BXO mode-converted electron Bernstein emission diagnostic (invited)
Volpe, F.; Laqua, H. P.
2003-03-01
Electron temperature profiles at densities above the electron cyclotron emission (ECE) cutoff are measured at the W7-AS stellarator by a novel diagnostic based on black body emission and Bernstein-extraordinary-ordinary mode conversion of electron Bernstein waves (EBWs). The radiation is collected along a special oblique line of sight by an antenna with gaussian optics. This was optimized for maximal conversion efficiency and minimal Doppler broadening by means of EBW ray tracing calculations in full stellarator geometry. The elliptical O-mode polarization detected along the oblique line of sight is changed into a linear polarization by a broadband quarter wave shifter, namely an elliptical waveguide. The signal is spectrum analyzed by an heterodyne radiometer and temperature profiles are derived from spectra by means of ray tracing. The diagnostic was applied to measurements of edge-localized modes to illustrate its advantages in terms of spatial and temporal resolution. Moreover, for the first time, the heat wave propagation method for the determination of local heat transport coefficients was extended beyond the ECE cutoff density by combining EBW emission measurements at the first harmonic (f=66-78 GHz) with modulated EBW heating at the second harmonic (140 GHz).
Electron Bernstein Wave Emission and Mode Conversion Physics on NSTX
Energy Technology Data Exchange (ETDEWEB)
Diem, S J; Caughman, J B; Efthimion, P; Kugel, H; LeBlanc, B P; Preinhaelter, J; Sabbagh, S A; Urban, J
2008-05-21
NSTX is a spherical tokamak (ST) that operates with ne up to 1020 m-3 and BT less than 0.6 T, cutting off low harmonic electron cyclotron (EC) emission widely used for Te measurements on conventional aspect ratio tokamaks. The electron Bernstein wave (EBW) can propagate in ST plasmas and is emitted at EC harmonics. These properties suggest thermal EBW emission (EBE) may be used for local Te measurements in the ST. Practically, a robust Te(R,t) EBE diagnostic requires EBW transmission efficiencies of > 90% for a wide range of plasma conditions. EBW emission and coupling physics were studied on NSTX with an obliquely viewing EBW to O-mode (B-X-O) diagnostic with two remotely steered antennas, coupled to absolutely calibrated radiometers. While Te(R,t) measurements with EBW emission on NSTX were possible, they were challenged by several issues. Rapid fluctuations in edge ne scale length resulted in > 20% changes in the low harmonic B-X-O transmission efficiency. Also, B-X-O transmission efficiency 2 during H-modes was observed to decay by a factor of 5-10 to less than a few percent. The B-X-O transmission behavior during H-modes was reproduced by EBE simulations that predict that EBW collisional damping can significantly reduce emission when Te < 30 eV inside the B-X-O mode conversion (MC) layer. Initial edge lithium conditioning experiments during H-modes have shown that evaporated lithium can increase Te inside the B-X-O MC layer, significantly increasing B-X-O transmission.
Plasma heating via electron Bernstein wave heating using ordinary and extraodinary mode
Directory of Open Access Journals (Sweden)
A. Parvazian
2008-03-01
Full Text Available Magnetically confined plasma can be heated with high power microwave sources. In spherical torus the electron plasma frequency exeeds the electron cyclotron frequency (EC and, as a consequence, electromagnetic waves at fundamental and low harmonic EC cannot propagate within the plasma. In contrast, electron Bernstein waves (EBWs readily propagate in spherical torus plasma and are absorbed strongly at the electron cyclotron resonances. In order to proagate EBWs beyond the upper hybrid resonance (UHR, that surrounds the plasma, the EBWs must convert via one of two processes to either ordinary (O-mode or extraordinary (X-mode electromagnetic waves. O-mode and X-mode electromagnetic waves lunched at the plasma edge can convert to the electron Bernstein waves (EBWs which can propagate without and cut-off into the core of the plasma and damp on electrons. Since the electron Bernstein wave (EBW has no cut-off limits, it is well suited to heat an over-dense plasma by resonant absorption. An important problem is to calculate mode conversion coefficient that is very sensitive to density. Mode conversion coefficient depends on Budden parameter ( ñ and density scale length (Ln in upper hybrid resonance (UHR. In Mega Ampere Spherical Tokamak (MAST, the optimized conversion efficiency approached 72.5% when Ln was 4.94 cm and the magnetic field was 0.475 Tesla in the core of the plasma.
Oblique Bernstein Mode Generation Near the Upper-hybrid Frequency in Solar Pre-flare Plasmas
Kryshtal, A.; Fedun, V.; Gerasimenko, S.; Voitsekhovska, A.
2015-11-01
We study analytically the generation process of the first harmonics of the pure electron weakly oblique Bernstein modes. This mode can appear as a result of the rise and development of a corresponding instability in a solar active region. We assume that this wave mode is modified by the influence of pair Coulomb collisions and a weak large-scale sub-Dreicer electric field in the pre-flare chromosphere near the footpoints of a flare loop. To describe the pre-flare plasma we used the model of the solar atmosphere developed by Fontenla, Avrett, and Loeser ( Astrophys. J. 406, 319, 1993). We show that the generated first harmonic is close to the upper-hybrid frequency. This generation process begins at the very low threshold values of the sub-Dreicer electric field and well before the beginning of the preheating phase of a flare. We investigate the necessary conditions for the existence of non-damped first harmonics of oblique Bernstein waves with small amplitudes in the flare area.
Walsh, Daniel K.; Dubin, Daniel H. E.
2015-11-01
This poster presents theory and numerical calculations of electrostatic Bernstein modes in an inhomogeneous cylindrical plasma column. These modes rely on FLR effects to propagate radially across the column until they are reflected when their frequency matches the local upper hybrid frequency, setting up an internal normal mode on the column, and also mode-coupling to the electrostatic surface cyclotron wave (which allows the normal mode to be excited and observed using external electrodes). Numerical results predicting the mode spectra, using a novel linear Vlasov code on a cylindrical grid, will be presented and compared to an analytic WKB theory. A previous version of the theory expanded the plasma response in powers of 1/B, approximating the local upper hybrid frequency, and consequently its frequency predictions are shifted with respect to the numerical results. A new version of the WKB theory uses the exact cold fluid plasma response and does a better job of reproducing the numerical frequency spectrum. The eventual goal is to compare the theory to recent experiments that have observed these waves in pure electron and pure ion plasmas. Supported by National Science Foundation Grant PHY-1414570.
Xiao, Jianyuan; Qin, Hong; Yu, Zhi; Xiang, Nong
2015-01-01
In this paper, the nonlinear mode conversion of extraordinary waves in nonuniform magnetized plasmas is studied using the variational symplectic particle-in-cell simulation. The accuracy of the nonlinear simulation is guaranteed by the long-term accuracy and conservativeness of the symplectic algorithm. The spectra of the electromagnetic wave, the evolution of the wave reflectivity, the energy deposition profile, and the parameter-dependent properties of radio-frequency waves during the nonlinear mode conversion are investigated. It is illustrated that nonlinear effects significantly modify the physics of the radio-frequency injection in magnetized plasmas. The evolutions of the radio-frequency wave reflectivity and the energy deposition are observed, as well as the self-interaction of the Bernstein waves and mode excitations. Even for waves with small magnitude, nonlinear effects can also become important after continuous wave injections, which are common in the realistic radio-frequency wave heating and cur...
Axisymmetric Bernstein modes in a finite-length non-neutral plasma: simulation and kinetic theory
Hart, Grant; Peterson, Bryan G.; Spencer, Ross L.
2016-10-01
We are using a 2-D PIC code to model high-frequency (near the cyclotron frequency) axisymmetric oscillations in a finite-length pure-ion plasma. We previously modeled these modes for infinite-length plasmas, where they are not detectable in the surface charge on the walls because of axisymmetry and lack of z-dependence. This is not true in a finite-length plasma, however, because the eigenfunction of the oscillation has to have nodes a short distance beyond the ends of the plasma. This gives the modes a cos (kz z) or sin (kz z) dependence, with a kz such that an integral number (approximately) of half-wavelengths fit into the plasma. This z-dependence makes the mode detectable in the surface charge on the walls. The modes also have r-dependence. The radial-velocity eigenfunctions of the modes behave as J1 (kr r) . We have simulated the plasma with different kz and kr values and find that increasing kz introduces a small frequency shift, either upward or downward depending on which mode is measured. The damping of the modes also increases as kz or kr increases. We are developing an appropriate kinetic theory of these modes that will include both the finite-Larmour-radius effects and the axial bouncing motion of the particles.
Abbasi, Mustafa; Sadeghi, Yahya; Sobhanian, Samad; Asgarian, Mohammad Ali
2016-03-01
The electron Bernstein wave (EBW) is typically the only wave in the electron cyclotron (EC) range that can be applied in spherical tokamaks for heating and current drive (H&CD). Spherical tokamaks (STs) operate generally in high- β regimes, in which the usual EC ordinary (O) and extraordinary (X) modes are cut off. As it was recently investigated the existence of EBWs at nonlinear regime thus the next step would be the probable nonlinear phenomena study which are predicted to be occurred within the high levels of injected power. In this regard, parametric instabilities are considered as the major channels for losses at the X-B conversion. Hence, we have to consider their effects at the UHR region which can reduce the X-B conversion efficiency. In the case of EBW heating (EBH) at high power density, the nonlinear effects can arise. Particularly at the UHR position, the group velocity is strongly reduced, which creates a high energy density and subsequently a high amplitude electric field. Therefore, a part of the input wave can decay into daughter waves via parametric instability (PI). Thus, via the present research, the excitations of ion Bernstein waves as the dominant decay channels are investigated and also an estimate for the threshold power in terms of experimental parameters related to the fundamental mode of instability is proposed.
Stefan, V. Alexander
2014-10-01
A novel method for alpha particle diagnostics is proposed. The theory of stimulated Raman scattering, SRS, of the fast wave and ion Bernstein mode, IBM, turbulence in multi-ion species plasmas, (Stefan University Press, La Jolla, CA, 2008). is utilized for the diagnostics of fast ions, (4)He (+2), in ITER plasmas. Nonlinear Landau damping of the IBM on fast ions near the plasma edge leads to the space-time changes in the turbulence level, (inverse alpha particle channeling). The space-time monitoring of the IBM turbulence via the SRS techniques may prove efficient for the real time study of the fast ion velocity distribution function, spatial distribution, and transport. Supported by Nikola Tesla Labs., La Jolla, CA 92037.
Energy Technology Data Exchange (ETDEWEB)
Igami, H.; Shimozuma, T.; Yoshimura, Y.; Takahashi, H.; Nishiura, M.; Seki, T.; Osakabe, M.; Mutoh, T. [National Institute for Fusion Science, Toki (Japan); Kubo, S. [National Institute for Fusion Science, Toki, Japan and Department of Energy Engineering and Science, Nagoya Univ., Nagoya (Japan); Ogasawara, S.; Makino, R. [Department of Energy Engineering and Science, Nagoya Univ., Nagoya (Japan); Idei, H. [Research Institute for Applied Mechanics, Kyusyu Univ., Kasuga (Japan); Nagasaki, K. [Institute of Advanced Energy, Kyoto Univ., Uji (Japan)
2014-02-12
In the large helical device (LHD), the theoretically predicted width of the ordinary-extraordinary-electron Bernstein wave (O-X-B) mode conversion (MC) window is comparable to the beam width and the power deposition is located in the off-axis region if the 77GHz fundamental electron cyclotron (EC) wave of is launched from an existing horizontal port antenna. In the experiment, the actual MC window location was looked for with changing the aiming. The effective aiming with that the increase of the stored energy was observed was two degrees apart from the location of the theoretical MC window at a maximum. Measurement of the waves originated from the thermally emitted EBW and radiated via the B-X-O mode conversion process is effective to improve the accuracy of the theoretical prediction with comparison between the theoretical and the experimental results. The theoretical prediction suggests that the width of the MC window of the fundamental 77GHz EC wave can be expanded if the lower port antenna is used. On the other hand, the MC window of the second harmonic 154GHz EC wave is blocked by horizontal port wall if another horizontal port antenna is used. It is required to move the final mirror of the quasi-optical antenna toward the plasma surface. Focusing of the beam at the plasma cutoff is (PC) also necessary for the effective mode conversion.
Sun, Jicheng; Gao, Xinliang; Chen, Lunjin; Lu, Quanming; Tao, Xin; Wang, Shui
2016-02-01
Ion Bernstein modes, also known as magnetosonic waves in the magnetospheric community, are considered to play an important role in radiation belt electron acceleration. The detailed properties of perpendicular magnetosonic waves excited in the inner magnetosphere by a tenuous proton ring distribution are investigated in a two series paper with a combination of the linear theory and one-dimensional particle-in-cell simulations. Here, in this paper, we study the properties of the excited magnetosonic waves under different plasma conditions with the linear theory. When the proton to electron mass ratio or the ratio of the light speed to the Alfven speed is small, the excited magnetosonic waves are prone to having a discrete spectrum with only several wave modes. With the increase of the proton to electron mass ratio or the ratio of the light speed to the Alfven speed, the lower hybrid frequency also increases, which leads to the increase of both the number and frequency of the excited wave modes. Meanwhile, the growth rate of these wave modes also increases. When the proton to electron mass ratio or the ratio of the light speed to the Alfven speed is sufficiently large, the spectrum of the excited magnetic waves becomes continuous due to the overlapping of the adjacent wave modes. The increase of the density of the protons with the ring distribution can also result in the increase of the growth rate, which may also change the discrete spectrum of the excited waves to a continuous one, while the increase of the ring velocity of the tenuous proton ring distribution leads to a broader spectrum, but with a smaller growth rate.
Weakly relativistic dispersion of Bernstein waves
Robinson, P. A.
1988-01-01
Weakly relativistic effects on the dispersion of Bernstein waves are investigated for waves propagating nearly perpendicular to a uniform magnetic field in a Maxwellian plasma. Attention is focused on those large-wave-vector branches that are either weakly damped or join continuously onto weakly damped branches since these are the modes of most interest in applications. The transition between dispersion at perpendicular and oblique propagation is examined and major weakly relativistic effects can dominate even in low-temperature plasmas. A number of simple analytic criteria are obtained which delimit the ranges of harmonic number and propagation angle within which various types of weakly damped Bernstein modes can exist.
Pedagogic Governance: Theorising with/after Bernstein
Singh, Parlo
2017-01-01
Researchers interested in new modes of social control and regulation through pedagogic means have increasingly drawn on Bernstein's theories of social control through pedagogic means and the emergence of a totally pedagogised society. This article explores this aspect of the Bernsteinian theoretical project by extrapolating and contrasting…
Ion Bernstein wave heating research
Energy Technology Data Exchange (ETDEWEB)
Ono, Masayuki.
1992-03-01
Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW's low phase velocity ({omega}/k{sub {perpendicular}} {approx} V{sub Ti} {much lt} V{sub {alpha}}) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion {alpha}-particles. In addition, the property of IBW's that k{sub {perpendicular}} {rho}{sub i} {approx} 1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW's can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. This paper discusses this research.
Ion Bernstein wave heating research
Energy Technology Data Exchange (ETDEWEB)
Ono, Masayuki
1992-03-01
Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW`s low phase velocity ({omega}/k{sub {perpendicular}} {approx} V{sub Ti} {much_lt} V{sub {alpha}}) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion {alpha}-particles. In addition, the property of IBW`s that k{sub {perpendicular}} {rho}{sub i} {approx} 1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW`s can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. This paper discusses this research.
Bernstein-type approximations of smooth functions
Directory of Open Access Journals (Sweden)
Andrea Pallini
2007-10-01
Full Text Available The Bernstein-type approximation for smooth functions is proposed and studied. We propose the Bernstein-type approximation with definitions that directly apply the binomial distribution and the multivariate binomial distribution. The Bernstein-type approximations generalize the corresponding Bernstein polynomials, by considering definitions that depend on a convenient approximation coefficient in linear kernels. In the Bernstein-type approximations, we study the uniform convergence and the degree of approximation. The Bernstein-type estimators of smooth functions of population means are also proposed and studied.
Electron Bernstein waves emission in the TJ-II stellarator
Energy Technology Data Exchange (ETDEWEB)
Garcia-Regana, J M; Cappa, A; Castejon, F; Ros, A [Laboratorio Nacional de Fusion, CIEMAT, 28040, Madrid (Spain); Caughman, J B O; Rasmussen, D A; Wilgen, J B [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Tereshchenko, M, E-mail: josemanuel.garcia@ciemat.es [Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
2011-06-15
Taking advantage of the electron Bernstein waves heating system of the TJ-II stellarator, an electron Bernstein emission (EBE) diagnostic was installed. Its purpose is to investigate the B-X-O radiation properties in the zone where optimum theoretical electron Bernstein wave (EBW) coupling is predicted. An internal movable mirror shared by both systems allows us to collect the EBE radiation along the same line of sight that is used for EBW heating. The theoretical EBE has been calculated for different orientations of the internal mirror using the TRUBA code as the ray tracer. A comparison with experimental data obtained in NBI discharges is carried out. The results provide valuable information regarding the experimental O-X-mode conversion window expected in the EBW heating experiments. Furthermore, the characterization of the radiation polarization shows evidence of the underlying B-X-O conversion process.
Bernstein wave aided laser third harmonic generation in a plasma
Tyagi, Yachna; Tripathi, Deepak; Kumar, Ashok
2016-09-01
The process of Bernstein wave aided resonant third harmonic generation of laser in a magnetized plasma is investigated. The extra-ordinary mode (X-mode) laser of frequency ω 0 and wave number k → 0 , travelling across the magnetic field in a plasma, exerts a second harmonic ponderomotive force on the electrons imparting them an oscillatory velocity v → 2 ω0 , 2 k → 0 . This velocity beats with the density perturbation due to the Bernstein wave to produce a density perturbation at cyclotron frequency shifted second harmonic. The density perturbation couples with the oscillatory velocity v → ω0 , k → 0 of X-mode of the laser to produce the cyclotron frequency shifted third harmonic current density leading to harmonic radiation. The phase matching condition for the up shifted frequency is satisfied when the Bernstein wave is nearly counter-propagating to the laser. As the transverse wave number of the Bernstein wave is large, it is effective in the phase matched third harmonic generation, when the laser frequency is not too far from the upper hybrid frequency.
Sun, Jicheng; Gao, Xinliang; Lu, Quanming; Chen, Lunjin; Tao, Xin; Wang, Shui
2016-02-01
In this paper, we perform one-dimensional particle-in-cell simulations to investigate the properties of perpendicular magnetosonic waves in a plasma system consisting of three components: cool electrons, cool protons, and tenuous ring distribution protons, where the waves are excited by the tenuous proton ring distribution. Consistent with the linear theory, the spectra of excited magnetosonic waves can change from discrete to continuous due to the overlapping of adjacent unstable wave modes. The increase of the proton to electron mass ratio, the ratio of the light speed to the Alfven speed, or the concentration of protons with a ring distribution tends to result in a continuous spectrum of magnetosonic waves, while the increase of the ring velocity of the tenuous proton ring distribution leads to a broader one, but with a discrete structure. Moreover, the energization of both cool electrons and protons and the scattering of ring distribution protons due to the excited magnetosonic waves are also observed in our simulations, which cannot be predicted by the linear theory. Besides, a thermalized proton ring distribution may lead to the further excitation of several lower discrete harmonics with their frequencies about several proton gyrofrequencies.
Re-Reading and Rehabilitating Basil Bernstein
Bolander, Brook; Watts, Richard J.
2009-01-01
This article constitutes a re-reading of and an attempt to rehabilitate Basil Bernstein, both of which are important in light of the interpretation of Bernstein as a proponent of the verbal deficit view, and the general discrediting of his work on social class differences in the British educational system, as related to what he later called…
AN APPLICATION OF BERNSTEIN-DURRMEYER OPERATORS
Institute of Scientific and Technical Information of China (English)
Baohuai Sheng; Chunping Zhang
2007-01-01
In the present paper, we find that the Bernstein-Durrmeyer operators, besides their better applications in approximation theory and some other fields, are good tools Bernstein-Durrmeyer operators a sequence of translation network operators is constructed and its degree of approximation is dealt.
Bernstein, Educational Change, and Gendered Language
Cook-Gumperz, Jenny
2009-01-01
This paper focuses on a little known Bernstein concept of "gender codes" developed in the study of schooling, suggesting that schools transmit hidden gender messages though a range of semiotic devices. Initially, the paper shows how Bernstein's 1970s' research provided a novel way of looking at some critical issues current in educational…
Electron Bernstein waves emission in the TJ--II Stellarator
García-Regaña, J M; Castejón, F; Caughman, J B O; Tereshchenko, M; Ros, A; Rasmussen, D A; Wilgen, J B
2010-01-01
Taking advantage of the electron Bernstein waves heating (EBWH) system of the TJ--II stellarator, an electron Bernstein emission (EBE) diagnostic was installed. Its purpose is to investigate the B--X--O radiation properties in the zone where optimum theoretical EBW coupling is predicted. An internal movable mirror shared by both systems allows us to collect the EBE radiation along the same line of sight that is used for EBW heating. The theoretical EBE has been calculated for different orientations of the internal mirror using the TRUBA code as ray tracer. A comparison with experimental data obtained in NBI discharges is carried out. The results provide a valuable information regarding the experimental O--X mode conversion window expected in the EBW heating experiments. Furthermore, the characterization of the radiation polarization shows evidence of the underlying B--X--O conversion process.
Basil Bernstein: Agency, Structure and Linguistic Conception of Class
Best, Shaun
2007-01-01
The paper outlines an interpretation of Bernstein's contribution to the sociology of education that stands in contrast to the common interpretations of Bernstein's work. It is commonly assumed that Bernstein constructed a simplistic "deficit model" of educational failure, or alternatively, that Bernstein was a structuralist who did not give any…
A note on Bernstein-Jordan Algebras(2)
Miyamoto, Kohei
2003-01-01
As a contribution of the problem of classifying all Bernstein algebras, we attempt to describe the posibility of u-part decomposition of Bernstein-Jordan algebras in terms of the direct product of Bernstein algebras and study some conditions for a Bernstein-Jordan algebra to be u-part decomposable.
Bernstein: Prelude, Fugue and Riffs / Michel Parouty
Parouty, Michel
1998-01-01
Uuest heliplaadist "Bernstein: Prelude, Fugue and Riffs. Facsimile. West Side Story - Symphonic Dances. Divertimento. City of Birmingham Symphony Orchestra / Paavo Järvi" Virgin Classics VC5 45295-2 (68 minutes:DDD)
Bernstein: Prelude, Fugue and Riffs / Edward Greenfield
Greenfield, Edward
1998-01-01
Uuest heliplaadist "Bernstein: Prelude, Fugue and Riffs. Facsimile. West Side Story - Symphonic Dances. Divertimento. City of Birmingham Symphony Orchestra / Paavo Järvi. Virgin Classics VC5 45295-2 (68 minutes:DDD)
Observations of Obliquely Propagating Electron Bernstein Waves
DEFF Research Database (Denmark)
Armstrong, R. J.; Juul Rasmussen, Jens; Stenzel, R. L.;
1981-01-01
Plane electron Bernstein waves propagating obliquely to the magnetic field are investigated. The waves are excited by a plane grid antenna in a large volume magnetoplasma. The observations compare favorably with the predictions of the linear dispersion relation.......Plane electron Bernstein waves propagating obliquely to the magnetic field are investigated. The waves are excited by a plane grid antenna in a large volume magnetoplasma. The observations compare favorably with the predictions of the linear dispersion relation....
Transfinite diameter of Bernstein sets in
Directory of Open Access Journals (Sweden)
Bialas-Cież Leokadia
2002-01-01
Full Text Available Let be a compact set in satisfying the following generalized Bernstein inequality: for each such that , for each polynomial of degree where is a constant independent of and , is an infinite set of natural numbers that is also independent of and . We give an estimate for the transfinite diameter of the set : For satisfying the usual Bernstein inequality (i.e., , we prove that
Electron Bernstein Wave Studies in MST
Seltzman, Andrew; Anderson, Jay; Forest, Cary; Nonn, Paul; Thomas, Mark; Almagri, Abdulgader; Chapman, Brett; Dubois, Ami; Goetz, John; McCollam, Karsten
2015-11-01
The RFP plasma is inaccessible to ECRH, requiring the electron Bernstein wave (EBW) for edge localized heating and current drive. MST is capable of generating RFPs or overdense tokamaks with Bt(0) ~ 0.08-0.14T in which a 5.55 GHz RF source (450kW, 2ms pulse) can heat at fundamental and harmonic EC resonances. The design of a suitable antenna is challenging in the RFP due to a magnetic field geometry that requires a low-field-side launch. The small vacuum gap between the close-fitting conducting shell and plasma leads to substantial antenna-plasma interaction. A minimized port hole size is required to limit error fields. Even so the port hole induced magnetic field perturbation in the antenna near-field that affects the mode conversion process and introduces EC resonances. A 5cm diameter cylindrical antenna centered in 5cm and 11cm diameter portholes is used. A multi-chord time-resolved x-ray detector and GENRAY ray tracing verifies EBW heating at higher harmonics in an MST tokamak with 10-40keV detected x-ray energies. Evidence of RF-induced emission from absorption at higher harmonics (4th / 5th) in low current RFP discharges has been observed. Simultaneous reflected power changes correspond to termination of x-ray emission indicating power limits. Work supported by USDOE.
Derivatives of Multivariate Bernstein Operators and Smoothness with Jacobi Weights
Directory of Open Access Journals (Sweden)
Jianjun Wang
2012-01-01
Full Text Available Using the modulus of smoothness, directional derivatives of multivariate Bernstein operators with weights are characterized. The obtained results partly generalize the corresponding ones for multivariate Bernstein operators without weights.
Numerical and Analytical Calculation of Bernstein Resonances in a Non-Uniform Cylindrical Plasma
Walsh, D. K.; Dubin, D. H. E.
2016-10-01
This poster presents theory and numerical predictions of electrostatic Bernstein modes in a cylindrical non-neutral plasma column with multiple ion species. These modes propagate radially across the column until they are reflected when their frequency matches the local upper hybrid frequency, setting up an internal normal mode on the column, and also mode-coupling to the electrostatic surface cyclotron wave (which allows the normal mode to be excited and observed using external electrodes). Using our linear Vlasov code discussed last year, we present several numerical results at various magnetic fields, eilθ-dependencies, and plasma profiles in order to make quantitative predictions of future cyclotron wave experiments. These results are compared to the semi-analytic WKB theory in order to determine under what conditions Bernstein waves are measurable at the wall. Supported by NSF Grant PHY-1414570, and DOE Grants DE-SC0002451.
On the Relevance of Bernstein for German-Speaking Switzerland
Bolander, Brook
2009-01-01
This article assesses the relevance of Basil Bernstein for German-speaking Switzerland. It argues that Bernstein is potentially relevant for German-speaking Switzerland in light of contemporary studies which highlight a connection between social background and differential school achievement. After contextualising Bernstein's theoretical outlook…
Min, Kyungguk; Liu, Kaijun
2016-04-01
Fast magnetosonic waves in Earth's inner magnetosphere, which have as their source ion Bernstein instabilities, are driven by hot proton velocity distributions (fp) with ∂fp(v⊥)/∂v⊥>0. Two typical types of distributions with such features are ring and shell velocity distributions. Both have been used in studies of ion Bernstein instabilities and fast magnetosonic waves, but the differences between instabilities driven by the two types of distributions have not been thoroughly addressed. The present study uses linear kinetic theory to examine and understand these differences. It is found that the growth rate pattern is primarily determined by the cyclotron resonance condition and the structure of the velocity distribution in gyroaveraged velocity space. For ring-driven Bernstein instabilities, as the parallel wave number (k∥) increases, the discrete unstable modes approximately follow the corresponding proton cyclotron harmonic frequencies while they become broader in frequency space. At sufficiently large k∥, the neighboring discrete modes merge into a continuum. In contrast, for shell-driven Bernstein instabilities, the curved geometry of the shell velocity distribution in gyroaveraged velocity space results in a complex alternating pattern of growth and damping rates in frequency and wave number space and confines the unstable Bernstein modes to relatively small k∥. In addition, when k∥ increases, the unstable modes are no longer limited to the proton cyclotron harmonic frequencies. The local growth rate peak near an exact harmonic at small k∥ bifurcates into two local peaks on both sides of the harmonic when k∥ becomes large.
CONVERGENCE ARTE FOR INTERATES OF q-BERNSTEIN POLYNOMIALS
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Recently, q-Bernstein polynomials have been intensively investigated by a number of authors. Their results show that for q ≠ 1, q-Bernstein polynomials possess of many interesting properties. In this paper, the convergence rate for iterates of both q-Bernstein when n →∞ and convergence rate of Bn(f,q;x) when f ∈ Cn-1[0, 1], q →∞ are also presented.
Grace, Gerald
2008-01-01
Using the concepts of classification and framing and other relevant writings by Basil Bernstein, an attempt will be made to construct a theorised account of changes in the socio-political context of education in Britain; of the mode of governance in education and of the constructs and practice of educational leadership from the 1950s to the…
Bernstein's "Codes" and the Linguistics of "Deficit"
Jones, Peter E.
2013-01-01
This paper examines the key linguistic arguments underpinning Basil Bernstein's theory of "elaborated" and "restricted" "codes". Building on a review of selected highlights from the collective critical response to Bernstein, the paper attempts to clarify the relationship of the theory to "deficit" views…
EQUIVALENT THEOREMS ON SIMULTANEOUS APPROXIMATION BY COMBINATIONS OF BERNSTEIN OPERATORES
Institute of Scientific and Technical Information of China (English)
Li Cheng; Linsen Xie
2006-01-01
In this paper we give equivalent theorems on simultaneous approximation for the combinations of Bernstein operators by r-th Ditzian-Totik modulus of smoothness ωτψλ (f, t)(0 ≤λ≤ 1). We also investigate the relation between the derivatives of the combinations of Bernstein operators and the smoothness of derivatives of functions.
Patriotism, Peace and Poverty : Reply to Bernstein and Varden
Kleingeld, Pauline
2014-01-01
In this essay I reply to Alyssa Bernstein and Helga Varden’s comments on my book, Kant and Cosmopolitanism. In response to Bernstein, I argue that Kant’s opposition to the coercive incorporation of states into an international federation should be interpreted as permitting no exceptions. In response
Numerical solution of stochastic SIR model by Bernstein polynomials
Directory of Open Access Journals (Sweden)
N. Rahmani
2016-01-01
Full Text Available In this paper, we present numerical method based on Bernstein polynomials for solving the stochastic SIR model. By use of Bernstein operational matrix and its stochastic operational matrix we convert stochastic SIR model to a nonlinear system that can be solved by Newton method. Finally, a test problem of SIR model is presented to illustrate our mathematical findings.
Derivatives of Bernstein- Kantorovich Operators and Smoothness%Bernstein-Kantorovich算子导数与光滑性
Institute of Scientific and Technical Information of China (English)
蒋红标
2003-01-01
借助于r-阶古典光滑模ωr(f,t),研究了Bernstein-Kantorovich算子导数与它所逼近函数光滑性之间的关系,得到了Bernstein-Kantorovich算子导数与r-阶古典光滑模ωr(f,t)的等价定理.
Simplified Storm Surge Simulations Using Bernstein Polynomials
Beisiegel, Nicole; Behrens, Jörn
2016-04-01
Storm surge simulations are vital for forecasting, hazard assessment and eventually improving our understanding of Earth system processes. Discontinuous Galerkin (DG) methods have recently been explored in that context, because they are locally mass-conservative and in combination with suitable robust nodal filtering techniques (slope limiters) positivity-preserving and well-balanced for the still water state at rest. These filters manipulate interpolation point values in every time step in order to retain the desirable properties of the scheme. In particular, DG methods are able to represent prognostic variables such as the fluid height at high-order accuracy inside each element (triangle). For simulations that include wetting and drying, however, the high-order accuracy will destabilize the numerical model because point values on quadrature points may become negative during the computation if they do not coincide with interpolation points. This is why the model that we are presenting utilizes Bernstein polynomials as basis functions to model the wetting and drying. This has the advantage that negative pointvalues away from interpolation points are prevented, the model is stabilized and no additional time step restriction is introduced. Numerical tests show that the model is capable of simulating simplified storm surges. Furthermore, a comparison of model results with third-order Bernstein polynomials with results using traditional nodal Lagrange polynomials reveals an improvement in numerical convergence.
MULTIVARIATE WEIGHTED BERNSTEIN-TYPE INEQUALITY AND ITS APPLICATIONS
Institute of Scientific and Technical Information of China (English)
Cao Feilong; Lin Shaobo
2012-01-01
Bernstein inequality played an important role in approximation theory and Fourier analysis.This article first introduces a general system of functions and the socalled multivariate weighted Bernstein,Nikol'skiǐ,and Ul'yanov-type inequalities.Then,the relations among these three inequalities are discussed.Namely,it is proved that a family of functions equipped with Bernstein-type inequality satisfies Nikol'skiǐ-type and Ul'yanov-type inequality.Finally,as applications,some classical inequalities are deduced from the obtained results.
Generalized -Bernstein-Schurer Operators and Some Approximation Theorems
Directory of Open Access Journals (Sweden)
M. Mursaleen
2013-01-01
Full Text Available We study statistical approximation properties of -Bernstein-Shurer operators and establish some direct theorems. Furthermore, we compute error estimation and show graphically the convergence for a function by operators and give its algorithm.
Superthermal electrons and Bernstein waves in Jupiter's inner magnetosphere
Barbosa, D. D.; Kurth, W. S.
1980-01-01
A theoretical model for generation of banded electrostatic emissions by low density, superthermal electrons is developed for application to Jupiter's magnetosphere. The model employs a power law form for the energy dependence and a loss cone pitch angle distribution of the superthermals to drive convective instability of Bernstein modes. A direct correspondence between spectral features of the 3/2 band and resonant superthermal electrons is found. The concept of a critical flux of resonant electrons able to provide 10 e-foldings of electric field amplification yields an explicit relation in terms of the background thermal electron pressure. This result is used to construct a theoretical/empirical model of thermal electron density and temperature from 6-20 Jupiter radii in the Jovian magnetosphere which suggests that the electron temperature is less than the ion temperature which is approximately equal to 10 times the electron temperature in this region. Finally, wave ray paths are computed for propagation in the magnetic equator and in the magnetic meridional plane of a dipole magnetic field. These ray paths suggest that intense wave activity is tightly confined to a small latitudinal extent, less than + or - approximately 4 deg, about the magnetic equator.
Proofs of the Cantor-Bernstein theorem a mathematical excursion
Hinkis, Arie
2013-01-01
This book offers an excursion through the developmental area of research mathematics. It presents some 40 papers, published between the 1870s and the 1970s, on proofs of the Cantor-Bernstein theorem and the related Bernstein division theorem. While the emphasis is placed on providing accurate proofs, similar to the originals, the discussion is broadened to include aspects that pertain to the methodology of the development of mathematics and to the philosophy of mathematics. Works of prominent mathematicians and logicians are reviewed, including Cantor, Dedekind, Schröder, Bernstein, Borel, Zermelo, Poincaré, Russell, Peano, the Königs, Hausdorff, Sierpinski, Tarski, Banach, Brouwer and several others mainly of the Polish and the Dutch schools. In its attempt to present a diachronic narrative of one mathematical topic, the book resembles Lakatos’ celebrated book Proofs and Refutations. Indeed, some of the observations made by Lakatos are corroborated herein. The analogy between the two books is clearly an...
Ion Bernstein waves in a magnetic reconnection region
Narita, Y.; Nakamura, R.; Baumjohann, W.; Glassmeier, K. H.; Motschmann, U.; Comisel, H.
2015-12-01
Four-dimensional energy spectra and a diagram for dispersion relations are determined for the first time in a magnetic reconnection region in the magnetotail using the four-point magnetometer data from the Cluster mission on a spatial scale of 200 km, about 0.1 ion inertial lengths. The energy spectra are anisotropic with an extension in the perpendicular direction and axially asymmetric with respect to the mean magnetic field. The dispersion diagram for the waves in the quasi-perpendicular directions in the plasma rest frame is in reasonably good agreement with the ion Bernstein waves particularly at the second harmonic of the proton gyro-frequency. Perpendicular-propagating ion Bernstein waves likely exist in an outflow region of magnetic reconnection. We discuss the causality of the Bernstein waves with magnetic reconnection with an estimate of the anomalous resistivity, and propose an observationally-driven model of turbulent magnetic reconnection.
Interpolation and Convergence of Bernstein-Bézier Coefficients
Institute of Scientific and Technical Information of China (English)
Feng Jun LI
2011-01-01
In this paper,two ways of the proof are given for the fact that the Berustein-Bézier coefficients (BB-coefficients) of a multivariate polynomial converge uniformly to the polynomial under repeated degree elevation over the simplex.We show that the partial derivatives of the inverse Bernstein polynomial An(g) converge uniformly to the corresponding partial derivatives of g at the rate 1/n.We also consider multivariate interpolation for the BB-coefficients,and provide effective interpolation formulas by using Bernstein polynomials with ridge form which essentially possess the nature of univariate polynomials in computation,and show that Bernstein polynomials with ridge form with least degree can be constructed for interpolation purpose,and thus a computational algorithm is provided correspondingly.
McPhail, Graham J.
2016-01-01
In 2002 Parlo Singh outlined Bernstein's theory of the pedagogic device, elaborating the potential in Bernstein's complex theoretical framework for empirical research. In particular, Singh suggests that Bernstein's concepts provide the means of making explicit the macro and micro structuring of knowledge into pedagogic communication. More…
Bin, W.; Alessi, E.; Bruschi, A.; D'Arcangelo, O.; Figini, L.; Galperti, C.; Garavaglia, S.; Granucci, G.; Moro, A.
2014-05-01
The algorithm for the automatic control of the new front steering antenna of the Frascati Tokamak Upgrade device has been improved, in view of forthcoming experiments aimed at testing the mode conversion of electron cyclotron waves at a frequency of 140 GHz. The existing antenna system has been prepared to provide two-point real-time measurements of electron Bernstein waves and to allow real-time tracking of the optimal conversion region. This required an accurate analysis of the antenna to minimize the risk of a mechanical damage of the movable launching mirrors, when accessing the high toroidal launching angles needed for this kind of experiment. A detailed description is presented of the work carried out to safely reach and validate the desired range of steering angles, which include the region of interest, and a technique is proposed to track and chase the correct line of sight for electron Bernstein waves detection during the shot.
On the convective properties of magnetospheric Bernstein waves
Barbosa, D. D.
1980-01-01
Recent plasma wave observations made by the ISEE and GEOS satellites of the electrostatic cyclotron harmonic waves have been consistent with and organized very well within the theoretical framework of Bernstein waves excited in magnetospheric plasma. Attention is given to an examination of a number of effects that result simply from the convective properties of Bernstein waves in a magnetospheric plasma environment. The roles of wave trapping in plasma density depressions and partial trappings near the magnetic equator are discussed. Certain future wave observations are suggested that can improve the understanding of this magnetospheric wave phenomenon.
Min, Kyungguk; Liu, Kaijun; Gary, S. Peter
2016-03-01
A ring-like proton velocity distribution with ∂fp(v⊥)/∂v⊥>0 and which is sufficiently anisotropic can excite two distinct types of growing modes in the inner magnetosphere: ion Bernstein instabilities with multiple ion cyclotron harmonics and quasi-perpendicular propagation and an Alfvén-cyclotron instability at frequencies below the proton cyclotron frequency and quasi-parallel propagation. Recent particle-in-cell simulations have demonstrated that even if the maximum linear growth rate of the latter instability is smaller than the corresponding growth of the former instability, the saturation levels of the fluctuating magnetic fields can be greater for the Alfvén-cyclotron instability than for the ion Bernstein instabilities. In this study, linear dispersion theory and two-dimensional particle-in-cell simulations are used to examine scalings of the linear growth rate and saturation level of the two types of growing modes as functions of the temperature anisotropy T⊥/T|| for a general ring-like proton distribution with a fixed ring speed of 2vA, where vA is the Alfvén speed. For the proton distribution parameters chosen, the maximum linear theory growth rate of the Alfvén-cyclotron waves is smaller than that of the fastest-growing Bernstein mode for the wide range of anisotropies (1≤T⊥/T||≤7) considered here. Yet the corresponding particle-in-cell simulations yield a higher saturation level of the fluctuating magnetic fields for the Alfvén-cyclotron instability than for the Bernstein modes as long as T⊥/T|| ≳ 3. Since fast magnetosonic waves with ion Bernstein instability properties observed in the magnetosphere are often not accompanied by electromagnetic ion cyclotron waves, the results of the present study indicate that the ring-like proton distributions responsible for the excitation of these fast magnetosonic waves should not be very anisotropic.
Approximation of Bernstein-Bezier Operators%算子Bernstein-Bezier的一个逼近定理
Institute of Scientific and Technical Information of China (English)
王瑶准
2015-01-01
本文章以光滑模和K泛函为工具,结合Bernstein多项式的性质及广义的Bernstein-Bezie的逼近定理,讨论了修正的Bernstein-Bezier算子在连续区间C[0,1]上的逼近性质,并得到该算子的点态逼近正定理,丰富了Bernstein算子和Bezier算子的逼近理论.
Some Preserved Properties for Modified Bernstein-Durrmeyer Operators%修正的Bernstein-Durrmeyer算子的若干保持性质
Institute of Scientific and Technical Information of China (English)
马月梅
2005-01-01
修正的Bernstein-Durrmeyer算子既具有一些与Bernstein算子相似的性质,同时也具有Bernstein-Durrmeyer算子的一些性质.研究了修正的Bernstein-Durrmeyer算子的特性,得到相应原函数的单调性、凸性、Hw类的保持性质.所得结果类似于所对应的Bernstein算子的结果.
