A virtual experiment technique on the elementary behaviour of granular materials with discrete element method

Multi‐scale investigations aided by the discrete element method (DEM) play a vital role for current state‐of‐the‐art research on the elementary behaviour of granular materials. Similar to laboratory tests, there are three important aspects to be considered carefully, which are the proper stress/strain definition and measurement, the application of target loading paths and the designed experiment setup, to be addressed in the present paper. Considering the volume sensitive characteristics of granular materials, in the proposed technique, the deformation of the tested specimen is controlled and measured by deformation gradient tensor involving both the undeformed configuration and the current configuration. Definitions of Biot strain and Cauchy stress are adopted. The expressions of them in terms of contact forces and particle displacements, respectively, are derived. The boundary of the tested specimen consists of rigid massless planar units. It is suggested that the representative element uses a convex polyhedral (polygonal) shape to minimize possible boundary arching effects. General loading paths are described by directly specifying the changes in the stress/strain invariants or directions. Loading can be applied in the strain‐controlled mode by specifying the translations and rotations of the boundary units, or in the stress‐controlled mode by using a servo‐control mechanism, or in the combination of the two methods to realize mixed boundary conditions. Taking the simulation results as the natural consequences originated from a complex system, virtual experiments provide particle‐scale information database to conduct multi‐scale investigations for better understanding in granular material behaviours and possible development of the constitutive theories provided the qualitative similarity between the simulation results from virtual experiments and observations on real material behaviour. Copyright © 2011 John Wiley & Sons, Ltd.     

Soil saturation index of salt marshes subjected to spring‐neap tides: a new variable for describing marsh soil aeration condition

Organized spatial distribution of plants (plant zonation) in salt marshes has been linked to the soil aeration condition in the rhizosphere through simplistic tidal inundation parameters. Here, a soil saturation index (ratio of saturation period to tidal period at a soil depth) is introduced to describe the soil aeration condition. This new index captures the effects of not only the tidal inundation period and frequency but also the flow dynamics of groundwater in the marsh soil. One‐dimensional numerical models based on saturated flow with the Boussinesq approximations and a two‐dimensional variably saturated flow model were developed to explore the behaviour of this new soil aeration variable under the influence of spring‐neap tides. Simulations revealed two characteristic zones of soil aeration across the salt marsh: a relatively well aerated near‐creek zone and a poorly aerated interior zone. In the near‐creek zone, soils undergo periodic wetting and drying as the groundwater table fluctuates throughout the spring‐neap cycle. In the interior, the soil remains largely water saturated except for neap tide periods when limited drainage occurs. Although such a change of soil aeration condition has been observed in previous numerical simulations, the soil saturation index provides a clear delineation of the zones that are separated by an ‘inflexion point’ on the averaged index curve. The results show how the saturation index represents the effects of soil properties, tidal parameters and marsh platform elevation on marsh soil aeration. Simulations of these combined effects have not been possible with traditional tidal inundation parameters. The saturation index can be easily derived using relatively simple models based on five non‐dimensional variables. Copyright © 2010 John Wiley & Sons, Ltd.     

Reproductive rate of a marine planktonic copepodLabidocera euchaet a Giesbrecht in Xiamen Harbor

Reproductive rate of a marine planktonic copepodLabidocera euchaeta Giesbrecht in Xiamen Harbor bor was studied during the period from April 1986 to August 1987. Results showed that rate of egg production (F, eggs/(♀, d)) was positively correlated with temperature (T,^oC) and body weight of spawning female (Wc, μgC) as:F=0.0637 (T−7)^0.7445 Wc. Each month a maximum rate of egg production occurred at one of the five experimental temperatures (10°, 15°, 25°, and 30°C) near the monthly mean field temperature. The available food density (P, μgC/ml) had significant effect on specific rate of egg production (Fc, %C ♀/d) as:Fc=0.1732 (P-0.0179)/P. The gross efficiency of egg production of ca 62% in carbon was independent of food density snd ingestion rate. Observations on in situ egg production and hatching rate demonstrated that this species reproduces continuously all the year round, with summer as its high reproductive season and winter a low one. Ten generations a year is also suggested based on the number of the peaks of average population egg production rate. This agreed well with the result obtained from the generation-time equations. Egg-laying pattern was also observed and discussed.     

Summer temperature-salinity distributions and circulation characteristics of the source water of the Tsushima Warm current

Based on the data obtained in the area southwest of Kyushu in the summer of 1987, the temperature-salinity distribtutions and circulation characteristics are described and the origin of the Tsushima Warm Current is analysed.     

