Finite beta and compressibility effects on stability of resistive modes in toroidal geometry
Energy Technology Data Exchange (ETDEWEB)
Leboeuf, J.-N.G. [Oak Ridge National Lab., TN (United States); Kurita, Gen-ichi
1998-03-01
Linear resistive stability results obtained from the toroidal magnetohydrodynamic codes FAR developed at the Oak Ridge National Laboratory in United States of America and AEOLUS developed at the Japan Atomic Energy Research Institute are compared for carefully constructed benchmark profiles and parameters. These are unstable to a tearing mode with toroidal mode number n=1. The eigenvalues and eigenfunctions calculated with both codes are in close agreement and show that the effect of compressibility is weak for these modes. The effect of finite plasma beta is considered, and the eigenvalues calculated by the FAR and AEOLUS codes also show good agreement. It is shown that the finite beta has a stabilizing effect on the toroidal tearing mode, but that the compressibility also has little effect on finite beta tearing modes. (author)
Numerical {Delta}` studies of the nonlinear finite-{beta} tearing mode
Energy Technology Data Exchange (ETDEWEB)
Pletzer, A. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)
1996-09-01
Tearing modes have recently attracted attention following theoretical successes in predicting the presence of magnetic island with moderate poloidal m = 3,4 and toroidal n = 2,3 mode numbers during TFTR (Tokamak Fusion Test Reactor) supershots. Classical linear resistive mode theory predicts instability when the asymptotic matching index {Delta}` defined as the jump of logarithmic derivative of the radial magnetic perturbation across the rational surface is positive. Recently, it was suggested that tearing modes could also persist when {Delta}`<0 provided bootstrap current effects are taken into account. In all the above theories, the crucial parameter which determines the stability from both the geometry and equilibrium profiles is {Delta}`. It is shown in the present study that the {Delta}` of the (m=2, n=1) mode computed with the PEST-3 code is virtually always positive. Saturation can nevertheless be achieved provided the symmetry breaking term of a current gradient is included in the resistive layer. (author) 3 figs., 11 refs.
Finite-beta effects on the nonlinear evolution of the (m = 1; n = 1) mode in tokamaks
Energy Technology Data Exchange (ETDEWEB)
Holmes, J.A.; Carreras, B.A.; Hicks, H.R.; Lynch, V.E.; Rothe, K.E.
1982-01-01
The stability and evolution of ISX-B-like plasmas are numerically studied using a reduced set of resistive magnetohydrodynamic (MHD) equations. For a sequence of equilibria stable to ideal modes, the n = 1 mode changes from a tearing branch to a pressure-driven branch as ..beta../sup p/ is increased. When this mode is unstable at low beta, it is just the (m = 1;n = 1) tearing mode. Higher n modes also become linearly unstable with increasing ..beta../sub p/; they are essentially pressure driven and have a ballooning character. For low values of beta the instability is best described as a ..beta../sub p/ distortion of the (m = 1;n = 1) tearing mode. This mode drives many other helicities through toroidal and nonlinear couplings. As ..beta../sub p/ is increased, the growth of the m = 1 island slows down in time, going from exponential to linear before reconnection occurs. If ..beta../sub p/ is large enough, the island saturates without reconnection. A broad spectrum of other modes, driven by the (m = 1;n = 1) instability, is produced. These results agree with some observed features of MHD activity in ISX-B.
Localized Acoustic Surface Modes
Farhat, Mohamed
2015-08-04
We introduce the concept of localized acoustic surface modes (ASMs). We demonstrate that they are induced on a two-dimensional cylindrical rigid surface with subwavelength corrugations under excitation by an incident acoustic plane wave. Our results show that the corrugated rigid surface is acoustically equivalent to a cylindrical scatterer with uniform mass density that can be represented using a Drude-like model. This, indeed, suggests that plasmonic-like acoustic materials can be engineered with potential applications in various areas including sensing, imaging, and cloaking.
Electromagnetic gyrokinetic turbulence in finite-beta helical plasmasa)
Ishizawa, A.; Watanabe, T.-H.; Sugama, H.; Maeyama, S.; Nakajima, N.
2014-05-01
A saturation mechanism for microturbulence in a regime of weak zonal flow generation is investigated by means of electromagnetic gyrokinetic simulations. The study identifies a new saturation process of the kinetic ballooning mode (KBM) turbulence originating from the spatial structure of the KBM instabilities in a finite-beta Large Helical Device (LHD) plasma. Specifically, the most unstable KBM in LHD has an inclined mode structure with respect to the mid-plane of a torus, i.e., it has a finite radial wave-number in flux tube coordinates, in contrast to KBMs in tokamaks as well as ion-temperature gradient modes in tokamaks and helical systems. The simulations reveal that the growth of KBMs in LHD is saturated by nonlinear interactions of oppositely inclined convection cells through mutual shearing as well as by the zonal flow. The saturation mechanism is quantitatively investigated by analysis of the nonlinear entropy transfer that shows not only the mutual shearing but also a self-interaction with an elongated mode structure along the magnetic field line.
Localized vibrational modes in diamond
Murzaev, R. T.; Bachurin, D. V.; Korznikova, E. A.; Dmitriev, S. V.
2017-03-01
Discrete breather (DB) or, synonymously, intrinsic localized mode (ILM) is a spatially localized and time-periodic vibrational mode in a defect-free nonlinear lattice, e.g., in a crystal lattice. Standing DB and DB clusters (double and triple) are studied in diamond using molecular dynamics method with the AIREBO interatomic potentials. Single DB can be easily excited by applying initial shifts, A0, to a pair of nearest atoms along the valence bond in the opposite directions. Admissible excitation amplitudes are 0.09 ≤A0 /a0 ≤ 0.12, where a0 is the equilibrium interatomic distance. The core of a DB is a pair of nearest carbon atoms oscillating out-of-phase, while the neighboring atoms oscillate with one order of magnitude lower amplitudes. DB frequency is above the top of the phonon spectrum and increases with the oscillation amplitude. DB lives for more than 100 oscillation periods which approximately corresponds to 2 ps. The range of initial amplitudes and other conditions necessary for the excitation of double and triple DB clusters as well as their lifetime are investigated in detail. Two different mechanisms of energy exchange between DBs in the DB clusters are revealed, which is the main result of the present study. Our results contribute to a deeper understanding of the nonlinear lattice dynamics of diamond.
Reversal of particle flux in collisional-finite beta tokamak discharges
Energy Technology Data Exchange (ETDEWEB)
Ma, J.; Wang, G. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Weiland, J. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Chalmers University of Technology and EURATOM-VR Association, Gothenburg (Sweden); Rafiq, T.; Kritz, A. H. [Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)
2015-01-15
The mixed gradient method [Zhong et al. Phys. Rev. Lett. 111, 265001 (2013)] is adopted and effects of collisions and finite beta are included in the Weiland 9-equation fluid model. The particle flux and particle pinch, obtained using the Weiland anomalous transport fluid model, are compared with Tore Supra experimental results. Particle transport is also studied using predictive simulation data for an experimental advanced superconducting tokamak discharge in which neutral beam heating is utilized. The effects of collisions on particle transport are studied by turning collisions on and off in the Weiland model. It is found that the particle pinch region is related to the mode structure. The particle pinch region coincides with the region where the strong ballooning modes are present due to large gradients. The general properties of the fluid model are examined by finding regions where collisions can enhance the particle pinch.
Finite beta effects on low- and high-frequency magnetosonic waves in a two-ion-species plasma
Energy Technology Data Exchange (ETDEWEB)
Toida, Mieko; Aota, Yukio [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)
2013-08-15
A magnetosonic wave propagating perpendicular to a magnetic field in a two-ion-species plasma has two branches, high-frequency and low-frequency modes. The finite beta effects on these modes are analyzed theoretically on the basis of the three-fluid model with finite ion and electron pressures. First, it is shown that the Korteweg-de Vries (KdV) equation for the low-frequency mode is valid for amplitudes ε<ε{sub max}, where the upper limit of the amplitude ε{sub max} is given as a function of β (β is the ratio of the kinetic and magnetic energy densities), the density ratio, and the cyclotron frequency ratio of two ion species. Next, the linear dispersion relation and KdV equation for the high-frequency mode are derived, including β as a factor. In addition, the theory for heavy ion acceleration by the high-frequency mode pulse and the pulse damping due to this energy transfer in a finite beta plasma are presented.
Electron acceleration by a localized Bernstein mode
Kumar, Asheel
2017-07-01
An analytical framework for electron acceleration by an axially localized large amplitude electron Bernstein mode in a magnetized plasma is developed. The mode is localized due to plasma density profile or magnetic field profile and could be excited by launching an electron cyclotron wave from out side. A mildly pre-accelerated electron beam of finite Larmor radius resonantly interacts with the mode and gains axial energy as well as transverse energy. The scheme is suitable for producing electron beams of energy upto several MeV.
Reynolds stress of localized toroidal modes
Energy Technology Data Exchange (ETDEWEB)
Zhang, Y.Z. [International Center for Theoretical Studies, Trieste (Italy); Mahajan, S.M. [Univ. of Texas, Austin, TX (United States). Institute for Fusion Studies
1995-02-01
An investigation of the 2D toroidal eigenmode problem reveals the possibility of a new consistent 2D structure, the dissipative BM-II mode. In contrast to the conventional ballooning mode, the new mode is poloidally localized at {pi}/2 (or -{pi}/2), and possesses significant radial asymmetry. The radial asymmetry, in turn, allows the dissipative BM-II to generate considerably larger Reynolds stress as compared to the standard slab drift type modes. It is also shown that a wide class of localized dissipative toroidal modes are likely to be of the dissipative BM-II nature, suggesting that at the tokamak edge, the fluctuation generated Reynolds stress (a possible source of poloidal flow) can be significant.
Localized modes in nonlinear binary kagome ribbons
Belicev, P. P.; Gligoric, G.; Radosavljevic, A; Maluckov, A.; Stepic, M.; Vicencio, R. A.; Johansson, Magnus
2015-01-01
The localized mode propagation in binary nonlinear kagome ribbons is investigated with the premise to ensure controlled light propagation through photonic lattice media. Particularity of the linear system characterized by the dispersionless flat band in the spectrum is the opening of new minigaps due to the "binarism." Together with the presence of nonlinearity, this determines the guiding mode types and properties. Nonlinearity destabilizes the staggered rings found to be nondiffracting in t...
Nonlinear magnetohydrodynamics of edge localized mode precursors
Energy Technology Data Exchange (ETDEWEB)
Guo, Z. B., E-mail: guozhipku@gmail.com [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing (China); WCI Center for Fusion Theory, NFRI, Gwahangno 113, Yusung-gu, Daejeon 305-333 (Korea, Republic of); Wang, Lu [SEEE, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Wang, X. G. [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing (China)
2015-02-15
A possible origin of edge-localized-mode (ELM) precursors based on nonlinear ideal peeling-ballooning mode is reported. Via nonlinear variational principle, a nonlinear evolution equation of the radial displacement is derived and solved, analytically. Besides an explosive growth in the initial nonlinear phase, it is found that the local displacement evolves into an oscillating state in the developed nonlinear phase. The nonlinear frequency of the ELM precursors scales as ω{sub pre}∼x{sup 1/3}ξ{sup ^}{sub ψ,in}{sup 2/3}n, with x position in radial direction, ξ{sup ^}{sub ψ,in} strength of initial perturbation, and n toroidal mode number.
Localized modes in nonlinear photonic kagome nanoribbons
Energy Technology Data Exchange (ETDEWEB)
Molina, Mario I., E-mail: mmolina@uchile.cl [Departamento de Física, MSI – Nucleus for Advanced Optics, and Center for Optics and Photonics (CEFOP), Facultad de Ciencias, Universidad de Chile, Santiago (Chile)
2012-10-01
We examine localization of light in nonlinear (Kerr) kagome lattices in the shape of narrow strips of varying width. For the narrowest ribbon, the band structure features a flat band leading to linear dynamical trapping of an initially localized excitation. We also find a geometry-induced bistability of the nonlinear modes as the width of the strip is changed. A crossover from one to two dimensions localization behavior is observed as the width is increased, attaining two-dimensional behavior for relatively narrow ribbons.
Hydrogen local vibrational modes in semiconductors
Energy Technology Data Exchange (ETDEWEB)
McCluskey, Matthew D. [Univ. of California, Berkeley, CA (United States). Dept. of Physics
1997-06-01
Following, a review of experimental techniques, theory, and previous work, the results of local vibrational mode (LVM) spectroscopy on hydrogen-related complexes in several different semiconductors are discussed. Hydrogen is introduced either by annealing in a hydrogen ambient. exposure to a hydrogen plasma, or during growth. The hydrogen passivates donors and acceptors in semiconductors, forming neutral complexes. When deuterium is substituted for hydrogen. the frequency of the LVM decreases by approximately the square root of two. By varying the temperature and pressure of the samples, the microscopic structures of hydrogen-related complexes are determined. For group II acceptor-hydrogen complexes in GaAs, InP, and GaP, hydrogen binds to the host anion in a bond-centered orientation, along the [111] direction, adjacent to the acceptor. The temperature dependent shift of the LVMs are proportional to the lattice thermal energy U(T), a consequence of anharmonic coupling between the LVM and acoustical phonons. In the wide band gap semiconductor ZnSe, epilayers grown by metalorganic chemical vapor phase epitaxy (MOCVD) and doped with As form As-H complexes. The hydrogen assumes a bond-centered orientation, adjacent to a host Zn. In AlSb, the DX centers Se and Te are passivated by hydrogen. The second, third, and fourth harmonics of the wag modes are observed. Although the Se-D complex has only one stretch mode, the Se-H stretch mode splits into three peaks. The anomalous splitting is explained by a new interaction between the stretch LVM and multi-phonon modes of the lattice. As the temperature or pressure is varied, and anti-crossing is observed between LVM and phonon modes.
Localized modes in nonlinear binary kagome ribbons.
Beličev, P P; Gligorić, G; Radosavljević, A; Maluckov, A; Stepić, M; Vicencio, R A; Johansson, M
2015-11-01
The localized mode propagation in binary nonlinear kagome ribbons is investigated with the premise to ensure controlled light propagation through photonic lattice media. Particularity of the linear system characterized by the dispersionless flat band in the spectrum is the opening of new minigaps due to the "binarism." Together with the presence of nonlinearity, this determines the guiding mode types and properties. Nonlinearity destabilizes the staggered rings found to be nondiffracting in the linear system, but can give rise to dynamically stable ringlike solutions of several types: unstaggered rings, low-power staggered rings, hour-glass-like solutions, and vortex rings with high power. The type of solutions, i.e., the energy and angular momentum circulation through the nonlinear lattice, can be controlled by suitable initial excitation of the ribbon. In addition, by controlling the system "binarism" various localized modes can be generated and guided through the system, owing to the opening of the minigaps in the spectrum. All these findings offer diverse technical possibilities, especially with respect to the high-speed optical communications and high-power lasers.
Seismic base isolation by nonlinear mode localization
Energy Technology Data Exchange (ETDEWEB)
Wang, Y. [University of Illinois, Department of Civil and Environmental Engineering, Urbana, IL (United States); Washington University, Department of Civil and Environmental Engineering, St. Louis, MO (United States); McFarland, D.M. [University of Illinois, Department of Aerospace Engineering, Urbana, IL (United States); Vakakis, A.F. [National Technical University of Athens, Division of Mechanics (Greece); Bergman, L.A. [University of Illinois, Department of Mechanical and Industrial Engineering, Urbana, IL (United States)
2005-03-01
In this paper, the performance of a nonlinear base-isolation system, comprised of a nonlinearly sprung subfoundation tuned in a 1:1 internal resonance to a flexible mode of the linear primary structure to be isolated, is examined. The application of nonlinear localization to seismic isolation distinguishes this study from other base-isolation studies in the literature. Under the condition of third-order smooth stiffness nonlinearity, it is shown that a localized nonlinear normal mode (NNM) is induced in the system, which confines energy to the subfoundation and away from the primary or main structure. This is followed by a numerical analysis wherein the smooth nonlinearity is replaced by clearance nonlinearity, and the system is excited by ground motions representing near-field seismic events. The performance of the nonlinear system is compared with that of the corresponding linear system through simulation, and the sensitivity of the isolation system to several design parameters is analyzed. These simulations confirm the existence of the localized NNM, and show that the introduction of simple clearance nonlinearity significantly reduces the seismic energy transmitted to the main structure, resulting in significant attenuation in the response. (orig.)
Localized modes in orientation-disordered uniaxial medium
Energy Technology Data Exchange (ETDEWEB)
Wan Zhenzhu; Han Yanling [School of Mathematics and Physics, China University of Geosciences, Wuhan 430074 (China); Wang Hong, E-mail: wanghong745@sohu.com, E-mail: w_pearl2008@163.com [Center of Information and Laboratory, China University of Geosciences, Wuhan 430074 (China)
2011-02-01
Using a 4x4 transfer matrix method, localized modes in orientation-disordered uniaxial medium have been investigated. We confirm that localized modes origin from the randomness of spatial orientation of optical axes. The misalignment of the optical axe provides the opportunity for a rearrangement of the localized modes. The number of localize mode also closely relative to the spatial orientation of optical axis. Numerical results indicate that it is possible to adjust the localized modes through altering the relative orientation of the optical axes of scatterers. This study is an importance for well understanding of localization of light wave and lasing action in anisotropic random media.
Flexural Mie Resonances: Localized Surface Platonic Modes
Farhat, M; Chen, P Y; Salama, K N; Bagci, H
2016-01-01
Surface plasmons polaritons were thought to exist only in metals near their plasma frequencies. The concept of spoof plasmons extended the realms of plasmonics to domains such as radio frequencies, magnetism, or even acoustic waves. Here, we introduce the concept of localized surface platonic modes (SPMs). We demonstrate that they can be generated on a two-dimensional clamped (or stress-free) cylindrical surface, in a thin elastic plate, with subwavelength corrugations under excitation by an incident flexural plane wave. Our results show that the corrugated rigid surface is elastically equivalent to a cylindrical scatterer with negatively uniform and dispersive flexural rigidity. This, indeed, suggests that plasmonic-like platonic materials can be engineered with potential applications in various areas including earthquake sensing, or elastic imaging and cloaking.
Breyfogle, M.; Marine, T.; Ware, A. S.; Spong, D. A.
2008-11-01
The impact of magnetic geometry on neoclassical flows and viscosities for the Helically Symmetric Experiment (HSX) is investigated using the PENTA code [1,2]. Specifically, two topics are investigated: (1) finite-beta effects and (2) configurational variations. The PENTA code is used to calculate flows in HSX with the vacuum magnetic geometry and with finite-beta magnetic surfaces from the VMEC equilibrium code. This is done for the standard quasi-helically symmetric configuration of HSX, a symmetry-breaking mirror configuration and a hill configuration. The impact of these changes in the magnetic geometry on neoclassical viscosities and flows in HSX will be discussed.[0pt] [1] D. A. Spong, Phys. Plasmas 12, 056114 (2005). [0pt] [2] D. A. Spong, Fusion Sci. Technology 50, 343 (2006).
Intrinsic localized modes and nonlinear impurity modes in curved Fermi-Pasta-Ulam chain
Indian Academy of Sciences (India)
Ranja Sarkar; Bishwajyoti Dey
2008-06-01
We explore the nature of intrinsic localized modes (ILMs) in a curved FermiPasta-Ulam (FPU) chain and the effects of geometry and second-neighbor interaction on the localization and movability properties of such modes. We determine analytically the structure of the localized modes induced by an isotopic light-mass impurity in this chain. We further demonstrate that a nonlinear impurity mode may be treated as a bound state of an ILM with the impurity.
Energy Technology Data Exchange (ETDEWEB)
Kanno, R.; Nakajima, N.; Sugama, H.; Okamoto, M.; Ogawa, Y.
1997-01-01
Effects of finite-{beta} and radial electric fields on the neoclassical transport in the Large Helical Device are investigated with the DKES (Drift Kinetic Equation Solver) code. In the finite-{beta} configuration, even orbits of deeply trapped particles deviate significantly from magnetic flux surfaces. Thus, neoclassical ripple transport coefficients in the finite-{beta} configuration are several times larger than those in the vacuum configuration under the same condition of temperatures and radial electric fields. When the plasma temperature is several keV, a bifurcation of the electric fields appears under the ambipolarity condition, and sufficient large radial electric fields can be generated. As a result, the ExB drift rectifies orbits of particles and improves significantly the transport coefficients in the finite-{beta} configuration. (author)
Cavity quantum electrodynamics with Anderson-localized modes
DEFF Research Database (Denmark)
Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren;
2010-01-01
by a factor of 15 on resonance with the Anderson-localized mode, and 94% of the emitted single photons coupled to the mode. Disordered photonic media thus provide an efficient platform for quantum electrodynamics, offering an approach to inherently disorder-robust quantum information devices....
Localized radio frequency communication using asynchronous transfer mode protocol
Witzke, Edward L.; Robertson, Perry J.; Pierson, Lyndon G.
2007-08-14
A localized wireless communication system for communication between a plurality of circuit boards, and between electronic components on the circuit boards. Transceivers are located on each circuit board and electronic component. The transceivers communicate with one another over spread spectrum radio frequencies. An asynchronous transfer mode protocol controls communication flow with asynchronous transfer mode switches located on the circuit boards.
Spiralling solitons and multipole localized modes in nonlocal nonlinear media
DEFF Research Database (Denmark)
Buccoliero, Daniel; Lopez-Aguayo, Servando; Skupin, Stefan
2007-01-01
We analyze the propagation of rotating multi-soliton localized structures in optical media with spatially nonlocal nonlinearity. We demonstrate that nonlocality stabilizes the azimuthal breakup of rotating dipole as well as multipole localized soliton modes. We compare the results for two differe...... models of nonlocal nonlinearity and suggest that the stabilization mechanism is a generic property of a spatial nonlocal nonlinear response independent of its particular functional form.......We analyze the propagation of rotating multi-soliton localized structures in optical media with spatially nonlocal nonlinearity. We demonstrate that nonlocality stabilizes the azimuthal breakup of rotating dipole as well as multipole localized soliton modes. We compare the results for two different...
Lumped Mass Modeling for Local-Mode-Suppressed Element Connectivity
DEFF Research Database (Denmark)
Joung, Young Soo; Yoon, Gil Ho; Kim, Yoon Young
2005-01-01
for the standard element density method. Local modes are artificial, numerical modes resulting from the intrinsic modeling technique of the topology optimization method. Even with existing local mode controlling techniques, the convergence of the topology optimization of vibrating structures, especially...... experiencing large structural changes, appears to be still poor. In ECP, the nodes of the domain-discretizing elements are connected by zero-length one-dimensional elastic links having varying stiffness. For computational efficiency, every elastic link is now assumed to have two lumped masses at its ends......For successful topology design optimization of crashworthy “continuum” structures, unstable element-free and local vibration mode-free transient analyses should be ensured. Among these two issues, element instability was shown to be overcome if a recently-developed formulation, the element...
Discrete dissipative localized modes in nonlinear magnetic metamaterials.
Rosanov, Nikolay N; Vysotina, Nina V; Shatsev, Anatoly N; Shadrivov, Ilya V; Powell, David A; Kivshar, Yuri S
2011-12-19
We analyze the existence, stability, and propagation of dissipative discrete localized modes in one- and two-dimensional nonlinear lattices composed of weakly coupled split-ring resonators (SRRs) excited by an external electromagnetic field. We employ the near-field interaction approach for describing quasi-static electric and magnetic interaction between the resonators, and demonstrate the crucial importance of the electric coupling, which can completely reverse the sign of the overall interaction between the resonators. We derive the effective nonlinear model and analyze the properties of nonlinear localized modes excited in one-and two-dimensional lattices. In particular, we study nonlinear magnetic domain walls (the so-called switching waves) separating two different states of nonlinear magnetization, and reveal the bistable dependence of the domain wall velocity on the external field. Then, we study two-dimensional localized modes in nonlinear lattices of SRRs and demonstrate that larger domains may experience modulational instability and splitting.
Observation of Localized Multi-Spatial-Mode Quadrature Squeezing
Directory of Open Access Journals (Sweden)
C. S. Embrey
2015-07-01
Full Text Available Quantum states of light can improve imaging whenever the image quality and resolution are limited by the quantum noise of the illumination. In the case of a bright illumination, quantum enhancement is obtained for a light field composed of many squeezed transverse modes. A possible realization of such a multi-spatial-mode squeezed state is a field which contains a transverse plane in which the local electric field displays reduced quantum fluctuations at all locations, on any one quadrature. Using a traveling-wave amplifier, we have generated a multi-spatial-mode squeezed state and showed that it exhibits localized quadrature squeezing at any point of its transverse profile, in regions much smaller than its size. We observe 75 independently squeezed regions. The amplification relies on nondegenerate four-wave mixing in a hot vapor and produces a bichromatic squeezed state. The result confirms the potential of this technique for producing illumination suitable for practical quantum imaging.
Cavity quantum electrodynamics with Anderson-localized modes.
Sapienza, Luca; Thyrrestrup, Henri; Stobbe, Søren; Garcia, Pedro David; Smolka, Stephan; Lodahl, Peter
2010-03-12
A major challenge in quantum optics and quantum information technology is to enhance the interaction between single photons and single quantum emitters. This requires highly engineered optical cavities that are inherently sensitive to fabrication imperfections. We have demonstrated a fundamentally different approach in which disorder is used as a resource rather than a nuisance. We generated strongly confined Anderson-localized cavity modes by deliberately adding disorder to photonic crystal waveguides. The emission rate of a semiconductor quantum dot embedded in the waveguide was enhanced by a factor of 15 on resonance with the Anderson-localized mode, and 94% of the emitted single photons coupled to the mode. Disordered photonic media thus provide an efficient platform for quantum electrodynamics, offering an approach to inherently disorder-robust quantum information devices.
Mode localized MEMS transducers with voltage-controlled linear coupling
Manav, M.; Srikantha Phani, A.; Cretu, E.
2017-05-01
Recent studies have demonstrated mode localized resonant micro-electro-mechanical systems (MEMS) sensing devices with orders of magnitude improvement in sensitivity. Avoided crossings or eigenvalue veering is the physical mechanism exploited to achieve the enhancement in sensitivity of devices operating either in vacuum or in air. The mode localized MEMS devices are typically designed to be symmetric and use gap-varying electrostatic springs to couple motions of two or more resonators. The role of asymmetry in the design of devices and its influence on sensitivity is not fully understood. Furthermore, gap-varying electrostatic springs suffer from nonlinearities when gap variation between coupling plates becomes large due to mode localization, imposing limitations on the device performance. To address these shortcomings, this contribution has two principal objectives. The first objective is to critically assess the role of asymmetry in the device design and operation. We show, based on energy analysis, that carefully designed asymmetry in devices can lead to even higher sensitivities than reported in the literature. Our second objective is to design and implement linear, tunable, electrostatic springs, using shaped combs, which allow large vibration amplitudes of resonators thereby increasing the signal to noise ratio. We experimentally demonstrate linear electrostatic coupling in a two oscillator device. Our study suggests that a future avenue for progress in the mode localized resonant sensing technology is to combine asymmetric devices with tunable linear coupling designs.
Vertical Transport of Subwavelength Localized Surface Electromagnetic Modes
Gao, Fei; Zhang, Youming; Shi, Xihang; Yang, Zhaoju; Zhang, Baile
2015-01-01
Transport of subwavelength electromagnetic (EM) energy has been achieved through near-field coupling of highly confined surface EM modes supported by plasmonic nanoparticles, in a configuration usually staying on a two-dimensional (2D) substrate. Vertical transport of similar modes along the third dimension, on the other hand, can bring more flexibility in designs of functional photonic devices, but this phenomenon has not been observed in reality. In this paper, designer (or spoof) surface plasmon resonators (plasmonic meta-atoms) are stacked in the direction vertical to their individual planes in demonstrating vertical transport of subwavelength localized surface EM modes. Dispersion relation of this vertical transport is determined from coupled mode theory and is verified with near-field transmission spectrum and field mapping with a microwave near-field scanning stage. This work extends the near-field coupled resonator optical waveguide (CROW) theory into the vertical direction, and may find applications ...
IP over ATM Implementation with Local Switch Mode
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
In classical IPOA, the communication of two users between local Asynchronous Transfer Mode(ATM) ports needs a VCC, however, it is not an elegant solution to the ATM access equipments design when the performance of the whole system is considered. Thus, we investigate the way to provide the improved IPOA protocol that uses switching way in local ports. And it is fully compatible with the CIPOA by using the same protocol for ARP and IP forwarding. In addition, we also present the design of one 10/100 Mbit/s auto adaptive IPOA client board with local switch ability idea and CAM mechanism for our project.
High Confinement Mode and Edge Localized Mode Characteristics in a Near-Unity Aspect Ratio Tokamak.
Thome, K E; Bongard, M W; Barr, J L; Bodner, G M; Burke, M G; Fonck, R J; Kriete, D M; Perry, J M; Schlossberg, D J
2016-04-29
Tokamak experiments at near-unity aspect ratio A≲1.2 offer new insights into the self-organized H-mode plasma confinement regime. In contrast to conventional A∼3 plasmas, the L-H power threshold P_{LH} is ∼15× higher than scaling predictions, and it is insensitive to magnetic topology, consistent with modeling. Edge localized mode (ELM) instabilities shift to lower toroidal mode numbers as A decreases. These ultralow-A operations enable heretofore inaccessible J_{edge}(R,t) measurements through an ELM that show a complex multimodal collapse and the ejection of a current-carrying filament.
Parametric localized modes in quadratic nonlinear photonic structures
DEFF Research Database (Denmark)
Sukhorukov, Andrey A.; Kivshar, Yuri S.; Bang, Ole;
2001-01-01
We analyze two-color spatially localized nonlinear modes formed by parametrically coupled fundamental and second-harmonic fields excited at quadratic (or chi2) nonlinear interfaces embedded in a linear layered structure-a quadratic nonlinear photonic crystal. For a periodic lattice of nonlinear...... interfaces, we derive an effective discrete model for the amplitudes of the fundamental and second-harmonic waves at the interfaces (the so-called discrete chi2 equations) and find, numerically and analytically, the spatially localized solutions-discrete gap solitons. For a single nonlinear interface...... in a linear superlattice, we study the properties of two-color localized modes, and describe both similarities to and differences from quadratic solitons in homogeneous media....
Entanglement Dynamics in Typical Local- and Normal-Mode Molecules
Institute of Scientific and Technical Information of China (English)
HOU Xi-Wen; WAN Ming-Fang; MA Zhong-Qi
2007-01-01
The entanglement dynamics of two stretching vibrations in theoretically typical local- and normal-mode molecules and realistic molecules H2O and SO2 in an algebraic model is studied in terms of the reduced-density linear entropy with initial entangled states taken to be two-mode squeezed vacuum states. It is shown that the behaviour of the entropy in theoretically typical molecules appears to be more regular than that in realistic ones, and that the entropy becomes irregular as the amplitude of two-mode squeezed vacuum states increases. For initial states with a small amplitude, it is demonstrated that the periodicity and the "classical" beat phenomenon of the entropy occur with the beat in theoretically typical molecules being more regular than that in realistic molecules H2O and SO2.
Study of intrinsic localized vibrational modes in micromechanical oscillator arrays.
Sato, M; Hubbard, B E; English, L Q; Sievers, A J; Ilic, B; Czaplewski, D A; Craighead, H G
2003-06-01
Intrinsic localized modes (ILMs) have been observed in micromechanical cantilever arrays, and their creation, locking, interaction, and relaxation dynamics in the presence of a driver have been studied. The micromechanical array is fabricated in a 300 nm thick silicon-nitride film on a silicon substrate, and consists of up to 248 cantilevers of two alternating lengths. To observe the ILMs in this experimental system a line-shaped laser beam is focused on the 1D cantilever array, and the reflected beam is captured with a fast charge coupled device camera. The array is driven near its highest frequency mode with a piezoelectric transducer. Numerical simulations of the nonlinear Klein-Gordon lattice have been carried out to assist with the detailed interpretation of the experimental results. These include pinning and locking of the ILMs when the driver is on, collisions between ILMs, low frequency excitation modes of the locked ILMs and their relaxation behavior after the driver is turned off.
Edge localized mode rotation and the nonlinear dynamics of filaments
Energy Technology Data Exchange (ETDEWEB)
Morales, J. A.; Bécoulet, M.; Garbet, X.; Dif-Pradalier, G.; Huijsmans, G. T. A.; Fil, A.; Nardon, E.; Passeron, C.; Latu, G. [CEA, IRFM, 13108 St. Paul-Lez-Durance (France); Orain, F.; Hoelzl, M. [Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany); Pamela, S. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Cahyna, P. [Institute of Plasma Physics ASCR, Za Slovankou 1782/3, 182 00 Prague 8 (Czech Republic)
2016-04-15
Edge Localized Modes (ELMs) rotating precursors were reported few milliseconds before an ELM crash in several tokamak experiments. Also, the reversal of the filaments rotation at the ELM crash is commonly observed. In this article, we present a mathematical model that reproduces the rotation of the ELM precursors as well as the reversal of the filaments rotation at the ELM crash. Linear ballooning theory is used to establish a formula estimating the rotation velocity of ELM precursors. The linear study together with nonlinear magnetohydrodynamic simulations give an explanation to the rotations observed experimentally. Unstable ballooning modes, localized at the pedestal, grow and rotate in the electron diamagnetic direction in the laboratory reference frame. Approaching the ELM crash, this rotation decreases corresponding to the moment when the magnetic reconnection occurs. During the highly nonlinear ELM crash, the ELM filaments are cut from the main plasma due to the strong sheared mean flow that is nonlinearly generated via the Maxwell stress tensor.
Edge localized mode rotation and the nonlinear dynamics of filaments
Morales, J. A.; Bécoulet, M.; Garbet, X.; Orain, F.; Dif-Pradalier, G.; Hoelzl, M.; Pamela, S.; Huijsmans, G. T. A.; Cahyna, P.; Fil, A.; Nardon, E.; Passeron, C.; Latu, G.
2016-04-01
Edge Localized Modes (ELMs) rotating precursors were reported few milliseconds before an ELM crash in several tokamak experiments. Also, the reversal of the filaments rotation at the ELM crash is commonly observed. In this article, we present a mathematical model that reproduces the rotation of the ELM precursors as well as the reversal of the filaments rotation at the ELM crash. Linear ballooning theory is used to establish a formula estimating the rotation velocity of ELM precursors. The linear study together with nonlinear magnetohydrodynamic simulations give an explanation to the rotations observed experimentally. Unstable ballooning modes, localized at the pedestal, grow and rotate in the electron diamagnetic direction in the laboratory reference frame. Approaching the ELM crash, this rotation decreases corresponding to the moment when the magnetic reconnection occurs. During the highly nonlinear ELM crash, the ELM filaments are cut from the main plasma due to the strong sheared mean flow that is nonlinearly generated via the Maxwell stress tensor.
Driven intrinsic localized modes in a coupled pendulum array
Energy Technology Data Exchange (ETDEWEB)
Thakur, R Basu [Department of Physics and Astronomy, Dickinson College, Carlisle, PA 17013 (United States); English, L Q [Department of Physics and Astronomy, Dickinson College, Carlisle, PA 17013 (United States); Sievers, A J [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853 (United States)
2008-01-07
Intrinsic localized modes (ILMs), also called discrete breathers, are directly generated via modulational instability in an array of coupled pendulums. These ILMs can be stabilized over a range of driver frequencies and amplitudes. They are characterized by a {pi}-phase difference between their centre and wings. At higher driver frequencies, these ILMs are observed to disintegrate via a pulsating instability, and the mechanism of this breather instability is investigated.
Nonlinear simulations of particle source effects on edge localized mode
Energy Technology Data Exchange (ETDEWEB)
Huang, J.; Tang, C. J. [College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Chen, S. Y., E-mail: sychen531@163.com [College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Southwestern Institute of Physics, Chengdu 610041 (China); Wang, Z. H. [Southwestern Institute of Physics, Chengdu 610041 (China)
2015-12-15
The effects of particle source (PS) with different intensities and located positions on Edge Localized Mode (ELM) are systematically studied with BOUT++ code. The results show the ELM size strongly decreases with increasing the PS intensity once the PS is located in the middle or bottom of the pedestal. The effects of PS on ELM depend on the located position of PS. When it is located at the top of the pedestal, peeling-ballooning (P-B) modes can extract more free energy from the pressure gradient and grow up to be a large filament at the initial crash phase and the broadening of mode spectrum can be suppressed by PS, which leads to more energy loss. When it is located in the middle or bottom of the pedestal, the extraction of free energy by P-B modes can be suppressed, and a small filament is generated. During the turbulence transport phase, the broader mode spectrum suppresses the turbulence transport when PS is located in the middle, while the zonal flow plays an important role in damping the turbulence transport when PS is located at the bottom.
Edge-localized mode avoidance and pedestal structure in I-mode plasmas
Energy Technology Data Exchange (ETDEWEB)
Walk, J. R., E-mail: jrwalk@psfc.mit.edu; Hughes, J. W.; Hubbard, A. E.; Terry, J. L.; Whyte, D. G.; White, A. E.; Baek, S. G.; Reinke, M. L.; Theiler, C.; Churchill, R. M.; Rice, J. E. [MIT Plasma Science and Fusion Center, Cambridge, MA 02139-4307 (United States); Snyder, P. B.; Osborne, T. [General Atomics, San Diego, CA 92186-5608 (United States); Dominguez, A [Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451 (United States); Cziegler, I. [UCSD Center for Momentum Transport and Flow Organization, La Jolla, CA 92093-0417 (United States)
2014-05-15
I-mode is a high-performance tokamak regime characterized by the formation of a temperature pedestal and enhanced energy confinement, without an accompanying density pedestal or drop in particle and impurity transport. I-mode operation appears to have naturally occurring suppression of large Edge-Localized Modes (ELMs) in addition to its highly favorable scalings of pedestal structure and overall performance. Extensive study of the ELMy H-mode has led to the development of the EPED model, which utilizes calculations of coupled peeling-ballooning MHD modes and kinetic-ballooning mode (KBM) stability limits to predict the pedestal structure preceding an ELM crash. We apply similar tools to the structure and ELM stability of I-mode pedestals. Analysis of I-mode discharges prepared with high-resolution pedestal data from the most recent C-Mod campaign reveals favorable pedestal scalings for extrapolation to large machines—pedestal temperature scales strongly with power per particle P{sub net}/n{sup ¯}{sub e}, and likewise pedestal pressure scales as the net heating power (consistent with weak degradation of confinement with heating power). Matched discharges in current, field, and shaping demonstrate the decoupling of energy and particle transport in I-mode, increasing fueling to span nearly a factor of two in density while maintaining matched temperature pedestals with consistent levels of P{sub net}/n{sup ¯}{sub e}. This is consistent with targets for increased performance in I-mode, elevating pedestal β{sub p} and global performance with matched increases in density and heating power. MHD calculations using the ELITE code indicate that I-mode pedestals are strongly stable to edge peeling-ballooning instabilities. Likewise, numerical modeling of the KBM turbulence onset, as well as scalings of the pedestal width with poloidal beta, indicates that I-mode pedestals are not limited by KBM turbulence—both features identified with the trigger for large ELMs
Excitation of localized modes and mechanism of random lasing forming in random media
Institute of Scientific and Technical Information of China (English)
WANG Hong; LIU Jinsong; WANG Kejia; HAN Yanling
2006-01-01
Laser phenomena in random media have been studied based on the localized theory for lightwave in random media. The relationship between random lasing modes and localized modes has been investigated by directly solving Maxwell equations numerically via the finite difference time domain method. The spatial distribution and the spectra of localized modes are obtained for both passive and active random media. The results show that random lasing modes directly originate from the localized modes inside the random medium. In the presence of gain, any one of the localized modes can be amplified and can serve as random lasing mode.
Mechanism of Edge Localized Mode Mitigation by Resonant Magnetic Perturbations
Bécoulet, M.; Orain, F.; Huijsmans, G. T. A.; Pamela, S.; Cahyna, P.; Hoelzl, M.; Garbet, X.; Franck, E.; Sonnendrücker, E.; Dif-Pradalier, G.; Passeron, C.; Latu, G.; Morales, J.; Nardon, E.; Fil, A.; Nkonga, B.; Ratnani, A.; Grandgirard, V.
2014-09-01
A possible mechanism of edge localized modes (ELMs) mitigation by resonant magnetic perturbations (RMPs) is proposed based on the results of nonlinear resistive magnetohydrodynamic modeling using the jorek code, realistic JET-like plasma parameters and an RMP spectrum of JET error-field correction coils (EFCC) with a main toroidal number n =2 were used in the simulations. Without RMPs, a large ELM relaxation is obtained mainly due to the most unstable medium-n ballooning mode. The externally imposed RMP drives nonlinearly the modes coupled to n =2 RMP which produce small multimode relaxations, mitigated ELMs. The modes driven by RMPs exhibit a tearinglike structure and produce additional islands. Mitigated ELMs deposit energy into the divertor mainly in the structures ("footprints") created by n =2 RMPs, however, slightly modulated by other nonlinearly driven even harmonics. The divertor power flux during a ELM phase mitigated by RMPs is reduced almost by a factor of 10. The mechanism of ELM mitigation by RMPs proposed here reproduces generic features of high collisionality RMP experiments, where large ELMs are replaced by small, much more frequent ELMs or magnetic turbulence. Total ELM suppression was also demonstrated in modeling at higher RMP amplitude.
Localized modes in optics of photonic liquid crystals with local anisotropy of absorption
Belyakov, V. A.; Semenov, S. V.
2016-05-01
The localized optical modes in spiral photonic liquid crystals are theoretically studied for the certainty at the example of chiral liquid crystals (CLCs) for the case of CLC with an anisotropic local absorption. The model adopted here (absence of dielectric interfaces in the structures under investigation) makes it possible to get rid of mixing of polarizations on the surfaces of the CLC layer and of the defect structure and to reduce the corresponding equations to only the equations for light with polarization diffracting in the CLC. The dispersion equations determining connection of the edge mode (EM) and defect mode (DM) frequencies with the CLC layer parameters (anisotropy of local absorption, CLC order parameter) and other parameters of the DMS are obtained. Analytic expressions for the transmission and reflection coefficients of CLC layer and DMS for the case of CLC with an anisotropic local absorption are presented and analyzed. It is shown that the CLC layers with locally anisotropic absorption reduce the EM and DM lifetimes (and increase the lasing threshold) in the way different from the case of CLC with an isotropic local absorption. Due to the Borrmann effect revealing of which is different at the opposite stop-band edges in the case of CLC layers with an anisotropic local absorption the EM life-times for the EM frequencies at the opposite stop-bands edges may be significantly different. The options of experimental observations of the theoretically revealed phenomena are briefly discussed.
Edge localized modes of cold neutrons in periodic condensed media
Belyakov, V. A.
2017-06-01
It is found that for certain energies of discreet cold neutrons, quasi-stationary eigen solutions of the corresponding Schrodinger equation, which are localized in the layer of a periodic medium, exist. The localization time of these solutions is strongly dependent on the layer thickness, being finite for a finite layer thickness and increasing indefinitely upon a infinite growth of the layer thickness as the third power of the layer thickness. The problem has been solved in the two-wave approximation of the dynamic diffraction theory for the neutron propagation direction coinciding with the periodicity axes (normal incidence of the neutron beam on the layer). The expressions for neutron eigenwave functions in a periodic medium, the reflection and transmission coefficients, and the neutron wavefunction in the layer as a function of the neutron energy incident on the layer have been determined. It turns out that for the certain discrete neutron energies, the amplitudes of the neutron wavefunction in the layer reach sharp maxima. The corresponding energies are just outside of the neutron stop band (energies forbidden for neutron propagation in the layer) and determine the energies of neutron edge modes (NEMs) localized in the layer, which are direct analogs of the optical edge modes for photonic crystals. The dispersion equation for the localized neutron edge modes has been obtained and analytically solved for the case of thick layers. A rough estimate for the localization length L is L ( db N)-1, where b is the neutron scattering length, d is the crystal period, and N is the density of nuclei in the crystal. The estimates of the localized thermal neutron lifetime show that acheaving of a lifetime close to the free neutron lifetime seems nonrealistic due to absorption of thermal neutrons and requires a perfect large size crystal. Nevertheless, acheaving the localized neutron lifetime exceeding by 104 times the neutron time of flight through the layer appears as
Theoretic base of Edge Local Mode triggering by vertical displacements
Energy Technology Data Exchange (ETDEWEB)
Wang, Z. T. [Southwestern Institute of Physics, Chengdu 610041 (China); College of Physics Science and Technology, Sichuan University, Chengdu 610065 (China); He, Z. X.; Wang, Z. H. [Southwestern Institute of Physics, Chengdu 610041 (China); Wu, N.; Tang, C. J. [College of Physics Science and Technology, Sichuan University, Chengdu 610065 (China)
2015-05-15
Vertical instability is studied with R-dependent displacement. For Solovev's configuration, the stability boundary of the vertical instability is calculated. The pressure gradient is a destabilizing factor which is contrary to Rebhan's result. Equilibrium parallel current density, j{sub //}, at plasma boundary is a drive of the vertical instability similar to Peeling-ballooning modes; however, the vertical instability cannot be stabilized by the magnetic shear which tends towards infinity near the separatrix. The induced current observed in the Edge Local Mode (ELM) triggering experiment by vertical modulation is derived. The theory provides some theoretic explanation for the mitigation of type-I ELMS on ASDEX Upgrade. The principle could be also used for ITER.
Parametric resonance of intrinsic localized modes in coupled cantilever arrays
Kimura, Masayuki; Matsushita, Yasuo; Hikihara, Takashi
2016-08-01
In this study, the parametric resonances of pinned intrinsic localized modes (ILMs) were investigated by computing the unstable regions in parameter space consisting of parametric excitation amplitude and frequency. In the unstable regions, the pinned ILMs were observed to lose stability and begin to fluctuate. A nonlinear Klein-Gordon, Fermi-Pasta-Ulam-like, and mixed lattices were investigated. The pinned ILMs, particularly in the mixed lattice, were destabilized by parametric resonances, which were determined by comparing the shapes of the unstable regions with those in the Mathieu differential equation. In addition, traveling ILMs could be generated by parametric excitation.
Localized surface plate modes via flexural Mie resonances
Farhat, M.
2017-05-11
Surface-plasmon polaritons are naturally generated upon excitation of metals with high-frequency electromagnetic waves. However, the concept of spoof plasmons has made it possible to generate plasmoniclike effects in microwave electrodynamics, magnetics, and even acoustics. Similarly, in this paper, the concept of localized surface plate modes (SPMs) is introduced. It is demonstrated that SPMs can be generated on a two-dimensional (clamped or stress-free) cylindrical surface with subwavelength corrugations, which resides on a thin elastic plate, under excitation by an incident flexural plane wave. Numerical characterization of this corrugated rigid structure shows that it is elastically equivalent to a cylindrical scatterer with dispersive but uniformly negative flexural rigidity. This, indeed, suggests that plasmoniclike elastic materials can be engineered with potential applications in various areas including earthquake sensing and elastic imaging and cloaking.
Mode localization in the cooperative dynamics of protein recognition
Copperman, J.; Guenza, M. G.
2016-07-01
The biological function of proteins is encoded in their structure and expressed through the mediation of their dynamics. This paper presents a study on the correlation between local fluctuations, binding, and biological function for two sample proteins, starting from the Langevin Equation for Protein Dynamics (LE4PD). The LE4PD is a microscopic and residue-specific coarse-grained approach to protein dynamics, which starts from the static structural ensemble of a protein and predicts the dynamics analytically. It has been shown to be accurate in its prediction of NMR relaxation experiments and Debye-Waller factors. The LE4PD is solved in a set of diffusive modes which span a vast range of time scales of the protein dynamics, and provides a detailed picture of the mode-dependent localization of the fluctuation as a function of the primary structure of the protein. To investigate the dynamics of protein complexes, the theory is implemented here to treat the coarse-grained dynamics of interacting macromolecules. As an example, calculations of the dynamics of monomeric and dimerized HIV protease and the free Insulin Growth Factor II Receptor (IGF2R) domain 11 and its IGF2R:IGF2 complex are presented. Either simulation-derived or experimentally measured NMR conformers are used as input structural ensembles to the theory. The picture that emerges suggests a dynamical heterogeneous protein where biologically active regions provide energetically comparable conformational states that are trapped by a reacting partner in agreement with the conformation-selection mechanism of binding.
The non-linear evolution of edge localized modes
Energy Technology Data Exchange (ETDEWEB)
Wenninger, Ronald
2013-01-09
Edge localized modes (ELMs) are instabilities in the edge of tokamak plasmas in the high confinement regime (H-mode). Without them the edge transport in ordinary H-mode plasmas is too low to establish a stationary situation. However in a future device large unmitigated ELMs are believed to cause divertor power flux densities far in excess of tolerable material limits. Hence the size of energy loss per ELM and the resulting ELM frequency must be controlled. To proceed in understanding how the ELM size is determined and how ELM mitigation methods work it is necessary to characterize the non-linear evolution of pedestal erosion. In order to achieve this experimental data is compared to the results of ELM simulations with the code JOREK (reduced MHD, non-linear) applying a specially developed synthetic magnetic diagnostic. The experimental data are acquired by several fast sampling diagnostics at the experiments ASDEX Upgrade and TCV at a large number of toroidal/poloidal positions. A central element of the presented work is the detailed characterization of dominant magnetic perturbations during ELMs. These footprints of the instability can be observed most intensely in close temporal vicinity to the onset of pedestal erosion. Dominant magnetic perturbations are caused by current perturbations located at or inside the last closed flux surface. In ASDEX Upgrade under certain conditions dominant magnetic perturbations like other H-mode edge instabilities display a similarity to solitons. Furthermore - as expected - they are often observed to be correlated to a perturbation of electron temperature. In TCV it is possible to characterize the evolution of the toroidal structure of dominant magnetic perturbations. Between growing above the level of background fluctuations and the maximum perturbation level for all time instance a similar toroidal structure is observed. This rigid mode-structure is an indication for non-linear coupling. Most frequently the dominant toroidal
Intrinsic Localized Modes in Optical Photonic Lattices and Arrays
Christodoulides, Demetrios
Discretizing light behavior requires optical elements that can confine optical energy at distinct sites. One possible scenario in implementing such arrangements is to store energy within low loss high Q-microcavities and then allow photon exchange between such components in time. This scheme requires high-contrast dielectric elements that became available with the advent of photonic crystal technologies. Another possible avenue where such light discretization can be directly observed and studied is that based on evanescently coupled waveguide arrays. As indicated in several studies, discrete systems open up whole new directions in terms of modifying light transport properties. One such example is that of discrete solitons. By nature, discrete solitons represent self-trapped wavepackets in nonlinear periodic structures and result from the interplay between lattice diffraction (or dispersion) and material nonlinearity. In optics, this class of self-localized states has been successfully observed in both one- and two-dimensional nonlinear waveguide arrays. In recent years such photonic lattices have been implemented or induced in a variety of material systems, including those with cubic (Kerr), quadratic, photorefractive, and liquid-crystal nonlinearities. In all cases the underlying periodicity or discreteness can lead to new families of optical solitons that have no counterpart whatsoever in continuous systems. Interestingly, these results paved the way for observations in other physical systems obeying similar evolution equations like Bose-Einstein condensates. New developments in laser writing ultrashort femtosecond laser pulses, now allow the realization of all-optical switching networks in fully 3D environments using nonlinear discrete optics. Using this approach all-optical routing can be achieved using blocking operations. The spatio-temporal evolution of optical pulses in both normally and anomalously dispersive arrays can lead to novel schemes for mode
Impurity-induced local modes in one-dimensional dusty plasma chains
Institute of Scientific and Technical Information of China (English)
Ren Yong-Chao; Wang Xin-Shang; Wang Xiao-Gang
2012-01-01
The effects of impurity on eigenmodes in one-dimensional dusty plasma lattices are studied.It is found that local modes can be excited besides lattice waves,due to the existence of an impurity particle.The dispersion relations of the modes are derived accordingly.Properties of the lattice and local modes are also analyzed and discussed,particularly for their symmetric features and conditions of the mode excitation.
Field-Line Localized Destabilization of Ballooning Modes in Three-Dimensional Tokamaks
Willensdorfer, M.; Cote, T. B.; Hegna, C. C.; Suttrop, W.; Zohm, H.; Dunne, M.; Strumberger, E.; Birkenmeier, G.; Denk, S. S.; Mink, F.; Vanovac, B.; Luhmann, L. C.; ASDEX Upgrade Team
2017-08-01
Field-line localized ballooning modes have been observed at the edge of high confinement mode plasmas in ASDEX Upgrade with rotating 3D perturbations induced by an externally applied n =2 error field and during a moderate level of edge localized mode mitigation. The observed ballooning modes are localized to the field lines which experience one of the two zero crossings of the radial flux surface displacement during one rotation period. The localization of the ballooning modes agrees very well with the localization of the largest growth rates from infinite-n ideal ballooning stability calculations using a realistic 3D ideal magnetohydrodynamic equilibrium. This analysis predicts a lower stability with respect to the axisymmetric case. The primary mechanism for the local lower stability is the 3D distortion of the local magnetic shear.
Nonlinear localized modes in PT-symmetric optical media with competing gain and loss
Energy Technology Data Exchange (ETDEWEB)
Midya, Bikashkali, E-mail: bikash.midya@gmail.com [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700108 (India); Roychoudhury, Rajkumar, E-mail: rroychoudhury123@gmail.com [Advanced Center for Nonlinear and Complex Phenomena, Kolkata 700075 (India)
2014-02-15
The existence and stability of the nonlinear spatial localized modes are investigated in parity-time symmetric optical media characterized by a generic complex hyperbolic refractive index distribution with competing gain and loss profile. The exact analytical expression of the localized modes are found for all values of the competing parameter and in the presence of both the self-focusing and self-defocusing Kerr nonlinearity. The effects of competing gain/loss profile on the stability structure of these localized modes are discussed with the help of linear stability analysis followed by the direct numerical simulation of the governing equation. The spatial localized modes in two-dimensional geometry as well as the transverse power-flow density associated with these localized modes are also examined. -- Highlights: • Existence of localized modes is investigated in PT-symmetric complex potentials. • Exact analytical expression of the localized modes is obtained. • Effect of gain/loss profile on the stability of these localized modes is discussed. • Localized modes in 2D and associated transverse power-flow density are also examined.
Nonlinear localized modes in PT-symmetric Rosen-Morse potential well
Midya, Bikashkali
2013-01-01
We report the existence and properties of localized modes described by nonlinear Schroedinger equation with complex PT-symmetric Rosen-Morse potential well. Exact analytical expressions of the localized modes are found in both one dimensional and two-dimensional geometry with self-focusing and self-defocusing Kerr nonlinearity. Linear stability analysis reveals that these localized modes are unstable for all real values of the potential parameters although corresponding linear Schroedinger eigenvalue problem possesses unbroken PT-symmetry. This result has been verified by the direct numerical simulation of the governing equation. The transverse power flow density associated with these localized modes has also been examined.
Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects
Energy Technology Data Exchange (ETDEWEB)
Pankin, Alexei Y.; Kritz, Arnold H.
2011-07-19
Topics covered are: anomalous transport and E x B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies.
Features of the repetition frequency of edge localized modes in EAST
DEFF Research Database (Denmark)
Jiang, M.; Xiao, C.; Xu, G.S.
2012-01-01
This paper presents the features of the edge localized modes (ELMs) observed in the 2010 experimental campaign on the Experimental Advanced Superconducting Tokamak (EAST). The first high-confinement mode (H-mode) at an H-factor of HIPB98(y, 2)~1 has been obtained with about 1 MW lower hybrid wave...
Assimilation of Mode-S EHS aircraft observations with a local EnKF
Lange, Heiner; Janjic, Tijana
2016-04-01
Aircraft observations of wind and temperature collected by airport surveillance radars (Mode-S EHS) were assimilated in COSMO-KENDA (Kilometre-scale ENsemble Data Assimilation) which couples an Ensemble Kalman Filter to a 40 member ensemble of the convection permitting COSMO-DE (Consortium for Small-Scale Modelling) model. The number of observing aircrafts in Mode-S EHS was about 15 times larger than in the AMDAR system. Between both aircraft observation systems, comparable observation error standard deviations in wind and a larger error in temperature were diagnosed a posteriori using analysis/forecast residuals in observation space (Desrozier's method). With the high density of Mode-S EHS observations, a reduction of temperature and wind error in forecasts of one and three hours was found mainly in the flight level and less near the surface. The amount of Mode-S EHS data was reduced by random thinning to test the effect of a varying observation density. With the current data assimilation setup, a saturation of the forecast error reduction was apparent when more than 50 percent of the Mode-S EHS data were assimilated. Forecast kinetic energy spectra indicated that the reduction in error is related to analysis updates on all scales resolved by COSMO-DE. Evolution (every 15 minutes) of forecast kinetic energy spectra compared to the control experiment showed different behavior of COSMO-DE model depending on amount of data assimilated.
Henry, Bryan R.; Gough, Kathleen M.
1983-01-01
The theoretical basis for the local mode model is reviewed. The model is applied to gas phase overtone spectra of aromatic molecules to investigate both substituent induced CH bond length changes and conformationally inequivalent hydrogens. The dynamic implications of the local mode model are discussed.
Nonlinear localized modes in PT-symmetric optical media with competing gain and loss
Midya, Bikashkali
2014-01-01
The existence and stability of the nonlinear spatial localized modes are investigated in parity-time symmetric optical media characterized by a generic complex hyperbolic refractive index distribution with competing gain and loss profile. The exact analytical expressions of the localized modes are found for all values of the competing parameter and in the presence of both the self-focusing and self-defocusing Kerr nonlinearity. The effect of competing gain/loss profile on the stability structure of these localized modes are discussed with the help of linear stability analysis followed by the direct numerical simulation of the governing equation. The spatial localized modes in two-dimensional geometry as well as the transverse power-flow density associated with these localized modes are also examined.
Drift-Alfven turbulence of a parallel shearing flow of the finite beta plasma with warm ions
Mikhailenko, V. V.; Mikhailenko, V. S.; Lee, Hae June
2016-09-01
It was predicted [Mikhailenko et al., Phys. Plasmas 23, 020701 (2016)] that two distinct drift-Alfven instabilities may be developed in the parallel shearing flow of finite beta plasmas ( 1 ≫β≫me/mi ) with comparable ion and electron temperatures. The first one is the shear-flow-modified drift-Alfven instability, which develops due to the inverse electron Landau damping and exists in the shearless plasma as well. The second one is the shear-flow-driven drift-Alfven instability, which develops due to the combined effect of the velocity shear and ion Landau damping and is absent in the shearless plasma flows. In the present paper, these drift-Alfven instabilities are examined numerically and analytically by including the electromagnetic response of the ions. The levels of the drift-Alfven turbulence, resulted from the development of both instabilities, are determined from the renormalized nonlinear dispersion equation, which accounts for the nonlinear effect of ion scattering by the electromagnetic turbulence. The renormalized quasilinear equation for the ion distribution function, which accounts for the same nonlinear effect of ion scattering, is derived and employed for the analysis of the ion viscosity and ions heating resulting from the interactions of ions with drift-Alfven turbulence.
