between SST forcing and tropical precipitation. Soil moisture plays a significant role in climate variability during the rainy seasons of all semi-arid regions (which is consistent with many previous studies), and during the dry seasons of the humid Amazon. Evapotranspiration is identified as the main mechanism linking precipitation variability to soil moisture. Amazon is the only region where vegetation dynamics has a significant influence on precipitation variability. However, the impact of vegetation dynamics on temperature is strong over the US Great Plains in all four seasons and in the Amazon region during the dry and dry-to-wet transition seasons.  相似文献   

Projected climate change scenario over California by a regional ocean–atmosphere coupled model system     

Haiqin Li  Masao Kanamitsu  Song-You Hong  Kei Yoshimura  Daniel R. Cayan  Vasubandhu Misra  Liqiang Sun 《Climatic change》2014,122(4):609-619

This study examines a future climate change scenario over California in a 10-km coupled regional downscaling system of the Regional Spectral Model for the atmosphere and the Regional Ocean Modeling System for the ocean forced by the global Community Climate System Model version 3.0 (CCSM3). In summer, the coupled and uncoupled downscaled experiments capture the warming trend of surface air temperature, consistent with the driving CCSM3 forcing. However, the surface warming change along the California coast is weaker in the coupled downscaled experiment than it is in the uncoupled downscaling. Atmospheric cooling due to upwelling along the coast commonly appears in both the present and future climates, but the effect of upwelling is not fully compensated for by the projected large-scale warming in the coupled downscaling experiment. The projected change of extreme warm events is quite different between the coupled and uncoupled downscaling experiments, with the former projecting a more moderate change. The projected future change in precipitation is not significantly different between coupled and uncoupled downscaling. Both the coupled and uncoupled downscaling integrations predict increased onshore sea breeze change in summer daytime and reduced offshore land breeze change in summer nighttime along the coast from the Bay area to Point Conception. Compared to the simulation of present climate, the coupled and uncoupled downscaling experiments predict 17.5 % and 27.5 % fewer Catalina eddy hours in future climate respectively.  相似文献   

我国硫资源供需状况及需求预测     

赵明  陈春琳  高鹏  孙小红 《化工矿产地质》2014,36(3):173-181

全球硫资源特征及国内硫资源供需现状表明,国内硫资源贫乏,硫资源生产与消费逐年增加,尤其磷肥生产对硫资源的需求越来越迫切,预计到2020~2025年磷肥用硫量将达到峰值1620万t左右,不包括出口磷肥耗硫量。因此,加强硫资源的综合利用、加大硫铁矿找矿及矿山设计是非常有必要的。  相似文献   

Metallogenic and Metamorphic Age of the Hongtoushan Copper–Zinc Massive Sulfide Deposit,Liaoning Province,China     

Ye Qian  Fengyue Sun  Yajin Zhang  Liang Huo 《Resource Geology》2014,64(1):17-24

The Hongtoushan copper–zinc deposit is the only large Archean volcanogenic massive sulfide (VMS) deposit in China. This paper presents new information on the timing of metallogenesis and metamorphism of the deposit, including new cathodoluminescence (CL) images, and Th U^?1 and LA–ICP–MS U–Pb dating on zircons of the biotite–plagioclase gneiss and plagioclase–amphibole gneiss that host the deposit. The CL images and Th U^?1 ratios indicate that the zircons within the gneiss are of metamorphic origin. LA–ICP–MS dating of the plagioclase–amphibole gneiss yielded the upper intercept ages of 2549 Ma, and the biotite–plagioclase gneiss yielded the upper intercept ages of 2552 Ma and 2550 Ma correspondingly, indicating that the mineralization of the deposit occurred at around 2550 Ma. The rims of zircons within these host rocks yielded younger U–Pb ages at 2529, 2520 and 2515 Ma, identical to the age of felsic intrusive rocks in the study area. This suggests that the Hongtoushan VMS deposit underwent initial metamorphism and deformation at around 2520 Ma by the intrusion of granite magmas.  相似文献   

