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Sample records for nonlinear effects resulting

  1. GENERAL APROACH TO MODELING NONLINEAR AMPLITUDE AND FREQUENCY DEPENDENT HYSTERESIS EFFECTS BASED ON EXPERIMENTAL RESULTS

    Directory of Open Access Journals (Sweden)

    Christopher Heine

    2014-08-01

    Full Text Available A detailed description of the rubber parts’ properties is gaining in importance in the current simulation models of multi-body simulation. One application example is a multi-body simulation of the washing machine movement. Inside the washing machine, there are different force transmission elements, which consist completely or partly of rubber. Rubber parts or, generally, elastomers usually have amplitude-dependant and frequency-dependent force transmission properties. Rheological models are used to describe these properties. A method for characterization of the amplitude and frequency dependence of such a rheological model is presented within this paper. Within this method, the used rheological model can be reduced or expanded in order to illustrate various non-linear effects. An original result is given with the automated parameter identification. It is fully implemented in Matlab. Such identified rheological models are intended for subsequent implementation in a multi-body model. This allows a significant enhancement of the overall model quality.

  2. Results of nonlinear and nonstationary image processing

    International Nuclear Information System (INIS)

    Pizer, S.M.; Correla, J.A.; Chesler, D.A.; Metz, C.E.

    1973-01-01

    A nonstationary method, multiple z-divided filtering, and a nonlinear method, biased smearing have been applied to scintigrams. Biased smearing does not appear to hold much promise. Multiple z-divided filtering, on the other hand, appears to be justified, and initial results at minimum encourage further research into the possibility that this technique may become a method of choice

  3. Nonlinear effects in water waves

    International Nuclear Information System (INIS)

    Janssen, P.A.E.M.

    1989-05-01

    This set of lecture notes on nonlinear effects in water waves was written on the occasion of the first ICTP course on Ocean Waves and Tides held from 26 September until 28 October 1988 in Trieste, Italy. It presents a summary and unification of my knowledge on nonlinear effects of gravity waves on an incompressible fluid without vorticity. The starting point of the theory is the Hamiltonian for water waves. The evolution equations of both weakly nonlinear, shallow water and deep water gravity waves are derived by suitable approximation of the energy of the waves, resulting in the Korteweg-de Vries equation and the Zakharov equation, respectively. Next, interesting properties of the KdV equation (solitons) and the Zakharov equation (instability of a finite amplitude wave train) are discussed in some detail. Finally, the evolution of a homogeneous, random wave field due to resonant four wave processes is considered and the importance of this process for ocean wave prediction is pointed out. 38 refs, 21 figs

  4. Stochastic effects on the nonlinear Schroedinger equation

    International Nuclear Information System (INIS)

    Flessas, G P; Leach, P G L; Yannacopoulos, A N

    2004-01-01

    The aim of this article is to provide a brief review of recent advances in the field of stochastic effects on the nonlinear Schroedinger equation. The article reviews rigorous and perturbative results. (review article)

  5. Nonlinear effects in modulated quantum optomechanics

    Science.gov (United States)

    Yin, Tai-Shuang; Lü, Xin-You; Zheng, Li-Li; Wang, Mei; Li, Sha; Wu, Ying

    2017-05-01

    The nonlinear quantum regime is crucial for implementing interesting quantum effects, which have wide applications in modern quantum science. Here we propose an effective method to reach the nonlinear quantum regime in a modulated optomechanical system (OMS), which is originally in the weak-coupling regime. The mechanical spring constant and optomechanical interaction are modulated periodically. This leads to the result that the resonant optomechanical interaction can be effectively enhanced into the single-photon strong-coupling regime by the modulation-induced mechanical parametric amplification. Moreover, the amplified phonon noise can be suppressed completely by introducing a squeezed vacuum reservoir, which ultimately leads to the realization of photon blockade in a weakly coupled OMS. The reached nonlinear quantum regime also allows us to engineer the nonclassical states (e.g., Schrödinger cat states) of the cavity field, which are robust against the phonon noise. This work offers an alternative approach to enhance the quantum nonlinearity of an OMS, which should expand the applications of cavity optomechanics in the quantum realm.

  6. Nonlinear effects on bremsstrahlung emission in dusty plasmas

    International Nuclear Information System (INIS)

    Kim, Young-Woo; Jung, Young-Dae

    2004-01-01

    Nonlinear effects on the bremsstrahlung process due to ion-dust grain collisions are investigated in dusty plasmas. The nonlinear screened interaction potential is applied to obtain the Fourier coefficients of the force acting on the dust grain. The classical trajectory analysis is applied to obtain the differential bremsstrahlung radiation cross section as a function of the scaled impact parameter, projectile energy, photon energy, and Debye length. The result shows that the nonlinear effects suppress the bremsstrahlung radiation cross section due to collisions of ions with positively charged dust grains. These nonlinear effects decrease with increasing Debye length and temperature, and increase with increasing radiation photon energy

  7. New results on the mathematical problems in nonlinear physics

    International Nuclear Information System (INIS)

    1980-01-01

    The main topics treated in this report are: I) Existence of generalized Lagrangians. II) Conserved densities for odd-order polynomial evolution equations and linear evolution systems. III ) Conservation laws for Klein-Gordon, Di rae and Maxwell equations. IV) Stability conditions for finite-energy solutions of a non-linear Klein-Gordon equation. V) Hamiltonian approach to non-linear evolution equations and Backlund transformations. VI) Anharmonic vibrations: Status of results and new possible approaches. (Author) 83 refs

  8. Nonlinear Ion Harmonics in the Paul Trap with Added Octopole Field: Theoretical Characterization and New Insight into Nonlinear Resonance Effect.

    Science.gov (United States)

    Xiong, Caiqiao; Zhou, Xiaoyu; Zhang, Ning; Zhan, Lingpeng; Chen, Yongtai; Nie, Zongxiu

    2016-02-01

    The nonlinear harmonics within the ion motion are the fingerprint of the nonlinear fields. They are exclusively introduced by these nonlinear fields and are responsible to some specific nonlinear effects such as nonlinear resonance effect. In this article, the ion motion in the quadrupole field with a weak superimposed octopole component, described by the nonlinear Mathieu equation (NME), was studied by using the analytical harmonic balance (HB) method. Good accuracy of the HB method, which was comparable with that of the numerical fourth-order Runge-Kutta (4th RK), was achieved in the entire first stability region, except for the points at the stability boundary (i.e., β = 1) and at the nonlinear resonance condition (i.e., β = 0.5). Using the HB method, the nonlinear 3β harmonic series introduced by the octopole component and the resultant nonlinear resonance effect were characterized. At nonlinear resonance, obvious resonant peaks were observed in the nonlinear 3β series of ion motion, but were not found in the natural harmonics. In addition, both resonant excitation and absorption peaks could be observed, simultaneously. These are two unique features of the nonlinear resonance, distinguishing it from the normal resonance. Finally, an approximation equation was given to describe the corresponding working parameter, q nr , at nonlinear resonance. This equation can help avoid the sensitivity degradation due to the operation of ion traps at the nonlinear resonance condition.

  9. Rapid assessment of nonlinear optical propagation effects in dielectrics

    Science.gov (United States)

    Hoyo, J. Del; de La Cruz, A. Ruiz; Grace, E.; Ferrer, A.; Siegel, J.; Pasquazi, A.; Assanto, G.; Solis, J.

    2015-01-01

    Ultrafast laser processing applications need fast approaches to assess the nonlinear propagation of the laser beam in order to predict the optimal range of processing parameters in a wide variety of cases. We develop here a method based on the simple monitoring of the nonlinear beam shaping against numerical prediction. The numerical code solves the nonlinear Schrödinger equation with nonlinear absorption under simplified conditions by employing a state-of-the art computationally efficient approach. By comparing with experimental results we can rapidly estimate the nonlinear refractive index and nonlinear absorption coefficients of the material. The validity of this approach has been tested in a variety of experiments where nonlinearities play a key role, like spatial soliton shaping or fs-laser waveguide writing. The approach provides excellent results for propagated power densities for which free carrier generation effects can be neglected. Above such a threshold, the peculiarities of the nonlinear propagation of elliptical beams enable acquiring an instantaneous picture of the deposition of energy inside the material realistic enough to estimate the effective nonlinear refractive index and nonlinear absorption coefficients that can be used for predicting the spatial distribution of energy deposition inside the material and controlling the beam in the writing process.

  10. Analytical evaluation of nonlinear distortion effects on multicarrier signals

    CERN Document Server

    Araújo, Theresa

    2015-01-01

    Due to their ability to support reliable high quality of service as well as spectral and power efficiency, multicarrier modulation systems have found increasing use in modern communications services. However, one of the main drawbacks of these systems is their vulnerability to nonlinear distortion effects. Analytical Evaluation of Nonlinear Distortion Effects on Multicarrier Signals details a unified approach to well-known analytical results on memoryless nonlinearities that takes advantage of the Gaussian behavior of multicarrier signals.Sharing new insights into the behavior of nonlinearly d

  11. Ranking scientific publications: the effect of nonlinearity

    Science.gov (United States)

    Yao, Liyang; Wei, Tian; Zeng, An; Fan, Ying; di, Zengru

    2014-10-01

    Ranking the significance of scientific publications is a long-standing challenge. The network-based analysis is a natural and common approach for evaluating the scientific credit of papers. Although the number of citations has been widely used as a metric to rank papers, recently some iterative processes such as the well-known PageRank algorithm have been applied to the citation networks to address this problem. In this paper, we introduce nonlinearity to the PageRank algorithm when aggregating resources from different nodes to further enhance the effect of important papers. The validation of our method is performed on the data of American Physical Society (APS) journals. The results indicate that the nonlinearity improves the performance of the PageRank algorithm in terms of ranking effectiveness, as well as robustness against malicious manipulations. Although the nonlinearity analysis is based on the PageRank algorithm, it can be easily extended to other iterative ranking algorithms and similar improvements are expected.

  12. Ranking scientific publications: the effect of nonlinearity.

    Science.gov (United States)

    Yao, Liyang; Wei, Tian; Zeng, An; Fan, Ying; Di, Zengru

    2014-10-17

    Ranking the significance of scientific publications is a long-standing challenge. The network-based analysis is a natural and common approach for evaluating the scientific credit of papers. Although the number of citations has been widely used as a metric to rank papers, recently some iterative processes such as the well-known PageRank algorithm have been applied to the citation networks to address this problem. In this paper, we introduce nonlinearity to the PageRank algorithm when aggregating resources from different nodes to further enhance the effect of important papers. The validation of our method is performed on the data of American Physical Society (APS) journals. The results indicate that the nonlinearity improves the performance of the PageRank algorithm in terms of ranking effectiveness, as well as robustness against malicious manipulations. Although the nonlinearity analysis is based on the PageRank algorithm, it can be easily extended to other iterative ranking algorithms and similar improvements are expected.

  13. Research on nonlinearity effect of secondary electron multiplier

    International Nuclear Information System (INIS)

    Wei Xingjian; Liao Junsheng; Deng Dachao; Yu Chunrong; Yuan Li

    2007-01-01

    The nonlinearity of secondary electron multiplier (SEM) of a thermal ionization mass spectrometer has been researched by using UTB-500 uranium isotope reference material and multi-collecting technique. The results show that the nonlinearity effect of SEM exists in the whole ion counting range, and there is an extreme point of the nonlinearity when the ion counting rate is about 20000 cps. The deviation between measured value of the extreme point and the reference value of the reference sample can be up to 3%, and the nonlinearity obeys logarithm linearity law on both sides of extreme point. A kind of mathematics model of nonlinearity calibration has been put forward. Using this model, the nonlinearity of SEM of TIMS can be calibrated. (authors)

  14. Cosmological effects of nonlinear electrodynamics

    International Nuclear Information System (INIS)

    Novello, M; Goulart, E; Salim, J M; Bergliaffa, S E Perez

    2007-01-01

    It will be shown that a given realization of nonlinear electrodynamics, used as a source of Einstein's equations, generates a cosmological model with interesting features, namely a phase of current cosmic acceleration, and the absence of an initial singularity, thus pointing to a way of solving two important problems in cosmology

  15. Mathematical problems in non-linear Physics: some results

    International Nuclear Information System (INIS)

    1979-01-01

    The basic results presented in this report are the following: 1) Characterization of the range and Kernel of the variational derivative. 2) Determination of general conservation laws in linear evolution equations, as well as bounds for the number of polynomial conserved densities in non-linear evolution equations in two independent variables of even order. 3) Construction of the most general evolution equation which has a given family of conserved densities. 4) Regularity conditions for the validity of the Lie invariance method. 5) A simple class of perturbations in non-linear wave equations. 6) Soliton solutions in generalized KdV equations. (author)

  16. On some nonlinear effects in ultrasonic fields

    Science.gov (United States)

    Tjotta

    2000-03-01

    Nonlinear effects associated with intense sound fields in fluids are considered theoretically. Special attention is directed to the study of higher effects that cannot be described within the standard propagation models of nonlinear acoustics (the KZK and Burgers equations). The analysis is based on the fundamental equations of motion for a thermoviscous fluid, for which thermal equations of state exist. Model equations are derived and used to analyze nonlinear sources for generation of flow and heat, and other changes in the ambient state of the fluid. Fluctuations in the coefficients of viscosity and thermal conductivity caused by the sound field, are accounted for. Also considered are nonlinear effects induced in the fluid by flexural vibrations. The intensity and absorption of finite amplitude sound waves are calculated, and related to the sources for generation of higher order effects.

