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941.
应用背景噪声层析成像方法对塔里木盆地及其邻区进行了研究.利用中国地震局数字地震台网和吉尔吉斯斯坦及哈萨克斯坦台网共74个地震台站记录的2009年1月至9月的连续地震数据,通过对台站对间的数据进行互相关处理获得Love波的经验格林函数,然后通过多次滤波分析和相位匹配处理得到每个台站对的8S到30 S的Love波相速度频散曲线.反演所得的Love波相速度图显示出明显的横向速度不均匀性,与研究区域主要地质结构和构造单元之间具有良好的相关性.由于较厚的沉积层,塔里木和准格尔盆地在周期8~30 S总体都表现为低速的特征,而山地区则表现为相对高速的特征.此外,塔里木盆地的东西和南北也显示出明显的横向速度不均匀性.东部的速度明显低于西部. 相似文献
942.
943.
944.
In recent summers, some natural lightning optical spectra and audible thunder signals were observed. Twelve events on 15 August
2008 are selected as samples since some synchronizing information about them are obtained, such as lightning optical spectra,
surface E-field changes, etc. By using digital filter and Fourier transform, thunder frequency spectra in observation location
have been calculated. Then the two main propagation effects, finite amplitude propagation and attenuation by air, are calculated.
Upon that we take the test thunder frequency spectra and work backward to recalculate the original frequency spectra near
generation location. Thunder frequency spectra and the frequency distribution varying with distance are researched. According
to the theories on plasma, the channel temperature and electron density are further calculated by transition parameters of
lines in lightning optical spectra. Pressure and the average ionization degree of each discharge channel are obtained by using
Saha equations, charge conservation equations and particle conservation equations. Moreover, the relationship between the
peak frequency of each thunder and channel parameters of the lightning is studied. 相似文献
945.
新疆准噶尔北缘乔夏哈拉铁铜金矿床成岩成矿时代 总被引:7,自引:0,他引:7
乔夏哈拉铁铜金矿位于新疆准噶尔北缘,矿体赋存于中泥盆统北塔山组第三岩性段凝灰质砂岩、粉砂岩、大理岩、凝灰岩、玄武岩及安山岩中。铁矿体呈似层状、扁豆状或透镜状,铜金矿体产于铁矿体内及铁矿体下盘的绿帘石蚀变岩中,空间上与矿区广泛出露的闪长玢岩密切相关。对矿区闪长玢岩中锆石LA-ICP-MS U-Pb年龄及绿帘石磁铁矿矿石、黄铜矿磁铁矿矿石中辉钼矿Re-Os年龄进行了研究,闪长玢岩的206Pb/238U加权平均年龄为(377.6±1.4)Ma(MSDW=0.20),4件样品的Re-Os同位素模式年龄为(377.7±5.9)383.1±5.4Ma,加权平均值为(380.1±2.7)Ma(MSDW=0.66),等时线年龄为(377.4±4.3)Ma(MSDW=0.36),表明乔夏哈拉铁铜金矿成矿时代与闪长玢岩侵入时代一致,均为中泥盆世晚期,矿床的形成与闪长玢岩有成因关系。辉钼矿样品的w(Re)为383.11 928μg/g,指示成矿物质主要来源于地幔,可能有地壳物质的加入。 相似文献
946.
包裹碎石桩是在碎石桩外包裹一层土工材料制成的一种新型桩体,由于包裹作用,碎石桩的刚度和抗剪强度得到了明显提高。然而,目前有关包裹碎石桩的研究较少,特别是其抗震性能方面。鉴于此,通过开展包裹碎石桩复合地基和碎石桩复合地基振动台模型试验,在考虑不同类型、幅值的地震波作用下,研究两种复合地基的加速度、桩土应力、破坏现象和位移,进而对比分析这两种复合地基的动力响应规律和抗震性能。试验表明:包裹碎石桩桩顶和桩间土水平方向加速度放大系数均约为碎石桩的2倍;相同地震波条件下,包裹碎石桩复合地基的峰值桩-土应力比约为碎石桩复合地基的3倍;与碎石桩复合地基相比,0.9g人工波加载后包裹碎石桩复合地基在较大区域内产生较窄裂缝;包裹碎石桩复合地基产生的总沉降较碎石桩复合地基减小了51%。因此,包裹碎石桩复合地基的抗震性能优于碎石桩复合地基。 相似文献
947.