Contesting Reform: Bernstein's Pedagogic Device and Madrasah Education in Singapore
Tan, Charlene
2010-01-01
This paper highlights the active role played by various pedagogic agents in contesting the state educational reforms for madrasahs in Singapore. Drawing upon Basil Bernstein's pedagogic device, the paper identifies tensions and challenges that arise from the attempts by the state to implement curriculum reforms. The paper contends that the stakes…
New Bernstein type inequalities for polynomials on ellipses
Freund, Roland; Fischer, Bernd
1990-01-01
New and sharp estimates are derived for the growth in the complex plane of polynomials known to have a curved majorant on a given ellipse. These so-called Bernstein type inequalities are closely connected with certain constrained Chebyshev approximation problems on ellipses. Also presented are some new results for approximation problems of this type.
Pointwise Approximation Theorems for Combinations and Derivatives of Bernstein Polynomials
Institute of Scientific and Technical Information of China (English)
Lin Sen XIE
2005-01-01
We establish the pointwise approximation theorems for the combinations of Bernstein polynomials by the rth Ditzian-Totik modulus of smoothness ωγφ(f, t) where φ is an admissible step-weight function. An equivalence relation between the derivatives of these polynomials and the smoothness of functions is also obtained.
Electron-Bernstein Waves in Inhomogeneous Magnetic Fields
DEFF Research Database (Denmark)
Armstrong, R. J.; Frederiksen, Å.; Pécseli, Hans
1984-01-01
The propagation of small amplitude electron-Bernstein waves in different inhomogeneous magnetic field geometries is investigated experimentally. Wave propagation towards both cut-offs and resonances are considered. The experimental results are supported by a numerical ray-tracing analysis. Spatial...
ON LIMITING PROPERTIES OF BERNSTEIN-TROTTER TYPE OPERATOR
Institute of Scientific and Technical Information of China (English)
ZengXiaoming; LinLu
1994-01-01
In this paper ,a class of Bernstein-Trotter type operator and its limiting properties are studied. By using both the limiting theorem and P. Le' vy continuity theorem on probability theory, a theorem of convergence is obtained. The result in [1] is included.
Pointwise Approximation for the Iterated Boolean Sums of Bernstein Operators
Institute of Scientific and Technical Information of China (English)
HUO Xiao-yan; LI Cui-xiang; YAO Qiu-mei
2013-01-01
In this paper,with the help of modulus of smoothness ω2r(4)(f,t),we discuss the pointwise approximation properties for the iterated Boolean sums of Bernstein operator Bnn and obtain direct and inverse theorems when 1-1/r ≤ λ ≤ 1,r ∈ N.
Ion Bernstein waves in the magnetic reconnection region
Narita, Y.; Nakamura, R.; Baumjohann, W.; Glassmeier, K.-H.; Motschmann, U.; Comişel, H.
2016-01-01
Four-dimensional energy spectra and a diagram for dispersion relations are determined for the first time in a magnetic reconnection region in the magnetotail using data from four-spacecraft measurements by the Cluster mission on a spatial scale of 200 km, about 0.1 ion inertial lengths. The energy spectra are anisotropic with an extension in the perpendicular direction and axially asymmetric with respect to the mean magnetic field. The dispersion diagram in the plasma rest frame is in reasonably good agreement with the ion Bernstein waves at the second and higher harmonics of the proton gyrofrequency. Perpendicular-propagating ion Bernstein waves likely exist in an outflow region of magnetic reconnection, which may contribute to bifurcation of the current sheet in the outflow region.
Observation of Bernstein Waves Excited by Newborn Interstellar Pickup Ions in the Solar Wind
Joyce, Colin J.; Smith, Charles W.; Isenberg, Philip A.; Gary, S. Peter; Murphy, Neil; Gray, Perry C.; Burlaga, Leonard F.
2012-01-01
A recent examination of 1.9 s magnetic field data recorded by the Voyager 2 spacecraft in transit to Jupiter revealed several instances of strongly aliased spectra suggestive of unresolved high-frequency magnetic fluctuations at 4.4 AU. A closer examination of these intervals using the highest resolution data available revealed one clear instance of wave activity at spacecraft frame frequencies from 0.2 to 1 Hz. Using various analysis techniques, we have characterized these fluctuations as Bernstein mode waves excited by newborn interstellar pickup ions. We can find no other interpretation or source consistent with the observations, but this interpretation is not without questions. In this paper, we report a detailed analysis of the waves, including their frequency and polarization, that supports our interpretation.
OBSERVATION OF BERNSTEIN WAVES EXCITED BY NEWBORN INTERSTELLAR PICKUP IONS IN THE SOLAR WIND
Energy Technology Data Exchange (ETDEWEB)
Joyce, Colin J.; Smith, Charles W.; Isenberg, Philip A. [Physics Department, Space Science Center, University of New Hampshire, Durham, NH (United States); Peter Gary, S. [Los Alamos National Laboratory, Los Alamos, NM (United States); Murphy, Neil [Jet Propulsion Laboratory, Mail Stop 180-600, 4800 Oak Grove Drive, Pasadena, CA (United States); Gray, Perry C. [P.O. Box 790, Los Alamos, NM (United States); Burlaga, Leonard F., E-mail: cjl46@unh.edu, E-mail: Charles.Smith@unh.edu, E-mail: Phil.Isenberg@unh.edu, E-mail: pgary@lanl.gov, E-mail: Neil.Murphy@jpl.nasa.gov, E-mail: Perry.Gray@dtra.mil, E-mail: lburlagahsp@verizon.net [NASA/Goddard Space Flight Center, Geospace Physics Laboratory, Code 673, Greenbelt, MD 20771 (United States)
2012-02-01
A recent examination of 1.9 s magnetic field data recorded by the Voyager 2 spacecraft in transit to Jupiter revealed several instances of strongly aliased spectra suggestive of unresolved high-frequency magnetic fluctuations at 4.4 AU. A closer examination of these intervals using the highest resolution data available revealed one clear instance of wave activity at spacecraft frame frequencies from 0.2 to 1 Hz. Using various analysis techniques, we have characterized these fluctuations as Bernstein mode waves excited by newborn interstellar pickup ions. We can find no other interpretation or source consistent with the observations, but this interpretation is not without questions. In this paper, we report a detailed analysis of the waves, including their frequency and polarization, that supports our interpretation.
The Schroder-Bernstein property for a-saturated models
Goodrick, John
2012-01-01
A first-order theory T has the Schr\\"oder-Bernstein (SB) property if any pair of elementarily bi-embeddable models are isomorphic. We prove that T has an expansion by constants that has the SB property if and only if T is superstable and non-multidimensional. We also prove that among superstable theories T, the class of a-saturated models of T has the SB property if and only if T has no nomadic types.
Approximation by Chebyshevian Bernstein Operators versus Convergence of Dimension Elevation
Ait-Haddou, Rachid
2016-03-18
On a closed bounded interval, consider a nested sequence of Extended Chebyshev spaces possessing Bernstein bases. This situation automatically generates an infinite dimension elevation algorithm transforming control polygons of any given level into control polygons of the next level. The convergence of these infinite sequences of polygons towards the corresponding curves is a classical issue in computer-aided geometric design. Moreover, according to recent work proving the existence of Bernstein-type operators in such Extended Chebyshev spaces, this nested sequence is automatically associated with an infinite sequence of Bernstein operators which all reproduce the same two-dimensional space. Whether or not this sequence of operators converges towards the identity on the space of all continuous functions is a natural issue in approximation theory. In the present article, we prove that the two issues are actually equivalent. Not only is this result interesting on the theoretical side, but it also has practical implications. For instance, it provides us with a Korovkin-type theorem of convergence of any infinite dimension elevation algorithm. It also enables us to tackle the question of convergence of the dimension elevation algorithm for any nested sequence obtained by repeated integration of the kernel of a given linear differential operator with constant coefficients. © 2016 Springer Science+Business Media New York
Verma, Prabal Singh; Sengupta, Sudip; Kaw, Predhiman
2012-07-01
A one-dimensional particle in cell simulation of large amplitude plasma oscillations is carried out to explore the physics beyond wave breaking in a cold homogeneous unmagnetized plasma. It is shown that after wave breaking, all energy of the plasma oscillation does not end up as random kinetic energy of particles, but some fraction, which is decided by Coffey's wave breaking limit in warm plasma, always remains with two oppositely propagating coherent Bernstein-Greene-Kruskal like modes with supporting trapped particle distributions. The randomized energy distribution of untrapped particles is found to be characteristically non-Maxwellian with a preponderance of energetic particles.
关于加权的Bernstein-Markov型不等式%The Weighted Bernstein-Markov Inequality
Institute of Scientific and Technical Information of China (English)
逯文鸣; 赵易
2010-01-01
假设函数f在端点处具有奇性,该文针对此类函数定义了一类修正的Bernstein算子,并在此基础上给出了修正的Bernstein算子的加权Bernstein-Markov型不等式,此类不等式推广了数学工作者们的结论.
Ion Bernstein instability dependence on the proton-to-electron mass ratio: Linear dispersion theory
Min, Kyungguk; Liu, Kaijun
2016-07-01
Fast magnetosonic waves, which have as their source ion Bernstein instabilities driven by tenuous ring-like proton velocity distributions, are frequently observed in the inner magnetosphere. One major difficulty in the simulation of these waves is that they are excited in a wide frequency range with discrete harmonic nature and require time-consuming computations. To overcome this difficulty, recent simulation studies assumed a reduced proton-to-electron mass ratio, mp/me, and a reduced light-to-Alfvén speed ratio, c/vA, to reduce the number of unstable modes and, therefore, computational costs. Although these studies argued that the physics of wave-particle interactions would essentially remain the same, detailed investigation of the effect of this reduced system on the excited waves has not been done. In this study, we investigate how the complex frequency, ω = ωr+iγ, of the ion Bernstein modes varies with mp/me for a sufficiently large c/vA (such that ωpe2/Ωe2≡(me/mp)(c/vA)2≫1) using linear dispersion theory assuming two different types of energetic proton velocity distributions, namely, ring and shell. The results show that low- and high-frequency harmonic modes respond differently to the change of mp/me. For the low harmonic modes (i.e., ωr˜Ωp), both ωr/Ωp and γ/Ωp are roughly independent of mp/me, where Ωp is the proton cyclotron frequency. For the high harmonic modes (i.e., Ωp≪ωr≲ωlh, where ωlh is the lower hybrid frequency), γ/ωlh (at fixed ωr/ωlh) stays independent of mp/me when the parallel wave number, k∥, is sufficiently large and becomes inversely proportional to (mp/me)1/4 when k∥ goes to zero. On the other hand, the frequency range of the unstable modes normalized to ωlh remains independent of mp/me, regardless of k∥.
Wright, Ruth; Froehlich, Hildegard
2012-01-01
This article describes Basil Bernstein's theory of the pedagogic device as applied to school music instruction. Showing that educational practices are not personal choices alone, but the result of socio-political mandates, the article traces how education functions as a vehicle for social reproduction. Bernstein called this process the…
Basil Bernstein and Emile Durkheim: Two Theories of Change in Educational Systems
Cherkaoui, Mohamed
1977-01-01
Attempts to draw out parallels and differences between Emile Durkheim's and Basil Bernstein's theories of educational systems and highlights Bernstein's reformulation of certain features of Durkheim's thought. Focuses on the role of the school, curriculum change, and social conflict. (Author/RK)
Lp APPROXIMATION BY GENERAL BERNSTEIN-DURRMEYER OPERATOR DEFINED ON SIMPLEX
Institute of Scientific and Technical Information of China (English)
Cao Feilong
2004-01-01
As a generalization of the Bernstein-Durrmeyer operators defined on the simplex, a class of general Bernstein- Durrmeyer operators is introduced. With the weighted moduli of smoothness as a metric, we prove a strong direct theorem and an inverse theorem of weak type for these operators by using a decomposition way. From the theorems the characterization of Lp approximation behavior is derived.
Institute of Scientific and Technical Information of China (English)
黄朝霞
2002-01-01
对Bernstein-Fan算子进行推广,并在此基础上进一步探讨其一致收敛性以及导数与连续模之间的关系.%On the basis of the Bernstein-Fan operator, a generalization is given. Its uniform convergence and the relationship between continuous model and derivative are discussed.
Study on the Third Type of Bernstein S. N. Interpolation Process%第三型Bernstein S．N．插值过程
Institute of Scientific and Technical Information of China (English)
袁学刚; 何甲兴
2001-01-01
对Bernstein S．N．问题做了进一步讨论，利用两点修正的方法构造了算子Pn(f；x)，并得到了较好的结果。%In this paper, Bernstein S. N. problem is studied in a deeper step and a new operator Pn (f;x) is constructed by the method of two revised zero nodes and better results are achieved.
Directory of Open Access Journals (Sweden)
Sally Power
2008-12-01
Full Text Available This paper explores Basil Bernstein’s insights into education and social class, and in particular the relevance of his work for understanding the British middle class. Bernstein is one of the few sociologists of education to recognise and explore differences and tensions within the middle class. We begin by exploring some of the influences of Bernstein’s theorization of social class in general, and outline his main ideas on the relationship between the middle class and education in particular. We then examine the relevance of his work for research on education and middle-class differentiation through drawing on data from our ‘Destined for Success’ project. This project traced the educational biographies of 300 young men and women from the beginning of their promising educational secondary school career to their mid-twenties. We argue that the distinctive dispositions and orientations of the ‘new’ and ‘old’ middle class proposed by Bernstein are evident within parental preferences for types of school, processes of student engagement and, ultimately, differentiated middle-class identities.
A teoria de Basil Bernstein: alguns aspectos fundamentais
Directory of Open Access Journals (Sweden)
Ana Maria Morais
2007-12-01
Full Text Available The article begins with a reference to the pieces of work that Basil Bernstein considered to have been the landmarks of the evolution of his thought. This is followed by a detailed description of the two models that contain the main concepts of his theory – Model of Cultural Reproduction and Transformation and Model of Pedagogic Discourse – where the theoretical meaning of these models and concepts is explained and where are given some examples of how to put them into practice at the level of pedagogic texts and contexts. The article also includes the most recent developments of Bernstein’s thought by explaining his ideas about the forms discourses can take – Vertical and Horizontal Discourses. Finally, Bernstein’s theory is approached within the framework of the empirical research, highlighting his epistemological positioning and explicating the methodological model that he suggested should be the driving force of any theory.
Directory of Open Access Journals (Sweden)
Ryoo CS
2010-01-01
Full Text Available The purpose of this paper is to give some properties of several Bernstein type polynomials to represent the fermionic -adic integral on . From these properties, we derive some interesting identities on the Euler numbers and polynomials.
Bernstein dual-Petrov-Galerkin method: application to 2D time fractional diffusion equation
Jani, Mostafa; Babolian, Esmail
2016-01-01
In this paper, we develop a dual-Petrov-Galerkin method using Bernstein polynomials. The method is then implemented for the numerical simulation of the two-dimensional subdiffusion equation. The method is based on a finite difference discretization in time and a spectral method in space utilizing a suitable compact combinations of dual Bernstein basis as the test functions and the Bernstein polynomials as the trial ones. We derive the exact sparse operational matrix of differentiation for the dual Bernstein basis which provides a matrix-based approach for spatial discretization of the problem. It is also shown that the proposed method leads to banded linear systems. Finally some numerical examples are provided to show the efficiency and accuracy of the method.
Some approximation properties of ( p , q $(p,q$ -Bernstein operators
Directory of Open Access Journals (Sweden)
Shin Min Kang
2016-06-01
Full Text Available Abstract This paper is concerned with the ( p , q $(p,q$ -analog of Bernstein operators. It is proved that, when the function is convex, the ( p , q $(p,q$ -Bernstein operators are monotonic decreasing, as in the classical case. Also, some numerical examples based on Maple algorithms that verify these properties are considered. A global approximation theorem by means of the Ditzian-Totik modulus of smoothness and a Voronovskaja type theorem are proved.
Design of an RF System for Electron Bernstein Wave Studies in MST
Kauffold, J. X.; Seltzman, A. H.; Anderson, J. K.; Nonn, P. D.; Forest, C. B.
2010-11-01
Motivated by the possibility of current profile control a 5.5GHz RF system for EBW is being developed. The central component is a standard radar Klystron with 1.2MW peak power and 4μs typical pulse length. Meaningful experiments require RF pulse lengths similar to the characteristic electron confinement times in MST necessitating the creation of a power supply providing 80kV at 40A for 10ms. A low inductance IGBT network switches power at 20kHz from an electrolytic capacitor bank into the primary of a three-phase resonant transformer system that is then rectified and filtered. The system uses three magnetically separate transformers with microcrystalline iron cores to provide suitable volt-seconds and low hysteresis losses. Each phase has a secondary with a large leakage inductance and a parallel capacitor providing a boost ratio greater than 60:1 with a physical turns ratio of 13.5:1. A microprocessor feedback control system varies the drive frequency around resonance to regulate the boost ratio and provide a stable output as the storage bank discharges. The completed system will deliver RF to the plasma boundary where coupling to the Bernstein mode and subsequent heating and current drive can occur.
Alfven Eigenmode And Ion Bernstein Wave Studies For Controlling Fusion Alpha Particles
Heeter, R F
1999-01-01
In magnetic confinement fusion reactor plasmas, the charged fusion products (such as alpha particles in deuterium-tritium plasmas) will be the dominant power source, and by controlling these charged fusion products using wave-particle interactions the reactor performance could be optimized. This thesis studies two candidate waves: Mode-Converted Ion Bernstein Waves (MCIBWs) and Alfvén Eigenmodes (AEs). Rates of MCIBW-driven losses of alpha-like fast deuterons, previously observed in the Tokamak Fusion Test Reactor (TFTR), are reproduced by a new model so that the wave-particle diffusion coefficient can be deduced. The MCIBW power in TFTR is found to be ∼ 1/3 that needed for collisionless alpha particle control. A reasonable reactor power scaling is derived. To study AEs, existing magnetic fluctuation probes at the Joint European Torus (JET) have been absolutely calibrated from 30–500 kHz for the first time, allowing fluctuation measurements with &vbm0;dBpol&vbm0;/B0&am...
Uncertainty Quantification for Polynomial Systems via Bernstein Expansions
Crespo, Luis G.; Kenny, Sean P.; Giesy, Daniel P.
2012-01-01
This paper presents a unifying framework to uncertainty quantification for systems having polynomial response metrics that depend on both aleatory and epistemic uncertainties. The approach proposed, which is based on the Bernstein expansions of polynomials, enables bounding the range of moments and failure probabilities of response metrics as well as finding supersets of the extreme epistemic realizations where the limits of such ranges occur. These bounds and supersets, whose analytical structure renders them free of approximation error, can be made arbitrarily tight with additional computational effort. Furthermore, this framework enables determining the importance of particular uncertain parameters according to the extent to which they affect the first two moments of response metrics and failure probabilities. This analysis enables determining the parameters that should be considered uncertain as well as those that can be assumed to be constants without incurring significant error. The analytical nature of the approach eliminates the numerical error that characterizes the sampling-based techniques commonly used to propagate aleatory uncertainties as well as the possibility of under predicting the range of the statistic of interest that may result from searching for the best- and worstcase epistemic values via nonlinear optimization or sampling.
MALDI-TOF Baseline Drift Removal Using Stochastic Bernstein Approximation
Directory of Open Access Journals (Sweden)
Howard Daniel
2006-01-01
Full Text Available Stochastic Bernstein (SB approximation can tackle the problem of baseline drift correction of instrumentation data. This is demonstrated for spectral data: matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF data. Two SB schemes for removing the baseline drift are presented: iterative and direct. Following an explanation of the origin of the MALDI-TOF baseline drift that sheds light on the inherent difficulty of its removal by chemical means, SB baseline drift removal is illustrated for both proteomics and genomics MALDI-TOF data sets. SB is an elegant signal processing method to obtain a numerically straightforward baseline shift removal method as it includes a free parameter that can be optimized for different baseline drift removal applications. Therefore, research that determines putative biomarkers from the spectral data might benefit from a sensitivity analysis to the underlying spectral measurement that is made possible by varying the SB free parameter. This can be manually tuned (for constant or tuned with evolutionary computation (for .
Nash, Roy
2006-01-01
Can an explanation of the origins of social disparities in educational achievement be assisted by a critical examination of Bernstein's sociology? This central question is approached by a consideration of the status of Bernstein's socio-linguistic thesis. The focus is on the nature of the explanations provided. The paper asks: What is the…
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M.H.T. Alshbool
2017-01-01
Full Text Available An algorithm for approximating solutions to fractional differential equations (FDEs in a modified new Bernstein polynomial basis is introduced. Writing x→xα(0<α<1 in the operational matrices of Bernstein polynomials, the fractional Bernstein polynomials are obtained and then transformed into matrix form. Furthermore, using Caputo fractional derivative, the matrix form of the fractional derivative is constructed for the fractional Bernstein matrices. We convert each term of the problem to the matrix form by means of fractional Bernstein matrices. A basic matrix equation which corresponds to a system of fractional equations is utilized, and a new system of nonlinear algebraic equations is obtained. The method is given with some priori error estimate. By using the residual correction procedure, the absolute error can be estimated. Illustrative examples are included to demonstrate the validity and applicability of the presented technique.
dos Santos, Mateus Casanova; Leite, Maria Cecília Lorea; Heck, Rita Maria
2010-12-01
This is an investigative case study with descriptive and participative character, based on an educational experience with the Simulation in Nursing learning trigger. It was carried out during the second semester of the first cycle of Faculdade de Enfermagem (FEN), Universidade Federal de Pelotas (UFPel). The aim is to study the recontextualization of pedagogic practice of simulation-based theories developed by Basil Bernstein, an education sociologist, and to contribute with the improvement process of education planning, and especially the evaluation of learning trigger. The research shows that Bernstein's theory is a powerful tool semiotic pedagogical of practices which contributes to the planning and analysis of curricular educational device.
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Mohsen Alipour
2014-01-01
Full Text Available We introduce a new combination of Bernstein polynomials (BPs and Block-Pulse functions (BPFs on the interval [0, 1]. These functions are suitable for finding an approximate solution of the second kind integral equation. We call this method Hybrid Bernstein Block-Pulse Functions Method (HBBPFM. This method is very simple such that an integral equation is reduced to a system of linear equations. On the other hand, convergence analysis for this method is discussed. The method is computationally very simple and attractive so that numerical examples illustrate the efficiency and accuracy of this method.
On Bernstein type inequalities and a weighted Chebyshev approximation problem on ellipses
Freund, Roland
1989-01-01
A classical inequality due to Bernstein which estimates the norm of polynomials on any given ellipse in terms of their norm on any smaller ellipse with the same foci is examined. For the uniform and a certain weighted uniform norm, and for the case that the two ellipses are not too close, sharp estimates of this type were derived and the corresponding extremal polynomials were determined. These Bernstein type inequalities are closely connected with certain constrained Chebyshev approximation problems on ellipses. Some new results were also presented for a weighted approximation problem of this type.
Code switching and sexual orientation: a test of Bernstein's sociolinguistic theory.
Lumby, M E
1976-01-01
Bernstein's theory was tested in the homosexual's "closed" community to determine code-switching ability and its relationship to jargon. Subjects told a story based on homoerotic photographs where knowledge of sexual orientation was varied. Rather than finding the restricted code associated with in-group communication, an analysis of data trends (since all hypotheses were rejected) suggests that homosexual hemophyly encouraged elaboration, and status differentiation resulted in a more restricted code. Story length was the most significant variable across groups. Some of Bernstein's theoretical explanations require modification to account for subjects' behavior in stigmatized social groups.
APPLICATIONS OF THE BERNSTEIN-DURRMEYER OPERATORS IN ESTIMATING THE NORM OF MERCER KERNEL MATRICES
Institute of Scientific and Technical Information of China (English)
Chunping Zhang; Baohuai Sheng; Zhixiang Chen
2008-01-01
The paper is related to the norm estimate of Mercer kernel matrices.The lower and upper bound estimates of Rayleigh entropy numbers for some Mercer kernel matrices on[0,1]×[0,1]based on the Bernstein-Durrmeyer operator kernel ale obtained,with which and the approximation property of the Bernstein-Durrmeyer operator the lower and upper bounds of the Rayleigh entropy number and the l2-norm for general Mercer kernel matrices on[0,1]×[0,1]are provided.
A Bernstein type inequality associated with wavelet bi-frame decomposition
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Kai-Cheng Wang
2016-10-01
Full Text Available Abstract Bernstein inequality is an essential inequality for Besov spaces. Smoothness based approaches are widely used in establishing the inequality. Yet, despite numerous studies over the last two decades, there is still little research focusing on decay-based approaches. However, motivating authors to establish inequality poses challenges, many of which can be overcome by means of the completeness of wavelet bi-frames in Lebesgue spaces and the stability of wavelet coefficients. The research has shown how wavelets with decay conditions enable descriptions of Lebesgue spaces, and in particular, the Bernstein inequality.
A critique of Bernstein's beyond objectivism and relativism: science, hermeneutics, and praxis.
Matusitz, Jonathan; Kramer, Eric
2011-06-01
This analysis comments on Bernstein's lack of clear understanding of subjectivity, based on his book, Beyond Objectivism and Relativism: Science, Hermeneutics, and Praxis. Bernstein limits his interpretation of subjectivity to thinkers such as Gadamer and Habermas. The authors analyze the ideas of classic scholars such as Edmund Husserl and Friedrich Nietzsche. Husserl put forward his notion of transcendental subjectivity and phenomenological ramifications of the relationship between subjectivity and objectivity. Nietzsche referred to subjectivity as "perspectivism," the inescapable fact that any and all consciousnesses exist in space and time. Consciousness is fundamentally constituted of cultural, linguistic, and historical dimensions.
Small amplitude variable charge dust Bernstein-Greene-Kruskal double layers
Energy Technology Data Exchange (ETDEWEB)
Amour, Rabia [Plasma Physics Group, Theoretical Physics Laboratory, Faculty of Sciences - Physics, U.S.T.H.B, Bab-Ezzouar, B.P. 32, El Alia, Algiers 16111 (Algeria); Tribeche, Mouloud [Plasma Physics Group, Theoretical Physics Laboratory, Faculty of Sciences - Physics, U.S.T.H.B, Bab-Ezzouar, B.P. 32, El Alia, Algiers 16111 (Algeria)], E-mail: mouloud-tribeche@lycos.com
2009-05-11
A first theoretical attempt is made to investigate small amplitude, variable charge dust Bernstein-Greene-Kruskal (BGK) double layers (DLs). The nature of the dust BGK-DLs (compressive or rarefactive), their strength and thickness depend sensitively on the net negative charge residing on the grain surface, the dust grain dynamics and, more interestingly, on the ion-to-electron temperatures ratio.
Bernstein Revisited: The Recontextualisation of Equity in Contemporary Australian School Education
Loughland, Tony; Sriprakash, Arathi
2016-01-01
This article draws on the sociology of Basil Bernstein to show how his detailed theories of "recontextualisation" and the "pedagogic device" provide useful analytic levers to examine the politics of educational change. We focus on recent policy developments that have significantly impacted Australian school education: the…
On the Effects of Social Class on Language Use: A Fresh Look at Bernstein's Theory
Aliakbari, Mohammad; Allahmoradi, Nazal
2014-01-01
Basil Bernstein (1971) introduced the notion of the Restricted and the Elaborated code, claiming that working-class speakers have access only to the former but middle-class members to both. In an attempt to test this theory in the Iranian context and to investigate the effect of social class on the quality of students language use, we examined the…
When Is a Bernstein-bezier Curve the Graph of a Function?
Mclaughlin, H. W.
1985-01-01
The question of determining when a Bernstein-Bezier cubic curve in the plane can be represented as the graph of function in some fixed orthogonal coordinate system is considered. The notion of a curve being monotone in a given direction is introduced to aid in the analysis.
Measurements of Intrinsic Ion Bernstein Waves in a Tokamak by Collective Thomson Scattering
DEFF Research Database (Denmark)
Korsholm, Søren Bang; Stejner Pedersen, Morten; Bindslev, Henrik;
2011-01-01
In this Letter we report measurements of collective Thomson scattering (CTS) spectra with clear signatures of ion Bernstein waves and ion cyclotron motion in tokamak plasmas. The measured spectra are in accordance with theoretical predictions and show clear sensitivity to variation in the density...
Erickson, Frederick
2009-01-01
After briefly outlining Bernstein's personal and educational history, the paper goes on to review the scope of his work over the past 30 years, his theoretical contribution and his position among colleagues in the post-WWII era of British sociology. There follows a more detailed examination of the main tenets of his theory, pointing out that…
Jackson-type and Bernstein-type inequalities for multipliers on Herz-type Hardy spaces
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
We establish Jackson-type and Bernstein-type inequalities for multipliers on Herz-type Hardy spaces. These inequalities can be applied to some important operators in Fourier analysis, such as the Bochner-Riesz multiplier over the critical index, the generalized Bochner-Riesz mean and the generalized Able-Poisson operator.
David, Mr Bear and Bernstein: Searching for an Equitable Pedagogy through Guided Group Work
Boyle, Bill; Charles, Marie
2012-01-01
The authors' experiences of observing teaching and learning in schools have led them to become concerned at the dominant paradigm of a "pedagogy of poverty" at the expense of a "pedagogy of plenty". Bernstein's theory of power and control of education knowledge is overtly practised in classrooms globally. This is evidenced in…
Translation of Bernstein Coefficients Under an Affine Mapping of the Unit Interval
Alford, John A., II
2012-01-01
We derive an expression connecting the coefficients of a polynomial expanded in the Bernstein basis to the coefficients of an equivalent expansion of the polynomial under an affine mapping of the domain. The expression may be useful in the calculation of bounds for multi-variate polynomials.
The Importance of Voice in Supervision: A Response to Ellis and Robbins (1993) and Bernstein (1993).
Twohey, Denise
1993-01-01
Comments two responses to author's article "Listening for the Voices of Care and Justice in Counselor Supervision" (Twohey and Volker, 1993). Responds to Ellis and Robbins (1993) by clarifying perspective on relationship between moral decision making and supervision. Takes issue with Bernstein's (1993) comments about superiority of instrumental…
Hong, X; Harris, C J
2000-01-01
This paper introduces a new neurofuzzy model construction algorithm for nonlinear dynamic systems based upon basis functions that are Bézier-Bernstein polynomial functions. This paper is generalized in that it copes with n-dimensional inputs by utilising an additive decomposition construction to overcome the curse of dimensionality associated with high n. This new construction algorithm also introduces univariate Bézier-Bernstein polynomial functions for the completeness of the generalized procedure. Like the B-spline expansion based neurofuzzy systems, Bézier-Bernstein polynomial function based neurofuzzy networks hold desirable properties such as nonnegativity of the basis functions, unity of support, and interpretability of basis function as fuzzy membership functions, moreover with the additional advantages of structural parsimony and Delaunay input space partition, essentially overcoming the curse of dimensionality associated with conventional fuzzy and RBF networks. This new modeling network is based on additive decomposition approach together with two separate basis function formation approaches for both univariate and bivariate Bézier-Bernstein polynomial functions used in model construction. The overall network weights are then learnt using conventional least squares methods. Numerical examples are included to demonstrate the effectiveness of this new data based modeling approach.
Jackson-type and Bernstein-type inequalities for multipliers on Herz-type Hardy spaces
Institute of Scientific and Technical Information of China (English)
XIE LinSen; LAN JiaCheng; LAN SenHua; YAN DunYan
2009-01-01
We establish Jackson-type and Bernstein-type inequalities for multipliers on Herz-type Hardy spaces.These inequalities can be applied to some important operators in Fourier analysis,such as the Bochner-Riesz multiplier over the critical index,the generalized Bochner-Riesz mean and the generalized Able-Poisson operator.
Institute of Scientific and Technical Information of China (English)
程丽
2010-01-01
利用r阶Ditzian-Totik光滑模ωrφλ(f,t)(0≤λ≤1)给出了关于Bernstein-Kantorovich算子线性组合同时逼近的等价定理;同时研究了Bernstein-Kantorovich算子的高阶导数与所逼近函数高阶导数的光滑性之间的关系.
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Using the pointwise modulus of continuity, wediscussed the simultaneous approximation for Bernstein-Durrmeyeroperators. The results include the results on functions of boundedvariation and continuous functions.%本文利用点态连续模研究了Bernstein-Durrmeyer算子的同时逼近,推广了关于有界变差函数和连续函数的结果.
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Hiroe IGAMI; Hiroshi IDEI; Shin KUBO; Yasuo YOSHIMURA; Takashi SHIMOZUMA; Hiromi TAKAHASHI
2011-01-01
Possibility of the measurement of radiated waves derived from the thermally emitted electron Bernstein wave （EBW） is numerically investigated based on the assumption of the super dense core （SDC） plasma generated in LHD. EBW that is thermally emitted in the electron cyclotron resonance （ECR） layer may couple with the electromagnetic wave and be emitted to the vacuum via the EBW-extraordinary-ordinary （B-X-O） mode conversion process. We consider the use of one of the transmission lines for electron cyclotron heating （ECH） in LHD as a receiving system of the emission. It is derived that the waves in the fundamental cyclotron frequency range are emitted as the EBW near their upper hybrid resonance （UHR） layer outside the last close flux surface （LCFS）. On the other hand, waves in the second harmonics cyclotron frequency range are emitted in the core region. It means that successful measurement of waves of the second harmonic frequency range emitted from extremely high dense core plasma with setting an aim angle for receiving indicates a possibility of the second harmonic ECH by EBW in the core region with setting the same aim angle and the same polarization for launching.
用Bernstein型算子刻划Besov空间%The Description of Besov Spaces with Bernstein Type Operators
Institute of Scientific and Technical Information of China (English)
陈文忠; 盛保怀
2000-01-01
利用包括Bernstein算子,Bernstein-Kantorovic算子以及Bernstein-Durrmeyer算子的Bernstein型算子刻划由DeVore-Yu Xiangming引入的一类Besov空间,并运用K-泛函与内插空间之间的内在联系,建立刻划这类Besov空间特征的等价定理.
Andrew Bernstein, Modern Passings. Death Rites, Politics and Social Change in Imperial Japan
Duteil-Ogata, Fabienne
2010-01-01
Andrew Bernstein, historien américain nous présente ici une étude portant sur une période charnière de l’histoire des funérailles au Japon : celle qui débute avec l’ère Meiji (1868-1912) et prend fin en 1945, la période du shintô d’État. Basé sur un travail minutieux de dépouillement de la presse nationale et locale, des archives officielles et des archives des premières sociétés de pompes funèbres, A. Bernstein nous montre comment, durant cette période, les funérailles n’échappent pas au pro...
Examining the Bernstein global optimization approach to optimal power flow problem
Patil, Bhagyesh V.; Sampath, L. P. M. I.; Krishnan, Ashok; Ling, K. V.; Gooi, H. B.
2016-10-01
This work addresses a nonconvex optimal power flow problem (OPF). We introduce a `new approach' in the context of OPF problem based on the Bernstein polynomials. The applicability of the approach is studied on a real-world 3-bus power system. The numerical results obtained with this new approach for a 3-bus system reveal a satisfactory improvement in terms of optimality. The results are found to be competent with generic global optimization solvers BARON and COUENNE.
The exact order of approximation to periodic functions by Bernstein-Stechkin polynomials
Energy Technology Data Exchange (ETDEWEB)
Trigub, R M [Donetsk National University, Donetsk (Ukraine)
2013-12-31
The paper concerns the approximation properties of the Bernstein-Stechkin summability method for trigonometric Fourier series. The Jackson-Stechkin theorem is refined. Moreover, for any continuous periodic function not only is the exact upper estimate for approximation found, a lower estimate of the same order is also put forward. To do this special moduli of smoothness and the K-functional are introduced. Bibliography: 16 titles.
On the Acceleration Problem of q-Bernstein Polynomials%关于q-Bernstein多项式的加速问题
Institute of Scientific and Technical Information of China (English)
云连英; 项雪艳; 王慧
2008-01-01
In this paper,we investigate not only the acceleration problem of the q-Bernstein polynomials Bn(f,q;x)to B∞(f,q;x)but also the convergence of their iterated Boolean sum.Using the methods of exact estimate and theories of modulus of smoothness,we get the respective estimates of the convergence rate,which suggest that q-Bernstein polynomials have the similar answer with the classical Bernstein polynomials to these two problems.
Fokker-Planck/Ray Tracing for Electron Bernstein and Fast Wave Modeling in Support of NSTX
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Harvey, R. W. [CompX, Del Mar, CA (United States)
2009-11-12
This DOE grant supported fusion energy research, a potential long-term solution to the world's energy needs. Magnetic fusion, exemplified by confinement of very hot ionized gases, i.e., plasmas, in donut-shaped tokamak vessels is a leading approach for this energy source. Thus far, a mixture of hydrogen isotopes has produced 10's of megawatts of fusion power for seconds in a tokamak reactor at Princeton Plasma Physics Laboratory in New Jersey. The research grant under consideration, ER54684, uses computer models to aid in understanding and projecting efficacy of heating and current drive sources in the National Spherical Torus Experiment, a tokamak variant, at PPPL. The NSTX experiment explores the physics of very tight aspect ratio, almost spherical tokamaks, aiming at producing steady-state fusion plasmas. The current drive is an integral part of the steady-state concept, maintaining the magnetic geometry in the steady-state tokamak. CompX further developed and applied models for radiofrequency (rf) heating and current drive for applications to NSTX. These models build on a 30 year development of rf ray tracing (the all-frequencies GENRAY code) and higher dimensional Fokker-Planck rf-collisional modeling (the 3D collisional-quasilinear CQL3D code) at CompX. Two mainline current-drive rf modes are proposed for injection into NSTX: (1) electron Bernstein wave (EBW), and (2) high harmonic fast wave (HHFW) modes. Both these current drive systems provide a means for the rf to access the especially high density plasma--termed high beta plasma--compared to the strength of the required magnetic fields. The CompX studies entailed detailed modeling of the EBW to calculate the efficiency of the current drive system, and to determine its range of flexibility for driving current at spatial locations in the plasma cross-section. The ray tracing showed penetration into NSTX bulk plasma, relatively efficient current drive, but a limited ability to produce current over
Keim, Inken
2009-01-01
This paper begins by looking at responses to Bernstein in Germany in the 1970s that criticized his notions of class difference in sociolinguistic codes. As part of a re-examination of Bernstein's ideas, the paper goes on to look at the current communicative situation in German education where urban schools have many second-generation immigrant…
Bernstein-Type and Steckin-Type Inequality(I)%Bernstein型不等式与Steckin型不等式
Institute of Scientific and Technical Information of China (English)
林绍波; 曹飞龙
2009-01-01
Bernstein and Steckin inequalities play an important role in approximation theory.For example,Bernstein inequality is the main tool to prove the Inverse Theorem and Embedding Theorem.This paper establishes the relation between weighted Bernstein-type inequality and Steckin-type inequality in a general system of multivariate function.%Bernstein不等式在三角多项式逼近中起着非常重要的作用,比如它是证明逼近论逆定理即Steckin不等式的主要工具.文章建立了多维加权Bernstein型不等式与Steckin型不等式的关系,并进一步给出若干应用.
On S.N. Bernstein's derivation of Mendel's Law and 'rediscovery' of the Hardy-Weinberg distribution
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Alan Stark
2012-01-01
Full Text Available Around 1923 the soon-to-be famous Soviet mathematician and probabilist Sergei N. Bernstein started to construct an axiomatic foundation of a theory of heredity. He began from the premise of stationarity (constancy of type proportions from the first generation of offspring. This led him to derive the Mendelian coefficients of heredity. It appears that he had no direct influence on the subsequent development of population genetics. A basic assumption of Bernstein was that parents coupled randomly to produce offspring. This paper shows that a simple model of non-random mating, which nevertheless embodies a feature of the Hardy-Weinberg Law, can produce Mendelian coefficients of heredity while maintaining the population distribution. How W. Johannsen's monograph influenced Bernstein is discussed.
PAC-Bayes-Bernstein Inequality for Martingales and its Application to Multiarmed Bandits
Seldin, Yevgeny; Auer, Peter; Laviolette, François; Shawe-Taylor, John
2011-01-01
We combine PAC-Bayesian analysis with a Bernstein-type inequality for martingales to obtain a result that makes it possible to control the concentration of multiple (possibly uncountably many) simultaneously evolving and interdependent martingales. We apply this result to derive a regret bound for the multiarmed bandit problem. Our result forms a basis for integrative simultaneous analysis of exploration-exploitation and model order selection trade-offs. It also opens a way for applying PAC-Bayesian analysis in other fields, where sequentially dependent samples and limited feedback are encountered.
Invertibility of random submatrices via the Non-Commutative Bernstein Inequality
Chrétien, Stéphane
2011-01-01
Let $X$ be a $n\\times p$ matrix. We provide a detailed study of the quasi isometry property for random submatrices of $X$ obtained by uniform column sampling. The analysis relies on a tail decoupling argument with explicit constants and a recent version of the Non-Commutative Bernstein inequality (NCBI) [14]. Our results complement those obtained in [13] for the moments of submatrices. They also generalize and improve on those in [2], which are based on a Non-Commutative Kahane- Kintchine inequality (NCKI).
Transport Implementation of the Bernstein-Vazirani Algorithm with Ion Qubits
Fallek, Spencer; McMahon, Brian; Maller, Kara; Brown, Kenneth; Amini, Jason
2016-01-01
Using trapped ion quantum bits in a scalable microfabricated surface trap, we perform the Bernstein-Vazirani algorithm. Our architecture relies upon ion transport and can readily be expanded to larger systems. The algorithm is demonstrated using two- and three-ion chains. For three ions, an improvement is achieved compared to a classical system using the same number of oracle queries. For two ions and one query, we correctly determine an unknown bit string with probability 97.6(8)%. For three ions, we succeed with probability 80.9(3)%.
