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Integration of spatial attractions between and within pixels for sub-pixel mapping 被引量:3
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作者 Qunming Wang Liguo Wang Danfeng Liu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2012年第2期293-303,共11页
As a promising technique to enhance the spatial reso- lution of remote sensing imagery, sub-pixel mapping is processed based on the spatial dependence theory with the assumption that the land cover is spatially depend... As a promising technique to enhance the spatial reso- lution of remote sensing imagery, sub-pixel mapping is processed based on the spatial dependence theory with the assumption that the land cover is spatially dependent both within pixels and be- tween them. The spatial attraction is used as a tool to describe the dependence. First, the spatial attractions between pixels, sub- pixel/pixel spatial attraction model (SPSAM), are described by the modified SPSAM (MSPSAM) that estimates the attractions accord- ing to the distribution of sub-pixels within neighboring pixels. Then a mixed spatial attraction model (MSAM) for sub-pixel mapping is proposed that integrates the spatial attractions both within pix- els and between them. According to the expression of the MSAM maximumising the spatial attraction, the genetic algorithm is em- ployed to search the optimum solution and generate the sub-pixel mapping results. Experiments show that compared with SPSAM, MSPSAM and pixel swapping algorithm modified by initialization from SPSAM (MPS), MSAM can provide higher accuracy and more rational sub-pixel mapping results. 展开更多
关键词 remote sensing imagery sub-pixel mapping mixed spatial attraction model (MSAM) genetic algorithm (GA).
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Development of Global Cropland Agreement Level Analysis by Integrating Pixel Similarity of Recent Global Land Cover Datasets
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作者 Anjar Dimara Sakti Wataru Takeuchi Ketut Wikantika 《Journal of Environmental Protection》 2017年第12期1509-1529,共21页
Global cropland monitoring is important when considering tactical strategies for achieving food sustainability. Different global land cover (GLC) datasets providing cropland information have already been published and... Global cropland monitoring is important when considering tactical strategies for achieving food sustainability. Different global land cover (GLC) datasets providing cropland information have already been published and they are used in many applications. The different data input methods, classification techniques, class definitions and production years among the different GLC datasets make them all independently useful sources of information. This study attempted to produce a cropland agreement level (CAL) analysis based on the integration of several cropland datasets to more accurately estimate cropland area distribution. Estimating cropland area and how it has changed on a national level was done by converting the level of cropland agreement into percentages with an existing cropland fraction map. A pre-analysis showed that the four GLC datasets used in the 2005 and 2010 groups had similar year input data acquisitions. Therefore, we placed these four datasets (GlobCover, MODIS LC, GLCNMO and ESACCI LC) into 2005 and 2010 year-groups and selected them to process dataset integration through a CRISP