我国城市群发展中的物流、信息流整合

我国城市群的现代物流业和信息化仍处于起始阶段,存在着许多问题和制约因素,物流、信息流的不整合是当前城市群发展的一个重大瓶颈。物流、信息流整合的主要任务是构建现代物流网和高速信息网。前者包括综合配套物流基础设施、建立现代物流支撑体系、改造企业传统物流模式、加强政府指导和协调、完善物流业发展的政策法规和对现代物流业实行政策倾斜。后者包括综合利用信息资源、加强信息基础设施建设、统一开发信息基础骨干传送网、统一开发电子政务核心平台、统一开发信息产业项目和组织研制标准化体系。     

基于土壤切片技术的细观孔隙实验研究及其分布规律表征

岩土多孔材料孔隙分布特性强烈影响其宏观物理力学特性,细观孔隙研究具有极其重要的意义.采用固化剂及蓝色有机染料对生态护坡材料进行固化和染色,基于土壤切片技术获取样本的典型剖面,利用高分辨率相机采集剖面彩色图像,借助IPP技术获取细观孔隙分布数据.结果表明：细观孔隙度随孔径分布较为均匀,不同样本的细观孔隙数量分布较为近似,数量分布曲线越光滑,材料结构越稳定.为合理描述细观孔隙分布规律,提出了一种改进的隙率模型,较已有孔隙率模型,改进模型在二维空间内具有更广的适用范围及更小的预测误差.     

基于黏弹性接触的颗粒材料蠕变特性研究

强黏结土体或胶凝砂砾石料等颗粒材料的颗粒间存在较大黏结力,在低应力情况下主要由颗粒接触特性决定颗粒材料的宏观蠕变特性。基于颗粒细观力学方法,研究了二维各向同性颗粒材料的蠕变特性。首先引入速率相关的力与位移关系描述颗粒材料细观颗粒间特性。其次,运用Laplace变换,将时间域内的线黏弹性颗粒材料细观均匀化问题转化为拉氏空间内线弹性颗粒材料细观均匀化问题,随后基于颗粒材料线弹性问题在Reuss、Voigt和一般位移场三种假设下的解,通过Laplace逆变换得到颗粒材料相应的宏观蠕变特性解析模型,并建立了材料蠕变特性的上下限。最后,通过理论模型的解析解与商业软件（PFC2D）的数值结果的对比,验证了理论模型的合理性。     

西藏哈姆曲锑(金)矿床曲珍矿段S、Pb同位素组成及意义

西藏哈姆曲锑(金)矿床位于雅鲁藏布江结合带西缘, 矿体主要赋存于晚白垩世侵入岩中, 糜棱岩化闪长玢岩是其主要的赋矿围岩.矿体受NNE—SSW向断裂控制, 主要呈脉状、层状、透镜状产出.在野外地质调查和分析矿床成矿地质条件的基础上, 对矿床辉锑矿进行了 S、Pb 同位素研究, 探讨了矿床的成矿物质来源.辉锑矿δ34S值在...     

On the stress-force-fabric equation in triaxial compressions: Some insights into the triaxial strength

The strength of granular materials during triaxial compression is investigated via a grain scale analysis in this paper. A 3D Discrete Element Method (DEM) program provides the triaxial strength data and helps to validate the micromechanical analysis. Some standard methods in statistics are employed first to quantitatively examine the assumptions made when deriving the stress-force-fabric (SFF) equation. After careful validation, a more concise format for the SFF equation is proposed for triaxial compressions. With this SFF equation, the strength is found to be jointly contributed by the magnitudes of the contact force anisotropy and fabric anisotropy. The influence of the initial void ratio, confining pressure and loading direction on the development of contact force anisotropy and fabric anisotropy is examined and presented. With similar techniques, the “force” term in the SFF equation is further decoupled, and an equation is obtained such that it explicitly links the contact force term with the friction coefficient between grains, a tensor defined as a statistic of the normal contact forces and a tensor defined as a statistic of the mobilisation status of contacts. Based on this equation, another equation regarding the stress ratio of granular assembly is obtained, and it clearly indicates two sources that contribute to the phenomenological friction nature of granular assembly. These two sources are caused by the contact force at the grain scale. The first is the anisotropy of the average normal contact forces, and the second is the mobilisation of contacts.     

Discrete modeling of low-velocity penetration in sand

In this paper, a discrete particle method was evaluated and used in numerical simulations of low-velocity penetration in sand. Hemispherical, blunt, and ogival-nosed impactors were tested at striking velocities below 5 m/s. The tests were conducted in a dropped-object-rig where the resisting force from the sand was measured continuously during the experiments. This provided a basis for comparison for the simulations. The shapes of the force-penetration depth curves were different for the various impactors, but the ultimate penetration depths were similar in all tests that were done with the same impact velocity. Three-dimensional discrete particle simulations were generally capable of describing the behavior of the sand. However, the peak resisting force was underestimated, which led to a slight overestimation of the ultimate penetration depth. This discrete particle method has previously been evaluated at high impact velocities. The results presented in this study supplement past results and show that the method can also be used to describe the overall response of sand subjected to low-velocity penetration.     

Petrogenetic character and provenance of metabasalts in the aspiring and Torlesse Terranes, South Island, New Zealand: Implications for the gold endowment of the Otago Schist?

We report quantitative X-ray diffraction, whole-rock geochemical and Sm–Nd isotope data for metabasalts from the Aspiring and Torlesse Terranes in the South Island of New Zealand. These rocks underlie the Mesozoic metasedimentary Otago Schist which is anomalously enriched in gold and host to at least one world-class orogenic gold deposit at Macraes (> 125 t Au). Geochemical and Nd isotopic similarities between the samples point to a common history of the two terranes rather than the amalgamation of one or two allochthonous plate fragments. Furthermore, geochemical and Nd data suggest the metabasalts within both terranes formed in an oceanic but essentially non-subduction-related setting. The origin of the Aspiring and Torlesse basalts can be linked to the formation of an oceanic plateau that had resulted from a (?Permian) mantle plume initiation event proximal to a mid-oceanic rise or triple junction. Given the intrinsically gold-enriched nature of certain oceanic-character mafic rocks, the anomalous gold endowment of the Otago Schist may have been enhanced via the accretion and subduction of a gold-enriched oceanic plateau fragment. The metabasalts are generally enriched in gold (up to 13 ppb) compared to their enclosing metasedimentary rocks (typically ca. 1 ppb), with sulphide-rich metabasaltic rocks having up to 550 ppb Au. However, the relatively small volume of metabasalts in the Otago Schist precludes these rocks as the principal source for Otago Schist orogenic gold, with a primarily metasedimentary source of the gold potentially having a limiting effect on the overall endowment of the Otago Schist. This approach, that employs petrogenetic fingerprinting of potentially fertile source rocks for the assessment of gold endowment, might prove useful in the conceptual exploration targeting of relatively immature and poorly exposed terrains.