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基于探元直方图匹配的CBERS-01星CCD数据相对辐射校正方法 被引量:24
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作者 潘志强 顾行发 +1 位作者 刘国栋 闵祥军 《武汉大学学报(信息科学版)》 EI CSCD 北大核心 2005年第10期925-927,共3页
提出并实现了基于探元直方图匹配的相对辐射校正方法。首先以探元为单位对CBERS01星CCD0级数据进行统计,然后基于直方图匹配方法建立每个探元的直方图查找表,用直方图查找表对01星数据进行相对辐射校正。该方法较好地解决了探元的非线... 提出并实现了基于探元直方图匹配的相对辐射校正方法。首先以探元为单位对CBERS01星CCD0级数据进行统计,然后基于直方图匹配方法建立每个探元的直方图查找表,用直方图查找表对01星数据进行相对辐射校正。该方法较好地解决了探元的非线性响应问题,图像处理质量有很大提高,为01星CCD数据的更广泛应用奠定了基础。 展开更多
关键词 探元 直方图匹配 相对辐射校正
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HJ-1B热红外通道探元级星上辐射定标方法研究
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作者 刘李 韩启金 +2 位作者 史婷婷 王爱春 张学文 《大气与环境光学学报》 CAS 2014年第1期50-56,共7页
HJ-1B热红外通道在轨星上定标精度直接影响着后续遥感数据的定量化应用。以往针对整个通道的星上辐射定标忽视了各个探元的响应差异问题。使用查找表法、半高宽法和矩方法,分别对2009年9月14日星上下传的黑体数据进行处理,得到HJ-1B... HJ-1B热红外通道在轨星上定标精度直接影响着后续遥感数据的定量化应用。以往针对整个通道的星上辐射定标忽视了各个探元的响应差异问题。使用查找表法、半高宽法和矩方法,分别对2009年9月14日星上下传的黑体数据进行处理,得到HJ-1B热红外通道探元级辐射定标结果。分析结果,红外相机热红外通道各探元扫描校正黑体时存在2个DN左右的波动,引入误差约0.28%~0.45%。其中,探元9和10相对其他探元波动范围较大。 展开更多
关键词 辐射定标 探元 热红外
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基于探测器宽度的FBP改进算法
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作者 刘亮 张斌 潘晋孝 《CT理论与应用研究(中英文)》 2007年第1期54-59,共6页
在实际的CT重建过程中,探测器是有大小的,如果我们在重建算法设计中考虑到这一点,对重建图像来说,将会得到更多更精确的信息量。本文针对实际探测器的结构特点,提出一种新的改进FBP重建算法,将算法与实际结合,并通过实际的工业CT系统进... 在实际的CT重建过程中,探测器是有大小的,如果我们在重建算法设计中考虑到这一点,对重建图像来说,将会得到更多更精确的信息量。本文针对实际探测器的结构特点,提出一种新的改进FBP重建算法,将算法与实际结合,并通过实际的工业CT系统进行实验。实验结果表明,改进方法重建出的图像边缘和细节都要比未改进的方法好,而且还有抑制噪声的作用,对工业CT的实际应用有一定的意义。 展开更多
关键词 测器结构 探元宽度 滤波反投影算法
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当代科学革命与探索复杂性新范式的创立
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作者 崔东明 《科学.经济.社会》 CSSCI 2011年第4期129-132,136,共5页
复杂性科学的兴起导致了科学研究方向的根本转变。以生命为隐喻理解世界,复杂性科学从无生命对象向有生命对象逐步扩展其研究范围,在机器系统和生命系统之间搭起桥梁;复杂性科学致力于研究系统整体性特征及其演化、生成机制,将信息、功... 复杂性科学的兴起导致了科学研究方向的根本转变。以生命为隐喻理解世界,复杂性科学从无生命对象向有生命对象逐步扩展其研究范围,在机器系统和生命系统之间搭起桥梁;复杂性科学致力于研究系统整体性特征及其演化、生成机制,将信息、功能和行为作为它的基本概念。在抛弃经典科学旧范式,逐步突破还原论纲领、超越划归思想的同时,复杂性科学从还原论走向探元论,从原子构成论走向系统生成论,向人们描绘了一幅非决定论的、自主性的、涌现的、生成的世界图景。 展开更多
关键词 系统科学 复杂性科学 科学革命 复杂性 索复杂性 生成论 探元
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海洋一号C卫星海岸带成像仪在轨几何定标
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作者 戴荣凡 韩静雨 +3 位作者 王密 曹金山 金淑英 孙从容 《海洋气象学报》 2023年第4期62-70,共9页
海洋一号C卫星(HY-1C)搭载的海岸带成像仪(coastal zone imager,CZI)为满足大幅宽成像需求,采用双相机组合成像,每台相间使用2片4色电荷耦合光敏元器件(charge-coupled device,CCD)拼接。从严密几何成像模型出发,对相机成像过程中存在... 海洋一号C卫星(HY-1C)搭载的海岸带成像仪(coastal zone imager,CZI)为满足大幅宽成像需求,采用双相机组合成像,每台相间使用2片4色电荷耦合光敏元器件(charge-coupled device,CCD)拼接。从严密几何成像模型出发,对相机成像过程中存在的系统误差进行分析,采用一种基于探元指向角的几何定标模型,并结合CZI相机设计特点与几何特性,设计出一套针对HY-1C/CZI的几何定标方案。首先利用CZI参考基准波段影像与高精度参考影像进行绝对几何定标,采用分步迭代的方法对参考基准波段影像内外定标参数进行解算,其次进行波段间相对几何定标,最后得到所有波段影像的几何定标结果。实验结果表明,经在轨几何定标后,平面无控定位精度优于5个像元,影像几何质量得到明显改善,说明所采用的定标模型和方案合理有效。 展开更多
关键词 海洋一号C卫星 海岸带成像仪 在轨几何定标 探元指向角模型 几何定位精度
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3D finite element numerical simulation of advanced detection in roadway for DC focus method 被引量:5
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作者 邓小康 柳建新 +2 位作者 刘海飞 童孝忠 柳卓 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第7期2187-2193,共7页
Within the roadway advanced detection methods, DC resistivity method has an extensive application because of its simple principle and operation. Numerical simulation of the effect of focusing current on advanced detec... Within the roadway advanced detection methods, DC resistivity method has an extensive application because of its simple principle and operation. Numerical simulation of the effect of focusing current on advanced detection was carried out using a three-dimensional finite element method (FEM), meanwhile the electric-field distribution of the point source and nine-point power source were calculated and analyzed with the same electric charges. The results show that the nine-point power source array has a very good ability to focus, and the DC focus method can be used to predict the aquifer abnormality body precisely. By comparing the FEM modelling results with physical simulation results from soil sink, it is shown that the accuracy of forward simulation meets the requirement and the artificial disturbance from roadway has no impact on the DC focus method. 展开更多