DEFF Research Database (Denmark)
Neves, Miguel M.; Sigmund, Ole; Bendsøe, Martin P.
2002-01-01
The problem of determining highly localized buckling modes in perfectly periodic cellular microstructures of infinite extent is addressed. A double scale asymptotic technique is applied to the linearized stability problem for a periodic structure built from linearly elastic microstructures...... to design materials with optimal elastic properties that are less prone to localized instability in the form of local buckling modes at the scale of the micro structure. Copyright (C) 2002 John Wiley Sons, Ltd....
Energy Technology Data Exchange (ETDEWEB)
Garofalo, A. M., E-mail: garofalo@fusion.gat.com; Burrell, K. H.; Meneghini, O.; Osborne, T. H.; Paz-Soldan, C.; Smith, S. P.; Snyder, P. B.; Turnbull, A. D. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Eldon, D.; Grierson, B. A.; Solomon, W. M. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Hanson, J. M. [Columbia University, 2960 Broadway, New York, New York 10027-6900 (United States); Holland, C. [University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States); Huijsmans, G. T. A.; Liu, F.; Loarte, A. [ITER Organization, Route de Vinon sur Verdon, 13067 St Paul Lez Durance (France); Zeng, L. [University of California Los Angeles, P.O. Box 957099, Los Angeles, California 90095-7099 (United States)
2015-05-15
For the first time, DIII-D experiments have achieved stationary quiescent H-mode (QH-mode) operation for many energy confinement times at simultaneous ITER-relevant values of beta, confinement, and safety factor, in an ITER-like shape. QH-mode provides excellent energy confinement, even at very low plasma rotation, while operating without edge localized modes (ELMs) and with strong impurity transport via the benign edge harmonic oscillation (EHO). By tailoring the plasma shape to improve the edge stability, the QH-mode operating space has also been extended to densities exceeding 80% of the Greenwald limit, overcoming the long-standing low-density limit of QH-mode operation. In the theory, the density range over which the plasma encounters the kink-peeling boundary widens as the plasma cross-section shaping is increased, thus increasing the QH-mode density threshold. The DIII-D results are in excellent agreement with these predictions, and nonlinear magnetohydrodynamic analysis of reconstructed QH-mode equilibria shows unstable low n kink-peeling modes growing to a saturated level, consistent with the theoretical picture of the EHO. Furthermore, high density operation in the QH-mode regime has opened a path to a new, previously predicted region of parameter space, named “Super H-mode” because it is characterized by very high pedestals that can be more than a factor of two above the peeling-ballooning stability limit for similar ELMing H-mode discharges at the same density.
High Confinement Mode in the KSTAR Device and Control of Accompanying Edge Localized Mode
Energy Technology Data Exchange (ETDEWEB)
Kim, Jay Hyun; Jeon, Young Mu; Xiao, Weiwen; Yoon, Si Woo; Bae, Young Soon; Ko, Won Ha; Lee, Sang Gon [National Fusion Research Institute, Daejeon (Korea, Republic of); Ahn, Joon Wook [Oak Ridge National Laboratory, Oak Ridge (United States); Yun, Gun Su [Pohang University of Science and Technology, Pohang (Korea, Republic of)
2011-10-15
ELMy high confinement mode (H-mode) discharges have been achieved in the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak with the combined auxiliary heating of neutral beam injection (NBI) and electron cyclotron resonance heating (ECRH) since the 3{sup rd} campaign in 2010. The minimum external heating power required was about 0.9 MW at a line-averaged density higher than 1.4x10{sup 19} m{sup -3} and a toroidal field of 2 T. A clear increase of electron and ion temperatures in the pedestal was observed in the H-mode phase while the core ion temperature did not change notably. The toroidal rotation also increased over all radii in the H-mode phase. The measured ELM frequency was around 30{approx}50 Hz and the drop of the total energy appeared to be less than 5 %. Between large ELM spikes, small/grassy ELMs were also identified when mixed heating of NBI and ECRH was applied. On the basis of the H-mode achievement in the 3{sup rd} campaign, the 4{sup th} campaign experiments were focused on the ELM control by various methods such as resonant magnetic perturbation (RMP), supersonic molecular beam injection (SMBI), vertical jogging of plasma column, and edge current drive. Abrupt burst of stored energy due to ELM is harmful to plasma facing component especially in reactor scale devices like international thermonuclear experimental reactor (ITER). The aforementioned ELM control experiments were supported by advanced diagnostics such as electron cyclotron emission imaging (ECEI) and X-ray imaging crystal spectroscopy (XICS). In the 3{sup rd} campaign, the ECEI observed the evolution of filamentary ELM structures in 2D and the XICS measured the plasma rotation profile enhanced by H-mode. Furthermore, the analyses based on advanced diagnostics are in progress for investigating the underlying physics of edge/pedestal characteristics when applying ELM control methods
New approach to Tolman's electronic parameter based on local vibrational modes.
Kalescky, Robert; Kraka, Elfi; Cremer, Dieter
2014-01-06
Tolman's electronic parameter (TEP) derived from the A1-symmetrical CO stretching frequency of nickel-phosphine-tricarbonyl complexes, R3PNi(CO)3, is brought to a new, improved level by replacing normal with local vibrational frequencies. CO normal vibrational frequencies are always flawed by mode-mode coupling especially with metal-carbon stretching modes, which leads to coupling frequencies as large as 100 cm(-1) and can become even larger when the transition metal and the number of ligands is changed. Local TEP (LTEP) values, being based on local CO stretching force constants rather than normal mode frequencies, no longer suffer from mode coupling and mass effects. For 42 nickel complexes of the type LNi(CO)3, it is shown that LTEP values provide a different ordering of ligand electronic effects as previously suggested by TEP and CEP values. The general applicability of the LTEP concept is demonstrated.
Observation of Locked Intrinsic Localized Vibrational Modes in a Micromechanical Oscillator Array
Sato, Masayuki; Hubbard, B. E.; Sievers, A.J.; Ilic, B.; Czaplewski, D. A.; Craighead, H. G.
2003-01-01
The nonlinear vibrational properties of a periodic micromechanical oscillator array have been measured. For sufficiently large amplitude of the driver, the optic mode of the di-element cantilever array becomes unstable and breaks up into excitations ranging over only a few cells. A driver-induced locking effect is observed to eternalize some of these intrinsic localized modes so that their amplitudes become fixed and the modes become spatially pinned.
Observation of locked intrinsic localized vibrational modes in a micromechanical oscillator array.
Sato, M; Hubbard, B E; Sievers, A J; Ilic, B; Czaplewski, D A; Craighead, H G
2003-01-31
The nonlinear vibrational properties of a periodic micromechanical oscillator array have been measured. For sufficiently large amplitude of the driver, the optic mode of the di-element cantilever array becomes unstable and breaks up into excitations ranging over only a few cells. A driver-induced locking effect is observed to eternalize some of these intrinsic localized modes so that their amplitudes become fixed and the modes become spatially pinned.
Institute of Scientific and Technical Information of China (English)
LI De-Jun; MI Xian-Wu; DENG Ke; TANG Yi
2006-01-01
In the classical lattice theory, solitons and locaLized modes can exist in many one-dimensional nonlinear lattice chains, however, in the quantum lattice theory, whether quantum solitons and localized modes can exist or not in the one-dimensional lattice chains is an interesting problem. By using the number state method and the Hartree approximation combined with the method of multiple scales, we investigate quantum solitons and localized modes in a one-dimensional lattice chain with the nonlinear substrate potential. It is shown that quantum solitons do exist in this nonlinear lattice chain, and at the boundary of the phonon Brillouin zone, quantum solitons become quantum localized modes, phonons are pinned to the lattice of the vicinity at the central position j = j0.
Hui, Xiaonan; Zhang, Weite; Jin, Xiaofeng; Chi, Hao; Zhang, Xianmin
2015-01-01
The topological charge of an electromagnetic vortex beam depends on its wavefront helicity. For mixed vortex beams composed of several different coaxial vortices, the topological charge spectrum can be obtained by Fourier transform. However, the vortex beam is generally divergent and imperfect. It makes it significant to investigate the local topological charges, especially in radio frequency regime. Fourier transform based methods are restrained by the uncertainty principle and cannot achieve high angular resolution and mode resolution simultaneously. In this letter, an analysis method for local topological charges of vortex beams is presented based on the empirical mode decomposition (EMD). From EMD, the intrinsic mode functions (IMFs) can be obtained to construct the bases of the electromagnetic wave, and each local topological charge can be respectively defined. With this method the local value achieves both high resolution of azimuth angle and topological charge, meanwhile the amplitudes of each OAM mode...
MISR Level 1B1 Local Mode Radiance Data V002
National Aeronautics and Space Administration — This is the Local Mode Level 1B1 Product containing the DNs radiometrically scaled to radiances with no geometric resampling (Suggested Usage: The MISR Instrument...
Non-local Lee-Wick modes in the fermionic Myers-Pospelov model
Lopez-Sarrion, Justo
2011-01-01
General solutions and dispersion relations are given explicitly in the Lorentz invariance violating fermionic sector of the Myers and Pospelov theory. We quantize the theory and identify Lee-Wick modes due to the higher time-derivative terms. We analyze the non local character of these modes and discuss the loss of microcausality.
Localized bulk electron heating with ICRF mode conversion in the JET tokamak
DEFF Research Database (Denmark)
Mantsinen, M.J.; Mayoral, M.-L.; Eester, D. Van
2004-01-01
Ion cyclotron resonance frequencies (ICRF) mode conversion has been developed for localized on-axis and off-axis bulk electron heating on the JET tokamak. The fast magnetosonic waves launched from the low-field side ICRF antennas are mode-converted to short-wavelength waves on the high-field side...
Dynamic localization and Bloch oscillations in the spectrum of a frequency mode-locked laser.
Longhi, Stefano
2005-04-01
It is shown that a frequency mode-locked laser with a sinusoidal sweep of modulation frequency around a mode-locking condition represents an ideal optical system for observing in the spectral domain the phenomena of dynamic localization and Bloch oscillations of electrons in an ideal solid placed in an external ac electric field.
DEFF Research Database (Denmark)
Migliucci, P.; Naulin, Volker
2010-01-01
Fast magnetic pickup coils are used in forward modeling to match parameters in a simple edge localized mode (ELM) filament model. This novel method allows us to determine key parameters for the evolution of the ELM filaments, as effective mode number, radial and toroidal velocities, and average...
Molina, Andrew; Smereka, Peter; Zimmerman, Paul M.
2016-03-01
The use of alternate coordinate systems as a means to improve the efficiency and accuracy of anharmonic vibrational structure analysis has seen renewed interest in recent years. While normal modes (which diagonalize the mass-weighted Hessian matrix) are a typical choice, the delocalized nature of this basis makes it less optimal when anharmonicity is in play. When a set of modes is not designed to treat anharmonicity, anharmonic effects will contribute to inter-mode coupling in an uncontrolled fashion. These effects can be mitigated by introducing locality, but this comes at its own cost of potentially large second-order coupling terms. Herein, a method is described which partially localizes vibrations to connect the fully delocalized and fully localized limits. This allows a balance between the treatment of harmonic and anharmonic coupling, which minimizes the error that arises from neglected coupling terms. Partially localized modes are investigated for a range of model systems including a tetramer of hydrogen fluoride, water dimer, ethene, diphenylethane, and stilbene. Generally, partial localization reaches ˜75% of maximal locality while introducing less than ˜30% of the harmonic coupling of the fully localized system. Furthermore, partial localization produces mode pairs that are spatially separated and thus weakly coupled to one another. It is likely that this property can be exploited in the creation of model Hamiltonians that omit the coupling parameters of the distant (and therefore uncoupled) pairs.
Energy Technology Data Exchange (ETDEWEB)
Lee, J.; Yun, G. S., E-mail: gunsu@postech.ac.kr; Lee, J. E.; Kim, M.; Choi, M. J.; Lee, W. [Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Park, H. K. [Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of); Domier, C. W.; Luhmann, N. C. [University of California at Davis, Davis, California 95616 (United States); Sabbagh, S. A.; Park, Y. S. [Columbia University, New York, New York 10027 (United States); Lee, S. G.; Bak, J. G. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of)
2014-06-15
A new and more accurate technique is presented for determining the toroidal mode number n of edge-localized modes (ELMs) using two independent electron cyclotron emission imaging (ECEI) systems in the Korea Superconducting Tokamak Advanced Research (KSTAR) device. The technique involves the measurement of the poloidal spacing between adjacent ELM filaments, and of the pitch angle α{sub *} of filaments at the plasma outboard midplane. Equilibrium reconstruction verifies that α{sub *} is nearly constant and thus well-defined at the midplane edge. Estimates of n obtained using two ECEI systems agree well with n measured by the conventional technique employing an array of Mirnov coils.
Damage localization by statistical evaluation of signal-processed mode shapes
DEFF Research Database (Denmark)
Ulriksen, Martin Dalgaard; Damkilde, Lars
2015-01-01
in the spatial mode shape signals, hereby potentially facilitating damage detection and/or localization. However, by being based on distinguishing damage-induced discontinuities from other signal irregularities, an intrinsic deficiency in these methods is the high sensitivity towards measurement noise....... The present article introduces a damage localization method which, compared to the conventional mode shape-based methods, has greatly enhanced robustness towards measurement noise. The method is based on signal processing of spatial mode shapes by means of continuous wavelet transformation (CWT...
Experiment study of edge localized mode with plasma vertical jogging in HL-2A tokamak
Wu, N.; Chen, S. Y.; Song, X. M.; Mou, M. L.; Huang, J.; Wang, Z. T.; Tang, C. J.; Song, X.; Xia, F.; Jiang, M.; HL-2A Team
2017-09-01
The effect of plasma vertical jogging on edge localized modes (ELMs) is investigated in HL-2A tokamak. During the experiment, plasma jogging with a period of about 75 ms is performed, and the results show that both the ELM amplitude and period decrease when the plasma moves upward, which are qualitatively explained by the simulation based on the theory of peeling-ballooning mode including the resistivity effect. The upward movement of plasma causes a change in pedestal parameters, and then the dominant toroidal mode shifts to a relatively high-n mode with the effects of resistivity and diamagnetic, which lead to smaller ELM amplitudes.
Ulriksen, M. D.; Damkilde, L.
2016-02-01
Contrary to global modal parameters such as eigenfrequencies, mode shapes inherently provide structural information on a local level. Therefore, this particular modal parameter and its derivatives are utilized extensively for damage identification. Typically, more or less advanced mathematical methods are employed to identify damage-induced discontinuities in the spatial mode shape signals, hereby, potentially, facilitating damage detection and/or localization. However, by being based on distinguishing damage-induced discontinuities from other signal irregularities, an intrinsic deficiency in these methods is the high sensitivity towards measurement noise. In the present paper, a damage localization method which, compared to the conventional mode shape-based methods, has greatly enhanced robustness towards measurement noise is proposed. The method is based on signal processing of a spatial mode shape by means of continuous wavelet transformation (CWT) and subsequent application of a generalized discrete Teager-Kaiser energy operator (GDTKEO) to identify damage-induced mode shape discontinuities. In order to evaluate whether the identified discontinuities are in fact damage-induced, outlier analysis is conducted by applying the Mahalanobis metric to major principal scores of the sensor-located bands of the signal-processed mode shape. The method is tested analytically and benchmarked with other mode shape-based damage localization approaches on the basis of a free-vibrating beam and validated experimentally in the context of a residential-sized wind turbine blade subjected to an impulse load.
Mode Localization in the Cooperative Dynamics of Protein Recognition
Copperman, J
2015-01-01
The biological function of proteins is encoded in their structure and expressed through the mediation of their dynamics. Local fluctuations are known to initiate biologically relevant pathways as they cooperatively enhance the dynamics in specific regions in the protein. Those biologically active regions provide energetically-comparable conformational states that can be trapped by a reacting partner. We analyze this mechanism as we calculate the dynamics of monomeric and dimerized HIV protease, and free Insulin Growth Factor II Receptor (IGF2R) domain 11 and its IGF2R:IGF2 complex. We adopt a newly developed coarse-grained model, the Langevin Equation for Protein Dynamics (LE4PD), which predicts dynamical relevant mechanisms with high accuracy. Both simulation-derived and experimental NMR conformers are the input structural ensembles for the LE4PD. The use of the experimental NMR conformers requires minimal computational resources.
Excitations and management of the nonlinear localized gap modes
Indian Academy of Sciences (India)
Bishwajyoti Dey
2015-11-01
We discuss about the theory of nonlinear localized excitations, such as soliton and compactons in the gap of the linear spectrum of the nonlinear systems. We show how the gap originates in the linear spectrum using examples of a few systems, such as nonlinear lattices, Bose–Einstein condensates in optical lattice and systems represented by coupled nonlinear evolution equations. We then analytically show the excitation of solitons and compacton-like solutions in the gap of the linear spectrum of a system of coupled Korteweg–de Vries (KdV) equations with linear and nonlinear dispersions. Finally, we discuss about the theory of Feshbach resonance management and dispersion management of the soliton solutions.
Excitation Thresholds for Nonlinear Localized Modes on Lattices
Weinstein, M I
1999-01-01
Breathers are spatially localized and time periodic solutions of extended Hamiltonian dynamical systems. In this paper we study excitation thresholds for (nonlinearly dynamically stable) ground state breather or standing wave solutions for networks of coupled nonlinear oscillators and wave equations of nonlinear Schrödinger (NLS) type. Excitation thresholds are rigorously characterized by variational methods. The excitation threshold is related to the optimal (best) constant in a class of discr ete interpolation inequalities related to the Hamiltonian energy. We establish a precise connection among $d$, the dimensionality of the lattice, $2\\sigma+1$, the degree of the nonlinearity and the existence of an excitation threshold for discrete nonlinear Schrödinger systems (DNLS). We prove that if $\\sigma\\ge 2/d$, then ground state standing waves exist if and only if the total power is larger than some strictly positive threshold, the context of DNLS. We also discuss upper and lower bounds for excitation threshol...
Nonlinear localized flatband modes with spin-orbit coupling
Gligorić, G; Hadžievski, Lj; Flach, S; Malomed, B
2016-01-01
We report the coexistence and properties of stable compact localized states (CLSs) and discrete solitons (DSs) for nonlinear spinor waves on a flatband network with spin-orbit coupling (SOC). The system can be implemented by means of a binary Bose-Einstein condensate loaded in the corresponding optical lattice. In the linear limit, the SOC opens a minigap between flat and dispersive bands in the system's bandgap structure, and preserves the existence of CLSs at the flatband frequency, simultaneously lowering their symmetry. Adding onsite cubic nonlinearity, the CLSs persist and remain available in an exact analytical form, with frequencies which are smoothly tuned into the minigap. Inside of the minigap, the CLS and DS families are stable in narrow areas adjacent to the FB. Deep inside the semi-infinite gap, both the CLSs and DSs are stable too.
On the benefits of localized modes in anharmonic vibrational calculations for small molecules
Panek, Pawel T
2016-01-01
Anharmonic vibrational calculations can already be computationally demanding for relatively small molecules. The main bottlenecks lie in the construction of the potential energy surface and in the size of the excitation space in the vibrational configuration interaction (VCI) calculations. To address these challanges, we use localized-mode coordinates to construct potential energy surfaces and perform vibrational self-consistent field (L-VSCF) and L-VCI calculations [P. T. Panek, Ch. R. Jacob, ChemPhysChem 15, 3365 (2014)] for all vibrational modes of two prototypical test cases, the ethene and furan molecules. We find that the mutual coupling between modes is reduced when switching from normal-mode coordinates to localized-mode coordinates. When using such localized-mode coordinates, we observe a faster convergence of the $n$-mode expansion of the potential energy surface. This makes it possible to neglect higher-order contributions in the $n$-mode expansion of the potential energy surface or to approximate ...
Modulating toroidal flow stabilization of edge localized modes with plasma density
Cheng, Shikui; Banerjee, Debabrata
2016-01-01
Recent EAST experiments have demonstrated mitigation and suppression of edge localized modes (ELMs) with toroidal rotation flow in higher collisionality regime, suggesting potential roles of plasma density. In this work, the effects of plasma density on the toroidal flow stabilization of the high-$n$ edge localized modes have been extensively studied in linear calculations for a circular-shaped limiter H-mode tokamak, using the extended MHD code NIMROD. In the single MHD model, toroidal flow has a weak stabilizing effects on the high-$n$ modes. Such a stabilization, however, can be significantly enhanced with the increase in plasma density. Furthermore, our calculations show that the enhanced stabilization of high-$n$ modes from toroidal flow with higher edge plasma density persists in the 2-fluid MHD model. These findings may explain the ELM mitigation and suppression by toroidal rotation in higher collisionality regime due to the enhancement of plasma density obtained in recent EAST experiments.
Finite-width effects for the localized edge modes in zigzag graphene nanoribbons
Akbari-Sharbaf, Arash; Cottam, Michael G.
2016-06-01
A matrix formalism is used to derive the analytical Green's functions describing correlations between any two atomic sites on a zigzag (ZZ) graphene nanoribbon, incorporating modified electronic hopping values between edge sites that may be distinct from the hopping between interior sites. An analysis of the poles of our Green's functions shows two distinct types of localized edge modes in the electronic spectrum. The first of these, the "zero" mode, is a topologically induced mode arising from the bipartite honeycomb lattice structure of graphene and is always present along ZZ edges. The second type of localized edge mode is present at edges when the edge-to-bulk hopping ratio deviates significantly from unity. The correlations between edge sites are found to exhibit strikingly different features when mediated by the zero edge mode compared with mediation by the "modified" edge mode. In particular, the zero-mode spectral intensity for correlations between two atomic sites along opposite edges can be comparable in strength with that between two sites on the same edge of a finite-width ribbon, before it eventually tends to zero as the ribbon width tends to infinity. This remarkable behavior shows a strong dependence on the sublattice labels of the sites and is in contrast with properties of the modified hopping edge modes. The explicit form of our analytical expressions for the electronic spectrum enables us to predict the zero-mode properties (including frequency, spatial attenuation, and intensity) when the hopping values along ZZ edges are modified.
Xu, X. Q.; Xia, T. Y.; Yan, N.; Liu, Z. X.; Kong, D. F.; Diallo, A.; Groebner, R. J.; Hubbard, A. E.; Hughes, J. W.
2016-05-01
The high-fidelity BOUT++ two-fluid code suite has demonstrated significant recent progress toward integrated multi-scale simulations of tokamak pedestal, including Edge-Localized-Mode (ELM) dynamics, evolution of ELM cycles, and continuous fluctuations, as observed in experiments. Nonlinear ELM simulations show three stages of an ELM event: (1) a linear growing phase; (2) a fast crash phase; and (3) a slow inward turbulence spreading phase lasting until the core heating flux balances the ELM energy loss and the ELM is terminated. A new coupling/splitting model has been developed to perform simulations of multi-scale ELM dynamics. Simulation tracks five ELM cycles for 10 000 Alfvén times for small ELMs. The temporal evolution of the pedestal pressure is similar to that of experimental measurements for the pedestal pressure profile collapses and recovers to a steep gradient during ELM cycles. To validate BOUT++ simulations against experimental data and develop physics understanding of the fluctuation characteristics for different tokamak operation regimes, both quasi-coherent fluctuations (QCFs) in ELMy H-modes and Weakly Coherent Modes in I-modes have been simulated using three dimensional 6-field 2-fluid electromagnetic model. The H-mode simulation results show that (1) QCFs are localized in the pedestal region having a predominant frequency at f ≃300 -400 kHz and poloidal wavenumber at kθ≃0.7 cm-1 , and propagate in the electron diamagnetic direction in the laboratory frame. The overall signatures of simulation results for QCFs show good agreement with C-Mod and DIII-D measurements. (2) The pedestal profiles giving rise to QCFs are near the marginal instability threshold for ideal peeling-ballooning modes for both C-Mod and DIII-D, while the collisional electromagnetic drift-Alfvén wave appears to be dominant for DIII-D. (3) Particle diffusivity is either smaller than the heat diffusivity for DIII-D or similar to the heat diffusivity for C-Mod. Key I-mode
Localized modes in dissipative lattice media: An overview
He, Yingji; Mihalache, Dumitru
2014-01-01
We overview recent theoretical studies of the dynamics of one- and two-dimensional spatial dissipative solitons in models based on the complex Ginzburg-Landau equations with the cubic-quintic combination of loss and gain terms, which include imaginary, real, or complex spatially periodic potentials. The imaginary potential represents periodic modulation of the local loss and gain. It is shown that the effective gradient force, induced by the inhomogeneous loss distribution, gives rise to three generic propagation scenarios for one-dimensional (1D) dissipative solitons: transverse drift, persistent swing motion, and damped oscillations. When the lattice-average loss/gain value is zero, and the real potential has spatial parity opposite to that of the imaginary component, the respective complex potential is a realization of the parity-time symmetry. Under the action of lattice potentials of the latter type, 1D solitons feature unique motion regimes in the form of transverse drift and persistent swing. In the 2D...
Localized modes in dissipative lattice media: an overview.
He, Yingji; Malomed, Boris A; Mihalache, Dumitru
2014-10-28
We give an overview of recent theoretical studies of the dynamics of one- and two-dimensional spatial dissipative solitons in models based on the complex Ginzburg-Landau equations with the cubic-quintic combination of loss and gain terms, which include imaginary, real or complex spatially periodic potentials. The imaginary potential represents periodic modulation of the local loss and gain. It is shown that the effective gradient force, induced by the inhomogeneous loss distribution, gives rise to three generic propagation scenarios for one-dimensional dissipative solitons: transverse drift, persistent swing motion, and damped oscillations. When the lattice-average loss/gain value is zero, and the real potential has spatial parity opposite to that of the imaginary component, the respective complex potential is a realization of the parity-time symmetry. Under the action of lattice potentials of the latter type, one-dimensional solitons feature motion regimes in the form of the transverse drift and persistent swing. In the two-dimensional geometry, three types of axisymmetric radial lattices are considered, namely those based solely on the refractive-index modulation, or solely on the linear-loss modulation, or on a combination of both. The rotary motion of solitons in such axisymmetric potentials can be effectively controlled by varying the strength of the initial tangential kick. © 2014 The Author(s) Published by the Royal Society. All rights reserved.
Goos-Hänchen shift and localization of optical modes in deformed microcavities.
Unterhinninghofen, Julia; Wiersig, Jan; Hentschel, Martina
2008-07-01
Recently, an interesting phenomenon of spatial localization of optical modes along periodic ray trajectories near avoided resonance crossings has been observed [Wiersig, Phys. Rev. Lett. 97, 253901 (2006)]. For the case of a microdisk cavity with elliptical cross section, we use the Husimi function to analyze this localization in phase space. Moreover, we present a semiclassical explanation of this phenomenon in terms of the Goos-Hänchen shift, which works very well even deep in the wave regime. This semiclassical correction to the ray dynamics modifies the phase-space structure such that modes can localize either on stable islands or along unstable periodic ray trajectories.
Geometrical structure, multifractal spectra and localized optical modes of aperiodic Vogel spirals.
Trevino, Jacob; Liew, Seng Fatt; Noh, Heeso; Cao, Hui; Dal Negro, Luca
2012-01-30
We present a numerical study of the structural properties, photonic density of states and bandedge modes of Vogel spiral arrays of dielectric cylinders in air. Specifically, we systematically investigate different types of Vogel spirals obtained by the modulation of the divergence angle parameter above and below the golden angle value (≈137.507°). We found that these arrays exhibit large fluctuations in the distribution of neighboring particles characterized by multifractal singularity spectra and pair correlation functions that can be tuned between amorphous and random structures. We also show that the rich structural complexity of Vogel spirals results in a multifractal photonic mode density and isotropic bandedge modes with distinctive spatial localization character. Vogel spiral structures offer the opportunity to create novel photonic devices that leverage radially localized and isotropic bandedge modes to enhance light-matter coupling, such as optical sensors, light sources, concentrators, and broadband optical couplers.
Fine structure of type-I edge-localized modes in the steep gradient region.
Kurzan, B; Murmann, H D; Neuhauser, J
2005-09-30
Fast, high resolution multichannel Thomson scattering is used to quantitatively determine plasma perturbations induced by type-I edge-localized modes (ELMs) in the low-field side edge of ASDEX Upgrade H-mode plasmas. 2D snapshots of temperature and density, deduced from the laser light scattered in a vertically elongated, poloidal array of 5 x 10 scattering volumes, are obtained in the hot, steep edge gradient zone, which is difficult to access by other diagnostics. Local maxima and minima with large amplitude are identified during ELMs and even in the precursor phase, both in density and temperature. Interpreting these structures as footprints of approximately field aligned helical modes in accordance with previous experimental and theoretical work, toroidal mode numbers between 8 and 20 are obtained, roughly consistent with corresponding scrape-off layer and divertor measurements.
Isotope effect in normal-to-local transition of acetylene bending modes.
Ma, Jianyi; Xu, Dingguo; Guo, Hua; Tyng, Vivian; Kellman, Michael E
2012-01-07
The normal-to-local transition for the bending modes of acetylene is considered a prelude to its isomerization to vinylidene. Here, such a transition in fully deuterated acetylene is investigated using a full-dimensional quantum model. It is found that the local benders emerge at much lower energies and bending quantum numbers than in the hydrogen isotopomer HCCH. This is accompanied by a transition to a second kind of bending mode called counter-rotator, again at lower energies and quantum numbers than in HCCH. These transitions are also investigated using bifurcation analysis of two empirical spectroscopic fitting Hamiltonians for pure bending modes, which helps to understand the origin of the transitions semiclassically as branchings or bifurcations out of the trans- and cis-normal bend modes when the latter become dynamically unstable. The results of the quantum model and the empirical bifurcation analysis are in very good agreement.
Hahn, Seungsoo
2016-10-01
The Hamiltonian matrix for the first excited vibrational states of a protein can be effectively represented by local vibrational modes constituting amide III, II, I, and A modes to simulate various vibrational spectra. Methods for obtaining the Hamiltonian matrix from ab initio quantum calculation results are discussed, where the methods consist of three steps: selection of local vibrational mode coordinates, calculation of a reduced Hessian matrix, and extraction of the Hamiltonian matrix from the Hessian matrix. We introduce several methods for each step. The methods were assessed based on the density functional theory calculation results of 24 oligopeptides with four different peptide lengths and six different secondary structures. The completeness of a Hamiltonian matrix represented in the reduced local mode space is improved by adopting a specific atom group for each amide mode and reducing the effect of ignored local modes. The calculation results are also compared to previous models using C=O stretching vibration and transition dipole couplings. We found that local electric transition dipole moments of the amide modes are mainly bound on the local peptide planes. Their direction and magnitude are well conserved except amide A modes, which show large variation. Contrary to amide I modes, the vibrational coupling constants of amide III, II, and A modes obtained by analysis of a dipeptide are not transferable to oligopeptides with the same secondary conformation because coupling constants are affected by the surrounding atomic environment.
Data-based matched-mode source localization for a moving source.
Yang, T C
2014-03-01
A data-based matched-mode source localization method is proposed in this paper for a moving source, using mode wavenumbers and depth functions estimated directly from the data, without requiring any environmental acoustic information and assuming any propagation model. The method is in theory free of the environmental mismatch problem because the mode replicas are estimated from the same data used to localize the source. Besides the estimation error due to the approximations made in deriving the data-based algorithms, the method has some inherent drawbacks: (1) It uses a smaller number of modes than theoretically possible because some modes are not resolved in the measurements, and (2) the depth search is limited to the depth covered by the receivers. Using simulated data, it is found that the performance degradation due to the afore-mentioned approximation/limitation is marginal compared with the original matched-mode source localization method. The proposed method has a potential to estimate the source range and depth for real data and be free of the environmental mismatch problem, noting that certain aspects of the (estimation) algorithms have previously been tested against data. The key issues are discussed in this paper.
On a common critical state in localized and diffuse failure modes
Zhu, Huaxiang; Nguyen, Hien N. G.; Nicot, François; Darve, Félix
2016-10-01
Accurately modeling the critical state mechanical behavior of granular material largely relies on a better understanding and characterizing the critical state fabric in different failure modes, i.e. localized and diffuse failure modes. In this paper, a mesoscopic scale is introduced, in which the organization of force-transmission paths (force-chains) and cells encompassed by contacts (meso-loops) can be taken into account. Numerical drained biaxial tests using a discrete element method are performed with different initial void ratios, in order to investigate the critical state fabric on the meso-scale in both localized and diffuse failure modes. According to the displacement and strain fields extracted from tests, the failure mode and failure area of each specimen are determined. Then convergent critical state void ratios are observed in failure area of specimens. Different mechanical features of two kinds of meso-structures (force-chains and meso-loops) are investigated, to clarify whether there exists a convergent meso-structure inside the failure area of granular material, as the signature of critical state. Numerical results support a positive answer. Failure area of both localized and diffuse failure modes therefore exhibits the same fabric in critical state. Hence, these two failure modes prove to be homological with respect to the concept of the critical state.
The model of local mode analysis for structural acoustics of box structures
Ngai, King-Wah
Structure-borne noise is a new noise pollution problem emerging from railway concrete box structures in Hong Kong. Its low frequency noise with intermittent effect can cause considerable nuisance to neighborhoods. The tonal noise peaks in this low frequency range should be one of the important factors in structure-borne noise analysis. In the acoustic field, the deterministic analysis of all the resonant modes of vibration is generally considered as not practical. Many acoustic experts use the statistical energy analysis as the main tool for the noise investigation whereas the application of the experimental modal analysis in the structural acoustic problem is comparatively rare. In the past, most studies mainly focused on the structure-borne noise measurement and analysis. The detail study of the cause of structure-borne noise is lack, especially for the rectangular concrete box structure. In this dissertation, an experimental and analytical approach is adopted to study a typical concrete box model. This thesis aims at confirming the importance of modal analysis in the structure-borne noise study and then at identifying the local vibration modes along the cross-section of box structure. These local modes are responsible for the structure-borne noise radiation. The findings of this study suggest that the web of viaduct cross-section is not as rigid as assumed in the conventional viaduct design and the web face is likely to be more flexible in the vertical displacement of the concrete viaduct. Two types of local vibration modes along the cross-section are identified: the centre mode and the web mode. At the top panel of the viaduct, the centre mode has movement in the middle but not at the edges. The web mode has movement at the edges with the middle fixed. The combined centre and web mode has been found to be important in the structural acoustics of the concrete box structure. In the actual concrete viaduct, the coincidence frequency is especially low (often around
Using a local gyrokinetic code to study global ITG modes in tokamaks
Abdoul, P A; Roach, C M; Wilson, H R
2015-01-01
In this paper the global mode structures of linear ion-temperature-gradient (ITG) modes in tokamak plasmas are obtained by combining results from the local gyrokinetic code GS2 with analytical theory. Local gyrokinetic calculations, using GS2, are performed for a range of radial flux surfaces, ${x}$, and ballooning phase angles, ${p}$, to map out the local complex mode frequency, ${\\Omega_{0}(x,p)=\\omega_{0}(x,p)+i\\gamma_{0}(x,p)}$ for a single toroidal mode number, ${n}$. Taylor expanding ${\\Omega_{0}}$ about ${x=0}$, and employing the Fourier-ballooning representation leads to a second order ODE for the amplitude envelope, ${A\\left(p\\right)}$ , which describes how the local results are combined to form the global mode. We employ the so-called CYCLONE base case for circular Miller equilibrium model. Assuming radially varying profiles of ${a/L_{T}}$ and ${a/L_{n}}$, peaked at ${x=0}$, and with all other equilibrium profiles held constant, ${\\Omega_{0}(x,p)}$ is found to have a stationary point. The reconstruc...
Local modes analysis of a rotating marine ship propeller with higher order harmonic elements
Feng, Chen; Yong, Chen; Hongxing, Hua
2016-09-01
An annular harmonic finite element for the computation of the local modes of a pretwisted ship propeller is developed. The elements take into account both the gyroscopic effect and centrifugal stiffening of the propeller blades. The displacement field is expressed by a truncated Fourier series along the angle and by polynomial shape functions in the radial direction. As an example, the dynamic behaviour, i.e. the nature frequency and local modes, of a ship propeller is studied, and compared with ANSYS, both of which have good consistency.
Localized modes in orientation-disordered one-dimensional media with uniaxial scatterers
Institute of Scientific and Technical Information of China (English)
Yingmao Xie; Zhengdong Liu
2008-01-01
Localized modes in one-dimensional (1D) media with uniaxial scatterers that are assumed to be order in spatial location but disorder in spatial orientation of their optical axis are investigated. Based on the holistic effect model in random laser, I.e., the random laser is due to the interaction of the complex localized modes in active random media with local aperiodic quasi-structure with appropriate pump light, a physical model on this type of random media is found. Its disorder degree is defined by D = no/ne. Then, the typical transmission spectrum through the random media and the light field intensity distribution corresponding to the defect modes in photonic band-gap are calculated numerically by means of the transfer matrix method, and the condition that the localized mode appears is discussed. Results show that the medium disorder plays an important role in determining the lightwave state. The localized state appears when the medium disorder is strong enough, and a new mechanism creating random laser phenomenon is brought forward.
Quantum information processing in localized modes of light within a photonic band-gap material
Vats, N; John, S; Vats, Nipun; Rudolph, Terry; John, Sajeev
1999-01-01
The single photon occupation of a localized field mode within an engineered network of defects in a photonic band-gap (PBG) material is proposed as a unit of quantum information (qubit). Qubit operations are mediated by optically-excited atoms interacting with these localized states of light as the atoms traverse the connected void network of the PBG structure. We describe conditions under which this system can have independent qubits with controllable interactions and very low decoherence, as required for quantum computation.
Local group modes and the dynamics of intramolecular energy transfer across a heavy atom
Lopez, Vicente; Fairen, Victor; Lederman, Steven M.; Marcus, R.A
1986-01-01
The dynamics of energy transfer is discussed for a model system in which two ligands are separated by a heavy atom. Numerical and analytical results are given for the case that each ligand is a CC. In the quasiperiodic regime, the dynamics are interpreted using perturbation theory. Local group modes involved in an intramolecular energy localization which can occur in this regime are identified. An approximate separation of the primarily ligand–ligand motions from the primarily ligand–metal–li...
Intrinsic localized modes of a classical discrete anisotropic Heisenberg ferromagnetic spin chain
Energy Technology Data Exchange (ETDEWEB)
Lakshmanan, M., E-mail: lakshman@cnld.bdu.ac.in [Centre for Nonlinear Dynamics, Department of Physics, Bharathidasan University, Tiruchirapalli 620 024 (India); Subash, B. [Centre for Nonlinear Dynamics, Department of Physics, Bharathidasan University, Tiruchirapalli 620 024 (India); Saxena, Avadh [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2014-03-01
We report several exact intrinsic localized mode solutions of the classical spin evolution equation of a one-dimensional anisotropic Heisenberg ferromagnetic spin chain in terms of Jacobian elliptic functions. These include one, two and three spin excitations. All these solutions have smooth anticontinuum limits. Their linear stability and semiclassical quantization are also discussed briefly.
Local probing of Bloch mode dispersion in a photonic crystal waveguide
Engelen, R.J.P.; Engelen, Rob J.P.; Karle, Tim J.; Gersen, H.; Korterik, Jeroen P.; Krauss, Thomas F.; Kuipers, L.; van Hulst, N.F.
2005-01-01
The local dispersion relation of a photonic crystal waveguide is directly determined by phase-sensitive near-field microscopy. We readily demonstrate the propagation of Bloch waves by probing the band diagram also beyond the first Brillouin zone. Both TE and TM polarized modes were distinguished in
Local complementary inputs as drivers of entry mode choices : The case of US investments in Brazil
Hennart, J.M.A.; Sheng, H.H.; Pimenta, G.
2015-01-01
The theory of entry mode choice has modeled that choice as solely determined by the foreign investor. Hennart's bundling model, on the other hand, argues that foreign entry into a host market involves the bundling of intangibles contributed by the foreign investor with local complementary inputs con
All-solid-state cavity QED using Anderson-localized modes in disordered photonic crystal waveguides
DEFF Research Database (Denmark)
Lodahl, Peter; Sapienza, Luca; Nielsen, Henri Thyrrestrup;
2010-01-01
We employ Anderson-localized modes in deliberately disordered photonic crystal waveguides to confine light and enhance the interaction with matter. A 15-fold enhancement of the decay rate of a single quantum dot is observed meaning that 94% of the emitted single photons are coupled to an Anderson...
Local complementary inputs as drivers of entry mode choices : The case of US investments in Brazil
Hennart, J.M.A.; Sheng, H.H.; Pimenta, G.
The theory of entry mode choice has modeled that choice as solely determined by the foreign investor. Hennart's bundling model, on the other hand, argues that foreign entry into a host market involves the bundling of intangibles contributed by the foreign investor with local complementary inputs
A local constitutive model with anisotropy for various homogeneous 2D biaxial deformation modes
Luding, S.; Perdahcioglu, E.S.
2011-01-01
A local constitutive model for granular materials with anisotropy is proposed and applied to different biaxial box deformation modes. The simplified version of the model (in the coordinate system of the biaxial box) involves only scalar values for hydrostatic and shear stresses, for the isotropic an
Mitigating impact of thermal and rectified radio-frequency sheath potentials on edge localized modes
Energy Technology Data Exchange (ETDEWEB)
Gui, B. [Institute of Plasma Physics Chinese Academy of Sciences, Hefei (China); Lawerence Livermore National Lab, Livermore, California 94550 (United States); Xu, X. Q. [Lawerence Livermore National Lab, Livermore, California 94550 (United States); Myra, J. R.; D' Ippolito, D. A. [Lodestar Research Corporation, Boulder, Colorado 80301 (United States)
2014-11-15
The mitigating impact of thermal and rectified radio frequency (RF) sheath potentials on the peeling-ballooning modes is studied non-linearly by employing a two-fluid three-field simulation model based on the BOUT++ framework. Additional shear flow and the Kelvin-Helmholtz effect due to the thermal and rectified RF sheath potential are induced. It is found that the shear flow increases the growth rate while the K-H effect decreases the growth rate slightly when there is a density gradient, but the energy loss of these cases is suppressed in the nonlinear phase. The stronger external electrostatic field due to the sheaths has a more significant effect on the energy loss suppression. From this study, it is found the growth rate in the linear phase mainly determines the onset of edge-localized modes, while the mode spectrum width in the nonlinear phase has an important impact on the turbulent transport. The wider mode spectrum leads to weaker turbulent transport and results in a smaller energy loss. Due to the thermal sheath and rectified RF sheath potential in the scrape-off-layer, the modified shear flow tears apart the peeling-ballooning filament and makes the mode spectrum wider, resulting in less energy loss. The perturbed electric potential and the parallel current near the sheath region is also suppressed locally due to the sheath boundary condition.
Camelin, P; Marconi, M; Giudici, M
2016-01-01
We show that the pumping current is a convenient parameter for manipulating the temporal Localized Structures (LSs), also called localized pulses, found in passively mode-locked Vertical-Cavity Surface-Emitting Lasers. While short electrical pulses can be used for writing and erasing individual LSs, we demonstrate that a current modulation introduces a temporally evolving parameter landscape allowing to control the position and the dynamics of LSs. We show that the localized pulses drifting speed in this landscape depends almost exclusively on the local parameter value instead of depending on the landscape gradient, as shown in quasi-instantaneous media. This experimental observation is theoretically explained by the causal response time of the semiconductor carriers that occurs on an finite timescale and breaks the parity invariance along the cavity, thus leading to a new paradigm for temporal tweezing of localized pulses. Different modulation waveforms are applied for describing exhaustively this paradigm. ...
On the exploitation of mode localization in surface acoustic wave MEMS
Hanley, T. H.; Gallacher, B. J.; Grigg, H. T. D.
2017-05-01
Mode localization sensing has been recently introduced as an alternative resonant sensing protocol. It has been shown to exhibit several advantages over other resonant methods, in particular a potential for higher sensitivity and rejection of common mode noise. This paper expounds the principles of utilising surface acoustic waves (SAW) to create a mode localization sensor. A generalised geometry consisting of a pair of coupled resonant cavities is introduced and an analytical solution found for the displacement fields within the cavities. The solution is achieved by coupling the internal cavity solutions using a ray tracing method. The results of the analytical solution are compared to a numerical solution found using commercial finite element method (FEM) software; exact agreement is found between the two solutions. The insight gained from the analytical model enables the determination of critical design parameters. A brief analysis is presented showing analogous operation to previous examples of mode localization sensors. The sensitivity of the device is shown to depend nonlinearly on the number of periods in the array coupling the two cavities.
Potential energy and vibrational levels for local modes in water and acetylene
Wright, James S.; Donaldson, D. J.
1985-03-01
MRD Cl calculations are given for the potential energy along local X-H streching modes in water and acetylene, out to near dissolution. The Cl data points are accurately fitted by Morse functions up to half the well depth, but generalized (five-parameter) Morse functions are required to fit the whole range of data. The implications for the traetment of vibrational overtone levels are discussed, including a comparison of several treatments. Agreement with experimentally derived mode spectra is good, as is the agreement with bond distances and thermochemistry.
Kirk, A.; Chapman, I. T.; Harrison, J.; Liu, Yueqiang; Nardon, E.; Saarelma, S.; Scannell, R.; Thornton, A. J.; the MAST Team
2013-01-01
The application of resonant magnetic perturbations (RMPs) with a toroidal mode number of n = 4 or n = 6 to lower single null plasmas in the MAST tokamak produces up to a factor of 5 increase in edge-localized mode (ELM) frequency and reduction in plasma energy loss associated with type-I ELMs. A threshold current for ELM mitigation is observed above which the ELM frequency increases approximately linearly with current in the coils. Despite a large scan of parameters, complete ELM suppression has not been achieved. The results have been compared with modelling performed using either the vacuum approximation or including the plasma response. During the ELM mitigated stage clear lobe structures are observed in visible-light imaging of the X-point region. The size of these lobes is correlated with the increase in ELM frequency observed. The characteristics of the mitigated ELMs are similar to those of the natural ELMs suggesting that they are type-I ELMs which are triggered at a lower pressure gradient. The application of the RMPs in the n = 4 and n = 6 configurations before the L-H transition has little effect on the power required to achieve H-mode while still allowing the first ELM to be mitigated.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Pei [Manchester Univ. (United Kingdom); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Baboi, Nicoleta [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Jones, Roger M. [The Cockcroft Institute, Daresbury (United Kingdom)
2012-06-15
An electron beam entering an accelerating cavity excites a wakefield. This wakefield can be decomposed into a series of multi-poles or modes. The dominant component of the transverse wakefield is dipole. This report summarizes the higher order mode (HOM) signals of the third harmonic cavities of FLASH measured at various stages: transmission measurements in the single cavity test stand at Fermilab, at CMTB (Cryo- Module Test Bench) and at FLASH, and beam-excited measurements at FLASH. Modes in the first two dipole bands and the fifth dipole band have been identified using a global Lorentzian fit technique. The beam-pipe modes at approximately 4 GHz and some modes in the fifth dipole band have been observed as localized modes, while the first two dipole bands, containing some strong coupling cavity modes, propagate. This report also presents the dependence of the localized dipole modes on the transverse beam position. Linear dependence for various modes has been observed. This makes them suitable for beam position diagnostics. These modes, together with some propagating, strong coupling modes, have been considered in the design of a dedicated electronics for beam diagnostics with HOMs for the third harmonic cavities.
Zhong, Min; Liu, Shui Jie; Xu, Bang Li; Wang, Jie; Huang, Hua Qing
2017-10-01
In this paper, we design and simulate a metamaterials absorbers based on the resonance of the local surface plasmon (LSP) mode. The damping constant of gold layer is optimized in simulations to eliminate the effect of the inappropriate material parameters on the electromagnetic properties of the proposed metamaterial absorber. The horizontal distance between two metal particles is optimized in simulations and a perfect absorption resonance peak is achieved due to the strong coupling of LSP modes. A new absorption peak is obtained when the horizontal distance is 0 nm. The vertical distance between the new metal particles and the bottom metal layer is reduced, which leads to the absorption peak reduce based on the reduction of the intensity of LSP modes. A new absorption peak is obtained when the new metallic particle and the bottom gold layer form a whole structure.
Effect of localized microstructural evolution on higher harmonic generation of guided wave modes
Choi, Gloria; Liu, Yang; Yao, Xiaochu; Lissenden, Cliff J.
2015-03-01
Higher harmonic generation of ultrasonic waves has the potential to be used to detect precursors to macroscale damage of phenomenon like fatigue due to microstructural evolution contributing to nonlinear material behavior. Aluminum plates having various plastic zone sizes were plastically deformed to different levels. The fundamental shear horizontal mode was then generated in the plate samples via a magnetostrictive transducer. After propagating through the plastic zone the primary wave mode (SH0) and its third harmonic (sh0) were received by a second transducer. Results of a parallel numerical study using the S1-s2 Lamb mode pair, where sensitivity to changes in third order elastic constants were investigated, are described within the context of the experimental results. Specimens used within both studies are geometrically similar and have double edge notches for dog bone samples that introduce localized plastic deformation. Through both studies, the size of the plastic zone with respect to the propagation distance and damage intensity influence the higher harmonics.
Stabilizing effects of resistivity on low-n edge localized modes in NSTX
Banerjee, Debabrata; Maingi, Rajesh
2016-01-01
The stabilizing effects of enhanced edge resistivity on the low-n edge localized modes (ELMs) are reported for the first time in the context of ELM suppression in H-mode discharge due to Lithium-conditioning in the National Spherical Torus Experiment (NSTX). Here n is the toroidal mode number. Linear stability analysis of the corresponding experimental equilibrium suggests that the change in the equilibrium plasma density profile alone due to Lithium-conditioning may be insufficient for a complete suppression of ELMs. The enhanced resistivity due to the increased effective electric charge number Z eff after Lithium-conditioning can account for additional stabi- lization effect necessary for full ELM suppression. Remarkably, such a stabilizing effect of enhanced edge resistivity on the low-n ELMs only exists when two-fluid effects are considered in the MHD model.
A stochastic, local mode study of neon-liquid surface collision dynamics.
Packwood, Daniel M; Phillips, Leon F
2011-01-14
Equations of motion for a fast, light rare gas atom passing over a liquid surface are derived and used to infer the dynamics of neon collisions with squalane and perfluorinated polyether surfaces from experimental data. The equations incorporate the local mode model of a liquid surface via a stochastic process and explicitly account for impulsive collisional energy loss to the surface. The equations predict angular distributions for scattering of neon that are in good quantitative agreement with experimental data. Our key dynamical conclusions are that experimental angular distributions derive mainly from local mode surface topography rather than from structural features of individual surface molecules, and that the available data for these systems can be accounted for almost exclusively by single collisions between neon atoms and the liquid surface.
Nonlinear nano-scale localized breather modes in a discrete weak ferromagnetic spin lattice
Energy Technology Data Exchange (ETDEWEB)
Kavitha, L., E-mail: louiskavitha@yahoo.co.in [Department of Physics, School of Basic and Applied Sciences, Central University of Tamil Nadu (CUTN), Thiruvarur 610 101, Tamil Nadu (India); Max-Planck Institute for the Physics of Complex Systems, Dresden (Germany); The Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Parasuraman, E. [Department of Physics, Periyar University, Salem 636 011, Tamil Nadu (India); Center for Nanoscience and Nanotechnology, Periyar University, Salem 636 011, Tamil Nadu (India); Gopi, D. [Department of Chemistry, Periyar University, Salem 636 011, Tamil Nadu (India); Center for Nanoscience and Nanotechnology, Periyar University, Salem 636 011, Tamil Nadu (India); Prabhu, A. [Department of Physics, Periyar University, Salem 636 011, Tamil Nadu (India); Vicencio, Rodrigo A. [Departamento de Física and MSI-Nucleus on Advanced Optics, Center for Optics and Photonics (CEFOP), Facultad de Ciencias, Universidad de Chile, Santiago 7800003 (Chile); Max-Planck Institute for the Physics of Complex Systems, Dresden (Germany)
2016-03-01
We investigate the propagation dynamics of highly localized discrete breather modes in a weak ferromagnetic spin lattice with on-site easy axis anisotropy due to crystal field effect. We derive the discrete nonlinear equation of motion by employing boson mappings and p-representation. We explore the onset of modulational instability both analytically in the framework of linear stability analysis and numerically by means of molecular dynamics (MD) simulations, and a perfect agreement was demonstrated. It is also explored that how the antisymmetric nature of the canted ferromagnetic lattice supports highly localized discrete breather (DBs) modes as shown in the stability/instability windows. The energy exchange between low amplitude discrete breathers favours the growth of higher amplitude DBs, resulting eventually in the formation of few long-lived high amplitude DBs. - Highlights: • The effects of DM and anisotropy interaction on the DB modes are studied. • The antisymmetric nature of the canted ferromagnetic medium supports the DB modes. • Dynamics of ferromagnetic chain is governed by boson mappings and p-representation.
Spectral gaps and mode localization in Fibonacci chains of metal nanoparticles.
Dal Negro, Luca; Feng, Ning-Ning
2007-10-29
In this paper we study the spectral, localization and dispersion properties of dipolar modes in quasi-periodically modulated nanoparticle chains based on the Fibonacci sequence. By developing a transfer matrix approach for the calculation of resonant frequencies, oscillation eigenvectors and integrated density of states (IDS) of spatially-modulated dipole chains, we demonstrate the presence of large spectral gaps and calculate the pseudo-dispersion diagram of Fibonacci plasmonic chains. The presence of plasmonic band-gaps and localized states in metal nanoparticle chains based on quasi-periodic order can have a large impact in the design and fabrication of novel nanophotonics devices.
Coalescence of Anderson-localized modes at an exceptional point in 2D random media
Bachelard, Nicolas; Arlandis, Julien; Touzani, Rachid; Sebbah, Patrick
2014-01-01
In non-hermitian systems, the particular position at which two eigenstates coalesce under a variation of a parameter in the complex plane is called an exceptional point. A non-perturbative theory is proposed which describes the evolution of modes in 2D open dielectric systems when permittivity distribution is modified. We successfully test this theory in a 2D disordered system to predict the position in the parameter space of the exceptional point between two Anderson-localized states. We observe that the accuracy of the prediction depends on the number of localized states accounted for. Such an exceptional point is experimentally accessible in practically relevant disordered photonic systems
Camelin, P.; Javaloyes, J.; Marconi, M.; Giudici, M.
2016-12-01
We show that the pumping current is a convenient parameter for manipulating the temporal localized structures (LSs), also called localized pulses, found in passively-mode-locked vertical-cavity surface-emitting lasers. While short electrical pulses can be used for writing and erasing individual LSs, we demonstrate that a current modulation introduces a temporally evolving parameter landscape allowing one to control the position and the dynamics of LSs. We show that the localized pulse drifting speed in this landscape depends almost exclusively on the local parameter value instead of depending on the landscape gradient, as shown in quasi-instantaneous media. This experimental observation is theoretically explained by the causal response time of the semiconductor carriers that occurs on a finite time scale and breaks the parity invariance along the cavity, thus leading to a different paradigm for temporal tweezing of localized pulses. Different modulation waveforms are applied for describing exhaustively this paradigm. Starting from a generic model of passive mode locking based upon delay differential equations, we deduce the effective equations of motion for these LSs in a time-dependent current landscape.
Capture and release of traveling intrinsic localized mode in coupled cantilever array
Kimura, Masayuki; Hikihara, Takashi
2009-01-01
A method to manipulate intrinsic localized mode (ILM) is numerically discussed in a nonlinear coupled oscillator array, which is obtained by modeling a microcantilever array. Prior to the manipulation, coexistence and dynamical stability of standing ILMs are first investigated. The stability of coexisting ILMs is determined by a nonlinear coupling coefficient of the array. In addition, the global phase structure, which dominates traveling ILMs, is also changed with the stability. It makes pos...
Localized Mode Enhanced Coupler Based on Quasi-One-Dimensional Photonic Crystal Microstrip
Institute of Scientific and Technical Information of China (English)
LI Yun-Hui; JIANG Hai-Tao; HE Li; LI Hong-Qiang; ZHANG Ye-Wen; CHEN Hong
2004-01-01
We propose a novel localized mode enhanced (LME) coupler based on quasi-one-dimensional photonic crystal microstrips, which is promising to be applied in wavelength division multiplexed microwave communication systems. Compared to the traditional microstrip coupler, the LME structure has two advantages: high efficiency and frequency selectivity. Even in a relatively far coupling distance, this structure can still achieve a high efficiency about 50%. The frequency selectivity can be realized by simply tuning the distance between two transmission lines.
Local phonon mode in thermoelectric Bi{sub 2}Te{sub 2}Se from charge neutral antisites
Energy Technology Data Exchange (ETDEWEB)
Tian, Yao [Department of Physics and Institute of Optical Sciences, University of Toronto, Toronto, Ontario M5S 1A7 (Canada); Osterhoudt, Gavin B.; Burch, Kenneth S., E-mail: ks.burch@bc.edu [Department of Physics, Boston College, 140 Commonwealth Ave., Chestnut Hill, Massachusetts 02467-3804 (United States); Jia, Shuang; Cava, R. J. [Department of Chemistry, Princeton University, Princeton, New Jersey 08540 (United States)
2016-01-25
Local modes caused by defects play a significant role in the thermal transport properties of thermoelectrics. Of particular interest are charge-neutral defects that suppress thermal conductivity, without significantly reducing electrical transport. Here, we report a temperature dependent Raman study that identifies such a mode in a standard thermoelectric material, Bi{sub 2}Te{sub 2}Se. One of the modes observed, whose origin has been debated for decades, was shown most likely to be an antisite defect induced local mode. The anomalous temperature independent broadening of the local mode is ascribed to the random arrangement of Se atoms. The temperature renormalization of all modes is well explained by an anharmonic model–Klemens's model.
Orain, François; Bécoulet, M.; Morales, J.; Huijsmans, G. T. A.; Dif-Pradalier, G.; Hoelzl, M.; Garbet, X.; Pamela, S.; Nardon, E.; Passeron, C.; Latu, G.; Fil, A.; Cahyna, P.
2015-01-01
The dynamics of a multi-edge localized mode (ELM) cycle as well as the ELM mitigation by resonant magnetic perturbations (RMPs) are modeled in realistic tokamak X-point geometry with the non-linear reduced MHD code JOREK. The diamagnetic rotation is found to be a key parameter enabling us to reproduce the cyclical dynamics of the plasma relaxations and to model the near-symmetric ELM power deposition on the inner and outer divertor target plates consistently with experimental measurements. Moreover, the non-linear coupling of the RMPs with unstable modes are found to modify the edge magnetic topology and induce a continuous MHD activity in place of a large ELM crash, resulting in the mitigation of the ELMs. At larger diamagnetic rotation, a bifurcation from unmitigated ELMs—at low RMP current—towards fully suppressed ELMs—at large RMP current—is obtained.