The significance of biodiversity and ecosystem services are gradually recognized by human as an approach towards sustainability, so it is important to understand relationships and congruence between them to support conservation planning, especially in the hotspot areas with a prominent role in conservation. However, the management of most conservation hotspots mainly focused on biodiversity, and rarely concerned with ecosystem services. With the aim of proposing criteria for conservation strategies that contribute to the optimization of biodiversity and ecosystem services, in this study, a Geographic Information System(GIS)-based approach was designed to estimate and map the biodiversity and ecosystem services in Chongqing Municipality of China. Furthermore, the distributions of hotspot areas for biodiversity and ecosystem services were mapped based on the relationship between cumulative ecosystem services and areas. Finally the statistical analysis was processed focused on specific conservation objectives. The results showed that hotspot areas can conserve the most biodiversity but with the least ecosystem services under the conservation plans target to biodiversity conservation. In contrast, depending on the ecosystem services of interest, hotspot areas can conserve the largest ecosystem services but with the least biodiversity. By integrating biodiversity and ecosystem services into conservation plan, we found that the conservation and regeneration of these small areas, would contribute to a conservation of 44% of the biodiversity hotspot and 14%–42% of the ecosystem services hotspot. Moreover, the current nature reserve selection was not maximize the biodiversity and ecosystem services compared to integration strategy, indicating that hotspot areas conservation and selection is vital for optimization protection of biodiversity and ecosystem services, and has practical significance for natural resources and ecosystem management. 相似文献
948.
Changes in ecosystem service of soil conservation between 2000 and 2010 and its driving factors in southwestern China 总被引:2,自引:0,他引:2
Human activities significantly alter ecosystems and their services; however, quantifying the impact of human activities on ecosystems has been a great challenge in ecosystem management. We used the Universal Soil Loss Equation and county-level socioeconomic data to assess the changes in the ecosystem service of soil conservation between 2000 and 2010, and to analyze its spatial characteristics and driving factors in the southwestern China. The results showed that cropland in the southwestern China decreased by 3.74%, while urban land, forest, and grassland areas increased by 46.78%, 0.86%, and 1.12%, respectively. The soil conservation increased by 1.88 × 10~(11) kg, with deterioration only in some local areas. The improved and the degraded areas accounted for 6.41% and 2.44% of the total land area, respectively. Implementation of the Sloping Land Conversion Program and urbanization explained 57.80% and 23.90% of the variation in the soil conservation change, respectively, and were found to be the main factors enhancing soil conservation. The 2008 Wenchuan earthquake was one of the factors that led to the degradation of soil conservation. Furthermore, industrial adjustment, by increasing shares of Industry and Service and reducing those of Agriculture, has also promoted soil conservation. Our results quantitatively showed and emphasized the contributions to soil conservation improvement made by implementing ecological restoration programs and promoting urbanization. Consequently, these results provide basic information to improve our understanding of the effects of ecological restoration programs, and help guide future sustainable urban development and regional industrial restructuring. 相似文献
949.
核工业地质分析测试研究中心于2012年8月组织有关实验室进行了"BRIUG IC-2012铀矿地质样品成分分析实验室间比对"活动。本实验室在低本底铅室内用HPGeγ谱仪对5个样品进行了测量,通过相对比较法给出了各样品放射性核素238 U、232 Th、226 Ra、40 K的含量。比对结果仅Albriug-4样品的40 K测量值不满意,其他均为满意。对该次比对测量中存在的问题进行了初步分析和讨论,认为Albriug-4样品的测量值偏高是核素228 Ac的1459.2keV的特征峰干扰所致,测量值经干扰校正后,结果令人满意。而样品Albriug-1的232 Th测试项目给出的结果虽然为满意,但本实验室结果24.0μg/g与中位值49.3μg/g的偏差很大,认为可能是样品的钍系不平衡所致。 相似文献
950.
为了准确掌握翡翠原石的放射性水平,消除公众对珠宝玉石存在放射性的疑虑,本文选取了3种翡翠原石的10件样品,利用高纯锗型(HPGe)低本底多道γ能谱仪测量了样品中天然放射性核素226Ra、232Th和40K的比活度值.结果表明,样品中有关核素的比活度值低于或仅略高于仪器检测限,样品的内照指数(IRa)和外照指数(Iγ)均远远低于国家对建筑材料中放射性核素的限量规定,说明翡翠原石的放射性水平很低,与环境的天然本底相当,不存在所谓的放射性危害. 相似文献