  17. Enhanced Nonlinear Effects in Metamaterials and Plasmonics

    Directory of Open Access Journals (Sweden)

    C. Argyropoulos

    2012-07-01

    Full Text Available In this paper we provide an overview of the anomalous and enhanced nonlinear effects available when optical nonlinear materials are combined inside plasmonic waveguide structures. Broad, bistable and all-optical switching responses are exhibited at the cut-off frequency of these waveguides, characterized by reduced Q-factor resonances. These phenomena are due to the large field enhancement obtained inside specific plasmonic gratings, which ensures a significant boosting of the nonlinear operation. Several exciting applications are proposed, which may potentially lead to new optical components and add to the optical nanocircuit paradigm.

  18. Chaos resulting from nonlinear relations between different variables

    International Nuclear Information System (INIS)

    Dohtani, Akitaka

    2011-01-01

    Research highlights: → We prove a general result on the existence of chaos. → We focus on the cyclic composites of interdependent relations between different variables. → By considering several examples, we conclude that the cyclic composites play an important role in detecting chaotic dynamics. - Abstract: In this study, we further develop the perturbation method of Marotto and investigate the general mechanisms responsible for nonlinear dynamics, which are typical of multidimensional systems. We focus on the composites of interdependent relations between different variables. First, we prove a general result on chaos, which shows that the cyclic composites of nonlinear interdependent relations are sources of chaotic dynamics in multidimensional systems. By considering several examples, we conclude that the cyclic composites play an important role in detecting chaotic dynamics.

  19. Quantum Information Processing using Nonlinear Optical Effects

    DEFF Research Database (Denmark)

    Andersen, Lasse Mejling

    This PhD thesis treats applications of nonlinear optical effects for quantum information processing. The two main applications are four-wave mixing in the form of Bragg scattering (BS) for quantum-state-preserving frequency conversion, and sum-frequency generation (SFG) in second-order nonlinear......-chirping the pumps. In the high-conversion regime without the effects of NPM, exact Green functions for BS are derived. In this limit, separability is possible for conversion efficiencies up to 60 %. However, the system still allows for selective frequency conversion as well as re-shaping of the output. One way...

  20. Transient thermal effect, nonlinear refraction and nonlinear absorption properties of graphene oxide sheets in dispersion.

    Science.gov (United States)

    Zhang, Xiao-Liang; Liu, Zhi-Bo; Li, Xiao-Chun; Ma, Qiang; Chen, Xu-Dong; Tian, Jian-Guo; Xu, Yan-Fei; Chen, Yong-Sheng

    2013-03-25

    The nonlinear refraction (NLR) properties of graphene oxide (GO) in N, N-Dimethylformamide (DMF) was studied in nanosecond, picosecond and femtosecond time regimes by Z-scan technique. Results show that the dispersion of GO in DMF exhibits negative NLR properties in nanosecond time regime, which is mainly attributed to transient thermal effect in the dispersion. The dispersion also exhibits negative NLR in picosecond and femtosecond time regimes, which are arising from sp(2)- hybridized carbon domains and sp(3)- hybridized matrix in GO sheets. To illustrate the relations between NLR and nonlinear absorption (NLA), NLA properties of the dispersion were also studied in nanosecond, picosecond and femtosecond time regimes.

  1. Two-dimensional effects in nonlinear Kronig-Penney models

    DEFF Research Database (Denmark)

    Gaididei, Yuri Borisovich; Christiansen, Peter Leth; Rasmussen, Kim

    1997-01-01

    An analysis of two-dimensional (2D) effects in the nonlinear Kronig-Penney model is presented. We establish an effective one-dimensional description of the 2D effects, resulting in a set of pseudodifferential equations. The stationary states of the 2D system and their stability is studied...

  2. The Geometric Nonlinear Generalized Brazier Effect

    DEFF Research Database (Denmark)

    Nikolajsen, Jan Ánike; Lauridsen, Peter Riddersholm; Damkilde, Lars

    2016-01-01

    that the generalized Brazier effect is a local effect not influencing the overall mechanical behavior of the structure significantly. The offset is a nonlinear geometric beam-type Finite Element calculation, which takes into account the large displacements and rotations. The beam-type model defines the stresses which...... mainly are in the direction of the beam axis. The generalized Brazier effect is calculated as a linear load case based on these stresses....

  3. Non-linear Isotope Effects

    DEFF Research Database (Denmark)

    Schmidt, Johan Albrecht

    ’s stratosphere is nearly mass dependent, and only a small fraction of the observed anomalous oxygen-17 excess can be attributed to N2O photolysis. In contrast, stratospheric photolysis produces a significant inverse clumped isotope effect.(ii) Stratospheric OCS photolysis significantly enrich the remaining OCS...

  4. Enhancing Thermoelectric Performance Using Nonlinear Transport Effects

    Science.gov (United States)

    Jiang, Jian-Hua; Imry, Yoseph

    2017-06-01

    We study nonlinear transport effects on the maximum efficiency and power for both inelastic and elastic thermoelectric generators. The former device refers to phonon-assisted hopping in double quantum dots, while the latter device is represented by elastic tunneling through a single quantum dot. We find that nonlinear thermoelectric transport can lead to enhanced efficiency and power for both types of devices. A comprehensive survey of various quantum-dot energy, temperature, and parasitic heat conduction reveals that the nonlinear transport-induced improvements of the maximum efficiency and power are overall much more significant for inelastic devices than for elastic devices, even for temperature biases as small as Th=1.2 Tc (Th and Tc are the temperatures of the hot and cold reservoirs, respectively). The underlying mechanism is revealed as due to the fact that, unlike the Fermi distribution, the Bose distribution is not bounded when the temperature bias increases. A large flux density of absorbed phonons leads to a great enhancement of the electrical current, output power, and energy efficiency, dominating over the concurrent increase of the parasitic heat current. Our study reveals that nonlinear transport effects can be a useful tool for improving thermoelectric performance.

  5. Nonlinear heat conduction equations with memory: Physical meaning and analytical results

    Science.gov (United States)

    Artale Harris, Pietro; Garra, Roberto

    2017-06-01

    We study nonlinear heat conduction equations with memory effects within the framework of the fractional calculus approach to the generalized Maxwell-Cattaneo law. Our main aim is to derive the governing equations of heat propagation, considering both the empirical temperature-dependence of the thermal conductivity coefficient (which introduces nonlinearity) and memory effects, according to the general theory of Gurtin and Pipkin of finite velocity thermal propagation with memory. In this framework, we consider in detail two different approaches to the generalized Maxwell-Cattaneo law, based on the application of long-tail Mittag-Leffler memory function and power law relaxation functions, leading to nonlinear time-fractional telegraph and wave-type equations. We also discuss some explicit analytical results to the model equations based on the generalized separating variable method and discuss their meaning in relation to some well-known results of the ordinary case.

  6. A nonlinear oscillator with parametric coloured noise: some analytical results

    International Nuclear Information System (INIS)

    Mallick, Kirone; Marcq, Philippe

    2005-01-01

    The asymptotic behaviour of a nonlinear oscillator subject to a multiplicative Ornstein-Uhlenbeck noise is investigated. When the dynamics is expressed in terms of energy-angle coordinates, it is observed that the angle is a fast variable as compared to the energy. Thus, an effective stochastic dynamics for the energy can be derived if the angular variable is averaged out. However, the standard elimination procedure, performed earlier for a Gaussian white noise, fails when the noise is coloured because of correlations between the noise and the fast angular variable. We develop here a specific averaging scheme that retains these correlations. This allows us to calculate the probability distribution function (PDF) of the system and to derive the behaviour of physical observables in the long time limit

  7. Nonlinear Talbot Effect and Its Applications

    Science.gov (United States)

    Yang, Zhening

    2018-03-01

    Talbot effect, a lenless self-imaging phenomenon, was first discovered in 1836 by H.F. Talbot. The conventional Talbott effect has been studied for over a hundred years. Recently, the rapid development of optical superlattices has brought a great breakthrough in Talbot effect research. A nonlinear self-imaging phenomenon was found in the periodically poled LiTaO3 (PPLT) crystals. [1][2][3] This nonlinear Talbot effect has applications not only in optics but also in many other fields. For example, the phenomenon is realized by frequency-doubled beams, which offers people a new way to enhance the spatial resolution of the self-images of periodic objects. And by observing the self-image of the second harmonic (SH) field on the sample surface, people can detect the domain structure in the crystal without damaging the sample. Throughout this review paper, an overview of nonlinear Talbot effect and two applications of this phenomenon is presented. Breakthroughs like achieving a super-focused spot and realizing an acousto-optic tunable SH Talbot illuminator will be introduced as well.

  8. Contributions of changes in climatology and perturbation and the resulting nonlinearity to regional climate change.

    Science.gov (United States)

    Adachi, Sachiho A; Nishizawa, Seiya; Yoshida, Ryuji; Yamaura, Tsuyoshi; Ando, Kazuto; Yashiro, Hisashi; Kajikawa, Yoshiyuki; Tomita, Hirofumi

    2017-12-20

    Future changes in large-scale climatology and perturbation may have different impacts on regional climate change. It is important to understand the impacts of climatology and perturbation in terms of both thermodynamic and dynamic changes. Although many studies have investigated the influence of climatology changes on regional climate, the significance of perturbation changes is still debated. The nonlinear effect of these two changes is also unknown. We propose a systematic procedure that extracts the influences of three factors: changes in climatology, changes in perturbation and the resulting nonlinear effect. We then demonstrate the usefulness of the procedure, applying it to future changes in precipitation. All three factors have the same degree of influence, especially for extreme rainfall events. Thus, regional climate assessments should consider not only the climatology change but also the perturbation change and their nonlinearity. This procedure can advance interpretations of future regional climates.

  9. Effect of Forcing Function on Nonlinear Acoustic Standing Waves

    Science.gov (United States)

    Finkheiner, Joshua R.; Li, Xiao-Fan; Raman, Ganesh; Daniels, Chris; Steinetz, Bruce

    2003-01-01

    Nonlinear acoustic standing waves of high amplitude have been demonstrated by utilizing the effects of resonator shape to prevent the pressure waves from entering saturation. Experimentally, nonlinear acoustic standing waves have been generated by shaking an entire resonating cavity. While this promotes more efficient energy transfer than a piston-driven resonator, it also introduces complicated structural dynamics into the system. Experiments have shown that these dynamics result in resonator forcing functions comprised of a sum of several Fourier modes. However, previous numerical studies of the acoustics generated within the resonator assumed simple sinusoidal waves as the driving force. Using a previously developed numerical code, this paper demonstrates the effects of using a forcing function constructed with a series of harmonic sinusoidal waves on resonating cavities. From these results, a method will be demonstrated which allows the direct numerical analysis of experimentally generated nonlinear acoustic waves in resonators driven by harmonic forcing functions.

  10. Nonlinear effects in varactor-tuned resonators.

    Science.gov (United States)

    Everard, Jeremy; Zhou, Liang

    2006-05-01

    This paper describes the effects of RF power level on the performance of varactor-tuned resonator circuits. A variety of topologies are considered, including series and parallel resonators operating in both unbalanced and balanced modes. As these resonators were designed to produce oscillators with minimum phase noise, the initial small signal insertion loss was set to 6 dB and, hence, QL/Q0 = 1/2. To enable accurate analysis and simulation, S parameter and PSPICE models for the varactors were optimized and developed. It is shown that these resonators start to demonstrate nonlinear operation at very low power levels demonstrating saturation and lowering of the resonant frequency. On occasion squegging is observed for modified bias conditions. The nonlinear effects are dependent on the unloaded Q (Q0), the ratio of loaded to unloaded Q (QL/Q0), the bias voltage, and circuit configurations with typical nonlinear effects occurring at -8 dBm in a circuit with a loaded Q of 63 and a varactor bias voltage of 3 V. Analysis, simulation, and measurements that show close correlation are presented.

  11. Nonlinear Dynamics of Silicon Nanowire Resonator Considering Nonlocal Effect.

    Science.gov (United States)

    Jin, Leisheng; Li, Lijie

    2017-12-01

    In this work, nonlinear dynamics of silicon nanowire resonator considering nonlocal effect has been investigated. For the first time, dynamical parameters (e.g., resonant frequency, Duffing coefficient, and the damping ratio) that directly influence the nonlinear dynamics of the nanostructure have been derived. Subsequently, by calculating their response with the varied nonlocal coefficient, it is unveiled that the nonlocal effect makes more obvious impacts at the starting range (from zero to a small value), while the impact of nonlocal effect becomes weaker when the nonlocal term reaches to a certain threshold value. Furthermore, to characterize the role played by nonlocal effect in exerting influence on nonlinear behaviors such as bifurcation and chaos (typical phenomena in nonlinear dynamics of nanoscale devices), we have calculated the Lyapunov exponents and bifurcation diagram with and without nonlocal effect, and results shows the nonlocal effect causes the most significant effect as the device is at resonance. This work advances the development of nanowire resonators that are working beyond linear regime.

  12. Bryan's effect and anisotropic nonlinear damping

    Science.gov (United States)

    Joubert, Stephan V.; Shatalov, Michael Y.; Fay, Temple H.; Manzhirov, Alexander V.