Active control of edge localized modes with a low n perturbation fields in the JET tokamak
Energy Technology Data Exchange (ETDEWEB)
Liang, Y., E-mail: y.liang@fz-juelich.d [Association EURATOM-FZJ, Forschungszentrum Juelich GmbH, Institute of Energy Research IEF-4: Plasma Physics, Partner in the Trilateral Euregio Cluster, 52425 Juelich (Germany); Jachmich, S. [Association EURATOM-Belgian State, Koninklijke Militaire School - Ecole Royale Militaire, B-1000 Brussels (Belgium); Koslowski, H.R. [Association EURATOM-FZJ, Forschungszentrum Juelich GmbH, Institute of Energy Research IEF-4: Plasma Physics, Partner in the Trilateral Euregio Cluster, 52425 Juelich (Germany); Nardon, E. [EURATOM-UKAEA Fusion Association, Culham Science Centre, OX14 3DB Abingdon, OXON (United Kingdom); Alfier, A. [Associazione EURATOM-ENEA sulla Fusione, Consorzio RFX Padova (Italy); Baranov, Y. [EURATOM-UKAEA Fusion Association, Culham Science Centre, OX14 3DB Abingdon, OXON (United Kingdom); De La Luna, E. [Asociacion EURATOM-CIEMAT, Avenida Complutense 22, E-28040 Madrid (Spain); Vries, P. de [EURATOM-UKAEA Fusion Association, Culham Science Centre, OX14 3DB Abingdon, OXON (United Kingdom); Eich, T. [Association EURATOM-Max-Planck-Institut fuer Plasmaphysik, D-85748 Garching (Germany); Esser, H.G.; Harting, D. [Association EURATOM-FZJ, Forschungszentrum Juelich GmbH, Inst. of Energy Research IEF-4: Plasma Physics, Partner in the Trilateral Euregio Cluster, 52425 Juelich (Germany); Kiptily, V. [EURATOM-UKAEA Fusion Association, Culham Science Centre, OX14 3DB Abingdon, OXON (United Kingdom); Kreter, A. [Association EURATOM-FZJ, Forschungszentrum Juelich GmbH, Inst. of Energy Research IEF-4: Plasma Physics, Partner in the Trilateral Euregio Cluster, 52425 Juelich (Germany); Gerasimov, S.; Gryaznevich, M.P.; Howell, D. [EURATOM-UKAEA Fusion Association, Culham Science Centre, OX14 3DB Abingdon, OXON (United Kingdom); Sergienko, G. [Association EURATOM-FZJ, Forschungszentrum Juelich GmbH, Inst. of Energy Research IEF-4: Plasma Physics, Partner in the Trilateral Euregio Cluster, 52425 Juelich (Germany)
2009-06-15
Active control of edge localized modes (ELMs) by using static external magnetic perturbation fields with low toroidal mode number, n, has been demonstrated for both, ITER baseline (q{sub 95}approx3) and high beta advanced tokamak scenarios at the JET tokamak. During the application of the low n field the ELM frequency increased by a factor up to approx4-5. Reduction in carbon erosion and ELM peak heat fluxes on the divertor target by roughly the same factor as the increase of the ELM frequency has been observed. The frequency of the mitigated ELMs using a low n field is found to increase proportional to the total input heating power. Compensation of the density pump-out effect observed when the external low n field is applied has been achieved by gas fueling in low triangularity plasmas.
Pseudospectral calculation of near-dissociative local mode states for the bifluoride anion HF - 2
Bramley, M. J.; Corey, G. C.; Hamilton, I. P.
1995-12-01
Using a recently reported global potential energy surface, we calculate all vibrational levels of the HF-2 anion up to the dissociation threshold. The equilibrium geometry of the bifluoride anion is linear with the H atom between the F atoms. The vibrational wave functions are symmetric or antisymmetric with respect to reflection in a plane bisecting the F-F axis. We focus on nearly degenerate pairs of symmetric and antisymmetric levels lying close to the dissociation energy. Sums and differences of these levels are local mode states for which the H atom is localized on one of the F atoms. These near-dissociative local mode states, which can exist above the threshold for dissociation into F- and HF or FH and F- fragments, have been proposed as candidates for spectroscopic experiments which probe the dynamics and structure of the transition state in the unimolecular dissociation of polyatomic molecules. Energies of the low-lying vibrational levels, as well as those around the dissociation energy, are presented. Wave functions of highly vibrationally excited states, lying slightly below and slightly above the dissociation threshold, are analyzed graphically.
20-MHz B-mode ultrasound in monitoring the course of localized scleroderma (morphea).
Hoffmann, K; Gerbaulet, U; el-Gammal, S; Altmeyer, P
1991-01-01
Ultrasonographic methods have recently provided us with the means for objective and non-invasive monitoring of the dynamics of chronic skin diseases. We examined 34 patients with localized scleroderma (morphea) using a 20-MHz B-mode ultrasound scanner (DUB 20, Taberna pro Medicum, Lüneburg). In patients with plaque-type and linear band-type localized scleroderma intraindividual comparison of sclerotic skin with corresponding areas of healthy skin showed thickening of the corium. The increase in corium thickness was between 2% and 251%. The extent of the difference in corium thickness between sclerotic and healthy skin depended on the location-originally thin skin showed a greater degree of sclerosis. We also frequently found enhanced reflexes in the lower corium and hyperechoic, widened bands of connective tissue traversing the subcutaneous fatty tissue from the corium-subcutis border in the direction of the muscle fascia. 20 patients were examined several times in the course of one year. In nine patients we found ultrasonographic evidence of regression (decrease in thickness 26%) and in nine the ultrasound examination showed progression (increase in thickness 28%). 20-MHz B-mode ultrasound imaging is a suitable non-invasive method for monitoring the course and treatment of localized scleroderma. Its routine use is strongly recommended.
Free-boundary ideal MHD modes in W7-AS
Energy Technology Data Exchange (ETDEWEB)
Merkel, P.; Nuehrenberg, C. [Max-Planck-Institut fuer Plasmaphysik, Teilinstitut Greifswald, Greifswald (Germany); Cooper, W.A. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)
1996-09-01
The CAS3D stability code may now be used to analyze the ideal magnetohydrodynamic energy principle for three-dimensional plasmas surrounded by a vacuum region, i.e. for perturbations which may deform the plasma-vacuum interface because of a non-vanishing normal component on this surface. A Green`s function technique is used here to determine the vacuum energy contribution from a surface integral with the plasma-vacuum interface as domain of integration. Assets of this procedure are that it does not require to continue either the coordinate system nor the perturbation functions into the vacuum region. The application of the CAS3D free-boundary stability code to a set of finite-{beta} W7-AS plasma configurations, computationally generated from the W7-AS coil data, shows that unstable, radially extended free-boundary modes exist in equilibria of this set, for which the local Mercier stability criterion detects stability. This is in contrast to the behaviour of the fixed-boundary modes, for which the point of marginal stability approximately coincides with the one given by the local stability analysis. Corresponding results from the TERPSICHORE and CAS3D codes are in good agreement. (author) 6 figs., 16 refs.
Jaber, Abobaker M; Ismail, Mohd Tahir; Altaher, Alsaidi M
2014-01-01
This paper mainly forecasts the daily closing price of stock markets. We propose a two-stage technique that combines the empirical mode decomposition (EMD) with nonparametric methods of local linear quantile (LLQ). We use the proposed technique, EMD-LLQ, to forecast two stock index time series. Detailed experiments are implemented for the proposed method, in which EMD-LPQ, EMD, and Holt-Winter methods are compared. The proposed EMD-LPQ model is determined to be superior to the EMD and Holt-Winter methods in predicting the stock closing prices.
Resistive Reduced MHD Modeling of Multi-Edge-Localized-Mode Cycles in Tokamak X -Point Plasmas
Orain, F.; Bécoulet, M.; Huijsmans, G. T. A.; Dif-Pradalier, G.; Hoelzl, M.; Morales, J.; Garbet, X.; Nardon, E.; Pamela, S.; Passeron, C.; Latu, G.; Fil, A.; Cahyna, P.
2015-01-01
The full dynamics of a multi-edge-localized-mode (ELM) cycle is modeled for the first time in realistic tokamak X -point geometry with the nonlinear reduced MHD code jorek. The diamagnetic rotation is found to be instrumental to stabilize the plasma after an ELM crash and to model the cyclic reconstruction and collapse of the plasma pressure profile. ELM relaxations are cyclically initiated each time the pedestal gradient crosses a triggering threshold. Diamagnetic drifts are also found to yield a near-symmetric ELM power deposition on the inner and outer divertor target plates, consistent with experimental measurements.
Capture and release of traveling intrinsic localized mode in coupled cantilever array.
Kimura, Masayuki; Hikihara, Takashi
2009-03-01
A method to manipulate intrinsic localized mode (ILM) is numerically discussed in a nonlinear coupled oscillator array, which is obtained by modeling a microcantilever array. Prior to the manipulation, coexistence and dynamical stability of standing ILMs are first investigated. The stability of coexisting ILMs is determined by a nonlinear coupling coefficient of the array. In addition, the global phase structure, which dominates traveling ILMs, is also changed with the stability. It makes possible to manipulate a traveling ILM by adjusting the nonlinear coupling coefficient. The capture and release manipulation of the traveling ILM is shown numerically.
Directory of Open Access Journals (Sweden)
Abobaker M. Jaber
2014-01-01
Full Text Available This paper mainly forecasts the daily closing price of stock markets. We propose a two-stage technique that combines the empirical mode decomposition (EMD with nonparametric methods of local linear quantile (LLQ. We use the proposed technique, EMD-LLQ, to forecast two stock index time series. Detailed experiments are implemented for the proposed method, in which EMD-LPQ, EMD, and Holt-Winter methods are compared. The proposed EMD-LPQ model is determined to be superior to the EMD and Holt-Winter methods in predicting the stock closing prices.
Pedestal and E r profile evolution during an edge localized mode cycle at ASDEX Upgrade
Cavedon, M.; Pütterich, T.; Viezzer, E.; Laggner, F. M.; Burckhart, A.; Dunne, M.; Fischer, R.; Lebschy, A.; Mink, F.; Stroth, U.; Willensdorfer, M.; Wolfrum, E.; the ASDEX Upgrade Team
2017-10-01
The upgrade of the edge charge exchange recombination spectroscopy diagnostic at ASDEX Upgrade has enabled highly spatially resolved measurements of the impurity ion dynamics during an edge-localized mode cycle (ELM) with unprecedented temporal resolution, i.e. 65 μs. The increase of transport during an ELM induces a relaxation of the ion, electron edge gradients in impurity density and flows. Detailed characterization of the recovery of the edge temperature gradients reveals a difference in the ion and electron channel: the maximum ion temperature gradient {{\
Energy Technology Data Exchange (ETDEWEB)
Wang, Xian-Qu [Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhang, Rui-Bin; Meng, Guo [State Key Lab of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China)
2016-07-15
The destabilization of ideal internal kink modes by trapped fast particles in tokamak plasmas with a “shoulder”-like equilibrium current is investigated. It is found that energetic particle branch of the mode is unstable with the driving of fast-particle precession drifts and corresponds to a precessional fishbone. The mode with a low stability threshold is also more easily excited than the conventional precessional fishbone. This is different from earlier studies for the same equilibrium in which the magnetohydrodynamic (MHD) branch of the mode is stable. Furthermore, the stability and characteristic frequency of the mode are analyzed by solving the dispersion relation and comparing with the conventional fishbone. The results suggest that an equilibrium with a locally flattened q-profile, may be modified by localized current drive (or bootstrap current, etc.), is prone to the onset of the precessional fishbone branch of the mode.
Localization and fractal spectra of optical phonon modes in quasiperiodic structures
Anselmo, D. H. A. L.; Dantas, A. L.; Medeiros, S. K.; Albuquerque, E. L.; Freire, V. N.
2005-04-01
The dispersion relation and localization profile of confined optical phonon modes in quasiperiodic structures, made up of nitride semiconductor materials, are analyzed through a transfer-matrix approach. The quasiperiodic structures are characterized by the nature of their Fourier spectrum, which can be dense pure point (Fibonacci sequences) or singular continuous (Thue-Morse and Double-period sequences). These substitutional sequences are described in terms of a series of generations that obey peculiar recursion relations and/or inflation rules. We present a quantitative analysis of the localization and magnitude of the allowed band widths in the optical phonons spectra of these quasiperiodic structures, as well as how they scale as a function of the number of generations of the sequences.
Institute of Scientific and Technical Information of China (English)
Liu Yang; Tang Yi
2008-01-01
By means of the Glauber's coherent state method combined with multiple-scale method,this paper investigates the localized modes in a quantum one-dimensional Klein-Gordon chain and finds that the equation of motion of annihilation operator is reduced to the nonlinear Schr(o)dinger equation.Interestingly,the model can support both bright and dark small amplitude travelling and non-travelling nonlinear localized modes in different parameter spaces.
Lv, Wei; Henry, Asegun
2016-10-01
Thermal conductivity is important for almost all applications involving heat transfer. The theory and modeling of crystalline materials is in some sense a solved problem, where one can now calculate their thermal conductivity from first principles using expressions based on the phonon gas model (PGM). However, modeling of amorphous materials still has many open questions, because the PGM itself becomes questionable when one cannot rigorously define the phonon velocities. In this report, we used our recently developed Green-Kubo modal analysis (GKMA) method to study amorphous silicon dioxide (a-SiO2). The predicted thermal conductivities exhibit excellent agreement with experiments and anharmonic effects are included in the thermal conductivity calculation for all the modes in a-SiO2 for the first time. Previously, localized modes (locons) have been thought to have a negligible contribution to thermal conductivity, due to their highly localized nature. However, in a-SiO2 our results indicate that locons contribute more than 10% to the total thermal conductivity from 400 K to 800 K and they are largely responsible for the increase in thermal conductivity of a-SiO2 above room temperature. This is an effect that cannot be explained by previous methods and therefore offers new insight into the nature of phonon transport in amorphous/glassy materials.
Boukahil, A.; Huber, D. L.
1989-09-01
The harmonic magnon modes in a one-dimensional Heisenberg spin glass having nearest-neighbor exchange interactions of fixed magnitude and random sign are investigated. The Lyapounov exponent is calculated for chains of 107-108 spins over the interval 0<=ω<=4J. In the low-frequency regime, ω<~0.1J, an anomalous behavior for the density of states ρ(ω)~ω-1/3 is established, consistent with earlier results obtained by Stinchcombe and Pimentel using transfer-matrix techniques; at higher frequencies, gaps appear in the spectrum. At low frequencies, the localization length diverges as ω-2/3. A formal connection is established between the spin glass and the one-dimensional discretized Schrödinger equation. By making use of the connection, it is shown that the theory of Derrida and Gardner, which was developed for weak potential disorder, can account quantitatively for the distribution and localization of the low-frequency magnon modes in the spin-glass model.
Lv, Wei; Henry, Asegun
2016-10-21
Thermal conductivity is important for almost all applications involving heat transfer. The theory and modeling of crystalline materials is in some sense a solved problem, where one can now calculate their thermal conductivity from first principles using expressions based on the phonon gas model (PGM). However, modeling of amorphous materials still has many open questions, because the PGM itself becomes questionable when one cannot rigorously define the phonon velocities. In this report, we used our recently developed Green-Kubo modal analysis (GKMA) method to study amorphous silicon dioxide (a-SiO2). The predicted thermal conductivities exhibit excellent agreement with experiments and anharmonic effects are included in the thermal conductivity calculation for all the modes in a-SiO2 for the first time. Previously, localized modes (locons) have been thought to have a negligible contribution to thermal conductivity, due to their highly localized nature. However, in a-SiO2 our results indicate that locons contribute more than 10% to the total thermal conductivity from 400 K to 800 K and they are largely responsible for the increase in thermal conductivity of a-SiO2 above room temperature. This is an effect that cannot be explained by previous methods and therefore offers new insight into the nature of phonon transport in amorphous/glassy materials.
Mode decomposition methods for flows in high-contrast porous media. Global-local approach
Ghommem, Mehdi
2013-11-01
In this paper, we combine concepts of the generalized multiscale finite element method (GMsFEM) and mode decomposition methods to construct a robust global-local approach for model reduction of flows in high-contrast porous media. This is achieved by implementing Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) techniques on a coarse grid computed using GMsFEM. The resulting reduced-order approach enables a significant reduction in the flow problem size while accurately capturing the behavior of fully-resolved solutions. We consider a variety of high-contrast coefficients and present the corresponding numerical results to illustrate the effectiveness of the proposed technique. This paper is a continuation of our work presented in Ghommem et al. (2013) [1] where we examine the applicability of POD and DMD to derive simplified and reliable representations of flows in high-contrast porous media on fully resolved models. In the current paper, we discuss how these global model reduction approaches can be combined with local techniques to speed-up the simulations. The speed-up is due to inexpensive, while sufficiently accurate, computations of global snapshots. © 2013 Elsevier Inc.
Characterization of small, Type V edge-localized modes in the National Spherical Torus Experiment
Energy Technology Data Exchange (ETDEWEB)
Maingi, Rajesh [ORNL; Bell, M. [Princeton Plasma Physics Laboratory (PPPL); Fredrickson, E. [Princeton Plasma Physics Laboratory (PPPL); Lee, K. C. [Princeton Plasma Physics Laboratory (PPPL); Maqueda, R. J. [Nova Photonics, Princeton, NJ; Snyder, P. [General Atomics, San Diego; Tritz, K. [Johns Hopkins University; Zweben, S. J. [Princeton Plasma Physics Laboratory (PPPL); Bell, R. E. [Princeton Plasma Physics Laboratory (PPPL); Biewer, Theodore M [ORNL; Bush, Charles E [ORNL; Boedo, J. [University of California, San Diego; Brooks, N. H. [General Atomics, San Diego; Delgado-Aparicio, L. [Johns Hopkins University; Domier, C. W. [University of California, Davis; Gates, D. [Princeton Plasma Physics Laboratory (PPPL); Johnson, D. W. [Princeton Plasma Physics Laboratory (PPPL); Kaita, R. [Princeton Plasma Physics Laboratory (PPPL); Kaye, S. M. [Princeton Plasma Physics Laboratory (PPPL); Kugel, H. [Princeton Plasma Physics Laboratory (PPPL); LaBlanc, B. P. [Princeton Plasma Physics Laboratory (PPPL); Luhmann, N. C. [University of California, Davis; Menard, J. [Princeton Plasma Physics Laboratory (PPPL); Mueller, D. [Princeton Plasma Physics Laboratory (PPPL); Park, H. [Princeton Plasma Physics Laboratory (PPPL); Raman, R [University of Washington, Seattle; Roquemore, A. L. [Princeton Plasma Physics Laboratory (PPPL); Sabbagh, S. A. [Columbia University; Soukhanovskii, V. A. [Lawrence Livermore National Laboratory (LLNL); Stevenson, T. [Princeton Plasma Physics Laboratory (PPPL); Stutman, D. [General Atomics, San Diego
2006-01-01
There has been a substantial international research effort in the fusion community to identify tokamak operating regimes with either small or no periodic bursts of particles and power from the edge plasma, known as edge-localized modes (ELMs). While several candidate regimes have been presented in the literature, very little has been published on the characteristics of the small ELMs themselves. One such small ELM regime, also known as the Type V ELM regime, was recently identified in the National Spherical Torus Experiment [M. Ono, S. M. Kaye, Y.-K. M. Peng et al., Nucl. Fusion 40, 557 (2000)]. In this paper, the spatial and temporal structure of the Type V ELMs is presented, as measured by several different diagnostics. The composite picture of the Type V ELM is of an instability with one or two filaments that rotate toroidally at ~5-10 km/s, in the direction opposite to the plasma current and neutral beam injection. The toroidal extent of Type V ELMs is typically ~5 m, whereas the cross-field (radial) extent is typically 10 cm (3cm), yielding a portrait of an electromagnetic, ribbon-like perturbation aligned with the total magnetic field. The filaments comprising the Type V ELM appear to be destabilized near the top of the H-mode pedestal and drift radially outward as they rotate toroidally. After the filaments come in contact with the open field lines, the divertor plasma perturbations are qualitatively similar to other ELM types, albeit with only one or two filaments in the Type V ELM versus more filaments for Type I and Type III ELMs. Preliminary stability calculations eliminate pressure driven modes as the underlying instability for Type V ELMs, but more work is required to determine if current driven modes are responsible for destabilization.
Nonlinear localized modes in dipolar Bose–Einstein condensates in two-dimensional optical lattices
Energy Technology Data Exchange (ETDEWEB)
Rojas-Rojas, Santiago, E-mail: srojas@cefop.cl [Center for Optics and Photonics and MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Naether, Uta [Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, 50009 Zaragoza (Spain); Delgado, Aldo [Center for Optics and Photonics and MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Vicencio, Rodrigo A. [Center for Optics and Photonics and MSI-Nucleus on Advanced Optics, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago (Chile)
2016-09-16
Highlights: • We study discrete two-dimensional breathers in dipolar Bose–Einstein Condensates. • Important differences in the properties of three fundamental modes are found. • Norm threshold for existence of 2D breathers varies with dipolar interaction. • The Effective Potential Method is implemented for stability analysis. • Uncommon mobility of 2D discrete solitons is observed. - Abstract: We analyze the existence and properties of discrete localized excitations in a Bose–Einstein condensate loaded into a periodic two-dimensional optical lattice, when a dipolar interaction between atoms is present. The dependence of the Number of Atoms (Norm) on the energy of solutions is studied, along with their stability. Two important features of the system are shown, namely, the absence of the Norm threshold required for localized solutions to exist in finite 2D systems, and the existence of regions in the parameter space where two fundamental solutions are simultaneously unstable. This feature enables mobility of localized solutions, which is an uncommon feature in 2D discrete nonlinear systems. With attractive dipolar interaction, a non-trivial behavior of the Norm dependence is obtained, which is well described by an analytical model.
Lin, C S; Lim, H S; Wang, Z K; Ng, S C; Kuok, M H; Adeyeye, A O
2011-03-01
An understanding of the spin dynamics of nanoscale magnetic elements is important for their applications in magnetic sensing and storage. Inhomogeneity of the demagnetizing field in a non-ellipsoidal magnetic element results in localization of spin waves near the edge of the element. However, relative little work has been carried out to investigate the effect of the applied magnetic fields on the nature of such localized modes. In this study, micromagnetic simulations are performed on an equilateral triangular nanomagnet to investigate the magnetic field dependence of the mode profiles of the lowest-frequency spin wave. Our findings reveal that the lowest-frequency mode is localized at the base edge of the equilateral triangle. The characteristics of its mode profile change with the ground state magnetization configuration of the nanotriangle, which, in turn, depends on the magnitude of the in-plane applied magnetic field.
Relationship of edge localized mode burst times with divertor flux loop signal phase in JET
Energy Technology Data Exchange (ETDEWEB)
Chapman, S. C., E-mail: S.C.Chapman@warwick.ac.uk [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry (United Kingdom); Max Planck Institute for the Physics of Complex Systems, Dresden (Germany); Dendy, R. O. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry (United Kingdom); Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxfordshire (United Kingdom); JET-EFDA, Culham Science Centre, Abingdon, Oxfordshire (United Kingdom); Todd, T. N.; Webster, A. J.; Morris, J. [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxfordshire (United Kingdom); JET-EFDA, Culham Science Centre, Abingdon, Oxfordshire (United Kingdom); Watkins, N. W. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry (United Kingdom); Max Planck Institute for the Physics of Complex Systems, Dresden (Germany); Centre for the Analysis of Time Series, London School of Economics, London (United Kingdom); Department of Engineering and Innovation, Open University, Milton Keynes (United Kingdom); Calderon, F. A. [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry (United Kingdom); JET-EFDA, Culham Science Centre, Abingdon, Oxfordshire (United Kingdom)
2014-06-15
A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM.
Low-temperature heat capacity and localized vibrational modes in natural and synthetic tetrahedrites
Lara-Curzio, E.; May, A. F.; Delaire, O.; McGuire, M. A.; Lu, X.; Liu, Cheng-Yun; Case, E. D.; Morelli, D. T.
2014-05-01
The heat capacity of natural (Cu12-x (Fe, Zn, Ag)x(Sb, As)4S13) and synthetic (Cu12-xZnxSb4S13 with x = 0, 1, 2) tetrahedrite compounds was measured between 2 K and 380 K. It was found that the temperature dependence of the heat capacity can be described using a Debye term and three Einstein oscillators with characteristic temperatures that correspond to energies of ˜1.0 meV, ˜2.8 meV, and ˜8.4 meV. The existence of localized vibrational modes, which are assigned to the displacements of the trigonally coordinated Cu atoms in the structure, is discussed in the context of anharmonicity and its effect on the low lattice thermal conductivity exhibited by these compounds.
Impact of intrinsic localized modes of atomic motion on materials properties
Energy Technology Data Exchange (ETDEWEB)
Manley, M E
2010-01-20
Recent neutron and x-ray scattering measurements show intrinsic localized modes (ILMs) in metallic uranium and ionic sodium iodide. Here, the role ILMs play in the behavior of these materials is examined. With the thermal activation of ILMs, thermal expansion is enhanced, made more anisotropic, and, at a microscopic level, becomes inhomogeneous. Interstitial diffusion, ionic conductivity, the annealing rate of radiation damage, and void growth are all influenced by ILMs. The lattice thermal conductivity is suppressed above the ILM activation temperature while no impact is observed in the electrical conductivity. This complement of transport properties suggests that ILMs could improve thermoelectric performance. Ramifications also include thermal ratcheting, a transition from brittle to ductile fracture, and possibly a phase transformation in uranium.
Enhanced toroidal flow stabilization of edge localized modes with increased plasma density
Cheng, Shikui; Zhu, Ping; Banerjee, Debabrata
2017-09-01
Toroidal flow alone is generally thought to have an important influence on tokamak edge pedestal stability, even though theoretical analysis often predicts merely a weak stabilizing effect of toroidal flow on the edge localized modes (ELMs) in experimental parameter regimes. For the first time, we find from two-fluid MHD calculations that such a stabilization, however, can be significantly enhanced by increasing the edge plasma density. Our finding resolves a long-standing mystery whether or how toroidal rotation can indeed have an effective influence on ELMs, and explains why the ELM mitigation and suppression by toroidal rotation are more favorably achieved in higher collisionality regime in recent experiments. The finding suggests a new control scheme on modulating toroidal flow stabilization of ELMs with plasma density, along with a new additional constraint on the optimal level of plasma density for the desired edge plasma conditions.
An approach to the damping of local modes of oscillations resulting from large hydraulic transients
Energy Technology Data Exchange (ETDEWEB)
Dobrijevic, D.M.; Jankovic, M.V.
1999-09-01
A new method of damping of local modes of oscillations under large disturbance is presented in this paper. The digital governor controller is used. Controller operates in real time to improve the generating unit transients through the guide vane position and the runner blade position. The developed digital governor controller, whose control signals are adjusted using the on-line measurements, offers better damping effects for the generator oscillations under large disturbances than the conventional controller. Digital simulations of hydroelectric power plant equipped with low-head Kaplan turbine are performed and the comparisons between the digital governor control and the conventional governor control are presented. Simulation results show that the new controller offers better performances, than the conventional controller, when the system is subjected to large disturbances.
Local vibration modes of shallow thermal donors in nitrogen-doped CZ silicon crystals
Energy Technology Data Exchange (ETDEWEB)
Inoue, N. [RIAST, Osaka Prefecture University, Sakai, 599-8570 (Japan) and Nitrogen Measurement WG, JEITA, Tokyo, 101-0062 (Japan)]. E-mail: inouen@riast.osakafu-u.ac.jp; Nakatsu, M. [RIAST, Osaka Prefecture University, Sakai, 599-8570 (Japan); Ono, H. [Japan Fine Ceramics Center, Tokyo, 105-0003 (Japan); Nitrogen Measurement WG, JEITA, Tokyo, 101-0062 (Japan)
2006-04-01
Local vibration mode (LVM) infrared absorption from shallow thermal donors (STD) composed of nitrogen-oxygen complexes in nitrogen-doped CZ silicon crystals was examined. The samples whose STD concentration had been determined were measured. The sample dependence of the peaks at 810 and 1018cm{sup -1} was similar to that of STD but the estimated concentration was slightly higher. New LVM peaks were found at 855, 973, 982, 1002cm{sup -1} and so on. Their magnitude and sample dependence agreed well with those of STD. Annealing temperature dependence of other samples supported the results. Annealing time dependence of STD concentration at 650 deg. C was examined. STD peaks at 250, 242 and those at 240, 234 and 238cm{sup -1} behaved differently, suggesting the presence of two kinds of STD origin.
Directory of Open Access Journals (Sweden)
Abobaker M. Jaber
2014-01-01
Full Text Available Empirical mode decomposition (EMD is particularly useful in analyzing nonstationary and nonlinear time series. However, only partial data within boundaries are available because of the bounded support of the underlying time series. Consequently, the application of EMD to finite time series data results in large biases at the edges by increasing the bias and creating artificial wiggles. This study introduces a new two-stage method to automatically decrease the boundary effects present in EMD. At the first stage, local polynomial quantile regression (LLQ is applied to provide an efficient description of the corrupted and noisy data. The remaining series is assumed to be hidden in the residuals. Hence, EMD is applied to the residuals at the second stage. The final estimate is the summation of the fitting estimates from LLQ and EMD. Simulation was conducted to assess the practical performance of the proposed method. Results show that the proposed method is superior to classical EMD.
Localized Majorana-Like Modes in a Number-Conserving Setting: An Exactly Solvable Model.
Iemini, Fernando; Mazza, Leonardo; Rossini, Davide; Fazio, Rosario; Diehl, Sebastian
2015-10-09
In this Letter we present, in a number conserving framework, a model of interacting fermions in a two-wire geometry supporting nonlocal zero-energy Majorana-like edge excitations. The model has an exactly solvable line, on varying the density of fermions, described by a topologically nontrivial ground state wave function. Away from the exactly solvable line we study the system by means of the numerical density matrix renormalization group. We characterize its topological properties through the explicit calculation of a degenerate entanglement spectrum and of the braiding operators which are exponentially localized at the edges. Furthermore, we establish the presence of a gap in its single particle spectrum while the Hamiltonian is gapless, and compute the correlations between the edge modes as well as the superfluid correlations. The topological phase covers a sizable portion of the phase diagram, the solvable line being one of its boundaries.
Generation of localized modes in an electrical lattice using subharmonic driving.
English, L Q; Palmero, F; Candiani, P; Cuevas, J; Carretero-González, R; Kevrekidis, P G; Sievers, A J
2012-02-24
We show experimentally and numerically that an intrinsic localized mode (ILM) can be stably produced (and experimentally observed) via subharmonic, spatially homogeneous driving in the context of a nonlinear electrical lattice. The precise nonlinear spatial response of the system has been seen to depend on the relative location in frequency between the driver frequency, ω(d), and the bottom of the linear dispersion curve, ω(0). If ω(d)/2 lies just below ω(0), then a single ILM can be generated in a 32-node lattice, whereas, when ω(d)/2 lies within the dispersion band, a spatially extended waveform resembling a train of ILMs results. To our knowledge, and despite its apparently broad relevance, such an experimental observation of subharmonically driven ILMs has not been previously reported.
Suppression of edge localized mode crashes by multi-spectral non-axisymmetric fields in KSTAR
Kim, Jayhyun; Park, Gunyoung; Bae, Cheonho; Yoon, Siwoo; Han, Hyunsun; Yoo, Min-Gu; Park, Young-Seok; Ko, Won-Ha; Juhn, June-Woo; Na, Yong Su; The KSTAR Team
2017-02-01
Among various edge localized mode (ELM) crash control methods, only non-axisymmetric magnetic perturbations (NAMPs) yield complete suppression of ELM crashes beyond their mitigation, and thus attract more attention than others. No other devices except KSTAR, DIII-D, and recently EAST have successfully achieved complete suppression with NAMPs. The underlying physics mechanisms of these successful ELM crash suppressions in a non-axisymmetric field environment, however, still remain uncertain. In this work, we investigate the ELM crash suppression characteristics of the KSTAR ELMy H-mode discharges in a controlled multi-spectral field environment, created by both n=2 middle reference and n=1 top/bottom proxy in-vessel control coils. Interestingly, the attempts have produced a set of contradictory findings, one expected (ELM crash suppression enhancement with the addition of n = 1 to the n = 2 field at relatively low heating discharges) and another unexpected (ELM crash suppression degradation at relatively high heating discharges) from the earlier findings in DIII-D. This contradiction indicates the dependence of the ELM crash suppression characteristics on the heating level and the associated kink-like plasma responses. Preliminary linear resistive MHD plasma response simulation shows the unexpected suppression performance degradation to be likely caused by the dominance of kink-like plasma responses over the island gap-filling effects.
Localized Modes of the Linear Periodic Schr\\"{o}dinger Operator with a Nonlocal Perturbation
Dohnal, Tomá?; Reichel, Wolfgang
2008-01-01
We consider the existence of localized modes corresponding to eigenvalues of the periodic Schr\\"{o}dinger operator $-\\partial_x^2+ V(x)$ with an interface. The interface is modeled by a jump either in the value or the derivative of $V(x)$ and, in general, does not correspond to a localized perturbation of the perfectly periodic operator. The periodic potentials on each side of the interface can, moreover, be different. As we show, eigenvalues can only occur in spectral gaps. We pose the eigenvalue problem as a $C^1$ gluing problem for the fundamental solutions (Bloch functions) of the second order ODEs on each side of the interface. The problem is thus reduced to finding matchings of the ratio functions $R_\\pm=\\frac{\\psi_\\pm'(0)}{\\psi_\\pm(0)}$, where $\\psi_\\pm$ are those Bloch functions that decay on the respective half-lines. These ratio functions are analyzed with the help of the Pr\\"{u}fer transformation. The limit values of $R_\\pm$ at band edges depend on the ordering of Dirichlet and Neumann eigenvalues ...
Sato, M; Shi, W; Shige, S; Ishikawa, T; Soga, Y; Hubbard, B E; Ilic, B; Sievers, A J
2014-01-01
Both low frequency and high frequency impurity modes have been produced in a SiN micromechanical cantilever array by illumination with either an infrared or visible laser. When such laser-induced impurities are placed near a driven intrinsic localized mode (ILM) it is either repelled or attracted. By measuring the linear response spectrum for these two cases it was found that vibrational hopping of the ILM takes place when the natural frequency of the ILM and an even symmetry linear local mode are symmetrically located about the driven ILM frequency so that parametric excitation of these two linear modes is enhanced, amplifying the lateral motion of the ILM. Numerical simulations are consistent with these signature findings. It is also demonstrated that the correct sign of the observed interaction can be found with a harmonic lattice-impurity model but the magnitude of the effect is enhanced in a nonlinear lattice.
Localized Phonons Associated with Solitons in Polyacetylene: Coupling to the Nonuniform Mode
1987-11-15
the translational tribute to the infrared conductivity . 6 This nonuniform motion of the added charge. In the presence of a bond- translational mode is...two normal modes of the soliton. The first is three peaks (B modes) in the infrared conductivity . The -. the uniform translational (Goldstone) mode of...SCHAFFER, R. H. FRIEND, AND A. J. HEEGER 36 polythiophene , 2 1 the complexity of that system may have Coulomb correlations are of some importance in
The Materials Mode in the Local Context of Mugla and the Role of Mother Tongue
Korkut, Perihan; Ertas, Abdullah
2017-01-01
Materials mode is one of the four modes of a lesson in the Self Evaluation Teacher Talk (SETT) framework. The aim of this study is to identify the interactional features during the materials mode in Mugla, Turkey. The lessons of English teachers at the state schools and the microteaching presentations of teacher trainees at Mugla Sitki Koçman…
Tang, Bing; Li, Guang-Ling; Fu, Mei
2017-03-01
A semiclassical theoretical study on the property of the modulational instability of corresponding linear spin-waves and the presence of nonlinear localized excitations in a discrete quantum ferromagnetic spin chain with single-ion easy-axis anisotropy is reported. We consider the Glauber coherent-state representation combined with the Dyson-Maleev transformation for local spin operators as the basic representation of the system, and derive the equation of motion by means of the Ehrenfest theorem. Using a modulational instability analysis of plane waves, we predict the existence regions of bright envelope solitons and intrinsic localized spin-wave modes. Besides, with the help of a semidiscrete multi-scale method, we obtain analytical solutions for the bright envelope soliton and intrinsic localized spin-wave mode. Moreover, we analyze their existence conditions, which agree with the results of modulational instability analysis.
Wang, Zheng; Liu, Chao; Li, Erwen; Chakravarty, Swapnajit; Xu, Xiaochuan; Wang, Alan X.; Fan, D. L.; Chen, Ray T.
2017-02-01
Raman scattering spectroscopy is a unique tool to probe vibrational, rotational, and other low-frequency modes of a molecular system and therefore could be utilized to identify chemistry and quantity of molecules. However, the ultralow efficient Raman scattering, which is only 1/109 1/1014 of the excitation light due to the small Raman scattering cross-sections of molecules, have significantly hindered its development in practical sensing applications. The discovery of surface-enhanced Raman scattering (SERS) in the 1970s and the significant progress in nanofabrication technique, provide a promising solution to overcome the inherent issues of Raman spectroscopy. It is found that In the vicinity of nanoparticles and their junctions, the Raman signals of molecules can be significantly improved by an enhancement factor as high as 1010, due to the ultrahigh electric field generated by the localized surface plasmons resonance (LSPR), where the intensity of Raman scattering is proportional to the |E|4. In this work, we propose and demonstrate a new approach combining LSPR from nanocapsules with densely assembled silver nanoparticles (NC-AgNPs) and guidemode- resonance (GMR) from dielectric photonic crystal slabs (PCSs) for SERS substrates with robustly high performance.
Inductive intrinsic localized modes in a one-dimensional nonlinear electric transmission line
Sato, M.; Mukaide, T.; Nakaguchi, T.; Sievers, A. J.
2016-07-01
The experimental properties of intrinsic localized modes (ILMs) have long been compared with theoretical dynamical lattice models that make use of nonlinear onsite and/or nearest-neighbor intersite potentials. Here it is shown for a one-dimensional lumped electrical transmission line that a nonlinear inductive component in an otherwise linear parallel capacitor lattice makes possible a new kind of ILM outside the plane wave spectrum. To simplify the analysis, the nonlinear inductive current equations are transformed to flux transmission line equations with analog onsite hard potential nonlinearities. Approximate analytic results compare favorably with those obtained from a driven damped lattice model and with eigenvalue simulations. For this mono-element lattice, ILMs above the top of the plane wave spectrum are the result. We find that the current ILM is spatially compressed relative to the corresponding flux ILM. Finally, this study makes the connection between the dynamics of mass and force constant defects in the harmonic lattice and ILMs in a strongly anharmonic lattice.
Perelli, Alessandro; De Marchi, Luca; Marzani, Alessandro; Speciale, Nicolò
2012-02-01
A strategy for the localization of acoustic emissions (AE) in plates with dispersion and reverberation is proposed. The procedure exploits signals received in passive mode by sparse conventional piezoelectric transducers and a three-step processing framework. The first step consists in a signal dispersion compensation procedure, which is achieved by means of the warped frequency transform. The second step concerns the estimation of the differences in arrival time (TDOA) of the acoustic emission at the sensors. Complexities related to reflections and plate resonances are overcome via a wavelet decomposition of cross-correlating signals where the mother function is designed by a synthetic warped cross-signal. The magnitude of the wavelet coefficients in the warped distance-frequency domain, in fact, precisely reveals the TDOA of an acoustic emission at two sensors. Finally, in the last step the TDOA data are exploited to locate the acoustic emission source through hyperbolic positioning. The proposed procedure is tested with a passive network of three/four piezo-sensors located symmetrically and asymmetrically with respect to the plate edges. The experimentally estimated AE locations are close to those theoretically predicted by the Cramèr-Rao lower bound.
Local vibration modes and nitrogen incorporation in AlGaAs:N layers
Energy Technology Data Exchange (ETDEWEB)
Gallardo, E.; Lazic, S.; Calleja, J.M. [Dept. de Fisica de Materiales, Universidad Autonoma de Madrid (Spain); Miguel-Sanchez, J.; Montes, M.; Hierro, A.; Gargallo-Caballero, R.; Guzman, A.; Munoz, E. [Instituto de Sistemas Optoelectronicos y Microtecnologia, Universidad Politecnica de Madrid (Spain); Teweldeberhan, A.M.; Fahy, S. [Tyndall National Institute, Cork (Ireland)
2008-07-01
Raman scattering measurements in dilute AlGaAs:N films grown by plasma-assisted molecular beam epitaxy on (100) GaAs substrates reveal strong local vibration modes (LVM) associated to N complexes. The LVM observed frequencies between 325 and 540 cm{sup -1} are in good agreement with density functional theory supercell calculations of Al{sub n}Ga{sub 4-n}N complexes (n=1,2,3,4). We find that the observed LVMs correspond to all n values including Al{sub 4}N. The LVMs spectra are resonant at energies around 1.85 eV. The values of the extended phonon frequencies of the ternary compound (GaAs and AlAs-like) reveal changes in the N distribution depending on the growth conditions: A transition from random- to non-random nitrogen distribution is observed upon increasing the growth temperature. Our results confirm the preferential bonding of N to Al in AlGaAs:N, due to the higher Al-N bond strength as compared to the Ga-N bond. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Intrinsic localized mode and low thermal conductivity of PbSe
Shulumba, Nina; Hellman, Olle; Minnich, Austin J.
2017-01-01
Lead chalcogenides such as PbS, PbSe, and PbTe are of interest for their exceptional thermoelectric properties and strongly anharmonic lattice dynamics. Although PbTe has received the most attention, PbSe has a lower thermal conductivity and a nonlinear temperature dependence of thermal resistivity despite being stiffer, trends that prior first-principles calculations have not fully reproduced. Here, we use ab initio calculations that explicitly account for strong anharmonicity and a computationally efficient stochastic phase-space sampling scheme to identify the origin of this low thermal conductivity as an anomalously large anharmonic interaction, exceeding in strength that in PbTe, between the transverse optic and longitudinal acoustic branches. The strong anharmonicity is reflected in the striking observation of an intrinsic localized mode that forms in the acoustic frequencies. Our work shows the deep insights into thermal phonons that can be obtained from ab initio calculations that do not rely on perturbations from the ground-state phonon dispersion.
Institute of Scientific and Technical Information of China (English)
赵付洲; 宋冰; 侍洪波
2016-01-01
There are multiple operating modes in the real industrial process, and the collected data follow the complex multimodal distribution, so most traditional process monitoring methods are no longer applicable because their presumptions are that sampled-data should obey the single Gaussian distribution or non-Gaussian distribution. In order to solve these problems, a novel weighted local standardization (WLS) strategy is proposed to standardize the multimodal data, which can eliminate the multi-mode characteristics of the collected data, and normalize them into unimodal data distribution. After detailed analysis of the raised data preprocessing strategy, a new algorithm using WLS strategy with support vector data description (SVDD) is put forward to apply for multi-mode monitoring process. Unlike the strategy of building multiple local models, the developed method only contains a model without the prior knowledge of multi-mode process. To demonstrate the proposed method’s validity, it is applied to a numerical example and a Tennessee Eastman (TE) process. Finally, the simulation results show that the WLS strategy is very effective to standardize multimodal data, and the WLS-SVDD monitoring method has great advantages over the traditional SVDD and PCA combined with a local standardization strategy (LNS-PCA) in multi-mode process monitoring.
Direct observation of current in type-I edge-localized-mode filaments on the ASDEX upgrade tokamak
DEFF Research Database (Denmark)
Vianello, N.; Zuin, M.; Cavazzana, R.;
2011-01-01
Magnetically confined plasmas in the high confinement regime are regularly subjected to relaxation oscillations, termed edge localized modes (ELMs), leading to large transport events. Present ELM theories rely on a combined effect of edge current and the edge pressure gradients which result in in...
Kendrick, Maureen; Mutonyi, Harriet
2007-01-01
This article seeks to better understand the relation between local and traditional modes of communication and health literacy within the context of a rural West Nile community in Northern Uganda. Drawing on social semiotics (multimodality) and Bakhtin's notion of the carnival, the focus is on a group of women participating in a grassroots literacy…
Toi, K.; Ohdachi, S.; Ueda, R.; Watanabe, K. Y.; Nicolas, T.; Suzuki, Y.; Ogawa, K.; Tanaka, K.; Takemura, Y.; LHD Experiment Group
2016-09-01
Clear suppression of magnetic fluctuations associated with resistive interchange modes (RICs) is observed during long edge-localized-mode (ELM)-free phases of the H-mode plasma in an outward-shifted configuration of the Large Helical Decice, in which a steep pressure gradient is generated at the plasma edge in the magnetic hill. The ELM-free H-phase is interrupted by large amplitude ELMs which are thought to be induced through nonlinear evolution of the RICs having m = 1/n = 1 dominant component (m: poloidal mode number, n: toroidal one). The m = 1/n = 1 RIC amplitude is enhanced about 10 times compared with the H-phase level during each ELM. In most of the H-mode shots, the final ELM-free phase returns to L-phase by a large amplitude ELM. In the L-phase, the RIC amplitude is enhanced by a factor of ~3 compared with that in the H-phase, although the edge pressure gradient is reduced considerably. Linear resistive magnetohydrodynamic stability analysis is attempted using experimentally obtained equilibrium profiles. From the numerical analysis, the distance between the location of the steepest pressure gradient and the main mode resonance surface, i.e. the rotational transform ι = 1, is found to be important for a large growth of the m = 1/n = 1 RIC in the H-phase.
Requirements on localized current drive for the suppression of neoclassical tearing modes
Bertelli, N.; De Lazzari, D.; Westerhof, E.
2011-10-01
A heuristic criterion for the full suppression of an NTM was formulated as ηNTM ≡ jCD,max/jBS >= 1.2 (Zohm et al 2005 J. Phys. Conf. Ser. 25 234), where jCD,max is the maximum in the driven current density profile applied to stabilize the mode and jBS is the local bootstrap current density. In this work we subject this criterion to a systematic theoretical analysis on the basis of the generalized Rutherford equation. Taking into account only the effect of jCD inside the island, a new criterion for full suppression by a minimum applied total current is obtained in the form of a maximum allowed value for the width of the driven current, wdep, combined with a required minimum for the total driven current in the form of wdepηNTM, where both limits depend on the marginal and saturated island sizes. These requirements can be relaxed when additional effects are taken into account, such as a change in the stability parameter Δ' from the current driven outside the island, power modulation, the accompanying heating inside the island or when the current drive is applied preemptively. When applied to ITER scenario 2, the requirement for full suppression of either the 3/2 or 2/1 NTM becomes wdep ~ 5 cm in agreement with (Sauter et al 2010 Plasma Phys. Control. Fusion 52 025002). Optimization of the ITER ECRH Upper Port Launcher design towards minimum required power for full NTM suppression requires an increase in the toroidal injection angle of the lower steering mirror of several degrees compared with its present design value, while for the upper steering mirror the present design value is close to the optimum.
Energy Technology Data Exchange (ETDEWEB)
NONE
1999-07-01
In France, the collection and processing of wastes are local public utility activities. These public utilities can be of two type: administrative when their are financed by a local tax, and industrial/commercial when they are financed by a fee. This document presents the different ways of waste management (public corporation, public market or public utility delegation), the management systems in practice, and the criteria for the choice of a management system. (J.S.)
Photonic band-gap and defect modes of a one-dimensional photonic crystal under localized compression
Sánchez, A.; Porta, A. V.; Orozco, S.
2017-05-01
The rupture of periodicity caused by one defect (defect layer) in a one-dimensional photonic crystal (1DPhC) results in a narrow transmission spectral line in the photonic band-gap, and the field distribution shows a strong confinement in the proximity of the defect layer. In this work, we present a theoretical model to calculate the frequency of defect modes caused by defect layers induced by localized mechanical stress. Two periodical arrangements were studied: one with layers of poly(methyl-methacrylate) (PMMA) and polystyrene (PS), PMMA-PS; the other with layers of PMMA and fused silica (SiO2), PMMA-SiO2. The defect layers were induced by localized compression (tension). The frequencies of the defect modes were calculated using elasto-optical theory and plane wave expansion and perturbation methods. Numerical results show that the frequency of the defect mode increases (decreases) when the compression (tension) increases. Based on the theoretical model developed, we show that compression of n layers of a 1DPhC induces n defect modes whose frequencies depend on the compression magnitude in the case of normal incidence of electromagnetic waves, in accordance with the results reported for other types of defect layers. The methodology shows the feasibility of the plane wave expansion and perturbation methods to study the frequency of the defect modes. Both periodical arrangements are suitable for designing mechanically tunable (1DPhC)-based narrow pass band filters and narrow reflectors in the (60, 65) THz range.
Sato, M; Imai, S; Fujita, N; Shi, W; Takao, Y; Sada, Y; Hubbard, B E; Ilic, B; Sievers, A J
2013-01-01
An intrinsic localized mode (ILM) represents a localized vibrational excitation in a nonlinear lattice. Such a mode will stay in resonance as the driver frequency is changed adiabatically until a bifurcation point is reached, at which point the ILM switches and disappears. The dynamics behind switching in such a many body system is examined here through experimental measurements and numerical simulations. Linear response spectra of a driven micromechanical array containing an ILM were measured in the frequency region between two fundamentally different kinds of bifurcation points that separate the large amplitude ILM state from the two low amplitude vibrational states. Just as a natural frequency can be associated with a driven harmonic oscillator, a similar natural frequency has been found for a driven ILM via the beat frequency between it and a weak, tunable probe. This finding has been confirmed using numerical simulations. The behavior of this nonlinear natural frequency plays important but different roles as the two bifurcation points are approached. At the upper transition its frequency coalesces with the driver and the resulting bifurcation is very similar to the saddle-node bifurcation of a single driven Duffing oscillator, which is treated in an Appendix. The lower transition occurs when the four-wave mixing partner of the natural frequency of the ILM intersects the topmost extended band mode of the same symmetry. The properties of linear local modes associated with the driven ILM are also identified experimentally for the first time and numerically but play no role in these transitions.
Sato, M.; Imai, S.; Fujita, N.; Shi, W.; Takao, Y.; Sada, Y.; Hubbard, B. E.; Ilic, B.; Sievers, A. J.
2013-01-01
An intrinsic localized mode (ILM) represents a localized vibrational excitation in a nonlinear lattice. Such a mode will stay in resonance as the driver frequency is changed adiabatically until a bifurcation point is reached, at which point the ILM switches and disappears. The dynamics behind switching in such a many body system is examined here through experimental measurements and numerical simulations. Linear response spectra of a driven micromechanical array containing an ILM were measured in the frequency region between two fundamentally different kinds of bifurcation points that separate the large amplitude ILM state from the two low amplitude vibrational states. Just as a natural frequency can be associated with a driven harmonic oscillator, a similar natural frequency has been found for a driven ILM via the beat frequency between it and a weak, tunable probe. This finding has been confirmed using numerical simulations. The behavior of this nonlinear natural frequency plays important but different roles as the two bifurcation points are approached. At the upper transition its frequency coalesces with the driver and the resulting bifurcation is very similar to the saddle-node bifurcation of a single driven Duffing oscillator, which is treated in an Appendix. The lower transition occurs when the four-wave mixing partner of the natural frequency of the ILM intersects the topmost extended band mode of the same symmetry. The properties of linear local modes associated with the driven ILM are also identified experimentally for the first time and numerically but play no role in these transitions.
Radial localization of edge modes in Alcator C-Mod pedestals using optical diagnostics
Theiler, C.; Terry, J. L.; Edlund, E.; Cziegler, I.; Churchill, R. M.; Hughes, J. W.; LaBombard, B.; Golfinopoulos, T.; the Alcator C-Mod Team
2017-02-01
Dedicated experiments in ion cyclotron range heated enhanced D-alpha (EDA) H-mode and I-mode plasmas have been performed on Alcator C-Mod to identify the location of edge fluctuations inside the pedestal and to determine their plasma frame phase velocity. For this purpose, measurements from gas puff imaging (GPI) and gas puff charge exchange recombination spectroscopy (GP-CXRS) have been collected using the same optical views. The data suggest that the EDA H-mode-specific quasi-coherent mode (QCM) is centered near the radial electric field (E r) well minimum and propagates along the ion diamagnetic drift direction in the plasma frame. The weakly coherent mode (WCM) and the geodesic acoustic mode observed in I-mode, on the other hand, are found to be located around the outer shear layer of the E r well. This results in a weak plasma frame phase velocity mostly along the electron diamagnetic drift direction for the WCM. The findings in these EDA H-mode plasmas differ from probe measurements in ohmic EDA H-mode (LaBombard et al 2014 Phys. Plasmas 21 056108), where the QCM was identified as an electron drift-wave located several mm outside the E r well minimum in a region of positive E r. To explore if instrumental effects of the optical diagnostics could be the cause of the difference, a synthetic diagnostic for GPI is introduced. This diagnostic reproduces amplitude ratios and relative radial shifts of the mode profiles determined from poloidally and toroidally oriented optics and, if instrumental effects related to GP-CXRS are also included, indicates that the measured location of the QCM and WCM relative to the E r well reported here is only weakly affected by instrumental effects.
A suggestion on new mode for tapping local resources of bittern and natural gas
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
@@ Amid an upsurge of industrialization and urbanization, China's economic future is likely to be threatened by a shortage in national per capita resources, a fragile ecological foundation, as well by as an economy based on the traditional extensive development mode.
Observation of localized flat-band modes in a one-dimensional photonic rhombic lattice
Mukherjee, Sebabrata
2015-01-01
We experimentally demonstrate the photonic realization of a dispersionless flat-band in a one-dimensional photonic rhombic lattice fabricated by ultrafast laser inscription. In the nearest neighbor tight binding approximation the lattice supports two dispersive and a non-dispersive (flat) band. We experimentally excite a superposition of flat-band eigen modes at the input of the photonic lattice and show the diffractionless propagation of the input modes due to their infinite effective mass.
Mackeprang, Kasper; Kjaergaard, Henrik G.
2017-04-01
The local mode perturbation theory (LMPT) model was developed to improve the description of hydrogen bonded XH-stretching transitions, where X is typically O or N. We present a modified version of the LMPT model to extend its application from hydrated bimolecular complexes to hydrogen bonded bimolecular complexes with donors such as alcohols, amines and acids. We have applied the modified model to a series of complexes of different hydrogen bond type and complex energy. We found that the differences between local mode (LM) and LMPT calculated fundamental XH-stretching transition wavenumbers and oscillator strengths were correlated with the strength of the hydrogen bond. Overall, we have found that the LMPT model in most cases predicts transition wavenumbers within 20 cm-1 of the experimental values.
Wing, Waylin J.; Sadeghi, Seyed M.; Gutha, Rithvik R.
2016-12-01
We experimentally investigate plasmonic lattice modes of gold nanoantenna arrays that occur in asymmetric structures containing a silica substrate and either air or a thin layer of a high-index dielectric. Very distinct polarization switching is observed in the nanoantenna arrays wherein by rotating the incident light polarization by ninety degrees, the array can exhibit either a plasmonic lattice mode or a multipolar localized surface plasmon resonance of varying nature. A large range of nanoantenna lengths are studied, and since the length of the nanoantennas dictates the multipolar localized surface plasmon resonance, we find that the characteristics of the polarization switching are affected accordingly. We also investigate how the thin layer of the high-index dielectric on top of the nanoantenna arrays, in conjunction with varying nanoantenna length, impacts the generation of plasmonic lattice modes and the polarization switching in the arrays. The high-index dielectric is found to assist in the generation and optical coupling of the plasmonic lattice modes. By altering the angle of incidence, the polarization switching can become very large, and the arrays can be made to selectively transmit light of certain wavelengths.
Singh, Bipin K.; Pandey, Praveen C.
2014-06-01
In this paper, we present an analytical study on the reflection properties of light through one-dimensional (1-D) quasi-periodic multilayer structures. The considered structures are as follows: F7, F8, F9, (F2)10, (F3)10 and some combinations such as: [(F2)10 (F7) (F2)10], [(F2)10 (F8) (F2)10], [(F3)10 (F7) (F3)10], [(F3)10 (F8) (F3)10], [(F2)10(F3)10], [(F2)10 (F7) (F3)10] and [(F2)10 (F8) (F3)10], where (Fj)n represents n period of the Fibonacci sequence of jth generation. These multilayer structures are considered of two types of layers. One type of layer is considered of graded material like normal, linear or exponential graded material, and the second type of layer is considered of constant refractive index material. Transfer matrix method is utilized to calculate the reflection spectra and localization modes of such structures in the frequency range 150-450 THz. This work would provide the basis of understanding of the effect of graded materials on the reflection and localization modes in Fibonacci photonic quasicrystal structures and obtained spectra can be used in the recognition of grading of materials. The considered heterostructures provide the broad reflection band and some localization modes in the calculated region.
Energy Technology Data Exchange (ETDEWEB)
Budny, R.V.; Alper, B.; Borba, D.; Cordey, J.G.; Ernst, D.R.; Gowers, C. [and others
2001-02-02
First results of gyrokinetic analysis of JET [Joint European Torus] ELMy [Edge Localized Modes] H-mode [high-confinement modes] plasmas are presented. ELMy H-mode plasmas form the basis of conservative performance predictions for tokamak reactors of the size of ITER [International Thermonuclear Experimental Reactor]. Relatively high performance for long duration has been achieved and the scaling appears to be favorable. It will be necessary to sustain low Z(subscript eff) and high density for high fusion yield. This paper studies the degradation in confinement and increase in the anomalous heat transport observed in two JET plasmas: one with an intense gas puff and the other with a spontaneous transition between Type I to III ELMs at the heating power threshold. Linear gyrokinetic analysis gives the growth rate, gamma(subscript lin) of the fastest growing modes. The flow-shearing rate omega(subscript ExB) and gamma(subscript lin) are large near the top of the pedestal. Their ratio decreases approximately when the confinement degrades and the transport increases. This suggests that tokamak reactors may require intense toroidal or poloidal torque input to maintain sufficiently high |gamma(subscript ExB)|/gamma(subscript lin) near the top of the pedestal for high confinement.
Energy Technology Data Exchange (ETDEWEB)
Maingi, R [PPPL
2014-07-01
Large edge localized modes (ELMs) typically accompany good H-mode confinement in fusion devices, but can present problems for plasma facing components because of high transient heat loads. Here the range of techniques for ELM control deployed in fusion devices is reviewed. The two baseline strategies in the ITER baseline design are emphasized: rapid ELM triggering and peak heat flux control via pellet injection, and the use of magnetic perturbations to suppress or mitigate ELMs. While both of these techniques are moderately well developed, with reasonable physical bases for projecting to ITER, differing observations between multiple devices are also discussed to highlight the needed community R & D. In addition, recent progress in ELM-free regimes, namely Quiescent H-mode, I-mode, and Enhanced Pedestal H-mode is reviewed, and open questions for extrapolability are discussed. Finally progress and outstanding issues in alternate ELM control techniques are reviewed: supersonic molecular beam injection, edge electron cyclotron heating, lower hybrid heating and/or current drive, controlled periodic jogs of the vertical centroid position, ELM pace-making via periodic magnetic perturbations, ELM elimination with lithium wall conditioning, and naturally occurring small ELM regimes.
