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71.
为检测和区分极化遥感SAR图像中的非平稳目标,讨论了极化SAR图像中两种非平稳目标的检测和区分方法。用极大似然比对固定朝向非平稳目标进行检测,用变化系数对周期表面非平稳目标进行检测。仿真结果表明,两种方法分别能把两种非平稳目标检测出来。  相似文献   
72.
基于能量耗散理论建立非均质岩石的动态损伤破坏元胞自动机,分析单轴压缩试验中岩石破坏截面的损伤状态,得到该情况下的岩石裂隙微观动态发展过程、损伤演化关系以及全程应力应变曲线。研究发现:①加载过程中,均质度较低的岩样裂纹的萌生和扩展较为分散,损伤速率低;均质度较高的岩样裂纹的萌生和扩展非常集中,表现为脆性破坏。②损伤演化曲线呈3阶段S形发展。③随着岩石均质度参数的增加,岩石的峰值强度和峰值应变都有所提高,峰后曲线越来越陡。④给出的衡量岩石脆性破坏强弱程度的指标参数,能够较好地描述岩石破坏形式随着均值度参数m变化的规律。  相似文献   
73.
A nonlinear hybrid method is developed for multiscale analysis of a bearing-capacity test of a real-scale segmental tunnel ring subjected to point loads. The structural analysis consists of two parts. Part I refers to modeling of bending-induced tensile cracking of the segments, resulting from the external loading. The segments are subdivided into elements, according to the crack spacing. Each element is either intact or contains one central crack band, flanked by lateral undamaged domains. A multiscale model for tensile softening of concrete is used to describe the progressive deterioration of the crack bands. After iterative determination of their state of damage, the effective bending and extensional stiffnesses of the corresponding elements are quantified by means of Voigt-Reuss-Hill estimates. The effective stiffnesses are used for linear-elastic simulations of the segmental tunnel ring. Part II refers to the relative rotation angles at the joints, which are estimated from monitoring data, using the Bernoulli-Euler hypothesis. Since the validity of this hypothesis is questionable for neck-like joints, the relative rotation angles are post-processed such that they refer to rigid body displacements of the segments. The following conclusions are drawn: The presented approach yields good estimates of crack widths. Relative rotation angles at the joints mainly result in rigid body displacements of the segments, governing the convergences. Because realistic interface models are lacking, hybrid analysis based on displacement-monitoring data allows for performing ultimate-load analysis of segmental tunnel rings.  相似文献   
74.
根据长株潭城市群核心区水文地质条件及地下水资源特征,结合城市供水现状圈定了19个地下水应急水源地,针对2020年规划的长株潭三市城市人口,按照20L/d·人和50L/d·人的标准,分别对各城市进行了应急供水方案研究,并提出了城市应急水源地建设与保护建议。  相似文献   
75.
刘鹏  郑建华等 《地球科学》2003,28(2):163-166
采用共沉淀法合成了含有金属铟离子的碳酸根型水滑石,研究了沉淀方式、温度、pH值、老化时间和镁铝铟摩尔比这些对镁铝铟类水滑石(Mg-Al-In HTlc)的纯度和结晶度有影响的合成条件。通过XRD及IR表征,结果表明以恒定pH值的高过饱和沉淀法,控制其沉淀和老化温度在65℃、洗涤温度为室温,pH值为10-11.5,老化时间为8h,n(In^3 )/n(M^3 )在0.1-0.8之间可以得到纯度高和结晶好的镁铝铟类水滑石。  相似文献   
76.
The purpose of this paper is to discuss the poly-phase salt tectonics and its relation to the hydrocarbon accumulation of the Tarim superimposed basin. Several salt sequences are developed in the Tarim basin, they are: (1) the Mid-Early Cambrian salt sequence, mainly distributed in the west part of the north Tarim uplift and Keping uplift; (2) the Early Carboniferous salt sequence, mainly distributed in the south slope of the north Tarim uplift; (3) the Paleogene salt sequence, mainly distributed in the mid-west part of the Kuqa foreland fold belt and north Tarim uplift; and (4) the Miocene salt sequence, mainly distributed in the east part of the Kuqa foreland fold belt. The salt sequences deposited in the tectonically calm scenario, while the salt layers deformed during the period of intense tectonism. Although the salt sequences are characteristic of plastic flow, the differences of salt deformation styles exist in the different salt sequences because of the different deformation mechanism. It is attractive that the distribution of the large oil-gas fields or pools has a bearing upon the salt sequences and salt structures, such as the Tahe oilfield related to the Lower Carboniferous salt sequence and laterally facies changed mudstone, the Kela No.2 gas field to the Paleogene salt structures, and the Dina gas field to the Miocene salt structures. It is indicated that the large-scale hydrocarbon accumulation is controlled by the poly-phase salt sequences and structures. The deep analysis of the poly-phase salt tectonics is helpful to understanding the characteristics of the structural deformation and oil-gas accumulation of the Tarim basin.  相似文献   
77.
皮金云  王彦春  张静 《物探与化探》2007,31(2):164-166,170
在共偏移距初至曲线上,针对初至偏大和初至偏小的点,分别设置不同的计算参数,联动共炮点道集进行初至批量修改。在初至自动拾取算法上,利用波谷波峰比,结合参考初至、拾取时窗以及门槛值等参数,较好地解决了低信噪比地区初至拾取精度和效率问题。  相似文献   
78.
通过对大民屯凹陷地震资料的详细分析,针对洼陷部位信噪比高、主要目的层沙三、沙四段频率相对较低的特点,研究出一套高分辨率处理技术,主要包括子波处理技术及优势频带约束下的分频处理技术,能满足沙三、沙四段储层横向预测的需要,见到了较好的应用效果。  相似文献   
79.
田世君  陈俊  皮亦鸣 《测绘学报》2007,36(3):274-278
针对高动态GPS定位系统的特点,引入了一种基于粒子滤波的高动态GPS定位系统滤波算法。借助于移动目标的速度矢量模型建立了系统状态方程,论文给出了标准的卡尔曼滤波算法模型,重点讨论了粒子滤波算法在高动态GPS定位中的应用,详细描述了算法的推导过程。对算法进行仿真,结果表明当GPS接收机作大范围机动或GPS信号受到干扰时,粒子滤波要优于标准的卡尔曼滤波。  相似文献   
80.
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