    2018-03-01

    In 1890, G. H. Bryan discovered the following: "The vibration pattern of a revolving cylinder or bell revolves at a rate proportional to the inertial rotation rate of the cylinder or bell." We call this phenomenon Bryan's law or Bryan's effect. It is well known that any imperfections in a vibratory gyroscope (VG) affect Bryan's law and this affects the accuracy of the VG. Consequently, in this paper, we assume that all such imperfections are either minimised or eliminated by some known control method and that only damping is present within the VG. If the damping is isotropic (linear or nonlinear), then it has been recently demonstrated in this journal, using symbolic analysis, that Bryan's law remains invariant. However, it is known that linear anisotropic damping does affect Bryan's law. In this paper, we generalise Rayleigh's dissipation function so that anisotropic nonlinear damping may be introduced into the equations of motion. Using a mixture of numeric and symbolic analysis on the ODEs of motion of the VG, for anisotropic light nonlinear damping, we demonstrate (up to an approximate average), that Bryan's law is affected by any form of such damping, causing pattern drift, compromising the accuracy of the VG.

  13. A novel nonlinear damage resonance intermodulation effect for structural health monitoring

    Science.gov (United States)

    Ciampa, Francesco; Scarselli, Gennaro; Meo, Michele

    2017-04-01

    This paper is aimed at developing a theoretical model able to predict the generation of nonlinear elastic effects associated to the interaction of ultrasonic waves with the steady-state nonlinear response of local defect resonance (LDR). The LDR effect is used in nonlinear elastic wave spectroscopy to enhance the excitation of the material damage at its local resonance, thus to dramatically increase the vibrational amplitude of material nonlinear phenomena. The main result of this work is to prove both analytically and experimentally the generation of novel nonlinear elastic wave effects, here named as nonlinear damage resonance intermodulation, which correspond to a nonlinear intermodulation between the driving frequency and the LDR one. Beside this intermodulation effect, other nonlinear elastic wave phenomena such as higher harmonics of the input frequency and superharmonics of LDR frequency were found. The analytical model relies on solving the nonlinear equation of motion governing bending displacement under the assumption of both quadratic and cubic nonlinear defect approximation. Experimental tests on a damaged composite laminate confirmed and validated these predictions and showed that using continuous periodic excitation, the nonlinear structural phenomena associated to LDR could also be featured at locations different from the damage resonance. These findings will provide new opportunities for material damage detection using nonlinear ultrasounds.

  14. Nonlinear effects on mode-converted lower-hybrid waves

    International Nuclear Information System (INIS)

    Kuehl, H.H.

    1976-01-01

    Nonlinear ponderomotive force effects on mode-converted lower-hybrid waves are considered. The nonlinear distortion of these waves is shown to be governed by the cubic nonlinear Schroedinger equation. The threshold condition for self-focusing and filamentation is derived

  15. Nonlinear effects in dynamic analysis and design of nuclear power plant components: research status and needs

    Energy Technology Data Exchange (ETDEWEB)

    Stoykovich, M [Burns and Roe, Inc., New York (USA)

    1978-10-01

    This paper encompasses nonlinear effects in dynamic analysis and design of nuclear power plant facilities. The history of plasticity as a science is briefly discussed, and nonlinear cases of special interest are described. Approaches to some of the nonlinear problems are presented. These include the nonlinearity due to foundation-structure interaction associated with the base slab uplift during seismic disturbances, the nonlinear base-isolation system for the reduction of earthquake-generated forces and deformations of superstructures, nonlinear systems having restoring-force functions in case of gaps and liift-off conditions, and nonlinearity of viscoelastic systems due to inelastic deformations. Available computer programs information for the solution of various types of nonlinear problems are provided. Advantages and disadvantages of some of the nonlinear and linear analyses are discussed. Comparison of some nonlinear and linear results of analyses are presented. Conclusions are reached with regard to research status and recommendations for further studies and for performing non-linear analyses associated with the problems of nonlinearity are presented.

  16. Nonlinear effects in dynamic analysis and design of nuclear power plant components: research status and needs

    International Nuclear Information System (INIS)

    Stoykovich, M.

    1978-01-01

    This paper encompasses nonlinear effects in dynamic analysis and design of nuclear power plant facilities. The history of plasticity as a science is briefly discussed, and nonlinear cases of special interest are described. Approaches to some of the nonlinear problems are presented. These include the nonlinearity due to foundation-structure interaction associated with the base slab uplift during seismic disturbances, the nonlinear base-isolation system for the reduction of earthquake-generated forces and deformations of superstructures, nonlinear systems having restoring-force functions in case of gaps and liift-off conditions, and nonlinearity of viscoelastic systems due to inelastic deformations. Available computer programs information for the solution of various types of nonlinear problems are provided. Advantages and disadvantages of some of the nonlinear and linear analyses are discussed. Comparison of some nonlinear and linear results of analyses are presented. Conclusions are reached with regard to research status and recommendations for further studies and for performing non-linear analyses associated with the problems of nonlinearity are presented. (Auth.)

  17. Improved effective potential by nonlinear canonical transformations

    International Nuclear Information System (INIS)

    Ritschel, U.

    1990-01-01

    We generalize the familiar gaussian-effective-potential formalism to a class of non-gaussian trial states. With the help of exact nonlinear canonical transformations, expectation values can be calculated analytically and in closed form. A detailed description of our method, particularly for quadratic and cubic transformations, and of the related renormalization procedure is given. Applications to φ 4 -models in various dimensionalities are treated. We find the expected critical behaviour in two space-time dimensions. In three and four dimensions we observe instabilities which go back the incompleteness of the gaussian-based renormalization. In the appendices it is shown that the quadratic transformation leads to a coherent state in a certain limiting case, and the generalization to systems at finite temperature is performed. (orig.)

  18. Nonlinear effects of high temperature on buckling of structural elements

    International Nuclear Information System (INIS)

    Iyengar, N.G.R.

    1975-01-01

    Structural elements used in nuclear reactors are subjected to high temperatures. Since with increase in temperature there is a gradual fall in the elastic modulus and the stress-strain relationship is nonlinear at these operating load levels, a realistic estimate of the buckling load should include this nonlinearity. In this paper the buckling loads for uniform columns with circular and rectangular cross-sections and different boundary conditions under high temperature environment are estimated. The stress-strain relationship for the material has been assumed to follow inverse Ramberg-Osgood law. In view of the fact that no closed form solutions are possible, approximate methods like perturbation and Galerkin techniques are used. Further, the solution for general value for 'm' is quite involved. Results have been obtained with values for 'm' as 3 and 5. Studies reveal that the influence of material nonlinearity on the buckling load is of the softening type, and it increases with increase in the value of 'm'. The nonlinear effects are more for clamped boundaries than for simply supported boundaries. For the first mode analysis both the methods are powerful. It is, however, felt that for higher modes the Galerkin method might be better in view of its simplicity. This investigation may be considered as a step towards a more general solution

  19. Nonlinear effects in Pulsations of Compact Stars and Gravitational Waves

    International Nuclear Information System (INIS)

    Passamonti, A

    2007-01-01

    Nonlinear stellar oscillations can be studied by using a multiparameter perturbative approach, which is appropriate for investigating the low and mild nonlinear dynamical regimes. We present the main properties of our perturbative framework for describing, in the time domain, the nonlinear coupling between the radial and nonradial perturbations of spherically symmetric and perfect fluid compact stars. This particular coupling can be described by gauge invariant quantities that obeys a system of partial differential equations with source terms, which are made up of product of first order radial and nonradial perturbations. We report the results of numerical simulations for both the axial and polar coupling perturbations, that exhibit in the stellar dynamics and in the associated gravitational wave signal some interesting nonlinear effects, such as combination harmonics and resonances. In particular, we concentrate on the axial case, where the linear axial perturbations describe a harmonic component of a differentially rotating neutron star. The gravitational wave signal of this stellar configuration mirrors at second perturbative order the spectral features of the linear radial normal modes. In addition, a signal amplification appears when one of the radial frequencies is close to the axial w-mode frequencies of the star

  20. Nonlinear space charge effect of bunched beam in linac

    International Nuclear Information System (INIS)

    Chen Yinbao

    1992-02-01

    The nonlinear space charge effect due to the nonuniform particle density distribution in bunched beam of a linac is discussed. The formulae of nonlinear space charge effect and nonlinear focusing forces were derived for the bunched beam with Kapchinskij-Vladimirskij (K-V) distribution, waterbag (WB) distribution, parabolic (PA) distribution, and Gauss (GA) distribution in both of the space charge disk model and space charge cylinder model in the waveguide of a linac

  1. Vibrational mechanics nonlinear dynamic effects, general approach, applications

    CERN Document Server

    Blekhman, Iliya I

    2000-01-01

    This important book deals with vibrational mechanics - the new, intensively developing section of nonlinear dynamics and the theory of nonlinear oscillations. It offers a general approach to the study of the effect of vibration on nonlinear mechanical systems.The book presents the mathematical apparatus of vibrational mechanics which is used to describe such nonlinear effects as the disappearance and appearance under vibration of stable positions of equilibrium and motions (i.e. attractors), the change of the rheological properties of the media, self-synchronization, self-balancing, the vibrat

  2. Effective-medium theory for nonlinear magneto-optics in magnetic granular alloys: cubic nonlinearity

    International Nuclear Information System (INIS)

    Granovsky, Alexander B.; Kuzmichov, Michail V.; Clerc, J.-P.; Inoue, Mitsuteru

    2003-01-01

    We propose a simple effective-medium approach for calculating the effective dielectric function of a magnetic metal-insulator granular alloy in which there is a weakly nonlinear relation between electric displacement D and electric field E for both constituent materials of the form D i =ε i (0) E i +χ i (3) |E i | 2 E i . We assume that linear ε i (0) and cubic nonlinear χ i (3) dielectric functions are diagonal and linear with magnetization non-diagonal components. For such metal-insulator composite magneto-optical effects depend on a light intensity and the effective cubic dielectric function χ eff (3) can be significantly greater (up to 10 3 times) than that for constituent materials. The calculation scheme is based on the Bergman and Stroud-Hui theory of nonlinear optical properties of granular matter. The giant cubic magneto-optical nonlinearity is found for composites with metallic volume fraction close to the percolation threshold and at a resonance of optical conductivity. It is shown that a composite may exhibit nonlinear magneto-optics even when both constituent materials have no cubic magneto-optical nonlinearity

  3. Effective-medium theory for nonlinear magneto-optics in magnetic granular alloys: cubic nonlinearity

    Energy Technology Data Exchange (ETDEWEB)

    Granovsky, Alexander B. E-mail: granov@magn.ru; Kuzmichov, Michail V.; Clerc, J.-P.; Inoue, Mitsuteru

    2003-03-01

    We propose a simple effective-medium approach for calculating the effective dielectric function of a magnetic metal-insulator granular alloy in which there is a weakly nonlinear relation between electric displacement D and electric field E for both constituent materials of the form D{sub i}={epsilon}{sub i}{sup (0)}E{sub i} +{chi}{sub i}{sup (3)}|E{sub i}|{sup 2}E{sub i}. We assume that linear {epsilon}{sub i}{sup (0)} and cubic nonlinear {chi}{sub i}{sup (3)} dielectric functions are diagonal and linear with magnetization non-diagonal components. For such metal-insulator composite magneto-optical effects depend on a light intensity and the effective cubic dielectric function {chi}{sub eff}{sup (3)} can be significantly greater (up to 10{sup 3} times) than that for constituent materials. The calculation scheme is based on the Bergman and Stroud-Hui theory of nonlinear optical properties of granular matter. The giant cubic magneto-optical nonlinearity is found for composites with metallic volume fraction close to the percolation threshold and at a resonance of optical conductivity. It is shown that a composite may exhibit nonlinear magneto-optics even when both constituent materials have no cubic magneto-optical nonlinearity.

  4. Multi-atom Jaynes-Cummings model with nonlinear effects

    International Nuclear Information System (INIS)

    Aleixo, Armando Nazareno Faria; Balantekin, Akif Baha; Ribeiro, Marco Antonio Candido

    2001-01-01

    The standard Jaynes-Cummings (JC) model and its extensions, normally used in quantum optics, idealizes the interaction of matter with electromagnetic radiation by a simple Hamiltonian of a two-level atom coupled to a single bosonic mode. This Hamiltonian has a fundamental importance to the field of quantum optics and it is a central ingredient in the quantized description of any optical system involving the interaction between light and atoms. The JC Hamiltonian defines a molecule, a composite system formed from the coupling of a two-state system and a quantized harmonic oscillator. For this Hamiltonian, mostly the single-particle situation has been studied. This model can also be extended for the situation where one has N two-level systems, which interact only with the electromagnetic radiation. In this case the effects of the spatial distribution of the particles it is not taken into account and the spin angular momentum S-circumflex i of each particle contributes to form a total angular momentum J-circumflex of the system. When one considers the effects due to the spatial variation in the field intensity in a nonlinear medium it is necessary to further add a Kerr term to the standard JC Hamiltonian. This kind of nonlinear JC Hamiltonian is used in the study of micro masers. Another nonlinear variant of the JC model takes the coupling between matter and the radiation to depend on the intensity of the electromagnetic field. This model is interesting since this kind of interaction means that effectively the coupling is proportional to the amplitude of the field representing a very simple case of a nonlinear interaction corresponding to a more realistic physical situation. In this work we solve exactly the problem of the interaction of a N two-level atoms with an electromagnetic radiation when nonlinear effects due to the spatial variation in the field intensity in a nonlinear Kerr medium and the dependence on the intensity of the electromagnetic field on the matter

  5. Spatial nonlinearities: Cascading effects in the earth system

    Science.gov (United States)

    Peters, Debra P.C.; Pielke, R.A.; Bestelmeyer, B.T.; Allen, Craig D.; Munson-McGee, Stuart; Havstad, K. M.; Canadell, Josep G.; Pataki, Diane E.; Pitelka, Louis F.

