Reduced-Dimensional Processing for Ground Moving Target Detection in Distributed Space-Based Radar

With multisatellite radar systems, several additional features are achieved: multistatic observation, interferometry, ground moving target indication (GMTI). In this letter, a new reduced-dimensional method based on joint pixels sum-difference (Sigma-Delta) data for clutter rejection and GMTI is proposed. The reduced-dimensional joint pixels Sigma-Delta data are obtained by the orthogonal projection of the joint pixels data of different synthetic aperture radar (SAR) images generated by a multisatellite radar system. In the sense of statistic expectation, the joint pixels Sigma-Delta data contain the common and different information among SAR images. Then, the objective of clutter cancellation and GMTI can be achieved by adaptive processing. Simulation results demonstrate the effectiveness and robustness of the proposed method even with clutter fluctuation and image coregistration errors     

In Situ Stress Measurement Method and its Application in Unconventional Oil and Gas Exploration and Development

<正>Unconventional oil and gas resources have become more and more important for meeting our increasing energy needs,for conventional petroleum resources are becoming depleted.During the exploration and     

晋东北地区燕山运动的基本特征——来自1∶25万应县幅区域地质调查的总结

晋东北地区燕山期地壳活动剧烈而频繁,经历了3次由伸展→挤压转换→隆升和岩浆活动过程。燕山运动早期形成早侏罗世断陷盆地和中侏罗世挤压坳陷型聚煤构造盆地;中期中晚侏罗世形成被NW、NE向深大断裂围限的火山断陷盆地,中基性—酸性火山喷发和浅成、超浅成中酸性岩浆侵入,晚侏罗世末形成了一系列NNE向褶皱和逆冲推覆构造带;晚期早白垩世再次形成断陷盆地和开阔平缓褶皱,义县组不整合在火山岩之上,晚白垩世处于挤压造山后的山体隆升阶段,左云组不整合在义县组之上,伴随有壳源型花岗岩侵入,NW、NE向断裂复活,形成地堑、地垒式断裂组合,导致山体隆升。     

黄土高原半干旱区异常能量闭合率特征分析

以兰州大学半干旱气候与环境观测站（简称SACOL站）4 a的陆面通量数据为基础,利用普通最小二乘法（OLS）和能量平衡比率（EBR）方法,对能量平衡的异常闭合特征及其与相对垂直湍强（RIw）的关系进行了研究,并进行了能量滞后分析。结果表明,能量过闭合和负闭合现象分别主要发生在白天和夜间,大小遵从正态分布;较大异常闭合产生的原因主要是日出日落时净辐射与地表热通量接近以及降水影响造成湍流通量出现异常大值。一般来说,垂直湍流运动越强,异常闭合越少,闭合度越向1收敛,反之亦然。强湍流或极弱湍流都不利于产生异常闭合,过闭合、负闭合的最适相对垂直湍强RIw约为0.11、0.14。另外,能量支出项的相对滞后也是造成包括负闭合在内的异常闭合的原因之一。剔除湍强较弱的点或将地表热通量G0、感热H、潜热LE相位相对净辐射Rn提前30 min后,异常闭合所占比重减少;月平均EBR法过闭合度降低,OLS法闭合度提高。     

塔里木盆地东北部中—上奥陶统沉积物源与构造背景相关性分析

基于塔里木盆地库鲁克塔格露头区却尔却克山、元宝山和南雅尔当山中—上奥陶统宏观沉积特征分析,结合钻井、地震资料分析,对盆地东北部巨厚的中—上奥陶统碎屑岩沉积物源及其构造背景相关性进行了探讨。中—上奥陶统却尔却克组发育复理石建造,综合重矿物组合、矿物成熟度参数、砂岩主、微量元素、稀土元素和阴极发光等提供的物源信息,反映物源区主要为大陆岛弧和活动大陆边缘构造背景。却尔却克组沉积早期物源区主要来自北部古陆,主要为酸性花岗岩类和变质岩类,却尔却克组沉积中后期,除来自北部的物源外,还有来自东南部阿尔金造山带的火山碎屑物质的加入。中—上奥陶统沉积物源分析为塔里木盆地东北部地区中晚奥陶世构造隆升与沉积充填关系研究提供重要依据。     

辽中地区矿业城市生态系统脆弱性研究

辽中地区矿业城市是中国重要的能源生产和重工业基地,研究其生态系统脆弱性有助于改善该区域环境恶化、生态系统失调的状况,为其可持续发展提供决策依据。基于矿业城市复合生态系统内涵,建立了辽中地区矿业脆弱性评价指标体系,提出生态系统协调度,并设定了其脆弱性和协调性分级标准。结果表明:2005年,辽中地区矿业城市生态系统脆弱性处于亚稳定状态,主要限制因子为资源匹配指数、环境质量指数和经济发展指数;辽中地区矿业城市生态系统间处于亚协调状态,其中本溪略低于亚协调,处于低度失调状态。鞍山的资源匹配指数处于较失调状态,抚顺、本溪的资源匹配指数处于失调状态,抚顺、本溪的经济发展指数处于较失调状态,是限制整个生态系统协调发展的主要原因。该评价模型较真实的反映了辽中地区矿业城市生态系统脆弱性、协调性状况,并且提出了制约其发展主要限制因子。     

