Generation and Analysis of Random Waves
DEFF Research Database (Denmark)
Liu, Zhou; Frigaard, Peter
applied to hydrology, wind mechanics, ice mechanics, etc., not to mention the fact that spectral analysis comes originally from optics and electronics. The book intents to be a textbook for senior and graduate students who have interest in coastal and offshore structures. The only pre......Sea waves are the most important phenomenon to be considered in the design of coastal and offshore structures. It should be stressed that, even though all contents in the book are related to sea waves, they have a broader application in practice. For example, the extreme theory has also been......-requirement for the book is the knowledge of linear wave theory....
Directory of Open Access Journals (Sweden)
Keqin Yan
2017-01-01
Full Text Available This chapter presents a reliability study for an offshore jacket structure with emphasis on the features of nonconventional modeling. Firstly, a random set model is formulated for modeling the random waves in an ocean site. Then, a jacket structure is investigated in a pushover analysis to identify the critical wave direction and key structural elements. This is based on the ultimate base shear strength. The selected probabilistic models are adopted for the important structural members and the wave direction is specified in the weakest direction of the structure for a conservative safety analysis. The wave height model is processed in a P-box format when it is used in the numerical analysis. The models are applied to find the bounds of the failure probabilities for the jacket structure. The propagation of this wave model to the uncertainty in results is investigated in both an interval analysis and Monte Carlo simulation. The results are compared in context of information content and numerical accuracy. Further, the failure probability bounds are compared with the conventional probabilistic approach.
Analysis and Computation of Acoustic and Elastic Wave Equations in Random Media
Motamed, Mohammad
2014-01-06
We propose stochastic collocation methods for solving the second order acoustic and elastic wave equations in heterogeneous random media and subject to deterministic boundary and initial conditions [1, 4]. We assume that the medium consists of non-overlapping sub-domains with smooth interfaces. In each sub-domain, the materials coefficients are smooth and given or approximated by a finite number of random variable. One important example is wave propagation in multi-layered media with smooth interfaces. The numerical scheme consists of a finite difference or finite element method in the physical space and a collocation in the zeros of suitable tensor product orthogonal polynomials (Gauss points) in the probability space. We provide a rigorous convergence analysis and demonstrate different types of convergence of the probability error with respect to the number of collocation points under some regularity assumptions on the data. In particular, we show that, unlike in elliptic and parabolic problems [2, 3], the solution to hyperbolic problems is not in general analytic with respect to the random variables. Therefore, the rate of convergence is only algebraic. A fast spectral rate of convergence is still possible for some quantities of interest and for the wave solutions with particular types of data. We also show that the semi-discrete solution is analytic with respect to the random variables with the radius of analyticity proportional to the grid/mesh size h. We therefore obtain an exponential rate of convergence which deteriorates as the quantity h p gets smaller, with p representing the polynomial degree in the stochastic space. We have shown that analytical results and numerical examples are consistent and that the stochastic collocation method may be a valid alternative to the more traditional Monte Carlo method. Here we focus on the stochastic acoustic wave equation. Similar results are obtained for stochastic elastic equations.
Analysis and computation of the elastic wave equation with random coefficients
Motamed, Mohammad; Nobile, Fabio; Tempone, Raul
2015-01-01
We consider the stochastic initial-boundary value problem for the elastic wave equation with random coefficients and deterministic data. We propose a stochastic collocation method for computing statistical moments of the solution or statistics
Analysis and computation of the elastic wave equation with random coefficients
Motamed, Mohammad
2015-10-21
We consider the stochastic initial-boundary value problem for the elastic wave equation with random coefficients and deterministic data. We propose a stochastic collocation method for computing statistical moments of the solution or statistics of some given quantities of interest. We study the convergence rate of the error in the stochastic collocation method. In particular, we show that, the rate of convergence depends on the regularity of the solution or the quantity of interest in the stochastic space, which is in turn related to the regularity of the deterministic data in the physical space and the type of the quantity of interest. We demonstrate that a fast rate of convergence is possible in two cases: for the elastic wave solutions with high regular data; and for some high regular quantities of interest even in the presence of low regular data. We perform numerical examples, including a simplified earthquake, which confirm the analysis and show that the collocation method is a valid alternative to the more traditional Monte Carlo sampling method for approximating quantities with high stochastic regularity.
Analysis and Computation of Acoustic and Elastic Wave Equations in Random Media
Motamed, Mohammad; Nobile, Fabio; Tempone, Raul
2014-01-01
], the solution to hyperbolic problems is not in general analytic with respect to the random variables. Therefore, the rate of convergence is only algebraic. A fast spectral rate of convergence is still possible for some quantities of interest and for the wave
Metallurgical flow recognition by random signal analysis of stress wave emissions
International Nuclear Information System (INIS)
Woodward, B.
1973-01-01
The present study involves detailed random signal analysis of individual 'bursts' of emission with objective of 'reading' their frequency spectra to identify specific metallurgical mechanisms. Mild steel unnotched testpieces were used in the early stages of development of this research. From a fracture mechanics point of view this research could lead to a powerful nondestructive testing device allowing identification of interior, instead of only surface, deformation mechanisms. (author)
Wave propagation and scattering in random media
Ishimaru, Akira
1978-01-01
Wave Propagation and Scattering in Random Media, Volume 2, presents the fundamental formulations of wave propagation and scattering in random media in a unified and systematic manner. The topics covered in this book may be grouped into three categories: waves in random scatterers, waves in random continua, and rough surface scattering. Random scatterers are random distributions of many particles. Examples are rain, fog, smog, hail, ocean particles, red blood cells, polymers, and other particles in a state of Brownian motion. Random continua are the media whose characteristics vary randomly an
International Nuclear Information System (INIS)
Iooss, B.
2009-01-01
The present document constitutes my Habilitation thesis report. It recalls my scientific activity of the twelve last years, since my PhD thesis until the works completed as a research engineer at CEA Cadarache. The two main chapters of this document correspond to two different research fields both referring to the uncertainty treatment in engineering problems. The first chapter establishes a synthesis of my work on high frequency wave propagation in random medium. It more specifically relates to the study of the statistical fluctuations of acoustic wave travel-times in random and/or turbulent media. The new results mainly concern the introduction of the velocity field statistical anisotropy in the analytical expressions of the travel-time statistical moments according to those of the velocity field. This work was primarily carried by requirements in geophysics (oil exploration and seismology). The second chapter is concerned by the probabilistic techniques to study the effect of input variables uncertainties in numerical models. My main applications in this chapter relate to the nuclear engineering domain which offers a large variety of uncertainty problems to be treated. First of all, a complete synthesis is carried out on the statistical methods of sensitivity analysis and global exploration of numerical models. The construction and the use of a meta-model (inexpensive mathematical function replacing an expensive computer code) are then illustrated by my work on the Gaussian process model (kriging). Two additional topics are finally approached: the high quantile estimation of a computer code output and the analysis of stochastic computer codes. We conclude this memory with some perspectives about the numerical simulation and the use of predictive models in industry. This context is extremely positive for future researches and application developments. (author)
DEFF Research Database (Denmark)
Frigaard, Peter; Andersen, Thomas Lykke
The present book describes the most important aspects of wave analysis techniques applied to physical model tests. Moreover, the book serves as technical documentation for the wave analysis software WaveLab 3, cf. Aalborg University (2012). In that respect it should be mentioned that supplementary...... to the present technical documentation exists also the online help document describing the WaveLab software in detail including all the inputs and output fields. In addition to the two main authors also Tue Hald, Jacob Helm-Petersen and Morten Møller Jakobsen have contributed to the note. Their input is highly...... acknowledged. The outline of the book is as follows: • Chapter 2 and 3 describes analysis of waves in time and frequency domain. • Chapter 4 and 5 describes the separation of incident and reflected waves for the two-dimensional case. • Chapter 6 describes the estimation of the directional spectra which also...
Breather Rogue Waves in Random Seas
Wang, J.; Ma, Q. W.; Yan, S.; Chabchoub, A.
2018-01-01
Rogue or freak waves are extreme wave events that have heights exceeding 8 times the standard deviation of surrounding waves and emerge, for instance, in the ocean as well as in other physical dispersive wave guides, such as in optical fibers. One effective and convenient way to model such an extreme dynamics in laboratory environments within a controlled framework as well as for short process time and length scales is provided through the breather formalism. Breathers are pulsating localized structures known to model extreme waves in several nonlinear dispersive media in which the initial underlying process is assumed to be narrow banded. On the other hand, several recent studies suggest that breathers can also persist in more complex environments, such as in random seas, beyond the attributed physical limitations. In this work, we study the robustness of the Peregrine breather (PB) embedded in Joint North Sea Wave Project (JONSWAP) configurations using fully nonlinear hydrodynamic numerical simulations in order to validate its practicalness for ocean engineering applications. We provide a specific range for both the spectral bandwidth of the dynamical process as well as the background wave steepness and, thus, quantify the applicability of the PB in modeling rogue waves in realistic oceanic conditions. Our results may motivate analogous studies in fields of physics such as optics and plasma to quantify the limitations of exact weakly nonlinear models, such as solitons and breathers, within the framework of the fully nonlinear governing equations of the corresponding medium.
Electromagnetic Wave Propagation in Random Media
DEFF Research Database (Denmark)
Pécseli, Hans
1984-01-01
The propagation of a narrow frequency band beam of electromagnetic waves in a medium with randomly varying index of refraction is considered. A novel formulation of the governing equation is proposed. An equation for the average Green function (or transition probability) can then be derived...
Tapia-Herrera, R.; Huerta-Lopez, C. I.; Martinez-Cruzado, J. A.
2009-05-01
Results of site characterization for an experimental site in the metropolitan area of Tijuana, B. C., Mexico are presented as part of the on-going research in which time series of earthquakes, ambient noise, and induced vibrations were processed with three different methods: H/V spectral ratios, Spectral Analysis of Surface Waves (SASW), and the Random Decrement Method, (RDM). Forward modeling using the wave propagation stiffness matrix method (Roësset and Kausel, 1981) was used to compute the theoretical SH/P, SV/P spectral ratios, and the experimental H/V spectral ratios were computed following the conventional concepts of Fourier analysis. The modeling/comparison between the theoretical and experimental H/V spectral ratios was carried out. For the SASW method the theoretical dispersion curves were also computed and compared with the experimental one, and finally the theoretical free vibration decay curve was compared with the experimental one obtained with the RDM. All three methods were tested with ambient noise, induced vibrations, and earthquake signals. Both experimental spectral ratios obtained with ambient noise as well as earthquake signals agree quite well with the theoretical spectral ratios, particularly at the fundamental vibration frequency of the recording site. Differences between the fundamental vibration frequencies are evident for sites located at alluvial fill (~0.6 Hz) and at sites located at conglomerate/sandstones fill (0.75 Hz). Shear wave velocities for the soft soil layers of the 4-layer discrete soil model ranges as low as 100 m/s and up to 280 m/s. The results with the SASW provided information that allows to identify low velocity layers, not seen before with the traditional seismic methods. The damping estimations obtained with the RDM are within the expected values, and the dominant frequency of the system also obtained with the RDM correlates within the range of plus-minus 20 % with the one obtained by means of the H/V spectral
Low-wave-number statistics of randomly advected passive scalars
International Nuclear Information System (INIS)
Kerstein, A.R.; McMurtry, P.A.
1994-01-01
A heuristic analysis of the decay of a passive scalar field subject to statistically steady random advection, predicts two low-wave-number spectral scaling regimes analogous to the similarity states previously identified by Chasnov [Phys. Fluids 6, 1036 (1994)]. Consequences of their predicted coexistence in a single flow are examined. The analysis is limited to the idealized case of narrow band advection. To complement the analysis, and to extend the predictions to physically more realistic advection processes, advection diffusion is simulated using a one-dimensional stochastic model. An experimental test of the predictions is proposed
Nonlinear diffuse scattering of the random-phased wave
International Nuclear Information System (INIS)
Kato, Yoshiaki; Arinaga, Shinji; Mima, Kunioki.
1983-01-01
First experimental observation of the nonlinear diffuse scattering is reported. This new effect was observed in the propagation of the random-phased wave through a nonlinear dielectric medium. This effect is ascribed to the diffusion of the wavevector of the electro-magnetic wave to the lateral direction due to the randomly distributed nonlinear increase in the refractive index. (author)
Statistical analysis on extreme wave height
Digital Repository Service at National Institute of Oceanography (India)
Teena, N.V.; SanilKumar, V.; Sudheesh, K.; Sajeev, R.
-294. • WAFO (2000) – A MATLAB toolbox for analysis of random waves and loads, Lund University, Sweden, homepage http://www.maths.lth.se/matstat/wafo/,2000. 15 Table 1: Statistical results of data and fitted distribution for cumulative distribution...
Parametric analysis of change in wave number of surface waves
Directory of Open Access Journals (Sweden)
Tadić Ljiljana
2015-01-01
Full Text Available The paper analyzes the dependence of the change wave number of materials soil constants, ie the frequency of the waves. The starting point in this analysis cosists of wave equation and dynamic stiffness matrix of soil.
Nonlinear evolution equations for waves in random media
International Nuclear Information System (INIS)
Pelinovsky, E.; Talipova, T.
1994-01-01
The scope of this paper is to highlight the main ideas of asymptotical methods applying in modern approaches of description of nonlinear wave propagation in random media. We start with the discussion of the classical conception of ''mean field''. Then an exactly solvable model describing nonlinear wave propagation in the medium with fluctuating parameters is considered in order to demonstrate that the ''mean field'' method is not correct. We develop new asymptotic procedures of obtaining the nonlinear evolution equations for the wave fields in random media. (author). 16 refs
Random wave fields and scintillated beams
CSIR Research Space (South Africa)
Roux, FS
2009-01-01
Full Text Available F. Stef Roux CSIR National Laser Centre PO Box 395, Pretoria 0001, South Africa CSIR National Laser Centre – p.1/29 Contents . Scintillated beams and adaptive optics . Detecting a vortex — Shack-Hartmann . Remove optical vortices . Random vortex... beam. CSIR National Laser Centre – p.3/29 Weak scintillation If the scintillation is weak the resulting phase function of the optical beam is still continuous. Such a weakly scintillated beam can be corrected by an adaptive optical system. CSIR National...
Zhang, Yu; Li, Yan; Shao, Hao; Zhong, Yaozhao; Zhang, Sai; Zhao, Zongxi
2012-06-01
Band structure and wave localization are investigated for sea surface water waves over large-scale sand wave topography. Sand wave height, sand wave width, water depth, and water width between adjacent sand waves have significant impact on band gaps. Random fluctuations of sand wave height, sand wave width, and water depth induce water wave localization. However, random water width produces a perfect transmission tunnel of water waves at a certain frequency so that localization does not occur no matter how large a disorder level is applied. Together with theoretical results, the field experimental observations in the Taiwan Bank suggest band gap and wave localization as the physical mechanism of sea surface water wave propagating over natural large-scale sand waves.
Directory of Open Access Journals (Sweden)
M. Ettefagh
2018-03-01
Full Text Available One of the new methods for powering low-power electronic devices employed in the sea, is using of mechanical energies of sea waves. In this method, piezoelectric material is employed to convert the mechanical energy of sea waves into electrical energy. The advantage of this method is based on not implementing the battery charging system. Although, many studies have been done about energy harvesting from sea waves, energy harvesting with considering random JONWSAP wave theory is not fully studied up to now. The random JONSWAP wave model is a more realistic approximation of sea waves in comparison of Airy wave model. Therefore, in this paper a vertical beam with the piezoelectric patches, which is fixed to the seabed, is considered as energy harvester system. The energy harvesting system is simulated by MATLAB software, and then the vibration response of the beam and consequently the generated power is obtained considering the JONWSAP wave theory. In addition, the reliability of the system and the effect of piezoelectric patches uncertainties on the generated power are studied by statistical method. Furthermore, the failure possibility of harvester based on violation criteria is investigated.
On the Extreme Wave Height Analysis
DEFF Research Database (Denmark)
Burcharth, H. F.; Liu, Zhou
1994-01-01
The determination of the design wave height is usually based on the statistical analysis of long-term extreme wave height measurements. After an introduction to the procedure of the extreme wave height analysis, the paper presents new development concerning various aspects of the extreme wave...... height analysis. Finally, the paper gives a practical example based on a data set of the hindcasted wave heights for a deep water location in the Mediterranean Sea....
Analysis of flexural wave cloaks
Directory of Open Access Journals (Sweden)
Alfonso Climente
2016-12-01
Full Text Available This work presents a comprehensive study of the cloak for bending waves theoretically proposed by Farhat et al. [see Phys. Rev. Lett. 103, 024301 (2009] and later on experimentally realized by Stenger et al. [see Phys. Rev. Lett. 108, 014301 (2012]. This study uses a semi-analytical approach, the multilayer scattering method, which is based in the Kirchoff-Love wave equation for flexural waves in thin plates. Our approach was unable to reproduce the predicted behavior of the theoretically proposed cloak. This disagreement is here explained in terms of the simplified wave equation employed in the cloak design, which employed unusual boundary conditions for the cloaking shell. However, our approach reproduces fairly well the measured displacement maps for the fabricated cloak, indicating the validity of our approach. Also, the cloak quality has been here analyzed using the so called averaged visibility and the scattering cross section. The results obtained from both analysis let us to conclude that there is room for further improvements of this type of flexural wave cloak by using better design procedures.
Computation of High-Frequency Waves with Random Uncertainty
Malenova, Gabriela
2016-01-06
We consider the forward propagation of uncertainty in high-frequency waves, described by the second order wave equation with highly oscillatory initial data. The main sources of uncertainty are the wave speed and/or the initial phase and amplitude, described by a finite number of random variables with known joint probability distribution. We propose a stochastic spectral asymptotic method [1] for computing the statistics of uncertain output quantities of interest (QoIs), which are often linear or nonlinear functionals of the wave solution and its spatial/temporal derivatives. The numerical scheme combines two techniques: a high-frequency method based on Gaussian beams [2, 3], a sparse stochastic collocation method [4]. The fast spectral convergence of the proposed method depends crucially on the presence of high stochastic regularity of the QoI independent of the wave frequency. In general, the high-frequency wave solutions to parametric hyperbolic equations are highly oscillatory and non-smooth in both physical and stochastic spaces. Consequently, the stochastic regularity of the QoI, which is a functional of the wave solution, may in principle below and depend on frequency. In the present work, we provide theoretical arguments and numerical evidence that physically motivated QoIs based on local averages of |uE|2 are smooth, with derivatives in the stochastic space uniformly bounded in E, where uE and E denote the highly oscillatory wave solution and the short wavelength, respectively. This observable related regularity makes the proposed approach more efficient than current asymptotic approaches based on Monte Carlo sampling techniques.
Wave speed in excitable random networks with spatially constrained connections.
Directory of Open Access Journals (Sweden)
Nikita Vladimirov
Full Text Available Very fast oscillations (VFO in neocortex are widely observed before epileptic seizures, and there is growing evidence that they are caused by networks of pyramidal neurons connected by gap junctions between their axons. We are motivated by the spatio-temporal waves of activity recorded using electrocorticography (ECoG, and study the speed of activity propagation through a network of neurons axonally coupled by gap junctions. We simulate wave propagation by excitable cellular automata (CA on random (Erdös-Rényi networks of special type, with spatially constrained connections. From the cellular automaton model, we derive a mean field theory to predict wave propagation. The governing equation resolved by the Fisher-Kolmogorov PDE fails to describe wave speed. A new (hyperbolic PDE is suggested, which provides adequate wave speed v( that saturates with network degree , in agreement with intuitive expectations and CA simulations. We further show that the maximum length of connection is a much better predictor of the wave speed than the mean length. When tested in networks with various degree distributions, wave speeds are found to strongly depend on the ratio of network moments / rather than on mean degree , which is explained by general network theory. The wave speeds are strikingly similar in a diverse set of networks, including regular, Poisson, exponential and power law distributions, supporting our theory for various network topologies. Our results suggest practical predictions for networks of electrically coupled neurons, and our mean field method can be readily applied for a wide class of similar problems, such as spread of epidemics through spatial networks.
International Nuclear Information System (INIS)
Braginsky, V.B.; Kardashev, N.S.; Polnarev, A.G.; Novikov, I.D.
1989-12-01
Propagation of an electromagnetic wave in the field of gravitational waves is considered. Attention is given to the principal difference between the electromagnetic wave propagation in the field of random gravitational waves and the electromagnetic wave propagation in a medium with a randomly-inhomogeneous refraction index. It is shown that in the case of the gravitation wave field the phase shift of an electromagnetic wave does not increase with distance. The capability of space radio interferometry to detect relic gravitational waves as well as gravitational wave bursts of non cosmological origin are analyzed. (author). 64 refs, 2 figs
Chuang, Wei-Liang; Chang, Kuang-An; Mercier, Richard
2018-06-01
Green water kinematics and dynamics due to wave impingements on a simplified geometry, fixed platform were experimentally investigated in a large, deep-water wave basin. Both plane focusing waves and random waves were employed in the generation of green water. The focusing wave condition was designed to create two consecutive plunging breaking waves with one impinging on the frontal vertical wall of the fixed platform, referred as wall impingement, and the other directly impinging on the deck surface, referred as deck impingement. The random wave condition was generated using the JONSWAP spectrum with a significant wave height approximately equal to the freeboard. A total of 179 green water events were collected in the random wave condition. By examining the green water events in random waves, three different flow types are categorized: collapse of overtopping wave, fall of bulk water, and breaking wave crest. The aerated flow velocity was measured using bubble image velocimetry, while the void fraction was measured using fiber optic reflectometry. For the plane focusing wave condition, measurements of impact pressure were synchronized with the flow velocity and void fraction measurements. The relationship between the peak pressures and the pressure rise times is examined. For the high-intensity impact in the deck impingement events, the peak pressures are observed to be proportional to the aeration levels. The maximum horizontal velocities in the green water events in random waves are well represented by the lognormal distribution. Ritter's solution is shown to quantitatively describe the green water velocity distributions under both the focusing wave condition and the random wave condition. A prediction equation for green water velocity distribution under random waves is proposed.
Interaction of random wave-current over uneven and porous bottoms
International Nuclear Information System (INIS)
Suo Yaohong; Zhang Zhonghua; Zhang Jiafan; Suo Xiaohong
2009-01-01
Starting from linear wave theory and applying Green's second identity and considering wave-current interaction for porous bottoms and variable water depth, the comprehensive mild-slope equation model theory of wave-current interaction is developed, then paying attention to the effect of random waves, by use of Kubo et al.'s method, a model theory of the interaction between random waves and current over uneven and porous bottoms is established. Finally the characteristics of the random waves are discussed numerically from both the geometric-optics approximation and the target spectrum.
A stochastic collocation method for the second order wave equation with a discontinuous random speed
Motamed, Mohammad; Nobile, Fabio; Tempone, Raul
2012-01-01
In this paper we propose and analyze a stochastic collocation method for solving the second order wave equation with a random wave speed and subjected to deterministic boundary and initial conditions. The speed is piecewise smooth in the physical
Trend analysis of the wave storminess: the wave direction
Casas Prat, M.; Sierra, J. P.; Mösso, C.; Sánchez-Arcilla, A.
2009-09-01
directionality. It is based on 44 year hindcast model data (1958-2001) of the HIPOCAS project, enabling to work with a longer time series compared to the existing measured ones. 41 nodes of this database are used, containing 3 hourly simulated data of significant wave height and wave direction, among other parameters. For storm definition, the Peak Over Threshold (POT) method is used with some additional duration requirements in order to analyse statistically independent events (Mendoza & Jiménez, 2006). Including both wave height and storm duration, the wave storminess is characterised by the energy content (Mendoza & Jiménez, 2004), being in turn log-transformed because of its positive scale. Separately, the wave directionality itself is analysed in terms of different sectors and approaching their probability of occurrence by counting events and using Bayesian inference (Agresti, 2002). Therefore, the original data is transformed into compositional data and, before performing the trend analysis, the isometric logratio (ilr) transformation (Egozcue et al., 2003) is done. In general, the trend analysis methodology consists in two steps: 1) trend detection and 2) trend quantification. For 1) the Mann Kendall test is used in order to identify the nodes with significant trend. For these selected nodes, the trend quantification is done, comparing two methods: 1) a simple linear regression analysis complemented with the bootstrap technique and 2) a Bayesian analysis, assuming normally distributed data with linearly increasing mean. Preliminary results show no significant trend for both annual mean and maximum energy content except for some nodes located to the Northern Catalan coast. Regarding the wave direction (but not only considering stormy conditions) there is a tendency of North direction to decrease whereas South and Southeast direction seems to increase.
Data analysis techniques for gravitational wave observations
Indian Academy of Sciences (India)
Astrophysical sources of gravitational waves fall broadly into three categories: (i) transient and bursts, (ii) periodic or continuous wave and (iii) stochastic. Each type of source requires a different type of data analysis strategy. In this talk various data analysis strategies will be reviewed. Optimal filtering is used for extracting ...
Risk analysis of breakwater caisson under wave attack using load surface approximation
Kim, Dong Hyawn
2014-12-01
A new load surface based approach to the reliability analysis of caisson-type breakwater is proposed. Uncertainties of the horizontal and vertical wave loads acting on breakwater are considered by using the so-called load surfaces, which can be estimated as functions of wave height, water level, and so on. Then, the first-order reliability method (FORM) can be applied to determine the probability of failure under the wave action. In this way, the reliability analysis of breakwaters with uncertainties both in wave height and in water level is possible. Moreover, the uncertainty in wave breaking can be taken into account by considering a random variable for wave height ratio which relates the significant wave height to the maximum wave height. The proposed approach is applied numerically to the reliability analysis of caisson breakwater under wave attack that may undergo partial or full wave breaking.
Man, Wanrong; Hu, Jianqiang; Zhao, Zhijing; Zhang, Mingming; Wang, Tingting; Lin, Jie; Duan, Yu; Wang, Ling; Wang, Haichang; Sun, Dongdong; Li, Yan
2016-09-01
The instantaneous wave-free ratio (iFR) is a new vasodilator-free index of coronary stenosis severity. The aim of this meta-analysis is to assess the diagnostic performance of iFR for the evaluation of coronary stenosis severity with fractional flow reserve as standard reference. We searched PubMed, EMBASE, CENTRAL, ProQuest, Web of Science, and International Clinical Trials Registry Platform (ICTRP) for publications concerning the diagnostic value of iFR. We used a random-effects covariate to synthesize the available data of sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR-), and diagnostic odds ratio (DOR). Overall test performance was summarized by the summary receiver operating characteristic curve (sROC) and the area under the curve (AUC). Eight studies with 1611 subjects were included in the meta-analysis. The pooled sensitivity, specificity, LR+, LR-, and DOR for iFR were respectively 73.3% (70.1-76.2%), 86.4% (84.3-88.3%), 5.71 (4.43-7.37), 0.29 (0.22-0.38), and 20.54 (16.11-26.20). The area under the summary receiver operating characteristic curves for iFR was 0.8786. No publication bias was identified. The available evidence suggests that iFR may be a new, simple, and promising technology for coronary stenosis physiological assessment.
A stochastic collocation method for the second order wave equation with a discontinuous random speed
Motamed, Mohammad
2012-08-31
In this paper we propose and analyze a stochastic collocation method for solving the second order wave equation with a random wave speed and subjected to deterministic boundary and initial conditions. The speed is piecewise smooth in the physical space and depends on a finite number of random variables. The numerical scheme consists of a finite difference or finite element method in the physical space and a collocation in the zeros of suitable tensor product orthogonal polynomials (Gauss points) in the probability space. This approach leads to the solution of uncoupled deterministic problems as in the Monte Carlo method. We consider both full and sparse tensor product spaces of orthogonal polynomials. We provide a rigorous convergence analysis and demonstrate different types of convergence of the probability error with respect to the number of collocation points for full and sparse tensor product spaces and under some regularity assumptions on the data. In particular, we show that, unlike in elliptic and parabolic problems, the solution to hyperbolic problems is not in general analytic with respect to the random variables. Therefore, the rate of convergence may only be algebraic. An exponential/fast rate of convergence is still possible for some quantities of interest and for the wave solution with particular types of data. We present numerical examples, which confirm the analysis and show that the collocation method is a valid alternative to the more traditional Monte Carlo method for this class of problems. © 2012 Springer-Verlag.
Extreme Wave Analysis by Integrating Model and Wave Buoy Data
Directory of Open Access Journals (Sweden)
Fabio Dentale
2018-03-01
Full Text Available Estimating the extreme values of significant wave height (HS, generally described by the HS return period TR function HS(TR and by its confidence intervals, is a necessity in many branches of coastal science and engineering. The availability of indirect wave data generated by global and regional wind and wave model chains have brought radical changes to the estimation procedures of such probability distribution—weather and wave modeling systems are routinely run all over the world, and HS time series for each grid point are produced and published after assimilation (analysis of the ground truth. However, while the sources of such indirect data are numerous, and generally of good quality, many aspects of their procedures are hidden to the users, who cannot evaluate the reliability and the limits of the HS(TR deriving from such data. In order to provide a simple engineering tool to evaluate the probability of extreme sea-states as well as the quality of such estimates, we propose here a procedure based on integrating HS time series generated by model chains with those recorded by wave buoys in the same area.
DEFF Research Database (Denmark)
Bigoni, Daniele; Engsig-Karup, Allan Peter; Eskilsson, Claes
2016-01-01
A major challenge in next-generation industrial applications is to improve numerical analysis by quantifying uncertainties in predictions. In this work we present a formulation of a fully nonlinear and dispersive potential flow water wave model with random inputs for the probabilistic description...... at different points in the parameter space, allowing for the reuse of existing simulation software. The choice of the applied methods is driven by the number of uncertain input parameters and by the fact that finding the solution of the considered model is computationally intensive. We revisit experimental...... benchmarks often used for validation of deterministic water wave models. Based on numerical experiments and assumed uncertainties in boundary data, our analysis reveals that some of the known discrepancies from deterministic simulation in comparison with experimental measurements could be partially explained...
Scattering of electromagnetic wave by the layer with one-dimensional random inhomogeneities
Kogan, Lev; Zaboronkova, Tatiana; Grigoriev, Gennadii., IV.
A great deal of attention has been paid to the study of probability characteristics of electro-magnetic waves scattered by one-dimensional fluctuations of medium dielectric permittivity. However, the problem of a determination of a density of a probability and average intensity of the field inside the stochastically inhomogeneous medium with arbitrary extension of fluc-tuations has not been considered yet. It is the purpose of the present report to find and to analyze the indicated functions for the plane electromagnetic wave scattered by the layer with one-dimensional fluctuations of permittivity. We assumed that the length and the amplitude of individual fluctuations as well the interval between them are random quantities. All of indi-cated fluctuation parameters are supposed as independent random values possessing Gaussian distribution. We considered the stationary time cases both small-scale and large-scale rarefied inhomogeneities. Mathematically such problem can be reduced to the solution of integral Fred-holm equation of second kind for Hertz potential (U). Using the decomposition of the field into the series of multiply scattered waves we obtained the expression for a probability density of the field of the plane wave and determined the moments of the scattered field. We have shown that all odd moments of the centered field (U-¡U¿) are equal to zero and the even moments depend on the intensity. It was obtained that the probability density of the field possesses the Gaussian distribution. The average field is small compared with the standard fluctuation of scattered field for all considered cases of inhomogeneities. The value of average intensity of the field is an order of a standard of fluctuations of field intensity and drops with increases the inhomogeneities length in the case of small-scale inhomogeneities. The behavior of average intensity is more complicated in the case of large-scale medium inhomogeneities. The value of average intensity is the
Crack Detection with Lamb Wave Wavenumber Analysis
Tian, Zhenhua; Leckey, Cara; Rogge, Matt; Yu, Lingyu
2013-01-01
In this work, we present our study of Lamb wave crack detection using wavenumber analysis. The aim is to demonstrate the application of wavenumber analysis to 3D Lamb wave data to enable damage detection. The 3D wavefields (including vx, vy and vz components) in time-space domain contain a wealth of information regarding the propagating waves in a damaged plate. For crack detection, three wavenumber analysis techniques are used: (i) two dimensional Fourier transform (2D-FT) which can transform the time-space wavefield into frequency-wavenumber representation while losing the spatial information; (ii) short space 2D-FT which can obtain the frequency-wavenumber spectra at various spatial locations, resulting in a space-frequency-wavenumber representation; (iii) local wavenumber analysis which can provide the distribution of the effective wavenumbers at different locations. All of these concepts are demonstrated through a numerical simulation example of an aluminum plate with a crack. The 3D elastodynamic finite integration technique (EFIT) was used to obtain the 3D wavefields, of which the vz (out-of-plane) wave component is compared with the experimental measurement obtained from a scanning laser Doppler vibrometer (SLDV) for verification purposes. The experimental and simulated results are found to be in close agreement. The application of wavenumber analysis on 3D EFIT simulation data shows the effectiveness of the analysis for crack detection. Keywords: : Lamb wave, crack detection, wavenumber analysis, EFIT modeling
International Nuclear Information System (INIS)
Conte, Elio; Khrennikov, Andrei; Federici, Antonio; Zbilut, Joseph P.
2009-01-01
We develop a new method for analysis of fundamental brain waves as recorded by the EEG. To this purpose we introduce a Fractal Variance Function that is based on the calculation of the variogram. The method is completed by using Random Matrix Theory. Some examples are given. We also discuss the link of such formulation with H. Weiss and V. Weiss golden ratio found in the brain, and with El Naschie fractal Cantorian space-time theory.
Shahat, Ahmed; Elderwy, Ahmad; Safwat, Ahmed S; Abdelkawi, Islam F; Reda, Ahmed; Abdelsalam, Yasser; Sayed, Mohamed; Hammouda, Hisham
2016-04-01
We assessed the effect of tamsulosin as an adjunctive therapy after shock wave lithotripsy for pediatric single renal pelvic stones. A total of 120 children with a unilateral single renal pelvic stone were included in a prospective randomized, controlled study. All children were randomized to 2 equal groups. Group 1 received tamsulosin (0.01 mg/kg once daily) as adjunctive therapy after shock wave lithotripsy in addition to paracetamol while group 2 received paracetamol only. Stone clearance was defined as no renal stone fragments or fragments less than 3 mm and no pelvicalyceal system dilatation. Our study included 69 boys and 51 girls with a median age of 3.5 years and a median stone size of 1.2 cm. There was no statistically significant difference between groups 1 and 2 in stone or patient criteria. Of the children 99 (82.5%) achieved stone clearance after the first session, including 50 in group 1 and 49 in group 2. All children in each group were cleared of stones after the second session. The overall complication rate was 14.2%. There was no statistically significant difference between single session stone clearance rates (p = 0.81) and complications rates (p = 0.432) in either group. On multivariate analysis using logistic regression smaller stone size (p = 0.016) and radiopaque stones (p = 0.019) were the only predictors of stone clearance at a single shock wave lithotripsy session. Tamsulosin therapy did not affect stone clearance (p = 0.649). Tamsulosin does not seem to improve renal stone clearance. Smaller and radiopaque renal stones have more chance of clearance after shock wave lithotripsy for pediatric single renal pelvic stones. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.
Analysis of Bending Waves in Phononic Crystal Beams with Defects
Directory of Open Access Journals (Sweden)
Yongqiang Guo
2018-01-01
Full Text Available Existing investigations on imperfect phononic crystal beams mainly concern periodic multi-span beams carrying either one or two channel waves with random or deterministic disorder in span-length. This paper studies the two channel bending waves in phononic crystal beams consisting of many phases of materials with defects introduced as one structural segment having different cross-sectional dimensions or material parameters. The method of reverberation-ray matrix (MRRM based on the Timoshenko beam theory, which can conduct high-frequency analysis, is extended for the theoretical analysis of dispersion and transmission of bending waves. The supercell technique and the Floquet–Bloch theorem are adopted for modeling the dispersion characteristics, and the whole finite structural model is used to calculate the transmission spectra. Experimental measurements and numerical calculations are provided to validate the displacement transmission obtained by the proposed MRRM, with the effect of damping on transmission spectra being concerned. The high-frequency calculation applicability of the proposed MRRM is also confirmed by comparing the present results with the corresponding ones either using the transfer matrix method (TMM or MRRM based on Euler—Bernoulli beam theory. The influences of defect size, defect form, and unit-cell number on the transmission spectra and the band structures are discussed. The drawn conclusions may be useful for designing or evaluating the defected phononic crystal beams in bending wave control. In addition, our conclusions are especially potential for identifying the defect location through bending wave signals.
On the fourth moment of Hecke Maass forms and the Random Wave Conjecture
Buttcane, Jack; Khan, Rizwanur
2016-01-01
Conditionally on the Generalized Lindel\\"of Hypothesis, we obtain an asymptotic for the fourth moment of Hecke Maass cusp forms of large Laplacian eigenvalue for the full modular group. This lends support to the Random Wave Conjecture.
Testing, Analysis and Control of Wave Dragon, Wave Energy Converter
DEFF Research Database (Denmark)
Tedd, James
of the incident waves upon a wave device allows the possibility of accurately tuning the power-take off mechanism (the hydro-turbines for the Wave Dragon) to capture more energy. A digital filter method for performing this prediction in real-time with minimal computational effort is presented. Construction...... of digital filters is well known within signal processing, but their use for this application in Wave Energy is new. The filter must be designed carefully as the frequency components of waves travel at different speeds. Research presented in this thesis has advanced the development of the Wave Dragon device...
Computation of High-Frequency Waves with Random Uncertainty
Malenova, Gabriela; Motamed, Mohammad; Runborg, Olof; Tempone, Raul
2016-01-01
or nonlinear functionals of the wave solution and its spatial/temporal derivatives. The numerical scheme combines two techniques: a high-frequency method based on Gaussian beams [2, 3], a sparse stochastic collocation method [4]. The fast spectral
Human action analysis with randomized trees
Yu, Gang; Liu, Zicheng
2014-01-01
This book will provide a comprehensive overview on human action analysis with randomized trees. It will cover both the supervised random trees and the unsupervised random trees. When there are sufficient amount of labeled data available, supervised random trees provides a fast method for space-time interest point matching. When labeled data is minimal as in the case of example-based action search, unsupervised random trees is used to leverage the unlabelled data. We describe how the randomized trees can be used for action classification, action detection, action search, and action prediction.
Manual for wave generation and analysis
DEFF Research Database (Denmark)
Jakobsen, Morten Møller
This Manual is for the included wave generation and analysis software and graphical user interface. The package is made for Matlab and is meant for educational purposes. The code is free to use under the GNU Public License (GPL). It is still in development and should be considered as such. If you...
Optimal Control of a Surge-Mode WEC in Random Waves
Energy Technology Data Exchange (ETDEWEB)
Chertok, Allan [Resolute Marine Energy, Inc., Boston, MA (United States); Ceberio, Olivier [Resolute Marine Energy, Inc., Boston, MA (United States); Staby, Bill [Resolute Marine Energy, Inc., Boston, MA (United States); Previsic, Mirko [Re Vision Consulting, Sacramento, CA (United States); Scruggs, Jeffrey [Univ. of Michigan, Ann Arbor, MI (United States); Van de Ven, James [Univ. of Minnesota, Minneapolis, MN (United States)
2016-08-30
The objective of this project was to develop one or more real-time feedback and feed-forward (MPC) control algorithms for an Oscillating Surge Wave Converter (OSWC) developed by RME called SurgeWEC™ that leverages recent innovations in wave energy converter (WEC) control theory to maximize power production in random wave environments. The control algorithms synthesized innovations in dynamic programming and nonlinear wave dynamics using anticipatory wave sensors and localized sensor measurements; e.g. position and velocity of the WEC Power Take Off (PTO), with predictive wave forecasting data. The result was an advanced control system that uses feedback or feed-forward data from an array of sensor channels comprised of both localized and deployed sensors fused into a single decision process that optimally compensates for uncertainties in the system dynamics, wave forecasts, and sensor measurement errors.
Directory of Open Access Journals (Sweden)
A. Arunjith
2013-06-01
Full Text Available The design of rubble mound structures like breakwaters and seawalls are influenced by the wave run-up and overtopping over them. The above phenomena largely depend on the type of the armour units as they directly interact with the incident waves. The hydrodynamic characteristics of various concrete armour units have been established by several researchers. A new armour block, ‘Kolos’, a modified version of Dolos, is considered in this study for a detailed investigation. An attempt is made to establish empirical relationships for the estimation of wave overtopping discharges over crown wall and run-up on Kolosarmoured slope exposed to random wave from the results of a comprehensive experimental program. Further, the results are compared with that of a tested section with natural rocks as armour layer and with that of other investigators.
Statistical Analysis of Wave Climate Data Using Mixed Distributions and Extreme Wave Prediction
Directory of Open Access Journals (Sweden)
Wei Li
2016-05-01
Full Text Available The investigation of various aspects of the wave climate at a wave energy test site is essential for the development of reliable and efficient wave energy conversion technology. This paper presents studies of the wave climate based on nine years of wave observations from the 2005–2013 period measured with a wave measurement buoy at the Lysekil wave energy test site located off the west coast of Sweden. A detailed analysis of the wave statistics is investigated to reveal the characteristics of the wave climate at this specific test site. The long-term extreme waves are estimated from applying the Peak over Threshold (POT method on the measured wave data. The significant wave height and the maximum wave height at the test site for different return periods are also compared. In this study, a new approach using a mixed-distribution model is proposed to describe the long-term behavior of the significant wave height and it shows an impressive goodness of fit to wave data from the test site. The mixed-distribution model is also applied to measured wave data from four other sites and it provides an illustration of the general applicability of the proposed model. The methodologies used in this paper can be applied to general wave climate analysis of wave energy test sites to estimate extreme waves for the survivability assessment of wave energy converters and characterize the long wave climate to forecast the wave energy resource of the test sites and the energy production of the wave energy converters.
Partial wave analysis using graphics processing units
Energy Technology Data Exchange (ETDEWEB)
Berger, Niklaus; Liu Beijiang; Wang Jike, E-mail: nberger@ihep.ac.c [Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Lu, Shijingshan, 100049 Beijing (China)
2010-04-01
Partial wave analysis is an important tool for determining resonance properties in hadron spectroscopy. For large data samples however, the un-binned likelihood fits employed are computationally very expensive. At the Beijing Spectrometer (BES) III experiment, an increase in statistics compared to earlier experiments of up to two orders of magnitude is expected. In order to allow for a timely analysis of these datasets, additional computing power with short turnover times has to be made available. It turns out that graphics processing units (GPUs) originally developed for 3D computer games have an architecture of massively parallel single instruction multiple data floating point units that is almost ideally suited for the algorithms employed in partial wave analysis. We have implemented a framework for tensor manipulation and partial wave fits called GPUPWA. The user writes a program in pure C++ whilst the GPUPWA classes handle computations on the GPU, memory transfers, caching and other technical details. In conjunction with a recent graphics processor, the framework provides a speed-up of the partial wave fit by more than two orders of magnitude compared to legacy FORTRAN code.
Analysis of critically refracted longitudinal waves
Energy Technology Data Exchange (ETDEWEB)
Pei, Ning, E-mail: npei@iastate.edu; Bond, Leonard J., E-mail: npei@iastate.edu [Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50011 (United States)
2015-03-31
Fabrication processes, such as, welding, forging, and rolling can induce residual stresses in metals that will impact product performance and phenomena such as cracking and corrosion. To better manage residual stress tools are needed to map their distribution. The critically refracted ultrasonic longitudinal (LCR) wave is one such approach that has been used for residual stress characterization. It has been shown to be sensitive to stress and less sensitive to the effects of the texture of the material. Although the LCR wave is increasingly widely applied, the factors that influence the formation of the LCR beam are seldom discussed. This paper reports a numerical model used to investigate the transducers' parameters that can contribute to the directionality of the LCR wave and hence enable performance optimization when used for industrial applications. An orthogonal test method is used to study the transducer parameters which influence the LCR wave beams. This method provides a design tool that can be used to study and optimize multiple parameter experiments and it can identify which parameter or parameters are of most significance. The simulation of the sound field in a 2-D 'water-steel' model is obtained using a Spatial Fourier Analysis method. The effects of incident angle, standoff, the aperture and the center frequency of the transducer were studied. Results show that the aperture of the transducer, the center frequency and the incident angle are the most important factors in controlling the directivity of the resulting LCR wave fields.
The analysis of interfacial waves
International Nuclear Information System (INIS)
Galimov, Azat Yu.; Drew, Donald A.; Lahey, Richard T.; Moraga, Francisco J.
2005-01-01
We present analytical results for stable stratified wavy two-phase flow and functional forms for the various interfacial force densities in a two-fluid model. In particular, we have derived analytically the components of the non-drag interfacial force density [Drew, D.A., Passman, S.L., 1998. Theory of Multicomponent Fluids. Springer-Verlag, New York; Nigmatulin, T.R., Drew, D.A., Lahey, R.T., Jr., 2000. An analysis of wavy annular flow. In: International Conference on Multiphase Systems, ICMS'2000, Ufa, Russia, June 15-17], Reynolds stress tensor, and the term, (p-bar cl i -p-bar cl )-bar α cl , where p-bar cl i is interfacial average pressure, p-bar cl the average pressure, and α cl is the volume fraction of the continuous liquid phase. These functional forms should be useful for assessing two-fluid closure relations and Computational Multiphase Fluid Dynamics (CMFD) numerical models for stratified wavy flows. Moreover, it appears that this approach can be generalized to other flow regimes (e.g., annular flows)
Statistical analysis of random pulse trains
International Nuclear Information System (INIS)
Da Costa, G.
1977-02-01
Some experimental and theoretical results concerning the statistical properties of optical beams formed by a finite number of independent pulses are presented. The considered waves (corresponding to each pulse) present important spatial variations of the illumination distribution in a cross-section of the beam, due to the time-varying random refractive index distribution in the active medium. Some examples of this kind of emission are: (a) Free-running ruby laser emission; (b) Mode-locked pulse trains; (c) Randomly excited nonlinear media
Numerical simulation of multi-directional random wave transformation in a yacht port
Ji, Qiaoling; Dong, Sheng; Zhao, Xizeng; Zhang, Guowei
2012-09-01
This paper extends a prediction model for multi-directional random wave transformation based on an energy balance equation by Mase with the consideration of wave shoaling, refraction, diffraction, reflection and breaking. This numerical model is improved by 1) introducing Wen's frequency spectrum and Mitsuyasu's directional function, which are more suitable to the coastal area of China; 2) considering energy dissipation caused by bottom friction, which ensures more accurate results for large-scale and shallow water areas; 3) taking into account a non-linear dispersion relation. Predictions using the extended wave model are carried out to study the feasibility of constructing the Ai Hua yacht port in Qingdao, China, with a comparison between two port layouts in design. Wave fields inside the port for different incident wave directions, water levels and return periods are simulated, and then two kinds of parameters are calculated to evaluate the wave conditions for the two layouts. Analyses show that Layout I is better than Layout II. Calculation results also show that the harbor will be calm for different wave directions under the design water level. On the contrary, the wave conditions do not wholly meet the requirements of a yacht port for ship berthing under the extreme water level. For safety consideration, the elevation of the breakwater might need to be properly increased to prevent wave overtopping under such water level. The extended numerical simulation model may provide an effective approach to computing wave heights in a harbor.
Sorghum cobalt analysis on not determined wave length with atomic ...
African Journals Online (AJOL)
This study was to know the better wave length on measuring cobalt content in forage sorghum hybrid (Sorghum bicolor) with an atomic absorption spectrophotometer. The analysis was on background correction mode with three wave lengths; 240.8, 240.7 (determined wave length or recommended wave length) and 240.6 ...
Bull, Diana
2014-01-01
A stochastic approach is used to gain a sophisticated understanding of a non-axisymmetric floating oscillating water column's response to random waves. A linear, frequency-domain performance model that links the oscillating structure to air-pressure fluctuations with a Wells Turbine in 3-dimensions is used to study the device performance at a northern California deployment location. Both short-term, sea-state, and long-term, annual, predictions are made regarding the devices performance. U...
Nonlinear and diffraction effects in propagation of N-waves in randomly inhomogeneous moving media.
Averiyanov, Mikhail; Blanc-Benon, Philippe; Cleveland, Robin O; Khokhlova, Vera
2011-04-01
Finite amplitude acoustic wave propagation through atmospheric turbulence is modeled using a Khokhlov-Zabolotskaya-Kuznetsov (KZK)-type equation. The equation accounts for the combined effects of nonlinearity, diffraction, absorption, and vectorial inhomogeneities of the medium. A numerical algorithm is developed which uses a shock capturing scheme to reduce the number of temporal grid points. The inhomogeneous medium is modeled using random Fourier modes technique. Propagation of N-waves through the medium produces regions of focusing and defocusing that is consistent with geometrical ray theory. However, differences up to ten wavelengths are observed in the locations of fist foci. Nonlinear effects are shown to enhance local focusing, increase the maximum peak pressure (up to 60%), and decrease the shock rise time (about 30 times). Although the peak pressure increases and the rise time decreases in focal regions, statistical analysis across the entire wavefront at a distance 120 wavelengths from the source indicates that turbulence: decreases the mean time-of-flight by 15% of a pulse duration, decreases the mean peak pressure by 6%, and increases the mean rise time by almost 100%. The peak pressure and the arrival time are primarily governed by large scale inhomogeneities, while the rise time is also sensitive to small scales.
Near-surface compressional and shear wave speeds constrained by body-wave polarization analysis
Park, Sunyoung; Ishii, Miaki
2018-06-01
A new technique to constrain near-surface seismic structure that relates body-wave polarization direction to the wave speed immediately beneath a seismic station is presented. The P-wave polarization direction is only sensitive to shear wave speed but not to compressional wave speed, while the S-wave polarization direction is sensitive to both wave speeds. The technique is applied to data from the High-Sensitivity Seismograph Network in Japan, and the results show that the wave speed estimates obtained from polarization analysis are compatible with those from borehole measurements. The lateral variations in wave speeds correlate with geological and physical features such as topography and volcanoes. The technique requires minimal computation resources, and can be used on any number of three-component teleseismic recordings, opening opportunities for non-invasive and inexpensive study of the shallowest (˜100 m) crustal structures.
Nonstationary random acoustic and electromagnetic fields as wave diffusion processes
International Nuclear Information System (INIS)
Arnaut, L R
2007-01-01
We investigate the effects of relatively rapid variations of the boundaries of an overmoded cavity on the stochastic properties of its interior acoustic or electromagnetic field. For quasi-static variations, this field can be represented as an ideal incoherent and statistically homogeneous isotropic random scalar or vector field, respectively. A physical model is constructed showing that the field dynamics can be characterized as a generalized diffusion process. The Langevin-It o-hat and Fokker-Planck equations are derived and their associated statistics and distributions for the complex analytic field, its magnitude and energy density are computed. The energy diffusion parameter is found to be proportional to the square of the ratio of the standard deviation of the source field to the characteristic time constant of the dynamic process, but is independent of the initial energy density, to first order. The energy drift vanishes in the asymptotic limit. The time-energy probability distribution is in general not separable, as a result of nonstationarity. A general solution of the Fokker-Planck equation is obtained in integral form, together with explicit closed-form solutions for several asymptotic cases. The findings extend known results on statistics and distributions of quasi-stationary ideal random fields (pure diffusions), which are retrieved as special cases
Attenuation Analysis of Lamb Waves Using the Chirplet Transform
Kerber, Florian; Sprenger, Helge; Niethammer, Marc; Luangvilai, Kritsakorn; Jacobs, Laurence J.
2010-01-01
Guided Lamb waves are commonly used in nondestructive evaluation to monitor plate-like structures or to characterize properties of composite or layered materials. However, the dispersive propagation and multimode excitability of Lamb waves complicate their analysis. Advanced signal processing
International Nuclear Information System (INIS)
Ryutova, M.
1990-08-01
Effects of strong and random inhomogeneities of the magnetic fields, plasma density, and temperature in the solar atmosphere on the properties of magnetoacoustic waves of arbitrary amplitudes are studied. The procedure which allows one to obtain the averaged equation containing the nonlinearity of a wave, dispersion properties of a system, and dissipative effects is described. It is shown that depending on the statistical properties of the medium, different scenarios of wave propagation arise: in the predominance of dissipative effects the primary wave is damped away in the linear stage and the efficiency of heating due to inhomogeneities is much greater than that in homogeneous medium. Depending on the interplay of nonlinear and dispersion effects, the process of heating can be afforded through the formation of shocks or through the storing of energy in a system of solitons which are later damped away. Our computer simulation supports and extends the above theoretical investigations. In particular the enhanced dissipation of waves due to the strong and random inhomogeneities is observed and this is more pronounced for shorter waves
A multiple scattering theory for EM wave propagation in a dense random medium
Karam, M. A.; Fung, A. K.; Wong, K. W.
1985-01-01
For a dense medium of randomly distributed scatterers an integral formulation for the total coherent field has been developed. This formulation accounts for the multiple scattering of electromagnetic waves including both the twoand three-particle terms. It is shown that under the Markovian assumption the total coherent field and the effective field have the same effective wave number. As an illustration of this theory, the effective wave number and the extinction coefficient are derived in terms of the polarizability tensor and the pair distribution function for randomly distributed small spherical scatterers. It is found that the contribution of the three-particle term increases with the particle size, the volume fraction, the frequency and the permittivity of the particle. This increase is more significant with frequency and particle size than with other parameters.
Resolution analysis by random probing
Fichtner, Andreas; van Leeuwen, T.
2015-01-01
We develop and apply methods for resolution analysis in tomography, based on stochastic probing of the Hessian or resolution operators. Key properties of our methods are (i) low algorithmic complexity and easy implementation, (ii) applicability to any tomographic technique, including full‐waveform
Simulation study of localization of electromagnetic waves in two-dimensional random dipolar systems
International Nuclear Information System (INIS)
Wang, Ken Kang-Hsin; Ye Zhen
2003-01-01
We study the propagation and scattering of electromagnetic waves by random arrays of dipolar cylinders in a uniform medium. A set of self-consistent equations, incorporating all orders of multiple scattering of the electromagnetic waves, is derived from first principles and then solved numerically for electromagnetic fields. For certain ranges of frequencies, spatially localized electromagnetic waves appear in such a simple but realistic disordered system. Dependence of localization on the frequency, radiation damping, and filling factor is shown. The spatial behavior of the total, coherent, and diffusive waves is explored in detail, and found to comply with a physical intuitive picture. A phase diagram characterizing localization is presented, in agreement with previous investigations on other systems
Simulation study of localization of electromagnetic waves in two-dimensional random dipolar systems.
Wang, Ken Kang-Hsin; Ye, Zhen
2003-12-01
We study the propagation and scattering of electromagnetic waves by random arrays of dipolar cylinders in a uniform medium. A set of self-consistent equations, incorporating all orders of multiple scattering of the electromagnetic waves, is derived from first principles and then solved numerically for electromagnetic fields. For certain ranges of frequencies, spatially localized electromagnetic waves appear in such a simple but realistic disordered system. Dependence of localization on the frequency, radiation damping, and filling factor is shown. The spatial behavior of the total, coherent, and diffusive waves is explored in detail, and found to comply with a physical intuitive picture. A phase diagram characterizing localization is presented, in agreement with previous investigations on other systems.
Potential and limitations of wave intensity analysis in coronary arteries
Siebes, M.; Kolyva, C.; Verhoeff, B.J.; Piek, J.J.; Spaan, J.A.
2009-01-01
Wave intensity analysis (WIA) is beginning to be applied to the coronary circulation both to better understand coronary physiology and as a diagnostic tool. Separation of wave intensity (WI) into forward and backward traveling components requires knowledge of pulse wave velocity at the point of
Assessing ground compaction via time lapse surface wave analysis
Czech Academy of Sciences Publication Activity Database
Dal Moro, Giancarlo; Al-Arifi, N.; Moustafa, S.S.R.
2016-01-01
Roč. 13, č. 3 (2016), s. 249-256 ISSN 1214-9705 Institutional support: RVO:67985891 Keywords : Full velocity spectrum (FVS) analysis * ground compaction * ground compaction * phase velocities * Rayleigh waves * seismic data inversion * surface wave dispersion * surface waves Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.699, year: 2016
A Semi-Analytical Method for the PDFs of A Ship Rolling in Random Oblique Waves
Liu, Li-qin; Liu, Ya-liu; Xu, Wan-hai; Li, Yan; Tang, You-gang
2018-03-01
The PDFs (probability density functions) and probability of a ship rolling under the random parametric and forced excitations were studied by a semi-analytical method. The rolling motion equation of the ship in random oblique waves was established. The righting arm obtained by the numerical simulation was approximately fitted by an analytical function. The irregular waves were decomposed into two Gauss stationary random processes, and the CARMA (2, 1) model was used to fit the spectral density function of parametric and forced excitations. The stochastic energy envelope averaging method was used to solve the PDFs and the probability. The validity of the semi-analytical method was verified by the Monte Carlo method. The C11 ship was taken as an example, and the influences of the system parameters on the PDFs and probability were analyzed. The results show that the probability of ship rolling is affected by the characteristic wave height, wave length, and the heading angle. In order to provide proper advice for the ship's manoeuvring, the parametric excitations should be considered appropriately when the ship navigates in the oblique seas.
Scattering of elastic waves on fractures randomly distributed in a three-dimensional medium
Strizhkov, S. A.; Ponyatovskaya, V. I.
1985-02-01
The purpose of this work is to determine the variation in basic characteristics of the wave field formed in a jointed medium, such as the intensity of fluctuations of amplitude, correlation radius, scattering coefficient and frequency composition of waves, as functions of jointing parameters. Fractures are simulated by flat plates randomly distributed and chaotically oriented in a three-dimensional medium. Experiments were performed using an alabaster model, a rectangular block measuring 50 x 50 x 120 mm. The plates were introduced into liquid alabaster which was then agitated. Models made in this way contain randomly distributed and chaotically oriented fractures. The influence of these fractures appears as fluctuations in the wave field formed in the medium. The data obtained in experimental studies showed that the dimensions of heterogeneities determined by waves in the jointed medium and the dimensions of the fractures themselves coincide only if the distance between fractures is rather great. If the distance between fractures is less than the wavelength, the dimensions of the heterogeneities located by the wave depend on wavelength.
Analysis of a plane stress wave by the moving least squares method
Directory of Open Access Journals (Sweden)
Wojciech Dornowski
2014-08-01
Full Text Available A meshless method based on the moving least squares approximation is applied to stress wave propagation analysis. Two kinds of node meshes, the randomly generated mesh and the regular mesh are used. The nearest neighbours’ problem is developed from a triangulation that satisfies minimum edges length conditions. It is found that this method of neighbours’ choice significantly improves the solution accuracy. The reflection of stress waves from the free edge is modelled using fictitious nodes (outside the plate. The comparison with the finite difference results also demonstrated the accuracy of the proposed approach.[b]Keywords[/b]: civil engineering, meshless method, moving least squares method, elastic waves
Trend analysis of wave storminess: wave direction and its impact on harbour agitation
Directory of Open Access Journals (Sweden)
M. Casas-Prat
2010-11-01
Full Text Available In the context of wave climate variability, long-term alterations in the wave storminess pattern of the Catalan coast (northwestern Mediterranean Sea are analysed in terms of wave energy content and wave direction, on the basis of wave hindcast data (from 44-year time series. In general, no significant temporal trends are found for annual mean and maximum energy. However, the same analysis carried out separately for different wave directions reveals a remarkable increase in the storm energy of events from the south, which is partly due to a rise in the annual percentage of such storms. A case study of Tarragona Port (on the southern Catalan coast highlights the importance of including changes in wave direction in the study of potential impacts of climate change. In particular, an increase in the frequency of storms from the south leads to greater agitation inside the Port.
