深水重力流与底流交互作用研究进展

重力流和底流是深水环境下的两大基本流动体制,对二者交互作用的研究是当前沉积学研究的前缘和薄弱环节.底流及底流改造沉积物在岩芯上具有上部侵蚀面、双泥层、牵引流成因的各种层理等识别标志;底流成因的漂积体在剖面上呈现透镜状单元、迁移性特征及波状发射等地震反射特征.本文通过综述重力流与底流交互作用的研究成果,认为依据某段地质时期内深水盆地中主导沉积机制的不同,将重力流与底流的交互作用分为以下4种表现形式:①底流对前期重力流沉积进行改造;②重力流对前期底流沉积进行改造;③重力流与底流交互主导同一地区的沉积以及④底流与重力流同时作用于沉积物.相对海平面变化、气候(冰期～间冰期)变化、构造活动、地形地貌等因素,主要通过影响重力流与底流机制的相对强度大小,控制深水重力流与底流交互作用的进行.中国南海具有重力流与底流交互沉积的优越地质条件,发育有单向迁移水道、沉积物波等特色沉积记录.加强现今海流观测,对于南海底流循环格架的建立意义重大.     

Devonian land-sea interaction： Evolution of ecosystems and climate （DEVEC）—the new IGCP Project 499

During the last two decades research on the Devonian period was part of some successful IGCP projects, such as IGCP 216 ““““““““Global biological events in Earth history““““““““ (led by O.H. Walliser), IGCP 335 ““““““““Biotic recoveries from mass extinctions““““““““ (led by D.H.Erwin and E.G. Kauffman), and IGCP 421 ““““““““North Gondwanan Mid-Palaeozoic bioevent /biogeography patterns in relation to crustal dynamics““““““““ (led by R. Feist and J.A. Talent）.     

Neutron Scattering and Computer Simulation Studies of Ice Dynamics

In this article we describe a range of simulations (lattice dynamics and molecular dynamics) of the inelastic incoherent neutron scattering spectra of ices (normal ice, ice Ⅱ and ice Ⅷ ). These simulations use a variety of different intermolecular potentials from simple classic pair-wise (rigid and non-rigid molecule) potentials to sophisticated polarisable potentials. It was found that MCY makes stretching and bending interactions too weak while others do them well. We demonstrate that in order to reproduce the measured neutron spectrum, greater anisotropy (or orientational variation) is required than these potentials presently provide.     

Spatial interaction and network structure evolvement of cities in terms of China’s rail passenger flows

Cities separated in space are connected together by spatial interaction （SI） between them. But the studies focusing on the SI are relatively few in China mainly because of the scarcity of data. This paper deals with the SI in terms of rail passenger flows, which is an important aspect of the network structure of urban agglomeration. By using a data set consisting of rail O-D （origin-destination） passenger flows among nearly 200 cities, inter-city rail distance O-D matrixes, and some other indices, it is found that the attenuating tendency of rail passenger is obvious. And by the analysis on dominant flows and spatial structure of flows, we find that passenger flows have a trend of polarizing to hubs while the linkages between hubs upgrade. However, the gravity model reveals an overall picture of convergence process over time which is not in our expectation of integration process in the framework of globalization and eco- nomic integration. Some driven factors for the re-organization process of the structure of urban agglomeration, such as technique advance, globalization, etc. are discussed further based on the results we obtained.     

天然褐铁矿的光电化学响应及对嗜酸性氧化亚铁硫杆菌生长的影响

通过对比实验研究了天然褐铁矿对嗜酸性氧化亚铁硫杆菌(A.f.)生长的影响.利用X射线衍射分析(XRD)确定实验中所用天然褐铁矿样品的主要物相为针铁矿和赤铁矿,紫外-可见漫反射光谱(UV-Vis DRS)和不同光照条件下的时间电流曲线表明天然褐铁矿在可见光下具有良好的光电化学响应.采用H型装置进行双室体系反应,设置了3组对比实验,结果显示A.f.在有光催化电子传入情况下生长较好,在96 h内细胞浓度增加了12倍,3组实验中Fe2+浓度的变化规律与A.f.的生长趋势相对应.由此揭示了天然褐铁矿促进A.f.生长的机制为:在光照作用下天然褐铁矿能产生光生电子-空穴对,光生空穴被电子供体(抗坏血酸)捕获,分离出的光生电子传入阴极室能够将Fe3+还原为Fe2+,实现Fe2+的电化学再生,提供充足的电子能量来源,促进细菌生长.     

