A three-dimensional heat transfer and thermal cracking model considering the effect of cracks on heat transfer

A simple three-dimensional heat transfer model is developed to consider the hindering effect of cracks on heat transfer. The 3D heat transfer model can also be applied to numerical methods such as the combined finite-discrete element method (FDEM), discrete element method (DEM), discontinuous deformation analysis (DDA), the numerical manifold method (NMM), and the finite element method (FEM) to construct thermo-mechanical coupling models that allow these methods to solve thermal cracking problems and dynamically consider the hindering effect of cracks on heat transfer. In the 3D heat transfer model, the continuous-discontinuous medium is discretized into independent tetrahedral elements, and joint elements are inserted between adjacent tetrahedral elements. Heat transfer calculations for continuous-discontinuous media are converted to heat conduction in tetrahedral elements and the heat exchange between the adjacent tetrahedral elements through the joint element. If the joint element between adjacent tetrahedral elements breaks (ie, a crack generates), the heat exchange coefficient of the joint element is reduced to account for the hindering effect of cracks on heat conduction. Then the model and the FDEM are combined to build a thermo-mechanical coupling model to simulate thermal cracking. The thermally induced deformation, stress, and cracking are investigated by the thermo-mechanical coupling model, and the numerical results are compared with analytical solutions or experimental results. The 3D heat transfer model and thermo-mechanical model can provide a powerful tool for simulating heat transfer and thermal cracking in a continuous-discontinuous medium.     

Comparison of halo detection from noisy weak lensing convergence maps with Gaussian smoothing and MRLens treatment

Taking into account the noise from intrinsic ellipticities of source galaxies,we study the efficiency and completeness of halo detections from weak lensing convergence maps.Particularly,with numerical simulations,we compare the Gaussian filter with the so called MRLens treatment based on the modification of the Maximum Entropy Method.For a pure noise field without lensing signals,a Gaussian smoothing results in a residual noise field that is approximately Gaussian in terms of statistics if a large enough nu...     

四川盆地雷四3亚段油气勘探方向

近年来,中石油和中石化在四川盆地雷口坡组雷四³亚段的勘探陆续取得重要进展,展示了良好的勘探前景。笔者结合新钻探井和最新研究成果,从地层、沉积相、烃源岩、储层和成藏等多方面采用烃源对比、埋藏史及烃源岩热演化史、包裹体测温等方法对四川盆地雷四³亚段的含油气地质条件进行了进一步分析,总结了其油气成藏特征,提出了有利勘探区带,以期有助于拓展四川盆地雷口坡组的勘探领域。研究结果表明:雷四³亚段天然气以雷口坡组和须家河组烃源岩混合来源气为主;储集空间以粒间溶孔、晶间溶孔为主,属低孔低渗储层;雷四³亚段气藏为2期成藏,烃源岩于中、晚侏罗世进入生烃高峰;雷四³亚段具有构造和构造-岩性地层2种气藏类型,龙门山山前断褶带为构造气藏的有利勘探区,新津-邛崃斜坡带与梓潼-盐亭斜坡带是构造-岩性地层气藏的有利勘探区。     

http://www.sciencedirect.com/science/article/pii/S1674987111001307

South China Sea(SCS) is the largest Western Pacific marginal sea.However,microbial studies have never been performed in the cold seep sediments in the SCS.In 2004."SONNE" 177 cruise found two cold seep areas with different water depth in the northern SCS.Haiyang 4 area,where the water depth is around 3000 m.has already been confirmed for active seeping on the seafloor.such as microbial mats,authigenic carbonate crusts and bivalves.We investigated microbial abundance and diversity in a 5.55-111 sediment core collected from this cold seep area.An integrated approach was employed including geochemistry and 16S rRNA gene phylogenetic analyses.Here,we show that microbial abundance and diversity along with geochemistry profiles of the sediment core revealed a coupled reaction between sulphate reduction and methane oxidation.Acridine orange direct count results showed that microbial abundance ranges from 10~5 to 10~6 cells/g sediment(wet weight).The depth-related variation of the abundance showed the same trend as the methane concentration profile.Phylogenetic analysis indicated the presence of sulphate-reducing bacteria and anaerobic methane-oxidizing archaea.The diversity was much higher at the surface,but decreased sharply with depth in response to changes in the geochemical conditions of the sediments,such as methane,sulphate concentration and total organic carbon.Marine Benthic Group B.Chloroflexi and JSl were predominant phylotypes of the archaeal and bacterial libraries,respectively.     