approach. The results of this process proposed four agreement levels for this CAL analysis, and the model correlation was converted into percentage values. The cropland estimate results from the CAL analysis were observed along with FAO data statistics and showed the highest accuracy, with a 0.70 and 0.71 regression value for 2005 and 2010 respectively. In the cropland area change analysis, this CAL change analysis had the highest level of accuracy when describing the total size of cropland area change from 2005 and 2010 when compared to other individual original GLC datasets. 展开更多
关键词 GLOBAL Land COVER pixel Comparison CROPLAND AGREEMENT level
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Fast Approaches for Sub-pixel Precision Variable Block Size Motion Estimation
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作者 张颖 萧允治 沈庭芝 《Journal of Beijing Institute of Technology》 EI CAS 2009年第2期209-214,共6页
The new features of H. 264 video coding standard make the motion estimation module much more time consuming than before. Especially, the motion search is required for each of the 4 modes for inter prediction. In order... The new features of H. 264 video coding standard make the motion estimation module much more time consuming than before. Especially, the motion search is required for each of the 4 modes for inter prediction. In order to reduce the computational complexity, we analyze the statistics of results of motion estimation, such as the continuity of best modes of blocks in successive frames and the chance to give up a sub-partition mode (smaller than 16 × 16) after integer-pixel motion estimation, from which we suggest to make mode prediction based on the motion information of the previous frame and skip sub-pixel motion estimation in subpartition mode selectively. According to the experimental result, the proposed algorithm can save 75 % of the computational time with a slight degradation (0.03 dB) on PSNR compared with the pseudocode of fast search motion estimation in JM12.2. 展开更多
关键词 video coding motion estimation sub-pixel variable block size
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一种改进的三次样条插值划痕宽度检测方法
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作者 张丽玲 刘洋 +1 位作者 饶繁星 齐贤敏 《机械设计与制造》 北大核心 2026年第1期89-93,98,共6页
由于对光学镜片划痕的像素级检测算法检测精度低,对相机分辨率要求高,且亚像素边缘检测方法无法直接完成宽度计算。因此,提出一种基于改进的三次样条插值亚像素宽度自动测量方法。首先,对经典Sobel算子模板进行拓展用于划痕的粗定位并... 由于对光学镜片划痕的像素级检测算法检测精度低,对相机分辨率要求高,且亚像素边缘检测方法无法直接完成宽度计算。因此,提出一种基于改进的三次样条插值亚像素宽度自动测量方法。首先,对经典Sobel算子模板进行拓展用于划痕的粗定位并确定边缘梯度,再由三次样条插值对边缘梯度进行精确定位,确定图像中的亚像素边缘点,根据边缘梯度方向对划痕宽度计算方法改进,最终完成对划痕宽度的检测。实验分析表明,该方法可以满足生产实际需要,能够实时精确地检测出划痕宽度。 展开更多
关键词 亚像素 三次样条插值 光学镜片 边缘检测
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基于虚拟像平面模型的RGB-T图像生成方法
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作者 蔡鑫洋 李巍岷 +1 位作者 张瀛煜 刘昶 《仪表技术》 2026年第1期50-54,共5页
针对可见光与热红外(RGB-Thermal,RGB-T)图像的融合问题,提出一种基于虚拟像平面模型的RGB-T图像生成方法。采用带有发热元件的平面棋盘格标定板,完成可见光相机与热红外面阵传感器的联合标定;在畸变校正基础上,将可见光图像重投影至虚... 针对可见光与热红外(RGB-Thermal,RGB-T)图像的融合问题,提出一种基于虚拟像平面模型的RGB-T图像生成方法。采用带有发热元件的平面棋盘格标定板,完成可见光相机与热红外面阵传感器的联合标定;在畸变校正基础上,将可见光图像重投影至虚拟像平面,得到对应的虚拟图像;将热红外图像投影至同一虚拟像平面,实现可见光与热红外图像的像素级对齐,从而构建目标的四通道RGB-T图像。实验结果表明,所提方法能够有效融合目标的颜色信息与温度特征,有助于提升热源目标的检测性能。 展开更多
关键词 图像融合 虚拟像平面模型 RGB-T图像 像素级对齐 热目标检测
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基于机器视觉的微小圆孔直径测量系统
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作者 黄政思 张能恩 《自动化与仪表》 2026年第1期97-100,106,共5页