Genesis of tuff interval and its uranium enrichment in Upper Triassic of Ordos Basin,NW China

Recently measured high gamma ray values in the Yanchang Formation of the Upper Triassic in the Ordos Basin have added an interesting and controversial twist to the study of the formation’s uranium enrichment and genesis. High uranium and thorium contents in the tuffaceous layer cause high gamma ray values in the Yanchang Formation. Petrographic studies, major elements, rare earth elements (REEs), and trace elements have been systematically analyzed to determine the composition, geochemical environment, and diagenetic processes of the layer. The observed color of the tuffaceous layer in the study area varies from yellow to yellowish brown. The tuff consists of matrix supported with sub-rounded to sub-angular lithic fragments. These lithic fragments probably derived from pre-existing rocks and incorporated into the tuffaceous layer during volcanic eruption. Quartz, plagioclase, and biotite were observed in well to poorly sorted form, in addition to framboidal pyrite and organic laminae. Measured ratios of SiO₂/Al₂O₃ ranged from 3.277 to 6.105 with an average of 3.738. The ratio of TiO₂/Al₂O₃ varied from 0.037 to 0.201 with an average of 0.061, indicating that the sediments of the tuffaceous layer originated from an intermediate magma. REE distribution patterns show sharp negative Eu anomalies, indicating a reducing environment, which is suitable for uranium deposition. A reducing environment was confirmed by black shale in the base of the Yanchang Formation. Such black shale has high organic matter content that can take kerogene from mudstone and provide a reducing environment for uranium enrichment in the tuffaceous layer. Moreover, negative Eu anomalies and the REE patterns indicate a subduction-related volcanic arc environment as the magma source of the tuffaceous layers. High values of Rb, Ba, and Sr might be the result of fluid phase activities; low values of Hf and Eu indicate the involvement of crustal material during diagenesis of the tuff. Discrimination diagrams (Th/Yb vs Ta/Yb, Th/Hf vs Ta/Hf) suggest an active continental margin as the tectonic setting of source volcanoes. Plots of Nb versus Y, Rb versus Y + Nb, TiO₂ versus Zr, and Th/Yb versus Nb/Yb of the tuffaceous content point to calc-alkaline continental arc-related magmatism. We concluded that uranium enrichment in the tuffaceous layer was supported by oxidation–reduction.     

大型桥梁钢沉井下沉过程局部冲刷研究

钢沉井下沉过程中局部冲刷的研究是同类桥墩设计和施工十分关心的重要课题,它对保证钢沉井安全有效施工、桥梁设计中施工期桥墩最大冲深、失稳和安全计算有重要参考价值。通过室内试验研究了钢沉井下沉过程中的局部冲刷机理和冲刷形态,探讨了桥墩下部钢沉井基础施工的相对高程对局部冲刷的变化规律,并将试验研究所获得的局部冲刷规律和影响因素,采用墩型系数方法引入局部冲刷计算中,给出了计算公式。研究成果补充了国家行业规范内容,对同类工程的设计、施工具有借鉴和指导意义。     

活性炭从硫脲浸出液中回收金的工艺研究

本文研究了在酸性硫脲浸出液中活性炭回收金的工艺过程,实验表明,在该浸出液中活性炭对金具有较高的吸附速度、吸附率和吸附容量并易于解吸,为工业应用提供了可靠的技术依据。     

Metallographic cooling rates and origin of IVA iron meteorites

We have determined the metallographic cooling rates for 13 IVA irons using the most recent and most accurate metallographic cooling rate model. Group IVA irons have cooling rates that vary from 6600 °C/Myr at the low-Ni end of the group to 100 °C/Myr at the high-Ni end of the group. This large cooling rate range is totally incompatible with cooling in a mantled core which should have a uniform cooling rate. Thermal and fractional crystallization models have been used to describe the cooling and solidification of the IVA asteroid. The thermal model indicates that a metallic body of 150 ± 50 km in radius with less than 1 km of silicate on the outside of the body has a range of cooling rates that match the metallographic cooling rates in IVA irons in the temperature range 700-400 °C where the Widmanstätten pattern formed. The fractional crystallization model for Ni with initial S contents between 3 and 9 wt% is consistent with the measured variation of cooling rate with bulk Ni and the thermal model. New models for impacts in the early solar system and the evolution of the primordial asteroid belt allow us to propose that the IVA irons crystallized and cooled in a metallic body that was derived from a differentiated protoplanet during a grazing impact. Other large magmatic iron groups, IIAB, IIIAB, and IVB, also show significant cooling rate ranges and are very likely to share a similar history.