Li, Jia; Wu, Pinghui; Chang, Liping
2015-08-24
Within the accuracy of the first-order Born approximation, sufficient conditions are derived for the invariance of spectrum of an electromagnetic wave, which is generated by the scattering of an electromagnetic plane wave from an anisotropic random media. We show that the following restrictions on properties of incident fields and the anisotropic media must be simultaneously satisfied: 1) the elements of the dielectric susceptibility matrix of the media must obey the scaling law; 2) the spectral components of the incident field are proportional to each other; 3) the second moments of the elements of the dielectric susceptibility matrix of the media are inversely proportional to the frequency.
Mathematical Methods in Wave Propagation: Part 2--Non-Linear Wave Front Analysis
Jeffrey, Alan
1971-01-01
The paper presents applications and methods of analysis for non-linear hyperbolic partial differential equations. The paper is concluded by an account of wave front analysis as applied to the piston problem of gas dynamics. (JG)
CFD Analysis of Water Solitary Wave Reflection
Directory of Open Access Journals (Sweden)
K. Smida
2011-12-01
Full Text Available A new numerical wave generation method is used to investigate the head-on collision of two solitary waves. The reflection at vertical wall of a solitary wave is also presented. The originality of this model, based on the Navier-Stokes equations, is the specification of an internal inlet velocity, defined as a source line within the computational domain for the generation of these non linear waves. This model was successfully implemented in the PHOENICS (Parabolic Hyperbolic Or Elliptic Numerical Integration Code Series code. The collision of two counter-propagating solitary waves is similar to the interaction of a soliton with a vertical wall. This wave generation method allows the saving of considerable time for this collision process since the counter-propagating wave is generated directly without reflection at vertical wall. For the collision of two solitary waves, numerical results show that the run-up phenomenon can be well explained, the solution of the maximum wave run-up is almost equal to experimental measurement. The simulated wave profiles during the collision are in good agreement with experimental results. For the reflection at vertical wall, the spatial profiles of the wave at fixed instants show that this problem is equivalent to the collision process.
Wave-equation Migration Velocity Analysis Using Plane-wave Common Image Gathers
Guo, Bowen
2017-06-01
Wave-equation migration velocity analysis (WEMVA) based on subsurface-offset, angle domain or time-lag common image gathers (CIGs) requires significant computational and memory resources because it computes higher dimensional migration images in the extended image domain. To mitigate this problem, a WEMVA method using plane-wave CIGs is presented. Plane-wave CIGs reduce the computational cost and memory storage because they are directly calculated from prestack plane-wave migration, and the number of plane waves is often much smaller than the number of shots. In the case of an inaccurate migration velocity, the moveout of plane-wave CIGs is automatically picked by a semblance analysis method, which is then linked to the migration velocity update by a connective function. Numerical tests on two synthetic datasets and a field dataset validate the efficiency and effectiveness of this method.
Energy Technology Data Exchange (ETDEWEB)
Cryns, Jackson W.; Hatchell, Brian K.; Santiago-Rojas, Emiliano; Silvers, Kurt L.
2013-07-01
Formal journal article Experimental analysis of a piezoelectric energy harvesting system for harmonic, random, and sine on random vibration Abstract: Harvesting power with a piezoelectric vibration powered generator using a full-wave rectifier conditioning circuit is experimentally compared for varying sinusoidal, random and sine on random (SOR) input vibration scenarios. Additionally, the implications of source vibration characteristics on harvester design are discussed. Studies in vibration harvesting have yielded numerous alternatives for harvesting electrical energy from vibrations but piezoceramics arose as the most compact, energy dense means of energy transduction. The rise in popularity of harvesting energy from ambient vibrations has made piezoelectric generators commercially available. Much of the available literature focuses on maximizing harvested power through nonlinear processing circuits that require accurate knowledge of generator internal mechanical and electrical characteristics and idealization of the input vibration source, which cannot be assumed in general application. In this manuscript, variations in source vibration and load resistance are explored for a commercially available piezoelectric generator. We characterize the source vibration by its acceleration response for repeatability and transcription to general application. The results agree with numerical and theoretical predictions for in previous literature that load optimal resistance varies with transducer natural frequency and source type, and the findings demonstrate that significant gains are seen with lower tuned transducer natural frequencies for similar source amplitudes. Going beyond idealized steady state sinusoidal and simplified random vibration input, SOR testing allows for more accurate representation of real world ambient vibration. It is shown that characteristic interactions from more complex vibrational sources significantly alter power generation and power processing
Dynamics of wave packets in two-dimensional random systems with anisotropic disorder.
Samelsohn, Gregory; Gruzdev, Eugene
2008-09-01
A theoretical model is proposed to describe narrowband pulse dynamics in two-dimensional systems with arbitrary correlated disorder. In anisotropic systems with elongated cigarlike inhomogeneities, fast propagation is predicted in the direction across the structure where the wave is exponentially localized and tunneling of evanescent modes plays a dominant role in typical realizations. Along the structure, where the wave is channeled as in a waveguide, the motion of the wave energy is relatively slow. Numerical simulations performed for ultra-wide-band pulses show that even at the initial stage of wave evolution, the radiation diffuses predominantly in the direction along the major axis of the correlation ellipse. Spectral analysis of the results relates the long tail of the wave observed in the transverse direction to a number of frequency domain "lucky shots" associated with the long-living resonant modes localized inside the sample.
Directory of Open Access Journals (Sweden)
Moshirfar M
2011-09-01
Full Text Available Majid Moshirfar1, Brent S Betts2, Daniel S Churgin3, Maylon Hsu1, Marcus Neuffer1, Shameema Sikder4, Dane Church5, Mark D Mifflin11John A Moran Eye Center, Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, UT, USA; 2Temple University School of Medicine, Philadelphia, PA, USA; 3University of Arizona College of Medicine – Phoenix, Phoenix, AZ, USA; 4Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA; 5Virginia Commonwealth University School of Medicine, Richmond, VA, USAPurpose: To compare outcomes in visual acuity, refractive error, higher-order aberrations (HOAs, contrast sensitivity, and dry eye in patients undergoing laser in situ keratomileusis (LASIK using wavefront (WF guided VISX CustomVue and WF optimized WaveLight Allegretto platforms.Methods: In this randomized, prospective, single-masked, fellow eye study, LASIK was performed on 44 eyes (22 patients, with one eye randomized to WaveLight Allegretto, and the fellow eye receiving VISX CustomVue. Postoperative outcome measures at 3 months included uncorrected distance visual acuity (UDVA, corrected distance visual acuity (CDVA, refractive error, root-mean-square (RMS value of total and grouped HOAs, contrast sensitivity, and Schirmers testing.Results: Mean values for UDVA (logMAR were -0.067 ± 0.087 and -0.073 ± 0.092 in the WF optimized and WF guided groups, respectively (P = 0.909. UDVA of 20/20 or better was achieved in 91% of eyes undergoing LASIK with both lasers while UDVA of 20/15 or better was achieved in 64% of eyes using the Allegretto platform, and 59% of eyes using VISX CustomVue (P = 1.000. In the WF optimized group, total HOA increased 4% (P = 0.012, coma increased 11% (P = 0.065, and spherical aberration increased 19% (P = 0.214, while trefoil decreased 5% (P = 0.490. In the WF guided group, total HOA RMS decreased 9% (P = 0.126, coma decreased 18% (P = 0.144, spherical aberration decreased 27% (P = 0.713 and trefoil
Wave energy patterns of counterpulsation: a novel approach with wave intensity analysis.
Lu, Pong-Jeu; Yang, Chi-Fu Jeffrey; Wu, Meng-Yu; Hung, Chun-Hao; Chan, Ming-Yao; Hsu, Tzu-Cheng
2011-11-01
In counterpulsation, diastolic augmentation increases coronary blood flow and systolic unloading reduces left ventricular afterload. We present a new approach with wave intensity analysis to revisit and explain counterpulsation principles. In an acute porcine model, a standard intra-aortic balloon pump was placed in descending aorta in 4 pigs. We measured pressure and velocity with probes in left anterior descending artery and aorta during and without intra-aortic balloon pump assistance. Wave intensities of aortic and left coronary waves were derived from pressure and flow measurements with synchronization correction. We identified predominating waves in counterpulsation. In the aorta, during diastolic augmentation, intra-aortic balloon inflation generated a backward compression wave, with a "pushing" effect toward the aortic root that translated to a forward compression wave into coronary circulation. During systolic unloading, intra-aortic balloon pump deflation generated a backward expansion wave that "sucked" blood from left coronary bed into the aorta. While this backward expansion wave translated to reduced left ventricular afterload, the "sucking" effect resulted in left coronary blood steal, as demonstrated by a forward expansion wave in left anterior descending coronary flow. The waves were sensitive to inflation and deflation timing, with just 25 ms delay from standard deflation timing leading to weaker forward expansion wave and less coronary regurgitation. Intra-aortic balloon pumps generate backward-traveling waves that predominantly drive aortic and coronary blood flow during counterpulsation. Wave intensity analysis of arterial circulations may provide a mechanism to explain diastolic augmentation and systolic unloading of intra-aortic balloon pump counterpulsation. Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.
Chen, Pengzhen; Wang, Xiaoqing; Liu, Li; Chong, Jinsong
2016-06-01
According to Bragg theory, capillary waves are the predominant scatterers of high-frequency band (such as Ka-band) microwave radiation from the surface of the ocean. Therefore, understanding the modulation mechanism of capillary waves is an important foundation for interpreting high-frequency microwave remote sensing images of the surface of the sea. In our experiments, we discovered that modulations of capillary waves are significantly larger than the values predicted by the classical theory. Further, analysis shows that the difference in restoring force results in an inflection point while the phase velocity changes from gravity waves region to capillary waves region, and this results in the capillary waves being able to resonate with gravity waves when the phase velocity of the gravity waves is equal to the group velocity of the capillary waves. Consequently, we propose a coupling modulation model in which the current modulates the capillary wave indirectly by modulating the resonant gravity waves, and the modulation of the former is approximated by that of the latter. This model very effectively explains the results discovered in our experiments. Further, based on Bragg scattering theory and this coupling modulation model, we simulate the modulation of normalized radar cross section (NRCS) of typical internal waves and show that the high-frequency bands are superior to the low-frequency bands because of their greater modulation of NRCS and better radiometric resolution. This result provides new support for choice of radar band for observation of wave-current modulation oceanic phenomena such as internal waves, fronts, and shears.
Parametric interaction of waves in the plasma with random large-scale inhomogeneities
International Nuclear Information System (INIS)
Abramovich, B.S.; Tamojkin, V.V.
1980-01-01
Parametric processes of the decay and fusion of three waves in a weakly turbulent plasma with random inhomogeneities, the size of which is too big as compared with wave-lengths are considered. Under the diffusive approximation applicability closed equations are obtained, which determine the behaviour of all the intensity moments of parametrically bound waves. It is shown that under the conditions when the characteristic length of the multiple scattering is considerably less than the nonlinear interaction, length the effective increment of average intensity increase and its moments at dissociation processes is too small as compared with the homogeneous plasma case. At fusion processes the same increment (decrement) determines the distance at which all intensity moments are in the saturation regime
Random-Access Technique for Self-Organization of 5G Millimeter-Wave Cellular Communications
Directory of Open Access Journals (Sweden)
Jasper Meynard Arana
2016-01-01
Full Text Available The random-access (RA technique is a key procedure in cellular networks and self-organizing networks (SONs, but the overall processing time of this technique in millimeter-wave (mm-wave cellular systems with directional beams is very long because RA preambles (RAPs should be transmitted in all directions of Tx and Rx beams. In this paper, two different types of preambles (RAP-1 and RAP-2 are proposed to reduce the processing time in the RA stage. After analyzing the correlation property, false-alarm probability, and detection probability of the proposed RAPs, we perform simulations to show that the RAP-2 is suitable for RA in mm-wave cellular systems with directional beams because of the smaller processing time and high detection probability in multiuser environments.
A time-frequency analysis of wave packet fractional revivals
International Nuclear Information System (INIS)
Ghosh, Suranjana; Banerji, J
2007-01-01
We show that the time-frequency analysis of the autocorrelation function is, in many ways, a more appropriate tool to resolve fractional revivals of a wave packet than the usual time-domain analysis. This advantage is crucial in reconstructing the initial state of the wave packet when its coherent structure is short-lived and decays before it is fully revived. Our calculations are based on the model example of fractional revivals in a Rydberg wave packet of circular states. We end by providing an analytical investigation which fully agrees with our numerical observations on the utility of time-frequency analysis in the study of wave packet fractional revivals
Ground States of Random Spanning Trees on a D-Wave 2X
Hall, J. S.; Hobl, L.; Novotny, M. A.; Michielsen, Kristel
The performances of two D-Wave 2 machines (476 and 496 qubits) and of a 1097-qubit D-Wave 2X were investigated. Each chip has a Chimera interaction graph calG . Problem input consists of values for the fields hj and for the two-qubit interactions Ji , j of an Ising spin-glass problem formulated on calG . Output is returned in terms of a spin configuration {sj } , with sj = +/- 1 . We generated random spanning trees (RSTs) uniformly distributed over all spanning trees of calG . On the 476-qubit D-Wave 2, RSTs were generated on the full chip with Ji , j = - 1 and hj = 0 and solved one thousand times. The distribution of solution energies and the average magnetization of each qubit were determined. On both the 476- and 1097-qubit machines, four identical spanning trees were generated on each quadrant of the chip. The statistical independence of these regions was investigated. In another study, on the D-Wave 2X, one hundred RSTs with random Ji , j ∈ { - 1 , 1 } and hj = 0 were generated on the full chip. Each RST problem was solved one hundred times and the number of times the ground state energy was found was recorded. This procedure was repeated for square subgraphs, with dimensions ranging from 7 ×7 to 11 ×11. Supported in part by NSF Grants DGE-0947419 and DMR-1206233. D-Wave time provided by D-Wave Systems and by the USRA Quantum Artificial Intelligence Laboratory Research Opportunity.
Electromagnetic Cyclotron Waves in the Solar Wind: Wind Observation and Wave Dispersion Analysis
Jian, L. K.; Moya, P. S.; Vinas, A. F.; Stevens, M.
2016-01-01
Wind observed long-lasting electromagnetic cyclotron waves near the proton cyclotron frequency on 11 March 2005, in the descending part of a fast wind stream. Bi-Maxwellian velocity distributions are fitted for core protons, beam protons, and alpha-particles. Using the fitted plasma parameters we conduct kinetic linear dispersion analysis and find ion cyclotron and/or firehose instabilities grow in six of 10 wave intervals. After Doppler shift, some of the waves have frequency and polarization consistent with observation, thus may be correspondence to the cyclotron waves observed.
Wave-equation Migration Velocity Analysis Using Plane-wave Common Image Gathers
Guo, Bowen; Schuster, Gerard T.
2017-01-01
Wave-equation migration velocity analysis (WEMVA) based on subsurface-offset, angle domain or time-lag common image gathers (CIGs) requires significant computational and memory resources because it computes higher dimensional migration images
Survivor bias in Mendelian randomization analysis
DEFF Research Database (Denmark)
Vansteelandt, Stijn; Dukes, Oliver; Martinussen, Torben
2017-01-01
Mendelian randomization studies employ genotypes as experimental handles to infer the effect of genetically modified exposures (e.g. vitamin D exposure) on disease outcomes (e.g. mortality). The statistical analysis of these studies makes use of the standard instrumental variables framework. Many...... of these studies focus on elderly populations, thereby ignoring the problem of left truncation, which arises due to the selection of study participants being conditional upon surviving up to the time of study onset. Such selection, in general, invalidates the assumptions on which the instrumental variables...... analysis rests. We show that Mendelian randomization studies of adult or elderly populations will therefore, in general, return biased estimates of the exposure effect when the considered genotype affects mortality; in contrast, standard tests of the causal null hypothesis that the exposure does not affect...
Theory analysis and simple calculation of travelling wave burnup scheme
International Nuclear Information System (INIS)
Zhang Jian; Yu Hong; Gang Zhi
2012-01-01
Travelling wave burnup scheme is a new burnup scheme that breeds fuel locally just before it burns. Based on the preliminary theory analysis, the physical imagine was found. Through the calculation of a R-z cylinder travelling wave reactor core with ERANOS code system, the basic physical characteristics of this new burnup scheme were concluded. The results show that travelling wave reactor is feasible in physics, and there are some good features in the reactor physics. (authors)
Mountain Wave Analysis Using Fourier Methods
National Research Council Canada - National Science Library
Roadcap, John R
2007-01-01
...) their requirements for only a coarse horizontal background state. Common traits of Fourier mountain wave models include use of the Boussinesq approximation and neglect of moisture and Coriolis terms...
Analysis of Z Pinch Shock Wave Experiments
International Nuclear Information System (INIS)
Asay, James; Budge, Kent G.; Chandler, Gordon; Fleming, Kevin; Hall, Clint; Holland, Kathleen; Konrad, Carl; Lawrence, Jeffery; Trott, Wayne; Trucano, Timothy
1999-01-01
In this paper, we report details of our computational study of two shock wave physics experiments performed on the Sandia Z machine in 1998. The novelty of these particular experiments is that they represent the first successful application of VISAR interferometry to diagnose shock waves generated in experimental payloads by the primary X-ray pulse of the machine. We use the Sandia shock-wave physics code ALEGRA to perform the simulations reported in this study. Our simulations are found to be in fair agreement with the time-resolved VISAR experimental data. However, there are also interesting and important discrepancies. We speculate as to future use of time-resolved shock wave data to diagnose details of the Z machine X-ray pulse in the future
Huang, N. E.; Tung, C.-C.
1977-01-01
The influence of the directional distribution of wave energy on the dispersion relation is calculated numerically using various directional wave spectrum models. The results indicate that the dispersion relation varies both as a function of the directional energy distribution and the direction of propagation of the wave component under consideration. Furthermore, both the mean deviation and the random scatter from the linear approximation increase as the energy spreading decreases. Limited observational data are compared with the theoretical results. The agreement is favorable.
3D Guided Wave Motion Analysis on Laminated Composites
Tian, Zhenhua; Leckey, Cara; Yu, Lingyu
2013-01-01
Ultrasonic guided waves have proved useful for structural health monitoring (SHM) and nondestructive evaluation (NDE) due to their ability to propagate long distances with less energy loss compared to bulk waves and due to their sensitivity to small defects in the structure. Analysis of actively transmitted ultrasonic signals has long been used to detect and assess damage. However, there remain many challenging tasks for guided wave based SHM due to the complexity involved with propagating guided waves, especially in the case of composite materials. The multimodal nature of the ultrasonic guided waves complicates the related damage analysis. This paper presents results from parallel 3D elastodynamic finite integration technique (EFIT) simulations used to acquire 3D wave motion in the subject laminated carbon fiber reinforced polymer composites. The acquired 3D wave motion is then analyzed by frequency-wavenumber analysis to study the wave propagation and interaction in the composite laminate. The frequency-wavenumber analysis enables the study of individual modes and visualization of mode conversion. Delamination damage has been incorporated into the EFIT model to generate "damaged" data. The potential for damage detection in laminated composites is discussed in the end.
Analysis of Measured and Simulated Supraglottal Acoustic Waves.
Fraile, Rubén; Evdokimova, Vera V; Evgrafova, Karina V; Godino-Llorente, Juan I; Skrelin, Pavel A
2016-09-01
To date, although much attention has been paid to the estimation and modeling of the voice source (ie, the glottal airflow volume velocity), the measurement and characterization of the supraglottal pressure wave have been much less studied. Some previous results have unveiled that the supraglottal pressure wave has some spectral resonances similar to those of the voice pressure wave. This makes the supraglottal wave partially intelligible. Although the explanation for such effect seems to be clearly related to the reflected pressure wave traveling upstream along the vocal tract, the influence that nonlinear source-filter interaction has on it is not as clear. This article provides an insight into this issue by comparing the acoustic analyses of measured and simulated supraglottal and voice waves. Simulations have been performed using a high-dimensional discrete vocal fold model. Results of such comparative analysis indicate that spectral resonances in the supraglottal wave are mainly caused by the regressive pressure wave that travels upstream along the vocal tract and not by source-tract interaction. On the contrary and according to simulation results, source-tract interaction has a role in the loss of intelligibility that happens in the supraglottal wave with respect to the voice wave. This loss of intelligibility mainly corresponds to spectral differences for frequencies above 1500 Hz. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.
Data envelopment analysis of randomized ranks
Directory of Open Access Journals (Sweden)
Sant'Anna Annibal P.
2002-01-01
Full Text Available Probabilities and odds, derived from vectors of ranks, are here compared as measures of efficiency of decision-making units (DMUs. These measures are computed with the goal of providing preliminary information before starting a Data Envelopment Analysis (DEA or the application of any other evaluation or composition of preferences methodology. Preferences, quality and productivity evaluations are usually measured with errors or subject to influence of other random disturbances. Reducing evaluations to ranks and treating the ranks as estimates of location parameters of random variables, we are able to compute the probability of each DMU being classified as the best according to the consumption of each input and the production of each output. Employing the probabilities of being the best as efficiency measures, we stretch distances between the most efficient units. We combine these partial probabilities in a global efficiency score determined in terms of proximity to the efficiency frontier.
Topics in the Analysis of Shear-Wave Propagation in Oblique-Plate Impact Tests
National Research Council Canada - National Science Library
Scheidler, Mike
2007-01-01
This report addresses several topics in the theoretical analysis of shock waves, acceleration waves, and centered simple waves, with emphasis on the propagation of shear waves generated in oblique-plate impact tests...
Searching for Survivors through Random Human-Body Movement Outdoors by Continuous-Wave Radar Array.
Li, Chuantao; Chen, Fuming; Qi, Fugui; Liu, Miao; Li, Zhao; Liang, Fulai; Jing, Xijing; Lu, Guohua; Wang, Jianqi
2016-01-01
It is a major challenge to search for survivors after chemical or nuclear leakage or explosions. At present, biological radar can be used to achieve this goal by detecting the survivor's respiration signal. However, owing to the random posture of an injured person at a rescue site, the radar wave may directly irradiate the person's head or feet, in which it is difficult to detect the respiration signal. This paper describes a multichannel-based antenna array technology, which forms an omnidirectional detection system via 24-GHz Doppler biological radar, to address the random positioning relative to the antenna of an object to be detected. Furthermore, since the survivors often have random body movement such as struggling and twitching, the slight movements of the body caused by breathing are obscured by these movements. Therefore, a method is proposed to identify random human-body movement by utilizing multichannel information to calculate the background variance of the environment in combination with a constant-false-alarm-rate detector. The conducted outdoor experiments indicate that the system can realize the omnidirectional detection of random human-body movement and distinguish body movement from environmental interference such as movement of leaves and grass. The methods proposed in this paper will be a promising way to search for survivors outdoors.
Searching for Survivors through Random Human-Body Movement Outdoors by Continuous-Wave Radar Array
Liu, Miao; Li, Zhao; Liang, Fulai; Jing, Xijing; Lu, Guohua; Wang, Jianqi
2016-01-01
It is a major challenge to search for survivors after chemical or nuclear leakage or explosions. At present, biological radar can be used to achieve this goal by detecting the survivor’s respiration signal. However, owing to the random posture of an injured person at a rescue site, the radar wave may directly irradiate the person’s head or feet, in which it is difficult to detect the respiration signal. This paper describes a multichannel-based antenna array technology, which forms an omnidirectional detection system via 24-GHz Doppler biological radar, to address the random positioning relative to the antenna of an object to be detected. Furthermore, since the survivors often have random body movement such as struggling and twitching, the slight movements of the body caused by breathing are obscured by these movements. Therefore, a method is proposed to identify random human-body movement by utilizing multichannel information to calculate the background variance of the environment in combination with a constant-false-alarm-rate detector. The conducted outdoor experiments indicate that the system can realize the omnidirectional detection of random human-body movement and distinguish body movement from environmental interference such as movement of leaves and grass. The methods proposed in this paper will be a promising way to search for survivors outdoors. PMID:27073860
DANWEC - Empirical Analysis of the Wave Climate at the Danish Wave Energy Centre
DEFF Research Database (Denmark)
Tetu, Amelie; Nielsen, Kim; Kofoed, Jens Peter
information on the DanWEC wave and current climate. In this paper an analysis of the wave climate of the DanWEC test site will be presented. This includes a description of the data quality control and filtration for analysis and the observations and data analysis. Relevant characteristics of the test site...... site for several Danish WECs. In 2013 DanWEC has received Greenlab funding from the EUDP programme to establish the site including more detailed information on its wave climate and bathymetry and seabed conditions. The project “Resource Assessment, Forecasts and WECs O&M strategies at DanWEC and beyond......, as for example scatter diagram (Hm0, Tz) will be analysed and wave power distribution given. Based on the data gathered so far a preliminary analysis of extreme events at the DanWEC test site will be presented. Deployment, control strategies and O&M strategies of wave energy converters are sensitive to the wave...
Spectral analysis of surface waves method to assess shear wave velocity within centrifuge models
MURILLO, Carol Andrea; THOREL, Luc; CAICEDO, Bernardo
2009-01-01
The method of the spectral analysis of surface waves (SASW) is tested out on reduced scale centrifuge models, with a specific device, called the mini Falling Weight, developed for this purpose. Tests are performed on layered materials made of a mixture of sand and clay. The shear wave velocity VS determined within the models using the SASW is compared with the laboratory measurements carried out using the bender element test. The results show that the SASW technique applied to centrifuge test...
Analysis of sediment particle velocity in wave motion based on wave flume experiments
Krupiński, Adam
2012-10-01
The experiment described was one of the elements of research into sediment transport conducted by the Division of Geotechnics of West-Pomeranian University of Technology. The experimental analyses were performed within the framework of the project "Building a knowledge transfer network on the directions and perspectives of developing wave laboratory and in situ research using innovative research equipment" launched by the Institute of Hydroengineering of the Polish Academy of Sciences in Gdańsk. The objective of the experiment was to determine relations between sediment transport and wave motion parameters and then use the obtained results to modify formulas defining sediment transport in rivers, like Ackers-White formula, by introducing basic parameters of wave motion as the force generating bed material transport. The article presents selected results of the experiment concerning sediment velocity field analysis conducted for different parameters of wave motion. The velocity vectors of particles suspended in water were measured with a Particle Image Velocimetry (PIV) apparatus registering suspended particles in a measurement flume by producing a series of laser pulses and analysing their displacement with a high-sensitivity camera connected to a computer. The article presents velocity fields of suspended bed material particles measured in the longitudinal section of the wave flume and their comparison with water velocity profiles calculated for the definite wave parameters. The results presented will be used in further research for relating parameters essential for the description of monochromatic wave motion to basic sediment transport parameters and "transforming" mean velocity and dynamic velocity in steady motion to mean wave front velocity and dynamic velocity in wave motion for a single wave.
Le Bihan, Nicolas; Margerin, Ludovic
2009-07-01
In this paper, we present a nonparametric method to estimate the heterogeneity of a random medium from the angular distribution of intensity of waves transmitted through a slab of random material. Our approach is based on the modeling of forward multiple scattering using compound Poisson processes on compact Lie groups. The estimation technique is validated through numerical simulations based on radiative transfer theory.
Barrelet zeros in partial wave analysis
International Nuclear Information System (INIS)
Baker, R.D.
1976-01-01
The formalism of Barrelet zeros is discussed. Spinless scattering is described to introduce the idea, then the more usual case of 0 - 1/2 + → 0 - 1/2 + scattering. The zeros are regarded here only as a means to an end, viz the partial waves. The extraction of these is given in detail, and ambiguities are discussed at length. (author)
Geodesics analysis of colliding gravitational shock waves
International Nuclear Information System (INIS)
Pozdeeva, E.
2011-01-01
Full text: (author)We consider collision of charged gravitational shock waves with infinite transverse extension (charged gravitational walls). We study the influence of the charges on the trapped surface formation in the charged walls collision. This consideration has applications in the in heavy ion collisions using a holographic approach in which the charge plays the role of the chemical potential
Preliminary Analysis of a Submerged Wave Energy Device
Wagner, J. R.; Wagner, J. J.; Hayatdavoodi, M.; Ertekin, R. C.
2016-02-01
Preliminary analysis of a submerged wave energy harvesting device is presented. The device is composed of a thin, horizontally submerged plate that is restricted to heave oscillations under the influence of surface waves. The submerged plate is oscillating, and it can be attached to a fixed rotor, or a piston, to harvest the wave energy. A fully submerged wave energy converter is preferred over a surface energy convertor due to its durability and less visual and physical distractions it presents. In this study, the device is subject to nonlinear shallow-water waves. Wave loads on the submerged oscillating plate are obtained via the Level I Green-Naghdi equations. The unsteady motion of the plate is obtained by solving the nonlinear equations of motion. The results are obtained for a range of waves with varying heights and periods. The amplitude and period of plate oscillations are analyzed as functions of the wave parameters and plate width. Particular attention is given to the selection of the site of desired wave field. Initial estimation on the amount of energy extraction from the device, located near shore at a given site, is provided.
Two dimensional kinetic analysis of electrostatic harmonic plasma waves
Energy Technology Data Exchange (ETDEWEB)
Fonseca-Pongutá, E. C.; Ziebell, L. F.; Gaelzer, R. [Instituto de Física, UFRGS, 91501-970 Porto Alegre, RS (Brazil); Yoon, P. H. [IPST, University of Maryland, College Park, Maryland 20742 (United States); SSR, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of)
2016-06-15
Electrostatic harmonic Langmuir waves are virtual modes excited in weakly turbulent plasmas, first observed in early laboratory beam-plasma experiments as well as in rocket-borne active experiments in space. However, their unequivocal presence was confirmed through computer simulated experiments and subsequently theoretically explained. The peculiarity of harmonic Langmuir waves is that while their existence requires nonlinear response, their excitation mechanism and subsequent early time evolution are governed by essentially linear process. One of the unresolved theoretical issues regards the role of nonlinear wave-particle interaction process over longer evolution time period. Another outstanding issue is that existing theories for these modes are limited to one-dimensional space. The present paper carries out two dimensional theoretical analysis of fundamental and (first) harmonic Langmuir waves for the first time. The result shows that harmonic Langmuir wave is essentially governed by (quasi)linear process and that nonlinear wave-particle interaction plays no significant role in the time evolution of the wave spectrum. The numerical solutions of the two-dimensional wave spectra for fundamental and harmonic Langmuir waves are also found to be consistent with those obtained by direct particle-in-cell simulation method reported in the literature.
Zhang, Yin; Liang, Lanju; Yang, Jing; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian; Jin, Biaobing; Liu, Weiwei
2016-05-26
Suppressing specular electromagnetic wave reflection or backward radar cross section is important and of broad interests in practical electromagnetic engineering. Here, we present a scheme to achieve broadband backward scattering reduction through diffuse terahertz wave reflection by a flexible metasurface. The diffuse scattering of terahertz wave is caused by the randomized reflection phase distribution on the metasurface, which consists of meta-particles of differently sized metallic patches arranged on top of a grounded polyimide substrate simply through a certain computer generated pseudorandom sequence. Both numerical simulations and experimental results demonstrate the ultralow specular reflection over a broad frequency band and wide angle of incidence due to the re-distribution of the incident energy into various directions. The diffuse scattering property is also polarization insensitive and can be well preserved when the flexible metasurface is conformably wrapped on a curved reflective object. The proposed design opens up a new route for specular reflection suppression, and may be applicable in stealth and other technology in the terahertz spectrum.
Gong, Zheng; Chen, Tianrun; Ratilal, Purnima; Makris, Nicholas C
2013-11-01
An analytical model derived from normal mode theory for the accumulated effects of range-dependent multiple forward scattering is applied to estimate the temporal coherence of the acoustic field forward propagated through a continental-shelf waveguide containing random three-dimensional internal waves. The modeled coherence time scale of narrow band low-frequency acoustic field fluctuations after propagating through a continental-shelf waveguide is shown to decay with a power-law of range to the -1/2 beyond roughly 1 km, decrease with increasing internal wave energy, to be consistent with measured acoustic coherence time scales. The model should provide a useful prediction of the acoustic coherence time scale as a function of internal wave energy in continental-shelf environments. The acoustic coherence time scale is an important parameter in remote sensing applications because it determines (i) the time window within which standard coherent processing such as matched filtering may be conducted, and (ii) the number of statistically independent fluctuations in a given measurement period that determines the variance reduction possible by stationary averaging.
Analysis shear wave velocity structure obtained from surface wave methods in Bornova, Izmir
Energy Technology Data Exchange (ETDEWEB)
Pamuk, Eren, E-mail: eren.pamuk@deu.edu.tr; Akgün, Mustafa, E-mail: mustafa.akgun@deu.edu.tr [Department of Geophysical Engineering, Dokuz Eylul University, Izmir (Turkey); Özdağ, Özkan Cevdet, E-mail: cevdet.ozdag@deu.edu.tr [Dokuz Eylul University Rectorate, Izmir (Turkey)
2016-04-18
Properties of the soil from the bedrock is necessary to describe accurately and reliably for the reduction of earthquake damage. Because seismic waves change their amplitude and frequency content owing to acoustic impedance difference between soil and bedrock. Firstly, shear wave velocity and depth information of layers on bedrock is needed to detect this changing. Shear wave velocity can be obtained using inversion of Rayleigh wave dispersion curves obtained from surface wave methods (MASW- the Multichannel Analysis of Surface Waves, ReMi-Refraction Microtremor, SPAC-Spatial Autocorrelation). While research depth is limeted in active source study, a passive source methods are utilized for deep depth which is not reached using active source methods. ReMi method is used to determine layer thickness and velocity up to 100 m using seismic refraction measurement systems.The research carried out up to desired depth depending on radius using SPAC which is utilized easily in conditions that district using of seismic studies in the city. Vs profiles which are required to calculate deformations in under static and dynamic loads can be obtained with high resolution using combining rayleigh wave dispersion curve obtained from active and passive source methods. In the this study, Surface waves data were collected using the measurements of MASW, ReMi and SPAC at the İzmir Bornova region. Dispersion curves obtained from surface wave methods were combined in wide frequency band and Vs-depth profiles were obtained using inversion. Reliability of the resulting soil profiles were provided by comparison with theoretical transfer function obtained from soil paremeters and observed soil transfer function from Nakamura technique and by examination of fitting between these functions. Vs values are changed between 200-830 m/s and engineering bedrock (Vs>760 m/s) depth is approximately 150 m.
Analysis of seismic waves and strong ground motion
International Nuclear Information System (INIS)
Simpson, I.C.; Sutton, R.
1976-10-01
A number of Western USA earthquake acceleration-time histories concerning events of magnitude less than 6 are considered and their Fourier spectra calculated. An analysis of some of the simpler types of seismic wave is given in order to consider the generation of a spatially dependent acceleration-time history suitable for input into a soil-structure program of analysis. Such an acceleration-time history is required by a comprehensive analysis of soil-structure interaction since the conventionally assumed model of vertically propagating seismic waves, which give rise to three spatially independent ground motions, can lead to over-conservative estimates of the building response in the high frequency range. The possible application is discussed of a given component of a recorded acceleration-time history to the base of structure under the assumption of surface Rayleigh waves or obliquely incident P and SV bulk waves. (author)
Optimizing detection and analysis of slow waves in sleep EEG.
Mensen, Armand; Riedner, Brady; Tononi, Giulio
2016-12-01
Analysis of individual slow waves in EEG recording during sleep provides both greater sensitivity and specificity compared to spectral power measures. However, parameters for detection and analysis have not been widely explored and validated. We present a new, open-source, Matlab based, toolbox for the automatic detection and analysis of slow waves; with adjustable parameter settings, as well as manual correction and exploration of the results using a multi-faceted visualization tool. We explore a large search space of parameter settings for slow wave detection and measure their effects on a selection of outcome parameters. Every choice of parameter setting had some effect on at least one outcome parameter. In general, the largest effect sizes were found when choosing the EEG reference, type of canonical waveform, and amplitude thresholding. Previously published methods accurately detect large, global waves but are conservative and miss the detection of smaller amplitude, local slow waves. The toolbox has additional benefits in terms of speed, user-interface, and visualization options to compare and contrast slow waves. The exploration of parameter settings in the toolbox highlights the importance of careful selection of detection METHODS: The sensitivity and specificity of the automated detection can be improved by manually adding or deleting entire waves and or specific channels using the toolbox visualization functions. The toolbox standardizes the detection procedure, sets the stage for reliable results and comparisons and is easy to use without previous programming experience. Copyright © 2016 Elsevier B.V. All rights reserved.
Multi-directional random wave interaction with an array of cylinders
DEFF Research Database (Denmark)
Ji, Xinran; Liu, Shuxue; Bingham, Harry B.
2015-01-01
Based on the linear theory of wave interaction with an array of circular bottom-mounted vertical cylinders, systematic calculations are made to investigate the effects of the wave directionality on wave loads in short-crested seas. The multi-directional waves are specified using a discrete form...... of the Mitsuyasu-type spreading function. The time series of multi-directional wave loads, including both the wave run-up and wave force, can be simulated. The effect of wave directionality on the wave run-up and wave loading on the cylinders is investigated. For multi-directional waves, as the distribution...
Dispersive Wave Analysis Using the Chirplet Transform
International Nuclear Information System (INIS)
Kerber, Florian; Luangvilai, Kritsakorn; Kuttig, Helge; Niethammer, Marc; Jacobs, Laurence J.
2007-01-01
Time-frequency representations (TFR) are a widely used tool to analyze signals of guided waves such as Lamb waves. As a consequence of the uncertainty principle, however, the resolution in time and frequency is limited for all existing TFR methods. Due to the multi-modal and dispersive character of Lamb waves, displacement or energy related quantities can only be allocated to individual modes when they are well-separated in the time-frequency plane.The chirplet transform (CT) has been introduced as a generalization of both the wavelet and Short-time Fourier transform (STFT). It offers additional degrees of freedom to adjust time-frequency atoms which can be exploited in a model-based approach to match the group delay of individual modes. Thus, more exact allocation of quantities of interest is possible.The objective of this research is to use a previously developed adaptive algorithm based on the CT for nondestructive evaluation. Both numerically and experimentally generated data for a single aluminum plate is analyzed to determine the accuracy and robustness of the new method in comparison the classical STFT
Analysis of android random number generator
Sarıtaş, Serkan
2013-01-01
Ankara : The Department of Computer Engineering and the Graduate School of Engineering and Science of Bilkent University, 2013. Thesis (Master's) -- Bilkent University, 2013. Includes bibliographical references leaves 61-65. Randomness is a crucial resource for cryptography, and random number generators are critical building blocks of almost all cryptographic systems. Therefore, random number generation is one of the key parts of secure communication. Random number generatio...
Analysis of a cylindrical imploding shock wave
International Nuclear Information System (INIS)
Mishkin, E.A.; Fujimoto, Y.
1978-01-01
the self-similar solution of the gasdynamic equations of a strong cylindrical shock wave moving through an ideal gas, with γ = csub(p)/csub(v), is considered. These equations are greatly simplified following the transformation of the reduced velocity U 1 (xi) → U 1 = 1/2(γ + 1 ) (U + xi). The requirement of a single maximum pressure, dsub(xi)P = 0, leads to an analytical determination of the self-similarity exponent α(γ). For gases with γ = 2 + 3sup(1/2), this maximum ensues right at the shock front and the pressure distribution then decreases monotonically. The postulate of analyticity by Gelfand and Butler is shown to concur with the requirement dsub(xi)P 0. The saturated density of the gas left in the wake of the shock is computed and - U is shown to be the reduced velocity of sound at P = P sub(m). (author)
Reliability Analysis of Dynamic Stability in Waves
DEFF Research Database (Denmark)
Søborg, Anders Veldt
2004-01-01
exhibit sufficient characteristics with respect to slope at zero heel (GM value), maximum leverarm, positive range of stability and area below the leverarm curve. The rule-based requirements to calm water leverarm curves are entirely based on experience obtained from vessels in operation and recorded......The assessment of a ship's intact stability is traditionally based on a semi-empirical deterministic concept that evaluates the characteristics of ship's calm water restoring leverarm curves. Today the ship is considered safe with respect to dynamic stability if its calm water leverarm curves...... accidents in the past. The rules therefore only leaves little room for evaluation and improvement of safety of a ship's dynamic stability. A few studies have evaluated the probability of ship stability loss in waves using Monte Carlo simulations. However, since this probability may be in the order of 10...
International Nuclear Information System (INIS)
Yan Zhizhong; Zhang Chuanzeng; Wang Yuesheng
2011-01-01
The band structures of in-plane elastic waves propagating in two-dimensional phononic crystals with one-dimensional random disorder and aperiodicity are analyzed in this paper. The localization of wave propagation is discussed by introducing the concept of the localization factor, which is calculated by the plane-wave-based transfer-matrix method. By treating the random disorder and aperiodicity as the deviation from the periodicity in a special way, three kinds of aperiodic phononic crystals that have normally distributed random disorder, Thue-Morse and Rudin-Shapiro sequence in one direction and translational symmetry in the other direction are considered and the band structures are characterized using localization factors. Besides, as a special case, we analyze the band gap properties of a periodic planar layered composite containing a periodic array of square inclusions. The transmission coefficients based on eigen-mode matching theory are also calculated and the results show the same behaviors as the localization factor does. In the case of random disorders, the localization degree of the normally distributed random disorder is larger than that of the uniformly distributed random disorder although the eigenstates are both localized no matter what types of random disorders, whereas, for the case of Thue-Morse and Rudin-Shapiro structures, the band structures of Thue-Morse sequence exhibit similarities with the quasi-periodic (Fibonacci) sequence not present in the results of the Rudin-Shapiro sequence.
Spectral analysis of surface waves method to assess shear wave velocity within centrifuge models
Murillo, Carol Andrea; Thorel, Luc; Caicedo, Bernardo
2009-06-01
The method of the spectral analysis of surface waves (SASW) is tested out on reduced scale centrifuge models, with a specific device, called the mini Falling Weight, developed for this purpose. Tests are performed on layered materials made of a mixture of sand and clay. The shear wave velocity VS determined within the models using the SASW is compared with the laboratory measurements carried out using the bender element test. The results show that the SASW technique applied to centrifuge testing is a relevant method to characterize VS near the surface.
Low-lying S-wave and P-wave dibaryons in a nodal structure analysis
International Nuclear Information System (INIS)
Liu Yuxin; Li Jingsheng; Bao Chengguang
2003-01-01
The inherent nodal surface structure analysis approach is proposed for six-quark clusters with u, d, and s quarks. The wave functions of the six-quark clusters are classified, and the contribution of the hidden-color channels are discussed. The quantum numbers and configurations of the wave functions of the low-lying dibaryons are obtained. The states [ΩΩ] (0,0 + ) , [ΩΩ] (0,2 - ) , [Ξ * Ω] (1/2,0 + ) , and [Σ * Σ * ] (0,4 - ) and the hidden-color channel states with the same quantum numbers are proposed to be the candidates of experimentally observable dibaryons
Analysis and optimization of Love wave liquid sensors.
Jakoby, B; Vellekoop, M J
1998-01-01
Love wave sensors are highly sensitive microacoustic devices, which are well suited for liquid sensing applications thanks to the shear polarization of the wave. The sensing mechanism thereby relies on the mechanical (or acoustic) interaction of the device with the liquid. The successful utilization of Love wave devices for this purpose requires proper shielding to avoid unwanted electric interaction of the liquid with the wave and the transducers. In this work we describe the effects of this electric interaction and the proper design of a shield to prevent it. We present analysis methods, which illustrate the impact of the interaction and which help to obtain an optimized design of the proposed shield. We also present experimental results for devices that have been fabricated according to these design rules.
International Nuclear Information System (INIS)
Boaga, J; Vignoli, G; Cassiani, G
2011-01-01
Inversion is a critical step in all geophysical techniques, and is generally fraught with ill-posedness. In the case of seismic surface wave studies, the inverse problem can lead to different equivalent subsoil models and consequently to different local seismic response analyses. This can have a large impact on an earthquake engineering design. In this paper, we discuss the consequences of non-uniqueness of surface wave inversion on seismic responses, with both numerical and experimental data. Our goal is to evaluate the consequences on common seismic response analysis in the case of different impedance contrast conditions. We verify the implications of inversion uncertainty, and consequently of data information content, on realistic local site responses. A stochastic process is used to generate a set of 1D shear wave velocity profiles from several specific subsurface models. All these profiles are characterized as being equivalent, i.e. their responses, in terms of a dispersion curve, are compatible with the uncertainty in the same surface wave data. The generated 1D shear velocity models are then subjected to a conventional one-dimensional seismic ground response analysis using a realistic input motion. While recent analyses claim that the consequences of surface wave inversion uncertainties are very limited, our test points out that a relationship exists between inversion confidence and seismic responses in different subsoils. In the case of regular and relatively smooth increase of shear wave velocities with depth, as is usual in sedimentary plains, our results show that the choice of a specific model among equivalent solutions strongly influences the seismic response. On the other hand, when the shallow subsoil is characterized by a strong impedance contrast (thus revealing a characteristic soil resonance period), as is common in the presence of a shallow bedrock, equivalent solutions provide practically the same seismic amplification, especially in the
P-wave and surface wave survey for permafrost analysis in alpine regions
Godio, A.; Socco, L. V.; Garofalo, F.; Arato, A.; Théodule, A.
2012-04-01
In various high mountain environments the estimate of mechanical properties of slope and sediments are relevant for the link of the geo-mechanical properties with the climate change effects. Two different locations were selected to perform seismic and georadar surveying, the Tsanteleina glacier (Gran Paradiso) and the Blue Lake in Val d'Ayas in the massif of Monterosa. The analysis of the seismic and GPR lines allowed to characterize the silty soil (top layer) and underlying bedrock. We applied seismic survey in time lapse mode to check the presence of "active" layer and estimate the mechanical properties of the moraines material and their sensitivity to the permafrost changes. Mechanical properties of sediments and moraines in glacial areas are related to the grain-size, the compaction of the material subjected to the past glacial activity, the presence of frozen materials and the reactivity of the permafrost to the climate changes. The test site of Tsanteleina has been equipped with sensors to monitor the temperature of soil and air and with time domain reflectometry to estimate the soil moisture and the frozen and thawing cycle of the uppermost material. Seismic reflections from the top of the permafrost layer are difficult to identify as they are embedded in the source-generated noise. Therefore we estimate seismic velocities from the analysis of traveltime refraction tomography and the analysis of surface wave. This approach provides information on compressional and shear waves using a single acquisition layout and a hammer acts as source. This reduces the acquisition time in complex logistical condition especially in winter period. The seismic survey was performed using 48 vertical geophones with 2 m spacing. The survey has been repeated in two different periods: summer 2011 and winter 2011. Common offset reflection lines with a 200 MHz GPR system (in summer) permitted to investigate the sediments and obtain information on the subsoil layering. The processing
Directory of Open Access Journals (Sweden)
Huan-Feng Duan
2017-10-01
Full Text Available This paper investigates the impacts of non-uniformities of pipe diameter (i.e., an inhomogeneous cross-sectional area along pipelines on transient wave behavior and propagation in water supply pipelines. The multi-scale wave perturbation method is firstly used to derive analytical solutions for the amplitude evolution of transient pressure wave propagation in pipelines, considering regular and random variations of cross-sectional area, respectively. The analytical analysis is based on the one-dimensional (1D transient wave equation for pipe flow. Both derived results show that transient waves can be attenuated and scattered significantly along the longitudinal direction of the pipeline due to the regular and random non-uniformities of pipe diameter. The obtained analytical results are then validated by extensive 1D numerical simulations under different incident wave and non-uniform pipe conditions. The comparative results indicate that the derived analytical solutions are applicable and useful to describe the wave scattering effect in complex pipeline systems. Finally, the practical implications and influence of wave scattering effects on transient flow analysis and transient-based leak detection in urban water supply systems are discussed in the paper.
Analysis of unbounded operators and random motion
International Nuclear Information System (INIS)
Jorgensen, Palle E. T.
2009-01-01
We study infinite weighted graphs with view to 'limits at infinity' or boundaries at infinity. Examples of such weighted graphs arise in infinite (in practice, that means 'very' large) networks of resistors or in statistical mechanics models for classical or quantum systems. However, more generally, our analysis includes reproducing kernel Hilbert spaces and associated operators on them. If X is some infinite set of vertices or nodes, in applications the essential ingredient going into the definition is a reproducing kernel Hilbert space; it measures the differences of functions on X evaluated on pairs of points in X. Moreover, the Hilbert norm-squared in H(X) will represent a suitable measure of energy. Associated unbounded operators will define a notion or dissipation, it can be a graph Laplacian or a more abstract unbounded Hermitian operator defined from the reproducing kernel Hilbert space under study. We prove that there are two closed subspaces in reproducing kernel Hilbert space H(X) that measure quantitative notions of limits at infinity in X: one generalizes finite-energy harmonic functions in H(X) and the other a deficiency index of a natural operator in H(X) associated directly with the diffusion. We establish these results in the abstract, and we offer examples and applications. Our results are related to, but different from, potential theoretic notions of 'boundaries' in more standard random walk models. Comparisons are made.
Sensitivity analysis of P-waves and S-waves to gas hydrate in the Shenhu area using OBS
Xing, Lei; Liu, Xueqin; Zhang, Jin; Liu, Huaishan; Zhang, Jing; Li, Zizheng; Wang, Jianhua
2018-02-01
Compared to towed streamers, ocean-bottom seismometers (OBS) obtain both S-wave data and richer wavefield information. In this paper, the induced polarization method is used to conduct wavefield separation on OBS data obtained from the Shenhu area in the South China Sea. A comparison of the changes in P- and S-waves, and a comprehensive analysis of geological factors within the area, enable analysis and description of the occurrence of natural gas hydrate in the study area. Results show an increase in P-wave velocity when natural gas hydrate exists in the formation, whereas the S-wave velocity remains almost constant, as S-waves can only propagate through the rock skeleton. Therefore, the bottom-simulating reflection (BSR) response of the P-wave is better than that of the S-wave in the frequency analysis profile. In a wide-angle section, the refractive wave of the hydrate layer is evident when using P-wave components but identification is difficult with S-wave components. This velocity model illustrates the sensitivity of P- and S-wave components to gas hydrate. The use of this polarization method and results of analysis provide technical and theoretical support for research on hydrate deposits and other geological features in the Shenhu area.
Emoto, K.; Saito, T.; Shiomi, K.
2017-12-01
Short-period (2 s) seismograms. We found that the energy of the coda of long-period seismograms shows a spatially flat distribution. This phenomenon is well known in short-period seismograms and results from the scattering by small-scale heterogeneities. We estimate the statistical parameters that characterize the small-scale random heterogeneity by modelling the spatiotemporal energy distribution of long-period seismograms. We analyse three moderate-size earthquakes that occurred in southwest Japan. We calculate the spatial distribution of the energy density recorded by a dense seismograph network in Japan at the period bands of 8-16 s, 4-8 s and 2-4 s and model them by using 3-D finite difference (FD) simulations. Compared to conventional methods based on statistical theories, we can calculate more realistic synthetics by using the FD simulation. It is not necessary to assume a uniform background velocity, body or surface waves and scattering properties considered in general scattering theories. By taking the ratio of the energy of the coda area to that of the entire area, we can separately estimate the scattering and the intrinsic absorption effects. Our result reveals the spectrum of the random inhomogeneity in a wide wavenumber range including the intensity around the corner wavenumber as P(m) = 8πε2a3/(1 + a2m2)2, where ε = 0.05 and a = 3.1 km, even though past studies analysing higher-frequency records could not detect the corner. Finally, we estimate the intrinsic attenuation by modelling the decay rate of the energy. The method proposed in this study is suitable for quantifying the statistical properties of long-wavelength subsurface random inhomogeneity, which leads the way to characterizing a wider wavenumber range of spectra, including the corner wavenumber.
A. Arunjith; S.A. Sannasiraj; V. Sundar
2013-01-01
The design of rubble mound structures like breakwaters and seawalls are influenced by the wave run-up and overtopping over them. The above phenomena largely depend on the type of the armour units as they directly interact with the incident waves. The hydrodynamic characteristics of various concrete armour units have been established by several researchers. A new armour block, ‘Kolos’, a modified version of Dolos, is considered in this study for a detailed investigation. An attempt is made to ...
Montiel, F.; Squire, V. A.
2013-12-01
A new ocean wave/sea-ice interaction model is proposed that simulates how a directional wave spectrum evolves as it travels through a realistic marginal ice zone (MIZ), where wave/ice dynamics are entirely governed by coherent conservative wave scattering effects. Field experiments conducted by Wadhams et al. (1986) in the Greenland Sea generated important data on wave attenuation in the MIZ and, particularly, on whether the wave spectrum spreads directionally or collimates with distance from the ice edge. The data suggest that angular isotropy, arising from multiple scattering by ice floes, occurs close to the edge and thenceforth dominates wave propagation throughout the MIZ. Although several attempts have been made to replicate this finding theoretically, including by the use of numerical models, none have confronted this problem in a 3D MIZ with fully randomised floe distribution properties. We construct such a model by subdividing the discontinuous ice cover into adjacent infinite slabs of finite width parallel to the ice edge. Each slab contains an arbitrary (but finite) number of circular ice floes with randomly distributed properties. Ice floes are modeled as thin elastic plates with uniform thickness and finite draught. We consider a directional wave spectrum with harmonic time dependence incident on the MIZ from the open ocean, defined as a continuous superposition of plane waves traveling at different angles. The scattering problem within each slab is then solved using Graf's interaction theory for an arbitrary incident directional plane wave spectrum. Using an appropriate integral representation of the Hankel function of the first kind (see Cincotti et al., 1993), we map the outgoing circular wave field from each floe on the slab boundaries into a directional spectrum of plane waves, which characterizes the slab reflected and transmitted fields. Discretizing the angular spectrum, we can obtain a scattering matrix for each slab. Standard recursive
P.W. Plaisier; M.Y. Berger (Marjolein); R.L. van der Hul (René); H.G. Nijs (Huub); R. den Toom (Rene); O.T. Terpstra (Onno); H.A. Bruining (Hajo); S.M. Strasberg (S.)
1994-01-01
textabstractShortly after extracorporeal shock wave lithotripsy (ESWL) was introduced as a promising new treatment modality for gallstone disease, a randomized controlled study was performed to assess the cost-effectiveness of ESWL compared to open cholecystectomy, the gold standard. During the
Effect of H-wave polarization on laser radar detection of partially convex targets in random media.
El-Ocla, Hosam
2010-07-01
A study on the performance of laser radar cross section (LRCS) of conducting targets with large sizes is investigated numerically in free space and random media. The LRCS is calculated using a boundary value method with beam wave incidence and H-wave polarization. Considered are those elements that contribute to the LRCS problem including random medium strength, target configuration, and beam width. The effect of the creeping waves, stimulated by H-polarization, on the LRCS behavior is manifested. Targets taking large sizes of up to five wavelengths are sufficiently larger than the beam width and are sufficient for considering fairly complex targets. Scatterers are assumed to have analytical partially convex contours with inflection points.
Gravitational wave detection and data analysis for pulsar timing arrays
Haasteren, Rutger van
2011-01-01
Long-term precise timing of Galactic millisecond pulsars holds great promise for measuring long-period (months-to-years) astrophysical gravitational waves. In this work we develop a Bayesian data analysis method for projects called pulsar timing arrays; projects aimed to detect these gravitational
SLAC three-body partial wave analysis system
International Nuclear Information System (INIS)
Aston, D.; Lasinski, T.A.; Sinervo, P.K.
1985-10-01
We present a heuristic description of the SLAC-LBL three-meson partial wave model, and describe how we have implemented it at SLAC. The discussion details the assumptions of the model and the analysis, and emphasizes the methods we have used to prepare and fit the data. 28 refs., 12 figs., 1 tab
Data synthesis and display programs for wave distribution function analysis
Storey, L. R. O.; Yeh, K. J.
1992-01-01
At the National Space Science Data Center (NSSDC) software was written to synthesize and display artificial data for use in developing the methodology of wave distribution analysis. The software comprises two separate interactive programs, one for data synthesis and the other for data display.
Analysis of Different Methods for Wave Generation and Absorption in a CFD-Based Numerical Wave Tank
Directory of Open Access Journals (Sweden)
Adria Moreno Miquel
2018-06-01
Full Text Available In this paper, the performance of different wave generation and absorption methods in computational fluid dynamics (CFD-based numerical wave tanks (NWTs is analyzed. The open-source CFD code REEF3D is used, which solves the Reynolds-averaged Navier–Stokes (RANS equations to simulate two-phase flow problems. The water surface is computed with the level set method (LSM, and turbulence is modeled with the k-ω model. The NWT includes different methods to generate and absorb waves: the relaxation method, the Dirichlet-type method and active wave absorption. A sensitivity analysis has been conducted in order to quantify and compare the differences in terms of absorption quality between these methods. A reflection analysis based on an arbitrary number of wave gauges has been adopted to conduct the study. Tests include reflection analysis of linear, second- and fifth-order Stokes waves, solitary waves, cnoidal waves and irregular waves generated in an NWT. Wave breaking over a sloping bed and wave forces on a vertical cylinder are calculated, and the influence of the reflections on the wave breaking location and the wave forces on the cylinder is investigated. In addition, a comparison with another open-source CFD code, OpenFOAM, has been carried out based on published results. Some differences in the calculated quantities depending on the wave generation and absorption method have been observed. The active wave absorption method is seen to be more efficient for long waves, whereas the relaxation method performs better for shorter waves. The relaxation method-based numerical beach generally results in lower reflected waves in the wave tank for most of the cases simulated in this study. The comparably better performance of the relaxation method comes at the cost of larger computational requirements due to the relaxation zones that have to be included in the domain. The reflections in the NWT in REEF3D are generally lower than the published results for
Energy Technology Data Exchange (ETDEWEB)
Berginc, G [THALES, 2 avenue Gay-Lussac 78995 ELANCOURT (France)
2013-11-30
We have developed a general formalism based on Green's functions to calculate the coherent electromagnetic field scattered by a random medium with rough boundaries. The approximate expression derived makes it possible to determine the effective permittivity, which is generalised for a layer of an inhomogeneous random medium with different types of particles and bounded with randomly rough interfaces. This effective permittivity describes the coherent propagation of an electromagnetic wave in a random medium with randomly rough boundaries. We have obtained an expression, which contains the Maxwell – Garnett formula at the low-frequency limit, and the Keller formula; the latter has been proved to be in good agreement with experiments for particles whose dimensions are larger than a wavelength. (coherent light scattering)
Guided Wave Delamination Detection and Quantification With Wavefield Data Analysis
Tian, Zhenhua; Campbell Leckey, Cara A.; Seebo, Jeffrey P.; Yu, Lingyu
2014-01-01
Unexpected damage can occur in aerospace composites due to impact events or material stress during off-nominal loading events. In particular, laminated composites are susceptible to delamination damage due to weak transverse tensile and inter-laminar shear strengths. Developments of reliable and quantitative techniques to detect delamination damage in laminated composites are imperative for safe and functional optimally-designed next-generation composite structures. In this paper, we investigate guided wave interactions with delamination damage and develop quantification algorithms by using wavefield data analysis. The trapped guided waves in the delamination region are observed from the wavefield data and further quantitatively interpreted by using different wavenumber analysis methods. The frequency-wavenumber representation of the wavefield shows that new wavenumbers are present and correlate to trapped waves in the damage region. These new wavenumbers are used to detect and quantify the delamination damage through the wavenumber analysis, which can show how the wavenumber changes as a function of wave propagation distance. The location and spatial duration of the new wavenumbers can be identified, providing a useful means not only for detecting the presence of delamination damage but also allowing for estimation of the delamination size. Our method has been applied to detect and quantify real delamination damage with complex geometry (grown using a quasi-static indentation technique). The detection and quantification results show the location, size, and shape of the delamination damage.
A phase-plane analysis of localized frictional waves
Putelat, T.; Dawes, J. H. P.; Champneys, A. R.