关键词 ROADWAY DC focus advanced detection finite element method
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3D laterolog array sonde design and response simulation 被引量:4
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作者 尹成芳 柯式镇 +3 位作者 许巍 姜明 张雷洁 陶婕 《Applied Geophysics》 SCIE CSCD 2014年第2期223-234,254,255,共14页
A new three-dimensional laterolog array sonde(3D-LS) is presented. The 3DLS is based on existing high-resolution laterolog array and azimuthal resistivity imaging sondes with radial, longitudinal, and circumferentia... A new three-dimensional laterolog array sonde(3D-LS) is presented. The 3DLS is based on existing high-resolution laterolog array and azimuthal resistivity imaging sondes with radial, longitudinal, and circumferential detection abilities. Six investigation modes are designed using the 3D finite-element method and different investigation depths are simulated based on the pseudo-geometrical factor of the six modes. The invasion profile is described using multi-array radial logs. From the analysis of the pseudo-geometrical factor, the investigation depth of the 3D-LS is about 1.5 m for conductive invasion, which is close to that of the dual laterolog tool but greater than that of the highly integrated azimuthal laterolog sonde. The vertical and azimuthal resolution is also analyzed with the same method. The 3DLS can detect low-resistivity anomalies of 0.5 m thickness and 15? around the borehole for infinitely thick formations. This study lays the foundation for more work on 3D laterolog array sonde for evaluating low-resistivity anomalies. 展开更多
关键词 Three-dimensional laterolog sonde numerical modeling FEM DETECTIVITY lowresistivity
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高分六号高分全色相机高精度几何检校 被引量:1
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作者 张谷生 王慧静 杨斌 《测绘与空间地理信息》 2022年第6期238-242,共5页
高分六号全色影像的幅宽大于90 km,在大比例尺度地表量测中具有重要意义,而其高精度几何检校是遥感影像几何处理的关键环节,直接影响遥感卫星影像的可量测性。本文在缺少人工标靶数据和精密实验室几何成像标校参数的条件下,利用高分六... 高分六号全色影像的幅宽大于90 km,在大比例尺度地表量测中具有重要意义,而其高精度几何检校是遥感影像几何处理的关键环节,直接影响遥感卫星影像的可量测性。本文在缺少人工标靶数据和精密实验室几何成像标校参数的条件下,利用高分六号卫星辅助数据和参考数据,采用基于探元指向角的几何检校模型对高分六号高分全色相机进行高精度几何检校。经过检校之后高分六号全色影像的绝对定位精度优于50 m,内部相对定位精度优于4个像素,表明高分六号高分全色相机在经过高精度几何检校之后影像几何质量可以满足测绘需求。 展开更多
关键词 高分六号 高精度几何检校 探元指向角 绝对定位精度 相对定位精度
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Electromagnetic holographic sensitivity field of two-phase flow in horizontal wells 被引量:2
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作者 张阔 吴锡令 +1 位作者 闫景富 蔡家铁 《Applied Geophysics》 SCIE CSCD 2017年第1期40-48,189,共10页
Electromagnetic holographic data are characterized by two modes, suggesting that image reconstruction requires a dual-mode sensitivity field as well. We analyze an electromagnetic holographic field based on tomography... Electromagnetic holographic data are characterized by two modes, suggesting that image reconstruction requires a dual-mode sensitivity field as well. We analyze an electromagnetic holographic field based on tomography theory and Radon inverse transform to derive the expression of the electromagnetic holographic sensitivity field (EMHSF). Then, we apply the EMHSF calculated by using finite-element methods to flow simulations and holographic imaging. The results suggest that the EMHSF based on the partial derivative of radius of the complex electric potential φ is closely linked to the Radon inverse transform and encompasses the sensitivities of the amplitude and phase data. The flow images obtained with inversion using EMHSF better agree with the actual flow patterns. The EMHSF overcomes the limitations of traditional single-mode sensitivity fields. 展开更多
