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排序方式: 共有9195条查询结果,搜索用时 15 毫秒
1.
遥感筛选评价区化异常的初步探索 总被引:1,自引:0,他引:1
近年来,作者发展了七种以上重要找矿指示元素的野外快速分析法,此乃其一。文中提出一种新的金样冷浸技术,引进了新的光导光度检测方法,样品经溴化钠—硫酸—过氧化氢冷浸,用经丙酮—MIBK处理的泡沫塑料富集金,经混合解脱剂解脱并直接取解脱液用改进的微珠析出法或用光导光度法测定。取10g样品,可测定0.0005- 50g/t范围内的金。方法简便、快速,可在普查分队驻地进行,每一工作日可测定80多个样品,由于废弃了王水分解样品和泡沫塑料的灰化,具有广阔的应用前景。 相似文献
2.
Chuanbo Zhou Shiwei Lu Nan Jiang Dingbang Zhang Zhihua Zhang Gaojian Miao 《Geotechnical and Geological Engineering》2016,34(3):847-866
In Daye Iron Mine, the open-pit mining has ended and the underground mining started in 2003. The present pit slopes are as high as 430 m and the slope angle is up to 43°. During the process of open-pit to underground mining, the high-steep pit slopes would be affected by both open-pit mining and underground mining, and its deformation characteristics would become more complex. So in this paper, the trinity method of numerical simulation, model experiment and field test was adopted to analyze the displacement and stress fields systematically. The results show that: (1) Prominent rebound deformation occurs near the slope foot, which is induced by the unloading in open-pit mining. When it is backfilled to 0 m level, the rebound deformation decreases, which indicate that backfilling mass can restrict the deformation and improve the slope stability; (2) Subsidence dominates the slope deformation in open-pit to underground mining and it increases with an increasing elevation of monitoring point; the maximum horizontal displacement occurs in the lower part of the slopes, because the backfilled part is squeezed by both the north slope and the south slope, and it has a lower elastic modulus than the previous orebody; (3) The stress and its variability near the slope foot are much larger than other places, indicating that the slope foot is most affected by stress redistribution and stress concentration may occur here; the stress at other stress monitoring points changes little, indicating that the influence of open-pit to underground mining is local; (4) The effect of underground mining on the deformation of the faults is not prominent; (5) Mining operations in near-ground part affect more on the variation of deformation and stress of pit slopes than that in deeper part. 相似文献
3.
The temporal and spatial characteristics of the surface air temperature variations over the Antarctic and its surrounding area 总被引:1,自引:0,他引:1
The characteristics of the spatial distribution, temporal variations trend and oscillation for the surface air temperature
variations during 1957—1993 in the Antarctic and its surrounding area were analyzed. The results show that the short-time
climate change in the Antarctic is complex both temporally and spatially. The Antarctic is by no means the strongest responding
region to the global greenhouse effect. There is a distinguished difference in the trends of the temperature changes for the
Antarctic and global mean, which could not be explained simply by the global greenhouse effect.
Project supported by the National Antarctic Key Project of China (85-905). 相似文献
4.
5.
降水粒子特性是大气运动和云内微物理过程的综合结果,在云降水物理及人工影响天气领域有着重要的意义。传统的测量方法不适合对大量数据分析寻找规律,德国OTT公司的Parsivel激光降水粒子谱测量系统可以较好解决自动测量难题。该仪器是以激光测量为基础的粒子测量传感器,采用平行激光束和光电管阵列结合,当有降水粒子穿越采样空间时,自动记录遮挡物的宽度,通过穿越时间计算降水粒子的尺度和速度,根据各种参数的综合信息对降水粒子进行分类,并能够以数字形式显示瞬时降水强度、降水粒子总数、累积降水量、降水时的能见度和雷达反射因子,以图形方式显示降水粒子尺度谱、速度谱、降水粒子分类且自动生成天气现象代码,实现天气现象的自动识别。激光降水粒子谱仪主要用于气象水文观测。在雷达气象学领域可用于Z/R关系的拟合修正,比传统的用雨量筒观测数据拟合效果好得多;由降水粒子谱仪测量雨滴的降落速度,可以对天气雷达垂直向上测量的粒子径向速度谱进行校正。人工影响天气的效果检验一直是一个难题,自然降水粒子谱分布形式与人工催化以后的降水粒子谱型理论上应当具有较大的差别,人工增雨作业降水滴谱变化物理响应和降水强度时间变化响应都有明显的区别。如果能够实时检测到这些差别,就能够充分说明人工催化的有效性。未来如果能够进行联网观测记录区域性降水、降雹,就有充分证据表明人影作业的有效性,在定量化作业效果评估以及灾害损失评估等方面应用潜力巨大。利用该仪器已经对一年的自然降水过程进行了连续观测,并将所获得的降水粒子谱、雨滴浓度值随时间变化状况与卫星反演的云顶有效粒子半径时间变化趋势进行了对比,发现有较好的一致性。 相似文献
6.