2017-07-01
Sliding frictional interfaces at a range of length scales are observed to generate travelling waves; these are considered relevant, for example, to both earthquake ground surface movements and the performance of mechanical brakes and dampers. We propose an explanation of the origins of these waves through the study of an idealized mechanical model: a thin elastic plate subject to uniform shear stress held in frictional contact with a rigid flat surface. We construct a nonlinear wave equation for the deformation of the plate, and couple it to a spinodal rate-and-state friction law which leads to a mathematically well-posed problem that is capable of capturing many effects not accessible in a Coulomb friction model. Our model sustains a rich variety of solutions, including periodic stick-slip wave trains, isolated slip and stick pulses, and detachment and attachment fronts. Analytical and numerical bifurcation analysis is used to show how these states are organized in a two-parameter state diagram. We discuss briefly the possible physical interpretation of each of these states, and remark also that our spinodal friction law, though more complicated than other classical rate-and-state laws, is required in order to capture the full richness of wave types.
Directory of Open Access Journals (Sweden)
O. W. Roberts
2014-12-01
Full Text Available Recent observations of astrophysical magnetic fields have shown the presence of fluctuations being wave-like (propagating in the plasma frame and those described as being structure-like (advected by the plasma bulk velocity. Typically with single-spacecraft missions it is impossible to differentiate between these two fluctuations, due to the inherent spatio-temporal ambiguity associated with a single point measurement. However missions such as Cluster which contain multiple spacecraft have allowed for temporal and spatial changes to be resolved, using techniques such as k filtering. While this technique does not assume Taylor's hypothesis it requires both weak stationarity of the time series and that the fluctuations can be described by a superposition of plane waves with random phases. In this paper we test whether the method can cope with a synthetic signal which is composed of a combination of non-random-phase coherent structures with a mean radius d and a mean separation λ, as well as plane waves with random phase.
The next wave in metabolome analysis
DEFF Research Database (Denmark)
Nielsen, Jens; Oliver, S.
2005-01-01
The metabolome of a cell represents the amplification and integration of signals from other functional genomic levels, such as the transcriptome and the proteome. Although this makes metabolomics a useful tool for the high-throughput analysis of phenotypes, the lack of a direct connection...... to the genome makes it difficult to interpret metabolomic data. Nevertheless, functional genomics has produced examples of the use of metabolomics to elucidate the phenotypes of otherwise silent mutations. Despite several successes, we believe that future metabolomic studies must focus on the accurate...... measurement of the concentrations of unambiguously identified metabolites. The research community must develop databases of metabolite concentrations in cells that are grown in several well-defined conditions if metabolomic data are to be integrated meaningfully with data from the other levels of functional...
Surface detection performance evaluation of pseudo-random noise continuous wave laser radar
Mitev, Valentin; Matthey, Renaud; Pereira do Carmo, Joao
2017-11-01
A number of space missions (including in the ESA Exploration Programme) foreseen a use of laser radar sensor (or lidar) for determination of range between spacecrafts or between spacecraft and ground surface (altimetry). Such sensors need to be compact, robust and power efficient, at the same time with high detection performance. These requirements can be achieved with a Pseudo-Random Noise continuous wave lidar (PRN cw lidar). Previous studies have pointed to the advantages of this lidar with respect to space missions, but they also identified its limitations in high optical background. The progress of the lasers and the detectors in the near IR spectral range requires a re-evaluation of the PRN cw lidar potential. Here we address the performances of this lidar for surface detection (altimetry) in planetary missions. The evaluation is based on the following system configuration: (i) A cw fiber amplifier as lidar transmitter. The seeding laser exhibits a single-frequency spectral line, with subsequent amplitude modulation. The fiber amplifier allows high output power level, keeping the spectral characteristics and the modulation of the seeding light input. (ii) An avalanche photodiode in photon counting detection; (iii) Measurement scenarios representative for Earth, Mercury and Mars.
Directory of Open Access Journals (Sweden)
You-Wei Zhang
Full Text Available A general symplectic method for the random response analysis of infinitely periodic structures subjected to stationary/non-stationary random excitations is developed using symplectic mathematics in conjunction with variable separation and the pseudo-excitation method (PEM. Starting from the equation of motion for a single loaded substructure, symplectic analysis is firstly used to eliminate the dependent degrees of the freedom through condensation. A Fourier expansion of the condensed equation of motion is then applied to separate the variables of time and wave number, thus enabling the necessary recurrence scheme to be developed. The random response is finally determined by implementing PEM. The proposed method is justified by comparison with results available in the literature and is then applied to a more complicated time-dependent coupled system.
Data analysis algorithms for gravitational-wave experiments
International Nuclear Information System (INIS)
Bonifazi, P.; Ferrari, V.; Frasca, S.; Pallottino, G.V.; Pizzella, G.
1978-01-01
The analysis of the sensitivity of a gravitational-wave antenna system shows that the role of the algorithms used for the analysis of the experimental data is comparable to that of the experimental apparatus. After a discussion of the processing performed on the input signals by the antenna and the electronic instrumentation, we derive a mathematical model of the system. This model is then used as a basis for the discussion of a number of data analysis algorithms that include also the Wiener-Kolmogoroff optimum filter; the performances of the algorithms are presented in terms of signal-to-noise ratio and sensitivity to short bursts of resonant gravitational waves. The theoretical results are in good agreement with the experimental results obtained with a small cryogenic antenna (24 kg)
Random matrix analysis of human EEG data
Czech Academy of Sciences Publication Activity Database
Šeba, Petr
2003-01-01
Roč. 91, - (2003), s. 198104-1 - 198104-4 ISSN 0031-9007 R&D Projects: GA ČR GA202/02/0088 Institutional research plan: CEZ:AV0Z1010914 Keywords : random matrix theory * EEG signal Subject RIV: BE - Theoretical Physics Impact factor: 7.035, year: 2003
Simulation and Analysis of Converging Shock Wave Test Problems
Energy Technology Data Exchange (ETDEWEB)
Ramsey, Scott D. [Los Alamos National Laboratory; Shashkov, Mikhail J. [Los Alamos National Laboratory
2012-06-21
Results and analysis pertaining to the simulation of the Guderley converging shock wave test problem (and associated code verification hydrodynamics test problems involving converging shock waves) in the LANL ASC radiation-hydrodynamics code xRAGE are presented. One-dimensional (1D) spherical and two-dimensional (2D) axi-symmetric geometric setups are utilized and evaluated in this study, as is an instantiation of the xRAGE adaptive mesh refinement capability. For the 2D simulations, a 'Surrogate Guderley' test problem is developed and used to obviate subtleties inherent to the true Guderley solution's initialization on a square grid, while still maintaining a high degree of fidelity to the original problem, and minimally straining the general credibility of associated analysis and conclusions.
Statistical analysis of random duration times
International Nuclear Information System (INIS)
Engelhardt, M.E.
1996-04-01
This report presents basic statistical methods for analyzing data obtained by observing random time durations. It gives nonparametric estimates of the cumulative distribution function, reliability function and cumulative hazard function. These results can be applied with either complete or censored data. Several models which are commonly used with time data are discussed, and methods for model checking and goodness-of-fit tests are discussed. Maximum likelihood estimates and confidence limits are given for the various models considered. Some results for situations where repeated durations such as repairable systems are also discussed
Directory of Open Access Journals (Sweden)
Jackson W. Cryns
2013-01-01
Full Text Available Harvesting power with a piezoelectric vibration powered generator using a full-wave rectifier conditioning circuit is experimentally compared for varying sinusoidal, random, and sine on random (SOR input vibration scenarios; the implications of source vibration characteristics on harvester design are discussed. The rise in popularity of harvesting energy from ambient vibrations has made compact, energy dense piezoelectric generators commercially available. Much of the available literature focuses on maximizing harvested power through nonlinear processing circuits that require accurate knowledge of generator internal mechanical and electrical characteristics and idealization of the input vibration source, which cannot be assumed in general application. Variations in source vibration and load resistance are explored for a commercially available piezoelectric generator. The results agree with numerical and theoretical predictions in the previous literature for optimal power harvesting in sinusoidal and flat broadband vibration scenarios. Going beyond idealized steady-state sinusoidal and flat random vibration input, experimental SOR testing allows for more accurate representation of real world ambient vibration. It is shown that characteristic interactions from more complex vibration sources significantly alter power generation and processing requirements by varying harvested power, shifting optimal conditioning impedance, inducing voltage fluctuations, and ultimately rendering idealized sinusoidal and random analyses incorrect.
DEFF Research Database (Denmark)
Ibsen, Lars Bo
2008-01-01
Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....
Quantitative subsurface analysis using frequency modulated thermal wave imaging
Subhani, S. K.; Suresh, B.; Ghali, V. S.
2018-01-01
Quantitative depth analysis of the anomaly with an enhanced depth resolution is a challenging task towards the estimation of depth of the subsurface anomaly using thermography. Frequency modulated thermal wave imaging introduced earlier provides a complete depth scanning of the object by stimulating it with a suitable band of frequencies and further analyzing the subsequent thermal response using a suitable post processing approach to resolve subsurface details. But conventional Fourier transform based methods used for post processing unscramble the frequencies with a limited frequency resolution and contribute for a finite depth resolution. Spectral zooming provided by chirp z transform facilitates enhanced frequency resolution which can further improves the depth resolution to axially explore finest subsurface features. Quantitative depth analysis with this augmented depth resolution is proposed to provide a closest estimate to the actual depth of subsurface anomaly. This manuscript experimentally validates this enhanced depth resolution using non stationary thermal wave imaging and offers an ever first and unique solution for quantitative depth estimation in frequency modulated thermal wave imaging.
International Nuclear Information System (INIS)
Ovchinnikov, O. S.; Jesse, S.; Kalinin, S. V.; Bintacchit, P.; Trolier-McKinstry, S.
2009-01-01
An approach for the direct identification of disorder type and strength in physical systems based on recognition analysis of hysteresis loop shape is developed. A large number of theoretical examples uniformly distributed in the parameter space of the system is generated and is decorrelated using principal component analysis (PCA). The PCA components are used to train a feed-forward neural network using the model parameters as targets. The trained network is used to analyze hysteresis loops for the investigated system. The approach is demonstrated using a 2D random-bond-random-field Ising model, and polarization switching in polycrystalline ferroelectric capacitors.
An Analysis of Fundamental Mode Surface Wave Amplitude Measurements
Schardong, L.; Ferreira, A. M.; van Heijst, H. J.; Ritsema, J.
2014-12-01
Seismic tomography is a powerful tool to decipher the Earth's interior structure at various scales. Traveltimes of seismic waves are widely used to build velocity models, whereas amplitudes are still only seldomly accounted for. This mainly results from our limited ability to separate the various physical effects responsible for observed amplitude variations, such as focussing/defocussing, scattering and source effects. We present new measurements from 50 global earthquakes of fundamental-mode Rayleigh and Love wave amplitude anomalies measured in the period range 35-275 seconds using two different schemes: (i) a standard time-domain amplitude power ratio technique; and (ii) a mode-branch stripping scheme. For minor-arc data, we observe amplitude anomalies with respect to PREM in the range of 0-4, for which the two measurement techniques show a very good overall agreement. We present here a statistical analysis and comparison of these datasets, as well as comparisons with theoretical calculations for a variety of 3-D Earth models. We assess the geographical coherency of the measurements, and investigate the impact of source, path and receiver effects on surface wave amplitudes, as well as their variations with frequency in a wider range than previously studied.
Global analysis of ICRF wave coupling on Tore Supra
International Nuclear Information System (INIS)
Goniche, M.; Bremond, S.; Colas, L.
2003-01-01
The Tore Supra tokamak is equipped with a multi-megawatt ion cyclotron range of frequency (ICRF) system for heating and current drive. The coupling of the fast wave to the plasma, characterized by the distributed coupling resistance along the radiating straps, is a crucial issue in order to launch large RF powers. Many factors can have an effect on ICRF wave coupling. Quantitative prediction from theoretical modelling requires the knowledge of the local inhomogeneous plasma density profile in front of the antenna for running sophisticated antenna codes. In this work, we have rather followed a 'global' approach, based on Tore Supra experimental results, for the parametric study of the coupling resistance. From a large data base covering seven experimental campaigns (∼2250 shots), a scaling law of the coupling resistance including the main parameters of the plasma and of the antenna configuration is established. This approach is found to be reliable for the analysis of coupling in the different scenarios: He/D 2 gas filling, gas/pellets for plasma fuelling, plasma leaning on inner wall/low field side limiter, limiter/ergodic divertor configuration, minority heating/direct electron heating. From one scenario to another, a significant variation of the coefficients of the scaling law is found. The study of these variations allows to get some insight on the main physical mechanisms which influence the ICRF wave coupling in a tokamak operation, such as the wall conditioning and recycling conditions, RF sheaths or frequency. (author)
Multi-channel Analysis of Passive Surface Waves (MAPS)
Xia, J.; Cheng, F. Mr; Xu, Z.; Wang, L.; Shen, C.; Liu, R.; Pan, Y.; Mi, B.; Hu, Y.
2017-12-01
Urbanization is an inevitable trend in modernization of human society. In the end of 2013 the Chinese Central Government launched a national urbanization plan—"Three 100 Million People", which aggressively and steadily pushes forward urbanization. Based on the plan, by 2020, approximately 100 million people from rural areas will permanently settle in towns, dwelling conditions of about 100 million people in towns and villages will be improved, and about 100 million people in the central and western China will permanently settle in towns. China's urbanization process will run at the highest speed in the urbanization history of China. Environmentally friendly, non-destructive and non-invasive geophysical assessment method has played an important role in the urbanization process in China. Because human noise and electromagnetic field due to industrial life, geophysical methods already used in urban environments (gravity, magnetics, electricity, seismic) face great challenges. But humanity activity provides an effective source of passive seismic methods. Claerbout pointed out that wavefileds that are received at one point with excitation at the other point can be reconstructed by calculating the cross-correlation of noise records at two surface points. Based on this idea (cross-correlation of two noise records) and the virtual source method, we proposed Multi-channel Analysis of Passive Surface Waves (MAPS). MAPS mainly uses traffic noise recorded with a linear receiver array. Because Multi-channel Analysis of Surface Waves can produces a shear (S) wave velocity model with high resolution in shallow part of the model, MPAS combines acquisition and processing of active source and passive source data in a same flow, which does not require to distinguish them. MAPS is also of ability of real-time quality control of noise recording that is important for near-surface applications in urban environment. The numerical and real-world examples demonstrated that MAPS can be
On the Security of Millimeter Wave Vehicular Communication Systems Using Random Antenna Subsets
Eltayeb, Mohammed E.
2017-03-20
Millimeter wave (mmWave) vehicular communication systems have the potential to improve traffic efficiency and safety. Lack of secure communication links, however, may lead to a formidable set of abuses and attacks. To secure communication links, a physical layer precoding technique for mmWave vehicular communication systems is proposed in this paper. The proposed technique exploits the large dimensional antenna arrays available at mmWave systems to produce direction dependent transmission. This results in coherent transmission to the legitimate receiver and artificial noise that jams eavesdroppers with sensitive receivers. Theoretical and numerical results demonstrate the validity and effectiveness of the proposed technique and show that the proposed technique provides high secrecy throughput when compared to conventional array and switched array transmission techniques.
On the Security of Millimeter Wave Vehicular Communication Systems Using Random Antenna Subsets
Eltayeb, Mohammed E.; Choi, Junil; Al-Naffouri, Tareq Y.; Heath, Robert W.
2017-01-01
Millimeter wave (mmWave) vehicular communication systems have the potential to improve traffic efficiency and safety. Lack of secure communication links, however, may lead to a formidable set of abuses and attacks. To secure communication links, a physical layer precoding technique for mmWave vehicular communication systems is proposed in this paper. The proposed technique exploits the large dimensional antenna arrays available at mmWave systems to produce direction dependent transmission. This results in coherent transmission to the legitimate receiver and artificial noise that jams eavesdroppers with sensitive receivers. Theoretical and numerical results demonstrate the validity and effectiveness of the proposed technique and show that the proposed technique provides high secrecy throughput when compared to conventional array and switched array transmission techniques.
A random probabilistic approach to seismic nuclear power plant analysis
International Nuclear Information System (INIS)
Romo, M.P.
1985-01-01
A probabilistic method for the seismic analysis of structures which takes into account the random nature of earthquakes and of the soil parameter uncertainties is presented in this paper. The method was developed combining elements of the theory of perturbations, the Random vibration theory and the complex response method. The probabilistic method is evaluated by comparing the responses of a single degree of freedom system computed with this approach and the Monte Carlo method. (orig.)
Efficiency Analysis of a Wave Power Generation System by Using Multibody Dynamics
International Nuclear Information System (INIS)
Kim, Min Soo; Sohn, Jeong Hyun; Kim, Jung Hee; Sung, Yong Jun
2016-01-01
The energy absorption efficiency of a wave power generation system is calculated as the ratio of the wave power to the power of the system. Because absorption efficiency depends on the dynamic behavior of the wave power generation system, a dynamic analysis of the wave power generation system is required to estimate the energy absorption efficiency of the system. In this study, a dynamic analysis of the wave power generation system under wave loads is performed to estimate the energy absorption efficiency. RecurDyn is employed to carry out the dynamic analysis of the system, and the Morison equation is used for the wave load model. According to the results, the lower the wave height and the shorter the period, the higher is the absorption efficiency of the system
Efficiency Analysis of a Wave Power Generation System by Using Multibody Dynamics
Energy Technology Data Exchange (ETDEWEB)
Kim, Min Soo; Sohn, Jeong Hyun [Pukyong National Univ., Busan (Korea, Republic of); Kim, Jung Hee; Sung, Yong Jun [INGINE Inc., Seoul (Korea, Republic of)
2016-06-15
The energy absorption efficiency of a wave power generation system is calculated as the ratio of the wave power to the power of the system. Because absorption efficiency depends on the dynamic behavior of the wave power generation system, a dynamic analysis of the wave power generation system is required to estimate the energy absorption efficiency of the system. In this study, a dynamic analysis of the wave power generation system under wave loads is performed to estimate the energy absorption efficiency. RecurDyn is employed to carry out the dynamic analysis of the system, and the Morison equation is used for the wave load model. According to the results, the lower the wave height and the shorter the period, the higher is the absorption efficiency of the system.
A meta-analysis of third wave mindfulness-based cognitive behavioral therapies for older people.
Kishita, Naoko; Takei, Yuko; Stewart, Ian
2017-12-01
The aim of this study is to review the effectiveness of third wave mindfulness-based cognitive behavioral therapies (CBTs) for depressive or anxiety symptomatology in older adults across a wide range of physical and psychological conditions. Electronic literature databases were searched for articles, and random-effects meta-analysis was conducted. Ten studies met the inclusion criteria, of which nine reported the efficacy of interventions on depressive symptoms and seven on anxiety symptoms. Effect-size estimates suggested that mindfulness-based CBT is moderately effective on depressive symptoms in older adults (g = 0.55). The results demonstrated a similar level of overall effect size for anxiety symptoms (g = 0.58). However, there was a large heterogeneity, and publication bias was evident in studies reporting outcomes on anxiety symptoms, and thus, this observed efficacy for late-life anxiety may not be robust. The quality of the included studies varied. Only one study used an active psychological control condition. There were a limited number of studies that used an intent-to-treat (last observation carried forward method) analysis and reported appropriate methods for clinical trials (e.g., treatment-integrity reporting). Third wave mindfulness-based CBT may be robust in particular for depressive symptoms in older adults. We recommend that future studies (i) conduct randomized controlled trials with intent-to-treat to compare mindfulness-based CBT with other types of psychotherapy in older people and (ii) improve study quality by using appropriate methods for checking treatment adherence, randomization, and blinding of assessors. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
Use of the MULTINEST algorithm for gravitational wave data analysis
International Nuclear Information System (INIS)
Feroz, Farhan; Hobson, Michael P; Gair, Jonathan R; Porter, Edward K
2009-01-01
We describe an application of the MULTINEST algorithm to gravitational wave data analysis. MULTINEST is a multimodal nested sampling algorithm designed to efficiently evaluate the Bayesian evidence and return posterior probability densities for likelihood surfaces containing multiple secondary modes. The algorithm employs a set of 'live' points which are updated by partitioning the set into multiple overlapping ellipsoids and sampling uniformly from within them. This set of 'live' points climbs up the likelihood surface through nested iso-likelihood contours and the evidence and posterior distributions can be recovered from the point set evolution. The algorithm is model independent in the sense that the specific problem being tackled enters only through the likelihood computation, and does not change how the 'live' point set is updated. In this paper, we consider the use of the algorithm for gravitational wave data analysis by searching a simulated LISA data set containing two non-spinning supermassive black hole binary signals. The algorithm is able to rapidly identify all the modes of the solution and recover the true parameters of the sources to high precision.
Use of the MULTINEST algorithm for gravitational wave data analysis
Energy Technology Data Exchange (ETDEWEB)
Feroz, Farhan; Hobson, Michael P [Astrophysics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Gair, Jonathan R [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Porter, Edward K [APC, UMR 7164, Universite Paris 7 Denis Diderot, 10, rue Alice Domon et Leonie Duquet, 75205 Paris Cedex 13 (France)
2009-11-07
We describe an application of the MULTINEST algorithm to gravitational wave data analysis. MULTINEST is a multimodal nested sampling algorithm designed to efficiently evaluate the Bayesian evidence and return posterior probability densities for likelihood surfaces containing multiple secondary modes. The algorithm employs a set of 'live' points which are updated by partitioning the set into multiple overlapping ellipsoids and sampling uniformly from within them. This set of 'live' points climbs up the likelihood surface through nested iso-likelihood contours and the evidence and posterior distributions can be recovered from the point set evolution. The algorithm is model independent in the sense that the specific problem being tackled enters only through the likelihood computation, and does not change how the 'live' point set is updated. In this paper, we consider the use of the algorithm for gravitational wave data analysis by searching a simulated LISA data set containing two non-spinning supermassive black hole binary signals. The algorithm is able to rapidly identify all the modes of the solution and recover the true parameters of the sources to high precision.
Experimental analysis of shock wave effects in copper
International Nuclear Information System (INIS)
Llorca, Fabrice; Buy, Francois; Farre, Jose
2002-01-01
This paper proposes the analysis of shock wave effects for a high purity copper. The method developed is based on the analysis of the mechanical behavior of as received and shocked materials. Shock effect is generated through plates impact tests performed in the range 9 GPa to 12 GPa on a single stage light gas gun. Therefore, as-received and impacted materials are characterized on quasi static and Split Hopkinson apparatus. The difference between measured stresses between as received and shocked materials allows to understand shock effects in the low pressure range of study. A specific modeling approach is engaged in order to give indications about the evolution of the microstructure of the materials
International Nuclear Information System (INIS)
Adzhemyan, L.Ts.; Vasil'ev, A.N.; Pis'mak, Yu.M.
1988-01-01
The investigation of the infrared behavior of the propagator of a light wave in a randomly inhomogeneous medium with massless Gaussian noise is continued. The infrared representation of the propagator for correlation function D varphi (k)∼k -2 is generalized to the case of an arbitrary power-law noise correlation function is rigorously established in the first two orders of the infrared asymptotic behavior by construction of a suitable R operation. As a consequence, the results are generalized to the case of critical opalescence, when D varphi (k)∼k -2+η , where η ∼ 0.03 is the Fisher index
Quasi-static analysis of wave loadings on spine-based wave energy devices
Energy Technology Data Exchange (ETDEWEB)
Lockett, F.P.; Peatfield, A.M.; West, M.J.
1980-02-01
A report is given on the Wave Energy Research Programme at Lanchester Polytechnic. Results are presented for both theoretical and experimental scale models for wave loadings on circular and rectangular spines of various lengths. The results are in good agreement over the operational wave range for the 1/50 scale model and for the more limited data on the 1/10 scale model.
Analysis of waves in the plasma guided by a periodical vane-type slow wave structure
International Nuclear Information System (INIS)
Wu, T.J.; Kou, C.S.
2005-01-01
In this study, the dispersion relation has been derived to characterize the propagation of the waves in the plasma guided by a periodical vane-type slow wave structure. The plasma is confined by a quartz plate. Results indicate that there are two different waves in this structure. One is the plasma mode that originates from the plasma surface wave propagating along the interface between the plasma and the quartz plate, and the other is the guide mode that originally travels along the vane-type slow wave structure. In contrast to its original slow wave characteristics, the guide mode becomes a fast wave in the low-frequency portion of the passband, and there exists a cut-off frequency for the guide mode. The vane-type guiding structure has been shown to limit the upper frequency of the passband of the plasma mode, compared with that of the plasma surface wave. In addition, the passband of the plasma mode increases with the plasma density while it becomes narrower for the guide mode. The influences of the parameters of the guiding structure and plasma density on the propagation of waves are also presented
Wave energy budget analysis in the Earth's radiation belts uncovers a missing energy.
Artemyev, A V; Agapitov, O V; Mourenas, D; Krasnoselskikh, V V; Mozer, F S
2015-05-15
Whistler-mode emissions are important electromagnetic waves pervasive in the Earth's magnetosphere, where they continuously remove or energize electrons trapped by the geomagnetic field, controlling radiation hazards to satellites and astronauts and the upper-atmosphere ionization or chemical composition. Here, we report an analysis of 10-year Cluster data, statistically evaluating the full wave energy budget in the Earth's magnetosphere, revealing that a significant fraction of the energy corresponds to hitherto generally neglected very oblique waves. Such waves, with 10 times smaller magnetic power than parallel waves, typically have similar total energy. Moreover, they carry up to 80% of the wave energy involved in wave-particle resonant interactions. It implies that electron heating and precipitation into the atmosphere may have been significantly under/over-valued in past studies considering only conventional quasi-parallel waves. Very oblique waves may turn out to be a crucial agent of energy redistribution in the Earth's radiation belts, controlled by solar activity.
Dispersion analysis for waves propagated in fractured media
Energy Technology Data Exchange (ETDEWEB)
Lesniak, A; Niitsuma, H [Tohoku University, Sendai (Japan). Faculty of Engineering
1996-05-01
Dispersion of velocity is defined as a variation of the phase velocity with frequency. This paper describes the dispersion analysis of compressional body waves propagated in the heterogeneous fractured media. The new method proposed and discussed here permitted the evaluation of the variation in P wave arrival with frequency. For this processing method, any information about the attenuation of the medium are not required, and only an assumption of weak heterogeneity is important. It was shown that different mechanisms of dispersion can be distinguished and its value can be quantitatively estimated. Although the frequency used in this study was lower than those in most previous experiments reported in literature, the evaluated dispersion was large. It was suggested that such a large dispersion may be caused by the velocity structure of the media studied and by frequency dependent processes in a highly fractured zone. It was demonstrated that the present method can be used in the evaluation of subsurface fracture systems or characterization of any kind of heterogeneities. 10 refs., 6 figs.
Constraint likelihood analysis for a network of gravitational wave detectors
International Nuclear Information System (INIS)
Klimenko, S.; Rakhmanov, M.; Mitselmakher, G.; Mohanty, S.
2005-01-01
We propose a coherent method for detection and reconstruction of gravitational wave signals with a network of interferometric detectors. The method is derived by using the likelihood ratio functional for unknown signal waveforms. In the likelihood analysis, the global maximum of the likelihood ratio over the space of waveforms is used as the detection statistic. We identify a problem with this approach. In the case of an aligned pair of detectors, the detection statistic depends on the cross correlation between the detectors as expected, but this dependence disappears even for infinitesimally small misalignments. We solve the problem by applying constraints on the likelihood functional and obtain a new class of statistics. The resulting method can be applied to data from a network consisting of any number of detectors with arbitrary detector orientations. The method allows us reconstruction of the source coordinates and the waveforms of two polarization components of a gravitational wave. We study the performance of the method with numerical simulations and find the reconstruction of the source coordinates to be more accurate than in the standard likelihood method
IMPLODING IGNITION WAVES. I. ONE-DIMENSIONAL ANALYSIS
International Nuclear Information System (INIS)
Kushnir, Doron; Waxman, Eli; Livne, Eli
2012-01-01
We show that converging spherical and cylindrical shock waves may ignite a detonation wave in a combustible medium, provided the radius at which the shocks become strong exceeds a critical radius, R crit . An approximate analytic expression for R crit is derived for an ideal gas equation of state and a simple (power-law-Arrhenius) reaction law, and shown to reproduce the results of numerical solutions. For typical acetylene-air experiments we find R crit ∼ 100 μm (spherical) and R crit ∼ 1 mm (cylindrical). We suggest that the deflagration to detonation transition (DDT) observed in these systems may be due to converging shocks produced by the turbulent deflagration flow, which reaches sub- (but near) sonic velocities on scales >>R crit . Our suggested mechanism differs from that proposed by Zel'dovich et al., in which a fine-tuned spatial gradient in the chemical induction time is required to be maintained within the turbulent deflagration flow. Our analysis may be readily extended to more complicated equations of state and reaction laws. An order of magnitude estimate of R crit within a white dwarf at the pre-detonation conditions believed to lead to Type Ia supernova explosions is 0.1 km, suggesting that our proposed mechanism may be relevant for DDT initiation in these systems. The relevance of our proposed ignition mechanism to DDT initiation may be tested by both experiments and numerical simulations.
On the excited state wave functions of Dirac fermions in the random ...
Indian Academy of Sciences (India)
wave functions in FRGP can be written in terms of descendents of the Liouville vertex operator. In the ... that the localization length ξ scales with the energy E as ξ ∼ E−b2/(1+b2)2. , where b is .... Let us write the Hamiltonian of the. FRGP model ...
Lagrangian analysis of nonlinear wave-wave interactions in bounded plasmas
International Nuclear Information System (INIS)
Carr, A.R.
1979-01-01
In a weakly turbulent nonlinear wave-supporting medium, one of the important nonlinear processes which may occur is resonant three-wave interaction. Whitham's averaged Lagrangian method provides a general formulation of wave evolution laws which is easily adapted to nonlinear dispersive media. In this thesis, the strength of nonlinear interactions between three coherent, axisymmetric, low frequency, magnetohydrodynamic (Alfven) waves propagating in resonance along a cold cylindrical magnetized plasma column is calculated. Both a uniform and a parabolic density distribution have been considered. To account for a non-zero plasma temperature, pressure effects have been included. Distinctive features of the work are the use of cylindrical geometry, the presence of a finite rather than an infinite axial magnetic field, the treatment of a parabolic density distribution, and the inclusion of both ion and electron contributions in all expressions. Two astrophysical applications of the presented theory have been considered. In the first, the possibility of resonant three-wave coupling between geomagnetic micropulsations, which propagate as Alfven or magnetosonic waves along the Earth's magnetic field lines, has been investigated. The second case is the theory of energy transport through the solar chromosphere by upward propagating magnetohydrodynamic waves, which may then couple to heavily damped waves in the corona, causing the observed excess heating in that region
Including the influence of waves in the overall slope stability analysis of rubble mound breakwaters
Mollaert, J.; Tavallali, A.
2016-01-01
An offshore breakwater is designed for the construction of a LNG-terminal. For the slope stability analysis of the rubble mound breakwater the existing and the extreme wave climate are considered. Pore water pressure variations exist in the breakwater and its permeable foundation. A wave trough combined with the moment of maximum wave run-up results in a decrease and increase of the pore water pressure, respectively. Therefore, the wave actions have on overall effect on the slope stability of...
Analysis of multidimensional measurements of electromagnetic waves in the Earth's magnetosphere
Pechal, Radim
2011-01-01
Title: Analysis of multidimensional measurements of electromagnetic waves in the Earth's magnetosphere Author: Radim Pechal Department: Department of Surface and Plasma Science Supervisor: doc. RNDr. Lubomír Přech, Dr. Supervisor's e-mail address: Abstract: The thesis introduces into basic knowledge of waves in plasma, especially waves in the Earth's magnetosphere. There are mentioned some space projects focused on chorus waves. The second part of this thesis is a la...
Analysis of wave directional spreading using neural networks
Digital Repository Service at National Institute of Oceanography (India)
Deo, M.C.; Gondane, D.S.; SanilKumar, V.
describes how a representative spreading parameter could be arrived at from easily available wave parameters such as significant wave height and average zero-cross wave period, using the technique of neural networks. It is shown that training of the network...
Directory of Open Access Journals (Sweden)
Kasgin Khaheshi Banab
2010-01-01
Full Text Available The multi-channel analysis of surface waves (MASWs method was used to obtain the shear wave velocity variations through near surface (depth 2,300 m/s is very large. The MASW velocity results compared with those of other geophysical approaches, such as seismic reflection/refraction methods and borehole data, where available, mostly confirming the capability of the MASW method to distinguish the high shear wave velocity contrast in the study area. We have found that, of the inversion procedures of MASW data, the random search inversion technique provides better results than the analytical generalized inversion method.
Cho, Hwi-Young; Kim, Kitae; Lee, Byounghee; Jung, Jinhwa
2015-03-01
[Purpose] This study investigated a brain wave and visual perception changes in stroke subjects using neurofeedback (NFB) training. [Subjects] Twenty-seven stroke subjects were randomly allocated to the NFB (n = 13) group and the control group (n=14). [Methods] Two expert therapists provided the NFB and CON groups with traditional rehabilitation therapy in 30 thirst-minute sessions over the course of 6 weeks. NFB training was provided only to the NFB group. The CON group received traditional rehabilitation therapy only. Before and after the 6-week intervention, a brain wave test and motor free visual perception test (MVPT) were performed. [Results] Both groups showed significant differences in their relative beta wave values and attention concentration quotients. Moreover, the NFB group showed a significant difference in MVPT visual discrimination, form constancy, visual memory, visual closure, spatial relation, raw score, and processing time. [Conclusion] This study demonstrated that NFB training is more effective for increasing concentration and visual perception changes than traditional rehabilitation. In further studies, detailed and diverse investigations should be performed considering the number and characteristics of subjects, and the NFB training period.
Eigenmode analysis of compressional waves in the magnetosphere
International Nuclear Information System (INIS)
Cheng, C.Z.; Lin, C.S.
1987-04-01
A field-aligned eigenode analysis of compressional Alfven instabilities has been performed for a two component anisotropic plasma in a dipole magnetic field. The eigenmode equations are derived from the gyrokinetic equations in the long wavelength (k rho < 1) and low frequency (ω < ω/sub b/) limits, where rho is the hot particle gyroradius and ω/sub b/ is the hot particle bounce frequency. Two types of compressional instabilities are identified. One is the drift mirror mode which has an odd parity compressional magnetic component with respect to the magnetic equator. The other is the drift compressional mode with an even parity compressional magnetic component. For typical storm time plasma parameters neargeosynchronous orbit, the drift mirror mode is most unstable and the drift compressional mode is stable. The storm time compressional Pc 5 waves, observed by multiple satellites during November 14-15, 1979 [Takahashi et al., 1987], can be explained by the drift mirror instability
Poles of the Zagreb analysis partial-wave T matrices
Batinić, M.; Ceci, S.; Švarc, A.; Zauner, B.
2010-09-01
The Zagreb analysis partial-wave T matrices included in the Review of Particle Physics [by the Particle Data Group (PDG)] contain Breit-Wigner parameters only. As the advantages of pole over Breit-Wigner parameters in quantifying scattering matrix resonant states are becoming indisputable, we supplement the original solution with the pole parameters. Because of an already reported numeric error in the S11 analytic continuation [Batinić , Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.57.1004 57, 1004(E) (1997); arXiv:nucl-th/9703023], we declare the old BATINIC 95 solution, presently included by the PDG, invalid. Instead, we offer two new solutions: (A) corrected BATINIC 95 and (B) a new solution with an improved S11 πN elastic input. We endorse solution (B).
Thermal analysis of gyrotron traveling-wave tube collector
International Nuclear Information System (INIS)
Zheng Zhiqing; Luo Yong; Jiang Wei; Tang Yong
2013-01-01
In order to solve cooling problem of the gyrotron traveling-wave tube(TWT) collector and guarantee the gyrotron TWT's reliability and stability, the electron trajectories in the gyrotron TWT are simulated using CST electron simulation software. Thermal analysis of the collector with finite element software ANSYS is performed. The ways of applying boundary that affects the distribution of collector temperature are compared. The influence of the water temperature and flow rate on collector temperature distribution under actual heat fluxes (boundary condition) is researched. The size and number of collector fins are optimized, and a relatively perfect structure is obtained finally. The result estimated by simulation is consistent with the experiment and proves that the model and method employed in this work are suitable. (authors)
Wave Analysis for West Coast of South Myanmar
Directory of Open Access Journals (Sweden)
Xu Yanan
2015-01-01
Full Text Available The characteristic of southern parts of Myanmar is tropical monsoon climate, and this area is affected by few typhoons. The wave height is changed with season, the field measured data shows that the aver-age monthly maximum wave height is in June. The wave height, swelling from Indian Ocean and spreading to research area, is small. The research adopts SWAN model to simulate the waves that are transformed from off-shore to nearshore Myanmar based on the meteorological data from ECMWF. The simulated results were com-pared with satellite data and field measured data, it showed that the trend between the curves is unified, and the extreme value of simulation is close to the measured value. The simulation presents wave distribution around Myanmar southern sea, it shows that the wave height and wave directions are affected by terrain refraction and island trains shielding. When the wave is from WSW direction, the wave will be decreased fast caused by island shielding, and the direction turns to W direction at northern coastline. When the wave comes from SSW direction, the island shielding will be weak, the wave will be decreased slowly, and the direction will turn to SW direction at southern coastline.
Analysis of Technical Feasibility of Traveling Wave Reactor
International Nuclear Information System (INIS)
Kim, Sang Ji; Yoo, Jae Woon; Bae, In Ho
2011-01-01
The status and trend of TWR, patent status and its major technical characteristics were examined in this study. Main technical features of traveling wave reactor can be characterized as a reactor operation without refueling up to the reactor life more than 60 years and TWR utilizes depleted uranium which would be produced from the enrichment process as a byproduct. Enriched fuel is only loaded to an igniter which is required for initiation of burning wave. In this study, quantitative analysis of TWR arising from the technical features was carried out in terms of resource utilization, safety and integrity, and proliferation resistance. In parallel with the concept review of TerraPower SWR design concepts, independent analysis of SWR design by altering a design specification and operation strategy was done in this study. The fuel rod design of SWR was also investigated based on the current database of fuel irradiation and performance. The technical issues of TWR or SWR which should be prior to detailed research and development can be summarized as follows: ·Strong physical protection is required during the shuffling or in-service inspection period to improve the proliferation resistance. ·New flow control logic or device is required for distributing the assembly-wise flow to be corresponded with power swing of fuel assembly. ·High integrity cladding material need to be developed for covering the high fast neutron fluence more than three times of current limit which result from the high burnup and long fuel cycle. The metal fuel under the high burnup condition should be validated through the irradiation test
DISPELLING ILLUSIONS OF REFLECTION: A NEW ANALYSIS OF THE 2007 MAY 19 CORONAL 'WAVE' EVENT
International Nuclear Information System (INIS)
Attrill, Gemma D. R.
2010-01-01
A new analysis of the 2007 May 19 coronal wave-coronal mass ejection-dimmings event is offered employing base difference extreme-ultraviolet (EUV) images. Previous work analyzing the coronal wave associated with this event concluded strongly in favor of purely an MHD wave interpretation for the expanding bright front. This conclusion was based to a significant extent on the identification of multiple reflections of the coronal wave front. The analysis presented here shows that the previously identified 'reflections' are actually optical illusions and result from a misinterpretation of the running difference EUV data. The results of this new multiwavelength analysis indicate that two coronal wave fronts actually developed during the eruption. This new analysis has implications for our understanding of diffuse coronal waves and questions the validity of the analysis and conclusions reached in previous studies.
Utility based maintenance analysis using a Random Sign censoring model
International Nuclear Information System (INIS)
Andres Christen, J.; Ruggeri, Fabrizio; Villa, Enrique
2011-01-01
Industrial systems subject to failures are usually inspected when there are evident signs of an imminent failure. Maintenance is therefore performed at a random time, somehow dependent on the failure mechanism. A competing risk model, namely a Random Sign model, is considered to relate failure and maintenance times. We propose a novel Bayesian analysis of the model and apply it to actual data from a water pump in an oil refinery. The design of an optimal maintenance policy is then discussed under a formal decision theoretic approach, analyzing the goodness of the current maintenance policy and making decisions about the optimal maintenance time.
Gorodnichev, E E
2018-04-01
The problem of multiple scattering of polarized light in a two-dimensional medium composed of fiberlike inhomogeneities is studied. The attenuation lengths for the density matrix elements are calculated. For a highly absorbing medium it is found that, as the sample thickness increases, the intensity of waves polarized along the fibers decays faster than the other density matrix elements. With further increase in the sample thickness, the off-diagonal elements which are responsible for correlations between the cross-polarized waves disappear. In the asymptotic limit of very thick samples the scattered light proves to be polarized perpendicular to the fibers. The difference in the attenuation lengths between the density matrix elements results in a nonmonotonic depth dependence of the degree of polarization. In the opposite case of a weakly absorbing medium, the off-diagonal element of the density matrix and, correspondingly, the correlations between the cross-polarized fields are shown to decay faster than the intensity of waves polarized along and perpendicular to the fibers.
Person mobility in the design and analysis of cluster-randomized cohort prevention trials.
Vuchinich, Sam; Flay, Brian R; Aber, Lawrence; Bickman, Leonard
2012-06-01
Person mobility is an inescapable fact of life for most cluster-randomized (e.g., schools, hospitals, clinic, cities, state) cohort prevention trials. Mobility rates are an important substantive consideration in estimating the effects of an intervention. In cluster-randomized trials, mobility rates are often correlated with ethnicity, poverty and other variables associated with disparity. This raises the possibility that estimated intervention effects may generalize to only the least mobile segments of a population and, thus, create a threat to external validity. Such mobility can also create threats to the internal validity of conclusions from randomized trials. Researchers must decide how to deal with persons who leave study clusters during a trial (dropouts), persons and clusters that do not comply with an assigned intervention, and persons who enter clusters during a trial (late entrants), in addition to the persons who remain for the duration of a trial (stayers). Statistical techniques alone cannot solve the key issues of internal and external validity raised by the phenomenon of person mobility. This commentary presents a systematic, Campbellian-type analysis of person mobility in cluster-randomized cohort prevention trials. It describes four approaches for dealing with dropouts, late entrants and stayers with respect to data collection, analysis and generalizability. The questions at issue are: 1) From whom should data be collected at each wave of data collection? 2) Which cases should be included in the analyses of an intervention effect? and 3) To what populations can trial results be generalized? The conclusions lead to recommendations for the design and analysis of future cluster-randomized cohort prevention trials.
Scattering analysis of point processes and random measures
International Nuclear Information System (INIS)
Hanisch, K.H.
1984-01-01
In the present paper scattering analysis of point processes and random measures is studied. Known formulae which connect the scattering intensity with the pair distribution function of the studied structures are proved in a rigorous manner with tools of the theory of point processes and random measures. For some special fibre processes the scattering intensity is computed. For a class of random measures, namely for 'grain-germ-models', a new formula is proved which yields the pair distribution function of the 'grain-germ-model' in terms of the pair distribution function of the underlying point process (the 'germs') and of the mean structure factor and the mean squared structure factor of the particles (the 'grains'). (author)
Digital Repository Service at National Institute of Oceanography (India)
Varkey, M.J
, steep nonsymmetric cnoidal waves, solitons and random waves. They have different properties too. Any wave form has a wave period (T), wave height (H) and speed (C) which depends on T. Still another type of waves are breaking waves near a coast...
Structural Loads Analysis for Wave Energy Converters: Preprint
Energy Technology Data Exchange (ETDEWEB)
van Rij, Jennifer A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yu, Yi-Hsiang [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Guo, Yi [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2017-08-09
This study explores and verifies the generalized body-modes method for evaluating the structural loads on a wave energy converter (WEC). Historically, WEC design methodologies have focused primarily on accurately evaluating hydrodynamic loads, while methodologies for evaluating structural loads have yet to be fully considered and incorporated into the WEC design process. As wave energy technologies continue to advance, however, it has become increasingly evident that an accurate evaluation of the structural loads will enable an optimized structural design, as well as the potential utilization of composites and flexible materials, and hence reduce WEC costs. Although there are many computational fluid dynamics, structural analyses and fluid-structure-interaction (FSI) codes available, the application of these codes is typically too computationally intensive to be practical in the early stages of the WEC design process. The generalized body-modes method, however, is a reduced order, linearized, frequency-domain FSI approach, performed in conjunction with the linear hydrodynamic analysis, with computation times that could realistically be incorporated into the WEC design process. The objective of this study is to verify the generalized body-modes approach in comparison to high-fidelity FSI simulations to accurately predict structural deflections and stress loads in a WEC. Two verification cases are considered, a free-floating barge and a fixed-bottom column. Details for both the generalized body-modes models and FSI models are first provided. Results for each of the models are then compared and discussed. Finally, based on the verification results obtained, future plans for incorporating the generalized body-modes method into the WEC simulation tool, WEC-Sim, and the overall WEC design process are discussed.
DEFF Research Database (Denmark)
Wang, W.; Hanson, Steen Grüner; Miyamoto, Y.
2005-01-01
We present the first direct experimental evidence of the local properties of optical vortices in a random laser speckle field. We have observed the Berry anisotropy ellipse describing the anisotropic squeezing of phase lines close to vortex cores and quantitatively verified the Dennis angular mom...
A wave parameters and directional spectrum analysis for extreme winds
Montoya Ramírez, Rubén Darío; Osorio Arias, Andres Fernando; Ortiz Royero, Juan Carlos; Ocampo-Torres, Francisco Javier
2013-01-01
In this research a comparison between two of the most popular ocean wave models, WAVEWATCH III™ and SWAN, was performed using data from hurricane Katrina in the Gulf of Mexico. The numerical simulation of sea surface directional wave spectrum and other wave parameters for several parameter- izations and its relation with the drag coefﬁcient was carried out. The simulated data were compared with in-situ NOAA buoy data. For most of the buoys, WAVEWATCH III™ presented the best statistical compar...
Analysis of supercritical vapor explosions using thermal detonation wave theory
Energy Technology Data Exchange (ETDEWEB)
Shamoun, B.I.; Corradini, M.L. [Univ. of Wisconsin, Madison, WI (United States)
1995-09-01
The interaction of certain materials such as Al{sub 2}O{sub 3} with water results in vapor explosions with very high (supercritical) pressures and propagation velocities. A quasi-steady state analysis of supercritical detonation in one-dimensional multiphase flow was applied to analyze experimental data of the KROTOS (26-30) set of experiments conducted at the Joint Research Center at Ispra, Italy. In this work we have applied a new method of solution which allows for partial fragmentation of the fuel in the shock adiabatic thermodynamic model. This method uses known experiment values of the shock pressure and propagation velocity to estimate the initial mixing conditions of the experiment. The fuel and coolant were both considered compressible in this analysis. In KROTOS 26, 28, 29, and 30 the measured values of the shock pressure by the experiment were found to be higher than 25, 50, 100, and 100 Mpa respectively. Using the above data for the wave velocity and our best estimate for the values of the pressure, the predicted minimum values of the fragmented mass of the fuel were found to be 0.026. 0.04, 0.057, and 0.068 kg respectively. The predicted values of the work output corresponding to the above fragmented masses of the fuel were found to be 40, 84, 126, and 150 kJ respectively, with predicted initial void fractions of 112%, 12.5%, 8%, and 6% respectively.
Surface acoustic wave nebulization facilitating lipid mass spectrometric analysis.
Yoon, Sung Hwan; Huang, Yue; Edgar, J Scott; Ting, Ying S; Heron, Scott R; Kao, Yuchieh; Li, Yanyan; Masselon, Christophe D; Ernst, Robert K; Goodlett, David R
2012-08-07
Surface acoustic wave nebulization (SAWN) is a novel method to transfer nonvolatile analytes directly from the aqueous phase to the gas phase for mass spectrometric analysis. The lower ion energetics of SAWN and its planar nature make it appealing for analytically challenging lipid samples. This challenge is a result of their amphipathic nature, labile nature, and tendency to form aggregates, which readily precipitate clogging capillaries used for electrospray ionization (ESI). Here, we report the use of SAWN to characterize the complex glycolipid, lipid A, which serves as the membrane anchor component of lipopolysaccharide (LPS) and has a pronounced tendency to clog nano-ESI capillaries. We also show that unlike ESI SAWN is capable of ionizing labile phospholipids without fragmentation. Lastly, we compare the ease of use of SAWN to the more conventional infusion-based ESI methods and demonstrate the ability to generate higher order tandem mass spectral data of lipid A for automated structure assignment using our previously reported hierarchical tandem mass spectrometry (HiTMS) algorithm. The ease of generating SAWN-MS(n) data combined with HiTMS interpretation offers the potential for high throughput lipid A structure analysis.
Probabilistic analysis of structures involving random stress-strain behavior
Millwater, H. R.; Thacker, B. H.; Harren, S. V.
1991-01-01
The present methodology for analysis of structures with random stress strain behavior characterizes the uniaxial stress-strain curve in terms of (1) elastic modulus, (2) engineering stress at initial yield, (3) initial plastic-hardening slope, (4) engineering stress at point of ultimate load, and (5) engineering strain at point of ultimate load. The methodology is incorporated into the Numerical Evaluation of Stochastic Structures Under Stress code for probabilistic structural analysis. The illustrative problem of a thick cylinder under internal pressure, where both the internal pressure and the stress-strain curve are random, is addressed by means of the code. The response value is the cumulative distribution function of the equivalent plastic strain at the inner radius.
Wave propagation in semi-infinite bar with random imperfectios of mass and elasticity module
Czech Academy of Sciences Publication Activity Database
Náprstek, Jiří
2007-01-01
Roč. 310, č. 3 (2007), s. 676-693 ISSN 0022-460X R&D Projects: GA AV ČR(CZ) IAA2071401; GA ČR(CZ) GA103/06/0099 Institutional research plan: CEZ:AV0Z20710524 Keywords : elasticity module * Young modulus * random imperfections Subject RIV: JM - Building Engineering Impact factor: 1.024, year: 2007
Renormalization group treatment for spin waves in the randomly disordered Heisenberg chain
International Nuclear Information System (INIS)
Chaves, C.M.; Koiller, B.
1983-03-01
Local densities of states in the randomly disordered binary quantum Heisenberg chain using a generalization of a recently developed approach based on renormalization group ideas are calculated. It envolves decimating alternate apins along the chain in such a way as to obtain recursion relations to describe the renormalized set of Green's function equations of motion. The densities of states are richly structured, indicating that the method takes into account compositional fluctuations of arbitrary range. (Author) [pt
Wave Analysis Study for the Punta Catalina Jetty, Dominican Republic
DEFF Research Database (Denmark)
Røge, Mads Sønderstrup; Andersen, Thomas Lykke; Burcharth, Hans Falk
This report deals with a two-dimensional test study to identify the largest significant wave height, the maximum wave height and the largest crest level along the Punta Catalina jetty in the Dominican Republic. The scale used for the model tests was 1:50. Unless otherwise specified all values given...
Analysis of wave equation in electromagnetic field by Proca equation
International Nuclear Information System (INIS)
Pamungkas, Oky Rio; Soeparmi; Cari
2017-01-01
This research is aimed to analyze wave equation for the electric and magnetic field, vector and scalar potential, and continuity equation using Proca equation. Then, also analyze comparison of the solution on Maxwell and Proca equation for scalar potential and electric field, both as a function of distance and constant wave number. (paper)
Wave analysis at frictional interface: A case wise study
Srivastava, Akanksha; Chattopadhyay, Amares; Singh, Pooja; Singh, Abhishek Kumar
2018-03-01
The present article deals with the propagation of a Stoneley wave and with the reflection as well as refraction of an incident P -wave at the frictional bonded interface between an initially stressed isotropic viscoelastic semi-infinite superstratum and an initially stressed isotropic substratum as case I and case II, respectively. The complex form of the velocity equation has been derived in closed form for the propagation of a Stoneley wave in the said structure. The real and imaginary parts of the complex form of the velocity equation correspond to the phase velocity and damped velocity of the Stoneley wave. Phase and damped velocity have been analysed against the angular frequency. The expressions of the amplitude ratios of the reflected and refracted waves are deduced analytically. The variation of the amplitude ratios is examined against the angle of incidence of the P -wave. The influence of frictional boundary parameters, initial stress, viscoelastic parameters on the phase and damped velocities of the Stoneley wave and the amplitude ratios of the reflected as well as refracted P - and SV -wave have been revealed graphically through numerical results.
Multi-component joint analysis of surface waves
Czech Academy of Sciences Publication Activity Database
Dal Moro, Giancarlo; Moura, R.M.M.; Moustafa, S.S.R.
2015-01-01
Roč. 119, AUG (2015), s. 128-138 ISSN 0926-9851 Institutional support: RVO:67985891 Keywords : surface waves * surface wave dispersion * seismic data acquisition * seismic data inversion * velocity spectrum Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.355, year: 2015
Bifurcation analysis and the travelling wave solutions of the Klein
Indian Academy of Sciences (India)
In this paper, we investigate the bifurcations and dynamic behaviour of travelling wave solutions of the Klein–Gordon–Zakharov equations given in Shang et al, Comput. Math. Appl. 56, 1441 (2008). Under different parameter conditions, we obtain some exact explicit parametric representations of travelling wave solutions by ...
Physiology and analysis of the electrocardiographic T wave in mice
DEFF Research Database (Denmark)
Speerschneider, T; Thomsen, Morten Bækgaard
2013-01-01
The murine electrocardiogram (ECG) is a valuable tool in cardiac research, although the definition of the T wave has been a matter of debate for several years potentially leading to incomparable data. By this study, we seek to make a clear definition of the murine T wave. Moreover, we investigate...... the consequences of performing QT interval correction in anaesthetized mice....
Analysis and design of efficient planar leaky-wave antennas
Ettore, M.
2008-01-01
This thesis deals with the effective design of planar leaky-wave antennas. The work describes a methodology based on the polar expansion of Green's function representations to address very different geometrical configurations which might appear to have little in common. In fact leaky waves with
Zhu, P. Y.
1991-01-01
The effective-medium approximation is applied to investigate scattering from a half-space of randomly and densely distributed discrete scatterers. Starting from vector wave equations, an approximation, called effective-medium Born approximation, a particular way, treating Green's functions, and special coordinates, of which the origin is set at the field point, are used to calculate the bistatic- and back-scatterings. An analytic solution of backscattering with closed form is obtained and it shows a depolarization effect. The theoretical results are in good agreement with the experimental measurements in the cases of snow, multi- and first-year sea-ice. The root product ratio of polarization to depolarization in backscattering is equal to 8; this result constitutes a law about polarized scattering phenomena in the nature.
Modal analysis of wave propagation in dispersive media
Abdelrahman, M. Ismail; Gralak, B.
2018-01-01
Surveys on wave propagation in dispersive media have been limited since the pioneering work of Sommerfeld [Ann. Phys. 349, 177 (1914), 10.1002/andp.19143491002] by the presence of branches in the integral expression of the wave function. In this article a method is proposed to eliminate these critical branches and hence to establish a modal expansion of the time-dependent wave function. The different components of the transient waves are physically interpreted as the contributions of distinct sets of modes and characterized accordingly. Then, the modal expansion is used to derive a modified analytical expression of the Sommerfeld precursor improving significantly the description of the amplitude and the oscillating period up to the arrival of the Brillouin precursor. The proposed method and results apply to all waves governed by the Helmholtz equations.
Integrated analysis of energy transfers in elastic-wave turbulence.
Yokoyama, Naoto; Takaoka, Masanori
2017-08-01
In elastic-wave turbulence, strong turbulence appears in small wave numbers while weak turbulence does in large wave numbers. Energy transfers in the coexistence of these turbulent states are numerically investigated in both the Fourier space and the real space. An analytical expression of a detailed energy balance reveals from which mode to which mode energy is transferred in the triad interaction. Stretching energy excited by external force is transferred nonlocally and intermittently to large wave numbers as the kinetic energy in the strong turbulence. In the weak turbulence, the resonant interactions according to the weak turbulence theory produce cascading net energy transfer to large wave numbers. Because the system's nonlinearity shows strong temporal intermittency, the energy transfers are investigated at active and moderate phases separately. The nonlocal interactions in the Fourier space are characterized by the intermittent bundles of fibrous structures in the real space.
Transient space-time surface waves characterization using Gabor analysis
Energy Technology Data Exchange (ETDEWEB)
Martinez, L; Wilkie-Chancellier, N; Caplain, E [Universite de Cergy Pontoise, ENS Cachan, UMR CNRS 8029, Laboratoire Systemes et Applications des Techniques de l' Information et de l' Energie (SATIE), 5 mail Gay-Lussac, F 9500 Cergy-Pontoise (France); Glorieux, C; Sarens, B, E-mail: nicolas.wilkie-chancellier@u-cergy.f [Katholieke Universiteit Leuven, Laboratorium voor Akoestiek en Thermische Fysica (LATF), Celestijnenlaan 200D, B-3001 Leuven (Belgium)
2009-11-01
Laser ultrasonics allow the observation of transient surface waves along their propagation media and their interaction with encountered objects like cracks, holes, borders. In order to characterize and localize these transient aspects in the Space-Time-Wave number-Frequency domains, the 1D, 2D and 3D Gabor transforms are presented. The Gabor transform enables the identification of several properties of the local wavefronts such as their shape, wavelength, frequency, attenuation, group velocity and the full conversion sequence along propagation. The ability of local properties identification by Gabor transform is illustrated by two experimental studies: Lamb waves generated by an annular source on a circular quartz and Lamb wave interaction with a fluid droplet. In both cases, results obtained with Gabor transform enable ones to identify the observed local waves.
Hayashi, Shuji; Yamada, Hirotsugu; Bando, Mika; Saijo, Yoshihito; Nishio, Susumu; Hirata, Yukina; Klein, Allan L; Sata, Masataka
2015-08-01
Left atrial (LA) strain analysis using speckle tracking echocardiography is useful for assessing LA function. However, there is no established procedure for this method. Most investigators have determined the electrocardiographic R-wave peak as the starting point for LA strain analysis. To test our hypothesis that P-wave onset should be used as the starting point, we measured LA strain using 2 different starting points and compared the strain values with the corresponding LA volume indices obtained by three-dimensional (3D) echocardiography. We enrolled 78 subjects (61 ± 17 years, 25 males) with and without various cardiac diseases in this study and assessed global longitudinal LA strain by two-dimensional speckle tracking strain echocardiography using EchoPac software. We used either R-wave peak or P-wave onset as the starting point for determining LA strains during the reservoir (Rres, Pres), conduit (Rcon, Pcon), and booster pump (Rpump, Ppump) phases. We determined the maximum, minimum, and preatrial contraction LA volumes, and calculated the LA total, passive, and active emptying fractions using 3D echocardiography. The correlation between Pres and LA total emptying fraction was better than the correlation between Rres and LA total emptying fraction (r = 0.458 vs. 0.308, P = 0.026). Pcon and Ppump exhibited better correlation with the corresponding 3D echocardiographic parameters than Rcon (r = 0.560 vs. 0.479, P = 0.133) and Rpump (r = 0.577 vs. 0.345, P = 0.003), respectively. LA strain in any phase should be analyzed using P-wave onset as the starting point rather than R-wave peak. © 2014, Wiley Periodicals, Inc.
