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一种适用于珞珈一号夜间灯光影像的去噪方法 被引量:12
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作者 王美玲 张和生 《遥感信息》 CSCD 北大核心 2021年第2期114-119,共6页
针对珞珈一号夜间灯光影像存在大量背景噪声和异高值的问题,提出一种掩膜和局部中值滤波相结合的去噪方法。首先,以去噪后同时期的NPP/VIIRS月均影像为掩膜数据,剔除珞珈一号平均影像残留的背景噪声;然后,计算每个栅格的8邻域标准差(sta... 针对珞珈一号夜间灯光影像存在大量背景噪声和异高值的问题,提出一种掩膜和局部中值滤波相结合的去噪方法。首先,以去噪后同时期的NPP/VIIRS月均影像为掩膜数据,剔除珞珈一号平均影像残留的背景噪声;然后,计算每个栅格的8邻域标准差(standard deviation,STD)并进行分级统计,确定以STD大于25000为边界提取异高值栅格,对这部分栅格进行中值滤波,把异高值降低到正常值范围。通过统计发现,该去噪方法减少的灯光辐射栅格主要分布在林地、耕地和草地,影像辐射最大值由6034.920下降到900.599,辐射总值的减少量仅占原辐射总值的6.9%,并且去噪后的影像与GDP和常住人口数据的相关性均有提升。研究结果表明,该去噪方法能够在尽可能保留原始数据信息的同时有效去除珞珈一号夜间灯光影像大量存在的背景噪声和异高值。 展开更多
关键词 珞珈一号 夜间灯光影像 背景噪声 异高值 局部中值滤波
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An Analysis of the Causes of Decadal Variations of Rainfall in Shandong in Summer 被引量:1
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作者 GAOAnchun ZHANGSuping +1 位作者 SHENPeilu WUJiejing 《Journal of Ocean University of China》 SCIE CAS 2005年第2期99-107,共9页
The precipitation in Shandong in July, August as well as the whole summer (JJA) and the corresponding 500 hPa geopotential height fields are analyzed by means of the SVD (singular value decomposition) methodology. It ... The precipitation in Shandong in July, August as well as the whole summer (JJA) and the corresponding 500 hPa geopotential height fields are analyzed by means of the SVD (singular value decomposition) methodology. It is found that the general circulations in East Asia and the Western Pacific underwent decadal changes around 1979. The geopotential height, in particular over key areas like the South China Sea and the Philippines, increased after 1979. Corresponding to the changes in the geopotential height, the rainfall in Shandong started to decrease around 1979. The synthesized analysis shows that when the geopotential height at 500hPa level decreases in the key areas, the Western Pacific subtropical high shifts northward and an anticyclonic anomalous cell enforces the southerly flow over Shandong-Korea-Japan, Shandong could experience a wet period. A dry period is likely to occur when the geopotential height increases in these key areas, the subtropical high moves southward or expands westward to a great distance, and a cyclonic anomalous cell controls Shandong. Respective conceptual models for the causative mechanism are obtained for the cases of July, August and the whole summer (JJA) . 展开更多
关键词 summer rainfall Shandong Province 500 hPa geopotential height decadalvariations SVD analysis
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Method for obtaining high-resolution velocity spectrum based on weighted similarity 被引量:1
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作者 Xu Xing-Rong Su Qin +3 位作者 Xie Jun-Fa Wang Jing Kou Long-Jiang Liu Meng-Li 《Applied Geophysics》 SCIE CSCD 2020年第2期221-232,315,共13页
Seismic wave velocity is one of the most important processing parameters of seismic data,which also determines the accuracy of imaging.The conventional method of velocity analysis involves scanning through a series of... Seismic wave velocity is one of the most important processing parameters of seismic data,which also determines the accuracy of imaging.The conventional method of velocity analysis involves scanning through a series of equal intervals of velocity,producing the velocity spectrum by superposing energy or similarity coefficients.In this method,however,the sensitivity of the semblance spectrum to change of velocity is weak,so the resolution is poor.In this paper,to solve the above deficiencies of conventional velocity analysis,a method for obtaining a high-resolution velocity spectrum based on weighted similarity is proposed.By introducing two weighting functions,the resolution of the similarity spectrum in time and velocity is improved.Numerical examples and real seismic data indicate that the proposed method provides a velocity spectrum with higher resolution than conventional methods and can separate cross reflectors which are aliased in conventional semblance spectrums;at the same time,the method shows good noise-resistibility. 展开更多
关键词 Weighted function SIMILARITY high resolution velocity spectrum singular value decomposition WAVELET
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The diagnostic value of tumor abnormal protein and high sensitivity C reactive protein in screening for endometrial cancer with endometrial thickness less than 8 mm 被引量:3
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作者 Yi Li Ruiqin Yue +4 位作者 Dongrui Qin Yanqing Wang Xinling Zhou Xinyong Jing Chuanzhong Wu 《Oncology and Translational Medicine》 2016年第4期185-188,共4页
Objective This study aimed to combine tumor abnormal protein(TAP) and high-sensitivity C-reactive protein(hs-CRP) level detection to diagnose endometrial cancer in patients with endometrial thickness less than 8 mm, a... Objective This study aimed to combine tumor abnormal protein(TAP) and high-sensitivity C-reactive protein(hs-CRP) level detection to diagnose endometrial cancer in patients with endometrial thickness less than 8 mm, and to provide a reference for clinical screening and diagnosis. Methods Clinical data from 19 cases of endometrial cancer, diagnosed on the basis of pathological findings, were collected from September 2014 to December 2015. The inclusion criteria were as follows: the patients were first diagnosed with endometrial thickness less than 8 mm and were all in menopause. Perimenopausal patients(n = 26) with uterine fibroids seen during the same period were selected as a control group. Serum TAP and hs-CRP levels of the patients in the two groups were simultaneously determined on admission. Results We found that both TAP and hs-CRP levels in the experimental group were higher than those in the control group [(182.95 ± 72.14) μm^2 vs.(133.19 ± 55.18) μm^2, P = 0.019;(7.52 ± 19.03) mg/L vs.(1.66 ± 2.31) mg/L, P = 0.136]. The sensitivity of TAP for the diagnosis of endometrial cancer was 73.68%, the specificity was 69.23%, and the Youden index was 0.4291. The diagnostic sensitivity and specificity of hs-CRP was 15.79% and 100%, respectively, and the Youden index was 0.1579. After plotting the receiver operating characteristics curves, the optimal cut-off value for TAP in diagnosing endometrial cancer was found to be 160.662 μm^2 and that for hs-CRP was 1.07 mg/L. Conclusion For patients suspected of having endometrial cancer with endometrial thickness less than 8 mm, combined detection of TAP and hs-CRP levels can be used as a screening tool and can provide new ideas regarding clinical diagnosis and treatment. 展开更多
关键词 tumor abnormal protein(TAP) high-sensitivity C-reactive protein(hs-CRP) endometrial thickness endometrial carcinoma
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