针对传统人工微孔直径测量存在效率低、精度差等难题,设计了一种基于机器视觉的微小圆孔测量系统。系统通过显微镜摄像头采集图片,结合图像预处理、微孔检测、轮廓提取与像素标定等步骤,实现了微孔直径的非接触、自动化、迅速测量。实... 针对传统人工微孔直径测量存在效率低、精度差等难题,设计了一种基于机器视觉的微小圆孔测量系统。系统通过显微镜摄像头采集图片,结合图像预处理、微孔检测、轮廓提取与像素标定等步骤,实现了微孔直径的非接触、自动化、迅速测量。实验结果表明,系统对直径为0.25 mm的微孔测量绝对误差小于0.0015 mm,相对误差低于0.6%,在确保精度的同时兼具低成本优势,满足工业精密检测需要。 展开更多
关键词 机器视觉 微孔测量 图像处理 亚像素边缘检测 像素标定
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Regional Frequency Analysis of Observed Sub-Daily Rainfall Maxima over Eastern China 被引量:2
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作者 Hemin SUN Guojie WANG +3 位作者 Xiucang LI Jing CHEN Buda SU Tong JIANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2017年第2期209-225,共17页
Based on hourly rainfall observational data from 442 stations during 1960-2014, a regional frequency analysis of the annual maxima (AM) sub-daily rainfall series (1-, 2-, 3-, 6-, 12-, and 24-h rainfall, using a mov... Based on hourly rainfall observational data from 442 stations during 1960-2014, a regional frequency analysis of the annual maxima (AM) sub-daily rainfall series (1-, 2-, 3-, 6-, 12-, and 24-h rainfall, using a moving window approach) for eastern China was conducted. Eastern China was divided into 13 homogeneous regions: Northeast (NE1, NE2), Central (C), Central North (CN1, CN2), Central East (CE1, CE2, CE3), Southeast (SE1, SE2, SE3, SE4), and Southwest (SW). The generalized extreme value performed best for the AM series in regions NE, C, CN2, CE1, CE2, SE2, and SW, and the generalized logistic distribution was appropriate in the other regions. Maximum return levels were in the SE4 region, with value ranges of 80-270 mm (1-h to 24-h rainfall) and 108-390 mm (1-h to 24-h rainfall) for 20- and 100 yr, respectively. Minimum return levels were in the CN1 and NE1 regions, with values of 37-104 mm and 53-140 mm for 20 and 100 yr, respectively. Comparing return levels using the optimal and commonly used Pearson-III distribution, the mean return-level differences in eastern China for 1-24-h rainfall varied from -3-4 mm to -23-11 mm (- 10%-10%) for 20-yr events, reaching -6-26 mm (-10%-30%) and -10-133 mm (-10%-90%) for 100-yr events. In view of the large differences in estimated return levels, more attention should be given to frequency analysis of sub-daily rainfall over China, for improved water management and disaster reduction. 展开更多
关键词 sub-daily rainfall annual maxima regional frequency analysis return level eastern China
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Effects of Sub-chronic Intoxication of 1,8-cineole on Blood Biochemical Indexes of Mice 被引量:1
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作者 Du Yonghua Wang Chuan +5 位作者 Zhou Lijun Zhang Ping Wei Qin Yin Zhongqiong Jiang Qinjiu Jiang Jihong 《Animal Husbandry and Feed Science》 CAS 2015年第3期167-170,173,共5页
[ Objective] Effects of sub-chronic intoxication of 1,8-cineole on body weights, routine blood indexes and biochemical indexes of mice were investigated. [Method] One hundred and sixty mice with body weights of 15 -17... [ Objective] Effects of sub-chronic intoxication of 1,8-cineole on body weights, routine blood indexes and biochemical indexes of mice were investigated. [Method] One hundred and sixty mice with body weights of 15 -17 g were randomly divided into four groups (forty mice per group). Mice were injected to 1, 8 - cineole with doses of 192.45,64. 