On AdS/CFT correspondence beyond SUGRA: plane waves, free CFTs and double-trace deformations

Energy Technology Data Exchange (ETDEWEB)

Diaz Vazquez, D.E.

2007-09-13

This thesis deals with three corners of the AdS/CFT Correspondence that lie one step beyond the classical supergravity (SUGRA) approximation. We first explore the BMN limit of the duality and study, in particular, the behavior of field theoretic propagators in the corresponding Penrose limit. We unravel the semiclassical (WKB-) exactness of the propagators in the resulting plane wave background metric. Then, we address the limit of vanishing coupling of the conformal field theory (CFT) at large N. In the simplified scenario of Higher Spin/O(N) Vector Model duality, the conformal partial wave (CPW) expansion of scalar four-point functions are reorganized to make them suggestive of a bulk interpretation in term of a consistent truncated massless higher spin theory and their corresponding exchange Witten graphs. We also explore the connection to the interacting O(N) Vector Model at its infra-red fixed point, at leading large N. Finally, coming back to the gauge theory, we study the effect of a relevant double-trace deformations of the boundary CFT on the partition function and its dual bulk interpretation. We show how the one-loop computation in the Anti-de Sitter (AdS) space correctly reproduces the partition function and conformal anomaly of the boundary theory. In all, we get a clean test of the duality beyond the classical SUGRA approximation in the AdS bulk and at the corresponding next-to-leading 1/N order of the CFT at the conformal boundary. (orig.)

On AdS/CFT correspondence beyond SUGRA: plane waves, free CFTs and double-trace deformations

International Nuclear Information System (INIS)

Diaz Vazquez, D.E.

2007-01-01

This thesis deals with three corners of the AdS/CFT Correspondence that lie one step beyond the classical supergravity (SUGRA) approximation. We first explore the BMN limit of the duality and study, in particular, the behavior of field theoretic propagators in the corresponding Penrose limit. We unravel the semiclassical (WKB-) exactness of the propagators in the resulting plane wave background metric. Then, we address the limit of vanishing coupling of the conformal field theory (CFT) at large N. In the simplified scenario of Higher Spin/O(N) Vector Model duality, the conformal partial wave (CPW) expansion of scalar four-point functions are reorganized to make them suggestive of a bulk interpretation in term of a consistent truncated massless higher spin theory and their corresponding exchange Witten graphs. We also explore the connection to the interacting O(N) Vector Model at its infra-red fixed point, at leading large N. Finally, coming back to the gauge theory, we study the effect of a relevant double-trace deformations of the boundary CFT on the partition function and its dual bulk interpretation. We show how the one-loop computation in the Anti-de Sitter (AdS) space correctly reproduces the partition function and conformal anomaly of the boundary theory. In all, we get a clean test of the duality beyond the classical SUGRA approximation in the AdS bulk and at the corresponding next-to-leading 1/N order of the CFT at the conformal boundary. (orig.)

Several localized waves induced by linear interference between a nonlinear plane wave and bright solitons

Science.gov (United States)

Qin, Yan-Hong; Zhao, Li-Chen; Yang, Zhan-Ying; Yang, Wen-Li

2018-01-01

We investigate linear interference effects between a nonlinear plane wave and bright solitons, which are admitted by a pair-transition coupled two-component Bose-Einstein condensate. We demonstrate that the interference effects can induce several localized waves possessing distinctive wave structures, mainly including anti-dark solitons, W-shaped solitons, multi-peak solitons, Kuznetsov-Ma like breathers, and multi-peak breathers. Specifically, the explicit conditions for them are clarified by a phase diagram based on the linear interference properties. Furthermore, the interactions between these localized waves are discussed. The detailed analysis indicates that the soliton-soliton interaction induced phase shift brings the collision between these localized waves which can be inelastic for solitons involving collision and can be elastic for breathers. These characters come from the fact that the profile of solitons depends on the relative phase between bright solitons and a plane wave, and the profile of breathers does not depend on the relative phase. These results would motivate more discussions on linear interference between other nonlinear waves. Specifically, the solitons or breathers obtained here are not related to modulational instability. The underlying reasons are discussed in detail. In addition, possibilities to observe these localized waves are discussed in a two species Bose-Einstein condensate.

Wave-equation Migration Velocity Analysis Using Plane-wave Common Image Gathers

KAUST Repository

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.

3D plane-wave least-squares Kirchhoff migration

KAUST Repository

Wang, Xin

2014-08-05

A three dimensional least-squares Kirchhoff migration (LSM) is developed in the prestack plane-wave domain to increase the quality of migration images and the computational efficiency. Due to the limitation of current 3D marine acquisition geometries, a cylindrical-wave encoding is adopted for the narrow azimuth streamer data. To account for the mispositioning of reflectors due to errors in the velocity model, a regularized LSM is devised so that each plane-wave or cylindrical-wave gather gives rise to an individual migration image, and a regularization term is included to encourage the similarities between the migration images of similar encoding schemes. Both synthetic and field results show that: 1) plane-wave or cylindrical-wave encoding LSM can achieve both computational and IO saving, compared to shot-domain LSM, however, plane-wave LSM is still about 5 times more expensive than plane-wave migration; 2) the regularized LSM is more robust compared to LSM with one reflectivity model common for all the plane-wave or cylindrical-wave gathers.

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.)

Chiral dynamics, S-wave contributions and angular analysis in D → ππl anti ν

Energy Technology Data Exchange (ETDEWEB)

Shi, Yu-Ji; Wang, Wei; Zhao, Shuai [Shanghai Jiao-Tong University, INPAC, Shanghai Key Laboratory for Particle Physics and Cosmology, Department of Physics and Astronomy, Shanghai (China)

2017-07-15

We present a theoretical analysis of the D{sup -} → π{sup +}π{sup -}l anti ν and anti D{sup 0} → π{sup +}π{sup 0}l anti ν decays. We construct a general angular distribution which can include arbitrary partial waves of ππ. Retaining the S-wave and P-wave contributions we study the branching ratios, forward-backward asymmetries and a few other observables. The P-wave contribution is dominated by ρ{sup 0} resonance, and the S-wave contribution is analyzed using the unitarized chiral perturbation theory. The obtained branching fraction for D → ρlν, at the order 10{sup -3}, is consistent with the available experimental data. The S-wave contribution has a branching ratio at the order of 10{sup -4}, and this prediction can be tested by experiments like BESIII and LHCb. Future measurements can also be used to examine the π-π scattering phase shift. (orig.)

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)

Regularized plane-wave least-squares Kirchhoff migration

KAUST Repository

Wang, Xin

2013-09-22

A Kirchhoff least-squares migration (LSM) is developed in the prestack plane-wave domain to increase the quality of migration images. A regularization term is included that accounts for mispositioning of reflectors due to errors in the velocity model. Both synthetic and field results show that: 1) LSM with a reflectivity model common for all the plane-wave gathers provides the best image when the migration velocity model is accurate, but it is more sensitive to the velocity errors, 2) the regularized plane-wave LSM is more robust in the presence of velocity errors, and 3) LSM achieves both computational and IO saving by plane-wave encoding compared to shot-domain LSM for the models tested.

Plane-wave scattering from half-wave dipole arrays

DEFF Research Database (Denmark)

Jensen, Niels E.

1970-01-01

A matrix equation for determination of plane-wave scattering from arrays of thin short-circuited dipoles of lengths about half a wavelength is derived. Numerical and experimental results are presented for linear, circular, and concentric circular arrays.......A matrix equation for determination of plane-wave scattering from arrays of thin short-circuited dipoles of lengths about half a wavelength is derived. Numerical and experimental results are presented for linear, circular, and concentric circular arrays....

Numerical Study of Shock Wave Attenuation in Two-Dimensional Ducts Using Solid Obstacles: How to Utilize Shock Focusing Techniques to Attenuate Shock Waves

Directory of Open Access Journals (Sweden)

Qian Wan

2015-04-01

Full Text Available Research on shock wave mitigation in channels has been a topic of much attention in the shock wave community. One approach to attenuate an incident shock wave is to use obstacles of various geometries arranged in different patterns. This work is inspired by the study from Chaudhuri et al. (2013, in which cylinders, squares and triangles placed in staggered and non-staggered subsequent columns were used to attenuate a planar incident shock wave. Here, we present numerical simulations using a different obstacle pattern. Instead of using a matrix of obstacles, an arrangement of square or cylindrical obstacles placed along a logarithmic spiral curve is investigated, which is motivated by our previous work on shock focusing using logarithmic spirals. Results show that obstacles placed along a logarithmic spiral can delay both the transmitted and the reflected shock wave. For different incident shock Mach numbers, away from the logarithmic spiral design Mach number, this shape is effective to either delay the transmitted or the reflected shock wave. Results also confirm that the degree of attenuation depends on the obstacle shape, effective flow area and obstacle arrangement, much like other obstacle configurations.

Topologically protected edge states for out-of-plane and in-plane bulk elastic waves

Science.gov (United States)

Huo, Shao-Yong; Chen, Jiu-Jiu; Huang, Hong-Bo

2018-04-01

Topological phononic insulators (TPnIs) show promise for application in the manipulation of acoustic waves for the design of low-loss transmission and perfectly integrated communication devices. Since solid phononic crystals exist as a transverse polarization mode and a mixed longitudinal-transverse polarization mode, the realization of topological edge states for both out-of-plane and in-plane bulk elastic waves is desirable to enhance the controllability of the edge waves in solid systems. In this paper, a two-dimensional (2D) solid/solid hexagonal-latticed phononic system that simultaneously supports the topologically protected edge states for out-of-plane and in-plane bulk elastic waves is investigated. Firstly, two pairs of two-fold Dirac cones, respectively corresponding to the out-of-plane and in-plane waves, are obtained at the same frequency by tuning the crystal parameters. Then, a strategy of zone folding is invoked to form double Dirac cones. By shrinking and expanding the steel scatterer, the lattice symmetry is broken, and band inversions induced, giving rise to an intriguing topological phase transition. Finally, the topologically protected edge states for both out-of-plane and in-plane bulk elastic waves, which can be simultaneously located at the frequency range from 1.223 to 1.251 MHz, are numerically observed. Robust pseudospin-dependent elastic edge wave propagation along arbitrary paths is further demonstrated. Our results will significantly broaden its practical application in the engineering field.

Uniqueness and numerical methods in inverse obstacle scattering

International Nuclear Information System (INIS)

Kress, Rainer

2007-01-01

The inverse problem we consider in this tutorial is to determine the shape of an obstacle from the knowledge of the far field pattern for scattering of time-harmonic plane waves. In the first part we will concentrate on the issue of uniqueness, i.e., we will investigate under what conditions an obstacle and its boundary condition can be identified from a knowledge of its far field pattern for incident plane waves. We will review some classical and some recent results and draw attention to open problems. In the second part we will survey on numerical methods for solving inverse obstacle scattering problems. Roughly speaking, these methods can be classified into three groups. Iterative methods interpret the inverse obstacle scattering problem as a nonlinear ill-posed operator equation and apply iterative schemes such as regularized Newton methods, Landweber iterations or conjugate gradient methods for its solution. Decomposition methods, in principle, separate the inverse scattering problem into an ill-posed linear problem to reconstruct the scattered wave from its far field and the subsequent determination of the boundary of the scatterer from the boundary condition. Finally, the third group consists of the more recently developed sampling methods. These are based on the numerical evaluation of criteria in terms of indicator functions that decide whether a point lies inside or outside the scatterer. The tutorial will give a survey by describing one or two representatives of each group including a discussion on the various advantages and disadvantages

Plane-wave least-squares reverse-time migration

KAUST Repository

Dai, Wei; Schuster, Gerard T.

2013-01-01

. The merits of plane-wave prestack LSRTM are the following: (1) plane-wave prestack LSRTM can sometimes offer stable convergence even when the migration velocity has bulk errors of up to 5%; (2) to significantly reduce computation cost, linear phase

Interaction of gravitational plane waves

International Nuclear Information System (INIS)

Ferrari, V.

1988-01-01

The mathematical theory of colliding, infinite-fronted, plane gravitational waves is presented. The process of focusing, the creation of singularities and horizons, due to the interaction, and the lens effect due to a beam-like gravitational wave are discussed

Plane wave limits and T-duality

International Nuclear Information System (INIS)

Guven, R.

2000-04-01

The Penrose limit is generalized to show that, any leading order solution of the low-energy field equations in any one of the five string theories has a plane wave solution as a limit. This limiting procedure takes into account all the massless fields that may arise and commutes with the T-duality so that any dual solution has again a plane wave limit. The scaling rules used in the limit are unique and stem from the scaling property of the D = 11 supergravity action. Although the leading order dual solutions need not be exact or supersymmetric, their plane wave limits always preserve some portion of the Poincare supersymmetry and solve the relevant field equations in all powers of the string tension parameter. Further properties of the limiting procedure are discussed. (author)

Self-bending elastic waves and obstacle circumventing in wireless power transfer

Science.gov (United States)

Tol, S.; Xia, Y.; Ruzzene, M.; Erturk, A.

2017-04-01

We demonstrate self-bending of elastic waves along convex trajectories by means of geometric and phased arrays. Potential applications include ultrasonic imaging and manipulation, wave focusing, and wireless power transfer around obstacles. The basic concept is illustrated through a geometric array, which is designed to implement a phase delay profile among the array elements that leads to self-bending along a specified circular trajectory. Experimental validation is conducted for the lowest asymmetric Lamb wave mode in a thin plate over a range of frequencies to investigate the bandwidth of the approach. Experiments also illustrate the functionality of the array as a transmitter to deliver elastic wave energy to a receiver/harvester located behind a large obstacle for electrical power extraction. It is shown that the trajectory is not distorted by the presence of the obstacle and circumventing is achieved. A linear phased array counterpart of the geometric array is then constructed to illustrate the concept by imposing proper time delays to the array elements, which allows the generation of different trajectories using the same line source. This capability is demonstrated by tailoring the path diameter in the phased array setting, which offers the flexibility and versatility to induce a variety of convex trajectories for self-bending elastic waves.

The vortex mechanism of suppression of tsunami waves by underwater obstacles

Science.gov (United States)

Boshenyatov, B. V.

2017-12-01

A theoretical model explaining the effect of anomalous suppression of the energy (up to 70%) of tsunami-type waves by thin (compared to the wavelength) underwater obstacles is developed based on the integral laws of conservation of mass and energy fluxes. It is shown that the analytical dependences for the coefficients of reflection and transmission of waves across an underwater obstacle that have been obtained using the theoretical model proposed by the author agree with the results of the experiments and numerical simulation based on the complete Navier-Stokes equations.

Photoelectron wave function in photoionization: plane wave or Coulomb wave?

Science.gov (United States)

Gozem, Samer; Gunina, Anastasia O; Ichino, Takatoshi; Osborn, David L; Stanton, John F; Krylov, Anna I

2015-11-19

The calculation of absolute total cross sections requires accurate wave functions of the photoelectron and of the initial and final states of the system. The essential information contained in the latter two can be condensed into a Dyson orbital. We employ correlated Dyson orbitals and test approximate treatments of the photoelectron wave function, that is, plane and Coulomb waves, by comparing computed and experimental photoionization and photodetachment spectra. We find that in anions, a plane wave treatment of the photoelectron provides a good description of photodetachment spectra. For photoionization of neutral atoms or molecules with one heavy atom, the photoelectron wave function must be treated as a Coulomb wave to account for the interaction of the photoelectron with the +1 charge of the ionized core. For larger molecules, the best agreement with experiment is often achieved by using a Coulomb wave with a partial (effective) charge smaller than unity. This likely derives from the fact that the effective charge at the centroid of the Dyson orbital, which serves as the origin of the spherical wave expansion, is smaller than the total charge of a polyatomic cation. The results suggest that accurate molecular photoionization cross sections can be computed with a modified central potential model that accounts for the nonspherical charge distribution of the core by adjusting the charge in the center of the expansion.

DLCQ and plane wave matrix Big Bang models

Science.gov (United States)

Blau, Matthias; O'Loughlin, Martin

2008-09-01

We study the generalisations of the Craps-Sethi-Verlinde matrix big bang model to curved, in particular plane wave, space-times, beginning with a careful discussion of the DLCQ procedure. Singular homogeneous plane waves are ideal toy-models of realistic space-time singularities since they have been shown to arise universally as their Penrose limits, and we emphasise the role played by the symmetries of these plane waves in implementing the flat space Seiberg-Sen DLCQ prescription for these curved backgrounds. We then analyse various aspects of the resulting matrix string Yang-Mills theories, such as the relation between strong coupling space-time singularities and world-sheet tachyonic mass terms. In order to have concrete examples at hand, in an appendix we determine and analyse the IIA singular homogeneous plane wave - null dilaton backgrounds.

DLCQ and plane wave matrix Big Bang models

International Nuclear Information System (INIS)

Blau, Matthias; O'Loughlin, Martin

2008-01-01

We study the generalisations of the Craps-Sethi-Verlinde matrix big bang model to curved, in particular plane wave, space-times, beginning with a careful discussion of the DLCQ procedure. Singular homogeneous plane waves are ideal toy-models of realistic space-time singularities since they have been shown to arise universally as their Penrose limits, and we emphasise the role played by the symmetries of these plane waves in implementing the flat space Seiberg-Sen DLCQ prescription for these curved backgrounds. We then analyse various aspects of the resulting matrix string Yang-Mills theories, such as the relation between strong coupling space-time singularities and world-sheet tachyonic mass terms. In order to have concrete examples at hand, in an appendix we determine and analyse the IIA singular homogeneous plane wave - null dilaton backgrounds.

Obstacle detection method, obstacle removing method, device and production line for practicing the methods

International Nuclear Information System (INIS)

Yoneyama, Takao; Ishimatsu, Tsuneo; Komata, Hisashi; Suzuki, Keisaburo.

1997-01-01

The present invention provides techniques for detecting and removing obstacles, which can be applied to pipelines and vessels to be used in structures such as nuclear power structures and electric power generation facilities. Namely, when the pipelines or vessels are in any of the stages, namely, production, installation, before the use after installation and before the reuse after inspection, obstacles remaining in the pipelines and vessels are blown off by using a fluid jetting mechanism (air compressor). Elastic waves generated when the blown off obstacles abut against the pipelines and vessels are detected by using a sensor. As a result, the remaining obstacles can be detected during any one of the stages described above. The blowing is repeated till the absence of the obstacles is confirmed by elastic wave signals detected by the sensor. As a result, the remaining obstacles can be removed. (I.S.)

Plane-wave Least-squares Reverse Time Migration

KAUST Repository

Dai, Wei

2012-11-04

Least-squares reverse time migration is formulated with a new parameterization, where the migration image of each shot is updated separately and a prestack image is produced with common image gathers. The advantage is that it can offer stable convergence for least-squares migration even when the migration velocity is not completely accurate. To significantly reduce computation cost, linear phase shift encoding is applied to hundreds of shot gathers to produce dozens of planes waves. A regularization term which penalizes the image difference between nearby angles are used to keep the prestack image consistent through all the angles. Numerical tests on a marine dataset is performed to illustrate the advantages of least-squares reverse time migration in the plane-wave domain. Through iterations of least-squares migration, the migration artifacts are reduced and the image resolution is improved. Empirical results suggest that the LSRTM in plane wave domain is an efficient method to improve the image quality and produce common image gathers.

Plane-Wave Imaging Challenge in Medical Ultrasound

DEFF Research Database (Denmark)

Liebgott, Herve; Molares, Alfonso Rodriguez; Jensen, Jørgen Arendt

2016-01-01

for this effect, but comparing the different methods is difficult due to the lack of appropriate tools. PICMUS, the Plane-Wave Imaging Challenge in Medical Ultrasound aims to provide these tools. This paper describes the PICMUS challenge, its motivation, implementation, and metrics.......Plane-Wave imaging enables very high frame rates, up to several thousand frames per second. Unfortunately the lack of transmit focusing leads to reduced image quality, both in terms of resolution and contrast. Recently, numerous beamforming techniques have been proposed to compensate...

Observation of three dimensional optical rogue waves through obstacles

International Nuclear Information System (INIS)

Leonetti, Marco; Conti, Claudio

2015-01-01

We observe three-dimensional rogue waves in the speckle distribution of a spatially modulated optical beam. Light is transmitted beyond a partially reflecting obstacle generating optical rogue waves at a controlled position in the shadow of the barrier. When the barrier transmits only 0.07% of the input laser power, we observe the mostly localized event. These results demonstrate that an optimum amount of spatial non-homogeneity maximizes the probability of a gigantic event while the technique we exploit enables to control light behind a fully reflective wall

The Interaction between the Plane Wave and the Plate with Limited Height in Soil

Directory of Open Access Journals (Sweden)

N.A. Lokteva

2017-03-01

Full Text Available A solution of the two-dimensional task on interaction between the harmonic wave and the plate with the limited height in soil has been provided. The plate surrounded on both sides with the half-spaces filled with soil medium has been used as a vibro-absorbing obstacle. The mechanical behavior of the plate has been described by S.P. Timoshenko's shift model and the mechanical behavior of soil by a linear elasticity theory equation. The main purpose of the paper is to determine the total acceleration vector field inducted by the penetrated and radiated waves in the second half-space. The mathematical formulation of the task includes a model of upcoming wave, soil medium and plate movement equation, infinity conditions, and conditions of soil contact with obstacle. Conditions of free slip have been taken as the contact conditions between the soil and the obstacle. We have considered a closed system of equations, which includes wave equations for scalar and vector potentials, elasticity theory equations for soil mediums, Koshi's relations, physical law, and plate movement equation. The boundary conditions for the plate correspond to a hinged support. To solve this task, all functions have been expanded in trigonometric series that allowed to obtain potential values in the coefficients of the series. To define the integrations constants, the contact conditions between the obstacle and soil have been used. On the basis of the revealed potentials, we have defined displacements on the boundary between the plate and soil and in other points of the second half-space. The vibro-absorbing properties of the plate have been investigated depending on the frequency of the harmonic wave falling on the plate. From the practical point of view, this task is related to protection of buildings from vibrations formed at a distance from underground railways.

Plane waves with weak singularities

International Nuclear Information System (INIS)

David, Justin R.

2003-03-01

We study a class of time dependent solutions of the vacuum Einstein equations which are plane waves with weak null singularities. This singularity is weak in the sense that though the tidal forces diverge at the singularity, the rate of divergence is such that the distortion suffered by a freely falling observer remains finite. Among such weak singular plane waves there is a sub-class which does not exhibit large back reaction in the presence of test scalar probes. String propagation in these backgrounds is smooth and there is a natural way to continue the metric beyond the singularity. This continued metric admits string propagation without the string becoming infinitely excited. We construct a one parameter family of smooth metrics which are at a finite distance in the space of metrics from the extended metric and a well defined operator in the string sigma model which resolves the singularity. (author)

A plane-wave final-state theory of ATI

International Nuclear Information System (INIS)

Parker, J.S.; Clark, C.W.

1993-01-01

A Fermi Golden Rule calculation of ionization cross-sections provides us with the simplest example of a plane-wave final-state theory. In this method the final (unbound) state is modeled as a plane wave, an approximation that generally gives best results in the high energy limit in which the affect of the atomic potential on the final state can be neglected. A cross-section is then calculated from the matrix element connecting the bound initial state with the final state. The idea of generalizing this method to model transitions among unbound states is credited to L.V. Keldysh, and a number of related formalisms have been proposed that are consistent with the general features of experimental data. Here we describe a plane-wave final-state model of ATI that is in the spirit of these theories, but differs significantly in its implementation and predictions. We will present a comparison of the predictions of the plane-wave model with those of a full numerical integration of the time-dependent Schrodinger equation for atomic hydrogen in a radiation field. The theory and the numerical integration give good qualitative agreement in their predictions of photoelectron spectra over about 14 orders of magnitude

Women’s orgasm obstacles: A qualitative study

Science.gov (United States)

Nekoolaltak, Maryam; Keshavarz, Zohreh; Simbar, Masoumeh; Nazari, Ali Mohammad; Baghestani, Ahmad Reza

2017-01-01

Background: Woman’s orgasm plays a vital role in sexual compatibility and marital satisfaction. Orgasm in women is a learnable phenomenon that is influenced by several factors. Objective: The aim of this study is exploring obstacles to orgasm in Iranian married women. Materials and Methods: This qualitative study with directed content analysis approach was conducted in 2015-2016, on 20 Iranian married women who were individually interviewed at two medical clinics in Tehran, Iran. Results: Orgasm obstacles were explored in one category, 4 subcategories, and 25 codes. The main category was “Multidimensionality of women’s orgasm obstacles”. Subcategories and some codes included: Physical obstacles (wife’s or husband’s boredom, vaginal infection, insufficient vaginal lubrication), psychological obstacles (lack of sexual knowledge, shame, lack of concentration on sex due to household and children problems), relational obstacles (husband’s hurry, having a dispute and annoyance with spouse) and contextual obstacles (Irregular sleep hours, lack of privacy and inability to separate children’s bedroom from their parents, lack of peace at home). Conclusion: For prevention or treatment of female orgasm disorders, attention to physical factors is not enough. Obtaining a comprehensive history about physical, psychological, relational and contextual dimensions of woman’s life is necessary. PMID:29082366

Women’s orgasm obstacles: A qualitative study

Directory of Open Access Journals (Sweden)

Maryam Nekoolaltak

2017-09-01

Full Text Available Background: Woman’s orgasm plays a vital role in sexual compatibility and marital satisfaction. Orgasm in women is a learnable phenomenon that is influenced by several factors. Objective: The aim of this study is exploring obstacles to orgasm in Iranian married women. Materials and Methods: This qualitative study with directed content analysis approach was conducted in 2015-2016, on 20 Iranian married women who were individually interviewed at two medical clinics in Tehran, Iran. Results: Orgasm obstacles were explored in one category, 4 subcategories, and 25 codes. The main category was “Multidimensionality of women’s orgasm obstacles”. Subcategories and some codes included: Physical obstacles (wife’s or husband’s boredom, vaginal infection, insufficient vaginal lubrication, psychological obstacles (lack of sexual knowledge, shame, lack of concentration on sex due to household and children problems, relational obstacles (husband’s hurry, having a dispute and annoyance with spouse and contextual obstacles (Irregular sleep hours, lack of privacy and inability to separate children’s bedroom from their parents, lack of peace at home. Conclusion: For prevention or treatment of female orgasm disorders, attention to physical factors is not enough. Obtaining a comprehensive history about physical, psychological, relational and contextual dimensions of woman’s life is necessary.

New family of exact solutions for colliding plane gravitational waves

International Nuclear Information System (INIS)

Yurtsever, U.

1988-01-01

We construct an infinite-parameter family of exact solutions to the vacuum Einstein field equations describing colliding gravitational plane waves with parallel polarizations. The interaction regions of the solutions in this family are locally isometric to the interiors of those static axisymmetric (Weyl) black-hole solutions which admit both a nonsingular horizon, and an analytic extension of the exterior metric to the interior of the horizon. As a member of this family of solutions we also obtain, for the first time, a colliding plane-wave solution where both of the two incoming plane waves are purely anastigmatic, i.e., where both incoming waves have equal focal lengths

Plane waves and structures in turbulent channel flow

Science.gov (United States)

Sirovich, L.; Ball, K. S.; Keefe, L. R.

1990-01-01

A direct simulation of turbulent flow in a channel is analyzed by the method of empirical eigenfunctions (Karhunen-Loeve procedure, proper orthogonal decomposition). This analysis reveals the presence of propagating plane waves in the turbulent flow. The velocity of propagation is determined by the flow velocity at the location of maximal Reynolds stress. The analysis further suggests that the interaction of these waves appears to be essential to the local production of turbulence via bursting or sweeping events in the turbulent boundary layer, with the additional suggestion that the fast acting plane waves act as triggers.

Problems of the orthogonalized plane wave method. 1

International Nuclear Information System (INIS)

Farberovich, O.V.; Kurganskii, S.I.; Domashevskaya, E.P.

1979-01-01

The main problems of the orthogonalized plane wave method are discussed including (a) consideration of core states; (b) effect of overlap of wave functions of external core states upon the band structure; (c) calculation of d-type states. The modified orthogonal plane wave method (MOPW method) of Deegan and Twose is applied in a general form to solve the problems of the usual OPW method. For the first time the influence on the spectrum of the main parameters of the MOPW method is studied systematically by calculating the electronic energy spectrum in the transition metals Nb and V. (author)

Transition operators in electromagnetic-wave diffraction theory - General theory

Science.gov (United States)

Hahne, G. E.

1992-01-01

A formal theory is developed for the scattering of time-harmonic electromagnetic waves from impenetrable immobile obstacles with given linear, homogeneous, and generally nonlocal boundary conditions of Leontovich (impedance) type for the wave of the obstacle's surface. The theory is modeled on the complete Green's function and the transition (T) operator in time-independent formal scattering theory of nonrelativistic quantum mechanics. An expression for the differential scattering cross section for plane electromagnetic waves is derived in terms of certain matrix elements of the T operator for the obstacle.

Transient waves generated by a moving bottom obstacle: a new near-field solution

DEFF Research Database (Denmark)

Madsen, Per A.; Hansen, Asger Bendix

2012-01-01

in the vicinity of the obstacle as well as the development of the transient free waves generated at the onset of the motion. At some distance from the obstacle, dispersion starts to play a role and undular bores develop, but up to this point the new formulation agrees very well with numerical simulations based...... the height and speed of the leading waves in the undular bores. The numerical and analytical solutions to the new single-family formulation of the NSW equations are compared to results based on the forced Korteweg–de Vries/Hopf equation and to numerical Boussinesq simulations....

Tunnelling of plane waves through a square barrier

Energy Technology Data Exchange (ETDEWEB)

Julve, J [IMAFF, Consejo Superior de Investigaciones CientIficas, Serrano 113 bis, Madrid 28006 (Spain); UrrIes, F J de [Departamento de Fisica, Universidad de Alcala de Henares, Alcala de Henares, Madrid (Spain)], E-mail: julve@imaff.cfmac.csic.es, E-mail: fernando.urries@uah.es

2008-08-01

The time evolution of plane waves in the presence of a one-dimensional square quantum barrier is considered. Comparison is made between the cases of an infinite and a cut-off (shutter) initial plane wave. The difference is relevant when the results are applied to the analysis of the tunnelling regime. This work is focused on the analytical calculation of the time-evolved solution and highlights the contribution of the resonant (Gamow) states.

Plane-wave electronic structure calculations on a parallel supercomputer

International Nuclear Information System (INIS)

Nelson, J.S.; Plimpton, S.J.; Sears, M.P.

1993-01-01

The development of iterative solutions of Schrodinger's equation in a plane-wave (pw) basis over the last several years has coincided with great advances in the computational power available for performing the calculations. These dual developments have enabled many new and interesting condensed matter phenomena to be studied from a first-principles approach. The authors present a detailed description of the implementation on a parallel supercomputer (hypercube) of the first-order equation-of-motion solution to Schrodinger's equation, using plane-wave basis functions and ab initio separable pseudopotentials. By distributing the plane-waves across the processors of the hypercube many of the computations can be performed in parallel, resulting in decreases in the overall computation time relative to conventional vector supercomputers. This partitioning also provides ample memory for large Fast Fourier Transform (FFT) meshes and the storage of plane-wave coefficients for many hundreds of energy bands. The usefulness of the parallel techniques is demonstrated by benchmark timings for both the FFT's and iterations of the self-consistent solution of Schrodinger's equation for different sized Si unit cells of up to 512 atoms

Path integral for Dirac particle in plane wave field

Energy Technology Data Exchange (ETDEWEB)

Zeggari, S.; Boudjedaa, T.; Chetouani, L. [Mentouri Univ., Constantine (Algeria). Dept. of Physique

2001-10-01

The problem of a relativistic spinning particle in interaction with an electromagnetic plane wave field is treated via path integrals. The dynamics of the spin of the particle is described using the supersymmetric action proposed by Fradkin and Gitman. The problem has been solved by using two identities, one bosonic and the other fermionic, which are related directly to the classical equations of motion. The exact expression of the relative Green's function is given and the result agrees with those of the literature. Further, the suitably normalized wave functions are also extracted. (orig.)

A differentiated plane wave: its passage through a slab

International Nuclear Information System (INIS)

Hannay, J H; Nye, J F

2013-01-01

Differentiating a monochromatic uniform plane electromagnetic wavefield with respect to its direction produces, from a field that is completely lacking in localized specific features, one that contains a straight vortex-like line, a ‘C-line’ of defined circular polarization. There is also a second separate C-line of opposite handedness; indeed, in a sense, a straight line of every polarization is realized. Because of its primitive construction it is analytically simple to study the passage of a differentiated wave obliquely through a plane interface into a medium of different refractive index, to trace its C-line. This was done in an earlier paper. Here we extend the method to passage through a parallel-sided transparent slab. There are multiple reflections within the slab, as in a Fabry–Pérot interferometer. The exiting wave, as a single differentiated plane wave, has a straight oblique C-line. Inside the slab, and in front of it, there is wave interference. The result is a coiled, helix-like, C-line in front of the slab and another inside it. The two coils wrap around separate hyperboloids of one sheet, like cooling towers. The emerging straight C-line is shifted (with respect to a C-line in a notional undisturbed incident plane wave) both in the plane of incidence and transversely to it, and the second C-line behaves similarly. The analysis is exact and could be extended in a straightforward way to a general stratified medium. (paper)

Dynamic Interaction of Interfacial Point Source Loading and Cylinder in an Elastic Quarter with Anti-plane Shear

Science.gov (United States)

Chun, Gao; Hui, Qi; Nan, Pan Xiang; Bo, Zhao Yuan

2017-07-01

Theoretical steady state solution of a semi-circular cylinder impacted by an anti-plane point loading in a vertical bound of an elastic quarter is formulated in this paper through using image method and wave function expansion series. The elastic quarter is extended as a half space, and the semi-circular interfacial cylinder is extended as a circular cylinder. Displacement field is constructed as series of Fourier-Hankel and Fourier-Bessel wave functions. At last, circular boundary is expanded as Fourier series to determine coefficients of wave function. Numerical results show that material parameters have two widely divergent effects on the radial and circumferential dynamic stress distribution.

Ground penetrating radar antenna measurements based on plane-wave expansions

DEFF Research Database (Denmark)

Lenler-Eriksen, Hans-Rudolph; Meincke, Peter

2005-01-01

The plane-wave transmitting spectrum of the system consisting of the ground penetrating radar (GPR) antenna and the air-soil interface is measured using a loop buried in the soil. The plane-wave spectrum is used to determine various parameters characterizing the radiation of the GPR antenna...

Plane-Wave Characterization of Antennas Close to a Planar Interface

DEFF Research Database (Denmark)

Meincke, Peter; Hansen, Thorkild

2004-01-01

The plane-wave scattering matrix is used to characterize antennas that are located just above a planar interface that separates two media. The plane-wave transmitting spectrum for the field radiated downwards into the lower medium is expressed directly in terms of the current distribution of the ...

Turbidity current flow over an erodible obstacle and phases of sediment wave generation

Science.gov (United States)

Strauss, Moshe; Glinsky, Michael E.

2012-06-01

We study the flow of particle-laden turbidity currents down a slope and over an obstacle. A high-resolution 2-D computer simulation model is used, based on the Navier-Stokes equations. It includes poly-disperse particle grain sizes in the current and substrate. Particular attention is paid to the erosion and deposition of the substrate particles, including application of an active layer model. Multiple flows are modeled from a lock release that can show the development of sediment waves (SW). These are stream-wise waves that are triggered by the increasing slope on the downstream side of the obstacle. The initial obstacle is completely erased by the resuspension after a few flows leading to self consistent and self generated SW that are weakly dependant on the initial obstacle. The growth of these waves is directly related to the turbidity current being self sustaining, that is, the net erosion is more than the net deposition. Four system parameters are found to influence the SW growth: (1) slope, (2) current lock height, (3) grain lock concentration, and (4) particle diameters. Three phases are discovered for the system: (1) "no SW," (2) "SW buildup," and (3) "SW growth". The second phase consists of a soliton-like SW structure with a preserved shape. The phase diagram of the system is defined by isolating regions divided by critical slope angles as functions of current lock height, grain lock concentration, and particle diameters.

Scattering on plane waves and the double copy

Science.gov (United States)

Adamo, Tim; Casali, Eduardo; Mason, Lionel; Nekovar, Stefan

2018-01-01

Perturbatively around flat space, the scattering amplitudes of gravity are related to those of Yang–Mills by colour-kinematic duality, under which gravitational amplitudes are obtained as the ‘double copy’ of the corresponding gauge theory amplitudes. We consider the question of how to extend this relationship to curved scattering backgrounds, focusing on certain ‘sandwich’ plane waves. We calculate the 3-point amplitudes on these backgrounds and find that a notion of double copy remains in the presence of background curvature: graviton amplitudes on a gravitational plane wave are the double copy of gluon amplitudes on a gauge field plane wave. This is non-trivial in that it requires a non-local replacement rule for the background fields and the momenta and polarization vectors of the fields scattering on the backgrounds. It must also account for new ‘tail’ terms arising from scattering off the background. These encode a memory effect in the scattering amplitudes, which naturally double copies as well.

Parallel Multi-Focusing Using Plane Wave Decomposition

DEFF Research Database (Denmark)

Misaridis, Thanassis; Munk, Peter; Jensen, Jørgen Arendt

2003-01-01

of desired 2-D sensitivity functions is specified, for multi-focusing in a number of directions. The field along these directions is decomposed to a sufficiently large (for accurate specification) number of plane waves, which are then back-propagated to all transducer elements. The contributions of all plane...... waves result in one time function per element. The numerical solution is presented and discussed. It contains pulses with a variation in central frequency and time-varying apodization across the aperture (dynamic apodization). The RMS difference between the transmitted field using the calculated pulse...... of the transmitted pulses is based on the directivity spectrum method, a generalization of the angular spectrum method, a generalization of the angular spectrum method, containing no evanescent waves. The underlying theory is based on the Fourier slice theorem, and field reconstruction from projections. First a set...

Excitation of plane Lamb wave in plate-like structures under applied surface loading

Science.gov (United States)

Zhou, Kai; Xu, Xinsheng; Zhao, Zhen; Yang, Zhengyan; Zhou, Zhenhuan; Wu, Zhanjun

2018-02-01

Lamb waves play an important role in structure health monitoring (SHM) systems. The excitation of Lamb waves has been discussed for a long time with absorbing results. However, little effort has been made towards the precise characterization of Lamb wave excitation by various transducer models with mathematical foundation. In this paper, the excitation of plane Lamb waves with plane strain assumption in isotropic plate structures under applied surface loading is solved with the Hamiltonian system. The response of the Lamb modes excited by applied loading is expressed analytically. The effect of applied loading is divided into the product of two parts as the effect of direction and the effect of distribution, which can be changed by selecting different types of transducer and the corresponding transducer configurations. The direction of loading determines the corresponding displacement of each mode. The effect of applied loading on the in-plane and normal directions depends on the in-plane and normal displacements at the surface respectively. The effect of the surface loading distribution on the Lamb mode amplitudes is mainly reflected by amplitude versus frequency or wavenumber. The frequencies at which the maxima and minima of the S0 or A0 mode response occur depend on the distribution of surface loading. The numerical results of simulations conducted on an infinite aluminum plate verify the theoretical prediction of not only the direction but also the distribution of applied loading. A pure S0 or A0 mode can be excited by selecting the appropriate direction and distribution at the corresponding frequency.

Quantum scattering beyond the plane-wave approximation

Science.gov (United States)

Karlovets, Dmitry

2017-12-01

While a plane-wave approximation in high-energy physics works well in a majority of practical cases, it becomes inapplicable for scattering of the vortex particles carrying orbital angular momentum, of Airy beams, of the so-called Schrödinger cat states, and their generalizations. Such quantum states of photons, electrons and neutrons have been generated experimentally in recent years, opening up new perspectives in quantum optics, electron microscopy, particle physics, and so forth. Here we discuss the non-plane-wave effects in scattering brought about by the novel quantum numbers of these wave packets. For the well-focused electrons of intermediate energies, already available at electron microscopes, the corresponding contribution can surpass that of the radiative corrections. Moreover, collisions of the cat-like superpositions of such focused beams with atoms allow one to probe effects of the quantum interference, which have never played any role in particle scattering.

Progress in parallel implementation of the multilevel plane wave time domain algorithm

KAUST Repository

Liu, Yang; Bagci, Hakan; Michielssen, Eric

2013-01-01

The computational complexity and memory requirements of classical schemes for evaluating transient electromagnetic fields produced by Ns dipoles active for Nt time steps scale as O(NtN s 2) and O(Ns 2), respectively. The multilevel plane wave time

Blackfolds, plane waves and minimal surfaces

Science.gov (United States)

Armas, Jay; Blau, Matthias

2015-07-01

Minimal surfaces in Euclidean space provide examples of possible non-compact horizon geometries and topologies in asymptotically flat space-time. On the other hand, the existence of limiting surfaces in the space-time provides a simple mechanism for making these configurations compact. Limiting surfaces appear naturally in a given space-time by making minimal surfaces rotate but they are also inherent to plane wave or de Sitter space-times in which case minimal surfaces can be static and compact. We use the blackfold approach in order to scan for possible black hole horizon geometries and topologies in asymptotically flat, plane wave and de Sitter space-times. In the process we uncover several new configurations, such as black helicoids and catenoids, some of which have an asymptotically flat counterpart. In particular, we find that the ultraspinning regime of singly-spinning Myers-Perry black holes, described in terms of the simplest minimal surface (the plane), can be obtained as a limit of a black helicoid, suggesting that these two families of black holes are connected. We also show that minimal surfaces embedded in spheres rather than Euclidean space can be used to construct static compact horizons in asymptotically de Sitter space-times.

Blackfolds, plane waves and minimal surfaces

Energy Technology Data Exchange (ETDEWEB)

Armas, Jay [Physique Théorique et Mathématique, Université Libre de Bruxelles and International Solvay Institutes, ULB-Campus Plaine CP231, B-1050 Brussels (Belgium); Albert Einstein Center for Fundamental Physics, University of Bern,Sidlerstrasse 5, 3012 Bern (Switzerland); Blau, Matthias [Albert Einstein Center for Fundamental Physics, University of Bern,Sidlerstrasse 5, 3012 Bern (Switzerland)

2015-07-29

Minimal surfaces in Euclidean space provide examples of possible non-compact horizon geometries and topologies in asymptotically flat space-time. On the other hand, the existence of limiting surfaces in the space-time provides a simple mechanism for making these configurations compact. Limiting surfaces appear naturally in a given space-time by making minimal surfaces rotate but they are also inherent to plane wave or de Sitter space-times in which case minimal surfaces can be static and compact. We use the blackfold approach in order to scan for possible black hole horizon geometries and topologies in asymptotically flat, plane wave and de Sitter space-times. In the process we uncover several new configurations, such as black helicoids and catenoids, some of which have an asymptotically flat counterpart. In particular, we find that the ultraspinning regime of singly-spinning Myers-Perry black holes, described in terms of the simplest minimal surface (the plane), can be obtained as a limit of a black helicoid, suggesting that these two families of black holes are connected. We also show that minimal surfaces embedded in spheres rather than Euclidean space can be used to construct static compact horizons in asymptotically de Sitter space-times.

String interactions in a plane-fronted parallel-wave spacetime

International Nuclear Information System (INIS)

Gopakumar, Rajesh

2002-01-01

We argue that string interactions in a plane-fronted parallel-wave spacetime are governed by an effective coupling g eff =g s (μp + α ' )f(μp + α ' ) where f(μp + α ' ) is proportional to the light-cone energy of the string states involved in the interaction. This simply follows from generalities of a matrix string description of this background. g eff nicely interpolates between the expected result (g s ) for flat space (small μp + α ' ) and a recently conjectured expression from the perturbative gauge theory side (large μp + α ' )

Diffraction of love waves by two parallel perfectly weak half planes

International Nuclear Information System (INIS)

Asghar, S.; Zaman, F.D.; Ayub, M.

1986-04-01

We consider the diffraction of Love waves by two parallel perfectly weak half planes in a layer overlying a half space. The problem is formulated in terms of the Wiener-Hopf equations in the transformed plane. The transmitted waves are then calculated using the Wiener-Hopf procedure and inverse transforms. (author)

Coupled fracture modes under anti-plane loading

Directory of Open Access Journals (Sweden)

Les P. Pook

2016-07-01

Full Text Available The linear elastic analysis of homogeneous, isotropic cracked bodies is a Twentieth Century development. It was recognised that the crack tip stress field is a singularity, but it was not until the introduction of the essentially two dimensional stress intensity factor concept in 1957 that widespread application to practical engineering problems became possible. The existence of three dimensional corner point effects in the vicinity of a corner point where a crack front intersects a free surface was investigated in the late 1970s: it was found that modes II and III cannot exist in isolation. The existence of one of these modes always induces the other. An approximate solution for corner point singularities by Bažant and Estenssoro explained some features of corner point effects but there were various paradoxes and inconsistencies. In an attempt to explain these a study was carried out on the coupled in-plane fracture mode induced by a nominal anti-plane (mode III loading applied to plates and discs weakened by a straight crack. The results derived from a large bulk of finite element models showed clearly that Bažant and Estenssoro’s analysis is incomplete. Some of the results of the study are summarised, together with some recent results for a disc under in-plane shear loading. On the basis of these results, and a mathematical argument, the results suggest that the stress field in the vicinity of a corner point is the sum of two singularities: one due to stress intensity factors and the other due to an as yet undetermined corner point singularity.

Plane-wave Least-squares Reverse Time Migration

KAUST Repository

Dai, Wei; Schuster, Gerard T.

2012-01-01

convergence for least-squares migration even when the migration velocity is not completely accurate. To significantly reduce computation cost, linear phase shift encoding is applied to hundreds of shot gathers to produce dozens of planes waves. A

Regularized plane-wave least-squares Kirchhoff migration

KAUST Repository

Wang, Xin; Dai, Wei; Schuster, Gerard T.

2013-01-01

A Kirchhoff least-squares migration (LSM) is developed in the prestack plane-wave domain to increase the quality of migration images. A regularization term is included that accounts for mispositioning of reflectors due to errors in the velocity

Propagation of plane waves in a rotating magneto-thermoelastic fiber-reinforced medium under G-N theory

Directory of Open Access Journals (Sweden)

Maity N.

2017-06-01

Full Text Available The article is concernedwith the possibility of plane wave propagation in a rotating elastic medium under the action of magnetic and thermal fields. The material is assumed to be fibre-reinforced with increased stiffness, strength and load bearing capacity. Green and Nagdhi’s concepts of generalized thermoelastic models II and III have been followed in the governing equations expressed in tensor notation. The effects of various parameters of the applied fields on the plane wave velocity have been shown graphically.

Dirac particle in a plane wave field and the semi-classical approximation

Energy Technology Data Exchange (ETDEWEB)

Bourouaine, S. [Department of Physics, Faculty of Sciences, Mentouri University, Constantine (Algeria)

2005-04-01

In this paper we investigate the influence of photon represented by plane wave field on Dirac particle in the context of path integral approach given by Fradkin and Gitman formalism. In our case, although the action relative to Dirac particle in plane wave field seems to be non quadratic, the result obtained by semi-classical approach is the same as that found by an exact calculation. Hence; when we add the plane wave field to any quadratic actions related to Fradkin and Gitman approach, the total action behaves like quadratic. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

Dirac particle in a plane wave field and the semi-classical approximation

International Nuclear Information System (INIS)

Bourouaine, S.

2005-01-01

In this paper we investigate the influence of photon represented by plane wave field on Dirac particle in the context of path integral approach given by Fradkin and Gitman formalism. In our case, although the action relative to Dirac particle in plane wave field seems to be non quadratic, the result obtained by semi-classical approach is the same as that found by an exact calculation. Hence; when we add the plane wave field to any quadratic actions related to Fradkin and Gitman approach, the total action behaves like quadratic. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

A new GTD slope diffraction coefficient for plane wave illumination of a wedge

DEFF Research Database (Denmark)

Lumholt, Michael; Breinbjerg, Olav

1997-01-01

Two wedge problems including slope diffraction are solved: one in which the incident field is a non-uniform plane wave, and one in which it is an inhomogeneous plane wave. The two solutions lead to the same GTD slope diffraction coefficient. This coefficient reveals the existence of a coupling...... effect between a transverse magnetic (or transverse electric) incident plane wave and the transverse electric (or transverse magnetic) slope-diffracted field. The coupling effect is not described by the existing GTD slope diffraction coefficient...

Beam Dynamics a Integrated Plane Wave Transformer Photoinjector at S- and X- band

Science.gov (United States)

Rosenzweig, J. B.; Ding, X.; Pellegrini, X.; Serafini, L.; Yu, D.

1997-05-01

The beam dynamics of an integrated S-band rf photoinjector based on the plane wave transformer concept, proposed as part of an SBIR collaboration between UCLA and DULY Research, are studied. The intial design, which calls for an 11.5 cell structure run at a peak on-axis accelerating field of 60 MV/m, and has a compact solenoid around the intial 2.5 cells, is based on the recently developed theory of emittance compensation(L.Serafini, and J.B. Rosenzweig, submitted to Physical Review E.). It calls for matching the beam onto an envelope which is a generalized Brillouin flow, producing a beam which diminishes in transverse size as the square root of the accelerating beam energy. This condition produces a minimized emittance, which for the S-band case is 1 mm-rad at at charge of 1 nC. This design is also scaled to produce nearly identical performance at X-band, giving an injector appropriate to running an FEL at the SLAC NLCTA. It is noted that these designs are insensitive to rf emittance increase, allowign a choice of injection phase, and the option to compress the emitted pulse.