关键词 electromagnetic holographic sensitivity field (EMHSF) holographic physical detection field finite-element method holographic imaging
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顾及姿态线性误差的微小卫星面阵影像在轨几何检校
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作者 王朗 尤红建 王慧贤 《测绘通报》 CSCD 北大核心 2020年第3期25-28,共4页
微小卫星由于平台体积、重量、能源等限制,其上搭载的姿态、位置测量设备精度不高,导致其直接对地定位误差较大。通过对某微小卫星嵩山地区的多景面阵影像进行姿态角常差检校,发现姿态角系统误差随时间线性变化的规律。为了提高定位精度... 微小卫星由于平台体积、重量、能源等限制,其上搭载的姿态、位置测量设备精度不高,导致其直接对地定位误差较大。通过对某微小卫星嵩山地区的多景面阵影像进行姿态角常差检校,发现姿态角系统误差随时间线性变化的规律。为了提高定位精度,本文提出一种针对面阵的顾及姿态线性误差的偏置矩阵和二维探元指向角几何检校模型。相对于传统的姿态角常差检校模型,本文方法考虑了姿态角系统误差随时间线性变化的规律。试验结果表明,经过内外方位元素检校后,卫星的定位精度从数十千米提升到十米以内,相对于传统的常差模型,本文提出的检校模型有效地消除了姿态随时间线性变化的系统误差。 展开更多
关键词 微小卫星 严格几何成像模型 参数检校 姿态角线性误差模型 二维探元指向角
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2D numerical study on the effect of conductor between the transmitter and survey area in CSEM exploration 被引量:1
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作者 王若 王妙月 +1 位作者 底青云 王光杰 《Applied Geophysics》 SCIE CSCD 2009年第4期311-318,393,共9页
In CSEM exploration, the receivers are generally located about three to five times the skin depth from the transmitter. In this paper, we study the effect of a conductor between the transmitter and the survey area on ... In CSEM exploration, the receivers are generally located about three to five times the skin depth from the transmitter. In this paper, we study the effect of a conductor between the transmitter and the survey area on the target conductor response using forward modeling and inversion. The 2D forward finite element calculations show that the conductor mainly affects the response at middle and low frequencies. The lower the resistivity and the larger the conductor, the larger the effect and the effect increases with decreasing frequency. The inversion results indicate that the calculated position of the target body can move towards the source, leading to an incorrect interpretation without considering the conductor. In order to reduce the effect of a conductor between the source and the survey area, CSEM acquisition should be conducted in three dimensions using multiple sources and 3D inversion should be used during interpretation. 展开更多
关键词 CSEM exploration 2D line source low resistivity body forward modeling INVERSION
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FE Method of Analysing Detecting Electrode of Capacitance Proximity Fuze 被引量:2
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作者 程顺 崔占忠 张旭东 《Journal of Beijing Institute of Technology》 EI CAS 2002年第3期302-305,共4页
The finite element method is first introduced into the design process of detecting electrodes of three electrode capacitance fuze, the mutual capacitance of the fuze and target is calculated by the finite element met... The finite element method is first introduced into the design process of detecting electrodes of three electrode capacitance fuze, the mutual capacitance of the fuze and target is calculated by the finite element method, which provides the parameters for simulation circuit and design of detecting electrode. The finite element method pierces the traditional method of designing detecting electrode-design, test and adjustment. The system capacitance can be calculated accurately and the performance can be predicted in the design period of the detecting electrode, which saves a lot of research fee. The capacitances of a mortar shell fuze above ground 2 m and lower are given. After putting the computing data into simulating circuit, the demodulation voltage can be obtained, its changing trend is in agreement with the tested result. 展开更多
关键词 capacitance fuze finite element detecting electrode circuit simulation
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Fault detection of excavator’s hydraulic system based on dynamic principal component analysis 被引量:5