The influence of irrigation and Wuliangsuhai Lake on groundwater quality in eastern Hetao Basin,Inner Mongolia,China     

Dongnan Zhu  M. Cathryn Ryan  Biao Sun  Changyou Li 《Hydrogeology Journal》2014,22(5):1101-1114

Geochemical and isotopic characterization of groundwater and lake-water samples were combined with water and total dissolved solids balances to evaluate sources of groundwater quality deterioration in eastern Hetao Basin, Inner Mongolia, China. Groundwater quality is poor; 11 of 13 wells exceed drinking-water guidelines for at least one health-based parameter and all wells exceed aesthetic guidelines. The well water is largely derived from Yellow River irrigation water. Notably high uranium concentrations in the Yellow River, relative to world rivers, suggest groundwater uranium and other trace elements may originate in the river-derived irrigation water. Complex hydrostratigraphy and spatial variation in groundwater recharge result in spatially complex groundwater flow and geochemistry. Evapotranspiration of irrigation water causes chloride concentration increases of up to two orders of magnitude in the basin, notably in shallow groundwater around Wuliangsuhai Lake. In addition to evapotranspiration, groundwater quality is affected by mineral precipitation and dissolution, silicate weathering, and redox processes. The lake-water and TDS balances suggest that a small amount of discharge to groundwater (but associated with very high solute concentrations) contributes to groundwater salinization in this region. Increasing salinity in the groundwater and Wuliangsuhai Lake will continue to deteriorate water quality unless irrigation management practices improve.  相似文献   

A new theoretical method for analyzing confined dry granular flows     

Gordon G. D. Zhou  Charles W. W. Ng  Q. C. Sun 《Landslides》2014,11(3):369-384

A granular body may deform in a continuous fashion such that the solid particles remain in close contact. Previous research works have always used the frictional Coulomb-like continuum treatment for analyzing granular bodies. However, this approach is only applicable for quasi-static conditions and cannot capture the complicated granular contact behavior of solid particles inside a failing granular body. This paper applies a revised Savage–Hutter equation to model granular flows moving down a confined, sloping channel. The Coulomb contact friction law is modified to consider the effect of the shear rate inside a granular body. This new method also considers the confinement effect of a sloping channel on granular flow mobility. The derived depth-averaged equations of motion bear a resemblance to nonlinear shallow-water wave equations. Results computed using the derived equations are compared with measurements from flume model tests, and consistency is found between the two.  相似文献   

中国西部地区方沸石胶结相与碎屑岩次生优质储集层形成机制   总被引：2，自引：0，他引：2       下载免费PDF全文

孙玉善  刘新年  张艳秋  董尉凯  徐彦龙  师桂霞  林艳波  李安琼 《古地理学报》2014,16(4):517-526

含油气盆地碎屑岩次生优质储集层的发育,除了与广泛发育的方解石胶结相有关外,在中国西部还有一类与沸石族自生矿物胶结的成岩相有关,其中以溶蚀方沸石胶结相形成的次生优质储集层与油气聚集成藏又有十分密切的关联。经实例分析:与自生方沸石胶结有关的成岩相主要受控于扇(辫状河)三角洲前缘相带、火山岩物源和成岩早期的碱性环境;次生优质储集层的形成在时间上主要处于成岩中期A阶段,在空间上受控于邻近的烃源岩、圈闭和输导体的沟通。方沸石矿物在物理性质上具有抗压易溶(有机酸)作用,较其他常见的自生矿物(胶结物)相对优越,就方沸石易于溶蚀的特点而言是较为理想的自生矿物(胶结物)。其溶蚀对孔隙度的贡献率在50％～75％之间,发育几率占绝对优势。所以,在方沸石发育的相带中寻找以粒间溶蚀孔为主的优质储集层,具有可靠的操作性和现实性。  相似文献