Tan, Shurun
The objective of my research is two-fold: to study wave scattering phenomena in dense volumetric random media and in periodic wave functional materials. For the first part, the goal is to use the microwave remote sensing technique to monitor water resources and global climate change. Towards this goal, I study the microwave scattering behavior of snow and ice sheet. For snowpack scattering, I have extended the traditional dense media radiative transfer (DMRT) approach to include cyclical corrections that give rise to backscattering enhancements, enabling the theory to model combined active and passive observations of snowpack using the same set of physical parameters. Besides DMRT, a fully coherent approach is also developed by solving Maxwell's equations directly over the entire snowpack including a bottom half space. This revolutionary new approach produces consistent scattering and emission results, and demonstrates backscattering enhancements and coherent layer effects. The birefringence in anisotropic snow layers is also analyzed by numerically solving Maxwell's equation directly. The effects of rapid density fluctuations in polar ice sheet emission in the 0.5˜2.0 GHz spectrum are examined using both fully coherent and partially coherent layered media emission theories that agree with each other and distinct from incoherent approaches. For the second part, the goal is to develop integral equation based methods to solve wave scattering in periodic structures such as photonic crystals and metamaterials that can be used for broadband simulations. Set upon the concept of modal expansion of the periodic Green's function, we have developed the method of broadband Green's function with low wavenumber extraction (BBGFL), where a low wavenumber component is extracted and results a non-singular and fast-converging remaining part with simple wavenumber dependence. We've applied the technique to simulate band diagrams and modal solutions of periodic structures, and to
Nonlinear Modeling and Analysis of Pressure Wave inside CEUP Fuel Pipeline
Directory of Open Access Journals (Sweden)
Qaisar Hayat
2014-01-01
Full Text Available Operating conditions dependent large pressure variations are one of the working characteristics of combination electronic unit pump (CEUP fuel injection system for diesel engines. We propose a precise and accurate nonlinear numerical model of pressure inside HP fuel pipeline of CEUP using wave equation (WE including both viscous and frequency dependent frictions. We have proved that developed hyperbolic approximation gives more realistic description of pressure wave as compared to classical viscous damped wave equation. Frictional effects of various frequencies on pressure wave have been averaged out across valid frequencies to represent the combined effect of all frequencies on pressure wave. Dynamic variations of key fuel properties including density, acoustic wave speed, and bulk modulus with varying pressures have also been incorporated. Based on developed model we present analysis on effect of fuel pipeline length on pressure wave propagation and variation of key fuel properties with both conventional diesel and alternate fuel rapeseed methyl ester (RME for CEUP pipeline.
Lee, Kwang Jin; Kim, Kihong
2011-10-10
We study theoretically the propagation and the Anderson localization of p-polarized electromagnetic waves incident obliquely on randomly stratified dielectric media with weak uncorrelated Gaussian disorder. Using the invariant imbedding method, we calculate the localization length and the disorder-averaged transmittance in a numerically precise manner. We find that the localization length takes an extremely large maximum value at some critical incident angle, which we call the generalized Brewster angle. The disorder-averaged transmittance also takes a maximum very close to one at the same incident angle. Even in the presence of an arbitrarily weak disorder, the generalized Brewster angle is found to be substantially different from the ordinary Brewster angle in uniform media. It is a rapidly increasing function of the average dielectric permittivity and approaches 90° when the average relative dielectric permittivity is slightly larger than two. We make a remarkable observation that the dependence of the generalized Brewster angle on the average dielectric permittivity is universal in the sense that it is independent of the strength of disorder. We also find, surprisingly, that when the average relative dielectric permittivity is less than one and the incident angle is larger than the generalized Brewster angle, both the localization length and the disorder-averaged transmittance increase substantially as the strength of disorder increases in a wide range of the disorder parameter. In other words, the Anderson localization of incident p waves can be weakened by disorder in a certain parameter regime.
Tornese, Davide; Mattei, Enrico; Lucchesi, Giampaolo; Bandi, Marco; Ricci, Gabriele; Melegati, Gianluca
2008-09-01
To describe and compare two extracorporeal shock wave therapy techniques for the treatment of painful subcalcaneal spur. Random assignment to two groups of treatment with two and eight months follow-up. The data were collected in outpatients. Forty-five subjects with a history of at least six months of heel pain were studied. Each subject received a three-session ultrasound-guided extracorporeal shock wave therapy (performed weekly). Perpendicular technique was used in group A (n=22, mean age 59.3 +/- 12 years) and tangential technique was used in group B (n= 23, mean age 58.8 +/- 12.3 years). Mayo Clinical Scoring System was used to evaluate each subject before the treatment and at two and eight months follow-up. Mayo Clinical Scoring System pretreatment scores were homogeneous between the groups (group A 55.2 +/-18.7; group B 53.5 +/- 20; P>0.05). In both groups there was a significant (Pwave therapy. The tangential technique was found to be better tolerated as regards treatment-induced pain, allowing higher energy dosages to be used.
Diffusing wave spectroscopy applied to material analysis and process control
International Nuclear Information System (INIS)
Lloyd, Christopher James
1997-01-01
Diffusing Wave Spectroscopy (DWS) was studied as a method of laboratory analysis of sub-micron particles, and developed as a prospective in-line, industrial, process control sensor, capable of near real-time feedback. No sample pre-treatment was required and measurement was via a non-invasive, flexible, dip in probe. DWS relies on the concept of the diffusive migration of light, as opposed to the ballistic scatter model used in conventional dynamic light scattering. The specific requirements of the optoelectronic hardware, data analysis methods and light scattering model were studied experimentally and, where practical, theoretically resulting in a novel technique of analysis of particle suspensions and emulsions of volume fractions between 0.01 and 0.4. Operation at high concentrations made the technique oblivious to dust and contamination. A pure homodyne (autodyne) experimental arrangement described was resilient to environmental disturbances, unlike many other systems which utilise optical fibres or heterodyne operation. Pilot and subsequent prototype development led to a highly accurate method of size ranking, suitable for analysis of a wide range of suspensions and emulsions. The technique was shown to operate on real industrial samples with statistical variance as low as 0.3% with minimal software processing. Whilst the application studied was the analysis of TiO 2 suspensions, a diverse range of materials including polystyrene beads, cell pastes and industrial cutting fluid emulsions were tested. Results suggest that, whilst all sizing should be comparative to suitable standards, concentration effects may be minimised and even completely modelled-out in many applications. Adhesion to the optical probe was initially a significant problem but was minimised after the evaluation and use of suitable non stick coating materials. Unexpected behaviour in the correlation in the region of short decay times led to consideration of the effects of rotational diffusion
Single realization stochastic FDTD for weak scattering waves in biological random media.
Tan, Tengmeng; Taflove, Allen; Backman, Vadim
2013-02-01
This paper introduces an iterative scheme to overcome the unresolved issues presented in S-FDTD (stochastic finite-difference time-domain) for obtaining ensemble average field values recently reported by Smith and Furse in an attempt to replace the brute force multiple-realization also known as Monte-Carlo approach with a single-realization scheme. Our formulation is particularly useful for studying light interactions with biological cells and tissues having sub-wavelength scale features. Numerical results demonstrate that such a small scale variation can be effectively modeled with a random medium problem which when simulated with the proposed S-FDTD indeed produces a very accurate result.
Wave propagation in semi-infinite bar with random imperfections of density and elasticity module
Czech Academy of Sciences Publication Activity Database
Náprstek, Jiří
2008-01-01
Roč. 310, č. 3 (2008), s. 676-693 ISSN 0022-460X R&D Projects: GA ČR(CZ) GA103/06/0099; GA AV ČR(CZ) IAA2071401 Institutional research plan: CEZ:AV0Z20710524 Keywords : correlation methods * elastic moduli * finite element method * random processes Subject RIV: JM - Building Engineering Impact factor: 1.364, year: 2008 http://www.sciencedirect.com/science/article/pii/S0022460X07002374?np=y
Analysis of Wave Reflection from Wave Energy Converters Installed as Breakwaters in Harbour
DEFF Research Database (Denmark)
Zanuttigh, B.; Margheritini, Lucia; Gambles, L.
2009-01-01
loads on the structure, i.e. better survivability. Nevertheless these devices must comply with the requirements of harbour protection structures and thus cope with problems due to reflection of incoming waves, i.e. dangerous sea states close to harbors entrances and intensified sediment scour, which can...
On the resolution of ECG acquisition systems for the reliable analysis of the P-wave
International Nuclear Information System (INIS)
Censi, Federica; Calcagnini, Giovanni; Mattei, Eugenio; Triventi, Michele; Bartolini, Pietro; Corazza, Ivan; Boriani, Giuseppe
2012-01-01
The analysis of the P-wave on surface ECG is widely used to assess the risk of atrial arrhythmias. In order to provide reliable results, the automatic analysis of the P-wave must be precise and reliable and must take into account technical aspects, one of those being the resolution of the acquisition system. The aim of this note is to investigate the effects of the amplitude resolution of ECG acquisition systems on the P-wave analysis. Starting from ECG recorded by an acquisition system with a less significant bit (LSB) of 31 nV (24 bit on an input range of 524 mVpp), we reproduced an ECG signal as acquired by systems with lower resolution (16, 15, 14, 13 and 12 bit). We found that, when the LSB is of the order of 128 µV (12 bit), a single P-wave is not recognizable on ECG. However, when averaging is applied, a P-wave template can be extracted, apparently suitable for the P-wave analysis. Results obtained in terms of P-wave duration and morphology revealed that the analysis of ECG at lowest resolutions (from 12 to 14 bit, LSB higher than 30 µV) could lead to misleading results. However, the resolution used nowadays in modern electrocardiographs (15 and 16 bit, LSB <10 µV) is sufficient for the reliable analysis of the P-wave. (note)
Vanmarcke, Erik
1983-03-01
Random variation over space and time is one of the few attributes that might safely be predicted as characterizing almost any given complex system. Random fields or "distributed disorder systems" confront astronomers, physicists, geologists, meteorologists, biologists, and other natural scientists. They appear in the artifacts developed by electrical, mechanical, civil, and other engineers. They even underlie the processes of social and economic change. The purpose of this book is to bring together existing and new methodologies of random field theory and indicate how they can be applied to these diverse areas where a "deterministic treatment is inefficient and conventional statistics insufficient." Many new results and methods are included. After outlining the extent and characteristics of the random field approach, the book reviews the classical theory of multidimensional random processes and introduces basic probability concepts and methods in the random field context. It next gives a concise amount of the second-order analysis of homogeneous random fields, in both the space-time domain and the wave number-frequency domain. This is followed by a chapter on spectral moments and related measures of disorder and on level excursions and extremes of Gaussian and related random fields. After developing a new framework of analysis based on local averages of one-, two-, and n-dimensional processes, the book concludes with a chapter discussing ramifications in the important areas of estimation, prediction, and control. The mathematical prerequisite has been held to basic college-level calculus.
STATISTICAL ANALYSIS OF ACOUSTIC WAVE PARAMETERS NEAR SOLAR ACTIVE REGIONS
International Nuclear Information System (INIS)
Rabello-Soares, M. Cristina; Bogart, Richard S.; Scherrer, Philip H.
2016-01-01
In order to quantify the influence of magnetic fields on acoustic mode parameters and flows in and around active regions, we analyze the differences in the parameters in magnetically quiet regions nearby an active region (which we call “nearby regions”), compared with those of quiet regions at the same disk locations for which there are no neighboring active regions. We also compare the mode parameters in active regions with those in comparably located quiet regions. Our analysis is based on ring-diagram analysis of all active regions observed by the Helioseismic and Magnetic Imager (HMI) during almost five years. We find that the frequency at which the mode amplitude changes from attenuation to amplification in the quiet nearby regions is around 4.2 mHz, in contrast to the active regions, for which it is about 5.1 mHz. This amplitude enhacement (the “acoustic halo effect”) is as large as that observed in the active regions, and has a very weak dependence on the wave propagation direction. The mode energy difference in nearby regions also changes from a deficit to an excess at around 4.2 mHz, but averages to zero over all modes. The frequency difference in nearby regions increases with increasing frequency until a point at which the frequency shifts turn over sharply, as in active regions. However, this turnover occurs around 4.9 mHz, which is significantly below the acoustic cutoff frequency. Inverting the horizontal flow parameters in the direction of the neigboring active regions, we find flows that are consistent with a model of the thermal energy flow being blocked directly below the active region.
Time-variant random interval natural frequency analysis of structures
Wu, Binhua; Wu, Di; Gao, Wei; Song, Chongmin
2018-02-01
This paper presents a new robust method namely, unified interval Chebyshev-based random perturbation method, to tackle hybrid random interval structural natural frequency problem. In the proposed approach, random perturbation method is implemented to furnish the statistical features (i.e., mean and standard deviation) and Chebyshev surrogate model strategy is incorporated to formulate the statistical information of natural frequency with regards to the interval inputs. The comprehensive analysis framework combines the superiority of both methods in a way that computational cost is dramatically reduced. This presented method is thus capable of investigating the day-to-day based time-variant natural frequency of structures accurately and efficiently under concrete intrinsic creep effect with probabilistic and interval uncertain variables. The extreme bounds of the mean and standard deviation of natural frequency are captured through the embedded optimization strategy within the analysis procedure. Three particularly motivated numerical examples with progressive relationship in perspective of both structure type and uncertainty variables are demonstrated to justify the computational applicability, accuracy and efficiency of the proposed method.
Multifractal detrended fluctuation analysis of analog random multiplicative processes
Energy Technology Data Exchange (ETDEWEB)
Silva, L.B.M.; Vermelho, M.V.D. [Instituto de Fisica, Universidade Federal de Alagoas, Maceio - AL, 57072-970 (Brazil); Lyra, M.L. [Instituto de Fisica, Universidade Federal de Alagoas, Maceio - AL, 57072-970 (Brazil)], E-mail: marcelo@if.ufal.br; Viswanathan, G.M. [Instituto de Fisica, Universidade Federal de Alagoas, Maceio - AL, 57072-970 (Brazil)
2009-09-15
We investigate non-Gaussian statistical properties of stationary stochastic signals generated by an analog circuit that simulates a random multiplicative process with weak additive noise. The random noises are originated by thermal shot noise and avalanche processes, while the multiplicative process is generated by a fully analog circuit. The resulting signal describes stochastic time series of current interest in several areas such as turbulence, finance, biology and environment, which exhibit power-law distributions. Specifically, we study the correlation properties of the signal by employing a detrended fluctuation analysis and explore its multifractal nature. The singularity spectrum is obtained and analyzed as a function of the control circuit parameter that tunes the asymptotic power-law form of the probability distribution function.
Numerical analysis of quasiperiodic perturbations for the Alfven wave
International Nuclear Information System (INIS)
Yamakoshi, Y.; Muto, K.; Yoshida, Z.
1994-01-01
The Alfven wave may have a localized eigenfunction when it propagates on a chaotic magnetic field. The Arnold-Beltrami-Childress (ABC) flow is a paradigm of chaotic stream lines and is a simple exact solution to the three-dimensional force-free plasma equilibrium equations. The three-dimensional structure of the magnetic field is represented by sinusoidal quasiperiodic modulation. The short wavelength Alfven wave equation for the ABC-flow magnetic field has a quasiperiodic potential term, which induces interference among ''Bragg-reflected'' waves with irregular phases. Then the eigenfunction decays at long distance and a point spectrum occurs. Two different types of short wavelength modes have numerically analyzed to demonstrate the existence of localized Alfven wave eigenmodes
Wavelet analysis of interfacial waves in cocurrent two-phase flow in horizontal duct
International Nuclear Information System (INIS)
Kondo, Masaya; Kukita, Yutaka
1996-07-01
Wavelet analysis was applied to spatially-growing interfacial waves in a cocurrent gas/liquid two-phase flow. The wave growth plays a key role in the transition from stratified-wavy to slug flow, which is an important phenomena in many engineering applications. Of particular interest to the present study was the quick growth or decay of particular waves which were observed in experiments together with the general growth of waves with distance in the flow direction. Among the several wavelet functions tested in the present study, the Morlet wavelet and the Gabor function were found to have spectral and spatial resolutions suitable to the analysis of interfacial wave data taken by the authors. The analysis revealed that 1) the spectral components composing the interfacial waves are propagating at different phase velocities which agree to the theoretical velocities of deep-water waves, 2) the group velocity of the waves also agrees to the deep-water theory, and 3) the quick growth and decay of particular waves occur as a result of the superposition of spectral components with different phase velocities. (author)
Performance analysis of an acoustic time reversal system in dynamic and random oceanic environments
Khosla, Sunny Rajendra
This dissertation provides a theoretical framework along with specific performance predictions for an acoustic time reversal system in shallow oceanic environments. Acoustic time-reversal is a robust means of retrofocusing acoustic energy, in both time and space, to the original sound-source location without any information about the acoustic environment in which it is deployed. The effect of three performance limiting oceanic complexities addressed, include (i)ambient noise field, (ii)reflection and volume scattering from a deterministic soliton internal wave traveling on the thermocline between two water masses, and (iii)volume scattering from a random superposition of linear internal waves convecting a gradient in the sound speed profile. The performance analysis establishes acoustic time reversal to be a promising technology for a two-way communication system in an oceanic medium. For an omni-directional noisy environment a general formulation for the probability of retrofocusing is developed that includes the effect of the medium, accounts for the system hardware and the acoustic parameters. Monte-Carlo simulations in both, a free-space environment and a shallow-ocean sound-channel environment compare well with theory. A 41 element TRA spanning a shallow water depth of 60 m is predicted to return a 70% focal probability at -15 dB SNR for a source to array range of 6 km. Preliminary research with broadband signals suggest that they should outperform narrowband response in both free space and sound channel environments. The impact of the nonlinear solitary waves is addressed using a two-path Green's function to treat the presence of a flat thermocline, and the single scattering Born approximation to address scattering from the soliton internal wave. It is predicted that a stationary soliton located along ray turning paths between the source and the TRA can lead to both enhanced and degraded focal performance. Based on extension of previous research in wave
International Nuclear Information System (INIS)
Chou, C-P; Lee, T K; Ho, C-M
2009-01-01
We examine the strong correlation effects of the d-wave superconducting state by including the Gutzwiller projection for no electron double occupancy at each lattice site. The spectral weights (SW's) for adding and removing an electron on the projected superconducting state, the ground state of the 2-dimensional t-t'-t - J model with moderate doped holes describing the high T c cuprates, are studied numerically on finite lattices and compared with the observation made by low-temperature tunneling (particle asymmetry of tunneling conductance) and angle-resolved photoemission (SW transfer from the projected Fermi liquid state) spectroscopies. The contrast with the d-wave case without projection is alo presented.
Pseudo-Random Modulation of a Laser Diode for Generating Ultrasonic Longitudinal Waves
Madaras, Eric I.; Anatasi, Robert F.
2004-01-01
Laser generated ultrasound systems have historically been more complicated and expensive than conventional piezoelectric based systems, and this fact has relegated the acceptance of laser based systems to niche applications for which piezoelectric based systems are less suitable. Lowering system costs, while improving throughput, increasing ultrasound signal levels, and improving signal-to-noise are goals which will help increase the general acceptance of laser based ultrasound. One current limitation with conventional laser generated ultrasound is a material s damage threshold limit. Increasing the optical power to generate more signal eventually damages the material being tested due to rapid, high heating. Generation limitations for laser based ultrasound suggests the use of pulse modulation techniques as an alternate generation method. Pulse modulation techniques can spread the laser energy over time or space, thus reducing laser power densities and minimizing damage. Previous experiments by various organizations using spatial or temporal pulse modulation have been shown to generate detectable surface, plate, and bulk ultrasonic waves with narrow frequency bandwidths . Using narrow frequency bandwidths improved signal detectability, but required the use of expensive and powerful lasers and opto-electronic systems. The use of a laser diode to generate ultrasound is attractive because of its low cost, small size, light weight, simple optics and modulation capability. The use of pulse compression techniques should allow certain types of laser diodes to produce usable ultrasonic signals. The method also does not need to be limited to narrow frequency bandwidths. The method demonstrated here uses a low power laser diode (approximately 150 mW) that is modulated by controlling the diode s drive current and the resulting signal is recovered by cross correlation. A potential application for this system which is briefly demonstrated is in detecting signals in thick
PLAISIER, PW; BERGER, MY; VANDERHUL, RL; NIJS, HGT; DENTOOM, R; TERPSTRA, OT; BRUINING, HA
1994-01-01
Shortly after extracorporeal shock wave lithotripsy (ESWL) was introduced as a promising new treatment modality for gallstone disease, a randomized controlled study was performed to assess the cost-effectiveness of ESWL compared to open cholecystectomy, the gold standard. During the performance of
Shao, Meng; Xiao, Chengsi; Sun, Jinwei; Shao, Zhuxiao; Zheng, Qiuhong
2017-12-01
The paper analyzes hydrodynamic characteristics and the strength of a novel dot-matrix oscillating wave energy converter, which is in accordance with nowadays’ research tendency: high power, high efficiency, high reliability and low cost. Based on three-dimensional potential flow theory, the paper establishes motion control equations of the wave energy converter unit and calculates wave loads and motions. On this basis, a three-dimensional finite element model of the device is built to check its strength. Through the analysis, it can be confirmed that the WEC is feasible and the research results could be a reference for wave energy’s exploration and utilization.
Chang, Shi-Shing; Wu, John H.
1993-09-01
After the 2th world war, although the application of ultrasonic wave in industries is becoming more and more popular. But due to the restriction of the precise equivelent , experimental method and the support of the basic theoremsetc. Ultrasonic wave is not applied in precise measurement. Nowadays due to many conditions - the improvement in the production technic, the precise of the equivelent, causes to increase the application of ultrasonic wave. But it's still limited due to the lack of measurement and analysis theorem. In this paper, first we caculate translation of the stress wave (elastic wave) in material for the free surface of material by a normal impulse load. as the theorem analysis base in real application. It is applied to an experiment of film measurement. We can find the partical motion in material and the arriving time of wave front. Then we can estimate the thickness of layers and can prove the actual condition with the result of experiment. This resarch is not only in the theoretical investigation but also in setting overall the measurement system, and excutes the following three experiments: the thickness measurement of two layers, the thickness measurement of film material. the thickness measurement of air propagation. About the data processing, we relied on the frequency analysis to evalute the time difference of two overlapped ultrasonic wave signal. in the meanwhile. we also designed several computer programs to assist the sonic wave identification and signal analysis.
A comparative analysis of heat waves and associated mortality in St. Louis, Missouri--1980 and 1995.
Smoyer, K E
1998-08-01
This research investigates heat-related mortality during the 1980 and 1995 heat waves in St. Louis, Missouri. St. Louis has a long history of extreme summer weather, and heat-related mortality is a public health concern. Heat waves are defined as days with apparent temperatures exceeding 40.6 degrees C (105 degrees F). The study uses a multivariate analysis to investigate the relationship between mortality and heat wave intensity, duration, and timing within the summer season. The heat wave of 1980 was more severe and had higher associated mortality than that of 1995. To learn if changing population characteristics, in addition to weather conditions, contributed to this difference, changes in population vulnerability between 1980 and 1995 are evaluated under simulated heat wave conditions. The findings show that St. Louis remains at risk of heat wave mortality. In addition, there is evidence that vulnerability has increased despite increased air-conditioning penetration and public health interventions.
Statistical analysis of monochromatic whistler waves near the Moon detected by Kaguya
Directory of Open Access Journals (Sweden)
Y. Tsugawa
2011-05-01
Full Text Available Observations are presented of monochromatic whistler waves near the Moon detected by the Lunar Magnetometer (LMAG on board Kaguya. The waves were observed as narrowband magnetic fluctuations with frequencies close to 1 Hz, and were mostly left-hand polarized in the spacecraft frame. We performed a statistical analysis of the waves to identify the distributions of their intensity and occurrence. The results indicate that the waves were generated by the solar wind interaction with lunar crustal magnetic anomalies. The conditions for observation of the waves strongly depend on the solar zenith angle (SZA, and a high occurrence rate is recognized in the region of SZA between 40° to 90° with remarkable north-south and dawn-dusk asymmetries. We suggest that ion beams reflected by the lunar magnetic anomalies are a possible source of the waves.
Inclusion of Structural Flexibility in Design Load Analysis for Wave Energy Converters: Preprint
Energy Technology Data Exchange (ETDEWEB)
Guo, Yi [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yu, Yi-Hsiang [National Renewable Energy Laboratory (NREL), Golden, CO (United States); van Rij, Jennifer A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tom, Nathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
2017-08-14
Hydroelastic interactions, caused by ocean wave loading on wave energy devices with deformable structures, are studied in the time domain. A midfidelity, hybrid modeling approach of rigid-body and flexible-body dynamics is developed and implemented in an open-source simulation tool for wave energy converters (WEC-Sim) to simulate the dynamic responses of wave energy converter component structural deformations under wave loading. A generalized coordinate system, including degrees of freedom associated with rigid bodies, structural modes, and constraints connecting multiple bodies, is utilized. A simplified method of calculating stress loads and sectional bending moments is implemented, with the purpose of sizing and designing wave energy converters. Results calculated using the method presented are verified with those of high-fidelity fluid-structure interaction simulations, as well as low-fidelity, frequency-domain, boundary element method analysis.
Wave energy resource of Brazil: An analysis from 35 years of ERA-Interim reanalysis data
Araújo, Alex Maurício
2017-01-01
This paper presents a characterization of the wave power resource and an analysis of the wave power output for three (AquaBuoy, Pelamis and Wave Dragon) different wave energy converters (WEC) over the Brazilian offshore. To do so it used a 35 years reanalysis database from the ERA-Interim project. Annual and seasonal statistical analyzes of significant height and energy period were performed, and the directional variability of the incident waves were evaluated. The wave power resource was characterized in terms of the statistical parameters of mean, maximum, 95th percentile and standard deviation, and in terms of the temporal variability coefficients COV, SV e MV. From these analyses, the total annual wave power resource available over the Brazilian offshore was estimated in 89.97 GW, with largest mean wave power of 20.63 kW/m in the southernmost part of the study area. The analysis of the three WEC was based in the annual wave energy output and in the capacity factor. The higher capacity factor was 21.85% for Pelamis device at the southern region of the study area. PMID:28817731
Wave energy resource of Brazil: An analysis from 35 years of ERA-Interim reanalysis data.
Espindola, Rafael Luz; Araújo, Alex Maurício
2017-01-01
This paper presents a characterization of the wave power resource and an analysis of the wave power output for three (AquaBuoy, Pelamis and Wave Dragon) different wave energy converters (WEC) over the Brazilian offshore. To do so it used a 35 years reanalysis database from the ERA-Interim project. Annual and seasonal statistical analyzes of significant height and energy period were performed, and the directional variability of the incident waves were evaluated. The wave power resource was characterized in terms of the statistical parameters of mean, maximum, 95th percentile and standard deviation, and in terms of the temporal variability coefficients COV, SV e MV. From these analyses, the total annual wave power resource available over the Brazilian offshore was estimated in 89.97 GW, with largest mean wave power of 20.63 kW/m in the southernmost part of the study area. The analysis of the three WEC was based in the annual wave energy output and in the capacity factor. The higher capacity factor was 21.85% for Pelamis device at the southern region of the study area.
Wave energy resource of Brazil: An analysis from 35 years of ERA-Interim reanalysis data.
Directory of Open Access Journals (Sweden)
Rafael Luz Espindola
Full Text Available This paper presents a characterization of the wave power resource and an analysis of the wave power output for three (AquaBuoy, Pelamis and Wave Dragon different wave energy converters (WEC over the Brazilian offshore. To do so it used a 35 years reanalysis database from the ERA-Interim project. Annual and seasonal statistical analyzes of significant height and energy period were performed, and the directional variability of the incident waves were evaluated. The wave power resource was characterized in terms of the statistical parameters of mean, maximum, 95th percentile and standard deviation, and in terms of the temporal variability coefficients COV, SV e MV. From these analyses, the total annual wave power resource available over the Brazilian offshore was estimated in 89.97 GW, with largest mean wave power of 20.63 kW/m in the southernmost part of the study area. The analysis of the three WEC was based in the annual wave energy output and in the capacity factor. The higher capacity factor was 21.85% for Pelamis device at the southern region of the study area.
Kim, Jeong-Man; Koo, Min-Mo; Jeong, Jae-Hoon; Hong, Keyyong; Cho, Il-Hyoung; Choi, Jang-Young
2017-05-01
This paper reports the design and analysis of a tubular permanent magnet linear generator (TPMLG) for a small-scale wave-energy converter. The analytical field computation is performed by applying a magnetic vector potential and a 2-D analytical model to determine design parameters. Based on analytical solutions, parametric analysis is performed to meet the design specifications of a wave-energy converter (WEC). Then, 2-D FEA is employed to validate the analytical method. Finally, the experimental result confirms the predictions of the analytical and finite element analysis (FEA) methods under regular and irregular wave conditions.
Hamiltonian analysis of fast wave current drive in tokamak plasmas
Energy Technology Data Exchange (ETDEWEB)
Becoulet, A; Fraboulet, D; Giruzzi, G; Moreau, D; Saoutic, B [Association Euratom-CEA, Centre d` Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Chinardet, J [CISI Ingenierie, Centre d` Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France)
1993-12-01
The Hamiltonian formalism is used to analyze the direct resonant interaction between the fast magnetosonic wave and the electrons in a tokamak plasma. The intrinsic stochasticity of the electron phase space trajectories is derived, and together with extrinsic de-correlation processes, assesses the validity of the quasilinear approximation for the kinetic studies of fast wave current drive (FWCD). A full-wave resolution of the Maxwell-Vlasov set of equations provides the exact pattern of the wave fields in a complete tokamak geometry, for a realistic antenna spectrum. The local quasilinear diffusion tensor is derived from the wave fields, and is used for a computation of the driven current and deposited power profiles, the current drive efficiency, including possible non-linear effects in the kinetic equation. Several applications of FWCD on existing and future machines are given, as well as results concerning combination of FWCD with other non inductive current drive methods. An analytical expression for the current drive efficiency is given in the high single-pass absorption regimes. (authors). 20 figs., 1 tab., 26 refs.
Hamiltonian analysis of fast wave current drive in tokamak plasmas
International Nuclear Information System (INIS)
Becoulet, A.; Fraboulet, D.; Giruzzi, G.; Moreau, D.; Saoutic, B.
1993-12-01
The Hamiltonian formalism is used to analyze the direct resonant interaction between the fast magnetosonic wave and the electrons in a tokamak plasma. The intrinsic stochasticity of the electron phase space trajectories is derived, and together with extrinsic de-correlation processes, assesses the validity of the quasilinear approximation for the kinetic studies of fast wave current drive (FWCD). A full-wave resolution of the Maxwell-Vlasov set of equations provides the exact pattern of the wave fields in a complete tokamak geometry, for a realistic antenna spectrum. The local quasilinear diffusion tensor is derived from the wave fields, and is used for a computation of the driven current and deposited power profiles, the current drive efficiency, including possible non-linear effects in the kinetic equation. Several applications of FWCD on existing and future machines are given, as well as results concerning combination of FWCD with other non inductive current drive methods. An analytical expression for the current drive efficiency is given in the high single-pass absorption regimes. (authors). 20 figs., 1 tab., 26 refs
Urban Heat Wave Vulnerability Analysis Considering Climate Change
JE, M.; KIM, H.; Jung, S.
2017-12-01
Much attention has been paid to thermal environments in Seoul City in South Korea since 2016 when the worst heatwave in 22 years. It is necessary to provide a selective measure by singling out vulnerable regions in advance to cope with the heat wave-related damage. This study aims to analyze and categorize vulnerable regions of thermal environments in the Seoul and analyzes and discusses the factors and risk factors for each type. To do this, this study conducted the following processes: first, based on the analyzed various literature reviews, indices that can evaluate vulnerable regions of thermal environment are collated. The indices were divided into climate exposure index related to temperature, sensitivity index including demographic, social, and economic indices, and adaptation index related to urban environment and climate adaptation policy status. Second, significant variables were derived to evaluate a vulnerable region of thermal environment based on the summarized indices in the above. this study analyzed a relationship between the number of heat-related patients in Seoul and variables that affected the number using multi-variate statistical analysis to derive significant variables. Third, the importance of each variable was calculated quantitatively by integrating the statistical analysis results and analytic hierarchy process (AHP) method. Fourth, a distribution of data for each index was identified based on the selected variables and indices were normalized and overlapped. Fifth, For the climate exposure index, evaluations were conducted as same as the current vulnerability evaluation method by selecting future temperature of Seoul predicted through the representative concentration pathways (RCPs) climate change scenarios as an evaluation variable. The results of this study can be utilized as foundational data to establish a countermeasure against heatwave in Seoul. Although it is limited to control heatwave occurrences itself completely, improvements
Hydrodynamic analysis and shape optimization for vertical axisymmetric wave energy converters
Zhang, Wan-chao; Liu, Heng-xu; Zhang, Liang; Zhang, Xue-wei
2016-12-01
The absorber is known to be vertical axisymmetric for a single-point wave energy converter (WEC). The shape of the wetted surface usually has a great influence on the absorber's hydrodynamic characteristics which are closely linked with the wave power conversion ability. For complex wetted surface, the hydrodynamic coefficients have been predicted traditionally by hydrodynamic software based on the BEM. However, for a systematic study of various parameters and geometries, they are too multifarious to generate so many models and data grids. This paper examines a semi-analytical method of decomposing the complex axisymmetric boundary into several ring-shaped and stepped surfaces based on the boundary discretization method (BDM) which overcomes the previous difficulties. In such case, by using the linear wave theory based on eigenfunction expansion matching method, the expressions of velocity potential in each domain, the added mass, radiation damping and wave excitation forces of the oscillating absorbers are obtained. The good astringency of the hydrodynamic coefficients and wave forces are obtained for various geometries when the discrete number reaches a certain value. The captured wave power for a same given draught and displacement for various geometries are calculated and compared. Numerical results show that the geometrical shape has great effect on the wave conversion performance of the absorber. For absorbers with the same outer radius and draught or displacement, the cylindrical type shows fantastic wave energy conversion ability at some given frequencies, while in the random sea wave, the parabolic and conical ones have better stabilization and applicability in wave power conversion.
The Effects of Random and Nonlinear Waves on Coastal and Offshore Structures
1987-07-01
Barik and Paramasivam [2]. Dao and Penzien [3]. Leonard, et al. (4). and Tuali and Hudspeth [8). For a real sea state, the super- position of linear...34 Ocean Engng., Vol. 10, No. 5, 1983, p 303 312. [2] Barik , K. C. and V. Paramasivam, "Response Analysis of Offehore Struc- tures," J. Waterways Port
T-wave morphology analysis of competitive athletes
DEFF Research Database (Denmark)
Hong, L; Andersen, Lars Juel; Graff, Claus
2015-01-01
BACKGROUND: T-wave morphology has been shown to be more sensitive than QT and QTc interval to describe repolarization abnormalities. The electrocardiogram (ECG) performed in athletes may manifest abnormalities, including repolarization alterations. The aim of this study was to investigate...... the characteristics of T-wave morphology features in athletes. METHODS: Eighty male elite athletes, consisting of 40 Tour de France cyclists (age 27±5years), 40 soccer players (age 26±6years) and 40 healthy men (age 27±5years) were included. RESULTS: Sinus bradycardia, left ventricular (LV) hypertrophy, incomplete...... interval, and repolarization features than the control group. CONCLUSIONS: T-wave morphology of athletes is different from non-athletes, depending of the sport. Decreased potassium current in cardiomyocytes associated with LVH may contribute to these changes....
2005-03-01
picture at 22/00Z.............50 x Figure 24. Case 5 – wave parameters........................51 Figure 25. Evolution of energy density (arrow...equation or energy balance equation: . in nl ds F v F S S S S t ∂ + ∇ = ≡ + + ∂ r (1) where ( , ; , )F f x tθ r is the two dimensional...collected from an offshore directional Seawatch buoy, in the vicinity of Cape Silleiro, Rayo Silleiro 19 (“E1”), (Figure 3), was provided by the
Wang, Guan-Jie; Liu, Jia
2012-07-01
To explore the effect of application of ultrashort wave and magnetic therapy instrument on the swelling regression in distal radius fractures treated by splint external fixation in initial stage. From March 2007 to May 2010,90 patients with distal radial fracture were treated by manual reduction and splint external fixation. After manual reduction and small splints external fixation, these patients were randomly divided into electrical physical therapy group, western medicine group and the control group by the order of calling number, with 30 cases each group. In control group, there were 9 males and 21 females with an average age of (61.29 +/- 1.97) years, the patients raised and exercise the limb and fingers only. The other two groups also carried out this treatment. In electrical physical therapy group, there were 9 males and 21 females with an average age of (62.37 +/- 2.48) years, the patients were treated with ultrashort wave and magnetic therapy instrument for early intervention, once a day, 5 days for a course of treatment and three cycle were operated. In western medicine group,there were 8 males and 22 females with an average age of (60.12 +/- 2.87) years, the patients were injected with beta-aescin (20 mg, intravenous injection,once a day) for 5 days, followed by Danshen injection (20 ml, intravenous injection, once a day) for 10 days. The limb swelling of patients were assessed every day for 20 days after manual reduction and small splints external fixation. The time of swelling regression in electrical physical therapy group, western medicine group and the control group were respectively (9.62 +/- 3.32), (10.05 +/- 3.05) and (14.57 +/- 2.93) days. Both of that in electrical physical therapy group and western medicine group were shorter than that in the control group (P0.05). The effective rate of swelling regression in electrical physical therapy group, western medicine group and the control group were 86.67%, 80.00%, 46.66% respectively. There was no
Statistical analysis of s-wave neutron reduced widths
International Nuclear Information System (INIS)
Pandita Anita; Agrawal, H.M.
1992-01-01
The fluctuations of the s-wave neutron reduced widths for many nuclei have been analyzed with emphasis on recent measurements by a statistical procedure which is based on the method of maximum likelihood. It is shown that the s-wave neutron reduced widths of nuclei follow single channel Porter Thomas distribution (x 2 -distribution with degree of freedom ν = 1) for most of the cases. However there are apparent deviations from ν = 1 and possible explanation and significance of this deviation is given. These considerations are likely to modify the evaluation of neutron cross section. (author)
Wavelet Transform Based Higher Order Statistical Analysis of Wind and Wave Time Histories
Habib Huseni, Gulamhusenwala; Balaji, Ramakrishnan
2017-10-01
Wind, blowing on the surface of the ocean, imparts the energy to generate the waves. Understanding the wind-wave interactions is essential for an oceanographer. This study involves higher order spectral analyses of wind speeds and significant wave height time histories, extracted from European Centre for Medium-Range Weather Forecast database at an offshore location off Mumbai coast, through continuous wavelet transform. The time histories were divided by the seasons; pre-monsoon, monsoon, post-monsoon and winter and the analysis were carried out to the individual data sets, to assess the effect of various seasons on the wind-wave interactions. The analysis revealed that the frequency coupling of wind speeds and wave heights of various seasons. The details of data, analysing technique and results are presented in this paper.
Fuzzy Random Walkers with Second Order Bounds: An Asymmetric Analysis
Directory of Open Access Journals (Sweden)
Georgios Drakopoulos
2017-03-01
Full Text Available Edge-fuzzy graphs constitute an essential modeling paradigm across a broad spectrum of domains ranging from artificial intelligence to computational neuroscience and social network analysis. Under this model, fundamental graph properties such as edge length and graph diameter become stochastic and as such they are consequently expressed in probabilistic terms. Thus, algorithms for fuzzy graph analysis must rely on non-deterministic design principles. One such principle is Random Walker, which is based on a virtual entity and selects either edges or, like in this case, vertices of a fuzzy graph to visit. This allows the estimation of global graph properties through a long sequence of local decisions, making it a viable strategy candidate for graph processing software relying on native graph databases such as Neo4j. As a concrete example, Chebyshev Walktrap, a heuristic fuzzy community discovery algorithm relying on second order statistics and on the teleportation of the Random Walker, is proposed and its performance, expressed in terms of community coherence and number of vertex visits, is compared to the previously proposed algorithms of Markov Walktrap, Fuzzy Walktrap, and Fuzzy Newman–Girvan. In order to facilitate this comparison, a metric based on the asymmetric metrics of Tversky index and Kullback–Leibler divergence is used.
Key-space analysis of double random phase encryption technique
Monaghan, David S.; Gopinathan, Unnikrishnan; Naughton, Thomas J.; Sheridan, John T.
2007-09-01
We perform a numerical analysis on the double random phase encryption/decryption technique. The key-space of an encryption technique is the set of possible keys that can be used to encode data using that technique. In the case of a strong encryption scheme, many keys must be tried in any brute-force attack on that technique. Traditionally, designers of optical image encryption systems demonstrate only how a small number of arbitrary keys cannot decrypt a chosen encrypted image in their system. However, this type of demonstration does not discuss the properties of the key-space nor refute the feasibility of an efficient brute-force attack. To clarify these issues we present a key-space analysis of the technique. For a range of problem instances we plot the distribution of decryption errors in the key-space indicating the lack of feasibility of a simple brute-force attack.
Generation and Analysis of Constrained Random Sampling Patterns
DEFF Research Database (Denmark)
Pierzchlewski, Jacek; Arildsen, Thomas
2016-01-01
Random sampling is a technique for signal acquisition which is gaining popularity in practical signal processing systems. Nowadays, event-driven analog-to-digital converters make random sampling feasible in practical applications. A process of random sampling is defined by a sampling pattern, which...... indicates signal sampling points in time. Practical random sampling patterns are constrained by ADC characteristics and application requirements. In this paper, we introduce statistical methods which evaluate random sampling pattern generators with emphasis on practical applications. Furthermore, we propose...... algorithm generates random sampling patterns dedicated for event-driven-ADCs better than existed sampling pattern generators. Finally, implementation issues of random sampling patterns are discussed....
Analysis of human skin tissue by millimeter-wave reflectometry
Smulders, P.F.M.
2013-01-01
Background/pupose: Millimeter-wave reflectometry is a potentially interesting technique to analyze the human skin in vivo in order to determine the water content locally in the skin. Purpose of this work is to investigate the possibility of skin-tissue differentiation. In addition, it addresses the
Analysis of flexural wave propagation in poroelastic composite ...
African Journals Online (AJOL)
DR OKE
dimensional solution for free vibration problem of homogeneous isotropic cylindrical ... Abousleiman and Cui (1998) presented poroelastic solutions in an inclined ...... The Biot-willis elastic coefficients for a sandstone, Journal of Applied Mechanics, Vol. ... Study of wave motions in fluid-saturated porous rocks, Journal of the ...
Distribution analysis of segmented wave sea clutter in littoral environments
CSIR Research Space (South Africa)
Strempel, MD
2015-10-01
Full Text Available are then fitted against the K-distribution. It is shown that the approach can accurately describe specific sections of the wave with a reduced error between actual and estimated distributions. The improved probability density function (PDF) representation...
Analysis of Wave Fields induced by Offshore Pile Driving
Ruhnau, M.; Heitmann, K.; Lippert, T.; Lippert, S.; von Estorff, O.
2015-12-01
Impact pile driving is the common technique to install foundations for offshore wind turbines. With each hammer strike the steel pile - often exceeding 6 m in diameter and 80 m in length - radiates energy into the surrounding water and soil, until reaching its targeted penetration depth. Several European authorities introduced limitations regarding hydroacoustic emissions during the construction process to protect marine wildlife. Satisfying these regulations made the development and application of sound mitigation systems (e.g. bubble curtains or insulation screens) inevitable, which are commonly installed within the water column surrounding the pile or even the complete construction site. Last years' advances have led to a point, where the seismic energy tunneling the sound mitigation systems through the soil and radiating back towards the water column gains importance, as it confines the maximum achievable sound mitigation. From an engineering point of view, the challenge of deciding on an effective noise mitigation layout arises, which especially requires a good understanding of the soil-dependent wave field. From a geophysical point of view, the pile acts like a very unique line source, generating a characteristic wave field dominated by inclined wave fronts, diving as well as head waves. Monitoring the seismic arrivals while the pile penetration steadily increases enables to perform quasi-vertical seismic profiling. This work is based on datasets that have been collected within the frame of three comprehensive offshore measurement campaigns during pile driving and demonstrates the potential of seismic arrivals induced by pile driving for further soil characterization.
Angle-domain Migration Velocity Analysis using Wave-equation Reflection Traveltime Inversion
Zhang, Sanzong; Schuster, Gerard T.; Luo, Yi
2012-01-01
way as wave-equation transmission traveltime inversion. The residual movemout analysis in the angle-domain common image gathers provides a robust estimate of the depth residual which is converted to the reflection traveltime residual for the velocity
Structural Modeling and Analysis of a Wave Energy Converter Applying Dynamical Substructuring Method
DEFF Research Database (Denmark)
Zurkinden, Andrew Stephen; Damkilde, Lars; Gao, Zhen
2013-01-01
to the relative stiff behavior of the arm the calculation can be reduced to a quasi-static analysis. The hydrodynamic and the structural analyses are thus performed separately. In order to reduce the computational time of the finite element calculation the main structure is modeled as a superelement......This paper deals with structural modeling and analysis of a wave energy converter. The device, called Wavestar, is a bottom fixed structure, located in a shallow water environment at the Danish Northwest coast. The analysis is concentrated on a single float and its structural arm which connects...... the WEC to a jackup structure. The wave energy converter is characterized by having an operational and survival mode. The survival mode drastically reduces the exposure to waves and therfore to the wave loads. Structural response analysis of the Wavestar arm is carried out in this study. Due...
Origin and Structure of Nearshore Internal Tides and Waves: Data Analysis and Linear Theory
National Research Council Canada - National Science Library
Hendershott, Myrl
2001-01-01
Analysis of the data set obtained during the 1996-97 summer and autumn deployments of ADCP and T-logger internal wave antennas of Mission Beach, CA, was the principle activity during the reporting period...
Spectro-spatial analysis of wave packet propagation in nonlinear acoustic metamaterials
Zhou, W. J.; Li, X. P.; Wang, Y. S.; Chen, W. Q.; Huang, G. L.
2018-01-01
The objective of this work is to analyze wave packet propagation in weakly nonlinear acoustic metamaterials and reveal the interior nonlinear wave mechanism through spectro-spatial analysis. The spectro-spatial analysis is based on full-scale transient analysis of the finite system, by which dispersion curves are generated from the transmitted waves and also verified by the perturbation method (the L-P method). We found that the spectro-spatial analysis can provide detailed information about the solitary wave in short-wavelength region which cannot be captured by the L-P method. It is also found that the optical wave modes in the nonlinear metamaterial are sensitive to the parameters of the nonlinear constitutive relation. Specifically, a significant frequency shift phenomenon is found in the middle-wavelength region of the optical wave branch, which makes this frequency region behave like a band gap for transient waves. This special frequency shift is then used to design a direction-biased waveguide device, and its efficiency is shown by numerical simulations.
Two-Dimensional Analysis of Cable Stayed Bridge under Wave Loading
Seeram, Madhuri; Manohar, Y.
2018-06-01
In the present study finite element analysis is performed for a modified fan type cable-stayed bridge using ANSYS Mechanical. A cable stayed bridge with two towers and main deck is considered for the present study. Dynamic analysis is performed to evaluate natural frequencies. The obtained natural frequencies and mode shapes of cable stayed bridge are compared to the existing results. Further studies have been conducted for offshore area application by increasing the pylon/tower height depending upon the water depth. Natural frequencies and mode shapes are evaluated for the cable stayed bridge for offshore area application. The results indicate that the natural periods are higher than the existing results due to the effect of increase in mass of the structure and decrease in stiffness of the pylon/tower. The cable stayed bridge is analyzed under various environmental loads such as dead, live, vehicle, seismic and wave loading. Morison equation is considered to evaluate the wave force. The sum of inertia and drag force is taken as the wave force distribution along the fluid interacting height of the pylon. Airy's wave theory is used to assess water particle kinematics, for the wave periods ranging from 5 to 20 s and unit wave height. The maximum wave force among the different regular waves is considered in the wave load case. The support reactions, moments and deflections for offshore area application are highlighted. It is observed that the maximum support reactions and support moments are obtained due to wave and earthquake loading respectively. Hence, it is concluded that the wave and earthquake forces shall be given significance in the design of cable stayed bridge.
Aeroacoustic directivity via wave-packet analysis of mean or base flows
Edstrand, Adam; Schmid, Peter; Cattafesta, Louis
2017-11-01
Noise pollution is an ever-increasing problem in society, and knowledge of the directivity patterns of the sound radiation is required for prediction and control. Directivity is frequently determined through costly numerical simulations of the flow field combined with an acoustic analogy. We introduce a new computationally efficient method of finding directivity for a given mean or base flow field using wave-packet analysis (Trefethen, PRSA 2005). Wave-packet analysis approximates the eigenvalue spectrum with spectral accuracy by modeling the eigenfunctions as wave packets. With the wave packets determined, we then follow the method of Obrist (JFM, 2009), which uses Lighthill's acoustic analogy to determine the far-field sound radiation and directivity of wave-packet modes. We apply this method to a canonical jet flow (Gudmundsson and Colonius, JFM 2011) and determine the directivity of potentially unstable wave packets. Furthermore, we generalize the method to consider a three-dimensional flow field of a trailing vortex wake. In summary, we approximate the disturbances as wave packets and extract the directivity from the wave-packet approximation in a fraction of the time of standard aeroacoustic solvers. ONR Grant N00014-15-1-2403.
Statistical analysis of P-wave neutron reduced widths
International Nuclear Information System (INIS)
Joshi, G.C.; Agrawal, H.M.
2000-01-01
The fluctuations of the p-wave neutron reduced widths for fifty one nuclei have been analyzed with emphasis on recent measurements by a statistical procedure which is based on the method of maximum likelihood. It is shown that the p-wave neutron reduced widths of even-even nuclei fallow single channel Porter Thomas distribution (χ 2 -distribution with degree of freedom ν=1) for most of the cases where there are no intermediate structure. It is emphasized that the distribution in nuclei other than even-even may differ from a χ 2 -distribution with one degree of freedom. Possible explanation and significance of this deviation from ν=1 is given. (author)
Quasilinear analysis of absorption of ion Bernstein waves by electrons
International Nuclear Information System (INIS)
Cardinali, A.; Paoletti, F.; Bernabei, S.; Ono, M.
1995-01-01
The effects induced on plasma electrons by an externally launched ion Bernstein wave (IBW), in the presence of a lower hybrid wave (LHW) in the current drive regime, are studied by analytical integration of the IBW ray-tracing equations along with the amplitude transport equation (Poynting theorem). The electric field amplitude parallel and perpendicular to the external magnetic field, the quasilinear diffusion coefficient, and the modified electron distribution function are analytically calculated in the case of IBW. The analytical calculation is compared to the numerical solution obtained by using a 2-D Fokker-Planck code for the distribution function, without any approximation for the collision operator. The synergy between the IBW and LHW can be accounted for, and the absorption of the IBW power when the electron distribution function presents a tail generated by the LHW in the current drive regime can be calculated
DEFF Research Database (Denmark)
Ilic, C; Chadwick, A; Helm-Petersen, Jacob
2000-01-01
, non-phased locked methods are more appropriate. In this paper, the accuracy of two non-phased locked methods of directional analysis, the maximum likelihood method (MLM) and the Bayesian directional method (BDM) have been quantitatively evaluated using numerical simulations for the case...... of multidirectional waves with partial reflections. It is shown that the results are influenced by the ratio of distance from the reflector (L) to the length of the time series (S) used in the spectral analysis. Both methods are found to be capable of determining the incident and reflective wave fields when US > 0......Recent studies of advanced directional analysis techniques have mainly centred on incident wave fields. In the study of coastal structures, however, partially reflective wave fields are commonly present. In the near structure field, phase locked methods can be successfully applied. In the far field...
Sensitivity of a numerical wave model on wind re-analysis datasets
Lavidas, George; Venugopal, Vengatesan; Friedrich, Daniel
2017-03-01
Wind is the dominant process for wave generation. Detailed evaluation of metocean conditions strengthens our understanding of issues concerning potential offshore applications. However, the scarcity of buoys and high cost of monitoring systems pose a barrier to properly defining offshore conditions. Through use of numerical wave models, metocean conditions can be hindcasted and forecasted providing reliable characterisations. This study reports the sensitivity of wind inputs on a numerical wave model for the Scottish region. Two re-analysis wind datasets with different spatio-temporal characteristics are used, the ERA-Interim Re-Analysis and the CFSR-NCEP Re-Analysis dataset. Different wind products alter results, affecting the accuracy obtained. The scope of this study is to assess different available wind databases and provide information concerning the most appropriate wind dataset for the specific region, based on temporal, spatial and geographic terms for wave modelling and offshore applications. Both wind input datasets delivered results from the numerical wave model with good correlation. Wave results by the 1-h dataset have higher peaks and lower biases, in expense of a high scatter index. On the other hand, the 6-h dataset has lower scatter but higher biases. The study shows how wind dataset affects the numerical wave modelling performance, and that depending on location and study needs, different wind inputs should be considered.
Comparative analysis of winch-based wave energy converters
Nachev, Aleksandar
2017-01-01
Renewable energy sources are probably the future of the mankind. The main points advocating wave energy in particular include its huge potential, low environmental impact and availability around the globe. In order to harvest that energy, however, engineers have to overcome, among others, the corrosive sea environment and the unpredictable storms as well as secure funding for research and development. A lot of effort has been put into building and testing WECs after the oil crisis in the 1970...
Singular value decomposition methods for wave propagation analysis
Czech Academy of Sciences Publication Activity Database
Santolík, Ondřej; Parrot, M.; Lefeuvre, F.
2003-01-01
Roč. 38, č. 1 (2003), s. 10-1-10-13 ISSN 0048-6604 R&D Projects: GA ČR GA205/01/1064 Grant - others:Barrande(CZ) 98039/98055 Institutional research plan: CEZ:AV0Z3042911; CEZ:MSM 113200004 Keywords : wave propagation * singular value decomposition Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.832, year: 2003
Use of offshore mooring platform for sea wave motion analysis
International Nuclear Information System (INIS)
Cicconi, G.; Dagnino, I.; Papa, L.
1979-01-01
An offshore mooring platform for supertankers may often turn out to be an ideal solution for the problem of installing a meteorological station. Its location may be particularly desirable for the purpose of recording and analysing sea wave motion in deep water or in the intermediate zone between shallow and deep water. The preliminary results obtained through the operation of a subsurface sensor at the mooring platform off the harbour of Genova are reported. (author)
Use of offshore mooring platform for sea wave motion analysis
Energy Technology Data Exchange (ETDEWEB)
Cicconi, G.; Dagnino, I.; Papa, L. (Genova Univ. (Italy). Ist. Geofisica e Geodetico); Basano, L.; Ottonello, P. (Genoa Univ. (Italy))
An offshore mooring platform for supertankers may often turn out to be an ideal solution for the problem of installing a meteorological station. Its location may be particularly desirable for the purpose of recording and analysing sea wave motion in deep water or in the intermediate zone between shallow and deep water. The preliminary results obtained through the operation of a subsurface sensor at the mooring platform off the harbour of Genova are reported.
Analysis of Periodic Errors for Synthesized-Reference-Wave Holography
Directory of Open Access Journals (Sweden)
V. Schejbal
2009-12-01
Full Text Available Synthesized-reference-wave holographic techniques offer relatively simple and cost-effective measurement of antenna radiation characteristics and reconstruction of complex aperture fields using near-field intensity-pattern measurement. These methods allow utilization of advantages of methods for probe compensations for amplitude and phasing near-field measurements for the planar and cylindrical scanning including accuracy analyses. The paper analyzes periodic errors, which can be created during scanning, using both theoretical results and numerical simulations.
Zuo, Weiguang; Liu, Ming; Fan, Tianhui; Wang, Pengtao
2018-06-01
This paper presents the probability distribution of the slamming pressure from an experimental study of regular wave slamming on an elastically supported horizontal deck. The time series of the slamming pressure during the wave impact were first obtained through statistical analyses on experimental data. The exceeding probability distribution of the maximum slamming pressure peak and distribution parameters were analyzed, and the results show that the exceeding probability distribution of the maximum slamming pressure peak accords with the three-parameter Weibull distribution. Furthermore, the range and relationships of the distribution parameters were studied. The sum of the location parameter D and the scale parameter L was approximately equal to 1.0, and the exceeding probability was more than 36.79% when the random peak was equal to the sample average during the wave impact. The variation of the distribution parameters and slamming pressure under different model conditions were comprehensively presented, and the parameter values of the Weibull distribution of wave-slamming pressure peaks were different due to different test models. The parameter values were found to decrease due to the increased stiffness of the elastic support. The damage criterion of the structure model caused by the wave impact was initially discussed, and the structure model was destroyed when the average slamming time was greater than a certain value during the duration of the wave impact. The conclusions of the experimental study were then described.
Random vibrations theory and practice
Wirsching, Paul H; Ortiz, Keith
1995-01-01
Random Vibrations: Theory and Practice covers the theory and analysis of mechanical and structural systems undergoing random oscillations due to any number of phenomena— from engine noise, turbulent flow, and acoustic noise to wind, ocean waves, earthquakes, and rough pavement. For systems operating in such environments, a random vibration analysis is essential to the safety and reliability of the system. By far the most comprehensive text available on random vibrations, Random Vibrations: Theory and Practice is designed for readers who are new to the subject as well as those who are familiar with the fundamentals and wish to study a particular topic or use the text as an authoritative reference. It is divided into three major sections: fundamental background, random vibration development and applications to design, and random signal analysis. Introductory chapters cover topics in probability, statistics, and random processes that prepare the reader for the development of the theory of random vibrations a...
Ashraf, M. A. M.; Kumar, N. S.; Yusoh, R.; Hazreek, Z. A. M.; Aziman, M.
2018-04-01
Site classification utilizing average shear wave velocity (Vs(30) up to 30 meters depth is a typical parameter. Numerous geophysical methods have been proposed for estimation of shear wave velocity by utilizing assortment of testing configuration, processing method, and inversion algorithm. Multichannel Analysis of Surface Wave (MASW) method is been rehearsed by numerous specialist and professional to geotechnical engineering for local site characterization and classification. This study aims to determine the site classification on soft and hard ground using MASW method. The subsurface classification was made utilizing National Earthquake Hazards Reduction Program (NERHP) and international Building Code (IBC) classification. Two sites are chosen to acquire the shear wave velocity which is in the state of Pulau Pinang for soft soil and Perlis for hard rock. Results recommend that MASW technique can be utilized to spatially calculate the distribution of shear wave velocity (Vs(30)) in soil and rock to characterize areas.
Analysis of efficient preconditioned defect correction methods for nonlinear water waves
DEFF Research Database (Denmark)
Engsig-Karup, Allan Peter
2014-01-01
Robust computational procedures for the solution of non-hydrostatic, free surface, irrotational and inviscid free-surface water waves in three space dimensions can be based on iterative preconditioned defect correction (PDC) methods. Such methods can be made efficient and scalable to enable...... prediction of free-surface wave transformation and accurate wave kinematics in both deep and shallow waters in large marine areas or for predicting the outcome of experiments in large numerical wave tanks. We revisit the classical governing equations are fully nonlinear and dispersive potential flow...... equations. We present new detailed fundamental analysis using finite-amplitude wave solutions for iterative solvers. We demonstrate that the PDC method in combination with a high-order discretization method enables efficient and scalable solution of the linear system of equations arising in potential flow...
International Nuclear Information System (INIS)
Zhang, Y. S.; Cai, F.; Xu, W. M.
2011-01-01
The ship motion equation with a cosine wave excitement force describes the slip moments in regular waves. A new kind of wave excitement force model, with the form as sums of cosine functions was proposed to describe ship rolling in irregular waves. Ship rolling time series were obtained by solving the ship motion equation with the fourth-order-Runger-Kutta method. These rolling time series were synthetically analyzed with methods of phase-space track, power spectrum, primary component analysis, and the largest Lyapunove exponent. Simulation results show that ship rolling presents some chaotic characteristic when the wave excitement force was applied by sums of cosine functions. The result well explains the course of ship rolling's chaotic mechanism and is useful for ship hydrodynamic study.
Investigation of interfacial wave structure using time-series analysis techniques
International Nuclear Information System (INIS)
Jayanti, S.; Hewitt, G.F.; Cliffe, K.A.