15 and 21.38 mg/kg body weight ( test groups) and the water solution of tween-80 with a volume fraction of 0.5% ( control group) respectively. Each mouse was administered orally at the dose of 0.2 mL per 10 g body weight once a day consecutively for 90 d. The body weight, routine blood indexes and serum biochemical indexes of mice were determined on the 30^th d, 60^th d, 90^th d and the 30^th d after stopping the administration of 1,8-cineole. [ Result] The effects of 1, 8-cineole on the body weight, routine blood indexes and serum biochemical indexes of mice with the doses of 64.15 and 21.38 mg/kg body weight had no statistically significant difference compared with the control group (P 〉0.05 ). 1, 8-cineole with the dose of 192.45 mg/kg body weight exhibited different influences on routine blood indexes and serum biochemical indexes of mice after the oral administration of 1,8-cineole for 60 d and 90 d, and statistically significant differences in many blood biochemical indexes were observed (P 〈 0.05 ). However, the differences in routine blood indexes and serum biochemical indexes were not statistically significant between the test groups and the control group at the 30'h d after stopping the administration of 1, 8-cineole ( P 〉 0.05). [Condusion] 1,8-cineole had sub-chronic oral toxicity to mice. The no observed adverse effect level (NOAEL) of 1,8-cineolc was 64.15 mg/kg body weight and the lowest observed adverse effect level (LOAEL) of 1,8-cineole was 192.45 mg/kg body weight. Effects of 1, 8-cineole on blood biochemical indexes of mice were in short term and reversible. 展开更多
关键词 1 8-cineole sub-chronic toxicity Lowest observed adverse effect level No observable adverse effect level
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Design on AM-OLED display control ASIC with high gray scale levels 被引量:4
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作者 季渊 冉峰 +3 位作者 徐洪光 沈伟星 稽维贵 徐美华 《Journal of Shanghai University(English Edition)》 CAS 2011年第4期310-315,共6页
The paper puts forward a method on controlling the AM-OLED panel to display image with high gray scale levels. It also gives an ASIC design sample to implement this method. A twenty sub-fields scan scheme has been tak... The paper puts forward a method on controlling the AM-OLED panel to display image with high gray scale levels. It also gives an ASIC design sample to implement this method. A twenty sub-fields scan scheme has been taken into use in the chip to display 256 gray scale levels on a QVGA resolution AM-OLED display screen. The functions of image scaling and rotating have also been implemented for multiply application. The simulation and chip test result show that the chip design has met the design requirements. 展开更多
关键词 active matrix organic light emitting display (AM-OLED) ASIC design gray scale level sub-field image scaling image rotation
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基于图像-文本大模型CLIP微调的零样本参考图像分割 被引量:3
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作者 刘杰 乔文昇 +2 位作者 朱佩佩 雷印杰 王紫轩 《计算机应用研究》 北大核心 2025年第4期1248-1254,共7页
近年来,以CLIP为代表的视觉-语言大模型在众多下游场景中显示出了出色的零样本推理能力,然而将CLIP模型迁移至需要像素水平图-文理解的参考图像分割中非常困难,其根本原因在于CLIP关注图像-文本整体上的对齐情况,却丢弃了图像中像素点... 近年来,以CLIP为代表的视觉-语言大模型在众多下游场景中显示出了出色的零样本推理能力,然而将CLIP模型迁移至需要像素水平图-文理解的参考图像分割中非常困难,其根本原因在于CLIP关注图像-文本整体上的对齐情况,却丢弃了图像中像素点的空间位置信息。鉴于此,以CLIP为基础模型,提出了一种单阶段、细粒度、多层次的零样本参考图像分割模型PixelCLIP。具体地,采取了多尺度的图像特征融合,既聚集CLIP中不同视觉编码器提取的图像像素级特征,同时又考虑CLIP中固有的图像整体语义特征。在文本信息表征上,不但依靠CLIP-BERT来保持物体种类信息,还引入LLaVA大语言模型进一步注入上下文背景知识。最后,PixelCLIP通过细粒度跨模态关联匹配,实现像素水平的参考图像分割。充分的数值分析结果验证了该方法的有效性。 展开更多
关键词 零样本 CLIP 像素级 单阶段 参考图像分割
