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21.
在分析地表沉陷基本规律的基础上,依据弹性薄板理论,建立非充分采动条件下岩层和地表沉陷预计的一类新模型,并推导出地表任意点倾斜、曲率、水平移动以及水平变形的计算公式。该模型充分考虑到地质采矿因素(煤层倾角)及煤层上方各岩层的影响,克服传统预测方法的缺陷,特别是概率积分法关于拐点反对称要求。最后,应用实例证明该方法的应用效果。 相似文献
22.
基于支持向量机的CBERS-02卫星影像信息提取 总被引:1,自引:0,他引:1
CBERS卫星是由中国空间技术研究院与巴西空间研究院联合研制的地球资源遥感卫星,CBERS-02卫星数据总体质量比CBERS-01卫星有所提高,本文利用支持向量机方法对CBERS-02卫星影像信息进行提取。研究中首先用6S模式对影像进行大气校正,然后选择RBF为支持向量机方法的核函数,并用交叉验证方法得到影响RBF核函数的两个最佳参数值进行学习完成信息提取,最后将提取结果制作成矢量图。通过研究得出用大气校正后的数据进行信息提取分类精度有所提高;与最大似然法和最小距离法相比,支持向量机方法分类精度较高。通过将研究结果与ETM+影像进行比较得出,CBERS-02卫星影像精度能够满足应用需求并能代替TM/ETM+数据开展研究工作。 相似文献
23.
24.
成矿信息的提取是矿产预测的重要手段,其方法的有效性直接影响到预测成果的可靠性。在成矿规律研究的基础上,有意识地干预模型的构成,突出与成矿有关的信息;抑制某些成矿意义不明显和属干扰的信息,有目的地使模型向反映成矿信息的方向逼近,提高模型与矿床实际赋存地质环境的吻合程度,均是成矿信息提取和强化的内涵。本文从研究实践中总结了先验约束模型和非先验约束模型的强化方法,在新疆阿勒泰地区的地质-找矿工作中已取得 相似文献
26.
The limitations of pulp chemistry measurements in the flotation of a platinum group mineral (PGM) bearing Merensky ore were demonstrated in Part 1 of this article. In this paper the importance of the contribution of the froth structure due to changing froth stability is analysed using the batch flotation data. The effects of mild steel (MS) and stainless steel (SS) milling media and the addition of copper sulphate on the flotation performance of the sulphide minerals in Merensky ore have been evaluated in relation to the changes in stability of the froth phase. The effects of pulp chemistry and froth stability on the flotation of sulphide minerals were distinguished by using two different rate constants (kt and kw). The rate constant (kw) calculated as a function of cumulative water recovery was used to describe characteristics of froth phase and kt was calculated as a function of flotation time. The results revealed that the type of grinding media and copper sulphate addition had an interactive effect on the froth stability. While mild steel (MS) milling increased the froth stability due to the presence of hydrophilic iron hydroxides and colloidal metallic iron, the addition of copper sulphate reduced the stability, especially with stainless steel (SS) milling. Copper sulphate addition had a dual role in the flotation of Merensky ore in that it caused destabilisation of the froth zone as well as activation of selected sulphide minerals. The dominant effect was found to depend on the type of milling media and floatability of the mineral in question and this work has demonstrated the importance of using a combination of measurements to evaluate flotation performance holistically. 相似文献
27.
Mohammad Rasul Jan Mahmood A Khawaja Jasmin Sha Kashif Gul 《中国地球化学学报》2006,25(B08):182-182
Due to the persistent nature of DDT, a persistent organic pollutant and its adverse environmental and health impacts, the present study was undertaken to examine the residual DDT in and around DDT manufacturing factory in Amman Gharh, Nowshera, NWFP. The factory was established in 1963 and remained in operation till 1994. Composite samples of soil, sediments and water were collected in and around the factory area, nearby DDT stores, main factory drain leading to river and nearby villages. Standard procedures were used for the collection, transportation and storage of samples for analysis. Physical parameters for the collected water samples measured were temperature, pH and conductance. Extraction of each sample for DDT analyses was carried out in triplicates using soxhlet extraction apparatus. The extract was transferred to well washed, clean; dry glass vial, sealed and put in the refrigerator. Gas Chromatograph with electron capture detector and capillary column was used for analysis. DDT in the samples was identified on the basis of their retention time and quantified on the basis of peak areas. It is evident from the analytical data obtained in the present study that both water and soil in and around the factory area are still contaminated with DDT, despite the closure of the factory since the past few years. 相似文献
28.