Bernstein Series Solution of a Class of Lane-Emden Type Equations
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Osman Rasit Isik
2013-01-01
Full Text Available The purpose of this study is to present an approximate solution that depends on collocation points and Bernstein polynomials for a class of Lane-Emden type equations with mixed conditions. The method is given with some priori error estimate. Even the exact solution is unknown, an upper bound based on the regularity of the exact solution will be obtained. By using the residual correction procedure, the absolute error can be estimated. Also, one can specify the optimal truncation limit n which gives a better result in any norm. Finally, the effectiveness of the method is illustrated by some numerical experiments. Numerical results are consistent with the theoretical results.
Transport implementation of the Bernstein-Vazirani algorithm with ion qubits
Fallek, S. D.; Herold, C. D.; McMahon, B. J.; Maller, K. M.; Brown, K. R.; Amini, J. M.
2016-08-01
Using trapped ion quantum bits in a scalable microfabricated surface trap, we perform the Bernstein-Vazirani algorithm. Our architecture takes advantage of the ion transport capabilities of such a trap. The algorithm is demonstrated using two- and three-ion chains. For three ions, an improvement is achieved compared to a classical system using the same number of oracle queries. For two ions and one query, we correctly determine an unknown bit string with probability 97.6(8)%. For three ions, we succeed with probability 80.9(3)%.
Morita invariance of the filter dimension and of the inequality of Bernstein
Bavula, V.V.; Hinchcliffe, V.
2006-01-01
It is proved that the filter dimenion is Morita invariant. A direct consequence of this fact is the Morita invariance of the inequality of Bernstein: if an algebra $A$ is Morita equivalent to the ring $\\CD (X)$ of differential operators on a smooth irreducible affine algebraic variety $X$ of dimension $n\\geq 1$ over a field of characteristic zero then the Gelfand-Kirillov dimension $ \\GK (M)\\geq n = \\frac{\\GK (A)}{2}$ for all nonzero finitely generated $A$-modules $M$. In fact, a more strong ...
Extracting the QCD Cutoff Parameter Using the Bernstein Polynomials and the Truncated Moments
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A. Mirjalili
2014-01-01
Full Text Available Since there are not experimental data over the whole range of x-Bjorken variable, that is, 0
The Functional-Analytic Properties of the Limit q-Bernstein Operator
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Sofiya Ostrovska
2012-01-01
Full Text Available The limit q-Bernstein operator Bq, 0Bernstein operator has been widely under scrutiny, and it has been shown that Bq is a positive shape-preserving linear operator on C[0,1] with ∥Bq∥=1. Its approximation properties, probabilistic interpretation, eigenstructure, and impact on the smoothness of a function have been examined. In this paper, the functional-analytic properties of Bq are studied. Our main result states that there exists an infinite-dimensional subspace M of C[0,1] such that the restriction Bq|M is an isomorphic embedding. Also we show that each such subspace M contains an isomorphic copy of the Banach space c0.
Erstnachweis von Taiwania, Cryptomeria und Liquidambar aus dem Bitterfelder und Baltischen Bernstein
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H. Jähnichen
1998-01-01
Full Text Available Aus dem untermiozänen Bernstein von Bitterfeld (Sachsen-Anhalt werden erstmalig ein strukturzeigender Zweig von Taiwania schaeferi, ein isoliertes Nadel-Fragment von Cryptomeria sp. sowie ein Fruchtstand von Liquidambar europaea beschrieben. Außerdem muß “Widdringtonites oblongifolius” (Goeppert & Menge Caspary & Klebs 1906/07 pro parte aus dem obereozänen Baltischen Bernstein nach morphologisch-anatomischen Merkmalskomplexen ebenfalls zu Taiwania schaeferi gestellt werden. “Enormicutis eoconferta” — aff. Cryptomeria spec. (Schneider 1986 aus der obereozänen Braunkohle von Nordwestsachsen muß nach morphologisch-anatomischen Details zu Athrotaxis couttsiae (Heer Gardner revidiert werden. First record of Taiwania, Cryptomeria and Liquidambar from Bitterfeld and Baltic amber A structure-bearing twig of Taiwania schaeferi, an isolated needle-fragment of Cryptomeria spec. as also an aggregate fruit of Liquidambar europaea are firstly described from the Lower Miocene amber of Bitterfeld (Saxony-Anhalt. Moreover “Widdringtonites oblongifolius” (Goeppert & Menge Caspary & Klebs 1906/07 p.p. from the Upper Eocene Baltic amber after morphological-anatomical features must be also assigned to Taiwania schaeferi. “Enormicutis eoconferta” — aff. Cryptomeria sp. (Schneider 1986 from the Upper Eocene brown-coal of North Western Saxony after morphological-anatomical details must be revised to Athrotaxis couttsiae (Heer Gardner. doi:10.1002/mmng.19980010112
McLean, Monica; Abbas, Andrea; Ashwin, Paul
2013-01-01
This paper illustrates how critical use of Basil Bernstein's theory illuminates the mechanisms by which university knowledge, curriculum and pedagogy both reproduce and interrupt social inequalities. To this end, empirical examples are selected from the findings of the ESRC-funded project "Pedagogic Quality and Inequality in University First…
Leaton Gray, Sandra
2017-01-01
This article discusses how the introduction of technology has led to a fundamental shift in the relationship between education and time. As a means of analysing the extent of such changes on pupils from different backgrounds, I use Bernstein's "conditions for democracy" as a framework for evaluating the impact new understandings of time…
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M. Raghunadh Acharya
2009-12-01
Full Text Available A new quadrature formula has been proposed which uses modified weight functions derived from those of ‘Bernstein Polynomial’ using a ‘Two-Phase Modification’ therein. The quadrature formula has been compared empirically with the simple method of numerical integration using the well-known “Bernstein Operator”. The percentage absolute relative errors for the proposed quadrature formula and that with the “Bernstein Operator” have been computed for certain selected functions, with different number of usual equidistant node-points in the interval of integration~ [0, 1]. It has been observed that both of the proposed modified quadrature formulae, respectively after the ‘Phase-I’ and after the ‘Phases-I & II’ of these modifications, produce significantly better results than that using, simply, the “Bernstein Operator”. Inasmuch as the proposed “Two-Phase Improvement” is available iteratively again-and-again at the end of the current iteration, the proposed improvement algorithm, which is ‘Computerizable’, is an “Iterative-Algorithm”, leading to more-and-more efficient “Quadrature-Operator”, till we are pleased!
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Guo Feng
2008-01-01
Full Text Available Abstract We consider the classes of periodic functions with formal self-adjoint linear differential operators , which include the classical Sobolev class as its special case. With the help of the spectral of linear differential equations, we find the exact values of Bernstein -width of the classes in the for .
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郭顺生; 刘丽霞; 宋占杰
2000-01-01
The purpose of this paper is to introduce ω2(x)3(f, t)z,β, and use it to prove the Steckin-Marchaud-type inequalities for Bernstein-Kantorovich Polynomials:ω2(x)3{f,(ψ)1-2(x)/√n}α1β≤C1/0＃(x)∑3-2≤│B:f-f│0 where 0≤λ≤1, 0≤α≤2, 0≤β≤2, n∈N.(ψ)(x)=√x(1-x),│f │0=SUP r∈(0,1)││(ψ)(x)x(2-3)-θf(x)││,B(x)n(f,x)=n∑2-0Pn,n(x)(n+1)x-1√x+1 (x)/(n+1)f(t)dt,P0,i(x)={n k}xk(1-x)n-k,ω23(ψ)(f,t)α,β=SUP α＜4≤1││(ψ)(2-α)(1-x)-θ(x)△kx1f(x)│,x,x ±h(ψ)2∈[0,1]│,and △2h(ψ)2f(x)=f(x+h(ψ)2)-2f(x)+f(x-h(ψ)2).
Daniel Frandji, Philippe Vitale, Actualité de Basil Bernstein. Savoir, pédagogie et société
Giraud, Frédérique
2011-01-01
Des travaux de Basil Bernstein, ce sont les premiers, notamment les études réunies dans Langages et classes sociales, qui sont les plus connus. Si l'on sait que la question clef dans ce travail est de comprendre comment se produisent les inégalités scolaires statistiquement observées, dans une perspective sociolinguistique, on ignore le plus souvent que Bernstein a étendu son domaine d'investigation empirique au procès social d'apprentissage dans son ensemble. Actualité de Basil Bernstein. S...
X-ray analysis of electron Bernstein wave heating in MST
Seltzman, A. H.; Anderson, J. K.; DuBois, A. M.; Almagri, A.; Forest, C. B.
2016-11-01
A pulse height analyzing x-ray tomography system has been developed to detect x-rays from electron Bernstein wave heated electrons in the Madison symmetric torus reversed field pinch (RFP). Cadmium zinc telluride detectors are arranged in a parallel beam array with two orthogonal multi-chord detectors that may be used for tomography. In addition a repositionable 16 channel fan beam camera with a 55° field of view is used to augment data collected with the Hard X-ray array. The chord integrated signals identify target emission from RF heated electrons striking a limiter located 12° toroidally away from the RF injection port. This provides information on heated electron spectrum, transport, and diffusion. RF induced x-ray emission from absorption on harmonic electron cyclotron resonances in low current (<250 kA) RFP discharges has been observed.
Integration of posture and movement: contributions of Sherrington, Hess, and Bernstein.
Stuart, Douglas G
2005-01-01
Neural mechanisms that integrate posture with movement are widespread throughout the central nervous system (CNS), and they are recruited in patterns that are both task- and context-dependent. Scientists from several countries who were born in the 19th century provided essential groundwork for these modern-day concepts. Here, the focus is on three of this group with each selected for a somewhat different reason. Charles Sherrington (1857-1952) had innumerable contributions that were certainly needed in the subsequent study of posture and movement: inhibition as an active coordinative mechanism, the functional anatomy of spinal cord-muscle connectivity, and helping set the stage for modern work on the sensorimotor cortex and the corticospinal tract. Sadly, however, by not championing the work of his trainee and collaborator, Thomas Graham Brown (1882-1965), he delayed progress on two key motor control mechanisms: central programming and pattern generation. Walter Hess (1881-1973), a self-taught experimentalist, is now best known for his work on CNS coordination of autonomic (visceral) and emotional behavior. His contributions to posture and movement, however, were also far-reaching: the coordination of eye movements and integration of goal-directed and "framework" (anticipatory set) motor behavior. Nikolai Bernstein (1896-1966), the quintessence of an interdisciplinary, self-taught movement neuroscientist, made far-reaching contributions that were barely recognized by Western workers prior to the 1960s. Today, he is widely praised for showing that the CNS's hierarchy of control mechanisms for posture and movement is organized hand-in-hand with distributed and parallel processing, with all three subject to evolutionary pressures. He also made important observations, like those of several previous workers, on the goal focus of voluntary movements. The contributions of Sherrington, Hess, and Bernstein are enduring. They prompt thought on the philosophical axioms that
Kinetic simulations of X-B and O-X-B mode conversion
Arefiev, A V; Köhn, A; Holzhauer, E; Shevchenko, V F; Vann, R G L
2015-01-01
We have performed fully-kinetic simulations of X-B and O-X-B mode conversion in one and two dimensional setups using the PIC code EPOCH. We have recovered the linear dispersion relation for electron Bernstein waves by employing relatively low amplitude incoming waves. The setups presented here can be used to study non-linear regimes of X-B and O-X-B mode conversion.
Directory of Open Access Journals (Sweden)
Mahmoud Paripour
2014-08-01
Full Text Available In this paper, the Bernstein polynomials are used to approximatethe solutions of linear integral equations with multiple time lags (IEMTL through expansion methods (collocation method, partition method, Galerkin method. The method is discussed in detail and illustrated by solving some numerical examples. Comparison between the exact and approximated results obtained from these methods is carried out
Row Sampling for Matrix Algorithms via a Non-Commutative Bernstein Bound
Magdon-Ismail, Malik
2010-01-01
We focus the use of \\emph{row sampling} for approximating matrix algorithms. We give applications to matrix multipication; sparse matrix reconstruction; and, \\math{\\ell_2} regression. For a matrix \\math{\\matA\\in\\R^{m\\times d}} which represents \\math{m} points in \\math{d\\ll m} dimensions, all of these tasks can be achieved in \\math{O(md^2)} via the singular value decomposition (SVD). For appropriate row-sampling probabilities (which typically depend on the norms of the rows of the \\math{m\\times d} left singular matrix of \\math{\\matA} (the \\emph{leverage scores}), we give row-sampling algorithms with linear (up to polylog factors) dependence on the stable rank of \\math{\\matA}. This result is achieved through the application of non-commutative Bernstein bounds. We then give, to our knowledge, the first algorithms for computing approximations to the appropriate row-sampling probabilities without going through the SVD of \\math{\\matA}. Thus, these are the first \\math{o(md^2)} algorithms for row-sampling based appro...
On the Effects of Social Class on Language Use: A Fresh Look at Bernstein's Theory
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Mohammad Aliakbari
2014-06-01
Full Text Available Basil Bernstein (1971 introduced the notion of the Restricted and the Elaborated code, claiming that working-class speakers have access only to the former but middle-class members to both. In an attempt to test this theory in the Iranian context and to investigate the effect of social class on the quality of students language use, we examined the use of six grammatical categories including noun, pronoun, adjective, adverb, preposition and conjunction by 20 working-class and 20 middle-class elementary students. The results of Chi-square operations at p<.05 corroborated Bernstein’s theory and showed that working- class students were different from middle-class ones in their language use. Being consistent with Bernstein’s theory, the results obtained for the use of personal pronouns indicated that middle-class students were more person-oriented and working-class ones more position-oriented. Findings, thus, call for teachers' deliberate attention to learners’ sociocultural variation to enhance mutual understanding and pragmatic success.
Observation of Electron Bernstein Wave Heating in the MST Reversed Field Pinch
Seltzman, Andrew; Anderson, Jay; Dubois, Ami; Almagri, Abdulgader; Nonn, Paul; McCollam, Karsten; Chapman, Brett; Goetz, John; Forest, Cary
2016-10-01
We report the first observation of electron Bernstein wave heating in the MST RFP. Similar to a high density stellarator, the RFP is inaccessible to electromagnetic ECRH. The plasma current and |B|operating range of MST allows a 5.5 GHz RF source (100kW, 4ms pulse) to heat on the fundamental and up to 4th harmonic EC resonances. With an x-ray diagnostic most sensitive to edge electrons located +12 degrees toroidally from the antenna, the measured emission is a strong function of predicted heating inside versus outside the Bt =0 reversal layer of the RFP. Measured during a scan of plasma current, distinct edges in a plot of emissivity versus predicted deposition layer align with the deposition layers crossing of this reversal layer and confirm EBW heating on the fundamental through 4th EC harmonic. Additional confirmation of the absorption location has been demonstrated by using auxiliary poloidal current drive to reduce electron diffusion rates and sweep the location of the Bt =0 surface across a static RF absorption location in RFP discharges. In these discharges EBW enhancement of the 15-40keV x-ray energies has been observed. Work supported by USDOE.
Mendoza-Torres, F.; Diaz-Viera, M. A.
2015-12-01
In many natural fractured porous media, such as aquifers, soils, oil and geothermal reservoirs, fractures play a crucial role in their flow and transport properties. An approach that has recently gained popularity for modeling fracture systems is the Discrete Fracture Network (DFN) model. This approach consists in applying a stochastic boolean simulation method, also known as object simulation method, where fractures are represented as simplified geometric objects (line segments in 2D and polygons in 3D). One of the shortcomings of this approach is that it usually does not consider the dependency relationships that may exist between the geometric properties of fractures (direction, length, aperture, etc), that is, each property is simulated independently. In this work a method for modeling such dependencies by copula theory is introduced. In particular, a nonparametric model using Bernstein copulas for direction-length fracture dependency in 2D is presented. The application of this method is illustrated in a case study for a fractured rock sample from a carbonate reservoir outcrop.
Steckin-Marchaud-type Inequalities in Connection with Bernstein-Kantorovich Polynomials
Institute of Scientific and Technical Information of China (English)
郭顺生; 刘丽霞; 宋占杰
2000-01-01
The purpose of this paper is to introduce ω2φλ(f, t )α.β, and use it to prove the Steckin-Marchaud-type inequalities for Bernstein-Kantorovich Polynomials: ω2φλ(f,φ1-λ(x)/√n)α,β≤C1/n∑k=1n‖Bk*f-f‖0. where 0≤λ≤1，0＜a＜a,0≤β≤2,n∈N, φ(x)=√x(1-x),‖f‖0=sup x∈(0,1){|φ(x)α(λ-1)-βf(x)|},Bn*(f,x)=∑k=0n Pn,k(x)(n+1)∫k/n-1k+1/n+1f(t)dt, Pn,k(x)=(n k)xk(1-x)n-k, ω2φλ(f,t)α,β=sup0＜h≤t{|φ(2-α)(1-λ)-β(x)△hφ2λf(x)|,x,x±hφλ∈[0,1]},and △hφ2λf(x)=f(x+hφλ)-2f(x)+f(x-hφλ).
Kalaee, Mohammad Javad; Katoh, Yuto
2016-07-01
One of the mechanisms for generating electromagnetic plasma waves (Z-mode and LO-mode) is mode conversion from electrostatic waves into electromagnetic waves in inhomogeneous plasma. Herein, we study a condition required for mode conversion of electrostatic waves propagating purely perpendicular to the ambient magnetic field, by numerically solving the full dispersion relation. An approximate model is derived describing the coupling between electrostatic waves (hot plasma Bernstein mode) and Z-mode waves at the upper hybrid frequency. The model is used to study conditions required for mode conversion from electrostatic waves (electrostatic electron cyclotron harmonic waves, including Bernstein mode) into electromagnetic plasma waves (LO-mode). It is shown that for mode conversion to occur in inhomogeneous plasma, the angle between the boundary surface and the magnetic field vector should be within a specific range. The range of the angle depends on the norm of the k vector of waves at the site of mode conversion in the inhomogeneous region. The present study reveals that inhomogeneity alone is not a sufficient condition for mode conversion from electrostatic waves to electromagnetic plasma waves and that the angle between the magnetic field and the density gradient plays an important role in the conversion process.
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Dumitru Baleanu
2013-01-01
Full Text Available We obtain the approximate analytical solution for the fractional quadratic Riccati differential equation with the Riemann-Liouville derivative by using the Bernstein polynomials (BPs operational matrices. In this method, we use the operational matrix for fractional integration in the Riemann-Liouville sense. Then by using this matrix and operational matrix of product, we reduce the problem to a system of algebraic equations that can be solved easily. The efficiency and accuracy of the proposed method are illustrated by several examples.
Energy Technology Data Exchange (ETDEWEB)
Ghizzo, A. [Institut Jean Lamour UMR 7163, Université de Lorraine, BP 239 F-54506 Vandoeuvre les Nancy (France)
2013-08-15
The stationary state with magnetically trapped particles is investigated at the saturation of the relativistic Weibel instability, within the “multiring” model in a Hamiltonian framework. The multistream model and its multiring extension have been developed in Paper I, under the assumption that the generalized canonical momentum is conserved in the perpendicular direction. One dimensional relativistic Bernstein-Greene-Kruskal waves with deeply trapped particles are addressed using similar mathematical formalism developed by Lontano et al.[Phys. Plasmas 9, 2562 (2002); Phys. Plasmas 10, 639 (2003)] using several streams and in the presence of both electrostatic and magnetic trapping mechanisms.
O dilema da Social-Democracia (2 - Reforma e Revolução: Bernstein, Rosa Luxemburgo e Karl Kautsky
Directory of Open Access Journals (Sweden)
Antonio Ozaí da Silva
2011-03-01
Full Text Available
Análise do “Bernstein-Debatte”, os argumentos revisionistas e a crítica de Rosa Luxemburgo e Karl Kautsky e os rumos da social-democracia alemã entre a prática reformista e a retórica revolucionária.
O dilema da Social-Democracia (2) - Reforma e Revolução: Bernstein, Rosa Luxemburgo e Karl Kautsky
Antonio Ozaí da Silva
2011-01-01
Análise do “Bernstein-Debatte”, os argumentos revisionistas e a crítica de Rosa Luxemburgo e Karl Kautsky e os rumos da social-democracia alemã entre a prática reformista e a retóric...
Unstable whistlers and Bernstein waves within the front of supercritical perpendicular shocks
Muschietti, Laurent; Lembege, Bertrand
2016-04-01
In supercritical shocks a significant fraction of ions is reflected at the steep shock ramp and carries a considerable amount of energy. The existence of reflected ions enables streaming instabilities to develop which are excited by the relative drifts between the populations of incoming ions, reflected ions, and electrons. The processes are fundamental to the transformation of directed kinetic energy into thermal energy, a tenet of shock physics. We model the particle distributions as a broad electron population and two ion populations, namely a core and a beam (representing the reflected ions) in order to investigate the kinetic instabilities possible under various wave propagation angles. Recently, assuming the ion beam is directed along the shock normal at 90° to the magnetic field Bo, we analyzed the linear dispersion properties by computing the full electromagnetic dielectric tensor [Muschietti and Lembege, AGU Fall meeting 2015]. Three types of waves were shown to be unstable: (1) Oblique whistlers with wavelengths about the ion inertia length which propagate toward upstream at angles about 50° to the magnetic field. Frequencies are a few times the lower-hybrid. The waves share many similarities to the obliquely propagating whistlers measured in detail by Polar [Hull et al., JGR 117, 2012]. (2) Quasi-perpendicular whistlers with wavelength covering a fraction of the electron inertia length which propagate toward downstream at angles larger than 80° to Bo. Frequencies are close to the lower-hybrid. (3) Bernstein waves with wavelengths close to the electron gyroradius which propagate toward upstream at angles within 5° of perpendicular to the magnetic field. Frequencies are close to the electron cyclotron. The waves have similarities to those reported by Wind and Stereo [Breneman et al., JGR 118, 2013; Wilson et al., JGR 115, 2010]. We will present electromagnetic 1D3V PIC simulations with predetermined propagation angles which illustrate the three types
McInnes, David; Murphy, Dean
2011-01-01
This paper seeks to make a theoretical and analytic intervention into the field of HIV-related education and prevention by applying the pedagogy framework of Basil Bernstein to a series of pedagogical devices developed and used in community-based programmes targeting gay men in Australia. The paper begins by outlining why it is such an…
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Castro, G.; Di Giugno, R.; Miracoli, R. [INFN- Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Universita degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S. Sofia 64, 95123 Catania (Italy); Mascali, D. [INFN- Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); CSFNSM, Viale A. Doria 6, 95125 Catania (Italy); Romano, F. P. [INFN- Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); CNR-IBAM Via Biblioteca 4, 95124 Catania (Italy); Celona, L.; Gammino, S.; Lanaia, D.; Ciavola, G. [INFN- Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Serafino, T. [CSFNSM, Viale A. Doria 6, 95125 Catania (Italy); Di Bartolo, F. [Universita di Messina, Ctr. da Papardo-Sperone, 98100 Messina (Italy); Gambino, N. [INFN- Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Universita degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S. Sofia 64, 95123 Catania (Italy); IET-Institute of Energy Technology, LEC-Laboratory for Energy Conversion, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich (Switzerland)
2012-02-15
A microwave discharge ion source (MDIS) operating at the Laboratori Nazionali del Sud of INFN, Catania has been used to compare the traditional electron cyclotron resonance (ECR) heating with an innovative mechanisms of plasma ignition based on the electrostatic Bernstein waves (EBW). EBW are obtained via the inner plasma electromagnetic-to-electrostatic wave conversion and they are absorbed by the plasma at cyclotron resonance harmonics. The heating of plasma by means of EBW at particular frequencies enabled us to reach densities much larger than the cutoff ones. Evidences of EBW generation and absorption together with X-ray emissions due to high energy electrons will be shown. A characterization of the discharge heating process in MDISs as a generalization of the ECR heating mechanism by means of ray tracing will be shown in order to highlight the fundamental physical differences between ECR and EBW heating.
1998-01-01
Conference "Internet, Web, What's next?" on 26 June 1998 at CERN: Mark Bernstein, Vice President of CNN Interactive, describes the impact of the Web on world media and predicts what we can expect as the next developments
Campbell, Ralph Ian
This analytic paper asks one question: How does Basil Bernstein's concept of the structure of pedagogic discourse (SPD) contribute to our understanding of the role of teacher-student interactions in science learning in the classroom? Applying Bernstein's theory of the SPD to an analysis of current research in science education explores the structure of Bernstein's theory as a tool for understanding the challenges and questions related to current concerns about classroom science learning. This analysis applies Bernstein's theory of the SPD as a heuristic through a secondary reading of selected research from the past fifteen years and prompts further consideration of Bernstein's ideas. This leads to a reevaluation of the categories of regulative discourse (RD) and instructional discourse (ID) as structures that frame learning environments and the dynamics of student-teacher interactions, which determine learning outcomes. The SPD becomes a simple but flexible heuristic, offering a useful deconstruction of teaching and learning dynamics in three different classroom environments. Understanding the framing interactions of RD and ID provides perspectives on the balance of agency and expectation, suggesting some causal explanations for the student learning outcomes described by the authors. On one hand, forms of open inquiry and student-driven instruction may lack the structure to ensure the appropriation of desired forms of scientific thinking. On the other hand, well-designed pathways towards the understanding of fundamental concepts in science may lack the forms of more open-ended inquiry that develop transferable understanding. Important ideas emerge about the complex dynamics of learning communities, the materials of learning, and the dynamic role of the teacher as facilitator and expert. Simultaneously, the SPD as a flexible heuristic proves ambiguous, prompting a reevaluation of Bernstein's organization of RD and ID. The hierarchical structure of pedagogic
The Convergence in Distribution Problems of the Random Bernstein Polynomial%随机Bernstein多项式的依分布收敛问题
Institute of Scientific and Technical Information of China (English)
于巍; 许爽爽; 姜雪
2013-01-01
利用随机的Bernstein多项式研究随机逼近问题具有一定的意义.借助弱收敛的概念,从分布函数的角度,讨论了随机Bernstein多项式依分布收敛问题.同时,与依概率收敛结果相比较,以此说明Bernstein多项式序列依分布收敛适用的范围更广.%It is very meaningful for studying the approximation problem of the random Bernstein polynomial.In this paper,the convergence in distribution problems of the random Bernstein polynomial is discussed in use of the weak convergence.Comparing with the convergence in probability,the convergence in distribution is more useful.
Voronovskaya-Type Formulas for ω, q-Bernstein Polynomials%ω,q-Bernstein多项式的Voronovskaya-型公式
Institute of Scientific and Technical Information of China (English)
江海新; 吴芸
2013-01-01
讨论了ω,q-Bernstein多项式的Voronovskaya-型公式及其收敛的饱和性.给出了当0＜q＜1,0≤ω≤1,f∈C1[0,1]时ω,q-Bernstein多项式的Voronovskaya-型公式.如果0＜ω,q＜1,f∈C1[0,1],则ω,q-Bernstein多项式的收敛阶为o(qn)当且仅当f(1-qk-1)-f(1-qk)/(1-qk-1)-(1-qk)=f'(1-qk),k=1,2,....还证明了如果f在[0,1]是凸的或者在(-ε,1+ε)(ε＞0)解析,则ω,q-Bernstein多项式的收敛阶为o(qn)当且仅当f是线性函数.%We discuss Voronovskaya-type formulas and saturation of convergence for ω,q-Bernstein polynomials. We give explicit formulas of Voronovskaya-type for ω,q-Bernstein polynomials for 0 0, then the rate of convergence for ω, q-Bernstein polynomials is o(qn) if and only if / is linear.
查尔斯·伯恩斯坦:挑战诗的理念%Charles Bernstein: Against the Idea of Poetry
Institute of Scientific and Technical Information of China (English)
利维·莱托
2007-01-01
This article is a foreword to a collection of poems and essays by Charles Bernstein in Finnish translation. The author, smartly and humorously, introduces his personal connection to Bernstein, via whom he was brought to a larger new poetry community. To the author, Bernstein's poetry is wildly individual, anti-communal, and against the very idea of poetry. The fruitful way to approach most of Charles Bernstein's poems is to see them as interventions in the field of poetry, as they always react against a particular idealization. Directly related to his two great fellow-Americans, Walt Whitman and Allen Ginsberg, Bernstein's poetry has a note of certain generalized, but always intellectually controlled sorrow. Having a constant feature of Bernsteinian prosody, his later poems are prevalent with a sense of transcendental utopianism.%本文是芬兰语版《伯恩斯坦诗文选集》前言,作者简要介绍了他个人与美国语言派诗人伯恩斯坦的交往及由此他步入的广阔的新诗领域.作者认为,伯恩斯坦的诗独具个性,一反常规,是对传统诗歌理念的反叛.要欣赏伯恩斯坦的诗最有效的方法是将他的诗看成是诗歌领域的干预活动,因为他的诗从来就是对某一理想化的诗歌范式的反动.伯恩斯坦的诗歌与惠特曼和金斯堡的诗有着直接的关联,但他的诗有着伯恩斯坦式的特别韵律,内蕴了一丝总被理智钳制的忧伤.他最近的诗还弥漫着一种超验的乌托邦情怀.
Full wave simulations of fast wave mode conversion and lower hybrid wave propagation in tokamaks
DEFF Research Database (Denmark)
Wright, J.C.; Bonoli, P.T.; Brambilla, M.;
2004-01-01
Fast wave (FW) studies of mode conversion (MC) processes at the ion-ion hybrid layer in toroidal plasmas must capture the disparate scales of the FW and mode converted ion Bernstein and ion cyclotron waves. Correct modeling of the MC layer requires resolving wavelengths on the order of k(perpendi......Fast wave (FW) studies of mode conversion (MC) processes at the ion-ion hybrid layer in toroidal plasmas must capture the disparate scales of the FW and mode converted ion Bernstein and ion cyclotron waves. Correct modeling of the MC layer requires resolving wavelengths on the order of k......). Two full wave codes, a massively-parallel-processor (MPP) version of the TORIC-2D finite Larmor radius code [M. Brambilla, Plasma Phys. Controlled Fusion 41, 1 (1999)] and also an all orders spectral code AORSA2D [E. F. Jaeger , Phys. Plasmas 9, 1873 (2002)], have been developed which for the first......)] to gain new understanding into the nature of FWMC in tokamaks. The massively-parallel-processor version of TORIC is also now capable of running with sufficient resolution to model planned lower hybrid range of frequencies experiments in the Alcator C-Mod. (C) 2004 American Institute of Physics....
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Mateus Casanova dos Santos
2010-12-01
Full Text Available O presente artigo é um estudo de caso investigativo de caráter participante e descritivo, a partir da vivência pedagógica no disparador de aprendizagem Simulação em Enfermagem, do segundo semestre do primeiro ciclo da graduação da Faculdade de Enfermagem (FEn da Universidade Federal de Pelotas (UFPel, onde se desenvolve a simulação clínica de semiologia e semiotécnica em Enfermagem. O objetivo é estudar a recontextualização da prática pedagógica da Simulação com base em teorizações do sociólogo da educação Basil Bernstein, contribuindo para o processo de aperfeiçoamento do planejamento de ensino e, especialmente, da avaliação deste disparador de aprendizagem. A partir das reflexões deste estudo, observa-se a teorização de Bernstein como uma potente ferramenta semiológica das práticas pedagógicas, a qual contribui para o planejamento e análise do dispositivo pedagógico curricular.Este artículo es un caso de estudio de carácter descriptivo y de investigación participante, desde la experiencia educativa de aprendizaje en el gatillo Simulación en Enfermería, de la segunda mitad del primer ciclo de la Escuela Enfermería (FEN de la Universidade Federal de Pelotas (UFPel donde se desarrolla la simulación de la semiología clínica y la semiótica en Enfermería. El objetivo es estudiar la recontextualización de la práctica pedagógica de teorías basadas en la simulación del sociólogo de la educación Basil Bernstein, contribuyendo al proceso de mejora de la educación, planificación y aprendizaje, especialmente la evaluación de gatillo. De las reflexiones de este estudio, existe la teoría de Bernstein como una poderosa herramienta de semiótica prácticas pedagógicas, lo que contribuye a la planificación y el análisis de dispositivos educativos curriculares.This article is a case study of investigative and descriptive participant character, from the educational experience of learning in the trigger
Enhanced loss of fusion products during mode conversion heating in TFTR
Energy Technology Data Exchange (ETDEWEB)
Darrow, D.S.; Majeski, R.; Fisch, N.J.; Heeter, R.F.; Herrmann, H.W.; Herrmann, M.C.; Zarnstorff, M.C.; Zweben, S.J.
1995-07-01
Ion Bernstein waves (IBWS) have been generated by mode conversion of ion cyclotron range of frequency (ICRF) fast waves in TFTR. The loss rate of fusion products in these discharges can be large, up to 10 times the first orbit loss rate. The losses are observed at the passing/trapped boundary, indicating that passing particles are being moved onto loss orbits either by increase of their v{perpendicular} due to the wave, by outward transport in minor radius, or both. The lost particles appear to be DD fusion produced tritons heated to {approximately}1.5 times their birth energy.
Yamaguchi, Yoshiyuki Y
2011-07-01
Traveling clusters are ubiquitously observed in the Hamiltonian mean-field model for a wide class of initial states, which are not predicted to become spatially inhomogeneous states by nonequilibrium statistical mechanics and by nonlinear Landau damping. To predict such a cluster state from a given initial state, we combine nonequilibrium statistical mechanics and a construction method of Bernstein-Greene-Kruskal (BGK) waves with the aid of phenomenological assumptions. The phenomenological theory is partially successful, and the theoretically constructed cluster states are in good agreement with N-body simulations. Robustness of the theory is also discussed for unsuccessful initial states.
On a New Family of Trigonometric Summation Polynomials of Bernstein Type%关于一类新的Bernstein型三角求和多项式
Institute of Scientific and Technical Information of China (English)
袁学刚; 何甲兴
2006-01-01
A new family of trigonometric summation polynomials, Gn,r(f; θ), of Bernstein type is constructed. In contrast to other trigonometric summation polynomials, the convergence properties of the new polynomials are superior to others.It is proved that Gn,r(f; θ) converges to arbitrary continuous functions with period 2π uniformly on (-∞, +∞) as n →∞. In particular, Gn,r(f; θ) has the best convergence order, and its saturation order is 1/n2r+4.
Dalnaja razminka / Boris Bernstein
Bernštein, Boriss, 1924-
2003-01-01
Professor Boris Bernshtein meenutab kunstipoliitilist skandaali Vladimir Voroshilovi (tol ajal Kalmanovitsh) diplomitöö kaitsmisel nõukogudeaegses Eesti Kunstiinstituudis. Vladimir Voroshilov on populaarse telemängu "Mis? Kus? Millal?" looja. Kunstiajaloolase mälestusteartikkel poliitilisest õhustikust nõukogudeaegsetes kunsti juhtivates ringkondades ilmub tervikuna ajakirjas "Tallinn"
Dalnaja razminka / Boris Bernstein
Bernštein, Boriss, 1924-
2003-01-01
Kunstipoliitilisest skandaalist Vladimir Voroshilovi (tol ajal Kalmanovitsh) diplomitöö kaitsmisel nõukogudeaegses Eesti Kunstiinstituudis. Vladimir Voroshilov on populaarse telemängu "Mis? Kus? Millal?" looja
Uvidet heruvima / Boris Bernstein
Bernštein, Boriss, 1924-
2006-01-01
Inglite kujundi loomisest euroopalike traditsioonide baasil. Inglite kujutamine Euroopa kunstis. Vaadeldud Jean Fouquet, Benozzo Gozzoli, Raffaeli, Luigi Bernini, Aleksandr Ivanovi, Alek Rapoporti töid
Energy Technology Data Exchange (ETDEWEB)
Kniehl, B.A. [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Maniatis, M. [Heidelberg Univ. (Germany). Inst. fuer Theoretische Physik; Weber, M.M. [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Muenchen (Germany)
2010-09-15
The discovery of charged Higgs bosons is of particular importance, since their existence is predicted by supersymmetry and they are absent in the Standard Model (SM). If the charged Higgs bosons are too heavy to be produced in pairs at future linear colliders, single production associated with a top and a bottom quark is enhanced in parts of the parameter space. We present the next-to-leading-order calculation in supersymmetric QCD within the minimal supersymmetric SM (MSSM), completing a previous calculation of the SM-QCD corrections. In addition to the usual approach to perform the loop integration analytically, we apply a numerical approach based on the Bernstein-Tkachov theorem. In this framework, we avoid some of the generic problems connected with the analytical method. (orig.)
Peng, Xinhua; Zhu, Xiwen; Fang, Ximing; Feng, Mang; Liu, Maili; Gao, Kelin
2004-02-22
A quantum circuit is introduced to describe the preparation of a labeled pseudo-pure state by multiplet-component excitation scheme which has been experimentally implemented on a 4-qubit nuclear magnetic resonance quantum processor. Meanwhile, we theoretically analyze and numerically investigate the low-power selective single-pulse implementation of a controlled-rotation gate, which manifests its validity in our experiment. Based on the labeled pseudo-pure state prepared, a 3-qubit Bernstein-Vazirani algorithm has been experimentally demonstrated by spectral implementation. The "answers" of the computations are identified from the split peak positions in the spectra of the observer spin, which are equivalent to projective measurements required by the algorithms.
A teoria dos códigos linguísticos de Basil Bernstein e a questão da modalidade oral da língua
Directory of Open Access Journals (Sweden)
Claudiana Nair Pothin Narzetti
2016-03-01
Full Text Available Este artigo apresenta resultados de pesquisa, de caráter bibliográfico e histórico, que consistiu em um retorno à teoria dos códigos restrito e elaborado, do sociólogo da linguagem Basil Bernstein, elaborada para caracterizar as diferenças entre a linguagem da classe trabalhadora e a linguagem da classe média, bem como para explicar as implicações do domínio desses códigos para o sucesso escolar dos estudantes. A pesquisa justificou-se por se tratar de um tema atual, isto é, a discrepância entre a linguagem falada pelo estudante das classes populares e a linguagem falada na escola, que está na origem, ainda hoje, de problemas de aprendizagem de língua portuguesa no Brasil. O objetivo foi retornar à teoria dos códigos e, confrontando-a com os recentes adquiridos da linguística, inquirir se essa teoria pode, atualmente, oferecer elementos para elaboração de metodologias de ensino de língua materna. O ponto de vista escolhido foi o das reflexões recentes, elaboradas no campo da linguística, sobre as modalidades oral e escrita da língua. A pesquisa constatou que os códigos dos quais tratou Bernstein podem ser concebidos como usos linguísticos na modalidade oral com diferentes níveis de formalidade. Nessa perspectiva, as reflexões do autor inglês suscitam um trabalho mais intenso com a produção de textos orais nas aulas de língua portuguesa.
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...
The Research Status Review of Bernstein Revisionism Theory%第二国际理论家伯恩施坦修正主义研究现状
Institute of Scientific and Technical Information of China (English)
熊久勋
2016-01-01
经济全球化和新自由主义盛行时代背景下，近年来国内一些学者试图为伯恩施坦修正主义正名，在意识形态领域造成了认识的“失重”。为回应当前西方各种改良社会主义思潮的冲击，追本溯源修正主义、改良主义始末发展显得势在必行。因此，全面认识国内外学术界关于伯恩施坦修正主义研究现状，正确揭示其对马克思主义的“背叛”和“修正”，对于我们廓清改良主义余毒，坚持马克思主义基本理论以及筑牢中国特色社会主义道路信念具有重大历史和现实意义。%Recent years,in the era trend of current economic globalization and the new liberalism,some domestic scholars try to defend for Bernstein Revisionism,which leads to the “weightlessness”in the realm of ideology.In response to the vast impact of current diverse western reformist socialism,tracing the foun-tainhead & development of revisionism is imperative.Therefore,a comprehensive understanding on Bern-stein Revisionism research status of domestic and foreign academic circles,rightly revealing its “betrayal”& “correction”of Marxism from all angles,is much important on history and reality for us to clear Revi-sionism vestiges,adhere to the basic theory of Marxism and build the road of Chinese characteristic social-ism.
Effects of Magnetic Shear on Ion-Cyclotron Modes.
Ganguli, Gurudas
Effects of Magnetic Shear on electrostatic Ion -Bernstein Modes (IBM) are examined. Shear affects the mode structure in 3 principal ways: (i) Local effect, (ii) Global effect and (iii) Orbital effect. The role of shear at the above three levels is investigated for IBM in general and in the context of parametric instability of two Ion-Bernstein modes by a magnetosonic wave in a multispecies plasma in particular. An improved marginal stability criterion is presented at Local and Global levels and the region where the Orbital effects are influential is defined and discussed. An electron drift relative to the ions is introduced parallel to the external magnetic field giving rise to Current Driven Ion Cyclotron Instability (CDICI). An improved theory of CDICI in a sheared magnetic field is given. For temperature ratios (tau) = T(,i)/T(,e) > .25, the imaginary part of the local dispersion relation, (as a function of k(,(PARLL)) (('x)), the local parallel wavevector), can be approximated by a parabola, while for weaker (tau) it can be approximated by a pair of straight lines; in each case a second order differential equation is solved for complex roots, (omega). Growth rates ((gamma)/(OMEGA)), are plotted against the square of the normalized pependicular wavevector ((TURN)b) for various values of shear, temperature ratios and electron drift strengths. The main effect of shear is to localize this instability in x-space around some x(,0) such that k(,(PARLL))('0) = ('s)k(,y)x(,0), (('s) being inverse shear length), corresponds to the ((gamma)/(OMEGA))(,max) in the absence of shear. Shear also reduces the growth rate in general: however, ((gamma)/(OMEGA)) for the b values away from the value corresponding to the maximum growth rate are affected more than those which are closer, thereby making the instability more coherent in b. Operator methods employing the Vlasov operator to obtain orbits and velocities in external magnetic fields are studied. Particle orbits and
Kinetic full wave analyses of O-X-B mode conversion of EC waves in tokamak plasmas
Fukuyama, Atsushi; Khan, Shabbir Ahmad; Igami, Hiroe; Idei, Hiroshi
2016-10-01
For heating and current drive in a high-density plasma of tokamak, especially spherical tokamak, the use of electron Bernstein waves and the O-X-B mode conversion were proposed and experimental observations have been reported. In order to evaluate the power deposition profile and the current drive efficiency, kinetic full wave analysis using an integral form of dielectric tensor has been developed. The incident angle dependence of wave structure and O-X-B mode conversion efficiency is examined using one-dimensional analysis in the major radius direction. Two-dimensional analyses on the horizontal plane and the poloidal plane are also conducted, and the wave structure and the power deposition profile are compared with those of previous analyses using ray tracing method and cold plasma approximation. This work is supported by JSPS KAKENHI Grant Number JP26630471.