Diffraction of love waves by two staggered perfectly weak half-planes

International Nuclear Information System (INIS)

Asghar, S.; Zaman, F.D.; Sajida Asghar

1989-01-01

Love wave travelling in a layer of uniform thickness overlying a half-space is assumed to be incident on two parallel but staggered perfectly weak half-planes lying in the upper layer. The diffracted fields is calculated using the modified Wiener-Hopf technique and contour integration method. The diffracted waves satisfy the dispersion relations appropriate to different regions formed by the perfectly weak half-planes

Synchrotron-radiation plane-wave topography

International Nuclear Information System (INIS)

Riglet, P.; Sauvage, M.; Petroff, J.F.; Epelboin, Y.

1980-01-01

A computer program based on the Takagi-Taupin differential equations for X-ray propagation in distorted crystals has been developed in order to simulate dislocation images in the Bragg case. The program is valid both for thin and thick crystals. Simulated images of misfit dislocations formed either in a thin epilayer or in a thick substrate are compared with experimental images obtained by synchrotron-radiation plane-wave topography. The influence of the various strain components on the image features is discussed. (author)

Superresolution Imaging Using Resonant Multiples and Plane-wave Migration Velocity Analysis

KAUST Repository

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

3D plane-wave least-squares Kirchhoff migration

KAUST Repository

Wang, Xin; Dai, Wei; Huang, Yunsong; Schuster, Gerard T.

2014-01-01

A three dimensional least-squares Kirchhoff migration (LSM) is developed in the prestack plane-wave domain to increase the quality of migration images and the computational efficiency. Due to the limitation of current 3D marine acquisition

Helical waves in easy-plane antiferromagnets

Science.gov (United States)

Semenov, Yuriy G.; Li, Xi-Lai; Xu, Xinyi; Kim, Ki Wook

2017-12-01

Effective spin torques can generate the Néel vector oscillations in antiferromagnets (AFMs). Here, it is theoretically shown that these torques applied at one end of a normal AFM strip can excite a helical type of spin wave in the strip whose properties are drastically different from characteristic spin waves. An analysis based on both a Néel vector dynamical equation and the micromagnetic simulation identifies the direction of magnetic anisotropy and the damping factor as the two key parameters determining the dynamics. Helical wave propagation requires the hard axis of the easy-plane AFM to be aligned with the traveling direction, while the damping limits its spatial extent. If the damping is neglected, the calculation leads to a uniform periodic domain wall structure. On the other hand, finite damping decelerates the helical wave rotation around the hard axis, ultimately causing stoppage of its propagation along the strip. With the group velocity staying close to spin-wave velocity at the wave front, the wavelength becomes correspondingly longer away from the excitation point. In a sufficiently short strip, a steady-state oscillation can be established whose frequency is controlled by the waveguide length as well as the excitation energy or torque.

In-Vivo Synthetic Aperture and Plane Wave High Frame Rate Cardiac Imaging

DEFF Research Database (Denmark)

Stuart, Matthias Bo; Jensen, Jonas; Brandt, Andreas Hjelm

2014-01-01

A comparison of synthetic aperture imaging using spherical and plane waves with low number of emission events is presented. For both wave types, a 90 degree sector is insonified using 15 emission events giving a frame rate of 200 frames per second. Field II simulations of point targets show simil.......43 for spherical and 0.70 for plane waves. All measures are well within FDA limits for cardiac imaging. In-vivo images of the heart of a healthy 28-year old volunteer are shown....

Trapped waves on the mid-latitude β-plane

Science.gov (United States)

Paldor, Nathan; Sigalov, Andrey

2008-08-01

A new type of approximate solutions of the Linearized Shallow Water Equations (LSWE) on the mid-latitude β-plane, zonally propagating trapped waves with Airy-like latitude-dependent amplitude, is constructed in this work, for sufficiently small radius of deformation. In contrast to harmonic Poincare and Rossby waves, these newly found trapped waves vanish fast in the positive half-axis, and their zonal phase speed is larger than that of the corresponding harmonic waves for sufficiently large meridional domains. Our analysis implies that due to the smaller radius of deformation in the ocean compared with that in the atmosphere, the trapped waves are relevant to observations in the ocean whereas harmonic waves typify atmospheric observations. The increase in the zonal phase speed of trapped Rossby waves compared with that of harmonic ones is consistent with recent observations that showed that Sea Surface Height features propagated westwards faster than the phase speed of harmonic Rossby waves.

High-frequency limit of the transport cross section in scattering by an obstacle with impedance boundary conditions

Energy Technology Data Exchange (ETDEWEB)

Aleksenko, A I; Cruz, J P; Lakshtanov, E L [Department of Mathematics, Aveiro University, Aveiro 3810 (Portugal)], E-mail: lakshtanov@rambler.ru

2008-06-27

The scalar scattering of a plane wave by a strictly convex obstacle with impedance boundary conditions is considered. A uniform bound of the total cross section for all values of the frequency is presented. The high-frequency limit of the transport cross section is calculated and presented as a classical functional of the variational calculus.

High-frequency limit of the transport cross section in scattering by an obstacle with impedance boundary conditions

International Nuclear Information System (INIS)

Aleksenko, A I; Cruz, J P; Lakshtanov, E L

2008-01-01

The scalar scattering of a plane wave by a strictly convex obstacle with impedance boundary conditions is considered. A uniform bound of the total cross section for all values of the frequency is presented. The high-frequency limit of the transport cross section is calculated and presented as a classical functional of the variational calculus

An Apparatus for Constructing an Electromagnetic Plane Wave Model

Science.gov (United States)

Kneubil, Fabiana Botelho; Loures, Marcus Vinicius Russo; Amado, William

2015-01-01

In this paper we report on an activity aimed at building an electromagnetic wave. This was part of a class on the concept of mass offered to a group of 20 pre-service Brazilian physics teachers. The activity consisted of building a plane wave using an apparatus in which it is possible to fit some rods representing electric and magnetic fields into…

Plane Wave Medical Ultrasound Imaging Using Adaptive Beamforming

DEFF Research Database (Denmark)

Holfort, Iben Kraglund; Gran, Fredrik; Jensen, Jørgen Arendt

2008-01-01

In this paper, the adaptive, minimum variance (MV) beamformer is applied to medical ultrasound imaging. The Significant resolution and contrast gain provided by the adaptive, minimum variance (MV) beamformer, introduces the possibility of plane wave (PW) ultrasound imaging. Data is obtained using...

The Uniform geometrical Theory of Diffraction for elastodynamics: Plane wave scattering from a half-plane.

Science.gov (United States)

Djakou, Audrey Kamta; Darmon, Michel; Fradkin, Larissa; Potel, Catherine

2015-11-01

Diffraction phenomena studied in electromagnetism, acoustics, and elastodynamics are often modeled using integrals, such as the well-known Sommerfeld integral. The far field asymptotic evaluation of such integrals obtained using the method of steepest descent leads to the classical Geometrical Theory of Diffraction (GTD). It is well known that the method of steepest descent is inapplicable when the integrand's stationary phase point coalesces with its pole, explaining why GTD fails in zones where edge diffracted waves interfere with incident or reflected waves. To overcome this drawback, the Uniform geometrical Theory of Diffraction (UTD) has been developed previously in electromagnetism, based on a ray theory, which is particularly easy to implement. In this paper, UTD is developed for the canonical elastodynamic problem of the scattering of a plane wave by a half-plane. UTD is then compared to another uniform extension of GTD, the Uniform Asymptotic Theory (UAT) of diffraction, based on a more cumbersome ray theory. A good agreement between the two methods is obtained in the far field.

From plane waves to local Gaussians for the simulation of correlated periodic systems

International Nuclear Information System (INIS)

Booth, George H.; Tsatsoulis, Theodoros; Grüneis, Andreas; Chan, Garnet Kin-Lic

2016-01-01

We present a simple, robust, and black-box approach to the implementation and use of local, periodic, atom-centered Gaussian basis functions within a plane wave code, in a computationally efficient manner. The procedure outlined is based on the representation of the Gaussians within a finite bandwidth by their underlying plane wave coefficients. The core region is handled within the projected augment wave framework, by pseudizing the Gaussian functions within a cutoff radius around each nucleus, smoothing the functions so that they are faithfully represented by a plane wave basis with only moderate kinetic energy cutoff. To mitigate the effects of the basis set superposition error and incompleteness at the mean-field level introduced by the Gaussian basis, we also propose a hybrid approach, whereby the complete occupied space is first converged within a large plane wave basis, and the Gaussian basis used to construct a complementary virtual space for the application of correlated methods. We demonstrate that these pseudized Gaussians yield compact and systematically improvable spaces with an accuracy comparable to their non-pseudized Gaussian counterparts. A key advantage of the described method is its ability to efficiently capture and describe electronic correlation effects of weakly bound and low-dimensional systems, where plane waves are not sufficiently compact or able to be truncated without unphysical artifacts. We investigate the accuracy of the pseudized Gaussians for the water dimer interaction, neon solid, and water adsorption on a LiH surface, at the level of second-order Møller–Plesset perturbation theory.

From plane waves to local Gaussians for the simulation of correlated periodic systems

Energy Technology Data Exchange (ETDEWEB)

Booth, George H., E-mail: george.booth@kcl.ac.uk [Department of Physics, King’s College London, Strand, London WC2R 2LS (United Kingdom); Tsatsoulis, Theodoros; Grüneis, Andreas, E-mail: a.grueneis@fkf.mpg.de [Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart (Germany); Chan, Garnet Kin-Lic [Frick Laboratory, Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States)

2016-08-28

We present a simple, robust, and black-box approach to the implementation and use of local, periodic, atom-centered Gaussian basis functions within a plane wave code, in a computationally efficient manner. The procedure outlined is based on the representation of the Gaussians within a finite bandwidth by their underlying plane wave coefficients. The core region is handled within the projected augment wave framework, by pseudizing the Gaussian functions within a cutoff radius around each nucleus, smoothing the functions so that they are faithfully represented by a plane wave basis with only moderate kinetic energy cutoff. To mitigate the effects of the basis set superposition error and incompleteness at the mean-field level introduced by the Gaussian basis, we also propose a hybrid approach, whereby the complete occupied space is first converged within a large plane wave basis, and the Gaussian basis used to construct a complementary virtual space for the application of correlated methods. We demonstrate that these pseudized Gaussians yield compact and systematically improvable spaces with an accuracy comparable to their non-pseudized Gaussian counterparts. A key advantage of the described method is its ability to efficiently capture and describe electronic correlation effects of weakly bound and low-dimensional systems, where plane waves are not sufficiently compact or able to be truncated without unphysical artifacts. We investigate the accuracy of the pseudized Gaussians for the water dimer interaction, neon solid, and water adsorption on a LiH surface, at the level of second-order Møller–Plesset perturbation theory.

Decay rate ratios of Υ(5S)→B anti B reactions

International Nuclear Information System (INIS)

Hwang, Dae Sung; Son, Hyungsuk

2010-01-01

We calculate the decay rate ratios for OZI allowed decays of Υ(5S) to two B mesons by using the decay amplitudes which incorporate the wave function of the Υ(5S) state. We obtain the result that the branching ratio of the Υ(5S) decay to B s * anti B s * is much larger than the branching ratio to B s anti B s * or anti B s B s * , in good agreement with the recent experimental results of CLEO and BELLE. This agreement with the experimental results is made possible since the nodes of the Υ(5S) radial wave function induce the nodes of the decay amplitude. We find that the results for the Υ(5S) decays to B u (*) anti B u (*) or B d (*) anti B d (*) pairs are sensitive to the parameter values used for the potential between heavy quarks. (orig.)

The memory effect for plane gravitational waves

Science.gov (United States)

Zhang, P.-M.; Duval, C.; Gibbons, G. W.; Horvathy, P. A.

2017-09-01

We give an account of the gravitational memory effect in the presence of the exact plane wave solution of Einstein's vacuum equations. This allows an elementary but exact description of the soft gravitons and how their presence may be detected by observing the motion of freely falling particles. The theorem of Bondi and Pirani on caustics (for which we present a new proof) implies that the asymptotic relative velocity is constant but not zero, in contradiction with the permanent displacement claimed by Zel'dovich and Polnarev. A non-vanishing asymptotic relative velocity might be used to detect gravitational waves through the "velocity memory effect", considered by Braginsky, Thorne, Grishchuk, and Polnarev.

Traveling Wave Modes of a Plane Layered Anelastic Earth

Science.gov (United States)

2016-05-20

grant, “Coupled Modes in Elastic Bottoms” (1) is the publication “Traveling wave modes of a plane layered anelastic earth ” accepted for...anelastic earth Robert I. Odom Applied Physics Laboratory and Department of Earth and Space Sciences University of Washington, 1013 NE 40th St., Seattle...contrast to a similar standing wave problem for the earth free oscillations (Tromp and Dahlen, 1990). Attenuation is commonly incorporated into synthetic

Multiphoton processes in the field of two-frequency circularly polarized plane electromagnetic waves

International Nuclear Information System (INIS)

Yu, An

1997-01-01

The authors solve Dirac's equation for an electron in the field of a two-frequency plane electromagnetic wave, deriving general formulae for the probabilities of radiation of a photon by the electron, and for the probabilities for pair production by a photon when the two-frequency wave is circularly polarized. In contrast to the case of a monochromatic-plane electromagnetic wave, when an electron is in the field of a two-frequency circularly polarized wave, besides the absorption of multiphotons and emission of simple harmonics of the individual waves, stimulated multiphoton emission processes and various composite harmonic-photon emission processes are occurred: when a high-energy photon is in a such a field, multiphoton processes also follow the pair production processes

Scattering of spinning test particles by gravitational plane waves

International Nuclear Information System (INIS)

Bini, D.; Gemelli, G.

1997-01-01

The authors study the motion of spinning particles in the gravitational plane-wave background and discuss particular solutions under a suitable choice of supplementary conditions. An analysis of the discontinuity of the motion across the wavefront is presented too

Technique for measurements of plane waves of uniaxial strain

International Nuclear Information System (INIS)

Graham, R.A.

1977-01-01

The measurement of plane waves in uniaxial strain, in which large surface areas are loaded and the measurements are restricted to a central region that is not influenced by lateral boundaries, is discussed. Measuring techniques are covered and instruments are discussed

A Note on Eccentricities within a Single n-Layered Obstacle and their Influence on Time Harmonic SH Waves

International Nuclear Information System (INIS)

Weber, Wolfgang; Zastrau, Bernd W.

2010-01-01

In this contribution some aspects of SH wave scattering due to a single eccentric n-layered obstacle are being looked at. Herewith, the basis solution is derived analytically for an elliptic inclusion as it occurs in civil engineering practice e. g. within textile reinforced concrete. Hence, (modified) MATHIEUfunctions have to be evaluated. Later on, the degenerate case of an eccentric circular obstacle is dealt with.

Soft Gravitons & the Memory Effect for Plane Gravitational Waves

OpenAIRE

Zhang, P. -M.; Duval, C.; Gibbons, G. W.; Horvathy, P. A.

2017-01-01

The "gravitational memory effect" due to an exact plane wave provides us with an elementary description of the diffeomorphisms associated with soft gravitons. It is explained how the presence of the latter may be detected by observing the motion of freely falling particles or other forms of gravitational wave detection. Numerical calculations confirm the relevance of the first, second and third time integrals of the Riemann tensor pointed out earlier. Solutions for various profiles are constr...

Efficient evaluation of Coulomb integrals in a mixed Gaussian and plane-wave basis

Czech Academy of Sciences Publication Activity Database

Čársky, Petr

2007-01-01

Roč. 107, č. 1 (2007), s. 56-62 ISSN 0020-7608 R&D Projects: GA AV ČR IAA100400501; GA AV ČR 1ET400400413 Grant - others:European Science Foundation (EIPAM)(XE) PESC7-20; U.S. National Science Foundation(US) OISE-0532040 Institutional research plan: CEZ:AV0Z40400503 Keywords : two- electron integrals * mixed plane-wave and Gaussian basis sets * Coulomb integrals Subject RIV: CF - Physical ; The oretical Chemistry Impact factor: 1.368, year: 2007

Studies on anti-tumor effect of electromagnetic waves

International Nuclear Information System (INIS)

Kadota, Ikuhito; Wakabayashi, Toshio; Ogoshi, Kyoji; Kamijo, Akemi

1995-01-01

Hyperthermia have treated cancer with thermal effect of electromagnetic waves for biological systems, but the expected effect is not shown. Also non-thermal effect of electromagnetic waves is out of consideration. If irradiation conditions of electromagnetic waves with non-thermal anti-tumor effect are obtained, we can expect newly spread in cancer therapy. We had in vivo experiments that electromagnetic waves were irradiated to mice. In some irradiation conditions, the non-thermal anti-tumor effect of electromagnetic waves showed. In order to specify the irradiation conditions, we had in vitro experiments. We found that activity ratio of tumor cells which was measured by MTT method depended on irradiation time and power of electromagnetic waves. These results are useful for the cancer therapy. (author)

Phase function of a spherical particle when scattering an inhomogeneous electromagnetic plane wave

DEFF Research Database (Denmark)

Frisvad, Jeppe Revall

2018-01-01

of the complex hypergeometric function 2F1 for every term of a series expansion. In this work, I develop a simpler solution based on associated Legendre functions with argument zero. It is similar to the solution for homogeneous plane waves but with new explicit expressions for the angular dependency of the far......In absorbing media, electromagnetic plane waves are most often inhomogeneous. Existing solutions for the scattering of an inhomogeneous plane wave by a spherical particle provide no explicit expressions for the scattering components. In addition, current analytical solutions require evaluation......-field scattering components, that is, the phase function. I include recurrence formulae for practical evaluation and provide numerical examples to evaluate how well the new expressions match previous work in some limiting cases. The predicted difference in the scattering phase function due to inhomogeneity...

Scattering of three-dimensional plane waves in a self-reinforced half-space lying over a triclinic half-space

Science.gov (United States)

Gupta, Shishir; Pramanik, Abhijit; Smita; Pramanik, Snehamoy

2018-06-01

The phenomenon of plane waves at the intersecting plane of a triclinic half-space and a self-reinforced half-space is discussed with possible applications during wave propagation. Analytical expressions of the phase velocities of reflection and refraction for quasi-compressional and quasi-shear waves under initial stress are discussed carefully. The closest form of amplitude proportions on reflection and refraction factors of three quasi-plane waves are developed mathematically by applying appropriate boundary conditions. Graphics are sketched to exhibit the consequences of initial stress in the three-dimensional plane wave on reflection and refraction coefficients. Some special cases that coincide with the fundamental properties of several layers are designed to express the reflection and refraction coefficients.

Energy Relations for Plane Waves Reflected from Moving Media

DEFF Research Database (Denmark)

Daly, P.; Gruenberg, Harry

1967-01-01

When a plane wave is obliquely incident from vacuum on a semi-infinite moving medium, the energy flow carried by the incident wave, is in general, not carried away by the reflected and transmitted waves. This is only the case when the medium velocity is parallel to its vacuum interface. Otherwise...... there is a net inflow or outflow of electromagnetic energy, which can be accounted for by the change of stored energy in the system, and the work done by the mechanical forces acting on the medium. A detailed energy balance is drawn up for two different media moving normal to their vacuum interfaces: (a...

Robot Navigation Control Based on Monocular Images: An Image Processing Algorithm for Obstacle Avoidance Decisions

Directory of Open Access Journals (Sweden)

William Benn

2012-01-01

Full Text Available This paper covers the use of monocular vision to control autonomous navigation for a robot in a dynamically changing environment. The solution focused on using colour segmentation against a selected floor plane to distinctly separate obstacles from traversable space: this is then supplemented with canny edge detection to separate similarly coloured boundaries to the floor plane. The resulting binary map (where white identifies an obstacle-free area and black identifies an obstacle could then be processed by fuzzy logic or neural networks to control the robot’s next movements. Findings show that the algorithm performed strongly on solid coloured carpets, wooden, and concrete floors but had difficulty in separating colours in multicoloured floor types such as patterned carpets.

Geometrical optics in the near field: local plane-interface approach with evanescent waves.

Science.gov (United States)

Bose, Gaurav; Hyvärinen, Heikki J; Tervo, Jani; Turunen, Jari

2015-01-12

We show that geometrical models may provide useful information on light propagation in wavelength-scale structures even if evanescent fields are present. We apply a so-called local plane-wave and local plane-interface methods to study a geometry that resembles a scanning near-field microscope. We show that fair agreement between the geometrical approach and rigorous electromagnetic theory can be achieved in the case where evanescent waves are required to predict any transmission through the structure.

GENERAL P, TYPE-I S, AND TYPE-II S WAVES IN ANELASTIC SOLIDS; INHOMOGENEOUS WAVE FIELDS IN LOW-LOSS SOLIDS.

Science.gov (United States)

Borcherdt, Roger D.; Wennerberg, Leif

1985-01-01

The physical characteristics for general plane-wave radiation fields in an arbitrary linear viscoelastic solid are derived. Expressions for the characteristics of inhomogeneous wave fields, derived in terms of those for homogeneous fields, are utilized to specify the characteristics and a set of reference curves for general P and S wave fields in arbitrary viscoelastic solids as a function of wave inhomogeneity and intrinsic material absorption. The expressions show that an increase in inhomogeneity of the wave fields cause the velocity to decrease, the fractional-energy loss (Q** minus **1) to increase, the deviation of maximum energy flow with respect to phase propagation to increase, and the elliptical particle motions for P and type-I S waves to approach circularity. Q** minus **1 for inhomogeneous type-I S waves is shown to be greater than that for type-II S waves, with the deviation first increasing then decreasing with inhomogeneity. The mean energy densities (kinetic, potential, and total), the mean rate of energy dissipation, the mean energy flux, and Q** minus **1 for inhomogeneous waves are shown to be greater than corresponding characteristics for homogeneous waves, with the deviations increasing as the inhomogeneity is increased for waves of fixed maximum displacement amplitude.

Far-field divergence of a vectorial plane wave diffracted by a circular aperture from the vectorial structure

International Nuclear Information System (INIS)

Zhou Guo-Quan

2011-01-01

Based on the vectorial structure of an electromagnetic wave, the analytical and concise expressions for the TE and TM terms of a vectorial plane wave diffracted by a circular aperture are derived in the far-field. The expressions of the energy flux distributions of the TE term, the TM term and the diffracted plane wave are also presented. The ratios of the power of the TE and TM terms to that of the diffracted plane wave are examined in the far-field. In addition, the far-field divergence angles of the TE term, the TM term and the diffracted plane wave, which are related to the energy flux distribution, are investigated. The different energy flux distributions of the TE and TM terms result in the discrepancy of their divergence angles. The influences of the linearly polarized angle and the radius of the circular aperture on the far-field divergence angles of the TE term, the TM term and the diffracted plane wave are discussed in detail. This research may promote the recognition of the optical propagation through a circular aperture. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Simulation of Guided Wave Interaction with In-Plane Fiber Waviness

Science.gov (United States)

Leckey, Cara A. C.; Juarez, Peter D.

2016-01-01

Reducing the timeline for certification of composite materials and enabling the expanded use of advanced composite materials for aerospace applications are two primary goals of NASA's Advanced Composites Project (ACP). A key a technical challenge area for accomplishing these goals is the development of rapid composite inspection methods with improved defect characterization capabilities. Ongoing work at NASA Langley is focused on expanding ultrasonic simulation capabilities for composite materials. Simulation tools can be used to guide the development of optimal inspection methods. Custom code based on elastodynamic finite integration technique is currently being developed and implemented to study ultrasonic wave interaction with manufacturing defects, such as in-plane fiber waviness (marcelling). This paper describes details of validation comparisons performed to enable simulation of guided wave propagation in composites containing fiber waviness. Simulation results for guided wave interaction with in-plane fiber waviness are also discussed. The results show that the wavefield is affected by the presence of waviness on both the surface containing fiber waviness, as well as the opposite surface to the location of waviness.

Spin waves in two-dimensional ferromagnet with large easy-plane anisotropy

International Nuclear Information System (INIS)

Fridman, Yu.A.; Spirin, D.V.

2002-01-01

Spin waves in easy-plane two-dimensional ferromagnet when anisotropy is much stronger than exchange are investigated. The spectra of magnons, the spin-spin and quadrupolar correlation functions have been derived. It is shown that in such a system there exist spin waves at low temperatures. Some properties of the quadrupolar ordering in ferromagnets are discussed

Quadrupole mass detector in the field of weak plane gravitational waves

International Nuclear Information System (INIS)

Borisova, L.B.

1978-01-01

Studied is the behaviour of the system which consists of two test particles connected by a string (quadrupole mass detector) and placed in the field of weak plane monochromatic gravitational waves. It is shown that at cross orientation of the detector the gravitational wave effecting such a system excites oscillations in it with the frequency equal to that of the gravitational wave source. The role of the driving force is played by the periodical change with the time of the equilibrium position. The gravitational wave does not influence the detector at its longitudinal orientation

A projection-free method for representing plane-wave DFT results in an atom-centered basis

International Nuclear Information System (INIS)

Dunnington, Benjamin D.; Schmidt, J. R.

2015-01-01

Plane wave density functional theory (DFT) is a powerful tool for gaining accurate, atomic level insight into bulk and surface structures. Yet, the delocalized nature of the plane wave basis set hinders the application of many powerful post-computation analysis approaches, many of which rely on localized atom-centered basis sets. Traditionally, this gap has been bridged via projection-based techniques from a plane wave to atom-centered basis. We instead propose an alternative projection-free approach utilizing direct calculation of matrix elements of the converged plane wave DFT Hamiltonian in an atom-centered basis. This projection-free approach yields a number of compelling advantages, including strict orthonormality of the resulting bands without artificial band mixing and access to the Hamiltonian matrix elements, while faithfully preserving the underlying DFT band structure. The resulting atomic orbital representation of the Kohn-Sham wavefunction and Hamiltonian provides a gateway to a wide variety of analysis approaches. We demonstrate the utility of the approach for a diverse set of chemical systems and example analysis approaches

An IBEM solution to the scattering of plane SH-waves by a lined tunnel in elastic wedge space

Science.gov (United States)

Liu, Zhongxian; Liu, Lei

2015-02-01

The indirect boundary element method (IBEM) is developed to solve the scattering of plane SH-waves by a lined tunnel in elastic wedge space. According to the theory of single-layer potential, the scattered-wave field can be constructed by applying virtual uniform loads on the surface of lined tunnel and the nearby wedge surface. The densities of virtual loads can be solved by establishing equations through the continuity conditions on the interface and zero-traction conditions on free surfaces. The total wave field is obtained by the superposition of free field and scattered-wave field in elastic wedge space. Numerical results indicate that the IBEM can solve the diffraction of elastic wave in elastic wedge space accurately and efficiently. The wave motion feature strongly depends on the wedge angle, the angle of incidence, incident frequency, the location of lined tunnel, and material parameters. The waves interference and amplification effect around the tunnel in wedge space is more significant, causing the dynamic stress concentration factor on rigid tunnel and the displacement amplitude of flexible tunnel up to 50.0 and 17.0, respectively, more than double that of the case of half-space. Hence, considerable attention should be paid to seismic resistant or anti-explosion design of the tunnel built on a slope or hillside.

A parallel orbital-updating based plane-wave basis method for electronic structure calculations

International Nuclear Information System (INIS)

Pan, Yan; Dai, Xiaoying; Gironcoli, Stefano de; Gong, Xin-Gao; Rignanese, Gian-Marco; Zhou, Aihui

2017-01-01

Highlights: • Propose three parallel orbital-updating based plane-wave basis methods for electronic structure calculations. • These new methods can avoid the generating of large scale eigenvalue problems and then reduce the computational cost. • These new methods allow for two-level parallelization which is particularly interesting for large scale parallelization. • Numerical experiments show that these new methods are reliable and efficient for large scale calculations on modern supercomputers. - Abstract: Motivated by the recently proposed parallel orbital-updating approach in real space method , we propose a parallel orbital-updating based plane-wave basis method for electronic structure calculations, for solving the corresponding eigenvalue problems. In addition, we propose two new modified parallel orbital-updating methods. Compared to the traditional plane-wave methods, our methods allow for two-level parallelization, which is particularly interesting for large scale parallelization. Numerical experiments show that these new methods are more reliable and efficient for large scale calculations on modern supercomputers.

Lectures on strings in flat space and plane waves from N = 4 super Yang Mills

International Nuclear Information System (INIS)

Maldacena, J.

2003-01-01

In these lecture notes we explain how the string spectrum in flat space and plane waves arises from the large N limit of U(N) N = 4 super Yang Mills. We reproduce the spectrum by summing a subset of the planar Feynman diagrams. We also describe some other aspects of string propagation on plane wave backgrounds. (author)

Path integral for Dirac particle in plane wave field

International Nuclear Information System (INIS)

Zeggari, S.; Boudjedaa, T.; Chetouani, L.

2001-01-01

The problem of a relativistic spinning particle in interaction with an electromagnetic plane wave field is treated via path integrals. The dynamics of the spin of the particle is described using the supersymmetric action proposed by Fradkin and Gitman. The problem has been solved by using two identities, one bosonic and the other fermionic, which are related directly to the classical equations of motion. The exact expression of the relative Green's function is given and the result agrees with those of the literature. Further, the suitably normalized wave functions are also extracted. (orig.)

On the comparsion of the Spherical Wave Expansion-to-Plane Wave Expansion and the Sources Reconstruction Method for Antenna Diagnostics

DEFF Research Database (Denmark)

Alvarez, Yuri; Cappellin, Cecilia; Las-Heras, Fernando

2008-01-01

A comparison between two recently developed methods for antenna diagnostics is presented. On one hand, the Spherical Wave Expansion-to-Plane Wave Expansion (SWE-PWE), based on the relationship between spherical and planar wave modes. On the other hand, the Sources Reconstruction Method (SRM), based...

Can plane wave modes be physical modes in soliton models?

International Nuclear Information System (INIS)

Aldabe, F.

1995-08-01

I show that plane waves may not be used as asymptotic states in soliton models because they describe unphysical states. When asymptotic states are taken to the physical there is not T-matrix of O(1). (author). 9 refs

Effect of weak nonlinearities on the plane waves in a plasma stream

International Nuclear Information System (INIS)

Seshadri, S.R.

1976-01-01

The effect of weak nonlinearities on the monochromatic plane waves in a cold infinite plasma stream is investigated for the case in which the waves are progressing parallel to the drift velocity. The fast and the slow space-charge waves undergo amplitude-dependent frequency and wave number shifts. There is a long time slow modulation of the amplitude of the electromagnetic mode which becomes unstable to this nonlinear wave modulation. The importance of using the relativistically correct equation of motion for predicting correctly the modulational stability of the electromagnetic mode is pointed out. (author)

Plane waves and spherical means applied to partial differential equations

CERN Document Server

John, Fritz

2004-01-01

Elementary and self-contained, this heterogeneous collection of results on partial differential equations employs certain elementary identities for plane and spherical integrals of an arbitrary function, showing how a variety of results on fairly general differential equations follow from those identities. The first chapter deals with the decomposition of arbitrary functions into functions of the type of plane waves. Succeeding chapters introduce the first application of the Radon transformation and examine the solution of the initial value problem for homogeneous hyperbolic equations with con

C1,1 regularity for degenerate elliptic obstacle problems

Science.gov (United States)

Daskalopoulos, Panagiota; Feehan, Paul M. N.

2016-03-01

The Heston stochastic volatility process is a degenerate diffusion process where the degeneracy in the diffusion coefficient is proportional to the square root of the distance to the boundary of the half-plane. The generator of this process with killing, called the elliptic Heston operator, is a second-order, degenerate-elliptic partial differential operator, where the degeneracy in the operator symbol is proportional to the distance to the boundary of the half-plane. In mathematical finance, solutions to the obstacle problem for the elliptic Heston operator correspond to value functions for perpetual American-style options on the underlying asset. With the aid of weighted Sobolev spaces and weighted Hölder spaces, we establish the optimal C 1 , 1 regularity (up to the boundary of the half-plane) for solutions to obstacle problems for the elliptic Heston operator when the obstacle functions are sufficiently smooth.

Analytical Time-Domain Solution of Plane Wave Propagation Across a Viscoelastic Rock Joint

Science.gov (United States)

Zou, Yang; Li, Jianchun; Laloui, Lyesse; Zhao, Jian

2017-10-01

The effects of viscoelastic filled rock joints on wave propagation are of great significance in rock engineering. The solutions in time domain for plane longitudinal ( P-) and transverse ( S-) waves propagation across a viscoelastic rock joint are derived based on Maxwell and Kelvin models which are, respectively, applied to describe the viscoelastic deformational behaviour of the rock joint and incorporated into the displacement discontinuity model (DDM). The proposed solutions are verified by comparing with the previous studies on harmonic waves, which are simulated by sinusoidal incident P- and S-waves. Comparison between the predicted transmitted waves and the experimental data for P-wave propagation across a joint filled with clay is conducted. The Maxwell is found to be more appropriate to describe the filled joint. The parametric studies show that wave propagation is affected by many factors, such as the stiffness and the viscosity of joints, the incident angle and the duration of incident waves. Furthermore, the dependences of the transmission and reflection coefficients on the specific joint stiffness and viscosity are different for the joints with Maxwell and Kelvin behaviours. The alternation of the reflected and transmitted waveforms is discussed, and the application scope of this study is demonstrated by an illustration of the effects of the joint thickness. The solutions are also extended for multiple parallel joints with the virtual wave source method and the time-domain recursive method. For an incident wave with arbitrary waveform, it is convenient to adopt the present approach to directly calculate wave propagation across a viscoelastic rock joint without additional mathematical methods such as the Fourier and inverse Fourier transforms.

Simplified description of out-of-plane waves in thin annular elastic plates

DEFF Research Database (Denmark)

Zadeh, Maziyar Nesari; Sorokin, Sergey

2013-01-01

Dispersion relations are derived for the out-of-plane wave propagation in planar elastic plates with constant curvature using the classical Kirchhoff thin plate theory. The dispersion diagrams and the mode shapes are compared with their counterparts for a straight plate strip and the role...... of curvature is assessed for plates with unconstrained edges. Elementary Bernoulli–Euler theory for a beam of rectangular cross-section with the circular shape of its axis is also employed to analyze the wave guide properties of this structure in its out-of-plane deformation. The applicability range...... of the elementary beam theory is validated. The wave finite element method in the formulation of the three-dimensional elasticity theory is used to ensure that the comparison of dispersion diagrams is performed in the frequency range, where the classical thin plate theory is valid. Thus, the paper summarizes...

Augmented-plane-wave calculations on small molecules

International Nuclear Information System (INIS)

Serena, P.A.; Baratoff, A.; Soler, J.M.

1993-01-01

We have performed ab initio calculations on a wide range of small molecules, demonstrating the accuracy and flexibility of an alternative method for calculating the electronic structure of molecules, solids, and surfaces. It is based on the local-density approximation (LDA) for exchange and correlation and the nonlinear augmented-plane-wave method. Very accurate atomic forces are obtained directly. This allows for implementation of Car-Parrinello-like techniques to determine simultaneously the self-consistent electron wave functions and the equilibrium atomic positions within an iterative scheme. We find excellent agreement with the best existing LDA-based calculations and remarkable agreement with experiment for the equilibrium geometries, vibrational frequencies, and dipole moments of a wide variety of molecules, including strongly bound homopolar and polar molecules, hydrogen-bound and electron-deficient molecules, and weakly bound alkali and noble-metal dimers, although binding energies are overestimated

The wave equation: From eikonal to anti-eikonal approximation

Directory of Open Access Journals (Sweden)

Luis Vázquez

2016-06-01

Full Text Available When the refractive index changes very slowly compared to the wave-length we may use the eikonal approximation to the wave equation. In the opposite case, when the refractive index highly variates over the distance of one wave-length, we have what can be termed as the anti-eikonal limit. This situation is addressed in this work. The anti-eikonal limit seems to be a relevant tool in the modelling and design of new optical media. Besides, it describes a basic universal behaviour, independent of the actual values of the refractive index and, thus, of the media, for the components of a wave with wave-length much greater than the characteristic scale of the refractive index.

Theory of steady-state plane tunneling-assisted impact ionization waves

International Nuclear Information System (INIS)

Kyuregyan, A. S.

2013-01-01

The effect of band-to-band and trap-assisted tunneling on the properties of steady-state plane ionization waves in p + -n-n + structures is theoretically analyzed. It is shown that such tunneling-assisted impact ionization waves do not differ in a qualitative sense from ordinary impact ionization waves propagating due to the avalanche multiplication of uniformly distributed seed electrons and holes. The quantitative differences of tunneling-assisted impact ionization waves from impact ionization waves are reduced to a slightly different relation between the wave velocity u and the maximum field strength E M at the front. It is shown that disregarding impact ionization does not exclude the possibility of the existence of tunneling-assisted ionization waves; however, their structure radically changes, and their velocity strongly decreases for the same E M . A comparison of the dependences u(E M ) for various ionization-wave types makes it possible to determine the conditions under which one of them is dominant. In conclusion, unresolved problems concerning the theory of tunneling-assisted impact ionization waves are discussed and the directions of further studies are outlined

Invertible propagator for plane wave illumination of forward-scattering structures.

Science.gov (United States)

Samelsohn, Gregory

2017-05-10

Propagation of directed waves in forward-scattering media is considered. It is assumed that the evolution of the wave field is governed by the standard parabolic wave equation. An efficient one-step momentum-space propagator, suitable for a tilted plane wave illumination of extended objects, is derived. It is expressed in terms of a propagation operator that transforms (the complex exponential of) a linogram of the illuminated object into a set of its diffraction patterns. The invertibility of the propagator is demonstrated, which permits a multiple-shot scatter correction to be performed, and makes the solution especially attractive for either projective or tomographic imaging. As an example, high-resolution tomograms are obtained in numerical simulations implemented for a synthetic phantom, with both refractive and absorptive inclusions.

Phase function of a spherical particle when scattering an inhomogeneous electromagnetic plane wave.

Science.gov (United States)

Frisvad, Jeppe Revall

2018-04-01

In absorbing media, electromagnetic plane waves are most often inhomogeneous. Existing solutions for the scattering of an inhomogeneous plane wave by a spherical particle provide no explicit expressions for the scattering components. In addition, current analytical solutions require evaluation of the complex hypergeometric function F 1 2 for every term of a series expansion. In this work, I develop a simpler solution based on associated Legendre functions with argument zero. It is similar to the solution for homogeneous plane waves but with new explicit expressions for the angular dependency of the far-field scattering components, that is, the phase function. I include recurrence formulas for practical evaluation and provide numerical examples to evaluate how well the new expressions match previous work in some limiting cases. The predicted difference in the scattering phase function due to inhomogeneity is not negligible for light entering an absorbing medium at an oblique angle. The presented theory could thus be useful for predicting scattering behavior in dye-based random lasing and in solar cell absorption enhancement.

REFLECT: a program to integrate the wave equation through a plane stratified plasma

International Nuclear Information System (INIS)

Greene, J.W.

1975-01-01

A program was developed to integrate the wave equation through a plane stratified plasma with a general density distribution. The reflection and transmission of a plane wave are computed as a function of the angle of incidence. The polarization of the electric vector is assumed to be perpendicular to the plane of incidence. The model for absorption by classical inverse bremsstrahlung avoids the improper extrapolation of underdense formulae that are singular at the plasma critical surface. Surprisingly good agreement with the geometric-optics analysis of a linear layer was found. The system of ordinary differential equations is integrated by the variable-step, variable-order Adams method in the Lawrence Livermore Laboratory Gear package. Parametric studies of the absorption are summarized, and some possibilities for further development of the code are discussed. (auth)

Plane-wave spectrum approach for the calculation of electromagnetic absorption under near-field exposure conditions

International Nuclear Information System (INIS)

Chatterjee, I.; Gandhi, O.P.; Hagmann, M.J.; Riazi, A.

1980-01-01

The exposure of humans to electromagnetic near fields has not been sufficiently emphasized by researcher. We have used the plane-wave-spectrum approach to evaluate the electromagnetic field and determine the energy deposited in a lossy, homogeneous, semi-infinite slab placed in the near field of a source leaking radiation. Values of the fields and absorbed energy in the target are obtained by vector summation of the contributions of all the plane waves into which the prescribed field is decomposed. Use of a fast Fourier transform algorithm contributes to the high efficiency of the computations. The numerical results show that, for field distributions that are nearly constant over a physical extent of at least a free-space wavelength, the energy coupled into the target is approximately equal to the resulting from plane-wave exposed

The Relativistic Transformation for an Electromagnetic Plane Wave with General Time Dependence

Science.gov (United States)

Smith, Glenn S.

2012-01-01

In special relativity, the transformation between inertial frames for an electromagnetic plane wave is usually derived for the time-harmonic case (the field is a sinusoid of infinite duration), even though all practical waves are of finite duration and may not even contain a dominant sinusoid. This paper presents an alternative derivation in which…

Imaging off-plane shear waves with a two-dimensional phononic crystal lens

International Nuclear Information System (INIS)

Chiang Chenyu; Luan Pigang

2010-01-01

A two-dimensional flat phononic crystal (PC) lens for focusing off-plane shear waves is proposed. The lens consists of a triangular lattice hole-array, embedded in a solid matrix. The self-collimation effect is employed to guide the shear waves propagating through the lens along specific directions. The Dirichlet-to-Neumann maps (DtN) method is employed to calculate the band structure of the PC, which can avoid the problems of bad convergence and fake bands automatically in the void-solid PC structure. When the lens is illuminated by the off-plane shear waves emanating from a point source, a subwavelength image appears in the far-field zone. The imaging characteristics are investigated by calculating the displacement fields explicitly using the multiple scattering method, and the results are in good agreement with the ray-trace predictions. Our results may provide insights for designing new phononic devices.

Photonic band structures solved by a plane-wave-based transfer-matrix method.

Science.gov (United States)

Li, Zhi-Yuan; Lin, Lan-Lan

2003-04-01

Transfer-matrix methods adopting a plane-wave basis have been routinely used to calculate the scattering of electromagnetic waves by general multilayer gratings and photonic crystal slabs. In this paper we show that this technique, when combined with Bloch's theorem, can be extended to solve the photonic band structure for 2D and 3D photonic crystal structures. Three different eigensolution schemes to solve the traditional band diagrams along high-symmetry lines in the first Brillouin zone of the crystal are discussed. Optimal rules for the Fourier expansion over the dielectric function and electromagnetic fields with discontinuities occurring at the boundary of different material domains have been employed to accelerate the convergence of numerical computation. Application of this method to an important class of 3D layer-by-layer photonic crystals reveals the superior convergency of this different approach over the conventional plane-wave expansion method.

Photonic band structures solved by a plane-wave-based transfer-matrix method

International Nuclear Information System (INIS)

Li Zhiyuan; Lin Lanlan

2003-01-01

Transfer-matrix methods adopting a plane-wave basis have been routinely used to calculate the scattering of electromagnetic waves by general multilayer gratings and photonic crystal slabs. In this paper we show that this technique, when combined with Bloch's theorem, can be extended to solve the photonic band structure for 2D and 3D photonic crystal structures. Three different eigensolution schemes to solve the traditional band diagrams along high-symmetry lines in the first Brillouin zone of the crystal are discussed. Optimal rules for the Fourier expansion over the dielectric function and electromagnetic fields with discontinuities occurring at the boundary of different material domains have been employed to accelerate the convergence of numerical computation. Application of this method to an important class of 3D layer-by-layer photonic crystals reveals the superior convergency of this different approach over the conventional plane-wave expansion method

Uniqueness in inverse elastic scattering with finitely many incident waves

International Nuclear Information System (INIS)

Elschner, Johannes; Yamamoto, Masahiro

2009-01-01

We consider the third and fourth exterior boundary value problems of linear isotropic elasticity and present uniqueness results for the corresponding inverse scattering problems with polyhedral-type obstacles and a finite number of incident plane elastic waves. Our approach is based on a reflection principle for the Navier equation. (orig.)

Measurement of Plane-Wave Spectra of Ground Penetrating Radar Antennas

DEFF Research Database (Denmark)

Lenler-Eriksen, Hans-Rudolph; Meincke, Peter

2005-01-01

The plane-wave transmitting spectrum of a ground penetrating radar (GPR) loop antenna close to the air-soil interface is measured by means of a probe buried in soil. Probe correction is implemented based upon knowledge about the complex permittivity of the soil and the current distribution...

Tissue elasticity of in vivo skeletal muscles measured in the transverse and longitudinal planes using shear wave elastography.

Science.gov (United States)

Chino, Kentaro; Kawakami, Yasuo; Takahashi, Hideyuki

2017-07-01

The aim of the present study was to measure in vivo skeletal muscle elasticity in the transverse and longitudinal planes using shear wave elastography and then to compare the image stability, measurement values and measurement repeatability between these imaging planes. Thirty-one healthy males participated in this study. Tissue elasticity (shear wave velocity) of the medial gastrocnemius, rectus femoris, biceps brachii and rectus abdominis was measured in both the transverse and longitudinal planes using shear wave elastography. Image stability was evaluated by the standard deviation of the colour distribution in the shear wave elastography image. Measurement repeatability was assessed by the coefficient of variance obtained from three measurement values. Image stability of all tested muscles was significantly higher in the longitudinal plane (Pplanes (P>0·05), except in the biceps brachii (P = 0·001). Measurement values of the medial gastrocnemius, rectus femoris and biceps brachii were significantly different between the imaging planes (Pplane, which indicates that imaging plane should be considered when measuring skeletal muscle tissue elasticity by shear wave elastography. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Unified Approach of Unmanned Surface Vehicle Navigation in Presence of Waves

Directory of Open Access Journals (Sweden)

Oren Gal

2011-01-01

Full Text Available Most of the present work for unmanned surface vehicle (USV navigation does not take into account environmental disturbances such as ocean waves, winds, and currents. In some scenarios, waves should be treated as special case of dynamic obstacle and can be critical to USV’s safety. For the first time, this paper presents unique concept facing this challenge by combining ocean waves' formulation with the probabilistic velocity obstacle (PVO method for autonomous navigation. A simple navigation algorithm is presented in order to apply the method of USV’s navigation in presence of waves. A planner simulation dealing with waves and obstacles avoidance is introduced.

Existence and Stability of Spatial Plane Waves for the Incompressible Navier-Stokes in R^3

Science.gov (United States)

Correia, Simão; Figueira, Mário

2018-03-01

We consider the three-dimensional incompressible Navier-Stokes equation on the whole space. We observe that this system admits a L^∞ family of global spatial plane wave solutions, which are connected with the two-dimensional equation. We then proceed to prove local well-posedness over a space which includes L^3(R^3) and these solutions. Finally, we prove L^3-stability of spatial plane waves, with no condition on their size.

Further study of the ππ S-wave isoscalar amplitude below the K(anti)K threshold

International Nuclear Information System (INIS)

Kaminski, R.; Lesniak, L.; Rybicki, K.

1999-01-01

We continue the analysis of S-wave production amplitudes for the reaction π - p→π + π - n involving the data obtained by the CERN-Cracow-Munich collaboration on a transversely polarized target at 17.2 GeV π - momentum. This study deals with the region below the (anti)KK threshold. In particular, we study the ''up-steep'' solution containing a narrow S-wave resonance under the ρ(770). This solution exhibits a considerable inelasticity η which does not have any physical interpretation. Assuming that this inelasticity behaviour represents an unlikely fluctuation we impose η≡1 for all data points. This leads to non-physical results in one third of the π + π - effective mass bins and in the remaining mass bins some parameters behave in a queer way. The situation is even worse for the ''down-steep'' solution. We conclude that the 17.2 GeV data cannot be described by a relatively narrow f 0 (750). The ''down-flat'' and ''up-flat'' solutions which easily pass the η≡1 constraint exhibit a slow increase of phase shifts in the ρ(770) mass range. (author)

An Analytical Method of Auxiliary Sources Solution for Plane Wave Scattering by Impedance Cylinders

DEFF Research Database (Denmark)

Larsen, Niels Vesterdal; Breinbjerg, Olav

2004-01-01

Analytical Method of Auxiliary Sources solutions for plane wave scattering by circular impedance cylinders are derived by transformation of the exact eigenfunction series solutions employing the Hankel function wave transformation. The analytical Method of Auxiliary Sources solution thus obtained...

Instabilities in dynamic anti-plane sliding of an elastic layer on a dissimilar elastic half-space

Science.gov (United States)

Kunnath, R.

2012-12-01

The stability of dynamic anti-plane sliding at an interface between an elastic layer and an elastic half-space with dissimilar elastic properties is studied. Friction at the interface is assumed to follow a rate- and state-dependent law, with a positive instantaneous dependence on slip velocity and a rate weakening behavior in the steady state. The perturbations are of the form exp(ikx+pt), where k is the wavenumber, x is the coordinate along the interface, p is the time response to the perturbation and t is time. The results of the stability analysis are shown in Figs. 1 and 2 with the velocity weakening parameter b/a=5, shear wave speed ratio cs'/cs=1.2, shear modulus ratio μ'/μ=1.2 and non-dimensional layer thickness H=100. The normalized instability growth rate and normalized phase velocity are plotted as a function of wavenumber. Fig.1 is for a non-dimensional unperturbed slip velocity ɛ=5 (rapid sliding) while Fig. 2 is for ɛ=0.05 (slow sliding). The results show the destabilization of interfacial waves. For slow sliding, destabilization of interfacial waves is still seen, indicating that the quasi-static approximation to slow sliding is not valid. This is in agreement with the result of Ranjith (Int. J. Solids and Struct., 2009, 46, 3086-3092) who predicted an instability of long-wavelength Love waves in slow sliding.