7.
Hong-Di He Wei-Zhen Lu 《Stochastic Environmental Research and Risk Assessment (SERRA)》2012,26(8):1053-1061
This paper reports an investigation on the periodic variation of pollutant levels at a typical traffic intersection of Hong Kong. Carbon monoxide, carbon dioxide and particulate matters (PM x ) were measured respectively and the measured data show periodic variations with the traffic signal intervals. The power spectral density (PSD) approach was used to inspect the trends and periodic oscillations of measured pollutants. Singular spectrum analysis was applied to decompose the measured data into statistically significant non-linear trends and oscillations in the process. From the results, most of the trends tend to increase due to the upcoming rush hour during the experiment. In addition, all the oscillations changed regularly with a period of 136?s, which is coincident with the traffic signal period and the frequency calculated by using PSD. The trends, together with the oscillations, collectively explain the most percentage of the variability of the data in the time series and provide the principal components of the data in understanding the periodic variation of the pollutant concentration. It can be deduced that vehicle emission is the major contributor to the air pollution in downtown area and pedestrians should be more alerted when crossing the busy traffic intersections. 相似文献
8.
高精度的数字地图是正确匹配车辆位置的基础。详细分析了地图数据的地理误差和拓扑误差的误差形式,路网数据模型的常见误差因素和改进策略,最后介绍了不同地图匹配算法对地图质量的敏感性和可行性。根据可能出现的误差对现有数字地图和匹配算法加以改进,弥补了原有数字地图带来的不精确缺陷。跑车实验证明,考虑了数字地图误差影响的匹配算法可以明显提高定位精度,减小车辆定位误差。 相似文献
9.
根据1951-2010年珠江流域23个典型断面流量资料,用P-III型分布曲线拟合洪水系列进行频率计算,分析了珠江流域极端洪水事件的变化趋势。结果表明:1980年以来,珠江流域极端洪水事件发生的频次明显增加,尤其是自1990年以来增加趋势显著;1981-2010年较1951-1980年珠江流域约70%典型断面极端洪水事件呈增加趋势,主要分布在西江、北江、粤西;而近30%的典型断面呈减少趋势,主要分布在东江和桂南。 相似文献
10.
Lijuan HUA Lin CHEN Xinyao RONG Jian LI Guo ZHANG Lu WANG 《Journal of Meteorological Research》2019,(1)
We present an overview of the El Ni?o–Southern Oscillation(ENSO) stability simulation using the Chinese Academy of Meteorological Sciences climate system model(CAMS-CSM). The ENSO stability was quantified based on the Bjerknes(BJ) stability index. Generally speaking, CAMS-CSM has the capacity of reasonably representing the BJ index and ENSO-related air–sea feedback processes. The major simulation biases exist in the underestimated thermodynamic damping and thermocline feedbacks. Further diagnostic analysis reveals that the underestimated thermodynamic feedback is due to the underestimation of the shortwave radiation feedback, which arises from the cold bias in mean sea surface temperature(SST) over central–eastern equatorial Pacific(CEEP). The underestimated thermocline feedback is attributed to the weakened mean upwelling and weakened wind–SST feedback(μ_a) in the model simulation compared to observation. We found that the weakened μ_a is also due to the cold mean SST over the CEEP.The study highlights the essential role of reasonably representing the climatological mean state in ENSO simulations. 相似文献