1990-09-01
The report presents an investigation into the interfacial structure in horizontal annular flow using spectral and time-series analysis techniques. Film thickness measured using conductance probes shows an interesting transition in wave pattern from a continuous low-frequency wave pattern to an intermittent, high-frequency one. From the autospectral density function of the film thickness, it appears that this transition is caused by the breaking up of long waves into smaller ones. To investigate the possibility of the wave structure being represented as a low order chaotic system, phase portraits of the time series were constructed using the technique developed by Broomhead and co-workers (1986, 1987 and 1989). These showed a banded structure when waves of relatively high frequency were filtered out. Although these results are encouraging, further work is needed to characterise the attractor. (Author)
Reiss, Miriam Christina; Rümpker, Georg
2017-04-01
We present a semi-automatic, graphical user interface tool for the analysis and interpretation of teleseismic shear-wave splitting in MATLAB. Shear wave splitting analysis is a standard tool to infer seismic anisotropy, which is often interpreted as due to lattice-preferred orientation of e.g. mantle minerals or shape-preferred orientation caused by cracks or alternating layers in the lithosphere and hence provides a direct link to the earth's kinematic processes. The increasing number of permanent stations and temporary experiments result in comprehensive studies of seismic anisotropy world-wide. Their successive comparison with a growing number of global models of mantle flow further advances our understanding the earth's interior. However, increasingly large data sets pose the inevitable question as to how to process them. Well-established routines and programs are accurate but often slow and impractical for analyzing a large amount of data. Additionally, shear wave splitting results are seldom evaluated using the same quality criteria which complicates a straight-forward comparison. SplitRacer consists of several processing steps: i) download of data per FDSNWS, ii) direct reading of miniSEED-files and an initial screening and categorizing of XKS-waveforms using a pre-set SNR-threshold. iii) an analysis of the particle motion of selected phases and successive correction of the sensor miss-alignment based on the long-axis of the particle motion. iv) splitting analysis of selected events: seismograms are first rotated into radial and transverse components, then the energy-minimization method is applied, which provides the polarization and delay time of the phase. To estimate errors, the analysis is done for different randomly-chosen time windows. v) joint-splitting analysis for all events for one station, where the energy content of all phases is inverted simultaneously. This allows to decrease the influence of noise and to increase robustness of the measurement
Graphical analysis of some pseudo-random number generators
Lewis, Peter A. W.
1986-01-01
There exist today many 'good' pseudo-random number generators; the problem is to retrieve them. This document discusses three commonly used pseudo- random number generators, the first being RANDU, a notoriously bad generator, but one which is still occasionally used. The next is the widely used prime modulus, multiplicative congruential generator used in LL-RANDOMII, the Naval Postgraduate School random number package, and the last is the random number generator provided for microcomputers wi...
Wave energy budget analysis in the Earth’s radiation belts uncovers a missing energy
Artemyev, A.V.; Agapitov, O.V.; Mourenas, D.; Krasnoselskikh, V.V.; Mozer, F.S.
2015-01-01
Whistler-mode emissions are important electromagnetic waves pervasive in the Earth’s magnetosphere, where they continuously remove or energize electrons trapped by the geomagnetic field, controlling radiation hazards to satellites and astronauts and the upper-atmosphere ionization or chemical composition. Here, we report an analysis of 10-year Cluster data, statistically evaluating the full wave energy budget in the Earth’s magnetosphere, revealing that a significant fraction of the energy corresponds to hitherto generally neglected very oblique waves. Such waves, with 10 times smaller magnetic power than parallel waves, typically have similar total energy. Moreover, they carry up to 80% of the wave energy involved in wave–particle resonant interactions. It implies that electron heating and precipitation into the atmosphere may have been significantly under/over-valued in past studies considering only conventional quasi-parallel waves. Very oblique waves may turn out to be a crucial agent of energy redistribution in the Earth’s radiation belts, controlled by solar activity. PMID:25975615
A New Alternative in Urban Geophysics: Multi-Channel Analysis of Surface Waves (MASW) Method
International Nuclear Information System (INIS)
Ozcep, F.
2007-01-01
Geophysical studies are increasingly being applied to geotechnical investigations as they can identify soil properties and soil boundaries. Other advantage is that many of these methods are non-invasive and environment friendly. Soil stiffness is one of the critical material parameters considered during an early stage of most foundation construction. It is related directly to the stability of structural load, especially as it relates to possible earthquake hazard. Soil lacking sufficient stiffness for a given load can experience a significant reduction in strength under earthquake shaking resulting in liquefaction, a condition responsible for tremendous amounts of damage from earthquakes around the world The multichannel analysis of surface waves (MASW) method originated from the traditional seismic exploration approach that employs multiple (twelve or more) receivers placed along a linear survey line. Main advantage is its capability of recognizing different types of seismic waves based on wave propagation characteristics such as velocity and attenuation. The MASW method utilizes this capability to discriminate the fundamental-mode Rayleigh wave against all other types of surface and body waves generated not only from the active seismic source but also from the ambient site conditions. Dispersive characteristics of seismic waves are imaged from an objective 2-D wave field transformation. The present paper indicates results from MASW survey at different urban site in Turkey. MASW techniques will prove to be important tools for obtaining shear wave velocity and evaluating liquefaction potential, soil bearing capacity and soil amplification, etc. for future geophysical and geotechnical engineering community
Pasquet, S.; Wang, W.; Holbrook, W. S.; Bodet, L.; Carr, B.; Flinchum, B. A.
2017-12-01
Estimating porosity and saturation in the shallow subsurface over large lateral scales is vitally important for understanding the development and evolution of the Critical Zone (CZ). Because elastic properties (P- and S-wave velocities) are particularly sensitive to porosity and saturation, seismic methods (in combination with petrophysical models) are effective tools for mapping CZ architecture and processes. While many studies employ P-wave refraction methods, fewer use the surface waves that are typically also recorded in those same surveys. Here we show the value of exploiting surface waves to extract supplementary shear-wave velocity (Vs) information in the CZ. We use a new, user-friendly, open-source MATLAB-based package (SWIP) to invert surface-wave data and estimate lateral variations of Vs in the CZ. Results from synthetics show that this approach enables the resolution of physical property variations in the upper 10-15 m below the surface with lateral scales of about 5 m - a vast improvement compared to P-wave tomography alone. A field example at a Yellowstone hydrothermal system also demonstrates the benefits of including Vs in the petrophysical models to estimate not only porosity but also saturation, thus highlighting subsurface gas pathways. In light of these results, we strongly suggest that surface-wave analysis should become a standard approach in CZ seismic surveys.
Random Matrix Theory Approach to Indonesia Energy Portfolio Analysis
Mahardhika, Alifian; Purqon, Acep
2017-07-01
In a few years, Indonesia experienced difficulties in maintaining energy security, the problem is the decline in oil production from 1.6 million barrels per day to 861 thousand barrels per day in 2012. However, there is a difference condition in 2015 until the third week in 2016, world oil prices actually fell at the lowest price level since last 12 years. The decline in oil prices due to oversupply of oil by oil-producing countries of the world due to the instability of the world economy. Wave of layoffs in Indonesia is a response to the decline in oil prices, this led to the energy and mines portfolios Indonesia feared would not be more advantageous than the portfolio in other countries. In this research, portfolio analysis will be done on energy and mining in Indonesia by using stock price data of energy and mines in the period 26 November 2010 until April 1, 2016. It was found that the results have a wide effect of the market potential is high in the determination of the return on the portfolio energy and mines. Later, it was found that there are eight of the thirty stocks in the energy and mining portfolio of Indonesia which have a high probability of return relative to the average return of stocks in a portfolio of energy and mines.
Millimeter Wave Attenuation in Moist Air: Laboratory Measurements and Analysis.
1984-03-01
generation of incoherent noise, Mnd wavelengths. (e) scintillitions due to random fluctuations of the medium in space and time. The array of mathematical ...calculations are for observations in the zenith direction free air is very empty. The molecular radius r -1.5 x ICI-4 Lem. groud lvel Coaic aditio of
Shimura, Tomoya; Mori, Nobuhito; Mase, Hajime
2015-01-01
Changes in ocean surface waves elicit a variety of impacts on coastal environments. To assess the future changes in the ocean surface wave climate, several future projections of global wave climate have been simulated in previous studies. However, previously there has been little discussion about the causes behind changes in the future wave climate and the differences between projections. The objective of this study is to estimate the future changes in mean wave climate and the sensitivity of...
Reconstruction of Interfering Waves from Three Dimensional Analysis of Their Interference Pattern
Directory of Open Access Journals (Sweden)
M. T. Tavassoli
1997-04-01
Full Text Available Optical interferometry is being used as an efficient tool to analyse smooth surfaces for more than a century. Although, due to introduction of novel computer assisted analyzing techniques and array detectors, like CCD, the speed and the precision of processing have been increased tremendously, but the main equation involved is not changed. The main equation is the intensity distribution in the interference pattern of a plane reference wave and the required wave. In the paper it is shown that by analysis of the interference pattern of two unknown waves in three dimension (which is possible for coherent waves it is possible to reconstruct each wave separately. This approach has several useful applications, namely, on can do without reference plane wave in the interferometric surface analysis and, it is possible to reconstruct an unknown wave by making it to interfere with itself. This is very useful in determining the profile of laser beams and erasing the effect of atmospheric disturbances on observing astronomical objects.
Symmetry analysis of many-body wave functions, with applications to the nuclear shell model
International Nuclear Information System (INIS)
Novoselsky, A.; Katriel, J.
1995-01-01
The weights of the different permutational symmetry components of a nonsymmetry-adapted many-particle wave function are evaluated in terms of the expectation values of the symmetric-group class sums. This facilitates the evaluation of the weights without the construction of a complete set of symmetry adapted functions. Subspace projection operators are introduced, to be used when prior knowledge about the symmetry-species composition of a wave function is available. The permutational weight analysis of a recursively angular-momentum coupled (shell model) wave function is presented as an illustration
Gravitational-wave physics and astronomy an introduction to theory, experiment and data analysis
Creighton, Jolien D E
2011-01-01
This most up-to-date, one-stop reference combines coverage of both theory and observational techniques, with introductory sections to bring all readers up to the same level. Written by outstanding researchers directly involved with the scientific program of the Laser Interferometer Gravitational-Wave Observatory (LIGO), the book begins with a brief review of general relativity before going on to describe the physics of gravitational waves and the astrophysical sources of gravitational radiation. Further sections cover gravitational wave detectors, data analysis, and the outlook of gravitation
Development of an analysis code for pressure wave propagation, (1)
International Nuclear Information System (INIS)
Tanaka, Yoshihisa; Sakano, Kosuke; Shindo, Yoshihisa
1974-11-01
We analyzed the propagation of the pressure-wave in the piping system of SWAT-1B rig by using SWAC-5 Code. We carried out analyses on the following parts. 1) A straight pipe 2) Branches 3) A piping system The results obtained in these analyses are as follows. 1) The present our model simulates well the straight pipe and the branch with the same diameters. 2) The present our model simulates approximately the branch with the different diameters and the piping system. (auth.)
Linear and nonlinear analysis of density wave instability phenomena
International Nuclear Information System (INIS)
Ambrosini, Walter
1999-01-01
In this paper the mechanism of density-wave oscillations in a boiling channel with uniform and constant heat flux is analysed by linear and nonlinear analytical tools. A model developed on the basis of a semi-implicit numerical discretization of governing partial differential equations is used to provide information on the transient distribution of relevant variables along the channel during instabilities. Furthermore, a lumped parameter model and a distributed parameter model developed in previous activities are also adopted for independent confirmation of the observed trends. The obtained results are finally put in relation with the picture of the phenomenon proposed in classical descriptions. (author)
Direct Calculation of the Scattering Amplitude Without Partial Wave Analysis
Shertzer, J.; Temkin, A.; Fisher, Richard R. (Technical Monitor)
2001-01-01
Two new developments in scattering theory are reported. We show, in a practical way, how one can calculate the full scattering amplitude without invoking a partial wave expansion. First, the integral expression for the scattering amplitude f(theta) is simplified by an analytic integration over the azimuthal angle. Second, the full scattering wavefunction which appears in the integral expression for f(theta) is obtained by solving the Schrodinger equation with the finite element method (FEM). As an example, we calculate electron scattering from the Hartree potential. With minimal computational effort, we obtain accurate and stable results for the scattering amplitude.
DEFF Research Database (Denmark)
This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis......, material characterization, electromagnetic properties of plasma, analysis and applications of periodic structures and waveguide components, etc....
A simplified method for random vibration analysis of structures with random parameters
International Nuclear Information System (INIS)
Ghienne, Martin; Blanzé, Claude
2016-01-01
Piezoelectric patches with adapted electrical circuits or viscoelastic dissipative materials are two solutions particularly adapted to reduce vibration of light structures. To accurately design these solutions, it is necessary to describe precisely the dynamical behaviour of the structure. It may quickly become computationally intensive to describe robustly this behaviour for a structure with nonlinear phenomena, such as contact or friction for bolted structures, and uncertain variations of its parameters. The aim of this work is to propose a non-intrusive reduced stochastic method to characterize robustly the vibrational response of a structure with random parameters. Our goal is to characterize the eigenspace of linear systems with dynamic properties considered as random variables. This method is based on a separation of random aspects from deterministic aspects and allows us to estimate the first central moments of each random eigenfrequency with a single deterministic finite elements computation. The method is applied to a frame with several Young's moduli modeled as random variables. This example could be expanded to a bolted structure including piezoelectric devices. The method needs to be enhanced when random eigenvalues are closely spaced. An indicator with no additional computational cost is proposed to characterize the ’’proximity” of two random eigenvalues. (paper)
Henderson, Gregory Newell
Semiconductor device dimensions are rapidly approaching a fundamental limit where drift-diffusion equations and the depletion approximation are no longer valid. In this regime, quantum effects can dominate device response. To increase further device density and speed, new devices must be designed that use these phenomena to positive advantage. In addition, quantum effects provide opportunities for a new class of devices which can perform functions previously unattainable with "conventional" semiconductor devices. This thesis has described research in the analysis of electron wave effects in semiconductors and the development of methods for the design, fabrication, and characterization of quantum devices based on these effects. First, an exact set of quantitative analogies are presented which allow the use of well understood optical design and analysis tools for the development of electron wave semiconductor devices. Motivated by these analogies, methods are presented for modeling electron wave grating diffraction using both an exact rigorous coupled-wave analysis and approximate analyses which are useful for grating design. Example electron wave grating switch and multiplexer designs are presented. In analogy to thin-film optics, the design and analysis of electron wave Fabry-Perot interference filters are also discussed. An innovative technique has been developed for testing these (and other) electron wave structures using Ballistic Electron Emission Microscopy (BEEM). This technique uses a liquid-helium temperature scanning tunneling microscope (STM) to perform spectroscopy of the electron transmittance as a function of electron energy. Experimental results show that BEEM can resolve even weak quantum effects, such as the reflectivity of a single interface between materials. Finally, methods are discussed for incorporating asymmetric electron wave Fabry-Perot filters into optoelectronic devices. Theoretical and experimental results show that such structures could
Coupled channel analysis of s-wave ππ and K anti-K photoproduction
International Nuclear Information System (INIS)
Chueng-Ryong Ji; Szczepaniak, A.; Kaminski, R.; Lesniak, L.; Williams, R.
1997-10-01
We present a coupled channel partial wave analysis of non-diffractive S-wave π + π - and K + K - photoproduction focusing on the K anti-K threshold. Final state interactions are included. We calculate total cross sections, angular and effective mass distributions in both ππ and K anti-K channels. Our results indicate that these processes are experimentally measurable and valuable information on the f 0 (980) resonance structure can be obtained. (author)
A Numerical Method for Blast Shock Wave Analysis of Missile Launch from Aircraft
Directory of Open Access Journals (Sweden)
Sebastian Heimbs
2015-01-01
Full Text Available An efficient empirical approach was developed to accurately represent the blast shock wave loading resulting from the launch of a missile from a military aircraft to be used in numerical analyses. Based on experimental test series of missile launches in laboratory environment and from a helicopter, equations were derived to predict the time- and position-dependent overpressure. The method was finally applied and validated in a structural analysis of a helicopter tail boom under missile launch shock wave loading.
Analysis of wave-like oscillations in parameters of sporadic E layer and neutral atmosphere
Mošna, Z.; Koucká Knížová, P.
2012-12-01
The present study mainly concerns the wave-like activity in the ionospheric sporadic E layer (Es) and in the lower lying stratosphere. The proposed analysis involves parameters describing the state of plasma in the sporadic E layer. Critical frequencies foEs and layer heights hEs were measured at the Pruhonice station (50°N, 14.5°E) during summer campaigns 2004, 2006 and 2008. Further, we use neutral atmosphere (temperature data at 10 hPa) data from the same time interval. The analysis concentrates on vertically propagating wave-like structures within distant atmospheric regions. By means of continuous wavelet transform (CWT) we have detected significant wave-like oscillation at periods covering tidal and planetary oscillation domains both in the Es layer parameters (some of them were reported earlier, for instance in works of Abdu et al., 2003; Pancheva and Mitchel, 2004; Pancheva et al., 2003; Šauli and Bourdillon, 2008) and in stratospheric temperature variations. Further analyses using cross wavelet transform (XWT) and wavelet coherence analysis (WTC) show that despite high wave-like activity in a wide period range, there are only limited coherent wave-like bursts present in both spectra. Such common coherent wave bursts occur on periods close to eigen-periods of the terrestrial atmosphere. We suppose that vertical coupling between atmospheric regions realized by vertically propagating planetary waves occurs predominantly on periods close to those of Rossby modes. Analysis of the phase shift between data from distant atmospheric regions reveals high variability and very likely supports the non-linear scenario of the vertical coupling provided by planetary waves.
Analysis of a time fractional wave-like equation with the homotopy analysis method
International Nuclear Information System (INIS)
Xu Hang; Cang Jie
2008-01-01
The time fractional wave-like differential equation with a variable coefficient is studied analytically. By using a simple transformation, the governing equation is reduced to two fractional ordinary differential equations. Then the homotopy analysis method is employed to derive the solutions of these equations. The accurate series solutions are obtained. Especially, when h f =h g =-1, these solutions are exactly the same as those results given by the Adomian decomposition method. The present work shows the validity and great potential of the homotopy analysis method for solving nonlinear fractional differential equations. The basic idea described in this Letter is expected to be further employed to solve other similar nonlinear problems in fractional calculus
Random signal tomographical analysis of two-phase flow
International Nuclear Information System (INIS)
Han, P.; Wesser, U.
1990-01-01
This paper reports on radiation tomography which is a useful tool for studying the internal structures of two-phase flow. However, general tomography analysis gives only time-averaged results, hence much information is lost. As a result, it is sometimes difficult to identify the flow regime; for example, the time-averaged picture does not significantly change as an annual flow develops from a slug flow. A two-phase flow diagnostic technique based on random signal tomographical analysis is developed. It extracts more information by studying the statistical variation of the measured signal with time. Local statistical parameters, including mean value, variance, skewness and flatness etc., are reconstructed from the information obtained by a general tomography technique. More important information are provided by the results. Not only the void fraction can be easily calculated, but also the flow pattern can be identified more objectively and more accurately. The experimental setup is introduced. It consisted of a two-phase flow loop, an X-ray system, a fan-like five-beam detector system and a signal acquisition and processing system. In the experiment, for both horizontal and vertical test sections (aluminum and steel tube with Di/Do = 40/45 mm), different flow situations are realized by independently adjusting air and water mass flow. Through a glass tube connected with the test section, some typical flow patterns are visualized and used for comparing with the reconstruction results
Analysis of Peristaltic Waves & their Role in Migrating Physarum Plasmodia
Lewis, Owen; Guy, Robert
2017-11-01
The true slime mold Physarum polycephalum exhibits a vast array of sophisticated manipulations of its intracellular cytoplasm. Growing microplasmodia of physarum have been observed to adopt an elongated tadpole shape, then contract in a rhythmic, traveling wave pattern that resembles peristaltic pumping. This contraction drives a fast flow of non-gelated cytoplasm along the cell longitudinal axis. It has been hypothesized that this flow of cytoplasm is a driving factor in generating motility of the plasmodium. In this work, we use two different mathematical models to investigate how peristaltic pumping within physarum may be used to drive cellular motility. We compare the relative phase of flow and deformation waves predicted by both models to similar phase data collected from in vivo experiments using physarum plasmodia. Both models suggest that a mechanical asymmetry in the cell is required to reproduce the experimental observations. Such a mechanical asymmetry is also shown to increase the potential for cellular migration, as measured by both stress generation and migration velocity.
Directory of Open Access Journals (Sweden)
E. A. K. Ford
2008-02-01
Full Text Available Data from the Fabry-Perot Interferometers at KEOPS (Sweden, Sodankylä (Finland, and Svalbard (Norway, have been analysed for gravity wave activity on all the clear nights from 2000 to 2006. A total of 249 nights were available from KEOPS, 133 from Sodankylä and 185 from the Svalbard FPI. A Lomb-Scargle analysis was performed on each of these nights to identify the periods of any wave activity during the night. Comparisons between many nights of data allow the general characteristics of the waves that are present in the high latitude upper thermosphere to be determined. Comparisons were made between the different parameters: the atomic oxygen intensities, the thermospheric winds and temperatures, and for each parameter the distribution of frequencies of the waves was determined. No dependence on the number of waves on geomagnetic activity levels, or position in the solar cycle, was found. All the FPIs have had different detectors at various times, producing different time resolutions of the data, so comparisons between the different years, and between data from different sites, showed how the time resolution determines which waves are observed. In addition to the cutoff due to the Nyquist frequency, poor resolution observations significantly reduce the number of short-period waves (<1 h period that may be detected with confidence. The length of the dataset, which is usually determined by the length of the night, was the main factor influencing the number of long period waves (>5 h detected. Comparisons between the number of gravity waves detected at KEOPS and Sodankylä over all the seasons showed a similar proportion of waves to the number of nights used for both sites, as expected since the two sites are at similar latitudes and therefore locations with respect to the auroral oval, confirming this as a likely source region. Svalbard showed fewer waves with short periods than KEOPS data for a season when both had the same time resolution data
Pseudospectral modeling and dispersion analysis of Rayleigh waves in viscoelastic media
Zhang, K.; Luo, Y.; Xia, J.; Chen, C.
2011-01-01
Multichannel Analysis of Surface Waves (MASW) is one of the most widely used techniques in environmental and engineering geophysics to determine shear-wave velocities and dynamic properties, which is based on the elastic layered system theory. Wave propagation in the Earth, however, has been recognized as viscoelastic and the propagation of Rayleigh waves presents substantial differences in viscoelastic media as compared with elastic media. Therefore, it is necessary to carry out numerical simulation and dispersion analysis of Rayleigh waves in viscoelastic media to better understand Rayleigh-wave behaviors in the real world. We apply a pseudospectral method to the calculation of the spatial derivatives using a Chebyshev difference operator in the vertical direction and a Fourier difference operator in the horizontal direction based on the velocity-stress elastodynamic equations and relations of linear viscoelastic solids. This approach stretches the spatial discrete grid to have a minimum grid size near the free surface so that high accuracy and resolution are achieved at the free surface, which allows an effective incorporation of the free surface boundary conditions since the Chebyshev method is nonperiodic. We first use an elastic homogeneous half-space model to demonstrate the accuracy of the pseudospectral method comparing with the analytical solution, and verify the correctness of the numerical modeling results for a viscoelastic half-space comparing the phase velocities of Rayleigh wave between the theoretical values and the dispersive image generated by high-resolution linear Radon transform. We then simulate three types of two-layer models to analyze dispersive-energy characteristics for near-surface applications. Results demonstrate that the phase velocity of Rayleigh waves in viscoelastic media is relatively higher than in elastic media and the fundamental mode increases by 10-16% when the frequency is above 10. Hz due to the velocity dispersion of P
Lin, Nan; Jiang, Junhai; Guo, Shicheng; Xiong, Momiao
2015-01-01
Due to the advancement in sensor technology, the growing large medical image data have the ability to visualize the anatomical changes in biological tissues. As a consequence, the medical images have the potential to enhance the diagnosis of disease, the prediction of clinical outcomes and the characterization of disease progression. But in the meantime, the growing data dimensions pose great methodological and computational challenges for the representation and selection of features in image cluster analysis. To address these challenges, we first extend the functional principal component analysis (FPCA) from one dimension to two dimensions to fully capture the space variation of image the signals. The image signals contain a large number of redundant features which provide no additional information for clustering analysis. The widely used methods for removing the irrelevant features are sparse clustering algorithms using a lasso-type penalty to select the features. However, the accuracy of clustering using a lasso-type penalty depends on the selection of the penalty parameters and the threshold value. In practice, they are difficult to determine. Recently, randomized algorithms have received a great deal of attentions in big data analysis. This paper presents a randomized algorithm for accurate feature selection in image clustering analysis. The proposed method is applied to both the liver and kidney cancer histology image data from the TCGA database. The results demonstrate that the randomized feature selection method coupled with functional principal component analysis substantially outperforms the current sparse clustering algorithms in image cluster analysis. PMID:26196383
Surface Acoustic Wave Monitor for Deposition and Analysis of Ultra-Thin Films
Hines, Jacqueline H. (Inventor)
2015-01-01
A surface acoustic wave (SAW) based thin film deposition monitor device and system for monitoring the deposition of ultra-thin films and nanomaterials and the analysis thereof is characterized by acoustic wave device embodiments that include differential delay line device designs, and which can optionally have integral reference devices fabricated on the same substrate as the sensing device, or on a separate device in thermal contact with the film monitoring/analysis device, in order to provide inherently temperature compensated measurements. These deposition monitor and analysis devices can include inherent temperature compensation, higher sensitivity to surface interactions than quartz crystal microbalance (QCM) devices, and the ability to operate at extreme temperatures.
An analysis of beam parameters on proton-acoustic waves through an analytic approach.
Kipergil, Esra Aytac; Erkol, Hakan; Kaya, Serhat; Gulsen, Gultekin; Unlu, Mehmet Burcin
2017-06-21
It has been reported that acoustic waves are generated when a high-energy pulsed proton beam is deposited in a small volume within tissue. One possible application of proton-induced acoustics is to get real-time feedback for intra-treatment adjustments by monitoring such acoustic waves. A high spatial resolution in ultrasound imaging may reduce proton range uncertainty. Thus, it is crucial to understand the dependence of the acoustic waves on the proton beam characteristics. In this manuscript, firstly, an analytic solution for the proton-induced acoustic wave is presented to reveal the dependence of the signal on the beam parameters; then it is combined with an analytic approximation of the Bragg curve. The influence of the beam energy, pulse duration and beam diameter variation on the acoustic waveform are investigated. Further analysis is performed regarding the Fourier decomposition of the proton-acoustic signals. Our results show that the smaller spill time of the proton beam upsurges the amplitude of the acoustic wave for a constant number of protons, which is hence beneficial for dose monitoring. The increase in the energy of each individual proton in the beam leads to the spatial broadening of the Bragg curve, which also yields acoustic waves of greater amplitude. The pulse duration and the beam width of the proton beam do not affect the central frequency of the acoustic wave, but they change the amplitude of the spectral components.
Theoretical analysis and experimental study of oxygen transfer under regular and non-breaking waves
Institute of Scientific and Technical Information of China (English)
尹则高; 梁丙臣; 王乐
2013-01-01
The dissolved oxygen concentration is an important index of water quality, and the atmosphere is one of the important sources of the dissolved oxygen. In this paper, the mass conservation law and the dimensional analysis method are employed to study the oxygen transfer under regular and non-breaking waves, and a unified oxygen transfer coefficient equation is obtained with consi-deration of the effect of kinetic energy and wave period. An oxygen transfer experiment for the intermediate depth water wave is per-formed to measure the wave parameters and the dissolved oxygen concentration. The experimental data and the least squares method are used to determine the constant in the oxygen transfer coefficient equation. The experimental data and the previous reported data are also used to further validate the oxygen transfer coefficient, and the agreement is satisfactory. The unified equation shows that the oxygen transfer coefficient increases with the increase of a parameter coupled with the wave height and the wave length, but it de-creases with the increase of the wave period, which has a much greater influence on the oxygen transfer coefficient than the coupled parameter.
A theoretical analysis of the weak shock waves propagating through a bubbly flow
International Nuclear Information System (INIS)
Jun, Gu Sik; Kim, Heuy Dong; Baek, Seung Cheol
2004-01-01
Two-phase flow of liquid and gas through pipe lines are frequently encountered in nuclear power plant or industrial facility. Pressure waves which can be generated by a valve operation or any other cause in pipe lines propagate through the two-phase flow, often leading to severe noise and vibration problems or fatigue failure of pipe line system. It is of practical importance to predict the propagation characteristics of the pressure waves for the safety design for the pipe line. In the present study, a theoretical analysis is performed to understand the propagation characteristics of a weak shock wave in a bubbly flow. A wave equation is developed using a small perturbation method to analyze the weak shock wave through a bubbly flow with comparably low void fractions. It is known that the elasticity of pipe and void fraction significantly affect the propagation speed of shock wave, but the frequency of relaxation oscillation which is generated behind the shock wave is not strongly influenced by the elasticity of pipe. The present analytical results are in close agreement with existing experimental data
Baryon Spectroscopy Through Partial-Wave Analysis and Meson Photoproduction
International Nuclear Information System (INIS)
Manley, D. Mark
2016-01-01
The principal goal of this project is the experimental and phenomenological study of baryon spectroscopy. The PI's group consists of himself and three graduate students. This final report summarizes research activities by the PI's group during the period 03/01/2015 to 08/14/2016. During this period, the PI co-authored 11 published journal papers and one proceedings article and presented three invited talks. The PI's general interest is the investigation of the baryon resonance spectrum up to masses of ~ 2 GeV. More detail is given on two research projects: Neutral Kaon Photoproduction and Partial-Wave Analyses of γp → η p, γn → η n, and γp → K"+ Λ.
Baryon Spectroscopy Through Partial-Wave Analysis and Meson Photoproduction
Energy Technology Data Exchange (ETDEWEB)
Manley, D. Mark [Kent State Univ., Kent, OH (United States)
2016-09-08
The principal goal of this project is the experimental and phenomenological study of baryon spectroscopy. The PI's group consists of himself and three graduate students. This final report summarizes research activities by the PI's group during the period 03/01/2015 to 08/14/2016. During this period, the PI co-authored 11 published journal papers and one proceedings article and presented three invited talks. The PI's general interest is the investigation of the baryon resonance spectrum up to masses of ~ 2 GeV. More detail is given on two research projects: Neutral Kaon Photoproduction and Partial-Wave Analyses of γp → η p, γn → η n, and γp → K⁺ Λ.
SHOCK WAVE ANALYSIS OF THE CONSEQUENCES OF A REACTOR ACCIDENT
Energy Technology Data Exchange (ETDEWEB)
Klickman, A E; Nicholson, R B; Nims, J B
1963-06-15
The solution to the problem of transmission and attenuation of the shock wave resulting from a large reactor accident is demonstrated for a configuration typical of many reactors. The particular configuration is that of a spherical gas bubble surrounded by one or more concentric regions of compressible material. A systematic parameter study was made in which the physical characteristics of the compressible shield regions and the expansion characteristics of a gas were assumed to be parameters. Results for seven cases are shown, and similar cases with only one important difference are compared. From these comparisons it was concluded that under certain conditions alternative materials can be substituted for reactor materials in model experiments and TNT can be used as an energy source instead of uranium. In the outer crushable region the total mass of material is the important factor. (A.G.W.)
Energy Technology Data Exchange (ETDEWEB)
Nazarenko, Sergey [Warwick Univ., Coventry (United Kingdom). Mathematics Inst.
2011-07-01
Wave Turbulence refers to the statistical theory of weakly nonlinear dispersive waves. There is a wide and growing spectrum of physical applications, ranging from sea waves, to plasma waves, to superfluid turbulence, to nonlinear optics and Bose-Einstein condensates. Beyond the fundamentals the book thus also covers new developments such as the interaction of random waves with coherent structures (vortices, solitons, wave breaks), inverse cascades leading to condensation and the transitions between weak and strong turbulence, turbulence intermittency as well as finite system size effects, such as ''frozen'' turbulence, discrete wave resonances and avalanche-type energy cascades. This book is an outgrow of several lectures courses held by the author and, as a result, written and structured rather as a graduate text than a monograph, with many exercises and solutions offered along the way. The present compact description primarily addresses students and non-specialist researchers wishing to enter and work in this field. (orig.)
Use of energy analysis to evaluate the parameters of wave fields
Energy Technology Data Exchange (ETDEWEB)
Soldatov, V.N.; Sinitsyn, Ye.S.
1984-01-01
Algorithms are proposed and studied for energy analysis of the wave fields. A comparative evaluation is made of the resolution of the energy analysis methods. A method is examined for automated processing of the energograms allowing a search for an estimate of the parameters with significant acceleration of the computer calculations and saving of its working storage by designing multipurpose algorithms of data processing.
Auto-correlation analysis of wave heights in the Bay of Bengal
Indian Academy of Sciences (India)
Time series observations of significant wave heights in the Bay of Bengal were subjected to auto- correlation analysis to determine temporal variability scale. The analysis indicates an exponen- tial fall of auto-correlation in the first few hours with a decorrelation time scale of about six hours. A similar figure was found earlier ...
Melnick, Gary J.
1990-01-01
The Mission Operations and Data Analysis Plan is presented for the Submillimeter Wave Astronomy Satellite (SWAS) Project. It defines organizational responsibilities, discusses target selection and navigation, specifies instrument command and data requirements, defines data reduction and analysis hardware and software requirements, and discusses mission operations center staffing requirements.
International Nuclear Information System (INIS)
Elson, J.M.
1995-01-01
In this work, we use first-order perturbation theory to calculate and then compare the (1) angular distribution of incident light scattered from a multilayer-coated optical component and (2) the angular distribution of incident light coupled into guided waves supported by the multilayer component. The incident beam is assumed to be a monochromatic plane wave and the scattering/coupling is assumed to be caused by roughness at the interfaces of the optical component. Numerical results show that for high quality (low root mean square roughness) optical components, comparison of the relative amounts of incident energy (1) scattered out of the specular beam and (2) coupled into guided waves are comparable. It follows that the guided wave energy will further contribute to the scattered field via radiative decay or be converted to heat. Thus, this work can help provide an estimation of when guided wave coupling can occur along with the expected magnitude. (orig.)
Directory of Open Access Journals (Sweden)
Hyebin Lee
2018-02-01
Full Text Available Wind-wave hybrid power generation systems have the potential to become a significant source of affordable renewable energy. However, their strong interactions with both wind- and wave-induced forces raise a number of technical challenges for modelling. The present study undertakes a numerical investigation on multi-body hydrodynamic interaction between a wind-wave hybrid floating platform and multiple wave energy converters (WECs in a frequency domain. In addition to the exact responses of the platform and the WECs, the power take-off (PTO mechanism was taken into account for analysis. The coupled hydrodynamic coefficients and wave exciting forces were obtained from WAMIT, the 3D diffraction/radiation solver based on the boundary element method. The overall performance of the multiple WECs is presented and compared with the performance of a single isolated WEC. The analysis showed significant differences in the dynamic responses of the WECs when the multi-body interaction was considered. In addition, the PTO damping effect made a considerable difference to the responses of the WECs. However, the platform response was only minimally affected by PTO damping. With regard to energy capture, the interaction effect of the designed multiple WEC array layout is evaluated. The WEC array configuration showed both constructive and destructive effects in accordance with the incident wave frequency and direction.
Complex network analysis of state spaces for random Boolean networks
Energy Technology Data Exchange (ETDEWEB)
Shreim, Amer [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Berdahl, Andrew [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Sood, Vishal [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Grassberger, Peter [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Paczuski, Maya [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada)
2008-01-15
We apply complex network analysis to the state spaces of random Boolean networks (RBNs). An RBN contains N Boolean elements each with K inputs. A directed state space network (SSN) is constructed by linking each dynamical state, represented as a node, to its temporal successor. We study the heterogeneity of these SSNs at both local and global scales, as well as sample to-sample fluctuations within an ensemble of SSNs. We use in-degrees of nodes as a local topological measure, and the path diversity (Shreim A et al 2007 Phys. Rev. Lett. 98 198701) of an SSN as a global topological measure. RBNs with 2 {<=} K {<=} 5 exhibit non-trivial fluctuations at both local and global scales, while K = 2 exhibits the largest sample-to-sample (possibly non-self-averaging) fluctuations. We interpret the observed 'multi scale' fluctuations in the SSNs as indicative of the criticality and complexity of K = 2 RBNs. 'Garden of Eden' (GoE) states are nodes on an SSN that have in-degree zero. While in-degrees of non-GoE nodes for K > 1 SSNs can assume any integer value between 0 and 2{sup N}, for K = 1 all the non-GoE nodes in a given SSN have the same in-degree which is always a power of two.
Complex network analysis of state spaces for random Boolean networks
International Nuclear Information System (INIS)
Shreim, Amer; Berdahl, Andrew; Sood, Vishal; Grassberger, Peter; Paczuski, Maya
2008-01-01
We apply complex network analysis to the state spaces of random Boolean networks (RBNs). An RBN contains N Boolean elements each with K inputs. A directed state space network (SSN) is constructed by linking each dynamical state, represented as a node, to its temporal successor. We study the heterogeneity of these SSNs at both local and global scales, as well as sample to-sample fluctuations within an ensemble of SSNs. We use in-degrees of nodes as a local topological measure, and the path diversity (Shreim A et al 2007 Phys. Rev. Lett. 98 198701) of an SSN as a global topological measure. RBNs with 2 ≤ K ≤ 5 exhibit non-trivial fluctuations at both local and global scales, while K = 2 exhibits the largest sample-to-sample (possibly non-self-averaging) fluctuations. We interpret the observed 'multi scale' fluctuations in the SSNs as indicative of the criticality and complexity of K = 2 RBNs. 'Garden of Eden' (GoE) states are nodes on an SSN that have in-degree zero. While in-degrees of non-GoE nodes for K > 1 SSNs can assume any integer value between 0 and 2 N , for K = 1 all the non-GoE nodes in a given SSN have the same in-degree which is always a power of two
Random versus Deterministic Descent in RNA Energy Landscape Analysis
Directory of Open Access Journals (Sweden)
Luke Day
2016-01-01
Full Text Available Identifying sets of metastable conformations is a major research topic in RNA energy landscape analysis, and recently several methods have been proposed for finding local minima in landscapes spawned by RNA secondary structures. An important and time-critical component of such methods is steepest, or gradient, descent in attraction basins of local minima. We analyse the speed-up achievable by randomised descent in attraction basins in the context of large sample sets where the size has an order of magnitude in the region of ~106. While the gain for each individual sample might be marginal, the overall run-time improvement can be significant. Moreover, for the two nongradient methods we analysed for partial energy landscapes induced by ten different RNA sequences, we obtained that the number of observed local minima is on average larger by 7.3% and 3.5%, respectively. The run-time improvement is approximately 16.6% and 6.8% on average over the ten partial energy landscapes. For the large sample size we selected for descent procedures, the coverage of local minima is very high up to energy values of the region where the samples were randomly selected from the partial energy landscapes; that is, the difference to the total set of local minima is mainly due to the upper area of the energy landscapes.
Lyu, Chao; Pedersen, Helle A.; Paul, Anne; Zhao, Liang; Solarino, Stefano
2017-07-01
It remains challenging to obtain absolute shear wave velocities of heterogeneities of small lateral extension in the uppermost mantle. This study presents a cross-section of Vs across the strongly heterogeneous 3-D structure of the western European Alps, based on array analysis of data from 92 broad-band seismic stations from the CIFALPS experiment and from permanent networks in France and Italy. Half of the stations were located along a dense sublinear array. Using a combination of these stations and off-profile stations, fundamental-mode Rayleigh wave dispersion curves were calculated using a combined frequency-time beamforming approach. We calculated dispersion curves for seven arrays of approximately 100 km aperture and 14 arrays of approximately 50 km aperture, the latter with the aim of obtaining a 2-D vertical cross-section of Vs beneath the western Alps. The dispersion curves were inverted for Vs(z), with crustal interfaces imposed from a previous receiver function study. The array approach proved feasible, as Vs(z) from independent arrays vary smoothly across the profile length. Results from the seven large arrays show that the shear velocity of the upper mantle beneath the European plate is overall low compared to AK135 with the lowest velocities in the internal part of the western Alps, and higher velocities east of the Alps beneath the Po plain. The 2-D Vs model is coherent with (i) a ∼100 km thick eastward-dipping European lithosphere west of the Alps, (ii) very high velocities beneath the Po plain, coherent with the presence of the Alpine (European) slab and (iii) a narrow low-velocity anomaly beneath the core of the western Alps (from the Briançonnais to the Dora Maira massif), and approximately colocated with a similar anomaly observed in a recent teleseismic P-wave tomography. This intriguing anomaly is also supported by traveltime variations of subvertically propagating body waves from two teleseismic events that are approximately located on
An Overview of Recent Advances in the Iterative Analysis of Coupled Models for Wave Propagation
Directory of Open Access Journals (Sweden)
D. Soares
2014-01-01
Full Text Available Wave propagation problems can be solved using a variety of methods. However, in many cases, the joint use of different numerical procedures to model different parts of the problem may be advisable and strategies to perform the coupling between them must be developed. Many works have been published on this subject, addressing the case of electromagnetic, acoustic, or elastic waves and making use of different strategies to perform this coupling. Both direct and iterative approaches can be used, and they may exhibit specific advantages and disadvantages. This work focuses on the use of iterative coupling schemes for the analysis of wave propagation problems, presenting an overview of the application of iterative procedures to perform the coupling between different methods. Both frequency- and time-domain analyses are addressed, and problems involving acoustic, mechanical, and electromagnetic wave propagation problems are illustrated.
Jiang, Lijian; Efendiev, Yalchin; Ginting, Victor
2010-01-01
In this paper, we discuss a numerical multiscale approach for solving wave equations with heterogeneous coefficients. Our interest comes from geophysics applications and we assume that there is no scale separation with respect to spatial variables. To obtain the solution of these multiscale problems on a coarse grid, we compute global fields such that the solution smoothly depends on these fields. We present a Galerkin multiscale finite element method using the global information and provide a convergence analysis when applied to solve the wave equations. We investigate the relation between the smoothness of the global fields and convergence rates of the global Galerkin multiscale finite element method for the wave equations. Numerical examples demonstrate that the use of global information renders better accuracy for wave equations with heterogeneous coefficients than the local multiscale finite element method. © 2010 IMACS.
Model-independent partial wave analysis using a massively-parallel fitting framework
Sun, L.; Aoude, R.; dos Reis, A. C.; Sokoloff, M.
2017-10-01
The functionality of GooFit, a GPU-friendly framework for doing maximum-likelihood fits, has been extended to extract model-independent {\\mathscr{S}}-wave amplitudes in three-body decays such as D + → h + h + h -. A full amplitude analysis is done where the magnitudes and phases of the {\\mathscr{S}}-wave amplitudes are anchored at a finite number of m 2(h + h -) control points, and a cubic spline is used to interpolate between these points. The amplitudes for {\\mathscr{P}}-wave and {\\mathscr{D}}-wave intermediate states are modeled as spin-dependent Breit-Wigner resonances. GooFit uses the Thrust library, with a CUDA backend for NVIDIA GPUs and an OpenMP backend for threads with conventional CPUs. Performance on a variety of platforms is compared. Executing on systems with GPUs is typically a few hundred times faster than executing the same algorithm on a single CPU.
Wave propagation analysis of a size-dependent magneto-electro-elastic heterogeneous nanoplate
Ebrahimi, Farzad; Dabbagh, Ali; Reza Barati, Mohammad
2016-12-01
The analysis of the wave propagation behavior of a magneto-electro-elastic functionally graded (MEE-FG) nanoplate is carried out in the framework of a refined higher-order plate theory. In order to take into account the small-scale influence, the nonlocal elasticity theory of Eringen is employed. Furthermore, the material properties of the nanoplate are considered to be variable through the thickness based on the power-law form. Nonlocal governing equations of the MEE-FG nanoplate have been derived using Hamilton's principle. The results of the present study have been validated by comparing them with previous researches. An analytical solution of governing equations is performed to obtain wave frequencies, phase velocities and escape frequencies. The effect of different parameters, such as wave number, nonlocal parameter, gradient index, magnetic potential and electric voltage on the wave dispersion characteristics of MEE-FG nanoscale plates is studied in detail.
Jiang, Lijian
2010-08-01
In this paper, we discuss a numerical multiscale approach for solving wave equations with heterogeneous coefficients. Our interest comes from geophysics applications and we assume that there is no scale separation with respect to spatial variables. To obtain the solution of these multiscale problems on a coarse grid, we compute global fields such that the solution smoothly depends on these fields. We present a Galerkin multiscale finite element method using the global information and provide a convergence analysis when applied to solve the wave equations. We investigate the relation between the smoothness of the global fields and convergence rates of the global Galerkin multiscale finite element method for the wave equations. Numerical examples demonstrate that the use of global information renders better accuracy for wave equations with heterogeneous coefficients than the local multiscale finite element method. © 2010 IMACS.
Bispectral analysis of nonlinear compressional waves in a two-dimensional dusty plasma crystal
International Nuclear Information System (INIS)
Nosenko, V.; Goree, J.; Skiff, F.
2006-01-01
Bispectral analysis was used to study the nonlinear interaction of compressional waves in a two-dimensional strongly coupled dusty plasma. A monolayer of highly charged polymer microspheres was suspended in a plasma sheath. The microspheres interacted with a Yukawa potential and formed a triangular lattice. Two sinusoidal pump waves with different frequencies were excited in the lattice by pushing the particles with modulated Ar + laser beams. Coherent nonlinear interaction of the pump waves was shown to be the mechanism of generating waves at the sum, difference, and other combination frequencies. However, coherent nonlinear interaction was ruled out for certain combination frequencies, in particular, for the difference frequency below an excitation-power threshold, as predicted by theory
Study on crack scattering in aluminum plates with Lamb wave frequency–wavenumber analysis
International Nuclear Information System (INIS)
Yu, Lingyu; Tian, Zhenhua; Leckey, Cara A C
2013-01-01
The multimodal characteristic of Lamb waves makes the interpretation of Lamb wave signals difficult in either the time or frequency domain. In this work, we present our study of Lamb wave propagation characterization and crack scattering using frequency–wavenumber analysis. The aim is to investigate three dimensional (3D) Lamb wave behavior in the presence of crack damage via the application of frequency–wavenumber analysis. The analysis techniques are demonstrated using simulation examples of an aluminum plate with a through-thickness crack. Both in-plane and out-of-plane components are acquired through a 3D elastodynamic finite integration technique (EFIT), while the out-of-plane component is also experimentally obtained using a scanning laser Doppler vibrometer for verification purposes. The time–space wavefield is then transformed to the frequency–wavenumber domain by a two dimensional (2D) Fourier transform and the out-of-plane EFIT results are compared to experimental measurements. The experimental and simulated results are found to be in close agreement. The frequency–wavenumber representation of in-plane and out-of-plane components shows clear distinction among various Lamb wave modes that are present. However, spatial information is lost during this 2D transformation. A short space 2D Fourier transform is therefore adopted to obtain the frequency–wavenumber spectra at various spatial locations, resulting in a space–frequency–wavenumber representation of the signal. The space–frequency–wavenumber analysis has shown its potential for indicating crack presence. (paper)
Improved analysis of all-sky meteor radar measurements of gravity wave variances and momentum fluxes
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V. F. Andrioli
2013-05-01
Full Text Available The advantages of using a composite day analysis for all-sky interferometric meteor radars when measuring mean winds and tides are widely known. On the other hand, problems arise if this technique is applied to Hocking's (2005 gravity wave analysis for all-sky meteor radars. In this paper we describe how a simple change in the procedure makes it possible to use a composite day in Hocking's analysis. Also, we explain how a modified composite day can be constructed to test its ability to measure gravity wave momentum fluxes. Test results for specified mean, tidal, and gravity wave fields, including tidal amplitudes and gravity wave momentum fluxes varying strongly with altitude and/or time, suggest that the modified composite day allows characterization of monthly mean profiles of the gravity wave momentum fluxes, with good accuracy at least at the altitudes where the meteor counts are large (from 89 to 92.5 km. In the present work we also show that the variances measured with Hocking's method are often contaminated by the tidal fields and suggest a method of empirical correction derived from a simple simulation model. The results presented here greatly increase our confidence because they show that our technique is able to remove the tide-induced false variances from Hocking's analysis.
Self-consistent adjoint analysis for topology optimization of electromagnetic waves
Deng, Yongbo; Korvink, Jan G.
2018-05-01
In topology optimization of electromagnetic waves, the Gâteaux differentiability of the conjugate operator to the complex field variable results in the complexity of the adjoint sensitivity, which evolves the original real-valued design variable to be complex during the iterative solution procedure. Therefore, the self-inconsistency of the adjoint sensitivity is presented. To enforce the self-consistency, the real part operator has been used to extract the real part of the sensitivity to keep the real-value property of the design variable. However, this enforced self-consistency can cause the problem that the derived structural topology has unreasonable dependence on the phase of the incident wave. To solve this problem, this article focuses on the self-consistent adjoint analysis of the topology optimization problems for electromagnetic waves. This self-consistent adjoint analysis is implemented by splitting the complex variables of the wave equations into the corresponding real parts and imaginary parts, sequentially substituting the split complex variables into the wave equations with deriving the coupled equations equivalent to the original wave equations, where the infinite free space is truncated by the perfectly matched layers. Then, the topology optimization problems of electromagnetic waves are transformed into the forms defined on real functional spaces instead of complex functional spaces; the adjoint analysis of the topology optimization problems is implemented on real functional spaces with removing the variational of the conjugate operator; the self-consistent adjoint sensitivity is derived, and the phase-dependence problem is avoided for the derived structural topology. Several numerical examples are implemented to demonstrate the robustness of the derived self-consistent adjoint analysis.
Pierce gain analysis for a sheet beam in a rippled waveguide traveling-wave tube
International Nuclear Information System (INIS)
Carlsten, Bruce E.
2001-01-01
A Pierce-type mode analysis is presented for a planar electron beam in a rippled planar waveguide. This analysis describes the gain of a traveling-wave tube consisting of that geometry. The dispersion relation is given by the determinant of a matrix based on the coupling of different free-space modes through the boundary conditions. For the case of high-frequency, low-power amplifiers, the dispersion relation reduces to a simple cubic expression for the Compton regime, leading to three roots analogous to the Pierce solution of a standard traveling-wave tube. The analysis shows that this type of traveling-wave tube is capable of very high gain at extremely high frequencies
A two-step FEM-SEM approach for wave propagation analysis in cable structures
Zhang, Songhan; Shen, Ruili; Wang, Tao; De Roeck, Guido; Lombaert, Geert
2018-02-01
Vibration-based methods are among the most widely studied in structural health monitoring (SHM). It is well known, however, that the low-order modes, characterizing the global dynamic behaviour of structures, are relatively insensitive to local damage. Such local damage may be easier to detect by methods based on wave propagation which involve local high frequency behaviour. The present work considers the numerical analysis of wave propagation in cables. A two-step approach is proposed which allows taking into account the cable sag and the distribution of the axial forces in the wave propagation analysis. In the first step, the static deformation and internal forces are obtained by the finite element method (FEM), taking into account geometric nonlinear effects. In the second step, the results from the static analysis are used to define the initial state of the dynamic analysis which is performed by means of the spectral element method (SEM). The use of the SEM in the second step of the analysis allows for a significant reduction in computational costs as compared to a FE analysis. This methodology is first verified by means of a full FE analysis for a single stretched cable. Next, simulations are made to study the effects of damage in a single stretched cable and a cable-supported truss. The results of the simulations show how damage significantly affects the high frequency response, confirming the potential of wave propagation based methods for SHM.
Analysis, Simulation and Prediction of Multivariate Random Fields with Package RandomFields
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Martin Schlather
2015-02-01
Full Text Available Modeling of and inference on multivariate data that have been measured in space, such as temperature and pressure, are challenging tasks in environmental sciences, physics and materials science. We give an overview over and some background on modeling with cross- covariance models. The R package RandomFields supports the simulation, the parameter estimation and the prediction in particular for the linear model of coregionalization, the multivariate Matrn models, the delay model, and a spectrum of physically motivated vector valued models. An example on weather data is considered, illustrating the use of RandomFields for parameter estimation and prediction.
Cannata, F; Spinoglio, A; Di Marco, P; Luzi, M; Canneti, A; Ricciuti, G; Reale, C
2014-01-01
Extracorporeal Shock Wave Lithotripsy is usually performed in day surgery setting, consequently people who undergo to this procedure need a safe and fast recovery. Conscious sedation with remifentanil can relieve from pain and keep patients in touch with anaesthesiologists. Few publications tell about infusion rates administered to perform this procedure7. The aim of this study is to assess which is the most appropriate infusion rate. Patients were randomly assigned to two groups. Two different infusion rates were compared: 0,05 mcg/kg/min, GROUP A (N.=114), vs. 0.1 µg/kg/min, GROUP B (N.=114). Patients' vital signs, additional analgesic requests, PONV (postoperative nausea and vomiting) and other side effects were registered. The deepness of sedation and patient's satisfaction were evaluated referring to Obsever's Assessment of Alertness and Sedation scale (O/ASS) and using a Likert's scale respectively. Pain intensity was assessed with a 11-points VAS (visual analogue scale). Differences between groups were analyzed using Student t test for independent variables. The χ2 test was used to analyze categorical variables. The study enrolled 228 patients and assigned them to two groups (N.=114). No significant differences were found regarding Likert's scale values (P=0.20), additional analgesic request (P=0.30) and mean VAS values (P>0.05) between the two groups. The difference between the two groups about PONV, hypotension, oxygen desaturation and respiratory depression was statistically significant (P<0.05), as a matter of fact in group A these side effects occurred less frequently. The fifth degree of O/ASS was estimated in about 1.61±0.19 min and 2.987±0.20 min in group A and in group B respectively (P<0.05). According with previous results remifentanil at the infusion rate of 0.05 µg/kg/min provides an effective analgesia, causing a lower incidence of side effect than 0.1 µg/kg/min, granting a fast and safe recovery.
Partial wave analysis for folded differential cross sections
Machacek, J. R.; McEachran, R. P.
2018-03-01
The value of modified effective range theory (MERT) and the connection between differential cross sections and phase shifts in low-energy electron scattering has long been recognized. Recent experimental techniques involving magnetically confined beams have introduced the concept of folded differential cross sections (FDCS) where the forward (θ ≤ π/2) and backward scattered (θ ≥ π/2) projectiles are unresolved, that is the value measured at the angle θ is the sum of the signal for particles scattered into the angles θ and π - θ. We have developed an alternative approach to MERT in order to analyse low-energy folded differential cross sections for positrons and electrons. This results in a simplified expression for the FDCS when it is expressed in terms of partial waves and thereby enables one to extract the first few phase shifts from a fit to an experimental FDCS at low energies. Thus, this method predicts forward and backward angle scattering (0 to π) using only experimental FDCS data and can be used to determine the total elastic cross section solely from experimental results at low-energy, which are limited in angular range.
Limit cycle analysis of nuclear coupled density wave oscillations
International Nuclear Information System (INIS)
Ward, M.E.
1985-01-01
An investigation of limit cycle behavior for the nuclear-coupled density wave oscillation (NCDWO) in a boiling water reactor (BWR) was performed. A simplified nonlinear model of BWR core behavior was developed using a two-region flow channel representation, coupled with a form of the point-kinetics equation. This model has been used to investigate the behavior of large amplitude NCDWO's through conventional time-integration solutions and through application of a direct relaxation-oscillation limit cycle solution in phase space. The numerical solutions demonstrate the potential for severe global power and flow oscillations in a BWR core at off-normal conditions, such as might occur during Anticipated Transients without Scram. Because of the many simplifying assumptions used, it is felt that the results should not be interpreted as an absolute prediction of core behavior, but as an indication of the potential for large oscillations and a demonstration of the corresponding limit cycle mechanisms. The oscillations in channel density drive the core power variations, and are reinforced by heat flux variations due to the changing fuel temperature. A global temperature increase occurs as energy is accumulated in the fuel, and limits the magnitude of the oscillations because as the average channel density decreases, the amplitude and duration of positive void reactivity at a given oscillation amplitude is lessened
Design and analysis of tubular permanent magnet linear wave generator.
Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng
2014-01-01
Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.
Design and Analysis of Tubular Permanent Magnet Linear Wave Generator
Directory of Open Access Journals (Sweden)
Jikai Si
2014-01-01
Full Text Available Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.
Quantum analysis of the direct measurement of light waves
International Nuclear Information System (INIS)
Saldanha, Pablo L
2014-01-01
In a beautiful experiment performed about a decade ago, Goulielmakis et al (2004 Science 305 1267–69) made a direct measurement of the electric field of light waves. However, they used a laser source to produce the light field, whose quantum state has a null expectation value for the electric field operator, so how was it possible to measure this electric field? Here we present a quantum treatment for the f:2f interferometer used to calibrate the carrier–envelope phase of the light pulses in the experiment. We show how the special nonlinear features of the f:2f interferometer can change the quantum state of the electromagnetic field inside the laser cavity to a state with a definite oscillating electric field, explaining how the ‘classical’ electromagnetic field emerges in the experiment. We discuss that this experiment was, to our knowledge, the first demonstration of an absolute coherent superposition of different photon number states in the optical regime. (paper)
Design and Analysis of Tubular Permanent Magnet Linear Wave Generator
Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng
2014-01-01
Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG. PMID:25050388
Veto analysis for gravitational wave burst signals in TAMA300 data using an ALF filter
International Nuclear Information System (INIS)
Akutsu, T; Ando, M; Kanda, N; Tatsumi, D; Telada, S; Miyoki, S; Ohashi, M
2006-01-01
Data taken by interferometers for gravitational waves include noises caused by instabilities of the interferometers. Veto analyses to remove false events caused by detectors are then necessary to detect real gravitational waves or to obtain a lower upper limit. In this paper, a veto analysis with an environmental monitor channel was implemented. We calculate the trigger rate of TAMA300 data and demonstrate the veto analysis using an alternative linear fit (ALF) filter. A threshold for the environmental monitor channel signals is set to be at 1% of the false dismissal rate. The result shows a 1/10-1/1000 reduction of trigger event rates
Analysis of random number generators in abnormal usage conditions
International Nuclear Information System (INIS)
Soucarros, M.
2012-01-01
Random numbers have been used through the ages for games of chance, more recently for secret codes and today they are necessary to the execution of computer programs. Random number generators have now evolved from simple dices to electronic circuits and algorithms. Accordingly, the ability to distinguish between random and non-random numbers has become more difficult. Furthermore, whereas in the past dices were loaded in order to increase winning chances, it is now possible to influence the outcome of random number generators. In consequence, this subject is still very much an issue and has recently made the headlines. Indeed, there was talks about the PS3 game console which generates constant random numbers and redundant distribution of secret keys on the internet. This thesis presents a study of several generators as well as different means to perturb them. It shows the inherent defects of their conceptions and possible consequences of their failure when they are embedded inside security components. Moreover, this work highlights problems yet to be solved concerning the testing of random numbers and the post-processing eliminating bias in these numbers distribution. (author) [fr
Qualitative Resting Coronary Pressure Wave Form Analysis to Predict Fractional Flow Reserve.
Matsumura, Mitsuaki; Maehara, Akiko; Johnson, Nils P; Fearon, William F; De Bruyne, Bernard; Oldroyd, Keith G; Pijls, Nico H J; Jenkins, Paul; Ali, Ziad A; Mintz, Gary S; Stone, Gregg W; Jeremias, Allen
2018-03-27
To evaluate the predictability of resting distal coronary pressure wave forms for fractional flow reserve (FFR). Resting coronary wave forms were qualitatively evaluated for the presence of (i) dicrotic notch; (ii) diastolic dipping; and (iii) ventricularization. In a development cohort (n=88) a scoring system was developed that was then applied to a validation cohort (n=428) using a multivariable linear regression model to predict FFR and receiver operating characteristics (ROC) to predict FFR ≤0.8. In the development cohort, all 3 qualitative parameters were independent predictors of FFR. However, in a multivariable linear regression model in the validation cohort, qualitative wave form analysis did not further improve the ability of resting distal coronary to aortic pressure ratio (Pd/Pa) (p=0.80) or instantaneous wave-free ratio (iFR) (p=0.26) to predict FFR. Using ROC, the area under the curve of resting Pd/Pa (0.86 versus 0.86, P=0.08) and iFR (0.86 versus 0.86, P=0.26) did not improve by adding qualitative analysis. Qualitative coronary wave form analysis showed moderate classification agreement in predicting FFR but did not add substantially to the resting pressure gradients Pd/Pa and iFR; however, when discrepancies between quantitative and qualitative analyses are observed, artifact or pressure drift should be considered.