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...
On The Anomalous Fast Ion Energy Diffusion in Toroidal Plasmas Due to Cavity Modes
Energy Technology Data Exchange (ETDEWEB)
N.N. Gorelenkov, N.J. Fisch and E. Fredrickson
2010-03-09
An enormous wave-particle diffusion coefficient along paths suitable for alpha channeling had been deduced in mode converted ion Bernstein wave experiments on Tokamak Fusion Test Reactor (TFTR) the only plausible explanation advanced for such a large diffusion coefficient was the excitation of internal cavity modes which induce particle diffusion along identical diffusion paths, but at much higher rates. Although such a mode was conjectured, it was never observed. However, recent detailed observations of high frequency compressional Alfven eigenmodes (CAEs) on the National Spherical torus Experiment (NSTX) indirectly support the existence of the related conjectured modes on TFTR. The eigenmodes responsible for the high frequency magnetic activity can be identified as CAEs through the polarization of the observed magnetic field oscillations in NSTX and through a comparison with the theoretically derived freuency dispersion relation. Here, we show how these recent observations of high frequency CAEs lend support to this explanation of the long-standing puzzle of anomalous fast ion energy diffusion on TFTR. The support of the conjecure that these internal modes could have caused the remarkable ion energy diffusion on TFTR carries significant and favorable implications for the possibilities in achieving the alpha channeling effect with small injected power in a tokamak reactor.
Jacobi-Bernstein基变换矩阵的一些性质%Some Properties of Jacobi-Bernstein Basis Transformation Matrices
Institute of Scientific and Technical Information of China (English)
白鸿武; 叶正麟; 王树勋; 王烈
2009-01-01
In computer-aided design,transformations among different forms of curves and surfaces are often required to carry out operations of degree-reduction of curves and surfaces and data exchanging between different geometric modeling systems.The errors of these transformations would depend on the condition numbers of the corresponding transformation matrices.For this reason,we studied some properties of Jacobi-Bernstein basis transformation matrices related to their condition numbers,and by computing the infinite norms of the transformation matrices and their inverse matrices,we obtained explicit upper bounds to these condition numbers.An example of applications of these condition numbers in CAGD was also provided.%在计算机辅助设计中,经常需要不同形式的曲线、曲面之间的变换,以完成曲线、曲面的降阶以及不同几何造型系统之间数据交换的操作,而这些变换的误差将依赖于相应变换矩阵的条件数.由于这个原因,我们研究了Jacobi-Bernstein矩阵的与其条件数相关的若干性质,而且通过计算变换矩阵与逆变换矩阵的无穷范数我们以显形式给出了这些条件数的上界.我们还给出了这些条件数在CAGD中的应用实例.
Institute of Scientific and Technical Information of China (English)
2016-01-01
“教育论述”理论是英国著名教育社会学家巴索·伯恩斯坦(Basil Bernstein)在晚年提出的重要思想理论,主要阐述了知识的生产、传递与再生产.伯恩斯坦“教育论述”理论对于我国当今的小学隐性课程的建设有一定的指导意义.
Institute of Scientific and Technical Information of China (English)
彭联勇; 王建军
2011-01-01
本文利用加权Ditzian-Totik光滑模证明Bernstein型算子的线性组合加权逼近阶估计和等价定理；同时,研究加Jacobi权下Benstein型算子的高阶导数与所逼近函数光滑性之间的关系.%Using the Ditzian-Totik moduli of smoothness equivalent approximation theorem with Jacobi weight for combinations of Bernstein operators is established in the paper. And the relation between higher derivatives of the operators and the smoothness of functions to be approximated is also obtained in the paper.
Mode conversion in three ion species ICRF heating scenario
Lin, Y.; Edlund, E.; Ennever, P.; Porkolab, M.; Wright, J.; Wukitch, S.
2016-10-01
Three-ion species ICRF heating has been studied on Alcator C-Mod and on JET. It has been shown to heat the plasma and generate energetic particles. In a typical three-ion scenario, the plasma consists of 60-70% D, 30-40% H and a trace level (1% or less) of 3He. This species mixture creates two hybrid resonances (D-3He and 3He-H) in the plasma, in the vicinity of the 3He IC resonance (on both sides). The fast wave can undergo mode conversion (MC) to ion Bernstein waves and ion cyclotron waves at the two hybrid resonances. A phase contrast imaging (PCI) system has been used to measure the RF waves in the three-ion heating experiment. The experimentally measured MC locations and the separating distance between the two MC regions help to determine the concentration of the three species. The PCI signal amplitudes for the RF waves are found to be sensitive to RF and plasma parameters, including PRF, Te, ne and also the species mix concentration. The parameter dependences found in the experiment will be compared with ICRF code simulations. Supported by USDoE Awards DE-FC02-99ER54512 and DE-FG02-94-ER54235.
Institute of Scientific and Technical Information of China (English)
程攀科; 周先东; 刘悦宁
2012-01-01
The cam was regulated by the Archimedes Helix in the CAGD/CAD system. The general formula of the vertex of polygon under the representation of the Archimedes Helix with Bernstein-like basis of order n was discussed, and the polygon was confirmed. The best order was confirmed on con- dition that the precision was sure by using the Area of Difference Method. The experiment had shown that using the Archimedes Helix with Bernstein-like basis of higher-order can construct the perfect cam. All of these reflected the important practical significance.%推出在n阶拟Bemstein基表示下的阿基米德螺线所得到的多边形顶点的通式，并确定多边形；同时在给定精度前提下，利用面积差值法来确定任意一段阿基米德螺线的拟Bern．stein基的最佳阶数。实例表明，运用高阶拟Bernstein基表示的阿基米德螺线构造的凸轮更加接近理想形状，具有实际意义。
Jelassi, H.; Viaris de Lesegno, B.; Pruvost, L.
2006-10-01
Nous avons étudié la photoassociation de 87Rb sous la limite 5S{1/2}+5P1/2 (D{1}), par spectroscopie de pertes d'atomes froids. Les spectres montrent les progressions vibrationnelles des trois séries d'états moléculaires attractifs 0_g-, 0_u+ et 1g convergents vers la limite 5S1/2+5P1/2. L'analyse de nos données utilise l'approche de Lu-Fano associé au modèle de LeRoy-Bernstein. Pour la série 0_g-, cette approche met en évidence un écart au modèle. Une amélioration de la formule de LeRoy-Bernstein permet de rendre compte des mesures expérimentales. Pour la série 0_u+(P1/2) avec la même méthode, on montre le couplage avec la série 0_u+(P3/2).
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.
Neutron Flux Measurements in an ICRF Mode Conversion Regime Heating Plasmas on HT-7
Institute of Scientific and Technical Information of China (English)
LI Xiao-Ling; WAN Bao-Nian; ZHONG Guo-Qiang; HU Li-Qun; LIN Shi-Yao; ZHANG Xin-Jun; ZANG Qing
2011-01-01
Ion cyclotron resonance heating experiments using antenna, in the high Reid side (HFS) have been carried out on HT-7 in different target plasmas. Unlike a standard-mode conversion heating scheme with dominant electron heating, anomalous ion heating and DD neutron fluxes higher than those estimated from thermal ions were observed in the present experiments with the ion-ion hybrid resonant layer near the center of plasma. The features of ion cyclotron range frequency (ICRF) antenna in HFS and experiments suggest that this is most probably due to the nonlinear 3/2 harmonic deuterium heating by the mode-converted ion Bernstein wave, which could produce a high energy tail on ion energy distribution.%Ion cyclotron resonance heating experiments using antenna in the high field side (HFS) have been carried out on HT-7 in different target plasmas.Unlike a standard-mode conversion heating scheme with dominant electron heating,anomalous ion heating and DD neutron fluxes higher than those estimated from thermal ions were observed in the present experiments with the ion-ion hybrid resonant layer near the center of plasma.The features of ion cyclotron range frequency (ICRF) antenna in HFS and experiments suggest that this is most probably due to the nonlinear 3/2 harmonic deuterium heating by the mode-converted ion Bernstein wave,which could produce a high energy tail on ion energy distribution.Neutron diagnostics have been applied in ion cyclotron range frequency (ICRF) plasmas on HT-7 for measurements of the fusion reaction product,which give a direct measure of the ICRF heating.The neutron emission is recorded by a 3He proportional counter,whose sensitive size is φ30 mm × 300 mm,gas pressure is 49.34 kPa and the responsibility to thermal neutrons is 133 cps/n.cm-2.s-1.It exploits large reaction cross sections and is therefore embedded in polythene moderators to thermalize the incident neutrons.
Institute of Scientific and Technical Information of China (English)
孙建安; 张涛锋; 陈继宇; 刘万海; 陶娜; 石玉仁
2011-01-01
采用修正Bernstein多项式作为基函数,使用Galerkin逼近,构造了数值求解KdV-Burgers方程的隐式格式.该格式具有很好的数值稳定性,能够有效处理长时间演化问题,数值解具有高精度.%An implicit scheme of solving numerical solution of KdV-Burgers' equation is constructed by applying modified Bernstein polynomials as basis function and Galerkin approximation. The scheme is of well numerical stability, and effective for long time evolution behavior. The numerical results are in well agreement with the exact solutions.
Volpe, F. A.; Choi, M.; Patel, Y.; Meneghini, O.
2013-10-01
We present initial two-dimensional full-wave modeling of an innovative diagnostic of the magnetic field vector as a function of the minor radius in the pedestal region. An angularly broad millimeter-wave beam of ordinary (O) polarization is obliquely injected in the magnetized plasma; part of it converts in the extraordinary (X) mode at the O-mode cutoff, the rest is reflected. The reflected beam pattern, measured with an array of receivers, contains information on the angular-dependent mode conversion, which contains information on the magnetic pitch angle at the cutoff. Measurements at various frequencies provide radially resolved measurements of pitch angle. The new technique proposed does not require the plasma to be an overdense emitter of Electron Bernstein Waves and is applicable whenever reflectometry is applicable. Simulations performed with the finite-element COMSOL Multiphysics code in ``DIII-D-like'' plasma slabs confirmed the presence of a minimum in reflectivity of an externally injected O-mode beam. The dependence of such reflectivity ``hole'' upon magnetic field is under study. Future inclusion of toroidal ripple, density and magnetic fluctuation effects, as well as possible extensions to a fully three-dimensional diagnostic of the magnetic field will be discussed. Current address: Imsol-X.
Theory of anomalous backscattering in second harmonic X-mode ECRH experiments
Gusakov, E. Z.; Popov, A. Yu.
2016-08-01
A quantitative model explaining generation of the anomalous backscattering signal in the second harmonic X-mode electron cyclotron resonance heating (ECRH) experiments at TEXTOR tokamak as a secondary nonlinear process which accompanies a primary low-threshold parametric decay instability (PDI) leading to excitation of two—upper hybrid (UH)—plasmons trapped in plasma is developed. The primary absolute PDI enhancing the UH wave fluctuations from the thermal noise level is supposed to be saturated due to a cascade of secondary low-threshold decays of the daughter UH wave leading to excitation of the secondary UH waves down-shifted in frequency and the ion Bernstein wave. A set of equations describing the cascade is derived and solved numerically. The results of numerical modelling are shown to be in agreement with the analytical estimations of the growth rate of the initial and secondary parametric decays and the saturation level. The generation of backscattering signal is explained by coupling of the daughter UH waves. The fine details of the frequency spectrum of the anomalously reflected extraordinary wave and the absolute value of the observed backscattering signal in the second harmonic X-mode ECRH experiments at TEXTOR are reproduced.
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.
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...
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.
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.
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
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.
Meneghini, Orso; Volpe, Francesco A.
2016-11-01
An innovative millimeter wave diagnostic is proposed to measure the local magnetic field and edge current as a function of the minor radius in the tokamak pedestal region. The idea is to identify the direction of minimum reflectivity at the O-mode cutoff layer. Correspondingly, the transmissivity due to O-X mode conversion is maximum. That direction, and the angular map of reflectivity around it, contains information on the magnetic field vector B at the cutoff layer. Probing the plasma with different wave frequencies provides the radial profile of B. Full-wave finite-element simulations are presented here in 2D slab geometry. Modeling confirms the existence of a minimum in reflectivity that depends on the magnetic field at the cutoff, as expected from mode conversion physics, giving confidence in the feasibility of the diagnostic. The proposed reflectometric approach is expected to yield superior signal-to-noise ratio and to access wider ranges of density and magnetic field, compared with related radiometric techniques that require the plasma to emit electron Bernstein waves. Due to computational limitations, frequencies of 10-20 GHz were considered in this initial study. Frequencies above the edge electron-cyclotron frequency (f > 28 GHz here) would be preferable for the experiment, because the upper hybrid resonance and right cutoff would lie in the plasma, and would help separate the O-mode of interest from spurious X-waves.
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...
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
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...
DEFF Research Database (Denmark)
Israelsen, Stine Møller
to implement a nonlinear chirp which is a first time demonstration. The results are modelled using coupled mode theory and it is shown that the conversion bandwidth may be increased more than four fold. In the final part of the thesis, imaging as a characterization tool for HOMs is considered. Three different......This PhD thesis considers higher order modes (HOMs) in optical fibers. That includes their excitation and characteristics. Within the last decades, HOMs have been applied both for space multiplexing in optical communications, group velocity dispersion management and sensing among others....... 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...
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.
Hardware Assisted ROP Detection Mode (HARD Mode)
2013-08-01
function call. The section of code to where a ROP attack jumps is called a “ gadget ” and a series of gadgets linked sequentially to achieve a result is...that page fault-based decision engine invocation is not effective . With HARD Mode, the goal was to develop a ROP detection mechanism which would protect...viewdoc/summary?doi=10.1.1.120.5702, 2008. [3] “Shacham, Page, et al.”. On the Effectiveness of Address-Space Randomization. In ACM Computer and
Institute of Scientific and Technical Information of China (English)
查尔斯·伯恩斯坦
2008-01-01
In recent years, the abstraction and non-referentiality of Language Poetry has given way to a more intertextual and intellectual poetry-a poetry that interrogates history and the literature of the past so as to come to a better understanding of the present. In his "thought opera" about the great critic Walter Benjamin, Charles Bernstein uses elaborate language games, literary echoes, citations, constraints, and "found text" to rethink the life and aesthetic of the deeply conflicted German intellectual, whose career was framed by the two World Wars. The libretto Shadowtime, which can be read independently of the music, presents both a loving but also ironic portrait of Benjamin-a character as deeply flawed as he is sympathetic. Bernstein's language, often drawn directly from specific Benjamin texts, like "Hashish at Marseilles," is elaborately deconstructed so as to produce a complex network of puns, paragrams, and aphorisms. But this "poem including history" is also very funny-full of wit and comedy so that it has broad audience appeal. It provides a paradigm for what is happening in avant-garde American poetry today: the use of intermedia, sound play, and semantically charged language that inherits many of the features of the Language movement but is more meditative and thought-provoking.%近年来,语言诗的抽象性与非指示性已经让位于一种更具有互文性和智性的诗歌,这种诗歌通过考问历史和历史上的文学以求对当下获得更好的理解.在关于两战期间德国伟大的批评家瓦尔特·本雅明的"思想歌剧"中,查尔斯·伯恩斯坦运用了精心制作的语言游戏、文学回声、引用、约束以及"发现的文本"来重新评论这位充满矛盾的德国学者的生平和美学观.即便独立于音乐之外进行阅读,该歌剧剧本深情而又不乏反讽地刻画出本雅明既有瑕疵又感人至深的人物性格.伯恩斯坦常常直接从本雅明的"马赛的麻药"等具体文本中提取
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...
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.
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....
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.
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…
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
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.
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…
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.
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.
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.
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.
Localized acoustic surface modes
Farhat, Mohamed; Chen, Pai-Yen; Bağcı, Hakan
2016-04-01
We introduce the concept of localized acoustic surface modes. 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.
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...
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.
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…
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...
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.
The semiparametric Bernstein-von Mises theorem
Bickel, P.J.; Kleijn, B.J.K.
2012-01-01
In a smooth semiparametric estimation problem, the marginal posterior for the parameter of interest is expected to be asymptotically normal and satisfy frequentist criteria of optimality if the model is endowed with a suitable prior. It is shown that, under certain straightforward and interpretable
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, ...
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.
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.
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.
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.
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.
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...
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).
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.
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...
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...
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.
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.
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.
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.
Mode selection in pulsating stars
Smolec, R
2013-01-01
In this review we focus on non-linear phenomena in pulsating stars the mode selection and amplitude limitation. Of many linearly excited modes only a fraction is detected in pulsating stars. Which of them and why (the problem of mode selection) and to what amplitude (the problem of amplitude limitation) are intrinsically non-linear and still unsolved problems. Tools for studying these problems are briefly discussed and our understanding of mode selection and amplitude limitation in selected groups of self-excited pulsators is presented. Focus is put on classical pulsators (Cepheids and RR Lyrae stars) and main sequence variables (delta Scuti and beta Cephei stars). Directions of future studies are briefly discussed.
Acoustic modes in fluid networks
Michalopoulos, C. D.; Clark, Robert W., Jr.; Doiron, Harold H.
Pressure and flow rate eigenvalue problems for one-dimensional flow of a fluid in a network of pipes are derived from the familiar transmission line equations. These equations are linearized by assuming small velocity and pressure oscillations about mean flow conditions. It is shown that the flow rate eigenvalues are the same as the pressure eigenvalues and the relationship between line pressure modes and flow rate modes is established. A volume at the end of each branch is employed which allows any combination of boundary conditions, from open to closed, to be used. The Jacobi iterative method is used to compute undamped natural frequencies and associated pressure/flow modes. Several numerical examples are presented which include acoustic modes for the Helium Supply System of the Space Shuttle Orbiter Main Propulsion System. It should be noted that the method presented herein can be applied to any one-dimensional acoustic system involving an arbitrary number of branches.
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.
Adaptive Structural Mode Control Project
National Aeronautics and Space Administration — M4 Engineering proposes the development of an adaptive structural mode control system. The adaptive control system will begin from a "baseline" dynamic model of the...
THE SPIRITUAL PRODUCTION MODE INNOVATION
Institute of Scientific and Technical Information of China (English)
肖柯
2016-01-01
The innovation of spiritual production mode is an eclectic open-ended project. Promoting innovation of spiritual production mode involves numerous intricate specific measures, including both the top-level design(macro-level) and the inno-vation of specific spiritual products (micro-level), complete with promotion of population quality and the regulation and gover-nance of spiritual products distribution, consumption and other aspects.
Breathing Modes in Dusty Plasma
Institute of Scientific and Technical Information of China (English)
王晓钢; 王爽; 潘秋惠; 刘悦; 贺明峰
2003-01-01
Acoustic breathing modes of dusty plasmas have been investigated in a cylindricalsystem with an axial symmetry. The linear wave solution and a "dispersion" relation were derived.It was found that in an infinite area, the mode is reduced to a "classical" dust acoustic wave inthe region away from the center. If the dusty plasma is confined in a finite region, however, thebreathing (or heart-beating) behavior would be found as observed in many experiments.
Rubble Mound Breakwater Failure Modes
DEFF Research Database (Denmark)
Burcharth, H. F.; Z., Liu
1995-01-01
The RMBFM-Project (Rubble Mound Breakwater Failure Modes) is sponsored by the Directorate General XII of the Commission of the European Communities under the Contract MAS-CT92- 0042, with the objective of contributing to the development of rational methods for the design of rubble mound breakwaters...... modes, plus development of related partial coefficients which make it possible to design according to preselected reliability levels. Due to limited space only the major activities are described....
Bound Modes in Dielectric Microcavities
Visser, P M; Lenstra, D
2002-01-01
We demonstrate how exactly bound cavity modes can be realized in dielectric structures other than 3d photonic crystals. For a microcavity consisting of crossed anisotropic layers, we derive the cavity resonance frequencies, and spontaneous emission rates. For a dielectric structure with dissipative loss and central layer with gain, the beta factor of direct spontaneous emission into a cavity mode and the laser threshold is calculated.
The evolution of transmission mode
Forbes, Mark R.; Hauffe, Heidi C.; Kallio, Eva R.; Okamura, Beth; Sait, Steven M.
2017-01-01
This article reviews research on the evolutionary mechanisms leading to different transmission modes. Such modes are often under genetic control of the host or the pathogen, and often in conflict with each other via trade-offs. Transmission modes may vary among pathogen strains and among host populations. Evolutionary changes in transmission mode have been inferred through experimental and phylogenetic studies, including changes in transmission associated with host shifts and with evolution of the unusually complex life cycles of many parasites. Understanding the forces that determine the evolution of particular transmission modes presents a fascinating medley of problems for which there is a lack of good data and often a lack of conceptual understanding or appropriate methodologies. Our best information comes from studies that have been focused on the vertical versus horizontal transmission dichotomy. With other kinds of transitions, theoretical approaches combining epidemiology and population genetics are providing guidelines for determining when and how rapidly new transmission modes may evolve, but these are still in need of empirical investigation and application to particular cases. Obtaining such knowledge is a matter of urgency in relation to extant disease threats. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’. PMID:28289251
Assembly modes of dragonfly wings.
Zhao, Hong-Xiao; Yin, Ya-Jun; Zhong, Zheng
2011-12-01
The assembly modes of dragonfly wings are observed through FEG-ESEM. Different from airplane wings, dragonfly wings are found to be assembled through smooth transition mode and global package mode. First, at the vein/membrane conjunctive site, the membrane is divided into upper and lower portions from the center layer and transited smoothly to the vein. Then the two portions pack the vein around and form the outer surface of the vein. Second, at the vein/spike conjunctive site, the vein and spike are connected smoothly into a triplet. Last, at the vein/membrane/spike conjunctive site, the membrane (i.e., the outer layer of the vein) transits smoothly to the spike, packs it around, and forms its outer layer. In short, the membrane looks like a closed coat packing the wing as a whole. The smooth transition mode and the global package mode are universal assembly modes in dragonfly wings. They provide us the references for better understanding of the functions of dragonfly wings and the bionic manufactures of the wings of flights with mini sizes.
Normal modes and mode transformation of pure electron vortex beams
Thirunavukkarasu, G.; Mousley, M.; Babiker, M.; Yuan, J.
2017-02-01
Electron vortex beams constitute the first class of matter vortex beams which are currently routinely produced in the laboratory. Here, we briefly review the progress of this nascent field and put forward a natural quantum basis set which we show is suitable for the description of electron vortex beams. The normal modes are truncated Bessel beams (TBBs) defined in the aperture plane or the Fourier transform of the transverse structure of the TBBs (FT-TBBs) in the focal plane of a lens with the said aperture. As these modes are eigenfunctions of the axial orbital angular momentum operator, they can provide a complete description of the two-dimensional transverse distribution of the wave function of any electron vortex beam in such a system, in analogy with the prominent role Laguerre-Gaussian (LG) beams played in the description of optical vortex beams. The characteristics of the normal modes of TBBs and FT-TBBs are described, including the quantized orbital angular momentum (in terms of the winding number l) and the radial index p>0. We present the experimental realization of such beams using computer-generated holograms. The mode analysis can be carried out using astigmatic transformation optics, demonstrating close analogy with the astigmatic mode transformation between LG and Hermite-Gaussian beams. This article is part of the themed issue 'Optical orbital angular momentum'.
Banach 球中的Bernstein 多项式%Bernstein Polynomials in the Banach Ball
Institute of Scientific and Technical Information of China (English)
黄迅成; 许晓宁
2008-01-01
从估计Bernstein多项式Bn(f)到f的距离入手,证明了LIP([0,1])中所有的Bernstein多项式Bn(f)都落在以f为球心,以2‖f‖为半径的Banach球中.这个有趣的结论无疑对深入研究Bernstein多项式在逼近论中的作用是有益的.
Mode characteristics of hollow core Bragg fiber
Institute of Scientific and Technical Information of China (English)
Minning Ji; Zhidong Shi; Qiang Guo
2005-01-01
Analytical expression to calculate propagation constant and mode field of the hollow core Bragg fiber is derived. Numerical results are presented. It is shown that the fundamental mode of the hollow core Bragg fiber is circularly symmetric TE01 mode with no polarization degeneracy, while the higher order mode may be HE11, TM01, or TE02 etc.. This property is different from conventional optical fiber that its fundamental mode is the linearly polarized HE11 mode and is polarization degeneracy.
The effective degeneracy of protein normal modes.
Na, Hyuntae; Song, Guang
2016-05-12
Normal modes are frequently computed and used to portray protein dynamics and interpret protein conformational changes. In this work, we investigate the nature of normal modes and find that the normal modes of proteins, especially those at the low frequency range (0-600 cm(-1)), are highly susceptible to degeneracy. Two or more modes are degenerate if they have the same frequency and consequently any orthogonal transformation of them also is a valid representation of the mode subspace. Thus, degenerate modes can no longer characterize unique directions of motions as regular modes do. Though the normal modes of proteins are usually of different frequencies, the difference in frequency between neighboring modes is so small that, under even slight structural uncertainty that unavoidably exists in structure determination, it can easily vanish and as a result, a mode becomes effectively degenerate with its neighboring modes. This can be easily observed in that some modes seem to disappear and their matching modes cannot be found when the structure used to compute the modes is modified only slightly. We term this degeneracy the effective degeneracy of normal modes. This work is built upon our recent discovery that the vibrational spectrum of globular proteins is universal. The high density of modes observed in the vibrational frequency spectra of proteins renders their normal modes highly susceptible to degeneracy, under even the smallest structural uncertainty. Indeed, we find the degree of degeneracy of modes is proportional to the density of modes in the vibrational spectrum. This means that for modes at the same frequency, degeneracy is more severe for larger proteins. Degeneracy exists also in the modes of coarse-grained models, but to a much lesser extent than those of all-atom models. In closing, we discuss the implications of the effective degeneracy of normal modes: how it may significantly affect the ways in which normal modes are used in various normal modes
Challenges in higher order mode Raman amplifiers
DEFF Research Database (Denmark)
Rottwitt, Karsten; Nielsen, Kristian; Friis, Søren Michael Mørk;
2015-01-01
A higher order Raman amplifier model that take random mode coupling into account ispresented. Mode dependent gain and signal power fluctuations at the output of the higher order modeRaman amplifier are discussed......A higher order Raman amplifier model that take random mode coupling into account ispresented. Mode dependent gain and signal power fluctuations at the output of the higher order modeRaman amplifier are discussed...
Exotic decay transition from cluster mode to fission mode
Santhosh, K P
2002-01-01
Exotic decay of some heavy nuclei with Z >= 100 formed in heavy ion 'cold fusion' reaction were studied taking interacting barrier consisting of Coulomb and proximity potential. Calculated half-life time shows that some modes of decay are well within the present upper limit for measurements (T sub 1 sub / sub 2 < 10 sup 3 sup 0 s). Cluster formation probabilities are calculated for different clusters within fission model. It is found that transition from cluster mode to fission mode take place at mass of the cluster, A sub 2 = 20 in exotic decay which is comparable with the value A sub 2 = 16 of Shanmugam et al based on cubic plus Yukawa plus exponential model (CYEM). (author)
Audit mode change, corporate governance
Directory of Open Access Journals (Sweden)
Limei Cao
2015-12-01
Full Text Available This study investigates changes in audit strategy in China following the introduction of risk-based auditing standards rather than an internal control-based audit mode. Specifically, we examine whether auditors are implementing the risk-based audit mode to evaluate corporate governance before distributing audit resources. The results show that under the internal control-based audit mode, the relationship between audit effort and corporate governance was weak. However, implementation of the risk-based mode required by the new auditing standards has significantly enhanced the relationship between audit effort and corporate governance. Since the change in audit mode, the Big Ten have demonstrated a significantly better grasp of governance risk and allocated their audit effort accordingly, relative to smaller firms. The empirical evidence indicates that auditors have adjusted their audit strategy to meet the regulations, risk-based auditing is being achieved to a degree, reasonable and effective corporate governance helps to optimize audit resource allocation, and smaller auditing firms in particular should urgently strengthen their risk-based auditing capability. Overall, our findings imply that the mandatory switch to risk-based auditing has optimized audit effort in China.
X-mode HF Pump-induced Phenomena at High Heater Frequencies in the High Latitude Ionosphere F-region
Blagoveshchenskaya, N. F.; Borisova, T. D.; Kalishin, A. S.; Yeoman, T. K.; Häggström, I.
2015-12-01
Experimental results concentrating on X-mode HF-induced phenomena in the high latitude ionosphere F region are discussed. Experiments have been carried out at the HF Heating facility at Tromsø with an effective radiated power of 450 - 650 MW at high heater frequencies of 6.2 - 8.0 MHz. Multi-instriment diagnostics included the European Incoherent Scatter (EISCAT) UHF radar at 931 MHz at Tromsø, the Finland CUTLASS (Co-operative UK Twin Located Auroral Sounding System) radar, the stimulated electromagnetic emission (SEE) equipment at Tromsø, and the HF receiver near St. Petersburg for the observations of narrow band SEE features. The key parameter considered is the ratio between the heater frequency and critical frequency of the F2 layer (fH/foF2). We have analyzed the behaviors of small-scale artificial field-aligned irregularities (FAIs) and HF-enhanced plasma and ion lines (HFPLs and HFILs) depending on the pump proximity to the critical frequency. It was shown that the HFPLs and HFILs coexisted with FAIs throughout the whole heater pulse when fH/foF2 > 1 as well as fH/foF2 ≤ 1. It is indicative that parametric decay instability was not quenched by fully developed FAIs. The comparison between contrasting O/X mode HF-induced phenomena, when the heater frequency is below or near the critical frequency of F2 layer, is made. It was found that an X-mode HF pumping is able to excite different narrow band spectral components in the SEE spectra (within 1 kHz of pump frequency), such as ion acoustic, electrostatic ion cyclotron, and electrostatic ion cyclotron harmonic waves (otherwise known as neutralized ion Bernstein waves) observed at a long distance from the HF Heating facility. It was suggested that these spectral component can be attributed to the stimulated Brillion scatter (SBS) process. The results obtained show that an X-polarized electromagnetic wave scattered by SBS can propagate more than one thousand km without significant attenuation.
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.
Macroscopic (and microscopic massless modes
Directory of Open Access Journals (Sweden)
Michael C. Abbott
2015-05-01
Full Text Available We study certain spinning strings exploring the flat directions of AdS3×S3×S3×S1, the massless sector cousins of su(2 and sl(2 sector spinning strings. We describe these, and their vibrational modes, using the D(2,1;α2 algebraic curve. By exploiting a discrete symmetry of this structure which reverses the direction of motion on the spheres, and alters the masses of the fermionic modes s→κ−s, we find out how to treat the massless fermions which were previously missing from this formalism. We show that folded strings behave as a special case of circular strings, in a sense which includes their mode frequencies, and we are able to recover this fact in the worldsheet formalism. We use these frequencies to calculate one-loop corrections to the energy, with a version of the Beisert–Tseytlin resummation.
Quasiadiabatic modes from viscous inhomogeneities
Giovannini, Massimo
2016-01-01
The viscous inhomogeneities of a relativistic plasma determine a further class of entropic modes whose amplitude must be sufficiently small since curvature perturbations are observed to be predominantly adiabatic and Gaussian over large scales. When the viscous coefficients only depend on the energy density of the fluid the corresponding curvature fluctuations are shown to be almost adiabatic. After addressing the problem in a gauge-invariant perturbative expansion, the same analysis is repeated at a non-perturbative level by investigating the nonlinear curvature inhomogeneities induced by the spatial variation of the viscous coefficients. It is demonstrated that the quasiadiabatic modes are suppressed in comparison with a bona fide adiabatic solution. Because of its anomalously large tensor to scalar ratio the quasiadiabatic mode cannot be a substitute for the conventional adiabatic paradigm so that, ultimately, the present findings seems to exclude the possibility of a successful accelerated dynamics solely...
Leaky Modes of Dielectric Cavities
Mansuripur, Masud; Jakobsen, Per
2016-01-01
In the absence of external excitation, light trapped within a dielectric medium generally decays by leaking out (and also by getting absorbed within the medium). We analyze the leaky modes of a parallel-plate slab, a solid glass sphere, and a solid glass cylinder, by examining those solutions of Maxwell's equations (for dispersive as well as non-dispersive media) which admit of a complex-valued oscillation frequency. Under certain circumstances, these leaky modes constitute a complete set into which an arbitrary distribution of the electromagnetic field residing inside a dielectric body can be expanded. We provide completeness proofs, and also present results of numerical calculations that illustrate the relationship between the leaky modes and the resonances of dielectric cavities formed by a simple parallel-plate slab, a glass sphere, and a glass cylinder.
Nonlinear dynamics by mode superposition
Energy Technology Data Exchange (ETDEWEB)
Nickell, R.E.
1976-01-01
A mode superposition technique for approximately solving nonlinear initial-boundary-value problems of structural dynamics is discussed, and results for examples involving large deformation are compared to those obtained with implicit direct integration methods such as the Newmark generalized acceleration and Houbolt backward-difference operators. The initial natural frequencies and mode shapes are found by inverse power iteration with the trial vectors for successively higher modes being swept by Gram-Schmidt orthonormalization at each iteration. The subsequent modal spectrum for nonlinear states is based upon the tangent stiffness of the structure and is calculated by a subspace iteration procedure that involves matrix multiplication only, using the most recently computed spectrum as an initial estimate. Then, a precise time integration algorithm that has no artificial damping or phase velocity error for linear problems is applied to the uncoupled modal equations of motion. Squared-frequency extrapolation is examined for nonlinear problems as a means by which these qualities of accuracy and precision can be maintained when the state of the system (and, thus, the modal spectrum) is changing rapidly. The results indicate that a number of important advantages accrue to nonlinear mode superposition: (a) there is no significant difference in total solution time between mode superposition and implicit direct integration analyses for problems having narrow matric half-bandwidth (in fact, as bandwidth increases, mode superposition becomes more economical), (b) solution accuracy is under better control since the analyst has ready access to modal participation factors and the ratios of time step size to modal period, and (c) physical understanding of nonlinear dynamic response is improved since the analyst is able to observe the changes in the modal spectrum as deformation proceeds.
Photovoltaic failure and degradation modes: PV failure and degradation modes
Energy Technology Data Exchange (ETDEWEB)
Jordan, Dirk C. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden Colorado 80401 USA; Silverman, Timothy J. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden Colorado 80401 USA; Wohlgemuth, John H. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden Colorado 80401 USA; Kurtz, Sarah R. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden Colorado 80401 USA; VanSant, Kaitlyn T. [Colorado School of Mines, 1500 Illinois Street Golden Colorado 8040 USA
2017-01-30
The extensive photovoltaic field reliability literature was analyzed and reviewed. Future work is prioritized based upon information assembled from recent installations, and inconsistencies in degradation mode identification are discussed to help guide future publication on this subject. Reported failure rates of photovoltaic modules fall mostly in the range of other consumer products; however, the long expected useful life of modules may not allow for direct comparison. In general, degradation percentages are reported to decrease appreciably in newer installations that are deployed after the year 2000. However, these trends may be convoluted with varying manufacturing and installation quality world-wide. Modules in hot and humid climates show considerably higher degradation modes than those in desert and moderate climates, which warrants further investigation. Delamination and diode/j-box issues are also more frequent in hot and humid climates than in other climates. The highest concerns of systems installed in the last 10 years appear to be hot spots followed by internal circuitry discoloration. Encapsulant discoloration was the most common degradation mode, particularly in older systems. In newer systems, encapsulant discoloration appears in hotter climates, but to a lesser degree. Thin-film degradation modes are dominated by glass breakage and absorber corrosion, although the breadth of information for thin-film modules is much smaller than for x-Si.
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......The introduction of private and individual transferable quotas is widely considered to have a negative impact on small- and medium-sized fishing operations. In this chapter, I set out to explore this in a theoretical manner. I discuss the differences in the fishing operations as two contrasting...... are promoted by this type of fisheries management....
Failure Mode/Mechanism Distributions
1991-09-01
nsc. Modas /Mach Dist. Dist. Suurce(,%)/Detai19 Bolt, MahineSources :1 Brcikon .1% 59.0% Broken Bolt(s) (25j01-(000,Qty:l) C25101-000,Qty:Ij., Part...Center (RAC) * 201 Mill St., Rome, NY 13440 * 315-337-0900 3-114 Failure Distribution Summaries FMD-91 ? art Failure Norm Fail Data Docm. Mode/Moch Dist... Deco . Mode/Mech Dist. Dist. Source(s)/Details Lamp,Bulb Sourcent 4 Lamp Failure 68.8% 53.8% Light Bulb Failure (23038-00l,Qty:3) (23038-004,Qty:l
Channel estimation in TDD mode
Institute of Scientific and Technical Information of China (English)
ZHANG Yi; GU Jian; YANG Da-cheng
2006-01-01
An efficient solution is proposed in this article for the channel estimation in time division duplex (TDD) mode wireless communication systems. In the proposed solution, the characteristics of fading channels in TDD mode systems are fully exploited to estimate the path delay of the fading channel.The corresponding amplitude is estimated using the minimum mean square error (MMSE) criterion. As a result, it is shown that the proposed novel solution is more accurate and efficient than the traditional solution, and the improvement is beneficial to the performance of Joint Detection.
Decay of Quantum Accelerator Modes
Sheinman, M; Guarneri, I; Rebuzzini, L; Fishman, Shmuel; Guarneri, Italo; Rebuzzini, Laura; Sheinman, Michael
2005-01-01
Experimentally observable Quantum Accelerator Modes are used as a test case for the study of some general aspects of quantum decay from classical stable islands immersed in a chaotic sea. The modes are shown to correspond to metastable states, analogous to the Wannier-Stark resonances. Different regimes of tunneling, marked by different quantitative dependence of the lifetimes on 1/hbar, are identified, depending on the resolution of KAM substructures that is achieved on the scale of hbar. The theory of Resonance Assisted Tunneling introduced by Brodier, Schlagheck, and Ullmo [9], is revisited, and found to well describe decay whenever applicable.
Microtearing modes in tokamak discharges
Rafiq, T.; Weiland, J.; Kritz, A. H.; Luo, L.; Pankin, A. Y.
2016-06-01
Microtearing modes (MTMs) have been identified as a source of significant electron thermal transport in tokamak discharges. In order to describe the evolution of these discharges, it is necessary to improve the prediction of electron thermal transport. This can be accomplished by utilizing a model for transport driven by MTMs in whole device predictive modeling codes. The objective of this paper is to develop the dispersion relation that governs the MTM driven transport. A unified fluid/kinetic approach is used in the development of a nonlinear dispersion relation for MTMs. The derivation includes the effects of electrostatic and magnetic fluctuations, arbitrary electron-ion collisionality, electron temperature and density gradients, magnetic curvature, and the effects associated with the parallel propagation vector. An iterative nonlinear approach is used to calculate the distribution function employed in obtaining the nonlinear parallel current and the nonlinear dispersion relation. The third order nonlinear effects in magnetic fluctuations are included, and the influence of third order effects on a multi-wave system is considered. An envelope equation for the nonlinear microtearing modes in the collision dominant limit is introduced in order to obtain the saturation level. In the limit that the mode amplitude does not vary along the field line, slab geometry, and strong collisionality, the fluid dispersion relation for nonlinear microtearing modes is found to agree with the kinetic dispersion relation.
Although glyphosate is the most used and studied herbicide in the world, the available information is not enough to fully understand its mode of action. The molecular site of action of glyphosate is the enzyme 5-enolpyruvlyshikimate-3-phosphate synthase (EPSPS). It is the only known compound that ...
An acoustic mode measurement technique
Joppa, P. D.
1984-10-01
Turbomachinery noise propagates in aircraft jet engine ducts in a complicated manner. Measurement of this propagation is useful both to identify source mechanisms and to design efficient linings. A practical method of making these measurements has been developed, using linear arrays of equally spaced microphones mounted flush with the duct wall. Circumferential or axial arrays are analyzed by spatial Fourier transform, giving sound level as a function of spinning order or axial wavenumber respectively. Complex demodulation is used to acquire data in a modest bandwidth around a high frequency of interest. A joint NASA/Boeing test of the system used 32 microphones in a JT15D turbofan engine inlet. A 400-Hz bandwidth centered at blade passage frequency and at half blade passage frequency was studied. The theoretically predicted modes were clearly seen at blade passage frequency; broadband noise at half blade passage frequency was biased towards modes corotating with the fan. Interference between similar modes was not a significant problem. A lining design study indicated a 15 percent improvement in lining efficiency was possible when mode data were used, for this particular engine. The technique has proven reliable and useful for source diagnostics and lining design.
Cancellieri, G
1991-01-01
This book describes signal propagation in single-mode optical fibres for telecommunication applications. Such description is based on the analysis of field propagation, considering waveguide properties and also some of the particular characteristics of the material fibre. The book covers such recent advances as, coherent transmissions; optical amplification; MIR fibres; polarization maintaining; polarization diversity and photon counting.
Quasiadiabatic modes from viscous inhomogeneities
Giovannini, Massimo
2016-04-01
The viscous inhomogeneities of a relativistic plasma determine a further class of entropic modes whose amplitude must be sufficiently small since curvature perturbations are observed to be predominantly adiabatic and Gaussian over large scales. When the viscous coefficients only depend on the energy density of the fluid the corresponding curvature fluctuations are shown to be almost adiabatic. After addressing the problem in a gauge-invariant perturbative expansion, the same analysis is repeated at a nonperturbative level by investigating the nonlinear curvature inhomogeneities induced by the spatial variation of the viscous coefficients. It is demonstrated that the quasiadiabatic modes are suppressed in comparison with a bona fide adiabatic solution. Because of its anomalously large tensor to scalar ratio the quasiadiabatic mode cannot be a substitute for the conventional adiabatic paradigm so that, ultimately, the present findings seems to exclude the possibility of a successful accelerated dynamics solely based on relativistic viscous fluids. If the dominant adiabatic mode is not affected by the viscosity of the background a sufficiently small fraction of entropic fluctuations of viscous origin cannot be a priori ruled out.
