科尔沁沙地沙丘-草甸相间地土壤颗粒的分形特征

选择科尔沁沙地典型沙丘-草甸相间地为研究区,利用土壤颗粒的体积分形模型计算了研究区49个采样点土壤颗粒的分形维数,并建立了分形维数与土壤颗粒不同粒级间的相关关系,以探讨半干旱寒冷地区土壤颗粒的分形特征与土壤物理性质以及养分含量之间的关系。结果表明:(1)研究区土壤颗粒的分形维数为1.33~2.50,变幅较大,且呈现出自中部的草甸、农田地带向南、北方向的沙丘地带递减的趋势;土壤颗粒的体积分形维数依照流动沙丘-半流动半固定沙丘-固定沙丘-农田-草甸的顺序而递增。(2)土壤颗粒的分形维数与黏粒、粉粒含量显著正相关,与砂粒含量显著负相关,且表现出明显的对数关系。100 μm是影响土壤颗粒分形维数变化的分界粒径,大于该粒径的颗粒含量越高,土壤颗粒的分形维数越小;反之越大。(3)分形维数与土壤养分含量相关显著,土壤颗粒的分形维数与电导率、pH值及有机质、全氮、全磷含量均显著正相关,但与全钾含量负相关。在分形维数大于2时,基本与土壤饱和含水率正相关、与干容重负相关。     

Experimental study on the settlement of marine deposits of Anzali under cyclic loading by laminar box apparatus

The central Alborz mountain range, located in northern Iran, neighboring the Caspian Sea and where the two Persia and Eurasia plates meet, is known as a seismologically active area. In this regard, investigation of the behavior of saturated sand deposits located in this area may be of particular interest. Saturated sand deposits are subjected to instabilities owing to liquefaction or volume change due to earthquake shakings. A particular type of saturated sand deposits is Anzali sand which is abundant in Anzali port and other cities located in this area in northern Iran. This type of sand is a representative for most sands found in this area, i.e., the southern coastal line of Caspian Sea. This research is solely focused on the volume change behavior of marine deposits of Anzali area, often characterized as Anzali sand, in terms of the settlement of a model footing located on the surface of the sand by the aid of a transparent laminar shear box apparatus. Effects of a number of factors such as the frequency of the cyclic loading, the initial density of the sand, and the sample preparation method have been investigated. Observations indicated that the density index and the frequency of loading which are proportional to the energy of an earthquake have direct effects on the accumulation and amount of the final settlement of Anzali sand.     

Evaluation of compression index of marine fine-grained soils by the use of index tests

Marine fine-grained soils are well known for their compressibility, which is typically measured and reported in terms of compression index, C_c. The difficulties associated with measuring C_c have resulted in growing research interest in statistics-based estimates (i.e., correlation equations). Although many empirical and semiempirical correlations exist for estimating C_c, most available correlations are based on either data from nonmarine soils or data collected from Japanese and Korean marine clays. Thus, there are few correlations for marine clays from other parts of the world. In the present study, two independent databases which contain a total of 1,000 data points from 170 different sites worldwide are used to build and validate statistically significant correlations for estimating compression index of marine soils. The results of this study suggest that (1) the proposed correlation equations provide quite good estimates of C_c for marine soils with different stress histories and sensitivities and (2) most of the existing models have unacceptable performance when they are applied to marine soils.     

自然地理学案例教学的实施策略

案例教学在培养学生能力方面具有独特的作用,案例教学的实施需要有科学的策略,策略是案例教学的生命。文章以案例教学在自然地理教学中的应用为研究载体,阐述了自然地理案例教学中存在的问题,论述了自然地理案例教学的实施策略,介绍了案例教学在自然地理教学中应用的实例。     

基于GIS的物流配送路径优化算法

在单点到多点的配送中,一般的路径选择算法通常仅把"时间最短"作为约束条件来进行路径选择,这通常会导致参与配送点的数量过多。探讨了基于地理信息系统技术的物流配送路径优化算法,提出了基于模糊数学理论,以"参与配送点最少"为约束条件并同时考虑配送时间的"模糊权衡算法"。实验表明,模糊权衡算法可以在时间耗费和参与点的数量之间达到一个相对较优解。     

Enhancing Diversity In The Geosciences

Abstract

An innovative interdisciplinary project at California State University, Long Beach, was designed to increase the attractiveness of the geosciences (physical geography, geology, and archaeology) to underrepresented groups. The goal was to raise awareness of the geosciences by providing summer research opportunities for underrepresented high school and community college students and their faculty. A survey of a larger sample provided insight into strategies for enhancing geoscience awareness. A qualitative evaluation pointed to its success in meeting project goals. This unprecedented level of collaboration has set the groundwork for an institutional shift for inclusion of minorities in the geosciences and warrants replication.     

增长模在热带地区发展的分析研究

利用T63L9全球谱模式对制作集合预报的增长模繁殖法(BGM)在热带地区的适用性进行研究,分析了在热带地区扰动增长的机理。设计与物理过程、积云对流参数化方案及湿物理过程有关的3个敏感性试验及1个控制试验。为了讨论不同物理过程对BGM生成扰动的影响,定义扰动动能变化率对试验结果进行分析。结果表明:在热带地区积云对流强盛区内风场扰动能够快速增长。扰动增长机制在热带地区与中高纬地区有本质区别,热带地区扰动的发展主要受物理过程的作用,其中模式积云对流及湿物理过程对扰动中快速增长的部分起着至关重要的作用。中高纬地区扰动发展与背景场的斜压不稳定有关。     

Study on the physical properties and chemical compositions of artificially synthesized coral hydroxyl apatite （CHA） bone

Abstract  

To develop synthesized coralline hydroxyl apatite (CHA) bone graft-substitute and measure its physical and chemical characteristics.     

地球物理场曲面特征线计算与场源特征识别

平面上的点及该点对应的场源信息构成了一个三维曲面,谷特征线和峰特征线是控制曲面形态的重要因素,对曲面谷特征线和峰特征线二类曲面结构线的提取,有助于场源信息的自动提取和识别。这里给出了这二类特征线的求取过程,简要分析了其对应的地质地球物理意义,并通过一个模型和实例计算说明了特征线在异常识别上的效果。     

激电测量在莱西市山后金矿区萌山矿段的应用

激电测量为寻找隐伏金矿的有效地球物理手段。通过在招平断裂带上山后矿区萌山矿段的成功运用,建立了激电测量在招平断裂带上山后矿区萌山矿段寻找隐伏矿资料解译模型,运用找矿模型对深部隐伏矿体是否存在进行判定,取得了良好的地质效果。