    2006-01-01

    Nonlinear behavior is prevalent in all aspects of the Earth System, including ecological responses to global change (Gallagher and Appenzeller 1999; Steffen et al. 2004). Nonlinear behavior refers to a large, discontinuous change in response to a small change in a driving variable (Rial et al. 2004). In contrast to linear systems where responses are smooth, well-behaved, continuous functions, nonlinear systems often undergo sharp or discontinuous transitions resulting from the crossing of thresholds. These nonlinear responses can result in surprising behavior that makes forecasting difficult (Kaplan and Glass 1995). Given that many system dynamics are nonlinear, it is imperative that conceptual and quantitative tools be developed to increase our understanding of the processes leading to nonlinear behavior in order to determine if forecasting can be improved under future environmental changes (Clark et al. 2001).

  6. The nonlinear effects on the characteristics of gravity wave packets: dispersion and polarization relations

    Directory of Open Access Journals (Sweden)

    S.-D. Zhang

    2000-10-01

    Full Text Available By analyzing the results of the numerical simulations of nonlinear propagation of three Gaussian gravity-wave packets in isothermal atmosphere individually, the nonlinear effects on the characteristics of gravity waves are studied quantitatively. The analyses show that during the nonlinear propagation of gravity wave packets the mean flows are accelerated and the vertical wavelengths show clear reduction due to nonlinearity. On the other hand, though nonlinear effects exist, the time variations of the frequencies of gravity wave packets are close to those derived from the dispersion relation and the amplitude and phase relations of wave-associated disturbance components are consistent with the predictions of the polarization relation of gravity waves. This indicates that the dispersion and polarization relations based on the linear gravity wave theory can be applied extensively in the nonlinear region.Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides

  7. Dark matter as a non-linear effect of gravitation

    International Nuclear Information System (INIS)

    Maia, M.D.; Capistrano, A.J.S.

    2006-01-01

    The rotation curves of stars in disk galaxies are calculated with the Newtonian law of motion applied to a scalar potential derived from the geodesic equation, only, under the slow motion condition, the so-called Nearly Newtonian Gravity (NNG). A nearly Newtonian gravitational potential, Φ NN = -1/2 c 2 (1+g 44 ), is obtained, characterized by an exact solution of Einsteins equations, with the non-linear effects present in the component g 44 . This gravitational field lies somewhere between General Relativity and Newtonian Gravity. Therefore, Einsteins equations and the equivalence principle are preserved, but the general covariance is broken. The resulting curves are remarkably close to the observed rotation curves in spiral galaxies, suggesting that a substantial component of dark matter may be explained by the non-linearity of Einsteins equations. (author)

  8. Preliminary Evaluation of Nonlinear Effects on TCA Flutter

    Science.gov (United States)

    Arslan, Alan E.; Hartwich, Peter M.; Baker, Myles L.

    1998-01-01

    The objective of this study is to investigate the effect of nonlinear aerodynamics, especially at high angles-of-attack with leading-edge separation, on the TCA flutter properties at transonic speeds. In order to achieve that objective, flutter simulations with Navier-Stokes CFD must be performed. To this end, time-marching Navier-Stokes solutions are computed for the TCA wing/body configuration at high angles-of-attack in transonic flight regimes. The approach is to perform non-linear flutter calculations on the TCA at two angles-of-attack, the first one being a case with attached flow (a=2.8 degrees) and the second one being a high angle-of-attack case with a wing leading edge vortex (a=12.11 degrees). Comparisons of the resulting histories and frequency damping information for both angles-of-attack will evaluate the impact of high-alpha aerodynamics on flutter.

  9. Heterogeneous Effects of a Nonlinear Price Schedule for Outpatient Care.

    Science.gov (United States)

    Farbmacher, Helmut; Ihle, Peter; Schubert, Ingrid; Winter, Joachim; Wuppermann, Amelie

    2017-10-01

    Nonlinear price schedules generally have heterogeneous effects on health-care demand. We develop and apply a finite mixture bivariate probit model to analyze whether there are heterogeneous reactions to the introduction of a nonlinear price schedule in the German statutory health insurance system. In administrative insurance claims data from the largest German health insurance plan, we find that some individuals strongly react to the new price schedule while a second group of individuals does not react. Post-estimation analyses reveal that the group of the individuals who do not react to the reform includes the relatively sick. These results are in line with forward-looking behavior: Individuals who are already sick expect that they will hit the kink in the price schedule and thus are less sensitive to the co-payment. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Aeroelastic Limit-Cycle Oscillations resulting from Aerodynamic Non-Linearities

    NARCIS (Netherlands)

    van Rooij, A.C.L.M.

    2017-01-01

    Aerodynamic non-linearities, such as shock waves, boundary layer separation or boundary layer transition, may cause an amplitude limitation of the oscillations induced by the fluid flow around a structure. These aeroelastic limit-cycle oscillations (LCOs) resulting from aerodynamic non-linearities

  11. Nonlinear ultrasound propagation through layered liquid and tissue-equivalent media: computational and experimental results at high frequency

    International Nuclear Information System (INIS)

    Williams, Ross; Cherin, Emmanuel; Lam, Toby Y J; Tavakkoli, Jahangir; Zemp, Roger J; Foster, F Stuart

    2006-01-01

    Nonlinear propagation has been demonstrated to have a significant impact on ultrasound imaging. An efficient computational algorithm is presented to simulate nonlinear ultrasound propagation through layered liquid and tissue-equivalent media. Results are compared with hydrophone measurements. This study was undertaken to investigate the role of nonlinear propagation in high frequency ultrasound micro-imaging. The acoustic field of a focused transducer (20 MHz centre frequency, f-number 2.5) was simulated for layered media consisting of water and tissue-mimicking phantom, for several wide-bandwidth source pulses. The simulation model accounted for the effects of diffraction, attenuation and nonlinearity, with transmission and refraction at layer boundaries. The parameter of nonlinearity, B/A, of the water and tissue-mimicking phantom were assumed to be 5.2 and 7.4, respectively. The experimentally measured phantom B/A value found using a finite-amplitude insert-substitution method was shown to be 7.4 ± 0.6. Relative amounts of measured second and third harmonic pressures as a function of the fundamental pressures at the focus were in good agreement with simulations. Agreement within 3% was found between measurements and simulations of the beam widths of the fundamental and second harmonic signals following propagation through the tissue phantom. The results demonstrate significant nonlinear propagation effects for high frequency imaging beams

  12. Nonextensive GES instability with nonlinear pressure effects

    Directory of Open Access Journals (Sweden)

    Munmi Gohain

    2018-03-01

    Full Text Available We herein analyze the instability dynamics associated with the nonextensive nonthermal gravito-electrostatic sheath (GES model for the perturbed solar plasma portraiture. The usual neutral gas approximation is herewith judiciously relaxed and the laboratory plasma-wall interaction physics is procedurally incorporated amid barotropic nonlinearity. The main motivation here stems from the true nature of the solar plasma system as a set of concentric nonlocal nonthermal sub-layers as evidenced from different multi-space satellite probes and missions. The formalism couples the solar interior plasma (SIP, bounded and solar wind plasma (SWP, unbounded via the diffused solar surface boundary (SSB formed due to an exact long-range gravito-electrostatic force-equilibration. A linear normal mode ansatz reveals both dispersive and non-dispersive features of the modified GES collective wave excitations. It is seen that the thermostatistical GES stability depends solely on the electron-to-ion temperature ratio. The damping behavior on both the scales is more pronounced in the acoustic domain, K→∞, than the gravitational domain, K→0; where, K is the Jeans-normalized angular wave number. It offers a unique quasi-linear coupling of the gravitational and acoustic fluctuations amid the GES force action. The results may be useful to see the excitation dynamics of natural normal modes in bounded nonextensive astero-environs from a new viewpoint of the plasma-wall coupling mechanism.

  13. Nonextensive GES instability with nonlinear pressure effects

    Science.gov (United States)

    Gohain, Munmi; Karmakar, Pralay Kumar

    2018-03-01

    We herein analyze the instability dynamics associated with the nonextensive nonthermal gravito-electrostatic sheath (GES) model for the perturbed solar plasma portraiture. The usual neutral gas approximation is herewith judiciously relaxed and the laboratory plasma-wall interaction physics is procedurally incorporated amid barotropic nonlinearity. The main motivation here stems from the true nature of the solar plasma system as a set of concentric nonlocal nonthermal sub-layers as evidenced from different multi-space satellite probes and missions. The formalism couples the solar interior plasma (SIP, bounded) and solar wind plasma (SWP, unbounded) via the diffused solar surface boundary (SSB) formed due to an exact long-range gravito-electrostatic force-equilibration. A linear normal mode ansatz reveals both dispersive and non-dispersive features of the modified GES collective wave excitations. It is seen that the thermostatistical GES stability depends solely on the electron-to-ion temperature ratio. The damping behavior on both the scales is more pronounced in the acoustic domain, K → ∞ , than the gravitational domain, K → 0 ; where, K is the Jeans-normalized angular wave number. It offers a unique quasi-linear coupling of the gravitational and acoustic fluctuations amid the GES force action. The results may be useful to see the excitation dynamics of natural normal modes in bounded nonextensive astero-environs from a new viewpoint of the plasma-wall coupling mechanism.

  14. Nonlinear and turbulent processes in physics. Volume 2. Nonlinear effects in various areas of science

    Energy Technology Data Exchange (ETDEWEB)

    Sagdeev, R Z

    1984-01-01

    The results of theoretical and experimental investigations of nonlinear and turbulent phenomena from a wide range of fields in physics are presented in reviews and reports. Topics examined include localized vortex formations in an ideal fluid, phase transitions in crystals, spatially nonuniform structures in condensed matter, solitons in molecular systems, the migration of quasi-particles in easily deformed crystals, bifurcations and dissipative structures in distributed kinetic systems, and structures in a nonlinear burning medium. Consideration is given to macroscopic motion generation in nonequilibrium media, the interaction of bulk and surface wave trains, near-threshold instabilities in hydrodynamics, solitons in nonlinear elastic rods with variable characteristics, the generation of solitons and vortices from chaos, and nonlinear electromagnetic-wave dissipation in an electron system.

  15. Superradiance Effects in the Linear and Nonlinear Optical Response of Quantum Dot Molecules

    Science.gov (United States)

    Sitek, A.; Machnikowski, P.

    2008-11-01

    We calculate the linear optical response from a single quantum dot molecule and the nonlinear, four-wave-mixing response from an inhomogeneously broadened ensemble of such molecules. We show that both optical signals are affected by the coupling-dependent superradiance effect and by optical interference between the two polarizations. As a result, the linear and nonlinear responses are not identical.

  16. On the effects of nonlinearities in room impulse response measurements with exponential sweeps

    DEFF Research Database (Denmark)

    Ciric, Dejan; Markovic, Milos; Mijic, Miomir

    2013-01-01

    In room impulse response measurements, there are some common disturbances that affect the measured results. These disturbances include nonlinearity, noise and time variance. In this paper, the effects of nonlinearities in the measurements with exponential sweep-sine signals are analyzed from diff...

  17. Existence Results for Some Nonlinear Functional-Integral Equations in Banach Algebra with Applications

    Directory of Open Access Journals (Sweden)

    Lakshmi Narayan Mishra

    2016-04-01

    Full Text Available In the present manuscript, we prove some results concerning the existence of solutions for some nonlinear functional-integral equations which contains various integral and functional equations that considered in nonlinear analysis and its applications. By utilizing the techniques of noncompactness measures, we operate the fixed point theorems such as Darbo's theorem in Banach algebra concerning the estimate on the solutions. The results obtained in this paper extend and improve essentially some known results in the recent literature. We also provide an example of nonlinear functional-integral equation to show the ability of our main result.

  18. Tune-shift with amplitude due to nonlinear kinematic effect

    CERN Document Server

    Wan, W

    1999-01-01

    Tracking studies of the Muon Collider 50 on 50 GeV collider ring show that the on-momentum dynamic aperture is limited to around 10 sigma even with the chromaticity sextupoles turned off. Numerical results from the normal form algorithm show that the tune-shift with amplitude is surprisingly large. Both analytical and numerical results are presented to show that nonlinear kinematic effect originated from the large angles of particles in the interaction region is responsible for the large tune-shift which in turn limits the dynamic aperture. A comparative study of the LHC collider ring is also presented to demonstrate the difference between the two machines. (14 refs).

  19. Effect of initial strain and material nonlinearity on the nonlinear static and dynamic response of graphene sheets

    Science.gov (United States)

    Singh, Sandeep; Patel, B. P.