四肢桁式钢管混凝土悬链线拱面内稳定性

为研究四肢桁式钢管混凝土(CFST)悬链线拱面内稳定性,采用有限元法开展桁式CFST悬链线拱在轴压或压弯作用下的面内弹塑性屈曲分析。基于试验数据与数值模拟验证模型参数,探讨平面内屈曲破坏模式,揭示屈曲机理;引入全拱和弦杆的归一化长细比,考虑弦杆屈曲影响的交互因数,得到轴压作用下的统一屈曲曲线;提出压弯作用下面内稳定承载力的交互作用方程。结果表明：斜腹管屈曲大幅降低稳定承载力;桁式CFST悬链线拱在屈曲破坏过程中总是存在弦杆变形,弦杆变形对稳定性的影响不可忽视;屈曲曲线可用于轴压桁式悬链线拱,交互方程可为一般荷载作用下的桁式悬链线拱提供较好的下限预测。该结果对四肢桁式CFST悬链线拱的面内稳定性设计具有指导意义。     

Isolated Main Galaxy Pairs from the SDSS Data Release 4

From the Main galaxy data of the SDSS Data Release 4 (SDSS4), we have identified close galaxy pairs at neighbourhood radius R = 100 kpc by three-dimensional cluster analysis. Using the criterion that an "isolated galaxy pair" must be separated from its "nearest neighbor" by more than 500 kpc, we constructed an isolated galaxy pair sample of 1158 pairs. We also constructed a random pair sample by randomly selecting 1158 galaxy pairs from the Main galaxy sample, which has the same redshift distribution as the isolated galaxy pair sample, and in which the two components of any pair have the same redshifts. Comparative studies of luminosity and size between the members of the galaxy pairs are performed. We find and further confirm there is no tendency for paired galaxies to have similar luminosities or sizes. From the isolated pair sample we also selected a subsample with the magnitude limit of the primary raised by 2 magnitudes, so as to include pairs in which the secondary is 2 magnitudes fainter than the primary. This subsample contains 82 pairs. A random pair sample is similarly constructed.     

南海北部湾盆地协调?非协调供源样式与沉积交互作用耦合响应:以涠西南凹陷C洼为例

断陷湖盆具有多物源注入和地貌复杂的特征,开展从源到汇的分析有利于深化对有利砂体展布的认识. 以涠西南凹陷C洼及邻近凸起为例,基于测井和地震资料刻画了源?汇系统的要素特征,区分出协调和非协调两类供源样式,明确了多物源汇聚下沉积体系的时空展布规律. 研究表明,涠西南凹陷C洼流三段接受北部、南部短轴体系和西部长轴体系的联合供源,南部体系可进一步划分为S-Ⅰ、S-Ⅱ、S-Ⅲ三个次级体系. 其中,长轴体系具有低缓的源区和宽缓的沟谷,表现为常年稳定和牵引流主导的协调型供源样式,在沉积区发育粒度和含砂率相关变化的辫状河体系;短轴体系具有相对高陡的源区、深切的沟谷,如S-Ⅱ单元,代表着脉冲式和重力流主导的非协调供源样式,在沉积区发育厚层泥岩夹薄层砾岩的盆底扇和扇三角洲体系. 在流三下亚段沉积时期,在南部短轴非协调体系的强烈供源下,长轴协调体系主体被推离C洼南部而分布在中北部;在流三上亚段沉积时期,湖平面上升后短轴源区面积减小使得非协调体系供源减弱,长轴协调体系则保持稳定的供源强度并向南部偏转以填充余出的可容空间. 通过对涠西南C洼及邻近凸起开展源?汇系统分析,强调供源样式和沉积交互作用耦合控制了有利砂体的时空展布,对涠西南凹陷C洼及相似断陷湖盆的油气勘探具有一定指导意义.