Copperman, J; Guenza, M G
2015-07-23
We utilize a multiscale approach where molecular dynamic simulations are performed to obtain quantitative structural averages used as input to a coarse-grained Langevin equation for protein dynamics, which can be solved analytically. The approach describes proteins as fundamentally semiflexible objects collapsed into the free energy well representing the folded state. The normal-mode analytical solution to this Langevin equation naturally separates into global modes describing the fully anisotropic tumbling of the macromolecule as a whole and internal modes which describe local fluctuations about the folded structure. Complexity in the configurational free-energy landscape of the macromolecule leads to a renormalization of the internal modes, while the global modes provide a basis set in which the dipolar orientation and global anisotropy can be accounted for when comparing to experiments. This simple approach predicts the dynamics of both global rotational diffusion and internal motion from the picosecond to the nanosecond regime and is quantitative when compared to time correlation functions calculated from molecular dynamic simulations and in good agreement with nuclear magnetic resonance relaxation experiments. Fundamental to this approach is the inclusion of internal dissipation, which is absent in any rigid-body hydrodynamical modeling scheme.
Maingi, R.
2014-11-01
Large edge localized modes (ELMs) typically accompany good H-mode confinement in fusion devices, but can present problems for plasma facing components because of high transient heat loads. Here the range of techniques for ELM control deployed in fusion devices is reviewed. Two strategies in the ITER baseline design are emphasized: rapid ELM triggering and peak heat flux control via pellet injection, and the use of magnetic perturbations to suppress or mitigate ELMs. While both of these techniques are moderately well developed, with reasonable physical bases for projecting to ITER, differing observations between multiple devices are also discussed to highlight the needed community R&D. In addition, recent progress in ELM-free regimes, namely quiescent H-mode, I-mode, and enhanced pedestal H-mode is reviewed, and open questions for extrapolability are discussed. Finally progress and outstanding issues in alternate ELM control techniques are reviewed: supersonic molecular beam injection, edge electron cyclotron heating, lower hybrid heating and/or current drive, controlled periodic jogs of the vertical centroid position, ELM pace-making via periodic magnetic perturbations, ELM elimination with lithium wall conditioning, and naturally occurring small ELM regimes.
Thomas, Jens; Becker, Ria G; Marshall, Graham D; Withford, Michael J; Tünnermann, Andreas; Nolte, Stefan; Steel, M J
2010-01-01
The spectral characteristics of a fiber Bragg grating (FBG) with a transversely inhomogeneous refractive index profile, differs con- siderably from that of a transversely uniform one. Transmission spectra of inhomogeneous and asymmetric FBGs that have been inscribed with focused ultrashort pulses with the so-called point-by-point technique are investigated. The cladding mode resonances of such FBGs can span a full octave in the spectrum and are very pronounced (deeper than 20dB). Using a coupled-mode approach, we compute the strength of resonant coupling and find that coupling into cladding modes of higher azimuthal order is very sensitive to the position of the modification in the core. Exploiting these properties allows precise control of such reflections and may lead to many new sensing applications.
Picosecond infrared studies of H$^{-}$ local modes in LaF$_{3}$
Wells, J P R; Bradley, I V; Pidgeon, C R
2001-01-01
Three-beam normalised pump-probe measurements for the Z-localised vibrational mode of H/sup -/ in LaF/sub 3/ yield a 10 K population decay time (T/sub 1/) of 49 ps. The temperature decrease of this T /sub 1/ time is fitted to two-phonon anharmonic decay together with one-phonon absorption to the 351 cm/sup -1/ higher (X, Y)-mode. Two- pulse vibrational echo measurements yield a homogeneous line width of 0.3 cm/sup -1/. (8 refs).
Structural Damage Localization by Outlier Analysis of Signal-processed Mode Shapes
DEFF Research Database (Denmark)
Ulriksen, Martin Dalgaard; Damkilde, Lars
2016-01-01
analysis is conducted by applying the Mahalanobis metric to major principal scores of the sensor-located bands of the signal-processed mode shape. The method is tested analytically on the basis of a free-vibrating beam and experimentally in the context of a residential-sized wind turbine blade subjected...
Quasinormal Modes of Charged Black Holes Localized in the Randall-Sundrum Brane World
Soleimani, M J; Radiman, Shahidan; Abdullah, W A T Wan
2016-01-01
We study the quasinormal modes of the massless scalar field of charged black holes embedded in the Randal-Sundrum brane world using the third order WKB approximation. We consider the effects of the electromagnetic and tidal charges on quasinormal frequencies spectrum for charged black hole black holes as well as the effect of the thickness of the bulk.
The relation between morphology, accretion modes and environmental factors in local radio AGN
Gendre, Melanie A; Wall, J V; Ker, L M
2013-01-01
The goal of this work is to determine the nature of the relation between morphology and accretion mode in radio galaxies, including environmental parameters. The CoNFIG extended catalogue (improved by new Ks-band identifications and estimated redshifts from UKIDSS, and spectral index measurements from new GMRT observations) is used to select a sub-sample of 206 radio galaxies with z<0.3 over a wide range of radio luminosity, which are morphology-classified using the Fanaroff-Riley (FR) classification of extended radio sources. For each galaxy, spectroscopic data are retrieved to determine the high/low excitation status of the source, related to its accretion mode. Environmental factors, such as the host galaxy luminosity and a richness factor are also computed, generally using SDSS data.
Fountaine, Katherine T; Kendall, Christian G; Atwater, Harry A
2014-05-05
We report design methods for achieving near-unity broadband light absorption in sparse nanowire arrays, illustrated by results for visible absorption in GaAs nanowires on Si substrates. Sparse (unity absorption at wire resonant wavelengths due to coupling into 'leaky' radial waveguide modes of individual wires and wire-wire scattering processes. From a detailed conceptual development of radial mode resonant absorption, we demonstrate two specific geometric design approaches to achieve near unity broadband light absorption in sparse nanowire arrays: (i) introducing multiple wire radii within a small unit cell array to increase the number of resonant wavelengths, yielding a 15% absorption enhancement relative to a uniform nanowire array and (ii) tapering of nanowires to introduce a continuum of diameters and thus resonant wavelengths excited within a single wire, yielding an 18% absorption enhancement over a uniform nanowire array.
Giant Goos-Hänchen shift in scattering: the role of interfering localized plasmon modes
Soni, J.; Mansha, S.; Dutta Gupta, S.; Banerjee, A.; Ghosh, N.
2014-07-01
The longitudinal and the transverse beam shifts, namely, the Goos-H\\"anchen (GH) and the Spin-Hall (SH) shifts are usually observed at planar interfaces. It has recently been shown that the transverse SH shift may also arise due to scattering of plane waves. Here, we show that analogous in-plane (longitudinal) shift also exist in scattering of plane waves from micro/nano systems. We study both the GH and the SH shifts in plasmonic metal nanoparticles/ nanostructures and dielectric micro-particles employing a unified framework that utilizes the transverse components of the Poynting vector of the scattered wave. The results demonstrate that interference of neighboring resonance modes in plasmonic nanostructures (e.g., electric dipolar and quadrupolar modes in metal spheres) leads to giant enhancement of GH shift in scattering from such systems. We also unravel interesting correlations between these shifts with the polarimetry parameters, diattenuation and retardance.
Giant Goos-H\\"anchen shift in Scattering: the role of interfering Localized Plasmon modes
Soni, J; Gupta, S Dutta; Banerjee, A; Ghosh, N
2014-01-01
The longitudinal and the transverse beam shifts, namely, the Goos-H\\"anchen (GH) and the Spin-Hall (SH) shifts are usually observed at planar interfaces. It has recently been shown that the transverse SH shift may also arise due to scattering of plane waves. Here, we show that analogous in-plane (longitudinal) shift also exist in scattering of plane waves from micro/nano systems. We study both the GH and the SH shifts in plasmonic metal nanoparticles/ nanostructures and dielectric micro-particles employing a unified framework that utilizes the transverse components of the Poynting vector of the scattered wave. The results demonstrate that interference of neighboring resonance modes in plasmonic nanostructures (e.g., electric dipolar and quadrupolar modes in metal spheres) leads to giant enhancement of GH shift in scattering from such systems. We also unravel interesting correlations between these shifts with the polarimetry parameters, diattenuation and retardance.
Cuevas, Mauro; Riso, Máximo A.; Depine, Ricardo A.
2016-04-01
In this work we study the modal characteristics of localized surface plasmons in graphene-coated, circular cross-section wires. Localized surface plasmons are represented in terms of cylindrical multipole partial waves characterized by discrete, complex frequencies that depend on the size of the wire and can be dynamically tuned via a gate voltage. We consider both intrinsically nonplasmonic wires and intrinsically plasmonic wires. In the first case the localized surface plasmons are introduced by the graphene coating, whereas in the second case the localized eigenmodes of the graphene coating are expected to hybridize those already existing in the bare wire. We show that the approach presented here, valid for particle sizes where the retardation effects can be significant, is in good agreement with analytical expressions obtained in the limit when particle size is very small compared to the wavelength of the eigenmode and with results indirectly determined from scattering cross-section spectra.
Localized surface plasmon modes in a system of two interacting metallic cylinders
DEFF Research Database (Denmark)
Babicheva, Viktoriia; Vergeles, Sergey S.; Vorobev, Petr E.
2012-01-01
of geometrical characteristics of the system and Ohmic losses in the metal. The results of numerical simulations were systematically compared with the analytical theory, obtained in the quasi-static limit. The analytical method was generalized in order to take into account the retardation effects. We also...... present the physical qualitative picture of the plasmon modes, which is validated by numerical simulations and analytical theory....
The dynamics and structure of edge-localized-modes in Alcator C-Mod
Energy Technology Data Exchange (ETDEWEB)
Terry, J.L. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States)]. E-mail: terry@psfc.mit.edu; Cziegler, I. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); Hubbard, A.E. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); Snipes, J.A. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); Hughes, J.W. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); Greenwald, M.J. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); LaBombard, B. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); Lin, Y. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States); Phillips, P. [Fusion Research Center, University of Texas-Austin, Austin, TX 78712 (United States); Wukitch, S. [Plasma Science and Fusion Center, MIT, 175 Albany St., Cambridge, MA 02139 (United States)
2007-06-15
Characteristics of discrete ELMs produced in Alcator C-Mod discharges of low edge collisionality (0.2 < {nu} {sup *} < 1) and large lower triangularity ({delta} {sub lower} {approx} 0.75) are examined. The energy lost per ELM from the H-mode pedestal is {approx}10% of the pedestal energy. These ELMs exhibit relatively long-lived precursor oscillations, often with two modes of intermediate toroidal mode number present. At the ELM 'crash' multiple plasma filament structures are expelled into the scrape-off-layer. A short-lived high frequency ({approx}0.5 MHz) magnetic oscillation is initiated at the 'crash'. The initial ELM filaments are large perturbations to the SOL with radial extents of 0.5-1 cm and typical radial propagation velocities of 1 km/s. Velocities of up to 8 km/s have been seen. The poloidal extent of the initial filaments is >4.5 cm. The initial filaments are followed (at intervals of {approx}100 {mu}s) by multiple, less perturbing secondary filaments.
Energy Technology Data Exchange (ETDEWEB)
Sommer, F; Guenter, S; Kallenbach, A; Maraschek, M; Boom, J; Fischer, R; Hicks, N; Reiter, B; Wolfrum, E [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching, EURATOM Association (Germany); Luhmann, N C Jr [University of California at Davis, Davis, CA 95616 (United States); Park, H K [POSTECH, Pahang, Gyeongbuk 790-784 (Korea, Republic of); Wenninger, R, E-mail: fabian.sommer@ipp.mpg.de [Universitaetssternwarte der Ludwig-Maximilians-Universitaet, D-81679 Muenchen (Germany)
2011-08-15
A new magnetohydrodynamic instability called the 'Edge Snake', which was found in 2006 at the tokamak ASDEX Upgrade during type-I ELMy H-modes, is investigated. It is located within the separatrix in the region of high temperature and density gradients and has a toroidal mode number of n = 1. The Edge Snake consists of a radially and poloidally strongly localized current wire, in which the temperature and density profiles flatten. This significant reduction in pressure gradient leads to a reduction in the neoclassical Bootstrap current and can plausibly explain the drive of the instability. The experimental observations point towards a magnetic island with a defect current inside the O-point of the island. The Edge Snake is compared with similar instabilities at JET, DIII-D and ASDEX Upgrade.
de Albuquerque, S. S.; dos Santos, J. L. L.; de Moura, F. A. B. F.; Lyra, M. L.
2015-05-01
In this work, we study the vibrational modes and energy spreading in a harmonic chain model with diluted second-neighbors couplings and correlated mass-spring disorder. While all nearest neighbor masses are coupled by an elastic spring, second neighbors springs are introduced with a probability pD. The masses are randomly distributed according to the site connectivity m_i=m_0≤ft(1+1/n_iα\\right) , where ni is the connectivity of the site i and α is a tunable exponent. We show that maximum localization of the vibrational modes is achieved for α ≃ 3/4. The time-evolution of the energy wave-packet is followed after an initial localized excitation. While the participation number remains finite, the energy spread is shown to be sub-diffusive after a displacement and super-diffusive after an impulse excitation. These features are related to the development of a power-law tail in the wave-packet distribution. Further, we unveil that the spring dilution leads to the emergence of a resonant localized state which is signaled by a van Hove singularity in the density of states.
Energy Technology Data Exchange (ETDEWEB)
Bai, Xiao-Dong; Ai, Qing; Zhang, Mei; Xiong, Jun, E-mail: junxiong@bnu.edu.cn; Yang, Guo-Jian; Deng, Fu-Guo
2015-09-15
We investigate the stability and phase transition of localized modes in Bose–Einstein Condensates (BECs) in an optical lattice with the discrete nonlinear Schrödinger model by considering both two- and three-body interactions. We find that there are three types of localized modes, bright discrete breather (DB), discrete kink (DK), and multi-breather (MUB). Moreover, both two- and three-body on-site repulsive interactions can stabilize DB, while on-site attractive three-body interactions destabilize it. There is a critical value for the three-body interaction with which both DK and MUB become the most stable ones. We give analytically the energy thresholds for the destabilization of localized states and find that they are unstable (stable) when the total energy of the system is higher (lower) than the thresholds. The stability and dynamics characters of DB and MUB are general for extended lattice systems. Our result is useful for the blocking, filtering, and transfer of the norm in nonlinear lattices for BECs with both two- and three-body interactions.
The mode branching route to localization of the finite-length floating elastica
Rivetti, Marco; Neukirch, Sébastien
2014-09-01
The beam on elastic foundation is a general model used in physical, biological, and technological problems to study delamination, wrinkling, or pattern formation. Recent focus has been given to the buckling of beams deposited on liquid baths, and in the regime where the beam is soft compared to hydrostatic forces the wrinkling pattern observed at buckling has been shown to lead to localization of the deformation when the confinement is increased. Here we perform a global study of the general case where the intensity of the liquid foundation and the confinement are both varied. We compute equilibrium and stability of the solutions and unravel secondary bifurcations that play a major role in the route to localization. Moreover we classify the post-buckling solutions and shed light on the mechanism leading to localization. Finally, using an asymptotic technique imported from fluid mechanics, we derive an approximated analytical solution to the problem.
Sheppard, Colin J R; Saari, Peeter
2008-01-07
A criticism of the focus wave mode (FWM) solution for localized pulses is that it contains backward propagating components that are difficult to generate in many practical situations. We describe a form of FWM where the strength of the backward propagating components is identically zero and derive special cases where the field can be written in an analytic form. In particular, a free-space version of "backward light" pulse is considered, which moves in the opposite direction with respect to all its spectral constituents.
Resistive reduced MHD modeling of multi-edge-localized-mode cycles in Tokamak X-point plasmas.
Orain, F; Bécoulet, M; Huijsmans, G T A; Dif-Pradalier, G; Hoelzl, M; Morales, J; Garbet, X; Nardon, E; Pamela, S; Passeron, C; Latu, G; Fil, A; Cahyna, P
2015-01-23
The full dynamics of a multi-edge-localized-mode (ELM) cycle is modeled for the first time in realistic tokamak X-point geometry with the nonlinear reduced MHD code jorek. The diamagnetic rotation is found to be instrumental to stabilize the plasma after an ELM crash and to model the cyclic reconstruction and collapse of the plasma pressure profile. ELM relaxations are cyclically initiated each time the pedestal gradient crosses a triggering threshold. Diamagnetic drifts are also found to yield a near-symmetric ELM power deposition on the inner and outer divertor target plates, consistent with experimental measurements.
Localization of MHD modes and consistency with q-profiles in JET
Energy Technology Data Exchange (ETDEWEB)
De Angelis, R., E-mail: riccardo.deangelis@enea.i [Associazione Euratom/ENEA sulla Fusione, CP 65-00044 Frascati, Rome (Italy); Baruzzo, M. [Consorzio RFX, EURATOM-ENEA Association, Corso Stati Uniti 4, 35127 Padova (Italy); Buratti, P. [Associazione Euratom/ENEA sulla Fusione, CP 65-00044 Frascati, Rome (Italy); Alper, B. [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Barrera, L. [Laboratorio Nacional de Fusion, Asociacion EURATOM-CIEMAT, 28040 Madrid (Spain); Botrugno, A. [Associazione Euratom/ENEA sulla Fusione, CP 65-00044 Frascati, Rome (Italy); Brix, M. [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Figini, L. [Istituto di Fisica del Plasma, Associazione EURATOM ENEA-CNR, Milano (Italy); Fonseca, A. [Associacao Euratom-IST, Centro de Fusao Nuclear, Av. Rovisco Pais, Lisbon (Portugal); Giroud, C.; Hawkes, N.; Howell, D. [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); De La Luna, E. [Laboratorio Nacional de Fusion, Asociacion EURATOM-CIEMAT, 28040 Madrid (Spain); Orsitto, F.; Pericoli, V. [Associazione Euratom/ENEA sulla Fusione, CP 65-00044 Frascati, Rome (Italy); Rachlew, E. [Association EURATOM-VR, KTH Royal Inst. of Technology, SE-10691 Stockholm (Sweden); Tudisco, O. [Associazione Euratom/ENEA sulla Fusione, CP 65-00044 Frascati, Rome (Italy)
2010-11-11
The measurement of the safety factor q in tokamaks, which describes the winding of the helical magnetic field lines, is very important especially for the achievement of advanced scenarios. The motional Stark effect diagnostic can provide a direct measurement of the magnetic field orientation but the derivation of the q-profiles requires a simulation of the magnetic equilibrium taking into account inputs from several other diagnostics. This analysis can be affected by large errors. In order to validate the results, q-profiles are compared with the radii of MHD modes, which can be attributed to surfaces of known q.
Localization of MHD modes and consistency with q-profiles in JET
De Angelis, R.; Baruzzo, M.; Buratti, P.; Alper, B.; Barrera, L.; Botrugno, A.; Brix, M.; Figini, L.; Fonseca, A.; Giroud, C.; Hawkes, N.; Howell, D.; De La Luna, E.; Orsitto, F.; Pericoli, V.; Rachlew, E.; Tudisco, O.; JET-EFDA Contributors
2010-11-01
The measurement of the safety factor q in tokamaks, which describes the winding of the helical magnetic field lines, is very important especially for the achievement of advanced scenarios. The motional Stark effect diagnostic can provide a direct measurement of the magnetic field orientation but the derivation of the q-profiles requires a simulation of the magnetic equilibrium taking into account inputs from several other diagnostics. This analysis can be affected by large errors. In order to validate the results, q-profiles are compared with the radii of MHD modes, which can be attributed to surfaces of known q.
Feasibility of A-mode ultrasound attenuation as a monitoring method of local hyperthermia treatment.
Manaf, Noraida Abd; Aziz, Maizatul Nadwa Che; Ridzuan, Dzulfadhli Saffuan; Mohamad Salim, Maheza Irna; Wahab, Asnida Abd; Lai, Khin Wee; Hum, Yan Chai
2016-06-01
Recently, there is an increasing interest in the use of local hyperthermia treatment for a variety of clinical applications. The desired therapeutic outcome in local hyperthermia treatment is achieved by raising the local temperature to surpass the tissue coagulation threshold, resulting in tissue necrosis. In oncology, local hyperthermia is used as an effective way to destroy cancerous tissues and is said to have the potential to replace conventional treatment regime like surgery, chemotherapy or radiotherapy. However, the inability to closely monitor temperature elevations from hyperthermia treatment in real time with high accuracy continues to limit its clinical applicability. Local hyperthermia treatment requires real-time monitoring system to observe the progression of the destroyed tissue during and after the treatment. Ultrasound is one of the modalities that have great potential for local hyperthermia monitoring, as it is non-ionizing, convenient and has relatively simple signal processing requirement compared to magnetic resonance imaging and computed tomography. In a two-dimensional ultrasound imaging system, changes in tissue microstructure during local hyperthermia treatment are observed in terms of pixel value analysis extracted from the ultrasound image itself. Although 2D ultrasound has shown to be the most widely used system for monitoring hyperthermia in ultrasound imaging family, 1D ultrasound on the other hand could offer a real-time monitoring and the method enables quantitative measurement to be conducted faster and with simpler measurement instrument. Therefore, this paper proposes a new local hyperthermia monitoring method that is based on one-dimensional ultrasound. Specifically, the study investigates the effect of ultrasound attenuation in normal and pathological breast tissue when the temperature in tissue is varied between 37 and 65 °C during local hyperthermia treatment. Besides that, the total protein content measurement was also
Local measurement of error field using naturally rotating tearing mode dynamics in EXTRAP T2R
Sweeney, R M; Brunsell, P; Fridström, R; Volpe, F A
2016-01-01
An error field (EF) detection technique using the amplitude modulation of a naturally rotating tearing mode (TM) is developed and validated in the EXTRAP T2R reversed field pinch. The technique was used to identify intrinsic EFs of $m/n = 1/-12$, where $m$ and $n$ are the poloidal and toroidal mode numbers. The effect of the EF and of a resonant magnetic perturbation (RMP) on the TM, in particular on amplitude modulation, is modeled with a first-order solution of the Modified Rutherford Equation. In the experiment, the TM amplitude is measured as a function of the toroidal angle as the TM rotates rapidly in the presence of an unknown EF and a known, deliberately applied RMP. The RMP amplitude is fixed while the toroidal phase is varied from one discharge to the other, completing a full toroidal scan. Using three such scans with different RMP amplitudes, the EF amplitude and phase are inferred from the phases at which the TM amplitude maximizes. The estimated EF amplitude is consistent with other estimates (e....
Local measurement of error field using naturally rotating tearing mode dynamics in EXTRAP T2R
Sweeney, R. M.; Frassinetti, L.; Brunsell, P.; Fridström, R.; Volpe, F. A.
2016-12-01
An error field (EF) detection technique using the amplitude modulation of a naturally rotating tearing mode (TM) is developed and validated in the EXTRAP T2R reversed field pinch. The technique was used to identify intrinsic EFs of m/n = 1/-12, where m and n are the poloidal and toroidal mode numbers. The effect of the EF and of a resonant magnetic perturbation (RMP) on the TM, in particular on amplitude modulation, is modeled with a first-order solution of the modified Rutherford equation. In the experiment, the TM amplitude is measured as a function of the toroidal angle as the TM rotates rapidly in the presence of an unknown EF and a known, deliberately applied RMP. The RMP amplitude is fixed while the toroidal phase is varied from one discharge to the other, completing a full toroidal scan. Using three such scans with different RMP amplitudes, the EF amplitude and phase are inferred from the phases at which the TM amplitude maximizes. The estimated EF amplitude is consistent with other estimates (e.g. based on the best EF-cancelling RMP, resulting in the fastest TM rotation). A passive variant of this technique is also presented, where no RMPs are applied, and the EF phase is deduced.
Naumov, A. V.; Vainer, Yu. G.; Bauer, M.; Kador, L.
2004-12-01
By means of single molecule (SM) spectroscopy we investigated elementary matrix excitations in a disordered solid, i.e., quasi-localized low-frequency vibrational modes (LFMs). To this end we recorded the spectra of single tetra-tert-butylterrylene molecules embedded in an amorphous polyisobutylene matrix in a temperature region, where the LFM contribution to line broadening dominates. The individual param- eters of LFMs in a polymer glass can be determined from the temperature-dependent linewidths of single molecules. The magnitude of the LFM contribution to SM spectra was obtained by the statistical analysis of the distribution of linewidths of SMs. Pronounced distributions of LFM frequencies and SM-LFM coupling constants were found. This result can be regarded as the first direct experimental proof of the localized nature of LFMs.
Energy Technology Data Exchange (ETDEWEB)
Tangyunyong, Paiboon; Miller, Mary A.; Cole, Edward Isaac, Jr.
2012-03-01
We present the results of a two-year early career LDRD that focused on defect localization in deep green and deep ultraviolet (UV) light-emitting diodes (LEDs). We describe the laser-based techniques (TIVA/LIVA) used to localize the defects and interpret data acquired. We also describe a defect screening method based on a quick electrical measurement to determine whether defects should be present in the LEDs. We then describe the stress conditions that caused the devices to fail and how the TIVA/LIVA techniques were used to monitor the defect signals as the devices degraded and failed. We also describe the correlation between the initial defects and final degraded or failed state of the devices. Finally we show characterization results of the devices in the failed conditions and present preliminary theories as to why the devices failed for both the InGaN (green) and AlGaN (UV) LEDs.
Mahmoudi, S.; Trivaudey, F.; Bouhaddi, N.
2015-07-01
The aim of this study is the prediction of the dynamic response of damaged laminated composite structures in the context of component mode synthesis. Hence, a method of damage localization of complex structures is proposed. The dynamic behavior of transversely isotropic layers is expressed through elasticity coupled with damage based on an existing macro model for cracked structures. The damage is located only in some regions of the whole structure, which is decomposed on substructures. The incremental linear dynamic governing equations are obtained by using the classical linear Kirchhoff-Love theory of plates. Then, considering the damage-induced nonlinearity, the obtained nonlinear dynamic equations are solved in time domain. However, a detailed finite element modelling of such structure on the scale of localized damage would generate very high computational costs. To reduce this cost, Component Mode Synthesis method (CMS) is used for modelling a nonlinear fine-scale substructure damaged, connected to linear dynamic models of the remaining substructures, which can be condensed and not updated at each iteration. Numerical results show that the mechanical properties of the structure highly change when damage is taken into account. Under an impact load, damage increases and reaches its highest value with the maximum of the applied load and then remains unchanged. Besides, the eigenfrequencies of the damaged structure decrease comparing with those of an undamaged one. This methodology can be used for monitoring strategies and lifetime estimations of hybrid complex structures due to the damage state is known in space and time.
Energy Technology Data Exchange (ETDEWEB)
Chung, K.S., E-mail: alsk3@snu.ac.kr; Chung, Kyoung-Jae, E-mail: jkjlsh1@snu.ac.kr; Jung, B.K.; Hwang, Y.S., E-mail: yhwang@snu.ac.kr
2013-10-15
Highlights: • A small plasma gun is constructed to study edge localized mode. • A plasma jet ejected from the gun is characterized with a quadruple Langmuir probe. • The device and diagnostics are suitable for research about the control of plasma jet. -- Abstract: A small plasma gun with parallel-plate configuration is fabricated to generate a bunch of plasma which is similar to ELM (edge localized mode) plasma, by taking advantages of its simplicity and cost-effectiveness. Prior to explore how to control the ELM-like plasma so as to relieve heat load on the divertor target, characteristics of a plasma jet ejected from the plasma gun are investigated using a quadruple Langmuir probe which is appropriate for measuring rapidly varying plasma parameters such as electron density, temperature, and ion velocity at the same time. The plasma density and ion velocity measured at 112 mm away from the exit are 3 × 10{sup 19} m{sup −3} and 11 km/s, respectively, which seem to be suitable for investigating next step research on the control of ELM-like plasma using various methods such as electromagnetic waves and high-voltage pulses. Also, the quadruple Langmuir probe is proven to be adequate for use in such experiments.
Institute of Scientific and Technical Information of China (English)
2012-01-01
In the past decade, the transfer of development rights (referred to TDR hereafter) has been emerged and developed to a large scale amid China’s fast urbanization. Different from the practices in countries with private land ownership like the United States, the practices of TDR in China are still dominated by local governments, which are trying hard to obtain extra construction land-use quota under China’s current centralized land management system since the late 1990s. In this process, the land-use efficiency may be improved at the prices of social equity and harmony.
Nonlinear localized flat-band modes with spin-orbit coupling
Gligorić, G.; Maluckov, A.; Hadžievski, Lj.; Flach, Sergej; Malomed, Boris A.
2016-10-01
We report the coexistence and properties of stable compact localized states (CLSs) and discrete solitons (DSs) for nonlinear spinor waves on a flat-band network with spin-orbit coupling (SOC). The system can be implemented by means of a binary Bose-Einstein condensate loaded in the corresponding optical lattice. In the linear limit, the SOC opens a minigap between flat and dispersive bands in the system's band-gap structure, and preserves the existence of CLSs at the flat-band frequency, simultaneously lowering their symmetry. Adding on-site cubic nonlinearity, the CLSs persist and remain available in an exact analytical form, with frequencies that are smoothly tuned into the minigap. Inside of the minigap, the CLS and DS families are stable in narrow areas adjacent to the FB. Deep inside the semi-infinite gap, both the CLSs and DSs are stable too.
Local Structure Evolution and Modes of Charge Storage in Secondary Li–FeS _{2} Cells
Energy Technology Data Exchange (ETDEWEB)
Butala, Megan M.; Mayo, Martin; Doan-Nguyen, Vicky V. T.; Lumley, Margaret A.; Göbel, Claudia; Wiaderek, Kamila M.; Borkiewicz, Olaf J.; Chapman, Karena W.; Chupas, Peter J.; Balasubramanian, Mahalingam; Laurita, Geneva; Britto, Sylvia; Morris, Andrew J.; Grey, Clare P.; Seshadri, Ram
2017-03-27
In the pursuit of high-capacity electrochemical energy storage, a promising domain of research involves conversion reaction schemes, wherein electrode materials are fully transformed during charge and discharge. There are, however, numerous difficulties in realizing theoretical capacity and high rate capability in many conversion schemes. Here we employ operando studies to understand the conversion material FeS2, focusing on the local structure evolution of this relatively reversible material. X-ray absorption spectroscopy, pair distribution function analysis, and first-principles calculations of intermediate structures shed light on the mechanism of charge storage in the Li-FeS2 system, with some general principles emerging for charge storage in chalcogenide materials. Focusing on second and later charge/discharge cycles, we find small, disordered domains that locally resemble Fe and Li2S at the end of the first discharge. Upon charge, this is converted to a Li-Fe-S composition whose local structure reveals tetrahedrally coordinated Fe. With continued charge, this ternary composition displays insertion extraction behavior at higher potentials and lower Li content. The finding of hybrid modes of charge storage, rather than simple conversion, points to the important role of intermediates that appear to store charge by mechanisms that more closely resemble intercalation.
Guzdar, P. N.; Kleva, R. G.; Groebner, R. J.; Gohil, P.
2004-03-01
Shear flow stabilization of edge turbulence in tokamaks has been the accepted paradigm for the improvement in confinement observed in high (H) confinement mode plasmas. Results on the generation of zonal flow and fields in finite β plasmas are presented. This theory yields a criterion for bifurcation from low to high (L-H) confinement mode, proportional to Te/√Ln , where Te is the electron temperature and Ln is the density scale-length at the steepest part of the density gradient. When this parameter exceeds a critical value (mostly determined by the strength of the toroidal magnetic field), the transition occurs. The predicted threshold based on this parameter shows good agreement with edge measurements on discharges undergoing L-H transitions in DIII-D [J. L. Luxon, R. Anderson, F. Batty et al., in Proceedings of the 11th Conference on Plasma Physics and Controlled Fusion Research, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159]. The observed differences in the transitions with the reversal of the toroidal magnetic field are reconciled in terms of this critical parameter due to the differences in the density gradient scale-lengths in the edge. The theory also provides a possible explanation for lowered threshold power, pellet injection H modes in DIII-D, thereby providing a unified picture of the varied observations on the L-H transition.
Edge localized mode control using n = 1 resonant magnetic perturbation in the EAST tokamak
Sun, Y.; Jia, M.; Zang, Q.; Wang, L.; Liang, Y.; Liu, Y. Q.; Yang, X.; Guo, W.; Gu, S.; Li, Y.; Lyu, B.; Zhao, H.; Liu, Y.; Zhang, T.; Li, G.; Qian, J.; Xu, L.; Chu, N.; Wang, H. H.; Shi, T.; He, K.; Chen, D.; Shen, B.; Gong, X.; Ji, X.; Wang, S.; Qi, M.; Yuan, Q.; Sheng, Z.; Gao, G.; Song, Y.; Fu, P.; Wan, B.; Contributors, EAST
2017-03-01
A set of in-vessel resonant magnetic perturbation (RMP) coil has been recently installed in EAST. It can generate a range of spectrum, and there is a relatively large window for edge localized mode (ELM) control according to the vacuum field modeling of the edge magnetic island overlapping area. Observation of mitigation and suppression of ELM in slow rotating plasmas during the application of an n = 1 RMP is presented in this paper. Strong ELM mitigation effect is observed in neutral beam injection heating plasmas. The ELM frequency increases by a factor of 5, and the crash amplitude and the particle flux are effectively reduced by a similar factor. Clear density pump-out and magnetic braking effects are observed during the application of RMP. Footprint splitting is observed during ELM mitigation and agrees well with vacuum field modelling. Strong ELM mitigation happens after a second sudden drop of plasma density, which indicates the possible effect due to field penetration of the resonant harmonics near the pedestal top, where the electron perpendicular rotation becomes flat and close to zero after the application of RMP. ELM suppression is achieved in a resonant window during the scan of the n = 1 RMP spectrum in radio-frequency (RF) dominant heating plasmas. The best spectrum for ELM suppression is consistent with the resonant peak of RMP by taking into account of linear magnetohydrodynamics plasma response. There is no mode locking during the application of n = 1 RMP in ELMy H-mode plasmas, although the maximal coil current is applied.
de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst
2013-01-01
We present a numerical formalism for solving the Lippmann-Schwinger equation for the electric field in three dimensions. The formalism may be applied to scatterers of different shapes and embedded in different background media, and we develop it in detail for the specific case of spherical scatterers in a homogeneous background medium. In addition, we show how several physically important quantities may readily be calculated with the formalism. These quantities include the extinction cross section, the total Green's tensor, the projected local density of states and the Purcell factor as well as the quasinormal modes of leaky resonators with the associated resonance frequencies and quality factors. We demonstrate the calculations for the well-known plasmonic dimer consisting of two silver nanoparticles and thus illustrate the versatility of the formalism for use in modeling of advanced nanophotonic devices.
Sun, Y; Liang, Y; Liu, Y Q; Gu, S; Yang, X; Guo, W; Shi, T; Jia, M; Wang, L; Lyu, B; Zhou, C; Liu, A; Zang, Q; Liu, H; Chu, N; Wang, H H; Zhang, T; Qian, J; Xu, L; He, K; Chen, D; Shen, B; Gong, X; Ji, X; Wang, S; Qi, M; Song, Y; Yuan, Q; Sheng, Z; Gao, G; Fu, P; Wan, B
2016-09-01
Evidence of a nonlinear transition from mitigation to suppression of the edge localized mode (ELM) by using resonant magnetic perturbations (RMPs) in the EAST tokamak is presented. This is the first demonstration of ELM suppression with RMPs in slowly rotating plasmas with dominant radio-frequency wave heating. Changes of edge magnetic topology after the transition are indicated by a gradual phase shift in the plasma response field from a linear magneto hydro dynamics modeling result to a vacuum one and a sudden increase of three-dimensional particle flux to the divertor. The transition threshold depends on the spectrum of RMPs and plasma rotation as well as perturbation amplitude. This means that edge topological changes resulting from nonlinear plasma response plays a key role in the suppression of ELM with RMPs.
Sasaki, Kenya; Mitani, Yoshihiro; Fujita, Yusuke; Hamamoto, Yoshihiko; Sakaida, Isao
2017-02-01
In this paper, in order to classify liver cirrhosis on regions of interest (ROIs) images from B-mode ultrasound images, we have proposed to use the higher order local autocorrelation (HLAC) features. In a previous study, we tried to classify liver cirrhosis by using a Gabor filter based approach. However, the classification performance of the Gabor feature was poor from our preliminary experimental results. In order accurately to classify liver cirrhosis, we examined to use the HLAC features for liver cirrhosis classification. The experimental results show the effectiveness of HLAC features compared with the Gabor feature. Furthermore, by using a binary image made by an adaptive thresholding method, the classification performance of HLAC features has improved.
de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst; Mørk, Jesper; Gregersen, Niels
2015-12-15
We present and validate a semianalytical quasi-normal mode (QNM) theory for the local density of states (LDOS) in coupled photonic crystal (PhC) cavity-waveguide structures. By means of an expansion of the Green's function on one or a few QNMs, a closed-form expression for the LDOS is obtained, and for two types of two-dimensional PhCs, with one and two cavities side-coupled to an extended waveguide, the theory is validated against numerically exact computations. For the single cavity, a slightly asymmetric spectrum is found, which the QNM theory reproduces, and for two cavities, a nontrivial spectrum with a peak and a dip is found, which is reproduced only when including both the two relevant QNMs in the theory. In both cases, we find relative errors below 1% in the bandwidth of interest.
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Xu, X. Q., E-mail: xxu@llnl.gov [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Ma, J. F. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Institute for Fusion Studies, University of Texas, Austin, Texas 78712 (United States); Li, G. Q. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China)
2014-12-15
The latest BOUT++ studies show an emerging understanding of dynamics of edge localized mode (ELM) crashes and the consistent collisionality scaling of ELM energy losses with the world multi-tokamak database. A series of BOUT++ simulations are conducted to investigate the scaling characteristics of the ELM energy losses vs collisionality via a density scan. Linear results demonstrate that as the pedestal collisionality decreases, the growth rate of the peeling-ballooning modes decreases for high n but increases for low n (1 < n < 5), therefore the width of the growth rate spectrum γ(n) becomes narrower and the peak growth shifts to lower n. Nonlinear BOUT++ simulations show a two-stage process of ELM crash evolution of (i) initial bursts of pressure blob and void creation and (ii) inward void propagation. The inward void propagation stirs the top of pedestal plasma and yields an increasing ELM size with decreasing collisionality after a series of micro-bursts. The pedestal plasma density plays a major role in determining the ELM energy loss through its effect on the edge bootstrap current and ion diamagnetic stabilization. The critical trend emerges as a transition (1) linearly from ballooning-dominated states at high collisionality to peeling-dominated states at low collisionality with decreasing density and (2) nonlinearly from turbulence spreading dynamics at high collisionality into avalanche-like dynamics at low collisionality.
Ahmad, Javaid; Cheng, Shaohong; Ghrib, Faouzi
2016-02-01
Suppressing unfavorable stay cable vibrations using cross-ties is becoming more popular on cable-stayed bridges though the mechanics of the formed cable network is yet fully understood. In practice, the main task in designing cross-ties or cable networks is to choose the cross-tie installation location, stiffness and number based on the main cable properties in the network. To have a more comprehensive picture of how to choose these design parameters to achieve higher in-plane network stiffness while minimizing the number of excited local modes, it is imperative to examine dynamic behavior of cable networks with general configurations. In the current study, an analytical model of a general cable network consisting of multiple main cables interconnected by multiple lines of transverse flexible cross-ties will be developed. A new term, defined as the local mode cluster, will be introduced to assess the severity of local mode excitation. Criteria for identifying the presence of local mode cluster will be proposed. A parametric study will be conducted to evaluate the impact of cross-tie installation location, stiffness and number on the network modal response. Results obtained from the present study will provide deeper insight into the selection of these system parameters to achieve the combined benefits of increasing network in-plane stiffness and minimizing the excitation of local modes.
Bachelard, Nicolas; Sebbah, Patrick; Vanneste, Christian
2014-01-01
We use time-domain numerical simulations of a two-dimensional (2D) scattering system to study the interaction of a collection of emitters resonantly coupled to an Anderson-localized mode. For a small electric field intensity, we observe the strong coupling between the emitters and the mode, which is characterized by linear Rabi oscillations. Remarkably, a larger intensity induces non-linear interaction between the emitters and the mode, referred to as the dynamical Stark effect, resulting in non-linear Rabi oscillations. The transition between both regimes is observed and an analytical model is proposed which accurately describes our numerical observations.
Jo, Young Hyun; Lee, Hae June; Mikhailenko, Vladimir V.; Mikhailenko, Vladimir S.
2016-01-01
It was derived that the drift-Alfven instabilities with the shear flow parallel to the magnetic field have significant difference from the drift-Alfven instabilities of a shearless plasma when the ion temperature is comparable with electron temperature for a finite plasma beta. The velocity shear not only modifies the frequency and the growth rate of the known drift-Alfven instability, which develops due to the inverse electron Landau damping, but also triggers a combined effect of the velocity shear and the inverse ion Landau damping, which manifests the development of the ion kinetic shear-flow-driven drift-Alfven instability. The excited unstable waves have the phase velocities along the magnetic field comparable with the ion thermal velocity, and the growth rate is comparable with the frequency. The development of this instability may be the efficient mechanism of the ion energization in shear flows. The levels of the drift--Alfven turbulence, resulted from the development of both instabilities, are determined from the renormalized nonlinear dispersion equation, which accounts for the nonlinear effect of the scattering of ions by the electromagnetic turbulence. The renormalized quasilinear equation for the ion distribution function, which accounts for the same effect of the scattering of ions by electromagnetic turbulence, is derived and employed for the analysis of the ion viscosity and ions heating, resulted from the interactions of ions with drift-Alfven turbulence. In the same way, the phenomena of the ion cyclotron turbulence and anomalous anisotropic heating of ions by ion cyclotron plasma turbulence has numerous practical applications in physics of the near-Earth space plasmas. Using the methodology of the shearing modes, the kinetic theory of the ion cyclotron turbulence of the plasma with transverse current with strong velocity shear has been developed.
Cahyna, Pavel; Huijsmans, Guido T A; Orain, Francois; Morales, Jorge; Kirk, Andrew; Thornton, Andrew J; Pamela, Stanislas; Panek, Radomir; Hoelzl, Matthias
2016-01-01
Resonant magnetic perturbations (RMPs) can mitigate the edge-localized modes (ELMs), i.e. cause a change of the ELM character towards smaller energy loss and higher frequency. During mitigation a change of the spatial structure of ELM loads on divertor was observed on DIII-D and MAST: the power is deposited predominantly in the footprint structures formed by the magnetic perturbation. In the present contribution we develop a theory explaining this effect, based on the idea that part of the ELM loss is caused by parallel transport in the homoclinic tangle formed by the magnetic perturbation of the ELM. The modified tangle resulting from the combination of the ELM perturbation and the applied RMP has the expected property of bringing open field lines in the same areas as the tangle from the RMP alone. We show that this explanation is consistent with features of the mitigated ELMs on MAST. We in addition validated our theory by an analysis of simulations of mitigated ELMs using the code JOREK. We produced detail...
Zacharuk, Matthias; Stamen, Dolaptchiev; Ulrich, Achatz; Ilya, Timofeyev
2016-04-01
Due to the finite spatial resolution in numerical atmospheric models subgrid-scale (SGS) processes are excluded. A SGS parameterization of these excluded processes might improve the model on all scales. To parameterize the SGS processes we choose the MTV stochastic mode reduction (Majda, Timofeyev, Vanden-Eijnden 2001, A mathematical framework for stochastic climate models. Commun. Pure Appl. Math., 54:891-974). For this the model is separated into fast and slow processes. Using the statistics of the fast processes, a SGS parameterization is found. To identify fast processes the state vector of the model is separated into two state vectors. One vector is the average of the full model state vector in a coarse grid cell. The other describes SGS processes which are defined as the deviation of the full state vector from the coarse cell average. If the SGS vector decorrelates faster in time than the coarse grid vector, the interactions of SGS processes in the equation of the SGS processes are replaced by a local Ornstein-Uhlenbeck process. Afterwards the MTV SGS parameterization can be derived. This method was successfully applied on the Burgers-equation (Dolaptchiev et al. 2013, Stochastic closure for local averages in the finite-difference discretization of the forced Burgers equation. Theor. Comp. Fluid Dyn., 27:297-317). In this study we consider a more atmosphere like model and choose a model of the one dimensional shallow water equations (SWe). It will be shown, that the fine state vector decorrelates faster than the coarse state vector. Due to the non-polynomial form of the SWe in flux formulation an approximation of all 1/h (h = fluid depth) terms needs to be done, except of the interactions between coarse state vector to coarse state vector. It will be shown, that this approximation has only minor impact on the model results. In the following the model with the local Ornstein-Uhlenbeck process approximation of SGS interactions is analyzed and compared to the
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Yun, G. S.; Lee, W.; Choi, M. J.; Lee, J.; Park, H. K. [Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Domier, C. W.; Luhmann, N. C. Jr. [University of California at Davis, Davis, California 95616 (United States); Tobias, B. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Donne, A. J. H. [FOM-Institute for Plasma Physics Rijnhuizen, 3430 BE Nieuwegein (Netherlands); Einhoven University of Technology, 5600 MB Einhoven (Netherlands); Lee, J. H.; Jeon, Y. M.; Yoon, S. W. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Collaboration: KSTAR Team
2012-05-15
The temporal evolution of edge-localized modes (ELMs) has been studied using a 2-D electron cyclotron emission imaging system in the KSTAR tokamak. The ELMs are observed to evolve in three distinctive stages: the initial linear growth of multiple filamentary structures having a net poloidal rotation, the interim state of regularly spaced saturated filaments, and the final crash through a short transient phase characterized by abrupt changes in the relative amplitudes and distance among filaments. The crash phase, typically consisted of multiple bursts of a single filament, involves a complex dynamics, poloidal elongation of the bursting filament, development of a fingerlike bulge, and fast localized burst through the finger. Substantial alterations of the ELM dynamics, such as mode number, poloidal rotation, and crash time scale, have been observed under external magnetic perturbations with the toroidal mode number n= 1.
Dyer, Gregory C.; Aizin, Gregory R.; Allen, S. James; Grine, Albert D.; Bethke, Don; Reno, John L.; Shaner, Eric A.
2014-05-01
The device applications of plasmonic systems such as graphene and two dimensional electron gases (2DEGs) in III-V heterostructures include terahertz detectors, mixers, oscillators and modulators. These two dimensional (2D) plasmonic systems are not only well-suited for device integration, but also enable the broad tunability of underdamped plasma excitations via an applied electric field. We present demonstrations of the coherent coupling of multiple voltage tuned GaAs/AlGaAs 2D plasmonic resonators under terahertz irradiation. By utilizing a plasmonic homodyne mixing mechanism to downconvert the near field of plasma waves to a DC signal, we directly detect the spectrum of coupled plasmonic micro-resonator structures at cryogenic temperatures. The 2DEG in the studied devices can be interpreted as a plasmonic waveguide where multiple gate terminals control the 2DEG kinetic inductance. When the gate tuning of the 2DEG is spatially periodic, a one-dimensional finite plasmonic crystal forms. This results in a subwavelength structure, much like a metamaterial element, that nonetheless Bragg scatters plasma waves from a repeated crystal unit cell. A 50% in situ tuning of the plasmonic crystal band edges is observed. By introducing gate-controlled defects or simply terminating the lattice, localized states arise in the plasmonic crystal. Inherent asymmetries at the finite crystal boundaries produce an induced transparency-like phenomenon due to the coupling of defect modes and crystal surface states known as Tamm states. The demonstrated active control of coupled plasmonic resonators opens previously unexplored avenues for sensitive direct and heterodyne THz detection, planar metamaterials, and slow-light devices.
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Nardon, E
2007-10-15
The present work is dedicated to one of the most promising methods of control of the ELMs (Edge Localized Modes), based on a system of coils producing Resonant Magnetic Perturbations (RMPs). Our main objectives are, on the one hand, to improve the physical understanding of the mechanisms at play, and on the other hand to propose a concrete design of ELMs control coils for ITER. In order to calculate and analyze the magnetic perturbations produced by a given set of coils, we have developed the ERGOS code. The first ERGOS calculation was for the DIII-D ELMs control coils, the I-coils. It showed that they produce magnetic islands chains which overlap at the edge of the plasma, resulting in the ergodization of the magnetic field. We have then used ERGOS for the modelling of the experiments on ELMs control using the error field correction coils at JET and MAST. In the case of JET, we have shown the existence of a correlation between the mitigation of the ELMs and the ergodization of the magnetic field at the edge, in agreement with the DIII-D result. In order to design the ELMs control coils for ITER we have used ERGOS intensively, taking the case of the DIII-D I-coils as a reference. Three candidate designs came out, which we presented at the ITER Design Review, in 2007. Recently, the ITER management decided to provide a budget for building ELMs control coils, the design of which remains to be chosen between two of the three options that we proposed. Finally, in order to understand better the non-linear magnetohydrodynamics phenomena taking place in ELMs control by RMPs, we performed numerical simulations, in particular with the JOREK code for a DIII-D case. The simulations reveal the existence of convection cells induced at the edge by the magnetic perturbations, and the possible screening of the RMPs in presence of rotation.
Jobson, K.W.; Wells, J.P.R.; Schropp, R.E.I.; Vinh, N.Q.; Dijkhuis, J.I.
2008-01-01
We report on picosecond, time-resolved measurements of the vibrational relaxation and decay pathways of the Si–H and Ge–H stretching modes in hydrogenated amorphous silicon-germanium thin films (a-SiGe:H). It is demonstrated that the decay of both modes has a nonexponential shape, attributable to th
Jobson, K. W.; Wells, J. P. R.; Schropp, R. E. I.; Vinh, N. Q.; Dijkhuis, J. I.
2008-01-01
We report on picosecond, time-resolved measurements of the vibrational relaxation and decay pathways of the Si-H and Ge-H stretching modes in hydrogenated amorphous silicon-germanium thin films (a-SiGe: H). It is demonstrated that the decay of both modes has a nonexponential shape, attributable to t
Energy Technology Data Exchange (ETDEWEB)
Diallo, A.; Kramer, G. J.; Bell, R. E.; Guttenfelder, W.; LeBlanc, B. P.; Podesta, M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States); Smith, D. R.; McKee, G. J. [Departments of Engineering Physics and Physics, University of Wisconsin, Madison, Wisconsin (United States); Maingi, R. [Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831 (United States); Fonck, R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States); Departments of Engineering Physics and Physics, University of Wisconsin, Madison, Wisconsin (United States)
2013-01-15
Characterization of the spatial structure of turbulence fluctuations during the edge localized mode cycle in the pedestal region is reported. Using the beam emission spectroscopy and the correlation reflectometry systems, measurements show spatial structure-k{sub Up-Tack }{rho}{sub i}{sup ped}-ranging from 0.2 to 0.7 propagating in the ion diamagnetic drift direction at the pedestal top. These propagating spatial scales are found to be anisotropic and consistent with ion-scale microturbulence of the type ion temperature gradient and/or kinetic ballooning modes.
Directory of Open Access Journals (Sweden)
Abílio Amiguinho
2005-01-01
Full Text Available The process of socio-educational territorialisation in rural contexts is the topic of this text. The theme corresponds to a challenge to address it having as main axis of discussion either the problem of social exclusion or that of local development. The reasons to locate the discussion in this last field of analysis are discussed in the first part of the text. Theoretical and political reasons are there articulated because the question is about projects whose intentions and practices call for the political both in the theoretical debate and in the choices that anticipate intervention. From research conducted for several years, I use contributions that aim at discuss and enlighten how school can be a potential locus of local development. Its identification and recognition as local institution (either because of those that work and live in it or because of those that act in the surrounding context are crucial steps to progressively constitute school as a partner for development. The promotion of the local values and roots, the reconstruction of socio-personal and local identities, the production of sociabilities and the equation and solution of shared problems were the dimensions of a socio-educative intervention, markedly globalising. This scenario, as it is argued, was also, intentionally, one of transformation and of deliberate change of school and of the administration of the educative territoires.
Zhao, Jinfeng; Bonello, Bernard; Boyko, Olga
2016-05-01
We have investigated the focusing of the lowest-order antisymmetric Lamb mode (A0) behind a positive gradient-index (GRIN) acoustic metalens consisting of air holes drilled in a silicon plate with silicon pillars erected on one face of the lens. We have analyzed the focusing in the near field as the result of the coupling between the flexural resonant mode of the pillars and the vibration mode of the air/silicon phononic crystal. We highlight the role played by the polarization coherence between the resonant mode and the vibration of the plate. We demonstrate both numerically and experimentally the focusing behind the lens over a spot less than half a wavelength, paving a way for performance of acoustic lenses beyond the diffraction limit. Our findings can be easily extended to other types of elastic wave.
Leconte, M; Jeon, Y M
2016-01-01
We derive and study a simple 1D nonlinear model for Edge Localized Mode (ELM) cycles. The nonlinear dynamics of a resistive ballooning mode is modeled via a single nonlinear equation of the Ginzburg-Landau type with a radial frequency gradient due to a prescribed ExB shear layer of finite extent. The nonlinearity is due to the feedback of the mode on the profile. We identify a novel mechanism, whereby the ELM only crosses the linear stability boundary once, and subsequently stays in the nonlinear regime for the full duration of the cycles. This is made possible by the shearing and merging of filaments by the ExB flow, which forces the system to oscillate between a radially-uniform solution and a non-uniform solitary - wave like solution. The model predicts a 'phase-jump' correlated with the ELM bursts.
Energy Technology Data Exchange (ETDEWEB)
Baylor, Larry R [ORNL; Commaux, Nicolas JC [ORNL; Jernigan, T. C. [Oak Ridge National Laboratory (ORNL); Meitner, Steven J [ORNL; Combs, Stephen Kirk [ORNL; Isler, Ralph C [ORNL; Unterberg, Ezekial A [ORNL; Brooks, N. H. [General Atomics, San Diego; Evans, T. E. [General Atomics, San Diego; Leonard, A. W. [General Atomics; Osborne, T. H. [General Atomics; Parks, P. B. [General Atomics; Snyder, P. B. [General Atomics; Strait, E. J. [General Atomics; Fenstermacher, M. E. [Lawrence Livermore National Laboratory (LLNL); Lasnier, C. J. [Lawrence Livermore National Laboratory (LLNL); Moyer, R. A. [University of California, San Diego; Loarte, A. [ITER Organization, Cadarache, France; Huijsmans, G. T.A. [ITER Organization, Saint Paul Lez Durance, France; Futantani, S. [ITER Organization, Saint Paul Lez Durance, France
2013-01-01
The injection of small deuterium pellets at high repetition rates up to 12 the natural edge localized mode (ELM) frequency has been used to trigger high-frequency ELMs in otherwise low natural ELM frequency H-mode deuterium discharges in the DIII-D tokamak [J. L. Luxon and L. G. Davis, Fusion Technol. 8, 441 (1985)]. The resulting pellet-triggered ELMs result in up to 12 lower energy and particle fluxes to the divertor than the natural ELMs. The plasma global energy confinement and density are not strongly affected by the pellet perturbations. The plasma core impurity density is strongly reduced with the application of the pellets. These experiments were performed with pellets injected from the low field side pellet in plasmas designed to match the ITER baseline configuration in shape and normalized operation with input heating power just above the H-mode power threshold. Nonlinear MHD simulations of the injected pellets show that destabilization of ballooning modes by a local pressure perturbation is responsible for the pellet ELM triggering. This strongly reduced ELM intensity shows promise for exploitation in ITER to control ELM size while maintaining high plasma purity and performance.
Institute of Scientific and Technical Information of China (English)
杨忠志; 李慎敏; 唐敖庆
1995-01-01
By using the quasiclassical trajectory method,changes of normal and local mode vibrationalexcitation energies with time are investigated for XH4 （X=C,Si,Ge） molecules.The results demonstrate thatin a CH4 molecule the coupling between C—H stretching vibration and H—C—H bending vibration is relative-ly large so that the energy transfer is fast;while in SiH4 or GeH4 molecules this coupling is relativelysmall and thus an obvious energy relaxation is observed.This implies that there exists approximate local modevibrations for certain vibrational excitation states.
Blanc, Philippe; Massip, Pierre; Kazantzidis, Andreas; Tzoumanikas, Panagiotis; Kuhn, Pascal; Wilbert, Stefan; Schüler, David; Prahl, Christoph
2017-06-01
Nowcasting of high resolution maps of direct normal irradiance (DNI) is of interest to efficiently operate Concentrated Solar Power plants. The paper presents a state-of-the-art and innovative methodology, developed in the framework of the FP7 DNICast project, to derive nowcasting of DNI maps from fish-eye cameras in stereoscopic mode. This methodology has been applied at the Plataforma Solar de Almeria: fish-eye cameras at distances from each other between 500 m and 900 m have been used in stereoscopic mode to produce nowcasted 1-min time series of decametric DNI maps.
Buchanan, Evan G; James, William H; Choi, Soo Hyuk; Guo, Li; Gellman, Samuel H; Müller, Christian W; Zwier, Timothy S
2012-09-07
Single-conformation infrared spectra in the amide I and amide II regions have been recorded for a total of 34 conformations of three α-peptides, three β-peptides, four α/β-peptides, and one γ-peptide using resonant ion-dip infrared spectroscopy of the jet-cooled, isolated molecules. Assignments based on the amide NH stretch region were in hand, with the amide I/II data providing additional evidence in favor of the assignments. A set of 21 conformations that represent the full range of H-bonded structures were chosen to characterize the conformational dependence of the vibrational frequencies and infrared intensities of the local amide I and amide II modes and their amide I/I and amide II/II coupling constants. Scaled, harmonic calculations at the DFT M05-2X/6-31+G(d) level of theory accurately reproduce the experimental frequencies and infrared intensities in both the amide I and amide II regions. In the amide I region, Hessian reconstruction was used to extract local mode frequencies and amide I/I coupling constants for each conformation. These local amide I frequencies are in excellent agreement with those predicted by DFT calculations on the corresponding (13)C = (18)O isotopologues. In the amide II region, potential energy distribution analysis was combined with the Hessian reconstruction scheme to extract local amide II frequencies and amide II/II coupling constants. The agreement between these local amide II frequencies and those obtained from DFT calculations on the N-D isotopologues is slightly worse than for the corresponding comparison in the amide I region. The local mode frequencies in both regions are dictated by a combination of the direct H-bonding environment and indirect, "backside" H-bonds to the same amide group. More importantly, the sign and magnitude of the inter-amide coupling constants in both the amide I and amide II regions is shown to be characteristic of the size of the H-bonded ring linking the two amide groups. These amide I/I and
Javadi, A.; Maibom, S.; Sapienza, L.; Thyrrestrup Nielsen, H.; Garcia, P.D.; Lodahl, P.