    2018-06-01

    Computationally efficient multiscale modelling based on Cauchy-Born rule in conjunction with finite element method is employed to study static and dynamic characteristics of graphene sheets, with/without considering initial strain, involving Green-Lagrange geometric and material nonlinearities. The strain energy density function at continuum level is established by coupling the deformation at continuum level to that at atomic level through Cauchy-Born rule. The atomic interactions between carbon atoms are modelled through Tersoff-Brenner potential. The governing equation of motion obtained using Hamilton's principle is solved through standard Newton-Raphson method for nonlinear static response and Newmark's time integration technique to obtain nonlinear transient response characteristics. Effect of initial strain on the linear free vibration frequencies, nonlinear static and dynamic response characteristics is investigated in detail. The present multiscale modelling based results are found to be in good agreement with those obtained through molecular mechanics simulation. Two different types of boundary constraints generally used in MM simulation are explored in detail and few interesting findings are brought out. The effect of initial strain is found to be greater in linear response when compared to that in nonlinear response.

  20. Localized Effects in the Nonlinear Behavior of Sandwich Panels with a Transversely Flexible Core

    DEFF Research Database (Denmark)

    Frostig, Y.; Thomsen, Ole Thybo

    2005-01-01

    This paper presents the results of an investigation of the role of localized effects within the geometrically nonlinear domain on structural sandwich panels with a "compliant" core. Special emphasis is focused on the nonlinear response near concentrated loads and stiffened core regions. The adopted...... nonlinear analysis approach incorporates the effects of the vertical flexibility of the core, and it is based on the approach of the High-order Sandwich Panel Theory (HSAPT). The results demonstrate that the effects of localized loads, when taken into the geometrically nonlinear domain, change the response...... of the panel from a strength problem controlled by stress constraints into a stability problem with unstable limit point behavior when force-controlled loads are applied. The stability problem emerge as the nonlinear response develops with the formation of a small number of buckling waves in the compressed...

  1. Inverse Higgs effect in nonlinear realizations

    International Nuclear Information System (INIS)

    Ivanov, E.A.; Ogievetskij, V.I.

    1975-01-01

    In theories with nonlinearly realized symmetry it is possible in a number of cases to eliminate some initial Goldstone and gauge fields by means of putting appropriate Cartan forms equal to zero. This is called the inverse Higgs phenomenon. We give a general treatment of the inverse Higgs phenomenon for gauge and space-time symmetries and consider four instructive examples which are the elimination of unessential gauge fields in chiral symmetry and in non-linearly realized supersymmetry and also the elimination of unessential Goldstone fields in the spontaneously broken conformal and projective symmetries

  2. Effect of gain nonlinearity in semiconductor lasers

    DEFF Research Database (Denmark)

    Jensen, Niels H.; Christiansen, Peter Leth; Skovgaard, Ove

    1988-01-01

    Semiconductor lasers are modeled by single-mode rate equations with Langevin noise terms and the influence of nonlinear gain is investigated. For cw operation the probability distribution for the carrier number and the photon number in the laser cavity is obtained. The corresponding (2+1)-dimensi......Semiconductor lasers are modeled by single-mode rate equations with Langevin noise terms and the influence of nonlinear gain is investigated. For cw operation the probability distribution for the carrier number and the photon number in the laser cavity is obtained. The corresponding (2...

  3. Effects of Plasma Shaping on Nonlinear Gyrokinetic Turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Belli, E. A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Hammett, G. W. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Dorland, W. [Univ. of Maryland, College Park, MD (United States)

    2008-08-01

    The effects of flux surface shape on the gyrokinetic stability and transport of tokamak plasmas are studied using the GS2 code [M. Kotschenreuther, G. Rewoldt, and W.M. Tang, Comput. Phys. Commun. 88, 128 (1995); W. Dorland, F. Jenko, M. Kotschenreuther, and B.N. Rogers, Phys. Rev. Lett. 85, 5579 (2000)]. Studies of the scaling of nonlinear turbulence with shaping parameters are performed using analytic equilibria based on interpolations of representative shapes of the Joint European Torus (JET) [P.H. Rebut and B.E. Keen, Fusion Technol. 11, 13 (1987)]. High shaping is found to be a stabilizing influence on both the linear ion-temperature-gradient (ITG) instability and the nonlinear ITG turbulence. For the parameter regime studied here, a scaling of the heat flux with elongation of χ ~ κ-1.5 or κ-2.0, depending on the triangularity, is observed at fixed average temperature gradient. While this is not as strong as empirical elongation scalings, it is also found that high shaping results in a larger Dimits upshift of the nonlinear critical temperature gradient due to an enhancement of the Rosenbluth-Hinton residual zonal flows.

  4. Effects of Plasma Shaping on Nonlinear Gyrokinetic Turbulence

    International Nuclear Information System (INIS)

    E.A. Belli, G.W. Hammett and W. Dorland

    2008-01-01

    The effects of flux surface shape on the gyrokinetic stability and transport of tokamak plasmas are studied using the GS2 code [M. Kotschenreuther, G. Rewoldt, and W.M. Tang, Comput. Phys. Commun. 88, 128 (1995); W. Dorland, F. Jenko, M. Kotschenreuther, and B.N. Rogers, Phys. Rev. Lett. 85, 5579 (2000)]. Studies of the scaling of nonlinear turbulence with shaping parameters are performed using analytic equilibria based on interpolations of representative shapes of the Joint European Torus (JET) [P.H. Rebut and B.E. Keen, Fusion Technol. 11, 13 (1987)]. High shaping is found to be a stabilizing influence on both the linear ion-temperature-gradient (ITG) instability and the nonlinear ITG turbulence. For the parameter regime studied here, a scaling of the heat flux with elongation of χ ∼ κ -1.5 or κ -2.0 , depending on the triangularity, is observed at fixed average temperature gradient. While this is not as strong as empirical elongation scalings, it is also found that high shaping results in a larger Dimits upshift of the nonlinear critical temperature gradient due to an enhancement of the Rosenbluth-Hinton residual zonal flows

  5. Nonlinear optical effects of opening a gap in graphene

    Science.gov (United States)

    Carvalho, David N.; Biancalana, Fabio; Marini, Andrea

    2018-05-01

    Graphene possesses remarkable electronic, optical, and mechanical properties that have taken the research of two-dimensional relativistic condensed matter systems to prolific levels. However, the understanding of how its nonlinear optical properties are affected by relativisticlike effects has been broadly uncharted. It has been recently shown that highly nontrivial currents can be generated in free-standing samples, notably leading to the generation of even harmonics. Since graphene monolayers are centrosymmetric media, for which such harmonic generation at normal incidence is deemed inaccessible, this light-driven phenomenon is both startling and promising. More realistically, graphene samples are often deposited on a dielectric substrate, leading to additional intricate interactions. Here, we present a treatment to study this instance by gapping the spectrum and we show this leads to the appearance of a Berry phase in the carrier dynamics. We analyze the role of such a phase in the generated nonlinear current and conclude that it suppresses odd-harmonic generation. The pump energy can be tuned to the energy gap to yield interference among odd harmonics mediated by interband transitions, allowing even harmonics to be generated. Our results and general methodology pave the way for understanding the role of gap opening in the nonlinear optics of two-dimensional lattices.

  6. A simple predistortion technique for suppression of nonlinear effects in periodic signals generated by nonlinear transducers

    Science.gov (United States)

    Novak, A.; Simon, L.; Lotton, P.

    2018-04-01

    Mechanical transducers, such as shakers, loudspeakers and compression drivers that are used as excitation devices to excite acoustical or mechanical nonlinear systems under test are imperfect. Due to their nonlinear behaviour, unwanted contributions appear at their output besides the wanted part of the signal. Since these devices are used to study nonlinear systems, it should be required to measure properly the systems under test by overcoming the influence of the nonlinear excitation device. In this paper, a simple method that corrects distorted output signal of the excitation device by means of predistortion of its input signal is presented. A periodic signal is applied to the input of the excitation device and, from analysing the output signal of the device, the input signal is modified in such a way that the undesirable spectral components in the output of the excitation device are cancelled out after few iterations of real-time processing. The experimental results provided on an electrodynamic shaker show that the spectral purity of the generated acceleration output approaches 100 dB after few iterations (1 s). This output signal, applied to the system under test, is thus cleaned from the undesirable components produced by the excitation device; this is an important condition to ensure a correct measurement of the nonlinear system under test.

  7. Non-Linear Effects in Knowledge Production

    Science.gov (United States)

    Purica, Ionut

    2007-04-01

    The generation of technological knowledge is paramount to our present development; the production of technological knowledge is governed by the same Cobb Douglas type model, with the means of research and the intelligence level replacing capital, respectively labor. We are exploring the basic behavior of present days' economies that are producing technological knowledge, along with the `usual' industrial production and determine a basic behavior that turns out to be a `Henon attractor'. Measures are introduced for the gain of technological knowledge and for the information of technological sequences that are based respectively on the underlying multi-valued modal logic of the technological research and on nonlinear thermodynamic considerations.

  8. Global non-linear effect of temperature on economic production.

    Science.gov (United States)

    Burke, Marshall; Hsiang, Solomon M; Miguel, Edward

    2015-11-12

    Growing evidence demonstrates that climatic conditions can have a profound impact on the functioning of modern human societies, but effects on economic activity appear inconsistent. Fundamental productive elements of modern economies, such as workers and crops, exhibit highly non-linear responses to local temperature even in wealthy countries. In contrast, aggregate macroeconomic productivity of entire wealthy countries is reported not to respond to temperature, while poor countries respond only linearly. Resolving this conflict between micro and macro observations is critical to understanding the role of wealth in coupled human-natural systems and to anticipating the global impact of climate change. Here we unify these seemingly contradictory results by accounting for non-linearity at the macro scale. We show that overall economic productivity is non-linear in temperature for all countries, with productivity peaking at an annual average temperature of 13 °C and declining strongly at higher temperatures. The relationship is globally generalizable, unchanged since 1960, and apparent for agricultural and non-agricultural activity in both rich and poor countries. These results provide the first evidence that economic activity in all regions is coupled to the global climate and establish a new empirical foundation for modelling economic loss in response to climate change, with important implications. If future adaptation mimics past adaptation, unmitigated warming is expected to reshape the global economy by reducing average global incomes roughly 23% by 2100 and widening global income inequality, relative to scenarios without climate change. In contrast to prior estimates, expected global losses are approximately linear in global mean temperature, with median losses many times larger than leading models indicate.

  9. Global non-linear effect of temperature on economic production

    Science.gov (United States)

    Burke, Marshall; Hsiang, Solomon M.; Miguel, Edward

    2015-11-01

    Growing evidence demonstrates that climatic conditions can have a profound impact on the functioning of modern human societies, but effects on economic activity appear inconsistent. Fundamental productive elements of modern economies, such as workers and crops, exhibit highly non-linear responses to local temperature even in wealthy countries. In contrast, aggregate macroeconomic productivity of entire wealthy countries is reported not to respond to temperature, while poor countries respond only linearly. Resolving this conflict between micro and macro observations is critical to understanding the role of wealth in coupled human-natural systems and to anticipating the global impact of climate change. Here we unify these seemingly contradictory results by accounting for non-linearity at the macro scale. We show that overall economic productivity is non-linear in temperature for all countries, with productivity peaking at an annual average temperature of 13 °C and declining strongly at higher temperatures. The relationship is globally generalizable, unchanged since 1960, and apparent for agricultural and non-agricultural activity in both rich and poor countries. These results provide the first evidence that economic activity in all regions is coupled to the global climate and establish a new empirical foundation for modelling economic loss in response to climate change, with important implications. If future adaptation mimics past adaptation, unmitigated warming is expected to reshape the global economy by reducing average global incomes roughly 23% by 2100 and widening global income inequality, relative to scenarios without climate change. In contrast to prior estimates, expected global losses are approximately linear in global mean temperature, with median losses many times larger than leading models indicate.

  10. Transverse effects in nonlinear optics: Toward the photon superfluid

    Science.gov (United States)

    McCormick, Colin Fraser

    Nonlinear optics displays a wealth of transverse effects. These effects are particularly rich in the presence of an optical cavity. Many considerations suggest that in a Kerr nonlinear cavity a new state of light known as a "photon superfluid" can form, with strong analogies to atomic superfluids. The conditions for the formation of the photon superfluid include requirements on the cavity, input light fields and the nonlinear medium as well as various timescales. The most favorable candidate nonlinear medium for observing the photon super-fluid is an atomic vapor. With a strong and fast Kerr effect, atomic vapors also have the advantage of a Kerr coefficient that is tunable in both magnitude and sign. A series of z-scan experiments in far-detuned atomic rubidium vapor is reported, measuring the Kerr coefficient and determining its functional dependence on detuning to be that of a Doppler-broadened two-level model with adiabatic following of the electric field by the atom pseudomoment. Saturation effects are found to be important. Z-scan measurements for detunings within the Doppler profile are shown to agree well with numerical simulations based on the Doppler-broadened model. Agreement between absorptive and refractive non-linear coefficients is evidence of the Kramers-Kronig relations at work, even in this nonlinear system. The formation of the photon superfluid is discussed and the calculation of a new process, nearly collinear four-wave mixing, is presented. This process is essentially an inverse beam filamentation that is likely to be the underlying physical mechanism for transverse cooling and condensation of photons in a nonlinear optical cavity. Nearly collinear four-wave mixing may also be related to phenomena in general nonlinear physics, including modulation instability and Fermi-Pasta-Ulam recurrence.

