未来20年印度资源需求预测及中国应对策略研究     

李晓明  王安建 《地球学报》2017,38(1):45-53

印度已经成为全球重要的国家之一。文章系统分析了印度的人口、经济发展特点,印度在过去发展过程中能源、铁、铜、铝资源的消费历史。并选用了合理的经济分析模型、资源需求预测方法,参考权威机构的研究成果,如资源需求"S"形规律、"GDP增速‘钟’形规律"以及格罗宁根研究中心(简称GGDC)、世界银行等机构的数据,科学、合理地预测了印度人口、经济及资源需求。认为:1)在工业化的带动下,印度经济具有再创神话的潜力;2)印度对能源、铁、铜、铝的需求将随着工业化进程的推进而快速上升,印度将成为继中国后拉动全球资源需求的"新引擎";3)印度发展不仅带给我国产业升级带来了新机遇,同时也是我国强有力的竞争者,比如在资源获取方面的竞争。因此我国企业应加强自身的核心竞争力,在印度发展的过程中获得好的机会成长。  相似文献   

Influences of the Helical Strake Cross-Section Shape on Vortex-Induced Vibrations Suppression for A Long Flexible Cylinder   总被引：2，自引：0，他引：2  

XU Wan-hai  LUAN Ying-sen  LIU Li-qin  WU Ying-xiang 《海洋工程》2017,31(4):438-446

An experimental study on a bare flexible cylinder as well as cylinders fitted with two types of cross-sectioned helical strakes was carried out in a towing tank. The main purpose of this paper is to investigate the effects of strakes’ cross-section on the vortex-induced vibrations (VIV) suppression of a flexible cylinder. The square-sectioned and round-sectioned helical strakes were selected in the experimental tests. The uniform current was generated by towing the cylinder models along the tank using a towing carriage. The Reynolds number was in the range of 800–16000. The strain responses were measured by the strain gages in cross-flow (CF) and in-line (IL) directions. A modal analysis method was adopted to obtain the displacement responses using the strain signals in different measurement positions. The comparison of the experimental results among the bare cylinder, square-sectioned straked cylinder and round-sectioned straked cylinder was performed. The helical strakes can effectively reduce the strain amplitude, displacement amplitude, response frequencies and dominant modes of a flexible cylinder excited by VIV. And the mean drag coefficients of straked cylinders were approximately consistent with each other. In addition, the square-sectioned and round-sectioned strakes nearly share the similar VIV reduction behaviors. Sometimes, the strakes with round-section represent more excellent effects on the VIV suppression of response frequency than those with square-section.  相似文献   

Experimental study on the hydraulic conductivity of calcareous sand in South China Sea     

Yin Wang  Yubin Ren  Qing Yang 《Marine Georesources & Geotechnology》2017,35(7):1037-1047

Characterization of the hydraulic property of a specific geomaterial is of fundamental importance in engineering design and application. This paper reports an experimental investigation to the hydraulic conductivity of a typical marine sand, i.e., calcareous sand, which becomes increasingly popular as sea-filling material for land reclamation or construction of artificial islands. A series of permeability tests have been performed using the calcareous sand collected from Nansha islands in South China Sea. Using the home-made permeability test apparatus (so-called velocity-controlled pressure-differential acquisition flow apparatus), the relationship between flow velocity and hydraulic gradient was obtained and the hydraulic conductivity of calcareous sand was then determined accordingly. The effects of important parameters, including particle shape and particle size distribution on the hydraulic conductivity of calcareous sand, were assessed. To investigate the effect of particle size distribution on the hydraulic conductivity of calcareous sand, two often-used parameters, i.e., nonuniformity coefficient and curvature coefficient were considered in this study. To quantitatively evaluate the irregularity of soil particle, a particle-shape parameter was introduced and it was able to consider sphericity and circularity of highly irregular particle. Two materials, namely, Fujian quartz sand and glass beads consisting of particles of characteristic shape, were also used in the permeability tests, and they were used to compare with calcareous sand. Through the comparison, the effect of particle shape of calcareous sand on its hydraulic conductivity was examined based on the newly introduced particle shape parameter. The test results indicate that the particle size distribution has a significant influence on the hydraulic conductivity of calcareous sand. The quite irregular particle shape is able to reduce the hydraulic conductivity of the calcareous sand. A comparative study of hydraulic conductivity between the theoretical prediction and experimental measurement was performed, and it is concluded that an improvement of theoretical model for prediction of the hydraulic conductivity of the porous media consisting of particles with highly irregular shapes, such as the calcareous sand, is still required.  相似文献   