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轴类工件圆度误差亚像素视觉检测和评定方法研究 被引量:1
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作者 袁奎 付恒勋 +3 位作者 谌立贵 秦东 吴怀超 王则皓 《现代制造工程》 北大核心 2025年第2期94-100,共7页
为解决现有轴类工件圆度误差检测方法存在的误差大、效率低和稳定性差等弊端,基于机器视觉技术提出了一种轴类工件圆度误差亚像素视觉检测和评定方法,该方法利用多项式插值-分段曲线拟合算法对图像边缘轮廓进行亚像素精确定位,在获取图... 为解决现有轴类工件圆度误差检测方法存在的误差大、效率低和稳定性差等弊端,基于机器视觉技术提出了一种轴类工件圆度误差亚像素视觉检测和评定方法,该方法利用多项式插值-分段曲线拟合算法对图像边缘轮廓进行亚像素精确定位,在获取图像边缘点亚像素级坐标的基础上,采用最小二乘法对圆心坐标进行检测,进而对轴类工件圆度误差进行检测和评定。实验结果表明,该方法测量值和三坐标测量机测量值绝对误差的平均值为8.75μm,且该方法测量的轴类工件圆度误差值分布较为均匀、波动性较小,且检测精度更高,为轴类工件圆度误差的评定提供了一种切实可行的途径。 展开更多
关键词 轴类工件 圆度误差 机器视觉 亚像素
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Sea Level Records on Ouvéa Island in New Caledonia
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作者 Nils-Axel Mörner 《Natural Science》 2020年第6期329-359,共31页
Ouvéa Island in New Caledonia emerges as a new sea level standard. It has excellent morphological records of former sea level positions at interglacial high-stands as well as records of Holocene changes in sea le... Ouvéa Island in New Caledonia emerges as a new sea level standard. It has excellent morphological records of former sea level positions at interglacial high-stands as well as records of Holocene changes in sea level from a maximum at about +1.5 m via a significant +70 cm level of sub-recent, probably 17<sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;"> century, age to a stable to falling sea level in present time.</span> 展开更多
关键词 Sea level Last Interglacial The Holocene sub-Recent Sea level 17th Century The Present
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Analysis of Local Diagnostic Reference Levels for Pediatric Patients Undergoing 18F-FDG PET/CT Imaging for Oncology
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作者 Saad Alqahtani Khaled Soliman +5 位作者 Saad Alotaibi Khaled Alnofaie Abdullah Alahmari Fahad Alyahya Abdullah Albdullah Rashed Alharbi 《Journal of Applied Mathematics and Physics》 2023年第7期2144-2155,共12页
Background: The PET/CT imaging studies have two doses components the dose from the PET radiopharmaceutical and the other from the low dose CT used for PET images attenuation correction. We have one PET/CT scanner at o... Background: The PET/CT imaging studies have two doses components the dose from the PET radiopharmaceutical and the other from the low dose CT used for PET images attenuation correction. We have one PET/CT scanner at our institution a Philips Time of Flight scanner. Our local patient’s radiation protection rules requires continuous assessment of radiation doses delivered to our patients. Purposes: The objectives of this study are to develop a weight- based facility DRLs for paediatric F-18-FDG PET-CT imaging for oncology in a large tertiary hospital and to determine whether the calculated DRLs compares with internationally published DRLs. Materials & Methods: Radiation dose data and patient demographics of two-hundreds and sixteen paediatric PET-CT oncology patients imaging procedures from one large tertiary hospital were selected and analysed in order to establish a facility paediatric DRLs. Statistical analysis was performed. Results: The PET dose reference levels ranged between [62 - 525] MBq of injected activity for a range of pediatric age groups. The CTDI<sub>vol</sub> values were between 3.5 and 16.5 mGy for all age groups. Comparison with current EANM and SNMMI recommendations of patient’s dose are discussed. Conclusion: Our pediatric PET/CT reference levels are higher than the ones reported internationally with notable variations. . 展开更多
