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Application of multichannel analysis of passive surface waves method for fault investigation

JOURNAL OF APPLIED GEOPHYSICS 2021年 192卷 104382-104382页

作者： Ning, Ling Dai, Tianyu Liu, Ya Xi, Chaoqiang Zhang, Hao Zhou, Changwei Zhejiang Univ Key Lab Geosci Big Data & Deep Resource Zhejiang Sch Earth Sci Hangzhou 310027 Peoples R China Nanchang Univ Sch Informat Engn Nanchang 330031 Jiangxi Peoples R China

Research on faulting is of fundamental significance to the exploration of geothermal resources since faulting is an important factor in the formation of traps for water accumulation. The high-frequency passive surface waves methods using ambient noise data become more popular because of its low-cost, environment-friendly, non-destructive and efficient advantages. We have conducted a field work in Hetian town of Zhejiang Province to evaluate the feasibility of high-frequency passive surface wave survey for fault investigation. We adopted the multichannel analysis of passive surface waves (MAPS) to process the high-frequency (>1 Hz) ambient noise for retrieving surface waves. Spectral analysis indicated that the dominant energy of ambient noise is focused on the frequency band from 1 to 12 Hz. We utilized the beamforming technique to show the distribution of ambient noise energy and the stable phase-velocity range of plane wave and reveal the location of interior sources in the receiver array. We selected these segments with less interior-source contamination from noise data collected at night to obtain clear and continuous surface-wave dispersion energy. The cross-correlation functions are obtained from ambient noise to acquire accurate phase velocity of surface waves. The dispersion curves of surface waves are inverted for shear (S)-wave velocity profiles. The faults revealed in the inversion profiles match well with the previous geological references. The inverted S-wave velocity profiles are consistent with the results of controlled source audio-magnetotelluric in terms of the characteristics of the layered structures. Our synthetic and real-world tests demonstrated that the waveforms of virtual shot gathers and dispersion images of surface waves are affected by interior sources of a receiver array. Results indicated that the survey arrays should be distributed along roads instead of crossing them. The success of this case study showed that MAPS has the great pote

关键词： High-frequency ambient noise Passive surface waves cross-correlation functions S-wave velocity profiles

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Islamic and conventional equity markets: Two sides of the same coin, or not?

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QUARTERLY REVIEW OF ECONOMICS AND FINANCE 2019年 72卷 191-205页

作者： Ahmed, Waild M. A. Ahmed Bin Mohamed Mil Coll Dept Management POB 22988 Doha Qatar

This study undertakes an empirical analysis of both mean and variance dynamics between the MSCI ACWI Islamic stock index on the one hand and three conventional counterparts for the US, developed, and GCC markets on the other. The investigation is carried out in the context of the modified cross-correlation function testing procedure of Hong (2001), after filtering out the effect of a diverse set of global influences and risk factors and accounting for regime shifts in the conditional second moment dynamics. The empirical evidence reveals the presence of substantial mean and volatility spillovers radiating from the mainstream stock market indices to their Sharia-compliant counterpart, with the opposite direction being largely negated. The findings invalidate the dichotomous distinction between conventional and Islamic stock markets. Practical implications for investors and portfolio managers are drawn from the results. (C) 2019 Board of Trustees of the University of Illinois. Published by Elsevier Inc. All rights reserved.

关键词： Islamic and conventional equity markets Causality-in-mean Causality-in-variance Volatility breaks cross-correlation functions

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Optimal Receiving and Estimation Parameters of Pseudorandom Signals of Nonlinear Dynamical Systems

Optimal Receiving and Estimation Parameters of Pseudorandom ...

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Wave Electronics and its Application in Information and Telecommunication Systems (WECONF)

作者： Nasyrov, I. K. Andreev, V. V. Kazan State Power Engn Univ Kazan Russia

ISBN: (纸本)9781538676325

The noise-like signals are widely adopted now in the wideband communications systems as they provide high noise protection of the communications system and the compatibility of information transmission with measurement of object motion parameters in system of moving communications system. Chaotic signals generated of nonlinear dynamical systems are noise-like ones inherently and therefore can be considered as the base for construction of communications systems with high noise protection. With the purpose of development of the pseudorandom signals nonlinear dynamical system optimal receive the problem of construction of functional of maximal likelihood is considered and cross-correlation functions are analyzed an examples of the dynamic chaotic systems of the type Lorenz and Rossler. The base of the suggested algorithm is maximal likelihood method and also presentation of nonlinear differential equations system as the stochastic differential equations systems)

关键词： pseudorandom signals optimal receiving and estimation parameters nonlinear dynamical systems stochastic differential equations Lorenz Ressler systems cross-correlation functions

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On the interdependence of natural gas and stock markets under structural breaks

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QUARTERLY REVIEW OF ECONOMICS AND FINANCE 2018年 67卷 149-161页

作者： Ahmed, Walid M. A. Ain Shams Univ Fac Commerce Dept Business Adm POB 11566 Cairo Egypt