  11. Role of viscosity in nonlinear effects

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, G V; Peshkin, M A; Polyakov, Ye Ye

    1980-01-01

    Data are presented on laboratory experiments for filtering of gases of liquids in clay, slightly permeable core samples. A method is proposed for processing the results of experiments which makes it possible to isolate the effect of viscosity of the fluid on the defined quantity of maximum pressure differential.

  12. Nonlinear QED effects in X-ray emission of pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Shakeri, Soroush [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Haghighat, Mansour [Department of Physics, Shiraz University, Shiraz 71946-84795 (Iran, Islamic Republic of); Xue, She-Sheng, E-mail: Soroush.Shakeri@ph.iut.ac.ir, E-mail: m.haghighat@shirazu.ac.ir, E-mail: xue@icra.it [ICRANet, Piazzale della Repubblica 10, 65122, Pescara (Italy)

    2017-10-01

    In the presence of strong magnetic fields near pulsars, the QED vacuum becomes a birefringent medium due to nonlinear QED interactions. Here, we explore the impact of the effective photon-photon interaction on the polarization evolution of photons propagating through the magnetized QED vacuum of a pulsar. We solve the quantum Boltzmann equation within the framework of the Euler-Heisenberg Lagrangian to find the evolution of the Stokes parameters. We find that linearly polarized X-ray photons propagating outward in the magnetosphere of a rotating neutron star can acquire high values for the circular polarization parameter. Meanwhile, it is shown that the polarization characteristics of photons besides photon energy depend strongly on parameters of the pulsars such as magnetic field strength, inclination angle and rotational period. Our results are clear predictions of QED vacuum polarization effects in the near vicinity of magnetic stars which can be tested with the upcoming X-ray polarimetric observations.

  13. Attenuation, dispersion and nonlinearity effects in graphene-based waveguides

    Directory of Open Access Journals (Sweden)

    Almir Wirth Lima Jr.

    2015-05-01

    Full Text Available We simulated and analyzed in detail the behavior of ultrashort optical pulses, which are typically used in telecommunications, propagating through graphene-based nanoribbon waveguides. In this work, we showed the changes that occur in the Gaussian and hyperbolic secant input pulses due to the attenuation, high-order dispersive effects and nonlinear effects. We concluded that it is possible to control the shape of the output pulses with the value of the input signal power and the chemical potential of the graphene nanoribbon. We believe that the obtained results will be highly relevant since they can be applied to other nanophotonic devices, for example, filters, modulators, antennas, switches and other devices.

  14. Macroscopic quantum effects in nonlinear optical patterns

    International Nuclear Information System (INIS)

    Gatti, A.; Lugiato, L.A.; Oppo, G.L.; Barnett, S.M.; Marzoli, I.

    1998-01-01

    We display the results of the numerical simulations of a set of Langevin equations, which describe the dynamics of a degenerate optical parametric oscillator in the Wigner representation. The scan of the threshold region shows the gradual transformation of a quantum image into a classical roll pattern. Thus the quantum image behaves as a precursor of the roll pattern which appear above threshold. In the fax field, suitable spatial correlation functions of intensity and field quadratures show unambiguously the quantum nature of fluctuations that generate the image, leading to effects of quantum noise reduction below the shot noise level and to the formulation of an EPR paradox. (author)

  15. Nonlinear surface impedance of YBCO thin films: Measurements, modeling, and effects in devices

    International Nuclear Information System (INIS)

    Oates, D.E.; Koren, G.; Polturak, E.

    1995-01-01

    High-T c thin films continue to be of interest for passive device applications at microwave frequencies, but nonlinear effects may limit the performance. To understand these effects we have measured the nonlinear effects may limit the performance. To understand these effects we have measured the nonlinear surface impedance Z s in a number of YBa 2 Cu 3 O 7-x thin films as a function of frequency from 1 to 18 GHz, rf surface magnetic field H rf to 1500 Oe, and temperature from 4 K to T c . The results at low H rf are shown to agree quantitatively with a modified coupled-grain model and at high H rf with hysteresis-loss calculations using the Bean critical-state model applied to a thin strip. The loss mechanisms are extrinsic properties resulting from defects in the films. We also report preliminary measurements of the nonlinear impedance of Josephson junctions, and the results are related to the models of nonlinear Z s . The implications of nonlinear Z s for devices are discussed using the example of a five-pole bandpass filter

  16. Results on stabilization of nonlinear systems under finite data-rate constraints

    NARCIS (Netherlands)

    Persis, Claudio De

    2004-01-01

    We discuss in this paper a result concerning the stabilization problem of nonlinear systems under data-rate constraints using output feedback. To put the result in a broader context, we shall first review a number of recent contributions on the stabilization problem under data-rate constraints when

  17. Effect of Integral Non-Linearity on Energy Calibration of ...

    African Journals Online (AJOL)

    The integral non-linearity (INL) of four spectroscopy systems, two integrated (A1 and A2) and two classical (B1 and B2) systems was determined using pulses from a random pulse generator. The effect of INL on the system's energy calibration was also determined. The effect is minimal in the classical system at high ...

  18. Zeno effect and switching of solitons in nonlinear couplers

    DEFF Research Database (Denmark)

    Abdullaev, F Kh; Konotop, V V; Ögren, Magnus

    2011-01-01

    The Zeno effect is investigated for soliton type pulses in a nonlinear directional coupler with dissipation. The effect consists in increase of the coupler transparency with increase of the dissipative losses in one of the arms. It is shown that localized dissipation can lead to switching...

  19. Geometrical Effects on Nonlinear Electrodiffusion in Cell Physiology

    Science.gov (United States)

    Cartailler, J.; Schuss, Z.; Holcman, D.

    2017-12-01

    We report here new electrical laws, derived from nonlinear electrodiffusion theory, about the effect of the local geometrical structure, such as curvature, on the electrical properties of a cell. We adopt the Poisson-Nernst-Planck equations for charge concentration and electric potential as a model of electrodiffusion. In the case at hand, the entire boundary is impermeable to ions and the electric field satisfies the compatibility condition of Poisson's equation. We construct an asymptotic approximation for certain singular limits to the steady-state solution in a ball with an attached cusp-shaped funnel on its surface. As the number of charge increases, they concentrate at the end of cusp-shaped funnel. These results can be used in the design of nanopipettes and help to understand the local voltage changes inside dendrites and axons with heterogeneous local geometry.

  20. Nonlinear throughflow and internal heating effects on vibrating porous medium

    Directory of Open Access Journals (Sweden)

    Palle Kiran

    2016-06-01

    Full Text Available The effect of vertical throughflow and internal heating effects on fluid saturated porous medium under gravity modulation is investigated. The amplitude of modulation is considered to be very small and the disturbances are expanded in terms of power series of amplitude of convection. A weakly nonlinear stability analysis is proposed to study stationary convection. The Nusselt number is obtained numerically to present the results of heat transfer while using Ginzburg–Landau equation. The vertical throughflow has dual effect either to destabilize or to stabilize the system for downward or upward directions. The effect of internal heat source (Ri>0 enhances or sink (Ri<0 diminishes heat transfer in the system. The amplitude and frequency of modulation have the effects of increasing or diminishing heat transport. For linear model Venezian approach suggested that throughflow and internal heating have both destabilizing and stabilizing effects for suitable ranges of Ω. Further, the study establishes that heat transport can be controlled effectively by a mechanism that is external to the system throughflow and gravity modulation.

  1. Investigation on the effect of nonlinear processes on similarity law in high-pressure argon discharges

    Science.gov (United States)

    Fu, Yangyang; Parsey, Guy M.; Verboncoeur, John P.; Christlieb, Andrew J.

    2017-11-01

    In this paper, the effect of nonlinear processes (such as three-body collisions and stepwise ionizations) on the similarity law in high-pressure argon discharges has been studied by the use of the Kinetic Global Model framework. In the discharge model, the ground state argon atoms (Ar), electrons (e), atom ions (Ar+), molecular ions (Ar2+), and fourteen argon excited levels Ar*(4s and 4p) are considered. The steady-state electron and ion densities are obtained with nonlinear processes included and excluded in the designed models, respectively. It is found that in similar gas gaps, keeping the product of gas pressure and linear dimension unchanged, with the nonlinear processes included, the normalized density relations deviate from the similarity relations gradually as the scale-up factor decreases. Without the nonlinear processes, the parameter relations are in good agreement with the similarity law predictions. Furthermore, the pressure and the dimension effects are also investigated separately with and without the nonlinear processes. It is shown that the gas pressure effect on the results is less obvious than the dimension effect. Without the nonlinear processes, the pressure and the dimension effects could be estimated from one to the other based on the similarity relations.

  2. Modelling non-linear effects of dark energy

    Science.gov (United States)

    Bose, Benjamin; Baldi, Marco; Pourtsidou, Alkistis

    2018-04-01

    We investigate the capabilities of perturbation theory in capturing non-linear effects of dark energy. We test constant and evolving w models, as well as models involving momentum exchange between dark energy and dark matter. Specifically, we compare perturbative predictions at 1-loop level against N-body results for four non-standard equations of state as well as varying degrees of momentum exchange between dark energy and dark matter. The interaction is modelled phenomenologically using a time dependent drag term in the Euler equation. We make comparisons at the level of the matter power spectrum and the redshift space monopole and quadrupole. The multipoles are modelled using the Taruya, Nishimichi and Saito (TNS) redshift space spectrum. We find perturbation theory does very well in capturing non-linear effects coming from dark sector interaction. We isolate and quantify the 1-loop contribution coming from the interaction and from the non-standard equation of state. We find the interaction parameter ξ amplifies scale dependent signatures in the range of scales considered. Non-standard equations of state also give scale dependent signatures within this same regime. In redshift space the match with N-body is improved at smaller scales by the addition of the TNS free parameter σv. To quantify the importance of modelling the interaction, we create mock data sets for varying values of ξ using perturbation theory. This data is given errors typical of Stage IV surveys. We then perform a likelihood analysis using the first two multipoles on these sets and a ξ=0 modelling, ignoring the interaction. We find the fiducial growth parameter f is generally recovered even for very large values of ξ both at z=0.5 and z=1. The ξ=0 modelling is most biased in its estimation of f for the phantom w=‑1.1 case.

  3. Dispersion and nonlinear effects in OFDM-RoF system

    Science.gov (United States)

    Alhasson, Bader H.; Bloul, Albe M.; Matin, M.

    2010-08-01

    The radio-over-fiber (RoF) network has been a proven technology to be the best candidate for the wireless-access technology, and the orthogonal frequency division multiplexing (OFDM) technique has been established as the core technology in the physical layer of next generation wireless communication system, as a result OFDM-RoF has drawn attentions worldwide and raised many new research topics recently. At the present time, the trend of information industry is towards mobile, wireless, digital and broadband. The next generation network (NGN) has motivated researchers to study higher-speed wider-band multimedia communication to transmit (voice, data, and all sorts of media such as video) at a higher speed. The NGN would offer services that would necessitate broadband networks with bandwidth higher than 2Mbit/s per radio channel. Many new services emerged, such as Internet Protocol TV (IPTV), High Definition TV (HDTV), mobile multimedia and video stream media. Both speed and capacity have been the key objectives in transmission. In the meantime, the demand for transmission bandwidth increased at a very quick pace. The coming of 4G and 5G era will provide faster data transmission and higher bit rate and bandwidth. Taking advantages of both optical communication and wireless communication, OFDM Radio over Fiber (OFDM-RoF) system is characterized by its high speed, large capacity and high spectral efficiency. However, up to the present there are some problems to be solved, such as dispersion and nonlinearity effects. In this paper we will study the dispersion and nonlinearity effects and their elimination in OFDM-radio-over-fiber system.

  4. Nonlinear Bubble Dynamics And The Effects On Propagation Through Near-Surface Bubble Layers

    Science.gov (United States)

    Leighton, Timothy G.

    2004-11-01

    Nonlinear bubble dynamics are often viewed as the unfortunate consequence of having to use high acoustic pressure amplitudes when the void fraction in the near-surface oceanic bubble layer is great enough to cause severe attenuation (e.g. >50 dB/m). This is seen as unfortunate since existing models for acoustic propagation in bubbly liquids are based on linear bubble dynamics. However, the development of nonlinear models does more than just allow quantification of the errors associated with the use of linear models. It also offers the possibility of propagation modeling and acoustic inversions which appropriately incorporate the bubble nonlinearity. Furthermore, it allows exploration and quantification of possible nonlinear effects which may be exploited. As a result, high acoustic pressure amplitudes may be desirable even in low void fractions, because they offer opportunities to gain information about the bubble cloud from the nonlinearities, and options to exploit the nonlinearities to enhance communication and sonar in bubbly waters. This paper presents a method for calculating the nonlinear acoustic cross-sections, scatter, attenuations and sound speeds from bubble clouds which may be inhomogeneous. The method allows prediction of the time dependency of these quantities, both because the cloud may vary and because the incident acoustic pulse may have finite and arbitrary time history. The method can be readily adapted for bubbles in other environments (e.g. clouds of interacting bubbles, sediments, structures, in vivo, reverberant conditions etc.). The possible exploitation of bubble acoustics by marine mammals, and for sonar enhancement, is explored.

  5. Linearity and Non-linearity of Photorefractive effect in Materials ...

    African Journals Online (AJOL)

    Linearity and Non-linearity of Photorefractive effect in Materials using the Band transport ... For low light beam intensities the change in the refractive index is ... field is spatially phase shifted by /2 relative to the interference fringe pattern, which ...