水泥土结构特性的定量化研究   总被引：7，自引：2，他引：5  

顾明芬  刘松玉  洪振舜  于小军 《岩土力学》2005,26(11):1862-1865

采用电阻率测试技术,通过测试水泥土在强度增长以及压缩过程中的竖向、水平向电阻,探求水泥土在强度增长过程和压缩过程中电阻率特性参数--平均结构因子F、平均形状因子f以及各向异性系数A变化的基本规律,分析了F, f, A与水泥土物理力学特性之间的关系,证实了这3个参数能对土的结构性进行定量分析。  相似文献   

粤北贵东复式岩体的形成与重熔界面的形态演化   总被引：1，自引：1，他引：0       下载免费PDF全文

李宏卫  娄峰  陈光明  邱列  唐煜坤  杨燕娜  许冠军 《地学前缘》2011,18(1):39-48

根据花岗岩的“原地重熔 壳内对流”理论,对粤北贵东复式岩体的各种地质地球化学资料进行重新编码,证实该复式岩体的形成是该区陆壳中生代多次熔融(重熔)的结果,并在此基础上重建该区不同期次重熔界面形态。研究表明,早侏罗世重熔界面总体自南向北倾斜,因而在同一剥蚀面下,岩体自南向北依次出露中心相、过渡相、边缘相的岩性;晚侏罗世的熔融(重熔)事件基本局限于早期岩体内部,故该期岩体普遍比早期岩体偏酸性,本期岩浆界面自北向南倾斜。早白垩世的熔融(重熔)事件形成了石英正长岩和次英安斑岩两类不同的岩石,两者岩性的较大差异与卷入的源岩有关,本期的重熔界面同样自北向南倾斜,据此进行的隐伏矿床预测已经获得验证。  相似文献   

岩石单轴抗拉强度的几何形状效应研究     

李明田  茹忠亮  李术才 《岩土力学》2006,27(Z1):555-558

提出了一种模拟岩石破坏过程的细胞自动机模型,以力、位移作为基本状态变量,基于基本的力学规律构造了细胞自动机模型的矢量局部更新规则,克服了以往规则确定随意性以及标量化的缺点。利用该模型模拟了岩石的单轴破坏过程,研究了非均质性对单轴直接拉伸破坏过程的影响,并研究了几何形状（长宽比）对单轴拉伸强度的影响,研究结果加深了对岩石单轴抗拉强度的了解,对试验有一定的指导作用,应进一步加强岩石的直接拉伸试验研究。  相似文献   

地球质心偏移与各圈层形变     

杨学祥  王莉 《大地测量与地球动力学》1995,(4)

地幔结构的地震层析图象显示热心南偏和质心北偏可能是地球南北反对称的动力基础。建立了南北半球密度反对称分布的数学模型，计算结果表明：地壳地幔南北半球的密度不均匀分布可使地核偏离地球质心１～３公里，完全符合张焕志１９８２年的计算结果。质心偏移将造成地球各圈层相同数量级的等位移动与等位变形，从而产生大幅度的全球海平面变化和地壳形变。  相似文献   

SHAPE INDICES: USEFUL MEASURES OR RED HERRINGS?     

Daniel A. Griffith  Michael P. O'Neill  Wende A. O'Neill  Lloyd A. Leifer  Rodric G. Mooney 《The Professional geographer》1986,38(3):263-270

Considerable attention has been devoted to shape analysis in geography with few fruitful results. We ask whether or not shape analysis is worth pursuing, referring to papers by Griffith and Lo. The methodology utilizes a two-step procedure. First, Lo's analysis is reconstructed to include indices reported in Griffith. Second, findings from the investigations are compared. Similar results are obtained from both studies, but the failure to extract any one-to-one correspondence between a shape and its associated index value(s) continues to cast doubt on the utility for subsequent studies.  相似文献   

应用于面状地理实体聚类分析的线段链形状相似性准则   总被引：1，自引：0，他引：1  

杨春成  张清浦  田向春  何列松 《武汉大学学报(信息科学版)》2005,30(1):61-65

提出了一种满足旋转与平移不变性的线段链形状相似性评价方法。该方法计算简便，适用于面状地理实体聚类分析，并给出了该评价方法的实现算法，分析了参数对评价方法可能产生的影响及影响程度。  相似文献   

人工神经网络信息融合及其在机场识别中的应用研究   总被引：1，自引：0，他引：1  

马洪超  郭丽艳 《武汉大学学报(信息科学版)》2005,30(8):682-684,698,i0001

以机场识别为研究对象,以两种改进的BP网络作为算法工具,以TM影像作为原始数据,在特征级信息融合技术框架下进行机场识别研究。首先对可用于机场识别的特征进行分析,提出使用光谱特征、纹理特征和几何形状特征这三个特征的7维矢量作为BP网络的输入,并对BP网络的训练、测试和识别三个过程进行了详细的讨论。  相似文献