This paper aims to provide an analysis of both mean and variance dynamics between natural gas and stock markets, using the gas-rich Gulf state of Qatar as a case study. The empirical investigation is conducted in the context of the modified cross-correlation function testing procedure of Hong (2001), after removing the influence of relevant regional and international factors and controlling for structural breaks in the conditional volatility process of either market. The results reveal the presence of mean and volatility spillovers from natural gas prices to stock prices in Qatar's emerging market, with the opposite direction being denied. The speed with which the stock market absorbs and reacts to variations in gas prices turns out to be somewhat slow. The findings have important implications for investors and policymakers. (C) 2017 Board of Trustees of the University of Illinois. Published by Elsevier Inc. All rights reserved.

关键词： Natural gas market Qatar Exchange Causality-in-mean Causality-in-variance Volatility breaks cross-correlation functions

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The Weight Distribution for an Extended Family of Reducible Cyclic Codes 2nd

The Weight Distribution for an Extended Family of Reducible ...

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2nd International Conference on Codes, Cryptology and Information Security (C2SI) In Honor of Claude Carlet

作者： Vega, Gerardo Cuen-Ramos, Jesus E. Univ Nacl Autonoma Mexico Direcc Gen Computo & Tecnol Informac & Comunicac Mexico City 04510 DF Mexico Univ Nacl Autonoma Mexico Posgrad Ciencias Matemat Mexico City 20059 DF Mexico

ISBN: (纸本)9783319555898;9783319555881

The purpose of this work is to present new advances on the weight distribution of the duals of some cyclic codes with two zeros. More specifically, our contribution improves the sufficient numerical conditions that determine the weight distribution for the class of reducible cyclic codes that were studied in [19] and in [17]. Furthermore, as will be shown later, a conclusion here will be that thanks to these previous works and the present contribution, we can determine the weight distribution for an extended family of reducible cyclic codes. More specifically, we are going to determine the weight distribution for all the elements of an extended family of reducible cyclic codes that fully covers one of the open cases suggested in [20]. In addition, as will be seen further on, through our results we obtain an alternative description for one of the families of cross-correlation functions studied in [8].

关键词： Weight distribution Reducible cyclic codes Gaussian periods cross-correlation functions

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Computer Aided Analysis of EMI Radiated from Printed Circuit Boards

Computer Aided Analysis of EMI Radiated from Printed Circuit...

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URSI Atlantic Radio Science Meeting

作者： Michael Haider Johannes A. Russer Technical University of Munich Munich Germany

ISBN: (纸本)9781538637647

In this paper, we describe a procedure for computer aided characterization of radiated emissions of printed circuit boards. Noisy electromagnetic fields are thereby modeled as Gaussian stochastic processes. From the auto- and cross-correlation functions of the fields, sampled at different locations, we obtain the spectral energy density on a plane close above the device under test. Based on a characterization by field correlations, we can assess the impact of different parts of the printed circuit board on other parts of the system due to radiated EMI.

关键词： cross-correlation functions characterization field correlations

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The role of local and regional processes on population synchrony along the gradients of habitat specialization

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ECOSPHERE 2016年第5期7卷 n/a-n/a页

作者： Pandit, Shubha N. Cottenie, Karl Enders, Eva C. Kolasa, Jurek McMaster Univ Dept Biol 1280 Main St West Hamilton ON L8S 4K1 Canada Fisheries & Oceans Canada Inst Freshwater 501 Univ Crescent Winnipeg MB R3T 2N6 Canada Univ Guelph Dept Integrat Biol Guelph ON N1G 2W1 Canada Terraqua Inc Terr & Aquat Appl Res & Management 2989 Entiat River Rd Entiat WA 98822 USA

Metacommunity perspective highlights the role of space as a factor contributing to local community structure and dynamics. Often tests of metacommunity models rely on snapshot patterns of species distribution and abundance. Such patterns may introduce biases because they overlook differences in responses of constituent species to changing environmental conditions, particularly when such responses override patterns predicted from dispersal and biotic interactions alone. This applies, for example, to habitat generalists, whose responses to environmental variations differ from those of habitat specialists, resulting in different snapshot patterns at different times. Synchronized (i.e., correlated among sites) environmental variation is perhaps the most obvious case of environmental variation that could generate regular differences among species of different specialization. We hypothesized that synchronized environmental variation synchronizes local populations of habitat specialists to a greater degree than it does for habitat generalists as experiments have shown that habitat generalists are less sensitive to changing environmental conditions. To test this in an empirical system, we used time series data (nine annual surveys) on an invertebrate metacommunity of 49 rock pools on the coast of Jamaica. We found that population synchrony of a significant portion of 24 species sharing these rock pools increased with habitat specialization in response to environmental synchrony (represented by synchrony of environment). However, distance among rock pools, which may affect dispersal or shared perturbations, was negatively correlated with population synchrony of individual species, irrespective of their specialization. As only habitat specialists showed increasing synchrony with environmental synchrony, and both generalist and specialist synchrony were negatively correlated with distance, we infer that habitat generalists must be synchronized more by space-related processes w