Mode-division multiplexed transmission with inline few-mode fiber amplifier.
Bai, Neng; Ip, Ezra; Huang, Yue-Kai; Mateo, Eduardo; Yaman, Fatih; Li, Ming-Jun; Bickham, Scott; Ten, Sergey; Liñares, Jesús; Montero, Carlos; Moreno, Vicente; Prieto, Xesús; Tse, Vincent; Man Chung, Kit; Lau, Alan Pak Tao; Tam, Hwa-Yaw; Lu, Chao; Luo, Yanhua; Peng, Gang-Ding; Li, Guifang; Wang, Ting
2012-01-30
We demonstrate mode-division multiplexed WDM transmission over 50-km of few-mode fiber using the fiber's LP01 and two degenerate LP11 modes. A few-mode EDFA is used to boost the power of the output signal before a few-mode coherent receiver. A 6×6 time-domain MIMO equalizer is used to recover the transmitted data. We also experimentally characterize the 50-km few-mode fiber and the few-mode EDFA.
DEFF Research Database (Denmark)
Mackinney-Valentin, Maria
2011-01-01
A textbook for school children 13-16 on fashion. Ethics, designers, social identity, zeitgeist, and gender are among the key themes.......A textbook for school children 13-16 on fashion. Ethics, designers, social identity, zeitgeist, and gender are among the key themes....
Blagoveshchenskaya, N. F.; Borisova, T. D.; Kalishin, A. S.; Yeoman, T. K.; Häggström, I.
2017-03-01
We provide the first experimental evidence of the sensitivity of phenomena induced by extraordinary (X-mode) polarized HF high power radio waves to pump frequency stepping across the fifth electron gyro-harmonic (5fce) from below to above. The results were obtained at the EISCAT (European Incoherent Scatter Scientific Association) HF heater facility near Tromsø under effective radiated powers of 456-715 MW, when the HF pump wave was transmitted into the magnetic zenith. We have analyzed the behavior and intensities of various spectral lines in the narrowband stimulated electromagnetic emission (SEE) spectra observed far from the heater, HF-enhanced plasma and ion lines (HFPL and HFIL) from EISCAT UHF incoherent scatter radar spectra, and artificial field-aligned irregularities from CUTLASS (Co-operative UK Twin Located Auroral Sounding System) observations, depending on the frequency offset of the pump field relative to the 5fce. At pump frequencies below 5fce the narrowband SEE spectra exhibited very intense so-called stimulated ion Bernstein scatter (SIBS), accompanied by other spectral components, associated with stimulated Brillouin scatter (SBS), which are greatly suppressed and disappeared in the vicinity of 5fce and did not reappear at fH>5fce. As the pump frequency reached 5fce, the abrupt enhancements of the HFPL and HFIL power, the appearance of cascade lines in the plasma line spectra, and the onset of increasing CUTLASS backscatter power occurred. That is opposite to the ordinary mode (O-mode) effects in the vicinity of 5fce. The X-mode pumping at frequencies below and in the vicinity of the fifth electron gyro-harmonic clearly demonstrated an ascending altitude of generation of induced plasma and ion lines from the initial interaction height, whereas for O-mode heating the region of interaction descended. The observations are consistent with the coexistence of the electron acceleration along and across the geomagnetic field at fH<5fce, while only very
Broadband mode conversion via gradient index metamaterials.
Wang, HaiXiao; Xu, YaDong; Genevet, Patrice; Jiang, Jian-Hua; Chen, HuanYang
2016-04-21
We propose a design for broadband waveguide mode conversion based on gradient index metamaterials (GIMs). Numerical simulations demonstrate that the zeroth order of transverse magnetic mode or the first order of transverse electric mode (TM0/TE1) can be converted into the first order of transverse magnetic mode or the second order of transverse electric mode (TM1/TE2) for a broadband of frequencies. As an application, an asymmetric propagation is achieved by integrating zero index metamaterials inside the GIM waveguide.
The quest for the solar g modes
Appourchaux, T.; Belkacem, K.; Broomhall, A.-M.; Chaplin, W. J.; Gough, D. O.; Houdek, G.; Provost, J.; Baudin, F.; Boumier, P.; Elsworth, Y.; García, R. A.; Andersen, B. N.; Finsterle, W.; Fröhlich, C.; Gabriel, A.; Grec, G.; Jiménez, A.; Kosovichev, A.; Sekii, T.; Toutain, T.; Turck-Chièze, S.
2010-02-01
Solar gravity modes (or g modes)—oscillations of the solar interior on which buoyancy acts as the restoring force—have the potential to provide unprecedented inference on the structure and dynamics of the solar core, inference that is not possible with the well-observed acoustic modes (or p modes). The relative high amplitude of the g-mode eigenfunctions in the core and the evanesence of the modes in the convection zone make the modes particularly sensitive to the physical and dynamical conditions in the core. Owing to the existence of the convection zone, the g modes have very low amplitudes at photospheric levels, which makes the modes extremely hard to detect. In this article, we review the current state of play regarding attempts to detect g modes. We review the theory of g modes, including theoretical estimation of the g-mode frequencies, amplitudes and damping rates. Then we go on to discuss the techniques that have been used to try to detect g modes. We review results in the literature, and finish by looking to the future, and the potential advances that can be made—from both data and data-analysis perspectives—to give unambiguous detections of individual g modes. The review ends by concluding that, at the time of writing, there is indeed a consensus amongst the authors that there is currently no undisputed detection of solar g modes.
An Eavesdropping Detecting Approach Based on Mode-Mode Correlation
Institute of Scientific and Technical Information of China (English)
XIONG Jin; ZENG Gui-Hua; ZHOU Nan-Run
2005-01-01
@@ We find that second-order coherence as well as a Hanbury-Brown-Twiss intensity interferometer may provide an optimal approach for eavesdropping detection in the quantum key distribution based on two-mode squeezed'vacuum states. With this approach, eavesdropping can be easily detected without sacrificing extra secret bits as the test key. In addition, the efficiency of the quantum key distribution protocol is enhanced greatly.
Mode-to-mode energy transfers in convective patterns
Indian Academy of Sciences (India)
Mahendra K Verma; Krishna Kumar; Bhaskar Kamble
2006-12-01
We investigate the energy transfer between various Fourier modes in a low-dimensional model for thermal convection. We have used the formalism of mode-to-mode energy transfer rate in our calculation. The evolution equations derived using this scheme is the same as those derived using the hydrodynamical equations for thermal convection in Boussinesq fluids. Numerical and analytical studies of this model show that convective rolls appear as the Rayleigh number is raised above its critical value c. Further increase of Rayleigh number generates rolls in the perpendicular directions as well, and we obtain a dynamic asymmetric square pattern. This pattern is due to Hopf bifurcation. There are two sets of limit cycles corresponding to the two competing asymmetric square patterns. When the Rayleigh number is increased further, the limit cycles become unstable simultaneously, and chaotic motion sets in. The onset of chaos is via intermittent route. The trajectories wander for quite a long time almost periodically before jumping irregularly to one of the two ghost limit cycles.
Atmospheric type modes in laser fusion targets
Scannapieco, A. J.
1981-09-01
The fluid stability of laser-fusion targets is considered as a stability problem of a pseudo-planetary atmosphere. Three atmospheric type modes are studied; acoustic, gravity, and Lamb modes. The changing character (i.e., growing, oscillatory, or growing-oscillatory) of each is investigated as a function of the density-gradient scale length H of the fluid. A growing class of modes is found which is distinct from the gravity (i.e., Taylor) mode if a gradient in entropy exists in the fluid. These modes are shown to be overstable Lamb modes. Also, the gravity mode is only stable for a distinct band of values of H. These values, at which the density and Lamb modes change character, are derived from the dispersion relation for the modes. Finally, the consequences for laser targets are discussed.
Ren, Fang; Li, Juhao; Wu, Zhongying; Hu, Tao; Yu, Jinyi; Mo, Qi; He, Yongqi; Chen, Zhangyuan; Li, Zhengbin
2017-01-01
We propose three-mode mode-division-multiplexing passive optical network (MDM-PON) based on low mode-crosstalk few-mode fiber (FMF) and all-fiber mode multiplexer/demultiplexer (MUX/DEMUX). The FMF with step-index profile is designed and fabricated for effectively three-independent-spatial-mode transmission and low mode-crosstalk for MDM-PON transmission. The all-fiber mode MUX/DEMUX are composed of cascaded mode selective couplers (MSCs), which simultaneously multiplex or demultiplex multiple modes. Based on the low mode-crosstalk of the FMF and all-fiber mode MUX/DEMUX, each optical network unit (ONU) communicates with the optical line terminal (OLT) independently utilizing a different optical linearly polarized (LP) spatial mode in MDM-PON system. We experimentally demonstrate MDM-PON transmission of three independent-spatial-modes over 12-km FMF with 10-Gb/s optical on-off keying (OOK) signal and direct detection.
Climate Modes of the Phanerozoic
Frakes, Lawrence A.; Francis, Jane E.; Syktus, Jozef I.
1992-11-01
This book views the Earth's climate as a global system, by describing the evolution of climate throughout the past 600 million years, from the Cambrian to the Quaternary. Palaeoclimates are examined in terms of Cold and Warm modes--phases during which the Earth's climates were either relatively cool with ice forming in high latitudes or when high levels of CO2 led to "greenhouse" warmings and temperate floras and faunas inhabited polar regions. Evidence for climate changes, such as biological indicators, geochemical parameters, and the presence of ice, are compared between these modes. These studies have highlighted the crucial role of tectonics and continental distribution in governing ocean circulation, the distribution of sea ice, sea level changes and global temperature distribution. Orbital forcing and the carbon cycle are also shown as important influences, particularly on short term climatic variations.
Fission modes of mercury isotopes
Warda, M; Nazarewicz, W
2012-01-01
Recent experiments on beta-delayed fission in the mercury-lead region and the discovery of asymmetric fission in $^{180}$Hg [1] have stimulated renewed interest in the mechanism of fission in heavy nuclei. Here we study fission modes and fusion valleys in $^{180}$Hg and $^{198}$Hg using the self-consistent nuclear density functional theory employing Skyrme and Gogny energy density functionals. We show that the observed transition from asymmetric fission in $^{180}$Hg towards more symmetric distribution of fission fragments in $^{198}$Hg can be explained in terms of competing fission modes of different geometries that are governed by shell effects in pre-scission configurations. The density distributions at scission configurations are studied and related to the experimentally observed mass splits.
Hypersonic modes in nanophononic semiconductors.
Hepplestone, S P; Srivastava, G P
2008-09-05
Frequency gaps and negative group velocities of hypersonic phonon modes in periodically arranged composite semiconductors are presented. Trends and criteria for phononic gaps are discussed using a variety of atomic-level theoretical approaches. From our calculations, the possibility of achieving semiconductor-based one-dimensional phononic structures is established. We present results of the location and size of gaps, as well as negative group velocities of phonon modes in such structures. In addition to reproducing the results of recent measurements of the locations of the band gaps in the nanosized Si/Si{0.4}Ge{0.6} superlattice, we show that such a system is a true one-dimensional hypersonic phononic crystal.
Mode S Baseline Radar Tracking.
1982-11-01
range units and 20 azimuth units) overlaying the position of the beacon reports. In the cases analyzed where beacon reports were not radar reinforced ...82/53 j~ C ~ 7 C _ _ _ _ _ _ 4. Title end Su.btitle 5. Neget at. November 1982 MDDE S BASELINE RADAR TRACKIN4G 6. Poelin Orgeuianti.. Cede ACT-100...Ground Clutter 33 Mode S/ARTS III 100-Scan False Radar Track Summary 74 34 Percent Beacon Radar Reinforcement 77 vii INTRODUCTION PURPOSE. The purpose of
Fast Response Liquid Crystal Mode
2011-04-19
Journal of Applied Physics , vol. 39, No. 6A, Jun. 1, 2000, pp. 527-530. Hajime...Nakamura, et a!., "Bend Transition in Pi-cell" Journal of Applied Physics , vol. 39, No. 11, Nov. 1, 2000, pp. 6368-6375. "Electro-Optical Performance of a...Characteristic of Fringe-Field Switching Mode Depending on Rubbing Direction," S.H. Hong et a!, Journal of Applied Physics vol. 39, No. 6A, Jun. 1, 2000,
Quasiadiabatic modes from viscous inhomogeneities
Giovannini, Massimo
2016-01-01
The viscous inhomogeneities of a relativistic plasma determine a further class of entropic modes whose amplitude must be sufficiently small since curvature perturbations are observed to be predominantly adiabatic and Gaussian over large scales. When the viscous coefficients only depend on the energy density of the fluid the corresponding curvature fluctuations are shown to be almost adiabatic. After addressing the problem in a gauge-invariant perturbative expansion, the same analysis is repea...
A Lagrangian Dynamic Mode Decomposition
Sesterhenn, Jörn
2016-01-01
Temporal or spatial structures are readily extracted from complex data by modal decompositions like POD or DMD. Subspaces of that decompositions serve as reduced order models and define spatial structures in time or temporal structures in space. Convecting phenomena pose a major problem to those decompositions. A structure travelling with a certain group velocity will be perceived as a plethora of modes in time or space respectively. This manifests itself for example in poorly decaying Singular Values when using a POD. The poor decay is very counter-intuitive, since we expect a single structure to be represented by a few modes. The intuition proves to be correct and we show that in a properly chosen reference frame along the characteristic defined by the group velocity, a POD or DMD reduces moving structures to a few modes, as expected. Beyond serving as a reduced model, the re- sulting entity can be used to define a constant or minimally changing structure in turbulent flows. This can be interpreted as an em...
Characteristics of magnetoacoustic sausage modes
Inglis, A R; Brady, C S; Nakariakov, V M; 10.1051/0004-6361/200912088
2013-01-01
Aims: We perform an advanced study of the fast magnetoacoustic sausage oscillations of coronal loops in the context of MHD coronal seismology to establish the dependence of the sausage mode period and cut-off wavenumber on the plasma-beta of the loop-filling plasma. A parametric study of the ratios for different harmonics of the mode is also carried out. Methods: Full magnetohydrodynamic numerical simulations were performed using Lare2d, simulating hot, dense loops in a magnetic slab environment. The symmetric Epstein profile and a simple step-function profile were both used to model the density structure of the simulated loops. Analytical expressions for the cut-off wavenumber and the harmonic ratio between the second longitudinal harmonic and the fundamental were also examined. Results: It was established that the period of the global sausage mode is only very weakly dependent on the value of the plasma-beta inside a coronal loop, which justifies the application of this model to hot flaring loops. The cut-o...
Subharmonic Fourier domain mode locking.
Eigenwillig, Christoph M; Wieser, Wolfgang; Biedermann, Benjamin R; Huber, Robert
2009-03-15
We demonstrate a subharmonically Fourier domain mode-locked wavelength-swept laser source with a substantially reduced cavity fiber length. In contrast to a standard Fourier domain mode-locked configuration, light is recirculated repetitively in the delay line with the optical bandpass filter used as switch. The laser has a fundamental optical round trip frequency of 285 kHz and can be operated at integer fractions thereof (subharmonics). Sweep ranges up to 95 nm full width centred at 1317 nm are achieved at the 1/5th subharmonic. A maximum sensitivity of 116 dB and an axial resolution of 12 microm in air are measured at an average sweep power of 12 mW. A sensitivity roll-off of 11 dB over 4 mm and 25 dB over 10 mm is observed and optical coherence tomography imaging is demonstrated. Besides the advantage of a reduced fiber length, subharmonic Fourier domain mode locking (shFDML) enables simple scaling of the sweep speed by extracting light from the delay part of the resonator. A sweep rate of 570 kHz is achieved. Characteristic features of shFDML operation, such as power leakage during fly-back and cw breakthrough, are investigated.
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.
Directory of Open Access Journals (Sweden)
Schmitz Michael
2016-03-01
Full Text Available In this paper I first introduce Tomasello’s notion of thought and his account of its emergence and development through differentiation, arguing that it calls into question the theory bias of the philosophical tradition on thought as well as its frequent atomism. I then raise some worries that he may be overextending the concept of thought, arguing that we should recognize an area of intentionality intermediate between action and perception on the one hand and thought on the other. After that I argue that the co-operative nature of humans is reflected in the very structure of their intentionality and thought: in co-operative modes such as the mode of joint attention and action and the we-mode, they experience and represent others as co-subjects of joint relations to situations in the world rather than as mere objects. In conclusion, I briefly comment on what Tomasello refers to as one of two big open questions in the theory of collective intentionality, namely that of the irreducibility of jointness.
High Polarization Single Mode Photonic Crystal Microlaser
Institute of Scientific and Technical Information of China (English)
CHEN Wei; XING Ming-Xin; ZHOU Wen-Jun; LIU An-Jin; ZHENG Wan-Hua
2009-01-01
Generally,dipole mode is a doubly degenerate mode.Theoretical calculations have indicated that the single dipole mode of two-dimensional photonic crystal single point defect cavity shows high polarization property.We present a structure with elongated lattice,which only supports a single y-dipole mode.With this structure we can eliminate the degeneracy,control the lasing action of the cavity and demonstrate the high polarization property of the single dipole mode.In our experiment,the polarization extinction ratio of the y-dipole mode is as high as 51:1.
Mode-dependent characterization of photonic lanterns.
Yu, Dawei; Fu, Songnian; Cao, Zizheng; Tang, Ming; Liu, Deming; Giles, Ian; Koonen, Ton; Okonkwo, Chigo
2016-05-15
We propose and experimentally demonstrate a simple method for characterizing the power transfer matrix of photonic lanterns (PLs) used for mode division multiplexing (MDM) transmission. Due to the optical reflection arising at output facet of the few-mode fiber (FMF), we are able to detect the power at the individual single-mode fiber (SMF) input port and exploit a series of equations based on the theory of energy conservation to obtain mode-dependent characteristics of the PL, including the property of mode selectivity, insertion loss (IL), and channel-dependent loss (CDL). The proposed method is experimentally verified for both the mode selective and the nonmode selective photonic lanterns.
Dipole modes with depressed amplitudes in red giants are mixed modes
Mosser, B; Pincon, C; Takata, M; Vrard, M; Barban, C; Goupil, M-J; Kallinger, T; Samadi, R
2016-01-01
Seismic observations have shown that a number of evolved stars exhibit low-amplitude dipole modes, which are referred to as depressed modes. Recently, these low amplitudes have been attributed to the presence of a strong magnetic field in the stellar core of those stars. We intend to study the properties of depressed modes in evolved stars, which is a necessary condition before concluding on the physical nature of the mechanism responsible for the reduction of the dipole mode amplitudes. We perform a thorough characterization of the global seismic parameters of depressed dipole modes and show that these modes have a mixed character. The observation of stars showing dipole mixed modes that are depressed is especially useful for deriving model-independent conclusions on the dipole mode damping. Observations prove that depressed dipole modes in red giants are not pure pressure modes but mixed modes. This result invalidates the hypothesis that the depressed dipole modes result from the suppression of the oscillat...
Sarkar, Sujit
2014-01-01
Quantum simulation aims to simulate a quantum system using a controble laboratory system that underline the same mathematical model. Cavity QED lattice system is that prescribe system to simulate the relativistic quantum effect. We quantum simulate the Dirac fermion mode, Majorana fermion mode and Majorana-Weyl fermion mode and a crossover between them in cavity QED lattice. We also present the different analytical relations between the field operators for different mode excitations.
WATERMARKING AUTHENTICATION: USING THE FRAGILE MODE OR THE ROBUST MODE?
Institute of Scientific and Technical Information of China (English)
Chen Dan; Wu Qianhong; Wang Yumin
2006-01-01
Due to the lack of a unified authentication model certain mistakes occurred in the use of the watermarking authentication methods. To clarify the confusion, authentication models of robust and fragile watermarking are developed respectively in the paper. Concrete algorithms are proposed to prove the models that different Discrete Wavelet Transform (DWT) domains are utilized to embed the watermarks and quantization method is presented with Just Notice Differences (JNDs) threshold as the quantization size. After the key technologies about the two methods are discussed, we detail the comparison of the two modes and recommend their respective application scenarios as applicable results.
Interferometric detection of mode splitting for whispering gallery mode biosensors
Knittel, Joachim; Lee, Kwan H; Bowen, Warwick P
2010-01-01
Sensors based on whispering gallery mode resonators can detect single nanoparticles and even single molecules. Particles attaching to the resonator induce a doublet in the transmission spectrum which provides a self-referenced detection signal. However, in practice this spectral feature is often obscured by the width of the resonance line which hides the doublet structure. This happens particularly in liquid environments that reduce the effective Q factor of the resonator. In this paper we demonstrate an interferometric set-up that allows the direct detection of the hidden doublet and thus provides a pathway for developing practical sensor applications.
The quest for the solar g modes
Appourchaux, T; Broomhall, A M; Chaplin, W J; Gough, D O; Houdek, G; Provost, J; Baudin, F; Boumier, P; Elsworth, Y; García, R A; Andersen, B; Finsterle, W; Fröhlich, C; Gabriel, A; Grec, G; Jiménez, A; Kosovichev, A; Sekii, T; Toutain, T; Turck-Chièze, S
2009-01-01
Solar gravity modes (or g modes) -- oscillations of the solar interior for which buoyancy acts as the restoring force -- have the potential to provide unprecedented inference on the structure and dynamics of the solar core, inference that is not possible with the well observed acoustic modes (or p modes). The high amplitude of the g-mode eigenfunctions in the core and the evanesence of the modes in the convection zone make the modes particularly sensitive to the physical and dynamical conditions in the core. Owing to the existence of the convection zone, the g modes have very low amplitudes at photospheric levels, which makes the modes extremely hard to detect. In this paper, we review the current state of play regarding attempts to detect g modes. We review the theory of g modes, including theoretical estimation of the g-mode frequencies, amplitudes and damping rates. Then we go on to discuss the techniques that have been used to try to detect g modes. We review results in the literature, and finish by looki...
Identifying modes of large whispering-gallery mode resonators from the spectrum and emission pattern
DEFF Research Database (Denmark)
Schunk, Gerhard; Fuerst, Josef U.; Förtsch, Michael;
2014-01-01
Identifying the mode numbers in whispering-gallery mode resonators (WGMRs) is important for tailoring them to experimental needs. Here we report on a novel experimental mode analysis technique based on the combination of frequency analysis and far-field imaging for high mode numbers of large WGMRs....... The radial mode numbers q and the angular mode numbers p = l-m are identified and labeled via far-field imaging. The polar mode numbers l are determined unambiguously by fitting the frequency differences between individual whispering gallery modes (WGMs). This allows for the accurate determination...
Higher order mode optical fiber Raman amplifiers
DEFF Research Database (Denmark)
Rottwitt, Karsten; Friis, Søren Michael Mørk; Usuga Castaneda, Mario A.;
2016-01-01
We review higher order mode Raman amplifiers and discuss recent theoretical as well as experimental results including system demonstrations.......We review higher order mode Raman amplifiers and discuss recent theoretical as well as experimental results including system demonstrations....
Path planning during combustion mode switch
Jiang, Li; Ravi, Nikhil
2015-12-29
Systems and methods are provided for transitioning between a first combustion mode and a second combustion mode in an internal combustion engine. A current operating point of the engine is identified and a target operating point for the internal combustion engine in the second combustion mode is also determined. A predefined optimized transition operating point is selected from memory. While operating in the first combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion engine to approach the selected optimized transition operating point. When the engine is operating at the selected optimized transition operating point, the combustion mode is switched from the first combustion mode to the second combustion mode. While operating in the second combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion to approach the target operating point.
Guaranteed performance in reaching mode of sliding mode controlled systems
Indian Academy of Sciences (India)
G K Singh; K E Holé
2004-02-01
Conventionally, the parameters of a sliding mode controller (SMC) are selected so as to reduce the time spent in the reaching mode. Although, an upper bound on the time to reach (reaching time) the sliding surface is easily derived, performance guarantee in the state/error space needs more consideration. This paper addresses the design of constant plus proportional rate reaching law-based SMC for second-order nonlinear systems. It is shown that this controller imposes a bounding second-order error-dynamics, and thus guarantees robust performance during the reaching phase. The choice of the controller parameters based on the time to reach a desirable level of output tracking error (OTE), rather than on the reaching time is proposed. Using the Lyapunov theory, it is shown that parameter selections, based on the reaching time criterion, may need substantially larger time to achieve the OTE. Simulation results are presented for a nonlinear spring-massdamper system. It is seen that parameter selections based on the proposed OTE criterion, result in substantially quicker tracking, while using similar levels of control effort.
Nanowire Plasmon Excitation by Adiabatic Mode Transformation
Verhagen, Ewold; Spasenović, Marko; Polman, Albert; Kuipers, L. (Kobus)
2009-05-01
We show with both experiment and calculation that highly confined surface plasmon polaritons can be efficiently excited on metallic nanowires through the process of mode transformation. One specific mode in a metallic waveguide is identified that adiabatically transforms to the confined nanowire mode as the waveguide width is reduced. Phase- and polarization-sensitive near-field investigation reveals the characteristic antisymmetric polarization nature of the mode and explains the coupling mechanism.
Acoustic Rotation Modes in Complex Plasmas
Institute of Scientific and Technical Information of China (English)
白冬雪; 王正汹; 王晓钢
2004-01-01
Acoustic rotation modes in complex plasmas are investigated in a cylindrical system with an axial symmetry.The linear mode solution is derived. The mode in an infinite area is reduced to a classical dust acoustic wave in the region away from the centre. When the dusty plasma is confined in a finite region, the breathing and rotating-void behaviour are observed. Vivid structures of different mode number solutions are illustrated.
Le Cocq, Guillaume; Bigot, Laurent; Le Rouge, Antoine; Bigot-Astruc, Marianne; Sillard, Pierre; Koebele, Clemens; Salsi, Massimilliano; Quiquempois, Yves
2012-11-19
Numerical and experimental study of a Few-Mode (FM) Erbium Doped Fiber Amplifier (EDFA) suitable for mode division multiplexing (MDM) is reported. Based on numerical simulations, a Few-Mode Erbium Doped Fiber (FM-EDF) has been designed to amplify four mode groups and to equally amplify LP11 and LP21 mode groups with gains greater than 20 dB and with a differential modal gain of less than 1 dB. Experimental results confirmed the simulations with a good concordance. This modal gain equalization is obtained by tailoring the erbium spatial distribution in the fiber core with a ring-shaped profile.
Principal modes in multimode fibers: exploring the crossover from weak to strong mode coupling
Xiong, Wen; Bromberg, Yaron; Redding, Brandon; Rotter, Stefan; Cao, Hui
2016-01-01
We present experimental and numerical studies on principal modes in a multimode fiber with mode coupling. By applying external stress to the fiber and gradually adjusting the stress, we have realized a transition from weak to strong mode coupling, which corresponds to the transition from single scattering to multiple scattering in mode space. Our experiments show that principal modes have distinct spatial and spectral characteristic in the weak and strong mode coupling regimes. We also investigate the bandwidth of the principal modes, in particular, the dependence of the bandwidth on the delay time, and the effects of the mode-dependent loss. By analyzing the path-length distributions, we discover two distinct mechanisms that are responsible for the bandwidth of principal modes in weak and strong mode coupling regimes. Taking into account the mode-dependent loss in the fiber, our numerical results are in good agreement with our experimental observations. Our study paves the way for exploring potential applica...
New Modes of Nuclear Excitations
Tsoneva, Nadia
2014-01-01
We present a theoretical approach based on density functional theory supplemented by a microscopic multi-phonon model which is applied for investigations of pygmy resonances and other excitations of different multipolarities in stable and exotic nuclei. The possible relation of low-energy modes to the properties of neutron or proton skins is systematically studied in isotonic and isotopic chains. The fine structure of nuclear electric and magnetic response functions is analyzed and compared to experimental data. Their relevance to nuclear astrophysics is discussed.
Applications of sliding mode control
Ghommam, Jawhar; Zhu, Quanmin
2017-01-01
This book presents essential studies and applications in the context of sliding mode control, highlighting the latest findings from interdisciplinary theoretical studies, ranging from computational algorithm development to representative applications. Readers will learn how to easily tailor the techniques to accommodate their ad hoc applications. To make the content as accessible as possible, the book employs a clear route in each paper, moving from background to motivation, to quantitative development (equations), and lastly to case studies/illustrations/tutorials (simulations, experiences, curves, tables, etc.). Though primarily intended for graduate students, professors and researchers from related fields, the book will also benefit engineers and scientists from industry. .
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...
Directory of Open Access Journals (Sweden)
Luís Melo Campos
2012-01-01
Full Text Available The concept of modes of relating to music is presented, consisting of three conceptual levels and organized into thirteen analytical dimensions that may be operationalized for the purposes of observing empirical situations. It involves closely examining a diversified set of relationships specific to musical practices, in an integrated manner, qualitatively typifying the forms of enjoying them around two poles: the essential and the relational. Although formulated to analyze professional musicians, it is maintained that the concept is also suitable (with adaptations for the analysis of musical consumptions and other spheres of cultural production (intellectual and artistic.
Silicon Geiger mode avalanche photodiodes
Institute of Scientific and Technical Information of China (English)
M. Mazzillo; S. Billotta; G. Bonanno; A. Campisi; L. Cosentino; P. Finocchiaro; F. Musumeci; S.Privitera; S. Tudisco; G. Condorelli; D. Sanfilippo; G. Fallica; E. Sciacca; S. Aurite; S. Lombardo; E. Rlmini; M. Belluso
2007-01-01
In this letter we present the results regarding the electrical and optical characterization of Geiger mode silicon avalanche photodiodes (GMAP) fabricated by silicon standard planar technology. Low dark count rates, negligible afterpulsing effects,good timing resolution and high quantum detection efficiency in all the visible range have been measured. The very good electro-optical performances of our photodiodes make them attractive for the fabrication of arrays with a large number of GMAP to be used both in the commercial and the scientific fields, as telecommunications and nuclear medical imaging.
Inertial modes of slowly rotating isentropic stars
Yoshida, S; Yoshida, Shijun; Lee, Umin
2000-01-01
We investigate inertial mode oscillations of slowly and uniformly rotating, isentropic, Newtonian stars. Inertial mode oscillations are induced by the Coriolis force due to the star's rotation, and their characteristic frequencies are comparable with the rotation frequency $\\Omega$ of the star. So called r-mode oscillations form a sub-class of the inertial modes. In this paper, we use the term ``r-modes'' to denote the inertial modes for which the toroidal motion dominates the spheroidal motion, and the term ``inertial modes'' to denote the inertial modes for which the toroidal and spheroidal motions have comparable amplitude to each other. Using the slow rotation approximation consistent up to the order of $\\Omega^3$, we study the properties of the inertial modes and r-modes, by taking account of the effect of the rotational deformation of the equilibrium on the eigenfrequencies and eigenfunctions. The eigenfrequencies of the r-modes and inertial modes calculated in this paper are in excellent agreement with...
MDM: A Mode Diagram Modeling Framework
DEFF Research Database (Denmark)
Wang, Zheng; Pu, Geguang; Li, Jianwen
2012-01-01
Periodic control systems used in spacecrafts and automotives are usually period-driven and can be decomposed into different modes with each mode representing a system state observed from outside. Such systems may also involve intensive computing in their modes. Despite the fact that such control ...
Chibisov, D. V.; Mikhailenko, V. S.; Stepanov, K. N.
2011-10-01
An extension of hydrodynamic D'Angelo mode of inhomogeneous sheared plasma flow along the magnetic field into the short wavelength range, where the hydrodynamic treatment is not valid, has been considered. We find that D'Angelo mode in this wavelength range is excited by inverse ion Landau damping and is a shear flow driven ion-kinetic mode.
Turbo Codes with Hybrid Interleaving Mode
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
In the investigation of turbo codes, either random interleavers or structured interleavers are used. Combined two kinds of interleavers in one turbo encoder, a hybrid interleaving mode is proposed in this paper. Computer simulations show that the performance of turbo codes with the hybrid interleaving mode is better than that with the typical interleaving mode.
Silicon Photonic Integrated Circuit Mode Multiplexer
DEFF Research Database (Denmark)
Ding, Yunhong; Ou, Haiyan; Xu, Jing;
2013-01-01
We propose and demonstrate a novel silicon photonic integrated circuit enabling multiplexing of orthogonal modes in a few-mode fiber (FMF). By selectively launching light to four vertical grating couplers, all six orthogonal spatial and polarization modes supported by the FMF are successfully exc...
Multimode optical fibers: steady state mode exciter.
Ikeda, M; Sugimura, A; Ikegami, T
1976-09-01
The steady state mode power distribution of the multimode graded index fiber was measured. A simple and effective steady state mode exciter was fabricated by an etching technique. Its insertion loss was 0.5 dB for an injection laser. Deviation in transmission characteristics of multimode graded index fibers can be avoided by using the steady state mode exciter.
Operating Modes Of Chemical Reactors Of Polymerization
Directory of Open Access Journals (Sweden)
Meruyert Berdieva
2012-05-01
Full Text Available In the work the issues of stable technological modes of operation of main devices of producing polysterol reactors have been researched as well as modes of stable operation of a chemical reactor have been presented, which enables to create optimum mode parameters of polymerization process, to prevent emergency situations of chemical reactor operation in industrial conditions.
Forms of knowledge and modes of innovation
DEFF Research Database (Denmark)
Jensen, Morten Berg; Johnson, Björn; Lorenz, Edward
2007-01-01
This paper contrasts two modes of innovation. One, the Science, Technology and Innovation (STI) mode, is based on the production and use of codified scientific and technical knowledge. The other, the Doing, Using and Interacting (DUI) mode, relies on informal processes of learning and experience...
Internal mode of incoherent photovoltaic vector solitons
Institute of Scientific and Technical Information of China (English)
Zhang Bing-Zhi; Wang Hong-Cheng; She Wei-Long
2007-01-01
The internal modes of incoherent vector solitons (IVSs) in photovoltaic photorefractive materials are investigated in the framework of coupled nonlinear Schr(o)dinger equations. It is found that there is a pair of internal modes corresponding to a bright-bright IVS. The propagation dynamics of the bright-bright IVS perturbed by the internal modes is simulated by numerical method.
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.
Janaud, A
1982-05-01
There are between 14-17 million women in the world, excluding China, who wear an IUD, or about 3-5% of all married women younger than 45. Studies on the mode of action of IUDs have been conducted mostly on laboratory animals; they show that ovulation and fecundation are not inhibited by the presence of an IUD. Contrary to what was generally believed, the latest studies have shown that the principle mode of action of the IUD is not its anti-implantation effect, but it depends on the adjustment inside the uterine cavity between the size of the uterine cavity itself, and the size and shape of the device. Endometrial modifications caused by IUDs include inflammatory phenomena, and inhibition of endometrial maturation. Moreover, copper IUDs act directly on spermatozoa and on endometrial steroid receptors. It is still not clear what role prostaglandins play in the mechanism of action of IUDs. Incidence of ectopic pregnancy is not greater in IUD wearers than in women who do not use contraception. Follicle stimulating hormone and luteinizing hormone levels also are comparable in IUD wearers and in nonwearers. IUD wearers have a shorter luteal phase, which entails an earlier menstrual bleeding due to the antifibrinolytic action of the IUD; progesterone levels are identical in users and in nonusers of IUDs.
Dominant modes via model error
Yousuff, A.; Breida, M.
1992-01-01
Obtaining a reduced model of a stable mechanical system with proportional damping is considered. Such systems can be conveniently represented in modal coordinates. Two popular schemes, the modal cost analysis and the balancing method, offer simple means of identifying dominant modes for retention in the reduced model. The dominance is measured via the modal costs in the case of modal cost analysis and via the singular values of the Gramian-product in the case of balancing. Though these measures do not exactly reflect the more appropriate model error, which is the H2 norm of the output-error between the full and the reduced models, they do lead to simple computations. Normally, the model error is computed after the reduced model is obtained, since it is believed that, in general, the model error cannot be easily computed a priori. The authors point out that the model error can also be calculated a priori, just as easily as the above measures. Hence, the model error itself can be used to determine the dominant modes. Moreover, the simplicity of the computations does not presume any special properties of the system, such as small damping, orthogonal symmetry, etc.
Untangled modes in multimode waveguides
Plöschner, Martin; Tyc, TomáÅ.¡; Čižmár, TomáÅ.¡
2016-03-01
Small, fibre-based endoscopes have already improved our ability to image deep within the human body. A novel approach introduced recently utilised disordered light within a standard multimode optical fibre for lensless imaging. Importantly, this approach brought very significant reduction of the instruments footprint to dimensions below 100 μm. The most important limitations of this exciting technology is the lack of bending flexibility - imaging is only possible as long as the fibre remains stationary. The only route to allow flexibility of such endoscopes is in trading-in all the knowledge about the optical system we have, particularly the cylindrical symmetry of refractive index distribution. In perfect straight step-index cylindrical waveguides we can find optical modes that do not change their spatial distribution as they propagate through. In this paper we present a theoretical background that provides description of such modes in more realistic model of real-life step-index multimode fibre taking into account common deviations in distribution of the refractive index from its ideal step-index profile. Separately, we discuss how to include the influence of fibre bending.
Institute of Scientific and Technical Information of China (English)
徐金龙
2011-01-01
Selected Poems of Charles Bernstein translated and edited by Nie Zhenzhao and Luo Lianggong has recently been published in Chinese translation.This work,taking the ＂translation poetics idea＂ as the guiding principle,has managed to maintain the artistic uniqueness of the original poems,and is also the crystallization and testimony of many years＇ deep friendship between the poet and the translators.Pioneering and rebellious,political and social,experimental and innovative,this collection highlights Bernstein＇s poetic ideas and will contribute to promoting the spread,acceptance and research of Language Poetry,particularly Bernstein＇s poetry in China,which is of great significance to the development and the innovation of Chinese contemporary poetry.%由聂珍钊和罗良功编译的《查尔斯.伯恩斯坦诗选》中译本新近出版。该著以＂翻译诗学观念＂为指导原则,保持了原作的本真艺术特性,也是原作者与编译者多年深情厚谊的结晶和见证。该著彰显了伯恩斯坦的诗学观念,表现了语言诗的先锋性和反叛性、政治性和社会性、实验性和创新性的艺术创作特色,有利于进一步推动语言诗尤其是伯恩斯坦的诗歌在中国的传播、接受和研究,对中国当代诗歌的发展和创新不无启示意义。
Dispersion of coupled mode-gap cavities
Lian, Jin; Yüce, Emre; De Rossi, Sylvain Combrié Alfredo; Mosk, Allard P
2015-01-01
The dispersion of a CROW made of photonic crystal mode-gap cavities is pronouncedly asymmetric. This asymmetry cannot be explained by the standard tight binding model. We show that the fundamental cause of the asymmetric dispersion is the fact that the cavity mode profile itself is dispersive, i.e., the mode wave function depends on the driving frequency, not the eigenfrequency. This occurs because the photonic crystal cavity resonances do not form a complete set. By taking into account the dispersive mode profile, we formulate a mode coupling model that accurately describes the asymmetric dispersion without introducing any new free parameters.
Distributed mode filtering rod fiber amplifier delivering 292W with improved mode stability
DEFF Research Database (Denmark)
Laurila, Marko; Jørgensen, Mette Marie; Hansen, Kristian Rymann;
2012-01-01
We demonstrate a high power fiber (85μm core) amplifier delivering up to 292Watts of average output power using a mode-locked 30ps source at 1032nm. Utilizing a single mode distributed mode filter bandgap rod fiber, we demonstrate 44% power improvement before the threshold-like onset of mode...
Tearing mode instability due to anomalous resistivity
Energy Technology Data Exchange (ETDEWEB)
Furuya, Atsushi [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka (Japan); Itoh, Sanae I.; Yagi, Masatoshi [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics
2000-09-01
Tearing mode instability in the presence of microscopic truculence is investigates. The effects of microscopic turbulence on tearing mode are taken as drags which are calculated by one-point renormalization method and mean-field approximation. These effects are reduced to effective diffusivities in reduced MHD equations. Using these equations, the stability analyses of the tearing mode are performed. It is shown that a finite amplitude of fluctuation enhances the growth rate of tearing mode. For very high values of turbulent diffusivities, marginally stable state exists. The effects of each turbulent diffusivity on mode stability are examined near marginal stability boundary. Parameter dependence of the resistive ballooning mode turbulence on tearing mode is analyzed as an example. (author)
New Edge Coherent Mode Providing Continuous Transport in Long-Pulse H-mode Plasmas
Wang, H. Q.; Xu, G. S.; Wan, B. N.; Ding, S. Y.; Guo, H. Y.; Shao, L. M.; Liu, S. C.; Xu, X. Q.; Wang, E.; Yan, N.; Naulin, V.; Nielsen, A. H.; Rasmussen, J. Juul; Candy, J.; Bravenec, R.; Sun, Y. W.; Shi, T. H.; Liang, Y. F.; Chen, R.; Zhang, W.; Wang, L.; Chen, L.; Zhao, N.; Li, Y. L.; Liu, Y. L.; Hu, G. H.; Gong, X. Z.
2014-05-01
An electrostatic coherent mode near the electron diamagnetic frequency (20-90 kHz) is observed in the steep-gradient pedestal region of long pulse H-mode plasmas in the Experimental Advanced Superconducting Tokamak, using a newly developed dual gas-puff-imaging system and diamond-coated reciprocating probes. The mode propagates in the electron diamagnetic direction in the plasma frame with poloidal wavelength of ˜8 cm. The mode drives a significant outflow of particles and heat as measured directly with the probes, thus greatly facilitating long pulse H-mode sustainment. This mode shows the nature of dissipative trapped electron mode, as evidenced by gyrokinetic turbulence simulations.