2014-01-01
We present a statistical study of the Purcell enhancement of the light emission from quantum dots coupled to Anderson-localized cavities formed in disordered photonic-crystal waveguides. We measure the time-resolved light emission from both single quantum emitters coupled to Anderson-localized cavit
Poulsen, William L.; Inan, Umran S.; Bell, Timothy F.
1993-01-01
Transient localized D region disturbances, such as those associated with lightning discharges, affect the characteristics of VLF waves propagating in the Earth-ionosphere waveguide. In particular, both phase and amplitude changes in the subionospheric signal can be observed at receiving sites as a result of the wave scattering that takes place in the disturbed region. In the present paper we present a multiple-mode three-dimensional model of VLF propagation in the Earth-ionosphere waveguide in the presence of localized D region disturbances. The model takes into account great circle (GC) propagation paths with realistic ground and ionospheric conductivity changes that result in mode conversion along the path. It is assumed that conductivity changes transverse to the GC paths are negligible except in the vicinity of the D region disturbance and that mode coupling is negligible within the disturbed region. This new model is applied to experimental observations and is found to be in general agreement. The diagnostics potential of the model for characterizing energetic particle precipitation events is discussed.
Energy Technology Data Exchange (ETDEWEB)
Lore, J. D., E-mail: lorejd@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Reinke, M. L.; Lipschultz, B. [York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Brunner, D.; LaBombard, B.; Terry, J. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); Pitts, R. A. [ITER Organization, Route de Vinon-sur-Verdon, CS 90046 - 13067 Saint Paul Lez Durance Cedex (France); Feng, Y. [Max Planck Institute for Plasma Physics, Greifswald (Germany)
2015-05-15
Experiments in Alcator C-Mod to assess the level of toroidal asymmetry in divertor conditions resulting from poloidally and toroidally localized extrinsic impurity gas seeding show a weak toroidal peaking (∼1.1) in divertor electron temperatures for high-power enhanced D-alpha H-mode plasmas. This is in contrast to similar experiments in Ohmically heated L-mode plasmas, which showed a clear toroidal modulation in the divertor electron temperature. Modeling of these experiments using the 3D edge transport code EMC3-EIRENE [Y. Feng et al., J. Nucl. Mater. 241, 930 (1997)] qualitatively reproduces these trends, and indicates that the different response in the simulations is due to the ionization location of the injected nitrogen. Low electron temperatures in the private flux region (PFR) in L-mode result in a PFR plasma that is nearly transparent to neutral nitrogen, while in H-mode the impurities are ionized in close proximity to the injection location, with this latter case yielding a largely axisymmetric radiation pattern in the scrape-off-layer. The consequences for the ITER gas injection system are discussed. Quantitative agreement with the experiment is lacking in some areas, suggesting potential areas for improving the physics model in EMC3-EIRENE.
Energy Technology Data Exchange (ETDEWEB)
Vecchiola, Aymeric [Laboratoire de Génie électrique et électronique de Paris (GeePs), UMR 8507 CNRS-CentraleSupélec, Paris-Sud and UPMC Universities, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette (France); Concept Scientific Instruments, ZA de Courtaboeuf, 2 rue de la Terre de Feu, 91940 Les Ulis (France); Unité Mixte de Physique CNRS-Thales UMR 137, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); Chrétien, Pascal; Schneegans, Olivier; Mencaraglia, Denis; Houzé, Frédéric, E-mail: frederic.houze@geeps.centralesupelec.fr [Laboratoire de Génie électrique et électronique de Paris (GeePs), UMR 8507 CNRS-CentraleSupélec, Paris-Sud and UPMC Universities, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette (France); Delprat, Sophie [Unité Mixte de Physique CNRS-Thales UMR 137, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); UPMC, Université Paris 06, 4 place Jussieu, 75005 Paris (France); Bouzehouane, Karim; Seneor, Pierre; Mattana, Richard [Unité Mixte de Physique CNRS-Thales UMR 137, 1 avenue Augustin Fresnel, 91767 Palaiseau (France); Tatay, Sergio [Molecular Science Institute, University of Valencia, 46980 Paterna (Spain); Geffroy, Bernard [Lab. Physique des Interfaces et Couches minces (PICM), UMR 7647 CNRS-École polytechnique, 91128 Palaiseau (France); Lab. d' Innovation en Chimie des Surfaces et Nanosciences (LICSEN), NIMBE UMR 3685 CNRS-CEA Saclay, 91191 Gif-sur-Yvette (France); and others
2016-06-13
An imaging technique associating a slowly intermittent contact mode of atomic force microscopy (AFM) with a home-made multi-purpose resistance sensing device is presented. It aims at extending the widespread resistance measurements classically operated in contact mode AFM to broaden their application fields to soft materials (molecular electronics, biology) and fragile or weakly anchored nano-objects, for which nanoscale electrical characterization is highly demanded and often proves to be a challenging task in contact mode. Compared with the state of the art concerning less aggressive solutions for AFM electrical imaging, our technique brings a significantly wider range of resistance measurement (over 10 decades) without any manual switching, which is a major advantage for the characterization of materials with large on-sample resistance variations. After describing the basics of the set-up, we report on preliminary investigations focused on academic samples of self-assembled monolayers with various thicknesses as a demonstrator of the imaging capabilities of our instrument, from qualitative and semi-quantitative viewpoints. Then two application examples are presented, regarding an organic photovoltaic thin film and an array of individual vertical carbon nanotubes. Both attest the relevance of the technique for the control and optimization of technological processes.
Vecchiola, Aymeric; Chrétien, Pascal; Delprat, Sophie; Bouzehouane, Karim; Schneegans, Olivier; Seneor, Pierre; Mattana, Richard; Tatay, Sergio; Geffroy, Bernard; Bonnassieux, Yvan; Mencaraglia, Denis; Houzé, Frédéric
2016-06-01
An imaging technique associating a slowly intermittent contact mode of atomic force microscopy (AFM) with a home-made multi-purpose resistance sensing device is presented. It aims at extending the widespread resistance measurements classically operated in contact mode AFM to broaden their application fields to soft materials (molecular electronics, biology) and fragile or weakly anchored nano-objects, for which nanoscale electrical characterization is highly demanded and often proves to be a challenging task in contact mode. Compared with the state of the art concerning less aggressive solutions for AFM electrical imaging, our technique brings a significantly wider range of resistance measurement (over 10 decades) without any manual switching, which is a major advantage for the characterization of materials with large on-sample resistance variations. After describing the basics of the set-up, we report on preliminary investigations focused on academic samples of self-assembled monolayers with various thicknesses as a demonstrator of the imaging capabilities of our instrument, from qualitative and semi-quantitative viewpoints. Then two application examples are presented, regarding an organic photovoltaic thin film and an array of individual vertical carbon nanotubes. Both attest the relevance of the technique for the control and optimization of technological processes.
Directory of Open Access Journals (Sweden)
G. Meneghetti
2015-07-01
Full Text Available In this work, a link between the averaged strain energy density (SED approach and the peak stress method in the case of cracks subjected to mixed mode (I+II loading has been investigated. Some closed-form expressions of the strain energy density, averaged in a volume of radius R0, as function of the Stress Intensity Factors are provided for plane strain conditions under mixed mode I+II loadings, the material being thought of as isotropic and linear elastic. On the basis of the peak stress method (PSM some expressions useful to estimate the mode I and mode II stress intensity factors (SIFs have been recently derived. These relationships take advantage of the elastic peak stresses from FE analyses carried out by using a given mesh pattern where the element size and type are kept constants. The evaluation of the SIFs from a numerical analysis of the local stress field usually requires very refined meshes and then large computational effort. The usefulness of the PSM-based expressions is that (i only the elastic peak stresses numerically evaluated at the crack tip are needed and not a set of stress–distance data; (ii the employed meshes are rather coarse if compared to those necessary for the evaluation of the whole local stress field. By substituting the PSM-based relationships in the closed-form expressions of the averaged SED it appears that the latter can be directly estimated by means of the elastic peak stresses evaluated at the crack tip. Several FE analyses have been carried out on cracked plates subjected to tension loading considering different geometrical combinations, varying the length 2a and the inclination ϕ of the crack (i.e. the mode mixity as well as the size d of the adopted finite elements, with the aim to evaluate the local SED and the elastic peak stress components σpeak and τpeak. In all cases the numerical values of the SED derived from the FE analyses have been compared with those analytically obtained by using the
DEFF Research Database (Denmark)
de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst; Mørk, Jesper
2015-01-01
We present and validate a semi-analytical quasi-normal mode (QNM) theory for the local density of states (LDOS) in coupled photonic crystal (PhC) cavity-waveguide structures. By means of an expansion of the Green's function on one or a few QNMs, a closed-form expression for the LDOS is obtained......, and for two types of two-dimensional PhCs, with one and two cavities side-coupled to an extended waveguide, the theory is validated against numerically exact computations. For the single cavity, a slightly asymmetric spectrum is found, which the QNM theory reproduces, and for two cavities a non...
Directory of Open Access Journals (Sweden)
Qin Jiang
2010-01-01
Full Text Available Mismatch problem has been one of important issues of matched field processing for underwater source detection. Experimental use of MFP has shown that robust range and depth localization is difficult to achieve. In many cases this is due to uncertainty in the environmental inputs required by acoustic propagation models. The paper presents that EMD (Empirical mode decomposition processing underwater acoustic signals is motivated because it is well suited for removing specific unwanted signal components that may vary spectrally. And the Karhunen-Loève expansion is applied on sample covariance matrix to gain a relatively uncorrupted signal. The EMD denoising scheme is combined with Karhunen-Loève expansion to improve underwater target localization performance of matched field processing (MFP. The robustness and effectiveness of the proposed method is tested by the benchmark cases numerical simulation when there had large environmental parameter uncertainties of the acoustic waveguide.
Jia, Baohua; Norton, Andrew H; Li, Jiafang; Rahmani, Adel; Asatryan, Ara A; Botten, Lindsay C; Gu, Min
2008-05-15
A near-field microscope coupled with a near-infrared (NIR) supercontinuum source is developed and applied to characterize optical modes in a three-dimensional (3D) woodpile photonic crystal (PC) possessing a NIR partial bandgap. Spatially resolved near-field intensity distributions under different illumination wavelengths demonstrate that the electric fields preferentially dwell in the polymer rods or in the gaps between rods, respectively, for frequencies below or above the stop gap, as predicted by the 3D finite-difference time-domain modeling. Near-field microspectroscopy further reveals that the position-dependent band-edge effect plays an important role in PC-based all-optical integrated devices.
Yang, Fan; Moiseev, E S; Simon, Christoph; Lvovsky, A I
2016-01-01
The Rayleigh limit has so far applied to all microscopy techniques that rely on linear optical interaction and detection in the far field. Here we demonstrate that detecting the light emitted by an object in higher-order transverse electromagnetic modes (TEMs) can help achieving sub-Rayleigh precision for a variety of microscopy-related tasks. Using optical heterodyne detection in TEM01, we measure the position of coherently and incoherently emitting objects to within 0.0015 and 0.012 of the Rayleigh limit, respectively, and determine the distance between two incoherently emitting slits positioned within 0.28 of the Rayleigh limit with a precision of 0.019 of the Rayleigh limit. Extending our technique to higher-order TEMs enables full imaging with resolution significantly below the Rayleigh limit in a way that is reminiscent of quantum tomography of optical states.
Energy Technology Data Exchange (ETDEWEB)
Fanack, C.; Boucher, I.; Heuraux, S.; Leclert, G. [Centre National de la Recherche Scientifique (CNRS), 54 - Nancy (France). Lab. de Physique du Solide; Clairet, F.; Zou, X.L. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee
1996-01-01
Ordinary wave reflectometry in a plasma containing a localized density perturbation is studied with a 1-D model. The phase response is studied as a function of the wavenumber and position of the perturbation. It is shown that it strongly depends upon the perturbation shape and size. For a small perturbation wavenumber, the response is due to the oscillation of the cut-off layer. For larger wavenumbers, two regimes are found: for a broad perturbation, the phase response is an image of the perturbation itself; for a narrow perturbation, it is rather an image of the Fourier transform. For tokamak plasmas it turns out that, for the fluctuation spectra usually observed, the phase response comes primarily from those fluctuations that are localized at the cut-off. Results of a 2-D numerical model show that geometry effects are negligible for the scattering by radial fluctuations. (author). 18 refs.
Energy Technology Data Exchange (ETDEWEB)
Colas, L., E-mail: laurent.colas@cea.fr [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Jacquet, Ph. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Van Eester, D. [LPP-ERM-KMS, TEC partner, Brussels (Belgium); Bobkov, V. [Max-Planck-Institut für Plasmaphysik, Garching (Germany); Brix, M.; Meneses, L. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Tamain, P. [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Marsen, S. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Silva, C. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa (Portugal); Carralero, D.; Kočan, M.; Müller, H.-W. [Max-Planck-Institut für Plasmaphysik, Garching (Germany); Crombé, K.; Křivska, A. [LPP-ERM-KMS, TEC partner, Brussels (Belgium); Goniche, M. [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Lerche, E. [LPP-ERM-KMS, TEC partner, Brussels (Belgium); Rimini, F.G. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)
2015-08-15
Combining Lithium beam emission spectroscopy and edge reflectometry, localized Scrape-Off Layer (SOL) density modifications by Ion Cyclotron Range of Frequencies (ICRF) near fields were characterized in JET L-mode plasmas. When using the ICRF wave launchers connected magnetically to the Li-beam chord, the density decreased more steeply 2–3 cm outside the last closed flux surface (mapped onto the outer mid-plane) and its value at the outer limiter radial position was half the ohmic value. The depletion depends on the ICRF power and on the phasing between adjacent radiating straps. Convection due to ponderomotive effects and/or E × B{sub 0} drifts is suspected: during ICRF-heated H-mode discharges in 2013, DC potentials up to 70 V were measured locally in the outer SOL by a floating reciprocating probe, located toroidally several metres from the active antennas. These observations are compared with probe measurements on ASDEX-Upgrade. Their implications for wave coupling, heat loads and impurity production are discussed.
Impact of localized gas injection on ICRF coupling and SOL parameters in JET-ILW H-mode plasmas
Energy Technology Data Exchange (ETDEWEB)
Lerche, E., E-mail: elerche@jet.efda.org [LPP-ERM-KMS, TEC Partner, 1000 Brussels (Belgium); CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Goniche, M. [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Jacquet, P. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Van Eester, D. [LPP-ERM-KMS, TEC Partner, 1000 Brussels (Belgium); Bobkov, V. [Max-Planck-Institut für Plasmaphysik, Garching (Germany); Colas, L. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Czarnecka, A. [IPPLM, 01-497 Warsaw (Poland); Brezinsek, S. [Forschungszentrum Jülich, Institute of Energy Research, Jülich (Germany); Brix, M. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Crombe, K. [LPP-ERM-KMS, TEC Partner, 1000 Brussels (Belgium); Graham, M. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Groth, M. [Aalto University, 02015 Espoo (Finland); Monakhov, I. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Mathurin, T. [École des Mines de Paris, 75006 Paris (France); Matthews, G. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Meneses, L. [Instituto de Plasma e Fusão Nuclear, Instituto Superior Técnico, Lisbon (Portugal); Noble, C. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Petrzilka, V. [Institute of Plasma Physics, Prague (Czech Republic); Rimini, F.; Shaw, A. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)
2015-08-15
Recent JET-ILW [1,2] experiments reiterated the importance of tuning the plasma fuelling in order to optimize ion cyclotron resonance frequency (ICRF) heating in high power H-mode discharges. By fuelling the plasma from gas injection modules (GIMs) located in the mid-plane and on the top of the machine instead of adopting the more standardly used divertor GIMs, a considerable increase of the ICRF antenna coupling resistances was achieved with moderate gas injection rates (<1.5 × 10{sup 22} e/s). This effect is explained by an increase of the scrape-off-layer density in front of the antennas when mid-plane and top fuelling is used. By distributing the gas injection to optimize the coupling of all ICRF antenna arrays simultaneously, a substantial increase in the ICRF power capability and reliability was attained. Although similar core/pedestal plasma properties were observed for the different injection cases, the experiments indicate that the RF-induced impurity sources are reduced when switching from divertor to main chamber gas injection.
Agapitov, Oleksiy; Artemyev, Anton; Mourenas, Didier; Mozer, Forrest; Krasnoselskikh, Vladimir
2016-04-01
Simultaneous observations of electron velocity distributions and chorus waves by the Van Allen Probe B are analyzed to identify long-lasting (more than 6 h) signatures of electron Landau resonant interactions with oblique chorus waves in the outer radiation belt. Such Landau resonant interactions result in the trapping of ˜1-10 keV electrons and their acceleration up to 100-300 keV. This kind of process becomes important for oblique whistler mode waves having a significant electric field component along the background magnetic field. In the inhomogeneous geomagnetic field, such resonant interactions then lead to the formation of a plateau in the parallel (with respect to the geomagnetic field) velocity distribution due to trapping of electrons into the wave effective potential. We demonstrate that the electron energy corresponding to the observed plateau remains in very good agreement with the energy required for Landau resonant interaction with the simultaneously measured oblique chorus waves over 6 h and a wide range of L shells (from 4 to 6) in the outer belt. The efficient parallel acceleration modifies electron pitch angle distributions at energies ˜50-200 keV, allowing us to distinguish the energized population. The observed energy range and the density of accelerated electrons are in reasonable agreement with test particle numerical simulations.
Bogdanov, A Y; Valiev, K A; Bogdanov, Yu.I.
2005-01-01
We investigate the procedure of Schmidt modes extraction in systems with continuous variables. An algorithm based on singular value matrix decomposition is applied to the study of entanglement in an "atom-photon" system with spontaneous radiation. Also, this algorithm is applied to the study of a bi-photon system with spontaneous parametric down conversion with type-II phase matching for broadband pump. We demonstrate that dynamic properties of entangled states in an atom-photon system with spontaneous radiation are defined by a parameter equal to the product of the fine structure constant and the atom-electron mass ratio. We then consider the evolution of the system during radiation and show that the atomic and photonic degrees of freedom are entangling for the times of the same order of magnitude as the excited state life-time. Then the degrees of freedom are de-entangling and asymptotically approach to the level of small residual entanglement that is caused by momentum dispersion of the initial atomic pack...
Fluctuation signatures of rotation reversals and non-local transport events in KSTAR L-mode plasmas
Shi, Yuejiang
2016-01-01
Experiments in KSTAR tokamak show that non-local heat transport (NLT) is closely connected to toroidal rotation reversal. We demonstrate that NLT can be affected by electron cyclotron resonance heating (ECH), and the intrinsic rotation direction follows the changes of NLT. The cut-off density of NLT can be significantly extended by ECH. Without ECH, NLT disappears as the line averaged density ne increases above 1.25*10e19me-3. By applying ECH, NLT reappears with the ne= 2.4*10e19me-3. At the same density level, the core toroidal rotation also changes from counter-current to co-current direction by applying ECH. The poloidal flow of turbulence in core plasma estimated from MIR is in electron diamagnetic direction in ECH plasmas and ion diamagnetic direction in high density OH plasma. The auto-power spectra of density fluctuation measured by MIR are almost the same in the outer region for ECH and OH plasma. On the other hand, in the core region of ECH plasmas, the power spectra of the density fluctuations are b...
de Lasson, Jakob Rosenkrantz; Mørk, Jesper; Gregersen, Niels
2015-01-01
We present and validate a semi-analytical quasi-normal mode (QNM) theory for the local density of states (LDOS) in coupled photonic crystal (PhC) cavity-waveguide structures. By means of an expansion of the Green's function on one or a few QNMs, a closed-form expression for the LDOS is obtained, and for two types of two-dimensional PhCs, with one and two cavities side-coupled to an extended waveguide, the theory is validated against numerically exact computations. For the single cavity, a slightly asymmetric spectrum is found, which the QNM theory reproduces, and for two cavities a non-trivial spectrum with a peak and a dip is found, which is reproduced only when including both the two relevant QNMs in the theory. In both cases, we find relative errors below 1% in the bandwidth of interest.
Energy Technology Data Exchange (ETDEWEB)
Wolfrum, E; Bernert, M; Burckhart, A; Classen, I G J; Conway, G D; Eich, T; Fischer, R; Gude, A; Herrmann, A; Maraschek, M; McDermott, R; Puetterich, T; Wieland, B [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Garching (Germany); Boom, J E [FOM Institute for Plasmaphysics, Rijnhuizen, Association EURATOM-FOM, Nieuwegein (Netherlands); Luhmann, N C Jr [University of California at Davis, Davis, CA95616 (United States); Park, H K [POSTECH, Pohang, Gyeongbuk, 790-784 (Korea, Republic of); Vicente, J [Associacao EURATOM/IST, Instituto de Plasmas e Fosao Nuclear - Laboratorio Associado, IST, Lisbon (Portugal); Willensdorfer, M, E-mail: e.wolfrum@ipp.mpg.de [Institute of Applied Physics, Vienna University of Technology, Association EURATOM-OEAW, Vienna (Austria)
2011-08-15
Edge localized modes (ELMs) with high frequency and low power loss (type-II ELMs) occur in high triangularity, near double null configurations in ASDEX Upgrade with full tungsten plasma facing components. The transition from type-I to type-II ELMs is shown to occur above a collisionality threshold. For the first time the characteristic MHD fluctuations around 40 kHz have been localized. The fluctuations are observed in a wide region extending from the pedestal inward to normalized poloidal radius {rho}{sub pol} = 0.7. Their amplitudes on the low-field side of the plasma exhibit maxima above and below the mid-plane. The fluctuations move in the electron drift direction and lead to a reduced edge electron temperature gradient. The reduction in the edge pressure gradient is connected with these MHD fluctuations, which affect the electron temperature but not the electron density profiles. A comparison with nitrogen-mitigated type-I ELMs in the same plasma shape shows that core profiles are also affected. The electron temperature profile is self-similar for type-I and nitrogen-mitigated type-I ELMs but is not self-similar in the case of type-II ELMs.
Physics basis of Multi-Mode anomalous transport module
Energy Technology Data Exchange (ETDEWEB)
Rafiq, T.; Kritz, A. H.; Luo, L. [Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States); Weiland, J. [Departments of Applied Physics, Chalmers University of Technology and Euratom-VR Assoc., S41296 Gothenburg (Sweden); Pankin, A. Y. [Tech-X Corporation, Boulder, Colorado (United States)
2013-03-15
The derivation of Multi-Mode anomalous transport module version 8.1 (MMM8.1) is presented. The MMM8.1 module is advanced, relative to MMM7.1, by the inclusion of peeling modes, dependence of turbulence correlation length on flow shear, electromagnetic effects in the toroidal momentum diffusivity, and the option to compute poloidal momentum diffusivity. The MMM8.1 model includes a model for ion temperature gradient, trapped electron, kinetic ballooning, peeling, collisionless and collision dominated magnetohydrodynamics modes as well as model for electron temperature gradient modes, and a model for drift resistive inertial ballooning modes. In the derivation of the MMM8.1 module, effects of collisions, fast ion and impurity dilution, non-circular flux surfaces, finite beta, and Shafranov shift are included. The MMM8.1 is used to compute thermal, particle, toroidal, and poloidal angular momentum transports. The fluid approach which underlies the derivation of MMM8.1 is expected to reliably predict, on an energy transport time scale, the evolution of temperature, density, and momentum profiles in plasma discharges for a wide range of plasma conditions.
Energy Technology Data Exchange (ETDEWEB)
Batou, A., E-mail: anas.batou@univ-paris-est.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallee (France); Soize, C., E-mail: christian.soize@univ-paris-est.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallee (France); Brie, N., E-mail: nicolas.brie@edf.fr [EDF R and D, Département AMA, 1 avenue du général De Gaulle, 92140 Clamart (France)
2013-09-15
Highlights: • A ROM of a nonlinear dynamical structure is built with a global displacements basis. • The reduced order model of fuel assemblies is accurate and of very small size. • The shocks between grids of a row of seven fuel assemblies are computed. -- Abstract: We are interested in the construction of a reduced-order computational model for nonlinear complex dynamical structures which are characterized by the presence of numerous local elastic modes in the low-frequency band. This high modal density makes the use of the classical modal analysis method not suitable. Therefore the reduced-order computational model is constructed using a basis of a space of global displacements, which is constructed a priori and which allows the nonlinear dynamical response of the structure observed on the stiff part to be predicted with a good accuracy. The methodology is applied to a complex industrial structure which is made up of a row of seven fuel assemblies with possibility of collisions between grids and which is submitted to a seismic loading.
Chowdhury, J.; Wan, Weigang; Chen, Yang; Parker, Scott E.; Groebner, Richard J.; Holland, C.; Howard, N. T.
2014-11-01
The δ f particle-in-cell code GEM is used to study the transport "shortfall" problem of gyrokinetic simulations. In local simulations, the GEM results confirm the previously reported simulation results of DIII-D [Holland et al., Phys. Plasmas 16, 052301 (2009)] and Alcator C-Mod [Howard et al., Nucl. Fusion 53, 123011 (2013)] tokamaks with the continuum code GYRO. Namely, for DIII-D the simulations closely predict the ion heat flux at the core, while substantially underpredict transport towards the edge; while for Alcator C-Mod, the simulations show agreement with the experimental values of ion heat flux, at least within the range of experimental error. Global simulations are carried out for DIII-D L-mode plasmas to study the effect of edge turbulence on the outer core ion heat transport. The edge turbulence enhances the outer core ion heat transport through turbulence spreading. However, this edge turbulence spreading effect is not enough to explain the transport underprediction.
Institute of Scientific and Technical Information of China (English)
李志平
2011-01-01
Accelerating the transformation of the local economy development mode is a profound change in our economic and social fields, which relates reform and opening up and global socialist modernization as well as whether the local government can really represent, safeguard, and develop the public interest. Through institutional innovation, accelerating the transformation of the local economy development mode is an effective way for the local government to accelerating the local economy development; developing the science of value is the key point of institutional innovation ; grasping the difficulties and conducting institutional innovation are practical ways of accelerating the transformation of economic development mode%加快经济发展方式转变是我国经济社会领域的一场深刻变革，关系改革开放和社会主义现代化建设全局，也关系到地方政府能否真正代表好、维护好、发展好地方的公共利益。通过制度创新，是地方政府加快转变经济发展方式的有效途径；弘扬价值科学创设是制度创新重点；扭住难点，进行制度创新是加快转变经济发展方式的现实路径。
Devynck, P.; Fedorczak, N.; Meyer, O.; Contributors, JET
2016-12-01
A database of 250 pulses taken randomly during the experimental campaigns of JET with the ITER-like wall (ILW) is used to study the frequency dependences of the type I edge localized modes (ELM). A scaling of the ELM frequency is presented as a function of the pedestal density drop dN ped and a very simple model to interpret this scaling is discussed. In this model, the frequency of the ELMs is governed by the time needed by the neutral flux to refill the density of the pedestal. The filling rate is the result of a small imbalance between the neutral flux filling the pedestal and the outward flux that expels the particles to the SOL. The ELM frequency can be governed by such a mechanism if the recovery time of the temperature of the pedestal in JET occurs before or at the same time as the one of the density. This is observed to be the case. An effect of the fuelling is measured when the number of injected particles is less than 1 × 1022 particles s-1. In that case an increase of the inter-ELM time is observed which is related to the slower recovery of the density pedestal. Additionally, a scaling is found for the source of tungsten during the ELMs. The number of tungsten atoms eroded by the ELMs per second is proportional to dN ped multiplied by the ELM frequency. This is possible only if the tungsten sputtering yield is independent of the energy of the impinging particle hitting the divertor. This result is in agreement with Guillemault et al (2015 Plasma Phys. Control. Fusion 57 085006) and is compatible with the D+ ions hitting the divertor having energies above 2 keV. Finally, by plotting the Wcontent/Wsource ratio during ELM crash, a global decreasing behaviour with the ELM frequency is found. However at frequencies below 40 Hz a scatter towards upper values is found. This scatter is found to correlate with the gas injection level. In a narrow ELM frequency band around 20 Hz, it is found that both the ratio Wcontent/Wsource and Wsource
Shigeta, M.; Sato, T.; Dasgupta, B.
1985-01-01
The magnetohydrodynamic stability of streaming tearing mode is investigated numerically. A bulk plasma flow parallel to the antiparallel magnetic field lines and localized in the neutral sheet excites a streaming tearing mode more strongly than the usual tearing mode, particularly for the wavelength of the order of the neutral sheet width (or smaller), which is stable for the usual tearing mode. Interestingly, examination of the eigenfunctions of the velocity perturbation and the magnetic field perturbation indicates that the streaming tearing mode carries more energy in terms of the kinetic energy rather than the magnetic energy. This suggests that the streaming tearing mode instability can be a more feasible mechanism of plasma acceleration than the usual tearing mode instability.
Shigeta, M.; Sato, T.; Dasgupta, B.
1985-01-01
The magnetohydrodynamic stability of streaming tearing mode is investigated numerically. A bulk plasma flow parallel to the antiparallel magnetic field lines and localized in the neutral sheet excites a streaming tearing mode more strongly than the usual tearing mode, particularly for the wavelength of the order of the neutral sheet width (or smaller), which is stable for the usual tearing mode. Interestingly, examination of the eigenfunctions of the velocity perturbation and the magnetic field perturbation indicates that the streaming tearing mode carries more energy in terms of the kinetic energy rather than the magnetic energy. This suggests that the streaming tearing mode instability can be a more feasible mechanism of plasma acceleration than the usual tearing mode instability.
Energy Technology Data Exchange (ETDEWEB)
Kamiya, K.; Honda, M.; Urano, H.; Yoshida, M.; Kamada, Y. [Japan Atomic Energy Agency (JAEA), Naka, Ibaraki-ken 311-0193 (Japan); Itoh, K. [National Institute for Fusion Science (NIFS), Toki, Gifu 509-5292 (Japan)
2014-12-15
Modulation charge eXchange recombination spectroscopy measurements with high spatial and temporal resolution have made the evaluation of the toroidal plasma flow of fully stripped carbon impurity ions (V{sub ϕ}{sup C6+}) in the JT-60U tokamak peripheral region (including, in particular, the separatrix) possible with a better signal-to-noise ratio. By comparing co- and counter-neutral beam injection discharges experimentally, we have identified the boundary condition of V{sub ϕ}{sup C6+} and radial electric field shear (∇E{sub r}) imposed at the separatrix in high confinement (H-mode) plasmas with edge localized modes (ELMs). The V{sub ϕ}{sup C6+} value at the separatrix is not fixed at zero but varies with the momentum input direction. On the other hand, the ∇E{sub r} value is nearly zero (or very weakly positive) at the separatrix. Furthermore, the edge localized mode perturbation does not appear to affect both V{sub ϕ}{sup C6+} and ∇E{sub r} values at the separatrix as strongly as that in the pedestal region. The above experimental findings based on the precise edge measurements have been used to validate a theoretical model and develop a new empirical model. A better understanding of the physical process in the edge transport barrier (ETB) formation due to the sheared E{sub r} formation is also discussed.
Lu, Haifei; Ren, Xingang; Sha, Wei E I; Ho, Ho-Pui; Choy, Wallace C H
2015-10-28
We demonstrate that the silver nanoplate-based macroscopically periodic (macro-periodic) and microscopically random (micro-random) structure has a broadband near-field enhancement as compared to conventional silver gratings. The specific field enhancement in a wide spectral range (from UV to near-infrared) originates from the abundance of localized surface-plasmonic (LSP) modes in the microscopically random distributed silver nanoplates and propagating Bloch-plasmonic (PBP) modes from the macroscopically periodic pattern. The characterization of polarization dependent spectral absorption, surface-enhanced Raman spectroscopy (SERS), as well as theoretical simulation was conducted to comprehensively understand the features of the broadband spectrum and highly concentrated near-field. The reported macro-periodic and micro-random structure may offer a new route for the design of plasmonic systems for photonic and optoelectronic applications.
DEFF Research Database (Denmark)
de Lasson, Jakob Rosenkrantz; Mørk, Jesper; Kristensen, Philip Trøst
2013-01-01
We present a numerical formalism for solving the Lippmann–Schwinger equation for the electric field in three dimensions. The formalism may be applied to scatterers of different shapes and embedded in different background media, and we develop it in detail for the specific case of spherical...... as the quasi-normal modes of leaky resonators with the associated resonance frequencies and quality factors. We demonstrate the calculations for the well-known plasmonic dimer consisting of two silver nanoparticles and thus illustrate the versatility of the formalism for use in modeling of advanced...
Furuuchi, Kazuyuki
2016-07-01
In this article we study Kaluza-Klein (KK) dimensional reduction of massive Abelian gauge theories with charged matter fields on a circle. Since local gauge transformations change position dependence of the charged fields, the decomposition of the charged matter fields into KK modes is gauge dependent. While whole KK mass spectrum is independent of the gauge choice, the mode number depends on the gauge. The masses of the KK modes also depend on the field value of the zero-mode of the extra dimensional component of the gauge field. In particular, one of the KK modes in the KK tower of each massless 5D charged field becomes massless at particular values of the extra-dimensional component of the gauge field. When the extra-dimensional component of the gauge field is identified with the inflaton, this structure leads to recursive cosmological particle productions.
Combellas, Catherine; Ghilane, Jalal; Kanoufi, Frédéric; Mazouzi, Driss
2004-05-20
Fluoropolymers have been reduced locally by the radical anion of a redox mediator electrogenerated at a microelectrode operating in the configuration of a scanning electrochemical microscope. Approach curves with different redox mediators were used to investigate the reduction mechanism of the fluoropolymer. Different factors are discussed, such as the monomer reduction mechanism, the kinetic control by the surface modification growth, and the conductivity of the modified surface. The fluoropolymers' reduction parallels the trends observed in organic electrochemistry in solution within the haloalkane series.
Ellis, Chase T.; Tischler, Joseph G.; Glembocki, Orest J.; Bezares, Francisco J.; Giles, Alexander J.; Kasica, Richard; Shirey, Loretta; Owrutsky, Jeffrey C.; Chigrin, Dmitry N.; Caldwell, Joshua D.
2016-09-01
Polar dielectrics have garnered much attention as an alternative to plasmonic metals in the mid- to long-wave infrared spectral regime due to their low optical losses. As such, nanoscale resonators composed of these materials demonstrate figures of merit beyond those achievable in plasmonic equivalents. However, until now, only low-order, phonon-mediated, localized polariton resonances, known as surface phonon polaritons (SPhPs), have been observed in polar dielectric optical resonators. In the present work, we investigate the excitation of 16 distinct high-order, multipolar, localized surface phonon polariton resonances that are optically excited in rectangular pillars etched into a semi-insulating silicon carbide substrate. By elongating a single pillar axis we are able to significantly modify the far- and near-field properties of localized SPhP resonances, opening the door to realizing narrow-band infrared sources with tailored radiation patterns. Such control of the near-field behavior of resonances can also impact surface enhanced infrared optical sensing, which is mediated by polarization selection rules, as well as the morphology and strength of resonator hot spots. Furthermore, through the careful choice of polar dielectric material, these results can also serve as the guiding principles for the generalized design of optical devices that operate from the mid- to far-infrared.
Mode decomposition evolution equations.
Wang, Yang; Wei, Guo-Wei; Yang, Siyang
2012-03-01
Partial differential equation (PDE) based methods have become some of the most powerful tools for exploring the fundamental problems in signal processing, image processing, computer vision, machine vision and artificial intelligence in the past two decades. The advantages of PDE based approaches are that they can be made fully automatic, robust for the analysis of images, videos and high dimensional data. A fundamental question is whether one can use PDEs to perform all the basic tasks in the image processing. If one can devise PDEs to perform full-scale mode decomposition for signals and images, the modes thus generated would be very useful for secondary processing to meet the needs in various types of signal and image processing. Despite of great progress in PDE based image analysis in the past two decades, the basic roles of PDEs in image/signal analysis are only limited to PDE based low-pass filters, and their applications to noise removal, edge detection, segmentation, etc. At present, it is not clear how to construct PDE based methods for full-scale mode decomposition. The above-mentioned limitation of most current PDE based image/signal processing methods is addressed in the proposed work, in which we introduce a family of mode decomposition evolution equations (MoDEEs) for a vast variety of applications. The MoDEEs are constructed as an extension of a PDE based high-pass filter (Europhys. Lett., 59(6): 814, 2002) by using arbitrarily high order PDE based low-pass filters introduced by Wei (IEEE Signal Process. Lett., 6(7): 165, 1999). The use of arbitrarily high order PDEs is essential to the frequency localization in the mode decomposition. Similar to the wavelet transform, the present MoDEEs have a controllable time-frequency localization and allow a perfect reconstruction of the original function. Therefore, the MoDEE operation is also called a PDE transform. However, modes generated from the present approach are in the spatial or time domain and can be
Institute of Scientific and Technical Information of China (English)
黄罗生; 陈德润
2014-01-01
This thesis uses the current condition and existing problems of professional education of environmental design in local college of undergraduate course as the point of departure, discusses the establishment of the cultivating mode in the form of professional environmental design studio which treats practical program as subject and breaks the limitation of age prejudice and the system of mentor assuming responsibility. For the environmental design major in local college of undergraduate course, establishing of the cultivating mode of studio, forming its unique teaching features and improving teaching qualities of design education can lay a solid foundation for the school and help it gain a firmer foothold in the severe competition due to the abundance of teaching resources in the further.%在地方本科院校建立以实际项目为课题、混合年级、导师负责的环境设计专业工作室，对地方本科院校设计教育教学质量的提高，形成教学特色具有积极的理论与实践意义。
Directory of Open Access Journals (Sweden)
Bernard G. Hounmenou
2003-10-01
Full Text Available Les politiques de développement en cours dans plusieurs pays du sud, notamment dans ceux de l’Afrique sub-saharienne ont amorcé un nouveau tournant à partir de la fin des années 1980. A la faveur de l’instauration du climat de démocratie dans plusieurs de ces pays à partir de cette période, nombre d’entre eux ont procédé à de profondes réformes, donnant à la société civile et aux populations à la base, un droit de regard plus important dans la conduite des affaires les concernant. L’une des manifestations les plus importantes de ces réformes se traduit par la mise en œuvre de la décentralisation. Ce processus vise entre autres, la prise en compte des réalités locales et la responsabilisation des communautés à la base dans la gestion de leur développement. Il s’agit en d’autres termes, de favoriser le renforcement des capacités des populations locales, en vue de leur permettre de prendre en charge de façon durable, la gestion de leurs propres affaires dans le cadre de la gouvernance participative. Amorcé en janvier 1993, avec les états généraux de l’administration territoriale, le processus de la décentralisation au Bénin n’a connu sa phase de concrétisation qu’avec les élections et l’installation des élus locaux en début 2003. En prélude à l’avènement de la décentralisation, plusieurs localités béninoises font l’objet, depuis le milieu des années 1990, d’expériences d’appui au développement des communautés locales. C’est le cas notamment, des villages des départements de l’Atlantique et des Collines. A travers ces expériences, se mettent en place, divers dispositifs de gouvernance locale au sein des systèmes locaux d’action publique relatifs aux localités rurales. Il s’agit notamment, des comités villageois de suivi ou de gestion, des dispositifs de comités villageois de développement dans le département de l’Atlantique, et du dispositif des projets de
Localization of Germany’ s Dual System of Personnel Training Mode%德国“双元制”人才培养模式本土化实践研究
Institute of Scientific and Technical Information of China (English)
尹久
2014-01-01
The Dual System of personnel training mode in Germany is a well known vocational education system throughout the world. Because of the different educational mode in China and Germany, it is impracticable to use the above mode in China. Hubei Light Industry Technology Institute absorbs the quintessence of Germany’ s vocational education, with the objective of serving for e-conomic development in central China, cooperating with the German beverage packaging Giant Clowns Company, makes a localiza-tion practice, works out the difficulties, has created a localized practicing way with clear characteristics of central China.%德国“双元制”人才培养模式，是享誉世界的职业教育模式，但是由于中德两国教育体制不同，在中国照搬该模式行不通。湖北轻工职院认真吸取德国职业教育的精髓，以服务中部经济发展为目标，与德国饮料包装机械巨头克朗斯公司深度合作进行“双元制”本土化实践，破解了“双元制”中企业“元”短缺的难题，走出了一条具有中部特色的“双元制”本土化实践道路。
Les contributions des associations au mode local de régulation et les inégalités entre les régions
Directory of Open Access Journals (Sweden)
Marie Bouchard
2003-05-01
Full Text Available Les auteurs s’intéressent à la contribution des organismes de lutte contre la pauvreté au système régional de régulation dans une zone métropolitaine et une zone rurale périphérique toutes deux défavorisées. L’analyse comparée de ces organismes montrent que ceux-ci présentent des capacités et des limites différenciées sur le plan socioculturel et sur le plan des mécanismes de régulation politique pour contribuer au développement régional dans une perspective de lutte à la pauvreté. Des pistes d’intervention sont proposées afin d’accroître la contribution de ces organismes au développement local.
Biedron, William S.
1995-11-01
Since 1990 there has been a rapid increase in the demand for communication services, especially local and wide area network (LAN/WAN) oriented services. With the introduction of the DFB laser transmitter, hybrid-fiber-coax (HFC) cable plant designs, ATM transport technologies and rf modems, new LAN/WAN services can now be defined and marketed to residential and business customers over existing cable TV systems. The term metropolitan area network (MAN) can be used to describe this overall network. This paper discusses the technical components needed to provision these services as well as provides some perspectives on integration issues. Architecture at the headend and in the backbone is discussed, as well as specific service definitions and the technology issues associated with each. The TCP/IP protocol is suggested as a primary protocol to be used throughout the MAN.
Chen, Shao-Xia; Li, Bo; Xiong, Ming; Yu, Hui; Guo, Ming-Zhe
2016-12-01
While standing fast sausage modes in flare loops are often invoked to interpret quasi-periodic pulsations (QPPs) in solar flares, it is unclear as to how they are influenced by the combined effects of a continuous transverse structuring and a finite internal plasma beta ({β }{{i}}). We derive a generic dispersion relation governing linear sausage waves in straight magnetic tubes for which plasma pressure is not negligible, and the density and temperature inhomogeneities of essentially arbitrary form take place in a layer of arbitrary width. Focusing on fast modes, we find that {β }{{i}} only weakly influences {k}{{c}}, the critical longitudinal wavenumber separating the leaky from trapped modes. Likewise, for both trapped and leaky modes, the periods P in units of the transverse fast time depend only weakly on {β }{{i}}, which is compatible with the fact that the effective wave vectors of fast sausage modes are largely perpendicular to the background magnetic field. However, a weak {β }{{i}} dependence of the damping times τ is seen only when the length-to-radius ratio L/R is ∼50% larger than some critical value π /({k}{{c}}R), which itself rather sensitively depends on the density contrast, profile steepness, as well as on how the transverse structuring is described. In the context of QPPs, we conclude that the much simpler zero-beta theory can be employed for trapped modes, as long as one sees the deduced internal Alfvén speed as actually being the fast speed. In contrast, effects due to a finite beta in flare loops should be considered when leaky modes are exploited.
Reflections on Postgraduate Training Mode of Local Uni-versities and Colleges%对地方院校研究生培养模式的思考
Institute of Scientific and Technical Information of China (English)
赵向华
2013-01-01
Nowadays, in the course of cultivating graduate stu-dents, teaching hardware relatively lags, teachers should be strengthened, there is gap between supply and demand of talent cultivation, innovation ability is lacked. In view of this situation, as the important force ,local universities and colleges try to re-search the graduate cultivating model. Zhongkai University of A-griculture and Engineering carry out cooperative education grad-uate, and effect peeps.% 针对当前研究生培养中存在“教学硬件相对滞后、师资力量亟待加强、人才培养供需脱节、创新能力不足”等问题，研究生教育中一支非常重要的力量——地方高校，对研究生培养模式进行了积极探索和实践，其中，仲恺农业工程学院开展的“产学研联合培养研究生”的尝试，成效初现。
Order-Style Talent Cultivation Mode in Local Colleges and Universities%地方院校“订单式”人才培养模式的探索
Institute of Scientific and Technical Information of China (English)
杨松; 王晶
2014-01-01
地方院校实施“订单式”人才培养模式是校企合作的一种重要形式，是一件高校、学生和用人单位三方共赢的好事。但在目前情况下，地方院校实施“订单式”人才培养模式还存在诸如订单班的组建、课程置换、学生离校后的毕业前考试、安全和管理、高质量订单单位的寻找等问题。解决这些问题需要做好以下工作，一是加大宣传以解决订单班的组建问题；二是深化高校内部改革以保证人才培养模式的顺利实施；三是明晰三方行为主体的权责利关系；四是校企双方专人负责，加强管理。%The implementation of order-style talent cultivation mode in local colleges and universities is an important form of the cooperation between universities and enterprises, which can benefit universities, students and employers. However, in the present situation, there still exist some problems in the implementation of order-style talent cultivation mode in local colleges and universities such as the formation of order-style class, course displacement, students’graduation examination before leaving their universities, security and management, seeking for order units with high qualities and so on. To solve these problems, the following things should be done well: firstly, publicity should be strenghthened to form order-style class; secondly, the internal reform of colleges and universities should be deepened to ensure the successful implementation of talent cultivation mode; thirdly, the relationship of universities, students and employers’ power, responsibility and benefits should be clarified; and lastly, universities and enterprieses should specially appoint certain person to be charge of this issue and strenghthen management.
Local measurement for structural health monitoring
Institute of Scientific and Technical Information of China (English)
G.Z.Qi; Guo Xun; Qi Xiaozhai; W. Dong; P.Chang
2005-01-01
Localized nature of damage in structures requires local measurements for structural health monitoring. The local measurement means to measure the local, usually higher modes of the vibration in a structure. Three fundamental issues about the local measurement for structural health monitoring including (1) the necessity of making local measurement, (2) the difficulty of making local measurement and (3) how to make local measurement are addressed in this paper. The results from both the analysis and the tests show that the local measurement can successfully monitor the structural health status as long as the local modes are excited. Unfortunately, the results also illustrate that it is difficult to excite local modes in a structure.Therefore, in order to carry structural health monitoring into effect, we must (1) ensure that the local modes are excited, and (2) deploy enough sensors in a structure so that the local modes can be monitored.
Damage mechanics - failure modes
Energy Technology Data Exchange (ETDEWEB)
Krajcinovic, D.; Vujosevic, M. [Arizona State Univ., Tempe, AZ (United States)
1996-12-31
The present study summarizes the results of the DOE sponsored research program focused on the brittle failure of solids with disordered microstructure. The failure is related to the stochastic processes on the microstructural scale; namely, the nucleation and growth of microcracks. The intrinsic failure modes, such as the percolation, localization and creep rupture, are studied by emphasizing the effect of the micro-structural disorder. A rich spectrum of physical phenomena and new concepts that emerges from this research demonstrates the reasons behind the limitations of traditional, deterministic, and local continuum models.
DEFF Research Database (Denmark)
Jakobsen, K. P.; Burcharth, H. F.; Ibsen, Lars Bo;
1999-01-01
The present appendix contains the derivation of ten different limit state equations divided on three different failure modes. Five of the limit state equations can be used independently of the characteristics of the subsoil, whereas the remaining five can be used for either drained or undrained...
Institute of Scientific and Technical Information of China (English)
李春艳
2012-01-01
Higher engineering education is an important part of higher education of china and Higher Mathematics course is the most important foundation course in higher engineering education. In this paper, the present situation of Higher Mathe- matics in engineering colleges is discussed, the teaching reform of Higher Mathematics is studied and the local-hierarchical Teaching Mode of Advanced Mathematics Course is introduced.%高等工程教育是我国高等教学的最重要组成部分，高等数学课程是高等工程教育中最重要的基础课程。本文对工科院校高等数学课程教学的现状进行分析，对工科院校高等数学课程教学改革进行研究，提出局部分层次教学模式的具体设计。
Institute of Scientific and Technical Information of China (English)
李孜
2015-01-01
中国在城镇化转型的过程中面临着严重的乡村社区衰落的问题，为了寻找契合信息化时代背景下乡村社区可持续发展模式，笔者深入遂昌县长期跟踪调研，通过分析总结遂昌县农村电子商务的发展，研究在互联网时代背景下，乡民如何结合新媒体工具与地域认同，再生社区凝聚力，进而实现可持续的乡村发展。%China is facing a serious rural decline in the fast urbanization. In order to find a mode of the sustainable development in rural community to adapt to the information age, this paper studies the development of the local rural e-commerce in Suichang County, and analyzes how the villagers employ the new media tools of the internet age and regional identity to regenerate the cohesion of rural community, and then realize the sustainable development of rural community.
Zhang, Zeshu; Pei, Jing; Wang, Dong; Gan, Qi; Ye, Jian; Yue, Jian; Wang, Benzhong; Povoski, Stephen P; Martin, Edward W; Hitchcock, Charles L; Yilmaz, Alper; Tweedle, Michael F; Shao, Pengfei; Xu, Ronald X
2016-01-01
Surgical resection remains the primary curative treatment for many early-stage cancers, including breast cancer. The development of intraoperative guidance systems for identifying all sites of disease and improving the likelihood of complete surgical resection is an area of active ongoing research, as this can lead to a decrease in the need of subsequent additional surgical procedures. We develop a wearable goggle navigation system for dual-mode optical and ultrasound imaging of suspicious lesions. The system consists of a light source module, a monochromatic CCD camera, an ultrasound system, a Google Glass, and a host computer. It is tested in tissue-simulating phantoms and an ex vivo human breast tissue model. Our experiments demonstrate that the surgical navigation system provides useful guidance for localization and core needle biopsy of simulated tumor within the tissue-simulating phantom, as well as a core needle biopsy and subsequent excision of Indocyanine Green (ICG)-fluorescing sentinel lymph nodes. Our experiments support the contention that this wearable goggle navigation system can be potentially very useful and fully integrated by the surgeon for optimizing many aspects of oncologic surgery. Further engineering optimization and additional in vivo clinical validation work is necessary before such a surgical navigation system can be fully realized in the everyday clinical setting.
Reform and innovation of practice teaching mode of law in local universities%地方性大学法学实践教学模式的改革与创新
Institute of Scientific and Technical Information of China (English)
何燕侠; 姜纪元; 蔺妍; 粱丽芳
2011-01-01
针对法学教育普遍存在的重理论、轻实践等问题,充分利用地方性大学的社会资源优势,构建符合应用型法律人才培养定位的实践教学体系,以社区法律诊所等为平台,强化实践教学成效,探索法学人才培养的新模式.%Aiming at the common problem of puiting more important on theories than on practice in our law education today, the advantage of a local university in respect of Us social resources should be taken, a professional skill training system is set up. Which corresponds our education goal of helping students become good law practitioners. This system IS based on the law clinics in the communities, in which the real effect of practicing and instruction is stressed, and by which a new mode of educating law professionals is explorted.
Directory of Open Access Journals (Sweden)
Zeshu Zhang
Full Text Available Surgical resection remains the primary curative treatment for many early-stage cancers, including breast cancer. The development of intraoperative guidance systems for identifying all sites of disease and improving the likelihood of complete surgical resection is an area of active ongoing research, as this can lead to a decrease in the need of subsequent additional surgical procedures. We develop a wearable goggle navigation system for dual-mode optical and ultrasound imaging of suspicious lesions. The system consists of a light source module, a monochromatic CCD camera, an ultrasound system, a Google Glass, and a host computer. It is tested in tissue-simulating phantoms and an ex vivo human breast tissue model. Our experiments demonstrate that the surgical navigation system provides useful guidance for localization and core needle biopsy of simulated tumor within the tissue-simulating phantom, as well as a core needle biopsy and subsequent excision of Indocyanine Green (ICG-fluorescing sentinel lymph nodes. Our experiments support the contention that this wearable goggle navigation system can be potentially very useful and fully integrated by the surgeon for optimizing many aspects of oncologic surgery. Further engineering optimization and additional in vivo clinical validation work is necessary before such a surgical navigation system can be fully realized in the everyday clinical setting.
Ostojic, Bojana; Schwerdtfeger, Peter; Bunker, Phil; Jensen, Per
2016-06-01
We present the results of ab initio calculations for the lower electronic states of the Group 15 (pnictogen) dihydrides, SbH_2 and BiH_2. For each of these molecules the two lowest electronic states become degenerate at linearity and are therefore subject to the Renner effect. Spin-orbit coupling is also strong in these two heavy-element containing molecules. For the lowest two electronic states of SbH_2, we construct the three dimensional potential energy surfaces and corresponding dipole moment and transition moment surfaces by multi-reference configuration interaction techniques. Including both the Renner effect and spin-orbit coupling, we calculate term values and simulate the rovibrational and rovibronic spectra of SbH_2. Excellent agreement is obtained with the results of matrix isolation infrared spectroscopic studies and with gas phase electronic spectroscopic studies in absorption [1,2]. For the heavier dihydride BiH_2 we calculate bending potential curves and the spin-orbit coupling constant for comparison. For SbH_2 we further study the local mode vibrational behavior and the formation of rovibronic energy level clusters in high angular momentum states. [1] X. Wang, P. F. Souter and L. Andrews, J. Phys. Chem. A 107, 4244-4249 (2003) [2] N. Basco and K. K. Lee, Spectroscopy Letters 1, 13-15 (1968)
Institute of Scientific and Technical Information of China (English)
刘春艳
2012-01-01
With higher education going into the stage of generalization, me increasingly society gives rise to quite a lot of problems and challenges to higher education. Local colleges and universities should construct student-centered mechanism of autonomous learning and diversified talent training modes. The management system of required course and elective credits as well as in-class and extracurricular credits is implemented and perfected and talents training mode is set up by establishing "Youchuang class" (outstanding innovation class) training system; "tutorial system" training and dynamic management mode is carried out to promote autonomous learning; student work and teaching complement each other to boost the construction of autonomous learning environment. "basic platform plus elective groups" curriculum system is established by constructing basic platforms of general education, disciplinary foundations and extra-curriculum programs and by setting up professional electives, disciplinary electives, humanities and other elective groups to stress students" personality development. Based on quaternary practical teaching system, the type and structure of teaching system is optimized; centered on "6S" projects, extra-curriculum education platform is constructed aiming at improving students" comprehensive qualities, thus, classroom practice and extracurricular practice are combined to set up ability training and all-round development teaching system. It aims to build innovative talents training mode, to develop and improve the comprehensive quality of talents training, and to meet the need of society for applied talents..%在高等教育大众化背景下，人才市场竞争日益激烈，高等学校人才培养面临诸多变化和挑战。地方院校应该以学生为中-D，构建自主学习机制和多样化人才培养格局。实行完善的课内外学分、必修课与选修课学分制度，通过建立“优创班”培养制度，确立优秀人才培养
Localized vibrations of graphene nanoribbons
Savin, A. V.; Kivshar, Yu. S.
2016-08-01
Vibrational modes of graphene nanoribbons are studied. It is demonstrated that in an unstretched graphene nanoribbon, localized vibrations (in the form of breathers) can occur only at the edges. The largest number of localized edge oscillations is expected for the nanoribbons with the armchair structure. Stretching of a nanoribbon can lead to the appearance of new types of strongly localized oscillations. When a nanoribbon is stretched, in its oscillatory spectrum a frequency gap appears in which the frequencies of the localized modes are located. An armchair nanoribbon can support localized modes only at its edges, while a highly stretched zigzag nanoribbon can support them both at the edges and inside the nanoribbon.
Institute of Scientific and Technical Information of China (English)
陈伟华
2009-01-01
Objective To assess the value of 18F-FDG PET cerebral 3D mode on the localizing the epileptic foci.Methods 13 patients with epilepsy,The brain scans with 3D mode were performed in all the patients.The images were analyzed by eyes and semi-quantitative method by two experienced nuclear medicine physicians.The scalp electroencephalogram(EEG)was performed in all the patients.Among them,Electrocorticogram (EcoG) or depth electroencephalogram were performed in 2 cases to verify the results of PET. MRI and/or CT were obtained in 12 cases.Results In 13 patients,92.3% was abnormal displaying hypometabolic foci on PET imaging(12/13cases).PET was more sensitive than EEG and MRI/CT to detect the lesions (92.3%、69.2% and 33.3%℅ respectively,χ2 were 14.3 and 35.0,all P<0.01).PET detected solitary lesion in 61.5% of patients, more higher than EEG(61.5% vs 38.4%,χ2 was 23.1, P<0.01). Comparing with golden standard of EcoG or depth electroencephalogram,the sensitivity and specificity of PET to localize the epileptic foci were 95% and 89%.Conclusion 18F-FDG PET is a sensitive and accurate image modality on the localizing the epileptic foci. It is useful to direct surgical treatment and orientating radiation therapy.%目的 研究18F-FDG PET-CT脑3D显像对致痫灶定位的应用价值.方法 癫痫患者13例,皆行18F-FDG脑三维PET显像,通过目测和半定量方法分析图像.所有患者均行EEG检查,其中2例行皮层脑电图(EcoG)或深部脑电图(DEEG);12例行脑MRI或CT检查.结果 (1)13例中,PET阳性表现为低代谢灶者检出率为92.3%(12/13例),明显高于EEG和脑MRI/CT(分别为92.3%、69.2%、33.3%,χ2分别为14.3、35.0,P均<0.01).单病灶检出率PET明显高于EEG(分别为61.5%和38.4%,χ2=23.1,P<0.01).与皮层脑电图(EcoG)或深部脑电图(DEEG)相比较,PET对致痫灶的检出灵敏度为95%,定位准确性为89%.结论 18F-FDG PET在致痫灶的检出及定位方面有较高的灵敏度和准确性;在引导癫痫外科手术
Experimental phase-space-based optical amplification of scar modes
Michel, Claire; Doya, Valerie; Aschieri, Pierre; Blanc, Wilfried; Legrand, Olivier; Mortessagne, Fabrice
2012-01-01
Waves billiard which are chaotic in the geometrical limit are known to support non-generic spatially localized modes called scar modes. The interaction of the scar modes with gain has been recently investigated in optics in micro-cavity lasers and vertically-cavity surface-emitting lasers. Exploiting the localization properties of scar modes in their wave analogous phase space representation, we report experimental results of scar modes selection by gain in a doped D-shaped optical fiber.
Causality and Primordial Tensor Modes
Baumann, Daniel
2009-01-01
We introduce the real space correlation function of $B$-mode polarization of the cosmic microwave background (CMB) as a probe of superhorizon tensor perturbations created by inflation. By causality, any non-inflationary mechanism for gravitational wave production after reheating, like global phase transitions or cosmic strings, must have vanishing correlations for angular separations greater than the angle subtended by the particle horizon at recombination, i.e. $\\theta \\gtrsim 2^\\circ$. Since ordinary $B$-modes are defined non-locally in terms of the Stokes parameters $Q$ and $U$ and therefore don't have to respect causality, special care is taken to define `causal $\\tilde B$-modes' for the analysis. We compute the real space $\\tilde B$-mode correlation function for inflation and discuss its detectability on superhorizon scales where it provides an unambiguous test of inflationary gravitational waves. The correct identification of inflationary tensor modes is crucial since it relates directly to the energy s...