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作者 何清华 贺湘宇 朱建新 《Journal of Central South University of Technology》 2008年第5期700-705,共6页
In order to improve reliability of the excavator's hydraulic system, a fault detection approach based on dynamic principal component analysis(PCA) was proposed. Dynamic PCA is an extension of PCA, which can effect... In order to improve reliability of the excavator's hydraulic system, a fault detection approach based on dynamic principal component analysis(PCA) was proposed. Dynamic PCA is an extension of PCA, which can effectively extract the dynamic relations among process variables. With this approach, normal samples were used as training data to develop a dynamic PCA model in the first step. Secondly, the dynamic PCA model decomposed the testing data into projections to the principal component subspace(PCS) and residual subspace(RS). Thirdly, T2 statistic and Q statistic performed as indexes of fault detection in PCS and RS, respectively. Several simulated faults were introduced to validate the approach. The results show that the dynamic PCA model developed is able to detect overall faults by using T2 statistic and Q statistic. By simulation analysis, the proposed approach achieves an accuracy of 95% for 20 test sample sets, which shows that the fault detection approach can be effectively applied to the excavator's hydraulic system. 展开更多
关键词 hydraulic system EXCAVATOR fault detection principal component analysis multivariate statistics
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Application of deviation rate in oil and gas reservoir exploration 被引量:1
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作者 汤井田 张继锋 +1 位作者 冯兵 王烨 《Journal of Central South University of Technology》 EI 2008年第2期251-255,共5页
Three dimensional geophysical models were abstracted and established according to characteristics of oil and gas reservoir.Then direct current fields for different models were simulated with finite element software(fi... Three dimensional geophysical models were abstracted and established according to characteristics of oil and gas reservoir.Then direct current fields for different models were simulated with finite element software(finite element program generator) by hole-to-surface resistivity method.Numerical solution was compared with analytical one for the homogeneity earth model.And a new parameter of deviation rate was proposed by analyzing different plot curves.The results show that the relative error of solution for homogeneity earth model may attain to 0.043%.And deviation rate decreases from 18% to 1% and its anomaly range becomes wide gradually when the depth of oil and gas reservoir increases from 200 to 1 500 m.If resistivity ratio of oil and gas reservoir to sur-rounding rock decreases from 100 to 10 for the resistive oil and gas reservoir,the amplitude attenuation of deviation rate nearly reaches 8%.When there exists stratum above oil and gas reservoir,and influence of resistive stratum may be eliminated or weakened and anomaly of oil and gas reservoir can be strengthened. 展开更多
关键词 numerical simulation deviation rate oil and gas reservoir hole-to-surface resistivity method finite element programgenerator
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The Finite Element Analysis for Parallel-wire Capacitance Probe in Small Diameter Two-phase Flow Pipe 被引量:1
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作者 翟路生 金宁德 +1 位作者 高忠科 黄旭 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2013年第7期813-819,共7页
