圆环试样内径对抗拉强度的影响

运用RFPA2D软件对岩石的单轴拉伸强度试验、不同内径的圆环试样的劈裂试验进行了模拟。比较模拟结果 ,重点研究了圆环试样内径对试件抗拉强度的影响 ,确定了最接近单轴拉伸试验结果内径的范围 ,利用回归分析确定了内径与试样抗拉强度之间的关系。     

P点铅及其应用意义

在铅同位素研究中，异常铅是经常遇到并难于解释的问题。在一个矿区或矿带范围内，某些矿床的铅同位素资料中往往显示存在两种类型的铅：具有单阶段演化历史的正常铅和具有两个(或多个)阶段演化历史的异常铅。在常规的铅同位素组成图解上，这两种铅的数据点有时构成异常铅等时线，正常铅则位于等时线上含放射性成因铅最低的位置处。如果这种正常铅能给出合理的矿化年龄，并且该年龄与容矿围岩的成岩年龄基本一致，但显著老于异常铅瞬间增长模式年龄，那么，这种正常铅可能是异常铅等时线的起点，笔者称其为P点铅。显然，异常铅是后期放射性成因铅加入到P点铅形成的，P点铅的模式年龄为异常铅来源区的年龄：利用P点铅及异常铅等时线的资料，可以计算获得异常铅的矿化年龄。因此，P点铅这个概念的提出，为探讨矿化年龄问题开辟了一条新途径。文章还以加拿大和北欧地区某些矿床的铅同位素资料为例，讨论了在实际成矿过程中是否有P点铅存在的问题，讨论了P点铅在矿床成因研究中的重要意义。并给出了如何判断P点铅的具体条件。     

西藏"一江两河"地区生态环境地质问题与防治对策

从生态环境地质的角度出发，指出西藏“一江两河”地区由于生态环境条件脆弱、生态系统的不稳定，在缺乏生态屏障保护下，对资源的大量开发利用、天然植被的大量掠取，诱发和加重了一系列重大生态环境地质问题；有针对性地提出了生态地质环境保护措施和防治对策，并提供了典型实例和经验。     

Multivariate statistical methods and GIS based evaluation of the health risk potential and water quality due to arsenic pollution in the Kızılırmak River

The K?z?l?rmak River is Turkey's longest (1,355 km) river and it is important since it constitutes the drinking and irrigation water source of the Central Anatolia Region. In the current study, the spatial distribution, effect on irrigation water quality, environmental pollution status, ecotoxicological and health risks as well as possible sources of 12 potential toxic elements' (PTEs) (manganese (Mn), aluminum (Al), arsenic (As), chromium (Cr), zinc (Zn), iron (Fe), nickel (Ni), cadmium (Cd), cobalt (Co), copper (Cu), mercury (Hg), and lead (Pb)) concentrations from surface water samples in the K?z?l?rmak River were analyzed by using geographical information systems (GIS) software, ecotoxicological indices, and multivariate statistical analysis. As a result of the current study, it was determined that the As concentration is above the World Health Organization (WHO) limit values, and, in terms of the 12 PTEs, there is slight heavy metal contamination in the river according to the Heavy Metal Pollution Index (HPI) and Heavy Metal Evaluation Index (HEI) values and there is a low level of pollution. The Hazard Quotient for ingestion (HQ_ingestion) and Hazard Index (HI) values indicate that non-carcinogenic effects may occur. Exposure to river water is likely to result in a low level of carcinogenic risk (CR) in adults, mainly due to the As concentration. The water at Sampling Station S3 (131.79) cannot be used for drinking and is not suitable for consumption. According to the sodium percentage (Na%), Sodium Absorption Ratio (SAR), and Magnesium Hazard (MH) index results, river water is suitable for agricultural use.     

一种基于关键点的轨迹-区域拓扑过程模型

定位技术的广泛应用带来了铺天盖地的移动数据,为诸如时空查询和数据挖掘等各种时空的研究及应用提供了重要素材,使得对于轨迹数据的研究成为当前的一个热点。当前,无论是对于原始轨迹数据的研究,还是对语义化轨迹数据的研究,都较少考虑轨迹移动过程中所潜藏的拓扑不变量。本文提出二维空间上基于关键点的轨迹-区域拓扑过程模型,以矩阵描述轨迹与区域的14种基本点集拓扑交叠类型,既而组织交叠序列描述轨迹和区域对象间的拓扑关联关系。模型不仅描述了轨迹与区域之间的拓扑不变量,而且结合轨迹特有行为的语义关联模型,描述轨迹相对区域的复杂拓扑过程。同时,本文还以模型中相邻两次交叠的相接交叠模式,探讨了区域间拓扑关系对于轨迹移动描述的约束。     