Rama Mohan Kurakalva Narasimha Murthy Nyasavajhala Phani Homeshwari Mamidi Venkata Anjaiah Kanukuntla 《中国地球化学学报》2006,25(B08):202-203
A simple and rapid procedure to extract organochlorine pesticides (OCPs) from sediments by means of microwave energy is proposed. Sediment samples were irradiated with microwaves in a closed vessel system while immersed in hexane-acetone (1 : 1, v/v). The sample extracts were cleaned up using solid phase extraction with Florisil as adsorbent. Pesticides were eluted with hexane-ethyl acetate (80 : 20, v/v) and determined by gas chromatographic separation with electron capture detection. Three oven programs were assayed with two different solvent mixtures in order to achieve adequate experimental conditions for the complete extraction of organochlorine pesticides from the matrix. Different variables such as the composition of extraction solvent, 相似文献
29.
Yaping WANG Chunxue XU Ziyi AN Suming WANG 《中国地球化学学报》2006,25(B08):205-205
Different species of one element have different activities, so it has different effects on environment and human health. To analyze qualitatively and quantitatively the speciation of a special element in sample, which is the important basis for appraising the toxicity and studying the rule of transfer and translation of elements. Since the 1970's, the scheme of sequential extraction has already been used at many laboratories both at home and abroard, to get the information about heavy metals' activity in polluted soils. Because this method has the experimental nature, many schemes of problem has taken place, the absence of consistency of these sequential extraction have been formed. Thus the complexity of the schemes, the lack of selectivity of reagent, the lack of quality control, the result mainly related to the extraction scheme used, and so on. In the face of these problems, the study of experimental methods of sequential extraction on three different soils, sediment in Dongting Lake, soil in Jiangsu Province and loess in Shanxi Province was made. Reference materials of heavy metal speciation following sequential extraction in soil and sediment had been developed. Nowadays two kinds of sequential extraction methods which are widely used are BCR (three steps) and improved Tessier methods (seven steps). Based on three steps of BCR, water-soluble speciation and the residual speciation were increased in our research. BCR701 was determined eight times at different laboratories using BCR three steps. The results showed that determined data obtained eight times were identical to the standard value, and it is indicated that this method has good reproducibility. The stability and homogeneity experiments indicated that the preparation of three types of candidates accorded with our requirements. Eight laboratories had afforded the determined values of 12 heavy metal elements (Cu, Pb, Zn, Mn, Co, Ni, Cd, Cr, Mo, As, Sb, Hg, Se et al.) using BCR three steps. Also, these three candidates afforded the determined values by seven steps, and 12 laboratories had participated. 相似文献
30.
Leonard Boszke Artur Kowalski Witold Szczuciński Grzegorz Rachlewicz Stanisław Lorenc Jerzy Siepak 《Environmental Geology》2006,51(4):527-536
The 26 December 2004 tsunami covered significant portion of a coastal zone with a blanket of potentially contaminated sediments. In this report are presented results on mercury concentrations in sediments deposited by the tsunami in a coastal zone of Thailand. Since the total mercury concentrations are insufficient to assess mercury mobility and bioavailability in sediment, its fractionation was applied. Sediments were sampled within 50 days after the event and analyzed by sequential extraction method. The procedure of sequential extraction involved five subsequent stages performed with solutions of chloroform, deionized water, 0.5 M HCl, 0.2 M NaOH, and aqua regia. The mean concentration of total mercury in sediments was 119 ± 50 ng g−1 dry mass (range 66–230). The fractionation revealed that mercury is mainly bound to the least bioavailable sulphides 75 ± 6% (range 62–86), organomercury compounds 14 ± 7% (range 4–26), and humic matter 9 ± 7% (range 1–27). The lowest contributions bring fractions of water-soluble mercury 0.8 ± 1.0% (range 0.1–3.6) and acid soluble mercury 0.9 ± 0.5% (range 0.2–2.1). Although, the total mercury content is similar in a reference sample and in the tsunami sediments, the highly toxic organomercury fraction contribution is higher in the latter. The results were compared with chemical and sedimentological properties of the sediments but no significant correlations were obtained between them. 相似文献