نتایج جستجو برای: spatial correlation

تعداد نتایج: 731324  

2011
Ian Paul Holman Monica Rivas-Casado John P. Bloomfield Jason J. Gurdak

The first comprehensive use of wavelet methods to identify non-stationary time-frequency relations between North Atlantic ocean-atmosphere teleconnection patterns and groundwater levels is described. Long-term hydrogeological time series from three boreholes within different aquifers across the UK are analysed to identify statistically significant wavelet coherence between the North Atlantic Os...

2015
Meng Gong Yang Shen Hongyi Li Xinfu Li Jinsheng Jia

Continuous data recorded at 39 broadband stations near the Longmen Shan Fault operated by the China Earthquake Administration from 1 January 2008 to 30 September 2010 are used to study temporal variability in direct surface wave arrivals extracted from ambient noise. We use a cross-correlation technique to compute Empirical green functions (EGFs) for all available station pairs at the frequency...

2016
Xiaoyuan Zhang Jianghua Wu Zhongyi Man Jose L. Gómez Alan P. Marscher Svetlana G. Jorstad

We present the results of simultaneous optical multi-color observations of BL Lac object 0716+714 in November 2014 and February 2016. The intra-day variability (IDV) varies from 0.04 to 0.3 mags. Both achromatic and bluer-when-brighter (BWB) color behaviors were detected. A probable quasi-periodic oscillation overlapping on a significant flare was also observed. We used the interpolated cross-c...

2008
Marie-Noëlle Célérier

Standard cosmology is based on the assumption that the universe is spatially homogeneous. However the consensus on a homogeneous matter structure, even on very large scales, has never been complete. The advantage of correlation dimension calculations is that they enable one to obtain the transition scale to a homogeneous distribution, whereas other methods, such as those using the two-point cor...

2016
Romain Escudier Baptiste Mourre

Algerian eddies are the strongest and largest propagating mesoscale structures in the Western Mediterranean Sea. They have a large influence on the mean circulation, water masses and biological processes. Over 20 years of satellite altimeter data have been analyzed to characterize the propagation of these eddies using automatic detection methods and cross-correlation analysis. We found that, on...

2014
Peter M. Robinson Francesca Rossi

We consider testing the null hypothesis of no spatial correlation against the alternative of pure first order spatial autoregression. A test statistic based on the least squares estimate has good first-order asymptotic properties, but these may not be relevant in small or moderate-sized samples, especially as (depending on properties of the spatial weight matrix) the usual parametric rate of co...

Journal: :Optics letters 2007
F Gori M Santarsiero

The choice of the mathematical form of spatial correlation functions for optical fields is restricted by the constraint of nonnegative definiteness. We discuss a sufficient condition for ensuring the satisfaction of such a constraint.

Journal: :IEEE Trans. Circuits Syst. Video Techn. 2003
Lei Zhang Paul Bao

This paper presents a spatial-correlation thresholding scheme for noise reduction by wavelet transform. Observing that edge structures are of high magnitude across wavelet scales but noise decays rapidly, we multiply two adjacent wavelet scales to form a spatial-correlation function to enhance significant structures and dilute noise. Dissimilar to the traditional thresholding schemes that apply...

Journal: :تحقیقات نظام سلامت 0
حدیث نجفی مهر کارشناسی ارشد، گروه آمار زیستی، دانشکده پیراپزشکی، دانشگاه علوم پزشکی شهید بهشتی، تهران، ایران امیر کاوسی دانشیار، گروه علوم پایه، دانشکده سلامت، ایمنی و محیط زیست، دانشگاه علوم پزشکی شهید بهشتی، تهران، ایران

background : the restriction in resources of health services renders the prioritization of the distribution of these resources necessary. the health care need index is used to investigate equality in distribution of health services. the main aim of the current study was to estimate this index for skin cancer in iran by involving the effect of adjacent regions. methods: the present study was a c...

Journal: :Journal of Agricultural, Biological, and Environmental Statistics 2007

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