Planar plane-wave matrix theory at the four loop order: integrability without BMN scaling

International Nuclear Information System (INIS)

Fischbacher, Thomas; Klose, Thomas; Plefka, Jan

2005-01-01

We study SU(N) plane-wave matrix theory up to fourth perturbative order in its large N planar limit. The effective hamiltonian in the closed su(2) subsector of the model is explicitly computed through a specially tailored computer program to perform large scale distributed symbolic algebra and generation of planar graphs. The number of graphs here was in the deep billions. The outcome of our computation establishes the four-loop integrability of the planar plane-wave matrix model. To elucidate the integrable structure we apply the recent technology of the perturbative asymptotic Bethe ansatz to our model. The resulting S-matrix turns out to be structurally similar but nevertheless distinct to the so far considered long-range spin-chain S-matrices of Inozemtsev, Beisert-Dippel-Staudacher and Arutyunov-Frolov-Staudacher in the AdS/CFT context. In particular our result displays a breakdown of BMN scaling at the four-loop order. That is, while there exists an appropriate identification of the matrix theory mass parameter with the coupling constant of the N=4 superconformal Yang-Mills theory which yields an eighth order lattice derivative for well separated impurities (naively implying BMN scaling) the detailed impurity contact interactions ruin this scaling property at the four-loop order. Moreover we study the issue of 'wrapping' interactions, which show up for the first time at this loop-order through a Konishi descendant length four operator. (author)

Quantum fields interacting with colliding plane waves: the stress-energy tensor and backreaction

International Nuclear Information System (INIS)

Dorca, M.; Verdaguer, E.

1997-01-01

Following a previous work on the quantization of a massless scalar field in a space-time representing the head on collision of two plane waves which focus into a Killing-Cauchy horizon, we compute the renormalized expectation value of the stress-energy tensor of the quantum field near that horizon in the physical state which corresponds to the Minkowski vacuum before the collision of the waves. It is found that for minimally coupled and conformally coupled scalar fields the respective stress-energy tensors are unbounded in the horizon. The specific form of the divergences suggests that when the semiclassical Einstein equations describing the backreaction of the quantum fields on the space-time geometry are taken into account, the horizon will acquire a curvature singularity. Thus the Killing-Cauchy horizon which is known to be unstable under ''generic'' classical perturbations is also unstable by vacuum polarization. The calculation is done following the point-splitting regularization technique. The dynamical colliding wave space-time has four quite distinct space-time regions, namely, one flat region, two single plane wave regions, and one interaction region. Exact mode solutions of the quantum field equation cannot be found exactly, but the blueshift suffered by the initial modes in the plane wave and interaction regions makes the use of the WKB expansion a suitable method of solution. To ensure the correct regularization of the stress-energy tensor, the initial flat modes propagated into the interaction region must be given to a rather high adiabatic order of approximation. (orig.)

Radiation of Electron in the Field of Plane Light Wave

International Nuclear Information System (INIS)

Zelinsky, A.; Drebot, I.V.; Grigorev, Yu.N.; Zvonareva, O.D.; Tatchyn, R.

2006-01-01

Results of integration of a Lorentz equation for a relativistic electron moving in the field of running, plane, linear polarized electromagnetic wave are presented in the paper. It is shown that electron velocities in the field of the wave are almost periodic functions of time. For calculations of angular spectrum of electron radiation intensity expansion of the electromagnetic field in a wave zone into generalized Fourier series was used. Expressions for the radiation intensity spectrum are presented in the paper. Derived results are illustrated for electron and laser beam parameters of NSC KIPT X-ray generator NESTOR. It is shown that for low intensity of the interacting electromagnetic wave the results of energy and angular spectrum calculations in the frame of classical electrodynamics completely coincide with calculation results produced using quantum electrodynamics. Simultaneously, derived expressions give possibilities to investigate dependence of energy and angular Compton radiation spectrum on phase of interaction and the interacting wave intensity

On plane-wave relativistic electrodynamics in plasmas and in vacuum

International Nuclear Information System (INIS)

Fiore, Gaetano

2014-01-01

We revisit the exact microscopic equations (in differential, and equivalent integral form) ruling a relativistic cold plasma after the plane-wave Ansatz, without customary approximations. We show that in the Eulerian description the motion of a very diluted plasma initially at rest and excited by an arbitrary transverse plane electromagnetic travelling-wave has a very simple and explicit dependence on the transverse electromagnetic potential; for a non-zero density plasma the above motion is a good approximation of the real one as long as the back-reaction of the charges on the electromagnetic field can be neglected, i.e. for a time lapse decreasing with the plasma density, and can be used as initial step in an iterative resolution scheme. As one of many possible applications, we use these results to describe how the ponderomotive force of a very intense and short plane laser pulse hitting normally the surface of a plasma boosts the surface electrons into the ion background. In response to this penetration, the electrons are pulled back by the electric force exerted by the ions and the other displaced electrons and may leave the plasma with high energy in the direction opposite to that of propagation of the pulse ‘slingshot effect’ (Fiore G et al 2013 arXiv:1309.1400). (paper)

Transition from regular to irregular reflection of cylindrical converging shock waves over convex obstacles

Science.gov (United States)

Vignati, F.; Guardone, A.

2017-11-01

An analytical model for the evolution of regular reflections of cylindrical converging shock waves over circular-arc obstacles is proposed. The model based on the new (local) parameter, the perceived wedge angle, which substitutes the (global) wedge angle of planar surfaces and accounts for the time-dependent curvature of both the shock and the obstacle at the reflection point, is introduced. The new model compares fairly well with numerical results. Results from numerical simulations of the regular to Mach transition—eventually occurring further downstream along the obstacle—point to the perceived wedge angle as the most significant parameter to identify regular to Mach transitions. Indeed, at the transition point, the value of the perceived wedge angle is between 39° and 42° for all investigated configurations, whereas, e.g., the absolute local wedge angle varies in between 10° and 45° in the same conditions.

A ''quadratized'' augmented plane wave method

International Nuclear Information System (INIS)

Smrcka, L.

1982-02-01

The exact radial solution inside the muffin-tin sphere is replaced by its Taylor expansion with respect to the energy, truncated after the quadratic term. Making use of it the energy independent augmented plane waves are formed which lead to the secular equations linear in energy. The method resembles the currently used linearized APW method but yields higher accuracy. The analysis of solution inside one muffin-tin sphere shows that the eigenvalue error is proportional to (E-E 0 ) 6 as compared with (E-E 0 ) 4 for LAPW. The error of eigenfunctions is (E-E 0 ) 3 ((E-E 0 ) 2 for LAPW). These conclusions are confirmed by direct numerical calculation of band structure of Cu and Al. (author)

A numerical method for determining the radial wave motion correction in plane wave couplers

DEFF Research Database (Denmark)

Cutanda Henriquez, Vicente; Barrera Figueroa, Salvador; Torras Rosell, Antoni

2016-01-01

Microphones are used for realising the unit of sound pressure level, the pascal (Pa). Electro-acoustic reciprocity is the preferred method for the absolute determination of the sensitivity. This method can be applied in different sound fields: uniform pressure, free field or diffuse field. Pressure...... solution is an analytical expression that estimates the difference between the ideal plane wave sound field and a more complex lossless sound field created by a non-planar movement of the microphone’s membranes. Alternatively, a correction may be calculated numerically by introducing a full model...... of the microphone-coupler system in a Boundary Element formulation. In order to obtain a realistic representation of the sound field, viscous losses must be introduced in the model. This paper presents such a model, and the results of the simulations for different combinations of microphones and couplers...

Back radiation suppression through a semi-transparent round ground plane for a mm-Wave monopole antenna

KAUST Repository

Klionovski, Kirill; Farooqui, Muhammad Fahad; Shamim, Atif

2017-01-01

Omnidirectional radiation pattern with minimum backward radiation is highly desirable for millimeter-wave telecommunication antennas. In this work, we propose a round, semitransparent ground plane of radius 0.8λ with uniform impedance distribution that can reduce the back radiation of a monopole antenna by 8.8 dB as compared with a similar sized metallic ground plane. The value of uniform impedance is obtained through analytical optimization by using asymptotic expressions in the Kirchhoff approximation of the radiation pattern of a toroidal wave scattered by a round semitransparent ground plane. The semitransparent ground plane has been realized using a low-cost carbon paste on a Kapton film. Experimental results match closely with those of simulations and validate the overall concept.

Back radiation suppression through a semi-transparent round ground plane for a mm-Wave monopole antenna

KAUST Repository

Klionovski, Kirill

2017-10-25

Omnidirectional radiation pattern with minimum backward radiation is highly desirable for millimeter-wave telecommunication antennas. In this work, we propose a round, semitransparent ground plane of radius 0.8λ with uniform impedance distribution that can reduce the back radiation of a monopole antenna by 8.8 dB as compared with a similar sized metallic ground plane. The value of uniform impedance is obtained through analytical optimization by using asymptotic expressions in the Kirchhoff approximation of the radiation pattern of a toroidal wave scattered by a round semitransparent ground plane. The semitransparent ground plane has been realized using a low-cost carbon paste on a Kapton film. Experimental results match closely with those of simulations and validate the overall concept.

Propagation of magnetostatic spin waves in an yttrium iron garnet film for out-of-plane magnetic fields

Science.gov (United States)

Bang, Wonbae; Lim, Jinho; Trossman, Jonathan; Tsai, C. C.; Ketterson, John B.

2018-06-01

We have observed the propagation of spin waves across a thin yttrium iron garnet film on (1 1 1) gadolinium gallium garnet for magnetic fields inclined with respect to the film plane. Two principle planes were studied: that for H in the plane defined by the wave vector k and the plane normal, n, with limiting forms corresponding to the Backward Volume and Forward Volume modes, and that for H in the plane perpendicular to k, with limiting forms corresponding to the Damon-Eshbach and Forward Volume modes. By exciting the wave at one edge of the film and observing the field dependence of the phase of the received signal at the opposing edge we determined the frequency vs. wavevector relation, ω = ω (k), of various propagating modes in the film. Avoided crossings are observed in the Damon-Eshbach and Forward Volume regimes when the propagating mode intersects the higher, exchange split, volume modes, leading to an extinction of the propagating mode; analysis of the resulting behavior allows a determination of the exchange parameter. The experimental results are compared with theoretical simulations.

Plane wave fast color flow mode imaging

DEFF Research Database (Denmark)

Bolic, Ibrahim; Udesen, Jesper; Gran, Fredrik

2006-01-01

A new Plane wave fast color flow imaging method (PWM) has been investigated, and performance evaluation of the PWM based on experimental measurements has been made. The results show that it is possible to obtain a CFM image using only 8 echo-pulse emissions for beam to flow angles between 45...... degrees and 75 degrees. Compared to the conventional ultrasound imaging the frame rate is similar to 30 - 60 times higher. The bias, B-est of the velocity profile estimate, based on 8 pulse-echo emissions, is between 3.3% and 6.1% for beam to flow angles between 45 degrees and 75 degrees, and the standard...

Scattering theory of walking droplets in the presence of obstacles

International Nuclear Information System (INIS)

Dubertrand, Rémy; Hubert, Maxime; Schlagheck, Peter; Vandewalle, Nicolas; Bastin, Thierry; Martin, John

2016-01-01

We aim to describe a droplet bouncing on a vibrating bath using a simple and highly versatile model inspired from quantum mechanics. Close to the Faraday instability, a long-lived surface wave is created at each bounce, which serves as a pilot wave for the droplet. This leads to so called walking droplets or walkers. Since the seminal experiment by Couder et al (2006 Phys. Rev. Lett. 97 154101) there have been many attempts to accurately reproduce the experimental results.We propose to describe the trajectories of a walker using a Green function approach. The Green function is related to the Helmholtz equation with Neumann boundary conditions on the obstacle(s) and outgoing boundary conditions at infinity. For a single-slit geometry our model is exactly solvable and reproduces some general features observed experimentally. It stands for a promising candidate to account for the presence of arbitrary boundaries in the walker’s dynamics. (paper)

Semipolar MOVPE AlGaN on (10 anti 10) m-plane sapphire; MOVPE von semipolarem AlGaN auf (10 anti 10) m-plane Saphir

Energy Technology Data Exchange (ETDEWEB)

Mehnke, Frank; Stellmach, Joachim; Frentrup, Martin; Kusch, Gunnar; Wernicke, Tim; Pristovsek, Markus; Kneissl, Michael [Technische Universitaet Berlin, Institut fuer Festkoerperphysik, Hardenbergstr. 36, 10623 Berlin (Germany)

2011-07-01

The energy gap of AlGaN varies between 3.4 eV and 6.2 eV and allows light emitting diodes (LED) in the ultraviolet spectral region. The authors studied semipolar (11 anti 22) AlGaN layers that were deposited on (10 anti 10) m-plane sapphire using MOVPE (metalorganic vapor phase epitaxy) without nucleation layer with a substrate temperature below 1100 C in H2 atmosphere. The layers are preferably (11 anti 22) oriented. The sample show a surface roughness between 15 and 2 nm. The Al content of the smoothest samples is about 60% determined by transmission experiments. Below 60% Al content a triangular morphology was observed, the opening angle increased with decreasing Al content. The absorption edge was 0.05 eV (GaN) to 0.35 eV (AlN) below the band edge of (0001) oriented AlGaN layers. Further investigations of semipolar AlGaN layers to study the applicability for UV LEDs are under preparation.

Japan’s Rearmament Dilemma: Obstacles to Rearmament.

Science.gov (United States)

1980-01-01

aircraft carrier Enterprise, and the problems with the first Japanese nuclear -powered ship , the Mutsu , have continued to keep the issue of nuclear weapons...4 Formation of the Psychology. .. ............... 4 Nuclear Allergy .. .................... 7 Self-Defense Force .. ................... 10 ARTICLE 9... nuclear weapons, would elicit a strong reaction from the U.S. This specter of the U.S. reaction is another obstacle to rearmament. While most scholars

Path Generation by Avoiding Obstacles using the Intersection of Bodies

Directory of Open Access Journals (Sweden)

Komák Martin

2018-02-01

Full Text Available We will discuss the problem of path finding in 3D space with an obstacle. The thesis deals with the problem of searching for the shortest path between the individual points in the space so that this path does not come into collision with an obstacle. A system has been designed to construct paths in cross-sectional planes of the given object representing an obstacle, based on its surface contour. The system solves the issue of loading STL format, creating cross-sectional planes of the object, intersection between geometric shapes, and generation of lines around the contour of the object in 2D. An experiment was performed, in which we have been moving around a model of a jet aircraft and its results are described in the conclusion.

Localized orbitals vs. pseudopotential-plane waves basis sets: performances and accuracy for molecular magnetic systems

CERN Document Server

Massobrio, C

2003-01-01

Density functional theory, in combination with a) a careful choice of the exchange-correlation part of the total energy and b) localized basis sets for the electronic orbital, has become the method of choice for calculating the exchange-couplings in magnetic molecular complexes. Orbital expansion on plane waves can be seen as an alternative basis set especially suited to allow optimization of newly synthesized materials of unknown geometries. However, little is known on the predictive power of this scheme to yield quantitative values for exchange coupling constants J as small as a few hundredths of eV (50-300 cm sup - sup 1). We have used density functional theory and a plane waves basis set to calculate the exchange couplings J of three homodinuclear Cu-based molecular complexes with experimental values ranging from +40 cm sup - sup 1 to -300 cm sup - sup 1. The plane waves basis set proves as accurate as the localized basis set, thereby suggesting that this approach can be reliably employed to predict and r...

Localized orbitals vs. pseudopotential-plane waves basis sets: performances and accuracy for molecular magnetic systems

International Nuclear Information System (INIS)

Massobrio, C.; Ruiz, E.

2003-01-01

Density functional theory, in combination with a) a careful choice of the exchange-correlation part of the total energy and b) localized basis sets for the electronic orbital, has become the method of choice for calculating the exchange-couplings in magnetic molecular complexes. Orbital expansion on plane waves can be seen as an alternative basis set especially suited to allow optimization of newly synthesized materials of unknown geometries. However, little is known on the predictive power of this scheme to yield quantitative values for exchange coupling constants J as small as a few hundredths of eV (50-300 cm -1 ). We have used density functional theory and a plane waves basis set to calculate the exchange couplings J of three homodinuclear Cu-based molecular complexes with experimental values ranging from +40 cm -1 to -300 cm -1 . The plane waves basis set proves as accurate as the localized basis set, thereby suggesting that this approach can be reliably employed to predict and rationalize the magnetic properties of molecular-based materials. (author)

Proposal of coherent Cherenkov radiation matched to circular plane wave for intense terahertz light source

International Nuclear Information System (INIS)

Sei, Norihiro; Sakai, Takeshi; Hayakawa, Ken; Tanaka, Toshinari; Hayakawa, Yasushi; Nakao, Keisuke; Nogami, Kyoko; Inagaki, Manabu

2015-01-01

Highlights: • We proposed a new intense terahertz-wave source based on coherent Cherenkov radiation (CCR). • A hollow conical dielectric is used to generate the CCR beam. • The wave front of the CCR beam can be matched to the basal plane. • The peak-power of the CCR beam is above 1 MW per micropulse with a short interval of 350 ps. - Abstract: We propose a high-peak-power terahertz-wave source based on an electron accelerator. By passing an electron beam through a hollow conical dielectric with apex facing the incident electron beam, the wave front of coherent Cherenkov radiation generated on the inner surface of the hollow conical dielectric matches the basal plane. Using the electron beam generated at the Laboratory for Electron Beam Research and Application at Nihon University, the calculated power of coherent Cherenkov radiation that matched the circular plane (CCR-MCP) was above 1 MW per micropulse with a short interval of 350 ps, for wavelengths ranging from 0.5 to 5 mm. The electron beam is not lost for generating the CCR-MCP beam by using the hollow conical dielectric. It is possible to combine the CCR-MCP beams with other light sources based on an accelerator

Plane-wave scattering by self-complementary metasurfaces in terms of electromagnetic duality and Babinet's principle

Science.gov (United States)

Nakata, Yosuke; Urade, Yoshiro; Nakanishi, Toshihiro; Kitano, Masao

2013-11-01

We investigate theoretically electromagnetic plane-wave scattering by self-complementary metasurfaces. By using Babinet's principle extended to metasurfaces with resistive elements, we show that the frequency-independent transmission and reflection are realized for normal incidence of a circularly polarized plane wave onto a self-complementary metasurface, even if there is diffraction. Next, we consider two special classes of self-complementary metasurfaces. We show that self-complementary metasurfaces with rotational symmetry can act as coherent perfect absorbers, and those with translational symmetry compatible with their self-complementarity can split the incident power equally, even for oblique incidences.

Propagation of plane waves at the interface of an elastic solid half-space and a microstretch thermoelastic diffusion solid half-space

Directory of Open Access Journals (Sweden)

Rajneesh Kumar

Full Text Available The problem of reflection and refraction phenomenon due to plane waves incident obliquely at a plane interface between uniform elastic solid half-space and microstretch thermoelastic diffusion solid half-space has been studied. It is found that the amplitude ratios of various reflected and refracted waves are functions of angle of incidence, frequency of incident wave and are influenced by the microstretch thermoelastic diffusion properties of the media. The expressions of amplitude ratios and energy ratios are obtained in closed form. The energy ratios have been computed numerically for a particular model. The variations of energy ratios with angle of incidence are shown for thermoelastic diffusion media in the context of Lord-Shulman (L-S (1967 and Green-Lindsay (G-L (1972 theories. The conservation of energy at the interface is verified. Some particular cases are also deduced from the present investigation.

[A new method to orthodontically correct dental occlusal plane canting: wave-shaped arch].

Science.gov (United States)

Zheng, X; Hu, X X; Ma, N; Chen, X H

2017-02-18

To introduce a technique of second order wave-shaped arch wire to orthodontically treat dental occlusal plane canting (DOPC) with left-right interactive anchorage, and to test its clinical efficacy. Among the permanent dentition malocclusion patients who showed no obvious facial asymmetry, we screened for patients who showed anterior occlusal plane canting (AOPC) after routine orthodontic examination, treatment planning, MBT fixed appliance installation and serial arch wires alignment. Each patient had been clinically appraised in frontal view by 2 orthodontists and the patient him/herself; if all 3 agreed that the AOPC was obvious, the patient was included. By this means, we included 37 patients, including 10 males and 27 females; the average age was (21.9±5.2) years. To correct AOPC, opposite direction equal curvature second order rocking-chair curve was bent on each side of 0.46 mm×0.56 mm stainless steel edgewise wire. With reference to normal occlusal plane, a curve toward the occlusal surface was made to extrude under-erupted teeth on one side while a curve toward the gingiva was made to intrude over-erupted teeth on the other side, so that the arch wire was made into a wave shape in vertical dimension. Before and after application of wave-shaped arch wire, frontal facial photographs were taken when the patient's mouth was open slightly with lips retracted to show anterior occlusal plane (AOP) clearly. An AOP was constructed by connecting the center of the slot in the medial edge of canine bracket on each side in the photograph. The angles between the bipupillary plane(BPP) and the constructed AOP were measured in ImageJ1-48v software and the angle differences before and after treatment were compared with paired Wilcoxon test in SPSS 10.0 software. The wave-shaped arch could correct AOPC effectively in 3 to 10 months time with an average of 5.5±1.7 months; the angles between AOP and BBP before treatment ranged from 2.90° to 6.12° with a median of 4.01�

ONETEP: linear-scaling density-functional theory with plane-waves

International Nuclear Information System (INIS)

Haynes, P D; Mostof, A A; Skylaris, C-K; Payne, M C

2006-01-01

This paper provides a general overview of the methodology implemented in onetep (Order-N Electronic Total Energy Package), a parallel density-functional theory code for largescale first-principles quantum-mechanical calculations. The distinctive features of onetep are linear-scaling in both computational effort and resources, obtained by making well-controlled approximations which enable simulations to be performed with plane-wave accuracy. Titanium dioxide clusters of increasing size designed to mimic surfaces are studied to demonstrate the accuracy and scaling of onetep

An extended Fourier modal method for plane-wave scattering from finite structures

NARCIS (Netherlands)

Pisarenco, M.; Maubach, J.M.L.; Setija, I.D.; Mattheij, R.M.M.

2010-01-01

This paper extends the area of application of the Fourier modal method from periodic structures to aperiodic ones, in particular for plane-wave illumination at arbitrary angles. This is achieved by placing perfectly matched layers at the lateral sides of the computational domain and reformulating

Formation of whispering gallery modes by scattering of an electromagnetic plane wave by two cylinders

Energy Technology Data Exchange (ETDEWEB)

Abramov, Arnold, E-mail: qulaser@gmail.com [Kuang-Chi Institute of Advanced Technology, Shenzhen, 518057 (China); Kostikov, Alexander [Donbass State Engineering Academy, 84303, Kramatorsk, Donetsk (Ukraine)

2017-03-26

We report the effect of scattering of electromagnetic plane waves by two cylinders on whispering gallery mode (WGM) formation in a cylinder. WGM can occur because of the presence of additional cylinder scatterers at specific location, while WGMs can only form in a single cylinder for specific cylinder radius and/or wavelength values, the matching accuracy required would be much greater than that required in our model for the additional cylinders locations. Analysis of the general solution to the problem showed that the effect can be explained by the interference of waves scattered by additional cylinders and incident on the main cylinder. - Highlights: • We consider scattering of electromagnetic plane waves by two cylinders. • WGMs occur because of the presence of additional cylinder at specific location. • The accuracy for the locations is much less than required for specific values of single cylinder. • The interference of waves scattered by additional cylinders and incident on the main is responsible for the effect.

Nanoscale measurement of Nernst effect in two-dimensional charge density wave material 1T-TaS2

Science.gov (United States)

Wu, Stephen M.; Luican-Mayer, Adina; Bhattacharya, Anand

2017-11-01

Advances in nanoscale material characterization on two-dimensional van der Waals layered materials primarily involve their optical and electronic properties. The thermal properties of these materials are harder to access due to the difficulty of thermal measurements at the nanoscale. In this work, we create a nanoscale magnetothermal device platform to access the basic out-of-plane magnetothermal transport properties of ultrathin van der Waals materials. Specifically, the Nernst effect in the charge density wave transition metal dichalcogenide 1T-TaS2 is examined on nano-thin flakes in a patterned device structure. It is revealed that near the commensurate charge density wave (CCDW) to nearly commensurate charge density wave (NCCDW) phase transition, the polarity of the Nernst effect changes. Since the Nernst effect is especially sensitive to changes in the Fermi surface, this suggests that large changes are occurring in the out-of-plane electronic structure of 1T-TaS2, which are otherwise unresolved in just in-plane electronic transport measurements. This may signal a coherent evolution of out-of-plane stacking in the CCDW → NCCDW transition.

Plane shock wave studies of geologic media

International Nuclear Information System (INIS)

Anderson, G.D.; Larson, D.B.

1977-01-01

Plane shock wave experiments have been conducted on eight geologic materials in an effort to determine the importance of time-dependent mechanical behavior. Of the eight rocks studied, only Westerly granite and nugget sandstone appear to show time independence. In the slightly porous materials (1-5 percent), Blair dolomite and sodium chloride, and in the highly porous (15 to 40 percent) rock, Mt. Helen tuff and Indiana limestone, time-dependent behavior is associated with the time required to close the available porosity. In water-saturated rocks the time dependence arises because the water that is present shows no indication of transformation to the higher pressure ice phases, thus suggesting the possibility that a metastable form of water exists under dynamic conditions

The influence of air-filled structures on wave propagation and beam formation of a pygmy sperm whale (Kogia breviceps) in horizontal and vertical planes.

Science.gov (United States)

Song, Zhongchang; Zhang, Yu; Thornton, Steven W; Li, Songhai; Dong, Jianchen

2017-10-01

The wave propagation, sound field, and transmission beam pattern of a pygmy sperm whale (Kogia breviceps) were investigated in both the horizontal and vertical planes. Results suggested that the signals obtained at both planes were similarly characterized with a high peak frequency and a relatively narrow bandwidth, close to the ones recorded from live animals. The sound beam measured outside the head in the vertical plane was narrower than that of the horizontal one. Cases with different combinations of air-filled structures in both planes were used to study the respective roles in controlling wave propagation and beam formation. The wave propagations and beam patterns in the horizontal and vertical planes elucidated the important reflection effect of the spermaceti and vocal chambers on sound waves, which was highly significant in forming intensive forward sound beams. The air-filled structures, the forehead soft tissues and skull structures formed wave guides in these two planes for emitted sounds to propagate forward.

Acoustic backscattering and radiation force on a rigid elliptical cylinder in plane progressive waves.

Science.gov (United States)

Mitri, F G

2016-03-01

This work proposes a formal analytical theory using the partial-wave series expansion (PWSE) method in cylindrical coordinates, to calculate the acoustic backscattering form function as well as the radiation force-per-length on an infinitely long elliptical (non-circular) cylinder in plane progressive waves. The major (or minor) semi-axis of the ellipse coincides with the direction of the incident waves. The scattering coefficients for the rigid elliptical cylinder are determined by imposing the Neumann boundary condition for an immovable surface and solving a resulting system of linear equations by matrix inversion. The present method, which utilizes standard cylindrical (Bessel and Hankel) wave functions, presents an advantage over the solution for the scattering that is ordinarily expressed in a basis of elliptical Mathieu functions (which are generally non-orthogonal). Furthermore, an integral equation showing the direct connection of the radiation force function with the square of the scattering form function in the far-field from the scatterer (applicable for plane waves only), is noted and discussed. An important application of this integral equation is the adequate evaluation of the radiation force function from a bistatic measurement (i.e., in the polar plane) of the far-field scattering from any 2D object of arbitrary shape. Numerical predictions are evaluated for the acoustic backscattering form function and the radiation force function, which is the radiation force per unit length, per characteristic energy density, and per unit cross-sectional surface of the ellipse, with particular emphasis on the aspect ratio a/b, where a and b are the semi-axes, as well as the dimensionless size parameter kb, without the restriction to a particular range of frequencies. The results are particularly relevant in acoustic levitation, acousto-fluidics and particle dynamics applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantum mechanics of lattice gas automata: One-particle plane waves and potentials

International Nuclear Information System (INIS)

Meyer, D.A.

1997-01-01

Classical lattice gas automata effectively simulate physical processes, such as diffusion and fluid flow (in certain parameter regimes), despite their simplicity at the microscale. Motivated by current interest in quantum computation we recently defined quantum lattice gas automata; in this paper we initiate a project to analyze which physical processes these models can effectively simulate. Studying the single particle sector of a one-dimensional quantum lattice gas we find discrete analogs of plane waves and wave packets, and then investigate their behavior in the presence of inhomogeneous potentials. copyright 1997 The American Physical Society

On the energy-momentum density of gravitational plane waves

International Nuclear Information System (INIS)

Dereli, T; Tucker, R W

2004-01-01

By embedding Einstein's original formulation of general relativity into a broader context, we show that a dynamic covariant description of gravitational stress-energy emerges naturally from a variational principle. A tensor T G is constructed from a contraction of the Bel tensor with a symmetric covariant second degree tensor field Φ and has a form analogous to the stress-energy tensor of the Maxwell field in an arbitrary spacetime. For plane-fronted gravitational waves helicity-2 polarized (graviton) states can be identified carrying non-zero energy and momentum

Stability of the Superconducting d-Wave Pairing Toward the Intersite Coulomb Repulsion in CuO_2 Plane

Science.gov (United States)

Val'kov, V. V.; Dzebisashvili, D. M.; Korovushkin, M. M.; Barabanov, A. F.

2018-06-01

Taking into account the real crystalline structure of the CuO_2 plane and the strong spin-fermion coupling, we study the influence of the intersite Coulomb repulsion between holes on the Cooper instability of the spin-polaron quasiparticles in cuprate superconductors. The analysis shows that only the superconducting d-wave pairing is implemented in the whole region of doping, whereas the solutions of the self-consistent equations for the s-wave pairing are absent. It is shown that intersite Coulomb interaction V_1 between the holes located at the nearest oxygen ions does not affect the d-wave pairing, because its Fourier transform V_q vanishes in the kernel of the corresponding integral equation. The intersite Coulomb interaction V_2 of quasiparticles located at the next-nearest oxygen ions does not vanish in the integral equations, however, but it is also shown that the d-wave pairing is robust toward this interaction for physically reasonable values of V_2.

Triple differential cross-sections of Ne (2s2) in coplanar to perpendicular plane geometry

Science.gov (United States)

Chen, L. Q.; Khajuria, Y.; Chen, X. J.; Xu, K. Z.

2003-10-01

The distorted wave Born approximation (DWBA) with the spin averaged static exchange potential has been used to calculate the triple differential cross-sections (TDCSs) for Ne (2s^2) ionization by electron impact in coplanar to perpendicular plane symmetric geometry at 110.5 eV incident electron energy. The present theoretical results at gun angles Psi = 0^circ (coplanar symmetric geometry) and Psi = 90^circ (perpendicular plane geometry) are in satisfactory agreement with the available experimental data. A deep interference minimum appears in the TDCS in the coplanar symmetric geometry and a strong peak at scattering angle xi = 90^circ caused by the single collision mechanism has been observed in the perpendicular plane geometry. The TDCSs at the gun angles Psi = 30^circ, and Psi = 60^circ are predicted.

On completeness and orthogonality of solutions of relativistic wave equations on zero plane

International Nuclear Information System (INIS)

Gitman, D.M.; Shakhmatov, V.M.; Shvartsman, Sh.M.

1975-01-01

The work considers the possible redeterminations of the scalar product for the relativistic wave fields, such as the Klein-Gordon and Dirac ones. It has been shown that a whole class of new exact solutions, for which the usual scalar product on the plane x 0 =const. could not be previously determinated, allows a correct scalar product on the zero plane x 0 -x 3 =const. The relations of orthogonality and completeness with respect to the above scalar product have been proved. Possible applications of the obtained results are discussed

Back Radiation Suppression through a Semitransparent Ground Plane for a mm-Wave Patch Antenna

KAUST Repository

Klionovski, Kirill

2017-06-21

Omnidirectional radiation pattern with minimum backward radiation is highly desirable for base station antennas to minimize the multipath effects. Semitransparent ground planes have been used to reduce the backward radiation, but mostly with complicated non-uniform impedance distribution. In this work, we propose, for the first time, a round semitransparent ground plane of radius 0.8 λ with uniform impedance distribution that can improve the front-to-back ratio of a wideband patch antenna by 11.6 dB as compared to a similar sized metallic ground plane. The value of uniform impedance is obtained through analytical optimization by using asymptotic expressions in the Kirchhoff approximation of the radiation pattern of a toroidal wave scattered by a round semitransparent ground plane. The semitransparent ground plane has been realized using a low-cost carbon paste on a Kapton film. Experimental results match closely with those of simulations and validate the overall concept.

A wavenumber approach to analysing the active control of plane waves with arrays of secondary sources

Science.gov (United States)

Elliott, Stephen J.; Cheer, Jordan; Bhan, Lam; Shi, Chuang; Gan, Woon-Seng

2018-04-01

The active control of an incident sound field with an array of secondary sources is a fundamental problem in active control. In this paper the optimal performance of an infinite array of secondary sources in controlling a plane incident sound wave is first considered in free space. An analytic solution for normal incidence plane waves is presented, indicating a clear cut-off frequency for good performance, when the separation distance between the uniformly-spaced sources is equal to a wavelength. The extent of the near field pressure close to the source array is also quantified, since this determines the positions of the error microphones in a practical arrangement. The theory is also extended to oblique incident waves. This result is then compared with numerical simulations of controlling the sound power radiated through an open aperture in a rigid wall, subject to an incident plane wave, using an array of secondary sources in the aperture. In this case the diffraction through the aperture becomes important when its size is compatible with the acoustic wavelength, in which case only a few sources are necessary for good control. When the size of the aperture is large compared to the wavelength, and diffraction is less important but more secondary sources need to be used for good control, the results then become similar to those for the free field problem with an infinite source array.

Observation of proton chorus waves close to the equatorial plane by Cluster

Science.gov (United States)

Grison, B.; Pickett, J. S.; Santolik, O.; Robert, P.; Cornilleau-Wehrlin, N.; Engebretson, M. J.; Constantinescu, D. O.

2009-12-01

Whistler mode chorus waves are a widely studied phenomena. They are present in numerous regions of the magnetosphere and are presumed to originate in the magnetic equatorial region. In a spectrogram they are characterized by narrowband features with rise (or fall) in frequency over short periods of time. Being whistler mode waves around a few tenths of the electron cyclotron frequency they interact mainly with electrons. In the present study we report observations by the Cluster spacecraft of what we call proton chorus waves. They have spectral features with rising frequency, similar to the electron chorus waves, but they are detected in a frequency range that starts roughly at 0.50fH+ up to fH+ (the local proton gyro-frequency). The lower part of their spectrum seems to originate from monochromatic Pc 1 waves (1.5 Hz). Proton chorus waves are detected close to the magnetic equatorial plane in both hemispheres during the same event. Our interpretation of these waves as proton chorus is supported by polarization analysis with the Roproc procedures and the Prassadco software using both the magnetic (STAFF-SC) and electric (EFW) parts of the fluctuations spectrum.

Solution of the Bethe-Salpeter equation in the field of a plane electromagnetic wave

International Nuclear Information System (INIS)

Starostin, V.S.

1988-01-01

A solution is obtained of the Bethe--Salpeter equation for positronium in the field of linearly and circularly polarized plane electromagnetic waves at frequencies much higher than atomic. It is not assumed that the field is weak

Initial value problem for colliding gravitational plane waves. III

International Nuclear Information System (INIS)

Hauser, I.; Ernst, F.J.

1990-01-01

The development of a homogeneous Hilbert problem (HHP) approach to the initial value problem (IVP) for colliding gravitational plane waves with noncollinear polarization that began in two earlier papers [I. Hauser and F. J. Ernst, J. Math. Phys. 30, 872 (1989) and 30, 2322 (1989)] is continued. After formulating the HHP, the description of how one can apply it to generate a new family of solutions of the colliding wave problem that generalizes a three-parameter family constructed by Ernst, Garcia, and Hauser [J. Math. Phys. 29, 681 (1988)] using a double-Harrison transformation is given. Then the proof that the solution of the new HHP indeed solves the IVP that is posed is presented. A matrix Fredholm equation of the second kind that is equivalent to the HHP is also deduced. This will be used in a sequel to complete the proof of existence of solutions of the HHP and the proof that certain assumed differentiability hypotheses are in fact valid

Path integral for spinning particle in the plane wave field: Global and local projections

International Nuclear Information System (INIS)

Boudiaf, N.; Boudjedaa, T.; Chetouani, L.

2001-01-01

The Green function related to the problem of a Dirac particle interacting with a plane wave is calculated via the path integral formalism proposed recently by Alexandrou et al. according to the two so-called global and local projections. With the help of the incorporation of two simple identities, it is shown that the contribution to the calculation of the integrals comes essentially from classical solutions projected along the direction of wave propagation. (orig.)

Computational dosimetry in embryos exposed to electromagnetic plane waves over the frequency range of 10 MHz-1.5 GHz

International Nuclear Information System (INIS)

Kawai, Hiroki; Nagaoka, Tomoaki; Watanabe, Soichi; Saito, Kazuyuki; Takahashi, Masaharu; Ito, Koichi

2010-01-01

This paper presents calculated specific absorption rate (SAR) dosimetry in 4 and 8 week Japanese pregnant-woman models exposed to plane waves over the frequency range of 10 MHz-1.5 GHz. Two types of 2 mm spatial-resolution pregnant-woman models comprised a woman model, which is similar to the average-sized Japanese adult female in height and weight, with a cubic (4 week) embryo or spheroidal (8 week) one. The averaged SAR in the embryos exposed to vertically and horizontally polarized plane waves at four kinds of propagation directions are calculated from 10 MHz to 1.5 GHz. The results indicate that the maximum average SAR in the embryos exposed to plane waves is lower than 0.08 W kg -1 when the incident power density is at the reference level of ICNIRP guideline for general public environment. (note)

Diffraction of an inhomogeneous plane wave by an impedance wedge in a lossy medium

CSIR Research Space (South Africa)

Manara, G

1998-11-01

Full Text Available The diffraction of an inhomogeneous plane wave by an impedance wedge embedded in a lossy medium is analyzed. The rigorous integral representation for the field is asymptotically evaluated in the context of the uniform geometrical theory...

Stability of plane wave solutions of the two-space-dimensional nonlinear Schroedinger equation

International Nuclear Information System (INIS)

Martin, D.U.; Yuen, H.C.; Saffman, P.G.

1980-01-01

The stability of plane, periodic solutions of the two-dimensional nonlinear Schroedinger equation to infinitesimal, two-dimensional perturbation has been calculated and verified numerically. For standing wave disturbances, instability is found for both odd and even modes; as the period of the unperturbed solution increases, the instability associated with the odd modes remains but that associated with the even mode disappears, which is consistent with the results of Zakharov and Rubenchik, Saffman and Yuen and Ablowitz and Segur on the stability of solitons. In addition, we have identified travelling wave instabilities for the even mode perturbations which are absent in the long-wave limit. Extrapolation to the case of an unperturbed solution with infinite period suggests that these instabilities may also be present for the soliton. In other words, the soliton is unstable to odd, standing-wave perturbations, and very likely also to even, travelling-wave perturbations. (orig.)

Optimization of exit-plane waves restored from HRTEM through-focal series

International Nuclear Information System (INIS)

Erni, Rolf; Rossell, Marta D.; Nakashima, Philip N.H.

2010-01-01

Atomic-resolution transmission electron microscopy has largely benefited from the implementation of aberration correctors in the imaging part of the microscope. Though the dominant geometrical axial aberrations can in principle be corrected or suitably adjusted, the impact of higher-order aberrations, which are mainly due to the implementation of non-round electron optical elements, on the imaging process remains unclear. Based on a semi-empirical criterion, we analyze the impact of residual aperture aberrations on the quality of exit-plane waves that are retrieved from through-focal series recorded using an aberration-corrected and monochromated instrument which was operated at 300 kV and enabled for an information transfer of ∼0.05 nm. We show that the impact of some of the higher-order aberrations in retrieved exit-plane waves can be balanced by a suitable adjustment of symmetry equivalent lower-order aberrations. We find that proper compensation and correction of 1st and 2nd order aberrations is critical, and that the required accuracy is difficult to achieve. This results in an apparent insensitivity towards residual higher-order aberrations. We also investigate the influence of the detector characteristics on the image contrast. We find that correction for the modulation transfer function results in a contrast gain of up to 40%.

Improved Plane-Wave Ultrasound Beamforming by Incorporating Angular Weighting and Coherent Compounding in Fourier Domain.

Science.gov (United States)

Chen, Chuan; Hendriks, Gijs A G M; van Sloun, Ruud J G; Hansen, Hendrik H G; de Korte, Chris L

2018-05-01

In this paper, a novel processing framework is introduced for Fourier-domain beamforming of plane-wave ultrasound data, which incorporates coherent compounding and angular weighting in the Fourier domain. Angular weighting implies spectral weighting by a 2-D steering-angle-dependent filtering template. The design of this filter is also optimized as part of this paper. Two widely used Fourier-domain plane-wave ultrasound beamforming methods, i.e., Lu's f-k and Stolt's f-k methods, were integrated in the framework. To enable coherent compounding in Fourier domain for the Stolt's f-k method, the original Stolt's f-k method was modified to achieve alignment of the spectra for different steering angles in k-space. The performance of the framework was compared for both methods with and without angular weighting using experimentally obtained data sets (phantom and in vivo), and data sets (phantom) provided by the IEEE IUS 2016 plane-wave beamforming challenge. The addition of angular weighting enhanced the image contrast while preserving image resolution. This resulted in images of equal quality as those obtained by conventionally used delay-and-sum (DAS) beamforming with apodization and coherent compounding. Given the lower computational load of the proposed framework compared to DAS, to our knowledge it can, therefore, be concluded that it outperforms commonly used beamforming methods such as Stolt's f-k, Lu's f-k, and DAS.

Worldline path integrals for a Dirac particle in a weak gravitational plane wave

International Nuclear Information System (INIS)

Haouat, S.; Chetouani, L.

2008-01-01

The problem of a relativistic spinning particle interacting with a weak gravitational plane wave in (3+1) dimensions is formulated in the frame work of covariant supersymmetric path integrals. The relative Green function is expressed through a functional integral over bosonic trajectories that describe the external motion and fermionic variables that describe the spin degrees of freedom. The (3+1) dimensional problem is reduced to the (1+1) dimensional one by using an identity. Next, the relative propagator is exactly calculated and the wave functions are extracted. (orig.)

A standing wave linear ultrasonic motor operating in in-plane expanding and bending modes.

Science.gov (United States)

Chen, Zhijiang; Li, Xiaotian; Ci, Penghong; Liu, Guoxi; Dong, Shuxiang

2015-03-01

A novel standing wave linear ultrasonic motor operating in in-plane expanding and bending modes was proposed in this study. The stator (or actuator) of the linear motor was made of a simple single Lead Zirconate Titanate (PZT) ceramic square plate (15 × 15 × 2 mm(3)) with a circular hole (D = 6.7 mm) in the center. The geometric parameters of the stator were computed with the finite element analysis to produce in-plane bi-mode standing wave vibration. The calculated results predicted that a driving tip attached at midpoint of one edge of the stator can produce two orthogonal, approximate straight-line trajectories, which can be used to move a slider in linear motion via frictional forces in forward or reverse direction. The investigations showed that the proposed linear motor can produce a six times higher power density than that of a previously reported square plate motor.

Density fitting for derivatives of Coulomb integrals in ab initio calculations using mixed Gaussian and plane-wave basis

Czech Academy of Sciences Publication Activity Database

Čársky, Petr

2009-01-01

Roč. 109, č. 620 (2009), s. 1237-1242 ISSN 0020-7608 R&D Projects: GA ČR GA203/07/0070; GA ČR GA202/08/0631; GA AV ČR 1ET400400413; GA AV ČR IAA100400501 Institutional research plan: CEZ:AV0Z40400503 Keywords : Derivatives of Coulomb integrals * mixed Gaussian and plane-wave basis sets * electron scattering * computer time saving Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.315, year: 2009

Multiple projection optical diffusion tomography with plane wave illumination

International Nuclear Information System (INIS)

Markel, Vadim A; Schotland, John C

2005-01-01

We describe a new data collection scheme for optical diffusion tomography in which plane wave illumination is combined with multiple projections in the slab imaging geometry. Multiple projection measurements are performed by rotating the slab around the sample. The advantage of the proposed method is that the measured data are more compatible with the dynamic range of most commonly used detectors. At the same time, multiple projections improve image quality by mutually interchanging the depth and transverse directions, and the scanned (detection) and integrated (illumination) surfaces. Inversion methods are derived for image reconstructions with extremely large data sets. Numerical simulations are performed for fixed and rotated slabs

Instability of coupled gravity-inertial-Rossby waves on a β-plane in solar system atmospheres

Directory of Open Access Journals (Sweden)

J. F. McKenzie

2009-11-01

Full Text Available This paper provides an analysis of the combined theory of gravity-inertial-Rossby waves on a β-plane in the Boussinesq approximation. The wave equation for the system is fifth order in space and time and demonstrates how gravity-inertial waves on the one hand are coupled to Rossby waves on the other through the combined effects of β, the stratification characterized by the Väisälä-Brunt frequency N, the Coriolis frequency f at a given latitude, and vertical propagation which permits buoyancy modes to interact with westward propagating Rossby waves. The corresponding dispersion equation shows that the frequency of a westward propagating gravity-inertial wave is reduced by the coupling, whereas the frequency of a Rossby wave is increased. If the coupling is sufficiently strong these two modes coalesce giving rise to an instability. The instability condition translates into a curve of critical latitude Θ_c versus effective equatorial rotational Mach number M, with the region below this curve exhibiting instability. "Supersonic" fast rotators are unstable in a narrow band of latitudes around the equator. For example Θ_c~12° for Jupiter. On the other hand slow "subsonic" rotators (e.g. Mercury, Venus and the Sun's Corona are unstable at all latitudes except very close to the poles where the β effect vanishes. "Transonic" rotators, such as the Earth and Mars, exhibit instability within latitudes of 34° and 39°, respectively, around the Equator. Similar results pertain to Oceans. In the case of an Earth's Ocean of depth 4km say, purely westward propagating waves are unstable up to 26° about the Equator. The nonlinear evolution of this instability which feeds off rotational energy and gravitational buoyancy may play an important role in atmospheric dynamics.

Progress in parallel implementation of the multilevel plane wave time domain algorithm

KAUST Repository

Liu, Yang

2013-07-01

The computational complexity and memory requirements of classical schemes for evaluating transient electromagnetic fields produced by Ns dipoles active for Nt time steps scale as O(NtN s 2) and O(Ns 2), respectively. The multilevel plane wave time domain (PWTD) algorithm [A.A. Ergin et al., Antennas and Propagation Magazine, IEEE, vol. 41, pp. 39-52, 1999], viz. the extension of the frequency domain fast multipole method (FMM) to the time domain, reduces the above costs to O(NtNslog2Ns) and O(Ns α) with α = 1.5 for surface current distributions and α = 4/3 for volumetric ones. Its favorable computational and memory costs notwithstanding, serial implementations of the PWTD scheme unfortunately remain somewhat limited in scope and ill-suited to tackle complex real-world scattering problems, and parallel implementations are called for. © 2013 IEEE.

Plane wave diffraction by a finite plate with impedance boundary conditions.

Science.gov (United States)

Nawaz, Rab; Ayub, Muhammad; Javaid, Akmal

2014-01-01

In this study we have examined a plane wave diffraction problem by a finite plate having different impedance boundaries. The Fourier transforms were used to reduce the governing problem into simultaneous Wiener-Hopf equations which are then solved using the standard Wiener-Hopf procedure. Afterwards the separated and interacted fields were developed asymptotically by using inverse Fourier transform and the modified stationary phase method. Detailed graphical analysis was also made for various physical parameters we were interested in.

Fast Plane Wave 2-D Vector Flow Imaging Using Transverse Oscillation and Directional Beamforming

DEFF Research Database (Denmark)

Jensen, Jonas; Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo

2017-01-01

load, which is 4.6 times larger than for TO and seven times smaller than for conventional DB. Steered plane wave transmissions are employed for high frame rate imaging, and parabolic flow with a peak velocity of 0.5 m/s is simulated in straight vessels at beamto- flow angles from 45 to 90. The TO......-DB method estimates the angle with a bias and standard deviation (SD) less than 2, and the SD of the velocity magnitude is less than 2%. When using only TO, the SD of the angle ranges from 2 to 17 and for the velocity magnitude up to 7%. Bias of the velocity magnitude is within 2% for TO and slightly larger...

Acoustic multipath arrivals in the horizontal plane due to approaching nonlinear internal waves.

Science.gov (United States)

Badiey, Mohsen; Katsnelson, Boris G; Lin, Ying-Tsong; Lynch, James F

2011-04-01

Simultaneous measurements of acoustic wave transmissions and a nonlinear internal wave packet approaching an along-shelf acoustic path during the Shallow Water 2006 experiment are reported. The incoming internal wave packet acts as a moving frontal layer reflecting (or refracting) sound in the horizontal plane. Received acoustic signals are filtered into acoustic normal mode arrivals. It is shown that a horizontal multipath interference is produced. This has previously been called a horizontal Lloyd's mirror. The interference between the direct path and the refracted path depends on the mode number and frequency of the acoustic signal. A mechanism for the multipath interference is shown. Preliminary modeling results of this dynamic interaction using vertical modes and horizontal parabolic equation models are in good agreement with the observed data.