  6. Lossy effects in a nonlinear nematic optical fiber

    Science.gov (United States)

    Rodríguez, R. F.; Reyes, J. A.

    2001-09-01

    We use the multiple scales method to derive a generalized nonlinear Schrödinger equation that takes into account the dissipative effects in the reorientation of a nematic confined in a cylindrical waveguide. This equation has soliton-like solutions and predicts a decrease in the penetration length of the optical solitons for each propagating mode with respect to the dissipationless case.

  7. Linearity and Non-linearity of Photorefractive effect in Materials ...

    African Journals Online (AJOL)

    In this paper we have studied the Linearity and Non-linearity of Photorefractive effect in materials using the band transport model. For low light beam intensities the change in the refractive index is proportional to the electric field for linear optics while for non- linear optics the change in refractive index is directly proportional ...

  8. Polaron effects on nonlinear optical rectification in asymmetrical Gaussian potential quantum wells with applied electric fields

    International Nuclear Information System (INIS)

    Wu, Jinghe; Guo, Kangxian; Liu, Guanghui

    2014-01-01

    Polaron effects on nonlinear optical rectification in asymmetrical Gaussian potential quantum wells are studied by the effective mass approximation and the perturbation theory. The numerical results show that nonlinear optical rectification coefficients are strongly dependent on the barrier hight V 0 of the Gaussian potential quantum wells, the range L of the confinement potential and the electric field F. Besides, the numerical results show that no matter how V 0 , L and F change, taking into consideration polaron effects, the optical rectification coefficients χ 0 (2) get greatly enhanced.

  9. Energy dependence of the Cronin effect from nonlinear QCD evolution

    International Nuclear Information System (INIS)

    Albacete, Javier L.; Armesto, Nestor; Salgado, Carlos A.; Wiedemann, Urs Achim; Kovner, Alex

    2004-01-01

    The nonlinear evolution of dense partonic systems has been suggested as a novel physics mechanism relevant for the dynamics of p-A and A-A collisions at collider energies. Here we study to what extent the description of Cronin enhancement in the framework of this nonlinear evolution is consistent with the recent observation in √(s)=200 GeV d-Au collisions at the Relativistic Heavy Ion Collider. We solve the Balitsky-Kovchegov evolution equation numerically for several initial conditions encoding Cronin enhancement. We find that the properly normalized nuclear gluon distribution is suppressed at all momenta relative to that of a single nucleon. For the resulting spectrum of produced gluons in p-A and A-A collisions, the nonlinear QCD evolution is unable to generate a Cronin-type enhancement, and it quickly erases any such enhancement which may be present at lower energies

  10. Cutoff effects in O(N) nonlinear sigma models

    International Nuclear Information System (INIS)

    Knechtli, Francesco; Leder, Bjoern; Wolff, Ulli

    2005-01-01

    In the nonlinear O(N) sigma model at N=3 unexpected cutoff effects have been found before with standard discretizations and lattice spacings. Here the situation is analyzed further employing additional data for the step scaling function of the finite volume mass gap at N=3,4,8 and a large N-study of the leading as well as next-to-leading terms in 1/N. The latter exact results are demonstrated to follow Symanzik's form of the asymptotic cutoff dependence. At the same time, when fuzzed with artificial statistical errors and then fitted like the Monte Carlo results, a picture similar to N=3 emerges. We hence cannot conclude a truly anomalous cutoff dependence but only relatively large cutoff effects, where the logarithmic component is important. Their size shrinks at larger N, but the structure remains similar. The large N results are particularly interesting as we here have exact nonperturbative control over an asymptotically free model both in the continuum limit and on the lattice

  11. Cutoff effects in O(N) nonlinear sigma models

    International Nuclear Information System (INIS)

    Knechtli, F.; Wolff, U.; Leder, B.

    2005-06-01

    In the nonlinear O(N) sigma model at N=3 unexpected cutoff effects have been found before with standard discretizations and lattice spacings. Here the situation is analyzed further employing additional data for the step scaling function of the finite volume mass gap at N=3,4,8 and a large N-study of the leading as well as next-to-leading terms in 1/N. The latter exact results are demonstrated to follow Symanzik's form of the asymptotic cutoff dependence. At the same time, when fuzzed with artificial statistical errors and then fitted like the Monte Carlo results, a picture similar to N=3 emerges. We hence cannot conclude a truly anomalous cutoff dependence but only relatively large cutoff effects, where the logarithmic component is important. Their size shrinks at larger N, but the structure remains similar. The large N results are particularly interesting as we here have exact nonperturbative control over an asymptotically free model both in the continuum limit and on the lattice. (orig.)

  12. Nonlinear effects in interactions of swift ions with solids

    International Nuclear Information System (INIS)

    Crawford, O.H.; Dorado, J.J.; Flores, F.

    1994-01-01

    The passage of a swift charged particle through a solid gives rise to a wake of induced electron density behind the particle. It is calculated for a proton penetrating an electron gas having the density of the valence electrons in gold, assuming linear response of the medium. The induced potential associated with the wake is responsible for the energy loss of the particle, and for many effects that have captured recent interest. These include, among others, vicinage effects on swift ion clusters, emission of electrons from bombarded solids, forces on swift ions near a surface, and energy shifts in electronic states of channeled ions. Furthermore, the wake has a determining influence on the spatial distribution, and character, of energy deposition in the medium. Previous theoretical studies of these phenomena have employed a linear wake, i.e., one that is proportional to the charge of the projectile, eZ. However, in most experiments that measure these effects, the conditions are such that the wake must include higher-order terms in Z. The purpose of this study is to analyze the nonlinear wake, to understand how the linear results must be revised

  13. Nonlinear charge reduction effect in strongly coupled plasmas

    International Nuclear Information System (INIS)

    Sarmah, D; Tessarotto, M; Salimullah, M

    2006-01-01

    The charge reduction effect, produced by the nonlinear Debye screening of high-Z charges occurring in strongly coupled plasmas, is investigated. An analytic asymptotic expression is obtained for the charge reduction factor (f c ) which determines the Debye-Hueckel potential generated by a charged test particle. Its relevant parametric dependencies are analysed and shown to predict a strong charge reduction effect in strongly coupled plasmas

  14. Performance of Different OCDMA Codes with FWM and XPM Nonlinear Effects

    Science.gov (United States)

    Rana, Shivani; Gupta, Amit

    2017-08-01

    In this paper, 1 Gb/s non-linear optical code division multiple access system have been simulated and modeled. To reduce multiple user interference multi-diagonal (MD) code which possesses the property of having zero cross-correlation have been deployed. The MD code shows better results than Walsh-Hadamard and multi-weight code under the nonlinear effect of four-wave mixing (FWM) and cross-phase modulation (XPM). The simulation results reveal that effect of FWM reduces when MD codes are employed as compared to other codes.

  15. On the Effect of Thermoelastic Damping in Nonlinear Micro Electro Mechanical Resonators using Differential Quadrature Method

    Directory of Open Access Journals (Sweden)

    A. Karami Mohammadi

    2015-07-01

    Full Text Available : In this paper, a nonlinear model of clamped-clamped microbeam actuated by electrostatic load with stretching and thermoelastic effects is presented. Free vibration frequency is calculated by discretization based on DQ method. Frequency is a complex value due to the thermoelastic effect that dissipates the energy. By separating the real and imaginary parts of frequency, quality factor of thermoelastic damping is calculated. Both stretching and thermoelastic effects are validated against the results of the reference papers. The variations of thermoelastic damping versus elasticity modulus, coefficient of thermal expansion and geometrical parameters such as thickness, gap distance, and length are investigated and these results are compared in the linear and nonlinear models for high values of voltage. Also, this paper shows that since for high values of electrostatic voltage the linear model reveals a large error for calculating the thermoelastic damping, the nonlinear model should be used for this purpose.

  16. Dynamic nonlinear thermal optical effects in coupled ring resonators

    Directory of Open Access Journals (Sweden)

    Chenguang Huang

    2012-09-01

    Full Text Available We investigate the dynamic nonlinear thermal optical effects in a photonic system of two coupled ring resonators. A bus waveguide is used to couple light in and out of one of the coupled resonators. Based on the coupling from the bus to the resonator, the coupling between the resonators and the intrinsic loss of each individual resonator, the system transmission spectrum can be classified by three different categories: coupled-resonator-induced absorption, coupled-resonator-induced transparency and over coupled resonance splitting. Dynamic thermal optical effects due to linear absorption have been analyzed for each category as a function of the input power. The heat power in each resonator determines the thermal dynamics in this coupled resonator system. Multiple “shark fins” and power competition between resonators can be foreseen. Also, the nonlinear absorption induced thermal effects have been discussed.

  17. Nonlinear Resonance Islands and Modulational Effects in a Proton Synchrotron

    Energy Technology Data Exchange (ETDEWEB)

    Satogata, Todd Jeffrey [Northwestern Univ., Evanston, IL (United States)

    1993-01-01

    We examine both one-dimensional and two-dimensional nonlinear resonance islands created in the transverse phase space of a proton synchrotron by nonlinear magnets. We also examine application of the theoretical framework constructed to the phenomenon of modulational diffusion in a collider model of the Fermilab Tevatron. For the one-dimensional resonance island system, we examine the effects of two types of modulational perturbations on the stability of these resonance islands: tune modulation and beta function modulation. Hamiltonian models are presented which predict stability boundaries that depend on only three paramders: the strength and frequency of the modulation and the frequency of small oscillations inside the resonance island. These. models are compared to particle tracking with excellent agreement. The tune modulation model is also successfully tested in experiment, where frequency domain analysis coupled with tune modulation is demonstrated to be useful in measuring the strength of a nonlinear resonance. Nonlinear resonance islands are also examined in two transverse dimensions in the presence of coupling and linearly independent crossing resonances. We present a first-order Hamiltonian model which predicts fixed point locations, but does not reproduce small oscillation frequencies seen in tracking; therefore in this circumstance such a model is inadequate. Particle tracking is presented which shows evidence of two-dimensional persistent signals, and we make suggestions on methods for observing such signals in future experiment.

  18. Fitting Higgs data with nonlinear effective theory.

    Science.gov (United States)

    Buchalla, G; Catà, O; Celis, A; Krause, C

    2016-01-01

    In a recent paper we showed that the electroweak chiral Lagrangian at leading order is equivalent to the conventional [Formula: see text] formalism used by ATLAS and CMS to test Higgs anomalous couplings. Here we apply this fact to fit the latest Higgs data. The new aspect of our analysis is a systematic interpretation of the fit parameters within an EFT. Concentrating on the processes of Higgs production and decay that have been measured so far, six parameters turn out to be relevant: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]. A global Bayesian fit is then performed with the result [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]. Additionally, we show how this leading-order parametrization can be generalized to next-to-leading order, thus improving the [Formula: see text] formalism systematically. The differences with a linear EFT analysis including operators of dimension six are also discussed. One of the main conclusions of our analysis is that since the conventional [Formula: see text] formalism can be properly justified within a QFT framework, it should continue to play a central role in analyzing and interpreting Higgs data.

  19. Existence results for boundary problems for uniformly elliptic and parabolic fully nonlinear equations

    Directory of Open Access Journals (Sweden)

    M. G. Crandall

    1999-07-01

    Full Text Available We study existence of continuous weak (viscosity solutions of Dirichlet and Cauchy-Dirichlet problems for fully nonlinear uniformly elliptic and parabolic equations. Two types of results are obtained in contexts where uniqueness of solutions fails or is unknown. For equations with merely measurable coefficients we prove solvability of the problem, while in the continuous case we construct maximal and minimal solutions. Necessary barriers on external cones are also constructed.

  20. Results of including geometric nonlinearities in an aeroelastic model of an F/A-18

    Science.gov (United States)

    Buttrill, Carey S.

    1989-01-01

    An integrated, nonlinear simulation model suitable for aeroelastic modeling of fixed-wing aircraft has been developed. While the author realizes that the subject of modeling rotating, elastic structures is not closed, it is believed that the equations of motion developed and applied herein are correct to second order and are suitable for use with typical aircraft structures. The equations are not suitable for large elastic deformation. In addition, the modeling framework generalizes both the methods and terminology of non-linear rigid-body airplane simulation and traditional linear aeroelastic modeling. Concerning the importance of angular/elastic inertial coupling in the dynamic analysis of fixed-wing aircraft, the following may be said. The rigorous inclusion of said coupling is not without peril and must be approached with care. In keeping with the same engineering judgment that guided the development of the traditional aeroelastic equations, the effect of non-linear inertial effects for most airplane applications is expected to be small. A parameter does not tell the whole story, however, and modes flagged by the parameter as significant also need to be checked to see if the coupling is not a one-way path, i.e., the inertially affected modes can influence other modes.