Zhang, Hui; Zheng, Rongqin; Qian, Xiaoxian; Zhang, Chengxi; Hao, Baoshun; Huang, Zeping; Wu, Tao
2014-03-01
Wave intensity analysis (WIA) of the carotid artery was conducted to determine the changes that occur in left ventricular systolic function after administration of doxorubicin in rabbits. Each randomly selected rabbit was subject to routine ultrasound, WIA of the carotid artery, cardiac catheterization and pathologic examination every week and was followed for 16 wk. The first positive peak (WI1) of the carotid artery revealed that left ventricular systolic dysfunction occurred earlier than conventional indexes of heart function. WI1 was highly, positively correlated with the maximum rate of rise in left ventricular pressure in cardiac catheterization (r = 0.94, p function, and the result is highly consistent with cardiac catheterization findings and the apoptosis index of myocardial cells. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.
Near-Field Ground Motion Modal versus Wave Propagation Analysis
Directory of Open Access Journals (Sweden)
Artur Cichowicz
2010-01-01
Full Text Available The response spectrum generally provides a good estimate of the global displacement and acceleration demand of far-field ground motion on a structure. However, it does not provide accurate information on the local shape or internal deformation of the response of the structure. Near-field pulse-like ground motion will propagate through the structure as waves, causing large, localized deformation. Therefore, the response spectrum alone is not a sufficient representation of near-field ground motion features. Results show that the drift-response technique based on a continuous shear-beam model has to be employed here to estimate structure-demand parameters when structure is exposed to the pulse like ground motion. Conduced modeling shows limited applicability of the drift spectrum based on the SDOF approximation. The SDOF drift spectrum approximation can only be applied to structures with smaller natural periods than the dominant period of the ground motion. For periods larger than the dominant period of ground motion the SDOF drift spectra model significantly underestimates maximum deformation. Strong pulse-type motions are observed in the near-source region of large earthquakes; however, there is a lack of waveforms collected from small earthquakes at very close distances that were recorded underground in mines. The results presented in this paper are relevant for structures with a height of a few meters, placed in an underground excavation. The strong ground motion sensors recorded mine-induced earthquakes in a deep gold mine, South Africa. The strongest monitored horizontal ground motion was caused by an event of magnitude 2 at a distance of 90 m with PGA 123 m/s2, causing drifts of 0.25%–0.35%. The weak underground motion has spectral characteristics similar to the strong ground motion observed on the earth's surface; the drift spectrum has a maximum value less than 0.02%.
A Critical Analysis and Validation of the Accuracy of Wave Overtopping Prediction Formulae for OWECs
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David Gallach-Sánchez
2018-01-01
Full Text Available The development of wave energy devices is growing in recent years. One type of device is the overtopping wave energy converter (OWEC, for which the knowledge of the wave overtopping rates is a basic and crucial aspect in their design. In particular, the most interesting range to study is for OWECs with steep slopes to vertical walls, and with very small freeboards and zero freeboards where the overtopping rate is maximized, and which can be generalized as steep low-crested structures. Recently, wave overtopping prediction formulae have been published for this type of structures, although their accuracy has not been fully assessed, as the overtopping data available in this range is scarce. We performed a critical analysis of the overtopping prediction formulae for steep low-crested structures and the validation of the accuracy of these formulae, based on new overtopping data for steep low-crested structures obtained at Ghent University. This paper summarizes the existing knowledge about average wave overtopping, describes the physical model tests performed, analyses the results and compares them to existing prediction formulae. The new dataset extends the wave overtopping data towards vertical walls and zero freeboard structures. In general, the new dataset validated the more recent overtopping formulae focused on steep slopes with small freeboards, although the formulae are underpredicting the average overtopping rates for very small and zero relative crest freeboards.
Shock Mechanism Analysis and Simulation of High-Power Hydraulic Shock Wave Simulator
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Xiaoqiu Xu
2017-01-01
Full Text Available The simulation of regular shock wave (e.g., half-sine can be achieved by the traditional rubber shock simulator, but the practical high-power shock wave characterized by steep prepeak and gentle postpeak is hard to be realized by the same. To tackle this disadvantage, a novel high-power hydraulic shock wave simulator based on the live firing muzzle shock principle was proposed in the current work. The influence of the typical shock characteristic parameters on the shock force wave was investigated via both theoretical deduction and software simulation. According to the obtained data compared with the results, in fact, it can be concluded that the developed hydraulic shock wave simulator can be applied to simulate the real condition of the shocking system. Further, the similarity evaluation of shock wave simulation was achieved based on the curvature distance, and the results stated that the simulation method was reasonable and the structural optimization based on software simulation is also beneficial to the increase of efficiency. Finally, the combination of theoretical analysis and simulation for the development of artillery recoil tester is a comprehensive approach in the design and structure optimization of the recoil system.
Analysis and Synthesis of WAVCIS Data for Characteristics of Waves and Currents on Louisiana Coast
Li, C.; Gibson, B.; Huang, W.; Luo, Y.; Milan, B.
2017-12-01
Texas-Louisiana coastal currents have been studied before, with a generally well-known pattern that is quasi steady except during the summer when it may weaken or reverse briefly. In the past decade, lot more efforts have been made and there is a large quantity of current velocity data accumulated. Among these data are those from the long-term mooring observations from the Wave Current-Surge Information System (WAVCIS), with a focus on the Louisiana coastal waters. More specifically, velocity and wave time series from current meters and pressure sensors or directional wave sensors at several locations on Louisiana coast provided unique opportunity to analyze and synthesize the characteristics of waves and currents on both east and west side of the Birdfoot Delta. In this study, we assembled all available WAVCIS data for a thorough analysis and synthesis of the characteristics of waves and coastal current in the area as a function of weather during different seasons. Year-to-year variabilities and seasonal variations are discussed. Spectrum, harmonic, and EOF analyses allowed a description and comparison of circulation patterns, wave and flow energy regimes, vertical shear of horizontal flows, tidal characteristics, synoptic weather effect, and severe weather impact. We provide basic statistics, as well as classifications of type of flows/circulations, and the major mechanisms that contribute to the variability.
Broyd, Christopher J; Nijjer, Sukhjinder; Sen, Sayan; Petraco, Ricardo; Jones, Siana; Al-Lamee, Rasha; Foin, Nicolas; Al-Bustami, Mahmud; Sethi, Amarjit; Kaprielian, Raffi; Ramrakha, Punit; Khan, Masood; Malik, Iqbal S; Francis, Darrel P; Parker, Kim; Hughes, Alun D; Mikhail, Ghada W; Mayet, Jamil; Davies, Justin E
2016-03-01
Wave intensity analysis (WIA) has found particular applicability in the coronary circulation where it can quantify traveling waves that accelerate and decelerate blood flow. The most important wave for the regulation of flow is the backward-traveling decompression wave (BDW). Coronary WIA has hitherto always been calculated from invasive measures of pressure and flow. However, recently it has become feasible to obtain estimates of these waveforms noninvasively. In this study we set out to assess the agreement between invasive and noninvasive coronary WIA at rest and measure the effect of exercise. Twenty-two patients (mean age 60) with unobstructed coronaries underwent invasive WIA in the left anterior descending artery (LAD). Immediately afterwards, noninvasive LAD flow and pressure were recorded and WIA calculated from pulsed-wave Doppler coronary flow velocity and central blood pressure waveforms measured using a cuff-based technique. Nine of these patients underwent noninvasive coronary WIA assessment during exercise. A pattern of six waves were observed in both modalities. The BDW was similar between invasive and noninvasive measures [peak: 14.9 ± 7.8 vs. -13.8 ± 7.1 × 10(4) W·m(-2)·s(-2), concordance correlation coefficient (CCC): 0.73, P Exercise increased the BDW: at maximum exercise peak BDW was -47.0 ± 29.5 × 10(4) W·m(-2)·s(-2) (P Physiological Society.
Security Analysis of Randomize-Hash-then-Sign Digital Signatures
DEFF Research Database (Denmark)
Gauravaram, Praveen; Knudsen, Lars Ramkilde
2012-01-01
At CRYPTO 2006, Halevi and Krawczyk proposed two randomized hash function modes and analyzed the security of digital signature algorithms based on these constructions. They showed that the security of signature schemes based on the two randomized hash function modes relies on properties similar...... functions, such as for the Davies-Meyer construction used in the popular hash functions such as MD5 designed by Rivest and the SHA family of hash functions designed by the National Security Agency (NSA), USA and published by NIST in the Federal Information Processing Standards (FIPS). We show an online...... 800-106. We discuss some important applications of our attacks and discuss their applicability on signature schemes based on hash functions with ‘built-in’ randomization. Finally, we compare our attacks on randomize-hash-then-sign schemes with the generic forgery attacks on the standard hash...
Migration velocity analysis using pre-stack wave fields
Alkhalifah, Tariq Ali; Wu, Zedong
2016-01-01
Using both image and data domains to perform velocity inversion can help us resolve the long and short wavelength components of the velocity model, usually in that order. This translates to integrating migration velocity analysis into full waveform
Analysis and classification of ECG-waves and rhythms using circular statistics and vector strength
Directory of Open Access Journals (Sweden)
Janßen Jan-Dirk
2017-09-01
Full Text Available The most common way to analyse heart rhythm is to calculate the RR-interval and the heart rate variability. For further evaluation, descriptive statistics are often used. Here we introduce a new and more natural heart rhythm analysis tool that is based on circular statistics and vector strength. Vector strength is a tool to measure the periodicity or lack of periodicity of a signal. We divide the signal into non-overlapping window segments and project the detected R-waves around the unit circle using the complex exponential function and the median RR-interval. In addition, we calculate the vector strength and apply circular statistics as wells as an angular histogram on the R-wave vectors. This approach enables an intuitive visualization and analysis of rhythmicity. Our results show that ECG-waves and rhythms can be easily visualized, analysed and classified by circular statistics and vector strength.
Analysis of entropy extraction efficiencies in random number generation systems
Wang, Chao; Wang, Shuang; Chen, Wei; Yin, Zhen-Qiang; Han, Zheng-Fu
2016-05-01
Random numbers (RNs) have applications in many areas: lottery games, gambling, computer simulation, and, most importantly, cryptography [N. Gisin et al., Rev. Mod. Phys. 74 (2002) 145]. In cryptography theory, the theoretical security of the system calls for high quality RNs. Therefore, developing methods for producing unpredictable RNs with adequate speed is an attractive topic. Early on, despite the lack of theoretical support, pseudo RNs generated by algorithmic methods performed well and satisfied reasonable statistical requirements. However, as implemented, those pseudorandom sequences were completely determined by mathematical formulas and initial seeds, which cannot introduce extra entropy or information. In these cases, “random” bits are generated that are not at all random. Physical random number generators (RNGs), which, in contrast to algorithmic methods, are based on unpredictable physical random phenomena, have attracted considerable research interest. However, the way that we extract random bits from those physical entropy sources has a large influence on the efficiency and performance of the system. In this manuscript, we will review and discuss several randomness extraction schemes that are based on radiation or photon arrival times. We analyze the robustness, post-processing requirements and, in particular, the extraction efficiency of those methods to aid in the construction of efficient, compact and robust physical RNG systems.
Lai, Ta-Wei; Ma, Hsiao-Li; Lee, Meng-Shiunn; Chen, Po-Ming; Ku, Ming-Chou
2018-01-01
Objectives: Extracorporeal shockwave therapy (ESWT) and corticosteroid injection (CSI) are treatment options for plantar fasciitis. Their clinical outcome comparison remains a debate. Also, the thickness changes of the plantar fascia on objective evaluation under the medium energy ESWT and CSI therapy are elusive. Methods: A total of 97 patients with chronic plantar fasciitis were enrolled in the randomized prospective trial. Forty-seven patients received extracorporeal shock wave therapy (ESWT), and fifty patients received corticosteroid injection (CSI). The thickness of the plantar fascia was evaluated respectively before ESWT and CSI, and at the 4th and 12th week after ESWT and CSI by ultrasonography. Pain level and clinical outcomes were recorded using visual analogue scale (VAS) and 100-points scoring systems. Correlation analysis was performed between the thickness change and clinical outcome. Results: Under ultrasonography, we observed more increase of plantar fascia thickness of ESWT group than CSI group at 4th week (p=0.048). VAS of plantar fasciitis patients receiving ESWT was lower than those who received corticosteroid injection (0.001 and pplantar fascia thickness at 4th week was positively correlated with the decrease of VAS score at 12th week follow-up (R=0.302, P=0.039). Conclusions: At 4th week after treatment, the thickness of plantar fascia increased. Then it decreased gradually, but not to the baseline at 12th week. On the pain level outcome at 12th week, extracorporeal shockwave therapy (ESWT) was more efficient than corticosteroid injection (CSI) on chronic plantar fasciitis. The more change of plantar fascia after ESWT, the more efficient on clinical outcome. PMID:29504578
Li, Siying; Koch, Gary G; Preisser, John S; Lam, Diana; Sanchez-Kam, Matilde
2017-01-01
Dichotomous endpoints in clinical trials have only two possible outcomes, either directly or via categorization of an ordinal or continuous observation. It is common to have missing data for one or more visits during a multi-visit study. This paper presents a closed form method for sensitivity analysis of a randomized multi-visit clinical trial that possibly has missing not at random (MNAR) dichotomous data. Counts of missing data are redistributed to the favorable and unfavorable outcomes mathematically to address possibly informative missing data. Adjusted proportion estimates and their closed form covariance matrix estimates are provided. Treatment comparisons over time are addressed with Mantel-Haenszel adjustment for a stratification factor and/or randomization-based adjustment for baseline covariables. The application of such sensitivity analyses is illustrated with an example. An appendix outlines an extension of the methodology to ordinal endpoints.
Numerical analysis of regular waves over an onshore oscillating water column
Energy Technology Data Exchange (ETDEWEB)
Davyt, D.P.; Teixeira, P.R.F. [Universidade Federal do Rio Grande (FURG), RS (Brazil)], E-mail: pauloteixeira@furg.br; Ramalhais, R. [Universidade Nova de Lisboa, Caparica (Portugal). Fac. de Ciencias e Tecnologia; Didier, E. [Laboratorio Nacional de Engenharia Civil, Lisboa (Portugal)], E-mail: edidier@lnec.pt
2010-07-01
The potential of wave energy along coastal areas is a particularly attractive option in regions of high latitude, such as the coasts of northern Europe, North America, New Zealand, Chile and Argentina where high densities of annual average wave energy are found (typically between 40 and 100 kW/m of wave front). Power estimated in the south of Brazil is 30kW/m, creating a possible alternative of source energy in the region. There are many types and designs of equipment to capture energy from waves under analysis, such as the oscillating water column type (OWC) which has been one of the first to be developed and installed at sea. Despite being one of the most analyzed wave energy converter devices, there are few case studies using numerical simulation. In this context, the numerical analysis of regular waves over an onshore OWC is the main objective of this paper. The numerical models FLUINCO and FLUENT are used for achieving this goal. The FLUINCO model is based on RANS equations which are discretized using the two-step semi-implicit Taylor-Galerkin method. An arbitrary Lagrangian Eulerian formulation is used to enable the solution of problems involving free surface movements. The FLUENT code (version 6.3.26) is based on the finite volume method to solve RANS equations. Volume of Fluid method (VOF) is used for modeling free surface flows. Time integration is achieved by a second order implicit scheme, momentum equations are discretized using MUSCL scheme and HRIC (High Resolution Interface Capturing) scheme is used for convective term of VOF transport equation. The case study consists of a 10.m deep channel with a 10 m wide chamber at its end. One meter high waves with different periods are simulated. Comparisons between FLUINCO and FLUENT results are presented. Free surface elevation inside the chamber; velocity distribution and streamlines; amplification factor (relation between wave height inside the chamber and incident wave height); phase angle (angular
Naumenko, Natalya F.
2014-09-01
A numerical technique characterized by a unified approach for the analysis of different types of acoustic waves utilized in resonators in which a periodic metal grating is used for excitation and reflection of such waves is described. The combination of the Finite Element Method analysis of the electrode domain with the Spectral Domain Analysis (SDA) applied to the adjacent upper and lower semi-infinite regions, which may be multilayered and include air as a special case of a dielectric material, enables rigorous simulation of the admittance in resonators using surface acoustic waves, Love waves, plate modes including Lamb waves, Stonely waves, and other waves propagating along the interface between two media, and waves with transient structure between the mentioned types. The matrix formalism with improved convergence incorporated into SDA provides fast and robust simulation for multilayered structures with arbitrary thickness of each layer. The described technique is illustrated by a few examples of its application to various combinations of LiNbO3, isotropic silicon dioxide and silicon with a periodic array of Cu electrodes. The wave characteristics extracted from the admittance functions change continuously with the variation of the film and plate thicknesses over wide ranges, even when the wave nature changes. The transformation of the wave nature with the variation of the layer thicknesses is illustrated by diagrams and contour plots of the displacements calculated at resonant frequencies.
Damage detection using piezoelectric transducers and the Lamb wave approach: I. System analysis
International Nuclear Information System (INIS)
Wang, X; Lu, Y; Tang, J
2008-01-01
Structural damage detection using piezoelectric transducers and the Lamb wave approach has been under intensive investigations. A commonly pursued topic is the selection of system parameters such that the detection performance can be optimized. Previous studies have indicated that the excitation center frequency plays a critical role, and suggested use of the 'sweet spot' frequency to maximize the peak wave amplitude ratio between the S 0 and the A 0 modes. In this paper, the analytical formulation of Lamb wave propagation on a narrow-strip beam excited and sensed by piezoelectric transducers is outlined first. Then, the antisymmetric and symmetric contents of the wave propagation response are analyzed in detail with respect to system parameters. In particular, the parametric influence on the 'sweet spot' frequency is investigated systematically. The complicated interaction of the wave components with respect to damage is illustrated through case studies. The analytical study is supported by numerical analysis using the finite element method and by experimental investigation. This research provides the mechanistic basis for robust damage detection using data processing and statistical analysis tools which is the focus of the second paper of this two-paper series
Energy Technology Data Exchange (ETDEWEB)
Tom, Nathan; Lawson, Michael; Yu, Yi-Hsiang; Wright, Alan
2015-09-09
The aim of this paper is to present a novel wave energy converter device concept that is being developed at the National Renewable Energy Laboratory. The proposed concept combines an oscillating surge wave energy converter with active control surfaces. These active control surfaces allow for the device geometry to be altered, which leads to changes in the hydrodynamic properties. The device geometry will be controlled on a sea state time scale and combined with wave-to-wave power-take-off control to maximize power capture, increase capacity factor, and reduce design loads. The paper begins with a traditional linear frequency domain analysis of the device performance. Performance sensitivity to foil pitch angle, the number of activated foils, and foil cross section geometry is presented to illustrate the current design decisions; however, it is understood from previous studies that modeling of current oscillating wave energy converter designs requires the consideration of nonlinear hydrodynamics and viscous drag forces. In response, a nonlinear model is presented that highlights the shortcomings of the linear frequency domain analysis and increases the precision in predicted performance.
Physics Structure Analysis of Parallel Waves Concept of Physics Teacher Candidate
International Nuclear Information System (INIS)
Sarwi, S; Linuwih, S; Supardi, K I
2017-01-01
The aim of this research was to find a parallel structure concept of wave physics and the factors that influence on the formation of parallel conceptions of physics teacher candidates. The method used qualitative research which types of cross-sectional design. These subjects were five of the third semester of basic physics and six of the fifth semester of wave course students. Data collection techniques used think aloud and written tests. Quantitative data were analysed with descriptive technique-percentage. The data analysis technique for belief and be aware of answers uses an explanatory analysis. Results of the research include: 1) the structure of the concept can be displayed through the illustration of a map containing the theoretical core, supplements the theory and phenomena that occur daily; 2) the trend of parallel conception of wave physics have been identified on the stationary waves, resonance of the sound and the propagation of transverse electromagnetic waves; 3) the influence on the parallel conception that reading textbooks less comprehensive and knowledge is partial understanding as forming the structure of the theory. (paper)
Sorghum cobalt analysis on not determined wave length with atomic ...
African Journals Online (AJOL)
Jane
2011-08-24
Aug 24, 2011 ... 2SamAn Inc, Nonsan, ChungcheongNam-do, Republic of Korea. 3Echo Information ... concentrations of 0.1 to 7 ppm can be quantitated. *Corresponding ... Eleven samples were air-dried and milled for Co analysis using an.
Using High Speed Smartphone Cameras and Video Analysis Techniques to Teach Mechanical Wave Physics
Bonato, Jacopo; Gratton, Luigi M.; Onorato, Pasquale; Oss, Stefano
2017-01-01
We propose the use of smartphone-based slow-motion video analysis techniques as a valuable tool for investigating physics concepts ruling mechanical wave propagation. The simple experimental activities presented here, suitable for both high school and undergraduate students, allows one to measure, in a simple yet rigorous way, the speed of pulses…
Analysis of 38 GHz mmWave Propagation Characteristics of Urban Scenarios
DEFF Research Database (Denmark)
Rodriguez Larrad, Ignacio; Nguyen, Huan Cong; Sørensen, Troels Bundgaard
2015-01-01
The 38 GHz mm-wave frequency band is a strong candidate for the future deployment of wireless systems. Compared to lower frequency bands, propagation in the 38 GHz band is relatively unexplored for access networks in urban scenarios. This paper presents a detailed measurement-based analysis of ur...
Tool to estimate optical metrics from summary wave-front analysis data in the human eye
Jansonius, Nomdo M.
Purpose Studies in the field of cataract and refractive surgery often report only summary wave-front analysis data data that are too condensed to allow for a retrospective calculation of metrics relevant to visual perception. The aim of this study was to develop a tool that can be used to estimate
Using Musical Intervals to Demonstrate Superposition of Waves and Fourier Analysis
LoPresto, Michael C.
2013-01-01
What follows is a description of a demonstration of superposition of waves and Fourier analysis using a set of four tuning forks mounted on resonance boxes and oscilloscope software to create, capture and analyze the waveforms and Fourier spectra of musical intervals.
Modal Analysis Based on the Random Decrement Transform
DEFF Research Database (Denmark)
Asmussen, J. C.; Brincker, Rune; Ibrahim, S. R.
of this paper is to present a state-of-the-art description of the Random Decrement technique where the statistical theory is outlined and examples are given. But also new results such as estimation of frequency response functions and quality assessment are introduced. Special attention is given......During the last years several papers utilizing the Random Decrement transform as a basis for extraction of modal parameters from the response of linear systems subjected to unknown ambient loads have been presented. Although the Random Decrement technique was developed in a decade starting from...... the introduktion in 1968 the technique seems still to be attractive. This is probably due to the simplicity and the speed of the algorithm and the fact that the theory of the technique has been extended by introducing statistical measures such as correlation functions or spectral densities. The purpose...
Lagrangian analysis of two-phase hydrodynamic and nuclear-coupled density-wave oscillations
International Nuclear Information System (INIS)
Lahey, R.T. Jr.; Yadigaroglu, G.
1974-01-01
The mathematical technique known as the ''method of characteristics'' has been used to construct an exact, analytical solution to predict the onset of density-wave oscillations in diabatic two-phase systems, such as Boiling Water Nuclear Reactors (BWR's). Specifically, heater wall dynamics, boiling boundary dynamics and nuclear kinetics have been accounted for in this analysis. Emphasis is placed on giving the reader a clear physical understanding of the phenomena of two-phase density-wave oscillations. Explanations are presented in terms of block diagram logic, and phasor representations of the various pressure drop perturbations are given. (U.S.)
O'Dea, A.; Haller, M. C.
2013-12-01
As concerns over the use of fossil fuels increase, more and more effort is being put into the search for renewable and reliable sources of energy. Developments in ocean technologies have made the extraction of wave energy a promising alternative. Commercial exploitation of wave energy would require the deployment of arrays of Wave Energy Converters (WECs) that include several to hundreds of individual devices. Interactions between WECs and ocean waves result in both near-field and far-field changes in the incident wave field, including a significant decrease in wave height and a redirection of waves in the lee of the array, referred to as the wave shadow. Nearshore wave height and direction are directly related to the wave radiation stresses that drive longshore currents, rip currents and nearshore sediment transport, which suggests that significant far-field changes in the wave field due to WEC arrays could have an impact on littoral processes. The goal of this study is to investigate the changes in nearshore wave conditions and radiation stress forcing as a result of an offshore array of point-absorber type WECs using a nested SWAN model, and to determine how array size, configuration, spacing and distance from shore influence these changes. The two sites of interest are the Northwest National Marine Renewable Energy Center (NNMREC) test sites off the coast of Newport Oregon, the North Energy Test Site (NETS) and the South Energy Test Site (SETS). NETS and SETS are permitted wave energy test sites located approximately 4 km and 10 km offshore, respectively. Twenty array configurations are simulated, including 5, 10, 25, 50 and 100 devices in two and three staggered rows in both closely spaced (three times the WEC diameter) and widely spaced (ten times the WEC diameter) arrays. Daily offshore wave spectra are obtained from a regional WAVEWATCH III hindcast for 2011, which are then propagated across the continental shelf using SWAN. Arrays are represented in SWAN
Ahlen, Johan; Lenhard, Fabian; Ghaderi, Ata
2015-12-01
Although under-diagnosed, anxiety and depression are among the most prevalent psychiatric disorders in children and adolescents, leading to severe impairment, increased risk of future psychiatric problems, and a high economic burden to society. Universal prevention may be a potent way to address these widespread problems. There are several benefits to universal relative to targeted interventions because there is limited knowledge as to how to screen for anxiety and depression in the general population. Earlier meta-analyses of the prevention of depression and anxiety symptoms among children suffer from methodological inadequacies such as combining universal, selective, and indicated interventions in the same analyses, and comparing cluster-randomized trials with randomized trials without any correction for clustering effects. The present meta-analysis attempted to determine the effectiveness of universal interventions to prevent anxiety and depressive symptoms after correcting for clustering effects. A systematic search of randomized studies in PsychINFO, Cochrane Library, and Google Scholar resulted in 30 eligible studies meeting inclusion criteria, namely peer-reviewed, randomized or cluster-randomized trials of universal interventions for anxiety and depressive symptoms in school-aged children. Sixty-three percent of the studies reported outcome data regarding anxiety and 87 % reported outcome data regarding depression. Seventy percent of the studies used randomization at the cluster level. There were small but significant effects regarding anxiety (.13) and depressive (.11) symptoms as measured at immediate posttest. At follow-up, which ranged from 3 to 48 months, effects were significantly larger than zero regarding depressive (.07) but not anxiety (.11) symptoms. There was no significant moderation effect of the following pre-selected variables: the primary aim of the intervention (anxiety or depression), deliverer of the intervention, gender distribution
Migration velocity analysis using pre-stack wave fields
Alkhalifah, Tariq Ali
2016-08-25
Using both image and data domains to perform velocity inversion can help us resolve the long and short wavelength components of the velocity model, usually in that order. This translates to integrating migration velocity analysis into full waveform inversion. The migration velocity analysis part of the inversion often requires computing extended images, which is expensive when using conventional methods. As a result, we use pre-stack wavefield (the double-square-root formulation) extrapolation, which includes the extended information (subsurface offsets) naturally, to make the process far more efficient and stable. The combination of the forward and adjoint pre-stack wavefields provides us with update options that can be easily conditioned to improve convergence. We specifically use a modified differential semblance operator to split the extended image into a residual part for classic differential semblance operator updates and the image (Born) modelling part, which provides reflections for higher resolution information. In our implementation, we invert for the velocity and the image simultaneously through a dual objective function. Applications to synthetic examples demonstrate the features of the approach.
Finite Element Analysis of the Propagation of Acoustic Waves Along Waveguides Immersed in Water
Hladky-Hennion, A.-C.; Langlet, P.; de Billy, M.
1997-03-01
The finite element approach has previously been used, with the help of the ATILA code, to model the propagation of acoustic waves in waveguides [A.-C. Hladky-Hennion, Journal of Sound and Vibration, 194,119-136 (1996)]. In this paper an extension of the technique to the analysis of the propagation of acoustic waves in immersed waveguides is presented. In the proposed approach, the problem is reduced to a bidimensional problem, in which only the cross-section of the guide and the surrounding fluid domain are meshed by using finite elements. Then, wedges the top angles of which vary, are studied and the finite element results of the wedge wave speed are compared with experimental results. Finally, the conclusion indicates a way to extend this approach to waveguides of any cross-section.
Design and Analysis for a Floating Oscillating Surge Wave Energy Converter: Preprint
Energy Technology Data Exchange (ETDEWEB)
Yu, Y. H.; Li, Y.; Hallett, K.; Hotimsky, C.
2014-03-01
This paper presents a recent study on the design and analysis of an oscillating surge wave energy converter. A successful wave energy conversion design requires the balance between the design performance and cost. The cost of energy is often used as the metric to judge the design of the wave energy conversion system. It is often determined based on the device power performance, the cost for manufacturing, deployment, operation and maintenance, as well as the effort to ensure the environmental compliance. The objective of this study is to demonstrate the importance of a cost driven design strategy and how it can affect a WEC design. Three oscillating surge wave energy converter (OSWEC) designs were used as the example. The power generation performance of the design was modeled using a time-domain numerical simulation tool, and the mass properties of the design were determined based on a simple structure analysis. The results of those power performance simulations, the structure analysis and a simple economic assessment were then used to determine the cost-efficiency of selected OSWEC designs. Finally, a discussion on the environmental barrier, integrated design strategy and the key areas that need further investigation is also presented.
Random Decrement and Regression Analysis of Traffic Responses of Bridges
DEFF Research Database (Denmark)
Asmussen, J. C.; Ibrahim, S. R.; Brincker, Rune
1996-01-01
The topic of this paper is the estimation of modal parameters from ambient data by applying the Random Decrement technique. The data fro the Queensborough Bridge over the Fraser River in Vancouver, Canada have been applied. The loads producing the dynamic response are ambient, e. g. wind, traffic...
Random Decrement and Regression Analysis of Traffic Responses of Bridges
DEFF Research Database (Denmark)
Asmussen, J. C.; Ibrahim, S. R.; Brincker, Rune
The topic of this paper is the estimation of modal parameters from ambient data by applying the Random Decrement technique. The data from the Queensborough Bridge over the Fraser River in Vancouver, Canada have been applied. The loads producing the dynamic response are ambient, e.g. wind, traffic...
Infinite conditional random fields for human behavior analysis
Bousmalis, Konstantinos; Zafeiriou, Stefanos; Morency, Louis-Philippe; Pantic, Maja
Hidden conditional random fields (HCRFs) are discriminative latent variable models that have been shown to successfully learn the hidden structure of a given classification problem (provided an appropriate validation of the number of hidden states). In this brief, we present the infinite HCRF
Software package for analysis of completely randomized block design
African Journals Online (AJOL)
This study is to design and develop statistical software (package), OYSP1.0 which conveniently accommodates and analyzes large mass of data emanating from experimental designs, in particular, completely Randomized Block design. Visual Basic programming is used in the design. The statistical package OYSP 1.0 ...
International Nuclear Information System (INIS)
Oscarsson, T.E.; Roennmark, K.G.
1990-01-01
In this paper the authors present an investigation of low-frequency waves observed on auroral field lines below the acceleration region by the Swedish satellite Viking. The measured frequency spectra are peaked at half the local proton gyrofrequency, and the waves are observed in close connection with precipitating electrons. In order to obtain information about the distribution of wave energy in wave vector space, they reconstruct the wave distribution function (WDF) from observed spectral densities. They use a new scheme that allows them to reconstruct simultaneously the WDF over a broad frequency band. The method also makes it possible to take into account available particle observations as well as Doppler shifts caused by the relative motion between the plasma and the satellite. The distribution of energy in wave vector space suggested by the reconstructed WDF is found to be consistent with what is expected from a plasma instability driven by the observed precipitating electrons. Furthermore, by using UV images obtained on Viking, they demonstrate that the wave propagation directions indicated by the reconstructed WDFs are consistent with a simple model of the presumed wave source in the electron precipitation region
Analysis of Longitudinal Waves in Rod-Type Piezoelectric Phononic Crystals
Directory of Open Access Journals (Sweden)
Longfei Li
2016-04-01
Full Text Available Phononic crystals can be used to control elastic waves due to their frequency bands. This paper analyzes the passive and active control as well as the dispersion properties of longitudinal waves in rod-type piezoelectric phononic crystals over large frequency ranges. Based on the Love rod theory for modeling the longitudinal wave motions in the constituent rods and the method of reverberation-ray matrix (MRRM for deriving the member transfer matrices of the constituent rods, a modified transfer matrix method (MTMM is proposed for the analysis of dispersion curves by combining with the Floquet–Bloch principle and for the calculation of transmission spectra. Numerical examples are provided to validate the proposed MTMM for analyzing the band structures in both low and high frequency ranges. The passive control of longitudinal-wave band structures is studied by discussing the influences of the electrode’s thickness, the Poisson’s effect and the elastic rod inserts in the unit cell. The influences of electrical boundaries (including electric-open, applied electric capacity, electric-short and applied feedback control conditions on the band structures are investigated to illustrate the active control scheme. From the calculated comprehensive frequency spectra over a large frequency range, the dispersion properties of the characteristic longitudinal waves in rod-type piezoelectric phononic crystals are summarized.
Multichannel analysis of the surface waves of earth materials in some parts of Lagos State, Nigeria
Directory of Open Access Journals (Sweden)
Adegbola R.B.
2016-09-01
Full Text Available We present a method that utilizes multichannel analysis of surface waves (MASW, which was used to measure shear wave velocities, with a view to establishing the probable causes of road failure, subsidence and weakening of structures in some local government areas in Lagos, Nigeria. MASW data were acquired using a 24-channel seismograph. The acquired data were processed and transformed into a two-dimensional (2-D structure reflective of the depth and surface wave velocity distribution within a depth of 0–15 m beneath the surface using SURFSEIS software. The shear wave velocity data were compared with other geophysical/ borehole data that were acquired along the same profile. The comparison and correlation illustrate the accuracy and consistency of MASW-derived shear wave velocity profiles. Rigidity modulus and N-value were also generated. The study showed that the low velocity/ very low velocity data are reflective of organic clay/ peat materials and thus likely responsible for the failure, subsidence and weakening of structures within the study areas.
Directory of Open Access Journals (Sweden)
Franz Konstantin Fuss
2013-09-01
Full Text Available This paper is a theoretical analysis of mirror tilt in a Michelson interferometer and its effect on the radiant flux over the active area of a rectangular photodetector or image sensor pixel. It is relevant to sensor applications using homodyne interferometry where these opto-electronic devices are employed for partial fringe counting. Formulas are derived for radiant flux across the detector for variable location within the fringe pattern and with varying wave front angle. The results indicate that the flux is a damped sine function of the wave front angle, with a decay constant of the ratio of wavelength to detector width. The modulation amplitude of the dynamic fringe pattern reduces to zero at wave front angles that are an integer multiple of this ratio and the results show that the polarity of the radiant flux changes exclusively at these multiples. Varying tilt angle causes radiant flux oscillations under an envelope curve, the frequency of which is dependent on the location of the detector with the fringe pattern. It is also shown that a fringe count of zero can be obtained for specific photodetector locations and wave front angles where the combined effect of fringe contraction and fringe tilt can have equal and opposite effects. Fringe tilt as a result of a wave front angle of 0.05° can introduce a phase measurement difference of 16° between a photodetector/pixel located 20 mm and one located 100 mm from the optical origin.
Born reflection kernel analysis and wave-equation reflection traveltime inversion in elastic media
Wang, Tengfei
2017-08-17
Elastic reflection waveform inversion (ERWI) utilize the reflections to update the low and intermediate wavenumbers in the deeper part of model. However, ERWI suffers from the cycle-skipping problem due to the objective function of waveform residual. Since traveltime information relates to the background model more linearly, we use the traveltime residuals as objective function to update background velocity model using wave equation reflected traveltime inversion (WERTI). The reflection kernel analysis shows that mode decomposition can suppress the artifacts in gradient calculation. We design a two-step inversion strategy, in which PP reflections are firstly used to invert P wave velocity (Vp), followed by S wave velocity (Vs) inversion with PS reflections. P/S separation of multi-component seismograms and spatial wave mode decomposition can reduce the nonlinearity of inversion effectively by selecting suitable P or S wave subsets for hierarchical inversion. Numerical example of Sigsbee2A model validates the effectiveness of the algorithms and strategies for elastic WERTI (E-WERTI).
Two-dimensional kinetic analysis on the ionization waves in a low current discharge
International Nuclear Information System (INIS)
Yamazaki, Tsutomu; Fujii, Masaharu; Noda, Shozou; Miura, Kousuke; Imazu, Shingo.
1982-01-01
In the research on the ionization waves produced in the positive column in a low pressure discharge, theoretical analyses have been made since long ago using mainly the fluid theory. However, the experimental properties that cannot be explained with the fluid theory have been found lately. For example, it has been shown experimentally that the product of longitudinal electric field E and the wavelength lambda of ionization waves becomes some specific values depending on the kinds of gas as one of the characteristics of the ionization waves produced in the positive column plasma in rare gas glow discharge, but these specific values of E-lambda cannot be explained with the fluid theory. In this paper, the perturbation component of electron energy distribution function accompanying ionization waves was derived from a two-dimensional Boltzmann equation which takes the radial non-uniformity into account, to consider the E-lambda values of ionization waves from the relative equation between electron density and the perturbation component of an electric field. The following results were obtained. The relative equation between electron density and the perturbation component of an electric field, which cannot be derived from the fluid theory, was able to be obtained; the values of E-lambda product agreed with the experimental results better than one-dimensional analysis; The steeper the shape of radial potential distribution, the more likely the resonance occurrence and the larger the E-lambda product; and so forth. (Wakatsuki, Y.)
Local full-wave energy and quasilinear analysis in nonuniform plasmas
International Nuclear Information System (INIS)
Smithe, D.N.
1989-01-01
The subject of local wave energy in plasmas is treated via quasilinear theory from the dual perspectives of the action-angle formalism and gyrokinetic analysis. An extension is presented to all orders in the gyroradius of the self-consistent wave-propagation/quasilinear-absorption problem using gyrokinetics. Questions of when and under what conditions local energy should be of definite sign are answered using the action-angle formalism. An important result is that the ''dielectric operators'' of the linearized wave equation and of the local energy are not the same, a fact which is obscured when the eikonal or WKB assumption is invoked. Even though the two dielectrics are very different in character, it is demonstrated that they are nevertheless related by a simple mathematical statement. This study was originally motivated by concern over the question of local energy for r.f.-heating of plasmas, where in certain instances, full-wave effects such as refraction, strong absorption, and mode conversion are of primary importance. Fundamentally, the r.f.-absorption must equate with the energy moment of the quasilinear term to achieve a correct energy balance. This fact governs the derivation (as opposed to postulation) of the local absorption. The troublesome ''kinetic flux'' may then be chosen (it is not unique) to satisfy a wave-energy balance relation with the Poynting flux and local absorption. It is shown that at least one such choice reduces asymptotically to the Stix form away from nonuniformities. (author)
EM wave propagation analysis in plasma covered radar absorbing material
Singh, Hema; Rawat, Harish Singh
2017-01-01
This book focuses on EM propagation characteristics within multilayered plasma-dielectric-metallic media. The method used for analysis is impedance transformation method. Plasma covered radar absorbing material is approximated as a multi-layered dielectric medium. The plasma is considered to be bounded homogeneous/inhomogeneous medium. The reflection coefficient and hence return loss is analytically derived. The role of plasma parameters, such as electron density, collision frequency, plasma thickness, and plasma density profile in the absorption behavior of multi-layered plasma-RAM structure is described. This book provides a clearer picture of EM propagation within plasma. The reader will get an insight of plasma parameters that play significant role in deciding the absorption characteristics of plasma covered surfaces.
Can P wave wavelet analysis predict atrial fibrillation after coronary artery bypass grafting?
Vassilikos, Vassilios; Dakos, George; Chouvarda, Ioanna; Karagounis, Labros; Karvounis, Haralambos; Maglaveras, Nikolaos; Mochlas, Sotirios; Spanos, Panagiotis; Louridas, George
2003-01-01
The purpose of this study was the evaluation of Morlet wavelet analysis of the P wave as a means of predicting the development of atrial fibrillation (AF) in patients who undergo coronary artery bypass grafting (CABG). The P wave was analyzed using the Morlet wavelet in 50 patients who underwent successful CABG. Group A consisted of 17 patients, 12 men and 5 women, of mean age 66.9 +/- 5.9 years, who developed AF postoperatively. Group B consisted of 33 patients, 29 men and 4 women, mean age 62.4 +/- 7.8 years, who remained arrhythmid-free. Using custom-designed software, P wave duration and wavelet parameters expressing the mean and maximum energy of the P wave were calculated from 3-channel digital recordings derived from orthogonal ECG leads (X, Y, and Z), and the vector magnitude (VM) was determined in each of 3 frequency bands (200-160 Hz, 150-100 Hz and 90-50 Hz). Univariate logistic-regression analysis identified a history of hypertension, the mean and maximum energies in all frequency bands along the Z axis, the mean and maximum energies (expressed by the VM) in the 200-160 Hz frequency band, and the mean energy in the 150-100 Hz frequency band along the Y axis as predictors for post-CABG AF. Multivariate analysis identified hypertension, ejection fraction, and the maximum energies in the 90-50 Hz frequency band along the Z and composite-vector axes as independent predictors. This multivariate model had a sensitivity of 91% and a specificity of 65%. We conclude that the Morlet wavelet analysis of the P wave is a very sensitive method of identifying patients who are likely to develop AF after CABG. The occurrence of post-CABG AF can be explained by a different activation pattern along the Z axis.
Götberg, Matthias; Christiansen, Evald H; Gudmundsdottir, Ingibjörg; Sandhall, Lennart; Omerovic, Elmir; James, Stefan K; Erlinge, David; Fröbert, Ole
2015-11-01
Instantaneous wave-free ratio (iFR) is a new hemodynamic resting index for assessment of coronary artery stenosis severity. iFR uses high frequency sampling to calculate a gradient across a coronary lesion during a period of diastole. The index has been tested against fractional flow reserve (FFR) and found to have an overall classification agreement of 80% to 85%. Whether the level of disagreement is clinically relevant is unknown. Clinical outcome data on iFR are scarce. This study is a registry-based randomized clinical trial, which is a novel strategy using health quality registries as on-line platforms for randomization, case record forms, and follow-up. iFR-SWEDEHEART is a multicenter, prospective, randomized, controlled, clinical open-label clinical trial. Two thousand patients with stable angina or acute coronary syndrome and an indication for physiology-guided assessment of one or more coronary stenoses will be randomized 1:1 to either iFR- or FFR-guided intervention. The randomization will be conducted online in the Swedish web-based system for enhancement and development of evidence-based care in heart disease evaluated according to recommended therapies (SWEDEHEART) registry. The trial has a non-inferiority design, with a primary combined end point of all-cause death, non-fatal myocardial infarction, and unplanned revascularization at 12 months. End points will be identified through national registries and undergo central blind adjudication to ensure data quality. The iFR-SWEDEHEART trial is an registry-based randomized clinical trial evaluating the safety and efficacy of the diagnostic method iFR compared to FFR. Copyright © 2015 Elsevier Inc. All rights reserved.
Sun, Wenxiu; Liu, Guoqiang; Xia, Hui; Xia, Zhengwu
2018-03-01
Accurate acquisition of the detection signal travel time plays a very important role in cross-hole tomography. The experimental platform of aluminum plate under the perpendicular magnetic field is established and the bilinear time-frequency analysis methods, Wigner-Ville Distribution (WVD) and the pseudo-Wigner-Ville distribution (PWVD), are applied to analyse the Lamb wave signals detected by electromagnetic acoustic transducer (EMAT). By extracting the same frequency component of the time-frequency spectrum as the excitation frequency, the travel time information can be obtained. In comparison with traditional linear time-frequency analysis method such as short-time Fourier transform (STFT), the bilinear time-frequency analysis method PWVD is more appropriate in extracting travel time and recognizing patterns of Lamb wave.
Gravitational-Wave Data Analysis. Formalism and Sample Applications: The Gaussian Case
Directory of Open Access Journals (Sweden)
Królak Andrzej
2005-03-01
Full Text Available The article reviews the statistical theory of signal detection in application to analysis of deterministic gravitational-wave signals in the noise of a detector. Statistical foundations for the theory of signal detection and parameter estimation are presented. Several tools needed for both theoretical evaluation of the optimal data analysis methods and for their practical implementation are introduced. They include optimal signal-to-noise ratio, Fisher matrix, false alarm and detection probabilities, F-statistic, template placement, and fitting factor. These tools apply to the case of signals buried in a stationary and Gaussian noise. Algorithms to efficiently implement the optimal data analysis techniques are discussed. Formulas are given for a general gravitational-wave signal that includes as special cases most of the deterministic signals of interest.
Gravitational-Wave Data Analysis. Formalism and Sample Applications: The Gaussian Case
Directory of Open Access Journals (Sweden)
Piotr Jaranowski
2012-03-01
Full Text Available The article reviews the statistical theory of signal detection in application to analysis of deterministic gravitational-wave signals in the noise of a detector. Statistical foundations for the theory of signal detection and parameter estimation are presented. Several tools needed for both theoretical evaluation of the optimal data analysis methods and for their practical implementation are introduced. They include optimal signal-to-noise ratio, Fisher matrix, false alarm and detection probabilities, ℱ-statistic, template placement, and fitting factor. These tools apply to the case of signals buried in a stationary and Gaussian noise. Algorithms to efficiently implement the optimal data analysis techniques are discussed. Formulas are given for a general gravitational-wave signal that includes as special cases most of the deterministic signals of interest.
Morisaki, Soichiro; Yokoyama, Jun'ichi; Eda, Kazunari; Itoh, Yousuke
2016-01-01
We introduce a new analysis method to deal with stationary non-Gaussian noises in gravitational wave detectors in terms of the independent component analysis. First, we consider the simplest case where the detector outputs are linear combinations of the inputs, consisting of signals and various noises, and show that this method may be helpful to increase the signal-to-noise ratio. Next, we take into account the time delay between the inputs and the outputs. Finally, we extend our method to nonlinearly correlated noises and show that our method can identify the coupling coefficients and remove non-Gaussian noises. Although we focus on gravitational wave data analysis, our methods are applicable to the detection of any signals under non-Gaussian noises.
Partial wave analysis of KKPI system in D and E/IOTA region
International Nuclear Information System (INIS)
Chung, S.U.; Fernow, R.; Kirk, H.
1985-01-01
A partial wave analysis and a Dalitz plot analysis of high-statistics data from reaction π - p → K + K/sub S/π - n at 8.0 GeV/c show that the D(1285) is a J/sup PG/ = 1 ++ state and the E(1420) a J/sup PG/ = 0 -+ state both with a substantial deltaπ decay mode. The 1 ++ K*anti K wave exhibits a rapid rise near threshold but no evidence of a resonance in the E region. The assignment of J/sup PG/ = O -+ to the E is confirmed from a Dalitz-plot analysis of the reaction pp → K + K/sub S/π - X 0 . 11 refs., 5 figs
Random safety auditing, root cause analysis, failure mode and effects analysis.
Ursprung, Robert; Gray, James
2010-03-01
Improving quality and safety in health care is a major concern for health care providers, the general public, and policy makers. Errors and quality issues are leading causes of morbidity and mortality across the health care industry. There is evidence that patients in the neonatal intensive care unit (NICU) are at high risk for serious medical errors. To facilitate compliance with safe practices, many institutions have established quality-assurance monitoring procedures. Three techniques that have been found useful in the health care setting are failure mode and effects analysis, root cause analysis, and random safety auditing. When used together, these techniques are effective tools for system analysis and redesign focused on providing safe delivery of care in the complex NICU system. Copyright 2010 Elsevier Inc. All rights reserved.
Analysis of Secret Key Randomness Exploiting the Radio Channel Variability
Directory of Open Access Journals (Sweden)
Taghrid Mazloum
2015-01-01
Full Text Available A few years ago, physical layer based techniques have started to be considered as a way to improve security in wireless communications. A well known problem is the management of ciphering keys, both regarding the generation and distribution of these keys. A way to alleviate such difficulties is to use a common source of randomness for the legitimate terminals, not accessible to an eavesdropper. This is the case of the fading propagation channel, when exact or approximate reciprocity applies. Although this principle has been known for long, not so many works have evaluated the effect of radio channel properties in practical environments on the degree of randomness of the generated keys. To this end, we here investigate indoor radio channel measurements in different environments and settings at either 2.4625 GHz or 5.4 GHz band, of particular interest for WIFI related standards. Key bits are extracted by quantizing the complex channel coefficients and their randomness is evaluated using the NIST test suite. We then look at the impact of the carrier frequency, the channel variability in the space, time, and frequency degrees of freedom used to construct a long secret key, in relation to the nature of the radio environment such as the LOS/NLOS character.
Repairable system analysis in presence of covariates and random effects
International Nuclear Information System (INIS)
Giorgio, M.; Guida, M.; Pulcini, G.
2014-01-01
This paper aims to model the failure pattern of repairable systems in presence of explained and unexplained heterogeneity. The failure pattern of each system is described by a Power Law Process. Part of the heterogeneity among the patterns is explained through the use of a covariate, and the residual unexplained heterogeneity (random effects) is modeled via a joint probability distribution on the PLP parameters. The proposed approach is applied to a real set of failure time data of powertrain systems mounted on 33 buses employed in urban and suburban routes. Moreover, the joint probability distribution on the PLP parameters estimated from the data is used as an informative prior to make Bayesian inference on the future failure process of a generic system belonging to the same population and employed in an urban or suburban route under randomly chosen working conditions. - Highlights: • We describe the failure process of buses powertrain system subject to heterogeneity. • Heterogeneity due to different service types is explained by a covariate. • Random effect is modeled through a joint pdf on failure process parameters. • The powertrain reliability under new future operating conditions is estimated
Superresolution Imaging Using Resonant Multiples and Plane-wave Migration Velocity Analysis
Guo, Bowen
2017-08-28
Seismic imaging is a technique that uses seismic echoes to map and detect underground geological structures. The conventional seismic image has the resolution limit of λ/2, where λ is the wavelength associated with the seismic waves propagating in the subsurface. To exceed this resolution limit, this thesis develops a new imaging method using resonant multiples, which produces superresolution images with twice or even more the spatial resolution compared to the conventional primary reflection image. A resonant multiple is defined as a seismic reflection that revisits the same subsurface location along coincident reflection raypath. This reverberated raypath is the reason for superresolution imaging because it increases the differences in reflection times associated with subtle changes in the spatial location of the reflector. For the practical implementation of superresolution imaging, I develop a post-stack migration technique that first enhances the signal-to-noise ratios (SNRs) of resonant multiples by a moveout-correction stacking method, and then migrates the post-stacked resonant multiples with the associated Kirchhoff or wave-equation migration formula. I show with synthetic and field data examples that the first-order resonant multiple image has about twice the spatial resolution compared to the primary reflection image. Besides resolution, the correct estimate of the subsurface velocity is crucial for determining the correct depth of reflectors. Towards this goal, wave-equation migration velocity analysis (WEMVA) is an image-domain method which inverts for the velocity model that maximizes the similarity of common image gathers (CIGs). Conventional WEMVA based on subsurface-offset, angle domain or time-lag CIGs requires significant computational and memory resources because it computes higher dimensional migration images in the extended image domain. To mitigate this problem, I present a new WEMVA method using plane-wave CIGs. Plane-wave CIGs reduce the
Design and Experiment Analysis of a Direct-Drive Wave Energy Converter with a Linear Generator
Directory of Open Access Journals (Sweden)
Jing Zhang
2018-03-01
Full Text Available Coastal waves are an abundant nonpolluting and renewable energy source. A wave energy converter (WEC must be designed for efficient and steady operation in highly energetic ocean environments. A direct-drive wave energy conversion (D-DWEC system with a tubular permanent magnet linear generator (TPMLG on a wind and solar photovoltaic complementary energy generation platform is proposed to improve the conversion efficiency and reduce the complexity and device volume of WECs. The operating principle of D-DWECs is introduced, and detailed analyses of the proposed D-DWEC’s floater system, wave force characteristics, and conversion efficiency conducted using computational fluid dynamics are presented. A TPMLG with an asymmetric slot structure is designed to increase the output electric power, and detailed analyses of the magnetic field distribution, detent force characteristics, and no-load and load performances conducted using finite element analysis are discussed. The TPMLG with an asymmetric slot, which produces the same power as the TPMLG with a symmetric slot, has one fifth detent force of the latter. An experiment system with a prototype of the TPMLG with a symmetric slot is used to test the simulation results. The experiment and analysis results agree well. Therefore, the proposed D-DWEC fulfills the requirements of WEC systems.
Directory of Open Access Journals (Sweden)
M. Ern
2009-01-01
Full Text Available Space-time spectral analysis of satellite data is an important method to derive a synoptic picture of the atmosphere from measurements sampled asynoptically by satellite instruments. In addition, it serves as a powerful tool to identify and separate different wave modes in the atmospheric data. In our work we present space-time spectral analyses of chemical heating rates derived from Scanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY hydroxyl nightglow emission measurements onboard Envisat for the years 2002–2006 at mesopause heights. Since SCIAMACHY nightglow hydroxyl emission measurements are restricted to the ascending (nighttime part of the satellite orbit, our analysis also includes temperature spectra derived from 15 μm CO2 emissions measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER instrument. SABER offers better temporal and spatial coverage (daytime and night-time values of temperature and a more regular sampling grid. Therefore SABER spectra also contain information about higher frequency waves. Comparison of SCIAMACHY and SABER results shows that SCIAMACHY, in spite of its observational restrictions, provides valuable information on most of the wave modes present in the mesopause region. The main differences between wave spectra obtained from these sensors can be attributed to the differences in their sampling patterns.
Directory of Open Access Journals (Sweden)
M. Ern
2009-01-01
Full Text Available Space-time spectral analysis of satellite data is an important method to derive a synoptic picture of the atmosphere from measurements sampled asynoptically by satellite instruments. In addition, it serves as a powerful tool to identify and separate different wave modes in the atmospheric data. In our work we present space-time spectral analyses of chemical heating rates derived from Scanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY hydroxyl nightglow emission measurements onboard Envisat for the years 2002–2006 at mesopause heights.
Since SCIAMACHY nightglow hydroxyl emission measurements are restricted to the ascending (nighttime part of the satellite orbit, our analysis also includes temperature spectra derived from 15 μm CO_{2} emissions measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER instrument. SABER offers better temporal and spatial coverage (daytime and night-time values of temperature and a more regular sampling grid. Therefore SABER spectra also contain information about higher frequency waves.
Comparison of SCIAMACHY and SABER results shows that SCIAMACHY, in spite of its observational restrictions, provides valuable information on most of the wave modes present in the mesopause region. The main differences between wave spectra obtained from these sensors can be attributed to the differences in their sampling patterns.
Stability analysis and reconstruction of wave distribution functions in warm plasmas
International Nuclear Information System (INIS)
Oscarsson, T.E.
1989-05-01
The purpose of this thesis is first to describe stability analysis and reconstruction of the wave distribution function (WDF) separately, and then to show how the two approaches can be combined in an investigation of satellite data. To demonstrate the type of stability investigation that is often used in space physics we study instabilities below the local proton gyrofrequency which are caused by anisotropic proton distributions. Arbitrary angles between the wavevector and the background magnetic field are considered, and effects of warm plasma on the wave propagation properties are included. We also comment briefly given on an often-used scheme for classifying instabilities. In our discussion on WDF analysis we develop a completely new and general method for reconstructing the WDF. Our scheme can be used to reconstruct the distribution function of waves in warm as well as cold plasma. Doppler effects introduced by satellite motion are included, and the reconstructions can be performed over a broad frequency range simultaneously. The applicability of our new WDF reconstruction method is studied in model problems and in an application to observations made by the Swedish satellite Viking. In the application to Viking data we combine stability and WDF analyses in a unique way that promises to become an important tool in future studies of wave-particle interactions in space plasmas. (author)
International Nuclear Information System (INIS)
Washizu, Masao; Tanabe, Yoshio.
1986-01-01
In a system handling the electromagnetic waves of large power such as the cavity resonator for a high energy accelerator and the high frequency heater for a nuclear fusion apparatus, the margin in the thermal and mechanical design of a wave guide system cannot be taken large, accordingly, the detailed analysis of electromagnetic waves is required. When the analysis in a general form is carried out, boundary element method may be a useful method of solution. This time, the authors carried out the formulation of steady electromagnetic wave problems by boundary element method, and it was shown that the formulation was able to be carried out under the physically clear boundary condition also in this case, and especially in the case of a perfect conductor system, a very simple form was obtained. In this paper, first, the techniques of formulation in a general case, and next, as a special case, the formulation for a perfect conductor system are described. Taking the analysis of the cavity resonators of cylindrical and rectangular parallelepiped forms as examples, the comparison with the analytical solution was carried out. (Kako, I.)
International Nuclear Information System (INIS)
Suck Salk, S.H.
1985-01-01
With the use of projection operators, the formal expressions of distorted-wave and coupled-channel-wave transition amplitudes for rearrangement collisions are derived. Use of projection operators (for the transition amplitudes) sharpens our understanding of the structural differences between the two transition amplitudes. The merit of each representation of the transition amplitudes is discussed. Derived perturbation potentials are found to have different structures. The rigorously derived distorted-wave Born-approximation (DWBA) transition amplitude is shown to be a generalization of the earlier DWBA expression obtained from the assumption of the dominance of elastic scattering in rearrangement collisions
Clark, Laura; Ronaldson, Sarah; Dyson, Lisa; Hewitt, Catherine; Torgerson, David; Adamson, Joy
2015-12-01
To assess the effectiveness of sending electronic prompts to randomized controlled trial participants to return study questionnaires. A "trial within a trial" embedded within a study determining the effectiveness of chronic obstructive pulmonary disease (DOC) screening on smoking cessation. Those participants taking part in DOC who provided a mobile phone number and/or an electronic mail address were randomized to either receive an electronic prompt or no electronic prompt to return a study questionnaire. The results were combined with two previous studies in a meta-analysis. A total of 437 participants were randomized: 226 to the electronic prompt group and 211 to the control group. A total of 285 (65.2%) participants returned the follow-up questionnaire: 157 (69.5%) in the electronic prompt group and 128 (60.7%) in the control group [difference 8.8%; 95% confidence interval (CI): -0.11%, 17.7%; P = 0.05]. The mean time to response was 23 days in the electronic prompt group and 33 days in the control group (hazard ratio = 1.27; 95% CI: 1.105, 1.47). The meta-analysis of all three studies showed an increase in response rate of 7.1% (95% CI: 0.8%, 13.3%). The use of electronic prompts increased response rates and reduces the time to response. Copyright © 2015 Elsevier Inc. All rights reserved.
ATLAS, an integrated structural analysis and design system. Volume 4: Random access file catalog
Gray, F. P., Jr. (Editor)
1979-01-01
A complete catalog is presented for the random access files used by the ATLAS integrated structural analysis and design system. ATLAS consists of several technical computation modules which output data matrices to corresponding random access file. A description of the matrices written on these files is contained herein.
Time-Frequency-Wavenumber Analysis of Surface Waves Using the Continuous Wavelet Transform
Poggi, V.; Fäh, D.; Giardini, D.