关键词 Diagnostic Reference levels PET/CT 18-F-FDG Pediatric Radiation Dose CTDI<sub>volsub> ONCOLOGY
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Optimal Management of the Pension Contribution Rate Using the H-Control Theory
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作者 Alexandros A. Zimbidis 《Journal of Applied Mathematics and Physics》 2022年第12期3510-3523,共14页
In this paper, we construct a general model for a pension fund when there are time delays in the valuation process. Actually, we use the standard structure of the basic reserve equation in order to rebuild a more soph... In this paper, we construct a general model for a pension fund when there are time delays in the valuation process. Actually, we use the standard structure of the basic reserve equation in order to rebuild a more sophisticated approach based on the theory of H<sub>∞</sub> control. Our model evaluates the incomplete information from the delayed fund valuations—due to the oscillatory pattern for benefit claims and investment experience of the past years—within the context of uncertainty additionally to the randomness which certainly exists. So, we construct estimations for the optimal proposed contribution rates based on a feedback mechanism which is a robust stabilization controller, using typical linear matrix inequalities. Finally, a numerical application is fully investigated to obtain further insight into the problem. 展开更多
关键词 Defined Benefit Pension Schemes Pension Contributions and Fund levels H<sub>∞sub>-Control Linear Matrix Inequalities
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基于PRBS的中压直流系统宽频阻抗测量装置及其控制 被引量:2
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作者 季振东 朱述超 +3 位作者 许光强 王建华 赵剑锋 肖小龙 《电力系统自动化》 北大核心 2025年第9期199-207,共9页
随着直流系统中电力电子化程度的加深,电力电子装置的端口阻抗特性对系统稳定性产生了一定影响。为了获取中压直流系统的阻抗特性用以评估系统稳定性,文中对宽频阻抗测量装置展开了研究。首先,以伪随机二进制序列(PRBS)作为输出扰动测... 随着直流系统中电力电子化程度的加深,电力电子装置的端口阻抗特性对系统稳定性产生了一定影响。为了获取中压直流系统的阻抗特性用以评估系统稳定性,文中对宽频阻抗测量装置展开了研究。首先,以伪随机二进制序列(PRBS)作为输出扰动测量信号,提出了一种混合子模块级联多电平拓扑的阻抗测量装置;然后,在此基础上提出了基于子模块分类的集中式调制方法,通过子模块4种工作模式的划分和配合来实现PRBS信号的高质量输出,实现子模块电容电压均衡,有利于降低开关损耗,并设计了相关主电路参数的计算原则。最后,硬件在环仿真结果验证了所提控制方法的有效性,表明所提阻抗测量装置具备良好的输出效果,能够在满足阻抗测量需求的前提下提高测量效率。 展开更多
关键词 中压直流系统 阻抗测量 伪随机二进制序列(PRBS) 级联多电平拓扑 集中式调制 混合子模块 电容均压
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Analytic Solution of a Two-Level Model Coupled by Y_(5,μ)Field
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作者 Zhang Xi-zhen Dong Bao-guo Liu Bin(China Institute of Atomic Energy,P.O.Box 275,Beijing 102413) 《Chinese journal of nuclear physics》 1995年第2期142-148,共7页
An analytic solution of a two-level model coupled by Y<sub>5μ</sub> field was given inthe limit of large angular momentum 11.
关键词 TWO-level MODEL Y<sub>5μsub>-deformation Metallic CLUSTERS
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Symmetry of Y_5 Deformation and Two-Level Model
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作者 Zhang Xi-zhen~(1,2) Dong Bao-guo~(1)(1 China Institute of Atomic Energy,P.O.Box 275(18),Beijing 102413)(2 Institute of Theoretical Physics,Chinese Academy of Science,Beijing 100080) 《Chinese journal of nuclear physics》 1994年第4期337-343,共7页
The symmetry of Y<sub>5μ</sub>-deformed fields are classified and the one-particlespectra in two-level model coupled by Y<sub>5μ</sub> fields are discussed.
