Results 11 to 20 of about 374,705 (148)
Guangtongxin yanjiu, 2020 针对分数阶傅里叶变换（FRFT）对啁啾（Chirp）信号进行盲检测时存在运算量大的问题,文章提出一种针对Chirp信号参数估计的盲检测方法。首先利用改变窗长相位差法对Chirp信号进行粗估计,并利用最小二乘法进行拟合得到Chirp信号调频斜率粗估计值,然后通过FRFT对Chirp信号进行精细估计,并利用二分法对FRFT的阶次进行搜索,进一步降低算法的运算量。仿真结果表明,利用改变窗长相位差法和FRFT联合检测Chirp信号的方法,在低信噪比下具有较高精度的估计值,且其归一化均方误差接近克拉美罗下界 ...
廖烨, 刘国峰, 李康, 周文峰
doaj +2 more sources
全球能源互联网, 2022 随着“双碳”背景下新型电力系统的建设，传统的单一供能网络逐渐发展成为多能耦合的综合能源系统。综合能源系统在信息采集和传输过程中会不可避免地出现量测误差，而传统的加权最小二乘法无法抑制其影响，影响状态估计的精度。为此，提出一种考虑量测误差的电热综合能源系统状态估计方法。首先，在考虑电力系统、热力系统以及耦合元件运行特性的基础上，建立电热综合能源系统量测模型。其次，将基于Huber估计的抗差状态估计方法拓展到电热综合能源系统中，提出电热综合能源系统抗差状态估计方法，并对电热耦合系统进行冗余度分析。最后 ...
李晓 +5 more
doaj +1 more source
The Photogrammetric Record, Volume 37, Issue 179, Page 285-305, September 2022., 2022 This paper aims to study and quantify the induced error due to the deflection of verticals (DOV) when integrating different sensors, focusing on GNSS and INS for 3D mapping in airborne mapping. It is shown that the DOV effect should be considered for direct georeferencing because the DOV components are in the order of (or larger than) INS uncertainty ...
Mohammad Bagherbandi +3 more
wiley +1 more source
Translating habitat class to land cover to map area of habitat of terrestrial vertebrates
Conservation Biology, Volume 36, Issue 3, June 2022., 2022 Abstract Area of habitat (AOH) is defined as the “habitat available to a species, that is, habitat within its range” and is calculated by subtracting areas of unsuitable land cover and elevation from the range. The International Union for the Conservation of Nature (IUCN) Habitats Classification Scheme provides information on species habitat ...
Maria Lumbierres +5 more
wiley +1 more source
First‐trimester ultrasound detection of fetal heart anomalies: systematic review and meta‐analysis
Ultrasound in Obstetrics &Gynecology, Volume 59, Issue 1, Page 11-25, January 2022., 2022 ABSTRACT Objectives To determine the diagnostic accuracy of ultrasound at 11–14 weeks' gestation in the detection of fetal cardiac abnormalities and to evaluate factors that impact the detection rate. Methods This was a systematic review of studies evaluating the diagnostic accuracy of ultrasound in the detection of fetal cardiac anomalies at 11–14 ...
J. N. Karim +26 more
wiley +1 more source
Bridging gaps in demographic analysis with phylogenetic imputation
Conservation Biology, Volume 35, Issue 4, Page 1210-1221, August 2021., 2021 Abstract Phylogenetically informed imputation methods have rarely been applied to estimate missing values in demographic data but may be a powerful tool for reconstructing vital rates of survival, maturation, and fecundity for species of conservation concern.
Tamora D. James +4 more
wiley +1 more source
Automated calibration of smartphone cameras for 3D reconstruction of mechanical pipes
The Photogrammetric Record, Volume 36, Issue 174, Page 124-146, June 2021., 2021 A framework for the laboratory calibration of smartphone cameras is proposed, introducing new methods for: (i) matching calibration targets; (ii) adjusting target eccentricity error without object‐space target information; and (iii) improving the calibration using a free‐network self‐calibrating bundle adjustment.
Reza Maalek, Derek D. Lichti
wiley +1 more source
Dizhen xuebao, 2022 对Lg波衰减模型中建模误差的统计特征进行了系统研究，并建立了地壳二维Lg波衰减模型。由于Lg波振幅可能受到几何扩散函数的强烈影响，合理评估反演过程的误差对于能否使用最小二乘意义下的反演非常重要。通过在川滇及其邻近地区收集的建模误差样本，使用K-S数值检验方法、Q-Q图和正态分布图形检验方法对Lg波衰减层析成像反演的输入数据中建模误差的分布特征进行了统计分析。采用奇异值分解（SVD）和反投影方法，分别获得了川滇地区的QLg模型，定量计算模型的协方差矩阵和分辨率矩阵 ...
Yansong Hu +3 more
doaj +1 more source
The bean method as a tool to measure sensitive behavior
Conservation Biology, Volume 35, Issue 2, Page 722-732, April 2021., 2021 Abstract Conservationists need to measure human behavior to guide decisions and evaluate their impact. However, activities can be misreported and reporting accuracy may change following conservation interventions, making it hard to verify any apparent changes.
Sorrel Jones +4 more
wiley +1 more source
, 2022 本发明属于光学流场诊断领域，针对视线非均匀吸收光谱测量中的关键中间变量积分吸光度，提供了一种积分吸光度测量误差估计方法，对视线非均匀流场下TDLAS方法测量结果的质量评估提供了输入参数。该方法包括如下步骤：第一步，基于测量所用吸收线型与线型参数范围计算非均匀性误差分布表；第二步，计算所用吸收线在非均匀流场的线型参数分布；第三步，根据测量流场线型参数分布查找非均匀性误差R1；第四步，计算非均匀流场下由吸收线重叠导致的积分吸光度误差R2；第五步，将误差R1与R2叠加得到积分吸光度估计误差R ...
李仁杰, 余西龙, 林鑫, 李飞
core +2 more sources