This paper presents a novel capacitance probe, i.e., paraUel-wire capacitance probe (PWCP), for two-phase flow measurement. Using finite element method (FEM), the sensitivity field of the PWCP is investigated and ... This paper presents a novel capacitance probe, i.e., paraUel-wire capacitance probe (PWCP), for two-phase flow measurement. Using finite element method (FEM), the sensitivity field of the PWCP is investigated and the optimum sensor geometry is determiend in term of the characterisitc parameters. Then, the response of PWCP for the oil-water stratified flow is calculated, and it is found the PWCP has better linearity and sensitivity to the variation of water-layer thickness, and is almost independant of the angle between the oil-water interface and the sensor electrode. Finally, the static experiment for oil-water stratified flow is carried out and the calibration method of liquid holdup is presented. 展开更多
关键词 parallel-wire capacitance probe finite element analysis sensitivity field oil-water stratified flow
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Self-contained in situ sediment acoustic measurement system based on hydraulic driving penetration 被引量:9
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作者 Kan Guangming Liu Baohua +2 位作者 Zhao Yuexia Li Guanbao Pei Yanliang 《High Technology Letters》 EI CAS 2011年第3期311-316,共6页
A novel self-contained in situ sediment acoustic measurement system based on hydraulic driving penetration is proposed to solve the problem of large disturbances to sediments of the in situ equipments already in exist... A novel self-contained in situ sediment acoustic measurement system based on hydraulic driving penetration is proposed to solve the problem of large disturbances to sediments of the in situ equipments already in existence. By using a hydraulic driving device, the system drives four acoustic probes into sediments at an even speed, and this decreases disturbances to sediments introduced by the penetration of acoustic probes. By means of the special design of the central control unit, the system can work full-automatically and the data are stored self-containedly, and this avoids the requirement of real-time remote controlling from the ship. Its operating water depth, measuring depth and measuring frequency is 500m, 1.0m and 30kHz respectively. A set of in situ sound speeds and attenuation coefficients of sediments are obtained at 40 stations using the system. The results confirm that the data obtained by the in situ sediment acoustic system are accurate and credible. 展开更多
关键词 acoustic properties sound speed sound attenuation in situ measurement system
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Scheme for Concentration of Unknown Photonic GHZ Entangled States via Linear Optical Elements 被引量:1
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作者 ZHANG Gang YANG Ming CAO Zhuo-Liang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第5X期853-856,共4页
We propose two schemes to concentrate unknown nonmaximally tripartite GHZ entangled states via linear optical elements. The finial maximally entangled states obtained from our schemes are shared by two or three partie... We propose two schemes to concentrate unknown nonmaximally tripartite GHZ entangled states via linear optical elements. The finial maximally entangled states obtained from our schemes are shared by two or three parties. Our schemes only need polarizing beam splitters and single-photon detectors. In addition, the schemes can be demonstrated within current experimental technology. 展开更多
关键词 unknown photonic GHZ entangled states CONCENTRATION linear optical elements
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Reverse time migration imaging of tunnels via the finite element method using an unstructured mesh
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作者 Wang Jing Liu Jiang-Ping +2 位作者 Cheng Fei Yang Huai-Jie Huang Yi-Fan 《Applied Geophysics》 SCIE CSCD 2020年第2期267-276,316,共11页