关键词： cross-correlation functions habitat generalists habitat specialists invertebrates metacommunity population synchrony temporal dynamics

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Memory-induced sign reversals of the spatial cross-correlation for particles in viscoelastic shear flows

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CHAOS SOLITONS & FRACTALS 2015年第PartB期81卷 443-450页

作者： Sauga, Ako Laas, Katrin Mankin, Romi Tallinn Univ Inst Math & Nat Sci EE-10120 Tallinn Estonia

The behavior of shear-induced cross-correlation functions between particle fluctuations along orthogonal directions in the shear plane for harmonically trapped Brownian particles in a viscoelastic shear flow is studied. A generalized Langevin equation with a power-law-type memory kernel is used to model the complex structure of the viscoelastic media. Interaction with fluctuations of environmental parameters is modeled by a multiplicative white Gaussian noise, by an internal fractional Gaussian noise, and by an additive external white noise. It is shown that the presence of a memory has a profound effect on the behavior of the cross-correlation functions. Particularly, memory-induced reentrant sign reversals of the spatial cross-moment between orthogonal random displacements of a particle are established, i.e., an increase of the memory exponent can cause the sign reversal from positive to negative, but by a further increase of the memory exponent a reentrant transition from negative to positive values appears. Similarities and differences between the behavior of the models with additive internal and external noises are considered. It is shown that additive external and internal noises cause qualitatively different dependencies of the cross-correlation functions on the time lag. The occurrence of energetic instability due to the influence of multiplicative noise is also discussed. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Viscoelastic friction Internal noise External noise Shear flow Brownian particle cross-correlation functions

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RESULTS OF USING THE METHOD OF SUCCESSIVE FREQUENCY SYNTHESIS ON RT-22 AT 18-26 GHz 24

RESULTS OF USING THE METHOD OF SUCCESSIVE FREQUENCY SYNTHESI...

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24th International Crimean Conference Microwave & Telecommunication Technology (CriMiCo)

作者： Volvach, L. N. Volvach, A. E. Larionov, M. G. Kostenko, V., I Litovchenko, I. D. Crimean Astrophys Observ Radio Astron Lab Katsiveli 298688 Yalta Russia RAS PN Lebedev Phys Inst Ctr Astro Space Moscow 117810 Russia

ISBN: (纸本)9789663354125

The results ofVLBI observations between the RT-22 (Simeiz) and RT-70 (Yevpatoriya) using the method of successive frequency synthesis at 18-26 GHz within the framework of "Radioastron" project are presented. The cross-correlation functions for five active galactic nuclei (BL Lac, 2145+067, 3C454.3, 3C84, 0528+134) and two sources in watervapor line (W3OH and ORION KL) are determined.

关键词： radioastronomical techniques radioastronomy radiowave interferometry 0528+134 2145+067 3C454.3 3C84 BL Lac ORION KL RT-22 RT-70 Radioastron project Simeiz VLBI observations W3OH Yevpatoriya active galactic nuclei cross-correlation functions frequency 18 GHz to 26 GHz successive frequency synthesis water vapor line

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Measurement and simulation of neutron/gamma-ray cross-correlation functions from spontaneous fission

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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2008年第2期595卷 426-430页

作者： Enqvist, Andreas Flaska, Marek Pozzi, Sara Chalmers Dept Nucl Engn SE-41296 Gothenburg Sweden Univ Michigan Dept Nucl Engn & Radiol Sci Ann Arbor MI 48109 USA

For the first time, a technique is presented for the measurement of total and separate neutron and gamma-ray cross-correlation functions from a spontaneous fission source. The cross-correlation functions are unique for given material-geometry configuration, thus represent signatures that can be used for the identification of radioactive materials. The measurement technique allows for the collection of fast coincidences within a time window of the order of a few tens of nanoseconds. A digital pulse shape discrimination technique is used, which allows for the accurate acquisition of the coincidences in all particle combinations. Specifically, separate neutron-neutron, neutron-gamma-ray, gamma-ray-neutron, and gamma-ray-gamma-ray coincidences are acquired with two liquid scintillation detectors. The measurements are compared to results obtained with the MCNP-PoliMi code, which simulates neutron and gamma-ray coincidences from a source on an event-by-event basis. This comparison leads to relatively good qualitative agreement. The measurements and simulations of the separate neutron and gamma-ray contributions to the total cross-correlations provide new signatures that can be obtained using existing experimental systems built to accurately identify nuclear materials. This research has direct applications in the areas of nuclear nonproliferation and homeland security. (C) 2007 Elsevier B.V. All rights reserved.

关键词： Nuclear nonproliferation Pulse shape discrimination Liquid scintillator detectors cross-correlation functions Coincidences

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