一种制备单原子碳链的方案

考虑到迄今为止实验上尚不能制备含有上百个原子的自由单原子链,本文提出利用探针从graphene中拉伸较长单原子碳链的设想,并通过分子动力学计算发现,室温下可以利用C60探针以1 m/s的速度从graphene的zigzag边缘拉出较长的一维单原子碳链,为实验提供了一种制备单原子碳链的可能方案.     

柴北缘冷湖地区砂岩型铀矿床地质特征及成矿条件分析

冷湖地区砂岩型铀矿是近年柴北缘新发现的具有工业价值的铀矿床,为了进一步研究该地区砂岩型铀成矿岩石学及矿物学特征、铀成矿条件等问题,本文在野外地质调查的基础上,利用偏光显微镜结合电子探针分析手段,对该区内大煤沟组中含矿岩石进行了系统研究.结果表明:研究区中侏罗统大煤沟组含矿岩石类型主要为(粉)砂质泥岩、薄层煤及细粒石英杂...     

孔压触探测试中探头饱和问题的探讨

孔压触探（ＣＰＴＵ）作为一种新型土体原位测试技术,日益引起人们的重视和推广,但ＣＰＴＵ测试中的一些技术环节尚需进一步探索和规范。本文对严重影响ＣＰＴＵ测试结果精度的探头饱和问题进行了探讨,指出探头饱和的重要性、一般方法、注意事项及检验措施。     

Bacteriological examination of ballast water in Singapore Harbour by flow cytometry with FISH

In this study the concentrations of total bacteria, enterobacteria, Vibrio spp., and E. coli have been compared for ballast water samples taken from ships in Singapore Harbour. The cell concentrations were enumerated using FISH and flow cytometry. The data were highly variable, reflecting the many influences upon ballast water as it is utilized in the shipping industry. The concentration of bacterial species was determined as a proportion of the total concentration of cells for the ballast water sampled. For the ballast water sampled these concentrations were 0.67-39.55% for eubacteria, 0-2.46% for enterobacteria, 0.18-35.82% for Vibrio spp., and 0-2.46% for E. coli. Using FISH and flow cytometry, an informative determination of the bacterial hazards of ship ballast water can be made.     

小型内波实验水槽及其供水、造波与量测系统

本文介绍了作者们设计并制造的小型内波实验水槽系统,它包括水槽、双缸法供水系统、造波与消波装置以及量测与显示手段。实验表明,此系统性能良好,可进行内波科研与教学实验。     

FICUS,a new in-situ probe for resistivity measurements in unconsolidated marine sediments

Physical properties of shallow sediments measured at a particular site can not easily be extrapolated over a given profile. The number of samples required to define sediment properties adequately can then become time-consuming and expensive. Laboratory and in-situ experimentations have shown that electrical probing provides a useful complementary technique to extrapolate results from cores. These experiments have pointed out the need for quantitative, easily-transportable and fast resistivity measurements combining high vertical resolution with azimuthal resolution and full coverage, in the shallow subsurface. A new prototype probe called FICUS (Formation Imaging and Coring for Unconsolidated Sediments) has been developed to bridge this gap. FICUS is designed to provide in-situ high resolution electrical resistivity images of the upper few meters of shallow unconsolidated sediments.Laboratory experiments have been completed to test the feasibility of this technique to provide resistivity images of unconsolidated sediments. Laboratory images agree with theoretical predictions from numerical modelling. The obtained cm-scale resolution could be used for petrophysical and sedimentary purposes. The probe may offer additional information about changes in porosity and pore morphology caused by climatic cycles, since electrical resistivity is known to be especially sensitive to these changes. The probe could also allow to detect and map organic pollutants in the future.     

Numerical Study of a Kyucho and a Bottom Intrusion in the Bungo Channel,Japan: Disturbances Generated by the Kuroshio Small Meanders

The generation and propagation mechanisms of a Kyucho and a bottom intrusion in the Bungo Channel, Japan, have been studied numerically using the hydrostatic primitive equations by assuming density stratification during summer. The experiments are designed to generate a Kuroshio small meander in Hyuga-Nada, which acts as a trigger for these disturbances. After the current speed of the Kuroshio is changed, a small meander is generated. At the head of the small meander, warm Kuroshio water is engulfed, and encounters the southwest coast of Shikoku. However, convergence of heat flux on the bump off Cape Ashizuri suppresses the generation of a warm disturbance, if the current speed is large. As the cold eddy associated with the small meander approaches Cape Ashizuri, the heat flux diverges on the bump. This heat source forces a warm disturbance, which intrudes along the east coast of the Bungo Channel as a baroclinic Kelvin wave (a Kyucho). After the cold eddy passes off Cape Ashizuri, the Kuroshio approaches the bump again. Strong convergence of heat flux then occurs on the bump, which forces a cold disturbance. This disturbance propagates as a topographic Rossby wave along the shelf break at the mouth of the channel. After the topographic wave reaches the west end of the shelf break, it intrudes along the bottom layer of the channel as a density current (a bottom intrusion). These results suggest that a Kyucho and a bottom intrusion are successive events associated with the propagation of the small meander.     

密度三侧向探管的故障分析

根据密度三侧向探管的工作原理,对该探管在工作中常出现的电源不振荡,直流高压过低,三侧向电路的供电不足、电流不反馈、部分档位误差大,数字传输不正确,放射性输出重复突变、面板无显示或测井无输出等故障现象进行剖析,指出各类故障的易发位置、器件名称与标准指示值,提出了排除故障时应采取的检查方法及相关程序。     

On the validity of the flow rule postulate for geomaterials

This paper is concerned with a fundamental assumption in the theory of plasticity: the direction of plastic strain increments is independent of the loading (stress) increment direction. This assumption, also known as plastic flow rule postulate, works quite well for metal‐like materials. However, geomaterials such as sand present deformational mechanisms that are distinctive from those of metals when they are loaded. As such, we hereby examine the validity of this postulate for granular media accounting for their discrete nature. This is accomplished by analysing the mechanical behaviour of a cubic assembly of polydispersed spherical articles using a particle flow code. An extension to Gudehus' response envelope to three‐dimensional conditions is used to study the incremental character and influence of loading direction on the behaviour of these materials. It is found that plastic flow in granular media is governed by both current state variables and incremental loading direction and magnitude, especially under non‐axisymmetric stress conditions. The flow rule postulate of plasticity remains valid only in axisymmetric and biaxial conditions. We also verified that the plastic response might be significantly influenced by the stress path (or history) taken prior to loading. These findings raise the question of whether or not classic elastoplastic models based on the above postulate will have serious shortcomings, especially in true‐triaxial conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

基于FLAC3D含SMP强度准则黏弹塑性模型的二次开发

在分析岩土工程时通常会用到强度准则,在众多强度准则中,SMP准则的物理意义最为明确,其屈服函数表达式是非线性形式,对其进行二次开发研究具有较为重要的意义。利用FLAC3D的二次开发平台,使用VC++环境在FLAC3D软件中实现了含SMP强度准则的黏弹塑性模型的开发,其中的SMP强度准则推广到了黏性土,通过一个简单的算例验证了程序编制的正确性和可靠性,所采用的相关二次开发的思路可以为其他强度准则及流变本构模型的二次开发提供参考。