Institute of Scientific and Technical Information of China (English)
黄倩
2013-01-01
教师的专业发展是教学部门开展的职后教师教育工作的目标追求。一些高校基校情开始或已经探索出了具有本校特色的外语教师专业发展模式。德州学以“自我”为资，采取有组织的干预性合作发展模式，通过构建教师学习群体和实践共同体，走出了从外在驱动到内在自觉的“本土化”大学英语专业发展之路，并取得了一定的实效。%Teacher’s professional development is aiming at the ultimate professional pursuit for in -service teachers based on the department itself.Some universities have started the professional development for teachers of foreign language on the ba -sis of their local environment .Dezhou Foreign Language Teaching Department has moved on the so -called localized foreign language teacher’s professional development , starting from the objective analysis of the current situation of the faculty , adop-ting interferential bounded cooperation mode and taking “self” as resources to improve classroom teaching .Commonwealth of learning and communities of practice has been constructed to realize the goal of localization of professional development for teachers of foreign language.
Hardware Assisted ROP Detection Mode (HARD Mode)
2013-08-01
Distribution A. Cleared for public release; unlimited distribution. USAFA-CN-2013-457 Hardware Assisted ROP Detection Mode (HARD Mode) NATHANIEL HART...457 This report, "Hardware Assisted ROP Detection Mode (HARD Mode)" is presented as a competent treatment of the subj ect, worthy of publication. The...Technical 20120810-20121215 Hardware Assisted ROP Detection Mode (HARD Mode) NATHANIEL HART MICHAEL WINSTEAD MARTIN CARLISLE RODNEY LYKINS MICHAEL
Effects of Mode Shares on Mode Choice
Carlos Carrion; Nebiyou Tilahun; David Levinson
2011-01-01
This study considers the influence of the knowledge of existing mode shares on travelers mode choice. This contrasts with traditional mode choice models, where the main objective is to predict the overall mode shares as the aggregate of individual mode choices according to variables encompassing attributes of the modes, and characteristics of the travelers. In this study, a computer-administered adaptive stated preference survey is developed and applied to a sample of subjects selected from t...
Energy Technology Data Exchange (ETDEWEB)
Chen, J.; Nakajima, N.; Okamoto, M.
1998-12-01
By means of a global mode analysis of ideal MHD modes for Mercier-unstable equilibria in a planar axis L=2/M=10 heliotron/torsatron system with an inherently large Shafranov shift, the conjecture from local mode analysis for Mercier-unstable equilibria given in [N. Nakajima, Phys. Plasmas 3, 4556 (1996)] has been confirmed and the properties of pressure-driven modes, namely, ballooning modes and interchange modes, inherent to such three-dimensional systems have been clarified. The change of the local magnetic shear due to the Shafranov shift, which is related to toroidicity, reduces the field line bending stabilizing effects on ballooning modes. According to the degree of the reduction of the local magnetic shear by the Shafranov shift, the Mercier-unstable equilibria are categorized into toroidicity-dominant (strong reduction) and helicity-dominant (weak reduction) Mercier-unstable equilibria. Since the local magnetic curvature due to helicity has the same period M in the toroidal direction as the toroidal field period of the equilibria, the characteristics of the pressure-driven modes in such Mercier-unstable equilibria dramatically change, both according to the reduction of the local magnetic shear by the Shafranov shift and also according to the relative magnitude of the typical toroidal mode number n of the perturbation compared with the toroidal field period of the equilibria M. In the toroidicity-dominant Mercier-unstable equilibria, the pressure-driven modes change from interchange modes for low toroidal mode numbers n < M, to tokamak-like poloidally localized ballooning modes with a weak toroidal mode coupling for moderate toroidal mode numbers n - M, and finally to both poloidally and toroidally localized ballooning modes purely inherent to three-dimensional systems for fairly high toroidal mode numbers n >> M. In the helicity-dominant Mercier-unstable equilibria, the pressure-driven modes change from interchange modes for n < M or n - M, directly to both
Institute of Scientific and Technical Information of China (English)
吕岿; 童国平; 毛杰健
2012-01-01
The lattice vibration equations of a diatomic chain with an impurity atom and on-site potential are solved. The analytic solutions of local vibration are obtained. The basic features of the effect of on-site potential on the local vibration are given, and the existence forms of localized mode are also discussed. With the on-site potential existence , it is found that the frequency of the high frequency mode and gap vibration mode increase, the degree of locality get better and the new local vibration mode are generated in the acoustic branch and optical branch, which means the disperse relation of the lattice vibration is effected markedly by the on-site potential.%对具有在位势且含杂质的一维双原子链的晶格振动方程组进行求解,得到了局域振动的解析解,给出了在位势对局域振动影响的基本特征,并简要讨论了局域模的存在形式.通过研究发现,在位势的存在使得杂质产生的高频模和隙模的频率升高,局城性变好,于一定条件下在声学支内和光学支内产生新的局域模,从而显著影响了晶格局城振动的色散关系.
Lyapunov modes in extended systems.
Yang, Hong-Liu; Radons, Günter
2009-08-28
Hydrodynamic Lyapunov modes, which have recently been observed in many extended systems with translational symmetry, such as hard sphere systems, dynamic XY models or Lennard-Jones fluids, are nowadays regarded as fundamental objects connecting nonlinear dynamics and statistical physics. We review here our recent results on Lyapunov modes in extended system. The solution to one of the puzzles, the appearance of good and 'vague' modes, is presented for the model system of coupled map lattices. The structural properties of these modes are related to the phase space geometry, especially the angles between Oseledec subspaces, and to fluctuations of local Lyapunov exponents. In this context, we report also on the possible appearance of branches splitting in the Lyapunov spectra of diatomic systems, similar to acoustic and optical branches for phonons. The final part is devoted to the hyperbolicity of partial differential equations and the effective degrees of freedom of such infinite-dimensional systems.
Free-Boundary Resistive Modes in Tokamaks
Huysmans, G. T. A.; Goedbloed, J. P.; Kerner, W.
1993-01-01
There exist a number of observations of magnetohydrodynamic (MHD) activity that can be related to resistive MHD modes localized near the plasma boundary. To study the stability of these modes, a free boundary description of the plasma is essential. The resistive plasma-vacuum boundary conditions hav
Causality and primordial tensor modes
Energy Technology Data Exchange (ETDEWEB)
Baumann, Daniel; Zaldarriaga, Matias, E-mail: dbaumann@physics.harvard.edu, E-mail: mzaldarriaga@cfa.harvard.edu [Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, U.S.A. and Center for Astrophysics, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States)
2009-06-01
We introduce the real space correlation function of B-mode polarization of the cosmic microwave background (CMB) as a probe of superhorizon tensor perturbations created by inflation. By causality, any non-inflationary mechanism for gravitational wave production after reheating, like global phase transitions or cosmic strings, must have vanishing correlations for angular separations greater than the angle subtended by the particle horizon at recombination, i.e. θ ∼> 2°. Since ordinary B-modes are defined non-locally in terms of the Stokes parameters Q and U and therefore don't have to respect causality, special care is taken to define 'causal B-tilde -modes' for the analysis. We compute the real space B-tilde -mode correlation function for inflation and discuss its detectability on superhorizon scales where it provides an unambiguous test of inflationary gravitational waves. The correct identification of inflationary tensor modes is crucial since it relates directly to the energy scale of inflation. Wrongly associating tensor modes from causal seeds with inflation would imply an incorrect inference of the energy scale of inflation. We find that the superhorizon B-tilde -mode signal is above cosmic variance for the angular range 2° < θ < 4° and is therefore in principle detectable. In practice, the signal will be challenging to measure since it requires accurately resolving the recombination peak of the B-mode power spectrum. However, a future CMB satellite (CMBPol), with noise level Δ{sub P} ≅ 1μK-arcmin and sufficient resolution to efficiently correct for lensing-induced B-modes, should be able to detect the signal at more than 3σ if the tensor-to-scalar ratio isn't smaller than r ≅ 0.01.
Measurement of the profiles of disorder-induced localized resonances by local tuning
Lian, J; Yüce, E; Combrié, S; De Rossi, A; Mosk, A P; .,
2016-01-01
Near the band edge of photonic crystal waveguides, localized modes appear due to disorder. We demonstrate a new method to elucidate spatial profile of the localized modes in such systems using precise local tuning. Using deconvolution with the known thermal profile, the spatial profile of a localized mode with quality factor ($Q$) $>10^5$ is successfully reconstructed with a resolution of $2.5 \\ \\mu $m.
Voltage Mode-to-Current Mode Transformation
Directory of Open Access Journals (Sweden)
Tejmal S. Rathore
2012-10-01
Full Text Available This paper proposes a procedure for converting a class of Op Amp-, FTFN-, CC- and CFAbased voltage mode circuits to corresponding current mode circuits without requiring any additional circuit elements and finally from Op Amp-based voltage mode circuits to any of the FTFN, CC and CFA current mode circuits. The latter circuits perform better at high frequency than the former ones. The validity of the transformation has been checked on simulated circuits with PSPICE.
Mode Transitions in Hall Effect Thrusters
Sekerak, Michael J.; Longmier, Benjamin W.; Gallimore, Alec D.; Brown, Daniel L.; Hofer, Richard R.; Polk, James E.
2013-01-01
Mode transitions have been commonly observed in Hall Effect Thruster (HET) operation where a small change in a thruster operating parameter such as discharge voltage, magnetic field or mass flow rate causes the thruster discharge current mean value and oscillation amplitude to increase significantly. Mode transitions in a 6-kW-class HET called the H6 are induced by varying the magnetic field intensity while holding all other operating parameters constant and measurements are acquired with ion saturation probes and ultra-fast imaging. Global and local oscillation modes are identified. In the global mode, the entire discharge channel oscillates in unison and azimuthal perturbations (spokes) are either absent or negligible. Downstream azimuthally spaced probes show no signal delay between each other and are very well correlated to the discharge current signal. In the local mode, signals from the azimuthally spaced probes exhibit a clear delay indicating the passage of "spokes" and are not well correlated to the discharge current. These spokes are localized oscillations propagating in the ExB direction that are typically 10-20% of the mean value. In contrast, the oscillations in the global mode can be 100% of the mean value. The transition between global and local modes occurs at higher relative magnetic field strengths for higher mass flow rates or higher discharge voltages. The thrust is constant through mode transition but the thrust-to-power decreased by 25% due to increasing discharge current. The plume shows significant differences between modes with the global mode significantly brighter in the channel and the near-field plasma plume as well as exhibiting a luminous spike on thruster centerline. Mode transitions provide valuable insight to thruster operation and suggest improved methods for thruster performance characterization.
Institute of Scientific and Technical Information of China (English)
潘自影
2014-01-01
The article ,from the definition of bureaucratic theory ,analyzes the current develop-ment situation of bureaucracy in China and concludes that it is in the deficiency stage of bureaucrati-zation ,while the administrative decision-making system mode of the local government can learn much from the bureaucratic theory .The infiltration of many ideas of traditional bureaucratic system into the administrative decision-making mode of the local government leads to many problems in the operation of existing mode .The author ,on the basis of China’s specific national conditions ,through the rational reference and surpass of bureaucratic system ,puts forward optimization way for administrative decision-making system mode of local government .%文章从对官僚制理论的界定入手，分析了官僚制在中国的发展现状为处于官僚化不足阶段，而官僚制理论对于我国地方政府的行政决策体制模式仍有许多可借鉴之处。由于传统官僚制的许多观念依然在我国地方政府的行政决策体制模式之中有所渗透，导致现有模式在运行中出现诸多问题，笔者结合我国的具体国情，通过对理性官僚制的借鉴和超越，提出了对我国地方政府行政决策体制模式的优化路径。
Viscous, Resistive Magnetorotational Modes
Pessah, Martin E
2008-01-01
We carry out a comprehensive analysis of the behavior of the magnetorotational instability (MRI) in viscous, resistive plasmas. We find exact, non-linear solutions of the non-ideal magnetohydrodynamic (MHD) equations describing the local dynamics of an incompressible, differentially rotating background threaded by a vertical magnetic field when disturbances with wavenumbers perpendicular to the shear are considered. We provide a geometrical description of these viscous, resistive MRI modes and show how their physical structure is modified as a function of the Reynolds and magnetic Reynolds numbers. We demonstrate that when finite dissipative effects are considered, velocity and magnetic field disturbances are no longer orthogonal (as it is the case in the ideal MHD limit) unless the magnetic Prandtl number is unity. We generalize previous results found in the ideal limit and show that a series of key properties of the mean Reynolds and Maxwell stresses also hold for the viscous, resistive MRI. In particular, ...
On radial geodesic forcing of zonal modes
Kendl, Alexander
2011-01-01
The elementary local and global influence of geodesic field line curvature on radial dispersion of zonal modes in magnetised plasmas is analysed with a primitive drift wave turbulence model. A net radial geodesic forcing of zonal flows and geodesic acoustic modes can not be expected in any closed toroidal magnetic confinement configuration, since the flux surface average of geodesic curvature identically vanishes. Radial motion of poloidally elongated zonal jets may occur in the presence of geodesic acoustic mode activity. Phenomenologically a radial propagation of zonal modes shows some characteristics of a classical analogon to second sound in quantum condensates.
Resistive interchange modes and plasma flow structures
Paccagnella, Roberto
2011-10-01
Interchange modes are ubiquitous in magnetic confinement systems and are likely to determine or influence their transport properties. For example a good agreement between theory predictions for linear interchange modes and experimental results has been found recently in a Reverse Field Pinch device. In this work a set of magneto-hydro-dynamic (MHD) equations that describe the dynamical evolution for the pressure driven interchange modes in a magnetic confinement system are studied. Global and local solutions relevant for tokamaks and Reversed Field Pinches (RFPs) configurations are considered. The emphasis is especially in the characterization of the plasma flow structures associated with the dominant modes.
Failure Modes of thin supported Membranes
DEFF Research Database (Denmark)
Hendriksen, Peter Vang; Høgsberg, J.R.; Kjeldsen, Ane Mette;
2007-01-01
Four different failure modes relevant to tubular supported membranes (thin dense films on a thick porous support) were analyzed. The failure modes were: 1) Structural collapse due to external pressure 2) burst of locally unsupported areas, 3) formation of surface cracks in the membrane due to TEC......-mismatches, and finally 4) delamination between membrane and support due to expansion of the membrane on use. Design criteria to minimize risk of failure by the four different modes are discussed. The theoretical analysis of the two last failure modes is compared to failures observed on actual components....
Locally localized gravity and geometric transitions
Energy Technology Data Exchange (ETDEWEB)
Bazeia, Dionisio [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58051-970 Joao Pessoa, Paraiba (Brazil)]. E-mail: bazeia@fisica.ufpb.br; Brito, Francisco A. [Departamento de Fisica, Universidade Federal de Campina Grande, 58109-970 Campina Grande, Paraiba (Brazil); Gomes, Adalto Rodrigues [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58051-970 Joao Pessoa, Paraiba (Brazil); Departamento de Ciencias Exatas, Centro Federal de Educacao Tecnologica do Maranhao, 65025-001 Sao Luis, Maranhao (Brazil)
2004-11-01
In this paper we analyze the local localization of gravity in AdS{sub 4} thick brane embedded in AdS{sub 5} space. The 3-brane is modelled by domain wall solution of a theory with a bulk scalar field coupled to five-dimensional gravity. In addition to small four-dimensional cosmological constant, the vacuum expectation value (vev) of the scalar field controls the emergence of a localized four-dimensional quasi-zero mode. We introduce high temperature effects, and we show that gravity localization on a thick 3-brane is favored below a critical temperature T{sub c}. These investigations suggest the appearance of another critical temperature T*, where the thick 3-brane engenders the geometric (author)
Tapping mode microwave impedance microscopy
Lai, K.
2009-01-01
We report tapping mode microwave impedance imaging based on atomic force microscope platforms. The shielded cantilever probe is critical to localize the tip-sample interaction near the tip apex. The modulated tip-sample impedance can be accurately simulated by the finite-element analysis and the result agrees quantitatively to the experimental data on a series of thin-film dielectric samples. The tapping mode microwave imaging is also superior to the contact mode in that the thermal drift in a long time scale is totally eliminated and an absolute measurement on the dielectric properties is possible. We demonstrated tapping images on working nanodevices, and the data are consistent with the transport results. © 2009 American Institute of Physics.
Instability of vibrational modes in hexagonal lattice
Korznikova, Elena A.; Bachurin, Dmitry V.; Fomin, Sergey Yu.; Chetverikov, Alexander P.; Dmitriev, Sergey V.
2017-02-01
The phenomenon of modulational instability is investigated for all four delocalized short-wave vibrational modes recently found for the two-dimensional hexagonal lattice with the help of a group-theoretic approach. The polynomial pair potential with hard-type quartic nonlinearity ( β-FPU potential with β > 0) is used to describe interactions between atoms. As expected for the hard-type anharmonic interactions, for all four modes the frequency is found to increase with the amplitude. Frequency of the modes I and III bifurcates from the upper edge of the phonon spectrum, while that of the modes II and IV increases from inside the spectrum. It is also shown that the considered model supports spatially localized vibrational mode called discrete breather (DB) or intrinsic localized mode. DB frequency increases with the amplitude above the phonon spectrum. Two different scenarios of the mode decay were revealed. In the first scenario (for modes I and III), development of the modulational instability leads to a formation of long-lived DBs that radiate their energy slowly until thermal equilibrium is reached. In the second scenario (for modes II and IV) a transition to thermal oscillations of atoms is observed with no formation of DBs.
Locally Localized Gravity: The Inside Story
Kaloper, Nemanja; Kaloper, Nemanja; Sorbo, Lorenzo
2005-01-01
We derive the exact gravitational field of a relativistic particle localized on an $AdS$ 3-brane, with curvature radius $\\ell$, in $AdS_5$ bulk with radius $L$. The solution is a gravitational shock wave. We use it to explore the dynamics of locally localized tensor gravitons over a wide range of scales. At distances below $L$ the shock wave looks exactly like the $5D$ $GR$ solution. Beyond $L$ the solution approximates very closely the shock wave in 4D $AdS$ space all the way out to distances $\\ell^3/L^2$ along the brane. At distances between $L$ and $\\ell$, the effective 4D graviton is a composite built of the ultralight mode and heavier gravitons, whereas between $\\ell$ and $\\ell^3/L^2$ it is just the ultralight mode. Finally beyond $\\ell^3/L^2$ the shock reveals a glimpse of the fifth dimension, since the ultralight mode wave function decays to zero at the rate inherited from the full $5D$ geometry. We obtain the precise bulk-side formula for the 4D Planck mass, defined as the coupling of the ultralight m...
CMB Anisotropies from a Gradient Mode
Mirbabayi, Mehrdad
2014-01-01
A pure gradient mode must have no observable dynamical effect at linear level. We confirm this by showing that its contribution to the dipolar power asymmetry of CMB anisotropies vanishes, if Maldacena's consistency condition is satisfied. To this end, the existing second order Sachs-Wolfe formula in the squeezed limit is extended to include a gradient in the long mode and to account for the change in the location of the last scattering surface induced by this mode. At second order, a gradient mode generated in Single-field inflation is shown to induce a quadrupole moment. For instance in a matter-dominated model it is equal to 5/18 times the square of the linear gradient part. This quadrupole can be cancelled by superposing a quadratic perturbation. The result is shown to be a non-linear extension of Weinberg's adiabatic modes: a long-wavelength physical mode which looks locally like a coordinate transformation.
CMB anisotropies from a gradient mode
Mirbabayi, Mehrdad; Zaldarriaga, Matias
2015-03-01
A linear gradient mode must have no observable dynamical effect on short distance physics. We confirm this by showing that if there was such a gradient mode extending across the whole observable Universe, it would not cause any hemispherical asymmetry in the power of CMB anisotropies, as long as Maldacena's consistency condition is satisfied. To study the effect of the long wavelength mode on short wavelength modes, we generalize the existing second order Sachs-Wolfe formula in the squeezed limit to include a gradient in the long mode and to account for the change in the location of the last scattering surface induced by this mode. Next, we consider effects that are of second order in the long mode. A gradient mode Φ = qṡx generated in Single-field inflation is shown to induce an observable quadrupole moment. For instance, in a matter-dominated model it is equal to Q = 5(qṡx)2/18. This quadrupole can be canceled by superposition of a quadratic perturbation. The result is shown to be a nonlinear extension of Weinberg's adiabatic modes: a long-wavelength physical mode which looks locally like a coordinate transformation.
Effect of pure mode I, II or III loading or mode mixity on crack growth in a homogeneous solid
DEFF Research Database (Denmark)
Tvergaard, Viggo
2010-01-01
the maximum. The reason for this is discussed in terms of the local stress and strain fields around the tip. For pure mode II or mode Ill loading it is shown that there is no maximum before the steady-state. Also results for different mixed mode conditions are presented and discussed in relation...
Tunable degree of localization in random lasers with controlled interaction
Leonetti, Marco; Lopez, Cefe
2012-01-01
We show that the degree of localization for the modes of a random laser (RL) is affected by the inter mode interaction that is controlled by shaping the spot of the pump laser. By experimentally investigating the spatial properties of the lasing emission we infer that strongly localized modes are activated in the low interacting regime while in the strongly interacting one extended modes are found lasing. Thus we demonstrate that the degree o localization may be finely tuned at the micrometer level.
Lian, J.; Sokolov, S.; Yuce, E.; Combrie, S.; Rossi, de A.; Mosk, A.P.
2016-01-01
Near the band edge of photonic crystal waveguides, localized modes appear due to disorder. We demonstrate a new method to elucidate spatial profile of the localized modes in such systems using precise local tuning. Using deconvolution with the known thermal profile, the spatial profile of a localize
Institute of Scientific and Technical Information of China (English)
周群
2012-01-01
Canadian CBE mode is an advanced vocational education thought. China＇s railway industry vocational education began to draw on the concept of Canadian vocational education from the 1990s. In the 21st century, based on the practice of the CBE mode, railway vocational education reform of China came to the deep of post-- based teaching and learning. The post-- based teaching and learning is the localization of the CBE mode,including curriculum development localization, training base construction localization, professional quality training localization and talent evaluation localization. From CBE to post-- based teaching and learning, it fully reflects the history of reform development of the railway vocational education in China. Of course, it is not difficult to find, our government still has some problems in vocational education such as the absence of legal provisions in vocational education--related links, some improper clauses related to the vocational education law, enterprise entity missing and so on.%加拿大CBE模式是一种先进的职业教育思想。我国铁路行业职业教育从20世纪90年代开始借鉴加拿大职业教育观念。进入21世纪以后，在实践CBE模式的基础上，我国铁路职业教育改革进入“以岗导学”形态的深水区。“以岗导学”是CBE模式的本土化，包括课程开发本土化、实训基地建设本土化、职业素质培养本土化，人才评价本土化。从CBE到以岗导学，充分反映了我国铁路职业教育的改革发展历程。当然，也不难发现，我国政府在职业教育相关环节还有缺位现象。以及职业教育法律相关条款不当和企业主体缺失等问题。
Impurity modes in the one-dimensional XXZ Heisenberg model
Energy Technology Data Exchange (ETDEWEB)
Sousa, J.M. [Departamento de Física, Universidade Federal do Piauí, Campus Ministro Petrônio Portella, 57072-970 Teresina, Piauí (Brazil); Leite, R.V. [Centro de Ciências Exatas e Tecnologia, Curso de Física, Universidade Estadual Vale do Acaraú, Av. Dr. Guarany 317, Campus Cidao, 62040-730 Sobral, Ceará (Brazil); Landim, R.R. [Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceará (Brazil); Costa Filho, R.N., E-mail: rai@fisica.ufc.br [Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceará (Brazil)
2014-04-01
A Green's function formalism is used to calculate the energy of impurity modes associated with one and/or two magnetic impurities in the one-dimensional Heisenberg XXZ magnetic chain. The system can be tuned from the Heisenberg to the Ising model varying a parameter λ. A numerical study is performed showing two types of localized modes (s and p). The modes depend on λ and the degeneracy of the acoustic modes is broken.
Institute of Scientific and Technical Information of China (English)
刘爱丽
2015-01-01
The talents cultivation mode of Tourism Management major of local universities and colleges is confronted with problems including failures to match the needs of society,outdated curriculum content,featureless curriculum setting,structural imbalances,etc. With innovation ability as the core of cultivation,local universities and colleges should identify professional orien-tation and training objectives;deepen the teaching content and build innovative practices platform through improving the curricu-lum system,and innovate the cultivation mode of applied talents with high quality.%地方高校旅游管理专业人才培养模式存在着培养目标与社会需求相脱节；课程内容滞后，亟待更新；课程设置无特色，结构失衡等问题。人才的培养是高等教育的重要任务，在地方高校转型发展的历史时期，地方高校应明确专业定位和培养目标，通过完善课程体系建设，深化教学内容、搭建创新实践平台等措施，创新应用型人才培养模式，提升应用型人才质量。
On radial geodesic forcing of zonal modes
Kendl, Alexander
2011-01-01
The elementary local and global influence of geodesic field line curvature on radial dispersion of zonal modes in magnetised plasmas is analysed with a primitive drift wave turbulence model. A net radial geodesic forcing of zonal flows and geodesic acoustic modes can not be expected in any closed toroidal magnetic confinement configuration, since the flux surface average of geodesic curvature identically vanishes. Radial motion of poloidally elongated zonal jets may occur in the presence of g...
Few-mode fibers for mode division multiplexing transmission
Kubota, Hirokazu; Morioka, Toshio
2012-01-01
A study is presented of the fiber properties needed to achieve 10-mode multiplexing transmission. A combination of MIMO processing with optical LP mode separation is proposed to prevent the need for massive MIMO computation. The impact of mode crosstalk, differential mode delay, and the mode dependent loss of the few-mode fibers on mode multiplexing are discussed.
Inmunoterapia local Local immunotherapy
Directory of Open Access Journals (Sweden)
E. Lasa
2003-01-01
Full Text Available La inmunoterapia específica, junto con la evitación del alergeno y el tratamiento sintomático, forma parte del tratamiento de la patología alérgica. La modalidad más antigua, más conocida y mejor estudiada es la inmunoterapia subcutánea (ITSC, cuya eficacia tanto a corto como a largo plazo, ha sido ampliamente demostrada en numerosos estudios. Sin embargo, a pesar de haberse demostrado segura, no está exenta de efectos adversos y precisa ser administrada bajo supervisión de personal médico. Esto ha animado a buscar nuevas vías de administración de eficacia similar, con un buen perfil de seguridad, y de buena cumplimentación por parte del paciente. De las distintas alternativas estudiadas la más relevante es la inmunoterapia sublingual (ITSL. En ésta, se administra el antígeno en forma de gotas debajo de la lengua. Existen diferentes pautas de administración en función del alergeno implicado. La dosis óptima de tratamiento está aún sin determinar, hallándose en este momento en un rango amplio de dosis respecto a la inmunoterapia subcutánea. Su mecanismo de acción es poco conocido aunque en diversos estudios se han observado cambios inmunológicos. La ITSL ha mostrado un buen perfil de seguridad con escasos efectos secundarios, habitualmente de carácter local. Asimismo se han realizado distintos ensayos clínicos en los que se ha demostrado su eficacia en el tratamiento de la alergia respiratoria tanto en niños como en adultos. Por ello, aunque aún existen datos sin resolver respecto a esta vía de administración de inmunoterapia, ha sido propuesta por la OMS como una alternativa válida a la ITSC.Specific immunotherapy, together with avoidance of the allergen and symptomatic treatment, forms part of the treatment of allergic pathology. The oldest, best known and most studied form is subcutaneous immunotherapy (SCIT, whose efficacy, both in the short and the long term, has been widely demonstrated in numerous studies
Institute of Scientific and Technical Information of China (English)
蔡红梅
2014-01-01
基于对“全学程双导师制”产生背景和内涵的分析，本研究指出了“全学程双导师制”职前英语教师培养模式实施的必要性，并在此基础上提出了在地方师范院校英语专业职前英语教师培养过程中实施“全学程双导师制”的构想，即由地方师范院校英语专业教育教学理论指导教师和中小学教育实践基地优秀英语实践指导教师共同承担职前英语教师的培养任务，在时间上将“双导师制”贯穿于英语专业职前英语教师培养的全过程，在空间上将师范院校的教育教学和基础教育教学实践结合起来，以达到培养高素质英语师资的目的。%Based on the analysis of the background and perceptions of "whole-course dual tutorial system"and the necessity for implementing the"whole-course dual tutorial system"pre-service teacher training mode , this thesis advances the pro-posal of implementing the teacher training mode in pre -service English teacher training at local normal college , that is, both the tutors at the English Department at local college and the mentors at local schools are involved in co -training pre-service English teachers with the mode running throughout the whole course of pre -service English teacher training programs in time and combining the theoretical training at local college with the teaching practices at basic education scenes in space , thus a-chieving the goal of training high -quality English teachers .
Cox, Richard J
1996-01-01
Now in paperback! Documenting Localities is the first effort to summarize the past decade of renewed discussion about archival appraisal theory and methodology and to provide a practical guide for the documentation of localities.This book discusses the continuing importance of the locality in American historical research and archival practice, traditional methods archivists have used to document localities, and case studies in documenting localities. These chapters draw on a wide range of writings from archivists, historians, material culture specialists, historic preservationists
Complex coupled-mode theory for tapered optical waveguides.
Mu, Jianwei; Huang, Wei-Ping
2011-03-15
A coupled-mode formulation based on complex local modes is developed for tapered and longitudinally varying optical waveguides. Different from the conventional coupled-mode theory that requires integration over the entire spectrum of radiation modes, the new formulation treats the radiation fields via discrete complex modes similarly to the guided modes. Accuracy, convergence, and scope of validity for the solutions of the complex coupled-mode equations are investigated in detail for a typical single-mode waveguide taper. It is demonstrated that the complex coupled-mode theory has overcome the difficulties of the conventional theory in simulation of radiation field effects while preserving the simplicity and intuitiveness of this popular method.
Lian, Jin; Sokolov, Sergei; Yüce, Emre; Combrié, Sylvain; De Rossi, Alfredo; Mosk, Allard P.
2016-09-01
Near the band edge of photonic crystal waveguides, localized modes appear due to disorder. We demonstrate a new method to elucidate spatial profile of the localized modes in such systems using precise local tuning. Using deconvolution with the known thermal profile, the spatial profile of a localized mode with quality factor ($Q$) $>10^5$ is successfully reconstructed with a resolution of $2.5 \\ \\mu $m.
DEFF Research Database (Denmark)
2014-01-01
The invention relates to a semiconductor mode selection laser, particularly to a VCSEL laser (200) having mode selection properties. The mode selection capability of the laser is achieved by configuring one of the reflectors (15,51) in the resonance cavity so that a reflectivity of the reflector...... (15) varies spatially in one dimension or two dimensions. Accordingly, the reflector (15) with spatially varying reflectivity is part both of the resonance cavity and the mode selection functionality of the laser. A plurality of the lasers configured with different mode selectors, i.e. different...... spatial reflector variations, may be combined to generate a laser beam containing a plurality of orthogonal modes. The laser beam may be injected into a few- mode optical fiber, e.g. for the purpose of optical communication. The VCSEL may have intra-cavity contacts (31,37) and a Tunnel junction (33...
Institute of Scientific and Technical Information of China (English)
齐珍珍
2011-01-01
In the background of popularization of higher education, the traditional mode of elite higher education need to change.At the same time,higher education keep even closer contact with regional economic development.To reform the training model is the important reflection as higher education support active service to the social and economic.From the training objectives, training content, training methods and paths and other aspects of the institutes and service personnel training model's basic features are described, in order to have some reference for the reform of personnel training.%在高等教育大众化进程的时代背景下,传统精英高等教模式需要转变,同时,高等教育与区域经济发展的联系日益密切,改革人才培养模式,是高等教育主动服务社会经济的重要体现.本文从培养目标、培养内容、培养方式和路径等方面阐述了地方本科高校服务型人才培养模式的基本特色,以期对人才培养改革有一定的借鉴意义.
Larsson, Anders; Gustavsson, Johan S.
The only active transverse mode in a truly single-mode VCSEL is the fundamental mode with a near Gaussian field distribution. A single-mode VCSEL produces a light beam of higher spectral purity, higher degree of coherence and lower divergence than a multimode VCSEL and the beam can be more precisely shaped and focused to a smaller spot. Such beam properties are required in many applications. In this chapter, after discussing applications of single-mode VCSELs, we introduce the basics of fields and modes in VCSELs and review designs implemented for single-mode emission from VCSELs in different materials and at different wavelengths. This includes VCSELs that are inherently single-mode as well as inherently multimode VCSELs where higher-order modes are suppressed by mode selective gain or loss. In each case we present the current state-of-the-art and discuss pros and cons. At the end, a specific example with experimental results is provided and, as a summary, the most promising designs based on current technologies are identified.
Language Differences and Operation Mode
DEFF Research Database (Denmark)
Dasi, Angels; Pedersen, Torben
2013-01-01
for a foreign market, so that language distance matters in the case of a home-based sales force, while language incidence is key when operating through a local agent. The hypotheses are tested on a large data set encompassing 462 multinational corporations headquartered in Finland, South Korea, New Zealand......Language serves different purposes depending on the international activity in question. Language has many dimensions and firms’ communicative requirements vary by operational platform. We argue that different dimensions of language vary in their importance depending on the operation mode chosen...
Tunable rotary orbits of matter-wave nonlinear modes in attractive Bose-Einstein condensates
Energy Technology Data Exchange (ETDEWEB)
He, Y J; Wang, H Z [State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou, 510275 (China); Malomed, Boris A [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Mihalache, Dumitru [Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), 407 Atomistilor, Magurele-Bucharest 077125 (Romania)], E-mail: stswhz@mail.sysu.edu.cn
2008-03-14
We demonstrate that by spatially modulating the Bessel optical lattice where a Bose-Einstein condensate is loaded, we get tunable rotary orbits of nonlinear lattice modes. We show that the radially expanding or shrinking Bessel lattice can drag the nonlinear localized modes to orbits of either larger or smaller radii and the rotary velocity of nonlinear modes can be changed accordingly. The localized modes can even be transferred to the Bessel lattice core when the localized modes' rotations are stopped. Effects beyond the quasi-particle approximation such as destruction of the nonlinear modes by nonadiabatic dragging are also explored.
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
Local architecture refers to structures built in the countryside,such as temples,memorial halls,residences, stores,pavilions, bridges,decorated archways, and wells. Because these structures were all built by focal craftsmen and villagers in the traditional local style, they are generally called local architecture.
Kotlyar, V V; Kovalev, A A; Soifer, V A
2014-04-15
We propose a new, three-parameter family of diffraction-free asymmetric elegant Bessel modes (aB-modes) with an integer and fractional orbital angular momentum (OAM). The aB-modes are described by the nth-order Bessel function of the first kind with complex argument. The asymmetry degree of the nonparaxial aB-mode is shown to depend on a real parameter c≥0: when c=0, the aB-mode is identical to a conventional radially symmetric Bessel mode; with increasing c, the aB-mode starts to acquire a crescent form, getting stretched along the vertical axis and shifted along the horizontal axis for c≫1. On the horizontal axis, the aB-modes have a denumerable number of isolated intensity zeros that generate optical vortices with a unit topological charge of opposite sign on opposite sides of 0. At different values of the parameter c, the intensity zeros change their location on the horizontal axis, thus changing the beam's OAM. An isolated intensity zero on the optical axis generates an optical vortex with topological charge n. The OAM per photon of an aB-mode depends near-linearly on c, being equal to ℏ(n+cI1(2c)/I0(2c)), where ℏ is the Planck constant and In(x) is a modified Bessel function.
Institute of Scientific and Technical Information of China (English)
石意如
2016-01-01
There are some problems in guidance of Economics and Management undergraduate thesis ,instructor selection ,quality evalu-ation mechanism in local colleges and universities .In order to agree with personnel training objectives of applied undergraduate talents ,we can reconstruct the guidance model of undergraduate thesis by restructuring thesis guiding process ,optimizing the selection mechanism of instructor , improving the quality evaluation mechanism of thesis as well as practicing incentive mechanism of instructor and so on .%现行地方高校经管类本科毕业论文指导各环节、指导教师遴选与质量评价机制都存在一些问题，为了与应用型本科人才培养目标一致，可以从重组论文指导流程、优化指导教师遴选机制、改进论文质量评价机制、践行指导教师激励机制等方面，重构本科毕业论文指导模式。
Free boundary resistive modes in tokamaks
Huysmans, G. T. A.; Goedbloed, J. P.; Kerner, W.
1993-05-01
There exist a number of observations of magnetohydrodynamic (MHD) activity that can be related to resistive MHD modes localized near the plasma boundary. To study the stability of these modes, a free boundary description of the plasma is essential. The resistive plasma-vacuum boundary conditions have been implemented in the fully toroidal resistive spectral code castor (Complex Alfvén Spectrum in Toroidal Geometry) [Proceedings of the 18th Conference on Controlled Fusion and Plasma Physics, Berlin, edited by P. Bachmann and D. C. Robinson (European Physical Society, Petit-Lancy, Switzerland, 1991), p. 89]. The influence of a free boundary, as compared to a fixed boundary on the stability of low-m tearing modes, is studied. It is found that the stabilizing (toroidal) effect of a finite pressure due the plasma compression is lost in the free boundary case for modes localized near the boundary. Since the stabilization due to the favorable average curvature in combination with a pressure gradient near the boundary is small, the influence of the pressure on the stability is much less important for free boundary modes than for fixed boundary modes.
Vertical Coordination Development Mode and Influential Factors of Agricultural Products
Institute of Scientific and Technical Information of China (English)
Tuzhan WANG
2016-01-01
In China,the vertical coordination development mode of agricultural products can be divided into traditional market-oriented transaction mode with fluctuation according to market conditions,made-to-order on the basis of farmer organization,company leading cooperative mode,share or shareholding cooperative mode,and vertical integration mode. There are differences in coordination characteristics,advantages and disadvantages,and adaptability between different modes. Traditional vertical coordination mode is transforming and upgrading to close and high-efficient mode. In this process,it is influenced by factors such as cost-benefit balance between farmers and agricultural product processing enterprises,special use of agricultural product processing,structure of agricultural product industry chain,and action of local government.
Institute of Scientific and Technical Information of China (English)
周晓刚
2015-01-01
The paper systematically elaborates on the connotation,the core content and the approaches of personnel cultivation mode,which involves "dual placement,three -station interaction,piecewise rotation".It is the localized practice based on the German dual system mode,aiming to solve the problems of cooperativeness,comprehensiveness,stableness and effective-ness among the college -business participants in combination of learning and working.%为了解决工学结合、校企合作人才培养中企业参与教学的协同性、全面性、稳定性和有效性问题，进行了德国双元制模式的本土化实践，构建“定岗双元、三站互动、分段轮换”人才培养模式，系统阐述了该人才培养模式的内涵、核心内容和建设路径。
Trapped electromagnetic modes in a waveguide with a small discontinuity
Stupakov, G. V.; Kurennoy, S. S.
1994-01-01
We demonstrate that a small discontinuity (such as an enlargement or a hole) on a smooth waveguide can result in the appearance of trapped modes localized in the vicinity of the discontinuity. The frequencies of these modes lie slightly below the cutoff frequencies of the corresponding propagating modes in the waveguide. We find the distribution of the electromagnetic field in the modes and calculate their damping rate due to a finite conductivity of the walls. The contribution of the trapped modes to the longitudinal impedance is calculated.
Two modes for dune orientation
Courrech Du Pont, Sylvain; Narteau, Clément; Gao, Xin
2015-11-01
Earth sand seas experience winds that blow with different strengths and from different directions in line with the seasons. In response, dune fields show a rich variety of shapes from small crescentic barchans to big star and linear dunes. Linear dunes often exhibit complex and compound patterns with different length scales and orientations, which seem difficult to relate to a single wind cycle. We present results of underwater experiments and numerical simulations where a single wind regime can lead to two different dunes orientation depending on sediment availability. Sediment availability selects the overriding mechanism for the formation of dunes: increasing in height from the destabilization of a sand bed or elongating in a finger on a non-erodible ground from a localized sand source. These mechanisms drive the dunes orientation. Therefore, dunes alignment maximizes dunes orthogonality to sand fluxes in the bed instability mode, while dunes are aligned with the sand transport direction in the fingering mode. Then, we derive a model for dunes orientation, which explains the coexistence of bedforms with different alignments and quantitatively predicts the orientation of dunes in Earth deserts. Finally, we explore the phase diagram and the stability of the fingering mode.
Drift-Alfven instabilities of a finite beta plasma shear flow along a magnetic field
Mikhailenko, V. V.; Mikhailenko, V. S.; Lee, Hae June
2016-02-01
It was derived that the drift-Alfven instabilities with the shear flow parallel to the magnetic field have significant difference from the drift-Alfven instabilities of a shearless plasma when the ion temperature is comparable with electron temperature for a finite plasma beta. The velocity shear not only modifies the frequency and the growth rate of the known drift-Alfven instability, which develops due to the inverse electron Landau damping, but also triggers a combined effect of the velocity shear and the inverse ion Landau damping, which manifests the development of the ion kinetic shear-flow-driven drift-Alfven instability. The excited unstable waves have the phase velocities along the magnetic field comparable with the ion thermal velocity, and the growth rate is comparable with the frequency. The development of this instability may be the efficient mechanism of the ion energization in shear flows.
Directory of Open Access Journals (Sweden)
Gizon Laurent
2005-11-01
Full Text Available We review the current status of local helioseismology, covering both theoretical and observational results. After a brief introduction to solar oscillations and wave propagation through inhomogeneous media, we describe the main techniques of local helioseismology: Fourier-Hankel decomposition, ring-diagram analysis, time-distance helioseismology, helioseismic holography, and direct modeling. We discuss local helioseismology of large-scale flows, the solar-cycle dependence of these flows, perturbations associated with regions of magnetic activity, and solar supergranulation.
Spatial and temporal localization of light in two dimensions
Máximo, Carlos E; Courteille, Philippe W; Kaiser, Robin; Bachelard, Romain
2015-01-01
Quasi-resonant scattering of light in two dimensions can be described either as a scalar or as a vectorial electromagnetic wave. Performing a scaling analysis we observe in both cases long lived modes, yet only the scalar case exhibits Anderson localized modes together with extremely long mode lifetimes. We show that the localization length of these modes is influenced only by their position, and not their lifetime. Investigating the reasons for the absence of localization, it appears that both the coupling of several polarizations and the presence of near-field terms are able to prevent long lifetimes and Anderson localization.
Mode choice model parameters estimation
Strnad, Irena
2010-01-01
The present work focuses on parameter estimation of two mode choice models: multinomial logit and EVA 2 model, where four different modes and five different trip purposes are taken into account. Mode choice model discusses the behavioral aspect of mode choice making and enables its application to a traffic model. Mode choice model includes mode choice affecting trip factors by using each mode and their relative importance to choice made. When trip factor values are known, it...
Spatial steadiness of individual disorder modes upon controlled spectral tuning
Caselli, Niccolò; Riboli, Francesco; Intonti, Francesca; La China, Federico; Biccari, Francesco; Gerardino, Annamaria; Gurioli, Massimo
2016-07-01
Recent innovative applications in disordered photonics would strongly benefit from the possibility to achieve spectral tuning of the individual disorder localized photonic modes without affecting their spatial distributions. Here, we design and fabricate a two-dimensional disordered photonic system, made of a GaAs slab patterned with randomly distributed circular air scattering centers, supporting localized light modes with very small modal volume. The photoluminescence of InAs quantum dots embedded in the slab is used as a probe for near field experiments and gives direct access to the electric field intensity distribution of the localized random modes. We demonstrate that laser assisted oxidation of the GaAs slab performed by near field illumination can be used for a gentle tuning of the individual random modes without modifying the subtle balance leading to light localization given by multiple scattering.
DEFF Research Database (Denmark)
Sundbo, Donna Isabella Caroline
2013-01-01
Recently there has been more focus on food in general and local food in particular. But what is local food? And what are the perceptions of this concept according to theory and to providers and consumers of local food? This article first summarises and compares three different theoretical...... as expressed by a group of Danish providers and consumers is empirically investigated through interviews, observation and surveys. From this, qualitative and quantitative data are generated, the analysis of which shows how varied perceptions of local food are. The elements of which the perceptions consist...... are identified and then categorised according to whether they pertain to the food product itself or the production methods and facilities and whether they describe physical or social properties of local food. From this a model with four categories is developed. It is found that properties of the product are more...
Sernelius, Bo E
2011-01-01
Electromagnetic surface modes are present at all surfaces and interfaces between material of different dielectric properties. These modes have very important effects on numerous physical quantities: adhesion, capillary force, step formation and crystal growth, the Casimir effect etc. They cause surface tension and wetting and they give rise to forces which are important e.g. for the stability of colloids.This book is a useful and elegant approach to the topic, showing how the concept of electromagnetic modes can be developed as a unifying theme for a range of condensed matter physics. The
DEFF Research Database (Denmark)
Israelsen, Stine Møller
. The research presented in this thesis falls in three parts. In the first part, a first time demonstration of the break of the azimuthal symmetry of the Bessel-like LP0X modes is presented. This effect, known as the bowtie effect, causes the mode to have an azimuthal dependence as well as a quasi...... and polarization state are investigated. For this fiber, the onset of the bowtie effect is shown numerically to be LP011. The characteristics usually associated with Bessel-likes modes such as long diffraction free length and selfhealing are shown to be conserved despite the lack of azimuthal symmetry...
Dissipative electron drift modes in the H1-NF stellarator
Energy Technology Data Exchange (ETDEWEB)
Nadeem, M.; Rafiq, T.; Persson, M. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electromagnetics
2001-09-01
A resistive drift wave model is developed from the two fluids theory, and the associated eigenvalue problem is solved using the ballooning mode formalism for the 3D equilibrium magnetic field configuration of the H-1NF stellarator. The frequency spectrum and the localization of electron drift modes are driven unstable by collisional dissipation of electrons along the magnetic field lines. (orig.)
Complementary magnetic localized surface plasmons
Gao, Zhen; Zhang, Youming; Zhang, Baile
2015-01-01
Magnetic localized surface plasmons (LSPs) supported on metallic structures corrugated by very long and curved grooves have been recently proposed and demonstrated on an extremely thin metallic spiral structure (MSS) in the microwave regime. However, the mode profile for the magnetic LSPs was demonstrated by measuring only the electric field, not the magnetic field.
Kolpakov, Stanislav A; Loika, Yuri; Tarasov, Nikita; Kalashnikov, Vladimir; Agrawal, Govind P
2015-01-01
A mode locked fibre laser as a source of ultra-stable pulse train has revolutionised a wide range of fundamental and applied research areas by offering high peak powers, high repetition rates, femtosecond range pulse widths and a narrow linewidth. However, further progress in linewidth narrowing seems to be limited by the complexity of the carrier-envelope phase control. Here for the first time we demonstrate experimentally and theoretically a new mechanism of resonance vector self-mode locking where tuning in-cavity birefringence leads to excitation of the longitudinal modes sidebands accompanied by the resonance phase locking of sidebands with the adjacent longitudinal modes. An additional resonance with acoustic phonons provides the repetition rate tunability and linewidth narrowing down to Hz range that drastically reduces the complexity of the carrier-envelope phase control and so will open the way to advance lasers in the context of applications in metrology, spectroscopy, microwave photonics, astronomy...
Supersymmetric mode converters
Heinrich, Matthias; Miri, Mohammad-Ali; Stützer, Simon; Nolte, Stefan; Szameit, Alexander; Christodoulides, Demetrios N.
2015-08-01
In recent years, the ever-increasing demand for high-capacity transmission systems has driven remarkable advances in technologies that encode information on an optical signal. Mode-division multiplexing makes use of individual modes supported by an optical waveguide as mutually orthogonal channels. The key requirement in this approach is the capability to selectively populate and extract specific modes. Optical supersymmetry (SUSY) has recently been proposed as a particularly elegant way to resolve this design challenge in a manner that is inherently scalable, and at the same time maintains compatibility with existing multiplexing strategies. Supersymmetric partners of multimode waveguides are characterized by the fact that they share all of their effective indices with the original waveguide. The crucial exception is the fundamental mode, which is absent from the spectrum of the partner waveguide. Here, we demonstrate experimentally how this global phase-matching property can be exploited for efficient mode conversion. Multimode structures and their superpartners are experimentally realized in coupled networks of femtosecond laser-written waveguides, and the corresponding light dynamics are directly observed by means of fluorescence microscopy. We show that SUSY transformations can readily facilitate the removal of the fundamental mode from multimode optical structures. In turn, hierarchical sequences of such SUSY partners naturally implement the conversion between modes of adjacent order. Our experiments illustrate just one of the many possibilities of how SUSY may serve as a building block for integrated mode-division multiplexing arrangements. Supersymmetric notions may enrich and expand integrated photonics by versatile optical components and desirable, yet previously unattainable, functionalities.
Trofimov, M. Yu.; Zakharenko, A. D.; Kozitskiy, S. B.
2016-10-01
A mode parabolic equation in the ray centered coordinates for 3D underwater sound propagation is developed. The Gaussian beam tracing in this case is constructed. The test calculations are carried out for the ASA wedge benchmark and proved an excellent agreement with the source images method in the case of cross-slope propagation. But in the cases of wave propagation at some angles to the cross-slope direction an account of mode interaction becomes necessary.
Fluctuating Elasticity Mode in Transient Molecular Networks
Nava, Giovanni; Rossi, Marina; Biffi, Silvia; Sciortino, Francesco; Bellini, Tommaso
2017-08-01
Transient molecular networks, a class of adaptive soft materials with remarkable application potential, display complex, and intriguing dynamic behavior. By performing dynamic light scattering on a wide angular range, we study the relaxation dynamics of a reversible network formed by DNA tetravalent nanoparticles, finding a slow relaxation mode that is wave vector independent at large q and crosses over to a standard q-2 viscoelastic relaxation at low q . Exploiting the controlled properties of our DNA network, we attribute this mode to fluctuations in local elasticity induced by connectivity rearrangement. We propose a simple beads and springs model that captures the basic features of this q0 behavior.
Dissipative trapped electron modes in stellarator plasmas
Energy Technology Data Exchange (ETDEWEB)
Nasim, M.H.; Rafiq, T.; Persson, M. [Department of Electromagnetics and Euratom/VR Association, Chalmers University of Technology, Gothenburg (Sweden)
2003-07-01
The objective of the present paper is to study the dissipative trapped electron modes in different stellarator and tokamak configurations with the purpose to contribute to the understanding of the geometrical effects on these instabilities. A three field periods heliac (H1-NF), a five field period helias (W7-X) and a circular tokamak are selected to study the effect of geometrical properties such as local magnetic shear, normal curvature, geodesic curvature and magnetic field, on the mode localisation. The VMEC code is used to obtain the 3-D equilibria. (orig.)
Instantaneous Normal Modes and the Protein Glass Transition
Energy Technology Data Exchange (ETDEWEB)
Schultz, Roland [University of Tennessee, Knoxville (UTK); Krishnan, Marimuthu [ORNL; Daidone, Isabella [University of Heidelberg; Smith, Jeremy C [ORNL
2009-01-01
In the instantaneous normal mode method, normal mode analysis is performed at instantaneous configurations of a condensed-phase system, leading to modes with negative eigenvalues. These negative modes provide a means of characterizing local anharmonicities of the potential energy surface. Here, we apply instantaneous normal mode to analyze temperature-dependent diffusive dynamics in molecular dynamics simulations of a small protein (a scorpion toxin). Those characteristics of the negative modes are determined that correlate with the dynamical (or glass) transition behavior of the protein, as manifested as an increase in the gradient with T of the average atomic mean-square displacement at 220 K. The number of negative eigenvalues shows no transition with temperature. Further, although filtering the negative modes to retain only those with eigenvectors corresponding to double-well potentials does reveal a transition in the hydration water, again, no transition in the protein is seen. However, additional filtering of the protein double-well modes, so as to retain only those that, on energy minimization, escape to different regions of configurational space, finally leads to clear protein dynamical transition behavior. Partial minimization of instantaneous configurations is also found to remove nondiffusive imaginary modes. In summary, examination of the form of negative instantaneous normal modes is shown to furnish a physical picture of local diffusive dynamics accompanying the protein glass transition.
Institute of Scientific and Technical Information of China (English)
戴军; 张广玲
2015-01-01
Market-oriented reform is the important direction and goal of China's current state-owned assets supervision system reform .On the basis of Temasek's supervision system , this paper offers two specific reform paths:one is the trans-formation of reaching the designated position by one pace , directly facing the market for enterprise as a legal person property of Temasek mode;the other is localized innovation of Temasek mode , exploring a way to transform SASAC into a legal insti-tution with legal responsibility and market-oriented operation by legislation .In a word, the former is faced with realistic and legal barriers , while the latter is more suitable for China's national conditions , which is the right path for our country cur-rently to deepen the reform of the state-owned assets supervision system .%市场化改革是当前我国国有资产监管体制改革的重要方向和目标。文章以淡马锡式的国资监管体制为基础，提出两条具体的改革路径：一是一步到位转型为企业法人性质、直接面对市场的淡马锡模式；二是对淡马锡模式进行本土化创新，探索通过专门立法，将国资委转化为权责法定、市场化运作的法定机构模式。综合分析，前者面临非常大的现实和法律障碍，而后者更适合中国国情，是我国当前深化国有资产监管体制改革的恰当路径。
DEFF Research Database (Denmark)
de Souza e Silva, Adriana Araujo; Gordon, Eric
Provides an introduction to the new theory of Net Locality and the profound effect on individuals and societies when everything is located or locatable. Describes net locality as an emerging form of location awareness central to all aspects of digital media, from mobile phones, to Google Maps, to...... of emerging technologies, from GeoCities to GPS, Wi-Fi, Wiki Me, and Google Android....
DEFF Research Database (Denmark)
de Souza e Silva, Adriana Araujo; Gordon, Eric
Provides an introduction to the new theory of Net Locality and the profound effect on individuals and societies when everything is located or locatable. Describes net locality as an emerging form of location awareness central to all aspects of digital media, from mobile phones, to Google Maps, to...... of emerging technologies, from GeoCities to GPS, Wi-Fi, Wiki Me, and Google Android....
Discrete mode lasers for communications applications
Barry, L. P.; Herbert, C.; Jones, D.; Kaszubowska-Anandarajah, A.; Kelly, B.; O'Carroll, J.; Phelan, R.; Anandarajah, P.; Shi, K.; O'Gorman, J.
2009-02-01
The wavelength spectra of ridge waveguide Fabry Perot lasers can be modified by perturbing the effective refractive index of the guided mode along very small sections of the laser cavity. One way of locally perturbing the effective index of the lasing mode is by etching features into the ridge waveguide such that each feature has a small overlap with the transverse field profile of the unperturbed mode, consequently most of the light in the laser cavity is unaffected by these perturbations. A proportion of the propagating light is however reflected at the boundaries between the perturbed and the unperturbed sections. Suitable positioning of these interfaces allows the mirror loss spectrum of a Fabry Perot laser to be manipulated. In order to achieve single longitudinal mode emission, the mirror loss of a specified mode must be reduced below that of the other cavity modes. Here we review the latest results obtained from devices containing such features. These results clearly demonstrate that these devices exceed the specifications required for a number of FTTH and Datacomms applications, such as GEPON, LX4 and CWDM. As well as this we will also present initial results on the linewidth of these devices.
Directory of Open Access Journals (Sweden)
Philippe Schlenker
2009-07-01
Full Text Available The dynamic approach posits that a presupposition must be satisfied in its local context. But how is a local context derived from the global one? Extant dynamic analyses must specify in the lexical entry of any operator what its 'Context Change Potential' is, and for this very reason they fail to be sufficiently explanatory. To circumvent the problem, we revise two assumptions of the dynamic approach: we take the update process to be derivative from a classical, non-dynamic semantics -- which obviates the need for dynamic lexical entries; and we deny that a local context encodes what the speech act participants 'take for granted.' Instead, we take the local context of an expression E in a sentence S to be the smallest domain that one may restrict attention to when assessing E without jeopardizing the truth conditions of S. To match the results of dynamic semantics, local contexts must be computed incrementally, using only information about the expressions that precede E. This version of the theory can be shown to be nearly equivalent to the dynamic theory of Heim 1983 -- but unlike the latter, it is entirely predictive. We also suggest that local contexts can, at some cost, be computed symmetrically, taking into account information about all of S (except E; this leads to gradient predictions, whose assessment is left for future research. doi:10.3765/sp.2.3 BibTeX info
Localization of Laplacian eigenfunctions in circular, spherical and elliptical domains
Nguyen, Binh-Thanh
2012-01-01
We consider Laplacian eigenfunctions in circular, spherical and elliptical domains in order to discuss three kinds of high-frequency localization: whispering gallery modes, bouncing ball modes, and focusing modes. Although the existence of these modes was known for a class of convex domains, the separation of variables for above domains helps to better understand the "mechanism" of localization, i.e. how an eigenfunction is getting distributed in a small region of the domain, and decays rapidly outside this region. Using the properties of Bessel and Mathieu functions, we derive the inequalities which imply and clearly illustrate localization. Moreover, we provide an example of a non-convex domain (an elliptical annulus) for which the high-frequency localized modes are still present. At the same time, we show that there is no localization in most of rectangle-like domains. This observation leads us to formulating an open problem of localization in polygonal domains and, more generally, in piecewise smooth conv...
Compressed modes for variational problems in mathematics and physics.
Ozolins, Vidvuds; Lai, Rongjie; Caflisch, Russel; Osher, Stanley
2013-11-12
This article describes a general formalism for obtaining spatially localized ("sparse") solutions to a class of problems in mathematical physics, which can be recast as variational optimization problems, such as the important case of Schrödinger's equation in quantum mechanics. Sparsity is achieved by adding an regularization term to the variational principle, which is shown to yield solutions with compact support ("compressed modes"). Linear combinations of these modes approximate the eigenvalue spectrum and eigenfunctions in a systematically improvable manner, and the localization properties of compressed modes make them an attractive choice for use with efficient numerical algorithms that scale linearly with the problem size.
High temperature quark localization by Polyakov loops
Kovacs, Tamas G; Bruckmann, Falk; Schierenberg, Sebastian
2011-01-01
We study the low eigenmodes of the overlap and staggered Dirac operator at high temperature. We show that the recently found localized quark modes obeying Poisson statistics are connected to physical gauge field objects with their size and density scaling in the continuum limit. The localized modes are also strongly correlated with large fluctuations of the Polyakov loop. Based on that we construct a random matrix model of the low Dirac modes inspired by dimensional reduction. Our model reproduces the Poisson to random matrix transition seen in the lattice Dirac spectrum.
