共查询到20条相似文献，搜索用时 975 毫秒
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多输入多输出极化步进频率探地雷达硬件系统开发 总被引：1，自引：0，他引：1
对基于矢量网络分析仪的单发单收探地雷达系统进行扩展,组建了可实现信号多通道发射和多通道接收的步进频率探地雷达系统。该系统主要由计算机、矢量网络分析仪、三维直角坐标仪、开关控制转换器、同轴开关以及多次覆盖极化天线阵列构成。系统信号发射通道和信号接收通道均可扩展至6个通道,可满足一般天线阵列测量需求。多次覆盖天线阵列采集共中心点（CMP）数据,每个测点可获取2个共极化模式数据和4个交叉极化模式数据,数据叠加后噪声可得到有效压制,系统信噪比可获得较大提升;同时应用Pauli分解方法获得伪彩色剖面图以对目标物体进行散射机制的分类。对该多输入多输出步进频率探地雷达系统进行系统测试和实验的结果,验证了其可靠性。 相似文献
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由于探地雷达系统大多采用超宽带窄脉冲信号,因此要求天线具有极宽的工作带宽。利用矩量法对线性离散电阻加载蝶形天线进行分析,结果表明,线性离散电阻加载在使天线获得宽带特性的同时,并使辐射的脉冲信号拖尾变得平稳,因此能够满足探地雷达系统的需要。 相似文献
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在实践基础上，总结了探地雷达超浅异常体探测经验，并对野外参数的选取及其对探测效果的影响进行了分析、研究，文章提供的实例对研究探地雷达探测应用效果有一定参考价值 相似文献
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基于GIS思想的探地雷达处理系统 总被引：1，自引：0，他引：1
作者借助于地学信息系统的方法思路，编程实现了基于GIS的探地雷达处理系统。可以进行不同雷达系统资料的共享，雷达数据的集成管理，多方法的信息处理技术以及基于Windows界面的成果可视化。 相似文献
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钢筋混凝土GPR检测图像的目标体快速识别技术 总被引：2，自引：0，他引：2
HUANG Ling ZENG Zhao-fa YAO Jian ZHANG Dai-guo College of GeoExploration Science Technology Jilin University Changchun China 《吉林大学学报(地球科学版)》2006,(Z2)
在一般的城建工程结构体的探地雷达检测中,为减小检测工作周期,需要进行现场探测、处理及解释;或是检测工区数据量大,逐个剖面进行人工处理解释需要很大的工作量和工作时间。为解决这些问题,引入了基于F—K偏移及小波变换法图像分割的目标体快速识别技术,对钢筋混凝土探地雷达检测图像进行处理,达到了对钢筋混凝土结构探地雷达检测图像快速处理与解释的效果,也为能够把数据处理程序直接嵌入探地雷达系统中提供理论基础。 相似文献
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The time series BT profiles and surface winds and atmospheric pressure, collected in the deep waters off Ratnagiri and Karwar
during summer monsoon were utilized to document the characteristics of internal waves (IW). Low-frequency (≤2, cycle per day
(cpd)) IW off Ratnagiri are found to propagate at 83 cm/s with wavelengths of 45 km and wave heights upto 40 m. These parameters
for high-frequency (>2 cpd) IW off Karwar correspond to 99 cm/s, 3 km and 23 m. The IW off Karwar appear to leave the station
at 70° (±10°) (measured from the horizontal). The data sets were further analysed to address the harmonic composition of the
IW and identify the possible sources for the observed IW fields. Power spectra of the IW indicated energy peaks at inertial
(0·6 cpd) and tidal (1 and 2 cpd) frequencies off Ratnagiri and in the high-frequency band of 0·5–2·0 cycles per hour off
Karwar. The coherence between the IW and wind/tide is found to be good at several frequencies within the IW spectrum. This
feature probably suggests tides as a source for the IW of tidal frequencies and winds and tides as a joint source for the
IW at the remaining frequencies. 相似文献
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卫星CCD图像的去云处理对遥感信息的增强与提取有重要的意义,尤其是在云覆盖严重的低纬度地区。为去除CBERS-02B卫星CCD图像中薄云的影响,分别使用Mallat和à trous 2种小波变换对图像进行分解;利用同态滤波对2种小波分解图像的低频系数进行处理,衰减其低频信息;将处理后的小波低频系数与分解的高频系数进行小波重构,从而达到去云的目的。定量分析基于Mallat和à trous小波变换结合同态滤波法的去云结果表明,经à trous小波变换结合同态滤波法的去云影像所包含信息量大,细节信息丰富,去云效果较好。 相似文献
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利用人工振动技术增加石油产量的机理之一是地层的机械共振作用。提出了一种简化的地层模型,并将其转化为一个双自由度有阻尼振动系统。研究了各种不同厚度的地层的振幅与振动频率的关系、共振频率与固有频率的关系以及品质因素 Ｑ 对地层振幅和共振频率的影响,得出有意义的结论。 相似文献
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Episodic observations of coronal holes were carried out simultaneously in several spectral lines during the 2002–2005 observational seasons. An analysis of eighteen time series is used to obtain the amplitude—spectral properties of oscillatory wave motions of the solar plasma at the bases of coronal holes. It is found that the amplitudes of the 5-min and 3-min line-of-sight velocity oscillations increase in coronal holes. Low-frequency (1–2 mHz) oscillations are concentrated at the boundaries of the chromospheric network, while the 3-mHz and 5-mHz oscillations dominate in the network cells. Clear indications of propagating waves have been found at the bases of coronal holes. The 3 mHz phase velocities are 45 ± 5 km/s and 80–100 km/s for the equatorial and polar coronal holes, respectively. 相似文献