Nanoscale measurement of Nernst effect in two-dimensional charge density wave material 1T-TaS₂

Energy Technology Data Exchange (ETDEWEB)

Wu, Stephen M. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627, USA; Luican-Mayer, Adina [Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada; Bhattacharya, Anand [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Nanoscience and Technology Division, Argonne National Laboratory, Argonne, Illinois 60439, USA

2017-11-27

Advances in nanoscale material characterization on two-dimensional van der Waals layered materials primarily involve their optical and electronic properties. The thermal properties of these materials are harder to access due to the difficulty of thermal measurements at the nanoscale. In this work, we create a nanoscale magnetothermal device platform to access the basic out-of-plane magnetothermal transport properties of ultrathin van der Waals materials. Specifically, the Nernst effect in the charge density wave transition metal dichalcogenide 1T-TaS₂ is examined on nano-thin flakes in a patterned device structure. It is revealed that near the commensurate charge density wave (CCDW) to nearly commensurate charge density wave (NCCDW) phase transition, the polarity of the Nernst effect changes. Since the Nernst effect is especially sensitive to changes in the Fermi surface, this suggests that large changes are occurring in the out-of-plane electronic structure of 1T-TaS₂, which are otherwise unresolved in just in-plane electronic transport measurements. This may signal a coherent evolution of out-of-plane stacking in the CCDW! NCCDW transition.

Application of structural symmetries in the plane-wave-based transfer-matrix method for three-dimensional photonic crystal waveguides

International Nuclear Information System (INIS)

Li Zhiyuan; Ho Kaiming

2003-01-01

The plane-wave-based transfer-matrix method (TMM) exhibits a peculiar advantage of being capable of solving eigenmodes involved in an infinite photonic crystal and electromagnetic (EM) wave propagation in finite photonic crystal slabs or even semi-infinite photonic crystal structures within the same theoretical framework. In addition, this theoretical approach can achieve much improved numerical convergency in solution of photonic band structures than the conventional plane-wave expansion method. In this paper we employ this TMM in combination with a supercell technique to handle two important kinds of three-dimensional (3D) photonic crystal waveguide structures. The first one is waveguides created in a 3D layer-by-layer photonic crystal that possesses a complete band gap, the other more popular one is waveguides built in a two-dimensional photonic crystal slab. These waveguides usually have mirror-reflection symmetries in one or two directions perpendicular to their axis. We have taken advantage of these structural symmetries to reduce the numerical burden of the TMM solution of the guided modes. The solution to the EM problems under these mirror-reflection symmetries in both the real space and the plane-wave space is discussed in a systematic way and in great detail. Both the periodic boundary condition and the absorbing boundary condition are employed to investigate structures with or without complete 3D optical confinement. The fact that the EM field components investigated in the TMM are collinear with the symmetric axes of the waveguide brings great convenience and clarity in exploring the eigenmode symmetry in both the real space and the plane-wave space. The classification of symmetry involved in the guided modes can help people to better understand the coupling of the photonic crystal waveguides with external channels such as dielectric slab or wire waveguides

Extending the precision and efficiency of the all-electron full-potential linearized augmented plane-wave density-functional theory method

International Nuclear Information System (INIS)

Michalicek, Gregor

2015-01-01

Density functional theory (DFT) is the most widely-used first-principles theory for analyzing, describing and predicting the properties of solids based on the fundamental laws of quantum mechanics. The success of the theory is a consequence of powerful approximations to the unknown exchange and correlation energy of the interacting electrons and of sophisticated electronic structure methods that enable the computation of the density functional equations on a computer. A widely used electronic structure method is the full-potential linearized augmented plane-wave (FLAPW) method, that is considered to be one of the most precise methods of its kind and often referred to as a standard. Challenged by the demand of treating chemically and structurally increasingly more complex solids, in this thesis this method is revisited and extended along two different directions: (i) precision and (ii) efficiency. In the full-potential linearized augmented plane-wave method the space of a solid is partitioned into nearly touching spheres, centered at each atom, and the remaining interstitial region between the spheres. The Kohn-Sham orbitals, which are used to construct the electron density, the essential quantity in DFT, are expanded into a linearized augmented plane-wave basis, which consists of plane waves in the interstitial region and angular momentum dependent radial functions in the spheres. In this thesis it is shown that for certain types of materials, e.g., materials with very broad electron bands or large band gaps, or materials that allow the usage of large space-filling spheres, the variational freedom of the basis in the spheres has to be extended in order to represent the Kohn-Sham orbitals with high precision over a large energy spread. Two kinds of additional radial functions confined to the spheres, so-called local orbitals, are evaluated and found to successfully eliminate this error. A new efficient basis set is developed, named linearized augmented lattice

Plane wave diffraction by a finite plate with impedance boundary conditions.

Directory of Open Access Journals (Sweden)

Rab Nawaz

Full Text Available In this study we have examined a plane wave diffraction problem by a finite plate having different impedance boundaries. The Fourier transforms were used to reduce the governing problem into simultaneous Wiener-Hopf equations which are then solved using the standard Wiener-Hopf procedure. Afterwards the separated and interacted fields were developed asymptotically by using inverse Fourier transform and the modified stationary phase method. Detailed graphical analysis was also made for various physical parameters we were interested in.

Self-interstitial atom clusters as obstacles to glide of 1/3{11-bar 00} edge dislocations in α-zirconium

International Nuclear Information System (INIS)

Voskoboynikov, R.E.; Osetsky, Yu.N.; Bacon, D.J.

2005-01-01

Atomic-scale details of interaction of a 1/3 {11-bar 00} edge dislocation with clusters of self-interstitial atoms (SIAs) in α-zirconium has been studied by computer simulation. Four typical clusters are considered. A triangular cluster of five SIAs lying within a basal plane bisected by the dislocation glide plane is not absorbed by the dislocation but acts as a moderately strong obstacle. A 3-D SIA cluster lying across the glide plane is completely absorbed by the dislocation by creation of super-jogs, and is a weak obstacle. Interaction of the dislocation with glissile SIA loops with perfect Burgers vector inclined at 60 deg. to the dislocation glide plane shows that the process depends on the vector orientation. Defects of the two orientations are strong obstacles, and one, which initially forms a sessile segment on the dislocation line, is particularly so

Fast plane wave density functional theory molecular dynamics calculations on multi-GPU machines

International Nuclear Information System (INIS)

Jia, Weile; Fu, Jiyun; Cao, Zongyan; Wang, Long; Chi, Xuebin; Gao, Weiguo; Wang, Lin-Wang

2013-01-01

Plane wave pseudopotential (PWP) density functional theory (DFT) calculation is the most widely used method for material simulations, but its absolute speed stagnated due to the inability to use large scale CPU based computers. By a drastic redesign of the algorithm, and moving all the major computation parts into GPU, we have reached a speed of 12 s per molecular dynamics (MD) step for a 512 atom system using 256 GPU cards. This is about 20 times faster than the CPU version of the code regardless of the number of CPU cores used. Our tests and analysis on different GPU platforms and configurations shed lights on the optimal GPU deployments for PWP-DFT calculations. An 1800 step MD simulation is used to study the liquid phase properties of GaInP

Entire solutions for bistable lattice differential equations with obstacles

CERN Document Server

Hoffman, Aaron; Vleck, E S Van

2018-01-01

The authors consider scalar lattice differential equations posed on square lattices in two space dimensions. Under certain natural conditions they show that wave-like solutions exist when obstacles (characterized by "holes") are present in the lattice. Their work generalizes to the discrete spatial setting the results obtained in Berestycki, Hamel, and Matuno (2009) for the propagation of waves around obstacles in continuous spatial domains. The analysis hinges upon the development of sub and super-solutions for a class of discrete bistable reaction-diffusion problems and on a generalization of a classical result due to Aronson and Weinberger that concerns the spreading of localized disturbances.

Energy dissipation by submarine obstacles during landslide impact on reservoir - potentially avoiding catastrophic dam collapse

Science.gov (United States)

Kafle, Jeevan; Kattel, Parameshwari; Mergili, Martin; Fischer, Jan-Thomas; Tuladhar, Bhadra Man; Pudasaini, Shiva P.

2017-04-01

Dense geophysical mass flows such as landslides, debris flows and debris avalanches may generate super tsunami waves as they impact water bodies such as the sea, hydraulic reservoirs or mountain lakes. Here, we apply a comprehensive and general two-phase, physical-mathematical mass flow model (Pudasaini, 2012) that consists of non-linear and hyperbolic-parabolic partial differential equations for mass and momentum balances, and present novel, high-resolution simulation results for two-phase flows, as a mixture of solid grains and viscous fluid, impacting fluid reservoirs with obstacles. The simulations demonstrate that due to the presence of different obstacles in the water body, the intense flow-obstacle-interaction dramatically reduces the flow momentum resulting in the rapid energy dissipation around the obstacles. With the increase of obstacle height overtopping decreases but, the deflection and capturing (holding) of solid mass increases. In addition, the submarine solid mass is captured by the multiple obstacles and the moving mass decreases both in amount and speed as each obstacle causes the flow to deflect into two streams and also captures a portion of it. This results in distinct tsunami and submarine flow dynamics with multiple surface water and submarine debris waves. This novel approach can be implemented in open source GIS modelling framework r.avaflow, and be applied in hazard mitigation, prevention and relevant engineering or environmental tasks. This might be in particular for process chains, such as debris impacts in lakes and subsequent overtopping. So, as the complex flow-obstacle-interactions strongly and simultaneously dissipate huge energy at impact such installations potentially avoid great threat against the integrity of the dam. References: Pudasaini, S. P. (2012): A general two-phase debris flow model. J. Geophys. Res. 117, F03010, doi: 10.1029/ 2011JF002186.

Parallel Implementation of Gamma-Point Pseudopotential Plane-Wave DFT with Exact Exchange

International Nuclear Information System (INIS)

Bylaska, Eric J.; Tsemekhman, Kiril L.; Baden, Scott B.; Weare, John H.; Jonsson, Hannes

2011-01-01

One of the more persistent failures of conventional density functional theory (DFT) methods has been their failure to yield localized charge states such as polarons, excitons and solitons in solid-state and extended systems. It has been suggested that conventional DFT functionals, which are not self-interaction free, tend to favor delocalized electronic states since self-interaction creates a Coulomb barrier to charge localization. Pragmatic approaches in which the exchange correlation functionals are augmented with small amount of exact exchange (hybrid-DFT, e.g. B3LYP and PBE0) have shown promise in localizing charge states and predicting accurate band gaps and reaction barriers. We have developed a parallel algorithm for implementing exact exchange into pseudopotential plane-wave density functional theory and we have implemented it in the NWChem program package. The technique developed can readily be employed in plane-wave DFT programs. Furthermore, atomic forces and stresses are straightforward to implement, making it applicable to both confined and extended systems, as well as to Car-Parrinello ab initio molecular dynamic simulations. This method has been applied to several systems for which conventional DFT methods do not work well, including calculations for band gaps in oxides and the electronic structure of a charge trapped state in the Fe(II) containing mica, annite.

Measurement Verification of Plane Wave Synthesis Technique Based on Multi-probe MIMO-OTA Setup

DEFF Research Database (Denmark)

Fan, Wei; Carreño, Xavier; Nielsen, Jesper Ødum

2012-01-01

Standardization work for MIMO OTA testing methods is currently ongoing, where a multi-probe anechoic chamber based solution is an important candidate. In this paper, the probes located on an OTA ring are used to synthesize a plane wave field in the center of the OTA ring. This paper investigates...

Diffraction of a plane electromagnetic wave on a dielectric plate of variable density. [Field equatios, diffracted-wave angular distributions

Energy Technology Data Exchange (ETDEWEB)

Aivazyan, Yu M; Mergelyan, O S; Poulatov, M P

1974-01-01

Aproblem for the diffraction of a plane electromagnetic wave on a dielectric plate between two other dielectrics is solved. The dielectric constant of the plate depends periodically on three coordinates. From this solution it is possible to obtain the equations for fields and the angular distribution of diffracted waves for the particular cases of a crystal plate and a dielectric surface fluted in all directions. If the expansion is made in the variable of the electron density in crystals, the results will correspond to the problem for the X-ray diffraction on a crystal lattice, the values of the coefficient ..cap alpha -->..sub(tau) being determined by the lattice parameters.

Water Tank Experiments on Stratified Flow over Double Mountain-Shaped Obstacles at High-Reynolds Number

Directory of Open Access Journals (Sweden)

Ivana Stiperski

2017-01-01

Full Text Available In this article, we present an overview of the HyIV-CNRS-SecORo (Hydralab IV-CNRS-Secondary Orography and Rotors Experiments laboratory experiments carried out in the CNRM (Centre National de Recherches Météorologiques large stratified water flume. The experiments were designed to systematically study the influence of double obstacles on stably stratified flow. The experimental set-up consists of a two-layer flow in the water tank, with a lower neutral and an upper stable layer separated by a sharp density discontinuity. This type of layering over terrain is known to be conducive to a variety of possible responses in the atmosphere, from hydraulic jumps to lee waves and highly turbulent rotors. In each experiment, obstacles were towed through the tank at a constant speed. The towing speed and the size of the tank allowed high Reynolds-number flow similar to the atmosphere. Here, we present the experimental design, together with an overview of laboratory experiments conducted and their results. We develop a regime diagram for flow over single and double obstacles and examine the parameter space where the secondary obstacle has the largest influence on the flow. Trapped lee waves, rotors, hydraulic jumps, lee-wave interference and flushing of the valley atmosphere are successfully reproduced in the stratified water tank. Obstacle height and ridge separation distance are shown to control lee-wave interference. Results, however, differ partially from previous findings on the flow over double ridges reported in the literature due to the presence of nonlinearities and possible differences in the boundary layer structure. The secondary obstacle also influences the transition between different flow regimes and makes trapped lee waves possible for higher Froude numbers than expected for an isolated obstacle.

A domain derivative-based method for solving elastodynamic inverse obstacle scattering problems

International Nuclear Information System (INIS)

Le Louër, Frédérique

2015-01-01

The present work is concerned with the shape reconstruction problem of isotropic elastic inclusions from far-field data obtained by the scattering of a finite number of time-harmonic incident plane waves. This paper aims at completing the theoretical framework which is necessary for the application of geometric optimization tools to the inverse transmission problem in elastodynamics. The forward problem is reduced to systems of boundary integral equations following the direct and indirect methods initially developed for solving acoustic transmission problems. We establish the Fréchet differentiability of the boundary to far-field operator and give a characterization of the first Fréchet derivative and its adjoint operator. Using these results we propose an inverse scattering algorithm based on the iteratively regularized Gauß–Newton method and show numerical experiments in the special case of star-shaped obstacles. (paper)

Trajectories of electrons with large longitudinal momenta in the phase plane during surfatron acceleration by an electromagnetic wave

Energy Technology Data Exchange (ETDEWEB)

Mkrtichyan, G. S., E-mail: hay-13@mail.ru [Peoples’ Friendship University of Russia (Russian Federation)

2015-07-15

The trajectories of electrons with large longitudinal momenta in the phase plane in the course of their surfatron acceleration by an electromagnetic wave propagating in space plasma across the external magnetic field are analyzed. Electrons with large longitudinal momenta are trapped immediately if the initial wave phase Ψ(0) on the particle trajectory is positive. For negative values of Ψ(0), no electrons trapping by the wave is observed over the available computational times. According to numerical calculations, the trajectories of trapped particles in the phase plane have a singular point of the stable focus type and the behavior of the trajectory corresponds to the motion in a complex nonstationary effective potential well. For some initial phases, electrons are confined in the region of the accelerating electric field for relatively short time, the energy gain being about 50–130% and more.

Fast solution of elliptic partial differential equations using linear combinations of plane waves.

Science.gov (United States)

Pérez-Jordá, José M

2016-02-01

Given an arbitrary elliptic partial differential equation (PDE), a procedure for obtaining its solution is proposed based on the method of Ritz: the solution is written as a linear combination of plane waves and the coefficients are obtained by variational minimization. The PDE to be solved is cast as a system of linear equations Ax=b, where the matrix A is not sparse, which prevents the straightforward application of standard iterative methods in order to solve it. This sparseness problem can be circumvented by means of a recursive bisection approach based on the fast Fourier transform, which makes it possible to implement fast versions of some stationary iterative methods (such as Gauss-Seidel) consuming O(NlogN) memory and executing an iteration in O(Nlog(2)N) time, N being the number of plane waves used. In a similar way, fast versions of Krylov subspace methods and multigrid methods can also be implemented. These procedures are tested on Poisson's equation expressed in adaptive coordinates. It is found that the best results are obtained with the GMRES method using a multigrid preconditioner with Gauss-Seidel relaxation steps.

Generating gravity waves with matter and electromagnetic waves

International Nuclear Information System (INIS)

Barrabes, C.; Hogan, P A.

2008-01-01

If a homogeneous plane lightlike shell collides head on with a homogeneous plane electromagnetic shock wave having a step-function profile then no backscattered gravitational waves are produced. We demonstrate, by explicit calculation, that if the matter is accompanied by a homogeneous plane electromagnetic shock wave with a step-function profile then backscattered gravitational waves appear after the collision

Gas explosion characterization, wave propagation (small-scale experiments)

International Nuclear Information System (INIS)

Larsen, G.C.

1985-01-01

A number of experiments have been performed with blast waves arising from the ignition of homogeneous and well defined mixtures of methane, oxygen and nitrogen, contained within spherical balloons with controlled initial dimensions. In the initial small scale experiments pressure characteristics, ground reflection phenomena and pressure distribution on box like obstacles were studied. Both configurations with one box and two closely spaced boxes have been considered, and a wave-wave interaction phenomenom was observed in the case of closely spaced obstacles. Main emphasis has been placed on the half scale field experiments. In these, the maximum flame speed has been of the order of 100 m/s, resulting in positive peak pressures of 50-100.10 2 Pa in 5 - 10 m distance from the source. The explosion process was found to be reasonable symmetric. The attenuation of the blast wave due to vegetation and the influence of obstacles as banks, walls and houses on the pressure field have been investigated. The presence of the bank and the house was felt in a zone with a length corresponding to a typical dimension of the obstacles, whereas the overall pressure field is shown to be unaffected by the type of obstacles and vegetation investigated. For the wall and house, reflection factors have been established, and some variation over the surface has been measured. The scatter of the pressure measurements is estimated for stable, neutral and unstable atmospheric conditions, and an attempt to determine the ground reflection factor has been performed. Finally the accelerations of a house exposed to the blast wave have been examined

Linear augmented plane wave method for self-consistent calculations

International Nuclear Information System (INIS)

Takeda, T.; Kuebler, J.

1979-01-01

O.K. Andersen has recently introduced a linear augmented plane wave method (LAPW) for the calculation of electronic structure that was shown to be computationally fast. A more general formulation of an LAPW method is presented here. It makes use of a freely disposable number of eigenfunctions of the radial Schroedinger equation. These eigenfunctions can be selected in a self-consistent way. The present formulation also results in a computationally fast method. It is shown that Andersen's LAPW is obtained in a special limit from the present formulation. Self-consistent test calculations for copper show the present method to be remarkably accurate. As an application, scalar-relativistic self-consistent calculations are presented for the band structure of FCC lanthanum. (author)

Electromagnetic forces and torques in nanoparticles irradiated by plane waves

International Nuclear Information System (INIS)

Garcia de Abajo, F.J.

2004-01-01

Optical tweezers and optical lattices are making it possible to control small particles by means of electromagnetic forces and torques. In this context, a method is presented in this work to calculate electromagnetic forces and torques for arbitrarily-shaped objects in the presence of other objects illuminated by a plane wave. The method is based upon an expansion of the electromagnetic field in terms of multipoles around each object, which are in turn used to derive forces and torques analytically. The calculation of multipole coefficients are obtained numerically by means of the boundary element method. Results are presented for both spherical and non-spherical objects

Explicit formulas for Neumann coefficients in the plane-wave geometry

International Nuclear Information System (INIS)

He Yanghui; Schwarz, John H.; Spradlin, Marcus; Volovich, Anastasia

2003-01-01

We obtain explicit formulas for the Neumann coefficients and associated quantities that appear in the three-string vertex for type IIB string theory in a plane-wave background, for any value of the mass parameter μ. The derivation involves constructing the inverse of a certain infinite-dimensional matrix, in terms of which the Neumann coefficients previously had been written only implicitly. We derive asymptotic expansions for large μ and find unexpectedly simple results, which are valid to all orders in 1/μ. Using BMN duality, these give predictions for certain gauge theory quantities to all orders in the modified 't Hooft coupling λ ' . A specific example is presented

Recovering an elastic obstacle containing embedded objects by the acoustic far-field measurements

Science.gov (United States)

Qu, Fenglong; Yang, Jiaqing; Zhang, Bo

2018-01-01

Consider the inverse scattering problem of time-harmonic acoustic waves by a 3D bounded elastic obstacle which may contain embedded impenetrable obstacles inside. We propose a novel and simple technique to show that the elastic obstacle can be uniquely recovered by the acoustic far-field pattern at a fixed frequency, disregarding its contents. Our method is based on constructing a well-posed modified interior transmission problem on a small domain and makes use of an a priori estimate for both the acoustic and elastic wave fields in the usual H 1-norm. In the case when there is no obstacle embedded inside the elastic body, our method gives a much simpler proof for the uniqueness result obtained previously in the literature (Natroshvili et al 2000 Rend. Mat. Serie VII 20 57-92 Monk and Selgas 2009 Inverse Problems Imaging 3 173-98).

Reflection and Transmission of Plane Electromagnetic Waves by a Geologic Layer.

Energy Technology Data Exchange (ETDEWEB)

Aldridge, David F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-04-01

Electric field and magnetic field reflection and transmission responses generated by a plane wave normally incident onto a finite - thickness geologic layer are mathematically derived and numerically evaluated. A thin layer with enhanced electric current conductivity and/or magnetic permeability is a reasonable geophysical representation of a hydraulic fracture inject ed with a high - contrast proppant pack. Both theory and numerics indicate that backward - and forward - scattered electromagnetic wavefields are potentially observable in a field experiment, despite the extreme thinness of a fracture compared to a typical low - frequency electromagnetic wavelength. The First Born Approximation (FBA) representation of layer scattering, significant for inversion studies, is shown to be accurate for a thin layer with mild medium parameter (i.e., conductivity, permeability, and per mittivity) contrasts with the surrounding homogeneous wholespace. However, FBA scattering theory breaks down for thick layers and strong parameter contrasts. ACKNOWLEDGEMENTS Sandia National Laboratories is a multi - mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000. This research is conducted under the auspices of CRADA (Cooperative Research and Development Agreement) SC11/01780.00 between Carbo Ceramics Inc. and Sandia National Laboratories. The author acknowledges former Carbo R&D Vic e - President Mr. Chad Cannan and former SNL Geophysics Department manage r Ms. Amy Halloran for their interest i n and support of this work. Technical discussions with Project Manager and Principal Investigator Dr. Chester J. Weiss of the SNL Geophysics Department greatly benefited this work. Dr. Lewis C. Bartel, formerly with S NL and presently a consultant to Carbo Ceramics, provided many useful and intuitive insights, and

Three-dimensional effects on cracked components under anti-plane loading

Directory of Open Access Journals (Sweden)

F. Berto

2015-07-01

Full Text Available The existence of three-dimensional effects at cracks has been known for many years, but understanding has been limited, and for some situations still is. Understanding improved when the existence of corner point singularities and their implications became known. Increasingly powerful computers made it possible to investigate three-dimensional effects numerically in detail. Despite increased understanding, threedimensional effects are sometimes ignored in situations where they may be important. The purpose of the present investigation is to study by means of accurate 3D finite element (FE models a coupled fracture mode generated by anti-plane loading of a straight through-the-thickness crack in linear elastic plates. An extended version of the present work has recently been published in the literature. The results obtained from the highly accurate finite element analyses have improved understanding of the behaviour of through cracked components under anti-plane loading. The influence of plate bending is increasingly important as the thickness decreases. It appears that a new field parameter, probably a singularity, is needed to describe the stresses at the free surfaces. Discussion on whether KIII tends to zero or infinity as a corner point is approached is futile because KIII is meaningless at a corner point. The intensity of the local stress and strain state through the thickness of the cracked components has been evaluated by using the strain energy density (SED averaged over a control volume embracing the crack tip. The SED has been considered as a parameter able to control fracture in some previous contributions and can easily take into account also coupled three-dimensional effects. Calculation of the SED shows that the position of the maximum SED is independent of plate thickness. Both for thin plates and for thick ones the maximum SED is close to the lateral surface, where the maximum intensity of the coupled mode II takes place.

Reflection of Lamb waves obliquely incident on the free edge of a plate.

Science.gov (United States)

Santhanam, Sridhar; Demirli, Ramazan

2013-01-01

The reflection of obliquely incident symmetric and anti-symmetric Lamb wave modes at the edge of a plate is studied. Both in-plane and Shear-Horizontal (SH) reflected wave modes are spawned by an obliquely incident in-plane Lamb wave mode. Energy reflection coefficients are calculated for the reflected wave modes as a function of frequency and angle of incidence. This is done by using the method of orthogonal mode decomposition and by enforcing traction free conditions at the plate edge using the method of collocation. A PZT sensor network, affixed to an Aluminum plate, is used to experimentally verify the predictions of the analysis. Experimental results provide support for the analytically determined results. Copyright © 2012 Elsevier B.V. All rights reserved.

Can continuous scans in orthogonal planes improve diagnostic performance of shear wave elastography for breast lesions?

Science.gov (United States)

Yang, Pan; Peng, Yulan; Zhao, Haina; Luo, Honghao; Jin, Ya; He, Yushuang

2015-01-01

Static shear wave elastography (SWE) is used to detect breast lesions, but slice and plane selections result in discrepancies. To evaluate the intraobserver reproducibility of continuous SWE, and whether quantitative elasticities in orthogonal planes perform better in the differential diagnosis of breast lesions. One hundred and twenty-two breast lesions scheduled for ultrasound-guided biopsy were recruited. Continuous SWE scans were conducted in orthogonal planes separately. Quantitative elasticities and histopathology results were collected. Reproducibility in the same plane and diagnostic performance in different planes were evaluated. The maximum and mean elasticities of the hardest portion, and standard deviation of whole lesion, had high inter-class correlation coefficients (0.87 to 0.95) and large areas under receiver operation characteristic curve (0.887 to 0.899). Without loss of accuracy, sensitivities had increased in orthogonal planes compared with single plane (from 73.17% up to 82.93% at most). Mean elasticity of whole lesion and lesion-to-parenchyma ratio were significantly less reproducible and less accurate. Continuous SWE is highly reproducible for the same observer. The maximum and mean elasticities of the hardest portion and standard deviation of whole lesion are most reliable. Furthermore, the sensitivities of the three parameters are improved in orthogonal planes without loss of accuracies.

High-order boundary integral equation solution of high frequency wave scattering from obstacles in an unbounded linearly stratified medium

Science.gov (United States)

Barnett, Alex H.; Nelson, Bradley J.; Mahoney, J. Matthew

2015-09-01

We apply boundary integral equations for the first time to the two-dimensional scattering of time-harmonic waves from a smooth obstacle embedded in a continuously-graded unbounded medium. In the case we solve, the square of the wavenumber (refractive index) varies linearly in one coordinate, i.e. (Δ + E +x2) u (x1 ,x2) = 0 where E is a constant; this models quantum particles of fixed energy in a uniform gravitational field, and has broader applications to stratified media in acoustics, optics and seismology. We evaluate the fundamental solution efficiently with exponential accuracy via numerical saddle-point integration, using the truncated trapezoid rule with typically 102 nodes, with an effort that is independent of the frequency parameter E. By combining with a high-order Nyström quadrature, we are able to solve the scattering from obstacles 50 wavelengths across to 11 digits of accuracy in under a minute on a desktop or laptop.

Accuracy and Precision of Plane Wave Vector Flow Imaging for Laminar and Complex Flow In Vivo

DEFF Research Database (Denmark)

Jensen, Jonas; Traberg, Marie Sand; Villagómez Hoyos, Carlos Armando

2017-01-01

In this study, a comparison between velocity fields for a plane wave 2-D vector flow imaging (VFI) method and a computational fluid dynamics (CFD) simulation is made. VFI estimates are obtained from the scan of a flow phantom, which mimics the complex flow conditions in the carotid artery....... Furthermore, the precision of the VFI method is investigated under laminar and complex flow conditions in vivo. The carotid bifurcation of a healthy volunteer was scanned using both fast plane wave ultrasound and magnetic resonance imaging (MRI). The acquired MRI geometry of the bifurcation was used...... difference within 15 %, however, it was 23 % in the external branch. For the in vivo scan, the precision in terms of mean standard deviation (SD) of estimates aligned to the cardiac cycle was highest in the center of the common carotid artery (SD 4.7◦ for angles) and lowest in the external branch and close...

RCS Diversity of Electromagnetic Wave Carrying Orbital Angular Momentum.

Science.gov (United States)

Zhang, Chao; Chen, Dong; Jiang, Xuefeng

2017-11-13

An electromagnetic (EM) wave with orbital angular momentum (OAM) has a helical wave front, which is different from that of the plane wave. The phase gradient can be found perpendicular to the direction of propagation and proportional to the number of OAM modes. Herein, we study the backscattering property of the EM wave with different OAM modes, i.e., the radar cross section (RCS) of the target is measured and evaluated with different OAM waves. As indicated by the experimental results, different OAM waves have the same RCS fluctuation for the simple target, e.g., a small metal ball as the target. However, for complicated targets, e.g., two transverse-deployed small metal balls, different RCSs can be identified from the same incident angle. This valuable fact helps to obtain RCS diversity, e.g., equal gain or selective combining of different OAM wave scattering. The majority of the targets are complicated targets or expanded targets; the RCS diversity can be utilized to detect a weak target traditionally measured by the plane wave, which is very helpful for anti-stealth radar to detect the traditional stealth target by increasing the RCS with OAM waves.

ABINIT: Plane-Wave-Based Density-Functional Theory on High Performance Computers

Science.gov (United States)

Torrent, Marc

2014-03-01

For several years, a continuous effort has been produced to adapt electronic structure codes based on Density-Functional Theory to the future computing architectures. Among these codes, ABINIT is based on a plane-wave description of the wave functions which allows to treat systems of any kind. Porting such a code on petascale architectures pose difficulties related to the many-body nature of the DFT equations. To improve the performances of ABINIT - especially for what concerns standard LDA/GGA ground-state and response-function calculations - several strategies have been followed: A full multi-level parallelisation MPI scheme has been implemented, exploiting all possible levels and distributing both computation and memory. It allows to increase the number of distributed processes and could not be achieved without a strong restructuring of the code. The core algorithm used to solve the eigen problem (``Locally Optimal Blocked Congugate Gradient''), a Blocked-Davidson-like algorithm, is based on a distribution of processes combining plane-waves and bands. In addition to the distributed memory parallelization, a full hybrid scheme has been implemented, using standard shared-memory directives (openMP/openACC) or porting some comsuming code sections to Graphics Processing Units (GPU). As no simple performance model exists, the complexity of use has been increased; the code efficiency strongly depends on the distribution of processes among the numerous levels. ABINIT is able to predict the performances of several process distributions and automatically choose the most favourable one. On the other hand, a big effort has been carried out to analyse the performances of the code on petascale architectures, showing which sections of codes have to be improved; they all are related to Matrix Algebra (diagonalisation, orthogonalisation). The different strategies employed to improve the code scalability will be described. They are based on an exploration of new diagonalization

The H.E.S.S. Galactic plane survey

Science.gov (United States)

H. E. S. S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Benkhali, F. Ait; Angüner, E. O.; Arakawa, M.; Arrieta, M.; Aubert, P.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Tjus, J. Becker; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bonnefoy, S.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Büchele, M.; Bulik, T.; Capasso, M.; Carrigan, S.; Caroff, S.; Carosi, A.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Colafrancesco, S.; Condon, B.; Conrad, J.; Davids, I. D.; Decock, J.; Deil, C.; Devin, J.; deWilt, P.; Dirson, L.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O.'C.; Dutson, K.; Dyks, J.; Edwards, T.; Egberts, K.; Eger, P.; Emery, G.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Funk, S.; Füßling, M.; Gabici, S.; Gallant, Y. A.; Garrigoux, T.; Gast, H.; Gaté, F.; Giavitto, G.; Giebels, B.; Glawion, D.; Glicenstein, J. F.; Gottschall, D.; Grondin, M.-H.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holch, T. L.; Holler, M.; Horns, D.; Ivascenko, A.; Iwasaki, H.; Jacholkowska, A.; Jamrozy, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katsuragawa, M.; Katz, U.; Kerszberg, D.; Khangulyan, D.; Khélifi, B.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Komin, Nu.; Kosack, K.; Krakau, S.; Kraus, M.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lees, J.-P.; Lefaucheur, J.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Marandon, V.; Malyshev, D.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morå, K.; Moulin, E.; Murach, T.; Nakashima, S.; de Naurois, M.; Ndiyavala, H.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Piel, Q.; Pita, S.; Poireau, V.; Poon, H.; Prokhorov, D.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Rauth, R.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Rinchiuso, L.; Romoli, C.; Rowell, G.; Rudak, B.; Rulten, C. B.; Safi-Harb, S.; Sahakian, V.; Saito, S.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schandri, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Seglar-Arroyo, M.; Settimo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Shiningayamwe, K.; Simoni, R.; Sol, H.; Spanier, F.; Spir-Jacob, M.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Steppa, C.; Sushch, I.; Takahashi, T.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tsirou, M.; Tsuji, N.; Tuffs, R.; Uchiyama, Y.; van der Walt, D. J.; van Eldik, C.; van Rensburg, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zaborov, D.; Zacharias, M.; Zanin, R.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Zorn, J.; Żywucka, N.

2018-04-01

We present the results of the most comprehensive survey of the Galactic plane in very high-energy (VHE) γ-rays, including a public release of Galactic sky maps, a catalog of VHE sources, and the discovery of 16 new sources of VHE γ-rays. The High Energy Spectroscopic System (H.E.S.S.) Galactic plane survey (HGPS) was a decade-long observation program carried out by the H.E.S.S. I array of Cherenkov telescopes in Namibia from 2004 to 2013. The observations amount to nearly 2700 h of quality-selected data, covering the Galactic plane at longitudes from ℓ = 250° to 65° and latitudes |b|≤ 3°. In addition to the unprecedented spatial coverage, the HGPS also features a relatively high angular resolution (0.08° ≈ 5 arcmin mean point spread function 68% containment radius), sensitivity (≲1.5% Crab flux for point-like sources), and energy range (0.2-100 TeV). We constructed a catalog of VHE γ-ray sources from the HGPS data set with a systematic procedure for both source detection and characterization of morphology and spectrum. We present this likelihood-based method in detail, including the introduction of a model component to account for unresolved, large-scale emission along the Galactic plane. In total, the resulting HGPS catalog contains 78 VHE sources, of which 14 are not reanalyzed here, for example, due to their complex morphology, namely shell-like sources and the Galactic center region. Where possible, we provide a firm identification of the VHE source or plausible associations with sources in other astronomical catalogs. We also studied the characteristics of the VHE sources with source parameter distributions. 16 new sources were previously unknown or unpublished, and we individually discuss their identifications or possible associations. We firmly identified 31 sources as pulsar wind nebulae (PWNe), supernova remnants (SNRs), composite SNRs, or gamma-ray binaries. Among the 47 sources not yet identified, most of them (36) have possible

Useful Solutions for Plane Wave Diffraction by Dielectric Slabs and Wedges

Directory of Open Access Journals (Sweden)

Gianluca Gennarelli

2012-01-01

Full Text Available This work presents an overview of available uniform asymptotic physical optics solutions for evaluating the plane wave diffraction by some canonical geometries of large interest: dielectric slabs and wedges. Such solutions are based on a physical optics approximation of the electric and magnetic equivalent surface currents in the involved scattering integrals. The resulting diffraction coefficients are expressed in terms of the geometrical optics response of the considered structure and the standard transition function of the Uniform Geometrical Theory of Diffraction. Numerical tests and comparisons make evident the effectiveness and reliability of the presented solutions.

Dispersive photonic crystals from the plane wave method

Energy Technology Data Exchange (ETDEWEB)

Guevara-Cabrera, E.; Palomino-Ovando, M.A. [Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Apdo. Post. 165, Puebla, Pue. 72000, México (Mexico); Flores-Desirena, B., E-mail: bflores@fcfm.buap.mx [Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Apdo. Post. 165, Puebla, Pue. 72000, México (Mexico); Gaspar-Armenta, J.A. [Departamento de Investigación en Física de la Universidad de Sonora Apdo, Post 5-088, Hermosillo Sonora 83190, México (Mexico)

2016-03-01

Nowadays photonic crystals are widely used in many different applications. One of the most used methods to compute their band structure is the plane wave method (PWM). However, it can only be applied directly to non-dispersive media and be extended to systems with a few model dielectric functions. We explore an extension of the PWM to photonic crystals containing dispersive materials, that solves an eigenvalue equation for the Bloch wave vectors. First we compare our calculation with analytical results for one dimensional photonic crystals containing Si using experimental values of its optical parameters, and obtainig very well agreement, even for the spectrum region with strong absorption. Then, using the same method, we computed the band structure for a two dimensional photonic crystal without absorption, formed by an square array of MgO cylinders in air. The optical parameters for MgO were modeled with the Lorentz dielectric function. Finally, we studied an array of MgO cylinders in a metal, using Drude model without absorption, for the metal dielectric function. For this last case, we study the gap–midgap ratio as a function of the filling fraction for both the square and triangular lattice. The gap–midgap ratio is larger for the triangular lattice, with a maximum value of 10% for a filling fraction of 0.6. Our results show that the method can be applied to dispersive materials, and then to a wide range of applications where photonic crystals can be used.

Flow features that arise due to the interaction of a plane shock wave with concave profiles

CSIR Research Space (South Africa)

MacLucas, David A

2012-10-01

Full Text Available The focus of the author's thesis was the aerodynamic flow field that develops as a result of the interaction of a moving plane shock wave with concave profiles. In this presentation, he discusses some of the interesting flow phenomena that arise...

Formation of superlattice with aligned plane orientation of colloidal PbS quantum dots

Science.gov (United States)

Mukai, Kohki; Fujimoto, Satoshi; Suetsugu, Fumimasa

2018-04-01

We investigated a method of forming a perfect quantum dot (QD) superlattice, in which each QD has the same plane orientation, by depositing colloidal PbS QDs with clear facets in solution. QD facets were controlled by adjusting the synthesis temperature. X-ray evaluation showed that the crystal orientations of the film with QDs having clear facets were aligned. The slow deposition promoted this crystal alignment. The red shift of photoluminescence wavelength caused by the film formation was larger with QDs having facets than with spherical QDs, suggesting that the connection of the wave function between QDs was better so that the quantum size effect was further reduced.

Lee waves, benign and malignant

Science.gov (United States)

Wurtele, M. G.; Datta, A.

1992-01-01

The flow of an incompressible, stratified fluid over an obstacle will produce an oscillation in which buoyancy is the restoring force, called a gravity wave. For disturbances of this scale, the atmosphere may be treated as incompressible; and even the linear approximation will explain many of the phenomena observed in the lee of mountains. However, nonlinearities arise in two ways: (1) through the large (scaled) size of the mountain, and (2) from dynamically singular levels in the fluid field. These produce a complicated array of phenomena that present hazards to aircraft and to lee surface areas. If there is no dynamic barrier, these waves can penetrate vertically into the middle atmosphere (30-100 km attitude), where recent observations show them to be of a length scale that must involve the Coriolis force in any modeling. At these altitudes, the amplitude of the waves is very large, and the waves are studied with a view to their potential impact on the projected National Aerospace Plane. This paper presents the results of analyses and state-of-the-art numerical simulations, validated where possible by observational data.

The effect of submerged obstacles on circular fronts propagating into water at rest

International Nuclear Information System (INIS)

Mvungi, J.R.

1986-03-01

In this paper, the effect of vertical walled obstacles on circular fronts propagating on the surface of shallow water is discussed. The amplitude of the transmitted acceleration waves is determined together with a recurrence relation for the reflection and transmission coefficients at successive obstacle walls. (author)

Assisting the Visually Impaired: Obstacle Detection and Warning System by Acoustic Feedback

Directory of Open Access Journals (Sweden)

Andrés Cela

2012-12-01

Full Text Available The aim of this article is focused on the design of an obstacle detection system for assisting visually impaired people. A dense disparity map is computed from the images of a stereo camera carried by the user. By using the dense disparity map, potential obstacles can be detected in 3D in indoor and outdoor scenarios. A ground plane estimation algorithm based on RANSAC plus filtering techniques allows the robust detection of the ground in every frame. A polar grid representation is proposed to account for the potential obstacles in the scene. The design is completed with acoustic feedback to assist visually impaired users while approaching obstacles. Beep sounds with different frequencies and repetitions inform the user about the presence of obstacles. Audio bone conducting technology is employed to play these sounds without interrupting the visually impaired user from hearing other important sounds from its local environment. A user study participated by four visually impaired volunteers supports the proposed system.

Increased Frame Rate for Plane Wave Imaging Without Loss of Image Quality

DEFF Research Database (Denmark)

Jensen, Jonas; Stuart, Matthias Bo; Jensen, Jørgen Arendt

2015-01-01

Clinical applications of plane wave imaging necessitate the creation of high-quality images with the highest possible frame rate for improved blood flow tracking and anatomical imaging. However, linear array transducers create grating lobe artefacts, which degrade the image quality especially...... in the near field for λ-pitch transducers. Artefacts can only partly be suppressed by increasing the number of emissions, and this paper demonstrates how the frame rate can be increased without loss of image quality by using λ/2-pitch transducers. The number of emissions and steering angles are optimized...

Pascal’s Theorem in Real Projective Plane

OpenAIRE

Coghetto Roland

2017-01-01

In this article we check, with the Mizar system [2], Pascal’s theorem in the real projective plane (in projective geometry Pascal’s theorem is also known as the Hexagrammum Mysticum Theorem)1. Pappus’ theorem is a special case of a degenerate conic of two lines.

Acoustic radiation force on cylindrical shells in a plane standing wave

International Nuclear Information System (INIS)

Mitri, F G

2005-01-01

In this paper, the radiation force per length resulting from a plane standing wave incident on an infinitely long cylindrical shell is computed. The cases of elastic and viscoelastic shells immersed in ideal (non-viscous) fluids are considered with particular emphasis on their thickness and the content of their interior hollow spaces. Numerical calculations of the radiation force function Y st are performed. The fluid-loading effect on the radiation force function curves is analysed as well. The results show several features quite different when the interior hollow space is changed from air to water. Moreover, the theory developed here is more general since it includes the results on cylinders

On the determination of general plane stress states in orthotropic materials from ultrasonic velocity data in non symmetry planes

International Nuclear Information System (INIS)

Goncalves Filho, Orlando J.A.

2015-01-01

This work reports the progress in the development of a new experimental protocol for plane stress determination in orthotropic materials based on the ultrasonic velocity of bulk waves propagating in non symmetry planes with oblique incidence. The presence of stress-induced deformation introduces an acoustic anisotropy in the material in addition to that defined by its texture. Orthotropic materials under general plane stress states become acoustically monoclic and its orthotropic planes orthogonal to the stress plane become non symmetry planes. The inverse solution of the generalized Christoffel equation for ultrasonic bulk waves propagating in non symmetry planes of anisotropic bodies is known to be numerically unstable. The suggested protocol deals with this numerical instability without recourse to bulk wave propagation in the stress plane as proposed in the literature. Hence, it should be useful for plane stress analysis of thin wall pressure vessels where ultrasonic measurements in the direction of the wall plane are not possible. For the initial validation of the suggested protocol and verification of the stability of the inversion algorithm, computer simulation of stress determination have been performed from synthetic sets of velocity data obtained by the forward solution of the generalized Christoffel equation. Preliminary results for slightly orthotropic aluminium highlight the potential of the suggested protocol. (author)

Pascal’s Theorem in Real Projective Plane

Directory of Open Access Journals (Sweden)

Coghetto Roland

2017-07-01

Full Text Available In this article we check, with the Mizar system [2], Pascal’s theorem in the real projective plane (in projective geometry Pascal’s theorem is also known as the Hexagrammum Mysticum Theorem1. Pappus’ theorem is a special case of a degenerate conic of two lines.

Lee waves: Benign and malignant

Science.gov (United States)

Wurtele, M. G.; Datta, A.; Sharman, R. D.

1993-01-01

The flow of an incompressible fluid over an obstacle will produce an oscillation in which buoyancy is the restoring force, called a gravity wave. For disturbances of this scale, the atmosphere may be treated as dynamically incompressible, even though there exists a mean static upward density gradient. Even in the linear approximation - i.e., for small disturbances - this model explains a great many of the flow phenomena observed in the lee of mountains. However, nonlinearities do arise importantly, in three ways: (1) through amplification due to the decrease of mean density with height; (2) through the large (scaled) size of the obstacle, such as a mountain range; and (3) from dynamically singular levels in the fluid field. These effects produce a complicated array of phenomena - large departure of the streamlines from their equilibrium levels, high winds, generation of small scales, turbulence, etc. - that present hazards to aircraft and to lee surface areas. The nonlinear disturbances also interact with the larger-scale flow in such a manner as to impact global weather forecasts and the climatological momentum balance. If there is no dynamic barrier, these waves can penetrate vertically into the middle atmosphere (30-100 km), where recent observations show them to be of a length scale that must involve the coriolis force in any modeling. At these altitudes, the amplitude of the waves is very large, and the phenomena associated with these wave dynamics are being studied with a view to their potential impact on high performance aircraft, including the projected National Aerospace Plane (NASP). The presentation shows the results of analysis and of state-of-the-art numerical simulations, validated where possible by observational data, and illustrated with photographs from nature.

Cylindrical and spherical space equivalents to the plane wave expansion technique of Maxwell's wave equations

Science.gov (United States)

Gauthier, Robert C.; Alzahrani, Mohammed A.; Jafari, Seyed Hamed

2015-02-01

The plane wave expansion (PWM) technique applied to Maxwell's wave equations provides researchers with a supply of information regarding the optical properties of dielectric structures. The technique is well suited for structures that display a linear periodicity. When the focus is directed towards optical resonators and structures that lack linear periodicity the eigen-process can easily exceed computational resources and time constraints. In the case of dielectric structures which display cylindrical or spherical symmetry, a coordinate system specific set of basis functions have been employed to cast Maxwell's wave equations into an eigen-matrix formulation from which the resonator states associated with the dielectric profile can be obtained. As for PWM, the inverse of the dielectric and field components are expanded in the basis functions (Fourier-Fourier-Bessel, FFB, in cylindrical and Fourier- Bessel-Legendre, BLF, in spherical) and orthogonality is employed to form the matrix expressions. The theoretical development details will be presented indicating how certain mathematical complications in the process have been overcome and how the eigen-matrix can be tuned to a specific mode type. The similarities and differences in PWM, FFB and BLF are presented. In the case of structures possessing axial cylindrical symmetry, the inclusion of the z axis component of propagation constant makes the technique applicable to photonic crystal fibers and other waveguide structures. Computational results will be presented for a number of different dielectric geometries including Bragg ring resonators, cylindrical space slot channel waveguides and bottle resonators. Steps to further enhance the computation process will be reported.

Shape optimization of solid-air porous phononic crystal slabs with widest full 3D bandgap for in-plane acoustic waves

Science.gov (United States)

D'Alessandro, Luca; Bahr, Bichoy; Daniel, Luca; Weinstein, Dana; Ardito, Raffaele

2017-09-01

The use of Phononic Crystals (PnCs) as smart materials in structures and microstructures is growing due to their tunable dynamical properties and to the wide range of possible applications. PnCs are periodic structures that exhibit elastic wave scattering for a certain band of frequencies (called bandgap), depending on the geometric and material properties of the fundamental unit cell of the crystal. PnCs slabs can be represented by plane-extruded structures composed of a single material with periodic perforations. Such a configuration is very interesting, especially in Micro Electro-Mechanical Systems industry, due to the easy fabrication procedure. A lot of topologies can be found in the literature for PnCs with square-symmetric unit cell that exhibit complete 2D bandgaps; however, due to the application demand, it is desirable to find the best topologies in order to guarantee full bandgaps referred to in-plane wave propagation in the complete 3D structure. In this work, by means of a novel and fast implementation of the Bidirectional Evolutionary Structural Optimization technique, shape optimization is conducted on the hole shape obtaining several topologies, also with non-square-symmetric unit cell, endowed with complete 3D full bandgaps for in-plane waves. Model order reduction technique is adopted to reduce the computational time in the wave dispersion analysis. The 3D features of the PnC unit cell endowed with the widest full bandgap are then completely analyzed, paying attention to engineering design issues.

Necessary conditions for the initiation and propagation of nuclear-detonation waves in plane atmospheres

International Nuclear Information System (INIS)

Weaver, T.A.; Wood, L.

1979-01-01

The basic conditions for the initiation of a nuclear-detonation wave in an atmosphere having plane symmetry (e.g., a thin, layered fluid envelope on a planet or star) are developed. Two classes of such a detonation are identified: those in which the temperature of the plasma is comparable to that of the electromagnetic radiation permeating it, and those in which the temperature of the plasma is much higher. Necessary conditions are developed for the propagation of such detonation waves for an arbitrarily great distance. The contribution of fusion chain reactions to these processes is evaluated. By means of these considerations, it is shown that neither the atmosphere nor oceans of the Earth may be made to undergo propagating nuclear detonation under any circumstances

Propagation of symmetric and anti-symmetric surface waves in aself-gravitating magnetized dusty plasma layer with generalized (r, q) distribution

Science.gov (United States)

Lee, Myoung-Jae; Jung, Young-Dae

2018-05-01

The dispersion properties of surface dust ion-acoustic waves in a self-gravitating magnetized dusty plasma layer with the (r, q) distribution are investigated. The result shows that the wave frequency of the symmetric mode in the plasma layer decreases with an increase in the wave number. It is also shown that the wave frequency of the symmetric mode decreases with an increase in the spectral index r. However, the wave frequency of the anti-symmetric mode increases with an increase in the wave number. It is also found that the anti-symmetric mode wave frequency increases with an increase in the spectral index r. In addition, it is found that the influence of the self-gravitation on the symmetric mode wave frequency decreases with increasing scaled Jeans frequency. Moreover, it is found that the wave frequency of the symmetric mode increases with an increase in the dust charge; however, the anti-symmetric mode shows opposite behavior.