Measurement of electron particle transport coefficients in different operational modes of DIII-D
Baker, D. R.; Wade, M. R.; Jackson, G. L.; Maingi, R.; Stockdale, R. E.; de Grassie, J. S.; Groebner, R. J.; Forest, C. B.; Porter, G. D.; DIII-D Team
1998-04-01
Electron transport coefficients have been obtained for different operational modes on the DIII-D tokamak. The operational modes are: double null diverted (DND) low confinement (L mode), DND high confinement (H mode) without edge localized modes (ELM-free), single null diverted (SND) ELM-free H mode and pumped SND ELMing H mode. Various values of plasma current and safety factor (q) profiles were investigated. For the L mode and ELMing H mode, the coefficients were obtained by a modulated puff of deuterium gas at the edge. For the ELM-free modes, the coefficients were obtained by analysing the temporal evolution of the electron density profile immediately after the L-H transition. The results show clearly that the radial profile of the electron diffusion coefficient depends on the operational mode of DIII-D. The difference in the radial dependences of the transport coefficients between the different tokamak operational modes is significant. In the L mode and the ELMing H mode, the diffusion coefficient increases with radius. In ELMing H mode, the diffusion coefficient increases with the edge value of q. The value at the edge for L mode is about twice that for ELMing H mode. In ELM-free H mode, the diffusion coefficient decreases rapidly outside a normalized radius of about 0.8. Within the (relatively large) error bars for ELM-free H mode, there is no measurable difference in diffusion coefficient between the DND and SND plasmas.
Thin layer Characterization by ZGV Lamb modes
Energy Technology Data Exchange (ETDEWEB)
Ces, Maximin; Clorennec, Dominique; Royer, Daniel; Prada, Claire, E-mail: maximin.ces@espci.fr [Laboratoire Ondes et Acoustique, ESPCI- Universite Paris 7- CNRS UMR 7587, 10 rue Vauquelin, 75231 Paris Cedex 05- France (France)
2011-01-01
Ultrasonic non-destructive testing of plates can be performed with Lamb modes guided by the structure. Non contact generation and detection of the elastic waves can be achieved with optical means such as a pulsed laser source and an interferometer. With this setup, we propose a method using zero group velocity (ZGV) Lamb modes rather than propagating modes. These ZGV modes have noteworthy properties, in particular their group velocity vanishes, whereas their phase velocity remains finite. Thus, a significant part of the energy deposited by the pulsed laser can be trapped in the source area. For example, in a homogeneous isotropic plate and at the minimum frequency of the S{sub 1}-Lamb mode a very sharp resonance can be observed, the frequency of which only depends on the plate thickness, for a given material. In fact, other ZGV modes exist and the set of ZGV resonance frequencies provide a local and absolute measurement of Poisson's ratio. These non-propagating modes can also be used to characterize multi-layered structures. Experimentally, we observed that a thin (500 nm) gold layer deposited on a thick (1.5 mm) Duralumin plate induces a sensitive down-shift of the set of ZGV resonance frequencies. This shift, which is typically 5 kHz for the S{sub 1}-Lamb mode at 1.924 MHz, can be approximated by a formula providing the layer thickness. Thickness down to 100 nm can be estimated by this method. Such a sensitivity with conventional ultrasound inspection by acoustic microscopy would require an operating frequency in the GHz range.
Spin-wave modes of ferromagnetic films
Arias, R. E.
2016-10-01
The spin-wave modes of ferromagnetic films have been studied for a long time experimentally as well as theoretically, either in the magnetostatic approximation or also considering the exchange interaction. A theoretical method is presented that allows one to determine with ease the exact frequency dispersion relations of dipole-exchange modes under general conditions: an obliquely applied magnetic field, and surface boundary conditions that allow for partial pinning, which may be of different origins. The method is a generalization of Green's theorem to the problem of solving the linear dynamics of ferromagnetic spin-wave modes. Convolution integral equations for the magnetization and the magnetostatic potential of the modes are derived on the surfaces of the film. For the translation-invariant film these become simple local algebraic equations at each in-plane wave vector. Eigenfrequencies result from imposing a 6 ×6 determinant to be null, and spin-wave modes follow everywhere through solving linear 6 ×6 inhomogeneous systems. An interpretation of the results is that the Green's functions represent six independent plane-wave solutions to the equations of motion, with six associated complex perpendicular wave vectors: volume modes correspond to the cases in which two of these are purely real at a given frequency. Furthermore, the convolution extinction equations enforce the boundary conditions: this is possible at specific eigenfrequencies for a given in-plane wave vector. Magnetostatic modes may also be obtained in detail. At low frequencies and for some obliquely applied magnetic fields, magnetostatic and dipole-exchange volume modes may have forward or backward character depending on the frequency range.
Mode Splitting for Efficient Plasmoinc Thin-film Solar Cell
Li, Tong; Jiang, Chun
2010-01-01
We propose an efficient plasmonic structure consisting of metal strips and thin-film silicon for solar energy absorption. We numerically demonstrate the absorption enhancement in symmetrical structure based on the mode coupling between the localized plasmonic mode in Ag strip pair and the excited waveguide mode in silicon slab. Then we explore the method of symmetry-breaking to excite the dark modes that can further enhance the absorption ability. We compare our structure with bare thin-film Si solar cell, and results show that the integrated quantum efficiency is improved by nearly 90% in such thin geometry. It is a promising way for the solar cell.
Process for Operating a Dual-Mode Combustor
Trefny, Charles J. (Inventor); Dippold, Vance F. (Inventor)
2017-01-01
A new dual-mode ramjet combustor used for operation over a wide flight Mach number range is described. Subsonic combustion mode is usable to lower flight Mach numbers than current dual-mode scramjets. High speed mode is characterized by supersonic combustion in a free-jet that traverses the subsonic combustion chamber to a variable nozzle throat. Although a variable combustor exit aperture is required, the need for fuel staging to accommodate the combustion process is eliminated. Local heating from shock-boundary-layer interactions on combustor walls is also eliminated.
Normal modes of a defected linear system of beaded springs
Aghamohammadi, Amir; Foulaadvand, M. Ebrahim; Yaghoubi, Mohammad Hassan; Mousavi, Amir Hossein
2017-03-01
A model of a one-dimensional mass-spring chain with mass or spring defects is investigated. With a mass defect, all oscillators except the central one have the same mass, and with a spring defect, all the springs except those connected to the central oscillator have the same stiffness constant. The motion is assumed to be one-dimensional and frictionless, and both ends of the chain are assumed to be fixed. The system vibrational modes are obtained analytically, and it is shown that if the defective mass is lighter than the others, then a high frequency mode appears in which the amplitudes decrease exponentially with the distance from the defect. In this sense, the mode is localized in space. If the defect mass is greater than the others, then there will be no localized mode and all modes are extended throughout the system. Analogously, for some values of the defective spring constant, there may be one or two localized modes. If the two defected spring constants are less than that of the others, there is no localized mode.
Sliding mode control and observation
Shtessel, Yuri; Fridman, Leonid; Levant, Arie
2014-01-01
The sliding mode control methodology has proven effective in dealing with complex dynamical systems affected by disturbances, uncertainties and unmodeled dynamics. Robust control technology based on this methodology has been applied to many real-world problems, especially in the areas of aerospace control, electric power systems, electromechanical systems, and robotics. Sliding Mode Control and Observation represents the first textbook that starts with classical sliding mode control techniques and progresses toward newly developed higher-order sliding mode control and observation algorithms and their applications. The present volume addresses a range of sliding mode control issues, including: *Conventional sliding mode controller and observer design *Second-order sliding mode controllers and differentiators *Frequency domain analysis of conventional and second-order sliding mode controllers *Higher-order sliding mode controllers and differentiators *Higher-order sliding mode observers *Sliding mode disturbanc...
Constitutive mixed mode model for cracks in concrete
DEFF Research Database (Denmark)
Jacobsen, J.S.; Poulsen, P.N.; Olesen, J.F.;
2013-01-01
The scope of the paper is to set up a constitutive mixed mode model for cracks in concrete. The model is formulated at macro level and includes the most important micro scale effects. An associated plasticity model inspired by the modified Cam clay model is established. The hardening parameters...... is determined from the topographic information and the constitutive model is thereby purely mechanically based. Using the actual topographic description the model is validated against experimental results for mixed mode crack openings....... are based on the standard Mode I tensile softening response and the response for Mode I crushing. The roughness of the crack is included through a topographic description of the crack surface. The constitutive behavior is based on the integration of local contributions. The local mixed mode ratio...
Thermodynamics of radiation modes
Energy Technology Data Exchange (ETDEWEB)
Pina, Eduardo; De la Selva, Sara Maria Teresa [Departamento de Fisica, Universidad Autonoma Metropolitana - Iztapalapa, PO Box 55 534, Mexico, D F, 09340 (Mexico)], E-mail: pge@xanum.uam.mx, E-mail: tere@xanum.uam.mx
2010-03-15
We study the equilibrium thermodynamics of the electromagnetic radiation in a cavity of a given volume and temperature. We found three levels of description, the thermodynamics of one mode, the thermodynamics of the distribution of frequencies in a band by summing over the frequencies in it and the global thermodynamics by summing over all the frequencies. One equation relating frequency and volume is used to define the thermodynamics of one mode, and to explain the mystery of the frequency-dependent quantities having a similar behaviour to the non-frequency-dependent quantities for some thermodynamic equations and different behaviour for others. Besides, this frequency-volume relation is used to count the number of modes in a band of frequency.
Directory of Open Access Journals (Sweden)
Evens Jabouin
2012-01-01
Full Text Available Le violent séisme qui a secoué Haïti et sa capitale le 12 janvier 2010 dernier a laissé des séquelles au sein de la population haïtienne déjà fragilisée par la violence, la pauvreté et aussi par des catastrophes naturelles répétées (ouragans, inondations, érosion, etc.. Ce séisme, aussi prévisible qu’il soit, est une catastrophe naturelle et humanitaire sans précédent dont les principales causes sont l’absence de constructions et d’infrastructures solides, bâties selon les normes parasismiques, l’occupation anarchique de l’espace urbain par les populations et les nombreuses irrégularités incontestées observées dans le domaine de l’urbanisme. En outre, ce séisme s’est produit à un moment où l’on commençait à observer dans le pays un élan de stabilisation sur le plan politique, un mouvement de croissance économique ainsi qu’un début d’amélioration des conditions de vie des populations. La catastrophe est venue freiner cette dynamique socioéconomique tout en amplifiant les problèmes existants et en engendrant d’autres difficultés et d’autres défis. Cet article analyse, à travers des témoignages de première main et un état des lieux, les différents impacts de cette catastrophe sur la population locale ainsi que les interrogations et les incertitudes diverses de cette population concernant son avenir.On January the twelfth 2010, Haiti and its capital have been devastated by a very strong earthquake that has provoked many aftereffects among the local population since that population had already been weakened before by street violence, poverty and by frequent natural disasters such as hurricanes, floods... That earthquake, even foreseeable, has given way to an important disaster whose causes are the absence of well built infrastructures and buildings, the anarchic use of urban spaces by the population, and multiple irregularities in town planning issues. Furthermore, that earthquake took
Directory of Open Access Journals (Sweden)
Stephen Hastings-King
2010-03-01
Full Text Available A locals collection is a set of parameters that are used to delimit data-mining operations. This piece uses a collection of locals from around Essex Massachusetts to shape and delimit an interrogation of post-reality in contemporary America. It explores the notion of crisis, the possibility of a crisis of empire that may or may not emerge in a media-space that does not allow crisis of empire to be mentioned and relations this maybe-crisis to the various levels of economic dysfunction that have become evident since late 2008. But mostly this piece explores ways in which particular stories about particular people do and do not link/link to these larger-scale narratives. This is the first of a potential series of locals collections that will mine the American post-real.
Mode Selection in Compressible Active Flow Networks
Forrow, Aden; Woodhouse, Francis G.; Dunkel, Jörn
2017-07-01
Coherent, large-scale dynamics in many nonequilibrium physical, biological, or information transport networks are driven by small-scale local energy input. Here, we introduce and explore an analytically tractable nonlinear model for compressible active flow networks. In contrast to thermally driven systems, we find that active friction selects discrete states with a limited number of oscillation modes activated at distinct fixed amplitudes. Using perturbation theory, we systematically predict the stationary states of noisy networks and find good agreement with a Bayesian state estimation based on a hidden Markov model applied to simulated time series data. Our results suggest that the macroscopic response of active network structures, from actomyosin force networks to cytoplasmic flows, can be dominated by a significantly reduced number of modes, in contrast to energy equipartition in thermal equilibrium. The model is also well suited to study topological sound modes and spectral band gaps in active matter.
Contained Modes In Mirrors With Sheared Rotation
Energy Technology Data Exchange (ETDEWEB)
Abraham J. Fetterman and Nathaniel J. Fisch
2010-10-08
In mirrors with E × B rotation, a fixed azimuthal perturbation in the lab frame can appear as a wave in the rotating frame. If the rotation frequency varies with radius, the plasma-frame wave frequency will also vary radially due to the Doppler shift. A wave that propagates in the high rotation plasma region might therefore be evanescent at the plasma edge. This can lead to radially localized Alfven eigenmodes with high azimuthal mode numbers. Contained Alfven modes are found both for peaked and non-peaked rotation profiles. These modes might be useful for alpha channeling or ion heating, as the high azimuthal wave number allows the plasma wave frequency in the rotating frame to exceed the ion cyclotron frequency. __________________________________________________
Observation of Spontaneous Neoclassical Tearing Modes
Energy Technology Data Exchange (ETDEWEB)
E.D. Fredrickson
2001-10-03
We present data in this paper from the Tokamak Fusion Test Reactor (TFTR) which challenges the commonly held belief that extrinsic MHD events such as sawteeth or ELMs [edge localized modes] are required to provide the seed islands that trigger Neoclassical Tearing Modes (NTMs). While sawteeth are reported to provide the trigger for most of the NTMs on DIII-D [at General Atomics in San Diego, California] and ASDEX-U [at Max-Planck-Institut fuer Plasmaphysik in Garching, Germany], the majority of NTMs seen in TFTR occur in plasmas without sawteeth, that is which are above the beta threshold for sawtooth stabilization. Examples of NTMs appearing in the absence of any detectable extrinsic MHD activity will be shown. Conversely, large n=1 modes in plasmas above the NTM beta threshold generally do not trigger NTMs. An alternative mechanism for generating seed islands will be discussed.
Multiresonance modes in sine–Gordon brane models
Energy Technology Data Exchange (ETDEWEB)
Cruz, W.T., E-mail: wilamicruz@gmail.com [Instituto Federal de Educação, Ciência e Tecnologia do Ceará (IFCE), Campus Juazeiro do Norte, 63040-540 Juazeiro do Norte-Ceará (Brazil); Maluf, R.V., E-mail: r.v.maluf@fisica.ufc.br [Universidade Federal do Ceará (UFC), Departamento de Física, Campus do Pici, Fortaleza - CE, C.P. 6030, 60455-760 (Brazil); Dantas, D.M., E-mail: davi@fisica.ufc.br [Universidade Federal do Ceará (UFC), Departamento de Física, Campus do Pici, Fortaleza - CE, C.P. 6030, 60455-760 (Brazil); Almeida, C.A.S., E-mail: carlos@fisica.ufc.br [Universidade Federal do Ceará (UFC), Departamento de Física, Campus do Pici, Fortaleza - CE, C.P. 6030, 60455-760 (Brazil)
2016-12-15
In this work, we study the localization of the vector gauge field in two five-dimensional braneworlds generated by scalar fields coupled to gravity. The sine–Gordon like potentials are employed to produce different thick brane setups. A zero mode localized is obtained, and we show the existence of reverberations with the wave solutions indicating a quasi-localized massive mode. More interesting results are achieved when we propose a double sine–Gordon potential to the scalar field. The resulting thick brane shows a more detailed topology with the presence of an internal structure composed by two kinks. The massive spectrum of the gauge field is revalued on this scenario revealing the existence of various resonant modes. Furthermore, we compute the corrections to Coulomb law coming from these massive KK vector modes in these thick scenarios, which is concluded that the dilaton parameter regulates these corrections.
Multiresonance modes in sine-Gordon brane models
Cruz, W. T.; Maluf, R. V.; Dantas, D. M.; Almeida, C. A. S.
2016-12-01
In this work, we study the localization of the vector gauge field in two five-dimensional braneworlds generated by scalar fields coupled to gravity. The sine-Gordon like potentials are employed to produce different thick brane setups. A zero mode localized is obtained, and we show the existence of reverberations with the wave solutions indicating a quasi-localized massive mode. More interesting results are achieved when we propose a double sine-Gordon potential to the scalar field. The resulting thick brane shows a more detailed topology with the presence of an internal structure composed by two kinks. The massive spectrum of the gauge field is revalued on this scenario revealing the existence of various resonant modes. Furthermore, we compute the corrections to Coulomb law coming from these massive KK vector modes in these thick scenarios, which is concluded that the dilaton parameter regulates these corrections.
Roberts, Daniel A; Susskind, Leonard
2014-01-01
We study products of precursors of spatially local operators, $W_{x_{n}}(t_{n}) ... W_{x_1}(t_1)$, where $W_x(t) = e^{-iHt} W_x e^{iHt}$. Using chaotic spin-chain numerics and gauge/gravity duality, we show that a single precursor fills a spatial region that grows linearly in $t$. In a lattice system, products of such operators can be represented using tensor networks. In gauge/gravity duality, they are related to Einstein-Rosen bridges supported by localized shock waves. We find a geometrical correspondence between these two descriptions, generalizing earlier work in the spatially homogeneous case.
Localization of Gravitino Field on Thin Branes
Du, Yun-Zhi; Zhou, Xiang-Nan; Zhong, Yi; Liu, Yu-Xiao
2015-01-01
In this paper, we investigate the localization of a gravitino field on two kinds of thin branes, the Randall-Sundrum-1 (RS1) branes and the scalar-tensor branes. The coupled chiral equations for the Kaluza-Klein (KK) modes of a gravitino field are obtained by the gravitino chiral KK decompositions with the supersymmetry transformations.It is shown that, in the RS1 model for the left- and right-handed zero modes of the gravitino field, only one of them can be localized near one brane. For the massive modes, both chiral modes survive and the lower KK modes are localized near the IR brane from the four-dimensional physical coordinate point of view. For the scalar-tensor brane model, the localization of the gravitino chiral zero modes depends on the coupling parameter $\\lambda$, and they will be not localized around anyone brane within a certain range of the parameter $\\lambda$, which is quite different from the RS1 model. Furthermore, we also give the corresponding mass spectra of the massive KK gravitinos in th...
DEFF Research Database (Denmark)
Nielsen, Jakob Isak
2013-01-01
Under en samtale i Paolo Sorrentinos La grande bellezza/da. Den store skønhed (2013) anføres det, at Italiens primære eksportvarer er mode og mozzarella. Selve filmen vidner om, at Italien har andet at byde på – heriblandt filmkunst og Roms righoldige kulturhistorie.......Under en samtale i Paolo Sorrentinos La grande bellezza/da. Den store skønhed (2013) anføres det, at Italiens primære eksportvarer er mode og mozzarella. Selve filmen vidner om, at Italien har andet at byde på – heriblandt filmkunst og Roms righoldige kulturhistorie....
Institute of Scientific and Technical Information of China (English)
SANG Hong-Yi; LI Zhi-Yuan; GU Ben-Yuan
2005-01-01
@@ Defect modes in one-dimensional photonic crystals (PCs) can be readily detected from the solution of the transmission spectra via the standard transfer-matrix method. We adopt an analytic Bloch-mode approach to examine this problem in terms of eigenmode solutions and investigate the dispersion behaviour of localized defect modes supported by a defect layer sandwiched within two symmetric semi-infinite PCs that are made from multiple constituents. The results show that the number of defect modes grows when the dielectric constant and width of the defect layer increase.
Mode correlation and coherent-mode decomposition of laser beams
Institute of Scientific and Technical Information of China (English)
张彬; 文侨; 楚晓亮
2003-01-01
Theory of the coherent-mode decomposition of laser beams is proposed.The new model for the flat-topped beams proposed by Li recently is taken as an example.The analytical expressions for the M2-factor and mode coherence coefficients of flat-topped beams have been derived in the rectangular coordinate system,by means of which the mode correlation,mode structure,and coherent-mode decomposition of flat-topped beams can be analysed.
Nonlinearity and disorder: Classification and stability of nonlinear impurity modes
DEFF Research Database (Denmark)
Sukhorukov, Andrey A.; Kivshar, Yuri S.; Bang, Ole
2001-01-01
We study the effects produced by competition of two physical mechanisms of energy localization in inhomogeneous nonlinear systems. As an example, we analyze spatially localized modes supported by a nonlinear impurity in the generalized nonlinear Schrödinger equation and describe three types of no...
Monique Turkenburg
2002-01-01
Original title: Taal lokaal. Children of immigrants living in the Netherlands have for years had the opportunity to receive lessons in their mother tongue at primary school. Since 1998 this has been referred to as minority language teaching (OALT in Dutch), and has been the responsibility of local
Trofimov, M Yu; Kozitskiy, S B
2015-01-01
An adiabatic mode Helmholtz equation for 3D underwater sound propagation is developed. The Gaussian beam tracing in this case is constructed. The test calculations are carried out for the crosswedge benchmark and proved an excellent agreement with the source images method.
Free carboxylate stretching modes
Oomens, J.; Steill, J. D.
2008-01-01
We report the first IR spectroscopic observation of carboxylate stretching modes in free space, i.e., in the complete absence of solvent or counterions. Gas-phase spectra of a series of benzoate anions have been recorded and compared to condensed-phase spectra, revealing the profound influence of th
Dewatripont, Mathias; Tirole, Jean
2005-01-01
The paper develops a theory of costly communication in which the sender's and receiver's motivations and abilities endogenously determine the communication mode and the transfer of knowledge. Communication is modeled as a problem of moral hazard in teams, in which the sender and receiver select persuasion and message elaboration efforts. The model…
Thermodynamics of Radiation Modes
Pina, Eduardo; de la Selva, Sara Maria Teresa
2010-01-01
We study the equilibrium thermodynamics of the electromagnetic radiation in a cavity of a given volume and temperature. We found three levels of description, the thermodynamics of one mode, the thermodynamics of the distribution of frequencies in a band by summing over the frequencies in it and the global thermodynamics by summing over all the…
Phase mixing and nonlinearity in geodesic acoustic modes
Energy Technology Data Exchange (ETDEWEB)
Hung, C. P.; Hassam, A. B. [University of Maryland at College Park, College Park, Maryland 20742 (United States)
2013-09-15
Phase mixing and nonlinear resonance detuning of geodesic acoustic modes in a tokamak plasma are examined. Geodesic acoustic modes (GAMs) are tokamak normal modes with oscillations in poloidal flow constrained to lie within flux surfaces. The mode frequency is sonic, dependent on the local flux surface temperature. Consequently, mode oscillations between flux surfaces get rapidly out of phase, resulting in enhanced damping from the phase mixing. Damping rates are shown to scale as the negative 1/3 power of the large viscous Reynolds number. The effect of convective nonlinearities on the normal modes is also studied. The system of nonlinear GAM equations is shown to resemble the Duffing oscillator, which predicts resonance detuning of the oscillator. Resonant amplification is shown to be suppressed nonlinearly. All analyses are verified by numerical simulation. The findings are applied to a recently proposed GAM excitation experiment on the DIII-D tokamak.
Alfven frequency modes at the edge of TFTR plasmas
Energy Technology Data Exchange (ETDEWEB)
Chang, Z.; Fredrickson, E.D.; Zweben, S.J. [and others
1995-07-01
An Alfven frequency mode (AFM) is very often seen in TFTR neutral beam heated plasmas as well as ohmic plasmas. This quasi-coherent mode is so far only seen on the magnetic fluctuation diagnostics (Mirnov coils). A close correlation between the plasma edge density and the mode activity (frequency and amplitude) has been observed, which indicates that the AFM is an edge localized mode with r/a > 0.85. No direct impact of this mode on the plasma global performance or fast ion loss (e.g., the {alpha}-particles in DT experiments) has been observed. This mode is apparently not the conventional TAE (toroidicity-induced Alfven eigenmodes). The present TAE theory cannot explain the observation. Other possible explanations are discussed.
ECE-imaging of the H-mode pedestal (invited)
Energy Technology Data Exchange (ETDEWEB)
Tobias, B. J.; Nazikian, R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Austin, M. E. [University of Texas-Austin, Austin, Texas 78712 (United States); Boom, J. E.; Classen, I. G. J. [Dutch Institute for Fundamental Energy Research, 3430 BE Nieuwegein (Netherlands); Burrell, K. H.; Snyder, P. B. [General Atomics, P.O.Box 85608, San Diego, California 92186 (United States); Domier, C. W.; Luhmann, N. C. Jr. [University of California-Davis, Davis, California 95616 (United States)
2012-10-15
A synthetic diagnostic has been developed that reproduces the highly structured electron cyclotron emission (ECE) spectrum radiated from the edge region of H-mode discharges. The modeled dependence on local perturbations of the equilibrium plasma pressure allows for interpretation of ECE data for diagnosis of local quantities. Forward modeling of the diagnostic response in this region allows for improved mapping of the observed fluctuations to flux surfaces within the plasma, allowing for the poloidal mode number of coherent structures to be resolved. In addition, other spectral features that are dependent on both T{sub e} and n{sub e} contain information about pedestal structure and the electron energy distribution of localized phenomena, such as edge filaments arising during edge-localized mode (ELM) activity.
Mitsutake, Ayori
2015-01-01
It is important to extract reaction coordinates or order parameters from protein simulations in order to investigate the local-minimum-energy states and the transition between them. The most popular method is principal component analysis, which extracts modes with large conformational fluctuation around an average structure. For protein systems, we recently have applied relaxation mode analysis, which investigate dynamics properties of structural fluctuations of proteins and extract slow relaxation modes. In this article, we apply relaxation mode analysis to extract reaction coordinates for the system, in which there are large conformational changes such as folding/unfolding simulation. We have performed a 750 ns simulation of chignolin at a transition temperature and observed many transitions between the most stable, misfolded and unfolded states. Here, we apply principal component analysis and relaxation mode analysis to the system. In relaxation mode analysis, we extract good reaction coordinates automatic...
Papers presented at the IAEA technical committee meeting on H-mode physics
Energy Technology Data Exchange (ETDEWEB)
TCV team [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)
1995-11-01
The two papers contained in this report deal with ohmic H-modes and effect on confinement of edge localized modes in the TCV tokamak. They were presented by the TCV team at the 1995 IAEA technical committee meeting on H-mode physics. figs., tabs., refs.
Haas, Andreas; Henzinger, Thomas A.; Holzer, Andreas; Kirsch, Christoph M.; Lippautz, Michael; Payer, Hannes; Sezgin, Ali; Sokolova, Ana; Veith, Helmut
2015-01-01
The semantics of concurrent data structures is usually given by a sequential specification and a consistency condition. Linearizability is the most popular consistency condition due to its simplicity and general applicability. Nevertheless, for applications that do not require all guarantees offered by linearizability, recent research has focused on improving performance and scalability of concurrent data structures by relaxing their semantics. In this paper, we present local linearizability,...
Progress in Local Helioseismology
Duvall, T. L., Jr.
1997-05-01
Much has been learned about the solar interior in the last two decades with the techniques of global helioseismology. By comparison, the efforts in local helioseismology, defined as the study of subsurface nonaxisymmetric phenomena, have been relatively modest. Part of the difficulty has been conceptual - it was not obvious how to attack the problem. The first attempts at local helioseismology were really scaled-down versions of the global techniques, in which mode measurements were made over a restricted area. These included the ring diagrams of Hill et al. and the Hankel function decompositions of Braun et al. Braun's methods have been extended to include other properties of standard scattering theory, including phase shift and S-matrix measurements. Both of these approaches are important components of our still rather limited arsenal of local helioseismic techniques. Recently more radical approaches to local helioseismology have been initiated, including the time-distance method of Duvall et al. and the knife-edge approach of Lindsey et al. In the time-distance method, the time for waves to travel along subsurface ray paths is determined from the temporal crosscorrelation of signals at two separated surface points. By measuring the times for many pairs of points from our dopplergrams covering the visible hemisphere, a tremendous quantity of information about the state of the solar interior is derived. The correct interpretation of all this information is considerably challenging. These methods show promise as a way of developing 3-d tomography of the solar interior. The current state of the different methods of local helioseismology will be reviewed.
Bi-local Fields in Noncommutative Field Theory
Iso, S; Kitazawa, Y; Iso, Satoshi; Kawai, Hikaru; Kitazawa, Yoshihisa
2000-01-01
We propose a bi-local representation in noncommutative field theory. It provides a simple description for high momentum degrees of freedom. It also shows that the low momentum modes can be well approximated by ordinary local fields. Long range interactions are generated in the effective action for the lower momentum modes after integrating out the high momentum bi-local fields. The low momentum modes can be represented by diagonal blocks in the matrix model picture and the high momentum bi-local fields correspond to off-diagonal blocks. This block-block interaction picture simply reproduces the infrared singular behaviors of nonplanar diagrams in noncommutative field theory.
Institute of Scientific and Technical Information of China (English)
魏奇
2016-01-01
专业结构优化是高等教育内涵发展的关键，处在专业设置、专业建设、专业评估、资源配置、人才培养模式等核心位置。新建本科高校在转型发展期将“就业竞争力、生源竞争力、人才培养实力、专业核心竞争力”作为专业评价的核心指标，将专业建设分为达标——合格——特色三层，基础型、应用型、技术性三型，实现人才培养的“专业与产业、行业（职业）”两融合，突出地方性、应用型两定位，构建了专业结构优化的“四三二一”模式，对提升应用型人才培养质量有重要意义。%The specialty structure optimization is the strategic point of the connotative development of Chinese higher education, which locates at the core position of specialty setup, professional construction, spe⁃cialty assessment, resource allocation and the personnel training mode. Local undergraduate institutions con⁃sider the following four factors as the key indicators to assess specialty development in the transitional period. They are employment competitiveness, enrollment competitiveness, the strength of talent training and the core competence of specialty. In this paper the author divides the specialty construction into three levels and three styles, which the former are“up to the standard, qualified and distinctive”while the latter are“basic, applied and technical”. The integration of specialties and industries, professions and occupations of the talent training is also discussed. What’s more, two orientations of endemicity and application is highlighted, and the“four-three-two-one”mode of specialty structure optimization is constructed. Therefore, the paper has impor⁃tant implications in upgrading the cultivation quality of application talent.
Correlation evaluation of tested and calculated modes of a launch vehicle equipment cabin
Institute of Scientific and Technical Information of China (English)
费红姿; 黄文虎; 牟全臣
2002-01-01
First, discusses some conventional modal correlation evaluation methods. And then, introduces the concepts of global modes and local modes to solve difficulties in analyzing large and complex structures with dense modes like the equipment cabin, establishes a criterion with the ratio of modal strain energy to conveniently distinguish these modes. Finally, investigates the methods of modal vector reduction, error localization and model updating used to achieve a high correlation between the tested and calculated modes of the cabin, and verifies the finite element model of the equipment cabin as a foundation for further design and analysis.
Polarization Mode Dispersion Probability Distribution for Arbitrary Mode Coupling
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
The probability distribution of the differential group delay for arbitrary mode coupling is simulated with Monte-Carlo method. Fitting the simulation results, we obtain probability distribution function for arbitrary mode coupling.
Resonance modes in optical fibres
Institute of Scientific and Technical Information of China (English)
余寿绵; 余恬
2002-01-01
The weakly nonlinear boundary value problem of wave propagation in an optical fibre (for the transverse electric mode, for example) is formulated and a modified linear solution is obtained. It is shown that a self-consistent theory of fibre optics should be weakly nonlinear. The mode of critical refraction that does not exist in the linear theory is obtained, showing that it is a mode consisting of resonance modes. It is shown that the signal carriers in a long fibre are of resonance modes, not normal modes. Some experimental data are given for comparison with the theoretical predictions, and the agreement seems satisfactory.
Institute of Scientific and Technical Information of China (English)
王琳琳; 陈小鹏; 梁杰珍; 刘幽燕; 韦小杰
2012-01-01
Taking the major courses of chemical engineering and technology specialties in the local college, (Chemical Reaction Engineering of Guangxi University) as an example, the reform and practice of the teaching mode and contents have been explored according to characters of strong engineering and theory. With the reform in the teaching mode such as combining classroom teaching with experimental course and production practice, establishing a platform of extra-curriculum activities, and laying stress on engineering practice, students can learn how to put theory in practice and they can also obtain the comprehensive ability in engineering analysis. Besides, innovation abilities and science exploration spirit can be developed, and students' interest on development and application of the local resources can be aroused. Meanwhile, great attention is paid to introducing measures such as elaborating on organizing contents in textbook, combining the practical teaching cases, turning the scientific research achievements and the latest academic results into classroom teaching, combining hot points with classical contents, and improving and enriching teaching contents. As a result, the students' interest and foresight idea are cultivated, practical ability is strengthened, and innovative talents are edified.%以地方本科院校广西大学化学工程与工艺类专业的核心课程化学反应工程为例,针对其工程性与理论性强的特点进行教学模式和教学内容的改革与实践.通过课堂教学与专业实验相结合、课堂教学与生产实习相结合以及创建丰富多彩的课外实践教学活动平台等教学模式的改革,突出工程实践教育,培养学生理论联系实际和工程分析的能力,强化工程设计创新能力和科学探索精神的培养,激发学生开发应用地方资源的热情；通过精心组织教学内容,结合生产实际进行案例教学,结合科研成果进行课堂教学,引入新成果、新信息,
Long-Period Fibre Grating Thin Film Sensors Based on Cladding Mode Coupling
Institute of Scientific and Technical Information of China (English)
XU Yan-Ping; GU Zheng-Tian; CHEN Jia-Bi
2005-01-01
@@ Based on a method of rigorous vector-field analysis, a numerical model of triple-clad long-period fibre grating is established. The vector components of the electric field for the HE11 cladding mode are plotted to study the field distribution of the cladding mode. The local intensity curves of the first six l = 1 cladding modes are also given. It is found that the low-order HE modes have a larger proportion of intensity localized in the core than the low-order EH modes, just like the double-clad LPFG. Further, the coupling constant between the core mode and the cladding mode is analysed. The results show that the coupling constant of the low-order HE increases monotonously when the mode number becomes larger, and it varies monotonously with the film thickness except for a certain specific region.
Constraining primordial vector mode from B-mode polarization
Energy Technology Data Exchange (ETDEWEB)
Saga, Shohei; Ichiki, Kiyotomo [Department of Physics and Astrophysics, Nagoya University, Aichi 464-8602 (Japan); Shiraishi, Maresuke, E-mail: saga.shohei@nagoya-u.jp, E-mail: maresuke.shiraishi@pd.infn.it, E-mail: ichiki@a.phys.nagoya-u.ac.jp [Dipartimento di Fisica e Astronomia ' ' G. Galilei' ' , Università degli Studi di Padova, via Marzolo 8, I-35131, Padova (Italy)
2014-10-01
The B-mode polarization spectrum of the Cosmic Microwave Background (CMB) may be the smoking gun of not only the primordial tensor mode but also of the primordial vector mode. If there exist nonzero vector-mode metric perturbations in the early Universe, they are known to be supported by anisotropic stress fluctuations of free-streaming particles such as neutrinos, and to create characteristic signatures on both the CMB temperature, E-mode, and B-mode polarization anisotropies. We place constraints on the properties of the primordial vector mode characterized by the vector-to-scalar ratio r{sub v} and the spectral index n{sub v} of the vector-shear power spectrum, from the Planck and BICEP2 B-mode data. We find that, for scale-invariant initial spectra, the ΛCDM model including the vector mode fits the data better than the model including the tensor mode. The difference in χ{sup 2} between the vector and tensor models is Δχ{sup 2} = 3.294, because, on large scales the vector mode generates smaller temperature fluctuations than the tensor mode, which is preferred for the data. In contrast, the tensor mode can fit the data set equally well if we allow a significantly blue-tilted spectrum. We find that the best-fitting tensor mode has a large blue tilt and leads to an indistinct reionization bump on larger angular scales. The slightly red-tilted vector mode supported by the current data set can also create O(10{sup -22})-Gauss magnetic fields at cosmological recombination. Our constraints should motivate research that considers models of the early Universe that involve the vector mode.
Institute of Scientific and Technical Information of China (English)
冯晓
2011-01-01
Aesthetics has become a hard subject to learn because of its philosophy and abstract theory. Taking the local music culture as its basis, and combining the modem teaching mode, the author applies theoretical study to practice to help students better understand and ponder over relevant theory of music aesthetics, thus fully exerting the double effects played by music aesthetics upon the music theoretical system, which can lay solid foundation for improving the music theoretical cultivation and research level of college students.%音乐美学学科因其主要以哲学为基础，理论性极强，已成为高校音乐理论课程中很难学习的一门课程。笔者根据它的这一特点，在教学实践中采取了以当地音乐文化为基点，结合现代的教学模式，将理论的学习真正地应用到实践的过程中，帮助学生在实践过程中更好地理解、思考相关的音乐美学理论点，从而充分发挥出音乐美学学科在音乐理论体系框架中基础性、指导性的双重重要作用，为提高高校师范生整体音乐理论素养与理论研究水平，打下坚实的基础。
Institute of Scientific and Technical Information of China (English)
甘建荣
2012-01-01
数字传播背景下电视传播受网络传播和手机传播“信息超市”裹挟，特别是智能手机的升级传播，微博自媒体的兴起，导致其传播效率、传播权威衰减。于是破解瓶颈的制度、运营、技术“三大创新”之说颇受关注。而电视媒体借势新媒体的媒介融合，则成为目前技术创新的最大特征。本文以凉山电视台实践为例，就从技术创新融合发展，创新传播手段，优化本土传播模式的有效路径进行了探索。% Affected by the internet and mobile phone communication,especially the upgrade transmission of the smart phone,the rise of micro blog,the spread efficiency and authority of television media becomes weak in the background of digital communication. Then crack the bottleneck of system、the operations and the technology becomes popular attention. An occasion of new media integration,television media become the biggest feature of the technological innovation. In this paper we take the Liangshan television station as an example,focus on the integrated development of technical innovation,the development of innovative way of communication,to optimize the effective path of the local mode of transmission.
Sliding Mode Thermal Control System for Space Station Furnace Facility
Jackson Mark E.; Shtessel, Yuri B.
1998-01-01
The decoupled control of the nonlinear, multiinput-multioutput, and highly coupled space station furnace facility (SSFF) thermal control system is addressed. Sliding mode control theory, a subset of variable-structure control theory, is employed to increase the performance, robustness, and reliability of the SSFF's currently designed control system. This paper presents the nonlinear thermal control system description and develops the sliding mode controllers that cause the interconnected subsystems to operate in their local sliding modes, resulting in control system invariance to plant uncertainties and external and interaction disturbances. The desired decoupled flow-rate tracking is achieved by optimization of the local linear sliding mode equations. The controllers are implemented digitally and extensive simulation results are presented to show the flow-rate tracking robustness and invariance to plant uncertainties, nonlinearities, external disturbances, and variations of the system pressure supplied to the controlled subsystems.
New localization mechanism and Hodge duality for q -form field
Fu, Chun-E.; Liu, Yu-Xiao; Guo, Heng; Zhang, Sheng-Li
2016-03-01
In this paper, we investigate the problem of localization and the Hodge duality for a q -form field on a p -brane with codimension one. By a general Kaluza-Klein (KK) decomposition without gauge fixing, we obtain two Schrödinger-like equations for two types of KK modes of the bulk q -form field, which determine the localization and mass spectra of these KK modes. It is found that there are two types of zero modes (the 0-level modes): a q -form zero mode and a (q -1 )-form one, which cannot be localized on the brane at the same time. For the n -level KK modes, there are two interacting KK modes, a massive q -form KK mode and a massless (q -1 )-form one. By analyzing gauge invariance of the effective action and choosing a gauge condition, the n -level massive q -form KK mode decouples from the n -level massless (q -1 )-form one. It is also found that the Hodge duality in the bulk naturally becomes two dualities on the brane. The first one is the Hodge duality between a q -form zero mode and a (p -q -1 )-form one, or between a (q -1 )-form zero mode and a (p -q )-form one. The second duality is between two group KK modes: one is an n -level massive q -form KK mode with mass mn and an n -level massless (q -1 )-form mode; another is an n -level (p -q )-form one with the same mass mn and an n -level massless (p -q -1 )-form mode. Because of the dualities, the effective field theories on the brane for the KK modes of the two dual bulk form fields are physically equivalent.
Atomic dynamics in the mode-mode competition system
Institute of Scientific and Technical Information of China (English)
Wu Qin; Fang Mao-Fa
2004-01-01
The atomic dynamical properties in the system with competing k-photon and l-photon transitions are studied fully by means of quantum theory. We discuss the influences of the mode-mode competition, the relative competing strengths of the atom and the two-mode field, and the initial state of the system on the atomic dynamics. We show that the presence of the mode-mode competition can result in quite a periodical collapses-revivals of the atomic inversion and the increase of the initial photons of the system can lead to the collapse-revival phenomenon and prolong the revival time of the atomic inversion.
Local Professionals for Local Market
Institute of Scientific and Technical Information of China (English)
Wen Xiaojie
2010-01-01
@@ In the past three decades,the Chinese hotel industry has developed at a rapid pace,with the number of hotels-especially high star hotelsgrowing fast.In Beijing alone,there arc nearly 60 five-star hotels.With the development of the hotel industry.China has also begun to see the number of local hotel professionals,including senior managers,increase.Wen Xiaojie,Deputy General Manager and Owner's Representative of Sofitel Wanda Beijing,is among the most outstanding senior hotel managers.
Whistler mode waves in the Jovian magnetosheath
Lin, Naiguo; Kellogg, P. J.; Thiessen, J. P.; Lengyel-Frey, D.; Tsurutani, B. T.; Phillips, J. L.
1994-01-01
During the Ulysses flyby of Jupiter in February 1992, the spacecraft traversed the Jovian magnetosheath for a few hours during the inbound pass and for aa few days during the outbound pass. Burstlike electomagnetic waves at frequencies of approximately 0.1-0.4 of the local electron cyclotron frequency have been observed by the Unified Radio and Plasma Wave (URAP) experiement. The waves were more often observed in the regions which were probably the outer or the middle magnetosheath, especially near the bow shock, and rarely seen in the magnetosphere/magnetosheath boundary layer. The propagation angles of the waves are estimated by comparing the measurements of the wave electric and magnetic fields in the spacecraft spin plane with the corresponding values calculated using the cold plasma dispersion relation under local field and plasma conditions. It is found that the waves propagate obliquely with wave angles between approximately 30 deg and 50 deg. These waves are likely to be the whistler mode waves which are excited by suprathermal electrons with a few hundred eV and a slight anisotropy (T(sub perp)/T(sub parallel) approximately 1.1-1.5). They are probably similar in nature to the lion roars observed in the Earth's magnetosheath. Signature of coupling between the mirror and the whistler mode have also been observed. The plasma conditions which favor the excitation of the whistler mode instability during the wave events exists as observed by the plasma experiement of Ulysses.
Mode interactions of a high-subsonic deep cavity
Chen, Zhenli; Adams, Nikolaus A.
2017-05-01
To understand the interactions of the acoustic modes associated with the tunnel walls and the cavity oscillations in the experiment, flows over a deep cavity having a length-to-depth ratio L/D = 0.42 at high subsonic speeds with and without an upper tunnel wall were investigated by using an implicit large-eddy simulation with an adaptive local deconvolution method. The results of the simulations with the upper tunnel wall converge well to the experimental results as the resolution increases. However, in the simulations without the upper tunnel wall the flow converges to a different mean state. The mode interactions were analyzed by using a Dynamic Mode Decomposition (DMD) method based on a memory-efficient snapshot algorithm. It was found that nearly trapped global modes, which have almost zero upstream and downstream radiation, can occur. The interactions of the trapped modes, the acoustic resonant modes in the cavity, and the shear-layer modes can be observed in the DMD modes of the flow with the upper tunnel wall, which results in the enhancement of harmonic modes and the existence of higher-order modes. In the flow without the upper tunnel wall, the pressure waves can transmit freely away from the cavity, but the interactions of the acoustic resonant modes and the shear-layer modes can also be observed when the frequencies of both kinds of modes coincide. The effects of the ratio of the cavity depth to the tunnel height (D/H) on the formation of trapped modes were also investigated. As the ratio D/H decreases, the frequency window of the trapped modes shrinks and finally closes, which is consistent with a theoretical model. It can be concluded that the effects of the upper tunnel wall on the dynamics of the cavity flow are strong and are promoted by the interactions of different kinds of modes. The appearance and enhancement of high order harmonic modes in the high-subsonic deep cavity are due to the effects of the trapped modes, but are not due to the directly
Wave propagation of coupled modes in the DNA double helix
Energy Technology Data Exchange (ETDEWEB)
Tabi, C B; Ekobena Fouda, H P [Laboratory of Biophysics, Department of Physics, Faculty of Science, University of Yaounde I, PO Box 812, Yaounde (Cameroon); Mohamadou, A [Condensed Matter Laboratory, Department of Physics, Faculty of Science, University of Douala, PO Box 24157, Douala (Cameroon); Kofane, T C, E-mail: contab408@hotmail.com [Laboratory of Mechanics, Department of Physics, Faculty of Science, University of Yaounde I, PO Box 812, Yaounde (Cameroon)
2011-03-15
The remarkable dynamics of waves propagating along the DNA molecule is described by the coupled nonlinear Schroedinger equations. We consider both the single and the coupled nonlinear excitation modes and, under numerical simulations of the Peyrard-Bishop model, with the use of realistic values of parameters, their biological implications are studied. Furthermore, the characteristics of the coupled mode solution are discussed and we show that such a solution can describe the local opening observed within the transcription and the replication phenomena.
2010-01-01
Für den Tourfilm 101 der Synthie-Pop-Gruppe Depeche Mode wurde der bekannte Musikdokumentarfilmer D.A. Pennebaker zusammen mit seiner Ehefrau Chris Hedegus sowie David Dawkins engagiert, um die letzten Etappen der Tour filmisch im Stile des Direct Cinema zu begleiten. Die Wahl fiel deshalb auf genau dieses Filmteam, weil die Band einen unmanipulierten Einblick ins Tourleben geben wollte und man in Pennebaker und seinen Mitstreitern dafür die richtigen Leute vermutete. Der Sänger Dave Gahan er...
Surface modes in sheared boundary layers over impedance linings
Brambley, E. J.
2013-08-01
Surface modes, being duct modes localized close to the duct wall, are analysed within a lined cylindrical duct with uniform flow apart from a thin boundary layer. As well as full numerical solutions of the Pridmore-Brown equation, simplified mathematical models are given where the duct lining and boundary layer are lumped together and modelled using a single boundary condition (a modification of the Myers boundary condition previously proposed by the author), from which a surface mode dispersion relation is derived. For a given frequency, up to six surface modes are shown to exist, rather than the maximum of four for uniform slipping flow. Not only is the different number and behaviour of surface modes important for frequency-domain mode-matching techniques, which depend on having found all relevant modes during matching, but the thin boundary layer is also shown to lead to different convective and absolute stability than for uniform slipping flow. Numerical examples are given comparing the predictions of the surface mode dispersion relation to full solutions of the Pridmore-Brown equation, and the accuracy with which surface modes are predicted is shown to be significantly increased compared with the uniform slipping flow assumption. The importance of not only the boundary layer thickness but also its profile (tanh or linear) is demonstrated. A Briggs-Bers stability analysis is also performed under the assumption of a mass-spring-damper or Helmholtz resonator impedance model.
Resistive Edge Modes in Stellarator and Tokamak Geometries
Energy Technology Data Exchange (ETDEWEB)
Ansar Mahmood, M.; Persson, M.; Rafiq, T.
2007-07-01
The reactive ion-temperature-gradient driven drift mode (or mode) is a promising candidate for explaining the anomalous transport in the core of tokamak plasmas. However, a strong influence of electron-ion collisions in the edge region gives a resistive nature to the drift modes. So far, a lot of work has been done towards understanding of these modes in tokamak configurations, whereas a limited amount of work has been reported in stellarators. In the present work, linear stability of the collisional mode and the resistive ballooning mode in the electrostatic limit is studied in a three-dimensional Wendelstein 7-X Stellarator geometry. The full magnetic field configuration is obtained using the variational moments equilibrium code VMEC. The reduced Braghinskii equations are used as a model for the electrons and an advanced fluid model for the ions. By employing the ballooning mode formalism, the drift wave problem is set as an eigenvalue equation along a field line. The derived eigenvalue equation is solved numerically using a standard shooting technique and applying WKB type boundary conditions. The growth rates and real frequencies of the most unstable modes and their eigenfunctions are calculated. The effects of collisions, density and temperature gradients and other geometrical quantities on mode localization and stability are studied. Finally, the results are contrasted and compared with those obtained for an ITER-like geometry. (Author)
ACCA College English Teaching Mode
Ding, Renlun
2008-01-01
This paper elucidates a new college English teaching mode--"ACCA" (Autonomous Cooperative Class-teaching All-round College English Teaching Mode). Integrated theories such as autonomous learning and cooperative learning into one teaching mode, "ACCA", which is being developed and advanced in practice as well, is the achievement…
Fluxon modes in superconducting multilayers
DEFF Research Database (Denmark)
Pedersen, Niels Falsig; Madsen, Søren Peder
2004-01-01
We show how to construct fluxon modes from plasma modes in the inductively coupled stacked Josephson junctions, and consider some special cases of these fluxon modes analytically. In some cases we can find exact analytical solutions when we choose the bias current in a special way. We also consid...
Standardization of Keyword Search Mode
Su, Di
2010-01-01
In spite of its popularity, keyword search mode has not been standardized. Though information professionals are quick to adapt to various presentations of keyword search mode, novice end-users may find keyword search confusing. This article compares keyword search mode in some major reference databases and calls for standardization. (Contains 3…
Multiresonance modes in sine-Gordon brane models
Cruz, W T; Almeida, C A S
2015-01-01
In this work, we study the localization of the vector gauge field in two five-dimensional braneworlds generated by scalar fields coupled to gravity. The sine-Gordon like potentials are employed to produce different thick brane setups. A zero mode localized is obtained, and we show the existence of reverberations with the wave solutions indicating a quasi-localized massive mode. More interesting results are achieved when we propose a double sine-Gordon potential to the scalar field. The resulting thick brane shows a more detailed topology with the presence of an internal structure composed by two kinks. The massive spectrum of the gauge field is revalued on this scenario revealing the existence of various resonant modes
Entry modes of European firms in Vietnam
Directory of Open Access Journals (Sweden)
Daniel Simonet
2012-09-01
Full Text Available Purpose: The purpose of the paper is to explore the entry modes of EU firms setting up operations in Vietnam. Design/methodology/approach: we use a case study approach on Haymarket, Cadbury, Creative Education, Fairchild, Aventis and Artemisinin and Farming International using interviews from managerial professionals in Vietnam. Findings: Despite the fact that Vietnam has been opening up for more than 20 years, licensing is the preferred entry mode because of the risks involved in venturing with local firms; that preference signals a low level commitment and a high perception of risk and state interference. In line with Vietnam transition to state - rather than private market - capitalism, a foreign company opting for a joint-venture will do so with a state-owned rather than privately-owned company. The choice of a subsidiary can be explained by the lack of trust in partners and institutions, not by improvement in the socio-political environment. Limitations: In determining the entry mode strategy, the paper focuses on the Uppsala school’s “psychic distance” (e.g. cultural distance, lack of trust rather than on firm-specific advantages (Rugman, 1980; 2006. Key-words: international entry mode; emerging markets; subsidiary; joint-venture; India; Vietnam
Gravity localization in sine-Gordon braneworlds
Energy Technology Data Exchange (ETDEWEB)
Cruz, W.T., E-mail: wilamicruz@gmail.com [Instituto Federal de Educação, Ciência e Tecnologia do Ceará (IFCE), Campus Juazeiro do Norte, 63040-540 Juazeiro do Norte, Ceará (Brazil); Maluf, R.V., E-mail: r.v.maluf@fisica.ufc.br [Departamento de Física, Universidade Federal do Ceará (UFC), C.P. 6030, 60455-760 Fortaleza, Ceará (Brazil); Sousa, L.J.S., E-mail: luisjose@fisica.ufc.br [Instituto Federal de Educação, Ciência e Tecnologia do Ceará (IFCE), Campus Canindé, 62700-000 Canindé, Ceará (Brazil); Almeida, C.A.S., E-mail: carlos@fisica.ufc.br [Departamento de Física, Universidade Federal do Ceará (UFC), C.P. 6030, 60455-760 Fortaleza, Ceará (Brazil)
2016-01-15
In this work we study two types of five-dimensional braneworld models given by sine-Gordon potentials. In both scenarios, the thick brane is generated by a real scalar field coupled to gravity. We focus our investigation on the localization of graviton field and the behaviour of the massive spectrum. In particular, we analyse the localization of massive modes by means of a relative probability method in a Quantum Mechanics context. Initially, considering a scalar field sine-Gordon potential, we find a localized state to the graviton at zero mode. However, when we consider a double sine-Gordon potential, the brane structure is changed allowing the existence of massive resonant states. The new results show how the existence of an internal structure can aid in the emergence of massive resonant modes on the brane.
Controlling Anderson localization in disordered photonic crystal waveguides
DEFF Research Database (Denmark)
Garcia-Fernández, David; Smolka, Stephan; Stobbe, Søren
2010-01-01
of a disordered photonic crystal waveguide and attributed to Anderson localization. We have tested this hypothesis by measuring the light localization length, ξloc, in a disordered photonic crystal waveguide and checked explicitly the criterion of one dimensional Anderson localization that ξloc is shorter than...... the waveguide length LS. Our measurements demonstrate for the first time the close relation between light localization and density of states, which can be used ultimately for controlling Anderson localized modes....
Controlling Anderson localization in disordered photonic crystal waveguides
DEFF Research Database (Denmark)
Garcia-Fernández, David; Smolka, Stephan; Stobbe, Søren;
2010-01-01
of a disordered photonic crystal waveguide and attributed to Anderson localization. We have tested this hypothesis by measuring the light localization length, ξloc, in a disordered photonic crystal waveguide and checked explicitly the criterion of one dimensional Anderson localization that ξloc is shorter than...... the waveguide length LS. Our measurements demonstrate for the first time the close relation between light localization and density of states, which can be used ultimately for controlling Anderson localized modes....
RF Localization in Indoor Environment
Directory of Open Access Journals (Sweden)
M. Stella
2012-06-01
Full Text Available In this paper indoor localization system based on the RF power measurements of the Received Signal Strength (RSS in WLAN environment is presented. Today, the most viable solution for localization is the RSS fingerprinting based approach, where in order to establish a relationship between RSS values and location, different machine learning approaches are used. The advantage of this approach based on WLAN technology is that it does not need new infrastructure (it reuses already and widely deployed equipment, and the RSS measurement is part of the normal operating mode of wireless equipment. We derive the Cramer-Rao Lower Bound (CRLB of localization accuracy for RSS measurements. In analysis of the bound we give insight in localization performance and deployment issues of a localization system, which could help designing an efficient localization system. To compare different machine learning approaches we developed a localization system based on an artificial neural network, k-nearest neighbors, probabilistic method based on the Gaussian kernel and the histogram method. We tested the developed system in real world WLAN indoor environment, where realistic RSS measurements were collected. Experimental comparison of the results has been investigated and average location estimation error of around 2 meters was obtained.
Orme, John S.; Nobbs, Steven G.
1995-01-01
The minimum fuel mode of the NASA F-15 research aircraft is designed to minimize fuel flow while maintaining constant net propulsive force (FNP), effectively reducing thrust specific fuel consumption (TSFC), during cruise flight conditions. The test maneuvers were at stabilized flight conditions. The aircraft test engine was allowed to stabilize at the cruise conditions before data collection initiated; data were then recorded with performance seeking control (PSC) not-engaged, then data were recorded with the PSC system engaged. The maneuvers were flown back-to-back to allow for direct comparisons by minimizing the effects of variations in the test day conditions. The minimum fuel mode was evaluated at subsonic and supersonic Mach numbers and focused on three altitudes: 15,000; 30,000; and 45,000 feet. Flight data were collected for part, military, partial, and maximum afterburning power conditions. The TSFC savings at supersonic Mach numbers, ranging from approximately 4% to nearly 10%, are in general much larger than at subsonic Mach numbers because of PSC trims to the afterburner.
Schopf, J.M.
1975-01-01
The processes of geologic preservation are important for understanding the organisms represented by fossils. Some fossil differences are due to basic differences in organization of animals and plants, but the interpretation of fossils has also tended to be influenced by modes of preservation. Four modes of preservation generally can be distinguished: (1) Cellular permineralization ("petrifaction") preserves anatomical detail, and, occasionally, even cytologic structures. (2) Coalified compression, best illustrated by structures from coal but characteristic of many plant fossils in shale, preserves anatomical details in distorted form and produces surface replicas (impressions) on enclosing matrix. (3) Authigenic preservation replicates surface form or outline (molds and casts) prior to distortion by compression and, depending on cementation and timing, may intergrade with fossils that have been subject to compression. (4) Duripartic (hard part) preservation is characteristic of fossil skeletal remains, predominantly animal. Molds, pseudomorphs, or casts may form as bulk replacements following dissolution of the original fossil material, usually by leaching. Classification of the kinds of preservation in fossils will aid in identifying the processes responsible for modifying the fossil remains of both animals and plants. ?? 1975.
Towards an emerging understanding of non-locality phenomena and non-local transport
Ida, K.; Shi, Z.; Sun, H. J.; Inagaki, S.; Kamiya, K.; Rice, J. E.; Tamura, N.; Diamond, P. H.; Dif-Pradalier, G.; Zou, X. L.; Itoh, K.; Sugita, S.; Gürcan, O. D.; Estrada, T.; Hidalgo, C.; Hahm, T. S.; Field, A.; Ding, X. T.; Sakamoto, Y.; Oldenbürger, S.; Yoshinuma, M.; Kobayashi, T.; Jiang, M.; Hahn, S. H.; Jeon, Y. M.; Hong, S. H.; Kosuga, Y.; Dong, J.; Itoh, S.-I.
2015-01-01
In this paper, recent progress on experimental analysis and theoretical models for non-local transport (non-Fickian fluxes in real space) is reviewed. The non-locality in the heat and momentum transport observed in the plasma, the departures from linear flux-gradient proportionality, and externally triggered non-local transport phenomena are described in both L-mode and improved-mode plasmas. Ongoing evaluation of ‘fast front’ and ‘intrinsically non-local’ models, and their success in comparisons with experimental data, are discussed
Viscous, Resistive Magnetorotational Modes
DEFF Research Database (Denmark)
Pessah, Martin Elias; Chan, Chi-kwan
2008-01-01
We carry out a comprehensive analysis of the behavior of the magnetorotational instability (MRI) in viscous, resistive plasmas. We find exact, non-linear solutions of the non-ideal magnetohydrodynamic (MHD) equations describing the local dynamics of an incompressible, differentially rotating...