胶南隆起北缘石门-薛家庄韧性剪切带

石门－薛家庄韧性剪切带曾经历过正－左行平移、正－右行平移及左行正滑三期剪切运动。其东段以正－右行平移运动为主，中段具左行正滑性质，而其西段（小卜落崮韧性剪切带）则主要为左行平移。该剪切带同时又是一条经受了低绿片岩相－角闪岩相变形的多相剪切变形带。在剪切带的横剖面上，石英与斜长石的粒度在弱变形带中具双峰式分布的特征，在强变形带中则细而均匀；钾长石的粒度在弱变形带中粗而均匀，在强变形带中则呈现双峰式分布。钾长石和斜长石在韧性变形过程中均可向钠长石转化，应力越大转化越彻底。剪切带的变形机制为简单剪切机制，石英滑移系既有底面滑移又有柱面、菱面滑移。     

基于共相思想的新一代组件式GIS研究与开发

在简要回顾GIS软件和组件式GIS的发展之后，经过对比分析，提出同时支持两大主流开发平台——．NET和Java EE是新一代GIS组件的必然选择，并对可能实现的几种模式加以讨论．提出基于“共相”思想的C＋＋扩展模式是最为彻底和完关的解决方案，最后介绍在“共相”思想指导下的新一代组件式SuperMap GIS的设计和开发。     

胶南造山带西段区域构造格局及变形特征

胶南造山带西段显示了以韧性剪切带为主，穹隆构造、弧形构造及复杂的叠加褶皱共存的构造格局。主要的剪切系统有近水平拆离型、平行造山带走向的高角度走滑型、呈弧形展布的推覆型和造山带边缘隆－滑型韧性剪切带。走滑型剪切带是该区变形最明显的一组强剪切应变带，其运动性质以右行平移为主；弧形韧性剪切带由垂直造山带走向的近南北向转为平行造山带走向的近东西向，呈向NW凸出的弧形，自SEE向NWW方向推覆；造山带边缘韧性剪切带具明显的纵向分段性，反映了其在隆升的同时形成了垂直造山带和平行造山带的运动分量。主要的穹隆构造有尚庄穹隆、丝山穹隆、甲子山穹隆和官山穹隆。尚庄穹隆由片麻理围斜外倾、环形韧性剪切带及环状分布的包体群所显示，是岩浆强力定位造成的真正的片麻岩穹隆。弧形构造主要有龙古弧、诗雒弧和临沐弧，它们显示了胶南造山带三维空间上的“立交桥”式结构特征。     

TRANSFERABLE PHOSPHORUS IN SEDIMENTS OF THE HUANGHE RIVER ESTUARY ＇S ADJACENT WATERS

Based on a new idea for research on cycling of marine biogenic elements, this study showed that only the leachable form phosphorus in natural grain sizes manne sediments constitutes the transferable phosphorous in the sediments. The transferable phosphorus content in the natural grain sizes surface sediments in the Huanghe River estuary adjacent waters ranges from 58.5-69.8 μg/g, accounting for only 9.1%-11.0% of the total phosphorus content, whereas the leachable form (“transferable” )phosphorus content in the sediment after it was totally ground into powder was found to be 454.8-529.2μg/g, accounting for 73.4%-89.1% of the total phosphorus. Analysis of the correlation between thebill,ass of benthos and the leachable form (“transferable” ) phosphorus showed that most of the leachableform (“transferable”) phosphorus in the totally ground sediment did not participate in the marine biogeo chemical cycling. Furthermore, a synchronous survey on benthos showed that the biornass of meio-and maero-benthos exhibited good positive correlation with the leachable form of phosphorus in the naturalgrain sizes sediment, but peorer correlation with the leachable form (“transferable”) phosphorus in the totally ground sediment, indicating that transferable phosphorus in marine sediment is the leachable form of phosphorus in the natural grain sizes sediments, and is not the previously known leachable form(“transferable”) phosphorus obtained from the totally ground sediment.     

脉冲星γ射线辐射光度的分析

本文作者在脉冲星γ射线辐射的极冠模型的基础上，考虑光子在磁层中的级联过程，提出了级联过程中能量转化效率的概念并得出了转化效率公式，分析表明，能量转化效率只和磁场强度有关，与周期无关，考虑能量转化效率，我们计算了极冠模型的γ射线辐射光度，得出了可以和观测值比较的结果，本文结果倾向于支持脉冲星γ射线辐射的极冠模型。     

ESTIMATION OF SOUNDING ABILITY OF A BRILLOUIN LIDAR IN THE EAST CHINA SEA

Vertical profiles of sound speed in the sea can be measured by using laser excited Brillouin scattering. In this paper the dependence of the accuracy of sound speed measurement on the accuracy of the Brillouin shift measurement is analyzed. We calculated the maximum detecting depths of sound speed to an accuracy of 1 m/s by lidar with different laser pulse energy, platform altitude, telescope aperture and lidar effective attenuation coefficient. The estimation of sounding ability in the East China Sea is made in some stations. These data can be used in the design of Brillouin Lidar for the China Sea.