地理过程的时间性 ——关于地理教学中"点、线、面"问题的再认识

地理过程是地理学的重要概念,它是塑造地理景观格局的重要机制。作为地理过程的重要特征,时间性是厘清地理过程概念、把握地理过程走向的关键。地理过程的时间性包括作为某一地理过程在特定时间存在的特定状态的时间截面,由多个时间截面联结而成的时间脉络,以及在同一时间截面上由不同地理过程相互交织而成的时间叠置等三个方面。认识地理过程的时间性,是地理综合思维动态发展必不可少的内容。     

Mineralogical study of spinel-lherzolite inclusions from basalts in southern and eastern China

Ten spinel-lherzolite inclusions and one olivine-websterite inclusion, which were collected from Fujian, Jiangsu, Hebei and Yunnan Provinces, consist of olivine (FΦ_87.7–91.2), enstatite (En_87.3–89.7), Cr-diopside and spinel. According to the Mg/(Mg+Fe²⁺) ratios in the rocks and their mineralogies, they are designated to the Cr-diopside type. The websterite is composed of bronzite (En_71.9) and augite, while the gabbro-norite consists of hypersthene (En_68.9) and augite, belonging to the Al-augite type. The geothermos of spinel-lherzolites were calculated with four geothermometric methods, giving a temperature range of 925°–1,072°C. However, according to P. R. A. Wells' method, temperatures range from 845δ to 1,014°C, and by D. H. Lindsly's approach, from 716°–974°C. Pressures range from 15.1 to 19.8 kb. Genetically, Spinel-lherzolites and olivine-websterite are thought to have been derived from residual mantle material by partial melting at approximately 1,000°C and at a depth of about 50–70 km. Websterite and gabbro-norite may be products of the crystallization-differentiation of alkali basaltic magma.     

广清高速公路改扩建工程岩溶塌陷主要影响因素分析

岩溶塌陷对工程建设的影响不容小视。为了研究广清高速公路改扩建工程中影响岩溶塌陷的两个主要因素冲击荷载作用和地下水下降对塌陷的影响程度,在资料收集和现场调研的基础上,统计工程区12处岩溶塌陷的基本情况,总结塌陷特征并分析影响塌陷的主要因素,建立与实际覆盖层结构相符的塌陷地质模型-砂土+粉质黏土+灰岩地质模型。根据极限平衡理论,分别在冲击荷载和水位下降两种力学作用下对塌陷地质模型进行稳定性计算。通过计算得出,最大冲击荷载的作用在一定程度上会影响覆盖层的稳定性,但不是导致地面塌陷的主要因素,而地下水位下降对工程区岩溶塌陷起到了决定性的作用。通过进一步分析水位下降对塌陷的影响程度,确定水位降幅4m为警戒值, 6m为危险值,为保证施工的安全性提供一定的理论依据。     

矿山边坡稳定性研究的回顾与展望

本文阐述了露天矿边坡工程的特点, 回顾了露天矿边坡稳定性研究及其取得的理论成果和进展, 指出露天矿边坡稳定性研究的特点, 提出相应的研究技术路线与方法。     

对GPS接收机测试评估的探讨

随着GPS的广泛应用和GPS产业的迅速发展，GPS厂家众多，生产的接收机类型更是数以百计，整个GPS接收机市场可以说是鱼目混珠，识别困难；大多数购买者只能听信厂家的技术指标，如何对GPS接收机的性能进行测试评估的意义显得很重要，本文基于此对GPS接收机测试评估展开探讨和研究。     

东北冷涡南落型强对流天气的潜势预报分析

通过2005-2008年4-6月Micaps资料,查找500 hPa东北有冷涡,500 hPa和700 hPa江苏境内为大片的西北气流,当天午后到夜里出现强对流天气的若干典型个例,借助Micaps系统通过对一些个例的物理量资料分析,得出它们共同的发生强对流天气的机理;同时还分析得出诊断该类对流天气的不太适合使用的物理量和较适合使用的物理量;并分析个例的大气探空层结曲线,得出它们的对流层结与其它类型的区别,并剖析它们的一日转变情况;同时用Q矢量锋生函数方法分析,发现低层强锋生区域与强对流天气区域有较好的对应关系,锋生函数正值中心区域常出现个别站龙卷或大范围冰雹.     

二郎山公路隧道岩爆特征与预测研究

根据二郎山公路隧道施工中记录的200多次岩爆资料,总结隧道的岩爆特征,并采用"地质超前预报法"和"σθ/Rb判据现场测定预测法"两种方法,对岩爆预测问题进行有益探讨.     

Uncertainty analysis in statistical modeling of extreme hydrological events

With the increase of both magnitude and frequency of hydrological extreme events such as drought and flooding, the significance of adequately modeling hydrological extreme events is fully recognized. Estimation of extreme rainfall/flood for various return periods is of prime importance for hydrological design or risk assessment. However, due to knowledge and data limitation, uncertainty involved in extrapolating beyond available data is huge. In this paper, different sources of uncertainty in statistical modeling of extreme hydrological events are studied in a systematic way. This is done by focusing on several key uncertainty sources using three different case studies. The chosen case studies highlight a number of projects where there have been questions regarding the uncertainty in extreme rainfall/flood estimation. The results show that the uncertainty originated from the methodology is the largest and could be >40% for a return period of 200 years, while the uncertainty caused by ignoring the dependence among multiple hydrological variables seems the smallest. In the end, it is highly recommended that uncertainty in modeling extreme hydrological events be fully recognized and incorporated into a formal hydrological extreme analysis.