关键词 Y<sub>5μsub>-deformed clusters TWO-level MODEL Single particle
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基于SVM模型的亚像素位移测量方法的研究 被引量:1
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作者 沈澍 孙磊磊 +2 位作者 孙义杰 张浩 王森 《小型微型计算机系统》 北大核心 2025年第5期1156-1160,共5页
亚像素位移测量算法常见的有曲面拟合法、梯度法和插值法等,论文介绍了一种基于支持向量机(SVM)模型的亚像素位移测量方法,提出一种用于计算物体移动前后两幅图像的相关值来表征亚像素位移的梯度加权求和法.利用计算机模拟生成一系列以0... 亚像素位移测量算法常见的有曲面拟合法、梯度法和插值法等,论文介绍了一种基于支持向量机(SVM)模型的亚像素位移测量方法,提出一种用于计算物体移动前后两幅图像的相关值来表征亚像素位移的梯度加权求和法.利用计算机模拟生成一系列以0.001pixel步调的图像,其中70%作为训练集,30%作为测试集,为了检验该模型抗噪性,在生成的图像中添加不同方差的高斯噪声,并将其与曲面拟合法和梯度法进行比较,结果表明在精度要求为0.01pixel时,采用SVM法在保证高精度的情况下其抗噪性优于曲面拟合法和梯度法,其噪声方差上限为0.015,具有很好的鲁棒性可用于实际物体位移的高精度测量. 展开更多
关键词 支持向量机(SVM) 亚像素位移 数字图像相关法(DICM) 梯度加权求和法 高斯噪声
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基于直纹曲面模型的测量图像亚像素边缘定位
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作者 张静 赵文辉 +2 位作者 杜坡 赵文珍 张明 《农业机械学报》 北大核心 2025年第10期802-808,共7页
针对现有亚像素边缘定位算法复杂难解、检测精度不高和计算速度较慢等问题,本文提出一种基于直纹曲面模型的边缘检测算法。采用sigmoid曲面模型代替传统高斯积分曲面模型表征测量图像边缘,利用模型反函数可求特性,在获取像素级边缘的基... 针对现有亚像素边缘定位算法复杂难解、检测精度不高和计算速度较慢等问题,本文提出一种基于直纹曲面模型的边缘检测算法。采用sigmoid曲面模型代替传统高斯积分曲面模型表征测量图像边缘,利用模型反函数可求特性,在获取像素级边缘的基础上,对像素级边缘灰度矩阵进行对数变换,对变换后矩阵元素进行光强补偿,从而标定图像饱和度不足或过盈带来的误差。搭建视觉测量系统,采用背光源照明的方式获取清晰的测量图像,使用点阵标定板确定像素当量Ar为19.4721μm/像素,应用量块标定出光强补偿系数ΔLs为0.13。量块边缘定位误差试验结果表明,相比于高斯曲面拟合算法,基于直纹曲面模型的边缘检测算法定位亚像素边缘更平滑,直线度误差为0.6μm,相同软硬件条件下计算效率提升3.3倍,测量精度从3.3μm提升到1μm。将本文算法应用于内齿轮齿廓总偏差测量,采集齿轮图像后定位出齿圈外圆弧和内齿轮齿廓亚像素边缘点,由外圆弧边缘点确定内齿轮中心,计算齿廓边缘点初始相位角,根据齿廓总偏差计算模型计算出齿廓总偏差,其误差均低于国家标准最大允许值,表明该视觉边缘定位算法可以应用于高精度机械零件测量。 展开更多
关键词 视觉测量 直纹曲面模型 边缘定位 SIGMOID 亚像素
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基于线结构光的焊缝光条亚像素中心提取方法
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作者 杨宏韬 李浩 +3 位作者 白昊天 程云龙 李秀兰 张鹏 《组合机床与自动化加工技术》 北大核心 2025年第4期66-70,77,共6页
随着工业的迅速发展,线结构光在焊缝检测中的应用越发广泛,针对线结构光测量中焊缝特征区域曲率变化大引起的光条灰度分布不均匀,从而导致提取中心存在一定偏差的问题,提出一种基于线结构光的焊缝光条亚像素中心提取方法。该方法主要包... 随着工业的迅速发展,线结构光在焊缝检测中的应用越发广泛,针对线结构光测量中焊缝特征区域曲率变化大引起的光条灰度分布不均匀,从而导致提取中心存在一定偏差的问题,提出一种基于线结构光的焊缝光条亚像素中心提取方法。该方法主要包括初始提取和精细提取两个阶段,在图像预处理的基础上,采用骨架细化法对光条中心初始提取;在精细提取阶段,利用Hessian矩阵求解其绝对值最大特征值对应的特征向量确定初始中心法向,最后在初始中心法向上引入灰度质心的思想,对法向像素集灰度进行二次平方加权计算,获取准确的亚像素中心。实验表明,所提方法解决了光条曲率变化较大的干扰问题,提取的平均偏差为0.224 7 pixel,满足工业测量的要求。 展开更多
关键词 线结构光 焊缝中心 骨架细化 HESSIAN矩阵 亚像素
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