Quantum Collapse and Revival of Atom in Mode-Mode Competing System
Institute of Scientific and Technical Information of China (English)
WU Qin; FANG Mao-Fa
2005-01-01
The atomic inversion dynamics in the mode-mode competing system is studied by means of fully quantum theory. A general solution to the Schrodinger equation of this system is obtained. The influence of the relative competing strength between the atom and the two-mode field on the atomic inversion is disccussed. We show that the presence of the mode-mode competition can result in periodical collapses-revivals of the atomic inversion.
Mode-selective optical packet switching in mode-division multiplexing networks.
Diamantopoulos, N P; Hayashi, M; Yoshida, Y; Maruta, A; Maruyama, R; Kuwaki, N; Takenaga, K; Uemura, H; Matsuo, S; Kitayama, K
2015-09-07
A novel mode-selective optical packet switching, based on mode-multiplexers/demultiplexers and multi-port optical micro-electro-mechanical systems (MEMS) switches, has been proposed and experimentally demonstrated. The experimental demonstration was performed using the LP(01), LP(11a) and LP(11b) modes of a 30-km long mode-division multiplexed few-mode fiber link, utilizing 40 Gb/s, 16-QAM signals.
Curioni, A.
2013-05-01
MODES SNM is a collaborative project (funded under the FP7 - Security program), aimed at developing a prototype for a mobile, modular detection system for radioactive and Special Nuclear Materials (SNM). To maximize the detection capability for SNM, the prototype will combine detectors for fast and thermal neutrons, as well as for gamma-rays. The key detector technology in the development is high pressure scintillation cells filled with noble gases, as recently developed by ARKTIS. The project started officially at the beginning of 2012, for a duration of 30 months. The goal of the project is to deliver a fully integrated and field tested prototype of a modular mobile system capable of passively detecting weak or shielded radioactive sources with accuracy higher than currently available systems. We will present the status of the project, preliminary results and future prospects.
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.
Nonlinear r-Modes in Neutron Stars Instability of an unstable mode
Gressman, P T; Suen, W M; Stergioulas, N; Friedman, J L; Gressman, Philip; Lin, Lap-Ming; Suen, Wai-Mo; Friedman, John L.
2002-01-01
We study the dynamical evolution of a large amplitude r-mode by numerical simulations. R-modes in neutron stars are unstable growing modes, driven by gravitational radiation reaction. In these simulations, r-modes of amplitude unity or above are destroyed by a catastrophic decay: A large amplitude r-mode gradually leaks energy into other fluid modes, which in turn act nonlinearly with the r-mode, leading to the onset of the rapid decay. As a result the r-mode suddenly breaks down into a differentially rotating configuration. The catastrophic decay does not appear to be related to shock waves at the star's surface. The limit it imposes on the r-mode amplitude is significantly smaller than that suggested by previous fully nonlinear numerical simulations.
Transient analysis mode participation for modal survey target mode selection using MSC/NASTRAN DMAP
Barnett, Alan R.; Ibrahim, Omar M.; Sullivan, Timothy L.; Goodnight, Thomas W.
1994-01-01
Many methods have been developed to aid analysts in identifying component modes which contribute significantly to component responses. These modes, typically targeted for dynamic model correlation via a modal survey, are known as target modes. Most methods used to identify target modes are based on component global dynamic behavior. It is sometimes unclear if these methods identify all modes contributing to responses important to the analyst. These responses are usually those in areas of hardware design concerns. One method used to check the completeness of target mode sets and identify modes contributing significantly to important component responses is mode participation. With this method, the participation of component modes in dynamic responses is quantified. Those modes which have high participation are likely modal survey target modes. Mode participation is most beneficial when it is used with responses from analyses simulating actual flight events. For spacecraft, these responses are generated via a structural dynamic coupled loads analysis. Using MSC/NASTRAN DMAP, a method has been developed for calculating mode participation based on transient coupled loads analysis results. The algorithm has been implemented to be compatible with an existing coupled loads methodology and has been used successfully to develop a set of modal survey target modes.
CMB Delensing Beyond the B Modes
Green, Daniel; van Engelen, Alexander
2016-01-01
Gravitational lensing by large-scale structure significantly impacts observations of the cosmic microwave background (CMB): it smooths the acoustic peaks in temperature and $E$-mode polarization power spectra, correlating previously uncorrelated modes; and it converts $E$-mode polarization into $B$-mode polarization. The act of measuring and removing the effect of lensing from CMB maps, or delensing, has been well studied in the context of $B$ modes, but little attention has been given to the delensing of the temperature and $E$ modes. In this paper, we model the expected delensed $T$ and $E$ power spectra to all orders in the lensing potential, demonstrating the sharpening of the acoustic peaks and a significant reduction in lens-induced power spectrum covariances. We then perform cosmological forecasts, demonstrating that delensing will yield improved sensitivity to parameters with upcoming surveys. We highlight the breaking of the degeneracy between the effective number of neutrino species and primordial h...
Interchange mode excited by trapped energetic ions
Energy Technology Data Exchange (ETDEWEB)
Nishimura, Seiya, E-mail: n-seiya@kobe-kosen.ac.jp [Kobe City College of Technology, Kobe, Hyogo 651-2194 (Japan)
2015-07-15
The kinetic energy principle describing the interaction between ideal magnetohydrodynamic (MHD) modes with trapped energetic ions is revised. A model is proposed on the basis of the reduced ideal MHD equations for background plasmas and the bounce-averaged drift-kinetic equation for trapped energetic ions. The model is applicable to large-aspect-ratio toroidal devices. Specifically, the effect of trapped energetic ions on the interchange mode in helical systems is analyzed. Results show that the interchange mode is excited by trapped energetic ions, even if the equilibrium states are stable to the ideal interchange mode. The energetic-ion-induced branch of the interchange mode might be associated with the fishbone mode in helical systems.
Mode Switching and Filtering in Nanowire Lasers.
Röder, Robert; Sidiropoulos, Themistoklis P H; Buschlinger, Robert; Riediger, Max; Peschel, Ulf; Oulton, Rupert F; Ronning, Carsten
2016-04-13
Coherent light sources confining the light below the vacuum wavelength barrier will drive future concepts of nanosensing, nanospectroscopy, and photonic circuits. Here, we directly image the angular emission of such a light source based on single semiconductor nanowire lasers. It is confirmed that the lasing switches from the fundamental mode in a thin ZnO nanowire to an admixture of several transverse modes in thicker nanowires approximately at the multimode cutoff. The mode competition with higher order modes substantially slows down the laser dynamics. We show that efficient photonic mode filtering in tapered nanowires selects the desired fundamental mode for lasing with improved performance including power, efficiency, and directionality important for an optimal coupling between adjacent nanophotonic waveguides.
Classical Coupled Mode Theory of Optomechanical Crystals
Khorasani, Sina
2016-01-01
Acousto-optic interaction in optomechanical crystals allows unidirectional control of elastic waves over optical waves. However, as a result of this nonlinear interaction, infinitely many optical modes are born. This article presents an exact formulaion of coupled mode theory for interaction between elastic Bloch wave waves and photonic Bloch waves moving in a phonotonic waveguide. In general, an optical wavefront is strongly diffracted by an elastic wave in frequency and wavevector, and thus infinite modes with different frequencies and wavevectors appear. We discuss resonance and mode conversion conditions, and present a rigorous method to derive coupling rates and mode profiles. We also find a conservation law which rules over total optical power from interacting individual modes. Modifications of the theory to phonotonic cavities are also discussed. We present application examples including switch, frequency shifter, and reflector.
Surface acoustic wave mode conversion resonator
Martin, S. J.; Gunshor, R. L.; Melloch, M. R.; Datta, S.; Pierret, R. F.
1983-08-01
The fact that a ZnO-on-Si structure supports two distinct surface waves, referred to as the Rayleigh and the Sezawa modes, if the ZnO layer is sufficiently thick is recalled. A description is given of a unique surface wave resonator that operates by efficiently converting between the two modes at the resonant frequency. Since input and output coupling is effected through different modes, the mode conversion resonator promises enhanced out-of-band signal rejection. A Rayleigh wave traversing the resonant cavity in one direction is reflected as a Sezawa wave. It is pointed out that the off-resonance rejection of the mode conversion resonator could be enhanced by designing the transducers to minimize the level of cross coupling between transducers and propagating modes.
Mode analysis of numerical geodynamo models
Schrinner, Martin; Hoyng, Peter
2011-01-01
It has been suggested in Hoyng (2009) that dynamo action can be analysed by expansion of the magnetic field into dynamo modes and statistical evaluation of the mode coefficients. We here validate this method by analysing a numerical geodynamo model and comparing the numerically derived mean mode coefficients with the theoretical predictions. The model belongs to the class of kinematically stable dynamos with a dominating axisymmetric, antisymmetric with respect to the equator and non-periodic fundamental dynamo mode. The analysis requires a number of steps: the computation of the so-called dynamo coefficients, the derivation of the temporally and azimuthally averaged dynamo eigenmodes and the decomposition of the magnetic field of the numerical geodynamo model into the eigenmodes. For the determination of the theoretical mode excitation levels the turbulent velocity field needs to be projected on the dynamo eigenmodes. We compare the theoretically and numerically derived mean mode coefficients and find reason...
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.
Multi-Mode Broadband Patch Antenna
Romanofsky, Robert R. (Inventor)
2001-01-01
A multi-mode broad band patch antenna is provided that allows for the same aperture to be used at independent frequencies such as reception at 19 GHz and transmission at 29 GHz. Furthermore, the multi-mode broadband patch antenna provides a ferroelectric film that allows for tuning capability of the multi-mode broadband patch antenna over a relatively large tuning range. The alternative use of a semiconductor substrate permits reduced control voltages since the semiconductor functions as a counter electrode.
Lateral Modes in Quantum Cascade Lasers
Directory of Open Access Journals (Sweden)
Gregory C. Dente
2016-03-01
Full Text Available We will examine the waveguide mode losses in ridge-guided quantum cascade lasers. Our analysis illustrates how the low-loss mode for broad-ridge quantum cascade lasers (QCLs can be a higher-order lateral waveguide mode that maximizes the feedback from the sloped ridge-wall regions. The results are in excellent agreement with the near- and far-field data taken on broad-ridge-guided quantum cascade lasers processed with sloped ridge walls.
Generalised Hermite-Gaussian beams and mode transformations
Wang, Yi; Zhang, Yanfeng; Chen, Hui; Yu, Siyuan
2016-01-01
Generalised Hermite-Gaussian modes (gHG modes), an extended notion of Hermite-Gaussian modes (HG modes), are formed by the summation of normal HG modes with a characteristic function $\\alpha$, which can be used to unite conventional HG modes and Laguerre-Gaussian modes (LG modes). An infinite number of normalised orthogonal modes can thus be obtained by modulation of the function $\\alpha$. The gHG mode notion provides a useful tool in analysis of the deformation and transformation phenomena occurring in propagation of HG and LG modes with astigmatic perturbation.
Research of the Power Plant Operational Modes
Directory of Open Access Journals (Sweden)
Koismynina Nina M.
2017-01-01
Full Text Available In this article the algorithm of the power plant operational modes research is offered. According to this algorithm the program for the modes analysis and connection power transformers choice is developed. The program can be used as educational means for studying of the power plant electric part, at the same time basic data are provided. Also the program can be used for the analysis of the working power plants modes. Checks of the entered data completeness and a choice correctness of the operational modes are provided in the program; in all cases of a deviation from the correct decisions to the user the relevant information is given.
Active control of multiple resistive wall modes
Brunsell, P. R.; Yadikin, D.; Gregoratto, D.; Paccagnella, R.; Liu, Y. Q.; Bolzonella, T.; Cecconello, M.; Drake, J. R.; Kuldkepp, M.; Manduchi, G.; Marchiori, G.; Marrelli, L.; Martin, P.; Menmuir, S.; Ortolani, S.; Rachlew, E.; Spizzo, G.; Zanca, P.
2005-12-01
A two-dimensional array of saddle coils at Mc poloidal and Nc toroidal positions is used on the EXTRAP T2R reversed-field pinch (Brunsell P R et al 2001 Plasma Phys. Control. Fusion 43 1457) to study active control of resistive wall modes (RWMs). Spontaneous growth of several RWMs with poloidal mode number m = 1 and different toroidal mode number n is observed experimentally, in agreement with linear MHD modelling. The measured plasma response to a controlled coil field and the plasma response computed using the linear circular cylinder MHD model are in quantitive agreement. Feedback control introduces a linear coupling of modes with toroidal mode numbers n, n' that fulfil the condition |n - n'| = Nc. Pairs of coupled unstable RWMs are present in feedback experiments with an array of Mc × Nc = 4 × 16 coils. Using intelligent shell feedback, the coupled modes are generally not controlled even though the field is suppressed at the active coils. A better suppression of coupled modes may be achieved in the case of rotating modes by using the mode control feedback scheme with individually set complex gains. In feedback with a larger array of Mc × Nc = 4 × 32 coils, the coupling effect largely disappears, and with this array, the main internal RWMs n = -11, -10, +5, +6 are all simultaneously suppressed throughout the discharge (7 8 wall times). With feedback there is a two-fold extension of the pulse length, compared to discharges without feedback.
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.
$\\mathcal{PT}$-symmetric mode-locking
Longhi, Stefano
2016-01-01
Parity-time ($\\mathcal{PT}$) symmetry is one of the most important accomplishments in optics over the past decade. Here the concept of $\\mathcal{PT}$ mode-locking of a laser is introduced, in which active phase locking of cavity axial modes is realized by asymmetric mode coupling in a complex time crystal. $\\mathcal{PT}$ mode-locking shows a transition from single to double pulse emission as the $\\mathcal{PT}$ symmetry breaking point is crossed. The transition can show a turbulent behavior, depending on a dimensionless modulation parameter that plays the same role as the Reynolds number in hydrodynamic flows.
Mode coupling in spin torque oscillators
Energy Technology Data Exchange (ETDEWEB)
Zhang, Steven S.-L., E-mail: ZhangShule@missouri.edu [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); Zhou, Yan, E-mail: yanzhou@hku.hk [Department of Physics, The University of Hong Kong, Hong Kong (China); Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong (China); Li, Dong, E-mail: geodesic.ld@gmail.com [Department of Physics, Centre for Nonlinear Studies, and Beijing-Hong Kong-Singapore Joint Centre for Nonlinear and Complex Systems, Hong Kong Baptist University, Kowloon Tong, Hong Kong (China); Heinonen, Olle, E-mail: heinonen@anl.gov [Material Science Division, Argonne National Laboratory, Lemont, IL 60439 (United States); Northwestern-Argonne Institute of Science and Technology, 2145 Sheridan Road, Evanston, IL 60208 (United States); Computation Institute, The Unversity of Chicago, 5735 S Ellis Avenue, Chicago, IL 60637 (United States)
2016-09-15
A number of recent experimental works have shown that the dynamics of a single spin torque oscillator can exhibit complex behavior that stems from interactions between two or more modes of the oscillator, such as observed mode-hopping or mode coexistence. There has been some initial work indicating how the theory for a single-mode (macro-spin) spin torque oscillator should be generalized to include several modes and the interactions between them. In the present work, we rigorously derive such a theory starting with the Landau–Lifshitz–Gilbert equation for magnetization dynamics by expanding up to third-order terms in deviation from equilibrium. Our results show how a linear mode coupling, which is necessary for observed mode-hopping to occur, arises through coupling to a magnon bath. The acquired temperature dependence of this coupling implies that the manifold of orbits and fixed points may shift with temperature. - Highlights: • Deriving equations for coupled modes in spin torque oscillators. • Including Hamiltonian formalism and elimination of three–magnon processes. • Thermal bath of magnons central to mode coupling. • Numerical examples of circular and elliptical devices.
Sliding mode control for mobile welding robot
Institute of Scientific and Technical Information of China (English)
Lü Xueqin; Zhang Ke; Wu Yixiong
2006-01-01
The sliding mode controller of mobile welding robot is established in this paper through applying the method of variable structure control with sliding mode into the control of the mobile welding robot.The traditional switching function smooth method is improved by combining the smoothed switching function with the time-varying control gain.It is shown that the proposed sliding mode controller is robust to bounded external disturbances.Experimental results demonstrate that sliding mode controller algorithm can be used into seam tracking and the tracking system is stable with bounded uncertain disturbance.In the seam tracking process, the robot moves steadily without any obvious chattering.
Dark propagation modes in optical lattices
Schiavoni, M; Carminati, F R; Renzoni, F; Grynberg, G; Schiavoni, Michele; Sanchez-Palencia, Laurent; Carminati, Francois-Regis; Renzoni, Ferruccio; Proxy, Gilbert Grynberg; ccsd-00000108, ccsd
2002-01-01
We examine the stimulated light scattering onto the propagation modes of a dissipative optical lattice. We show that two different pump-probe configurations may lead to the excitation, via different mechanisms, of the same mode. We found that in one configuration the scattering on the propagation mode results in a resonance in the probe transmission spectrum while in the other configuration no modification of the scattering spectrum occurs, i.e. the mode is dark. A theoretical explanation of this behaviour is provided.
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.
Measurement equivalence in mixed mode surveys
Directory of Open Access Journals (Sweden)
Joop J. Hox
2015-02-01
Full Text Available Surveys increasingly use mixed mode data collection (e.g., combining face-to-face and web because this controls costs and helps to maintain good response rates. However, a combination of different survey modes in one study, be it cross-sectional or longitudinal, can lead to different kinds of measurement errors. For example, respondents in a face-to-face survey or a web survey may interpret the same question differently, and might give a different answer, just because of the way the question is presented. This effect of survey mode on the question-answer process is called measurement mode effect. This study develops methodological and statistical tools to identify the existence and size of mode effects in a mixed mode survey. In addition, it assesses the size and importance of mode effects in measurement instruments using a specific mixed mode panel survey (Netherlands Kinship Panel Study. Most measurement instruments in the NKPS are multi-item scales, therefore confirmatory factor analysis (CFA will be used as the main analysis tool, using propensity score methods to correct for selection effects.The results show that the NKPS scales by and large have measurement equivalence, but in most cases only partial measurement equivalence. Controlling for respondent differences on demographic variables, and on scale scores from the previous uni-mode measurement occasion, tends to improve measurement equivalence, but not for all scales. The discussion ends with a review of the implications of our results for analyses employing these scales.
Correlations between locked modes and impurity influxes
Energy Technology Data Exchange (ETDEWEB)
Fishpool, G.M. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Lawson, K.D. [UKAEA Culham Lab., Abingdon (United Kingdom)
1994-07-01
An analysis of pulses that were disturbed by medium Z impurity influxes (Cl, Cr, Fe and Ni) recorded during the 91/92 JET operations, has demonstrated that such influxes can result in MHD modes which subsequently ``lock``. A correlation is found between the power radiated by the influx and the time difference between the start of the influx and the beginning of the locked mode. The growth in the amplitude of the locked mode itself can lead to further impurity influxes. A correlation is noted between intense influxes (superior to 10 MW) and the mode ``unlocking``. (authors). 4 refs., 4 figs.
Theory of Acoustic Raman Modes in Proteins
DeWolf, Timothy; Gordon, Reuven
2016-09-01
We present a theoretical analysis that associates the resonances of extraordinary acoustic Raman (EAR) spectroscopy [Wheaton et al., Nat. Photonics 9, 68 (2015)] with the collective modes of proteins. The theory uses the anisotropic elastic network model to find the protein acoustic modes, and calculates Raman intensity by treating the protein as a polarizable ellipsoid. Reasonable agreement is found between EAR spectra and our theory. Protein acoustic modes have been extensively studied theoretically to assess the role they play in protein function; this result suggests EAR spectroscopy as a new experimental tool for studies of protein acoustic 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....
Transverse multibunch modes for non-rigid bunches, including mode coupling
Energy Technology Data Exchange (ETDEWEB)
Berg, J.S.; Ruth, R.D. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)
1996-08-01
A method for computing transverse multibunch growth rates and frequency shifts in rings, which has been described previously, is applied to the PEP-II B factory. The method allows multibunch modes with different internal-bunch oscillation modes to couple to one another, similar to single-bunch mode coupling. Including coupling between the multibunch modes gives effects similar to those seen in single-bunch mode coupling. These effects occur at currents that are lower than the single-bunch mode coupling threshold. (author)
Transverse multibunch modes for non-rigid bunches, including mode coupling
Energy Technology Data Exchange (ETDEWEB)
Bert, J.S.; Ruth, R.D.
1995-08-01
A method for computing transverse multibunch growth rates and frequency shifts in rings, which has been described previously, is applied to the PEP-II B factory. The method allows multibunch modes with different internal-bunch oscillation modes to couple to one another, similar to single-bunch mode coupling. Including coupling between the multibunch modes gives effects similar to those seen in single-bunch mode coupling. These effects occur at currents that are lower than the single-bunch mode coupling threshold.
Liu, Changming; Wei, Xuli; Niu, Liting; Wang, Kejia; Yang, Zhengang; Liu, Jinsong
2016-06-13
We present an efficient method to discriminate orbital angular momentum (OAM) of the terahertz (THz) vortex beam using a diffractive mode transformer. The mode transformer performs a log-polar coordinate transformation of the input THz vortex beam, which consists of two 3D-printed diffractive elements. A following lens separates each transformed OAM mode to a different lateral position in its focal plane. This method enables a simultaneous measurement over multiple OAM modes of the THz vortex beam. We experimentally demonstrate the measurement of seven individual OAM modes and two multiplexed OAM modes, which is in good agreement with simulations.
Compartmented mode workstation (CMW) comparisons
Energy Technology Data Exchange (ETDEWEB)
Tolliver, J.S.
1995-12-31
As the Compartmented Mode Workstation (CMW) market has matured, several vendors have released new versions of their CMW operating systems. These include a new version from SecureWare (CMW + Version 2.4), and Sun`s CMW 1.1 (also known as Trusted Solaris 1.1). EC is now shipping MLS+ 3.0 for DEC Alpha platforms. Relatively new entries in the market include Loral B1/CMW for IBM RS/6000 platforms and a SecureWare-based CMW for HP platforms (HP-UX 10.09). With all these choices it is time for a comparative analysis of the features offered by the various vendors. The authors have three of the above five CMW systems plus HP-UX BLS 9.09, which is a multilevel secure operating system (OS) targeted at the B1 level but not a CMW. Each is unique in sometimes obvious, sometimes subtle ways, a situation that requires knowing and keeping straight a variety of commands to do the same thing on each system. Some vendors offer extensive GUI tools for system administration; some require entering command-line commands for certain system administration tasks. They examine the differences in system installation, system administration, and system operating among the systems. They look at trusted networking among the various systems and differences in the network databases and label encodings files. They examine the user interface on the various systems from logging in to logging out.
The relationship between acoustic radiation modes and structural modes and its applications
Institute of Scientific and Technical Information of China (English)
LI Shuang; CHEN Ke'an
2007-01-01
Both acoustic radiation modes and structural modes play an important role in the field of structure-borne sound, however, little work has been done for inherent relations between these two kinds of modes. This paper is focused on the relationship between the radiation modes and structural modes and its physical mechanisms. First, a governing equation for relating the radiation mode and structural mode is given based on the characteristics of the modes. Then, using the symmetric or anti-symmetric properties of two kinds of modes, the corresponding relations are presented. And then, numerical examples are given to verify the theoretical investigations, and it has been shown that, for a simply supported rectangular panel vibrating at low frequencies, the first radiation mode is dominant corresponding to (odd, odd)structural modes; the following radiation modes are respectively dominant corresponding to (even, odd), (odd, even), and (even, even) structural modes. Finally, such relations are applied to active acoustic structural control and provide a direct help for the design of active control strategy and arrangement of the secondary forces.
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.
Mode coupling in hybrid square-rectangular lasers for single mode operation
Ma, Xiu-Wen; Huang, Yong-Zhen; Yang, Yue-De; Xiao, Jin-Long; Weng, Hai-Zhong; Xiao, Zhi-Xiong
2016-08-01
Mode coupling between a square microcavity and a Fabry-Pérot (FP) cavity is proposed and demonstrated for realizing single mode lasers. The modulations of the mode Q factor as simulation results are observed and single mode operation is obtained with a side mode suppression ratio of 46 dB and a single mode fiber coupling loss of 3.2 dB for an AlGaInAs/InP hybrid laser as a 300-μm-length and 1.5-μm-wide FP cavity connected to a vertex of a 10-μm-side square microcavity. Furthermore, tunable single mode operation is demonstrated with a continuous wavelength tuning range over 10 nm. The simple hybrid structure may shed light on practical applications of whispering-gallery mode microcavities in large-scale photonic integrated circuits and optical communication and interconnection.
Intermodal Raman Scattering between Full Vectorial Modes in Few Moded Fiber
DEFF Research Database (Denmark)
Rishøj, Lars Søgaard; Ramachandran, Siddharth; Rottwitt, Karsten
2013-01-01
We experimentally investigate intermodal Raman interaction. The pump is in the fundamental mode, HE11, and the signal is in either of two full vectorial modes, TM01 or TE01. The on-off gain is approximately 3 dB for both modes, using 4 km of few-moded fiber and 400 mW of pump power.......We experimentally investigate intermodal Raman interaction. The pump is in the fundamental mode, HE11, and the signal is in either of two full vectorial modes, TM01 or TE01. The on-off gain is approximately 3 dB for both modes, using 4 km of few-moded fiber and 400 mW of pump power....
Edström, Krister
1998-01-01
An initialization algorithm for the continuous states in mode switching systems is shown to give correct initial values. The mode switching systems are modeled with switched bond graphs, and the proof is based on singular perturbation theory.
Edström, Krister
1998-01-01
An initialization algorithm for the continuous states in mode switching systems is shown to give correct initial values. The mode switching systems are modeled with switched bond graphs, and the proof is based on the singular perturbation theory.
Flexible Modes Control Using Sliding Mode Observers: Application to Ares I
Shtessel, Yuri B.; Hall, Charles E.; Baev, Simon; Orr, Jeb S.
2010-01-01
The launch vehicle dynamics affected by bending and sloshing modes are considered. Attitude measurement data that are corrupted by flexible modes could yield instability of the vehicle dynamics. Flexible body and sloshing modes are reconstructed by sliding mode observers. The resultant estimates are used to remove the undesirable dynamics from the measurements, and the direct effects of sloshing and bending modes on the launch vehicle are compensated by means of a controller that is designed without taking the bending and sloshing modes into account. A linearized mathematical model of Ares I launch vehicle was derived based on FRACTAL, a linear model developed by NASA/MSFC. The compensated vehicle dynamics with a simple PID controller were studied for the launch vehicle model that included two bending modes, two slosh modes and actuator dynamics. A simulation study demonstrated stable and accurate performance of the flight control system with the augmented simple PID controller without the use of traditional linear bending filters.
New Edge Coherent Mode Providing Continuous Transport in Long Pulse H-mode Plasmas
DEFF Research Database (Denmark)
Wang, H.Q.; Xu, G.S.; Wan, B.N.
2014-01-01
An electrostatic coherent mode near the electron diamagnetic frequency (20–90 kHz) is observed in the steep-gradient pedestal region of long pulse H-mode plasmas in the Experimental Advanced Super-conducting Tokamak, using a newly developed dual gas-puff-imaging system and diamond-coated reciproc......An electrostatic coherent mode near the electron diamagnetic frequency (20–90 kHz) is observed in the steep-gradient pedestal region of long pulse H-mode plasmas in the Experimental Advanced Super-conducting Tokamak, using a newly developed dual gas-puff-imaging system and diamond......-coated reciprocating probes. The mode propagates in the electron diamagnetic direction in the plasma frame with poloidal wavelength of ∼8 cm. The mode drives a significant outflow of particles and heat as measured directly with the probes, thus greatly facilitating long pulse H-mode sustainment. This mode shows...
Statistical dynamo theory: Mode excitation.
Hoyng, P
2009-04-01
We compute statistical properties of the lowest-order multipole coefficients of the magnetic field generated by a dynamo of arbitrary shape. To this end we expand the field in a complete biorthogonal set of base functions, viz. B= summation operator_{k}a;{k}(t)b;{k}(r) . The properties of these biorthogonal function sets are treated in detail. We consider a linear problem and the statistical properties of the fluid flow are supposed to be given. The turbulent convection may have an arbitrary distribution of spatial scales. The time evolution of the expansion coefficients a;{k} is governed by a stochastic differential equation from which we infer their averages a;{k} , autocorrelation functions a;{k}(t)a;{k *}(t+tau) , and an equation for the cross correlations a;{k}a;{l *} . The eigenfunctions of the dynamo equation (with eigenvalues lambda_{k} ) turn out to be a preferred set in terms of which our results assume their simplest form. The magnetic field of the dynamo is shown to consist of transiently excited eigenmodes whose frequency and coherence time is given by Ilambda_{k} and -1/Rlambda_{k} , respectively. The relative rms excitation level of the eigenmodes, and hence the distribution of magnetic energy over spatial scales, is determined by linear theory. An expression is derived for |a;{k}|;{2}/|a;{0}|;{2} in case the fundamental mode b;{0} has a dominant amplitude, and we outline how this expression may be evaluated. It is estimated that |a;{k}|;{2}/|a;{0}|;{2} approximately 1/N , where N is the number of convective cells in the dynamo. We show that the old problem of a short correlation time (or first-order smoothing approximation) has been partially eliminated. Finally we prove that for a simple statistically steady dynamo with finite resistivity all eigenvalues obey Rlambda_{k}<0 .
Validating Inductive Hypotheses by Mode Inference
Institute of Scientific and Technical Information of China (English)
王志坚
1993-01-01
Sme criteria based on mode inference for validating inductive hypotheses are presented in this paper.Mode inference is caried out mechanically,thus such kind of validation can result in low overhead in consistency check and high efficiency in performance.
Modes of Communication during Jazz Improvisation
Seddon, Frederick A.
2005-01-01
This study investigated modes of communication adopted by six student jazz musicians during rehearsal and performance. Six one-hour rehearsal sessions and a performance were observed and videotaped for analysis. Results revealed six modes of communication that formed two main categories, verbal and non-verbal, each containing three distinct modes…
Simultaneous Emotions: Entwining Modes in Children's Books
Cadden, Mike
2005-01-01
Critics and teachers tend to pay attention to genre and ignore mode as an area of consideration. This study examines three novels for young readers that are comparable in terms of their entwining opposing modes (irony and romance, comedy and tragedy) as a successful crossover strategy for appeal to readers young and old. I share implications for…
Mode Contributions to the Casimir Effect
Intravaia, F.; Henkel, C.
2010-04-01
Applying a sum-over-modes approach to the Casimir interaction between two plates with finite conductivity, we isolate and study the contributions of surface plasmons and Foucault (eddy current) modes. We show in particular that for the TE-polarization eddy currents provide a repulsive force that cancels, at high temperatures, the Casimir free energy calculated with the plasma model.
Line-mode browser development days
Anna Pantelia
2013-01-01
Twelve talented web developers have travelled to CERN from all over the world to recreate a piece of web history: the line-mode browser. See the line-mode browser simulator that they created here. Read more about the birth of the web here.
Research on Selection of Equipment Maintenance Modes
Institute of Scientific and Technical Information of China (English)
SHANG Wen-li; SHI Hai-bo; HE Bai-tao
2006-01-01
The development of equipment maintenance management is introduced, and equipment maintenance concept is defined. Equipment maintenance modes are classified, analyzed and compared, which merits and demerits are pointed out. At last, a decision-making frame to select equipment maintenance modes is advanced, and steps to select and implement equipment maintenance are given.
Mode contributions to the Casimir effect
Intravaia, Francesco
2009-01-01
Applying a sum-over-modes approach to the Casimir interaction between two plates with finite conductivity, we isolate and study the contributions of surface plasmons and Foucault (eddy current) modes. We show in particular that for the TE-polarization eddy currents provide a repulsive force that cancels, at high temperatures, the Casimir free energy calculated with the plasma model.
On-chip mode division multiplexing technologies
DEFF Research Database (Denmark)
Ding, Yunhong; Frellsen, Louise Floor; Guan, Xiaowei
2016-01-01
using one-dimensional (1D) photonic crystal silicon waveguides. We furthermore use the fabricated devices to demonstrate on-chip point-to-point mode division multiplexing transmission, and all-optical signal processing by mode-selective wavelength conversion. Finally, we report an efficient silicon...
An Abnormal Vibrational Mode of Torsion Pendulum
Institute of Scientific and Technical Information of China (English)
赵亮; 涂英; 顾邦明; 胡忠坤; 罗俊
2003-01-01
In the experiment for the determination of the gravitational constant G, we found an abnormal vibrational mode of the torsion pendulum. The abnormal mode disappeared as a magnetic damper was introduced to the torsion pendulum system. Our experimental results also show that the magnetic damper can be used to suppress the high frequency vibrational noises to torsion pendulums effectively.
Spatial Extent of Random Laser Modes
Molen, van der Karen L.; Tjerkstra, R. Willem; Mosk, Allard P.; Lagendijk, Ad
2007-01-01
We have experimentally studied the distribution of the spatial extent of modes and the crossover from essentially single-mode to distinctly multimode behavior inside a porous gallium phosphide random laser. This system serves as a paragon for random lasers due to its exemplary high index contrast. I
EMISAR single pass topographic SAR interferometer modes
DEFF Research Database (Denmark)
Madsen, Søren Nørvang; Skou, Niels; Woelders, Kim
1996-01-01
The Danish Center for Remote Sensing (DCRS) has augmented its dual-frequency polarimetric synthetic aperture radar system (EMISAR) with single pass across-track interferometric (XTI) modes. This paper describes the system configuration, specifications and the operating modes. Analysis of data...
Normalizable fermion modes in a holographic superconductor
Gubser, Steven S; Talavera, Pedro
2009-01-01
We consider fermions in a zero-temperature superconducting anti-de Sitter domain wall solution and find continuous bands of normal modes. These bands can be either partially filled or totally empty and gapped. We present a semi-classical argument which approximately captures the main features of the normal mode spectrum.
Measurement equivalence in mixed mode surveys
Hox, Joop; de Leeuw, Edith; Zijlmans, Eva
2015-01-01
Surveys increasingly use mixed mode data collection (e.g., combining face-to-face and web) because this controls costs and helps to maintain good response rates. However, a combination of different survey modes in one study, be it cross-sectional or longitudinal, can lead to different kinds of measu
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
Broadband Radiation Modes: Estimation and Active Control
Berkhoff, Arthur P.
2002-01-01
In this paper we give a formulation of the most efficiently radiating vibration patterns of a vibrating body, the radiation modes, in the time domain. The radiation modes can be used to arrive at efficient weighting schemes for an array of sensors in order to reduce the controller dimensionality. Be
Spatial mode discrimination using second harmonic generation
DEFF Research Database (Denmark)
Delaubert, Vincent; Lassen, Mikael Østergaard; Pulford, David
2007-01-01
Second harmonic generation can be used as a technique for controlling the spatial mode structure of optical beams. We demonstrate experimentally the generation of higher order spatial modes, and that it is possible to use nonlinear phase matching as a predictable and robust technique for the conv...
Predicting the Diversity of Foreign Entry Modes
DEFF Research Database (Denmark)
Hashai, Niron; Geisler Asmussen, Christian; Benito, Gabriel;
2007-01-01
diversity across value chain activities and host markets. Analyzing a sample of Israeli based firms we show that larger firms exhibit a higher degree of entry mode diversity both across value chain activities and across host markets. Higher levels of knowledge intensity are also associated with more...... diversity in firms' entry modes across both dimensions....
Experimental investigation on flow modes of electrospinning
Institute of Scientific and Technical Information of China (English)
Ting Si; Guang-Bin Li; Xing-Xing Chen; Rui-Jun Tian; Xie-Zhen Yin
2012-01-01
Electrospinning experiments are performed by using a set of experimental apparatus,a stroboscopic system is adopted for capturing instantaneous images of the conejet configuration.The cone and the jet of aqueous solutions of polyethylene oxide (PEO) are formed from an orifice of a capillary tube under the electric field.The viscoelastic constitutive relationship of the PEO solution is measured and discussed.The phenomena owing to the jet instability are described,five flow modes and corresponding structures are obtained with variations of the fluid flow rate Q,the electric potential U and the distance h from the orifice of the capillary tube to the collector.The flow modes of the cone-jet configuration involves the steady bending mode,the rotating bending mode,the swinging rotating mode,the blurring bending mode and the branching mode.Regimes in the Q-U plane of the flow modes are also obtained.These results may provide the fundamentals to predict the operating conditions expected in practical applications.
PRECISELY COMPENSATED EFFICIENT COMPONENT MODE SYNTHESIS METHOD
Institute of Scientific and Technical Information of China (English)
Zhu Yutian; Ichiro Hagiwara
2004-01-01
Based on the improved mode superposition method proposed by Z.D.Ma and I.Hagiwara, a precisely compensated efficient mode synthesis method is developed.The calculation procedure is discussed in detail and the truncation error is also analyzed.By comparison, it is shown that this method has a higher accuracy and a less calculation time than the general used ones.
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.
Modal sensitivity analysis for single mode operation in large mode area fiber
Sévigny, Benoit; Zhang, Xiaoxing; Garneau, Marc; Faucher, Mathieu; Lizé, Yannick Keith; Holehouse, Nigel
2008-02-01
Most of the current large mode area (LMA) fibers are few-moded designs using a large, low numerical aperture (N.A.) core, which promotes mode coupling between core modes and increases bending losses (coupling with claddingmodes), which is undesirable both in terms ofmode area and beamquality. Furthermore, short LMA fiber lengths and small cladding diameters are needed to minimize nonlinear effects and maximize pump absorption respectively in high-power pulsed laser systems. Although gain fiber coiling is a widely used technique to filter-out unwanted modes in LMA fibers, coupling between modes can still occur in component leads and relay fibers. In relay fiber, light coupled into higher-order modes can subsequently be lost in the coiling or continue as higher-order modes, which has the overall effect of reducing the effective transmission of the LP 01 mode and degrading the beam quality. However, maximum transmission of the LP 01 mode is often required in order to have the best possible beam quality (minimal M2). Launching in an LMA fiber with a mode field adapter (MFA)1 provides an excellent way of ensuring maximum LP 01 coupling, but preservation of this mode requires highmodal stability in the output fiber. Small cladding, low N.A. LMA fibers have the disadvantage of being extremely sensitive to external forces in real-life applications, which is unwanted for systems where highly sensitive mode coupling can occur. In this paper, we present a detailed experimental and theoretical analysis of mode coupling sensitivity in LMA fibers as a function of fiber parameters such as N.A., core diameter and cladding diameter. Furthermore, we present the impact of higher N.A. as a solution to increase mode stability in terms of its effect on peak power, effective mode area and coupling efficiency.
Operating modes of superconducting tunnel junction device
Energy Technology Data Exchange (ETDEWEB)
Maehata, Keisuke [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering
1998-07-01
In the Electrotechnical Laboratory, an Nb type superconducting tunnel junction (STJ) device with 200 x 200 sq. micron in area and super high quality was manufactured. By using 55-fe source, response of this large area STJ to X-ray was measured. In this measurement, two action modes with different output wave height from front amplifier were observed. Then, in this study, current-voltage feature of the element in each action mode was analyzed to elucidate a mechanism to form such two action modes. The feature was analyzed by using first order approximate solution on cavity resonance mode of Sine-Gordon equation. From the analytical results, it could be supposed that direction and magnitude of effective magnetic field penetrating into jointed area changed by an induction current effect owing to impressing speed of the magnetic field, which brings two different current-voltage features to make possible to observe two action modes with different pulse wave height. (G.K.)
Quantum interference between transverse spatial waveguide modes
Mohanty, Aseema; Zhang, Mian; Dutt, Avik; Ramelow, Sven; Nussenzveig, Paulo; Lipson, Michal
2017-01-01
Integrated quantum optics has the potential to markedly reduce the footprint and resource requirements of quantum information processing systems, but its practical implementation demands broader utilization of the available degrees of freedom within the optical field. To date, integrated photonic quantum systems have primarily relied on path encoding. However, in the classical regime, the transverse spatial modes of a multi-mode waveguide have been easily manipulated using the waveguide geometry to densely encode information. Here, we demonstrate quantum interference between the transverse spatial modes within a single multi-mode waveguide using quantum circuit-building blocks. This work shows that spatial modes can be controlled to an unprecedented level and have the potential to enable practical and robust quantum information processing. PMID:28106036
Quantum interference between transverse spatial waveguide modes
Mohanty, Aseema; Zhang, Mian; Dutt, Avik; Ramelow, Sven; Nussenzveig, Paulo; Lipson, Michal
2017-01-01
Integrated quantum optics has the potential to markedly reduce the footprint and resource requirements of quantum information processing systems, but its practical implementation demands broader utilization of the available degrees of freedom within the optical field. To date, integrated photonic quantum systems have primarily relied on path encoding. However, in the classical regime, the transverse spatial modes of a multi-mode waveguide have been easily manipulated using the waveguide geometry to densely encode information. Here, we demonstrate quantum interference between the transverse spatial modes within a single multi-mode waveguide using quantum circuit-building blocks. This work shows that spatial modes can be controlled to an unprecedented level and have the potential to enable practical and robust quantum information processing.
Normal modes of confined cold ionic systems
Energy Technology Data Exchange (ETDEWEB)
Schiffer, J.P.; Dubin, D.H. [Univ. of California, San Diego, CA (United States)
1995-08-01
The normal modes of a cloud of confined ions forming a strongly-correlated plasma were investigated. The results of molecular-dynamics simulations were compared to predictions of a cold fluid mode. Mode frequencies are observed to shift slightly compared to the cold fluid predictions, and the modes are also observed to damp in time. Simulations also reveal a set of torsional oscillations which have no counterpart in cold fluid theory. The frequency shift, damping, and torsional effects are compared to a model that treats trapped plasmas as a visco-elastic spheroid. It may be possible to measure high-frequency bulk and shear moduli of a strongly-correlated plasma from mode excitation experiments on trapped non-neutral plasmas. An example of the results of the calculation is presented.