Properties of the Aftershock Sequences of the 2003 Bingöl, M D = 6.4, (Turkey) Earthquake

Aftershock sequences of the magnitude M _{W =}6.4 Bingöl earthquake of 1 May, 2003 (Turkey) are studied to analyze the spatial and temporal variability of seismicity parameters of the b value of the frequency-magnitude distribution and the p value describing the temporal decay rate of aftershocks. The catalog taken from the KOERI contains 516 events and one month’s time interval. The b value is found as 1.49 ± 0.07 with Mc =3.2. Considering the error limits, b value is very close to the maximum b value stated in the literature. This larger value may be caused by the paucity of the larger aftershocks with magnitude M _D ≥ 5.0. Also, the aftershock area is divided into four parts in order to detect the differences in b value and the changes illustrate the heterogeneity of the aftershock region. The p value is calculated as 0.86 ± 0.11, relatively small. This small p value may be a result of the slow decay rate of the aftershock activity and the small number of aftershocks. For the fitting of a suitable model and estimation of correct values of decay parameters, the sequence is also modeled as a background seismicty rate model. Constant background activity does not appear to be important during the first month of the Bingöl aftershock sequences and this result is coherent with an average estimation of pre-existing seismicity. The results show that usage of simple modified Omori law is reasonable for the analysis. The spatial variability in b value is between 1.2 and 1.8 and p value varies from 0.6 to 1.2. Although the physical interpretation of the spatial variability of these seismicity parameters is not straightforward, the variation of b and p values can be related to the stress and slip distribution after the mainshock, respectively. The lower b values are observed in the high stress regions and to a certain extent, the largest b values are related to Holocene alluvium. The larger p values are found in some part of the aftershock area although no slip occurred after the main shock and it is interpreted that this situation may be caused by the alluvium structure of the region. These results indicate that the spatial distribution in b and p values are generally related to the rupture mechanism and material properties of an aftershock area.     

广西雷电活动时间分布规律

依据广西1961-1998年88个气象台站资料,分析了广西雷电活动的年际变化、季节分布及日变化特征,得出了广西各地的雷电持续期.     

一次积层混合云降水实例的数值模拟分析

观测显示,积层混合云有自己独特的动力热力结构,降水过程也有自己的特点,但过去关于积层混合云的实例模拟工作较少.2007年9月28日在我国华北地区发生了一次积层混合云降水过程.利用WRF-ARW中尺度数值模式,对这一个例进行了实例模拟,并结合常规观测、卫星和雷达资料分析模拟结果,表明:此次积层混合云系是降水云系减弱,层状云发展形成的.在降水物理过程中,此次积层混合云不仅具有积云和层云形态混合的特征,还具有冷云过程和暖云过程共存的相态混合的特征;中层的大范围辐合和相应的较均匀上升气流场支撑着层状云,而在均匀上升气流场中的波动导致了对流云镶嵌其中;有迹象表明,条件对称不稳定是维持此次积层混合云发展的动力因子.     

城市人为热对北京热环境的影响

城市的人为热对城市热岛的产生有重要作用 ,通过对北京冬季的居民采暖排放废热、汽车排放废热和工业生产排放废热的估算 ,制定了考虑随时空变化的北京市人为热排放清单。利用北京大学城市边界层模式对北京冬季城市边界层结构特征进行模拟 ,通过考虑和忽略人为热的排放研究北京地面温度的变化 ,并通过几种方案减少人为热的排放对缓解城市热岛作用作出评价。     

有机插层蛭石对有机污染物苯酚和氯苯的吸附特性研究

分别应用溴化十六烷基三甲基溴化铵(HDTMA)和溴化十六烷基吡啶(HDPY)改性插层级石对苯酚和氮苯两种非离于型环境污染物进行吸附性能研究。结果表明，蛭石原矿对苯酚和氮苯的吸附能力很小，经表面活性剂处理后其吸附能力大大增强。有机插层级石对苯酚的吸附具有表面吸附特征，其吸附等沮线为Freundish型；而对氮苯的吸附实际上是氮苯在水相与有机级石中有机相之间的一种分配过程，其吸附等沮线为直线型。苯酚和氮苯的竞争吸附并末减弱有机蛭石对氯苯的吸附能力，反而由于它们同时存在产生协同效应，使有机插层蛭石对氯苯总的吸附能力有所提高。