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Probing signals of atmospheric gravity waves excited by the July 29,2021 M_(W)8.2 Alaska earthquake

Geodesy and Geodynamics 2024年第3期15卷 219-229页

作者： Geng Zhang Jianqiao Xu Xiaodong Chen Heping Sun Lizhuo Gong State Key Laboratory of Geodesy and Earth's Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan430077China University of Chinese Academy of Sciences Beijing100049China

It is commonly believed that the atmosphere is decoupled from the solid ***,it is difficult for the seismic wave energy inside the Earth to propagate into the atmosphere,and atmospheric pressure wave signals excited by earthquakes are unlikely to exist in atmospheric *** increasing number of studies have shown that earthquakes,volcanoes,and tsunamis can perturb the Earth's atmosphere due to various coupling ***,the observations mainly focus on acoustic waves with periods of less than 10 min and inertial gravity waves with periods of greater than 1 *** are almost no clear observations of gravity waves that coincide with observations of low-frequency signals of the Earth's free oscillation frequency band within 1 *** paper investigates atmospheric gravity wave signals within1 h of surface-atmosphere observations using the periodogram method based on seismometer and microbarometer observations from the global seismic network before and after the July 29,2021 M_(w)8.2 Alaska earthquake in the United *** numerical results show that the atmospheric gravity wave signals with frequencies similar to those of the Earth's free oscillations _(0)S_(2) and _(0)T_(2) can be detected in the microbaro meter *** results con firm the existence of atmospheric gravity waves,indicating that the atmosphere and the solid Earth are not decoupled within this frequency band and that seismic wave energy excited by earthquakes can propagate from the interior of the Earth to the atmosphere and enhance the atmospheric gravity wave signals within 1 h.

关键词： Atmospheric gravity modes Atmospheric gravity waves Alaska earthquake normal modes Coupling of solid earth and atmosphere

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Finite-Time normal Mode Disturbances and Error Growth During Southern Hemisphere Blocking

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Advances in Atmospheric Sciences 2005年第1期22卷 69-89页

作者： Jorgen S.FREDERIKSEN CSIRO Atmospheric Research

The structural organization of initially random errors evolving in abarotropic tangent linear model, with time-dependent basic states taken from analyses, is examinedfor cases of block development, maturation and decay in the Southern Hemisphere atmosphere duringApril, November, and December 1989. The statistics of 100 evolved errors are studied for six-dayperiods and compared with the growth and structures of fast growing normal modes and finite-timenormal modes (FTNMs). The amplification factors of most initially random errors are slightly lessthan those of the fastest growing FTNM for the same time interval. During their evolution, thestandard deviations of the error fields become concentrated in the regions of rapid dynamicaldevelopment, particularly associated with developing and decaying blocks. We have calculatedprobability distributions and the mean and standard deviations of pattern correlations between eachof the 100 evolved error fields and the five fastest growing FTNMs for the same time interval. Themean of the largest pattern correlation, taken over the five fastest growing FTNMs, increases withincreasing time interval to a value close to 0.6 or larger after six days. FTNM 1 generally, but notalways, gives the largest mean pattern correlation with error fields. Corresponding patterncorrelations with the fast growing normal modes of the instantaneous basic state flow aresignificant' but lower than with FTNMs. Mean pattern correlations with fast growing FTNMs increasefurther when the time interval is increased beyond six days.

关键词： normal modes finite-time normal modes blocking tangent linear model pattern correlations

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Observation of double pseudowaves in an ion-beam-plasma system

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Chinese Physics B 2018年第8期27卷 350-355页

作者：卫子安马锦秀弋开阳 Department of Modern Physics and CAS Key Laboratory of Geospace Environment University of Science and Technology of China

Pseudowaves, known as burst-ion signals, which are different from plasma normal modes, exist frequently in ion- wave excitation experiments when launching the waves by applying a pulsed voltage to a negatively biased grid. In previous experiments, only one kind of the pseudowave was observed. In this paper, we report the observation and identification of double pseudowaves in an ion-beam-plasma system. These pseudowaves originate from two ion groups： the burst of the beam ions and the burst of the background ions. It was observed that the burst of the background ions was in the case of high ion beam energy, while the burst of the beam ions was in the case of low ion beam energy. By observing the dependence of the signal velocities on the characteristics of the excitation voltage, these pseudowaves can be identified. It was also observed that the burst ion signal originating from the background ions can interact with slow beam mode and that originating from the beam ions can interact with fast beam mode.

关键词： ion-beam-plasma system normal modes pseudowaves wave-particle interaction

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Optimal configuration for vibration frequencies in a ring of harmonic oscillators： The nonidentical mass effect

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Frontiers of physics 2015年第3期10卷 89-100页

作者： Shuai Liu Guo-Yong Zhang Zhiwei He Meng Zhan College of Science Northwest A&F University Yangling 712100 China Wuhan Center for Magnetic Resonance State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071 China College of Computer Science and Technology Hubei Normal University Huangshi 435002 China University of the Chinese Academy of Sciences Beijing 100049 China

The parameter diversity effect in coupled nonidentical elements has attracted persistent interest in nonlinear dynamics. Of fundamental importance is the so-called optimal configuration problem for how the spatial position of elements with different parameters precisely determines the dynamics of the whole system. In this work, we study the optimal configuration problem for the vibration spectra in the classical mass-spring model with a ring configuration, paying particular attention to how the configuration of different masses affects the second smallest vibration frequency （ω2） and the largest one （ωN）. For the extreme values of ω2 and ωN, namely, （ω2）min, （ω2）max, （ωN）min, and （ωN）max, we find some explicit organization rules for the optimal configurations and some approximation rules when the explicit organization rules are not available. The different distributions of ω2 and ωN are compared. These findings are interesting and valuable for uncovering the underlying mechanism of the parameter diversity effect in more general cases.