Simulation of peeling-ballooning modes with pellet injection
Energy Technology Data Exchange (ETDEWEB)
Chen, S. Y. [College of Physical Science and Technology, Sichuan University, 610064 Chengdu (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Southwestern Institute of Physics, Chengdu 610041 (China); Huang, J.; Sun, T. T.; Tang, C. J. [College of Physical Science and Technology, Sichuan University, 610064 Chengdu (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Wang, Z. H. [Southwestern Institute of Physics, Chengdu 610041 (China)
2014-11-15
The influence of pellet ablation on the evolution of peeling-ballooning (P-B) modes is studied with BOUT++ code. The atoms coming from pellet ablation can significantly reshape the plasma pressure profile, so the behaviors of P-B modes and edge localized mode (ELM) are modified dramatically. This paper shows that the energy loss associated with an ELM increases substantially over that without the pellet, if the pellet is deposited at the top of the pedestal. On the contrary, for pellet deposition in the middle of the pedestal region the ELM energy loss can be less.
Locked modes and magnetic field errors in MST
Energy Technology Data Exchange (ETDEWEB)
Almagri, A.F.; Assadi, S.; Prager, S.C.; Sarff, J.S.; Kerst, D.W.
1992-06-01
In the MST reversed field pinch magnetic oscillations become stationary (locked) in the lab frame as a result of a process involving interactions between the modes, sawteeth, and field errors. Several helical modes become phase locked to each other to form a rotating localized disturbance, the disturbance locks to an impulsive field error generated at a sawtooth crash, the error fields grow monotonically after locking (perhaps due to an unstable interaction between the modes and field error), and over the tens of milliseconds of growth confinement degrades and the discharge eventually terminates. Field error control has been partially successful in eliminating locking.
Tearing mode stability calculations with pressure flattening
Ham, C J; Cowley, S C; Hastie, R J; Hender, T C; Liu, Y Q
2013-01-01
Calculations of tearing mode stability in tokamaks split conveniently into an external region, where marginally stable ideal MHD is applicable, and a resonant layer around the rational surface where sophisticated kinetic physics is needed. These two regions are coupled by the stability parameter. Pressure and current perturbations localized around the rational surface alter the stability of tearing modes. Equations governing the changes in the external solution and - are derived for arbitrary perturbations in axisymmetric toroidal geometry. The relationship of - with and without pressure flattening is obtained analytically for four pressure flattening functions. Resistive MHD codes do not contain the appropriate layer physics and therefore cannot predict stability directly. They can, however, be used to calculate -. Existing methods (Ham et al. 2012 Plasma Phys. Control. Fusion 54 025009) for extracting - from resistive codes are unsatisfactory when there is a finite pressure gradient at the rational surface ...
Vanderbei, Robert J
2012-01-01
Using 55 years of daily average temperatures from a local weather station, I made a least-absolute-deviations (LAD) regression model that accounts for three effects: seasonal variations, the 11-year solar cycle, and a linear trend. The model was formulated as a linear programming problem and solved using widely available optimization software. The solution indicates that temperatures have gone up by about 2 degrees Fahrenheit over the 55 years covered by the data. It also correctly identifies the known phase of the solar cycle; i.e., the date of the last solar minimum. It turns out that the maximum slope of the solar cycle sinusoid in the regression model is about the same size as the slope produced by the linear trend. The fact that the solar cycle was correctly extracted by the model is a strong indicator that effects of this size, in particular the slope of the linear trend, can be accurately determined from the 55 years of data analyzed. The main purpose for doing this analysis is to demonstrate that it i...
Djokoto, E
1997-11-01
In 1991, in the northern region of Ghana, during the cholera epidemic, 10 rural health centers replied to a questionnaire regarding cholera case referrals. The results were as follows: 6 centers referred serious cases to hospitals, 2 did not receive patients because of fear of infection, and 2 received all patients. Although no patients admitted to the rural health centers died, many of the referred patients did. Of 14 cases referred to a hospital, 3 died in transit, 4 died at the hospital, and 7 survived. Deaths might be prevented if patients were treated promptly and locally with oral rehydration solutions based on cereals and rice; these are easy to prepare, superior to, and more available than standard oral rehydration salts (ORS). One mother walked 5 miles to a rural health post with her sick baby on her back, only to find that the dehydrated child had died on the way. During the 1991 cholera epidemic in Ghana, the author treated several patients in their homes; all recovered. Prompt and frequent rehydration in the home is the best treatment for diarrhea and cholera.
Detection limits in plasmonic whispering gallery mode biosensors
Swaim, Jon D; Bowen, Warwick P
2011-01-01
We analyze a whispering gallery mode biosensor with a metallic nanorod bound to its surface. It is found that a localized surface plasmon resonance in the nanorod can reduce the optical mode volume of the resonator by as much as four orders of magnitude via a local enhancement of the electric field, thus improving the detection sensitivity. Optical frequency shifts as large as 15 MHz are predicted for typical proteins and, for typical experimental parameters, the biosensor is predicted to be limited by laser frequency noise, leading to a minimum detectable polarizability on the order of 10 cubic angstroms.
Vibration mode analysis of the proton exchange membrane fuel cell stack
Liu, B.; Liu, L. F.; Wei, M. Y.; Wu, C. W.
2016-11-01
Proton exchange membrane fuel cell (PEMFC) stacks usually undergo vibration during packing, transportation, and serving time, in particular for those used in the automobiles or portable equipment. To study the stack vibration response, based on finite element method (FEM), a mode analysis is carried out in the present paper. Using this method, we can distinguish the local vibration from the stack global modes, predict the vibration responses, such as deformed shape and direction, and discuss the effects of the clamping configuration and the clamping force magnitude on vibration modes. It is found that when the total clamping force remains the same, increasing the bolt number can strengthen the stack resistance to vibration in the clamping direction, but cannot obviously strengthen stack resistance to vibration in the translations perpendicular to clamping direction and the three axis rotations. Increasing the total clamping force can increase both of the stack global mode and the bolt local mode frequencies, but will decrease the gasket local mode frequency.
Localized motion in random matrix decomposition of complex financial systems
Jiang, Xiong-Fei; Zheng, Bo; Ren, Fei; Qiu, Tian
2017-04-01
With the random matrix theory, we decompose the multi-dimensional time series of complex financial systems into a set of orthogonal eigenmode functions, which are classified into the market mode, sector mode, and random mode. In particular, the localized motion generated by the business sectors, plays an important role in financial systems. Both the business sectors and their impact on the stock market are identified from the localized motion. We clarify that the localized motion induces different characteristics of the time correlations for the stock-market index and individual stocks. With a variation of a two-factor model, we reproduce the return-volatility correlations of the eigenmodes.
Adaptive mode control in few mode fibers and its applications
Ashry, Islam; Lu, Peng; Xu, Yong
2016-10-01
With the development of mode-division-multiplexing (MDM), few mode fibers (FMFs) have found a wide range of applications in optical sensing and communications. However, how to precisely control the mode composition of optical signals in FMFs remains a difficult challenge. In this paper, we present an adaptive mode control method that can selectively excite the linearly polarized (LP) mode within the FMF. The method is based on using optical pulses reflected by a fiber Bragg grating (FBG) for wavefront optimization. Two potential applications are discussed. First, we theoretically demonstrate the feasibility of large scale multiplexing of absorption based fiber optical sensors. Second, we discuss the possibility of using mode dependent loss to reconstruct the spatial distributions of absorptive chemicals diffused within a FMF.
Effect of Pump Area on Lasing Modes in Active Random Media
Institute of Scientific and Technical Information of China (English)
XIE Ying-Mao; LIU Zheng-Dong
2005-01-01
@@ We investigate the effect of pump area on lasing modes in an active random medium. Considering the structure characteristics in a real experimental system, the random medium is divided into two regions, i.e. pump and non-pump areas. The dependence of lasing modes on the pump area is qualitatively explained by means of the model in which the lasing is ascribed to the interaction of the complex localized modes in the active random medium with local aperiodic quasi-structure with appropriate pump light. There exist different pump sizes for lasing with different modes. As the pump size decreases in this random system, the pump threshold of the lasing modes increases. There are different lasing modes in different excitation regions in this random system. This gives us some information about the dependence of lasing modes on pump areas in active random media.
Modeling of Ad-hoc and Infrastructure Dual Mode Mobile Networks
Institute of Scientific and Technical Information of China (English)
Yi-Hung Chen; Hui-Nien Hung; Yi-Bing Lin; Nan-Fu Peng
2005-01-01
This paper investigates a mobile telecommunications system that supports both ad hoc and infrastructure mode operations. Based on analytic and simulation models, our study investigates how base station (BS) and ad hoc channel capacity, and the mobility and locality of mobile stations affect the performance of a dual mode system. We show that a dual mode system can significantly outperform a single mode (infrastructure) system when the degree of locality is high. Furthermore, a dual mode system can support much faster mobile users with less BS channels in comparison to an infrastructure mode system. Our study quantitatively identifies the threshold value for the number of ad hoc channels such that beyond this threshold, increasing ad hoc channel capacity will not improve the performance of a dual mode system.
Local approach to quantum entanglement
Ho-Chih, Lin
Quantum entanglement is the key property that makes quantum information theory different from its classical counterpart and is also a valuable physical resource with massive potential for technological applications. However, our understanding of entanglement is still far from com plete despite intense research activities. Like other physical resources, the first step towards exploiting them fully is to know how to quantify. There are many reasons to focus on the en tanglement of continuous-variable states since the underlying degrees of freedom of physical systems carrying quantum information are frequently continuous, rather than discrete. Much of the effort has been concentrated on Gaussian states, because these are common as the ground or thermal states of optical modes. Within this framework, many interesting topics have been stud ied and some significant progress made. Nevertheless, non-Gaussian states are also extremely important this is especially so in condensed-phase systems, where harmonic behaviour in any degree of freedom is likely to be only an approximation. So far, there is little knowledge about the quantification of entanglement in non-Gaussian states. This thesis aims to contribute to the active field of research in quantum entanglement by introducing a new approach to the analysis of entanglement, especially in continuous-variable states, and shows that it leads to the first systematic quantification of the (local) entanglement in arbitrary bipartite non-Gaussian states. By applying this local approach, many new insights can be gained. Notably, local entanglements of systems with smooth wavefunctions are fully characterised by the derived simple expressions, provided the wavefunction is known. The local (logarithmic) negativity of any two-mode mixed states can be directly computed from the closed-form formulae given. For multi-mode mixed states, this approach provides a scheme that permits much simpler numerical computation for quantifying
Li, Yan; Zeng, Xinglin; Mo, Qi; Li, Wei; Liu, Zhijian; Wu, Jian
2016-10-01
In few-mode polarization-maintaining-fiber (FM-PMF), the effective-index splitting exists not only between orthogonally polarization state but also between degenerated modes within a high-order mode group. Hence besides the polarization state evolution, the mode patterns in each LP set are need to be analyzed. In this letter, the completed firstorder mode (LP11 mode) evolution in PM-FMF is analyzed and represented by analogous Jones vector and Poincarésphere respectively. Furthermore, with Jones matrix analysis, the modal dynamics in FM-PMFs is conveniently analyzed. The conclusions are used to propose a PM-FMF based LP11 mode rotator and an PM-FMF based OAM generator. Both simulation and experiments are conducted to investigate performance of the two devices.
Gravity localization on hybrid branes
Energy Technology Data Exchange (ETDEWEB)
Veras, D.F.S., E-mail: franklin@fisica.ufc.br [Universidade Federal do Ceará (UFC), Departamento de Física, Campus do Pici, Caixa Postal 6030, 60455-760, Fortaleza, Ceará (Brazil); Cruz, W.T., E-mail: wilamicruz@gmail.com [Instituto Federal de Educação, Ciência e Tecnologia do Ceará (IFCE), Campus Juazeiro do Norte, 63040-540 Juazeiro do Norte, Ceará (Brazil); Maluf, R.V., E-mail: r.v.maluf@fisica.ufc.br [Universidade Federal do Ceará (UFC), Departamento de Física, Campus do Pici, Caixa Postal 6030, 60455-760, Fortaleza, Ceará (Brazil); Almeida, C.A.S., E-mail: carlos@fisica.ufc.br [Universidade Federal do Ceará (UFC), Departamento de Física, Campus do Pici, Caixa Postal 6030, 60455-760, Fortaleza, Ceará (Brazil)
2016-03-10
This work deals with gravity localization on codimension-1 brane worlds engendered by compacton-like kinks, the so-called hybrid branes. In such scenarios, the thin brane behavior is manifested when the extra dimension is outside the compact domain, where the energy density is non-trivial, instead of asymptotically as in the usual thick brane models. The zero mode is trapped in the brane, as required. The massive modes, although not localized in the brane, have important phenomenological implications such as corrections to the Newton's law. We study such corrections in the usual thick domain wall and in the hybrid brane scenarios. By means of suitable numerical methods, we attain the mass spectrum for the graviton and the corresponding wavefunctions. The spectra possess the usual linearly increasing behavior from the Kaluza–Klein theories. Further, we show that the 4D gravitational force is slightly increased at short distances. The first eigenstate contributes highly for the correction to the Newton's law. The subsequent normalized solutions have diminishing contributions. Moreover, we find out that the phenomenology of the hybrid brane is not different from the usual thick domain wall. The use of numerical techniques for solving the equations of the massive modes is useful for matching possible phenomenological measurements in the gravitational law as a probe to warped extra dimensions.
Gravity localization on hybrid branes
Veras, D. F. S.; Cruz, W. T.; Maluf, R. V.; Almeida, C. A. S.
2016-03-01
This work deals with gravity localization on codimension-1 brane worlds engendered by compacton-like kinks, the so-called hybrid branes. In such scenarios, the thin brane behavior is manifested when the extra dimension is outside the compact domain, where the energy density is non-trivial, instead of asymptotically as in the usual thick brane models. The zero mode is trapped in the brane, as required. The massive modes, although not localized in the brane, have important phenomenological implications such as corrections to the Newton's law. We study such corrections in the usual thick domain wall and in the hybrid brane scenarios. By means of suitable numerical methods, we attain the mass spectrum for the graviton and the corresponding wavefunctions. The spectra possess the usual linearly increasing behavior from the Kaluza-Klein theories. Further, we show that the 4D gravitational force is slightly increased at short distances. The first eigenstate contributes highly for the correction to the Newton's law. The subsequent normalized solutions have diminishing contributions. Moreover, we find out that the phenomenology of the hybrid brane is not different from the usual thick domain wall. The use of numerical techniques for solving the equations of the massive modes is useful for matching possible phenomenological measurements in the gravitational law as a probe to warped extra dimensions.
Automatic determination of important mode-mode correlations in many-mode vibrational wave functions.
König, Carolin; Christiansen, Ove
2015-04-14
We introduce new automatic procedures for parameterizing vibrational coupled cluster (VCC) and vibrational configuration interaction wave functions. Importance measures for individual mode combinations in the wave function are derived based on upper bounds to Hamiltonian matrix elements and/or the size of perturbative corrections derived in the framework of VCC. With a threshold, this enables an automatic, system-adapted way of choosing which mode-mode correlations are explicitly parameterized in the many-mode wave function. The effect of different importance measures and thresholds is investigated for zero-point energies and infrared spectra for formaldehyde and furan. Furthermore, the direct link between important mode-mode correlations and coordinates is illustrated employing water clusters as examples: Using optimized coordinates, a larger number of mode combinations can be neglected in the correlated many-mode vibrational wave function than with normal coordinates for the same accuracy. Moreover, the fraction of important mode-mode correlations compared to the total number of correlations decreases with system size. This underlines the potential gain in efficiency when using optimized coordinates in combination with a flexible scheme for choosing the mode-mode correlations included in the parameterization of the correlated many-mode vibrational wave function. All in all, it is found that the introduced schemes for parameterizing correlated many-mode vibrational wave functions lead to at least as systematic and accurate calculations as those using more standard and straightforward excitation level definitions. This new way of defining approximate calculations offers potential for future calculations on larger systems.
Energy Technology Data Exchange (ETDEWEB)
Stapp, Henry
2011-11-10
vagaries that he cites do not upset the proof in question. It is show here in detail why the precise statement of this theorem justifies the specified application of CQT. It is also shown, in response to his challenge, why a putative proof of locality that he has proposed is not valid.
Properties of standing Kruskal-Schwarzschild-modes at the magnetopause
Directory of Open Access Journals (Sweden)
F. Plaschke
2011-10-01
Full Text Available The radial, oscillatory motion of the Earth's magnetopause has been found to occur predominantly with some distinct, sometimes called "magic" frequencies, which have been attributed to magnetospheric wave guide modes, typical solar wind variations or, more recently, surface waves on the magnetopause standing between the northern and southern ionospheres. In this paper we present for the first time a derivation of these surface waves, denominated as Kruskal-Schwarzschild-modes (KS-modes, in the approximation of the ideal, single-fluid magnetohydrodynamic theory for incompressible plasmas. The calculations are performed in the simplified geometry of the box magnetosphere with the magnetopause being a plane between two plasma regimes of homogeneous conditions. The reflection of the KS-modes at the ionospheres is being discussed. Under the given assumptions and realistic conditions the validity of the calculations is shown to be limited to cases of parallel or anti-parallel background magnetic fields on both sides of the magnetopause, respectively. For these cases a detailed discussion of the mode structure is presented. The magnetopause when affected by a KS-mode is found to resemble a membrane under tension with respect to its motion; the ionospheres act as supporting points of the membrane and the KS-modes correspond in this picture to their eigenmodes of oscillation. Localized pressure enhancements in the magnetosheath are discussed as possible excitation mechanism for the KS-modes.
Proximity Resonance and Localized Surface Plasmons
Liu, Bo; Heller, Eric
2014-03-01
The collective excitation of conduction electrons in subwavelength nanostructures is known as Localized Surface Plasmon(LSP)[1]. Such plasmon modes has been intensively studied using noble nanoparticles . More recently, the possibility of building terahertz metamaterials supporting such LSP modes has been explored in graphene microribbons and microdisks. Unlike Surface Plasmon Polaritons(SPPs) at metal-insulator interface, LSP can be directly excited by light illumination and holds promise for applications in ultrasensitive biosensing, nano-optical tweezers and improved photovoltaic devices. In this paper, we consider the interaction of two LSPs in the weak coupling regime and show how an effect similar to the proximity resonance in the quantum scattering theory) gives rise to an asymmetric(quadrupole) mode with increased damping rate. The existence of this asymmetric mode relies on a small phase retardation between the two LSPs. This phase retardation, though small, is key to both increased damping rate for the asymmetric mode and reduced damping rate for the symmetric mode. When this small phase retardation is removed by changing the polarization of the exciting light,we show that the asymmetric mode can not be excited and the symmetric mode shows increased damping.
The Interaction of Optical Guided Modes with Waveguide Diffraction Gratings.
Weller-Brophy, Laura Ann
In this thesis the results of a theoretical and experimental investigation of the coupling of guided modes by waveguide gratings are presented. This work is motivated by the potential application of waveguide gratings to integrated optical devices. The coupling of guided modes obliquely incident to both periodic and aperiodic gratings is a mechanism basic to the operation of integrated optical components such as filters, reflectors, beamsplitters, and modulators. It is shown in the Introduction to this thesis, that this mechanism is not modeled consistently by the analyses presented in the literature. For the case of TM-TM coupling, virtually each analytical treatment predicts a different value for the grating reflectivity. In addition, it is found that the typical Coupled-Mode formalisms used to derive the grating reflectivity do not offer an intuitive picture of the operation of waveguide gratings. These two particular problem areas serve as the focal points of this thesis. The latter of these is addressed through the development of a thin film model of the operation of waveguide gratings. This model presents an intuitively appealing picture of the interaction of waveguide gratings and guided modes. It also yields grating reflectivities which are in excellent agreement with those obtained through the numerical solution of the Coupled-Mode equations for both periodic and aperiodic gratings. The bulk of this research project is directed towards resolving the conflicting theoretical grating analyses presented in the literature. A new derivation of the coupling of guided modes obliquely incident to periodic gratings is presented in Chapter II of this thesis. This derivation is based on the Local Normal Mode expansion used by Marcuse for the case of normal incidence. It produces coupling coefficients which are nearly identical to those derived using the rigorous Boundary Perturbation technique. The coupling coefficients predicted by this Local Normal Mode formalism
Nanoscale dielectric microscopy of non-planar samples by lift-mode electrostatic force microscopy.
Van Der Hofstadt, M; Fabregas, R; Biagi, M C; Fumagalli, L; Gomila, G
2016-10-01
Lift-mode electrostatic force microscopy (EFM) is one of the most convenient imaging modes to study the local dielectric properties of non-planar samples. Here we present the quantitative analysis of this imaging mode. We introduce a method to quantify and subtract the topographic crosstalk from the lift-mode EFM images, and a 3D numerical approach that allows for extracting the local dielectric constant with nanoscale spatial resolution free from topographic artifacts. We demonstrate this procedure by measuring the dielectric properties of micropatterned SiO2 pillars and of single bacteria cells, thus illustrating the wide applicability of our approach from materials science to biology.
Nanoscale dielectric microscopy of non-planar samples by lift-mode electrostatic force microscopy
Van Der Hofstadt, M.; Fabregas, R.; Biagi, M. C.; Fumagalli, L.; Gomila, G.
2016-10-01
Lift-mode electrostatic force microscopy (EFM) is one of the most convenient imaging modes to study the local dielectric properties of non-planar samples. Here we present the quantitative analysis of this imaging mode. We introduce a method to quantify and subtract the topographic crosstalk from the lift-mode EFM images, and a 3D numerical approach that allows for extracting the local dielectric constant with nanoscale spatial resolution free from topographic artifacts. We demonstrate this procedure by measuring the dielectric properties of micropatterned SiO2 pillars and of single bacteria cells, thus illustrating the wide applicability of our approach from materials science to biology.
Principal modes in fiber amplifiers
Fridman, Moti; Dubinskii, Mark; Friesem, Asher A; Davidson, Nir
2010-01-01
The dynamics of the state of polarization in single mode and multimode fiber amplifiers are presented. The experimental results reveal that although the state of polarizations at the output can vary over a large range when changing the temperatures of the fiber amplifiers, the variations are significantly reduced when resorting to the principal states of polarization in single mode fiber amplifiers and principal modes in multimode fiber amplifiers.
Passively mode locked Raman laser
Liang, W; Savchenkov, A A; Matsko, A B; Seidel, D; Maleki, L
2010-01-01
We report on the observation of a novel mode locked optical comb generated at the Raman offset (Raman comb) in an optically pumped crystalline whispering gallery mode resonator. Mode locking is confirmed via measurement of the radio-frequency beat note produced by the optical comb on a fast photodiode. Neither the conventional Kerr comb nor hyper-parametric oscillation is observed when the Raman comb is present.
Nonlinear plastic modes in disordered solids.
Gartner, Luka; Lerner, Edan
2016-01-01
We propose a theoretical framework within which a robust micromechanical definition of precursors to plastic instabilities, often termed soft spots, naturally emerges. They are shown to be collective displacements (modes) z[over ̂] that correspond to local minima of a barrier function b(z[over ̂]), which depends solely on inherent structure information. We demonstrate how some heuristic searches for local minima of b(z[over ̂]) can a priori detect the locus and geometry of imminent plastic instabilities with remarkable accuracy, at strains as large as γ_{c}-γ∼10^{-2} away from the instability strain γ_{c}. Our findings suggest that the a priori detection of the entire field of soft spots can be effectively carried out by a systematic investigation of the landscape of b(z[over ̂]).
Zero Modes and Entanglement Entropy
Yazdi, Yasaman K
2016-01-01
Ultraviolet divergences are widely discussed in studies of entanglement entropy. Also present, but much less understood, are infrared divergences due to zero modes in the field theory. In this note, we discuss the importance of carefully handling zero modes in entanglement entropy. We give an explicit example for a chain of harmonic oscillators in 1D, where a mass regulator is necessary to avoid an infrared divergence due to a zero mode. We also comment on a surprising contribution of the zero mode to the UV-scaling of the entanglement entropy.
Intelligence and musical mode preference
DEFF Research Database (Denmark)
Bonetti, Leonardo; Costa, Marco
2016-01-01
The relationship between fluid intelligence and preference for major–minor musical mode was investigated in a sample of 80 university students. Intelligence was assessed by the Raven’s Advanced Progressive Matrices. Musical mode preference was assessed by presenting 14 pairs of musical stimuli th...... differences at the cognitive and personality level related to the enjoyment of sad music.......The relationship between fluid intelligence and preference for major–minor musical mode was investigated in a sample of 80 university students. Intelligence was assessed by the Raven’s Advanced Progressive Matrices. Musical mode preference was assessed by presenting 14 pairs of musical stimuli...
Tomography of Spatial Mode Detectors
Bobrov, Ivan; Markov, Anton; Straupe, Stanislav; Kulik, Sergey
2014-01-01
Transformation and detection of photons in higher-order spatial modes usually requires complicated holographic techniques. Detectors based on spatial holograms suffer from non-idealities and should be carefully calibrated. We report a novel method for analyzing the quality of projective measurements in spatial mode basis inspired by quantum detector tomography. It allows us to calibrate the detector response using only gaussian beams. We experimentally investigate the inherent inaccuracy of the existing methods of mode transformation and provide a full statistical reconstruction of the POVM (positive operator valued measure) elements for holographic spatial mode detectors.
On the difficulty of determining tearing mode stability
Energy Technology Data Exchange (ETDEWEB)
Bishop, C.M.; Connor, J.W.; Hastie, R.J.; Cowley, S.C. (AEA Technology, Culham (United Kingdom))
1991-04-01
The effect of local pressure gradients and of a local flattening of the pressure profile (p' {yields} 0) around the resonant surface of a tearing mode is investigated in toroidal geometry. It is shown that the stability index {Delta}', calculated from the ideal outer region, is modified by local profile changes in a way reminiscent of the favourable curvature stabilization of linear and non-linear tearing mode layer theory. If the width of the region of pressure flattening is of the order of the linear resistive layer width, the stabilization from the ideal outer region compensates for the loss of pressure gradient stabilization from the layer, and the overall stability of the mode is largely unaffected. For pressure flattening over a larger region, however, the mode can be strongly destabilized. Since the flattening region may then still be too small to resolve experimentally, this result implies the essential difficulty of determining the tearing mode stability of experimental profiles. (Author).
DEFF Research Database (Denmark)
Xu, G.S.; Wan, B.N.; Li, J.G.
2011-01-01
The first high-confinement mode (H-mode) with type-III edge localized modes at an H factor of HIPB98(y,2) ~ 1 has been obtained with about 1 MW lower hybrid wave power on the EAST superconducting tokamak. The first H-mode plasma appeared after wall conditioning by lithium (Li) evaporation before ...
Single-mode squeezing in arbitrary spatial modes
Semmler, Marion; Chille, Vanessa; Gabriel, Christian; Banzer, Peter; Aiello, Andrea; Marquardt, Christoph; Leuchs, Gerd
2016-01-01
As the generation of squeezed states of light has become a standard technique in laboratories, attention is increasingly directed towards adapting the optical parameters of squeezed beams to the specific requirements of individual applications. It is known that imaging, metrology, and quantum information may benefit from using squeezed light with a tailored transverse spatial mode. However, experiments have so far been limited to generating only a few squeezed spatial modes within a given setup. Here, we present the generation of single-mode squeezing in Laguerre-Gauss and Bessel-Gauss modes, as well as an arbitrary intensity pattern, all from a single setup using a spatial light modulator (SLM). The degree of squeezing obtained is limited mainly by the initial squeezing and diffractive losses introduced by the SLM, while no excess noise from the SLM is detectable at the measured sideband. The experiment illustrates the single-mode concept in quantum optics and demonstrates the viability of current SLMs as fl...
Localized waves supported by the rotating waveguide array
Zhang, Xiao; Ye, Fangwei; Kartashov, Yaroslav V.; Vysloukh, Victor A.; Chen, Xianfeng
2016-09-01
We show that truncated rotating square waveguide arrays support new types of localized modes that exist even in the linear case, in complete contrast to localized excitations in nonrotating arrays requiring nonlinearity for their existence and forming above the energy flow threshold. These new modes appear either around array center, since rotation leads to the emergence of the effective attractive potential with a minimum at the rotation axis, or in the array corners, in which case localization occurs due to competition between centrifugal force (in terms of quasi-particle analogy) and total internal reflection at the interface of the truncated array. The degree of localization of the central and corner modes mediated by rotation increases with rotation frequency. Stable rotating soliton families bifurcating from linear modes are analyzed in both focusing and defocusing media.
Localized waves supported by the rotating waveguide array
Zhang, Xiao; Kartashov, Yaroslav V; Vysloukh, Victor A; Chen, Xianfeng
2016-01-01
We show that truncated rotating square waveguide arrays support new types of localized modes that exist even in the linear case, in complete contrast to localized excitations in nonrotating arrays requiring nonlinearity for their existence and forming above the energy flow threshold. These new modes appear either around array center, since rotation leads to the emergence of the effective attractive potential with a minimum at the rotation axis, or in the array corners, in which case localization occurs due to competition between centrifugal force (in terms of quasi-particle analogy) and total internal reflection at the interface of the truncated array. The degree of localization of the central and corner modes mediated by rotation increases with rotation frequency. Stable rotating soliton families bifurcating from linear modes are analyzed in both focusing and defocusing media.
Fast-Particle-Driven Alfvenic Modes in a Reversed Field Pinch
Energy Technology Data Exchange (ETDEWEB)
Koliner, J. J. [University of Wisconsin, Madison; Forest, C. B. [University of Wisconsin, Madison; Sarff, J. S. [University of Wisconsin, Madison; Anderson, J. [University of Wisconsin, Madison; Liu, D [University of Wisconsin, Madison; Nomberg, M. D. [University of Wisconsin, Madison; Waksman, J. [University of Wisconsin, Madison; Lin, L. [University of California, Los Angeles; Brower, D. L. [University of California, Los Angeles; Ding, W. X. [University of California, Los Angeles; Spong, Donald A [ORNL
2012-01-01
Alfvenic modes are observed due to neutral beam injection for the first time in a reversed field pinch plasma. Modeling of the beam deposition and slowing down shows that the velocity and radial localization are high. This allows instability drive from inverse Landau damping of a bump-on-tail in the parallel distribution function or from free energy in the fast ion density gradient. Mode switching from a lower frequency toroidal mode number n = 5 mode that scales with beam injection velocity to a higher frequency n = 4 mode with Alfvenic scaling is observed.
Raman modes in transferred bilayer CVD graphene
Directory of Open Access Journals (Sweden)
Niilisk Ahti
2015-01-01
Full Text Available A systematic experimental Raman spectroscopic study of twisted bilayer graphene (tBLG domains localized inside wide-area single layer graphene (SLG produced by low-pressure CVD on Cu foil and transferred onto SiO2/Si substrate has been performed. According to the Raman characterization the tBLG domains had a great variety of twisting angles θ between the bottom and top graphene layers (6° < θ < 25°. The twisting angle θ was estimated from the spectral position of the rotating R and R' modes in the Raman spectrum.Under G band resonance conditions the breathing mode ZO' with a frequency of 95- 97 cm−1 was detected, and a breathing mode ZO was found in the spectra between 804 cm−1 and 836 cm−1, its position depending on the twisting angle θ. An almost linear relationship was found between the frequencies ωZO and ωR. Also a few other spectral peculiarities were found, e.g. a high-energy excitation of the G band resonance, the 2G overtone appearing at 3170-3180 cm−1 by the G band resonance, revealing a linear dispersion of 80 cm−1/eV of the 2D band in tBLG
Majorana zero modes in spintronics devices
Wu, Chien-Te; Anderson, Brandon M.; Hsiao, Wei-Han; Levin, K.
2017-01-01
We show that topological phases should be realizable in readily available and well-studied heterostructures. In particular we identify a new class of topological materials which are well known in spintronics: helical ferromagnet-superconducting junctions. We note that almost all previous work on topological heterostructures has focused on creating Majorana modes at the proximity interface in effectively two-dimensional or one-dimensional systems. The particular heterostructures we address exhibit finite-range proximity effects leading to nodal superconductors with Majorana modes localized well away from this interface. To show this, we implement a Bogoliubov-de Gennes (BdG) proximity numerical scheme, which importantly involves two finite dimensions in a three-dimensional junction. Incorporating this level of numerical complexity serves to distinguish ours from alternative numerical BdG approaches which are limited by generally assuming translational invariance or periodic boundary conditions along multiple directions. With this access to the edges, we are then able to illustrate in a concrete fashion the wave functions of Majorana zero modes and, moreover, address finite-size effects. In the process we establish consistency with a simple analytical model.
Pulsed squeezed light: simultaneous squeezing of multiple modes
Wasilewski, W; Banaszek, K; Radzewicz, C; Wasilewski, Wojciech; Banaszek, Konrad; Radzewicz, Czeslaw
2005-01-01
We analyze the spectral properties of squeezed light produced by means of pulsed, single-pass degenerate parametric down-conversion. The multimode output of this process can be decomposed into characteristic modes undergoing independent squeezing evolution akin to the Schmidt decomposition of the biphoton spectrum. The main features of this decomposition can be understood using a simple analytical model developed in the perturbative regime. In the strong pumping regime, for which the perturbative approach is not valid, we present a numerical analysis, specializing to the case of one-dimensional propagation in a beta-barium borate waveguide. Characterization of the squeezing modes provides us with an insight necessary for optimizing homodyne detection of squeezing. For a weak parametric process, efficient squeezing is found in a broad range of local oscillator modes, whereas the intense generation regime places much more stringent conditions on the local oscillator. We point out that without meeting these cond...
Gravity localization in sine-Gordon braneworlds
Cruz, W T; Sousa, L J S; Almeida, C A S
2016-01-01
In this work we study two types of five-dimensional braneworld models given by sine-Gordon potentials. In both scenarios, the thick brane is generated by a real scalar field coupled to gravity. We focus our investigation on the localization of graviton field and the behaviour of the massive spectrum. In particular, we analyse the localization of massive modes by means of a relative probability method in a Quantum Mechanics context. Initially, considering a scalar field sine-Gordon potential, we find a resonance to the graviton at zero mode. However, when we consider a double sine-Gordon potential, the brane structure is changed allowing the existence of massless and massive resonant states. The new results show how the existence of an internal structure can aid in the emergence of massive resonant modes on the brane.
Electrically controlled optical-mode switch for fundamental mode and first order mode
Imansyah, Ryan; Tanaka, Tatsushi; Himbele, Luke; Jiang, Haisong; Hamamoto, Kiichi
2016-08-01
We have proposed an optical mode switch, the principle of which is based on the partial phase shift of injected light; therefore, one important issue is to clarify the proper design criteria for the mode combiner section. We focused on the bending radius of the S-bend waveguide issue that is connected to the multi mode waveguide in the Y-junction section that acts as mode combiner. Long radius leads to undesired mode coupling before the Y-junction section, whereas a short radius causes radiation loss. Thus, we simulated this mode combiner by the beam-propagation method to obtain the proper radius. In addition, we used a trench pin structure to simplify the fabrication process into a single-step dry-etching process. As a result, we successfully fabricated an optical-mode switch with the bending radius R = 610 µm. It showed the successful electrical mode switching and the achieved mode crosstalk was approximately -10 dB for 1550 nm wavelength with the injection current of 60 mA (5.7 V).
The inner structure of empirical mode decomposition
Wang, Yung-Hung; Young, Hsu-Wen Vincent; Lo, Men-Tzung
2016-11-01
The empirical mode decomposition (EMD) is a nonlinear method that is truly adaptive with good localization property in the time domain for analyzing non-stationary complex data. The EMD has been proven useful in a wide range of applications. However, due to the nonlinear and complex nature of the sifting process, the most essential step of the EMD, a firm mathematical foundation or a transparent physical description are still lacked for EMD. Here, we embark on constructing a mathematical theory of the sifting operator. We first show that the sifting operator can be expressed as the data plus the sum of the responses to the impulses (multiplied by the data value) at the extrema. Such an expression of the sifting operator is then used to investigate the adaptive nature and the localizing effect of the EMD. Alternatively, the sifting operator can also be represented by a sifting matrix, which depends nonlinearly on the extrema distribution. Based on the eigen-decomposition of the sifting matrix, the transfer function of the sifting process is analyzed. Finally we answer what an intrinsic mode function (IMF) is from the wave perspective by exploring the physical basis of the IMFs.
Cavity quantum electrodynamics in the Anderson-localized regime
DEFF Research Database (Denmark)
Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren
2010-01-01
We experimentally measure, by means of time-resolved photoluminescence spectroscopy, a 15-fold enhancement of the spontaneous emission decay rate of single semiconductor quantum dots coupled to disorder-induced Anderson-localized modes with efficiencies reaching 94%.......We experimentally measure, by means of time-resolved photoluminescence spectroscopy, a 15-fold enhancement of the spontaneous emission decay rate of single semiconductor quantum dots coupled to disorder-induced Anderson-localized modes with efficiencies reaching 94%....
Localization of matter and fermion resonances on double walls
Liang, Jun; Duan, Yi-Shi
2009-10-01
We investigate the possibility of localizing various matter fields on the double walls. For spin 0 scalar field, massless zero mode can be normalized on the double walls. However, for spin 1 vector field, the zero mode is not localized on the double walls. In the paper [C.A.S. Almeida, M.M. Ferreira Jr., A.R. Gomes, R. Casana, arxiv:arXiv:0901.3543 [hep-th
Localization of matter and fermion resonances on double walls
Energy Technology Data Exchange (ETDEWEB)
Liang Jun, E-mail: liangjunbeijing@yahoo.com.c [Institute of Theoretical Physics, Lanzhou University, Lanzhou 730000 (China); Duan Yishi [Institute of Theoretical Physics, Lanzhou University, Lanzhou 730000 (China)
2009-10-26
We investigate the possibility of localizing various matter fields on the double walls. For spin 0 scalar field, massless zero mode can be normalized on the double walls. However, for spin 1 vector field, the zero mode is not localized on the double walls. In the paper [C.A.S. Almeida, M.M. Ferreira Jr., A.R. Gomes, R. Casana, (arXiv:0901.3543) [hep-th
Mode Combinations and International Operations
DEFF Research Database (Denmark)
Benito, Gabriel R. G.; Petersen, Bent; Welch, Lawrence S.
2011-01-01
reveals that companies tend to combine modes of operation; thereby producing unique foreign operation mode “packages” for given activities and/or countries, and that the packages are liable to be modified over time – providing a potentially important optional path for international expansion. Our data...
Mode Combinations and International Operations
DEFF Research Database (Denmark)
Benito, Gabriel R. G.; Petersen, Bent; Welch, Lawrence S.
2011-01-01
reveals that companies tend to combine modes of operation; thereby producing unique foreign operation mode “packages” for given activities and/or countries, and that the packages are liable to be modified over time—providing a potentially important optional path for international expansion. The data show...
Vibrational Modes of Trumpet Bells
MOORE, T. R.; KAPLON, J. D.; MCDOWALL, G. D.; MARTIN, K. A.
2002-07-01
We report on an investigation of the normal modes of vibration of the bells of several modern trumpets. We describe the results of experiments using electronic speckle-pattern interferometry to visualize the modal structure and we show that the mode frequencies follow a generalized version of Chladni's law.
Transformation and Modes of Production
DEFF Research Database (Denmark)
Høst, Jeppe Engset
2015-01-01
modes of production and examine the ways of life that are enabled by the two modes of production. The central questions are around how market-based fisheries management transforms the principal preconditions for the self-employed fishers; and, in turn, why capitalist organized large-scale fisheries...
Feedback control of subcritical Turing instability with zero mode.
Golovin, A A; Kanevsky, Y; Nepomnyashchy, A A
2009-04-01
A global feedback control of a system that exhibits a subcritical monotonic instability at a nonzero wave number (short-wave or Turing instability) in the presence of a zero mode is investigated using a Ginzburg-Landau equation coupled to an equation for the zero mode. This system is studied analytically and numerically. It is shown that feedback control, based on measuring the maximum of the pattern amplitude over the domain, can stabilize the system and lead to the formation of localized unipulse stationary states or traveling solitary waves. It is found that the unipulse traveling structures result from an instability of the stationary unipulse structures when one of the parameters characterizing the coupling between the periodic pattern and the zero mode exceeds a critical value that is determined by the zero mode damping coefficient.
Single mode quadrature entangled light from room temperature atomic vapour
Wasilewski, W; Jensen, K; Madsen, L S; Krauter, H; Polzik, E S
2009-01-01
We analyse a novel squeezing and entangling mechanism which is due to correlated Stokes and anti-Stokes photon forward scattering in a multi-level atom vapour. Following the proposal we present an experimental demonstration of 3.5 dB pulsed frequency nondegenerate squeezed (quadrature entangled) state of light using room temperature caesium vapour. The source is very robust and requires only a few milliwatts of laser power. The squeezed state is generated in the same spatial mode as the local oscillator and in a single temporal mode. The two entangled modes are separated by twice the Zeeman frequency of the vapour which can be widely tuned. The narrow-band squeezed light generated near an atomic resonance can be directly used for atom-based quantum information protocols. Its single temporal mode characteristics make it a promising resource for quantum information processing.
Single transverse mode selectively oxidized vertical cavity lasers
Energy Technology Data Exchange (ETDEWEB)
CHOQUETTE,KENT D.
2000-04-18
Vertical cavity surface emitting laser (VCSEL) sources have been adopted into Gigabit Ethernet applications in a remarkably short time period. VCSELs are particularly suitable for multimode optical fiber local area networks (LANs), due to their reduced threshold current, circular output beam, and inexpensive and high volume manufacture. Moreover, selectively oxidized VCSELs are nearly ideal LAN sources since the oxide aperture within the laser cavity produces strong electrical and optical confinement which enables high electrical to optical conversion efficiency and minimal modal discrimination allowing emission into multiple transverse optical modes. In addition to the large demand for multimode lasers, VCSELs which emit into a single optical mode are also increasingly sought for emerging applications, which include data communication with single mode optical fiber, bar code scanning, laser printing, optical read/write heads, and modulation spectroscopy. To achieve single mode selectively oxidized VCSELs is a challenging task, since the inherent index confinement within these high performance lasers is very large.
Mode-by-mode hydrodynamics: Ideas and concepts
Energy Technology Data Exchange (ETDEWEB)
Floerchinger, Stefan
2014-06-15
The main ideas, technical concepts and perspectives for a mode resolved description of the hydrodynamical regime of relativistic heavy ion collisions are discussed. A background-fluctuation splitting and a Bessel–Fourier expansion for the fluctuating part of the hydrodynamical fields allows for a complete characterization of initial conditions, the fluid dynamical propagation of single modes, the study of interaction effects between modes, the determination of the associated particle spectra and the generalization of the whole program to event-by-event correlations and probability distributions.
Arkhipov, Ievgen I.; Peřina, Jan; Peřina, Jan; Miranowicz, Adam
2016-07-01
The behavior of general nonclassical two-mode Gaussian states at a beam splitter is investigated. Single-mode nonclassicality as well as two-mode entanglement of both input and output states are analyzed suggesting their suitable quantifiers. These quantifiers are derived from local and global invariants of linear unitary two-mode transformations such that the sum of input (or output) local nonclassicality measures and entanglement measure gives a global invariant. This invariant quantifies the global nonclassicality resource. Mutual transformations of local nonclassicalities and entanglement induced by the beam splitter are analyzed considering incident noisy twin beams, single-mode noisy squeezed vacuum states, and states encompassing both squeezed states and twin beams. A rich tapestry of interesting nonclassical output states is predicted.
Classical impurities and boundary Majorana zero modes in quantum chains
Müller, Markus; Nersesyan, Alexander A.
2016-09-01
We study the response of classical impurities in quantum Ising chains. The Z2 degeneracy they entail renders the existence of two decoupled Majorana modes at zero energy, an exact property of a finite system at arbitrary values of its bulk parameters. We trace the evolution of these modes across the transition from the disordered phase to the ordered one and analyze the concomitant qualitative changes of local magnetic properties of an isolated impurity. In the disordered phase, the two ground states differ only close to the impurity, and they are related by the action of an explicitly constructed quasi-local operator. In this phase the local transverse spin susceptibility follows a Curie law. The critical response of a boundary impurity is logarithmically divergent and maps to the two-channel Kondo problem, while it saturates for critical bulk impurities, as well as in the ordered phase. The results for the Ising chain translate to the related problem of a resonant level coupled to a 1d p-wave superconductor or a Peierls chain, whereby the magnetic order is mapped to topological order. We find that the topological phase always exhibits a continuous impurity response to local fields as a result of the level repulsion of local levels from the boundary Majorana zero mode. In contrast, the disordered phase generically features a discontinuous magnetization or charging response. This difference constitutes a general thermodynamic fingerprint of topological order in phases with a bulk gap.
Scale locality of magnetohydrodynamic turbulence.
Aluie, Hussein; Eyink, Gregory L
2010-02-26
We investigate the scale locality of cascades of conserved invariants at high kinetic and magnetic Reynold's numbers in the "inertial-inductive range" of magnetohydrodynamic (MHD) turbulence, where velocity and magnetic field increments exhibit suitable power-law scaling. We prove that fluxes of total energy and cross helicity-or, equivalently, fluxes of Elsässer energies-are dominated by the contributions of local triads. Flux of magnetic helicity may be dominated by nonlocal triads. The magnetic stretching term may also be dominated by nonlocal triads, but we prove that it can convert energy only between velocity and magnetic modes at comparable scales. We explain the disagreement with numerical studies that have claimed conversion nonlocally between disparate scales. We present supporting data from a 1024{3} simulation of forced MHD turbulence.
Effects of voids on delamination behavior under static and fatigue mode I and mode II
Abdelal, Nisrin Rizek
Composite materials have become materials of choice for wind turbine blade manufacturing due to their high specific stiffness, strength and fatigue life. Glass fiber composites are used extensively in light-weight structural components for wind turbines, aircrafts, marine craft and high performance automobile because glass fiber is inexpensive and usually provides high strength to weight ratio and good in-plane mechanical properties. The high cycle fatigue resistance of composite materials used in wind turbine blades has been recognized as a major uncertainty in predicting the reliability of wind turbines over their design lifetime. Blades are expected to experience 108 to 109 fatigue cycles over a 20 to 30 year lifetime. Delamination or interlaminar failure is a serious failure mode observed in composite structures. Even partial delamination will lead to a loss of local stiffness, which can preclude buckling failure. Manufacturing process defects such as voids and fiber waviness degrade the fatigue life and delamination resistance of the blade's composite. This research describes the effect of voids on static and fatigue interlaminar fracture behavior under mode I and mode II loading of wind turbine glass fiber composites. Samples with different void volume fractions in the 0.5%-7% range were successfully obtained by varying the vacuum in the hand layup vacuum bagging manufacturing process. Void content was characterized using four different methods; ultrasonic scanning, epoxy burn off, serial sectioning and X-Ray computed tomography. The effect of voids on both mode I and mode II interlaminar fracture toughness under static and fatigue loading was investigated. Finally, fractographic analysis (using optical and scanning electron microscopy) was conducted. The results showed that voids leads to slight reduction in static modes I and II interlaminar fracture toughness. In addition, voids lead to a decrease in modes I and II maximum cyclic strain energy release
Geodesic acoustic modes with poloidal mode couplings ad infinitum
Singh, Rameswar; Garbet, X; Hennequin, P; Vermare, L; Morel, P; Singh, R
2015-01-01
Geodesic acoustic modes (GAMs) are studied, for the first time, including all poloidal mode $(m)$ couplings using drift reduced fluid equations. The nearest neighbor coupling pattern, due to geodesic curvature, leads to a semi-infinite chain model of the GAM with the mode-mode coupling matrix elements proportional to the radial wave number $k_{r}$. The infinite chain can be reduced to a renormalized bi-nodal chain with a matrix continued fractions. Convergence study of linear GAM dispersion with respect to $k_{r}$ and the $m$-spectra confirms that high m couplings become increasingly important with $k_{r}$. The radially sorted roots overlap with experimentally measured GAM frequency profile in low collisionality shots in Tore Supra thus explaining the reduced frequency of GAM in Tore Supra.
Mode Competition in Dual-Mode Quantum Dots Semiconductor Microlaser
Chusseau, Laurent; Viktorovitch, P; Letartre, Xavier
2013-01-01
This paper describes the modeling of quantum dots lasers with the aim of assessing the conditions for stable cw dual-mode operation when the mode separation lies in the THz range. Several possible models suited for InAs quantum dots in InP barriers are analytically evaluated, in particular quantum dots electrically coupled through a direct exchange of excitation by the wetting layer or quantum dots optically coupled through the homogeneous broadening of their optical gain. A stable dual-mode regime is shown possible in all cases when quantum dots are used as active layer whereas a gain medium of quantum well or bulk type inevitably leads to bistable behavior. The choice of a quantum dots gain medium perfectly matched the production of dual-mode lasers devoted to THz generation by photomixing.
Novel Propagation Analysis of Coupled Waveguides by Coupled Mode Expansion and Segmentation
Institute of Scientific and Technical Information of China (English)
Tomoyuki; Kato; Yasuo; Kokubun
2003-01-01
To optimize the coupling efficiency between the busline waveguide and the ring resonator in a vertically coupled microring resonator, we developed a new method using local normal modes and the segmentation along the propagation axis.
Few-mode fiber technology for mode division multiplexing
Mori, Takayoshi; Sakamoto, Taiji; Wada, Masaki; Yamamoto, Takashi; Nakajima, Kazuhide
2017-02-01
We review recent progress on few-mode fiber (FMF) technologies for mode-division multiplexing (MDM) transmission. First, we introduce fibers for use without and with multiple-input multiple-output (MIMO) digital signal processing (DSP) to compensate for modal crosstalk, and briefly report recent work on FMF for use without/with a MIMO DSP system. We next discuss in detail a fiber for MIMO transmission systems, and show numerically that a graded-index core can flexibly tune the differential mode group delay (DMD) and a cladding trench can flexibly control the guiding mode number. We optimized the spacing of the core and trench. Accordingly, we can achieve a 6 LP (10 spatial) mode operation and a low DMD while preventing the high index difference that leads to manufacturing difficulties and any loss increase. We finally describe our experimental results for a 6 LP (10 spatial) mode transmission line for use in a C + L band wavelength-division multiplexing (WDM) MDM transmission with MIMO DSP.
Controlling Anderson localization in disordered photonic crystal waveguides
Garcia, P D; Stobbe, S; Lodahl, P
2010-01-01
We prove Anderson localization in a disordered photonic crystal waveguide by measuring the ensemble-averaged localization length which is controlled by the dispersion of the photonic crystal waveguide. In such structures, the localization length shows a 10-fold variation between the fast- and the slow-light regime and, in the latter case, it becomes shorter than the sample length thus giving rise to strongly confined modes. The dispersive behavior of the localization length demonstrates the close relation between Anderson localization and the photon density of states in disordered photonic crystals, which opens a promising route to controlling and exploiting Anderson localization for efficient light confinement.
Calculation, normalization and perturbation of quasinormal modes in coupled cavity-waveguide systems
DEFF Research Database (Denmark)
Kristensen, Philip Trøst; de Lasson, Jakob Rosenkrantz; Gregersen, Niels
2014-01-01
We show how one can use a non-local boundary condition, which is compatible with standard frequency domain methods, for numerical calculation of quasinormal modes in optical cavities coupled to waveguides. In addition, we extend the definition of the quasinormal mode norm by use of the theory of ...
Wrinkling, fracture, and necking: The various failure modes in maritime crash
Atli-Veltin, B.; Dekker, R.; Brunner, S.K.; Walters, C.L.
2016-01-01
Depending on the state of stress, material can fait in a number of different modes during a collision. Three modes are identified here as material separation in the absence of necking, material separation after the onset of necking, and localized buckling/wrinkling. Through a series of case studies,
Local Duality for 2-Dimensional Local Ring
Indian Academy of Sciences (India)
Belgacem Draouil
2008-11-01
We prove a local duality for some schemes associated to a 2-dimensional complete local ring whose residue field is an -dimensional local field in the sense of Kato–Parshin. Our results generalize the Saito works in the case =0 and are applied to study the Bloch–Ogus complex for such rings in various cases.
Wang, Faming; Del Ferraro, Simona; Molinaro, Vincenzo; Morrissey, Matthew; Rossi, René
2014-09-01
Regional sweating patterns and body surface temperature differences exist between genders. Traditional sportswear made from one material and/or one fabric structure has a limited ability to provide athletes sufficient local wear comfort. Body mapping sportswear consists of one piece of multiple knit structure fabric or of different fabric pieces that may provide athletes better wear comfort. In this study, the 'modular' body mapping sportswear was designed and subsequently assessed on a 'Newton' type sweating manikin that operated in both constant temperature mode and thermophysiological model control mode. The performance of the modular body mapping sportswear kit and commercial products were also compared. The results demonstrated that such a modular body mapping sportswear kit can meet multiple wear/thermal comfort requirements in various environmental conditions. All body mapping clothing (BMC) presented limited global thermophysiological benefits for the wearers. Nevertheless, BMC showed evident improvements in adjusting local body heat exchanges and local thermal sensations.
Longitudinally Vibrating Elastic Rods with Locally and Non-Locally Reacting Viscous Dampers
Directory of Open Access Journals (Sweden)
Şefaatdin Yüksel
2005-01-01
Full Text Available Eigencharacteristics of a longitudinally vibrating elastic rod with locally and non-locally reacting damping are analyzed. The rod is considered as a continuous system and complex eigenfrequencies are determined as solution of a characteristic equation. The variation of the damping ratios with respect to damper locations and damping coefficients for the first four eigenfrequencies are obtained. It is shown that at any mode of locally or non-locally damped elastic rod, the variation of damping ratio with damper location is linearly proportional to absolute value of the mode shape of undamped system. It is seen that the increasing damping coefficient does not always increase the damping ratio and there are optimal values for the damping ratio. Optimal values for external damping coefficients of viscous dampers and locations of the dampers are presented.
Multiple relaxation modes in associative polymer networks with varying connectivity
Bohdan, M.; Sprakel, J.; van der Gucht, J.
2016-09-01
The dynamics and mechanics of networks depend sensitively on their spatial connectivity. To explore the effect of connectivity on local network dynamics, we prepare transient polymer networks in which we systematically cut connecting bonds. We do this by creating networks formed from hydrophobically modified difunctionalized polyethylene glycol chains. These form physical gels, consisting of flowerlike micelles that are transiently cross-linked by connecting bridges. By introducing monofunctionalized chains, we can systematically reduce the number of bonds between micelles and thus lower the network connectivity, which strongly reduces the network elasticity and relaxation time. Dynamic light scattering reveals a complex relaxation dynamics that are not apparent in bulk rheology. We observe three distinct relaxation modes. First we find a fast diffusive mode that does not depend on the number of bridges and is attributed to the diffusion of micelles within a cage formed by neighboring micelles. A second, intermediate mode depends strongly on network connectivity but surprisingly is independent of the scattering vector q . We attribute this viscoelastic mode to fluctuations in local connectivity of the network. The third, slowest mode is also diffusive and is attributed to the diffusion of micelle clusters through the viscoelastic matrix. These results shed light on the microscopic dynamics in weakly interconnected transient networks.
Local Limit Phenomena, Flow Compression, and Fuel Cracking Effects in High-Speed Turbulent Flames
2015-06-01
dynamic adaptive hybrid integration, was developed for stiff chemistry. 15. SUBJECT TERMS chemical explosive mode analysis ( CEMA ...TECHNICAL DISCUSSION 1. Chemical explosive mode analysis ( CEMA ) for computational flame diagnostics The method of chemical explosive mode...analysis ( CEMA ) is a systematic approach to identify limit flame phenomena, including local ignition, extinction, and premixed and non- premixed reaction
Optical surface modes in the presence of nonlinearity and disorder
Molina, M I; Tsironis, G P
2011-01-01
We investigate numerically the effect of the competition of disorder, nonlinearity, and boundaries on the Anderson localization of light waves in finite-size, one-dimensional waveguide arrays. Using the discrete Anderson - nonlinear Schr\\"odinger equation, the propagation of the mode amplitudes up to some finite distance is monitored. The analysis is based on the calculated localization length and the participation number, two standard measures for the statistical description of Anderson localization. For relatively weak disorder and nonlinearity, a higher disorder strength is required to achieve the same degree of localization at the edge than in the interior of the array, in agreement with recent experimental observations in the linear regime. However, for relatively strong disorder and/or nonlinearity, this behavior is reversed and it is now easier to localize an excitation at the edge than in the interior.
Directory of Open Access Journals (Sweden)
Wu C.Y.
2012-02-01
Full Text Available Spectra of γ rays following neutron capture at isolated resonances of 6 stable Gd isotopes were measured with highly segmented BaF2 detector DANCE at the Los Alamos LANSCE spallation neutron source. The main emphasis was put on studying the γ-cascade decay of neutron resonances to get unique information on photon strength. An analysis of the accumulated γ-ray spectra within the extreme statistical model leads to an inescapable conclusion that scissors mode resonances are built not only on the ground-state, but also on excited levels in all product nuclei studied. The results on summed B(M1↑ strength and energy of the scissors mode are compared with systematics of scissors mode parameters for the ground-state transitions deduced from nuclear resonance fluorescence measurements. A specific feature of our experiments is the investigation of scissors mode of odd nuclei, for which the nuclear resonance fluorescence provides only limited information.
Kroll, J.; Baramsai, B.; Becker, J. A.; Bečvář, F.; Bredeweg, T. A.; Couture, A.; Chyzh, A.; Dashdorj, D.; Haight, R. C.; Jandel, M.; Krtička, M.; Mitchell, G. E.; O'Donnell, J. M.; Parker, W.; Rundberg, R. S.; Ullmann, J. L.; Vieira, G. J.; Walker, C. L.; Wilhelmy, J. B.; Wouters, J. M.; Wu, C. Y.
2012-02-01
Spectra of γ rays following neutron capture at isolated resonances of 6 stable Gd isotopes were measured with highly segmented BaF2 detector DANCE at the Los Alamos LANSCE spallation neutron source. The main emphasis was put on studying the γ-cascade decay of neutron resonances to get unique information on photon strength. An analysis of the accumulated γ-ray spectra within the extreme statistical model leads to an inescapable conclusion that scissors mode resonances are built not only on the ground-state, but also on excited levels in all product nuclei studied. The results on summed B(M1)↑ strength and energy of the scissors mode are compared with systematics of scissors mode parameters for the ground-state transitions deduced from nuclear resonance fluorescence measurements. A specific feature of our experiments is the investigation of scissors mode of odd nuclei, for which the nuclear resonance fluorescence provides only limited information.