High frequency guided wave propagation in monocrystalline silicon wafers

Science.gov (United States)

Pizzolato, Marco; Masserey, Bernard; Robyr, Jean-Luc; Fromme, Paul

2017-04-01

Monocrystalline silicon wafers are widely used in the photovoltaic industry for solar panels with high conversion efficiency. The cutting process can introduce micro-cracks in the thin wafers and lead to varying thickness. High frequency guided ultrasonic waves are considered for the structural monitoring of the wafers. The anisotropy of the monocrystalline silicon leads to variations of the wave characteristics, depending on the propagation direction relative to the crystal orientation. Full three-dimensional Finite Element simulations of the guided wave propagation were conducted to visualize and quantify these effects for a line source. The phase velocity (slowness) and skew angle of the two fundamental Lamb wave modes (first anti-symmetric mode A0 and first symmetric mode S0) for varying propagation directions relative to the crystal orientation were measured experimentally. Selective mode excitation was achieved using a contact piezoelectric transducer with a custom-made wedge and holder to achieve a controlled contact pressure. The out-of-plane component of the guided wave propagation was measured using a noncontact laser interferometer. Good agreement was found with the simulation results and theoretical predictions based on nominal material properties of the silicon wafer.

Photonic antenna enhanced middle wave and longwave infrared focal plane array with low noise and high operating temperature, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Photodetectors and focal plane arrays (FPAs) covering the middle-wave and longwave infrared (MWIR/LWIR) are of great importance in numerous NASA applications,...

Validation of the k-filtering technique for a signal composed of random-phase plane waves and non-random coherent structures

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 effect of sources on horizons that may develop when plane gravitational waves collide

International Nuclear Information System (INIS)

Chandrasekhar, Subrahmanyan; Xanthopoulos, B.C.

1987-01-01

Colliding plane gravitational waves that lead to the development of a horizon and a subsequent time-like singularity are coupled with an electromagnetic field, a perfect fluid, and null dust (consisting of massless particles). The coupling of the gravitational waves with an electromagnetic field does not affect, in any essential way, the development of the horizon or the time-like singularity if the polarizations of the colliding gravitational waves are not parallel. If the polarizations are parallel, the space-like singularity which occurs in the vacuum is transformed into a horizon followed by a three-dimensional time-like singularity by the merest presence of the electromagnetic field. The coupling of the gravitational waves with a perfect fluid and null dust affect the development of horizons and singularities in radically different ways: the perfect fluid affects the development decisively in all cases but qualitatively in the same way, while null dust prevents the development of horizons and allows only the development of space-like singularities. The contrasting behaviours of a perfect fluid and of null dust in the framework of general relativity is compared with the behaviours one may expect, under similar circumstances, in the framework of special relativity. (author)

Connection between in-plane upper critical field Hc 2 and gap symmetry in layered d -wave superconductors

Science.gov (United States)

Wang, Jing-Rong; Liu, Guo-Zhu; Zhang, Chang-Jin

2016-07-01

Angle-resolved upper critical field Hc 2 provides an efficient tool to probe the gap symmetry of unconventional superconductors. We revisit the behavior of in-plane Hc 2 in d -wave superconductors by considering both the orbital effect and Pauli paramagnetic effect. After carrying out systematic analysis, we show that the maxima of Hc 2 could be along either nodal or antinodal directions of a d -wave superconducting gap, depending on the specific values of a number of tuning parameters. This behavior is in contrast to the common belief that the maxima of in-plane Hc 2 are along the direction where the superconducting gap takes its maximal value. Therefore, identifying the precise d -wave gap symmetry through fitting experiments results of angle-resolved Hc 2 with model calculations at a fixed temperature, as widely used in previous studies, is difficult and practically unreliable. However, our extensive analysis of angle-resolved Hc 2 show that there is a critical temperature T*: in-plane Hc 2 exhibits its maxima along nodal directions at T change as other parameters vary, but the existence of π /4 shift of Hc 2 at T* appears to be a general feature. Thus a better method to identify the precise d -wave gap symmetry is to measure Hc 2 at a number of different temperatures, and examine whether there is a π /4 shift in its angular dependence at certain T*. We further show that Landau level mixing does not change this general feature. However, in the presence of Fulde-Ferrell-Larkin-Ovchinnikov state, the angular dependence of Hc 2 becomes quite complicated, which makes it more difficult to determine the gap symmetry by measuring Hc 2. Our results indicate that some previous studies on the gap symmetry of CeCu2Si2 are unreliable and need to be reexamined, and also provide a candidate solution to an experimental discrepancy in the angle-resolved Hc 2 in CeCoIn5.

Correction of the near threshold behavior of electron collisional excitation cross-sections in the plane-wave Born approximation

Science.gov (United States)

Kilcrease, D. P.; Brookes, S.

2013-12-01

The modeling of NLTE plasmas requires the solution of population rate equations to determine the populations of the various atomic levels relevant to a particular problem. The equations require many cross sections for excitation, de-excitation, ionization and recombination. A simple and computational fast way to calculate electron collisional excitation cross-sections for ions is by using the plane-wave Born approximation. This is essentially a high-energy approximation and the cross section suffers from the unphysical problem of going to zero near threshold. Various remedies for this problem have been employed with varying degrees of success. We present a correction procedure for the Born cross-sections that employs the Elwert-Sommerfeld factor to correct for the use of plane waves instead of Coulomb waves in an attempt to produce a cross-section similar to that from using the more time consuming Coulomb Born approximation. We compare this new approximation with other, often employed correction procedures. We also look at some further modifications to our Born Elwert procedure and its combination with Y.K. Kim's correction of the Coulomb Born approximation for singly charged ions that more accurately approximate convergent close coupling calculations.

C-plane Reconstructions from Sheaf Acquisition for Ultrasound Electrode Vibration Elastography.

Science.gov (United States)

Ingle, Atul; Varghese, Tomy

2014-09-03

This paper presents a novel algorithm for reconstructing and visualizing ablated volumes using radiofrequency ultrasound echo data acquired with the electrode vibration elastography approach. The ablation needle is vibrated using an actuator to generate shear wave pulses that are tracked in the ultrasound image plane at different locations away from the needle. This data is used for reconstructing shear wave velocity maps for each imaging plane. A C-plane reconstruction algorithm is proposed which estimates shear wave velocity values on a collection of transverse planes that are perpendicular to the imaging planes. The algorithm utilizes shear wave velocity maps from different imaging planes that share a common axis of intersection. These C-planes can be used to generate a 3D visualization of the ablated region. Experimental validation of this approach was carried out using data from a tissue mimicking phantom. The shear wave velocity estimates were within 20% of those obtained from a clinical scanner, and a contrast of over 4 dB was obtained between the stiff and soft regions of the phantom.

The Fermionic Signature Operator and Hadamard States in the Presence of a Plane Electromagnetic Wave

Science.gov (United States)

Finster, Felix; Reintjes, Moritz

2017-05-01

We give a non-perturbative construction of a distinguished state for the quantized Dirac field in Minkowski space in the presence of a time-dependent external field of the form of a plane electromagnetic wave. By explicit computation of the fermionic signature operator, it is shown that the Dirac operator has the strong mass oscillation property. We prove that the resulting fermionic projector state is a Hadamard state.

Perturbation theory for the Bethe-Salpeter equation in the field of a plane electromagnetic wave

International Nuclear Information System (INIS)

Starostin, V.S.; Litskevich, I.K.

1990-01-01

The completeness and orthogonality of the solutions of the Bethe-Salpeter equation is proven. A correct derivation of perturbation-theory equations is given. A generalization that includes the field of a plane electromagnetic wave is proposed. The rate of one-photon annihilation of positronium in this field is calculated. If the one-photon decay is allowed, the stationary states of the system are found (states of light-positronium)

Spin-wave logic devices based on isotropic forward volume magnetostatic waves

International Nuclear Information System (INIS)

Klingler, S.; Pirro, P.; Brächer, T.; Leven, B.; Hillebrands, B.; Chumak, A. V.

2015-01-01

We propose the utilization of isotropic forward volume magnetostatic spin waves in modern wave-based logic devices and suggest a concrete design for a spin-wave majority gate operating with these waves. We demonstrate by numerical simulations that the proposed out-of-plane magnetized majority gate overcomes the limitations of anisotropic in-plane magnetized majority gates due to the high spin-wave transmission through the gate, which enables a reduced energy consumption of these devices. Moreover, the functionality of the out-of-plane majority gate is increased due to the lack of parasitic generation of short-wavelength exchange spin waves

Spin-wave logic devices based on isotropic forward volume magnetostatic waves

Energy Technology Data Exchange (ETDEWEB)

Klingler, S., E-mail: stefan.klingler@wmi.badw-muenchen.de; Pirro, P.; Brächer, T.; Leven, B.; Hillebrands, B.; Chumak, A. V. [Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern (Germany)

2015-05-25

We propose the utilization of isotropic forward volume magnetostatic spin waves in modern wave-based logic devices and suggest a concrete design for a spin-wave majority gate operating with these waves. We demonstrate by numerical simulations that the proposed out-of-plane magnetized majority gate overcomes the limitations of anisotropic in-plane magnetized majority gates due to the high spin-wave transmission through the gate, which enables a reduced energy consumption of these devices. Moreover, the functionality of the out-of-plane majority gate is increased due to the lack of parasitic generation of short-wavelength exchange spin waves.

Plane-wave diffraction by periodic structures with artificial anisotropic dielectrics

International Nuclear Information System (INIS)

Kazerooni, Azadeh Semsar; Shahabadi, Mahmoud

2010-01-01

Periodic structures with artificial anisotropic dielectrics are studied. The artificial anisotropic dielectric material in this work is made of two alternating isotropic dielectric layers. By a proper choice of the dielectric constant of the layers, we can realize a uniaxial anisotropic medium with controllable anisotropy. The artificial anisotropic dielectric is then used in periodic structures. For these structures, the optical axis of the artificial dielectric is assumed to be parallel or perpendicular to the period of the structure. Diffraction of plane waves by these structures is analyzed by a fully vectorial rigorous matrix method based on a generalized transmission line (TL) formulation. The propagation constants and field distributions are computed and diffraction properties of such structures are studied to show that, by a proper choice of structural parameters, these periodic structures with artificial anisotropic dielectrics can be used as polarizers or polarizing mirrors

Three-wave interaction in two-component quadratic nonlinear lattices

DEFF Research Database (Denmark)

Konotop, V. V.; Cunha, M. D.; Christiansen, Peter Leth

1999-01-01

We investigate a two-component lattice with a quadratic nonlinearity and find with the multiple scale technique that integrable three-wave interaction takes place between plane wave solutions when these fulfill resonance conditions. We demonstrate that. energy conversion and pulse propagation known...... from three-wave interaction is reproduced in the lattice and that exact phase matching of parametric processes can be obtained in non-phase-matched lattices by tilting the interacting plane waves with respect to each other. [S1063-651X(99)15110-9]....

A semi-analytical approach towards plane wave analysis of local resonance metamaterials using a multiscale enriched continuum description

NARCIS (Netherlands)

Sridhar, A.; Kouznetsova, V.; Geers, M.G.D.

2017-01-01

This work presents a novel multiscale semi-analytical technique for the acoustic plane wave analysis of (negative) dynamic mass density type local resonance metamaterials with complex micro-structural geometry. A two step solution strategy is adopted, in which the unit cell problem at the

Dirac electron in a chiral space-time crystal created by counterpropagating circularly polarized plane electromagnetic waves

Science.gov (United States)

Borzdov, G. N.

2017-10-01

The family of solutions to the Dirac equation for an electron moving in an electromagnetic lattice with the chiral structure created by counterpropagating circularly polarized plane electromagnetic waves is obtained. At any nonzero quasimomentum, the dispersion equation has two solutions which specify bispinor wave functions describing electron states with different energies and mean values of momentum and spin operators. The inversion of the quasimomentum results in two other linearly independent solutions. These four basic wave functions are uniquely defined by eight complex scalar functions (structural functions), which serve as convenient building blocks of the relations describing the electron properties. These properties are illustrated in graphical form over a wide range of quasimomenta. The superpositions of two basic wave functions describing different spin states and corresponding to (i) the same quasimomentum (unidirectional electron states with the spin precession) and (ii) the two equal-in-magnitude but oppositely directed quasimomenta (bidirectional electron states) are also treated.

P-Wave and S-Wave Velocity Structure of Submarine Landslide Associated With Gas Hydrate Layer on Frontal Ridge of Northern Cascadia Margin

Science.gov (United States)

He, T.; Lu, H.; Yelisetti, S.; Spence, G.

2015-12-01

The submarine landslide associated with gas hydrate is a potential risk for environment and engineering projects, and thus from long time ago it has been a hot topic of hydrate research. The study target is Slipstream submarine landslide, one of the slope failures observed on the frontal ridges of the Northern Cascadia accretionary margin off Vancouver Island. The previous studies indicated a possible connection between this submarine landslide feature and gas hydrate, whose occurrence is indicated by a prominent bottom-simulating reflector (BSR), at a depth of ~265-275 m beneath the seafloor (mbsf). The OBS (Ocean Bottom Seismometer) data collected during SeaJade (Seafloor Earthquake Array - Japan Canada Cascadia Experiment) project were used to derive the subseafloor velocity structure for both P- and S-wave using travel times picked from refraction and reflection events. The P-wave velocity structure above the BSR showed anomalous high velocities of about 2.0 km/s at shallow depths of 100 mbsf, closely matching the estimated depth of the glide plane (100 ± 10 m). Forward modelling of S-waves was carried out using the data from the OBS horizontal components. The S-wave velocities, interpreted in conjunction with the P-wave results, provide the key constraints on the gas hydrate distribution within the pores. The hydrate distribution in the pores is important for determining concentrations, and also for determining the frame strength which is critical for controlling slope stability of steep frontal ridges. The increase in S-wave velocity suggests that the hydrate is distributed as part of the load-bearing matrix to increase the rigidity of the sediment.

Note on s anti s-production in anti p-nucleus reactions at 607 MeV/c incident momentum

International Nuclear Information System (INIS)

Breivik, F.O.; Haatuft, A.; Halsteinslid, A.

1990-01-01

The measured cross sections for K o s and Λ o (Σ o ) production in anti pA reactions at 607 MeV/c incident momentum, and the number of quark recombinations, give the cross section σ(s anti s) for strange particle production for target nuclei with A= 2, 4 and 20 nucleons, respectively. The result favours the relation σ(s anti s) ∝ A 1/3 . Scattering of an antiquark off a virtual s anti s-pair, or gluon Bremsstrahlung emitted by scattering of an incident antiquark passing through nuclear matter, are possible processes consistent with this relation. Models inconsistent with the relation may be wrong. 4 refs.; 2 tabs

Semipolar GaN grown on m-plane sapphire using MOVPE

Energy Technology Data Exchange (ETDEWEB)

Wernicke, Tim; Netzel, Carsten; Weyers, Markus [Ferdinand-Braun-Institut fuer Hoechstfrequenztechnik, Berlin (Germany); Kneissl, Michael [Ferdinand-Braun-Institut fuer Hoechstfrequenztechnik, Berlin (Germany); Institute of Solid State Physics, Technical University of Berlin (Germany)

2008-07-01

We have investigated the MOVPE growth of semipolar gallium nitride (GaN) films on (10 anti 1 0) m-plane sapphire substrates. Specular GaN films with a RMS roughness (10 x 10 {mu}m{sup 2}) of 15.2 nm were obtained and an arrowhead like structure aligned along[ anti 2 113] is prevailing. The orientation relationship was determined by XRD and yielded (212){sub GaN} parallel (10 anti 10){sub sapphire} and [anti 2113]{sub GaN} parallel [0001]{sub sapphire} as well as [anti 2113]{sub GaN} parallel [000 anti 1]{sub sapphire}. PL spectra exhibited near band edge emission accompanied by a strong basal plane stacking fault emission. In addition lower energy peaks attributed to prismatic plane stacking faults and donor acceptor pair emission appeared in the spectrum. With similar growth conditions also (1013) GaN films on m-plane sapphire were obtained. In the later case we found that the layer was twinned, crystallites with different c-axis orientation were present. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Wigner functions of s waves

International Nuclear Information System (INIS)

Dahl, J. P.; Varro, S.; Wolf, A.; Schleich, W. P.

2007-01-01

We derive explicit expressions for the Wigner function of wave functions in D dimensions which depend on the hyperradius--that is, of s waves. They are based either on the position or the momentum representation of the s wave. The corresponding Wigner function depends on three variables: the absolute value of the D-dimensional position and momentum vectors and the angle between them. We illustrate these expressions by calculating and discussing the Wigner functions of an elementary s wave and the energy eigenfunction of a free particle

Wigner functions of s waves

DEFF Research Database (Denmark)

Dahl, Jens Peder; Varro, S.; Wolf, A.

2007-01-01

We derive explicit expressions for the Wigner function of wave functions in D dimensions which depend on the hyperradius-that is, of s waves. They are based either on the position or the momentum representation of the s wave. The corresponding Wigner function depends on three variables......: the absolute value of the D-dimensional position and momentum vectors and the angle between them. We illustrate these expressions by calculating and discussing the Wigner functions of an elementary s wave and the energy eigenfunction of a free particle....

Temporal change in shallow subsurface P- and S-wave velocities and S-wave anisotropy inferred from coda wave interferometry

Science.gov (United States)

Yamamoto, M.; Nishida, K.; Takeda, T.

2012-12-01

Recent progresses in theoretical and observational researches on seismic interferometry reveal the possibility to detect subtle change in subsurface seismic structure. This high sensitivity of seismic interferometry to the medium properties may thus one of the most important ways to directly observe the time-lapse behavior of shallow crustal structure. Here, using the coda wave interferometry, we show the co-seismic and post-seismic changes in P- and S-wave velocities and S-wave anisotropy associated with the 2011 off the Pacific coast of Tohoku earthquake (M9.0). In this study, we use the acceleration data recorded at KiK-net stations operated by NIED, Japan. Each KiK-net station has a borehole whose typical depth is about 100m, and two three-component accelerometers are installed at the top and bottom of the borehole. To estimate the shallow subsurface P- and S-wave velocities and S-wave anisotropy between two sensors and their temporal change, we select about 1000 earthquakes that occurred between 2004 and 2012, and extract body waves propagating between borehole sensors by computing the cross-correlation functions (CCFs) of 3 x 3 component pairs. We use frequency bands of 2-4, 4-8, 8-16 Hz in our analysis. Each averaged CCF shows clear wave packets traveling between borehole sensors, and their travel times are almost consistent with those of P- and S-waves calculated from the borehole log data. Until the occurrence of the 2011 Tohoku earthquake, the estimated travel time at each station is rather stable with time except for weak seasonal/annual variation. On the other hand, the 2011 Tohoku earthquake and its aftershocks cause sudden decrease in the S-wave velocity at most of the KiK-net stations in eastern Japan. The typical value of S-wave velocity changes, which are measured by the time-stretching method, is about 5-15%. After this co-seismic change, the S-wave velocity gradually recovers with time, and the recovery continues for over one year following the

Magnetism of hexagonal close-packed nickel calculated by full-potential linearized augmented plane wave method

International Nuclear Information System (INIS)

Tian, F.; Tian, H.; Whitmore, L.; Ye, L.Y.

2015-01-01

The energy dependent on volume of hexagonal close-packed (hcp) nickel with different magnetism is calculated by full-potential linearized augmented plane wave method. Based on the calculation ferromagnetic state is found to be the most stable state. The magnetic moment of hcp Ni is calculated and compared to those calculated by different pseudo-potential methods. Furthermore, it is also compared to that of face-centered cubic (fcc) one with the reason discussed

Multigrid Computation of Stratified Flow over Two-Dimensional Obstacles

Science.gov (United States)

Paisley, M. F.

1997-09-01

A robust multigrid method for the incompressible Navier-Stokes equations is presented and applied to the computation of viscous flow over obstacles in a bounded domain under conditions of neutral stability and stable density stratification. Two obstacle shapes have been used, namely a vertical barrier, for which the grid is Cartesian, and a smooth cosine-shaped obstacle, for which a boundary-conforming transformation is incorporated. Results are given for laminar flows at low Reynolds numbers and turbulent flows at a high Reynolds number, when a simple mixing length turbulence model is included. The multigrid algorithm is used to compute steady flows for each obstacle at low and high Reynolds numbers in conditions of weak static stability, defined byK=ND/πU≤ 1, whereU,N, andDare the upstream velocity, bouyancy frequency, and domain height respectively. Results are also presented for the vertical barrier at low and high Reynolds number in conditions of strong static stability,K> 1, when lee wave motions ensure that the flow is unsteady, and the multigrid algorithm is used to compute the flow at each timestep.

Propagation properties of Rossby waves for latitudinal β-plane variations of f and zonal variations of the shallow water speed

Directory of Open Access Journals (Sweden)

C. T. Duba

2012-05-01

Full Text Available Using the shallow water equations for a rotating layer of fluid, the wave and dispersion equations for Rossby waves are developed for the cases of both the standard β-plane approximation for the latitudinal variation of the Coriolis parameter f and a zonal variation of the shallow water speed. It is well known that the wave normal diagram for the standard (mid-latitude Rossby wave on a β-plane is a circle in wave number (ky,kx space, whose centre is displaced −β/2 ω units along the negative kx axis, and whose radius is less than this displacement, which means that phase propagation is entirely westward. This form of anisotropy (arising from the latitudinal y variation of f, combined with the highly dispersive nature of the wave, gives rise to a group velocity diagram which permits eastward as well as westward propagation. It is shown that the group velocity diagram is an ellipse, whose centre is displaced westward, and whose major and minor axes give the maximum westward, eastward and northward (southward group speeds as functions of the frequency and a parameter m which measures the ratio of the low frequency-long wavelength Rossby wave speed to the shallow water speed. We believe these properties of group velocity diagram have not been elucidated in this way before. We present a similar derivation of the wave normal diagram and its associated group velocity curve for the case of a zonal (x variation of the shallow water speed, which may arise when the depth of an ocean varies zonally from a continental shelf.

Relation between the occurrence of Burnout and differential pressure fluctuation characteristics caused by the disturbance waves passing by a flow obstacle in a vertical boiling two-phase upward flow in a narrow annular channel

Energy Technology Data Exchange (ETDEWEB)

Mori, Shoji [Yokohama National University, Yokohama 240-8501 (Japan)]. E-mail: morisho@ynu.ac.jp; Fukano, Tohru [Kurume Institute of University, Fukuoka 830-0052 (Japan)]. E-mail: fukanot@cc.kurume-it.ac.jp

2006-05-15

If a flow obstacle such as a spacer is placed in a boiling two-phase flow within a channel, the temperature on the surface of the heating tube is severely affected by the existence of the spacer. Under certain conditions the spacer has a cooling effect, and under other conditions the spacer causes dryout of the cooling water film on the heating surface, resulting in burnout of the tube. The burnout mechanism near the spacer, however, remains unclear. In a previous paper (Fukano, T., Mori, S., Akamatsu, S., Baba, A., 2002. Relation between temperature fluctuation of a heating surface and generation of drypatch caused by a cylindrical spacer in a vertical boiling two-phase upward flow in a narrow annular channel. Nucl. Eng. Des. 217, 81-90), we reported that the disturbance wave has a significant effect on dryout occurrence. Therefore, in the present paper, the relation between dryout, burnout occurrence, and interval between two successive disturbance waves obtained from the differential pressure fluctuation caused by the disturbance waves passing by a spacer, is further discussed in detail.

Relation between the occurrence of Burnout and differential pressure fluctuation characteristics caused by the disturbance waves passing by a flow obstacle in a vertical boiling two-phase upward flow in a narrow annular channel

International Nuclear Information System (INIS)

Mori, Shoji; Fukano, Tohru

2006-01-01

If a flow obstacle such as a spacer is placed in a boiling two-phase flow within a channel, the temperature on the surface of the heating tube is severely affected by the existence of the spacer. Under certain conditions the spacer has a cooling effect, and under other conditions the spacer causes dryout of the cooling water film on the heating surface, resulting in burnout of the tube. The burnout mechanism near the spacer, however, remains unclear. In a previous paper (Fukano, T., Mori, S., Akamatsu, S., Baba, A., 2002. Relation between temperature fluctuation of a heating surface and generation of drypatch caused by a cylindrical spacer in a vertical boiling two-phase upward flow in a narrow annular channel. Nucl. Eng. Des. 217, 81-90), we reported that the disturbance wave has a significant effect on dryout occurrence. Therefore, in the present paper, the relation between dryout, burnout occurrence, and interval between two successive disturbance waves obtained from the differential pressure fluctuation caused by the disturbance waves passing by a spacer, is further discussed in detail

Phase Plane Analysis Method of Nonlinear Traffic Phenomena

Directory of Open Access Journals (Sweden)

Wenhuan Ai

2015-01-01

Full Text Available A new phase plane analysis method for analyzing the complex nonlinear traffic phenomena is presented in this paper. This method makes use of variable substitution to transform a traditional traffic flow model into a new model which is suitable for the analysis in phase plane. According to the new model, various traffic phenomena, such as the well-known shock waves, rarefaction waves, and stop-and-go waves, are analyzed in the phase plane. From the phase plane diagrams, we can see the relationship between traffic jams and system instability. So the problem of traffic flow could be converted into that of system stability. The results show that the traffic phenomena described by the new method is consistent with that described by traditional methods. Moreover, the phase plane analysis highlights the unstable traffic phenomena we are chiefly concerned about and describes the variation of density or velocity with time or sections more clearly.

Controlling the position of a stabilized detonation wave in a supersonic gas mixture flow in a plane channel

Science.gov (United States)

Levin, V. A.; Zhuravskaya, T. A.

2017-03-01

Stabilization of a detonation wave in a stoichiometric hydrogen-air mixture flowing at a supersonic velocity into a plane symmetric channel with constriction has been studied in the framework of a detailed kinetic mechanism of the chemical interaction. Conditions ensuring the formation of a thrust-producing f low with a stabilized detonation wave in the channel are determined. The inf luence of the inf low Mach number, dustiness of the combustible gas mixture supplied to the channel, and output cross-section size on the position of a stabilized detonation wave in the f low has been analyzed with a view to increasing the efficiency of detonation combustion of the gas mixture. It is established that thrust-producing flow with a stabilized detonation wave can be formed in the channel without any energy consumption.

Pristine Basal- and Edge-Plane-Oriented Molybdenite MoS2 Exhibiting Highly Anisotropic Properties.

Science.gov (United States)

Tan, Shu Min; Ambrosi, Adriano; Sofer, Zdenĕk; Huber, Štěpán; Sedmidubský, David; Pumera, Martin

2015-05-04

The layered structure of molybdenum disulfide (MoS2 ) is structurally similar to that of graphite, with individual sheets strongly covalently bonded within but held together through weak van der Waals interactions. This results in two distinct surfaces of MoS2 : basal and edge planes. The edge plane was theoretically predicted to be more electroactive than the basal plane, but evidence from direct experimental comparison is elusive. Herein, the first study comparing the two surfaces of MoS2 by using macroscopic crystals is presented. A careful investigation of the electrochemical properties of macroscopic MoS2 pristine crystals with precise control over the exposure of one plane surface, that is, basal plane or edge plane, was performed. These crystals were characterized thoroughly by AFM, Raman spectroscopy, X-ray photoelectron spectroscopy, voltammetry, digital simulation, and DFT calculations. In the Raman spectra, the basal and edge planes show anisotropy in the preferred excitation of E2g and A1g phonon modes, respectively. The edge plane exhibits a much larger heterogeneous electron transfer rate constant k(0) of 4.96×10(-5) and 1.1×10(-3)  cm s(-1) for [Fe(CN)6 ](3-/4-) and [Ru(NH3 )6 ](3+/2+) redox probes, respectively, compared to the basal plane, which yielded k(0) tending towards zero for [Fe(CN)6 ](3-/4-) and about 9.3×10(-4)  cm s(-1) for [Ru(NH3 )6 ](3+/2+) . The industrially important hydrogen evolution reaction follows the trend observed for [Fe(CN)6 ](3-/4-) in that the basal plane is basically inactive. The experimental comparison of the edge and basal planes of MoS2 crystals is supported by DFT calculations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Obstacle detection system for underground mining vehicles

Energy Technology Data Exchange (ETDEWEB)

Cohen, P.; Polotski, V.; Piotte, M.; Melamed, F. [Ecole Polytechnique de Montreal, Montreal, PQ (Canada)

1998-01-01

A device for detecting obstacles by autonomous vehicles navigating in mine drifts is described. The device is based upon structured lighting and the extraction of relevant features from images of obstacles. The system uses image profile changes, ground and wall irregularities, disturbances of the vehicle`s trajectory, and impaired visibility to detect obstacles, rather than explicit three-dimensional scene reconstruction. 7 refs., 5 figs.

anti B_d_,_s → D"*_d_,_sV and anti B"*_d_,_s → D_d_,_sV decays in QCD factorization and possible puzzles

International Nuclear Information System (INIS)

Chang, Qin; Chen, Ling-Xin; Zhang, Yun-Yun; Sun, Jun-Feng; Yang, Yue-Ling

2016-01-01

Motivated by the rapid development of heavy-flavor experiments, phenomenological studies of nonleptonic anti B_d_,_s → D"*_d_,_sV and anti B"*_d_,_s → D_d_,_sV (V = ρ, K*) decays are performed within the framework of QCD factorization. Relative to the previous work, the QCD corrections to the transverse amplitudes are evaluated at next-to-leading order. The theoretical predictions of the observables are updated. For the measured anti B_d_,_s → D"*_d_,_sV decays, the tensions between theoretical results and experimental measurements, i.e. the ''R_d_s"V puzzle'' and ''D*V (or R_V_/_l _a_n_t_i _ν__l_) puzzle'', are presented after detailed analyses. For the anti B"*_d_,_s → D_d_,_sV decays, they have relatively large branching fractions of the order >or similar O(10"-"9) and are in the scope of Belle-II and LHCb experiments. Moreover, they also provide a way to crosscheck the possible puzzles mentioned above through the similar ratios R_d_s"'"V and R"'_V_/_l _a_n_t_i _ν__l_. More refined experimental measurements and theoretical efforts are required to confirm or refute such two anomalies. (orig.)

Spin effects in nonlinear Compton scattering in a plane-wave laser pulse

International Nuclear Information System (INIS)

Boca, Madalina; Dinu, Victor; Florescu, Viorica

2012-01-01

We study theoretically the electron angular and energy distribution in the non-linear Compton effect in a finite plane-wave laser pulse. We first present analytical and numerical results for unpolarized electrons (described by a Volkov solution of the Dirac equation), in comparison with those corresponding to a spinless particle (obeying the Klein–Gordon equation). Then, in the spin 1/2 case, we include results for the spin flip probability. The regime in which the spin effects are negligible, i.e. the results for the unpolarized spin 1/2 particle coincide practically with those for the spinless particle, is the same as the regime in which the emitted radiation is well described by classical electrodynamics.

Mittag–Leffler's function, Vekua transform and an inverse obstacle scattering problem

International Nuclear Information System (INIS)

Ikehata, Masaru

2010-01-01

This paper studies a prototype of inverse obstacle scattering problems whose governing equation is the Helmholtz equation in two dimensions. An explicit method to extract information about the location and shape of unknown obstacles from the far-field operator with a fixed wave number is given. The method is based on an explicit construction of a modification of Mittag–Leffler's function via the Vekua transform and the study of the asymptotic behaviour; an explicit density in the Herglotz wavefunction that approximates the modification of Mittag–Leffler's function in the bounded domain surrounding unknown obstacles; a system of inequalities derived from Kirsch's factorization formula of the far-field operator. Then an indicator function which can be calculated from the far-field operator acting on the density is introduced. It is shown that the asymptotic behaviour of the indicator function yields information about the visible part of the exterior of the obstacles

Excited state nuclear forces from the Tamm-Dancoff approximation to time-dependent density functional theory within the plane wave basis set framework

Science.gov (United States)

Hutter, Jürg

2003-03-01

An efficient formulation of time-dependent linear response density functional theory for the use within the plane wave basis set framework is presented. The method avoids the transformation of the Kohn-Sham matrix into the canonical basis and references virtual orbitals only through a projection operator. Using a Lagrangian formulation nuclear derivatives of excited state energies within the Tamm-Dancoff approximation are derived. The algorithms were implemented into a pseudo potential/plane wave code and applied to the calculation of adiabatic excitation energies, optimized geometries and vibrational frequencies of three low lying states of formaldehyde. An overall good agreement with other time-dependent density functional calculations, multireference configuration interaction calculations and experimental data was found.

In-plane and cross-plane thermal conductivities of molybdenum disulfide

International Nuclear Information System (INIS)

Ding, Zhiwei; Pei, Qing-Xiang; Zhang, Yong-Wei; Jiang, Jin-Wu

2015-01-01

We investigate the in-plane and cross-plane thermal conductivities of molybdenum disulfide (MoS 2 ) using non-equilibrium molecular dynamics simulations. We find that the in-plane thermal conductivity of monolayer MoS 2 is about 19.76 W mK −1 . Interestingly, the in-plane thermal conductivity of multilayer MoS 2 is insensitive to the number of layers, which is in strong contrast to the in-plane thermal conductivity of graphene where the interlayer interaction strongly affects the in-plane thermal conductivity. This layer number insensitivity is attributable to the finite energy gap in the phonon spectrum of MoS 2 , which makes the phonon–phonon scattering channel almost unchanged with increasing layer number. For the cross-plane thermal transport, we find that the cross-plane thermal conductivity of multilayer MoS 2 can be effectively tuned by applying cross-plane strain. More specifically, a 10% cross-plane compressive strain can enhance the thermal conductivity by a factor of 10, while a 5% cross-plane tensile strain can reduce the thermal conductivity by 90%. Our findings are important for thermal management in MoS 2 based nanodevices and for thermoelectric applications of MoS 2 . (paper)

Seismic shear waves as Foucault pendulum

Science.gov (United States)

Snieder, Roel; Sens-Schönfelder, Christoph; Ruigrok, Elmer; Shiomi, Katsuhiko

2016-03-01

Earth's rotation causes splitting of normal modes. Wave fronts and rays are, however, not affected by Earth's rotation, as we show theoretically and with observations made with USArray. We derive that the Coriolis force causes a small transverse component for P waves and a small longitudinal component for S waves. More importantly, Earth's rotation leads to a slow rotation of the transverse polarization of S waves; during the propagation of S waves the particle motion behaves just like a Foucault pendulum. The polarization plane of shear waves counteracts Earth's rotation and rotates clockwise in the Northern Hemisphere. The rotation rate is independent of the wave frequency and is purely geometric, like the Berry phase. Using the polarization of ScS and ScS2 waves, we show that the Foucault-like rotation of the S wave polarization can be observed. This can affect the determination of source mechanisms and the interpretation of observed SKS splitting.

In-plane confinement and waveguiding of surface acoustic waves through line defects in pillars-based phononic crystal

Directory of Open Access Journals (Sweden)

Abdelkrim Khelif

2011-12-01

Full Text Available We present a theoretical analysis of an in-plane confinement and a waveguiding of surface acoustic waves in pillars-based phononic crystal. The artificial crystal is made up of cylindrical pillars placed on a semi-infinite medium and arranged in a square array. With a well-chosen of the geometrical parameters, this pillars-based system can display two kinds of complete band gaps for guided waves propagating near the surface, a low frequency gap based on locally resonant mode of pillars as well as a higher frequency gap appearing at Bragg scattering regime. In addition, we demonstrate a waveguiding of surface acoustic wave inside an extended linear defect created by removing rows of pillars in the perfect crystal. We discuss the transmission and the polarization of such confined mode appearing in the higher frequency band gap. We highlight the strong similarity of such defect mode and the Rayleigh wave of free surface medium. An efficient finite element analysis is used to simulate the propagation of guided waves through silicon pillars on a silicon substrate.

Eikonal Approximation in AdS/CFT From Shock Waves to Four-Point Functions

CERN Document Server

Cornalba, L; Costa, Miguel S; Penedones, Joao; Cornalba, Lorenzo; Costa, M S; Penedones, J; Schiappa, Ricardo

2007-01-01

We initiate a program to generalize the standard eikonal approximation to compute amplitudes in Anti-de Sitter spacetimes. Inspired by the shock wave derivation of the eikonal amplitude in flat space, we study the two-point function E ~ _{shock} in the presence of a shock wave in Anti-de Sitter, where O_1 is a scalar primary operator in the dual conformal field theory. At tree level in the gravitational coupling, we relate the shock two-point function E to the discontinuity across a kinematical branch cut of the conformal field theory four-point function A ~ , where O_2 creates the shock geometry in Anti-de Sitter. Finally, we extend the above results by computing E in the presence of shock waves along the horizon of Schwarzschild BTZ black holes. This work gives new tools for the study of Planckian physics in Anti-de Sitter spacetimes.

Segmented Spiral Waves and Anti-phase Synchronization in a Model System with Two Identical Time-Delayed Coupled Layers

International Nuclear Information System (INIS)

Yuan Guoyong; Yang Shiping; Wang Guangrui; Chen Shigang

2008-01-01

In this paper, we consider a model system with two identical time-delayed coupled layers. Synchronization and anti-phase synchronization are exhibited in the reactive system without diffusion term. New segmented spiral waves, which are constituted by many thin trips, are found in each layer of two identical time-delayed coupled layers, and are different from the segmented spiral waves in a water-in-oil aerosol sodium bis(2-ethylhexyl) sulfosuccinate (AOT) micro-emulsion (ME) (BZ-AOT system), which consists of many small segments. 'Anti-phase spiral wave synchronization' can be realized between the first layer and the second one. For different excitable parameters, we also give the minimum values of the coupling strength to generate segmented spiral waves and the tip orbits of spiral waves in the whole bilayer.

Simulation of angle-resolved photoemission spectra by approximating the final state by a plane wave: From graphene to polycyclic aromatic hydrocarbon molecules

Energy Technology Data Exchange (ETDEWEB)

Puschnig, Peter, E-mail: peter.puschnig@uni-graz.at; Lüftner, Daniel

2015-04-15

Highlights: • Computational study on angular dependent photoemission spectroscopy. • Graphene and polycyclic aromatic hydrocarbon molecules. • Plane wave final state approximation accounts for experimental findings. - Abstract: We present a computational study on the angular-resolved photoemission spectra (ARPES) from a number of polycyclic aromatic hydrocarbons and graphene. Our theoretical approach is based on ab-initio density functional theory and the one-step model where we greatly simplify the evaluation of the matrix element by assuming a plane wave for the final state. Before comparing our ARPES simulations with available experimental data, we discuss how typical approximations for the exchange-correlation energy affect orbital energies. In particular, we show that by employing a hybrid functional, considerable improvement can be obtained over semi-local functionals in terms of band widths and relative energies of π and σ states. Our ARPES simulations for graphene show that the plane wave final state approximation provides indeed an excellent description when compared to experimental band maps and constant binding energy maps. Furthermore, our ARPES simulations for a number of polycyclic aromatic molecules from the oligo-acene, oligo-phenylene, phen-anthrene families as well as for disc-shaped molecules nicely illustrate the evolution of the electronic structure from molecules with increasing size towards graphene.

Deep Downhole Seismic Testing at the Waste Treatment Plant Site, Hanford, WA. Volume IV S-Wave Measurements in Borehole C4993 Seismic Records, Wave-Arrival Identifications and Interpreted S-Wave Velocity Profile.

Energy Technology Data Exchange (ETDEWEB)

Stokoe, Kenneth H.; Li, Song Cheng; Cox, Brady R.; Menq, Farn-Yuh

2007-06-06

In this volume (IV), all S-wave measurements are presented that were performed in Borehole C4993 at the Waste Treatment Plant (WTP) with T-Rex as the seismic source and the Lawrence Berkeley National Laboratory (LBNL) 3-D wireline geophone as the at-depth borehole receiver. S-wave measurements were performed over the depth range of 370 to 1300 ft, typically in 10-ft intervals. However, in some interbeds, 5-ft depth intervals were used, while below about 1200 ft, depth intervals of 20 ft were used. Shear (S) waves were generated by moving the base plate of T-Rex for a given number of cycles at a fixed frequency as discussed in Section 2. This process was repeated so that signal averaging in the time domain was performed using 3 to about 15 averages, with 5 averages typically used. In addition, a second average shear wave record was recorded by reversing the polarity of the motion of the T-Rex base plate. In this sense, all the signals recorded in the field were averaged signals. In all cases, the base plate was moving perpendicular to a radial line between the base plate and the borehole which is in and out of the plane of the figure shown in Figure 1.1. The definition of “in-line”, “cross-line”, “forward”, and “reversed” directions in items 2 and 3 of Section 2 was based on the moving direction of the base plate. In addition to the LBNL 3-D geophone, called the lower receiver herein, a 3-D geophone from Redpath Geophysics was fixed at a depth of 22 ft in Borehole C4993, and a 3-D geophone from the University of Texas (UT) was embedded near the borehole at about 1.5 ft below the ground surface. The Redpath geophone and the UT geophone were properly aligned so that one of the horizontal components in each geophone was aligned with the direction of horizontal shaking of the T-Rex base plate. This volume is organized into 12 sections as follows. Section 1: Introduction, Section 2: Explanation of Terminology, Section 3: Vs Profile at Borehole C4993

The D-instanton and other supersymmetric D-branes in IIB plane-wave string theory

International Nuclear Information System (INIS)

Gaberdiel, Matthias R.; Green, Michael B.

2003-01-01

A class of D-branes for the type IIB plane-wave background is considered that preserve half the dynamical supersymmetries of the light-cone gauge. The D-branes of this type are the Euclidean (or instantonic) (0,0), (0,4), and (4,0) branes (where (r,s) denotes a brane oriented with r axes in the first four directions transverse to the +, - light-cone, and s axes in the second four directions). Corresponding Lorentzian D-branes are (+,-;0,0), (+,-;0,4), and (+,-;4,0). These are constructed in two ways. The first uses a boundary state formalism which implements appropriate fermionic gluing conditions and the second is based on a direct quantization of the open strings ending on the branes. In distinction to the D-branes considered earlier these have massless world-volume fermions but do not possess kinematical supersymmetries. Cylinder diagrams describing the overlap between a pair of boundary states displaced by some distance are evaluated. The open-string description of this system involves mode frequencies that are, in general, given by irrational solutions to transcendental equations. The closed-string and open-string descriptions are shown to be equivalent by a nontrivial implementation of the S modular transformation. A classical description of the D-instanton (the (0,0) case) in light-cone gauge is also given

Rayleigh-wave phase-velocity maps and three-dimensional shear velocity structure of the western US from local non-plane surface wave tomography

Science.gov (United States)

Pollitz, F.F.; Snoke, J. Arthur

2010-01-01

We utilize two-and-three-quarter years of vertical-component recordings made by the Transportable Array (TA) component of Earthscope to constrain three-dimensional (3-D) seismic shear wave velocity structure in the upper 200 km of the western United States. Single-taper spectral estimation is used to compile measurements of complex spectral amplitudes from 44 317 seismograms generated by 123 teleseismic events. In the first step employed to determine the Rayleigh-wave phase-velocity structure, we implement a new tomographic method, which is simpler and more robust than scattering-based methods (e.g. multi-plane surface wave tomography). The TA is effectively implemented as a large number of local arrays by defining a horizontal Gaussian smoothing distance that weights observations near a given target point. The complex spectral-amplitude measurements are interpreted with the spherical Helmholtz equation using local observations about a succession of target points, resulting in Rayleigh-wave phase-velocity maps at periods over the range of 18–125 s. The derived maps depend on the form of local fits to the Helmholtz equation, which generally involve the nonplane-wave solutions of Friederich et al. In a second step, the phase-velocity maps are used to derive 3-D shear velocity structure. The 3-D velocity images confirm details witnessed in prior body-wave and surface-wave studies and reveal new structures, including a deep (>100 km deep) high-velocity lineament, of width ∼200 km, stretching from the southern Great Valley to northern Utah that may be a relic of plate subduction or, alternatively, either a remnant of the Mojave Precambrian Province or a mantle downwelling. Mantle seismic velocity is highly correlated with heat flow, Holocene volcanism, elastic plate thickness and seismicity. This suggests that shallow mantle structure provides the heat source for associated magmatism, as well as thinning of the thermal lithosphere, leading to relatively high

FDTD analysis of reflection of electromagnetic wave from a conductive plane covered with inhomogeneous time-varying plasma

International Nuclear Information System (INIS)

Liu Shaobin; Mo Jinjun; Yuan Naichang

2003-01-01

A finite-difference time-domain (FDTD) algorithm is applied to study the electro-magnetic reflection of conduction plane covered with inhomogeneous time-varying plasma, homogeneous plasma and inhomogeneous plasma. The collisions frequency of plasma is a function of electron density and plasma temperature. The number density profile follows a parabolic function. A discussion on the effect of various plasma parameters on the reflection coefficient is presented. Under the one-dimensional case, transient electromagnetic propagation through various plasmas has been obtained, and the reflection coefficients of EM wave through various plasma are calculated under different conditions. The results illustrate that a plasma cloaking system can successfully absorb the incident EM wave

Computing Strongly Homotopic Line Simplification in the Plane

DEFF Research Database (Denmark)

Daneshpajou, Shervin; Abam, Mohammad; Deleuran, Lasse Kosetski

We study a variant of the line-simplification problem where we are given a polygonal path P = p1 , p2 , . . . , pn and a set S of m point obstacles in a plane, and the goal is to find the optimal homotopic simplification, that is, a minimum subsequence Q = q1 , q2 , . . . , qk (q1 = p1 and qk = pn...... ) of P defining a polygonal path which approximates P within the given error ε and is homotopic to P . We assume all shortcuts pi,pj whose errors under a distance function F are at most ε can be computed in TF(n) time where TF(n) is polynomial for all widely-used distance functions. We define the new...

DFT LCAO and plane wave calculations of SrZrO3

International Nuclear Information System (INIS)

Evarestov, R.A.; Bandura, A.V.; Alexandrov, V.E.; Kotomin, E.A.

2005-01-01

The results of the density functional (DFT) LCAO and plane wave (PW) calculations of the electronic and structural properties of four known SrZrO 3 phases (Pm3m, I4/mcm, Cmcm and Pbnm) are presented and discussed. The calculated unit cell energies and relative stability of these phases agree well with the experimental sequence of SrZrO 3 phases as the temperature increases. The lattice structure parameters optimized in the PW calculations for all four phases are in good agreement with the experimental neutron diffraction data. The LCAO and PW results for the electronic structure, density of states and chemical bonding in the cubic phase (Pm3m) are discussed in detail and compared with the results of previous PW calculations. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Electromagnetic waves in gravitational wave spacetimes

International Nuclear Information System (INIS)

Haney, M.; Bini, D.; Ortolan, A.; Fortini, P.

2013-01-01

We have considered the propagation of electromagnetic waves in a space-time representing an exact gravitational plane wave and calculated the induced changes on the four-potential field Aμ of a plane electromagnetic wave. By choosing a suitable photon round-trip in a Michelson interferometer, we have been able to identify the physical effects of the exact gravitational wave on the electromagnetic field, i.e. phase shift, change of the polarization vector, angular deflection and delay. These results have been exploited to study the response of an interferometric gravitational wave detector beyond the linear approximation of the general theory of relativity. A much more detailed examination of this problem can be found in our paper recently published in Classical and Quantum Gravity (28 (2011) 235007).

Singularities and horizons in the collisions of gravitational waves

International Nuclear Information System (INIS)

Yurtsever, U.H.

1989-01-01

This thesis presents a study of the dynamical, nonlinear interaction of colliding gravitational waves, as described by classical general relativity. In the work on the collisions of exactly-plane waves, it is shown that Killing horizons in any plane-symmetric spacetime are unstable against small plane-symmetric perturbations. It is thus concluded that the Killing-Cauchy horizons produced by the collisions of some exactly plane gravitational waves are nongeneric, and the generic initial data for the colliding plane waves always produce pure spacetime singularities without such horizons. This conclusion is later proved rigorously (using the full nonlinear theory rather than perturbation theory), in connection with an analysis of the asymptotic singularity structure of a general colliding plane-wave spacetime. This analysis also proves that asymptotically the singularities created by colliding plane waves are of inhomogeneous-Kasner type; the asymptotic Kasner axes and exponents of these singularities in general depend on the spatial coordinate that runs tangentially to the singularity in the non-plane-symmetric direction. In the work on collisions of almost-plane gravitational waves, first some general properties of single almost-plane gravitational-wave spacetimes are explored. It is shown that, by contrast with an exact plane wave, an almost-plane gravitational wave cannot have a propagation direction that is Killing; i.e., it must diffract and disperse as it propagates. It is also shown that an almost-plane wave cannot be precisely sandwiched between two null wave-fronts; i.e., it must leave behind tails in the spacetime region through which is passes

Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

Science.gov (United States)

Mitri, F. G.

2015-12-01

The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries.

Projecting non-diffracting waves with intermediate-plane holography.