Wavefield extrapolation is critical in reverse time migration(RTM).The finite diff erence method is primarily used to achieve wavefi eld extrapolation in case of the RTM imaging of tunnels.However,complex tunnel model... Wavefield extrapolation is critical in reverse time migration(RTM).The finite diff erence method is primarily used to achieve wavefi eld extrapolation in case of the RTM imaging of tunnels.However,complex tunnel models,including those for karsts and fault fracture zones,are constructed using regular grids with straight curves,which can cause numerical dispersion and reduce the imaging accuracy.In this study,wavefi eld extrapolation was conducted for tunnel RTM using the finite element method,wherein an unstructured mesh was considered to be the body-fi tted partition in a complex model.Further,a Poynting vector calculation equation suitable for the unstructured mesh considered in the fi nite element method was established to suppress the interference owing to low-frequency noise.The tunnel space was considered during wavefi eld extrapolation to suppress the mirror artifacts based on the fl exibility of mesh generation.Finally,the infl uence of the survey layouts(one and two sidewalls)on the tunnel imaging results was investigated.The RTM results obtained for a simple tunnel model with an inclined interface demonstrate that the method based on unstructured meshes can effectively suppress the low-frequency noise and mirror artifacts,obtaining clear imaging results.Furthermore,the two-sidewall tunnel survey layout can be used to accurately obtain the real position of the inclined interface ahead of the tunnel face.The complex tunnel numerical modeling and actual data migration results denote the eff ectiveness of the fi nite element method in which an unstructured mesh is used. 展开更多
关键词 Tunnel advanced prediction fi nite element method unstructured mesh Poynting vector mirror artifacts
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Electrode Design of Cylindrical Coplanar-grid CdZnTe Detector by Finite Element Methods 被引量:1
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作者 JINWei SANGWen-bin ZHANGQi MINJia-Hua SHENYan 《Semiconductor Photonics and Technology》 CAS 2004年第1期48-52,共5页
Cylindrical coplanar-grid configurations,which offer a lot of advantages over established designs,can effectively overcome the problem of poor hole collection.Finite element analysis is utilized for simulating the pot... Cylindrical coplanar-grid configurations,which offer a lot of advantages over established designs,can effectively overcome the problem of poor hole collection.Finite element analysis is utilized for simulating the potential distribution of the cylindrical coplanar-grid detector under different models by varying the widths of grid and pitch of electrodes. In addition, a modified grid pattern has been discussed to improve the weighting potential match between two grids. In this way, the geometry of electrodes for cylindrical coplanar-grid detectors is optimized. 展开更多
关键词 CDZNTE Finite Element Methods Coplanar-grid DETECTOR
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A Laser Ranging System Using Chaotic Light 被引量:1
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作者 赵彤 王冰洁 +1 位作者 王安帮 王云才 《Journal of Measurement Science and Instrumentation》 CAS 2011年第4期398-401,共4页
A novel laser ranging system using chaotic laser as probe light source is designed and presented.The system is made up of five components:chaotic light source,transmitter,receiver,data acquisition unit and data proces... A novel laser ranging system using chaotic laser as probe light source is designed and presented.The system is made up of five components:chaotic light source,transmitter,receiver,data acquisition unit and data processing unit.Chaotic light is generated by an 808 nm,500 mW,single-mode laser diode with optical feedback cavity.Single target detection and multi-target detection are experimentally realized by correlating the chaotic reference light and the reflected or backscattered probe light.The performances,including the resolution of 18 cm within at least 130 m range and the sensitivity of-20 dB,are achieved and analyzed. 展开更多
关键词 laser ranging chaotic laser optical feedback laser diode
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