2013-03-01
A modified approach to surface wave dispersion analysis using active sources is proposed. The method is based on continuous recordings, and uses the continuous wavelet transform to analyze the phase velocity dispersion of surface waves. This gives the possibility to accurately localize the phase information in time, and to isolate the most significant contribution of the surface waves. To extract the dispersion information, then, a hybrid technique is applied to the narrowband filtered seismic recordings. The technique combines the flexibility of the slant stack method in identifying waves that propagate in space and time, with the resolution of f- k approaches. This is particularly beneficial for higher mode identification in cases of high noise levels. To process the continuous wavelet transform, a new mother wavelet is presented and compared to the classical and widely used Morlet type. The proposed wavelet is obtained from a raised-cosine envelope function (Hanning type). The proposed approach is particularly suitable when using continuous recordings (e.g., from seismological-like equipment) since it does not require any hardware-based source triggering. This can be subsequently done with the proposed method. Estimation of the surface wave phase delay is performed in the frequency domain by means of a covariance matrix averaging procedure over successive wave field excitations. Thus, no record stacking is necessary in the time domain and a large number of consecutive shots can be used. This leads to a certain simplification of the field procedures. To demonstrate the effectiveness of the method, we tested it on synthetics as well on real field data. For the real case we also combine dispersion curves from ambient vibrations and active measurements.
Chai, Rui; Xu, Li-Sheng; Yao, Yang; Hao, Li-Ling; Qi, Lin
2017-01-01
This study analyzed ascending branch slope (A_slope), dicrotic notch height (Hn), diastolic area (Ad) and systolic area (As) diastolic blood pressure (DBP), systolic blood pressure (SBP), pulse pressure (PP), subendocardial viability ratio (SEVR), waveform parameter (k), stroke volume (SV), cardiac output (CO), and peripheral resistance (RS) of central pulse wave invasively and non-invasively measured. Invasively measured parameters were compared with parameters measured from brachial pulse waves by regression model and transfer function model. Accuracy of parameters estimated by regression and transfer function model, was compared too. Findings showed that k value, central pulse wave and brachial pulse wave parameters invasively measured, correlated positively. Regression model parameters including A_slope, DBP, SEVR, and transfer function model parameters had good consistency with parameters invasively measured. They had same effect of consistency. SBP, PP, SV, and CO could be calculated through the regression model, but their accuracies were worse than that of transfer function model.
Pallares, Elena; Espino, Manuel; Sánchez-Arcilla, Agustín
2013-04-01
The Catalan Coast is located in the North Western Mediterranean Sea. It is a region with highly heterogeneous wind and wave conditions, characterized by a microtidal environment, and economically very dependent from the sea and the coastal zone activities. Because some of the main coastal conflicts and management problems occur within a few kilometers of the land-ocean boundary, the level of resolution and accuracy from meteo-oceanographic predictions required is not currently available. The current work is focused on improving high resolution wave forecasting very near the coast. The SWAN wave model is used to simulate the waves in the area, and various buoy data and field campaigns are used to validate the results. The simulations are structured in four different domains covering all the North Western Mediterranean Sea, with a grid resolution from 9 km to 250 meters in coastal areas. Previous results show that the significant wave height is almost always underpredicted in this area, and the underprediction is higher during storm events. However, the error in the peak period and the mean period is almost always constantly under predicted with a bias between one and two seconds, plus some residual error. This systematic error represents 40% of the total error. To improve the initial results, the whiteccaping dissipation term is studied and modified. In the SWAN model, the whitecapping is mainly controlled by the steepness of the waves. Although the by default parameter is not depending on the wave number, there is a new formulation in the last SWAN version (40.81) to include it in the calculations. Previous investigations show that adjusting the dependence for the wave number improved the predictions for the wave energy at lower frequencies, solving the underprediction of the period mentioned before. In the present work different simulations are developed to calibrate the new formulation, obtaining important improvements in the results. For the significant wave
Nonstandard Analysis and Shock Wave Jump Conditions in a One-Dimensional Compressible Gas
Energy Technology Data Exchange (ETDEWEB)
Roy S. Baty, F. Farassat, John A. Hargreaves
2007-05-25
Nonstandard analysis is a relatively new area of mathematics in which infinitesimal numbers can be defined and manipulated rigorously like real numbers. This report presents a fairly comprehensive tutorial on nonstandard analysis for physicists and engineers with many examples applicable to generalized functions. To demonstrate the power of the subject, the problem of shock wave jump conditions is studied for a one-dimensional compressible gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. To use conservations laws, smooth pre-distributions of the Dirac delta measure are applied whose supports are contained within the shock thickness. Furthermore, smooth pre-distributions of the Heaviside function are applied which vary from zero to one across the shock wave. It is shown that if the equations of motion are expressed in nonconservative form then the relationships between the jump functions for the flow parameters may be found unambiguously. The analysis yields the classical Rankine-Hugoniot jump conditions for an inviscid shock wave. Moreover, non-monotonic entropy jump conditions are obtained for both inviscid and viscous flows. The report shows that products of generalized functions may be defined consistently using nonstandard analysis; however, physically meaningful products of generalized functions must be determined from the physics of the problem and not the mathematical form of the governing equations.
Analysis of the high water wave volume for the Sava River near Zagreb
Trninic, Dusan
2010-05-01
The paper analyses volumes of the Sava River high water waves near Zagreb during the period: 1926-2008 (N = 83 years), which is needed for more efficient control of high and flood waters. The primary Sava flood control structures in the City of Zagreb are dikes built on both riverbanks, and the Odra Relief Canal with lateral spillway upstream from the City of Zagreb. Intensive morphological changes in the greater Sava area near Zagreb, and anthropological and climate variations and changes at the Sava catchment up to the Zagreb area require detailed analysis of the water wave characteristics. In one analysis, maximum annual volumes are calculated for high water waves with constant duration of: 10, 20, 30, 40, 50 and 60 days. Such calculations encompass total quantity of water (basic and surface runoff). The log Pearson III distribution is adapted for this series of maximum annual volumes. Based on the results obtained, the interrelations are established between the wave volume as function of duration and occurrence probability. In addition to the analysis of maximum volumes of constant duration, it is interesting to carry out the analyses of maximum volume in excess of the reference discharge since it is very important for the flood control. To determine the reference discharges, a discharge of specific duration is used from an average discharge duration curve. The adopted reference discharges have durations of 50, 40, 30, 20 and 10%. Like in the previous case, log Pearson III distribution is adapted to the maximum wave data series. For reference discharge Q = 604 m3/s (duration 10%), a linear trend is calculated of maximum annual volumes exceeding the reference discharge for the Sava near Zagreb during the analyzed period. The analysis results show a significant decrease trend. A similar analysis is carried out for the following three reference discharges: regular flood control measures at the Sava near Zagreb, which are proclaimed when the water level is 350 cm
Chai Rui; Li Si-Man; Xu Li-Sheng; Yao Yang; Hao Li-Ling
2017-07-01
This study mainly analyzed the parameters such as ascending branch slope (A_slope), dicrotic notch height (Hn), diastolic area (Ad) and systolic area (As) diastolic blood pressure (DBP), systolic blood pressure (SBP), pulse pressure (PP), subendocardial viability ratio (SEVR), waveform parameter (k), stroke volume (SV), cardiac output (CO) and peripheral resistance (RS) of central pulse wave invasively and non-invasively measured. These parameters extracted from the central pulse wave invasively measured were compared with the parameters measured from the brachial pulse waves by a regression model and a transfer function model. The accuracy of the parameters which were estimated by the regression model and the transfer function model was compared too. Our findings showed that in addition to the k value, the above parameters of the central pulse wave and the brachial pulse wave invasively measured had positive correlation. Both the regression model parameters including A_slope, DBP, SEVR and the transfer function model parameters had good consistency with the parameters invasively measured, and they had the same effect of consistency. The regression equations of the three parameters were expressed by Y'=a+bx. The SBP, PP, SV, CO of central pulse wave could be calculated through the regression model, but their accuracies were worse than that of transfer function model.
Yue, Y.; Jiang, T.; Zhou, Q.
2017-12-01
In order to ensure the rationality and the safety of tunnel excavation, the advanced geological prediction has been become an indispensable step in tunneling. However, the extraction of signal and the separation of P and S waves directly influence the accuracy of geological prediction. Generally, the raw data collected in TSP system is low quality because of the numerous disturb factors in tunnel projects, such as the power interference and machine vibration interference. It's difficult for traditional method (band-pass filtering) to remove interference effectively as well as bring little loss to signal. The power interference, machine vibration interference and the signal are original variables and x, y, z component as observation signals, each component of the representation is a linear combination of the original variables, which satisfy applicable conditions of independent component analysis (ICA). We perform finite-difference simulations of elastic wave propagation to synthetic a tunnel seismic reflection record. The method of ICA was adopted to process the three-component data, and the results show that extract the estimates of signal and the signals are highly correlated (the coefficient correlation is up to more than 0.93). In addition, the estimates of interference that separated from ICA and the interference signals are also highly correlated, and the coefficient correlation is up to more than 0.99. Thus, simulation results showed that the ICA is an ideal method for extracting high quality data from mixed signals. For the separation of P and S waves, the conventional separation techniques are based on physical characteristics of wave propagation, which require knowledge of the near-surface P and S waves velocities and density. Whereas the ICA approach is entirely based on statistical differences between P and S waves, and the statistical technique does not require a priori information. The concrete results of the wave field separation will be presented in
Astone, Pia; Weinstein, Alan; Agathos, Michalis; Bejger, Michal; Christensen, Nelson; Dent, Thomas; Graff, Philip; Klimenko, Sergey; Mazzolo, Giulio; Nishizawa, Atsushi
2015-01-01
The Amaldi 10 Parallel Session C2 on gravitational wave(GW) search results, data analysis and parameter estimation included three lively sessions of lectures by 13 presenters, and 34 posters. The talks and posters covered a huge range of material, including results and analysis techniques for ground-based GW detectors, targeting anticipated signals from different astrophysical sources: compact binary inspiral, merger and ringdown; GW bursts from intermediate mass binary black hole mergers, cosmic string cusps, core-collapse supernovae, and other unmodeled sources; continuous waves from spinning neutron stars; and a stochastic GW background. There was considerable emphasis on Bayesian techniques for estimating the parameters of coalescing compact binary systems from the gravitational waveforms extracted from the data from the advanced detector network. This included methods to distinguish deviations of the signals from what is expected in the context of General Relativity.
Astone, Pia; Weinstein, Alan; Agathos, Michalis; Bejger, Michał; Christensen, Nelson; Dent, Thomas; Graff, Philip; Klimenko, Sergey; Mazzolo, Giulio; Nishizawa, Atsushi; Robinet, Florent; Schmidt, Patricia; Smith, Rory; Veitch, John; Wade, Madeline; Aoudia, Sofiane; Bose, Sukanta; Calderon Bustillo, Juan; Canizares, Priscilla; Capano, Colin; Clark, James; Colla, Alberto; Cuoco, Elena; Da Silva Costa, Carlos; Dal Canton, Tito; Evangelista, Edgar; Goetz, Evan; Gupta, Anuradha; Hannam, Mark; Keitel, David; Lackey, Benjamin; Logue, Joshua; Mohapatra, Satyanarayan; Piergiovanni, Francesco; Privitera, Stephen; Prix, Reinhard; Pürrer, Michael; Re, Virginia; Serafinelli, Roberto; Wade, Leslie; Wen, Linqing; Wette, Karl; Whelan, John; Palomba, C; Prodi, G
The Amaldi 10 Parallel Session C2 on gravitational wave (GW) search results, data analysis and parameter estimation included three lively sessions of lectures by 13 presenters, and 34 posters. The talks and posters covered a huge range of material, including results and analysis techniques for ground-based GW detectors, targeting anticipated signals from different astrophysical sources: compact binary inspiral, merger and ringdown; GW bursts from intermediate mass binary black hole mergers, cosmic string cusps, core-collapse supernovae, and other unmodeled sources; continuous waves from spinning neutron stars; and a stochastic GW background. There was considerable emphasis on Bayesian techniques for estimating the parameters of coalescing compact binary systems from the gravitational waveforms extracted from the data from the advanced detector network. This included methods to distinguish deviations of the signals from what is expected in the context of General Relativity.
Bayesian analysis for exponential random graph models using the adaptive exchange sampler
Jin, Ick Hoon; Liang, Faming; Yuan, Ying
2013-01-01
Exponential random graph models have been widely used in social network analysis. However, these models are extremely difficult to handle from a statistical viewpoint, because of the existence of intractable normalizing constants. In this paper, we
Review of Recent Methodological Developments in Group-Randomized Trials: Part 2-Analysis.
Turner, Elizabeth L; Prague, Melanie; Gallis, John A; Li, Fan; Murray, David M
2017-07-01
In 2004, Murray et al. reviewed methodological developments in the design and analysis of group-randomized trials (GRTs). We have updated that review with developments in analysis of the past 13 years, with a companion article to focus on developments in design. We discuss developments in the topics of the earlier review (e.g., methods for parallel-arm GRTs, individually randomized group-treatment trials, and missing data) and in new topics, including methods to account for multiple-level clustering and alternative estimation methods (e.g., augmented generalized estimating equations, targeted maximum likelihood, and quadratic inference functions). In addition, we describe developments in analysis of alternative group designs (including stepped-wedge GRTs, network-randomized trials, and pseudocluster randomized trials), which require clustering to be accounted for in their design and analysis.
Analysis of axial compressive loaded beam under random support excitations
Xiao, Wensheng; Wang, Fengde; Liu, Jian
2017-12-01
An analytical procedure to investigate the response spectrum of a uniform Bernoulli-Euler beam with axial compressive load subjected to random support excitations is implemented based on the Mindlin-Goodman method and the mode superposition method in the frequency domain. The random response spectrum of the simply supported beam subjected to white noise excitation and to Pierson-Moskowitz spectrum excitation is investigated, and the characteristics of the response spectrum are further explored. Moreover, the effect of axial compressive load is studied and a method to determine the axial load is proposed. The research results show that the response spectrum mainly consists of the beam's additional displacement response spectrum when the excitation is white noise; however, the quasi-static displacement response spectrum is the main component when the excitation is the Pierson-Moskowitz spectrum. Under white noise excitation, the amplitude of the power spectral density function decreased as the axial compressive load increased, while the frequency band of the vibration response spectrum increased with the increase of axial compressive load.
Metabolic Profiling of Adiponectin Levels in Adults: Mendelian Randomization Analysis.
Borges, Maria Carolina; Barros, Aluísio J D; Ferreira, Diana L Santos; Casas, Juan Pablo; Horta, Bernardo Lessa; Kivimaki, Mika; Kumari, Meena; Menon, Usha; Gaunt, Tom R; Ben-Shlomo, Yoav; Freitas, Deise F; Oliveira, Isabel O; Gentry-Maharaj, Aleksandra; Fourkala, Evangelia; Lawlor, Debbie A; Hingorani, Aroon D
2017-12-01
Adiponectin, a circulating adipocyte-derived protein, has insulin-sensitizing, anti-inflammatory, antiatherogenic, and cardiomyocyte-protective properties in animal models. However, the systemic effects of adiponectin in humans are unknown. Our aims were to define the metabolic profile associated with higher blood adiponectin concentration and investigate whether variation in adiponectin concentration affects the systemic metabolic profile. We applied multivariable regression in ≤5909 adults and Mendelian randomization (using cis -acting genetic variants in the vicinity of the adiponectin gene as instrumental variables) for analyzing the causal effect of adiponectin in the metabolic profile of ≤37 545 adults. Participants were largely European from 6 longitudinal studies and 1 genome-wide association consortium. In the multivariable regression analyses, higher circulating adiponectin was associated with higher high-density lipoprotein lipids and lower very-low-density lipoprotein lipids, glucose levels, branched-chain amino acids, and inflammatory markers. However, these findings were not supported by Mendelian randomization analyses for most metabolites. Findings were consistent between sexes and after excluding high-risk groups (defined by age and occurrence of previous cardiovascular event) and 1 study with admixed population. Our findings indicate that blood adiponectin concentration is more likely to be an epiphenomenon in the context of metabolic disease than a key determinant. © 2017 The Authors.
A nonlinear analysis of the terahertz serpentine waveguide traveling-wave amplifier
International Nuclear Information System (INIS)
Li, Ke; Cao, Miaomiao; Liu, Wenxin; Wang, Yong
2015-01-01
A nonlinear model for the numerical simulation of terahertz serpentine waveguide traveling-wave tube (SW-TWT) is described. In this model, the electromagnetic wave transmission in the SW is represented as an infinite set of space harmonics to interact with an electron beam. Analytical expressions for axial electric fields in axisymmetric interaction gaps of SW-TWTs are derived and compared with the results from CST simulation. The continuous beam is treated as discrete macro-particles with different initial phases. The beam-tunnel field equations, space-charge field equations, and motion equations are combined to solve the beam-wave interaction. The influence of backward wave and relativistic effect is also considered in the series of equations. The nonlinear model is used to design a 340 GHz SW-TWT. Several favorable comparisons of model predictions with results from a 3-D Particle-in-cell simulation code CHIPIC are presented, in which the output power versus beam voltage and interaction periods are illustrated. The relative error of the predicted output power is less than 15% in the 3 dB bandwidth and the relative error of the saturated length is less than 8%.The results show that the 1-D nonlinear analysis model is appropriate to solve the terahertz SW-TWT operation characteristics
International Nuclear Information System (INIS)
Ohnuki, S.; Adachi, S.; Ohnuma, T.
1978-01-01
The radiation and reception characteristics of the oblate spheroidal antenna for electron plasma waves are theoretically investigated. The analysis is carried out as a boundary-value problem. The formulas for the radiation and reception characteristics such as radiation impedance, electron charge distributions, radiated wave potential, directional properties, and receiving voltage of the oblate spheroidal antenna are analytically obtained. As a result, it is concluded that the radiation and reception characteristics of the antennas are not uniquely determined by k/sub p/a (k/sub p/ is the wave number of an electron plasma wave, and a is the radius of the circular-plate antenna), but are determined by two out of three factors, k/sub p/a, zeta (radius divided by Debye length), and ω/ω/sub p/ (angular signal frequency to angular plasma frequency). This conclusion is in marked contrast to the conventional theory in which the charge distribution on the antenna is assumed a priori as uniform and, thus, the antenna characteristics are uniquely determined by k/sub p/a. It is claimed that the experimental results obtained hitherto support the present new theory
Millimeter-Wave Thermal Analysis Development and Application to GEN IV Reactor Materials
Energy Technology Data Exchange (ETDEWEB)
Wosko, Paul; Sundram, S. K.
2012-10-16
New millimeter-wave thermal analysis instrumentation has been developed and studied for characterization of materials required for diverse fuel and structural needs in high temperature reactor environments such as the Next Generation Nuclear Plant (NGNP). A two-receiver 137 GHz system with orthogonal polarizations for anisotropic resolution of material properties has been implemented at MIT. The system was tested with graphite and silicon carbide specimens at temperatures up to 1300 ºC inside an electric furnace. The analytic and hardware basis for active millimeter-wave radiometry of reactor materials at high temperature has been established. Real-time, non contact measurement sensitivity to anisotropic surface emissivity and submillimeter surface displacement was demonstrated. The 137 GHz emissivity of reactor grade graphite (NBG17) from SGL Group was found to be low, ~ 5 %, in the 500 – 1200 °C range and increases by a factor of 2 to 4 with small linear grooves simulating fracturing. The low graphite emissivity would make millimeter-wave active radiometry a sensitive diagnostic of graphite changes due to environmentally induced stress fracturing, swelling, or corrosion. The silicon carbide tested from Ortek, Inc. was found to have a much higher emissivity at 137 GHz of ~90% Thin coatings of silicon carbide on reactor grade graphite supplied by SGL Group were found to be mostly transparent to millimeter-waves, increasing the 137 GHz emissivity of the coated reactor grade graphite to about ~14% at 1250 ºC.
Geo-spatial multi-criteria analysis for wave energy conversion system deployment
Energy Technology Data Exchange (ETDEWEB)
Nobre, Ana; Pacheco, Miguel [Data Centre, Instituto Hidrografico, Portuguese Navy, Rua das Trinas 49, 1249-093 Lisboa (Portugal); Jorge, Raquel; Lopes, M.F.P.; Gato, L.M.C. [IDMEC, Instituto Superior Tecnico, Technical University of Lisbon, Avenida Rovisco Pais 1, 1049-001, Lisboa (Portugal)
2009-01-15
The growing requirements for renewable energy production lead to the development of a new series of systems, including wave energy conversion systems. Due to their sensitivity and the impact of the aggressive marine environment, the selection of the most adequate location for these systems is a major and very important task. Several factors, such as technological limitations, environmental conditions, administrative and logistic conditions, have to be taken into account in order to support the decision for best location. This paper describes a geo-spatial multi-criteria analysis methodology, based on geographic information systems technology, for identification of the best location to deploy a wave energy farm. This methodology is not conversion system dependent and therefore can be easily customized for different systems and implementation conditions. Selection factors can include, for example, ocean depth, sea bottom type, existing underwater cables, marine protected areas, ports location, shoreline, power grid location, military exercise areas, climatology of wave significant height, period and power. A case study demonstrating this methodology is presented, for an area offshore the Portuguese southwest coast. The system output allows a clear differential identification of the best spots for implementing a wave energy farm. It is not just a simple Boolean result showing valid and invalid locations, but a layer with a valued suitability for farm deployment. (author)
Geo-Spatial Multi-criteria Analysis for Wave Energy System Deployment
Energy Technology Data Exchange (ETDEWEB)
Nobre, Ana; Pacheco, Miguel (Instituto Hidrografico, Rua das Trinas, 49, Lisboa (PT)); Jorge, Raquel Lopes, M. F. P.; Gato, L. M. C. (IDMEC, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, Lisboa (PT))
2007-07-01
The growing requirements for renewable energy production lead to the development of a new series of systems, including wave energy conversion systems. Due to their sensitivity and the impact of the aggressive marine environment, the selection of the most adequate location for these systems is a major and very important task. Several factors, such as technological limitations, environmental conditions, administrative and logistic conditions, have to be taken into account in order to support the decision for best location. This paper describes a geo-spatial multi-criteria analysis methodology, based on geographic information systems technology, for selection of the best location to deploy a wave energy farm. This methodology is not conversion system dependent and therefore can be easily customized for different systems and conditions. Selection factors can include, for example, ocean depth, bottom type, underwater cables, marine protected areas, ports location, shoreline, power grid location, military exercise areas, climatology of wave significant height, period and direction. A case study demonstrating this methodology is presented, for an area offshore the Portuguese southwest coast. The system output allows a clear identification of the best spots for a wave energy farm. It is not just a simple Boolean result showing valid and invalid locations, but a layer with a graded suitability for farm deployment.
Nucleon-nucleon partial-wave analysis to 1100 MeV
International Nuclear Information System (INIS)
Arndt, R.A.; Hyslop, J.S. III; Roper, L.D.
1987-01-01
Comprehensive analyses of nucleon-nucleon elastic-scattering data below 1100 MeV laboratory kinetic energy are presented. The data base from which an energy-dependent solution and 22 single-energy solutions are obtained consists of 7223 pp and 5474 np data. A resonancelike structure is found to occur in the 1 D 2 , 3 F 3 , 3 P 2 - 3 F 2 , and 3 F 4 - 3 H 4 partial waves; this behavior is associated with poles in the complex energy plane. The pole positions and residues are obtained by analytic continuation of the ''production'' piece of the T matrix obtained in the energy-dependent solution. The new phases differ somewhat from previously published VPIandSU solutions, especially in I = 0 waves above 500 MeV, where np data are very sparse. The partial waves are, however, based upon a significantly larger data base and reflect correspondingly smaller errors. The full data base and solution files can be obtained through a computer scattering analysis interactive dial-in (SAID) system at VPIandSU, which also exists at many institutions around the world and which can be transferred to any site with a suitable computer system. The SAID system can be used to modify solutions, plan experiments, and obtain any of the multitude of predictions which derive from partial-wave analyses of the world data base
Simulation and scaling analysis of a spherical particle-laden blast wave
Ling, Y.; Balachandar, S.
2018-05-01
A spherical particle-laden blast wave, generated by a sudden release of a sphere of compressed gas-particle mixture, is investigated by numerical simulation. The present problem is a multiphase extension of the classic finite-source spherical blast-wave problem. The gas-particle flow can be fully determined by the initial radius of the spherical mixture and the properties of gas and particles. In many applications, the key dimensionless parameters, such as the initial pressure and density ratios between the compressed gas and the ambient air, can vary over a wide range. Parametric studies are thus performed to investigate the effects of these parameters on the characteristic time and spatial scales of the particle-laden blast wave, such as the maximum radius the contact discontinuity can reach and the time when the particle front crosses the contact discontinuity. A scaling analysis is conducted to establish a scaling relation between the characteristic scales and the controlling parameters. A length scale that incorporates the initial pressure ratio is proposed, which is able to approximately collapse the simulation results for the gas flow for a wide range of initial pressure ratios. This indicates that an approximate similarity solution for a spherical blast wave exists, which is independent of the initial pressure ratio. The approximate scaling is also valid for the particle front if the particles are small and closely follow the surrounding gas.
Vanel, Florence O.; Baysal, Oktay
1995-01-01
Important characteristics of the aeroacoustic wave propagation are mostly encoded in their dispersion relations. Hence, a computational aeroacoustic (CAA) algorithm, which reasonably preserves these relations, was investigated. It was derived using an optimization procedure to ensure, that the numerical derivatives preserved the wave number and angular frequency of the differential terms in the linearized, 2-D Euler equations. Then, simulations were performed to validate the scheme and a compatible set of discretized boundary conditions. The computational results were found to agree favorably with the exact solutions. The boundary conditions were transparent to the outgoing waves, except when the disturbance source was close to a boundary. The time-domain data generated by such CAA solutions were often intractable until their spectra was analyzed. Therefore, the relative merits of three different methods were included in the study. For simple, periodic waves, the periodogram method produced better estimates of the steep-sloped spectra than the Blackman-Tukey method. Also, for this problem, the Hanning window was more effective when used with the weighted-overlapped-segment-averaging and Blackman-Tukey methods gave better results than the periodogram method. Finally, it was demonstrated that the representation of time domain-data was significantly dependent on the particular spectral analysis method employed.
Simulation and scaling analysis of a spherical particle-laden blast wave
Ling, Y.; Balachandar, S.
2018-02-01
A spherical particle-laden blast wave, generated by a sudden release of a sphere of compressed gas-particle mixture, is investigated by numerical simulation. The present problem is a multiphase extension of the classic finite-source spherical blast-wave problem. The gas-particle flow can be fully determined by the initial radius of the spherical mixture and the properties of gas and particles. In many applications, the key dimensionless parameters, such as the initial pressure and density ratios between the compressed gas and the ambient air, can vary over a wide range. Parametric studies are thus performed to investigate the effects of these parameters on the characteristic time and spatial scales of the particle-laden blast wave, such as the maximum radius the contact discontinuity can reach and the time when the particle front crosses the contact discontinuity. A scaling analysis is conducted to establish a scaling relation between the characteristic scales and the controlling parameters. A length scale that incorporates the initial pressure ratio is proposed, which is able to approximately collapse the simulation results for the gas flow for a wide range of initial pressure ratios. This indicates that an approximate similarity solution for a spherical blast wave exists, which is independent of the initial pressure ratio. The approximate scaling is also valid for the particle front if the particles are small and closely follow the surrounding gas.
Dynamic Analysis of Wind Power Turbine's Tower under the Combined Action of Winds and Waves
Institute of Scientific and Technical Information of China (English)
CHENG You-liang; QU Jiang-man; XUE Zhan-pu; JIANG Yan
2017-01-01
To deal with the dynamic response problem of offshore wind power tower under the combined action of winds and waves,finite element method is used to analyze the structure and flow field around the outside flange of the segmentation part.The changes of pressure distribution and vorticity about the outside flange are obtained.Focused on the analysis on the change of hydrostatic pressure and temperature of the tower cut surface,contour lines under the combined action of winds and waves are depicted.Results show that the surface of the offshore wind turbine tower presents instable temperature field when it suffers the action of winds and waves loads,the static pressure increases nonlinearly with the increase of altitude,the fluid vorticity around the outside flange follows an parabolic curve approximately.Results provide a reference for the actual monitoring data of the offshore wind turbine tower under the combined action of winds and waves,so as to ensure the normal operation of tower.
Parameter sensitivity and uncertainty analysis for a storm surge and wave model
Directory of Open Access Journals (Sweden)
L. A. Bastidas
2016-09-01
Full Text Available Development and simulation of synthetic hurricane tracks is a common methodology used to estimate hurricane hazards in the absence of empirical coastal surge and wave observations. Such methods typically rely on numerical models to translate stochastically generated hurricane wind and pressure forcing into coastal surge and wave estimates. The model output uncertainty associated with selection of appropriate model parameters must therefore be addressed. The computational overburden of probabilistic surge hazard estimates is exacerbated by the high dimensionality of numerical surge and wave models. We present a model parameter sensitivity analysis of the Delft3D model for the simulation of hazards posed by Hurricane Bob (1991 utilizing three theoretical wind distributions (NWS23, modified Rankine, and Holland. The sensitive model parameters (of 11 total considered include wind drag, the depth-induced breaking γB, and the bottom roughness. Several parameters show no sensitivity (threshold depth, eddy viscosity, wave triad parameters, and depth-induced breaking αB and can therefore be excluded to reduce the computational overburden of probabilistic surge hazard estimates. The sensitive model parameters also demonstrate a large number of interactions between parameters and a nonlinear model response. While model outputs showed sensitivity to several parameters, the ability of these parameters to act as tuning parameters for calibration is somewhat limited as proper model calibration is strongly reliant on accurate wind and pressure forcing data. A comparison of the model performance with forcings from the different wind models is also presented.
Black-hole quasinormal resonances: Wave analysis versus a geometric-optics approximation
International Nuclear Information System (INIS)
Hod, Shahar
2009-01-01
It has long been known that null unstable geodesics are related to the characteristic modes of black holes--the so-called quasinormal resonances. The basic idea is to interpret the free oscillations of a black hole in the eikonal limit in terms of null particles trapped at the unstable circular orbit and slowly leaking out. The real part of the complex quasinormal resonances is related to the angular velocity at the unstable null geodesic. The imaginary part of the resonances is related to the instability time scale (or the inverse Lyapunov exponent) of the orbit. While this geometric-optics description of the black-hole quasinormal resonances in terms of perturbed null rays is very appealing and intuitive, it is still highly important to verify the validity of this approach by directly analyzing the Teukolsky wave equation which governs the dynamics of perturbation waves in the black-hole spacetime. This is the main goal of the present paper. We first use the geometric-optics technique of perturbing a bundle of unstable null rays to calculate the resonances of near-extremal Kerr black holes in the eikonal approximation. We then directly solve the Teukolsky wave equation (supplemented by the appropriate physical boundary conditions) and show that the resultant quasinormal spectrum obtained directly from the wave analysis is in accord with the spectrum obtained from the geometric-optics approximation of perturbed null rays.
Bouwmeester, J Christopher; Park, Jiheum; Valdovinos, John; Bonde, Pramod
2018-05-29
Changing the speed of left ventricular assist devices (LVADs) cyclically may be useful to restore aortic pulsatility; however, the effects of this pulsation on right ventricular (RV) function are unknown. This study investigates the effects of direct ventricular interaction by quantifying the amount of wave energy created by RV contraction when axial and centrifugal LVADs are used to assist the left ventricle. In 4 anesthetized pigs, pressure and flow were measured in the main pulmonary artery and wave intensity analysis was used to identify and quantify the energy of waves created by the RV. The axial pump depressed the intensity of waves created by RV contraction compared with the centrifugal pump. In both pump designs, there were only minor and variable differences between the continuous and pulsed operation on RV function. The axial pump causes the RV to contract with less energy compared with a centrifugal design. Diminishing the ability of the RV to produce less energy translates to less pressure and flow produced, which may lead to LVAD-induced RV failure. The effects of pulsed LVAD operation on the RV appear to be minimal during acute observation of healthy hearts. Further study is necessary to uncover the effects of other modes of speed modulation with healthy and unhealthy hearts to determine if pulsed operation will benefit patients by reducing LVAD complications.
Angle-domain Migration Velocity Analysis using Wave-equation Reflection Traveltime Inversion
Zhang, Sanzong
2012-11-04
The main difficulty with an iterative waveform inversion is that it tends to get stuck in a local minima associated with the waveform misfit function. This is because the waveform misfit function is highly non-linear with respect to changes in the velocity model. To reduce this nonlinearity, we present a reflection traveltime tomography method based on the wave equation which enjoys a more quasi-linear relationship between the model and the data. A local crosscorrelation of the windowed downgoing direct wave and the upgoing reflection wave at the image point yields the lag time that maximizes the correlation. This lag time represents the reflection traveltime residual that is back-projected into the earth model to update the velocity in the same way as wave-equation transmission traveltime inversion. The residual movemout analysis in the angle-domain common image gathers provides a robust estimate of the depth residual which is converted to the reflection traveltime residual for the velocity inversion. We present numerical examples to demonstrate its efficiency in inverting seismic data for complex velocity model.
International Nuclear Information System (INIS)
Sergeev, Alexey; Herman, Michael F.
2006-01-01
The behavior of an initial value representation surface hopping wave function is examined. Since this method is an initial value representation for the semiclassical solution of the time independent Schroedinger equation for nonadiabatic problems, it has computational advantages over the primitive surface hopping wave function. The primitive wave function has been shown to provide transition probabilities that accurately compare with quantum results for model problems. The analysis presented in this work shows that the multistate initial value representation surface hopping wave function should approach the primitive result in asymptotic regions and provide transition probabilities with the same level of accuracy for scattering problems as the primitive method
International Nuclear Information System (INIS)
Abbasbandy, S.
2009-01-01
Solitary wave solutions to the modified form of Camassa-Holm (CH) equation are sought. In this work, the homotopy analysis method (HAM), one of the most effective method, is applied to obtain the soliton wave solutions with and without continuity of first derivatives at crest
PCT Uncertainty Analysis Using Unscented Transform with Random Orthogonal Matrix
Energy Technology Data Exchange (ETDEWEB)
Fynana, Douglas A.; Ahn, Kwang-Il [KAERI, Daejeon (Korea, Republic of); Lee, John C. [Univ. of Michigan, Michigan (United States)
2015-05-15
Most Best Estimate Plus Uncertainty (BEPU) methods employ nonparametric order statistics through Wilks' formula to quantify uncertainties of best estimate simulations of nuclear power plant (NPP) transients. 95%/95% limits, the 95''t{sup h} percentile at a 95% confidence level, are obtained by randomly sampling all uncertainty contributors through conventional Monte Carlo (MC). Advantages are simple implementation of MC sampling of input probability density functions (pdfs) and limited computational expense of 1''s{sup t}, 2''n{sup d}, and 3''r{sup d} order Wilks' formula requiring only 59, 93, or 124 simulations, respectively. A disadvantage of small sample size is large sample to sample variation of statistical estimators. This paper presents a new efficient sampling based algorithm for accurate estimation of mean and variance of the output parameter pdf. The algorithm combines a deterministic sampling method, the unscented transform (UT), with random sampling through the generation of a random orthogonal matrix (ROM). The UT guarantees the mean, covariance, and 3''r{sup d} order moments of the multivariate input parameter distributions are exactly preserved by the sampled input points and the orthogonal transformation of the points by a ROM guarantees the sample error of all 4''t{sup h} order and higher moments are unbiased. The UT with ROM algorithm is applied to the uncertainty quantification of the peak clad temperature (PCT) during a large break loss-of-coolant accident (LBLOCA) in an OPR1000 NPP to demonstrate the applicability of the new algorithm to BEPU. This paper presented a new algorithm combining the UT with ROM for efficient multivariate parameter sampling that ensures sample input covariance and 3''r{sup d} order moments are exactly preserved and 4''th moment errors are small and unbiased. The advantageous sample properties guarantee higher order accuracy and
An application of random field theory to analysis of electron trapping sites in disordered media
International Nuclear Information System (INIS)
Hilczer, M.; Bartczak, W.M.
1993-01-01
The potential energy surface in a disordered medium is considered a random field and described using the concepts of the mathematical theory of random fields. The preexisting traps for excess electrons are identified with certain regions of excursion (extreme regions) of the potential field. The theory provides an analytical method of statistical analysis of these regions. Parameters of the cavity-averaged potential field, which are provided by computer simulation of a given medium, serve as input data for the analysis. The statistics of preexisting traps are obtained for liquid methanol as a numerical example of the random field method. 26 refs., 6 figs
Azzellino, Arianna; Contestabile, Pasquale; Lanfredi, Caterina; Vicinanza, Diego
2010-05-01
The exploitation of renewable energy resources is fast becoming a key objective in many countries. Countries with coastlines have particularly valuable renewable energy resources in the form of tides, currents, waves and offshore wind. Due to the visual impact of siting large numbers of energy generating devices (eg. wind turbines) in terrestrial landscapes, considerable attention is now being directed towards coastal waters. Due to their environmental sensitivity, the selection of the most adequate location for these systems is a critical factor. Multi-criteria analysis allows to consider a wide variety of key characteristics (e.g. water depth, distance to shore, distance to the electric grid in land, geology, environmental impact) that may be converted into a numerical index of suitability for different WEC devices to different locations. So identifying the best alternative between an offshore or a onshore device may be specifically treated as a multicriteria problem. Special enphasisi should be given in the multicriteria analysis to the environmental impact issues. The wave energy prospective in the Italian seas is relatively low if compared to the other European countries faced to the ocean. Based on the wave climate, the Alghero site, (NW Sardinia, Italy) is one of the most interesting sites for the wave energy perspective (about 10 kW/m). Alghero site is characterized by a high level of marine biodiversity. In 2002 the area northern to Alghero harbour (Capo Caccia-Isola Piana) was established a Marine Protected Area (MPA). It could be discussed for this site how to choose between the onshore/offshore WEC alternative. An offshore device like Wave Dragon (http://www.wavedragon.net/) installed at -65m depth (width=300m and length=170 m) may approximately produce about 3.6 GWh/y with a total cost of about 9,000,000 €. On the other hand, an onshore device like SSG (http://waveenergy.no/), employed as crown wall for a vertical breakwater to enlarge the present
Conditional Random Fields for Morphological Analysis of Wireless ECG Signals
Natarajan, Annamalai; Gaiser, Edward; Angarita, Gustavo; Malison, Robert; Ganesan, Deepak; Marlin, Benjamin
2015-01-01
Thanks to advances in mobile sensing technologies, it has recently become practical to deploy wireless electrocardiograph sensors for continuous recording of ECG signals. This capability has diverse applications in the study of human health and behavior, but to realize its full potential, new computational tools are required to effectively deal with the uncertainty that results from the noisy and highly non-stationary signals collected using these devices. In this work, we present a novel approach to the problem of extracting the morphological structure of ECG signals based on the use of dynamically structured conditional random field (CRF) models. We apply this framework to the problem of extracting morphological structure from wireless ECG sensor data collected in a lab-based study of habituated cocaine users. Our results show that the proposed CRF-based approach significantly out-performs independent prediction models using the same features, as well as a widely cited open source toolkit. PMID:26726321
Czech Academy of Sciences Publication Activity Database
Dal Moro, Giancarlo; Moustafa, S.S.R.; Al-Arifi, N.
2018-01-01
Roč. 175, č. 1 (2018), s. 67-88 ISSN 0033-4553 Institutional support: RVO:67985891 Keywords : surface wave dispersion * joint inversion of seismic data * Rayleigh waves * holistic analysis of surface waves Impact factor: 1.591, year: 2016
Dombrowski, M. P.; Labelle, J. W.; Kletzing, C.; Bounds, S. R.; Kaeppler, S. R.
2014-12-01
Langmuir-mode electron plasma waves are frequently observed by spacecraft in active plasma environments such as the ionosphere. Ionospheric Langmuir waves may be excited by the bump-on-tail instability generated by impinging beams of electrons traveling parallel to the background magnetic field (B). The Correlation of High-frequencies and Auroral Roar Measurement (CHARM II) sounding rocket was launched into a substorm at 9:49 UT on 17 February 2010, from the Poker Flat Research Range in Alaska. The primary instruments included the University of Iowa Wave-Particle Correlator (WPC), the Dartmouth High-Frequency Experiment (HFE), several charged particle detectors, low-frequency wave instruments, and a magnetometer. The HFE is a receiver system which effectively yields continuous (100% duty cycle) electric-field waveform measurements from 100 kHz to 5 MHz, and which had its detection axis aligned nominally parallel to B. The HFE output was fed on-payload to the WPC, which uses a phase-locked loop to track the incoming wave frequency with the most power, then sorting incoming electrons at eight energy levels into sixteen wave-phase bins. CHARM II encountered several regions of strong Langmuir wave activity throughout its 15-minute flight, and the WPC showed wave-lock and statistically significant particle correlation distributions during several time periods. We show results of an in-depth analysis of the CHARM II WPC data for the entire flight, including statistical analysis of correlations which show evidence of direct interaction with the Langmuir waves, indicating (at various times) trapping of particles and both driving and damping of Langmuir waves by particles. In particular, the sign of the gradient in particle flux appears to correlate with the phase relation between the electrons and the wave field, with possible implications for the wave physics.
The Coronal Analysis of SHocks and Waves (CASHeW) framework
Kozarev, Kamen A.; Davey, Alisdair; Kendrick, Alexander; Hammer, Michael; Keith, Celeste
2017-11-01
Coronal bright fronts (CBF) are large-scale wavelike disturbances in the solar corona, related to solar eruptions. They are observed (mostly in extreme ultraviolet (EUV) light) as transient bright fronts of finite width, propagating away from the eruption source location. Recent studies of individual solar eruptive events have used EUV observations of CBFs and metric radio type II burst observations to show the intimate connection between waves in the low corona and coronal mass ejection (CME)-driven shocks. EUV imaging with the atmospheric imaging assembly instrument on the solar dynamics observatory has proven particularly useful for detecting large-scale short-lived CBFs, which, combined with radio and in situ observations, holds great promise for early CME-driven shock characterization capability. This characterization can further be automated, and related to models of particle acceleration to produce estimates of particle fluxes in the corona and in the near Earth environment early in events. We present a framework for the coronal analysis of shocks and waves (CASHeW). It combines analysis of NASA Heliophysics System Observatory data products and relevant data-driven models, into an automated system for the characterization of off-limb coronal waves and shocks and the evaluation of their capability to accelerate solar energetic particles (SEPs). The system utilizes EUV observations and models written in the interactive data language. In addition, it leverages analysis tools from the SolarSoft package of libraries, as well as third party libraries. We have tested the CASHeW framework on a representative list of coronal bright front events. Here we present its features, as well as initial results. With this framework, we hope to contribute to the overall understanding of coronal shock waves, their importance for energetic particle acceleration, as well as to the better ability to forecast SEP events fluxes.
Dynamic analysis of the conditional oscillator underlying slow waves in thalamocortical neurons
Directory of Open Access Journals (Sweden)
Francois eDavid
2016-02-01
Full Text Available During non-REM sleep the EEG shows characteristics waves that are generated by the dynamic interactions between cortical and thalamic oscillators. In thalamic neurons, low-threshold T-type Ca2+ channels play a pivotal role in almost every type of neuronal oscillations, including slow (<1 Hz waves, sleep spindles and delta waves. The transient opening of T channels gives rise to the low threshold spikes (LTSs, and associated high frequency bursts of action potentials, that are characteristically present during sleep spindles and delta waves, whereas the persistent opening of a small fraction of T channels, (i.e. ITwindow is responsible for the membrane potential bistability underlying sleep slow oscillations. Surprisingly thalamocortical (TC neurons express a very high density of T channels that largely exceed the amount required to generate LTSs and therefore, to support certain, if not all, sleep oscillations. Here, to clarify the relationship between T current density and sleep oscillations, we systematically investigated the impact of the T conductance level on the intrinsic rhythmic activities generated in TC neurons, combining in vitro experiments and TC neuron simulation. Using bifurcation analysis, we provide insights into the dynamical processes taking place at the transition between slow and delta oscillations. Our results show that although stable delta oscillations can be evoked with minimal T conductance, the full range of slow oscillation patterns, including groups of delta oscillations separated by Up states (grouped-delta slow waves requires a high density of T channels. Moreover, high levels of T conductance ensure the robustness of different types of slow oscillations.
Random effects coefficient of determination for mixed and meta-analysis models.
Demidenko, Eugene; Sargent, James; Onega, Tracy
2012-01-01
The key feature of a mixed model is the presence of random effects. We have developed a coefficient, called the random effects coefficient of determination, [Formula: see text], that estimates the proportion of the conditional variance of the dependent variable explained by random effects. This coefficient takes values from 0 to 1 and indicates how strong the random effects are. The difference from the earlier suggested fixed effects coefficient of determination is emphasized. If [Formula: see text] is close to 0, there is weak support for random effects in the model because the reduction of the variance of the dependent variable due to random effects is small; consequently, random effects may be ignored and the model simplifies to standard linear regression. The value of [Formula: see text] apart from 0 indicates the evidence of the variance reduction in support of the mixed model. If random effects coefficient of determination is close to 1 the variance of random effects is very large and random effects turn into free fixed effects-the model can be estimated using the dummy variable approach. We derive explicit formulas for [Formula: see text] in three special cases: the random intercept model, the growth curve model, and meta-analysis model. Theoretical results are illustrated with three mixed model examples: (1) travel time to the nearest cancer center for women with breast cancer in the U.S., (2) cumulative time watching alcohol related scenes in movies among young U.S. teens, as a risk factor for early drinking onset, and (3) the classic example of the meta-analysis model for combination of 13 studies on tuberculosis vaccine.
Nassar, Amer H; Dorizas, Andrew S; Shafai, Aria; Sadick, Neil S
2015-03-01
There is an increased demand for the reduction of localized adipose tissue by noninvasive methods. The objective of this study was to determine the safety and efficacy of noninvasive lipolysis of excess adiposities overlying the lateral thigh region using acoustic wave therapy (AWT). This study incorporates 2 mechanical waves with varying properties in the same session: radial and planar AWT. The treatment was performed using AWT on the lateral thigh areas of 15 female patients. The study was performed using the planar and radial pulse handpieces, with 8 sessions performed within 4 weeks. Follow-up visits were performed 1, 4, and 12 weeks after the last treatment. Reduction in both thigh circumference and subcutaneous fat layer thickness, measured through ultrasound, was observed. This study demonstrates that AWT is safe and efficacious for the treatment of localized adiposities in the saddlebag area. However, the results obtained were not statistically significant. Larger studies will be needed to further access the effects of AWT on thigh circumference reduction. Furthermore, the authors also found an improvement in the appearance of both cellulite and skin firmness after the treatments.
Gialafos, Elias J; Dilaveris, Polychronis E; Synetos, Andreas G; Tsolakidis, George F; Papaioannou, Theodoros G; Andrikopoulos, George K; Richter, Dimitris J; Triposkiadis, Filippos; Gialafos, John E
2003-01-01
P wave analysis from the 12-lead ECG is a recent contribution of noninvasive electrocardiology. P wave analysis indices (maximum and minimum P wave duration, P wave dispersion [Pdis = Pmax-Pmin], adjusted P wave dispersion [APdis = Pdis/square root of measured leads], summated P wave duration [Psum], standard deviation of P wave duration [Psd], mean P wave duration [Pmean]) can predict atrial arrhythmias. However, the definitions of all these indices are based on few studies. The aim of this analysis was to define normal values of these indices and the examine possible associations between P wave indices and clinical variables. The study included 1,353 healthy men, 24 +/- 3 years of age, who answered a questionnaire and underwent a detailed physical examination and a digitized 12-lead surface ECG. All P wave indices were analyzed by two independent investigators. Mean values of the ECG indices were: Pmax: 96 +/- 11 ms, Pmin: 57 +/- 9 ms, Pdis: 38 +/- 10 ms, Psum: 924 +/- 96 ms, Psd: 12 +/- 3, APdis: 11 +/- 3 ms, and Pmean: 77 +/- 8 ms. Age was significantly related with Pmax (r = 0.277, P < 0.01), Pmin (r = 0.255, P < 0.001), Psum (r = 0.074, P < 0.01), and Pmean (r = 0.074, P < 0.01). All ECG indices were significantly associated with the R-R interval, and among each other. This study defined normal indices of wave duration and correlations among them. These markers may play an important predictive role in patients with atrial conduction abnormalities.
An introduction to random vibrations, spectral & wavelet analysis
Newland, D E
2005-01-01
One of the first engineering books to cover wavelet analysis, this classic text describes and illustrates basic theory, with a detailed explanation of the workings of discrete wavelet transforms. Computer algorithms are explained and supported by examples and a set of problems, and an appendix lists ten computer programs for calculating and displaying wavelet transforms.Starting with an introduction to probability distributions and averages, the text examines joint probability distributions, ensemble averages, and correlation; Fourier analysis; spectral density and excitation response relation
An analysis of current drive by travelling wave based on theory of intrinsic stochasticity
International Nuclear Information System (INIS)
Murakami, Akihiko; Midzuno, Yukio.
1982-04-01
The mechanism of the current generation in a collisionless plasma by a train of travelling mirrors with modulated phase velocity is studied based on the theory of intrinsic stochasticity. It is shown that, if the phase modulation is small, the main contribution to the current generation comes from the phase mixing of the trajectories of trapped electrons in each Fourier component of a driving wave. For the case of a moderate phase modulation, however, formation of a large stochastic region due to the overlapping of primary resonances is very effective for increasing the generated current. Large phase modulation has little advantage in the current generation because the stochastic regions are formed, so to speak, at random in the phase plane. The results of analytical evaluation based on the above theory agree quite well with results of numerical experiments. (author)
Partial wave analysis of the 18O(p,α0)15N reaction
International Nuclear Information System (INIS)
Wild, L.W.J.; Spicer, B.M.
1979-01-01
A partial wave analysis of the differential cross sections for the 18 O(p,α 0 ) 15 N reaction has been carried out applying the formalism of Blatt and Biedenharn (1952), made specific for this reaction. The differential cross sections, measured at 200 keV intervals from 6.6 to 10.4 MeV bombarding energy, were subjected to least-squares fitting to this specific analytic expression. Two resonances were given by the analysis, the 19 F states being at 14.71+-0.07 MeV (1/2 - ) and 14.80 + 0.07 MeV (1/2) +
Evaluation of arterial propagation velocity based on the automated analysis of the Pulse Wave Shape
International Nuclear Information System (INIS)
Clara, F M; Scandurra, A G; Meschino, G J; Passoni, L I
2011-01-01
This paper proposes the automatic estimation of the arterial propagation velocity from the pulse wave raw records measured in the region of the radial artery. A fully automatic process is proposed to select and analyze typical pulse cycles from the raw data. An adaptive neuro-fuzzy inference system, together with a heuristic search is used to find a functional approximation of the pulse wave. The estimation of the propagation velocity is carried out via the analysis of the functional approximation obtained with the fuzzy model. The analysis of the pulse wave records with the proposed methodology showed small differences compared with the method used so far, based on a strong interaction with the user. To evaluate the proposed methodology, we estimated the propagation velocity in a population of healthy men from a wide range of ages. It has been found in these studies that propagation velocity increases linearly with age and it presents a considerable dispersion of values in healthy individuals. We conclude that this process could be used to evaluate indirectly the propagation velocity of the aorta, which is related to physiological age in healthy individuals and with the expectation of life in cardiovascular patients.
International Nuclear Information System (INIS)
Laye epouse Granier, Agnes
1986-01-01
This report deals with the study of microwave discharges produced in argon gas by surface waves in the 20-760 Torr pressure range. Application to chemical analysis by emission optical spectroscopy is also investigated. First of all we study the propagation of a surface wave in a bounded plasma in which the effective collision frequency for momentum transfer ν is higher than the excitation one. The axial electron density profile is determined from two diagnostic techniques, i.e., phase variations of the wave field and Stark broadening of H β line. Then we deduce the discharge characteristics ν, θ (maintaining power of an electron-ion pair) and E eff (effective electric field for discharge sustaining) from the electron density profile. Then an energy balance of the discharge is developed. It explains the change of operating conditions in the 20-50 Torr range. At low pressure the discharge is governed by ambipolar diffusion whereas at high pressure, the electrons are mainly lost by volume recombination of Ar 2 + . Finally, we report on chemical analysis experiment of gases (optimum sensibility in found near 100 Torr) and of metallic solutions sprayed by a graphite oven. Performances of such a design and ICP plasma torches are compared. (author) [fr
Infinite hidden conditional random fields for human behavior analysis.
Bousmalis, Konstantinos; Zafeiriou, Stefanos; Morency, Louis-Philippe; Pantic, Maja
2013-01-01
Hidden conditional random fields (HCRFs) are discriminative latent variable models that have been shown to successfully learn the hidden structure of a given classification problem (provided an appropriate validation of the number of hidden states). In this brief, we present the infinite HCRF (iHCRF), which is a nonparametric model based on hierarchical Dirichlet processes and is capable of automatically learning the optimal number of hidden states for a classification task. We show how we learn the model hyperparameters with an effective Markov-chain Monte Carlo sampling technique, and we explain the process that underlines our iHCRF model with the Restaurant Franchise Rating Agencies analogy. We show that the iHCRF is able to converge to a correct number of represented hidden states, and outperforms the best finite HCRFs--chosen via cross-validation--for the difficult tasks of recognizing instances of agreement, disagreement, and pain. Moreover, the iHCRF manages to achieve this performance in significantly less total training, validation, and testing time.
Acoustically Generated Flows in Flexural Plate Wave Sensors: a Multifield Analysis
Sayar, Ersin; Farouk, Bakhtier
2011-11-01
Acoustically excited flows in a microchannel flexural plate wave device are explored numerically with a coupled solid-fluid mechanics model. The device can be exploited to integrate micropumps with microfluidic chips. A comprehensive understanding of the device requires the development of coupled two or three-dimensional fluid structure interactive (FSI) models. The channel walls are composed of layers of ZnO, Si3N4 and Al. An isothermal equation of state for the fluid (water) is employed. The flexural motions of the channel walls and the resulting flowfields are solved simultaneously. A parametric analysis is performed by varying the values of the driving frequency, voltage of the electrical signal and the channel height. The time averaged axial velocity is found to be proportional to the square of the wave amplitude. The present approach is superior to the method of successive approximations where the solid-liquid coupling is weak.
Partial wave analysis of ι/η(1430) from DM2
International Nuclear Information System (INIS)
Augustin, J.E.; Cosme, G.; Couchot, F.; Fulda, F.; Grosdidier, G.; Jean-Marie, B.; Lepeltier, V.; Mane, M.; Szklarz, G.; Jousset, J.; Ajaltouni, Z.; Falvard, A.; Michel, B.; Montret, J.C.
1989-12-01
A Partial Wave Analysis of the ι/η (1430) region from the study of the radiative decays J/Ψ → γ K S 0 K ± π -+ and J/Ψ → γ K ± K -+ π 0 is presented. Pseudoscalar dominance appears clearly with two dynamical components. The main one which proceeds via δ/a 0 (980) π is centered at 1460 MeV/c 2 , while the second one with K*(892) K dynamics is peaked at a lower mass (1420 MeV/c 2 ) close to its kinematical threshold. In addition, the higher part of the mass spectrum contains a significant contribution from the 1 ++ K*(892)K wave
Partial wave analysis of DM2 data in the η(1430) energy range
International Nuclear Information System (INIS)
Augustin, J.E.; Cosme, G.; Couchot, F.; Fulda, F.; Grosdidier, G.; Jean-Marie, B.; Lepeltier, V.; Szklarz, G.; Bisello, D.; Busetto, G.; Castro, A.; Pescara, L.; Sartori, P.; Stanco, L.; Ajaltouni, Z.; Falvard, A.; Jousset, J.; Michel, B.; Montret, J.C.
1990-10-01
Partial Wave Analysis of the J/ψ → γK S 0 K ± π -+ , γK ± K -+ π 0 decays in the ι/η(1430) mass range shows a clear pseudoscalar dominance, with two dynamical components. The main one, centered at ∼ 1460 MeV/c 2 , proceeds via a 0 (980)π dynamics, while the second one with K*(892)K dynamics is peaked at ∼ 1420 MeV/c 2 , close to its threshold. In addition, the higher part of the mass spectrum contains a significant contribution from the 1 ++ K*(892)K wave. In the PWA of the J/ψ → γηπ + π - channel a resonant a 0 π production is observed slightly below 1400 MeV/c 2
Partial wave analysis of anti pp → anti ΛΛ
International Nuclear Information System (INIS)
Bugg, D.V.
2004-01-01
A partial wave analysis of PS185 data for anti pp → anti ΛΛ is presented. A 3 S 1 cusp is identified in the inverse process anti ΛΛ→ anti p p at threshold, using detailed balance to deduce cross sections from anti pp → anti ΛΛ. Partial wave amplitudes for anti pp 3 P 0 , 3 F 3 , 3 D 3 and 3 G 3 exhibit a behaviour very similar to resonances observed in Crystal Barrel data. With this identification, the anti pp → anti ΛΛ data then provide evidence for a new I=0, J PC =1 - resonance with mass M = 2290 ±20 MeV, Γ= 275 ±35 MeV, coupling to both 3 S 1 and 3 D 1 . (orig.)
Directory of Open Access Journals (Sweden)
Dejan Jaksic
2017-01-01
Full Text Available Mathematical modelling of the behavior of the radio propagation at mmWave bands is crucial to the development of transmission and reception algorithms of new 5G systems. In this study we will model 5G propagation in nondeterministic line-of-sight (LOS conditions, when the random nature of LOS component ratio will be observed as Inverse Gamma (IG distributed process. Closed-form expressions will be presented for the probability density function (PDF and cumulative distribution function (CDF of such random process. Further, closed-form expressions will be provided for important performance measures such as level crossing rate (LCR and average fade duration (AFD. Capitalizing on proposed expressions, LCR and AFD will be discussed in the function of transmission parameters.
Screening of Available Tools for Dynamic Mooring Analysis of Wave Energy Converters
Directory of Open Access Journals (Sweden)
Jonas Bjerg Thomsen
2017-06-01
Full Text Available The focus on alternative energy sources has increased significantly throughout the last few decades, leading to a considerable development in the wave energy sector. In spite of this, the sector cannot yet be considered commercialized, and many challenges still exist, in which mooring of floating wave energy converters is included. Different methods for assessment and design of mooring systems have been described by now, covering simple quasi-static analysis and more advanced and sophisticated dynamic analysis. Design standards for mooring systems already exist, and new ones are being developed specifically forwave energy converter moorings, which results in other requirements to the chosen tools, since these often have been aimed at other offshore sectors. The present analysis assesses a number of relevant commercial software packages for full dynamic mooring analysis in order to highlight the advantages and drawbacks. The focus of the assessment is to ensure that the software packages are capable of fulfilling the requirements of modeling, as defined in design standards and thereby ensuring that the analysis can be used to get a certified mooring system. Based on the initial assessment, the two software packages DeepC and OrcaFlex are found to best suit the requirements. They are therefore used in a case study in order to evaluate motion and mooring load response, and the results are compared in order to provide guidelines for which software package to choose. In the present study, the OrcaFlex code was found to satisfy all requirements.