Science.gov (United States)

Mondal, Argha; Yevick, Aaron; Blackburn, Lauren C; Kanellakopoulos, Nikitas; Grier, David G

2018-02-19

We introduce intermediate-plane holography, which substantially improves the ability of holographic trapping systems to project propagation-invariant modes of light using phase-only diffractive optical elements. Translating the mode-forming hologram to an intermediate plane in the optical train can reduce the need to encode amplitude variations in the field, and therefore complements well-established techniques for encoding complex-valued transfer functions into phase-only holograms. Compared to standard holographic trapping implementations, intermediate-plane holograms greatly improve diffraction efficiency and mode purity of propagation-invariant modes, and so increase their useful non-diffracting range. We demonstrate this technique through experimental realizations of accelerating modes and long-range tractor beams.

Modeling stress wave propagation in rocks by distinct lattice spring model

Directory of Open Access Journals (Sweden)

Gaofeng Zhao

2014-08-01

Full Text Available In this paper, the ability of the distinct lattice spring model (DLSM for modeling stress wave propagation in rocks was fully investigated. The influence of particle size on simulation of different types of stress waves (e.g. one-dimensional (1D P-wave, 1D S-wave and two-dimensional (2D cylindrical wave was studied through comparing results predicted by the DLSM with different mesh ratios (lr and those obtained from the corresponding analytical solutions. Suggested values of lr were obtained for modeling these stress waves accurately. Moreover, the weak material layer method and virtual joint plane method were used to model P-wave and S-wave propagating through a single discontinuity. The results were compared with the classical analytical solutions, indicating that the virtual joint plane method can give better results and is recommended. Finally, some remarks of the DLSM on modeling of stress wave propagation in rocks were provided.

Heteroepitaxial growth of basal plane stacking fault free a-plane GaN

Energy Technology Data Exchange (ETDEWEB)

Wieneke, Matthias; Hempel, Thomas; Noltemeyer, Martin; Witte, Hartmut; Dadgar, Armin; Blaesing, Juergen; Christen, Juergen; Krost, Alois [Otto-von-Guericke Universitaet Magdeburg, FNW/IEP, Magdeburg (Germany)

2010-07-01

Growth of light emitting quantum-wells based on a-plane GaN is a possibility to reduce or even to avoid polarization correlated luminescence red shift and reduction of radiative recombination efficiency. But until now heteroepitaxially grown a-plane GaN films are characterized by a poor crystalline quality expressed by a high density of basal plane stacking faults (BSF) and partial dislocations. We present Si doped a-plane GaN films grown on r-plane sapphire substrates by metal organic vapor phase epitaxy using high temperature AlGaN nucleation layers. FE-SEM images revealed three dimensionally grown GaN crystallites sized up to tenth micrometer in the basal plane and a few tenth micrometers along the c-axes. Though, the full width at half maxima of the X-ray diffraction {omega}-scans of the in-plane GaN(1 anti 100) and GaN(0002) Bragg reflections exhibited a very high crystal quality. Furthermore, luminescence spectra were dominated by near band gap emission, while there was no separated peak of the basal plane stacking fault. In summary we present heteroepitaxially grown a-plane GaN without an evidence of basal plane stacking faults in X-ray diffraction measurements and luminescence spectra.

A singularity extraction technique for computation of antenna aperture fields from singular plane wave spectra

DEFF Research Database (Denmark)

Cappellin, Cecilia; Breinbjerg, Olav; Frandsen, Aksel

2008-01-01

An effective technique for extracting the singularity of plane wave spectra in the computation of antenna aperture fields is proposed. The singular spectrum is first factorized into a product of a finite function and a singular function. The finite function is inverse Fourier transformed...... numerically using the Inverse Fast Fourier Transform, while the singular function is inverse Fourier transformed analytically, using the Weyl-identity, and the two resulting spatial functions are then convolved to produce the antenna aperture field. This article formulates the theory of the singularity...

Study of spin and decay-plane correlations of W bosons in the e+e-→W+ W- process at LEP

International Nuclear Information System (INIS)

Achard, P.; Adriani, O.; Aguillar-Benitez, M.

2005-01-01

Data collected at LEP at centre-of-mass energies √(s)=189-209 GeV are used to study correlations of the spin of W bosons using e + e - →W + W - →lνq anti q events. Spin correlations are favoured by data, and found to agree with the Standard Model predictions. In addition, correlations between the W-boson decay planes are studied in e + e - →W + W - →lνq anti q and e + e - →W + W - →q anti qq anti q events. Decay-plane correlations are measured to be consistent with the Standard Model predictions. (orig.)

Three-dimensional stability of solitary kinetic Alfven waves and ion-acoustic waves

International Nuclear Information System (INIS)

Ghosh, G.; Das, K.P.

1994-01-01

Starting from a set of equations that lead to a linear dispersion relation coupling kinetic Alfven waves and ion-acoustic waves, three-dimensional KdV equations are derived for these waves. These equations are then used to investigate the three-dimensional stability of solitary kinetic Alfven waves and ion-acoustic waves by the small-k perturbation expansion method of Rowlands and Infeld. For kinetic Alfven waves it is found that there is instability if the direction of the plane-wave perturbation lies inside a cone, and the growth rate of the instability attains a maximum when the direction of the perturbation lies in the plane containing the external magnetic field and the direction of propagation of the solitary wave. For ion-acoustic waves the growth rate of instability attains a maximum when the direction of the perturbation lies in a plane perpendicular to the direction of propagation of the solitary wave. (Author)

Next generation sub-millimeter wave focal plane array coupling concepts: an ESA TRP project to develop multichroic focal plane pixels for future CMB polarization experiments

Science.gov (United States)

Trappe, N.; Bucher, M.; De Bernardis, P.; Delabrouille, J.; Deo, P.; DePetris, M.; Doherty, S.; Ghribi, A.; Gradziel, M.; Kuzmin, L.; Maffei, B.; Mahashabde, S.; Masi, S.; Murphy, J. A.; Noviello, F.; O'Sullivan, C.; Pagano, L.; Piacentini, F.; Piat, M.; Pisano, G.; Robinson, M.; Stompor, R.; Tartari, A.; van der Vorst, M.; Verhoeve, P.

2016-07-01

The main objective of this activity is to develop new focal plane coupling array concepts and technologies that optimise the coupling from reflector optics to the large number of detectors for next generation sub millimetre wave telescopes particularly targeting measurement of the polarization of the cosmic microwave background (CMB). In this 18 month TRP programme the consortium are tasked with developing, manufacturing and experimentally verifying a prototype multichroic pixel which would be suitable for the large focal plane arrays which will be demanded to reach the required sensitivity of future CMB polarization missions. One major development was to have multichroic operation to potentially reduce the required focal plane size of a CMB mission. After research in the optimum telescope design and definition of requirements based on a stringent science case review, a number of compact focal plane architecture concepts were investigated before a pixel demonstrator consisting of a planar mesh lens feeding a backend Resonant Cold Electron Bolometer RCEB for filtering and detection of the dual frequency signal was planned for manufacture and test. In this demonstrator the frequencies of the channels was chosen to be 75 and 105 GHz in the w band close to the peak CMB signal. In the next year the prototype breadboards will be developed to test the beams produced by the manufactured flat lenses fed by a variety of antenna configurations and the spectral response of the RCEBs will also be verified.

Lowest-lying even-parity anti B{sub s} mesons: heavy-quark spin-flavor symmetry, chiral dynamics, and constituent quark-model bare masses

Energy Technology Data Exchange (ETDEWEB)

Albaladejo, M.; Fernandez-Soler, P.; Nieves, J.; Ortega, P.G. [Centro Mixto CSIC-Universidad de Valencia, Instituto de Fisica Corpuscular (IFIC), Institutos de Investigacion de Paterna, Aptd. 22085, Valencia (Spain)

2017-03-15

The discovery of the D{sup *}{sub s0}(2317) and D{sub s1}(2460) resonances in the charmed-strange meson spectra revealed that formerly successful constituent quark models lose predictability in the vicinity of two-meson thresholds. The emergence of non-negligible effects due to meson loops requires an explicit evaluation of the interplay between Q anti q and (Q anti q)(q anti q) Fock components. In contrast to the c anti s sector, there is no experimental evidence of J{sup P} = 0{sup +}, 1{sup +} bottom-strange states yet. Motivated by recent lattice studies, in this work the heavy-quark partners of the D{sub s0}{sup *}(2317) and D{sub s1}(2460) states are analyzed within a heavy meson chiral unitary scheme. As a novelty, the coupling between the constituent quark-model P-wave anti B{sub s} scalar and axial mesons and the anti B{sup (*)}K channels is incorporated employing an effective interaction, consistent with heavy-quark spin symmetry, constrained by the lattice energy levels. (orig.)

Instability of coupled gravity-inertial-Rossby waves on a β-plane in solar system atmospheres

Directory of Open Access Journals (Sweden)

J. F. McKenzie

2009-11-01

Full Text Available This paper provides an analysis of the combined theory of gravity-inertial-Rossby waves on a β-plane in the Boussinesq approximation. The wave equation for the system is fifth order in space and time and demonstrates how gravity-inertial waves on the one hand are coupled to Rossby waves on the other through the combined effects of β, the stratification characterized by the Väisälä-Brunt frequency N, the Coriolis frequency f at a given latitude, and vertical propagation which permits buoyancy modes to interact with westward propagating Rossby waves. The corresponding dispersion equation shows that the frequency of a westward propagating gravity-inertial wave is reduced by the coupling, whereas the frequency of a Rossby wave is increased. If the coupling is sufficiently strong these two modes coalesce giving rise to an instability. The instability condition translates into a curve of critical latitude Θc versus effective equatorial rotational Mach number M, with the region below this curve exhibiting instability. "Supersonic" fast rotators are unstable in a narrow band of latitudes around the equator. For example Θc~12° for Jupiter. On the other hand slow "subsonic" rotators (e.g. Mercury, Venus and the Sun's Corona are unstable at all latitudes except very close to the poles where the β effect vanishes. "Transonic" rotators, such as the Earth and Mars, exhibit instability within latitudes of 34° and 39°, respectively, around the Equator. Similar results pertain to Oceans. In the case of an Earth's Ocean of depth 4km say, purely westward propagating waves are unstable up to 26° about the Equator. The nonlinear evolution of this instability which feeds off rotational energy and gravitational buoyancy may play an important role in atmospheric dynamics.

CFD Calculations of the Air Flow Along a Cold Vertical Wall with an Obstacle

DEFF Research Database (Denmark)

Svidt, Kjeld; Heiselberg, Per

This paper deals with the ability of Computational Fluid Dynamics to predict downdraught at a plane wall and at a wall with large obstacles. Quite simple boundary conditions were used in this study. Predictions of the main flow characteristics and the velocity levels in the occupied zone showed...

Influence of excitability on unpinning and termination of spiral waves.

Science.gov (United States)

Luengviriya, Jiraporn; Sutthiopad, Malee; Phantu, Metinee; Porjai, Porramain; Kanchanawarin, Jarin; Müller, Stefan C; Luengviriya, Chaiya

2014-11-01

Application of electrical forcing to release pinned spiral waves from unexcitable obstacles and to terminate the rotation of free spiral waves at the boundary of excitable media has been investigated in thin layers of the Belousov-Zhabotinsky (BZ) reaction, prepared with different initial concentrations of H_{2}SO_{4}. Increasing [H_{2}SO_{4}] raises the excitability of the reaction and reduces the core diameter of free spiral waves as well as the wave period. An electric current with density stronger than a critical value Junpin causes a pinned spiral wave to drift away from the obstacle. For a given obstacle size, Junpin increases with [H_{2}SO_{4}]. Under an applied electrical current, the rotation center of a free spiral wave drifts along a straight path to the boundary. When the current density is stronger than a critical value Jterm, the spiral tip is forced to hit the boundary, where the spiral wave is terminated. Similar to Junpin for releasing a pinned spiral wave, Jterm also increases with [H_{2}SO_{4}]. These experimental findings were confirmed by numerical simulations using the Oregonator model, in which the excitability was adjusted via the ratio of the excitation rate to the recovery rate of the BZ reaction. Therefore, our investigation shows that decreasing the excitability can facilitate elimination of spiral waves by electrical forcing, either in the presence of obstacles or not.

Coherent quantum states of a relativistic particle in an electromagnetic plane wave and a parallel magnetic field

International Nuclear Information System (INIS)

Colavita, E.; Hacyan, S.

2014-01-01

We analyze the solutions of the Klein–Gordon and Dirac equations describing a charged particle in an electromagnetic plane wave combined with a magnetic field parallel to the direction of propagation of the wave. It is shown that the Klein–Gordon equation admits coherent states as solutions, while the corresponding solutions of the Dirac equation are superpositions of coherent and displaced-number states. Particular attention is paid to the resonant case in which the motion of the particle is unbounded. -- Highlights: •We study a relativistic electron in a particular electromagnetic field configuration. •New exact solutions of the Klein–Gordon and Dirac equations are obtained. •Coherent and displaced number states can describe a relativistic particle

Closed form solution for the finite anti-plane shear field for a class of hyperelastic incompressible brittle solids

Science.gov (United States)

Stolz, Claude

2010-12-01

The equilibrium solution of a damaged zone in finite elasticity is given for a class of hyperelastic materials which does not suffer tension when a critical stretching value is reached. The study is made for a crack in anti-plane shear loading condition. The prescribed loading is that of linearized elastostatics conditions at infinity. The geometry of the damaged zone is found and the stationary propagation is discussed when the inertia terms can be neglected.

The effects of a flow obstacle on liquid film flowing concurrently with air in a horizontal rectangular duct

International Nuclear Information System (INIS)

Fukano, Tohru; Tominaga, Akira; Morikawa, Kengo.

1986-01-01

The aspect of a liquid film flowing near a flat plate type obstacle was observed, and the liquid film thickness and the entrainment were measured under a wide range of gas and liquid flow rates. The results are summarized as follows: (1) The configurations of film flows near the obstacle are classified according to whether (a) the liquid film climbs over the obstacle or not, (b) the air flows under the obstacle or not, or (c) the liquid film swells or sinks just upstream or downstream of the obstacle. (2) The lower the liquid flow rate, the larger the effect of the obstacle on the film thickness. (3) The generation of entrainment is regulated by the obstacle when the air volumetric flux is high and by the disturbance wave when it is low. (author)

Fourier plane imaging microscopy

Energy Technology Data Exchange (ETDEWEB)

Dominguez, Daniel, E-mail: daniel.dominguez@ttu.edu; Peralta, Luis Grave de [Department of Physics, Texas Tech University, Lubbock, Texas 79409 (United States); Nano Tech Center, Texas Tech University, Lubbock, Texas 79409 (United States); Alharbi, Nouf; Alhusain, Mdhaoui [Department of Physics, Texas Tech University, Lubbock, Texas 79409 (United States); Bernussi, Ayrton A. [Nano Tech Center, Texas Tech University, Lubbock, Texas 79409 (United States); Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)

2014-09-14

We show how the image of an unresolved photonic crystal can be reconstructed using a single Fourier plane (FP) image obtained with a second camera that was added to a traditional compound microscope. We discuss how Fourier plane imaging microscopy is an application of a remarkable property of the obtained FP images: they contain more information about the photonic crystals than the images recorded by the camera commonly placed at the real plane of the microscope. We argue that the experimental results support the hypothesis that surface waves, contributing to enhanced resolution abilities, were optically excited in the studied photonic crystals.

Epoxy-based broadband anti-reflection coating for millimeter-wave optics

OpenAIRE

Rosen, Darin; Suzuki, Aritoki; Keating, Brian; Krantz, William; Lee, Adrian T.; Quealy, Erin; Richards, Paul L.; Siritanasak, Praween; Walker, William

2013-01-01

We have developed epoxy-based, broadband anti-reflection coatings for millimeter-wave astrophysics experiments with cryogenic optics. By using multiple-layer coatings where each layer steps in dielectric constant, we achieved low reflection over a wide bandwidth. We suppressed the reflection from an alumina disk to 10% over fractional bandwidths of 92% and 104% using two-layer and three-layer coatings, respectively. The dielectric constants of epoxies were tuned between 2.06 and 7.44 by mixin...

Dynamics of plane-symmetric thin walls in general relativity

International Nuclear Information System (INIS)

Wang, A.

1992-01-01

Plane walls (including plane domain walls) without reflection symmetry are studied in the framework of Einstein's general relativity. Using the distribution theory, all the Einstein field equations and Bianchi identities are split into two groups: one holding in the regions outside of the wall and the other holding at the wall. The Einstein field equations at the wall are found to take a very simple form, and given explicitly in terms of the discontinuities of the metric coefficients and their derivatives. The Bianchi identities at the wall are also given explicitly. Using the latter, the interaction of a plane wall with gravitational waves and some specific matter fields is studied. In particular, it is found that, when a gravitational plane wave passes through a wall, if the wall has no reflection symmetry, the phenomena, such as reflection, stimulation, or absorption, in general, occur. It is also found that, unlike for gravitational waves, a massless scalar wave or an electromagnetic wave continuously passes through a wall without any reflection. The repulsion and attraction of a plane wall are also studied. It is found that the acceleration of an observer who is at rest relative to the wall usually consists of three parts: one is due to the force produced by the wall, the second is due to the force produced by the space-time curvature, which is zero if the wall has reflection symmetry, and the last is due to the accelerated motion of the wall. As a result, a repulsive (attractive) plane wall may not be repulsive (attractive) at all. Finally, the collision and interaction among the walls are studied

Temperature elevation in the eye of anatomically based human head models for plane-wave exposures

International Nuclear Information System (INIS)

Hirata, A; Watanabe, S; Fujiwara, O; Kojima, M; Sasaki, K; Shiozawa, T

2007-01-01

This study investigated the temperature elevation in the eye of anatomically based human head models for plane-wave exposures. The finite-difference time-domain method is used for analyzing electromagnetic absorption and temperature elevation. The eyes in the anatomic models have average dimensions and weight. Computational results show that the ratio of maximum temperature in the lens to the eye-average SAR (named 'heating factor for the lens') is almost uniform (0.112-0.147 deg. C kg W -1 ) in the frequency region below 3 GHz. Above 3 GHz, this ratio increases gradually with an increase of frequency, which is attributed to the penetration depth of an electromagnetic wave. Particular attention is paid to the difference in the heating factor for the lens between this study and earlier works. Considering causes clarified in this study, compensated heating factors in all these studies are found to be in good agreement

Detailed Analysis of Amplitude and Slope Diffraction Coefficients for knife-edge structure in S-UTD-CH Model

Directory of Open Access Journals (Sweden)

Eray Arik

2017-03-01

Full Text Available In urban, rural and indoor applications, diffraction mechanism is very important to predict the field strength and calculate the coverage accurately. The diffraction mechanism takes place on NLOS (non-line-of-sight cases like rooftop, vertex, corner, edge and sharp surfaces. S-UTD-CH model computes three type of electromagnetic wave incidence such as direct, reflected and diffracted waves, respectively. As obstacles in diffraction geometry are in the same or closer height, contribution of the diffraction mechanism is dominant. To predict the diffracted fields accurately, amplitude and slope diffraction coefficients and the derivative of these coefficients have to be taken correctly. In this paper, all the derivations about diffraction coefficients are made for knife edge type structures and extensive simulations are performed in order to analyze the amplitude and diffraction coefficients. In plane angle diffraction, contributions of amplitude and slope diffraction coefficient are maxima.

Four-dimensional parameter estimation of plane waves using swarming intelligence

International Nuclear Information System (INIS)

Zaman Fawad; Munir Fahad; Khan Zafar Ullah; Qureshi Ijaz Mansoor

2014-01-01

This paper proposes an efficient approach for four-dimensional (4D) parameter estimation of plane waves impinging on a 2-L shape array. The 4D parameters include amplitude, frequency and the two-dimensional (2D) direction of arrival, namely, azimuth and elevation angles. The proposed approach is based on memetic computation, in which the global optimizer, particle swarm optimization is hybridized with a rapid local search technique, pattern search. For this purpose, a new multi-objective fitness function is used. This fitness function is the combination of mean square error and the correlation between the normalized desired and estimated vectors. The proposed hybrid scheme is not only compared with individual performances of particle swarm optimization and pattern search, but also with the performance of the hybrid genetic algorithm and that of the traditional approach. A large number of Monte—Carlo simulations are carried out to validate the performance of the proposed scheme. It gives promising results in terms of estimation accuracy, convergence rate, proximity effect and robustness against noise. (interdisciplinary physics and related areas of science and technology)

Scattering of electromagnetic plane waves by a buried vertical dike

Directory of Open Access Journals (Sweden)

Batista Lurimar S.

2003-01-01

Full Text Available The complete and exact solution of the scattering of a TE mode frequency domain electromagnetic plane wave by a vertical dike under a conductive overburden has been established. An integral representation composed of one-sided Fourier transforms describes the scattered electric field components in each one of the five media: air, overburden, dike, and the country rocks on both sides of the dike. The determination of the terms of the series that represents the spectral components of the Fourier integrals requires the numerical inversion of a sparse matrix, and the method of successive approaches. The zero-order term of the series representation for the spectral components of the overburden, for given values of the electrical and geometrical parameters of the model, has been computed. This result allowed to determine an approximate value of the variation of the electric field on the top of the overburden in the direction perpendicular to the strike of the dike. The results demonstrate the efficiency of this forward electromagnetic modeling, and are fundamental for the interpretation of VLF and Magnetotelluric data.

Hemolytic disease of the fetus and newborn caused by anti-D and anti-S alloantibodies: a case report

Directory of Open Access Journals (Sweden)

Yousuf Rabeya

2012-02-01

Full Text Available Abstract Introduction Hemolytic disease of the fetus and newborn is most commonly caused by anti-D alloantibody. It is usually seen in Rhesus D (RhD-negative mothers that have been previously sensitized. We report here a case of hemolytic disease of the fetus and newborn in a newborn baby caused by anti-D and anti-S alloantibodies, born to a mother who was RhD negative, but with no previous serological evidence of RhD alloimmunization. Case presentation A one-day-old Chinese baby boy was born to a mother who was group A RhD negative. The baby was jaundiced with hyperbilirubinemia, but with no evidence of infection. His blood group was group A RhD positive, his direct Coombs' test result was positive and red cell elution studies demonstrated the presence of anti-D and anti-S alloantibodies. Investigations performed on the maternal blood during the 22 weeks of gestation showed the presence of anti-S antibodies only. Repeat investigations performed post-natally showed the presence of similar antibodies as in the newborn and an anti-D titer of 1:32 (0.25 IU/mL, which was significant. A diagnosis of hemolytic disease of the fetus and newborn secondary to anti-D and anti-S was made. The baby was treated with phototherapy and close monitoring. He was discharged well after five days of phototherapy. Conclusions This case illustrates the possibility of an anamnestic response of allo-anti-D from previous sensitization in a RhD-negative mother, or the development of anti-D in mid-trimester. Thus, it highlights the importance of thorough antenatal ABO, RhD blood grouping and antibody screening, and if necessary, antibody identification and regular monitoring of antibody screening and antibody levels for prevention or early detection of hemolytic disease of the fetus and newborn, especially in cases of mothers with clinically significant red cell alloantibody.

Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

International Nuclear Information System (INIS)

Mitri, F. G.

2015-01-01

The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb < 1). The results are particularly relevant in acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries

Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves

Energy Technology Data Exchange (ETDEWEB)

Mitri, F. G., E-mail: F.G.Mitri@ieee.org [Chevron, Area 52 Technology–ETC, Santa Fe, New Mexico 87508 (United States)

2015-12-07

The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb < 1). The results are particularly relevant in acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries.

Mobile ultrasound plane wave beamforming on iPhone or iPad using metal-based GPU processing

OpenAIRE

Hewener, H.; Tretbar, S.

2015-01-01

Mobile and cost effective ultrasound devices are being used in point of care scenarios or the drama room. To reduce the costs of such devices we already presented the possibilities of consumer devices like Apple iPad for full signal processing of raw data for ultraound image generation. Using technologies like plane wave imaging to generate a full image with only one excitation/reception event the acquisition times and power consumption of ultrasound imaging can be reduced for low power mobil...

Review: Iwanaga, Kazuki (ed. (2008, Women’s Political Participation and Representation in Asia. Obstacles and Challenges

Directory of Open Access Journals (Sweden)

Dagmar Hellmann-Rajanayagam

2010-04-01

Full Text Available Review of the edited volume: Iwanaga, Kazuki (ed. (2008, Women’s Political Participation and Representation in Asia. Obstacles and Challenges, Copenhagen: NIAS Press, = Women and Politics in Asia No. 2, ISBN 9788776940164, XVII and 314 pages.

A case for hidden b anti b tetraquarks based on e+e- → b anti b cross sections between √(s) = 10.54 and 11.20 GeV

International Nuclear Information System (INIS)

Ali, Ahmed; Hambrock, Christian; Ahmed, Ishtiaq; Aslam, M. Jamil

2009-11-01

We study the spectroscopy and dominant decays of the bottomonium-like tetraquarks (bound diquarks-antidiquarks), focusing on the lowest lying P-wave [bq][anti b anti q] states Y [bq] (with q=u,d), having J PC =1 -- . To search for them, we analyse the BABAR data obtained during an energy scan of the e + e - →b anti b cross section in the range of √(s)=10.54 to 11.20 GeV. We find that these data are consistent with the presence of an additional b anti b state Y [bq] with a mass of 10.90 GeV and a width of about 30 MeV apart from the Υ(5S) and Υ(6S) resonances. A closeup of the energy region around the Y [bq] -mass may resolve this state in terms of the two mass eigenstates, Y [b,l] and Y [b,h] , with a mass difference, estimated as about 6 MeV. We tentatively identify the state Y [bq] (10900) from the R b -scan with the state Y b (10890) observed by BELLE in the process e + e - →Y b (10890)→Υ(1S,2S)π + π - due to their proximity in masses and decay widths. (orig.)

Comparison of the projector augmented-wave, pseudopotential, and linearized augmented-plane-wave formalisms for density-functional calculations of solids

International Nuclear Information System (INIS)

Holzwarth, N.A.; Matthews, G.E.; Dunning, R.B.; Tackett, A.R.; Zeng, Y.

1997-01-01

The projector augmented-wave (PAW) method was developed by Bloechl as a method to accurately and efficiently calculate the electronic structure of materials within the framework of density-functional theory. It contains the numerical advantages of pseudopotential calculations while retaining the physics of all-electron calculations, including the correct nodal behavior of the valence-electron wave functions and the ability to include upper core states in addition to valence states in the self-consistent iterations. It uses many of the same ideas developed by Vanderbilt in his open-quotes soft pseudopotentialclose quotes formalism and in earlier work by Bloechl in his open-quotes generalized separable potentials,close quotes and has been successfully demonstrated for several interesting materials. We have developed a version of the PAW formalism for general use in structural and dynamical studies of materials. In the present paper, we investigate the accuracy of this implementation in comparison with corresponding results obtained using pseudopotential and linearized augmented-plane-wave (LAPW) codes. We present results of calculations for the cohesive energy, equilibrium lattice constant, and bulk modulus for several representative covalent, ionic, and metallic materials including diamond, silicon, SiC, CaF 2 , fcc Ca, and bcc V. With the exception of CaF 2 , for which core-electron polarization effects are important, the structural properties of these materials are represented equally well by the PAW, LAPW, and pseudopotential formalisms. copyright 1997 The American Physical Society

Model of Dirac field interacting with material plane within Symanzik’s approach

Directory of Open Access Journals (Sweden)

Pismak Yu. M.

2016-01-01

Full Text Available The model for the interaction of a spinor field with a material plane is constructed in the framework of the Symanzik’s approach. The characteristics of scattering process of Dirac particles on the plane are calculated. The bounced states localized near the plane are investigated.The model can find application to a wide class of phenomena arising by the interaction of quantum electrodynamics fields with two-dimensional materials.

Three-dimensional shear wave elastography for differentiation of breast lesions: An initial study with quantitative analysis using three orthogonal planes.

Science.gov (United States)

Wang, Qiao

2018-05-25

To prospectively evaluate the diagnostic performance of three-dimensional (3D) shear wave elastography (SWE) for breast lesions with quantitative stiffness information from transverse, sagittal and coronal planes. Conventional ultrasound (US), two-dimensional (2D)-SWE and 3D-SWE were performed for 122 consecutive patients with 122 breast lesions before biopsy or surgical excision. Maximum elasticity values of Young's modulus (Emax) were recorded on 2D-SWE and three planes of 3D-SWE. Area under the receiver operating characteristic curve (AUC), sensitivity and specificity of US, 2D-SWE and 3D-SWE were evaluated. Two combined sets (i.e., BI-RADS and 2D-SWE; BI-RADS and 3D-SWE) were compared in AUC. Observer consistency was also evaluated. On 3D-SWE, the AUC and sensitivity of sagittal plane were significantly higher than those of transverse and coronal planes (both P 0.05). However, the combined set of BI-RADS and sagittal plane of 3D-SWE had significantly higher sensitivity than the combined set of BI-RADS and 2D-SWE. The sagittal plane shows the best diagnostic performance among 3D-SWE. The combination of BI-RADS and 3D-SWE is a useful tool for predicting breast malignant lesions in comparison with BI-RADS alone.

Oxidized LDL-induced angiogenesis involves sphingosine 1-phosphate: prevention by anti-S1P antibody.

Science.gov (United States)

Camaré, Caroline; Trayssac, Magali; Garmy-Susini, Barbara; Mucher, Elodie; Sabbadini, Roger; Salvayre, Robert; Negre-Salvayre, Anne

2015-01-01

Neovascularization occurring in atherosclerotic lesions may promote plaque expansion, intraplaque haemorrhage and rupture. Oxidized LDL (oxLDL) are atherogenic, but their angiogenic effect is controversial; both angiogenic and anti-angiogenic effects have been reported. The angiogenic mechanism of oxLDL is partly understood, but the role of the angiogenic sphingolipid, sphingosine 1-phosphate (S1P), in this process is not known. Thus, we investigated whether S1P is involved in the oxLDL-induced angiogenesis and whether an anti-S1P monoclonal antibody can prevent this effect. Angiogenesis was assessed by capillary tube formation by human microvascular endothelial cells (HMEC-1) cultured on Matrigel and in vivo by the Matrigel plug assay in C57BL/6 mice. Human oxLDL exhibited a biphasic angiogenic effect on HMEC-1; low concentrations were angiogenic, higher concentrations were cytotoxic. The angiogenic response to oxLDL was blocked by the sphingosine kinase (SPHK) inhibitor, dimethylsphingosine, by SPHK1-siRNA and by an anti-S1P monoclonal antibody. Moreover, inhibition of oxLDL uptake and subsequent redox signalling by anti-CD36 and anti-LOX-1 receptor antibodies and by N-acetylcysteine, respectively, blocked SPHK1 activation and tube formation. In vivo, in the Matrigel plug assay, low concentrations of human oxLDL or murine oxVLDL also triggered angiogenesis, which was prevented by i.p. injection of the anti-S1P antibody. These data highlight the role of S1P in angiogenesis induced by oxLDL both in HMEC-1 cultured on Matrigel and in vivo in the Matrigel plug model in mice, and demonstrate that the anti-S1P antibody effectively blocks the angiogenic effect of oxLDL. © 2014 The British Pharmacological Society.

DFT LCAO and plane wave calculations of SrZrO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Evarestov, R.A.; Bandura, A.V.; Alexandrov, V.E. [Department of Quantum Chemistry, St. Petersburg State University, 26 Universitetskiy Prospekt, Stary Peterhof 198504 (Russian Federation); Kotomin, E.A. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, 70569, Stuttgart (Germany)

2005-02-01

The results of the density functional (DFT) LCAO and plane wave (PW) calculations of the electronic and structural properties of four known SrZrO{sub 3} phases (Pm3m, I4/mcm, Cmcm and Pbnm) are presented and discussed. The calculated unit cell energies and relative stability of these phases agree well with the experimental sequence of SrZrO{sub 3} phases as the temperature increases. The lattice structure parameters optimized in the PW calculations for all four phases are in good agreement with the experimental neutron diffraction data. The LCAO and PW results for the electronic structure, density of states and chemical bonding in the cubic phase (Pm3m) are discussed in detail and compared with the results of previous PW calculations. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Statistics for long irregular wave run-up on a plane beach from direct numerical simulations

Science.gov (United States)

Didenkulova, Ira; Senichev, Dmitry; Dutykh, Denys

2017-04-01

overturning), it allows shock-wave formation and propagation with the speed given by Rankine-Hugoniot jump conditions, which to some extent approximates wave breaking. The scheme is second order accurate thanks to the UNO2 special reconstruction. It was described and validated in (Dutykh et al. 2011a) and has already been successfully used to simulate wave run-up on random beaches (Dutykh et al. 2011b). For simplicity the incident wave field offshore is taken Gaussian in the present study, however, this distribution can be easily changed in the numerical code. Similar to (Didenkulova et al. 2011), in order to study influence of wave nonlinearity during wave propagation to the coast we consider waves of different amplitudes and the corresponding modifications of statistics of the moving shoreline. We also consider wave fields with a different bandwidth, so that we can see the influence of the bandwidth of the incoming wave field on statistics of wave run-up on a beach. In order to validate the numerical results we use the available experimental data of irregular wave run-up on a beach (Denissenko et al. 2011; 2013). For this in our simulations we use the corresponding bathymetry set-up: the flat part of the flume with a water depth of 3.5 m is matched with the beach of constant slope 1:6. The significant wave heights Hs are chosen according to (Denissenko et al. 2013) and are equal to 0.1m, 0.2m, 0.3m, 0.4m and 0.5m, while the bandwidth is selected as 0.1, 0.4 and 0.8, which allows comparison of the behavior of wide-band and narrow-band wave fields on the beach. The characteristic wave period is 20s, as in (Denissenko et al. 2013) that provides long wave condition. All time records contain several weeks of simulations that provides significant amount of data for extreme value statistics. [1] P. Denissenko, I. Didenkulova, E. Pelinovsky, J. Pearson. Influence of the nonlinearity on statistical characteristics of long wave runup. Nonlinear Processes in Geophysics 18, 967

S/WAVES: The Radio and Plasma Wave Investigation on the STEREO Mission

Czech Academy of Sciences Publication Activity Database

Bougeret, J. L.; Goetz, K.; Kaiser, M. L.; Bale, S. D.; Kellogg, P. J.; Maksimovic, M.; Monge, N.; Monson, S. J.; Astier, P. L.; Davy, S.; Dekkali, M.; Hinze, J. J.; Manning, R. E.; Aguilar-Rodriguez, E.; Bonnin, X.; Briand, C.; Cairns, I. H.; Cattell, C. A.; Cecconi, B.; Eastwood, J.; Ergun, R. E.; Fainberg, J.; Hoang, S.; Huttunen, K. E. J.; Krucker, S.; Lecacheux, A.; MacDowall, R. J.; Macher, W.; Mangeney, A.; Meetre, C. A.; Moussas, X.; Nguyen, Q. N.; Oswald, T. H.; Pulupa, M.; Reiner, M. J.; Robinson, P. A.; Rucker, H.; Salem, c.; Santolík, Ondřej; Silvis, J. M.; Ullrich, R.; Zarka, P.; Zouganelis, I.

2008-01-01

Roč. 136, 1-4 (2008), s. 487-528 ISSN 0038-6308 Grant - others: NASA (US) NAS5-03076 Institutional research plan: CEZ:AV0Z30420517 Keywords : S/WAVES * STEREO * plasma waves * radio waves Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.372, year: 2008

Propagation of sound waves in ducts

DEFF Research Database (Denmark)

Jacobsen, Finn

2000-01-01

Plane wave propagation in ducts with rigid walls, radiation from ducts, classical four-pole theory for composite duct systems, and three-dimentional waves in wave guides of various cross-sectional shape are described.......Plane wave propagation in ducts with rigid walls, radiation from ducts, classical four-pole theory for composite duct systems, and three-dimentional waves in wave guides of various cross-sectional shape are described....

A Newton method for a simultaneous reconstruction of an interface and a buried obstacle from far-field data

International Nuclear Information System (INIS)

Zhang, Haiwen; Zhang, Bo

2013-01-01

This paper is concerned with the inverse problem of scattering of time-harmonic acoustic waves from a penetrable and a buried obstacle. By introducing a related transmission scattering problem, a Newton iteration method is proposed to simultaneously reconstruct both the penetrable interface and the buried obstacle inside from far-field data. The main feature of our method is that we do not need to know the type of boundary conditions on the buried obstacle. In particular, the boundary condition on the buried obstacle can also be determined simultaneously by the method. Finally, numerical examples using multi-frequency data are carried out to illustrate the effectiveness of our method. (paper)

SDO/AIA Observations of Quasi-periodic Fast (~1000 km/s) Propagating (QFP) Waves as Evidence of Fast-mode Magnetosonic Waves in the Low Corona: Statistics and Implications

Science.gov (United States)

Liu, W.; Ofman, L.; Title, A. M.; Zhao, J.; Aschwanden, M. J.

2011-12-01

Recent EUV imaging observations from SDO/AIA led to the discovery of quasi-periodic fast (~2000 km/s) propagating (QFP) waves in active regions (Liu et al. 2011). They were interpreted as fast-mode magnetosonic waves and reproduced in 3D MHD simulations (Ofman et al. 2011). Since then, we have extended our study to a sample of more than a dozen such waves observed during the SDO mission (2010/04-now). We will present the statistical properties of these waves including: (1) Their projected speeds measured in the plane of the sky are about 400-2200 km/s, which, as the lower limits of their true speeds in 3D space, fall in the expected range of coronal Alfven or fast-mode speeds. (2) They usually originate near flare kernels, often in the wake of a coronal mass ejection, and propagate in narrow funnels of coronal loops that serve as waveguides. (3) These waves are launched repeatedly with quasi-periodicities in the 30-200 seconds range, often lasting for more than one hour; some frequencies coincide with those of the quasi-periodic pulsations (QPPs) in the accompanying flare, suggestive a common excitation mechanism. We obtained the k-omega diagrams and dispersion relations of these waves using Fourier analysis. We estimate their energy fluxes and discuss their contribution to coronal heating as well as their diagnostic potential for coronal seismology.

Evaluation of the Electromagnetic Power Absorption in Humans Exposed to Plane Waves: The Effect of Breathing Activity

Directory of Open Access Journals (Sweden)

Marta Cavagnaro

2013-01-01

Full Text Available The safety aspects of the exposure of people to uniform plane waves in the frequency range from 900 MHz to 5 GHz are analyzed. Starting from a human body model available in the literature, representing a man in resting state, two new anatomical models are considered, representing different phases of the respiratory activity: tidal breath and deep breath. These models have been used to evaluate the whole body Specific Absorption Rate (SAR and the 10-g averaged and 1-g averaged SAR. The analysis is performed using a parallel implementation of the finite difference time domain method. A uniform plane wave, with vertical polarization, is used as an incident field since this is the canonical exposure situation used in safety guidelines. Results show that if the incident electromagnetic field is compliant with the reference levels promulgated by the International Commission on Non-Ionizing Radiation Protection and by IEEE, the computed SAR values are lower than the corresponding basic restrictions, as expected. On the other side, when the Federal Communications Commission reference levels are considered, 1-g SAR values exceeding the basic restrictions for exposure at 4 GHz and above are obtained. Furthermore, results show that the whole body SAR values increase passing from the resting state model to the deep breath model, for all the considered frequencies.

Role of curvatures in determining the characteristics of a string vibrating against a doubly curved obstacle

Science.gov (United States)

Singh, Harkirat; Wahi, Pankaj

2017-08-01

The motion of a string in the presence of a doubly curved obstacle is investigated. A mathematical model has been developed for a general shape of the obstacle. However, detailed analysis has been performed for a shape relevant to the Indian stringed musical instruments like Tanpura and Sitar. In particular, we explore the effect of obstacle's curvature in the plane perpendicular to the string axis on its motion. This geometrical feature of the obstacle introduces a coupling between motions in mutually perpendicular directions over and above the coupling due to the stretching nonlinearity. We find that only one planar motion is possible for our system. Small amplitude planar motions are stable to perturbations in the perpendicular direction resulting in non-whirling motions while large amplitude oscillations lead to whirling motions. The critical amplitude of oscillations, across which there is a transition in the qualitative behavior of the non-planar trajectories, is determined using Floquet theory. Our analysis reveals that a small obstacle curvature in a direction perpendicular to the string axis leads to a considerable reduction in the critical amplitudes required for initiation of whirling motions. Hence, this obstacle curvature has a destabilizing effect on the planar motions in contrast to the curvature along the string axis which stabilizes planar motions.

Constructing target product profiles (TPPs) to help vaccines overcome post-approval obstacles

OpenAIRE

Lee, Bruce Y.; Burke, Donald S.

2009-01-01

As history has demonstrated, post-approval obstacles can impede a vaccine’s use and potentially lead to its withdrawal. Addressing these potential obstacles when changes in a vaccine’s technology can still be easily made may improve a vaccine’s chances of success. Augmented vaccine target product profiles (TPPs) can help vaccine scientists better understand and anticipate these obstacles and galvanize conversations among various vaccine stakeholders (e.g., scientists, marketers, business deve...

250 DPI at 1000 Hz acquisition rate S0 lamb wave digitizing pen.

Science.gov (United States)

Nikolovski, Jean-Pierre; Fournier, Danièle

2013-02-01

This paper presents an active stylus (X, Y) flat digitizing tablet (AST). The tablet features an acquisition rate of 1000 pts/s with 0.1 mm resolution. The cordless stylus incorporates a 1-mA low-power pulse generator. Precision is limited by diffraction to about ±0.3 mm on a 57 x 57 mm region of a 71 x 71 x 1 mm digitizing plate. Selective generation and detection of the S(0) Lamb mode with a precessing tip is the key feature of this tablet. We first highlight the ultrasonic propagation inside the stylus tip and stability of Lamb wave generation when the stylus is inclined, rotated, and slid. Then, modeling of the limitations imposed by diffraction of a 1-MHz burst S(0) plane Lamb wave packet is carried out. The model takes into account high-order zero crossing detection as well as reflections and shear horizontal (SH) conversions of the S(0) Lamb mode at free edges of a glass plate. Reflection and transmission through an isotropic PZT bar are also calculated. Finally, localization precision by time difference of arrival (TDOA) is calculated and experimentally verified near the borders of the plate, taking into account the angular sensitivity of the precessing tip.

Kinetic theory of electromagnetic plane wave obliquely incident on bounded plasma slab

International Nuclear Information System (INIS)

Angus, J. R.; Krasheninnikov, S. I.; Smolyakov, A. I.

2010-01-01

The effects of electromagnetic plane waves obliquely incident on a warm bounded plasma slab of finite length L are studied by solving the coupled Vlasov-Maxwell set of equations. It is shown that the solution can be greatly simplified in the limit where thermal effects are most important by expanding in small parameters and introducing self-similar variables. These solutions reveal that the coupling of thermal effects with the angle of incidence is negligible in the region of bounce resonance and anomalous skin effect. In the region of the anomalous skin effect, the heating is shown to scale linearly with the anomalous skin depth δ a when δ a a >>L, the heating is shown to decay with 1/δ a 3 . The transmission is found to be exponentially larger than that predicted from a local theory in the appropriate region of the anomalous skin effect.

Development of S-wave portable vibrator; S ha potable vibrator shingen no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Kaida, Y; Matsubara, Y [OYO Corp., Tokyo (Japan); Nijhof, V; Brouwer, J

1996-05-01

An S-wave portable vibrator to serve as a seismic source has been developed for the purpose of applying the shallow-layer reflection method to the study of the soil ground. The author, et al., who previously developed a P-wave portable vibrator has now developed an S-wave version, considering the advantage of the S-wave over the P-wave in that, for example, the S-wave velocity may be directly compared with the N-value representing ground strength and that the S-wave travels more slowly than the P-wave through sticky soil promising a higher-resolution exploration. The experimentally constructed S-wave vibrator consists of a conventional P-wave vibrator and an L-type wooden base plate combined therewith. Serving as the monitor for vibration is a conventional accelerometer without any modification. The applicability test was carried out at a location where a plank hammering test was once conducted for reflection aided exploration, and the result was compared with that of the plank hammering test. As the result, it was found that after some preliminary treatment the results of the two tests were roughly the same but that both reflected waves were a little sharper in the S-wave vibrator test than in the plank hammering test. 4 refs., 9 figs., 1 tab.

Metamaterials, from electromagnetic waves to water waves, bending waves and beyond

KAUST Repository

Dupont, G.

2015-08-04

We will review our recent work on metamaterials for different types of waves. Transposition of transform optics to water waves and bending waves on plates will be considered with potential applications of cloaking to water waves protection and anti-vibrating systems.

Nonlinear attenuation of S-waves and Love waves within ambient rock

Science.gov (United States)

Sleep, Norman H.; Erickson, Brittany A.

2014-04-01

obtain scaling relationships for nonlinear attenuation of S-waves and Love waves within sedimentary basins to assist numerical modeling. These relationships constrain the past peak ground velocity (PGV) of strong 3-4 s Love waves from San Andreas events within Greater Los Angeles, as well as the maximum PGV of future waves that can propagate without strong nonlinear attenuation. During each event, the shaking episode cracks the stiff, shallow rock. Over multiple events, this repeated damage in the upper few hundred meters leads to self-organization of the shear modulus. Dynamic strain is PGV divided by phase velocity, and dynamic stress is strain times the shear modulus. The frictional yield stress is proportional to depth times the effective coefficient of friction. At the eventual quasi-steady self-organized state, the shear modulus increases linearly with depth allowing inference of past typical PGV where rock over the damaged depth range barely reaches frictional failure. Still greater future PGV would cause frictional failure throughout the damaged zone, nonlinearly attenuating the wave. Assuming self-organization has taken place, estimated maximum past PGV within Greater Los Angeles Basins is 0.4-2.6 m s-1. The upper part of this range includes regions of accumulating sediments with low S-wave velocity that may have not yet compacted, rather than having been damaged by strong shaking. Published numerical models indicate that strong Love waves from the San Andreas Fault pass through Whittier Narrows. Within this corridor, deep drawdown of the water table from its currently shallow and preindustrial levels would nearly double PGV of Love waves reaching Downtown Los Angeles.

CMS-Wave

Science.gov (United States)

2015-10-30

Coastal Inlets Research Program CMS -Wave CMS -Wave is a two-dimensional spectral wind-wave generation and transformation model that employs a forward...marching, finite-difference method to solve the wave action conservation equation. Capabilities of CMS -Wave include wave shoaling, refraction... CMS -Wave can be used in either on a half- or full-plane mode, with primary waves propagating from the seaward boundary toward shore. It can

Applicability of geometrical optics to in-plane liquid-crystal configurations.

Science.gov (United States)

Sluijter, M; Xu, M; Urbach, H P; de Boer, D K G

2010-02-15

We study the applicability of geometrical optics to inhomogeneous dielectric nongyrotropic optically anisotropic media typically found in in-plane liquid-crystal configurations with refractive indices n(o)=1.5 and n(e)=1.7. To this end, we compare the results of advanced ray- and wave-optics simulations of the propagation of an incident plane wave to a special anisotropic configuration. Based on the results, we conclude that for a good agreement between ray and wave optics, a maximum change in optical properties should occur over a distance of at least 20 wavelengths.

Plane-wave and common-translation-factor treatments of He2++H collisions at high velocities

International Nuclear Information System (INIS)

Errea, L.F.; Harel, C.; Jouin, H.; Maidagan, J.M.; Mendez, L.; Pons, B.; Riera, A.

1992-01-01

We complement previous work that showed that the molecular approach, modified with plane-wave translation factors, is able to reproduce the fall of charge-exchange cross sections in He 2+ +H collisions, by presenting the molecular data, and studying the corresponding mechanism. We test the accuracy of simplifications of the method that have been employed in the literature, and that lead to very simple calculations. We show that the common-translation-factor method is also successful at high nuclear velocities, provided that sufficiently excited states are included in the basis; moreover, it yields a simple picture of the mechanism and a description of ionization processes at high velocities

Spin-parity structure of the (anti Kππ)0 system produced in the charge-exchange reaction K-p→(anti K0π+π-)n at 4.2 GeV/c

International Nuclear Information System (INIS)

Vergeest, J.S.M.; Cerrada, M.; Chaloupka, V.; Gavillet, Ph.; Gay, J.B.; Hemingway, R.J.; Losty, M.J.; Engelen, J.J.; Kittel, E.W.; Metzger, W.J.; Tiecke, H.G.J.M.; Jongejans, B.; Voorthuis, H.; Wolters, G.F.

1976-01-01

Partial wave analysis of the anti K 0 π + π - system produced in the charge exchange reaction K - p→(anti K 0 π + π - )n at 4.2 GeV/c has been performed both as a function of Kππ mass and of t. The 1 + S wave forms the largest contribution to the Kππ system and peaks at roughly the same mass as the Q in diffractive Kππ production. The polarization properties of the 1 + S (K*π) and 1 + S (Krho) waves differ from those of the diffractive 1 + wave. There is some evidence for a resonance contribution to 1 + S (K*π). The strong 2 + wave is identified with the K*(1420) and the Krho/K*π decay branching ratio determined to be 0.36 +- 0.10. An enhancement with spin-parity 1 - is observed under the K*(1420). (Auth.)

Earthquake early warning using P-waves that appear after initial S-waves

Science.gov (United States)

Kodera, Y.