关键词： synchronization vibration frequencies normal modes complex systems

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Catechin and Epicatechin. What’s the More Reactive?

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Computational Chemistry 2022年第2期10卷 53-70页

作者： Essoh Akpa Eugène N’guessan Boka Robert Adenidji Ganiyou Yapo Kicho Denis Adjou Ané Bamba El Hadji Sawaliho Laboratoire de Constitution et de Réaction de la Matière UFR SSMT Université Félix Houphou&#235 t-Boigny Abidjan C&#244 te d’Ivoire

Catechin and epicatechin are two isomeric flavonoids. Despite the vital properties highlighted by numerous scientific studies, very little data is available on the intrinsic reactivity of these compounds. To provide more details on the stability and reactivity of catechin and epicatechin, this study is performed by means of theoretical calculation methods. For this purpose, geometry optimizations and frequency calculations at the B3LYP/6-31 + G (d, p) level of theory has been carried out and Natural Bond Orbital (NBO) analysis and VEDA (Vibrational Energy Distribution Analysis). The geometric and energy parameters and NBO analysis show that catechin appears more stable than epicatechin. The hydroxyl group position on the ring C of the catechol structure represents a factor that influences this relative stability. The global and local reactivity parameters reveal that epicatechin becomes more reactive than catechin. They indicate that their hydroxyl groups correspond to their most receptive sites. Fukui indices, VEDA and acidity study establish that O28–H29 remains the most reactive.

关键词： Catechin Epicatechin NBO Acidity DFT normal modes

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Quasi-Steady Vibratory Motion Within an Inductively Heated Cylindrically-Shaped Liquid Volume

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Journal of Iron and Steel Research(International) 2012年第S2期19卷 739-742页

作者： SHI Yinghui PETRYKOWSKI John C. Mechanical and Aerospace Engineering Department University of Dayton

The motion of an inductively heated fluid volume of cylindrical shape is assessed based on time dependent oscillatory components of the Lorentz *** applications considered include vibratory motion in a channel induction furnace and vibratory motion in an electromagnetically excited direct chill *** governing equations for the resulting magnetoacoustic problem are presented with the acoustic field solutions expressed in terms of normal modes. Closed form expressions are developed for the velocity,pressure and phase relationships between the excitation and the *** are prescribed for the pressure in both the channel furnace and the direct chill casting,with the calculational results from the casting application suggesting that,roughly,a two-fold increase in the effective peak acoustic pressure can be achieved by superimposing on the AC electromagnetic field a DC magnetic field of strength sufficient to match the peak alternating magnetic field.A procedure is also outlined for developing field descriptions of the velocity and pressure which can be effected in a MATLAB environ.

关键词： induction systems low-frequency electromagnetic vibrating casting(LFEVC) normal modes

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The focal mechanism solution of the Ms6.5 Wuding earthquake in Yunnan Province of October 24,1995

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Acta Seismologica Sinica(English Edition) 1997年第3期10卷 20-25页

作者：马淑田赵薇

The focal mechanism of Wuding earthquake with magnitude M =6.5 on October 24, 1995 is estimated by the method of inversion of seismic tensor in this paper. The two principal axes are nearly horizontal, the principal compressive axis is about N30°E, the nodal plane which strikes about N105°E (N75°W) is probably consistent with the actual rupture plane.

关键词： normal modes Green′s functions Wuding earthquake mantle waves focal mechanism

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Parametric Modeling of Electromagnetically Induced Vibration Processes Occurring Within Induction Systems

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Journal of Iron and Steel Research(International) 2012年第S2期19卷 709-712页

作者： PETRYKOWSKI John C. SHI Yinghui Mechanical and Aerospace Engineering Department University of Dayton

A continuum based model is presented which identifies a favorable set of operational conditions whereby an effective and efficient electromagnetically induced vibratory motion can proceed within an induction ***, an analytical assessment is presented for the electromagnetic field and the electromagnetically induced acoustic field, with parametric factors incorporated into the model to permit a normal modes solution for the acoustic field which here is sensitive to the compliance of both the molten metal and the wall,as well as electromagnetic properties of the metal.A parametric analysis is presented which identifies the importance of matching the mechanical impedances of the melt-wall configuration so that the generation of acoustic energy within the melt system can be more effectively *** straight-forward calculations,presented for the acoustic field,may provide a more computationally efficient means for implementing process simulation studies for these systems.

关键词： induction systems low-frequency electromagnetic vibrating casting(LFEVC) normal modes

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Statistical geoacoustic inversion from vertical correlation of shallow water reverberation

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Chinese Journal of Acoustics 2008年第4期27卷 368-377页

作者： GAO Wei WANG Ning WANG Haozhong Department of Physics Ocean University of China Qingdao 266100

Statistical geoacoustic inversion results based on reverberation vertical correlation （RVC） data from 300 Hz to 800 Hz are presented. The data were obtained during Yellow Sea Experiment-2005 （YSE-05）. An uncertainty analysis is carried out. It is found that the inversion sea bottom sound velocities decrease when the frequency increases. So it is difficult to determine the sea bottom sound velocity. In order to solve this problem, a two-layer bottom model is assumed, and a multi-frequency inversion approach based on Genetic Algorithm is proposed. The approach is demonstrated using YSE-05 experiment data. Both RVC and normal modes depth functions （NMDFs） calculated using the inverted geoacoustic parameters are in good agreement with the experimental measurements.

关键词： uncertainty analysis Genetic Algorithm experiment data sound velocity normal modes Yellow Sea

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