Analysis of monochromatic signals by using data from the detector of Allegro gravitational waves
International Nuclear Information System (INIS)
Oliveira, Fernanda Gomes de
2010-01-01
The present work is developed in the searching for monochromatic gravitational waves signals in ALLEGRO's data. We have two procedures for data analysis based on the periodogram of Welch, which a method for the detection of monochromatic signals in the middle of noise which basically makes power spectrum estimates using averaged modified periodograms. By using this method it was possible to obtain a power spectrum for the data which reinforce peaks due to monochromatic signals. The two procedures of analysis for the years 1997 and 1999, were focused on monitoring a peak that appears in the spectral density of ALLEGRO's detector, so called 'mystery mode' (near 887 Hz). We look for variations in the frequency of the mystery mode that agree with the variation of the Doppler effect. In the rst analysis we have used by the variation of daily and annual Doppler shift. For the second one, we have only searched annual Doppler shift. We have applied the periodogram of Welch in both tests in the raw data of the detector in the search for a real signal and we found some peaks that can be candidates of gravitational radiation only the second analysis. In order to test the method we used in both analysis a simulated gravitational wave signal modulated by the Doppler effect injected in the data. We detected in both methods the artificial signal of GW simulated. Therefore we have reason to conclude that both methods are efficient in the search for monochromatic signals. (author)
Directory of Open Access Journals (Sweden)
Babak Vahdatpour
2012-01-01
Full Text Available Background and Aim: Results of previous studies have been conflicting on the efficacy of extracorporeal shock wave therapy (ESWT in the treatment of plantar fasciitis. We evaluated the effects of ESWT on plantar fasciitis in terms of ultrasonographic and subjective evaluations. Materials and Methods: In this randomized placebo-controlled trial, patients with plantar fasciitis were assigned to receive ESWT (4000 shock waves/session of 0.2 mJ/mm 2 in 3 sessions at weekly intervals or sham therapy (n = 20 in each group. Outcomes were documented by the ultrasonographic appearance of the aponeurosis and by patients′ pain scores, performed at baseline and 12 weeks after completion of the therapy. Results : The two groups were similar in baseline characteristics. Over the study period, plantar fascia thickness significantly reduced in the ESWT group (4.1 ± 1.3 to 3.6 ± 1.2 mm, P < 0.001, but slightly increased in the sham group (4.1 ± 0.8 to 4.5 ± 0.9 mm, P = 0.03. Both groups showed significant pain improvement over the course of the study (P < 0.001, though pain scores were significantly more reduced in the ESWT than the sham group (-4.2 ± 2.9 vs. -2.7 ± 1.8, P = 0.049. Conclusions: Extracorporeal shock wave therapy contributes to healing and pain reduction in plantar fasciitis and ultrasound imaging is able to depict the morphologic changes related to plantar fasciitis as a result of this therapy.
Sahlem, Gregory L; Badran, Bashar W; Halford, Jonathan J; Williams, Nolan R; Korte, Jeffrey E; Leslie, Kimberly; Strachan, Martha; Breedlove, Jesse L; Runion, Jennifer; Bachman, David L; Uhde, Thomas W; Borckardt, Jeffery J; George, Mark S
2015-01-01
A 2006 trial in healthy medical students found that anodal slow oscillating tDCS delivered bi-frontally during slow wave sleep had an enhancing effect in declarative, but not procedural memory. Although there have been supporting animal studies, and similar findings in pathological groups, this study has not been replicated, or refuted, in the intervening years. We therefore tested these earlier results for replication using similar methods with the exception of current waveform (square in our study, nearly sinusoidal in the original). Our objective was to test the findings of a 2006 trial suggesting bi-frontal anodal tDCS during slow wave sleep enhances declarative memory. Twelve students (mean age 25, 9 women) free of medical problems underwent two testing conditions (active, sham) in a randomized counterbalanced fashion. Active stimulation consisted of oscillating square wave tDCS delivered during early Non-Rapid Eye Movement (NREM) sleep. The sham condition consisted of setting-up the tDCS device and electrodes, but not turning it on during sleep. tDCS was delivered bi-frontally with anodes placed at F3/F4, and cathodes placed at mastoids. Current density was 0.517 mA/cm(2), and oscillated between zero and maximal current at a frequency of 0.75 Hz. Stimulation occurred during five-five minute blocks with 1-min inter-block intervals (25 min total stimulation). The primary outcomes were both declarative memory consolidation measured by a paired word association test (PWA), and non-declarative memory, measured by a non-dominant finger-tapping test (FTT). We also recorded and analyzed sleep EEG. There was no difference in the number of paired word associations remembered before compared to after sleep [(active = 3.1 ± 3.0 SD more associations) (sham = 3.8 ± 3.1 SD more associations)]. Finger tapping improved, (non-significantly) following active stimulation [(3.6 ± 2.7 SD correctly typed sequences) compared to sham stimulation (2.3 ± 2.2 SD correctly typed
Studies in astronomical time series analysis: Modeling random processes in the time domain
Scargle, J. D.
1979-01-01
Random process models phased in the time domain are used to analyze astrophysical time series data produced by random processes. A moving average (MA) model represents the data as a sequence of pulses occurring randomly in time, with random amplitudes. An autoregressive (AR) model represents the correlations in the process in terms of a linear function of past values. The best AR model is determined from sampled data and transformed to an MA for interpretation. The randomness of the pulse amplitudes is maximized by a FORTRAN algorithm which is relatively stable numerically. Results of test cases are given to study the effects of adding noise and of different distributions for the pulse amplitudes. A preliminary analysis of the optical light curve of the quasar 3C 273 is given.
Shimoji, Koki; Takahashi, Norio; Nishio, Yasuyuki; Koyanagi, Mika; Aida, Sumihisa
2007-01-01
Objectives. Newly developed bidirectional modulated sine waves (BMW) might provide some derived benefit to patients with low back pain. Pain relief by transcutaneous electric nerve stimulation (TENS) with BMWs was tested. Materials and Methods. Analgesic effects of BMWs and conventional bidirectional pulsed waves on chronic back pain in 28 patients were compared, and effects of repeated TENS using BMWs on chronic back pain were investigated in 21 patients by means of a randomized double-blind, sham-controlled, parallel-group method. Pain intensity was assessed using numerical rating scale (NRS). Results. There was significant immediate reduction in NRS in patients receiving BMWs, and 60 min after treatment compared to sham TENS. Weekly repeated treatments using massage and TENS with BMWs for 5 weeks resulted in a decrease of NRS, but there were no significant differences between the TENS plus massage and sham TENS plus massage groups. Conclusions. This study shows that TENS with BMWs significantly inhibits chronic back pain, and treatment effects are attained within a day. The results also suggest that there were no statistically significant long-term effects of TENS with BMW in the repeated treatment.
Sommerer, Claudia; Brocke, Janina; Bruckner, Thomas; Schaier, Matthias; Morath, Christian; Meuer, Stefan; Zeier, Martin; Giese, Thomas
2018-03-01
A new immune monitoring tool which assesses the expression of nuclear factor of activated T cells (NFAT)-regulated genes measures the functional effects of cyclosporine A. This is the first prospective randomized controlled study to compare standard pharmacokinetic monitoring by cyclosporine trough levels to NFAT-regulated gene expression (NFAT-RE). Expression of the NFAT-regulated genes was determined by qRT-PCR at cyclosporine trough and peak level. Cardiovascular risk was assessed by change of pulse wave velocity from baseline to month 6. Clinical follow-up was 12 months. In total, 55 stable kidney allograft recipients were enrolled. Mean baseline residual NFAT-RE was 13.1 ± 9.1%. Patients in the NFAT-RE group showed a significant decline in pulse wave velocity from baseline to month 6 versus the standard group (-1.7 ± 2.0 m/s vs 0.4 ± 1.4 m/s, P function was significantly better with NFAT-RE versus standard monitoring (Nankivell glomerular filtration rate: 68.5 ± 17.4 mL/min vs 57.2 ± 19.0 mL/min; P = 0.009). NFAT-RE as translational immune monitoring tool proved efficacious and safe in individualizing cyclosporine therapy, with the opportunity to reduce the cardiovascular risk and improve long-term renal allograft function.
Cameron, Chris; Fireman, Bruce; Hutton, Brian; Clifford, Tammy; Coyle, Doug; Wells, George; Dormuth, Colin R.; Platt, Robert; Toh, Sengwee
2015-01-01
Network meta-analysis is increasingly used to allow comparison of multiple treatment alternatives simultaneously, some of which may not have been compared directly in primary research studies. The majority of network meta-analyses published to date have incorporated data from randomized controlled trials (RCTs) only; however, inclusion of non-randomized studies may sometimes be considered. Non-randomized studies can complement RCTs or address some of their limitations, such as short follow-up...
Fracture analysis of randomized implant-supported fixed dental prostheses
Esquivel-Upshaw, Josephine F.; Mehler, Alex; Clark, Arthur E.; Neal, Dan; Anusavice, Kenneth J.
2014-01-01
Objective Fractures of posterior fixed dental all-ceramic prostheses can be caused by one or more factors including prosthesis design, flaw distribution, direction and magnitude of occlusal loading, and nature of supporting infrastructure (tooth root/implant), and presence of adjacent teeth. This clinical study of implant-supported, all-ceramic fixed dental prostheses, determined the effects of (1) presence of a tooth distal to the most distal retainer; (2) prosthesis loading either along the non-load bearing or load bearing areas; (3) presence of excursive contacts or maximum intercuspation contacts in the prosthesis; and (4) magnitude of bite force on the occurrence of veneer ceramic fracture. Methods 89 implant-supported FDPs were randomized as either a three-unit posterior metal-ceramic (Au-Pd-Ag alloy and InLine POM, Ivoclar, Vivadent) FDP or a ceramic-ceramic (ZirCAD and ZirPress, Ivoclar, Vivadent) FDP. Two implants (Osseospeed, Dentsply) and custom abutments (Atlantis, Dentsply) supported these FDPs, which were cemented with resin cement (RelyX Universal Cement). Baseline photographs were made with markings of teeth from maximum intercuspation (MI) and excursive function. Patients were recalled at 6 months and 1 to 3 years. Fractures were observed, their locations recorded, and images compared with baseline photographs of occlusal contacts. Conclusion No significant relationship exists between the occurrence of fracture and: (1) the magnitude of bite force; (2) a tooth distal to the most distal retainer; and (3) contacts in load-bearing or non-load-bearing areas. However, there was a significantly higher likelihood of fracture in areas with MI contacts only. Clinical Significance This clinical study demonstrates that there is a need to evaluate occlusion differently with implant-supported prostheses than with natural tooth supported prostheses because of the absence of a periodontal ligament. Implant supported prostheses should have minimal occlusion and
Analysis of genetic variation in Erianthus arundinaceum by random ...
African Journals Online (AJOL)
STORAGESEVER
2008-10-06
Oct 6, 2008 ... MATERIALS AND METHODS. Fifty-one E. arundinaceum accessions were used in the RAPD analysis. Figure 1. Plant materials planted in the sugarcane germ- plasm garden of Yunnan Agricultural University (YAU). Name and origin of the accessions are shown in Table 1. DNA was extracted from leaves ...
Analysis of Energy Overshoot of High Frequency Waves with Wavelet Transform
Institute of Scientific and Technical Information of China (English)
WEN Fan
2000-01-01
A study is made on the overshoot phenomena in wind-generated waves. The surface displace ments of time-growing waves are measured at four fetches in a wind wave channel. The evolution of high frequency waves is displayed with wavelet transform. The results are compared with Sutherland＇s. It is found that high frequency wave components experience much stronger energy overshoot in the evolution.The energy of high frequency waves decreases greatly after overshoot
International Nuclear Information System (INIS)
Dalton, G.J.; Alcorn, R.; Lewis, T.
2010-01-01
The performance and economic viability of the Pelamis wave energy converter (WEC) has been investigated over a 20 year project time period using 2007 wave energy data from various global locations: Ireland, Portugal, USA and Canada. Previous reports assessing the Pelamis quote a disparate range of financial returns for the Pelamis, necessitating a comparative standardised assessment of wave energy economic indicators. An Excel model (NAVITAS) was created for this purpose which estimated the annual energy output of Pelamis for each location using wave height (H s ) and period (T z ) data, and produced financial results dependant on various input parameters. The economic indicators used for the analysis were cost of electricity (COE), net present value (NPV) and internal rate of return (IRR), modelled at a tariff rate of EUR0.20/kWh. Analysis of the wave energy data showed that the highest annual energy output (AEO) and capacity for the Pelamis was the Irish site, as expected. Portugal returned lower AOE similar to the lesser North American sites. Monthly energy output was highest in the winter, and was particularly evident in the Irish location. Moreover, the difference between the winter wave energy input and the Pelamis energy output for Ireland was also significant as indicated by the capture width, suggesting that Pelamis design was not efficiently capturing all the wave energy states present during that period. Modelling of COE for the various case study locations showed large variation in returns, depending on the number of WEC modelled and the initial cost input and learning curve. COE was highest when modelling single WEC in comparison to multiples, as well as when using 2004 initial costs in comparison to 2008 costs (at which time price of materials peaked). Ireland returned the lowest COE of EUR0.05/kWh modelling over 100 WEC at 2004 cost of materials, and EUR0.15/kWh at 2008 prices. Although favourable COE were recorded from some of the modelled scenarios
Ren, Wei-Wei; Li, Xiao-Long; Wang, Dan; Liu, Bo-Ji; Zhao, Chong-Ke; Xu, Hui-Xiong
2018-04-13
To evaluate a special kind of ultrasound (US) shear wave elastography for differential diagnosis of breast lesions, using a new qualitative analysis (i.e. the elasticity score in the travel time map) compared with conventional quantitative analysis. From June 2014 to July 2015, 266 pathologically proven breast lesions were enrolled in this study. The maximum, mean, median, minimum, and standard deviation of shear wave speed (SWS) values (m/s) were assessed. The elasticity score, a new qualitative feature, was evaluated in the travel time map. The area under the receiver operating characteristic (AUROC) curves were plotted to evaluate the diagnostic performance of both qualitative and quantitative analyses for differentiation of breast lesions. Among all quantitative parameters, SWS-max showed the highest AUROC (0.805; 95% CI: 0.752, 0.851) compared with SWS-mean (0.786; 95% CI:0.732, 0.834; P = 0.094), SWS-median (0.775; 95% CI:0.720, 0.824; P = 0.046), SWS-min (0.675; 95% CI:0.615, 0.731; P = 0.000), and SWS-SD (0.768; 95% CI:0.712, 0.817; P = 0.074). The AUROC of qualitative analysis in this study obtained the best diagnostic performance (0.871; 95% CI: 0.825, 0.909, compared with the best parameter of SWS-max in quantitative analysis, P = 0.011). The new qualitative analysis of shear wave travel time showed the superior diagnostic performance in the differentiation of breast lesions in comparison with conventional quantitative analysis.
Energy Technology Data Exchange (ETDEWEB)
Takahashi, I.; Maenaka, H.; Takada, A. [Ship Research Inst., Tokyo (Japan)
1996-12-31
In order to examine fatigue behavior of boxing welded joints of anticorrosion aluminum A 5083 P-O alloy, the residual stress measurements, static loading tests, elastic finite element analyses, constant amplitude fatigue tests, and random fatigue tests were conducted. For a load wave in the random loading fatigue tests, a direct current component, a zero-mean narrow band random process, and a high frequency component were combined and superimposed, to examine the effect of the high frequency component and the effect of the stress cycle count method and the mean stress correction on the life estimation. For the fatigue analysis, a reference stress, such as that considering the structural stress concentration, was proved effective in reducing the amount of scattering in the fatigue test results and in improving the life estimation accuracy. Accordingly, for the actual scale measurements, it is insufficient only to measure the stress at points far from the crack initiation place. It is required to analyze the fatigue by measuring the reference stress same as the basic data acquisition tests in the laboratory. 4 refs., 21 figs., 4 tabs.
Energy Technology Data Exchange (ETDEWEB)
Takahashi, I; Maenaka, H; Takada, A [Ship Research Inst., Tokyo (Japan)
1997-12-31
In order to examine fatigue behavior of boxing welded joints of anticorrosion aluminum A 5083 P-O alloy, the residual stress measurements, static loading tests, elastic finite element analyses, constant amplitude fatigue tests, and random fatigue tests were conducted. For a load wave in the random loading fatigue tests, a direct current component, a zero-mean narrow band random process, and a high frequency component were combined and superimposed, to examine the effect of the high frequency component and the effect of the stress cycle count method and the mean stress correction on the life estimation. For the fatigue analysis, a reference stress, such as that considering the structural stress concentration, was proved effective in reducing the amount of scattering in the fatigue test results and in improving the life estimation accuracy. Accordingly, for the actual scale measurements, it is insufficient only to measure the stress at points far from the crack initiation place. It is required to analyze the fatigue by measuring the reference stress same as the basic data acquisition tests in the laboratory. 4 refs., 21 figs., 4 tabs.
International Nuclear Information System (INIS)
Abdul Rahim Samsuddin; Abdul Ghani Rafek; Umar Hamzah; Suharsono; Khairul Anuar Mohd Nayan
2008-01-01
Spectral analysis of surface waves (SASW) is a seismic method that uses the dispersive characteristics of Rayleigh waves propagating through layered material to evaluate S-wave velocity profile. The SASW is an in situ non intrusive method for geotechnical site characterization which is cost effective as compared to the conventional drilling method. In this study, a total of 20 stations from 13 sites were selected. A software (WINSASW 2.0) was used for the inversion process to produce S-wave velocity versus depth profiles. These profiles were then separately analyzed in relation to several engineering rock mass geological parameters such as stiffness, rock quality designation (RQD), anisotropy and the excavability properties. The analysis of the SASW data was based on the assumption that the rock mass is an isotropic homogeneous material with various intensity of discontinuity which influenced the velocity of surface wave propagation within the rock mass. Measurement of dynamic soil properties was carried out employing the shear wave velocities and the N values of the Standard Penetration Test (N SPT ) from borehole data. A new linear equation V s = 4.44 N SPT + 213.84 which relates S-wave and N SPT was deduced. An empirical equation is also proposed to calculate Rock Quality Designation (RQD) values based on S-wave velocity derived from SASW and that of ultrasonic tests. The result of this equation was found to be less than 10% in comparison to the RQD obtained from actual borehole data. An isotropic analysis of the rock mass was carried out using S-wave velocities derived from SASW measurements in four directions. The plots of S-wave - ultrasonic velocity ratio versus ultrasonic velocity were used to evaluate the excavability properties of rock mass. Five classes of rock mass excavability curves were finally proposed in relation to easy digging, easy ripping, hard ripping, hydraulic breaking and blasting. (author)
Zhang, L; Jiang, H; Wang, W; Bai, J; Liang, Y; Su, Y; Ge, J
2017-07-28
Interatrial septum (IAS) pacing seems to be a promising strategy for the prevention of atrial fibrillation (AF); however, studies have yielded conflicting results. This meta-analysis was to compare IAS with right atrial appendage (RAA) pacing on the prevention of postpacing AF occurrence. Pubmed, MEDLINE, EMBASE and Web of Science databases were searched through October 2016 for randomized controlled trials comparing IAS with RAA pacing on the prevention of AF. Data concerning study design, patient characteristics and outcomes were extracted. Risk ratio (RR), weighted mean differences (WMD) or standardized mean differences (SMD) were calculated using fixed or random effects models. A total of 12 trials involving 1146 patients with dual-chamber pacing were included. Although IAS was superior to RAA pacing in terms of reducing the number of AF episodes (SMD = -0.29, P = 0.05), AF burden (SMD = -0.41, P = 0.008) and P -wave duration (WMD = -34.45 ms, P IAS pacing. Nevertheless, no differences were observed concerning all-cause death (RR = 1.04, P = 0.88), procedure-related events (RR = 1.17, P = 0.69) and pacing parameters between IAS and RAA pacing in the follow-up period. IAS pacing is safe and as well tolerated as RAA pacing. Although IAS pacing may fail to prevent permanent AF occurrence and recurrences of AF, it is able to not only improve interatrial conduction, but also reduce AF burden.
A scaling analysis of electronic localization in two-dimensional random media
International Nuclear Information System (INIS)
Ye Zhen
2003-01-01
By an improved scaling analysis, we suggest that there may appear two possibilities concerning the electronic localization in two-dimensional random media. The first is that all electronic states are localized in two dimensions, as conjectured previously. The second possibility is that electronic behaviors in two- and three-dimensional random systems are similar, in agreement with a recent calculation based on a direct calculation of the conductance with the use of the Kubo formula. In this case, non-localized states are possible in two dimensions, and have some peculiar properties. A few predictions are proposed. Moreover, the present analysis accommodates results from the previous scaling analysis
A symbolic dynamics approach for the complexity analysis of chaotic pseudo-random sequences
International Nuclear Information System (INIS)
Xiao Fanghong
2004-01-01
By considering a chaotic pseudo-random sequence as a symbolic sequence, authors present a symbolic dynamics approach for the complexity analysis of chaotic pseudo-random sequences. The method is applied to the cases of Logistic map and one-way coupled map lattice to demonstrate how it works, and a comparison is made between it and the approximate entropy method. The results show that this method is applicable to distinguish the complexities of different chaotic pseudo-random sequences, and it is superior to the approximate entropy method
Random matrix theory and analysis of nucleus-nucleus collision at high energies
International Nuclear Information System (INIS)
Shahaliev, E.I.; Inst. of Radiation Problems, Baku; ); Kuznetsov, A.A.; Suleymanov, M.K.; ); Teryaev, O.V.; )
2006-01-01
A novel method for analysis of experimental data obtained at relativistic nucleus-nucleus collisions is proposed. The method, based on the ideas of Random Matrix Theory, is applied to detect systematic errors that occur at measurements of momentum distributions of emitted particles. The unfolded momentum distribution is well described by the Gaussian orthogonal ensemble of random matrices, when the uncertainty in the momentum distribution is maximal. The method is free from unwanted background contributions [ru
Bansal, N S; McDonell, F
1997-01-01
The randomly amplified polymorphic DNA (RAPD) technique was used in the development of a fingerprinting (typing) and identification protocol for Legionella strains. Twenty decamer random oligonucleotide primers were screened for their discriminatory abilities. Two candidate primers were selected. By using a combination of these primers, RAPD analysis allowed for the differentiation between all different species, between the serogroups, and further differentiation between subtypes of the same ...
Standardized Effect Size Measures for Mediation Analysis in Cluster-Randomized Trials
Stapleton, Laura M.; Pituch, Keenan A.; Dion, Eric
2015-01-01
This article presents 3 standardized effect size measures to use when sharing results of an analysis of mediation of treatment effects for cluster-randomized trials. The authors discuss 3 examples of mediation analysis (upper-level mediation, cross-level mediation, and cross-level mediation with a contextual effect) with demonstration of the…
Heat conduction analysis of multi-layered FGMs considering the finite heat wave speed
International Nuclear Information System (INIS)
Rahideh, H.; Malekzadeh, P.; Golbahar Haghighi, M.R.
2012-01-01
Highlights: ► Using a layerwise-incremental differential quadrature for heat transfer of FGMs. ► Superior accuracy with fewer degrees of freedom of the method with respect to FEM. ► Considering multi-layered functionally graded materials. ► Hyperbolic heat transfer analysis of thermal system with heat generation. ► Showing the effect of heat wave speed on thermal characteristic of the system. - Abstract: In this work, the heat conduction with finite wave heat speed of multi-layered domain made of functionally graded materials (FGMs) subjected to heat generation is simulated. For this purpose, the domain is divided into a set of mathematical layers, the number of which can be equal or greater than those of the physical layers. Then, in each mathematical layer, the non-Fourier heat transfer equations are employed. Since, the governing equations have variable coefficients due to FGM properties, as an efficient and accurate method the differential quadrature method (DQM) is adopted to discretize both spatial and temporal domains in each layer. This results in superior accuracy with fewer degrees of freedom than conventional finite element method (FEM). To verify this advantages through some comparison studies, a finite element solution are also obtained. After demonstrating the convergence and accuracy of the method, the effects of heat wave speed for two different set of boundary conditions on the temperature distribution and heat flux of the domain are studied.
Study of clay behaviour around a heat source by frequency spectrum analysis of seismic waves
International Nuclear Information System (INIS)
Sloovere, P. de.
1993-01-01
Wave propagated into soft rock is not completely described by purely linear elastic theory. Through spectrum analysis of wave, one can see that several frequencies are selected by the ground. ME2i uses this method to check grouting, piles a.s.o. The Mol experiment (on Radioactive Waste Disposal) aims to prove that little changes into heated clay can be detected by 'frequential seismic'. A cross-hole investigation system has been installed and tests have been performed for two years with a shear-hammer named MARGOT built to work inside horizontal boreholes: - Before heating the tests show the same results every time: . main frequency at 330 hertz; . maximal frequency at 520 hertz; - During heating: . the rays at 330 and 520 hertz disappear; . The frequencies in the range 100 - 300 hertz are prevailing; - After heating spectra have again their original shape. These results show that the effect is clear around an heated zone. The next steps should be: - Interpretation with computer's codes treating of wave propagation into a viscoelastic body; - Experimentations: . at the opening of a new gallery; . on big samples; . on granites and salt. 9 refs., 4 appendices
Kang, Dong Hyuk; Cho, Kang Su; Ham, Won Sik; Lee, Hyungmin; Kwon, Jong Kyou; Choi, Young Deuk; Lee, Joo Yong
2016-01-01
To perform a systematic review and network meta-analysis of randomized controlled trials (RCTs) to determine the optimal shock wave lithotripsy (SWL) frequency range for treating urinary stones, i.e., high-frequency (100-120 waves/minute), intermediate-frequency (80-90 waves/minute), and low-frequency (60-70 waves/minute) lithotripsy. Relevant RCTs were identified from electronic databases for meta-analysis of SWL success and complication rates. Using pairwise and network meta-analyses, comparisons were made by qualitative and quantitative syntheses. Outcome variables are provided as odds ratios (ORs) with 95% confidence intervals (CIs). Thirteen articles were included in the qualitative and quantitative synthesis using pairwise and network meta-analyses. On pairwise meta-analyses, comparable inter-study heterogeneity was observed for the success rate. On network meta-analyses, the success rates of low- (OR 2.2; 95% CI 1.5-2.6) and intermediate-frequency SWL (OR 2.5; 95% CI 1.3-4.6) were higher than high-frequency SWL. Forest plots from the network meta-analysis showed no significant differences in the success rate between low-frequency SWL versus intermediate-frequency SWL (OR 0.87; 95% CI 0.51-1.7). There were no differences in complication rate across different SWL frequency ranges. By rank-probability testing, intermediate-frequency SWL was ranked highest for success rate, followed by low-frequency and high-frequency SWL. Low-frequency SWL was also ranked highest for low complication rate, with high- and intermediate-frequency SWL ranked lower. Intermediate- and low-frequency SWL have better treatment outcomes than high-frequency SWL when considering both efficacy and complication.
Directory of Open Access Journals (Sweden)
F. S. Kuo
2007-02-01
Full Text Available The wave packets of atmospheric gravity waves were numerically generated, with a given characteristic wave period, horizontal wave length and projection mean wind along the horizontal wave vector. Their projection phase and group velocities along the oblique radar beam (vpr and vgr, with different zenith angle θ and azimuth angle φ, were analyzed by the method of phase- and group-velocity tracing. The results were consistent with the theoretical calculations derived by the dispersion relation, reconfirming the accuracy of the method of analysis. The RTI plot of the numerical wave packets were similar to the striation patterns of the QP echoes from the FAI irregularity region. We propose that the striation range rate of the QP echo is equal to the radial phase velocity vpr, and the slope of the energy line across the neighboring striations is equal to the radial group velocity vgr of the wave packet; the horizontal distance between two neighboring striations is equal to the characteristic wave period τ. Then, one can inversely calculate all the properties of the gravity wave responsible for the appearance of the QP echoes. We found that the possibility of some QP echoes being generated by the gravity waves originated from lower altitudes cannot be ruled out.
Tomioka, Yukiko; Kinoshita, Makoto; Umehara, Hidehiro; Watanabe, Shin-ya; Nakataki, Masahito; Iwayama, Yoshimi; Toyota, Tomoko; Ikeda, Masashi; Yamamori, Hidenaga; Shimodera, Shinji; Tajima, Atsushi; Hashimoto, Ryota; Iwata, Nakao; Yoshikawa, Takeo; Ohmori, Tetsuro
2018-01-01
Background Alterations in one-carbon metabolism have been associated with schizophrenia, and vitamin B6 is one of the key components in this pathway. Methods We first conducted a case–control study of serum pyridoxal levels and schizophrenia in a large Japanese cohort (n = 1276). Subsequently, we conducted a meta-analysis of association studies (n = 2125). Second, we investigated whether rs4654748, which was identified in a genome-wide association study as a vitamin B6-related single nucleotide polymorphism, was genetically implicated in patients with schizophrenia in the Japanese population (n = 10 689). Finally, we assessed the effect of serum pyridoxal levels on schizophrenia risk using a Mendelian randomization (MR) approach. Results Serum pyridoxal levels were significantly lower in patients with schizophrenia than in controls, not only in our cohort, but also in the pooled data set of the meta-analysis of association studies (standardized mean difference −0.48, 95% confidence interval [CI] −0.57 to −0.39, p = 9.8 × 10−24). We failed to find a significant association between rs4654748 and schizophrenia. Furthermore, an MR analysis failed to find a causal relationship between pyridoxal levels and schizophrenia risk (odds ratio 0.99, 95% CI 0.65–1.51, p = 0.96). Limitations Food consumption and medications may have affected serum pyridoxal levels in our cross-sectional study. Sample size, number of instrumental variables and substantial heterogeneity among patients with schizophrenia are limitations of an MR analysis. Conclusion We found decreased serum pyridoxal levels in patients with schizophrenia in this observational study. However, we failed to obtain data supporting a causal relationship between pyridoxal levels and schizophrenia risk using the MR approach. PMID:29688875
Soliton radiation beat analysis of optical pulses generated from two continuous-wave lasers
Zajnulina, M.; Böhm, M.; Blow, K.; Rieznik, A. A.; Giannone, D.; Haynes, R.; Roth, M. M.
2015-10-01
We propose a fibre-based approach for generation of optical frequency combs (OFCs) with the aim of calibration of astronomical spectrographs in the low and medium-resolution range. This approach includes two steps: in the first step, an appropriate state of optical pulses is generated and subsequently moulded in the second step delivering the desired OFC. More precisely, the first step is realised by injection of two continuous-wave (CW) lasers into a conventional single-mode fibre, whereas the second step generates a broad OFC by using the optical solitons generated in step one as initial condition. We investigate the conversion of a bichromatic input wave produced by two initial CW lasers into a train of optical solitons, which happens in the fibre used as step one. Especially, we are interested in the soliton content of the pulses created in this fibre. For that, we study different initial conditions (a single cosine-hump, an Akhmediev breather, and a deeply modulated bichromatic wave) by means of soliton radiation beat analysis and compare the results to draw conclusion about the soliton content of the state generated in the first step. In case of a deeply modulated bichromatic wave, we observed the formation of a collective soliton crystal for low input powers and the appearance of separated solitons for high input powers. An intermediate state showing the features of both, the soliton crystal and the separated solitons, turned out to be most suitable for the generation of OFC for the purpose of calibration of astronomical spectrographs.
Surface Wave Analysis of Regional Earthquakes in the Eastern Rift System (Africa)
Oliva, S. J. C.; Guidarelli, M.; Ebinger, C. J.; Roecker, S. W.; Tiberi, C.
2015-12-01
The Northern Tanzania Divergence (NTD), the youngest part of the East African Rift System, presents the opportunity to obtain insights about the birth and early stages of rifting before it progresses to mature rifting and seafloor spreading. This region is particularly interesting because the Eastern rift splits into three arms in this area and develops in a region of thick and cold lithosphere, amid the Archaean Tanzanian craton and the Proterozoic orogenic belt (the Masai block). We analyzed about two thousand seismic events recorded by the 39 broadband stations of the CRAFTI network during its two-year deployment in the NTD area in 2013 to 2014. We present the results of surface wave tomographic inversion obtained from fundamental-mode Rayleigh waves for short periods (between 4 to 14 seconds). Group velocity dispersion curves obtained via multiple filter analysis are path-averaged and inverted to produce 0.1º x 0.1º nodal grid tomographic maps for discrete periods using a 2D generalization of the Backus and Gilbert method. To quantify our results in terms of S-wave velocity structure the average group velocity dispersion curves are then inverted, using a linearized least-squares inversion scheme, in order to obtain the shear wave velocity structure for the upper 20 km of the crust. Low velocity anomalies are observed in the region 50 km south of Lake Natron, as well as in the area of the Ngorongoro crater. The implications of our results for the local tectonics and the development of the rifting system will be discussed in light of the growing geophysical database from this region.
Body shaping with acoustic wave therapy AWT(®)/EPAT(®): randomized, controlled study on 14 subjects.
Adatto, Maurice A; Adatto-Neilson, Robin; Novak, Pavel; Krotz, Alexander; Haller, Gerd
2011-12-01
Reduction of localised adiposities by non invasive means is a very frequent request among the female and male population. The objective of this study is to demonstrate the efficacy and safety of AWT(®), combining two different mechanical waves, planar AWT and radial AWT during the same session, in volume reduction of saddle bags in women. Treatment was performed on the saddle bag areas of 14 female patients, with the CELLACTOR(®) SC1 (Storz Medical AG, Tägerwilen, Switzerland) using extracorporeal pulse activation technology, EPAT(®). This device includes two handpieces, the C-ACTOR(®) and the D-ACTOR(®). Within 4 weeks, eight AWT(®) treatment sessions have been performed with both applicators. Follow-up visits were performed 1, 4 and 12 weeks after the last treatment. Measurements with the ultrasound system clearly demonstrate a significant diminution in the subcutaneous fat layer thickness and a reduction of the averaged circumference of thighs. This study, although performed on a small number of patients, tends to show the safety and efficacy of AWT(®) in treating localized fat areas in a non-invasive way. There is also an additional benefit for patients in reducing the cellulite appearance and improving the skin firmness at the same time by using AWT(®).
Randomizing world trade. II. A weighted network analysis
Squartini, Tiziano; Fagiolo, Giorgio; Garlaschelli, Diego
2011-10-01
Based on the misleading expectation that weighted network properties always offer a more complete description than purely topological ones, current economic models of the International Trade Network (ITN) generally aim at explaining local weighted properties, not local binary ones. Here we complement our analysis of the binary projections of the ITN by considering its weighted representations. We show that, unlike the binary case, all possible weighted representations of the ITN (directed and undirected, aggregated and disaggregated) cannot be traced back to local country-specific properties, which are therefore of limited informativeness. Our two papers show that traditional macroeconomic approaches systematically fail to capture the key properties of the ITN. In the binary case, they do not focus on the degree sequence and hence cannot characterize or replicate higher-order properties. In the weighted case, they generally focus on the strength sequence, but the knowledge of the latter is not enough in order to understand or reproduce indirect effects.
Mechanical design and analysis of a low beta squeezed half-wave resonator
He, Shou-Bo; Zhang, Cong; Yue, Wei-Ming; Wang, Ruo-Xu; Xu, Meng-Xin; Wang, Zhi-Jun; Huang, Shi-Chun; Huang, Yu-Lu; Jiang, Tian-Cai; Wang, Feng-Feng; Zhang, Sheng-Xue; He, Yuan; Zhang, Sheng-Hu; Zhao, Hong-Wei
2014-08-01
A superconducting squeezed type half-wave resonator (HWR) of β=0.09 has been developed at the Institute of Modern Physics, Lanzhou. In this paper, a basic design is presented for the stiffening structure for the detuning effect caused by helium pressure and Lorentz force. The mechanical modal analysis has been investigated the with finite element method (FEM). Based on these considerations, a new stiffening structure is proposed for the HWR cavity. The computation results concerning the frequency shift show that the low beta HWR cavity with new stiffening structure has low frequency sensitivity coefficient df/dp and Lorentz force detuning coefficient KL, and stable mechanical properties.
On continuous ambiguities in model-independent partial wave analysis - 1
International Nuclear Information System (INIS)
Nikitin, I.N.
1995-01-01
A problem of amplitude reconstruction in terms of the given angular distribution is considered. Solution of this problem is not unique. A class of amplitudes, correspondent to one and the same angular distribution, forms a region in projection onto a finite set of spherical harmonics. An explicit parametrization of a boundary of the region is obtained. A shape of the region of ambiguities is studied in particular example. A scheme of partial-wave analysis, which describes all solutions in the limits of the region, is proposed. 5 refs., 5 figs
Analysis of stress in reactor core vessel under effect of pressure lose shock wave
International Nuclear Information System (INIS)
Li Yong; Liu Baoting
2001-01-01
High Temperature gas cooled Reactor (HTR-10) is a modular High Temperature gas cooled Reactor of the new generation. In order to analyze the safety characteristics of its core vessel in case of large rupture accident, the transient performance of its core vessel under the effect of pressure lose shock wave is studied, and the transient pressure difference between the two sides of the core vessel and the transient stresses in the core vessel is presented in this paper, these results can be used in the safety analysis and safety design of the core vessel of HTR-10. (author)
International Nuclear Information System (INIS)
Wen, S.-B.; Mao Xianglei; Greif, Ralph; Russo, Richard E.
2007-01-01
By fitting simulation results with experimentally measured trajectories of the shock wave and the vapor/background gas contact surface, we found that inclusion of ionization energy in the analysis leads to a change in the evolution of the pressure, mass density, electron number density, and temperature of the vapor plume. The contribution of ionization energy to both the plasma and shock wave has been neglected in most studies of laser ablation. Compared to previous simulations, the densities, pressures, and temperatures are lower shortly after the laser pulse ( 50 ns). The predicted laser energy conversion ratio also showed about a 20% increase (from 35% to 45%) when the ionization energy is considered. The changes in the evolution of the physical quantities result from the retention of the ionization energy in the vapor plume, which is then gradually transformed to kinetic and thermal energies. When ionization energy is included in the simulation, the vapor plume attains higher expansion speeds and temperatures for a longer time after the laser pulse. The better determination of the temperature history of the vapor plume not only improves the understanding of the expansion process of the laser induced vapor plume but also is important for chemical analysis. The accurate temperature history provides supplementary information which enhances the accuracy of chemical analysis based on spectral emission measurements (e.g., laser induced breakdown spectroscopy)
Study on Nonlinear Vibration Analysis of Gear System with Random Parameters
Tong, Cao; Liu, Xiaoyuan; Fan, Li
2018-03-01
In order to study the dynamic characteristics of gear nonlinear vibration system and the influence of random parameters, firstly, a nonlinear stochastic vibration analysis model of gear 3-DOF is established based on Newton’s Law. And the random response of gear vibration is simulated by stepwise integration method. Secondly, the influence of stochastic parameters such as meshing damping, tooth side gap and excitation frequency on the dynamic response of gear nonlinear system is analyzed by using the stability analysis method such as bifurcation diagram and Lyapunov exponent method. The analysis shows that the stochastic process can not be neglected, which can cause the random bifurcation and chaos of the system response. This study will provide important reference value for vibration engineering designers.
Directory of Open Access Journals (Sweden)
JOEL Arnault
2013-03-01
Full Text Available The case study of a mountain wave triggered by the Antarctic Peninsula on 6 October 2005, which has already been documented in the literature, is chosen here to quantify the associated gravity wave forcing on the large-scale flow, with a budget analysis of the horizontal wind components and horizontal kinetic energy. In particular, a numerical simulation using the Weather Research and Forecasting (WRF model is compared to a control simulation with flat orography to separate the contribution of the mountain wave from that of other synoptic processes of non-orographic origin. The so-called differential budgets of horizontal wind components and horizontal kinetic energy (after subtracting the results from the simulation without orography are then averaged horizontally and vertically in the inner domain of the simulation to quantify the mountain wave dynamical influence at this scale. This allows for a quantitative analysis of the simulated mountain wave's dynamical influence, including the orographically induced pressure drag, the counterbalancing wave-induced vertical transport of momentum from the flow aloft, the momentum and energy exchanges with the outer flow at the lateral and upper boundaries, the effect of turbulent mixing, the dynamics associated with geostrophic re-adjustment of the inner flow, the deceleration of the inner flow, the secondary generation of an inertia–gravity wave and the so-called baroclinic conversion of energy between potential energy and kinetic energy.
Orms, Natalie; Rehn, Dirk R; Dreuw, Andreas; Krylov, Anna I
2018-02-13
Density-based wave function analysis enables unambiguous comparisons of the electronic structure computed by different methods and removes ambiguity of orbital choices. We use this tool to investigate the performance of different spin-flip methods for several prototypical diradicals and triradicals. In contrast to previous calibration studies that focused on energy gaps between high- and low spin-states, we focus on the properties of the underlying wave functions, such as the number of effectively unpaired electrons. Comparison of different density functional and wave function theory results provides insight into the performance of the different methods when applied to strongly correlated systems such as polyradicals. We show that canonical molecular orbitals for species like large copper-containing diradicals fail to correctly represent the underlying electronic structure due to highly non-Koopmans character, while density-based analysis of the same wave function delivers a clear picture of the bonding pattern.
Application of the random vibration approach in the seismic analysis of LMFBR structures
International Nuclear Information System (INIS)
Preumont, A.
1988-01-01
The first part discusses the general topic of the spectral analysis of linear multi-degree-of-freedom structure subjected to a stationary random field. Particular attention is given to structures with non-classical damping and hereditary characteristics. The method is implemented in the computer programme RANDOM. Next, the same concepts are applied to multi-supported structures subjected to a stationary seismic excitation. The method is implemented in the computer programme SEISME. Two related problems are dealt with in the next two chapters: (i) the relation between the input of the random vibration analysis and the traditional ground motion specification for seismic analysis (the Design Response Spectra) and (ii) the application of random vibration techniques to the direct generation of floor response spectra. Finally the problem of extracting information from costly time history analyses is addressed. This study has mainly been concerned with the methodology and the development of appropriate softwares. Some qualitative conclusions have been drawn regarding the expected benefit of the approach. They have been judged promising enough to motivate a benchmark exercise. Specifically, the random vibration approach will be compared to the current approximate methods (response spectrum) and time-history analyses (considered as representative of the true response) for a set of typical structures. The hope is that some of the flaws of the current approximate methods can be removed
International Nuclear Information System (INIS)
Preumont, A.; Shilab, S.; Cornaggia, L.; Reale, M.; Labbe, P.; Noe, H.
1992-01-01
This benchmark exercise is the continuation of the state-of-the-art review (EUR 11369 EN) which concluded that the random vibration approach could be an effective tool in seismic analysis of nuclear power plants, with potential advantages on time history and response spectrum techniques. As compared to the latter, the random vibration method provides an accurate treatment of multisupport excitations, non classical damping as well as the combination of high-frequency modal components. With respect to the former, the random vibration method offers direct information on statistical variability (probability distribution) and cheaper computations. The disadvantages of the random vibration method are that it is based on stationary results, and requires a power spectral density input instead of a response spectrum. A benchmark exercise to compare the three methods from the various aspects mentioned above, on one or several simple structures has been made. The following aspects have been covered with the simplest possible models: (i) statistical variability, (ii) multisupport excitation, (iii) non-classical damping. The random vibration method is therefore concluded to be a reliable method of analysis. Its use is recommended, particularly for preliminary design, owing to its computational advantage on multiple time history analysis
A random effects meta-analysis model with Box-Cox transformation.
Yamaguchi, Yusuke; Maruo, Kazushi; Partlett, Christopher; Riley, Richard D
2017-07-19
In a random effects meta-analysis model, true treatment effects for each study are routinely assumed to follow a normal distribution. However, normality is a restrictive assumption and the misspecification of the random effects distribution may result in a misleading estimate of overall mean for the treatment effect, an inappropriate quantification of heterogeneity across studies and a wrongly symmetric prediction interval. We focus on problems caused by an inappropriate normality assumption of the random effects distribution, and propose a novel random effects meta-analysis model where a Box-Cox transformation is applied to the observed treatment effect estimates. The proposed model aims to normalise an overall distribution of observed treatment effect estimates, which is sum of the within-study sampling distributions and the random effects distribution. When sampling distributions are approximately normal, non-normality in the overall distribution will be mainly due to the random effects distribution, especially when the between-study variation is large relative to the within-study variation. The Box-Cox transformation addresses this flexibly according to the observed departure from normality. We use a Bayesian approach for estimating parameters in the proposed model, and suggest summarising the meta-analysis results by an overall median, an interquartile range and a prediction interval. The model can be applied for any kind of variables once the treatment effect estimate is defined from the variable. A simulation study suggested that when the overall distribution of treatment effect estimates are skewed, the overall mean and conventional I 2 from the normal random effects model could be inappropriate summaries, and the proposed model helped reduce this issue. We illustrated the proposed model using two examples, which revealed some important differences on summary results, heterogeneity measures and prediction intervals from the normal random effects model. The
A random effects meta-analysis model with Box-Cox transformation
Directory of Open Access Journals (Sweden)
Yusuke Yamaguchi
2017-07-01
Full Text Available Abstract Background In a random effects meta-analysis model, true treatment effects for each study are routinely assumed to follow a normal distribution. However, normality is a restrictive assumption and the misspecification of the random effects distribution may result in a misleading estimate of overall mean for the treatment effect, an inappropriate quantification of heterogeneity across studies and a wrongly symmetric prediction interval. Methods We focus on problems caused by an inappropriate normality assumption of the random effects distribution, and propose a novel random effects meta-analysis model where a Box-Cox transformation is applied to the observed treatment effect estimates. The proposed model aims to normalise an overall distribution of observed treatment effect estimates, which is sum of the within-study sampling distributions and the random effects distribution. When sampling distributions are approximately normal, non-normality in the overall distribution will be mainly due to the random effects distribution, especially when the between-study variation is large relative to the within-study variation. The Box-Cox transformation addresses this flexibly according to the observed departure from normality. We use a Bayesian approach for estimating parameters in the proposed model, and suggest summarising the meta-analysis results by an overall median, an interquartile range and a prediction interval. The model can be applied for any kind of variables once the treatment effect estimate is defined from the variable. Results A simulation study suggested that when the overall distribution of treatment effect estimates are skewed, the overall mean and conventional I 2 from the normal random effects model could be inappropriate summaries, and the proposed model helped reduce this issue. We illustrated the proposed model using two examples, which revealed some important differences on summary results, heterogeneity measures and
Hobiger, Manuel; Cornou, Cécile; Bard, Pierre-Yves; Le Bihan, Nicolas; Imperatori, Walter
2016-10-01
We introduce the MUSIQUE algorithm and apply it to seismic wavefield recordings in California. The algorithm is designed to analyse seismic signals recorded by arrays of three-component seismic sensors. It is based on the MUSIC and the quaternion-MUSIC algorithms. In a first step, the MUSIC algorithm is applied in order to estimate the backazimuth and velocity of incident seismic waves and to discriminate between Love and possible Rayleigh waves. In a second step, the polarization parameters of possible Rayleigh waves are analysed using quaternion-MUSIC, distinguishing retrograde and prograde Rayleigh waves and determining their ellipticity. In this study, we apply the MUSIQUE algorithm to seismic wavefield recordings of the San Jose Dense Seismic Array. This array has been installed in 1999 in the Evergreen Basin, a sedimentary basin in the Eastern Santa Clara Valley. The analysis includes 22 regional earthquakes with epicentres between 40 and 600 km distant from the array and covering different backazimuths with respect to the array. The azimuthal distribution and the energy partition of the different surface wave types are analysed. Love waves dominate the wavefield for the vast majority of the events. For close events in the north, the wavefield is dominated by the first harmonic mode of Love waves, for farther events, the fundamental mode dominates. The energy distribution is different for earthquakes occurring northwest and southeast of the array. In both cases, the waves crossing the array are mostly arriving from the respective hemicycle. However, scattered Love waves arriving from the south can be seen for all earthquakes. Combining the information of all events, it is possible to retrieve the Love wave dispersion curves of the fundamental and the first harmonic mode. The particle motion of the fundamental mode of Rayleigh waves is retrograde and for the first harmonic mode, it is prograde. For both modes, we can also retrieve dispersion and ellipticity
DEFF Research Database (Denmark)
Marschler, Christian; Sieber, Jan; Berkemer, Rainer
2014-01-01
We introduce a general formulation for an implicit equation-free method in the setting of slow-fast systems. First, we give a rigorous convergence result for equation-free analysis showing that the implicitly defined coarse-level time stepper converges to the true dynamics on the slow manifold...... against the direction of traffic. Equation-free analysis enables us to investigate the behavior of the microscopic traffic model on a macroscopic level. The standard deviation of cars' headways is chosen as the macroscopic measure of the underlying dynamics such that traveling wave solutions correspond...... to equilibria on the macroscopic level in the equation-free setup. The collapse of the traffic jam to the free flow then corresponds to a saddle-node bifurcation of this macroscopic equilibrium. We continue this bifurcation in two parameters using equation-free analysis....
International Nuclear Information System (INIS)
Adams, T; Buskulic, D; Germain, V; Marion, F; Mours, B; Guidi, G M; Montani, M; Piergiovanni, F; Wang, G
2016-01-01
The multi-band template analysis (MBTA) pipeline is a low-latency coincident analysis pipeline for the detection of gravitational waves (GWs) from compact binary coalescences. MBTA runs with a low computational cost, and can identify candidate GW events online with a sub-minute latency. The low computational running cost of MBTA also makes it useful for data quality studies. Events detected by MBTA online can be used to alert astronomical partners for electromagnetic follow-up. We outline the current status of MBTA and give details of recent pipeline upgrades and validation tests that were performed in preparation for the first advanced detector observing period. The MBTA pipeline is ready for the outset of the advanced detector era and the exciting prospects it will bring. (paper)
International Nuclear Information System (INIS)
Koo, Dae Seo; Cheong, Yong Moo; Jung, Hyun Kyu; Park, Chi Seung; Park, Jae Suck; Choi, H. R.; Jung, S. S.
2006-07-01
In order to apply the guided ultrasonic techniques to the pipes in nuclear power plants, the cases of defective pipes of nuclear power plants, were investigated. It was confirmed that geometric factors of pipes, such as location, shape, and allowable space were impertinent for the application of guided ultrasonic techniques to pipes of nuclear power plants. The quality of pipes, supports, signals analysis of weldment/defects, acquisition of accurate defects signals also make difficult to apply the guided ultrasonic techniques to pipes of nuclear power plants. Thus, a piping mock-up representing the pipes in the nuclear power plants were designed and fabricated. The artificial flaws will be fabricated on the piping mock-up. The signals of guided ultrasonic waves from the artificial flaws will be analyzed. The guided ultrasonic techniques will be applied to the inspection of pipes of nuclear power plants according to the basis of signals analysis of artificial flaws in the piping mock-up
Lu, Zhihua; Lin, Guiting; Reed-Maldonado, Amanda; Wang, Chunxi; Lee, Yung-Chin; Lue, Tom F
2017-02-01
As a novel therapeutic method for erectile dysfunction (ED), low-intensity extracorporeal shock wave treatment (LI-ESWT) has been applied recently in the clinical setting. We feel that a summary of the current literature and a systematic review to evaluate the therapeutic efficacy of LI-ESWT for ED would be helpful for physicians who are interested in using this modality to treat patients with ED. A systematic review of the evidence regarding LI-ESWT for patients with ED was undertaken with a meta-analysis to identify the efficacy of the treatment modality. A comprehensive search of the PubMed and Embase databases to November 2015 was performed. Studies reporting on patients with ED treated with LI-ESWT were included. The International Index of Erectile Function (IIEF) and the Erection Hardness Score (EHS) were the most commonly used tools to evaluate the therapeutic efficacy of LI-ESWT. There were 14 studies including 833 patients from 2005 to 2015. Seven studies were randomized controlled trials (RCTs); however, in these studies, the setup parameters of LI-ESWT and the protocols of treatment were variable. The meta-analysis revealed that LI-ESWT could significantly improve IIEF (mean difference: 2.00; 95% confidence interval [CI], 0.99-3.00; pwaves per treatment, and duration of LI-ESWT treatment were closely related to clinical outcome, especially regarding IIEF improvement. The number of studies of LI-ESWT for ED have increased dramatically in recent years. Most of these studies presented encouraging results, regardless of variation in LI-ESWT setup parameters or treatment protocols. These studies suggest that LI-ESWT could significantly improve the IIEF and EHS of ED patients. The publication of robust evidence from additional RCTs and longer-term follow-up would provide more confidence regarding use of LI-ESWT for ED patients. We reviewed 14 studies of men who received low-intensity extracorporeal shock wave treatment (LI-ESWT) for erectile dysfunction (ED
Beli, D.; Mencik, J.-M.; Silva, P. B.; Arruda, J. R. F.
2018-05-01
The wave finite element method has proved to be an efficient and accurate numerical tool to perform the free and forced vibration analysis of linear reciprocal periodic structures, i.e. those conforming to symmetrical wave fields. In this paper, its use is extended to the analysis of rotating periodic structures, which, due to the gyroscopic effect, exhibit asymmetric wave propagation. A projection-based strategy which uses reduced symplectic wave basis is employed, which provides a well-conditioned eigenproblem for computing waves in rotating periodic structures. The proposed formulation is applied to the free and forced response analysis of homogeneous, multi-layered and phononic ring structures. In all test cases, the following features are highlighted: well-conditioned dispersion diagrams, good accuracy, and low computational time. The proposed strategy is particularly convenient in the simulation of rotating structures when parametric analysis for several rotational speeds is usually required, e.g. for calculating Campbell diagrams. This provides an efficient and flexible framework for the analysis of rotordynamic problems.
Synthetic spectral analysis of a kinetic model for slow-magnetosonic waves in solar corona
Energy Technology Data Exchange (ETDEWEB)
Ruan, Wenzhi; He, Jiansen; Tu, Chuanyi; Wang, Linghua [School of Earth and Space Sciences, Peking University, Beijing, 100871, China, E-mail: jshept@gmail.com (China); Zhang, Lei [State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100190 (China); Vocks, Christian [Leibniz-Institut für Astrophysik Potsdam, 14482, Potsdam (Germany); Marsch, Eckart [Institute for Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel, 24118 Kiel (Germany); Peter, Hardi [Max Plank Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen (Germany)
2016-03-25
We propose a kinetic model of slow-magnetosonic waves to explain various observational features associated with the propagating intensity disturbances (PIDs) occurring in the solar corona. The characteristics of slow mode waves, e.g, inphase oscillations of density, velocity, and thermal speed, are reproduced in this kinetic model. Moreover, the red-blue (R-B) asymmetry of the velocity distribution as self-consistently generated in the model is found to be contributed from the beam component, as a result of the competition between Landau resonance and Coulomb collisions. Furthermore, we synthesize the spectral lines and make the spectral analysis, based on the kinetic simulation data of the flux tube plasmas and the hypothesis of the surrounding background plasmas. It is found that the fluctuations of parameters of the synthetic spectral lines are basically consistent with the observations: (1) the line intensity, Doppler shift, and line width are fluctuating in phase; (2) the R-B asymmetry usually oscillate out of phase with the former three parameters; (3) the blueward asymmetry is more evident than the redward asymmetry in the R-B fluctuations. The oscillations of line parameters become weakened for the case with denser surrounding background plasmas. Similar to the observations, there is no doubled-frequency oscillation of the line width for the case with flux-tube plasmas flowing bulkly upward among the static background plasmas. Therefore, we suggest that the “wave + beam flow” kinetic model may be a viable interpretation for the PIDs observed in the solar corona.
Jiang, Yi; Li, Guoyang; Qian, Lin-Xue; Liang, Si; Destrade, Michel; Cao, Yanping
2015-10-01
We use supersonic shear wave imaging (SSI) technique to measure not only the linear but also the nonlinear elastic properties of brain matter. Here, we tested six porcine brains ex vivo and measured the velocities of the plane shear waves induced by acoustic radiation force at different states of pre-deformation when the ultrasonic probe is pushed into the soft tissue. We relied on an inverse method based on the theory governing the propagation of small-amplitude acoustic waves in deformed solids to interpret the experimental data. We found that, depending on the subjects, the resulting initial shear modulus [Formula: see text] varies from 1.8 to 3.2 kPa, the stiffening parameter [Formula: see text] of the hyperelastic Demiray-Fung model from 0.13 to 0.73, and the third- [Formula: see text] and fourth-order [Formula: see text] constants of weakly nonlinear elasticity from [Formula: see text]1.3 to [Formula: see text]20.6 kPa and from 3.1 to 8.7 kPa, respectively. Paired [Formula: see text] test performed on the experimental results of the left and right lobes of the brain shows no significant difference. These values are in line with those reported in the literature on brain tissue, indicating that the SSI method, combined to the inverse analysis, is an efficient and powerful tool for the mechanical characterization of brain tissue, which is of great importance for computer simulation of traumatic brain injury and virtual neurosurgery.
Random analysis of bearing capacity of square footing using the LAS procedure
Kawa, Marek; Puła, Wojciech; Suska, Michał
2016-09-01
In the present paper, a three-dimensional problem of bearing capacity of square footing on random soil medium is analyzed. The random fields of strength parameters c and φ are generated using LAS procedure (Local Average Subdivision, Fenton and Vanmarcke 1990). The procedure used is re-implemented by the authors in Mathematica environment in order to combine it with commercial program. Since the procedure is still tested the random filed has been assumed as one-dimensional: the strength properties of soil are random in vertical direction only. Individual realizations of bearing capacity boundary-problem with strength parameters of medium defined the above procedure are solved using FLAC3D Software. The analysis is performed for two qualitatively different cases, namely for the purely cohesive and cohesive-frictional soils. For the latter case the friction angle and cohesion have been assumed as independent random variables. For these two cases the random square footing bearing capacity results have been obtained for the range of fluctuation scales from 0.5 m to 10 m. Each time 1000 Monte Carlo realizations have been performed. The obtained results allow not only the mean and variance but also the probability density function to be estimated. An example of application of this function for reliability calculation has been presented in the final part of the paper.
Capan, Nalan; Esmaeilzadeh, Sina; Oral, Aydan; Basoglu, Ceyhun; Karan, Ayse; Sindel, Dilsad
2016-07-01
The aim of this study was to investigate the effects of radial extracorporeal shock wave therapy (rESWT) on pain, function, and grip strength in the treatment of patients with lateral epicondylitis unresponsive to previous treatments. A double-blind, randomized, placebo-controlled trial was conducted in outpatient clinics in a medical faculty hospital. Fifty-six patients with lateral epicondylitis were randomized to rESWT (n = 28) or sham rESWT (n = 28) groups. Both the patients and the outcome assessing investigator were blinded to group assignment. The rESWT was administered to the painful epicondyle at the elbow with a total of 2000 pulses of 10 Hz frequency at a 1.8 bar of air pressure at each session at three once weekly sessions. Sham rESWT was applied without the contact of the applicator at the same area. Study patients were assessed at baseline and at 1 and 3 mos after treatment using a visual analog scale for pain and Roles and Maudsley scale and Patient-Rated Tennis Elbow Evaluation for pain and function. Grip strength of the affected extremity was also measured using a hand dynamometer. Both rESWT and sham rESWT groups showed a significant improvement in all outcome measures at posttreatment follow-up points. Favorable absolute and percentage changes in assessments at 1- and 3-mo posttreatment did not show any significant difference between groups. The rESWT does not seem to be more effective either in reducing pain or improving function or grip strength in patients with lateral epicondylitis at least at 3 mos after treatment when compared with sham rESWT.
Directory of Open Access Journals (Sweden)
Haejoon Jung
2018-01-01
Full Text Available As an intrinsic part of the Internet of Things (IoT ecosystem, machine-to-machine (M2M communications are expected to provide ubiquitous connectivity between machines. Millimeter-wave (mmWave communication is another promising technology for the future communication systems to alleviate the pressure of scarce spectrum resources. For this reason, in this paper, we consider multi-hop M2M communications, where a machine-type communication (MTC device with the limited transmit power relays to help other devices using mmWave. To be specific, we focus on hop distance statistics and their impacts on system performances in multi-hop wireless networks (MWNs with directional antenna arrays in mmWave for M2M communications. Different from microwave systems, in mmWave communications, wireless channel suffers from blockage by obstacles that heavily attenuate line-of-sight signals, which may result in limited per-hop progress in MWNs. We consider two routing strategies aiming at different types of applications and derive the probability distributions of their hop distances. Moreover, we provide their baseline statistics assuming the blockage-free scenario to quantify the impact of blockages. Based on the hop distance analysis, we propose a method to estimate the end-to-end performances (e.g., outage probability, hop count, and transmit energy of the mmWave MWNs, which provides important insights into mmWave MWN design without time-consuming and repetitive end-to-end simulation.