Zircon SHRIMP U-Pb Age, Geochemistry and Genesis of the Youdong Granite in Northern Guangdong

油洞岩体位于诸广南部岩体中部,是一个重要的产铀岩体,岩性为中粒小斑状二云母花岗岩.SHRIMP锆石U-Pb年龄为232±4 Ma(MSWD=3.2),属于印支早期岩浆活动产物.该岩体在主量元素方面,具有富硅(SiO2平均为72.65％)、富铝(A/CNK值平均为1.12)和高的K2O/Na2O比值(平均为1.79);在微量元素方面,大离子元素富集,Ba、Sr、P、Ti、Nb、Ta亏损明显,具有高的Rb/Sr(平均为8.08)和Rb/Nb比值(平均为20.96);在稀土元素方面,轻稀土明显富集,配分模式呈右倾型,Eu亏损明显;在同位素方面,εNd(t)值低(平均为-11.9),(87Sr/86 Sr)i高(平均为0.72330),Nd模式年龄古老(平均为1954 Ma).这些特征一致表明,油洞岩体属于典型的壳源型花岗岩范畴,是在华南地块和印支地块碰撞结束后不久形成的伸展构造环境中,位于中—下地壳部位的古—中元古代地壳组分由于在地壳缩短之后的伸展、减薄环境下产生的减压、导水和地幔上涌等因素的综合影响下,由泥质岩和砂质岩混合组成的源区发生部分熔融而形成.     

INS位置精度对GPS整周模糊度解算影响分析

在基于载波相位观测值的DGPS/INS组合导航中,GPS失锁重捕获时,仅利用自身的观测信息很难快速恢复整周模糊度,使用INS位置信息辅助GPS模糊度解算的方法可以有效解决这个问题。以模糊度精度衰减因子(ADOP)作为指标,分别研究了松组合和紧组合两种模式下INS位置精度与GPS模糊度解算成功率之间的关系。结果表明:中低精度的惯导设备能够有效减小ADOP值,提高GPS模糊度解算的精度及可靠性。     

临潼地震台水温与远近场地震关系研究

系统分析临潼地震台水温20多年的连续观测数据变化特征,提取水温的正常动态与异常形态,及其与远、近场地震的关系,取得以下结果:水温较规则的夏高冬低的年周期动态特征,为正常动态;持续上升—转折下降及年周期消失属于异常动态;异常动态与青藏块体及其周缘M≥7.5远场大震以及该台所处的渭河盆地ML≥4地震存在较好的相关性.结果对揭示1988年以来青藏高原块体的地球动力学条件具有一定指示意义.     

广西公路建设对生物多样性的潜在影响

根据广西的生物多样性特征,以及因公路网络对景观结构的改变而造成的对生物多样性的潜在影响,文章主要通过公路阻隔效应指数(I)及公路对生物多样性影响指数(B),运用GIS技术,以5 km×5 km的像元为单元格计算各指数的数值,从而确定广西公路建设对生物多样性影响的区域特征及差异.结果表明,桂北山区、桂西南岩溶山区和广西边缘山区是生物多样性最易受到公路建设影响的区域,这些地区的生物多样性敏感而特殊,需要特别注意采取必要的保护措施.     

An Orbital Prediction Algorithm for LEO Satellites Based on Optical Observations of Short Arcs at Single Station

The forecasting technique of the target tracking based on the short arcs at single station is an important way to guarantee that high-precision photoelectric theodolites can normally track and capture the targets in unconventional environments. We construct the tracking prediction algorithm based on nonlinear filter, which can provide the guiding data for the closed loop tracking under normal circumstances. At the same time we also construct the target prediction algorithm based on the nonlinear transformation, without valid observational data, which can provide a track guidance for the theodolite and ensure that the targets will not be lost. It is demonstrated that the nonlinear filtering is more effective than the EKF (extended Kalman filter) in the tracking prediction algorithm of the short arcs at single station. The results indicate that the nonlinear filter designed in this paper can be used as the guiding algorithm for the optical tracking equipments. And its guiding accuracy is in the same order of magnitude of the theodolite's random measurement accuracy. When the systematic error of the equipments reaches 50″, the accuracy can achieve 20″ for predictions in 60 s. This still satisfies the requirement of the field of view of the tracking equipments.     

FASTL波段多波束馈源设计的初步分析

把抛物面天线的偏焦理论应用于FASTL波段多波束馈源系统的设计,分析了馈源喇叭横向偏焦距离与相应波束偏离角之间的关系,结合多波束射电望远镜扫描方式的要求,给出了FASTL波段多波束馈源的工作带宽、多波束馈源中相邻喇叭的间距以及喇叭口径大小的限制,并对正六边形阵列中处于不同位置的喇叭对应的波束的主瓣情况作了详细计算和分析。由此说明了FASTL波段多波束馈源采用19波束的可行性。另一方面,根据得到的工作频率带宽和喇叭口径大小的情况,对OMT和喇叭类型的选择进行了探讨。本文给出了FASTL波段多波束系统的大概轮廓,为进一步精确设计指明了方向。