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频率域航空电磁系统线圈姿态变化影响及校正是一项探索性很强的开拓性工作, 目前国内尚无成熟经验可循.吊舱式直升机频率域航空电磁法线圈安装在吊舱内, 探头姿态变化相对较大, 因此姿态校正提高了其数据处理精度, 对提高航空电磁法数据处理水平具有重要意义.为了消除吊舱式直升机频率域航空电磁系统因收发线圈姿态发生变化, 而导致的电磁探头接收地下地质体电磁响应数据产生的误差, 采用三维频率域有限差分方法模拟计算频率域航空电磁系统的电磁响应, 分析了不同频率、不同收发线圈姿态变化类型对水平共面(HCP, 全称horizontal co-plane)和垂直同轴(VCX, 全称vertical coaxial)线圈装置的电磁响应影响.计算结果表明: 垂直同轴线圈装置因姿态角度变化引起的测量误差比值远大于水平共面装置, 而且频率越高, 受探头姿态角度变化的影响越大.垂直同轴装置主要受俯冲姿态变化的影响, 水平共面装置受摇摆和俯冲这2种姿态变化的影响.在此基础上, 根据姿态误差几何校正方法进行了电磁数据校正, 有效地去除了因线圈姿态变化造成的误差响应. 相似文献
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目前国内、外油气勘探已经进入岩性油气藏勘探阶段,其中致密碳酸盐岩或页岩油气勘探具有远大前景。这类致密储层中裂缝是油气储集的主要空间。用模拟地震子波的小波函数对原始三维地震数据体作小波变换,可以得到不同频带（分辨率）的地震数据体。分别对具有不同分辨率的三维地震数据体进行C3相干处理,其中低频相干体突出了断裂的信息,而高频相干体则突出反映了受断裂控制下的小断裂或裂缝的发育信息,通过合理的融合系数有选择地对C3相干数据进行融合,获得了能够高精度分辨裂缝发育特征的相干数据体,由此提高了裂缝检测和储层预测的精度。 相似文献
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本文根据国际上采用直升机载频率域电磁系统进行环境和工程勘查的应用效果,结合我国引进的航空电磁系统的性能和特点,探讨了采用直升机载频率域电磁系统在我国进行环境和工程勘查的应用前景。 相似文献
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S. A. Potanin 《Astronomy Reports》2008,52(7):598-605
Low-frequency (0–0.5 Hz) errors in the positions of stars in the focal plane of the ZTE 1.25-m telescope of the Crimean Laboratory of the Sternberg Astronomical Institute and the AZT-22 1.5-m telescope of the Maidanak Observatory in Uzbekistan are analyzed using data obtained during the operation of two optical compensators designed to correct the tilt of incoming wave fronts. A spectral analysis is used to identify possible origins of these errors. The amplitudes of periodic errors in the main worm-and-worm gears of the tracking mechanisms have been measured to be 1.5″ (a period of 240 s) for the 1.25-m telescope and 0.15″ (167 s) for the 1.5-m telescope. The rates of constant drifts have also been determined. 相似文献
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某低频泥石流沟堆积物特征研究 总被引：2，自引：0，他引：2
低频泥石流是我国分布最广、数量最大、危害性极大的一类泥石流,因其特有的隐蔽性,它所造成的人员伤亡和财产损失均居各类泥石流之首。通过对新疆某水电站坝后一低频泥石流沟堆积物的研究,探讨了该类泥石流的发育特征和研究方法。由于低频泥石流形成周期较长,一般几十年甚至上百年,从而后期的流水、暴雨有足够的时间通过侵蚀、置换作用,在各期泥石流堆积物的顶部形成一个显著的“粗化层”,这为判定泥石流活动的期次、规模、发展趋势提供了重要的依据。 相似文献
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Quasi-periodic modulations of the microwave emission from solar outbursts at 37 GHz are studied based on 17 events observed in 1989–2000 at the Metsähovi Observatory. Low-frequency modulations with periods of ～5 min were found in approximately 90% of the observed microwave outbursts. The most likely origin of this modulation is modulation of the current flowing along a closed coronal magnetic loop due to the five-minute oscillations of the photospheric-convection velocity. In approximately 70% of the cases, oscillations with periods ～10 min were observed simultaneously with the five-minute oscillations in the same events. In 30% of the cases, simultaneous modulation of the microwave emission by three low-frequency signals with periods of 3, 5, and 10 min was observed. One possible origin of these “double” and “triple” modulations is parametric excitation of acoustic oscillations with periods of 10 and 3 min in a closed coronal magnetic loop as a result of coupling with the five-minute photospheric oscillations. This can occur when the period of the natural acoustic oscillations of the closed magnetic loop is about 10 min (the resonance condition). Since the ten-minute oscillations are excited more easily than the three-minute oscillations at the parametric instability, the latter are observed less frequently. For the same reason, the observed linewidth of the ten-minute oscillations is considerably greater than that of the three-minute oscillations. 相似文献