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.
Transportation Modes Classification Using Sensors on Smartphones.
Fang, Shih-Hau; Liao, Hao-Hsiang; Fei, Yu-Xiang; Chen, Kai-Hsiang; Huang, Jen-Wei; Lu, Yu-Ding; Tsao, Yu
2016-08-19
This paper investigates the transportation and vehicular modes classification by using big data from smartphone sensors. The three types of sensors used in this paper include the accelerometer, magnetometer, and gyroscope. This study proposes improved features and uses three machine learning algorithms including decision trees, K-nearest neighbor, and support vector machine to classify the user's transportation and vehicular modes. In the experiments, we discussed and compared the performance from different perspectives including the accuracy for both modes, the executive time, and the model size. Results show that the proposed features enhance the accuracy, in which the support vector machine provides the best performance in classification accuracy whereas it consumes the largest prediction time. This paper also investigates the vehicle classification mode and compares the results with that of the transportation modes.
Transportation Modes Classification Using Sensors on Smartphones
Directory of Open Access Journals (Sweden)
Shih-Hau Fang
2016-08-01
Full Text Available This paper investigates the transportation and vehicular modes classification by using big data from smartphone sensors. The three types of sensors used in this paper include the accelerometer, magnetometer, and gyroscope. This study proposes improved features and uses three machine learning algorithms including decision trees, K-nearest neighbor, and support vector machine to classify the user’s transportation and vehicular modes. In the experiments, we discussed and compared the performance from different perspectives including the accuracy for both modes, the executive time, and the model size. Results show that the proposed features enhance the accuracy, in which the support vector machine provides the best performance in classification accuracy whereas it consumes the largest prediction time. This paper also investigates the vehicle classification mode and compares the results with that of the transportation modes.
Emergency Linkage Mode of Power Enterprise
Directory of Open Access Journals (Sweden)
Feng Jie
2016-01-01
Full Text Available Power emergency disposal needs take full advantage of the power enterprise within the external emergency power and resources. Based on analyzing and summarizing the relevant experience of domestic and foreign emergency linkage, this paper draws the Emergency Linkage subjects, Emergency Linkage contents, Emergency Linkage level, which are three key elements if power enterprise Emergency Linkage. Emergency Linkage subjects are divided into the two types of inner subjects and the external body; Emergency Linkage contents are in accordance with four phases of prevention, preparedness, response and recovery; Emergency Linkage level is divided into three levels of enterprise headquarter, provincial enterprise and incident unite. Binding power enterprise emergency management practice, this paper studies the internal Emergency Linkage modes (including horizontal mode and vertical mode, external Emergency Linkage mode and comprehensive Emergency Linkage Mode of power enterprise based on Fishbone Diagram and Process Management Technology.
Preparation of topological modes by Lyapunov control.
Shi, Z C; Zhao, X L; Yi, X X
2015-09-08
By Lyapunov control, we present a proposal to drive quasi-particles into a topological mode in quantum systems described by a quadratic Hamiltonian. The merit of this control is the individual manipulations on the boundary sites. We take the Kitaev's chain as an illustration for Fermi systems and show that an arbitrary excitation mode can be steered into the Majorana zero mode by manipulating the chemical potential of the boundary sites. For Bose systems, taking the noninteracting Su-Schrieffer-Heeger (SSH) model as an example, we illustrate how to drive the system into the edge mode. The sensitivity of the fidelity to perturbations and uncertainties in the control fields and initial modes is also examined. The experimental feasibility of the proposal and the possibility to replace the continuous control field with square wave pulses is finally discussed.
Frequency doubling perimetry screening mode compared to the full-threshold mode
Stoutenbeek, R; Heeg, GP; Jansonius, NM
2004-01-01
The diagnostic performance of the frequency doubling perimetry (FDT) C20-1 screening mode was compared to that of the C20 full-threshold mode. For the number of defects p <1% in the total deviation plot, both modes appeared to perform similarly in terms of sensitivity, specificity, and area under th
A Bloch mode expansion approach for analyzing quasi-normal modes in open nanophotonic structures
DEFF Research Database (Denmark)
de Lasson, Jakob Rosenkrantz; Kristensen, Philip Trøst; Mørk, Jesper;
2014-01-01
to conventional techniques. The quasi-normal modes are determined by constructing a cavity roundtrip matrix and iterating the complex mode wavelength towards a unity eigenvalue. We demonstrate the method by deter- mining quasi-normal modes of cavities in two-dimensional photonic crystals side-coupled to W1...
Even nanomechanical modes transduced by integrated photonics
Energy Technology Data Exchange (ETDEWEB)
Westwood-Bachman, J. N.; Diao, Z.; Sauer, V. T. K.; Hiebert, W. K., E-mail: wayne.hiebert@nrc-cnrc.gc.ca [Department of Physics, University of Alberta, Edmonton T6G 2E1 (Canada); National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton T6G 2M9 (Canada); Bachman, D. [Department of Electrical Engineering, University of Alberta, Edmonton T6G 2V4 (Canada)
2016-02-08
We demonstrate the actuation and detection of even flexural vibrational modes of a doubly clamped nanomechanical resonator using an integrated photonics transduction scheme. The doubly clamped beam is formed by releasing a straight section of an optical racetrack resonator from the underlying silicon dioxide layer, and a step is fabricated in the substrate beneath the beam. The step causes uneven force and responsivity distribution along the device length, permitting excitation and detection of even modes of vibration. This is achieved while retaining transduction capability for odd modes. The devices are actuated via optical force applied with a pump laser. The displacement sensitivities of the first through third modes, as obtained from the thermomechanical noise floor, are 228 fm Hz{sup −1/2}, 153 fm Hz{sup −1/2}, and 112 fm Hz{sup −1/2}, respectively. The excitation efficiency for these modes is compared and modeled based on integration of the uneven forces over the mode shapes. While the excitation efficiency for the first three modes is approximately the same when the step occurs at about 38% of the beam length, the ability to tune the modal efficiency of transduction by choosing the step position is discussed. The overall optical force on each mode is approximately 0.4 pN μm{sup −1} mW{sup −1}, for an applied optical power of 0.07 mW. We show a potential application that uses the resonant frequencies of the first two vibrational modes of a buckled beam to measure the stress in the silicon device layer, estimated to be 106 MPa. We anticipate that the observation of the second mode of vibration using our integrated photonics approach will be useful in future mass sensing experiments.
Few-mode and large-mode-area fiber with circularly distributed cores
Jin, Wenxing; Ren, Guobin; Jiang, Youchao; Wu, Yue; Xu, Yao; Yang, Yuguang; Shen, Ya; Ren, Wenhua; Jian, Shuisheng
2017-03-01
In this paper, a novel few-mode large-mode-area fiber is proposed. This type of fiber consists of 11 conventional cores and 8 air-hole cores circularly arranged around the center core. Few-mode condition equal to strict dual-mode here is available by appropriate adjusting on corepitch, relative refractive index difference and core radius. Large effective area of fundamental mode around 1403.561 μm2 could be achieved by optimization of structural parameters. Bending loss less than 10-3 dB / m is realized when effective area is over 1400 μm2.
Dipole modes with depressed amplitudes in red giants are mixed modes
Mosser, B.; Belkacem, K.; Pinçon, C.; Takata, M.; Vrard, M.; Barban, C.; Goupil, M.-J.; Kallinger, T.; Samadi, R.
2017-02-01
Context. Seismic observations with the space-borne Kepler mission have shown that a number of evolved stars exhibit low-amplitude dipole modes, which is referred to as depressed modes. Recently, these low amplitudes have been attributed to the presence of a strong magnetic field in the stellar core of those stars. Subsequently, and based on this scenario, the prevalence of high magnetic fields in evolved stars has been inferred. It should be noted, however, that this conclusion remains indirect. Aims: We intend to study the properties of mode depression in evolved stars, which is a necessary condition before reaching conclusions about the physical nature of the mechanism responsible for the reduction of the dipole mode amplitudes. Methods: We perform a thorough characterization of the global seismic parameters of depressed dipole modes and show that these modes have a mixed character. The observation of stars showing dipole mixed modes that are depressed is especially useful for deriving model-independent conclusions on the dipole mode damping. We use a simple model to explain how mode visibilities are connected to the extra damping seen in depressed modes. Results: Observations prove that depressed dipole modes in red giants are not pure pressure modes but mixed modes. This result, observed in more than 90% of the bright stars (mV ≤ 11), invalidates the hypothesis that depressed dipole modes result from the suppression of the oscillation in the radiative core of the stars. Observations also show that, except for visibility, seismic properties of the stars with depressed modes are equivalent to those of normal stars. The measurement of the extra damping that is responsible for the reduction of mode amplitudes, without any prior on its physical nature, potentially provides an efficient tool for elucidating the mechanism responsible for the mode depression. Conclusions: The mixed nature of the depressed modes in red giants and their unperturbed global seismic
Field flatness tuning of TM110 mode cavities with closely spaced modes
Energy Technology Data Exchange (ETDEWEB)
Leo Bellantoni et al.
2003-10-31
Superconducting cavities for the CKM RF separated kaon beamline at Fermilab have modes that are closely spaced compared to the resonance bandwidths when warm, and this complicates the field flatness (warm) tuning process. Additionally, it is necessary to maintain the azimuthal orientation of the mode during the tuning deformations. the authors present two analytic techniques to warm-tune cavities with overlapping modes, a finite-element analysis of the tuning process, the design of a warm tuner which maintains mode polarization, and the results of tuning a cavity in which initial manufacturing variations caused the desired {pi} and nearby {pi}-1 modes to be indistinguishable before field flatness tuning.
Absorption mode FTICR mass spectrometry imaging.
Smith, Donald F; Kilgour, David P A; Konijnenburg, Marco; O'Connor, Peter B; Heeren, Ron M A
2013-12-03
Fourier transform ion cyclotron resonance mass spectrometry offers the highest mass resolving power for molecular imaging experiments. This high mass resolving power ensures that closely spaced peaks at the same nominal mass are resolved for proper image generation. Typically higher magnetic fields are used to increase mass resolving power. However, a gain in mass resolving power can also be realized by phase correction of the data for absorption mode display. In addition to mass resolving power, absorption mode offers higher mass accuracy and signal-to-noise ratio over the conventional magnitude mode. Here, we present the first use of absorption mode for Fourier transform ion cyclotron resonance mass spectrometry imaging. The Autophaser algorithm is used to phase correct each spectrum (pixel) in the image, and then, these parameters are used by the Chameleon work-flow based data processing software to generate absorption mode "Datacubes" for image and spectral viewing. Absorption mode reveals new mass and spatial features that are not resolved in magnitude mode and results in improved selected ion image contrast.
New modes of assisted mechanical ventilation.
Suarez-Sipmann, F
2014-05-01
Recent major advances in mechanical ventilation have resulted in new exciting modes of assisted ventilation. Compared to traditional ventilation modes such as assisted-controlled ventilation or pressure support ventilation, these new modes offer a number of physiological advantages derived from the improved patient control over the ventilator. By implementing advanced closed-loop control systems and using information on lung mechanics, respiratory muscle function and respiratory drive, these modes are specifically designed to improve patient-ventilator synchrony and reduce the work of breathing. Depending on their specific operational characteristics, these modes can assist spontaneous breathing efforts synchronically in time and magnitude, adapt to changing patient demands, implement automated weaning protocols, and introduce a more physiological variability in the breathing pattern. Clinicians have now the possibility to individualize and optimize ventilatory assistance during the complex transition from fully controlled to spontaneous assisted ventilation. The growing evidence of the physiological and clinical benefits of these new modes is favoring their progressive introduction into clinical practice. Future clinical trials should improve our understanding of these modes and help determine whether the claimed benefits result in better outcomes.
Institute of Scientific and Technical Information of China (English)
LI Sheng; ZHAO Deyou
2004-01-01
Modal analysis of structural acoustic radiation from a vibrating structure is discussed using structural vibration modes and acoustic radiation modes based on the quadratic form of acoustic power. The finite element method is employed for discretisizing the structure.The boundary element method and Rayleigh integral are used for modeling the acoustic fluid.It is shown that the power radiated by a single vibration mode is to increase the radiated power and the effect of modal interaction can lead to an increase or a decrease or no change in the radiated power, moreover, control of vibration modes is a good way to reduce both vibration and radiated sound as long as the influence of interaction of vibration modes on sound radiation is insignificant. Stiffeners may change mode shapes of a plate and thus change radiation efficiency of the plate's modes. The CHIEF method is adopted to obtain an acoustic radiation mode formulation without the nonuniqueness difficulty at critical frequencies for three-dimensional structures by using Moore-Penrose inverse. A pulsating cube is involved to verify the formulation. Good agreement is obtained between the numerical and analytical solutions. The shapes and radiation efficiencies of acoustic radiation modes of the cube are discussed. The structural acoustic control using structural vibration modes and acoustic radiation modes are compared and studied.
Experimental verification of microbending theory using mode coupling to discrete cladding modes
DEFF Research Database (Denmark)
Probst, C. B.; Bjarklev, Anders Overgaard; Andreasen, S. B.
1989-01-01
The existence of discrete cladding modes in single-mode fibers is illustrated by inducing periodically repeated microbends along the fiber axis and performing spectral measurements of the loss are performed. In order to explain the results of the measurements, it is necessary to apply a microbend......The existence of discrete cladding modes in single-mode fibers is illustrated by inducing periodically repeated microbends along the fiber axis and performing spectral measurements of the loss are performed. In order to explain the results of the measurements, it is necessary to apply...... a microbending theory in which coupling between the guided mode and a number of discrete cladding modes is considered. Very good agreement between theory and measurement is achieved. The consequences of the existence of discrete cladding modes with regard to the proper choice of artificial microbending spectrum...
Transverse-mode controlling of a large-mode-area multimode fiber laser
Institute of Scientific and Technical Information of China (English)
Libo Li; Qihong Lou; Jun Zhou; Jingxing Dong; Yunrong Wei; Bing He; Jinyan Li
2007-01-01
@@ Coiling technique is used to control the transverse mode of a large-mode-area (LMA) multimode fiber laser. By winding the fiber to a coil with different radius, high-order modes of a multimode fiber laser are suppressed one by one and finally 15.4-W single-transverse-mode output is achieved when the coil radius is 20 mm. It is found that as the coil radius decreases, the beam quality of a multimode fiber laser gets better but the slope efficiency drops for higher-order modes are discriminated. During the experiment, as the coil radius of multimode fiber changes, output characteristic of the laser has been measured. Meanwhile,the mode loss of different modes is calculated theoretically. It is proved that the experimental measured results fit well with the theoretically calculated results.
Low-bending loss and single-mode operation in few-mode optical fiber
Yin, Ping; Wang, Hua; Chen, Ming-Yang; Wei, Jin; Cai, Zhi-Min; Li, Lu-Ming; Yang, Ji-Hai; Zhu, Yuan-Feng
2016-10-01
The technique of eliminating the higher-order modes in a few-mode optical fiber is proposed. The fiber is designed with a group of defect modes in the cladding. The higher-order modes in the fiber can be eliminated by bending the fiber to induce strong coupling between the defect modes and the higher-order modes. Numerical simulation shows the bending losses of the LP01 mode are lower than 1.5×10-4 dB/turn for the wavelength shorter than 1.625 μm. The proposed fiber can be bent multiple turns at small bending radius which are preferable for FTTH related applications.
Damping of toroidal ion temperature gradient modes
Energy Technology Data Exchange (ETDEWEB)
Sugama, H. [National Inst. for Fusion Science, Toki, Gifu (Japan)
1999-04-01
The temporal evolution of linear toroidal ion temperature gradient (ITG) modes is studied based on a kinetic integral equation including an initial condition. It is shown how to evaluate the analytic continuation of the integral kernel as a function of a complex-valued frequency, which is useful for analytical and numerical calculations of the asymptotic damping behavior of the ITG mode. In the presence of the toroidal {nabla}B-curvature drift, the temporal dependence of the density and potential perturbations consists of normal modes and a continuum mode, which correspond to contributions from poles and from an integral along a branch cut, respectively, of the Laplace-transformed potential function of the complex-valued frequency. The normal modes have exponential time dependence with frequencies and growth rates determined by the dispersion relation while the continuum mode, which has a ballooning structure, shows a power law decay {proportional_to} t{sup -2} in the asymptotic limit, where t is the time variable. Therefore, the continuum mode dominantly describes the long-time asymptotic behavior of the density and potential perturbations for the stable system where all normal modes have negative growth rates. By performing proper analytic continuation for the homogeneous version of the kinetic integral equation, dependences of the normal modes` growth rate, real frequency, and eigenfunction on {eta}{sub i} (the ratio of the ion temperature gradient to the density gradient), k{sub {theta}} (the poloidal wavenumber), s (the magnetic shear parameter), and {theta}{sub k} (the ballooning angle corresponding to the minimum radial wavenumber) are numerically obtained for both stable and unstable cases. (author)
Self-mode-locking semiconductor disk laser.
Gaafar, Mahmoud; Richter, Philipp; Keskin, Hakan; Möller, Christoph; Wichmann, Matthias; Stolz, Wolfgang; Rahimi-Iman, Arash; Koch, Martin
2014-11-17
The development of mode-locked semiconductor disk lasers received striking attention in the last 14 years and there is still a vast potential of such pulsed lasers to be explored and exploited. While for more than one decade pulsed operation was strongly linked to the employment of a saturable absorber, self-mode-locking emerged recently as an effective and novel technique in this field - giving prospect to a reduced complexity and improved cost-efficiency of such lasers. In this work, we highlight recent achievements regarding self-mode-locked semiconductor devices. It is worth to note, that although nonlinear effects in the active medium are expected to give rise to self-mode-locking, this has to be investigated with care in future experiments. However, there is a controversy whether results presented with respect to self-mode-locking truly show mode-locking. Such concerns are addressed in this work and we provide a clear evidence of mode-locking in a saturable-absorber-free device. By using a BBO crystal outside the cavity, green light originating from second-harmonic generation using the out-coupled laser beam is demonstrated. In addition, long-time-span pulse trains as well as radiofrequency-spectra measurements are presented for our sub-ps pulses at 500 MHz repetition rate which indicate the stable pulse operation of our device. Furthermore, a long-time-span autocorrelation trace is introduced which clearly shows absence of a pedestal or double pulses. Eventually, a beam-profile measurement reveals the excellent beam quality of our device with an M-square factor of less than 1.1 for both axes, showing that self-mode-locking can be achieved for the fundamental transverse mode.
The radio luminosity function and redshift evolution of radio-mode and quasar-mode AGN
Pracy, Mike
2016-08-01
The properties of the AGN population indicate that there are two fundamentally different accretion modes operating. In the quasar-mode, material is accreted onto the supermassive black hole via a small, thin, optically luminous accretion disc. Accretion in this mode is recognisable by emission lines in the optical spectrum. However, there is a population of AGN observable only by their radio emission and without optical emission lines. These radio-mode AGN are likely powered by radiatively inefficient accretion from a hot gas halo. I will describe the cosmic evolution of these two populations via radio luminosity functions. The radio luminosity functions are constructed from a new survey of over 4000 radio galaxies out to z=1, all with confirmed redshifts and their accretion mode classified from their optical spectra. This is 20 times larger than the only other survey used to make such a measurement. The radio-mode AGN population displays no statistically significant evolution in space density out to redshift z=1. In contrast the quasar mode AGN exhibits rapid evolution in space density, increasing by a factor of 8 over the same redshift range. The characteristic break in the radio luminosity function occurs at a significantly higher power for the quasar-mode AGN in comparison to the radio-mode AGN and we demonstrate this is consistent with the two populations representing fundamentally different accretion modes. The radio luminosity function is used to estimate the total amount of mechanical energy available for radio mode feedback as a function of redshift, and is found to be in good agreement with cosmological models and previous measurements. Again, by separating by accretion mode, the previously estimated increase in available mechanical energy per unit volume out to z=1 (approximately a factor of 2) can be attributed to the rapid evolution of the quasar-mode AGN, while for the classical radio-mode AGN the total mechanical energy output remains roughly
Polarization Dependent Whispering Gallery Modes in Microspheres
Adamovsky, Grigory (Inventor); Wrbanek, Susan Y. (Inventor)
2016-01-01
A tunable resonant system is provided and includes a microsphere that receives an incident portion of a light beam generated via a light source, the light beam having a fundamental mode, a waveguide medium that transmits the light beam from the light source to the microsphere, and a polarizer disposed in a path of the waveguide between the light source and the microsphere. The incident portion of the light beam creates a fundamental resonance inside the microsphere. A change in a normalized frequency of the wavelength creates a secondary mode in the waveguide and the secondary mode creates a secondary resonance inside the microsphere.
Electronic response to nuclear breathing mode
Energy Technology Data Exchange (ETDEWEB)
Ludwig, Hendrik; Ruffini, Remo [ICRANet, P.zza della Repubblica 10, I-65122 Pescara, Italy Dipartimento di Fisica and ICRA, Sapienza Università di Roma P.le Aldo Moro 5, I-00185 Rome (Italy); ICRANet, University of Nice-Sophia Antipolis, 28 Av. de Valrose, 06103 Nice Cedex 2 (France); Xue, She-Sheng [ICRANet, P.zza della Repubblica 10, I-65122 Pescara, Italy Dipartimento di Fisica and ICRA, Sapienza Università di Roma P.le Aldo Moro 5, I-00185 Rome (Italy)
2015-12-17
Based on our previous work on stationary oscillation modes of electrons around giant nuclei, we show how to treat a general driving force on the electron gas, such as the one generated by the breathing mode of the nucleus, by means of the spectral method. As an example we demonstrate this method for a system with Z = 10{sup 4} in β-equilibrium with the electrons compressed up to the nuclear radius. In this case the stationary modes can be obtained analytically, which allows for a very speedy numerical calculation of the final result.
Weibel, Firehose and Mirror mode Relations
Treumann, R A
2014-01-01
Excitation of Weibel magnetic fields in an initially non-magnetized though anisotropic plasma may trigger other low-frequency instabilities fed by pressure anisotropy. It is shown that under Weibel-like-stable conditions the Weibel-like thermal fluctuation magnetic field allows for restricted Firehose-mode growth. In addition, low frequency Whistlers can also propagate in the plasma under certain anisotropic conditions. When the Weibel-like mode becomes unstable, Firehose instability ceases but Mirror modes take over. This will cause bubble structures in the Weibel-like field in addition to filamentation.
Spatial Mode Selective Waveguide with Hyperbolic Cladding
Tang, Y; Xu, M; Bäumer, S; Adam, A J L; Urbach, H P
2016-01-01
Hyperbolic Meta-Materials~(HMMs) are anisotropic materials with permittivity tensor that has both positive and negative eigenvalues. Here we report that by using a type II HMM as cladding material, a waveguide which only supports higher order modes can be achieved, while the lower order modes become leaky and are absorbed in the HMM cladding. This counter intuitive property can lead to novel application in optical communication and photonic integrated circuit. The loss in our HMM-Insulator-HMM~(HIH) waveguide is smaller than that of similar guided mode in a Metal-Insulator-Metal~(MIM) waveguide.
Algebraic description of intrinsic modes in nuclei
Energy Technology Data Exchange (ETDEWEB)
Leviatan, A. (Los Alamos National Lab., NM (USA))
1990-01-01
We present a procedure for extracting normal modes in algebraic number-conserving systems of interacting bosons relevant for collective states in even-even nuclei. The Hamiltonian is resolved into intrinsic (bandhead related) and collective (in-band related) parts. Shape parameters are introduced through non-spherical boson bases. Intrinsic modes decoupled from the spurious modes are obtained from the intrinsic part of the Hamiltonian in the limit of large number of bosons. Intrinsic states are constructed and serve to evaluate electromagnetic transition rates. The method is illustrated for systems with one type of boson as well as with proton-neutron bosons. (author).
Algebraic description of intrinsic modes in nuclei
Energy Technology Data Exchange (ETDEWEB)
Leviatan, A.
1989-01-01
We present a procedure for extracting normal modes in algebraic number-conserving systems of interacting bosons relevant for collective states in even-even nuclei. The Hamiltonian is resolved into intrinsic (bandhead related) and collective (in-band related) parts. Shape parameters are introduced through non-spherical boson bases. Intrinsic modes decoupled from the spurious modes are obtained from the intinsic part of the Hamiltonian in the limit of large number of bosons. Intrinsic states are constructed and serve to evaluate electromagnetic transition rates. The method is illustrated for systems with one type of boson as well as with proton-neutron bosons. 28 refs., 1 fig.
Distortional Modes of Thin-Walled Beams
DEFF Research Database (Denmark)
Jönsson, Jeppe; Andreassen, Michael Joachim
2009-01-01
The classic thin-walled beam theory for open and closed cross-sections can be generalized by including distortional displacement modes. The introduction of additional displacement modes leads to coupled differential equations, which seems to have prohibited the use of exact shape functions...... in the modelling of coupled torsion and distortion. However, if the distortional displacement modes are chosen as those which decouple the differential equations as in non proportionally damped modal dynamic analysis then it may be possible to use exact shape functions and perform analysis on a reduced problem...
Long wave polar modes in semiconductor heterostructures
Trallero-Giner, C; Garca̕-Moliner, F 0
1998-01-01
Long Wave Polar Modes in Semiconductor Heterostructures is concerned with the study of polar optical modes in semiconductor heterostructures from a phenomenological approach and aims to simplify the model of lattice dynamics calculations. The book provides useful tools for performing calculations relevant to anyone who might be interested in practical applications. The main focus of Long Wave Polar Modes in Semiconductor Heterostructures is planar heterostructures (quantum wells or barriers, superlattices, double barrier structures etc) but there is also discussion on the growing field of quan
Distribution of whistler mode bursts at Venus
Scarf, F. L.; Jordan, K. F.; Russell, C. T.
1987-01-01
Several thousand impulsive whistler mode noise bursts were detected by the Pioneer Venus wave instrument during the first 10 seasons with nightside traversals at low altitudes. The altitude distribution for these events shows that essentially all of the bursts were detected when the orbiter was less than 2000 km above the planet, suggesting that the varying plasma conditions could not maintain coherent whistler mode field-aligned guidance over greater distances. Within the 2000-km range, the distribution of the number of events versus altitude shows that there are two distinct subregions. These results are interpreted in terms of two types of whistler mode propagation from sources below the ionosphere.
Quasinormal modes of extremal BTZ black hole
Energy Technology Data Exchange (ETDEWEB)
Crisostomo, Juan; Lepe, Samuel; Saavedra, Joel [Instituto de FIsica, Facultad de Ciencias Basicas y Matematicas, Pontificia Universidad Catolica de ValparaIso, Avenida Brasil 2950, ValparaIso (Chile)
2004-06-21
Motivated by several pieces of evidence, in order to show that extremal black holes cannot be obtained as limits of non-extremal black holes, in this paper we calculate explicitly quasinormal modes for the Banados, Teitelboim and Zanelli (BTZ) extremal black hole and show that the imaginary part of the frequency is zero. We obtain exact result for the scalar and fermionic perturbations. We also showed that the frequency is bounded from below for the existence of the normal modes (non-dissipative modes)
Modes of Homogeneous Barrier Discharge at Atmospheric Pressure in Helium
Institute of Scientific and Technical Information of China (English)
WANG Yan-Hui; WANG De-Zhen
2004-01-01
@@ The discharge modes of a homogeneous barrier discharge at atmospheric pressure in helium are investigated with a one-dimensional fluid model It is found that, either in single peak discharge or in multipeak discharge, there are two discharge modes: glow and Townsend modes. The structure and features of the two modes are compared.The conditions forming the two modes are discussed.
Evidence for distinct modes of solar activity
Usoskin, I G; Gallet, Y; Roth, R; Licht, A; Joos, F; Kovaltsov, G A; Thebault, E; Khokhlov, A
2014-01-01
Aims. The Sun shows strong variability in its magnetic activity, from Grand minima to Grand maxima, but the nature of the variability is not fully understood, mostly because of the insufficient length of the directly observed solar activity records and of uncertainties related to long-term reconstructions. Here we present a new adjustment-free reconstruction of solar activity over three millennia and study its different modes. Methods. We present a new adjustment-free, physical reconstruction of solar activity over the past three millennia, using the latest verified carbon cycle, 14C production, and archeomagnetic field models. This great improvement allowed us to study different modes of solar activity at an unprecedented level of details. Results. The distribution of solar activity is clearly bi-modal, implying the existence of distinct modes of activity. The main regular activity mode corresponds to moderate activity that varies in a relatively narrow band between sunspot numbers about 20 and 67. The exist...
Rotary Mode Core Sample System availability improvement
Energy Technology Data Exchange (ETDEWEB)
Jenkins, W.W.; Bennett, K.L.; Potter, J.D. [Westinghouse Hanford Co., Richland, WA (United States); Cross, B.T.; Burkes, J.M.; Rogers, A.C. [Southwest Research Institute (United States)
1995-02-28
The Rotary Mode Core Sample System (RMCSS) is used to obtain stratified samples of the waste deposits in single-shell and double-shell waste tanks at the Hanford Site. The samples are used to characterize the waste in support of ongoing and future waste remediation efforts. Four sampling trucks have been developed to obtain these samples. Truck I was the first in operation and is currently being used to obtain samples where the push mode is appropriate (i.e., no rotation of drill). Truck 2 is similar to truck 1, except for added safety features, and is in operation to obtain samples using either a push mode or rotary drill mode. Trucks 3 and 4 are now being fabricated to be essentially identical to truck 2.
Mode coupling in organic dye lasers
Energy Technology Data Exchange (ETDEWEB)
Hirth, A.
1973-10-25
Saturable dye triggering is discussed together with relaxation time and pulse duration. The influence of stimulated emission is detailed. Experimental results of mode coupling with cyanines and xanthines, flash excited and not, are reported.
Interaction-Induced Mode Switching in Microlasers
Ge, Li; Johnson, Steven G; Rotter, Stefan; Tureci, Hakan E; Cerjan, Alexander; Cao, Hui; Stone, A Douglas
2016-01-01
We demonstrate that due to strong modal interactions through cross-gain saturation, the onset of a new lasing mode can switch off an existing mode via a negative power slope. In this process of interaction-induced mode switching (IMS) the two involved modes maintain their identities, i.e. they do not change their spatial field patterns or lasing frequencies. For a fixed pump profile, a simple analytic criterion for the occurrence of IMS is given in terms of their self- and cross-interaction coefficients and non-interacting thresholds, which is verified for the example of a two-dimensional microdisk laser. When the spatial pump profile is varied as the pump power is increased, IMS can be induced even when it would not occur with a fixed pump profile, as we show for two coupled laser cavities. Our findings may have potential applications in robust and flexible all-optical switching.
Cohesive mixed mode fracture modelling and experiments
DEFF Research Database (Denmark)
Walter, Rasmus; Olesen, John Forbes
2008-01-01
A nonlinear mixed mode model originally developed by Wernersson [Wernersson H. Fracture characterization of wood adhesive joints. Report TVSM-1006, Lund University, Division of Structural Mechanics; 1994], based on nonlinear fracture mechanics, is discussed and applied to model interfacial cracking...... in a steel–concrete interface. The model is based on the principles of Hillerborgs fictitious crack model, however, the Mode I softening description is modified taking into account the influence of shear. The model couples normal and shear stresses for a given combination of Mode I and II fracture...... curves, which may be interpreted using the nonlinear mixed mode model. The interpretation of test results is carried out in a two step inverse analysis applying numerical optimization tools. It is demonstrated how to perform the inverse analysis, which couples the assumed individual experimental load...
Dynamic rotor mode in antiferromagnetic nanoparticles
DEFF Research Database (Denmark)
Lefmann, Kim; Jacobsen, H.; Garde, J.;
2015-01-01
. The frequency of the rotor mode behaves in fair agreement with a simple analytical model, based on a high-temperature approximation of the generally accepted Hamiltonian of the system. The extracted model parameters, such as the magnetic interaction and the axial anisotropy, are in excellent agreement......We present experimental, numerical, and theoretical evidence for an unusual mode of antiferromagnetic dynamics in nanoparticles. Elastic neutron scattering experiments on 8-nm particles of hematite display a loss of diffraction intensity with temperature, the intensity vanishing around 150 K...... measured neutron data and reveal that thermally activated spin canting gives rise to an unusual type of coherent magnetic precession mode. This "rotor" mode can be seen as a high-temperature version of superparamagnetism and is driven by exchange interactions between the two magnetic sublattices...
Mode III effects on interface delamination
DEFF Research Database (Denmark)
Tvergaard, Viggo; Hutchinson, J.W.
2008-01-01
mode III has an effect. Subsequently, the focus is on crack growth along an interface between an elastic-plastic solid and an elastic substrate. The analyses are carried out for conditions of small-scale yielding, with the fracture process at the interface represented by a cohesive zone model. Due......For crack growth along an interface between dissimilar materials the effect of combined modes I, II and III at the crack-tip is investigated. First, in order to highlight situations where crack growth is affected by a mode III contribution, examples of material configurations are discussed where...... to the mismatch of elastic properties across the interface the corresponding elastic solution has an oscillating stress singularity, and this solution is applied as boundary conditions on the outer edge of the region analyzed. For several combinations of modes I, II and III crack growth resistance curves...
Development of Mode Conversion Waveguides at KIT
Directory of Open Access Journals (Sweden)
Jin Jianbo
2015-01-01
Full Text Available The development of mode conversion waveguides (launchers for high power gyrotrons has gone through three stages at KIT. Formerly, harmonically deformed launchers have been used in the series gyrotrons developed for the stellarator W7-X. In 2009, a numerical method for the analysis and synthesis of mirror-line launchers was developed at KIT. Such a launcher with adapted mode-converting mirrors for a 2 MW TE34,19-mode, 170GHz coaxial-cavity gyrotron has been designed and tested, and also a mirror-line launcher for the 1MW EU ITER gyrotron has been designed. Recently, based on the Helmholtz-Kirchhoff integral theorem, a novel numerical method for the synthesis of hybrid-type gyrotron launchers has been developed. As an example, TE32,9 mode launchers operating at 170GHz that have been designed using the three different methods are being compared.
Literature Review on Context Translation Mode
Institute of Scientific and Technical Information of China (English)
褚杨杨
2016-01-01
The theory context translation mode a new theory concerning context involves three dimensions including communicative dimension, pragmatic dimension and semiotic dimension. This paper aims to explain the progress of its development.
Nanofabricated Optomechanical Whispering Gallery Mode Resonators Project
National Aeronautics and Space Administration — Strong interest in whispering gallery mode resonators (WGMR) for use in chip-scale photonic devices is motivated by their high optical quality, mechanical simplicity...
Zero modes in finite range magnetic fields
Adam, C; Nash, C
2000-01-01
We find a class of Fermion zero modes of Abelian Dirac operators in three dimensional Euclidean space where the gauge potentials and the related magnetic fields are nonzero only in a finite space region.
Nuclear scissors modes and hidden angular momenta
Balbutsev, E B; Schuck, P
2016-01-01
The coupled dynamics of low lying modes and various giant resonances are studied with the help of the Wigner Function Moments method generalized to take into account spin degrees of freedom and pair correlations simultaneously. The method is based on Time Dependent Hartree-Fock-Bogoliubov equations. The model of the harmonic oscillator including spin-orbit potential plus quadrupole-quadrupole and spin-spin interactions is considered. New low lying spin dependent modes are analyzed. Special attention is paid to the scissors modes. A new source of nuclear magnetism, connected with counter-rotation of spins up and down around the symmetry axis (hidden angular momenta), is discovered. Its inclusion into the theory allows one to improve substantially the agreement with experimental data in the description of energies and transition probabilities of scissors modes.
The Female and Male Modes of Rhetoric.
Farrell, Thomas J.
1979-01-01
Analyzes the ways several women have written persuasive discourse and identifies a female rhetorical mode involving indirection, open-endedness, additive attention to small details, restraint, and noncombativeness. (DD)
Quasinormal Modes of the Draining Bathtub
Oliveira, Leandro A.; Crispino, Luís C. B.; Dolan, Sam R.
2015-01-01
We present an investigation of the quasinormal modes of the draining bathtub using three different methods, namely: finite difference, continued fraction and geodesic expansion. We compare the results obtained with these different approaches.
Transition from an antiphase error-correction mode to a synchronization mode in mutual hand tracking
Hayashi, Yoshikatsu; Sawada, Yasuji
2013-08-01
Proactive motion in hand tracking and in finger bending, in which the body motion occurs prior to the reference signal, has been previously reported when a periodic target signal was shown to the subjects at relatively high frequencies. These phenomena indicate that the human sensory-motor system tends to choose an anticipatory mode rather than a reactive mode, when the target motion is relatively fast. The present research was undertaken to study what kind of mode appears in the sensory-motor system when two persons were asked to track the hand position of the partner at various mean tracking frequency. The experimental results showed that a transition from a mutual error-correction mode to a synchronization mode occurred in the same region of the transition frequency with the one from a reactive error-correction mode to a proactive anticipatory mode reported previously in the target tracking experiments of the single subjects. Present research indicated that synchronization of body motion occurred only when both of the pair subjects operated in a proactive anticipatory mode. We also presented mathematical models to explain the behavior of the error-correction mode and the synchronization mode.
Mode group specific amplification length in an asymmetric LPG assisted few-mode EDFA
Rastogi, Vipul; Gaur, Ankita; Aschieri, Pierre; Dussardier, Bernard
2017-01-01
This article presents a scheme for few-mode EDFA, which allows to choose independent amplification lengths for different mode groups. The EDF is a dual concentric core fiber, where the central core is connected to the line FMF and the ring core is doped with erbium to provide amplification. The modes of FMF are launched into the central core of the EDF, are converted into ring modes using LPG for amplification and then converted back into central core modes using another LPG. The distance between the LPGs determines the amplification length. The amplification length, can thus, be chosen for a given mode group. We demonstrate the working of this concept by choosing LP11 and LP21 mode groups of the FMF and show that a suitable choice of amplification lengths for the two mode groups can tailor the differential modal gain (DMG) to any desired value. We demonstrate achieving zero DMG among all the mode of LP11 and LP21 mode groups using this concept while having gain in excess of 20 dB. The study should be useful for optical fiber communication system employing space-division multiplexing (SDM).
An automatic mode-locked system for passively mode-locked fiber laser
Li, Sha; Xu, Jun; Chen, Guoliang; Mei, Li; Yi, Bo
2013-12-01
This paper designs and implements one kind of automatic mode-locked system. It can adjust a passively mode-locked fiber laser to keep steady mode-locked states automatically. So the unsteadiness of traditional passively mode-locked fiber laser can be avoided. The system transforms optical signals into electrical pulse signals and sends them into MCU after processing. MCU calculates the frequency of the signals and judges the state of the output based on a quick judgment algorithm. A high-speed comparator is used to check the signals and the comparison voltage can be adjusted to improve the measuring accuracy. Then by controlling two polarization controllers at an angle of 45degrees to each other, MCU extrudes the optical fibers to change the polarization until it gets proper mode-locked output. So the system can continuously monitor the output signal and get it back to mode-locked states quickly and automatically. States of the system can be displayed on the LCD and PC. The parameters of the steady mode-locked states can be stored into an EEPROM so that the system will get into mode-locked states immediately next time. Actual experiments showed that, for a 6.238MHz passively mode-locked fiber lasers, the system can get into steady mode-locked states automatically in less than 90s after starting the system. The expected lock time can be reduced to less than 20s after follow up improvements.
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.
OAM mode converter in twisted fibers
DEFF Research Database (Denmark)
Usuga Castaneda, Mario A.; Beltran-Mejia, Felipe; Cordeiro, Cristiano
2014-01-01
We analyze the case of an OAM mode converter based on a twisted fiber, through finite element simulations where we exploit an equivalence between geometric and material transformations. The obtained converter has potential applications in MDM. © 2014 OSA.......We analyze the case of an OAM mode converter based on a twisted fiber, through finite element simulations where we exploit an equivalence between geometric and material transformations. The obtained converter has potential applications in MDM. © 2014 OSA....
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...
Low-Voltage Hall Thruster Mode Transitions
2014-06-01
Technical Paper 3. DATES COVERED (From - To) June 2014- July 2014 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER In-House Low-Voltage Hall Thruster Mode...ABSTRACT Past investigations of the 6kW-class H6 Hall thruster during low-voltage operation revealed two operating modes, corresponding to the...topologies were characterized for the H6 Hall thruster from 100V to 200V discharge, with variation in cathode flow fraction, cathode position inside and
Failure modes in surface micromachined microelectromechanical actuators
Energy Technology Data Exchange (ETDEWEB)
Miller, S.L.; Rodgers, M.S.; LaVigne, G.; Sniegowski, J.J.; Clews, P.; Tanner, D.M.; Peterson, K.A.
1998-03-01
In order for the rapidly emerging field of MicroElectroMechanical Systems (MEMS) to meet its extraordinary expectations regarding commercial impact, issues pertaining to how they fail must be understood. The authors identify failure modes common to a broad range of MEMS actuators, including adhesion (stiction) and friction induced failures caused by improper operational methods, mechanical instabilities, and electrical instabilities. Demonstrated methods to mitigate these failure modes include implementing optimized designs, model based operational methods, and chemical surface treatments.
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.
Fuzzy Sliding Mode Control of Plate Vibrations
Manu Sharma; Singh, S. P.
2010-01-01
In this paper, fuzzy logic is meshed with sliding mode control, in order to control vibrations of a cantilevered plate. Test plate is instrumented with a piezoelectric sensor patch and a piezoelectric actuator patch. Finite element method is used to obtain mathematical model of the test plate. A design approach of a sliding mode controller for linear systems with mismatched time-varying uncertainties is used in this paper. It is found that chattering around the sliding surface in the sliding ...