2017-12-01

As measures for underprediction for large earthquakes with finite faults and overprediction for multiple simultaneous earthquakes, Hoshiba (2013), Hoshiba and Aoki (2015), and Kodera et al. (2016) proposed earthquake early warning (EEW) methods that directly predict ground motion by computing the wave propagation of observed ground motion. These methods are expected to predict ground motion with a high accuracy even for complicated scenarios because these methods do not need source parameter estimation. On the other hand, there is room for improvement in their rapidity because they predict strong motion prediction mainly based on the observation of S-waves and do not explicitly use P-wave information available before the S-waves. In this research, we propose a real-time P-wave detector to incorporate P-wave information into these wavefield-estimation approaches. P-waves within a few seconds from the P-onsets are commonly used in many existing EEW methods. In addition, we focus on P-waves that may appear in the later part of seismic waves. Kurahashi and Irikura (2013) mentioned that P-waves radiated from strong motion generation areas (SMGAs) were recognizable after S-waves of the initial rupture point in the 2011 off the Pacific coast of Tohoku earthquake (Mw 9.0) (the Tohoku-oki earthquake). Detecting these P-waves would enhance the rapidity of prediction for the peak ground motion generated by SMGAs. We constructed a real-time P-wave detector that uses a polarity analysis. Using acceleration records in boreholes of KiK-net (band-pass filtered around 0.5-10 Hz with site amplification correction), the P-wave detector performed the principal component analysis with a sliding window of 4 s and calculated P-filter values (e.g. Ross and Ben-Zion, 2014). The application to the Tohoku-oki earthquake (Mw 9.0) showed that (1) peaks of P-filter that corresponded to SMGAs appeared in several stations located near SMGAs and (2) real-time seismic intensities (Kunugi et al

Assessing the ground vibrations produced by a heavy vehicle traversing a traffic obstacle.

Science.gov (United States)

Ducarne, Loïc; Ainalis, Daniel; Kouroussis, Georges

2018-01-15

Despite advancements in alternative transport networks, road transport remains the dominant mode in many modern and developing countries. The ground-borne motions produced by the passage of a heavy vehicle over a geometric obstacle (e.g. speed hump, train tracks) pose a fundamental problem in transport annoyance in urban areas. In order to predict the ground vibrations generated by the passage of a heavy vehicle over a geometric obstacle, a two-step numerical model is developed. The first step involves simulating the dynamic loads generated by the heavy vehicle using a multibody approach, which includes the tyre-obstacle-ground interaction. The second step involves the simulation of the ground wave propagation using a three dimensional finite element model. The simulation is able to be decoupled due to the large difference in stiffness between the vehicle's tyres and the road. First, the two-step model is validated using an experimental case study available in the literature. A sensitivity analysis is then presented, examining the influence of various factors on the generated ground vibrations. Factors investigated include obstacle shape, obstacle dimensions, vehicle speed, and tyre stiffness. The developed model can be used as a tool in the early planning stages to predict the ground vibrations generated by the passage of a heavy vehicle over an obstacle in urban areas. Copyright © 2017 Elsevier B.V. All rights reserved.

Anti-U-like as an alloantibody in S-s-U- and S-s-U+(var) black people.

Science.gov (United States)

Peyrard, Thierry; Lam, Yin; Saison, Carole; Arnaud, Lionel; Babinet, Jérôme; Rouger, Philippe; Bierling, Philippe; Janvier, Daniel

2012-03-01

S, s, and U antigens belong to the MNS system. They are carried by glycophorin B (GPB), encoded by GYPB. Black people with the low-prevalence S-s- phenotype, either U- or U+(var), can make a clinically significant anti-U. Anti-U-like, a cold immunoglobulin G autoantibody quite commonly observed in S-s+U+ black persons, was previously described to be nonreactive with ficin-, α-chymotrypsin-, and pronase-treated red blood cells (RBCs); nonreactive or weakly reactive with papain-treated RBCs; and reactive with trypsin-treated RBCs. Here we describe, in S-s- people from different molecular backgrounds, an alloantibody to a high-prevalence GPB antigen, which presents the same pattern of reactivity with proteases as autoanti-U-like. Four S-s- patients with an alloantibody to a high-prevalence GPB antigen were investigated by serologic and molecular methods. An alloantibody was observed in two S-s-U-/Del GYPB, one S-s-U+(var)/GYPB(P2), and one S-s-U+(var)/GYPB(NY) patients. As this alloantibody showed the same pattern of reactivity with proteases as autoanti-U-like, we decided to name it "anti-U-like." Anti-U-like made by the two S-s-U- patients was reactive with the S-s-U+(var) RBCs of the two other patients. S-s-U-/Del GYPB, S-s-U+(var)/GYPB(P2), and S-s-U+(var)/GYPB(NY) patients can make an alloanti-U-like. Anti-U-like made by S-s-U- people appears reactive with GYPB(P2) and GYPB(NY) RBCs, which both express a weak and partial U-like reactivity. We recommend transfusing S-s-U- RBCs in S-s-U- patients showing alloanti-U-like. Our study contributes to a better understanding of alloimmunization to GPB in black people and confirms importance of genotyping in S-s- patients, especially those with sickle cell disease to be frequently transfused. © 2011 American Association of Blood Banks.

Simulations of Wind Field Effect on Two-Stream Waves in the Equatorial Electrojet

Directory of Open Access Journals (Sweden)

Chi-Lon Fern

2009-01-01

Full Text Available The wind field effect on the phase veloc i ties of 3- to 10-me ter Farley-Buneman two-stream waves in the equato rial E region ion o sphere at al titudes in the range of 95 - 110 km is stud ied by nu mer i cal simu la tion. The behav ior of this two-stream wave in the uni form wind field Un in a plane per pen dic u lar to the Earth’s mag netic field is simu lated with a two-di men sional two-fluid code in which elec tron in er tia is ne glected while ion in er tia is re tained. It is con firmed that, the thresh old con di tion for the ap pear ance of two-stream waves is VD C U th » + s + n (1 / cos Y0 q ; and the phase ve loc ity of the two-stream wave at the thresh old con di tion is Vp » Cs + Un cos q, where q is the ele va tion an gle of the wave prop a ga tion in a limited range and Y0 = ninnen / WiWe. The first formula in di cates that the wind field paral lel (anti-par al lel to the elec tron drift ve loc ity will raise (lower the thresh old drift ve loc ity by the amount of the wind speed. This means that par al lel wind is a sta ble fac tor, while anti-paral lel wind is an un sta ble fac tor of two-stream waves. This may ex plain why high speed (larger than acous tic speed two-stream waves were rarely ob served, since larger thresh old drift veloc ity de mands larger po larization elec tric field. The result of the simu la tions at the sat u ra tion stage show that when VD was only slightly larger than VD th , the hor i zon tal phase ve loc ity of the two-stream wave would grad u ally down-shift to the thresh old phase ve loc ity Cs + Un. The physical implications of which are discussed

Measurement of D+s meson production in Z decays and of the anti B0s lifetime

International Nuclear Information System (INIS)

Buskulic, D.; Casper, D.; Bonis, I. de

1996-01-01

D + s mesons produced in Z 0 →b anti b events were separated from the Z 0 →c anti c component using a lifetime tag. Using a sample of 1.5 million hadronic Z decays collected with the ALEPH detector the anti B 0 s and D + s yields have been measured: B(b→ anti B 0 s )B(anti B 0 s →D + s )=0.088±0.020(stat.)±0.020(syst.), B(c→D + s )=0.128±0.019(stat.) +0.019 -0.016 (syst.). The anti B 0 s lifetime was measured in a anti B 0 s enriched sample reconstructing the decay length from the vertex of the D + s with a hadron from the anti B 0 s decay. The result obtained is: τ B s =1.61 +0.30 -0.29 (stat.) +0.18 -0.16 (syst.) ps. (orig.)

Magnetoelastic plane waves in rotating media in thermoelasticity of type II (G-N model

Directory of Open Access Journals (Sweden)

S. K. Roychoudhuri

2004-01-01

Full Text Available A study is made of the propagation of time-harmonic plane waves in an infinite, conducting, thermoelastic solid permeated by a uniform primary external magnetic field when the entire medium is rotating with a uniform angular velocity. The thermoelasticity theory of type II (G-N model (1993 is used to study the propagation of waves. A more general dispersion equation is derived to determine the effects of rotation, thermal parameters, characteristic of the medium, and the external magnetic field. If the primary magnetic field has a transverse component, it is observed that the longitudinal and transverse motions are linked together. For low frequency (χ≪1, χ being the ratio of the wave frequency to some standard frequency ω∗, the rotation and the thermal field have no effect on the phase velocity to the first order of χ and then this corresponds to only one slow wave influenced by the electromagnetic field only. But to the second order of χ, the phase velocity, attenuation coefficient, and the specific energy loss are affected by rotation and depend on the thermal parameters cT, cT being the nondimensional thermal wave speed of G-N theory, and the thermoelastic coupling εT, the electromagnetic parameters εH, and the transverse magnetic field RH. Also for large frequency, rotation and thermal field have no effect on the phase velocity, which is independent of primary magnetic field to the first order of (1/χ (χ≫1, and the specific energy loss is a constant, independent of any field parameter. However, to the second order of (1/χ, rotation does exert influence on both the phase velocity and the attenuation factor, and the specific energy loss is affected by rotation and depends on the thermal parameters cT and εT, electromagnetic parameter εH, and the transverse magnetic field RH, whereas the specific energy loss is independent of any field parameters to the first order of (1/χ.

Obstacles of Achieving Total Quality in the Faculty of Education in Alexandria University from Staff’s Perspective

Directory of Open Access Journals (Sweden)

Khaled Salah Hanafy Mahmoud

2018-03-01

Full Text Available This study investigated obstacles that prevent achieving total quality in the faculty of Education in Alexandria University from the point of view of the faculty members in order to provide methods for overcoming such obstacles. The study also aimed to measure the impact of the variables (gender – academic rank – the major on the staff's views in the fields of (teaching, learning – scientific research – community service – university administration – staff's personal aspects. The study was based on the descriptive method and used a questionnaire to a sample of (100 teaching staff members who were randomly selected. The results revealed that the obstacles were as follows: i obstacles of university administration with a mean of (4.5 indicating a very high agreement score, ii obstacles of teaching and learning process with a mean of (4.2 indicating a high agreement score, iii obstacles of the scientific research with a mean of (3.9 indicating a high agreement score, iv obstacles of the community service with a mean of (3.5 indicating a high agreement score and v obstacles related to the staff members’ personal aspects with a mean of (3.4 indicating an average agreement score. The results showed no statistically significant differences between the staff's views regarding about obstacles of applying total quality in the Faculty of Education, Alexandria University attributed to gender, academic rank or major. Keywords: Quality, Faculty of education, Staff members, TQM obstacles.

The effect of lower-hybrid waves on the propagation of hydromagnetic waves

International Nuclear Information System (INIS)

Hamabata, Hiromitsu; Namikawa, Tomikazu; Mori, Kazuhiro

1988-01-01

Propagation characteristics of hydromagnetic waves in a magnetic plasma are investigated using the two-plasma fluid equations including the effect of lower-hybrid waves propagating perpendicularly to the magnetic field. The effect of lower-hybrid waves on the propagation of hydromagnetic waves is analysed in terms of phase speed, growth rate, refractive index, polarization and the amplitude relation between the density perturbation and the magnetic-field perturbation for the cases when hydromagnetic waves propagate in the plane whose normal is perpendicular to both the magnetic field and the propagation direction of lower-hybrid waves and in the plane perpendicular to the propagation direction of lower-hybrid waves. It is shown that hydromagnetic waves propagating at small angles to the propagation direction of lower-hybrid waves can be excited by the effect of lower-hybrid waves and the energy of excited waves propagates nearly parallel to the propagation direction of lower-hybrid waves. (author)

Evaluation of irradiation measurements on tilted planes at PV systems in the Netherlands

NARCIS (Netherlands)

Betcke, J.W.H.; Dijk, V.A.P. van; Ramaekers, L.A.M.; Zolingen, R.J.C. van

1998-01-01

Monitoring data of Dutch PV systems in the field show lower values for the measured global irradiation in the array plane than expected from model calculatations. Since the locations of the PV systems contain obstacles, we expect that shielding of diffuse irradiation may cause the difference. For

A case for hidden b anti b tetraquarks based on e{sup +}e{sup -} {yields} b anti b cross sections between {radical}(s) = 10.54 and 11.20 GeV

Energy Technology Data Exchange (ETDEWEB)

Ali, Ahmed; Hambrock, Christian [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ahmed, Ishtiaq [Quaid-i-Azam Univ., Islamabad (Pakistan). National Centre for Physics; Aslam, M. Jamil [Quaid-i-Azam Univ., Islamabad (Pakistan). Physics Dept.

2009-11-15

We study the spectroscopy and dominant decays of the bottomonium-like tetraquarks (bound diquarks-antidiquarks), focusing on the lowest lying P-wave [bq][anti b anti q] states Y{sub [bq]} (with q=u,d), having J{sup PC}=1{sup --}. To search for them, we analyse the BABAR data obtained during an energy scan of the e{sup +}e{sup -}{yields}b anti b cross section in the range of {radical}(s)=10.54 to 11.20 GeV. We find that these data are consistent with the presence of an additional b anti b state Y{sub [bq]} with a mass of 10.90 GeV and a width of about 30 MeV apart from the {upsilon}(5S) and {upsilon}(6S) resonances. A closeup of the energy region around the Y{sub [bq]}-mass may resolve this state in terms of the two mass eigenstates, Y{sub [b,l]} and Y{sub [b,h]}, with a mass difference, estimated as about 6 MeV. We tentatively identify the state Y{sub [bq]}(10900) from the R{sub b}-scan with the state Y{sub b}(10890) observed by BELLE in the process e{sup +}e{sup -}{yields}Y{sub b}(10890){yields}{upsilon}(1S,2S){pi}{sup +}{pi}{sup -} due to their proximity in masses and decay widths. (orig.)

OverWatch: A Cross-Plane DDoS Attack Defense Framework with Collaborative Intelligence in SDN

Directory of Open Access Journals (Sweden)

Biao Han

2018-01-01

Full Text Available Distributed Denial of Service (DDoS attacks are one of the biggest concerns for security professionals. Traditional middle-box based DDoS attack defense is lack of network-wide monitoring flexibility. With the development of software-defined networking (SDN, it becomes prevalent to exploit centralized controllers to defend against DDoS attacks. However, current solutions suffer with serious southbound communication overhead and detection delay. In this paper, we propose a cross-plane DDoS attack defense framework in SDN, called OverWatch, which exploits collaborative intelligence between data plane and control plane with high defense efficiency. Attack detection and reaction are two key procedures of the proposed framework. We develop a collaborative DDoS attack detection mechanism, which consists of a coarse-grained flow monitoring algorithm on the data plane and a fine-grained machine learning based attack classification algorithm on the control plane. We propose a novel defense strategy offloading mechanism to dynamically deploy defense applications across the controller and switches, by which rapid attack reaction and accurate botnet location can be achieved. We conduct extensive experiments on a real-world SDN network. Experimental results validate the efficiency of our proposed OverWatch framework with high detection accuracy and real-time DDoS attack reaction, as well as reduced communication overhead on SDN southbound interface.

Wave Separation. Part One: Principle and Methods La séparation d'ondes. Première partie : Principes et méthodes

Directory of Open Access Journals (Sweden)

Mari J. L.

2006-11-01

Full Text Available This article is a practical review of the different wave separation methods used in seismic. A wave is described by its propagation vector and its wavelet. The first part of the article shows how the propagation vector can be used to define both the type of propagation (plane or nonplane wave and the characteristics of the medium (dispersive or faulted medium. Wave separation and wave-type identification can then be dealt with by studying the scalar product between two waves or between a wave and a reference model. The main filtering methods are described, in particular : f-k filtering, tau-p filtering, Karhunen-Loeve filtering and spectral matrix filtering. The efficiency of the different methods is assessed with synthetic data. The problem of extracting a wave from noise is also discussed and illustrated with a field example. The second part will be devoted to wave separation per se. The different methods described in the first part are applied to real data, in particular borehole survey seismic data. Special attention is given to the use of specific, less well-known methods such as spectral matrix filtering with adapted or constrained models. Cet article est une revue pratique des différentes méthodes de séparation d'ondes utilisées en sismique. Une onde est décrite par son vecteur de propagation et par son ondelette. La première partie montre comment le vecteur de propagation peut être utilisé à la fois pour définir le type de propagation (onde plane ou non plane et les caractéristiques du milieu (milieu dispersif ou faillé. La séparation d'ondes et l'identification d'un type d'onde peuvent alors être abordées par l'étude du produit scalaire entre deux ondes ou entre une onde et un modèle de référence. Les principales méthodes de filtrage sont décrites : notamment le filtrage (f, k, le filtrage (tau, p, le filtrage de Karhunen-Loève et le filtrage par la matrice interspectrale. L'efficacité des différentes m

Anti-miss-shot control device for selective stone disintegration in extracorporeal shock wave lithotripsy

Science.gov (United States)

Kuwahara, M.; Ioritani, N.; Kambe, K.; Orikasa, S.; Takayama, K.

1991-06-01

A new device to prevent erroneously focused shock waves to the renal parenchyma during extracorporeal shock wave lithotripsy (ESWL) has been developed; an anti-miss-shot control device (AMCD) and experiments have been conducted to evaluate its effectiveness. For shock wave generation and stone localization, piezoceramic elements (PSE) and ultrasound localization, respectively were used. After stone localization, probing ultrasounds (PU) were emmitted from the PSE towards the focal region and the reflected sound levels (RSL) were monitored by the PSE which also functioned as a microphone. A direct hit by the PU to the stone or a miss was judged from the RSL, i.e. a high RSL indicates a direct hit and a low RSL indicates a miss. Shock waves were generated only when the RSL exceeded the level which indicated a direct hit. The experimental results showed that the injury to the renal parenchyma was decreased by using the AMCD. Clinical application of the AMCD is expected to increase the safety of ESWL.

Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection

Science.gov (United States)

Thagard, Paul; Findlay, Scott

2010-06-01

Darwin’s theory of evolution by natural selection is central to modern biology, but is resisted by many people. This paper discusses the major psychological obstacles to accepting Darwin’s theory. Cognitive obstacles to adopting evolution by natural selection include conceptual difficulties, methodological issues, and coherence problems that derive from the intuitiveness of alternative theories. The main emotional obstacles to accepting evolution are its apparent conflict with valued beliefs about God, souls, and morality. We draw on the philosophy of science and on a psychological theory of cognitive and emotional belief revision to make suggestions about what can be done to improve acceptance of Darwinian ideas.

Real-space grid implementation of the projector augmented wave method

DEFF Research Database (Denmark)

Mortensen, Jens Jørgen; Hansen, Lars Bruno; Jacobsen, Karsten Wedel

2005-01-01

A grid-based real-space implementation of the projector augmented wave sPAWd method of Blöchl fPhys. Rev. B 50, 17953 s1994dg for density functional theory sDFTd calculations is presented. The use of uniform three-dimensional s3Dd real-space grids for representing wave functions, densities...... valence wave functions that can be represented on relatively coarse grids. We demonstrate the accuracy of the method by calculating the atomization energies of 20 small molecules, and the bulk modulus and lattice constants of bulk aluminum. We show that the approach in terms of computational efficiency...... is comparable to standard plane-wave methods, but the memory requirements are higher....

Smart Sensor Based Obstacle Detection for High-Speed Unmanned Surface Vehicle

DEFF Research Database (Denmark)

Hermann, Dan; Galeazzi, Roberto; Andersen, Jens Christian

2015-01-01

This paper describes an obstacle detection system for a high-speed and agile unmanned surface vehicle (USV), running at speeds up to 30 m/s. The aim is a real-time and high performance obstacle detection system using both radar and vision technologies to detect obstacles within a range of 175 m. ...... performance using sensor fusion of radar and computer vision....

Coherent field propagation between tilted planes.

Science.gov (United States)

Stock, Johannes; Worku, Norman Girma; Gross, Herbert

2017-10-01

Propagating electromagnetic light fields between nonparallel planes is of special importance, e.g., within the design of novel computer-generated holograms or the simulation of optical systems. In contrast to the extensively discussed evaluation between parallel planes, the diffraction-based propagation of light onto a tilted plane is more burdensome, since discrete fast Fourier transforms cannot be applied directly. In this work, we propose a quasi-fast algorithm (O(N 3  log N)) that deals with this problem. Based on a proper decomposition into three rotations, the vectorial field distribution is calculated on a tilted plane using the spectrum of plane waves. The algorithm works on equidistant grids, so neither nonuniform Fourier transforms nor an explicit complex interpolation is necessary. The proposed algorithm is discussed in detail and applied to several examples of practical interest.

Spontaneous Wave Generation from Submesoscale Fronts and Filaments

Science.gov (United States)

Shakespeare, C. J.; Hogg, A.

2016-02-01

Submesoscale features such as eddies, fronts, jets and filaments can be significant sources of spontaneous wave generation at the ocean surface. Unlike near-inertial waves forced by winds, these spontaneous waves are typically of higher frequency and can propagate through the thermocline, whereupon they break and drive mixing in the ocean interior. Here we investigate the spontaneous generation, propagation and subsequent breaking of these waves using a combination of theory and submesoscale resolving numerical models. The mechanism of generation is nearly identical to that of lee waves where flow is deflected over a rigid obstacle on the sea floor. Here, very sharp fronts and filaments of order 100m width moving in the submesoscale surface flow generate "surface lee waves" by presenting an obstacle to the surrounding stratified fluid. Using our numerical model we quantify the net downward wave energy flux from the surface, and where it is dissipated in the water column. Our results suggest an alternative to the classical paradigm where the energy associated with mixing in the ocean interior is sourced from bottom-generated lee waves.

Gas explosion characterization, wave propagation (small scale experiments)

International Nuclear Information System (INIS)

Larsen, G.C.

1985-08-01

A number of experiments have been performed with blast waves arising from the ignition of homogeneous and well defined mixtures of methane, oxygen and nitrogen, contained within spherical balloons with controlled initial dimensions. The pressure characteristics has been studied for blast waves with and without influence from reflected waves. The influence of obstacles in the flow field has also been treated. Both configuration with one box and two closely spaced boxes have been considered, and a wave-wave interaction phenomenon was observed in the case of closely spaced obstacles. Moreover reflection coefficients have been established and some pressure variations over the surfaces have been observed. An acoustic appriximation has been used to model the blast wave originating from an expanding sphere. It has been demonstrated, that the generated pressure pulse is very sensitive to the expansion rate. Calculated and measured data have been compared, and a reasonable agreement has been found. (author)

Decays of B, Bs and Bc to D-wave heavy-light mesons

International Nuclear Information System (INIS)

Li, Qiang; Wang, Tianhong; Jiang, Yue; Yuan, Han; Zhou, Tian; Wang, Guo-Li

2017-01-01

We study the weak decays of anti B (s) and B c into D-wave heavy-light mesons, including J P = 2 - (D (s)2 , D (s)2 ' , B (s)2 , B (s)2 ' ) and 3 - (D * (s)3 , B * (s)3 ) states. The weak decay hadronic matrix elements are obtained based on the instantaneous Bethe-Salpeter method. The branching ratios for the anti B decays are B[ anti B → D 2 e anti ν e ] = 1.1 -0.3 +0.3 x 10 -3 , B[ anti B → D 2 ' e anti ν e ] = 4.1 -0.8 +0.9 x 10 -4 , and B[ anti B → D 3 * e anti ν e ] = 1.0 -0.2 +0.2 x 10 -3 , respectively. For the semi-electronic decays of anti B s to D s2 , D s2 ' , and D * s3 , the corresponding branching ratios are 1.7 -0.5 +0.5 x 10 -3 , 5.2 -1.5 +1.6 x 10 -4 , and 1.5 -0.4 +0.4 x 10 -3 , respectively. The branching ratios of the semi-electronic decays of B c to D-wave D mesons are in the order of 10 -5 . We also obtained the forward-backward asymmetry, angular spectra, and lepton momentum spectra. In particular the distribution of decay widths for the 2 - states D 2 and D 2 ' varying along with mixing angle are presented. (orig.)

Neoclassical Solution of Transient Interaction of Plane Acoustic Waves with a Spherical Elastic Shell

Directory of Open Access Journals (Sweden)

Hanson Huang

1996-01-01

Full Text Available A detailed solution to the transient interaction of plane acoustic waves with a spherical elastic shell was obtained more than a quarter of a century ago based on the classical separation of variables, series expansion, and Laplace transform techniques. An eight-term summation of the time history series was sufficient for the convergence of the shell deflection and strain, and to a lesser degree, the shell velocity. Since then, the results have been used routinely for validation of solution techniques and computer methods for the evaluation of underwater explosion response of submerged structures. By utilizing modern algorithms and exploiting recent advances of computer capacities and floating point mathematics, sufficient terms of the inverse Laplace transform series solution can now be accurately computed. Together with the application of the Cesaro summation using up to 70 terms of the series, two primary deficiencies of the previous solution are now remedied: meaningful time histories of higher time derivative data such as acceleration and pressure are now generated using a sufficient number of terms in the series; and uniform convergence around the discontinuous step wave front is now obtained, completely eradicating spurious oscillations due to the Gibbs' phenomenon. New results of time histories of response items of interest are presented.

anti B{sub d,s} → D{sup *}{sub d,s}V and anti B{sup *}{sub d,s} → D{sub d,s}V decays in QCD factorization and possible puzzles

Energy Technology Data Exchange (ETDEWEB)

Chang, Qin [Henan Normal University, Institute of Particle and Nuclear Physics, Henan (China); Central China Normal University, Institute of Particle Physics, Wuhan (China); Chen, Ling-Xin; Zhang, Yun-Yun; Sun, Jun-Feng; Yang, Yue-Ling [Henan Normal University, Institute of Particle and Nuclear Physics, Henan (China)

2016-10-15

Motivated by the rapid development of heavy-flavor experiments, phenomenological studies of nonleptonic anti B{sub d,s} → D{sup *}{sub d,s}V and anti B{sup *}{sub d,s} → D{sub d,s}V (V = ρ, K*) decays are performed within the framework of QCD factorization. Relative to the previous work, the QCD corrections to the transverse amplitudes are evaluated at next-to-leading order. The theoretical predictions of the observables are updated. For the measured anti B{sub d,s} → D{sup *}{sub d,s}V decays, the tensions between theoretical results and experimental measurements, i.e. the ''R{sub ds}{sup V} puzzle'' and ''D*V (or R{sub V/l} {sub anti} {sub ν{sub l)}} puzzle'', are presented after detailed analyses. For the anti B{sup *}{sub d,s} → D{sub d,s}V decays, they have relatively large branching fractions of the order >or similar O(10{sup -9}) and are in the scope of Belle-II and LHCb experiments. Moreover, they also provide a way to crosscheck the possible puzzles mentioned above through the similar ratios R{sub ds}{sup 'V} and R{sup '}{sub V/l} {sub anti} {sub ν{sub l.}} More refined experimental measurements and theoretical efforts are required to confirm or refute such two anomalies. (orig.)

Covariant quantum mechanics on a null plane

International Nuclear Information System (INIS)

Leutwyler, H.; Stern, J.

1977-03-01

Lorentz invariance implies that the null plane wave functions factorize into a kinematical part describing the motion of the system as a whole and an inner wave function that involves the specific dynamical properties of the system - in complete correspondence with the non-relativistic situation. Covariance is equivalent to an angular condition which admits non-trivial solutions

Experimental validation of an ultra-thin metasurface cloak for hiding a metallic obstacle from an antenna radiation at low frequencies

Science.gov (United States)

Teperik, Tatiana V.; Burokur, Shah Nawaz; de Lustrac, André; Sabanowski, Guy; Piau, Gérard-Pascal

2017-07-01

We demonstrate numerically and experimentally an ultra-thin (≈ λ/240) metasurface-based invisibility cloak for low frequency antenna applications. We consider a monopole antenna mounted on a ground plane and a cylindrical metallic obstacle of diameter smaller than the wavelength located in its near-field. To restore the intrinsic radiation patterns of the antenna perturbed by this obstacle, a metasurface cloak consisting simply of a metallic patch printed on a dielectric substrate is wrapped around the obstacle. Using a finite element method based commercial electromagnetic solver, we show that the radiation patterns of the monopole antenna can be restored completely owing to electromagnetic modes of the resonant cavity formed between the patch and obstacle. The metasurface cloak is fabricated, and the concept is experimentally demonstrated at 125 MHz. Performed measurements are in good agreement with numerical simulations, verifying the efficiency of the proposed cloak.

Water wave scattering

CERN Document Server

Mandal, Birendra Nath

2015-01-01

The theory of water waves is most varied and is a fascinating topic. It includes a wide range of natural phenomena in oceans, rivers, and lakes. It is mostly concerned with elucidation of some general aspects of wave motion including the prediction of behaviour of waves in the presence of obstacles of some special configurations that are of interest to ocean engineers. Unfortunately, even the apparently simple problems appear to be difficult to tackle mathematically unless some simplified assumptions are made. Fortunately, one can assume water to be an incompressible, in viscid and homogeneous

Interaction of Interstellar Shocks with Dense Obstacles: Formation of ``Bullets''

Science.gov (United States)

Gvaramadze, V. V.

The so-called cumulative effect take place in converging conical shock waves arising behind dense obstacles overtaken by incident interstellar shock. A significant part of energy of converging flow of matter swept-up by a radiative conical shock can be transferred to a dense jet-like ejection (``bullet'') directed along the cone axis. Possible applications of this effect for star-forming regions (e.g., OMC-1) and supernova remnants (e.g., Vela SNR) are discussed.

Atomic Scale Simulation on the Anti-Pressure and Friction Reduction Mechanisms of MoS2 Monolayer

Directory of Open Access Journals (Sweden)

Yang Liu

2018-04-01

Full Text Available MoS2 nanosheets can be used as solid lubricants or additives of lubricating oils to reduce friction and resist wear. However, the atomic scale mechanism still needs to be illustrated. Herein, molecular simulations on the indentation and scratching process of MoS2 monolayer supported by Pt(111 surface were conducted to study the anti-pressure and friction reduction mechanisms of the MoS2 monolayer. Three deformation stages of Pt-supported MoS2 monolayer were found during the indentation process: elastic deformation, plastic deformation and finally, complete rupture. The MoS2 monolayer showed an excellent friction reduction effect at the first two stages, as a result of enhanced load bearing capacity and reduced deformation degree of the substrate. Unlike graphene, rupture of the Pt-supported MoS2 monolayer was related primarily to out-of-plane compression of the monolayer. These results provide a new insight into the relationship between the mechanical properties and lubrication properties of 2D materials.

Wave phenomena

CERN Document Server

Towne, Dudley H

1988-01-01

This excellent undergraduate-level text emphasizes optics and acoustics, covering inductive derivation of the equation for transverse waves on a string, acoustic plane waves, boundary-value problems, polarization, three-dimensional waves and more. With numerous problems (solutions for about half). ""The material is superbly chosen and brilliantly written"" - Physics Today. Problems. Appendices.

In-plane angular dependence of the spin-wave nonreciprocity of an ultrathin film with Dzyaloshinskii-Moriya interaction

Energy Technology Data Exchange (ETDEWEB)

Zhang, Vanessa Li; Di, Kai; Lim, Hock Siah; Ng, Ser Choon; Kuok, Meng Hau, E-mail: phykmh@nus.edu.sg [Department of Physics, National University of Singapore, Singapore 117551 (Singapore); Yu, Jiawei; Yoon, Jungbum; Qiu, Xuepeng; Yang, Hyunsoo, E-mail: eleyang@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

2015-07-13

The nonreciprocal propagation of spin waves in an ultrathin Pt/Co/Ni film has been measured by Brillouin light scattering. The frequency nonreciprocity, due to the interfacial Dzyaloshinskii-Moriya interaction (DMI), has a sinusoidal dependence on the in-plane angle between the magnon wavevector and the applied magnetic field. The results, which are in good agreement with analytical predictions reported earlier, yield a value of the DMI constant which is the same as that obtained previously from a study of the magnon dispersion relations. We have demonstrated that our magnon-dynamics based method can experimentally ascertain the DMI constant of multilayer thin films.

2.5D S-wave velocity model of the TESZ area in northern Poland from receiver function analysis

Science.gov (United States)

Wilde-Piorko, Monika; Polkowski, Marcin; Grad, Marek

2016-04-01

Receiver function (RF) locally provides the signature of sharp seismic discontinuities and information about the shear wave (S-wave) velocity distribution beneath the seismic station. The data recorded by "13 BB Star" broadband seismic stations (Grad et al., 2015) and by few PASSEQ broadband seismic stations (Wilde-Piórko et al., 2008) are analysed to investigate the crustal and upper mantle structure in the Trans-European Suture Zone (TESZ) in northern Poland. The TESZ is one of the most prominent suture zones in Europe separating the young Palaeozoic platform from the much older Precambrian East European craton. Compilation of over thirty deep seismic refraction and wide angle reflection profiles, vertical seismic profiling in over one hundred thousand boreholes and magnetic, gravity, magnetotelluric and thermal methods allowed for creation a high-resolution 3D P-wave velocity model down to 60 km depth in the area of Poland (Grad et al. 2016). On the other hand the receiver function methods give an opportunity for creation the S-wave velocity model. Modified ray-tracing method (Langston, 1977) are used to calculate the response of the structure with dipping interfaces to the incoming plane wave with fixed slowness and back-azimuth. 3D P-wave velocity model are interpolated to 2.5D P-wave velocity model beneath each seismic station and synthetic back-azimuthal sections of receiver function are calculated for different Vp/Vs ratio. Densities are calculated with combined formulas of Berteussen (1977) and Gardner et al. (1974). Next, the synthetic back-azimuthal sections of RF are compared with observed back-azimuthal sections of RF for "13 BB Star" and PASSEQ seismic stations to find the best 2.5D S-wave models down to 60 km depth. National Science Centre Poland provided financial support for this work by NCN grant DEC-2011/02/A/ST10/00284.

Student Obstacles in Solving Algebraic Thinking Problems

Science.gov (United States)

Andini, W.; Suryadi, D.

2017-09-01

The aim of this research is to analize the student obstacles on solving algebraic thinking problems in low grades elementary school. This research is a preliminary qualitative research, and involved 66 students of grade 3 elementary school. From the analysis student test results, most of student experience difficulty in solving algebraic thinking problems. The main obstacle is the student’s difficulty in understanding the problem of generalizing the pattern because the students are not accustomed to see the rules that exist in generalize the pattern.

Activating basal-plane catalytic activity of two-dimensional MoS2 monolayer with remote hydrogen plasma

KAUST Repository

Cheng, Chia-Chin; Lu, Ang-Yu; Tseng, Chien-Chih; Yang, Xiulin; Hedhili, Mohamed N.; Chen, Min-Cheng; Wei, Kung-Hwa; Li, Lain-Jong

2016-01-01

that account for a small percentage of the surface area, rather than the basal planes, of MoS2 monolayer have been confirmed as their active catalytic sites. As a result, extensive efforts have been developing in activating the basal planes of MoS2

First-order reflection/transmission coefficients for unconverted plane P waves in weakly anisotropic media

Czech Academy of Sciences Publication Activity Database

Farra, V.; Pšenčík, Ivan

2010-01-01

Roč. 183, č. 3 (2010), s. 1443-1454 ISSN 0956-540X R&D Projects: GA ČR GA205/08/0332 Institutional research plan: CEZ:AV0Z30120515 Keywords : body waves * seismic anisotropy * wave propagation Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.411, year: 2010

Sensitivity analysis of P-waves and S-waves to gas hydrate in the Shenhu area using OBS

Science.gov (United States)

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.

Dynamic Obstacle Avoidance for Unmanned Underwater Vehicles Based on an Improved Velocity Obstacle Method

Directory of Open Access Journals (Sweden)

Wei Zhang

2017-11-01

Full Text Available In view of a dynamic obstacle environment with motion uncertainty, we present a dynamic collision avoidance method based on the collision risk assessment and improved velocity obstacle method. First, through the fusion optimization of forward-looking sonar data, the redundancy of the data is reduced and the position, size and velocity information of the obstacles are obtained, which can provide an accurate decision-making basis for next-step collision avoidance. Second, according to minimum meeting time and the minimum distance between the obstacle and unmanned underwater vehicle (UUV, this paper establishes the collision risk assessment model, and screens key obstacles to avoid collision. Finally, the optimization objective function is established based on the improved velocity obstacle method, and a UUV motion characteristic is used to calculate the reachable velocity sets. The optimal collision speed of UUV is searched in velocity space. The corresponding heading and speed commands are calculated, and outputted to the motion control module. The above is the complete dynamic obstacle avoidance process. The simulation results show that the proposed method can obtain a better collision avoidance effect in the dynamic environment, and has good adaptability to the unknown dynamic environment.

Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at $\\sqrt{s_{NN}}$=2.76 TeV

CERN Document Server

Abelev, Betty; Adamova, Dagmar; Adare, Andrew Marshall; Aggarwal, Madan; Aglieri Rinella, Gianluca; Agocs, Andras Gabor; Agostinelli, Andrea; Aguilar Salazar, Saul; Ahammed, Zubayer; Ahmad, Arshad; Ahmad, Nazeer; Ahn, Sang Un; Akindinov, Alexander; Aleksandrov, Dmitry; Alessandro, Bruno; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Almaraz Avina, Erick Jonathan; Alme, Johan; Alt, Torsten; Altini, Valerio; Altinpinar, Sedat; Altsybeev, Igor; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshauser, Harald; Arbor, Nicolas; Arcelli, Silvia; Armesto, Nestor; Arnaldi, Roberta; Aronsson, Tomas Robert; Arsene, Ionut Cristian; Arslandok, Mesut; Augustinus, Andre; Averbeck, Ralf Peter; Awes, Terry; Aysto, Juha Heikki; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bailhache, Raphaelle Marie; Bala, Renu; Baldini Ferroli, Rinaldo; Baldisseri, Alberto; Baldit, Alain; Baltasar Dos Santos Pedrosa, Fernando; Ban, Jaroslav; Baral, Rama Chandra; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Barret, Valerie; Bartke, Jerzy Gustaw; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batyunya, Boris; Baumann, Christoph Heinrich; Bearden, Ian Gardner; Beck, Hans; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bellwied, Rene; Belmont-Moreno, Ernesto; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bergognon, Anais Annick Erica; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhati, Ashok Kumar; Bhom, Jihyun; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Bjelogrlic, Sandro; Blanco, F; Blanco, Francesco; Blau, Dmitry; Blume, Christoph; Bock, Nicolas; Boettger, Stefan; Bogdanov, Alexey; Boggild, Hans; Bogolyubsky, Mikhail; Boldizsar, Laszlo; Bombara, Marek; Book, Julian; Borel, Herve; Borissov, Alexander; Bose, Suvendu Nath; Bossu, Francesco; Botje, Michiel; Boyer, Bruno Alexandre; Braidot, Ermes; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Browning, Tyler Allen; Broz, Michal; Brun, Rene; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Bugaiev, Kyrylo; Busch, Oliver; Buthelezi, Edith Zinhle; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Calvo Villar, Ernesto; Camerini, Paolo; Canoa Roman, Veronica; Cara Romeo, Giovanni; Carena, Francesco; Carena, Wisla; Carminati, Federico; Casanova Diaz, Amaya Ofelia; Castillo Castellanos, Javier Ernesto; Casula, Ester Anna Rita; Catanescu, Vasile; Cavicchioli, Costanza; Ceballos Sanchez, Cesar; Cepila, Jan; Cerello, Piergiorgio; Chang, Beomsu; Chapeland, Sylvain; Charvet, Jean-Luc Fernand; Chattopadhyay, Sukalyan; Chattopadhyay, Subhasis; Chawla, Isha; Cherney, Michael Gerard; Cheshkov, Cvetan; Cheynis, Brigitte; Chiavassa, Emilio; Chibante Barroso, Vasco Miguel; Chinellato, David; Chochula, Peter; Chojnacki, Marek; Choudhury, Subikash; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Coccetti, Fabrizio; Colamaria, Fabio; Colella, Domenico; Conesa Balbastre, Gustavo; Conesa del Valle, Zaida; Constantin, Paul; Contin, Giacomo; Contreras, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortes Maldonado, Ismael; Cortese, Pietro; Cosentino, Mauro Rogerio; Costa, Filippo; Cotallo, Manuel Enrique; Crochet, Philippe; Cruz Alaniz, Emilia; Cuautle, Eleazar; Cunqueiro, Leticia; D'Erasmo, Ginevra; Dainese, Andrea; Dalsgaard, Hans Hjersing; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Kushal; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; de Barros, Gabriel; De Caro, Annalisa; de Cataldo, Giacinto; de Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; De Marco, Nora; De Pasquale, Salvatore; de Rooij, Raoul Stefan; Delagrange, Hugues; Deloff, Andrzej; Demanov, Vyacheslav; Denes, Ervin; Deppman, Airton; Di Bari, Domenico; Di Giglio, Carmelo; Di Liberto, Sergio; Di Mauro, Antonio; Di Nezza, Pasquale; Diaz Corchero, Miguel Angel; Dietel, Thomas; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Dobrowolski, Tadeusz Antoni; Dominguez, Isabel; Donigus, Benjamin; Dordic, Olja; Driga, Olga; Dubey, Anand Kumar; Ducroux, Laurent; Dupieux, Pascal; Dutta Majumdar, AK; Dutta Majumdar, Mihir Ranjan; Elia, Domenico; Emschermann, David Philip; Engel, Heiko; Erdal, Hege Austrheim; Espagnon, Bruno; Estienne, Magali Danielle; Esumi, Shinichi; Evans, David; Eyyubova, Gyulnara; Fabris, Daniela; Faivre, Julien; Falchieri, Davide; Fantoni, Alessandra; Fasel, Markus; Fearick, Roger Worsley; Fedunov, Anatoly; Fehlker, Dominik; Feldkamp, Linus; Felea, Daniel; Fenton-Olsen, Bo; Feofilov, Grigory; Fernandez Tellez, Arturo; Ferretti, Alessandro; Ferretti, Roberta; Figiel, Jan; Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fiore, Enrichetta Maria; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Frankenfeld, Ulrich Michael; Fuchs, Ulrich; Furget, Christophe; Fusco Girard, Mario; Gaardhoje, Jens Joergen; Gagliardi, Martino; Gago, Alberto; Gallio, Mauro; Gangadharan, Dhevan Raja; Ganoti, Paraskevi; Garabatos, Jose; Garcia-Solis, Edmundo; Garishvili, Irakli; Gerhard, Jochen; Germain, Marie; Geuna, Claudio; Gheata, Andrei George; Gheata, Mihaela; Ghidini, Bruno; Ghosh, Premomoy; Gianotti, Paola; Girard, Martin Robert; Giubellino, Paolo; Gladysz-Dziadus, Ewa; Glassel, Peter; Gomez, Ramon; Gonschior, Alexey; Gonzalez Ferreiro, Elena; Gonzalez-Trueba, Laura Helena; Gonzalez-Zamora, Pedro; Gorbunov, Sergey; Goswami, Ankita; Gotovac, Sven; Grabski, Varlen; Graczykowski, Lukasz Kamil; Grajcarek, Robert; Grelli, Alessandro; Grigoras, Alina Gabriela; Grigoras, Costin; Grigoriev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grinyov, Boris; Grion, Nevio; Grosse-Oetringhaus, Jan Fiete; Grossiord, Jean-Yves; Grosso, Raffaele; Guber, Fedor; Guernane, Rachid; Guerra Gutierrez, Cesar; Guerzoni, Barbara; Guilbaud, Maxime Rene Joseph; Gulbrandsen, Kristjan Herlache; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Gutbrod, Hans; Haaland, Oystein Senneset; Hadjidakis, Cynthia Marie; Haiduc, Maria; Hamagaki, Hideki; Hamar, Gergoe; Hanratty, Luke David; Hansen, Alexander; Harmanova, Zuzana; Harris, John William; Hartig, Matthias; Hasegan, Dumitru; Hatzifotiadou, Despoina; Hayrapetyan, Arsen; Heckel, Stefan Thomas; Heide, Markus Ansgar; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Herrmann, Norbert; Hess, Benjamin Andreas; Hetland, Kristin Fanebust; Hicks, Bernard; Hille, Per Thomas; Hippolyte, Boris; Horaguchi, Takuma; Hori, Yasuto; Hristov, Peter Zahariev; Hrivnacova, Ivana; Huang, Meidana; Humanic, Thomas; Hwang, Dae Sung; Ichou, Raphaelle; Ilkaev, Radiy; Ilkiv, Iryna; Inaba, Motoi; Incani, Elisa; Innocenti, Gian Michele; Ippolitov, Mikhail; Irfan, Muhammad; Ivan, Cristian George; Ivanov, Andrey; Ivanov, Marian; Ivanov, Vladimir; Ivanytskyi, Oleksii; Jacholkowski, Adam Wlodzimierz; Jacobs, Peter; Jangal, Swensy Gwladys; Janik, Malgorzata Anna; Janik, Rudolf; Jayarathna, Sandun; Jena, Satyajit; Jha, Deeptanshu Manu; Jimenez Bustamante, Raul Tonatiuh; Jirden, Lennart; Jones, Peter Graham; Jung, Hyung Taik; Jusko, Anton; Kakoyan, Vanik; Kalcher, Sebastian; Kalinak, Peter; Kalliokoski, Tuomo Esa Aukusti; Kalweit, Alexander Philipp; Kanaki, Kalliopi; Kang, Ju Hwan; Kaplin, Vladimir; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karpechev, Evgeny; Kazantsev, Andrey; Kebschull, Udo Wolfgang; Keidel, Ralf; Khan, Mohisin Mohammed; Khan, Palash; Khan, Shuaib Ahmad; Khanzadeev, Alexei; Kharlov, Yury; Kileng, Bjarte; Kim, Beomkyu; Kim, Dong Jo; Kim, Do Won; Kim, Jonghyun; Kim, Jin Sook; Kim, Minwoo; Kim, Mimae; Kim, Se Yong; Kim, Seon Hee; Kim, Taesoo; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Klay, Jennifer Lynn; Klein, Jochen; Klein-Bosing, Christian; Kluge, Alexander; Knichel, Michael Linus; Knospe, Anders Garritt; Koch, Kathrin; Kohler, Markus; Kolojvari, Anatoly; Kondratiev, Valery; Kondratyeva, Natalia; Konevskih, Artem; Korneev, Andrey; Kour, Ravjeet; Kowalski, Marek; Kox, Serge; Koyithatta Meethaleveedu, Greeshma; Kral, Jiri; Kralik, Ivan; Kramer, Frederick; Kraus, Ingrid Christine; Krawutschke, Tobias; Krelina, Michal; Kretz, Matthias; Krivda, Marian; Krizek, Filip; Krus, Miroslav; Kryshen, Evgeny; Krzewicki, Mikolaj; Kucheriaev, Yury; Kuhn, Christian Claude; Kuijer, Paul; Kulakov, Igor; Kurashvili, Podist; Kurepin, A; Kurepin, AB; Kuryakin, Alexey; Kushpil, Svetlana; Kushpil, Vasily; Kweon, Min Jung; Kwon, Youngil; La Pointe, Sarah Louise; La Rocca, Paola; Ladron de Guevara, Pedro; Lakomov, Igor; Langoy, Rune; Lara, Camilo Ernesto; Lardeux, Antoine Xavier; Lazzeroni, Cristina; Le Bornec, Yves; Lea, Ramona; Lechman, Mateusz; Lee, Graham Richard; Lee, Ki Sang; Lee, Sung Chul; Lefevre, Frederic; Lehnert, Joerg Walter; Leistam, Lars; Lemmon, Roy Crawford; Lenhardt, Matthieu Laurent; Lenti, Vito; Leon Monzon, Ildefonso; Leon Vargas, Hermes; Leoncino, Marco; Levai, Peter; Lien, Jorgen; Lietava, Roman; Lindal, Svein; Lindenstruth, Volker; Lippmann, Christian; Lisa, Michael Annan; Liu, Lijiao; Loenne, Per-Ivar; Loggins, Vera; Loginov, Vitaly; Lohn, Stefan Bernhard; Lohner, Daniel; Loizides, Constantinos; Loo, Kai Krister; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lovhoiden, Gunnar; Lu, Xianguo; Luettig, Philipp; Lunardon, Marcello; Luo, Jiebin; Luparello, Grazia; Luquin, Lionel; Luzzi, Cinzia; Ma, Rongrong; Maevskaya, Alla; Mager, Magnus; Mahapatra, Durga Prasad; Maire, Antonin; Mal'Kevich, Dmitry; Malaev, Mikhail; Maldonado Cervantes, Ivonne Alicia; Malinina, Ludmila; Malzacher, Peter; Mamonov, Alexander; Manceau, Loic Henri Antoine; Manko, Vladislav; Manso, Franck; Manzari, Vito; Mao, Yaxian; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Marin, Ana Maria; Marin Tobon, Cesar Augusto; Markert, Christina; Martashvili, Irakli; Martinengo, Paolo; Martinez, Mario Ivan; Martinez Davalos, Arnulfo; Martinez Garcia, Gines; Martynov, Yevgen; Mas, Alexis Jean-Michel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Mastromarco, Mario; Mastroserio, Annalisa; Matthews, Zoe Louise; Matyja, Adam Tomasz; Mayani, Daniel; Mayer, Christoph; Mazer, Joel; Mazzoni, Alessandra Maria; Meddi, Franco; Menchaca-Rocha, Arturo Alejandro; Mercado Perez, Jorge; Meres, Michal; Miake, Yasuo; Milano, Leonardo; Milosevic, Jovan; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz; Mitu, Ciprian Mihai; Mlynarz, Jocelyn; Mohanty, Ajit Kumar; Mohanty, Bedangadas; Molnar, Levente; Montano Zetina, Luis Manuel; Monteno, Marco; Montes, Esther; Moon, Taebong; Morando, Maurizio; Moreira De Godoy, Denise Aparecida; Moretto, Sandra; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhuri, Sanjib; Mukherjee, Maitreyee; Muller, Hans; Munhoz, Marcelo; Musa, Luciano; Musso, Alfredo; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Nattrass, Christine; Naumov, Nikolay; Navin, Sparsh; Nayak, Tapan Kumar; Nazarenko, Sergey; Nazarov, Gleb; Nedosekin, Alexander; Nicassio, Maria; Niculescu, Mihai; Nielsen, Borge Svane; Niida, Takafumi; Nikolaev, Sergey; Nikolic, Vedran; Nikulin, Sergey; Nikulin, Vladimir; Nilsen, Bjorn Steven; Nilsson, Mads Stormo; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Novitzky, Norbert; Nyanin, Alexandre; Nyatha, Anitha; Nygaard, Casper; Nystrand, Joakim Ingemar; Oeschler, Helmut Oskar; Oh, Saehanseul; Oh, Sun Kun; Oleniacz, Janusz; Oppedisano, Chiara; Ortona, Giacomo; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Pachmayer, Yvonne Chiara; Pachr, Milos; Padilla, Fatima; Pagano, Paola; Paic, Guy; Painke, Florian; Pajares, Carlos; Pal, S; Pal, Susanta Kumar; Palaha, Arvinder Singh; Palmeri, Armando; Papikyan, Vardanush; Pappalardo, Giuseppe; Park, Woo Jin; Passfeld, Annika; Patalakha, Dmitri Ivanovich; Paticchio, Vincenzo; Pavlinov, Alexei; Pawlak, Tomasz Jan; Peitzmann, Thomas; Pereira Da Costa, Hugo Denis Antonio; Pereira De Oliveira Filho, Elienos; Peresunko, Dmitri; Perez Lara, Carlos Eugenio; Perez Lezama, Edgar; Perini, Diego; Perrino, Davide; Peryt, Wiktor Stanislaw; Pesci, Alessandro; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petran, Michal; Petris, Mariana; Petrov, Plamen Rumenov; Petrovici, Mihai; Petta, Catia; Piano, Stefano; Piccotti, Anna; Pikna, Miroslav; Pillot, Philippe; Pinazza, Ombretta; Pinsky, Lawrence; Pitz, Nora; Piuz, Francois; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polichtchouk, Boris; Pop, Amalia; Porteboeuf-Houssais, Sarah; Pospisil, Vladimir; Potukuchi, Baba; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puchagin, Sergey; Puddu, Giovanna; Pujahari, Prabhat Ranjan; Pujol Teixido, Jordi; Pulvirenti, Alberto; Punin, Valery; Putis, Marian; Putschke, Jorn Henning; Quercigh, Emanuele; Qvigstad, Henrik; Rachevski, Alexandre; Rademakers, Alphonse; Radomski, Sylwester; Raiha, Tomi Samuli; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Ramirez Reyes, Abdiel; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Read, Kenneth Francis; Real, Jean-Sebastien; Redlich, Krzysztof; Reichelt, Patrick; Reicher, Martijn; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Rettig, Felix Vincenz; Revol, Jean-Pierre; Reygers, Klaus Johannes; Riccati, Lodovico; Ricci, Renato Angelo; Richert, Tuva; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Rodrigues Fernandes Rabacal, Bartolomeu; Rodriguez Cahuantzi, Mario; Rodriguez Manso, Alis; Roed, Ketil; Rohr, David; Rohrich, Dieter; Romita, Rosa; Ronchetti, Federico; Rosnet, Philippe; Rossegger, Stefan; Rossi, Andrea; Roy, Christelle Sophie; Roy, Pradip Kumar; Rubio Montero, Antonio Juan; Rui, Rinaldo; Russo, Riccardo; Ryabinkin, Evgeny; Rybicki, Andrzej; Sadovsky, Sergey; Safarik, Karel; Sahoo, Raghunath; Sahu, Pradip Kumar; Saini, Jogender; Sakaguchi, Hiroaki; Sakai, Shingo; Sakata, Dosatsu; Salgado, Carlos Albert; Salzwedel, Jai; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sanchez Castro, Xitzel; Sandor, Ladislav; Sandoval, Andres; Sano, Masato; Sano, Satoshi; Santo, Rainer; Santoro, Romualdo; Sarkamo, Juho Jaako; Scapparone, Eugenio; Scarlassara, Fernando; Scharenberg, Rolf Paul; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schreiner, Steffen; Schuchmann, Simone; Schukraft, Jurgen; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Scott, Patrick Aaron; Scott, Rebecca; Segato, Gianfranco; Selyuzhenkov, Ilya; Senyukov, Serhiy; Seo, Jeewon; Serci, Sergio; Serradilla, Eulogio; Sevcenco, Adrian; Shabetai, Alexandre; Shabratova, Galina; Shahoyan, Ruben; Sharma, Natasha; Sharma, Satish; Shigaki, Kenta; Shimomura, Maya; Shtejer, Katherin; Sibiriak, Yury; Siciliano, Melinda; Sicking, Eva; Siddhanta, Sabyasachi; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Silvestre, catherine; Simatovic, Goran; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singha, Subhash; Singhal, Vikas; Sinha, Bikash; Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Skjerdal, Kyrre; Smakal, Radek; Smirnov, Nikolai; Snellings, Raimond; Sogaard, Carsten; Soltz, Ron Ariel; Son, Hyungsuk; Song, Jihye; Song, Myunggeun; Soos, Csaba; Soramel, Francesca; Sputowska, Iwona; Spyropoulou-Stassinaki, Martha; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stefanek, Grzegorz; Stefanini, Giorgio; Steinbeck, Timm Morten; Steinpreis, Matthew; Stenlund, Evert Anders; Steyn, Gideon Francois; Stiller, Johannes Hendrik; Stocco, Diego; Stolpovskiy, Mikhail; Strabykin, Kirill; Strmen, Peter; Suaide, Alexandre Alarcon do Passo; Subieta Vasquez, Martin Alfonso; Sugitate, Toru; Suire, Christophe Pierre; Sukhorukov, Mikhail; Sultanov, Rishat; Sumbera, Michal; Susa, Tatjana; Szanto de Toledo, Alejandro; Szarka, Imrich; Szczepankiewicz, Adam; Szostak, Artur Krzysztof; Szymanski, Maciej; Takahashi, Jun; Tapia Takaki, Daniel Jesus; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terrevoli, Cristina; Thader, Jochen Mathias; Thomas, Deepa; Tieulent, Raphael Noel; Timmins, Anthony; Toia, Alberica; Torii, Hisayuki; Tosello, Flavio; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ulery, Jason Glyndwr; Ullaland, Kjetil; Ulrich, Jochen; Uras, Antonio; Urban, Jozef; Urciuoli, Guido Marie; Usai, Gianluca; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; van der Kolk, Naomi; van Leeuwen, Marco; Vande Vyvre, Pierre; Vannucci, Luigi; Vargas, Aurora Diozcora; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vechernin, Vladimir; Veldhoen, Misha; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara, Sergio; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Vikhlyantsev, Oleg; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Leonid; Vinogradov, Yury; Virgili, Tiziano; Viyogi, Yogendra; Vodopianov, Alexander; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; von Haller, Barthelemy; Vranic, Danilo; Øvrebekk, Gaute; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Vladimir; Wan, Renzhuo; Wang, Dong; Wang, Mengliang; Wang, Yifei; Wang, Yaping; Watanabe, Kengo; Weber, Michael; Wessels, Johannes; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Alexander; Wilk, Grzegorz Andrzej; Williams, Crispin; Windelband, Bernd Stefan; Xaplanteris Karampatsos, Leonidas; Yaldo, Chris G; Yamaguchi, Yorito; Yang, Hongyan; Yang, Shiming; Yasnopolsky, Stanislav; Yi, JunGyu; Yin, Zhongbao; Yoo, In-Kwon; Yoon, Jongik; Yu, Weilin; Yuan, Xianbao; Yushmanov, Igor; Zach, Cenek; Zampolli, Chiara; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zaviyalov, Nikolai; Zbroszczyk, Hanna Paulina; Zelnicek, Pierre; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Haitao; Zhang, Xiaoming; Zhou, Daicui; Zhou, Fengchu; Zhou, You; Zhu, Jianhui; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zinovjev, Gennady; Zoccarato, Yannick Denis; Zynovyev, Mykhaylo; Zyzak, Maksym