Parametric Landau damping of space charge modes
Macridin, Alexandru; Stern, Eric; Amundson, James; Spentzouris, Panagiotis
2016-01-01
Landau damping is the mechanism of plasma and beam stabilization; it is caused by energy transfer from collective modes to incoherent motion of resonant particles. Normally this resonance requires the wave frequency in the particle frame to match the resonant particles frequency. Using the Synergia modeling package to study transverse coherent modes of bunched beams with space charge, we have identified a new kind of damping mechanism, parametric Landau damping, driven by the modulation of the wave-particle interaction.
Thermal condensation mode in a dusty plasma
Indian Academy of Sciences (India)
B P Pandey; J Vranješ; S Parhi
2003-03-01
In the present work, the radiative condensation instability is investigated in the presence of dust charge ﬂuctuations. We ﬁnd that the charge variability of the grain reduces the growth rate of radiative mode only for ﬂuctuation wavelength smaller or of the order of the Debye length and this reduction is not very large. Far from the Debye sphere, radiative mode can damp due to thermal conduction of electrons and ions.
Mode resolved density of atmospheric aerosol particles
Directory of Open Access Journals (Sweden)
P. Aalto
2008-09-01
Full Text Available In this study, we investigate the mode resolved density of ultrafine atmospheric particles measured in boreal forest environment. The method used here enables us to find the distinct density information for each mode in atmospheric fine particle population: the density values for nucleation, Aitken, and accumulation mode particles are presented. The experimental data was gained during 2 May 2005–19 May 2005 at the boreal forest measurement station "SMEAR II" in Hyytiälä, Southern Finland. The density values for accumulation mode varied from 1.1 to 2 g/cm^{3} (average 1.5 g/cm^{3} and for Aitken mode from 0.4 to 2 g/cm^{3} (average 0.97 g/cm^{3}. As an overall trend during the two weeks campaign, the density value of Aitken mode was seen to gradually increase. With the present method, the time dependent behaviour of the particle density can be investigated in the time scale of 10 min. This allows us to follow the density evolution of the nucleation mode particles during the particle growth process following the nucleation burst. The density of nucleation mode particles decreased during the growth process. The density values for 15 nm particles were 1.2–1.5 g/cm^{3} and for grown 30 nm particles 0.5–1 g/cm^{3}. These values are consistent with the present knowledge that the condensing species are semi-volatile organics, emitted from the boreal forest.
Three lepton decay modes of the proton
O'Donnell, Patrick J.; Sarkar, Utpal
1993-01-01
We consider the three lepton decay modes of the proton within the proton decay interpretation of the atmospheric neutrino anomaly. We construct higher dimensional operators in the framework of the standard model. The operators which allow the particularly interesting decay mode are of dimension 10 involving $SU(2)_L$ non-singlet higgs. We show how these operators can be comparable to the dimension 9 operators. We then present a simple left-right symmetric model which can give rise to the desi...
Third abrasive wear mode: is it possible?
Directory of Open Access Journals (Sweden)
Ronaldo Câmara Cozza
2014-04-01
Full Text Available The objective of this paper is to propose an initial discussion on the characterization of a third abrasive wear mode. The results obtained in a previous work [1] under different test conditions revealed the occurrence of the superposition of the “rolling” and “grooving” abrasive wear modes. This phenomenon was denoted “micro-rolling abrasion” due to the observation that “rolling abrasion” was found to act on “grooving abrasion”.
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.
Enhanced Sleep Mode MAC Control for EPON
DEFF Research Database (Denmark)
Yan, Ying; Dittmann, Lars
2011-01-01
This paper introduces sleep mode operations for EPON. New MAC control functions are proposed to schedule sleep periods. Traffic profiles are considered to optimize energy efficiency and network performances. Simulation results are analyzed in OPNET modeler.......This paper introduces sleep mode operations for EPON. New MAC control functions are proposed to schedule sleep periods. Traffic profiles are considered to optimize energy efficiency and network performances. Simulation results are analyzed in OPNET modeler....
Chaos control using sliding-mode theory
Energy Technology Data Exchange (ETDEWEB)
Nazzal, Jamal M. [Faculty of Engineering, Al-Ahliyya Amman University, Post Code 19328 Amman (Jordan)]. E-mail: jnazzal@ammanu.edu.jo; Natsheh, Ammar N. [Faculty of Engineering, Al-Ahliyya Amman University, Post Code 19328 Amman (Jordan)
2007-07-15
Chaos control means to design a controller that is able to mitigating or eliminating the chaos behavior of nonlinear systems that experiencing such phenomenon. In this paper, a nonlinear Sliding-Mode Controller (SMC) is presented. Two nonlinear chaotic systems are chosen to be our case study in this paper, the well known Chua's circuit and Lorenz system. The study shows the effectiveness of the designed nonlinear Sliding-Mode Controller.
MDM: A Mode Diagram Modeling Framework
Directory of Open Access Journals (Sweden)
Zheng Wang
2012-12-01
Full Text Available Periodic control systems used in spacecrafts and automotives are usually period-driven and can be decomposed into different modes with each mode representing a system state observed from outside. Such systems may also involve intensive computing in their modes. Despite the fact that such control systems are widely used in the above-mentioned safety-critical embedded domains, there is lack of domain-specific formal modelling languages for such systems in the relevant industry. To address this problem, we propose a formal visual modeling framework called mode diagram as a concise and precise way to specify and analyze such systems. To capture the temporal properties of periodic control systems, we provide, along with mode diagram, a property specification language based on interval logic for the description of concrete temporal requirements the engineers are concerned with. The statistical model checking technique can then be used to verify the mode diagram models against desired properties. To demonstrate the viability of our approach, we have applied our modelling framework to some real life case studies from industry and helped detect two design defects for some spacecraft control systems.
Particle Distribution Modification by Low Amplitude Modes
Energy Technology Data Exchange (ETDEWEB)
White, R. B.; Gorelenkov, N.; Heidbrink, W. W.; Van Zeeland, M. A.
2009-08-28
Modification of a high energy particle distribution by a spectrum of low amplitude modes is investigated using a guiding center code. Only through resonance are modes effective in modifying the distribution. Diagnostics are used to illustrate the mode-particle interaction and to find which effects are relevant in producing significant resonance, including kinetic Poincare plots and plots showing those orbits with time averaged mode-particle energy transfer. Effects of pitch angle scattering and drag are studied, as well as plasma rotation and time dependence of the equilibrium and mode frequencies. A specific example of changes observed in a DIII-D deuterium beam distribution in the presence of low amplitude experimentally validated Toroidal Alfven (TAE) eigenmodes and Reversed Shear Alfven (RSAE) eigenmodes is examined in detail. Comparison with experimental data shows that multiple low amplitude modes can account for significant modification of high energy beam particle distributions. It is found that there is a stochastic threshold for beam profile modification, and that the experimental amplitudes are only slightly above this threshold.
Modes of storage ring coherent instabilities
Energy Technology Data Exchange (ETDEWEB)
Wang, J.M.
1986-12-01
Longitudinal impedance in a beam and various modes of longitudinal coherent instabilities are discussed. The coasting beam coherent instability, microwave instability, and single-bunch longitudinal coherent instabilities are considered. The Vlasov equation is formulated, and a method of solving it is developed. The synchrotron modes are treated, which take the possible bunch shape distortion fully into consideration. A method of treating the synchrotron mode coupling in the case of a small bunch is discussed which takes advantage of the fact that only a few of the synchrotron modes can contribute in such a case. The effect of many bunches on the coherent motion of the beam and the longitudinal symmetric coupled bunch modes are discussed. The transverse impedance is then introduced, and the transverse coasting beam instability is discussed. Various bunched beam instabilities are discussed, including both single bunch instabilities and coupled bunch instabilities. The Vlasov equation for transverse as well as longitudinal motion of particles is introduced as well as a method of solving it within a linear approximation. Head-tail modes and short bunch instabilities and strong coupling instabilities in the long bunch case are covered. (LEW)
Simulation of valveless micropump and mode analysis
Lan, W P; Wu, K C; Shih, Y C
2008-01-01
In this work, a 3-D simulation is performed to study for the solid-fluid coupling effect driven by piezoelectric materials and utilizes asymmetric obstacles to control the flow direction. The result of simulation is also verified. For a micropump, it is crucial to find the optimal working frequency which produce maximum net flow rate. The PZT plate vibrates under the first mode, which is symmetric. Adjusting the working frequency, the maximum flow rate can be obtained. For the micrpump we studied, the optimal working frequency is 3.2K Hz. At higher working frequency, say 20K Hz, the fluid-solid membrane may come out a intermediate mode, which is different from the first mode and the second mode. It is observed that the center of the mode drifts. Meanwhile, the result shows that a phase shift lagging when the excitation force exists in the vibration response. Finally, at even higher working frequency, say 30K Hz, a second vibration mode is observed.
Observations of sausage modes in magnetic pores
Morton, R J; Jess, D B; Mathioudakis, M
2010-01-01
We present here evidence for the observation of the magneto-hydrodynamic (MHD) sausage modes in magnetic pores in the solar photosphere. Further evidence for the omnipresent nature of acoustic global modes is also found. The empirical decomposition method of wave analysis is used to identify the oscillations detected through a 4170 {\\AA} 'blue continuum' filter observed with the Rapid Oscillations in the Solar Atmosphere (ROSA) instrument. Out of phase, periodic behavior in pore size and intensity is used as an indicator of the presence of magneto-acoustic sausage oscillations. Multiple signatures of the magneto-acoustic sausage mode are found in a number of pores. The periods range from as short as 30 s up to 450 s. A number of the magneto-acoustic sausage mode oscillations found have periods of 3 and 5 minutes, similar to the acoustic global modes of the solar interior. It is proposed that these global oscillations could be the driver of the sausage type magneto-acoustic MHD wave modes in pores.
Solar Gravity Modes: Present and Future
Turck-Chièze, S
2005-01-01
Gravity modes are the best probes to study the solar radiative zone dynamics, especially in the nuclear core. These modes remain difficult to observe, but they are essential ingredients for progressing on the evolution of the Sun-Earth relationship at the level of centuries. Today, the knowledge of the internal dynamics comes from acoustic modes and concerns mainly the external 2% of the solar mass. Nevertheless, the flat rotation profile of the radiative zone compels physics beyond the standard framework. I summarize different attempts to look for gravity modes and the results obtained after 8 years of observation with the GOLF/SoHO instrument. Some gravity mode candidates (at 1mm/s level) have appeared with more than 98% confidence level as quadruplets or quintuplets. These patterns, if confirmed as gravity modes, may reveal very exciting physics of the solar core. Getting information on rotation and magnetic field in the solar core are real keys to simulate a complete dynamical solar picture. The understan...
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.
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.
Trapped ion mode in toroidally rotating plasmas
Energy Technology Data Exchange (ETDEWEB)
Artun, M.; Tang, W.M.; Rewoldt, G.
1995-04-01
The influence of radially sheared toroidal flows on the Trapped Ion Mode (TIM) is investigated using a two-dimensional eigenmode code. These radially extended toroidal microinstabilities could significantly influence the interpretation of confinement scaling trends and associated fluctuation properties observed in recent tokamak experiments. In the present analysis, the electrostatic drift kinetic equation is obtained from the general nonlinear gyrokinetic equation in rotating plasmas. In the long perpendicular wavelength limit k{sub {tau}}{rho}{sub bi} {much_lt} 1, where {rho}{sub bi} is the average trapped-ion banana width, the resulting eigenmode equation becomes a coupled system of second order differential equations nmo for the poloidal harmonics. These equations are solved using finite element methods. Numerical results from the analysis of low and medium toroidal mode number instabilities are presented using representative TFTR L-mode input parameters. To illustrate the effects of mode coupling, a case is presented where the poloidal mode coupling is suppressed. The influence of toroidal rotation on a TFTR L-mode shot is also analyzed by including a beam species with considerable larger temperature. A discussion of the numerical results is presented.
Mode crosstalk matrix measurement of a 1 km elliptical core few-mode optical fiber.
Milione, Giovanni; Ip, Ezra; Li, Ming-Jun; Stone, Jefferey; Peng, Gaozhu; Wang, Ting
2016-06-15
The spatial modes of a 1 km elliptical core few-mode optical fiber (6 spatial modes) are analyzed by using liquid crystal on silicon spatial light modulators to measure the fiber's mode crosstalk matrix in Hermite-Gaussian, Laguerre-Gaussian, and linearly polarized spatial mode bases. It is shown that the fiber's spatial modes can be described by Hermite-Gaussian modes, which can propagate 1 km over the optical fiber with <-20 dB (1%) average mode crosstalk even when the fiber has multiple 1 cm diameter bends. The use of elliptical core few-mode optical fibers for space division multiplexing in data centers is discussed.
The Contributions of Bernstein's Sociology to Education Development Research
Sriprakash, Arathi
2011-01-01
Global and national agendas to improve the "quality" of Education For All have brought focus to pedagogic processes in developing country contexts. How can development research pay attention to the social and political significance of pedagogical projects and understand the micro-processes of classroom reform? This paper considers how…
Damage Identification Dependence on Number of Vibration Modes Using Mode Shape Curvature Squares
Janeliukstis, R.; Rucevskis, S.; Wesolowski, M.; Chate, A.
2016-09-01
In this paper a damage identification algorithm for multiple damage sites based on mode shape curvature square method of vibration mode shapes in aluminium beam is reported. The required mode shape curvature of a healthy structure was obtained via interpolation of mode shape curvature of a damaged structure with Fourier series functions of different orders. Algorithm employed calculations of standardized damage index distributions over beam coordinate. Finite element simulations of proposed methodology involving various artificial noise levels and reduction of mode shape input data points were validated on the damage identification results of experimentally measured mode shapes which were measured using scanning laser vibrometer. Results show that the algorithm is capable of capturing the areas of damage. The term called damage estimate reliability was introduced in terms of likelihood of the chosen approximation function to capture the location of damage.
Modes of the Kerr geometry with purely imaginary frequencies
Cook, Gregory B
2016-01-01
In this paper, we examine the behavior of modes of the Kerr geometry when the mode's frequency is purely imaginary. We demonstrate that quasinormal modes must be polynomial in nature if their frequency is purely imaginary, and present a method for computing such modes. The nature of these modes, however, is not always easy to determine. Some of the polynomial modes we compute are quasinormal modes. However, some are simultaneously quasinormal modes and total transmission modes, while others fail to satisfy the requisite boundary conditions for either. This analysis is, in part, an extension of the results known for Schwarzschild black holes, but clarifies misconceptions for the behavior of modes when the black hole has angular momentum. We also show that the algebraically special modes of Kerr with m=0 have an additional branch of solutions not seen before in the literature. All of these results are in precise agreement with new numerical solutions for sequences of gravitational quasinormal modes of Kerr. How...
Directory of Open Access Journals (Sweden)
Boucher Yann G.
2017-01-01
Full Text Available The formal identification between a two-mode waveguide and a system of two mutually coupled single-mode waveguides stems from the symmetries of the evolution operator. When the gap tends to zero, the super-modes of the coupled system merge continuously into the modes of the multimode waveguide. For modelling purposes, it is very tempting to extend the analogy to three-mode waveguides (and beyond. But not without some precautions…
Mode perturbation method for optimal guided wave mode and frequency selection.
Philtron, J H; Rose, J L
2014-09-01
With a thorough understanding of guided wave mechanics, researchers can predict which guided wave modes will have a high probability of success in a particular nondestructive evaluation application. However, work continues to find optimal mode and frequency selection for a given application. This "optimal" mode could give the highest sensitivity to defects or the greatest penetration power, increasing inspection efficiency. Since material properties used for modeling work may be estimates, in many cases guided wave mode and frequency selection can be adjusted for increased inspection efficiency in the field. In this paper, a novel mode and frequency perturbation method is described and used to identify optimal mode points based on quantifiable wave characteristics. The technique uses an ultrasonic phased array comb transducer to sweep in phase velocity and frequency space. It is demonstrated using guided interface waves for bond evaluation. After searching nearby mode points, an optimal mode and frequency can be selected which has the highest sensitivity to a defect, or gives the greatest penetration power. The optimal mode choice for a given application depends on the requirements of the inspection.
Förtsch, Michael; Fürst, Josef U; Strekalov, Dmitry; Gerrits, Thomas; Stevens, Martin J; Sedlmeir, Florian; Schwefel, Harald G L; Nam, Sae Woo; Leuchs, Gerd; Marquardt, Christoph
2014-01-01
We report a highly efficient source of narrow-band photon pairs based on parametric down-conversion in a crystalline whispering gallery mode resonator. Remarkably, each photon of a pair is strictly emitted into a single spatial and temporal mode, as witnessed by Glaubers autocorrelation function. We explore the phase-matching conditions in spherical geometries, and determine the requirements of the single-mode operation. Understanding these conditions has allowed us to experimentally demonstrate a single-mode pair-detection rate of $0.97 \\cdot 10^6$ pairs/s per mW pump power per 20 MHz bandwidth without the need of additional filter cavities.
Single mode lasing in transversely multi-moded PT-symmetric microring resonators
Hodaei, Hoseein; Hassan, Absar U; Hayenga, William E; Heinrich, Matthias; Christodoulides, Demetrios N; Khajavikhan, Mercedeh
2016-01-01
Single mode lasing is experimentally demonstrated in a transversely multi-moded InP-based semiconductor microring arrangement. In this system, mode discrimination is attained by judiciously utilizing the exceptional points in a parity-time (PT) symmetric double microring configuration. The proposed scheme is versatile, robust to small fabrication errors, and enables the device to operate in a stable manner considerably above threshold while maintaining spatial and spectral purity. The results presented here pave the way towards a new class of chip-scale semiconductor lasers that utilize gain/loss contrast as a primary mechanism for mode selection.
Coupled-mode equation of polarization modes of twisted birefringent fibers in a unified coordinate.
Fang, Zujie; Yang, Fei; Cai, Haiwen; Qu, Ronghui
2013-01-20
A coupled-mode equation (CME) of twisted birefringent fiber is presented in this paper, which uses the degenerate polarization modes of single-mode fibers as eigenmodes in a unified coordinate. The inconsistency between the coordinate and the rotating principal axis, existing in the previous CME, is solved by conversion to the lab coordinate. The CME gives self-consistent results for fibers with high birefringence or low birefringence and for single-mode fibers as well. Analyses and simulations show the CME gives characteristics of twisted birefringent fiber coincident with the property of polarization-maintaining fibers.
Mode Conversion of Solar p-Modes in Non-Vertical Magnetic Fields
Crouch, A. D.; Cally, P. S.
2005-03-01
Sunspots absorb and scatter incident f- and p-modes. Until recently, the responsible absorption mechanism was uncertain. The most promising explanation appears to be mode conversion to slow magnetoacoustic-gravity waves, which carry energy down the magnetic field lines into the interior. In vertical magnetic field, mode conversion can adequately explain the observed f-mode absorption, but is too inefficient to account for the absorption of p-modes. In the first paper of the present series we calculated the efficiency of fast-to-slow magnetoacoustic-gravity wave conversion in uniform non-vertical magnetic fields. We assumed two-dimensional propagation, where the Alfvén waves decouple. In comparison to vertical field, it was found that mode conversion is significantly enhanced in moderately inclined fields, especially at higher frequencies. Using those results, Cally, Crouch, and Braun showed that the resultant p-mode absorption produced by simple sunspot models with non-vertical magnetic fields is ample to explain the observations. In this paper, we further examine mode conversion in non-vertical magnetic fields. In particular, we consider three-dimensional propagation, where the fast and slow magnetoacoustic-gravity waves and the Alfvén waves are coupled. Broadly speaking, the p-mode damping rates are not substantially different to the two-dimensional case. However, we do find that the Alfvén waves can remove similar quantities of energy to the slow MAG waves.
All-fiber Raman Probe using Higher Order Modes
DEFF Research Database (Denmark)
Larsen, Stine Højer Møller; Rishøj, Lars Søgaard; Rottwitt, Karsten
2013-01-01
We demonstrate the first all-fiber Raman probe utilizing higher order modes for the excitation. The spectrum of cyclohexane is measured using both the fundamental mode as well as in-fiber-generated Bessel-like modes.......We demonstrate the first all-fiber Raman probe utilizing higher order modes for the excitation. The spectrum of cyclohexane is measured using both the fundamental mode as well as in-fiber-generated Bessel-like modes....
Thermally induced nonlinear mode coupling in high power fiber amplifiers
DEFF Research Database (Denmark)
Johansen, Mette Marie; Hansen, Kristian Rymann; Alkeskjold, Thomas T.;
2013-01-01
Thermally induced nonlinear mode coupling leads to transverse mode instability (TMI) in high power fiber amplifiers. A numerical model including altering mode profiles from thermal effects and waveguide perturbations predicts a TMI threshold of ~200W.......Thermally induced nonlinear mode coupling leads to transverse mode instability (TMI) in high power fiber amplifiers. A numerical model including altering mode profiles from thermal effects and waveguide perturbations predicts a TMI threshold of ~200W....
Standing sausage modes in curved coronal slabs
Pascoe, D. J.; Nakariakov, V. M.
2016-09-01
Context. Magnetohydrodynamic waveguides such as dense coronal loops can support standing modes. The ratios of the periods of oscillations for different longitudinal harmonics depend on the dispersive nature of the waveguide and so may be used as a seismological tool to determine coronal parameters. Aims: We extend models of standing sausage modes in low β coronal loops to include the effects of loop curvature. The behaviour of standing sausage modes in this geometry is used to explain the properties of observed oscillations that cannot be accounted for using straight loop models. Methods: We perform 2D numerical simulations of an oscillating coronal loop, modelled as a dense slab embedded in a potential magnetic field. The loop is field-aligned and so experiences expansion with height in addition to being curved. Standing sausage modes are excited by compressive perturbations of the loop and their properties are studied. Results: The spatial profiles of standing sausage modes are found to be modified by the expanding loop geometry typical for flaring loops and modelled by a potential magnetic field in our simulations. Longitudinal harmonics of order n > 1 have anti-nodes that are shifted towards the loop apex and the amplitude of anti-nodes near the loop apex is smaller than those near the loop footpoints. Conclusions: We find that the observation of standing sausage modes by the Nobeyama Radioheliograph in a flaring coronal loop on 12 January 2000 is consistent with interpretation in terms of the global mode (n = 1) and third harmonic (n = 3). This interpretation accounts for the period ratio and spatial structure of the observed oscillations.
Fiber-guided modes conversion using superposed helical gratings
Ma, Yancheng; Fang, Liang; Wu, Guoan
2017-03-01
Optical fibers can support various modal forms, including vector modes, linear polarization (LP) modes, and orbital angular momentum (OAM) modes, etc. The modal correlation among these modes is investigated via Jones matrix, associated with polarization and helical phase corresponding to spin angular momentum (SAM) and OAM of light, respectively. We can generate different modal forms by adopting superposed helical gratings (SHGs) with opposite helix orientations. Detailed analysis and discussion on mode conversion is given as for mode coupling in optical fibers with both low and high contrast index, respectively. Our study may deepen the understanding for various fiber-guided modes and mode conversion among them via fiber gratings.
[Emergy value evaluation on rice-duck organic farming mode].
Xi, Yunguan; Qin, Pei
2006-02-01
Employing emergy value evaluation method, this paper compared the ecological and economic benefits of rice-duck organic farming system (mode I) and conventional rice-wheat rotation system (mode II) in Shanghai suburb. The results showed that mode I had better emergy benefits, higher self-organizing ability and sustainability, and higher product safety. The net emergy yield ratio (EYR), feedback ratio of yield emergy (FYE), and emergy sustainable index (ESI) of mode I were respectively 1.57, 14.1, and 8.71 times as much as those of mode II, and the emergy index of product safety (EIPS) was 0 in mode I but -0.66 in mode II. The emergy investment ratio (EIR) and environmental loading ratio (ELR) of mode I were 40.1% and 18.3% of mode II, respectively, suggesting that mode I had less environmental pressure than mode II. Mode I had lower economic benefits than mode II. The economic output, gross income, and net income of mode I were 15.7%, 9.6%, and 29.6% less than those of mode II , respectively. As for Em dollars, the output, gross income, and net income of mode I were respectively 50%, 102.6%, and 136.4% higher than those of mode II. With the system optimization and the development of organic food market, mode I had the potential to improve its economic benefits.
Graphene with vacancies: Supernumerary zero modes
Weik, Norman; Schindler, Johannes; Bera, Soumya; Solomon, Gemma C.; Evers, Ferdinand
2016-08-01
The density of states ϱ (E ) of graphene is investigated within the tight-binding (Hückel) approximation in the presence of vacancies. They introduce a nonvanishing density of zero modes nzm that act as midgap states, ϱ (E ) =nzmδ (E ) +smooth . As is well known, the actual number of zero modes per sample can, in principle, exceed the sublattice imbalance, Nzm≥|NA-NB| , where NA,NB denote the number of carbon atoms in each sublattice. In this paper, we establish a stronger relation that is valid in the thermodynamic limit and that involves the concentration of zero modes, nzm>|cA-cB| , where cA and cB denote the concentration of vacancies per sublattice; in particular, nzm is nonvanishing even in the case of balanced disorder, NA/NB=1 . Adopting terminology from benzoid graph theory, the excess modes associated with the current carrying backbone (percolation cluster) are called supernumerary. In the simplest cases, such modes can be associated with structural elements such as carbon atoms connected with a single bond, only. Our result suggests that the continuum limit of bipartite hopping models supports nontrivial "supernumerary" terms that escape the present continuum descriptions.
Competing stability modes in vortex structure formation
Garrett, Stephen; Gostelow, J. Paul; Rona, Aldo; McMullan, W. Andrew
2015-11-01
Nose cones and turbine blades have rotating components and represent very practical geometries for which the behavior of vortex structures is not completely understood. These two different physical cases demonstrate a common theme of competition between mode and vortex types. The literature concerning boundary-layer transition over rotating cones presents clear evidence of an alternative instability mode leading to counter-rotating vortex pairs, consistent with a centrifugal instability. This is in contrast to co-rotating vortices present over rotating disks that arise from crossflow effects. It is demonstrated analytically that this mode competes with the crossflow mode and is dominant only over slender cones. Predictions are aligned with experimental measurements over slender cones. Concurrent experimental work on the flow over swept cylinders shows that organized fine-scale streamwise vorticity occurs more frequently on convex surfaces than is appreciated. The conventional view of purely two-dimensional laminar boundary layers following blunt leading edges is not realistic and such boundary layers need to be treated three-dimensionally, particularly when sweep is present. The vortical structures are counter-rotating for normal cylinders and co-rotating under high sweep conditions. Crossflow instabilities may have a major role to play in the transition process but the streamline curvature mode is still present, and seemingly unchanged, when the boundary layer becomes turbulent.
Multi-Mode Cavity Accelerator Structure
Energy Technology Data Exchange (ETDEWEB)
Jiang, Yong [Yale Univ., New Haven, CT (United States); Hirshfield, Jay Leonard [Omega-P R& D, Inc., New Haven, CT (United States)
2016-11-10
This project aimed to develop a prototype for a novel accelerator structure comprising coupled cavities that are tuned to support modes with harmonically-related eigenfrequencies, with the goal of reaching an acceleration gradient >200 MeV/m and a breakdown rate <10^{-7}/pulse/meter. Phase I involved computations, design, and preliminary engineering of a prototype multi-harmonic cavity accelerator structure; plus tests of a bimodal cavity. A computational procedure was used to design an optimized profile for a bimodal cavity with high shunt impedance and low surface fields to maximize the reduction in temperature rise ΔT. This cavity supports the TM010 mode and its 2nd harmonic TM011 mode. Its fundamental frequency is at 12 GHz, to benchmark against the empirical criteria proposed within the worldwide High Gradient collaboration for X-band copper structures; namely, a surface electric field E_{sur}^{max}< 260 MV/m and pulsed surface heating ΔT^{max}< 56 °K. With optimized geometry, amplitude and relative phase of the two modes, reductions are found in surface pulsed heating, modified Poynting vector, and total RF power—as compared with operation at the same acceleration gradient using only the fundamental mode.
Gyrokinetic simulation of internal kink modes
Energy Technology Data Exchange (ETDEWEB)
Naitou, Hiroshi; Tsuda, Kenji [Yamaguchi Univ., Ube (Japan). Dept. of Electrical and Electronical Engineering; Lee, W.W. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Sydora, R.D. [Univ. of California, Los Angeles, CA (United States). Dept. of Physics
1995-05-01
Internal disruption in a tokamak has been simulated using a three-dimensional magneto-inductive gyrokinetic particle code. The code operates in both the standard gyrokinetic mode (total-f code) and the fully nonlinear characteristic mode ({delta}f code). The latter, a recent addition, is a quiet low noise algorithm. The computational model represents a straight tokamak with periodic boundary conditions in the toroidal direction. The plasma is initially uniformly distributed in a square cross section with perfectly conducting walls. The linear mode structure of an unstable m = 1 (poloidal) and n = 1 (toroidal) kinetic internal kink mode is clearly observed, especially in the {delta}f code. The width of the current layer around the x-point, where magnetic reconnection occurs, is found to be close to the collisionless electron skin depth. This is consistent with the theory in which electron inertia has a dominant role. The nonlinear behavior of the mode is found to be quite similar for both codes. Full reconnection in the Alfven time scale is observed along with the electrostatic potential structures created during the full reconnection phase. The E x B drift due to this electrostatic potential dominates the nonlinear phase of the development after the full reconnection.
Competition and transformation of modes of unidirectional air waveguide
Sun, Yu-xin; Kong, Xiang-kun; Fang, Yun-tuan
2016-10-01
In order to study the mode excitation of the unidirectional air waveguide, we place a line source at different positions in the waveguide. The source position plays an important role in determining the result of the competition of the even mode and the odd mode. For the source at the edge of the waveguide, the odd mode gets advantage over the even mode. As a result, the odd mode is excited, but the even mode is suppressed. For the source at the center of the waveguide, the even mode is excited, but the odd mode is suppressed. With two sources at two edges of the waveguide, the even mode is released because the two odd modes are canceled.
Single transverse mode selectively oxidized vertical cavity lasers
Energy Technology Data Exchange (ETDEWEB)
CHOQUETTE,KENT D.; GEIB,KENT M.; BRIGGS,RONALD D.; ALLERMAN,ANDREW A.; HINDI,JANA JO
2000-04-26
Vertical cavity surface emitting lasers (VCSELs) which operate in multiple transverse optical modes have been rapidly adopted into present data communication applications which rely on multi-mode optical fiber. However, operation only in the fundamental mode is required for free space interconnects and numerous other emerging VCSEL applications. Two device design strategies for obtaining single mode lasing in VCSELs based on mode selective loss or mode selective gain are reviewed and compared. Mode discrimination is attained with the use of a thick tapered oxide aperture positioned at a longitudinal field null. Mode selective gain is achieved by defining a gain aperture within the VCSEL active region to preferentially support the fundamental mode. VCSELs which exhibit greater than 3 mW of single mode output power at 850 nm with mode suppression ratio greater than 30 dB are reported.
Kojima, Yasufumi
2008-01-01
Nonlinear growth of the bar-mode deformation is studied for a differentially rotating star with supercritical rotational energy. In particular, the growth mechanism of some azimuthal modes with odd wave numbers is examined by comparing a simplified mathematical model with a realistic simulation. Mode coupling to even modes, i.e., the bar mode and higher harmonics, significantly enhances the amplitudes of odd modes, unless they are exactly zero initially. Therefore, other modes which are not axially symmetric cannot be neglected at late times in the growth of the unstable bar-mode even when starting from an almost axially symmetric state.
Cluster SIMS Microscope Mode Mass Spectrometry Imaging
Kiss, András; Jungmann, Julia H; Heeren, Ron M A
2013-01-01
Microscope mode imaging for secondary ion mass spectrometry is a technique with the promise of simultaneous high spatial resolution and high speed imaging of biomolecules from complex surfaces. Technological developments such as new position-sensitive detectors, in combination with polyatomic primary ion sources, are required to exploit the full potential of microscope mode mass spectrometry imaging, i.e. to efficiently push the limits of ultra-high spatial resolution, sample throughput and sensitivity. In this work, a C60 primary source is combined with a commercial mass microscope for microscope mode secondary ion mass spectrometry imaging. The detector setup is a pixelated detector from the Medipix/Timepix family with high-voltage post-acceleration capabilities. The mass spectral and imaging performance of the system is tested with various benchmark samples and thin tissue sections. We show that the high secondary ion yield (with respect to traditional monatomic primary ion sources) of the C60 primary ion ...
Wave impedance retrieving via Bloch modes analysis
DEFF Research Database (Denmark)
Andryieuski, Andrei; Ha, S.; Sukhorukov, A.;
2011-01-01
of the Bloch mode, respectively. Case studies prove that our ap-proach can determine material and wave effective parameters of lossy and lossless metamaterials. In some examples when the passivity is violated we made further analysis and showed that this is due to the failure of concept of impedance retrieving......-ciples violation, like antiresonance behaviour with Im(ε) mode analysis of periodic metamaterials to extract the dominating (fundamental) Bloch mode. Then it is possible to determine the Bloch and wave impedances by the surface and volume aver-aging of the electromagnetic field......The main bottleneck in the restoration of electromagnetic effective parameters is connected to the impedance retrieving. The S-parameters method gives the input (Bloch) impedance, which, being then used for permittivity and permeability determination, causes some fundamental physics prin...
Detecting solar g-modes with ASTROD
Burston, R; Appourchaux, T; Ni, W T
2008-01-01
We present an up-to-date estimate for the prospect of using the Astrodynamical Space Test of Relativity using Optical Devices (ASTROD) for an unambiguous detection of solar g modes (f < 400 micro Hertz) through their gravitational signature. There are currently two major efforts to detect low-frequency gravitational effects, ASTROD and the Laser Interferometer Space Antenna (LISA). Using the most recent g mode surface amplitude estimates, both observational and theoretical, it is unclear whether LISA will be capable of successfully detecting these modes. The ASTROD project may be better suited for detection as its sensitivity curve is shifted towards lower frequencies with the best sensitivity occurring in the range 100-300 micro Hertz.
Plasmonic modes in thin films: quo vadis?
Directory of Open Access Journals (Sweden)
Antonio ePolitano
2014-07-01
Full Text Available Herein, we discuss the status and the prospect of plasmonic modes in thin films. Plasmons are collective longitudinal modes of charge fluctuation in metal samples excited by an external electric field. Surface plasmons (SPs are waves that propagate along the surface of a conductor with applications in magneto-optic data storage, optics, microscopy, and catalysis. In thin films the electronic response is influenced by electron quantum confinement. Confined electrons modify the dynamical screening processes at the film/substrate interface by introducing novel properties with potential applications and, moreover, they affect both the dispersion relation of SP frequency and the damping processes of the SP.Recent calculations indicate the emergence of acoustic surface plasmons (ASP in Ag thin films exhibiting quantum well states and in graphene films. The slope of the dispersion of ASP decreases with film thickness. We also discuss open issues in research on plasmonic modes in graphene/metal interfaes.
Examination of the 'web mode effect'
DEFF Research Database (Denmark)
Clement, Sanne Lund; Shamshiri-Petersen, Ditte
mode designs. But web surveys are subject to points of criticism. In addition to obvious errors in relation to coverage, sampling and non-response, the underlying construct is that web surveys produce measurement errors per se due to more superficial cognitive processing by respondents. Thus, including...... with telephone surveys, not enabling determination of a “web mode effect”. In this case, differences might as well be due to differences between self-administered and interviewer-administered collection methods. Other parts of literature on mixed-mode design including a web option are using stratified sampling...... to self-administered surveys by pen and paper, do web based surveys then produce greater measurement errors? Are there indications of greater tendency to ‘mental coin flipping’ when responding via web and are the answers less consistent? The questions asked will be answered on the basis of a survey...
Iron Line Variability of Discoseismic Corrugation Modes
Tsang, David
2013-01-01
Using a fast semi-analytic raytracing code, we study the variability of relativistically broadened iron lines due to discoseismic oscillations concentrated in the inner-most regions of accretion discs around black holes. The corrugation mode, or c-mode, is of particular interest as its natural frequency corresponds well to the ~0.1-15Hz range observed for low-frequency quasi-periodic oscillations (LFQPOs) for lower spins. Comparison of the oscillation phase dependent variability and QPO-phase stacked iron line observations will allow such discoseismic models to be confirmed or ruled out as a source of particular LFQPOs. The spectral range and frequency of the variability of the iron line due to corrugation modes can also potentially be used to constrain the black hole spin if observed with sufficient temporal and spectral resolution.
Compressive multi-mode superresolution display
Heide, Felix
2014-01-01
Compressive displays are an emerging technology exploring the co-design of new optical device configurations and compressive computation. Previously, research has shown how to improve the dynamic range of displays and facilitate high-quality light field or glasses-free 3D image synthesis. In this paper, we introduce a new multi-mode compressive display architecture that supports switching between 3D and high dynamic range (HDR) modes as well as a new super-resolution mode. The proposed hardware consists of readily-available components and is driven by a novel splitting algorithm that computes the pixel states from a target high-resolution image. In effect, the display pixels present a compressed representation of the target image that is perceived as a single, high resolution image. © 2014 Optical Society of America.
On Dirac Zero Modes in Hyperdiamond Model
Drissi, Lalla Btissam
2011-01-01
Using the SU(5) symmetry of the 4D hyperdiamond and results on 4D graphene, we engineer a class of 4D lattice QCD fermions whose Dirac operators have two zero modes. We show that generally the zero modes of the Dirac operator in hyperdiamond fermions are captured by a tensor {\\Omega}_{{\\mu}}^{l} with 4\\times5 complex components linking the Euclidean SO(4) vector {\\mu}; and the 5-dimensional representation of SU(5). The Bori\\c{c}i-Creutz (BC) and the Karsten-Wilzeck (KW) models as well as their Dirac zero modes are rederived as particular realizations of {\\Omega}_{{\\mu}}^{l}. Other features are also given. Keywords: Lattice QCD, Bori\\c{c}i-Creutz and Karsten-Wilzeck models, 4D hyperdiamond, 4D graphene, SU(5) Symmetry.
Modes Of The Spiral Clock Gong
Perrin, R.; Charnley, T.; Swallowe, G. M.; Banu, H.
1993-03-01
The modal frequencies of a spiral clock gong have been measured. The mode numbers and forms of vibrations have been identified by finite element modelling and photographic techniques; very good agreement between modelling and experiment was achieved. All modes were found to be either purely in-plane or out-of-plane. In both cases plots of log (2 n - 1) vs. log ƒ yielded curves with two distinct regions, the transition occurring where the wavelength corresponded to one turn of the spiral. Both sets of lower modes were very complex but the modal frequencies above n = 11 were found to fit a modified form of Chladni's law. It is suggested that the modified Chladni law may form the basis of many musical sounds.
Mechanical Weyl Modes in Topological Maxwell Lattices
Rocklin, D. Zeb; Chen, Bryan Gin-ge; Falk, Martin; Vitelli, Vincenzo; Lubensky, T. C.
2016-04-01
We show that two-dimensional mechanical lattices can generically display topologically protected bulk zero-energy phonon modes at isolated points in the Brillouin zone, analogs of massless fermion modes of Weyl semimetals. We focus on deformed square lattices as the simplest Maxwell lattices, characterized by equal numbers of constraints and degrees of freedom, with this property. The Weyl points appear at the origin of the Brillouin zone along directions with vanishing sound speed and move away to the zone edge (or return to the origin) where they annihilate. Our results suggest a design strategy for topological metamaterials with bulk low-frequency acoustic modes and elastic instabilities at a particular, tunable finite wave vector.
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. __________________________________________________
Nonlinear Bogolyubov-Valatin transformations: 2 modes
Scharnhorst, K
2010-01-01
Extending our earlier study of nonlinear Bogolyubov-Valatin transformations (canonical transformations for fermions) for one fermionic mode, in the present paper we perform a thorough study of general (nonlinear) canonical transformations for two fermionic modes. We find that the Bogolyubov-Valatin group for n=2 fermionic modes which can be implemented by means of unitary SU(2^n = 4) transformations is isomorphic to SO(6;R)/Z_2. The investigation touches on a number of subjects. As a novelty from a mathematical point of view, we study the structure of nonlinear basis transformations in a Clifford algebra [specifically, in the Clifford algebra C(0,4)] entailing (supersymmetric) transformations among multivectors of different grades. A prominent algebraic role in this context is being played by biparavectors (products of Dirac matrices, quadriquaternions, sedenions) and spin bivectors (antisymmetric complex matrices). The studied biparavectors are equivalent to Eddington's E-numbers and can be understood in ter...
Standard solar model. II - g-modes
Guenther, D. B.; Demarque, P.; Pinsonneault, M. H.; Kim, Y.-C.
1992-01-01
The paper presents the g-mode oscillation for a set of modern solar models. Each solar model is based on a single modification or improvement to the physics of a reference solar model. Improvements were made to the nuclear reaction rates, the equation of state, the opacities, and the treatment of the atmosphere. The error in the predicted g-mode periods associated with the uncertainties in the model physics is predicted and the specific sensitivities of the g-mode periods and their period spacings to the different model structures are described. In addition, these models are compared to a sample of published observations. A remarkably good agreement is found between the 'best' solar model and the observations of Hill and Gu (1990).
Sparsity-promoting dynamic mode decomposition
Jovanović, Mihailo R; Nichols, Joseph W
2013-01-01
Dynamic mode decomposition (DMD) represents an effective means for capturing the essential features of numerically or experimentally generated flow fields. In order to achieve a desirable tradeoff between the quality of approximation and the number of modes that are used to approximate the given fields, we develop a sparsity-promoting variant of the standard DMD algorithm. In our method, sparsity is induced by regularizing the least-squares deviation between the matrix of snapshots and the linear combination of DMD modes with an additional term that penalizes the $\\ell_1$-norm of the vector of DMD amplitudes. The globally optimal solution of the resulting regularized convex optimization problem is computed using the alternating direction method of multipliers, an algorithm well-suited for large problems. Several examples of flow fields resulting from numerical simulations and physical experiments are used to illustrate the effectiveness of the developed method.
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.