2013-02-12

The elliptic, $v_2$, triangular, $v_3$, and quadrangular, $v_4$, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions, and (anti-)protons in Pb–Pb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range |$\\eta$|8 GeV/c. The small $p_T$ dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to $p_T$ =8 GeV/c. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least $p_T$ =8 GeV/c indicating that the particle type dependence persists out to high $p_T$.

The plain truth about forming a plane wave of neutrons

Energy Technology Data Exchange (ETDEWEB)

Wagh, Apoorva G., E-mail: nintsspd@barc.gov.i [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Abbas, Sohrab [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Treimer, Wolfgang [Helmholtz Zentrum Berlin, Glienicker Str. 100, D-14109 Berlin (Germany)

2011-04-01

We have attained the first sub-arcsecond collimation of a monochromatic neutron beam by diffracting neutrons from a Bragg prism, viz. a single crystal prism operating in the vicinity of Bragg incidence. Analytical as well numerical computations based on the dynamical diffraction theory, led to the optimised collimator configuration of a silicon {l_brace}1 1 1{r_brace} Bragg prism for 5.26 A neutrons. We fabricated a Bragg prism to these specifications, tested and operated it at the double diffractometer setup in Helmholtz Zentrum Berlin to produce a 0.58 arcsec wide monochromatic neutron beam. With a similarly optimised Bragg prism analyser of opposite asymmetry, we recorded a 0.62 arcsec wide virgin rocking curve for this ultra-parallel beam. With this nearly plane-wave neutron beam, we have recorded the first ever USANS spectrum in Q{approx}10{sup -6} A{sup -1} range with a hydroxyapatite casein protein sample and demonstrated the instrument capability to characterise agglomerates up to 150 {mu}m in size. The super-collimated monochromatic beam has also enabled us to record the first neutron diffraction pattern from a macroscopic grating of 200 {mu}m period. The transverse coherence length of 175 {mu}m (FWHM) of the ultra-parallel beam derived from the analysis of this pattern, is the greatest achieved to date for A wavelength neutrons.

Supersonic flows past an obstacle in Yukawa liquids

Science.gov (United States)

Charan, Harish; Ganesh, Rajaraman

2018-04-01

Shock formation, when a supersonic flow passes a stationary obstacle, is ubiquitous in nature. Considering particles mediating via a Yukawa-type interaction as a prototype for a strongly coupled complex plasma, characterized by coupling strength (Γ, ratio of the average potential to kinetic energy per particle) and screening parameter (κ, ratio of the mean inter-particle distance to the shielding length), we address the fundamental problem of supersonic fluid flow U0, past a stationary obstacle immersed in this strongly coupled system. We here report the results on the bow shocks formed in Yukawa liquids when the liquid flows at speeds larger than the speed of sound in the system. Depending on the values of Mach number MC L=U/0 CL , where CL is the longitudinal speed of sound in the system, the bow shocks are found to be either traveling or localized. We find that for the transonic flows (0.8 ≲ MC L≲ 1.2), the bow shocks travel in the upstream direction opposite to the incoming fluid. The phase velocity of the traveling bow shocks is found to be a non-monotonous function of κ, varying as ∝1 /k1.11 at a fixed value of Γ, and is found to be independent of Γ at a fixed value of κ. It is observed that for the flow values with MC L>1.5 , the shock waves do not travel in the upstream direction but instead form a stationary arc like structure around the obstacle. For the fluid flows with 1 ≲ MC L≲ 2.6 , secondary bow shocks are seen to emerge behind the stationary obstacle which travel in the downstream direction, and the phase velocity of these secondary bow shocks is found to be equal to that of the primary bow shocks.

A phase-plane analysis of localized frictional waves

Science.gov (United States)

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.

What is the difference in the p-wave and s-wave photodetachment in an electric field?

OpenAIRE

Du, M. L.

2009-01-01

By applying closed-orbit theory to an existing model, a simple formula is derived for the modulation function of s-wave photo-detachment in the presence of a static electric field. We then compare the s-wave modulation function with the p-wave modulation function. We show the maximums (minimums) in the s-wave modulation function correspond to the minimums (maximums) in the p-wave modulation function because of a phase difference of $\\pi$ in their oscillations. The oscillation amplitude in the...

Experimental and numerical study of guided wave propagation in a thin metamaterial plate

International Nuclear Information System (INIS)

Zhu, R.; Huang, G.L.; Huang, H.H.; Sun, C.T.

2011-01-01

In this Letter, both in-plane and out-of-plane guided waves in a thin plate with local resonators are studied numerically and experimentally. Through the numerical simulation, a new metamaterial plate design is achieved for a low-frequency bandgap in both in-plane and out-of-plane guided waves. Experiments were conducted to validate the numerical design. In the experiment, piezoelectric transducers were used to generate and receive guided wave signals. The results show that the numerical predictions are in very good agreement with the experimental measurements. Specifically, the connection between the local resonance in the thin plate and its wave attenuation mechanism was discussed. -- Highlights: → Both in-plane and out-of-plane guided waves in a thin plate with local resonators are studied numerically and experimentally. → A new metamaterial plate design is achieved for a low-frequency bandgap in both in-plane and out-of-plane guided waves. → Experiments were conducted to validate the numerical design. → The connection between the local resonance in the thin plate and its wave attenuation mechanism was investigated.

Application of the model of the relativistic anti-loss-cone distribution to ECE spectrum in discharge applying LH wave

International Nuclear Information System (INIS)

Sato, Masayasu; Yokomizo, Hideaki

1987-11-01

The electron cyclotron emission (ECE) is dominated from supra-thermal electron in discharge applying LH wave. We obtain informations of supra-thermal electron by applying the model of the relativistic anti-loss-cone distribution to ECE spectrum in the discharge. In this model, the emission perpendicular to the magnetic field are considered. The frequency range is considered to be well above the plasma and electron cyclotron frequencies, thus collective effects can be neglected. The electron distribution is assumed to be anisotropic in the velocity space and strongly extended in the direction parallel to the magnetic field, namely the relativistic anti-loss-cone distribution. The informations of supra-thermal electron are obtained by the following way. The temperature and density of the supra-thermal electron and the anti-loss-cone angle are obtained from the power spectrum of LH wave launched, the measured slope of the spectrum of ECE and the spectral radiance of ECE. (author)

The comparison of spatial accessibility measures between non-obstacle and obstacle oriented based on gravity model

Science.gov (United States)

Han, Zhi-Gang; Cui, Cai-Hui

2009-10-01

Spatial accessibility denotes the ease with which activities may be reached from a given location using a particular transportation system. There are a number of accessibility measures methods and models, such as time of access to city centre, mean travel costs and opportunity accessibility. But these methods or models ignore the existence of obstacles. In fact, there are many kinds of obstacles in the world, such as rivers, railways, etc. The paper reviews the progress of accessibility measures, and introduces the obstacle to the accessibility measures. Meanwhile, through the analysis of A* algorithm, the advantage of A* algorithm that could avoid obstacles is put forward. Based on the above mentioned, the obstacle oriented accessibility measures based on simple gravity model is discussed in details. Finally, a case study is fulfilled by comparison between the obstacle oriented and non-obstacle accessibility measures.

17O NMR Study of Undoped and Lightly Hole Doped CuO2 Planes

International Nuclear Information System (INIS)

Thurber, K.R.; Hunt, A.W.; Imai, T.; Chou, F.C.; Lee, Y.S.

1997-01-01

Using 17 O NMR, we probed the short wavelength excitations in the CuO 2 planes of insulating and weakly metallic high T c cuprates. We measured the spin wave damping for an S=1/2 2D quantum Heisenberg antiferromagnet for the first time. The results establish the nearly free behavior (asymptotic freedom) of the high energy spin waves, even without long range magnetic order. Light hole doping dramatically enhances the low energy excitation spectrum below 300K. copyright 1997 The American Physical Society

Transmitting information of an object behind the obstacle to infinity

Science.gov (United States)

Xu, Bai Bing; Jiang, Wei Xiang; Meng, Ling Ling; Cui, Tie Jun

2015-08-01

We propose an illusion device that transforms a metallic cylinder into a Luneburg lens by using transformation optics. Such a transformed focusing lens guides electromagnetic waves to propagate around the central metallic cylinder smoothly and be focused on one spot, and thus the information of an object behind the obstacle can be transmitted to infinity. In order to realize the required-anisotropic parameters with high permittivity and low permeability, we design embedded split-ring resonators (SRRs) to increase the permittivity of the traditional SRR structures. In experiments, we fabricate and measure the transformed lens, and the tested results agree well with the numerical simulations and theoretical predictions. The proposed transformation lens can mimic some properties of Einstein gravitational lens because their wave propagation behaviors are very similar.

Generation and Propagation of Finite-Amplitude Waves in Flexible Tubes (A)

DEFF Research Database (Denmark)

Jensen, Leif Bjørnø

1972-01-01

Highly reproducible finite-amplitude waves, generated by a modified electromagnetic plane-wave generator, characterized by a rise time......Highly reproducible finite-amplitude waves, generated by a modified electromagnetic plane-wave generator, characterized by a rise time...

Effect of transparency on the Josephson junction between D-wave superconductors

International Nuclear Information System (INIS)

Rashedi, G

2008-01-01

In this paper, a dc Josephson junction between two singlet superconductors (d-wave and s-wave) with arbitrary reflection coefficient has been investigated theoretically following the famous paper [Y. Tanaka and S. Kashiwaya 1996 Phys. Rev. B 53, R11957]. For the case of High T c superconductors, the c-axes are parallel to an interface with finite transparency and their ab-planes have a mis-orientation. The effect of transparency and mis-orientation on the currents is studied both analytically and numerically. It is observed that, the current phase relations are totally different from the case of ideal transparent Josephson junctions between d-wave superconductors and two s-wave superconductors. This apparatus can be used to demonstrate d-wave order parameter in High T c superconductors

ESTIMA, Neutron Width Level Spacing, Neutron Strength Function of S- Wave, P-Wave Resonances

International Nuclear Information System (INIS)

Fort, E.

1982-01-01

1 - Description of problem or function: ESTIMA calculates level spacing and neutron strength function of a mixed sequence of s- and p-wave resonances given a set of neutron widths as input parameters. Three algorithms are used, two of which calculate s-wave average parameters and assume that the reduced widths obey a Porter-Thomas distribution truncated by a minimum detection threshold. The third performs a maximum likelihood fit to a truncated chi-squared distribution of any specified number of degrees of freedom, i.e. it can be used for calculating s-wave or p-wave average parameters. Resonances of undeclared angular orbital momentum are divided into groups of probable s-wave and probable p-wave by a simple application of Bayes' Theorem. 2 - Method of solution: Three algorithms are used: i) GAMN method, based on simple moments properties of a Porter-Thomas distribution. ii) Missing Level Estimator, a simplified version of the algorithm used by the program BAYESZ. iii) ESTIMA, a maximum likelihood fit. 3 - Restrictions on the complexity of the problem: A maximum of 400 resonances is allowed in the version available from NEADB, however this restriction can be relaxed by increasing array dimensions

Deep Downhole Seismic Testing at the Waste Treatment Plant Site, Hanford, WA. Volume V S-Wave Measurements in Borehole C4996 Seismic Records, Wave-Arrival Identifications and Interpreted S-Wave Velocity Profile.

Energy Technology Data Exchange (ETDEWEB)

Stokoe, Kenneth H.; Li, Song Cheng; Cox, Brady R.; Menq, Farn-Yuh

2007-06-06

Velocity measurements in shallow sediments from ground surface to approximately 370 to 400 feet bgs were collected by Redpath Geophysics using impulsive S- and P-wave seismic sources (Redpath 2007). Measurements below this depth within basalt and sedimentary interbeds were made by UTA between October and December 2006 using the T-Rex vibratory seismic source in each of the three boreholes. Results of these measurements including seismic records, wave-arrival identifications and interpreted velocity profiles are presented in the following six volumes: I. P-Wave Measurements in Borehole C4993 II. P-Wave Measurements in Borehole C4996 III. P-Wave Measurements in Borehole C4997 IV. S-Wave Measurements in Borehole C4993 V. S-Wave Measurements in Borehole C4996 VI. S-Wave Measurements in Borehole C4997 In this volume (V), all S-wave measurements are presented that were performed in Borehole C4996 at the WTP with T-Rex as the seismic source and the Lawrence Berkeley National Laboratory (LBNL) 3-D wireline geophone as the at-depth borehole receiver.

Deep Downhole Seismic Testing at the Waste Treatment Plant Site, Hanford, WA. Volume VI S-Wave Measurements in Borehole C4997 Seismic Records, Wave-Arrival Identifications and Interpreted S-Wave Velocity Profile.

Energy Technology Data Exchange (ETDEWEB)

Stokoe, Kenneth H.; Li, Song Cheng; Cox, Brady R.; Menq, Farn-Yuh

2007-06-06

Velocity measurements in shallow sediments from ground surface to approximately 370 to 400 feet bgs were collected by Redpath Geophysics using impulsive S- and P-wave seismic sources (Redpath 2007). Measurements below this depth within basalt and sedimentary interbeds were made by UTA between October and December 2006 using the T-Rex vibratory seismic source in each of the three boreholes. Results of these measurements including seismic records, wave-arrival identifications and interpreted velocity profiles are presented in the following six volumes: I. P-Wave Measurements in Borehole C4993 II. P-Wave Measurements in Borehole C4996 III. P-Wave Measurements in Borehole C4997 IV. S-Wave Measurements in Borehole C4993 V. S-Wave Measurements in Borehole C4996 VI. S-Wave Measurements in Borehole C4997 In this volume (VI), all S-wave measurements are presented that were performed in Borehole C4997 at the WTP with T-Rex as the seismic source and the Lawrence Berkeley National Laboratory (LBNL) 3-D wireline geophone as the at-depth borehole receiver.

Designing broad phononic band gaps for in-plane modes

Science.gov (United States)

Li, Yang Fan; Meng, Fei; Li, Shuo; Jia, Baohua; Zhou, Shiwei; Huang, Xiaodong

2018-03-01

Phononic crystals are known as artificial materials that can manipulate the propagation of elastic waves, and one essential feature of phononic crystals is the existence of forbidden frequency range of traveling waves called band gaps. In this paper, we have proposed an easy way to design phononic crystals with large in-plane band gaps. We demonstrated that the gap between two arbitrarily appointed bands of in-plane mode can be formed by employing a certain number of solid or hollow circular rods embedded in a matrix material. Topology optimization has been applied to find the best material distributions within the primitive unit cell with maximal band gap width. Our results reveal that the centroids of optimized rods coincide with the point positions generated by Lloyd's algorithm, which deepens our understandings on the formation mechanism of phononic in-plane band gaps.

Evaluation of Iowa?s anti-bullying law

OpenAIRE

Ramirez, Marizen; Ten Eyck, Patrick; Peek-Asa, Corinne; Onwuachi-Willig, Angela; Cavanaugh, Joseph E.

2016-01-01

Background Bullying is the most common form of youth aggression. Although 49 of all 50 states in the U.S. have an anti-bullying law in place to prevent bullying, little is known about the effectiveness of these laws. Our objective was to measure the effectiveness of Iowa?s anti-bullying law in preventing bullying and improving teacher response to bullying. Methods Sixth, 8th, and 11th grade children who completed the 2005, 2008 and 2010 Iowa Youth Survey were included in this study (n?=?253,0...

Time-domain analytic Solutions of two-wire transmission line excited by a plane-wave field

Institute of Scientific and Technical Information of China (English)

Ni Gu-Yan; Yan Li; Yuan Nai-Chang

2008-01-01

This paper reports that an analytic method is used to calculate the load responses of the two-wire transmission line excited by a plane-wave directly in the time domain.By the frequency-domain Baum-Liu-Tesche(BLT)equation,the time-domain analytic solutions are obtained and expressed in an infinite geometric series.Moreover,it is shown that there exist only finite nonzero terms in the infinite geometric series if the time variate is at a finite interval.In other word.the time-domain analytic solutions are expanded in a finite geometric series indeed if the time variate is at a finite interval.The computed results are subsequently compared with transient responses obtained by using the frequency-domain BLT equation via a fast Fourier transform,and the agreement is excellent.

A soft robot capable of 2D mobility and self-sensing for obstacle detection and avoidance

Science.gov (United States)

Qin, Lei; Tang, Yucheng; Gupta, Ujjaval; Zhu, Jian

2018-04-01

Soft robots have shown great potential for surveillance applications due to their interesting attributes including inherent flexibility, extreme adaptability, and excellent ability to move in confined spaces. High mobility combined with the sensing systems that can detect obstacles plays a significant role in performing surveillance tasks. Extensive studies have been conducted on movement mechanisms of traditional hard-bodied robots to increase their mobility. However, there are limited efforts in the literature to explore the mobility of soft robots. In addition, little attempt has been made to study the obstacle-detection capability of a soft mobile robot. In this paper, we develop a soft mobile robot capable of high mobility and self-sensing for obstacle detection and avoidance. This robot, consisting of a dielectric elastomer actuator as the robot body and four electroadhesion actuators as the robot feet, can generate 2D mobility, i.e. translations and turning in a 2D plane, by programming the actuation sequence of the robot body and feet. Furthermore, we develop a self-sensing method which models the robot body as a deformable capacitor. By measuring the real-time capacitance of the robot body, the robot can detect an obstacle when the peak capacitance drops suddenly. This sensing method utilizes the robot body itself instead of external sensors to achieve detection of obstacles, which greatly reduces the weight and complexity of the robot system. The 2D mobility and self-sensing capability ensure the success of obstacle detection and avoidance, which paves the way for the development of lightweight and intelligent soft mobile robots.

Evasion of HSR in S-wave charmonium decaying to P-wave light hadrons

Energy Technology Data Exchange (ETDEWEB)

Li, Gang [Qufu Normal University, Department of Physics, Qufu (China); Liu, Xiao-Hai [Peking University, Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Beijing (China); Zhao, Qiang [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China); CAS, Theoretical Physics Center for Science Facilities, Beijing (China)

2013-09-15

The S-wave charmonium decaying to a P-wave and S-wave light hadron pairs are supposed to be suppressed by the helicity selection rule in the perturbative QCD framework. With an effective Lagrangian method, we show that the intermediate charmed meson loops can provide a possible mechanism for the evasion of the helicity selection rule, and result in sizeable decay branching ratios in some of those channels. The theoretical predictions can be examined by the forthcoming BES-III data in the near future. (orig.)

Three-dimensional sheaf of ultrasound planes reconstruction (SOUPR) of ablated volumes.

Science.gov (United States)

Ingle, Atul; Varghese, Tomy

2014-08-01

This paper presents an algorithm for 3-D reconstruction of tumor ablations using ultrasound shear wave imaging with electrode vibration elastography. Radio-frequency ultrasound data frames are acquired over imaging planes that form a subset of a sheaf of planes sharing a common axis of intersection. Shear wave velocity is estimated separately on each imaging plane using a piecewise linear function fitting technique with a fast optimization routine. An interpolation algorithm then computes velocity maps on a fine grid over a set of C-planes that are perpendicular to the axis of the sheaf. A full 3-D rendering of the ablation can then be created from this stack of C-planes; hence the name "Sheaf Of Ultrasound Planes Reconstruction" or SOUPR. The algorithm is evaluated through numerical simulations and also using data acquired from a tissue mimicking phantom. Reconstruction quality is gauged using contrast and contrast-to-noise ratio measurements and changes in quality from using increasing number of planes in the sheaf are quantified. The highest contrast of 5 dB is seen between the stiffest and softest regions of the phantom. Under certain idealizing assumptions on the true shape of the ablation, good reconstruction quality while maintaining fast processing rate can be obtained with as few as six imaging planes suggesting that the method is suited for parsimonious data acquisitions with very few sparsely chosen imaging planes.

Development and implementation of a pressure propagation code applicable in spherical geometry to euler/isentropic/acoustic modelling. Comparative treatment of shock-up and refection on simplified rigid or elastic obstacles

International Nuclear Information System (INIS)

Essers, J.A.

1987-01-01

A sophisticated computer code for the calculation of plane or spherical pressure waves and their reflection on a simplified rigid or flexible obstacle has been constructed. Different options: choice of explicit or implicit scheme, use of eulerian, isentropic or acoustic flow models, introduction of different artificial viscosities, use of uniform or non-uniform adaptive grids have been made available and validated by simple shock waves computations. The results from different numerical experiments are presented. They have been used to evaluate the values of artificial viscosity coefficients leading to acceptable pressure pulses. In particular, the following important conclusions have been confirmed: - the linear acoustic model leads to important errors except for extremely weak overpressures; - an excellent accuracy can be obtained with the non-linear isentropic model in a wide overpressure range; - as opposed to the eulerian and to the non-linear isentropic models, the acoustic model is completely uncapable of predicting the shock-up phenomenon, and can therefore lead to important errors in the prediction of the pulse shape even for very weak overpressures

Spin-waves in antiferromagnetic single crystal LiFePO$_4$

OpenAIRE

Li, Jiying; Garlea, Vasile O.; Zarestky, Jerel L.; Vaknin, David

2005-01-01

Spin-wave dispersions in the antiferromagnetic state of single crystal LiFePO$_4$ were determined by inelastic neutron scattering measurements. The dispersion curves measured from the (010) reflection along both {\\it a}$^\\ast$ and {\\it b}$^\\ast$ reciprocal-space directions reflect the anisotropic coupling of the layered Fe$^{2+}$ (S = 2) spin-system. The spin-wave dispersion curves were theoretically modeled using linear spin-wave theory by including in the spin-Hamiltonian in-plane nearest- ...

Robust obstacle detection for unmanned surface vehicles

Science.gov (United States)

Qin, Yueming; Zhang, Xiuzhi

2018-03-01

Obstacle detection is of essential importance for Unmanned Surface Vehicles (USV). Although some obstacles (e.g., ships, islands) can be detected by Radar, there are many other obstacles (e.g., floating pieces of woods, swimmers) which are difficult to be detected via Radar because these obstacles have low radar cross section. Therefore, detecting obstacle from images taken onboard is an effective supplement. In this paper, a robust vision-based obstacle detection method for USVs is developed. The proposed method employs the monocular image sequence captured by the camera on the USVs and detects obstacles on the sea surface from the image sequence. The experiment results show that the proposed scheme is efficient to fulfill the obstacle detection task.

Gravitational waves in Einstein-æther and generalized TeVeS theory after GW170817

Science.gov (United States)

Gong, Yungui; Hou, Shaoqi; Liang, Dicong; Papantonopoulos, Eleftherios

2018-04-01

In this work we discuss the polarization contents of Einstein-æther theory and the generalized tensor-vector-scalar (TeVeS) theory, as both theories have a normalized timelike vector field. We derive the linearized equations of motion around the flat spacetime background using the gauge-invariant variables to easily separate physical degrees of freedom. We find the plane wave solutions and identify the polarizations by examining the geodesic deviation equations. We find that there are five polarizations in Einstein-æther theory and six polarizations in the generalized TeVeS theory. In particular, the transverse breathing mode is mixed with the pure longitudinal mode. We also discuss the experimental tests of the extra polarizations in Einstein-æther theory using pulsar timing arrays combined with the gravitational-wave speed bound derived from the observations on GW 170817 and GRB 170817A. It turns out that it might be difficult to use pulsar timing arrays to distinguish different polarizations in Einstein-æther theory. The same speed bound also forces one of the propagating modes in the generalized TeVeS theory to travel much faster than the speed of light. Since the strong coupling problem does not exist in some parameter subspaces, the generalized TeVeS theory is excluded in these parameter subspaces.

An obstacle detection system using binocular stereo fisheye lenses for planetary rover navigation

Science.gov (United States)

Liu, L.; Jia, J.; Li, L.

In this paper we present an implementation of an obstacle detection system using binocular stereo fisheye lenses for planetary rover navigation The fisheye lenses can improve image acquisition efficiency and handle minimal clearance recovery problem because they provide a large field of view However the fisheye lens introduces significant distortion in the image and this will make it much more difficult to find a one-to-one correspondence In addition we have to improve the system accuracy and efficiency for robot navigation To compute dense depth maps accurately in real time the following five key issues are considered 1 using lookup tables for a tradeoff between time and space in fisheye distortion correction and correspondence matching 2 using an improved incremental calculation scheme for algorithmic optimization 3 multimedia instruction set MMX implementation 4 consistency check to remove wrong stereo matching problems suffering from occlusions or mismatches 5 constraints of the recovery space To realize obstacle detection robustly we use the following three steps 1 extracting the ground plane parameters using Randomized Hough Transform 2 filtering the ground and background 3 locating the obstacles by using connected region detection Experimental results show the system can run at 3 2fps in 2 0GHz PC with 640X480 pixels

Cluster observations of surface waves on the dawn flank magnetopause

Directory of Open Access Journals (Sweden)

C. J. Owen

2004-03-01

Full Text Available On 14 June 2001 the four Cluster spacecraft recorded multiple encounters of the dawn-side flank magnetopause. The characteristics of the observed electron populations varied between a cold, dense magnetosheath population and warmer, more rarified boundary layer population on a quasi-periodic basis. The demarcation between these two populations can be readily identified by gradients in the scalar temperature of the electrons. An analysis of the differences in the observed timings of the boundary at each spacecraft indicates that these magnetopause crossings are consistent with a surface wave moving across the flank magnetopause. When compared to the orientation of the magnetopause expected from models, we find that the leading edges of these waves are approximately 45° steeper than the trailing edges, consistent with the Kelvin-Helmholtz (KH driving mechanism. A stability analysis of this interval suggests that the magnetopause is marginally stable to this mechanism during this event. Periods in which the analysis predicts that the magnetopause is unstable correspond to observations of greater wave steepening. Analysis of the pulses suggests that the waves have an average wavelength of approximately 3.4 R_E and move at an average speed of ~65km s^-1 in an anti-sunward and northward direction, despite the spacecraft location somewhat south of the GSE Z=0 plane. This wave propagation direction lies close to perpendicular to the average magnetic field direction in the external magnetosheath, suggesting that these waves may preferentially propagate in the direction that requires no bending of these external field lines

Key words. Magnetospheric physics (magnetospheric configuration and dynamics; MHD waves and unstabilities; solar wind-magnetosphere interactions

What are the anti-particles of KL,S

International Nuclear Information System (INIS)

Mathur, V.S.; Rajeev, S.G.

1991-01-01

The authors study the consequences of an anti-unitary symmetry such as CPT for an unstable quantum system described by a non-self-adjoint Hamiltonian. In this paper it is shown that CPT invariance by itself does not imply that every particle has an anti-particle of equal mass and life-time. In particular, the neutral kaons K L and K S do not have anti-particles even when CPT is conserved

Covariant trace formalism for heavy meson s-wave to p-wave transitions

International Nuclear Information System (INIS)

Balk, S.; Koerner, J.G.; Thompson, G.; Hussain, F.

1992-06-01

Heavy meson, s- to p-wave, weak transitions are studied in the context of the Heavy Quark Effective Theory using covariant meson wave functions. We use the trace formalism to evaluate the weak transitions. As expected from heavy quark symmetry, the eight transitions between s- and p-wave states are described in terms of only two universal form factors which are given in terms of explicit wave function overlap integrals. We present our results in terms of both invariant and helicity amplitudes. Using our helicity amplitude expressions we discuss rate formulae, helicity structure functions and joint angular decay distributions in the decays B-bar→D**(→(D,D*)+π)+W - (→l - ν l ). The heavy quark symmetry predictions for the one-pion transitions D**→(D,D*)+π are similarly worked out by using trace techniques. (author). 35 refs, 3 figs, 2 tabs

Observation of correlated anti-Stokes emissions by multiwave mixing in sodium vapor

International Nuclear Information System (INIS)

Motomura, Koji; Tsukamoto, Mayumi; Wakiyama, Akira; Harada, Ken-ichi; Mitsunaga, Masaharu

2005-01-01

We study experimentally nonlinear optical processes in which Stokes and anti-Stokes fields build up under strong, resonant, counterpropagating pump laser excitation in atomic sodium vapor. We find that, at some pump frequency, two off-axis anti-Stokes emissions propagating along reflection-symmetric directions are strongly temporally correlated, with a correlation time of 0.5 μs and a correlation range of 1 mrad. It is shown by the numerical analysis based on six-wave mixing process involving pump, Stokes, and anti-Stokes waves in the forward and the backward directions that such correlated anti-Stokes emissions are possible when the medium is opaque for the Stokes field and transparent for the anti-Stokes field. Possibilities of quantum correlation for entangled photon generation using this system are discussed

Ab-initio calculation for cation vacancy formation energy in anti-fluorite structure

Science.gov (United States)

Saleel, V. P. Saleel Ahammad; Chitra, D.; Veluraja, K.; Eithiraj, R. D.

2018-04-01

Lithium oxide (Li2O) has been suggested as a suitable breeder blanket material for fusion reactors. Li+ vacancies are created by neutron irradiation, forming bulk defect complex whose extra character is experimentally unclear. We present a theoretical study of Li2O using density functional theory (DFT) with a plane-wave basis set. The generalized gradient approximation (GGA) and local-density approximation (LDA) were used for exchange and correlation. Here we address the total energy for defect free, cation defect, cation vacancy and vacancy formation energy in Li2O crystal in anti-fluorite structure.

Curvature collineations for the field of gravitational waves

International Nuclear Information System (INIS)

Singh, K.P.; Singh, Gulab

1981-01-01

It has been shown that the space-times formed from a plane-fronted gravity wave and from a plane sandwich wave with constant polarisation admit proper curvature collineation in general. The curvature collineation vectors have been determined explicitly. (author)

The Study of Cooperative Obstacle Avoidance Method for MWSN Based on Flocking Control

Directory of Open Access Journals (Sweden)

Zuo Chen

2014-01-01

Full Text Available Compared with the space fixed feature of traditional wireless sensor network (WSN, mobile WSN has better robustness and adaptability in unknown environment, so that it is always applied in the research of target tracking. In order to reach the target, the nodes group should find a self-adaptive method to avoid the obstacles together in their moving directions. Previous methods, which were based on flocking control model, realized the strategy of obstacle avoidance by means of potential field. However, these may sometimes lead the nodes group to fall into a restricted area like a trap and never get out of it. Based on traditional flocking control model, this paper introduced a new cooperative obstacle avoidance model combined with improved SA obstacle avoidance algorithm. It defined the tangent line of the intersection of node’s velocity line and the edge of obstacle as the steering direction. Furthermore, the cooperative obstacle avoidance model was also improved in avoiding complex obstacles. When nodes group encounters mobile obstacles, nodes will predict movement path based on the spatial location and velocity of obstacle. And when nodes group enters concave obstacles, nodes will temporarily ignore the gravity of the target and search path along the edge of the concave obstacles. Simulation results showed that cooperative obstacle avoidance model has significant improvement on average speed and time efficiency in avoiding obstacle compared with the traditional flocking control model. It is more suitable for obstacle avoidance in complex environment.

Scattering of elastic waves by thin inclusions

International Nuclear Information System (INIS)

Simons, D.A.

1980-01-01

A solution is derived for the elastic waves scattered by a thin inclusion. The solution is asymptotically valid as inclusion thickness tends to zero with the other dimensions and the frequency fixed. The method entails first approximating the total field in the inclusion in terms of the incident wave by enforcing the appropriate continuity conditions on traction and displacement across the interface, then using these displacements and strains in the volume integral that gives the scattered field. Expressions are derived for the far-field angular distributions of P and S waves due to an incident plane P wave, and plots are given for normalized differential cross sections of an oblate spheroidal tungsten carbide inclusion in a titanium matrix

Time-domain analytic solutions of two-wire transmission line excited by a plane-wave field

International Nuclear Information System (INIS)

Ni Guyan; Yan Li; Yuan Naichang

2008-01-01

This paper reports that an analytic method is used to calculate the load responses of the two-wire transmission line excited by a plane-wave directly in the time domain. By the frequency-domain Baum–Liu–Tesche (BLT) equation, the time-domain analytic solutions are obtained and expressed in an infinite geometric series. Moreover, it is shown that there exist only finite nonzero terms in the infinite geometric series if the time variate is at a finite interval. In other word, the time-domain analytic solutions are expanded in a finite geometric series indeed if the time variate is at a finite interval. The computed results are subsequently compared with transient responses obtained by using the frequency-domain BLT equation via a fast Fourier transform, and the agreement is excellent. (the physics of elementary particles and fields)

Integrable open spin chain in Super Yang-Mills and the plane-wave/SYM duality

International Nuclear Information System (INIS)

Chen Bin; Wang Xiaojun; Wu Yongshi

2004-01-01

We investigate the integrable structures in an N = 2 superconfomal Sp(N) Yang-Mills theory with matter, which is dual to an open+closed string system. We restrict ourselves to the BMN operators that correspond to free string states. In the closed string sector, an integrable structure is inherited from its parent theory, N = 4 SYM. For the open string sector, the planar one-loop mixing matrix for gauge invariant holomorphic operators is identified with the Hamiltonian of an integrable SU(3) open spin chain. Using the K-matrix formalism we identify the integrable open-chain boundary conditions that correspond to string boundary conditions. The solutions to the algebraic Bethe ansatz equations (ABAE) with a few impurities are shown to recover the anomalous dimensions that exactly match the spectrum of free open string in the plane-wave background. We also discuss the properties of the solutions of ABAE beyond the BMN regime. (author)

BAYESZ, S-Wave, P-Wave Resonance Level Spacing and Strength Functions

International Nuclear Information System (INIS)

Moore, M.S.

1982-01-01

A - Description of problem or function: BAYESZ calculates average s- and p-wave level spacings, strength functions, and average radiation widths of a mixed sequence of s- and p-wave resonances whose parameters are supplied as input. The code is based on two physical assumptions: 1) The neutron reduced width distribution for each open channel is a chi-squared distribution with one degree of freedom, i.e. Porter-Thomas. 2) The spacing distribution follows the Gaussian Orthogonal Ensemble. This property is used, however, only to fix the s- to p-wave level density ratio as proportional to (2J+1) with a spin cut-off correction. B - Method of solution: The method used is an extension of that described by Moore et al. in reference (1), and is based on the method of moments of a truncated Porter-Thomas distribution. C - Restrictions on the complexity of the problem: Parameters for a maximum of 500 individual resonances can be specified. This restriction can be relaxed by increasing array dimensions

P-S & S-P Elastic Wave Conversions from Linear Arrays of Oriented Microcracks

Science.gov (United States)

Jiang, L.; Modiriasari, A.; Bobet, A.; Pyrak-Nolte, L. J.

2017-12-01

Natural and induced processes can produce oriented mechanical discontinuities such as en echelon cracks, fractures and faults. Previous research has shown that compressional to shear (P-S) wave conversions occur at normal incidence to a fracture because of cross-coupling fracture compliances (Nakagawa et al., 2000). Here, experiments and computer simulation are presented to demonstrate the link among cross-coupling stiffness, microcrack orientation and energy partitioning among P, S, and P-S/S-P waves. A FormLabs 2 3D printer was used to fabricate 7 samples (50 mm x 50 mm x 100 mm) with linear arrays of microcracks oriented at 0, 15, 30, 45, 60, 75, and 900 with a print resolution of 0.025 mm. The microcracks were elliptical in cross-sections (2 mm long by 1 mm wide), through the 50 mm thickness of sample, and spaced 3 mm (center-to-center for adjacent cracks). A 25 mm length of each sample contained no microcracks to act as a reference material. Broadband transducers (0.2-1.5 MHz) were used to transmit and receive P and polarized S wave signals that were propagated at normal incidence to the linear array of microcracks. P-wave amplitude increased, while S-wave amplitude remained relatively constant, as the microcrack orientation increased from 0o to 90o. At normal incidence, P-S and S-P wave conversions emerged and increased in amplitude as the crack inclination increased from 00 to 450. From 450 to 900, the amplitude of these converted modes decreased. Between negative and positive crack angles, the P-to-S and S-to-P waves were 1800 phase reversed. The observed energy partitioning matched the computed compliances obtained from numerical simulations with ABAQUS. The cross-coupling compliance for cracks inclined at 450 was found to be the smallest magnitude. 3D printing enabled the study of microstructural effects on macro-scale wave measurements. Information on the orientation of microcracks or even en echelon fractures and faults is contained in P-S conversions

Three Dimensional Sheaf of Ultrasound Planes Reconstruction (SOUPR) of Ablated Volumes

Science.gov (United States)

Ingle, Atul; Varghese, Tomy

2014-01-01

This paper presents an algorithm for three dimensional reconstruction of tumor ablations using ultrasound shear wave imaging with electrode vibration elastography. Radiofrequency ultrasound data frames are acquired over imaging planes that form a subset of a sheaf of planes sharing a common axis of intersection. Shear wave velocity is estimated separately on each imaging plane using a piecewise linear function fitting technique with a fast optimization routine. An interpolation algorithm then computes velocity maps on a fine grid over a set of C-planes that are perpendicular to the axis of the sheaf. A full three dimensional rendering of the ablation can then be created from this stack of C-planes; hence the name “Sheaf Of Ultrasound Planes Reconstruction” or SOUPR. The algorithm is evaluated through numerical simulations and also using data acquired from a tissue mimicking phantom. Reconstruction quality is gauged using contrast and contrast-to-noise ratio measurements and changes in quality from using increasing number of planes in the sheaf are quantified. The highest contrast of 5 dB is seen between the stiffest and softest regions of the phantom. Under certain idealizing assumptions on the true shape of the ablation, good reconstruction quality while maintaining fast processing rate can be obtained with as few as 6 imaging planes suggesting that the method is suited for parsimonious data acquisitions with very few sparsely chosen imaging planes. PMID:24808405

Radiation and propagation of electromagnetic waves

CERN Document Server

Tyras, George; Declaris, Nicholas

1969-01-01

Radiation and Propagation of Electromagnetic Waves serves as a text in electrical engineering or electrophysics. The book discusses the electromagnetic theory; plane electromagnetic waves in homogenous isotropic and anisotropic media; and plane electromagnetic waves in inhomogenous stratified media. The text also describes the spectral representation of elementary electromagnetic sources; the field of a dipole in a stratified medium; and radiation in anisotropic plasma. The properties and the procedures of Green's function method of solution, axial currents, as well as cylindrical boundaries a

Precursor Wave Emission Enhanced by Weibel Instability in Relativistic Shocks

Science.gov (United States)

Iwamoto, Masanori; Amano, Takanobu; Hoshino, Masahiro; Matsumoto, Yosuke

2018-05-01

We investigated the precursor wave emission efficiency in magnetized purely perpendicular relativistic shocks in pair plasmas. We extended our previous study to include the dependence of upstream magnetic field orientations. We performed two-dimensional particle-in-cell simulations and focused on two magnetic field orientations: the magnetic field in the simulation plane (i.e., in-plane configuration) and that perpendicular to the simulation plane (i.e., out-of-plane configuration). Our simulations in the in-plane configuration demonstrated that not only extraordinary but also ordinary mode waves are excited. We quantified the emission efficiency as a function of the magnetization parameter σ e and found that the large-amplitude precursor waves are emitted for a wide range of σ e . We found that especially at low σ e , the magnetic field generated by Weibel instability amplifies the ordinary mode wave power. The amplitude is large enough to perturb the upstream plasma, and transverse density filaments are generated as in the case of the out-of-plane configuration investigated in the previous study. We confirmed that our previous conclusion holds regardless of upstream magnetic field orientations with respect to the two-dimensional simulation plane. We discuss the precursor wave emission in three dimensions and the feasibility of wakefield acceleration in relativistic shocks based on our results.

Pixel-size-maintained image reconstruction of digital holograms on arbitrarily tilted planes by the angular spectrum method.

Science.gov (United States)

Jeong, Seung Jun; Hong, Chung Ki

2008-06-01

We present an effective method for the pixel-size-maintained reconstruction of images on arbitrarily tilted planes in digital holography. The method is based on the plane wave expansion of the diffraction wave fields and the three-axis rotation of the wave vectors. The images on the tilted planes are reconstructed without loss of the frequency contents of the hologram and have the same pixel sizes. Our method shows good results in the extreme cases of large tilting angles and in the region closer than the paraxial case. The effectiveness of the method is demonstrated by both simulation and experiment.

The S-wave resonance contributions in the B{sup 0}{sub s} decays into ψ(2S,3S) plus pion pair

Energy Technology Data Exchange (ETDEWEB)

Rui, Zhou [North China University of Science and Technology, College of Sciences, Tangshan (China); Li, Ya [Nanjing Normal University, Department of Physics and Institute of Theoretical Physics, Nanjing, Jiangsu (China); Wang, Wen-Fei [Shanxi University, Institute of Theoretical Physics, Taiyuan, Shanxi (China)

2017-03-15

The three-body decays B{sup 0}{sub s} → ψ(2S,3S)π{sup +}π{sup -} are studied based on the perturbative QCD approach. With the help of the nonperturbative two-pion distribution amplitudes, the analysis is simplified into the quasi-two-body processes. Besides the traditional factorizable and nonfactorizable diagrams at the leading order, the next-to-leading order vertex corrections are also included to cancel the scale dependence. The f{sub 0}(980), f{sub 0}(1500) resonance contributions as well as the nonresonant contributions are taken into account using the presently known ππ time-like scalar form factor for the s anti s component. It is found that the predicted B{sup 0}{sub s} → ψ(2S)π{sup +}π{sup -} decay spectra in the pion pair invariant mass shows a similar behavior as the experiment. The calculated S-wave contributions to the branching ratio of B{sup 0}{sub s} → ψ(2S)π{sup +}π{sup -} is 6.0 x 10{sup -5}, which is in agreement with the LHCb data B(B{sup 0}{sub s} → ψ(2S)π{sup +}π{sup -}) = (7.2±1.2) x 10{sup -5} within errors. The estimate of B(B{sup 0}{sub s} → ψ(3S)π{sup +}π{sup -}) can reach the order of 10{sup -5}, pending the corresponding measurements. (orig.)

Simulation of in-plane distribution of beam irradiation amount in ion implantation