  1. Analytical treatment of the nonlinear electron cloud effect and the combined effects with beam-beam and space charge nonlinear forces in storage rings

    International Nuclear Information System (INIS)

    Gao Jie

    2009-01-01

    In this paper we treat first some nonlinear beam dynamics problems in storage rings, such as beam dynamic apertures due to magnetic multipoles, wiggles, beam-beam effects, nonlinear space charge effect, and then nonlinear electron cloud effect combined with beam-beam and space charge effects, analytically. This analytical treatment is applied to BEPC II. The corresponding analytical expressions developed in this paper are useful both in understanding the physics behind these problems and also in making practical quick hand estimations. (author)

  2. Nonlinear free vibration of piezoelectric nanobeams incorporating surface effects

    International Nuclear Information System (INIS)

    Hosseini-Hashemi, Shahrokh; Nahas, Iman; Fakher, Mahmood; Nazemnezhad, Reza

    2014-01-01

    In this study, the nonlinear free vibration of piezoelectric nanobeams incorporating surface effects (surface elasticity, surface tension, and surface density) is studied. The governing equation of the piezoelectric nanobeam is derived within the framework of Euler–Bernoulli beam theory with the von Kármán geometric nonlinearity. In order to satisfy the balance conditions between the nanobeam bulk and its surfaces, the component of the bulk stress, σ zz , is assumed to vary linearly through the nanobeam thickness. An exact solution is obtained for the natural frequencies of a simply supported piezoelectric nanobeam in terms of the Jacobi elliptic functions using the free vibration mode shape of the corresponding linear problem. Then, the influences of the surface effects and the piezoelectric field on the nonlinear free vibration of nanobeams made of aluminum and silicon with positive and negative surface elasticity, respectively, have been studied for various properties of the piezoelectric field, various nanobeam sizes and amplitude ratios. It is observed that if the Young’s modulus of a nanobeam is lower, the effect of the piezoelectric field on the frequency ratios (FRs) of the nanobeam will be greater. In addition, it is seen that by increasing the nanobeam length so that the nanobeam cross section is set to be constant, the surface effects and the piezoelectric field with negative voltage values increases the FRs, whereas it is the other way around when the nanobeam cross section is assumed to be dependent on the length of the nanobeam. (paper)

  3. Nonlinear resonance islands and modulational effects in a proton synchrotron

    International Nuclear Information System (INIS)

    Satogata, T.J.

    1993-01-01

    The authors examine one-dimensional and two-dimensional nonlinear resonance islands created in the transverse phase space of a proton synchrotron by nonlinear magnets. The authors examine application of the theoretical framework constructed to the phenomenon of modulational diffusion in a collider model of the Fermilab Tevatron. For the one-dimensional resonance island system, the authors examine the effects of two types of modulational perturbations on the stability of these resonance islands: Tune modulation and beta function modulation. Hamiltonian models are presented which predict stability boundaries that depend on only three parameters: The strength and frequency of the modulation and the frequency of small oscillations inside the resonance island. The tune modulation model is successfully tested in experiment, where frequency domain analysis coupled with tune modulation is demonstrated to be useful in measuring the strength of a nonlinear resonance. Nonlinear resonance islands are examined in two transverse dimensions in the presence of coupling and linearly independent crossing resonances. The authors present a first-order Hamiltonian model which predicts fixed point locations, but does not reproduce small oscillation frequencies seen in tracking. Particle tracking is presented which shows evidence of two-dimensional persistent signals, and the authors make suggestions on methods for observing such signals in future experiment. The authors apply the tune modulation stability diagram to the explicitly two-dimensional phenomenon of modulational diffusion in the Fermilab Tevatron with beam-beam kicks as the source of nonlinearity. The amplitude growth created by this mechanism in simulation is exponential rather than root-time as predicted by modulational diffusion models. The authors comment upon the luminosity and lifetime limitations such a mechanism implies in a proton storage ring

  4. Effects of high light intensities on the optical Kerr nonlinearity of semiconducting polymers

    International Nuclear Information System (INIS)

    Charra, Fabrice

    1990-01-01

    Experimental investigations, in the picosecond time scale, of the Kerr type optical nonlinearity (or pump and probe) are presented. The nonlinear molecules semiconducting polymers of the type poly-diacetylene. The degenerate case (pump and probe at the same frequency) has been studied by four wave mixing at 1064 nm, in the configuration of phase conjugation. It is shown that the response is dominated by high orders of nonlinearity. The results are analysed in terms of two photon resonance. The non-degenerate case is studied by two wave mixing or in the optical Kerr gate experiment. The optical Stark effect and the differential spectra of photoinduced species are analysed. Two photon excitations at 1064 nm and one photon excitations at 532 nm are compared. A consequence of the mechanism of the nonlinearity is the possibility of generating phase conjugate waves at double frequency. The theoretical analysis and the experimental demonstration of this process are presented. The experiment is only sensitive to nonlinearities of the fifth order or more and thus allows to clarify its origins and dynamics. Finally, quantum modelling and calculations of the nonlinear optical responses, developed for the interpretations of the above experiments, are presented. (author) [fr

  5. Imprint of non-linear effects on HI intensity mapping on large scales

    Energy Technology Data Exchange (ETDEWEB)

    Umeh, Obinna, E-mail: umeobinna@gmail.com [Department of Physics and Astronomy, University of the Western Cape, Cape Town 7535 (South Africa)

    2017-06-01

    Intensity mapping of the HI brightness temperature provides a unique way of tracing large-scale structures of the Universe up to the largest possible scales. This is achieved by using a low angular resolution radio telescopes to detect emission line from cosmic neutral Hydrogen in the post-reionization Universe. We use general relativistic perturbation theory techniques to derive for the first time the full expression for the HI brightness temperature up to third order in perturbation theory without making any plane-parallel approximation. We use this result and the renormalization prescription for biased tracers to study the impact of nonlinear effects on the power spectrum of HI brightness temperature both in real and redshift space. We show how mode coupling at nonlinear order due to nonlinear bias parameters and redshift space distortion terms modulate the power spectrum on large scales. The large scale modulation may be understood to be due to the effective bias parameter and effective shot noise.

  6. Comparison of Nonlinear Model Results Using Modified Recorded and Synthetic Ground Motions

    International Nuclear Information System (INIS)

    Spears, Robert E.; Wilkins, J. Kevin

    2011-01-01

    A study has been performed that compares results of nonlinear model runs using two sets of earthquake ground motion time histories that have been modified to fit the same design response spectra. The time histories include applicable modified recorded earthquake ground motion time histories and synthetic ground motion time histories. The modified recorded earthquake ground motion time histories are modified from time history records that are selected based on consistent magnitude and distance. The synthetic ground motion time histories are generated using appropriate Fourier amplitude spectrums, Arias intensity, and drift correction. All of the time history modification is performed using the same algorithm to fit the design response spectra. The study provides data to demonstrate that properly managed synthetic ground motion time histories are reasonable for use in nonlinear seismic analysis.

  7. Nonlinear Analysis and Preliminary Testing Results of a Hybrid Wing Body Center Section Test Article

    Science.gov (United States)

    Przekop, Adam; Jegley, Dawn C.; Rouse, Marshall; Lovejoy, Andrew E.; Wu, Hsi-Yung T.

    2015-01-01

    A large test article was recently designed, analyzed, fabricated, and successfully tested up to the representative design ultimate loads to demonstrate that stiffened composite panels with through-the-thickness reinforcement are a viable option for the next generation large transport category aircraft, including non-conventional configurations such as the hybrid wing body. This paper focuses on finite element analysis and test data correlation of the hybrid wing body center section test article under mechanical, pressure and combined load conditions. Good agreement between predictive nonlinear finite element analysis and test data is found. Results indicate that a geometrically nonlinear analysis is needed to accurately capture the behavior of the non-circular pressurized and highly-stressed structure when the design approach permits local buckling.

  8. Nonlinear waves in reaction-diffusion systems: The effect of transport memory

    International Nuclear Information System (INIS)

    Manne, K. K.; Hurd, A. J.; Kenkre, V. M.

    2000-01-01

    Motivated by the problem of determining stress distributions in granular materials, we study the effect of finite transport correlation times on the propagation of nonlinear wave fronts in reaction-diffusion systems. We obtain results such as the possibility of spatial oscillations in the wave-front shape for certain values of the system parameters and high enough wave-front speeds. We also generalize earlier known results concerning the minimum wave-front speed and shape-speed relationships stemming from the finiteness of the correlation times. Analytic investigations are made possible by a piecewise linear representation of the nonlinearity. (c) 2000 The American Physical Society

  9. Nonlinear waves in reaction-diffusion systems: The effect of transport memory

    Science.gov (United States)

    Manne, K. K.; Hurd, A. J.; Kenkre, V. M.

    2000-04-01

    Motivated by the problem of determining stress distributions in granular materials, we study the effect of finite transport correlation times on the propagation of nonlinear wave fronts in reaction-diffusion systems. We obtain results such as the possibility of spatial oscillations in the wave-front shape for certain values of the system parameters and high enough wave-front speeds. We also generalize earlier known results concerning the minimum wave-front speed and shape-speed relationships stemming from the finiteness of the correlation times. Analytic investigations are made possible by a piecewise linear representation of the nonlinearity.

  10. Numerical study of bandwidth effect on stimulated Raman backscattering in nonlinear regime

    Science.gov (United States)

    Zhou, H. Y.; Xiao, C. Z.; Zou, D. B.; Li, X. Z.; Yin, Y.; Shao, F. Q.; Zhuo, H. B.

    2018-06-01

    Nonlinear behaviors of stimulated Raman scattering driven by finite bandwidth pumps are studied by one dimensional particle-in-cell simulations. The broad spectral feature of plasma waves and backscattered light reveals the different coupling and growth mechanisms, which lead to the suppression effect before the deep nonlinear stage. It causes nonperiodic plasma wave packets and reduces packet and etching velocities. Based on the negative frequency shift and electron energy distribution, the long-time evolution of instability can be divided into two stages by the relaxation time. It is a critical time after which the alleviation effects of nonlinear frequency shift and hot electrons are replaced by enhancement. Thus, the broadband pump suppresses instability at early time. However, it aggravates in the deep nonlinear stage by lifting the saturation level due to the coupling of the incident pump with each frequency shifted plasma wave. Our simulation results show that the nonlinear effects are valid in a bandwidth range from 2.25% to 3.0%, and the physics are similar within a nearby parameter space.

  11. Effective potentials in nonlinear polycrystals and quadrature formulae

    Science.gov (United States)

    Michel, Jean-Claude; Suquet, Pierre

    2017-08-01

    This study presents a family of estimates for effective potentials in nonlinear polycrystals. Noting that these potentials are given as averages, several quadrature formulae are investigated to express these integrals of nonlinear functions of local fields in terms of the moments of these fields. Two of these quadrature formulae reduce to known schemes, including a recent proposition (Ponte Castañeda 2015 Proc. R. Soc. A 471, 20150665 (doi:10.1098/rspa.2015.0665)) obtained by completely different means. Other formulae are also reviewed that make use of statistical information on the fields beyond their first and second moments. These quadrature formulae are applied to the estimation of effective potentials in polycrystals governed by two potentials, by means of a reduced-order model proposed by the authors (non-uniform transformation field analysis). It is shown how the quadrature formulae improve on the tangent second-order approximation in porous crystals at high stress triaxiality. It is found that, in order to retrieve a satisfactory accuracy for highly nonlinear porous crystals under high stress triaxiality, a quadrature formula of higher order is required.

  12. Nonlinear Effects at the Fermilab Recycler e-Cloud Instability

    Energy Technology Data Exchange (ETDEWEB)

    Balbekov, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2016-06-10

    Theoretical analysis of e-cloud instability in the Fermilab Recycler is represented in the paper. The e-cloud in strong magnetic field is treated as a set of immovable snakes each being initiated by some proton bunch. It is shown that the instability arises because of injection errors of the bunches which increase in time and from bunch to bunch along the batch being amplified by the e-cloud electric field. The particular attention is given to nonlinear additions to the cloud field. It is shown that the nonlinearity is the main factor which restricts growth of the bunch amplitude. Possible role of the field free parts of the Recycler id discussed as well. Results of calculations are compared with experimental data demonstrating good correlation.

  13. Effects of structural nonlinearity and foundation sliding on probabilistic response of a nuclear structure

    International Nuclear Information System (INIS)

    Hashemi, Alidad; Elkhoraibi, Tarek; Ostadan, Farhang

    2015-01-01

    Highlights: • Probabilistic SSI analysis including structural nonlinearity and sliding are shown. • Analysis is done for a soil and a rock site and probabilistic demands are obtained. • Structural drift ratios and In-structure response spectra are evaluated. • Structural nonlinearity significantly impacts local demands in the structure. • Sliding generally reduces seismic demands and can be accommodated in design. - Abstract: This paper examines the effects of structural nonlinearity and foundation sliding on the results of probabilistic structural analysis of a typical nuclear structure where structural nonlinearity, foundation sliding and soil-structure interaction (SSI) are explicitly included. The evaluation is carried out for a soil and a rock site at 10"4, 10"5, and 10"6 year return periods (1E − 4, 1E − 5, and 1E − 6 hazard levels, respectively). The input motions at each considered hazard level are deaggregated into low frequency (LF) and high frequency (HF) motions and a sample size of 30 is used for uncertainty propagation. The statistical distribution of structural responses including story drifts, and in-structure response spectra (ISRS) as well as foundation sliding displacements are examined. The probabilistic implementation of explicit structural nonlinearity and foundation sliding in combination with the SSI effects are demonstrated using nonlinear response history analysis (RHA) of the structure with the foundation motions obtained from elastic SSI analyses, which are applied as input to fixed-base inelastic analyses. This approach quantifies the expected structural nonlinearity and sliding for the particular structural configuration and provides a robust analytical basis for the estimation of the probabilistic distribution of selected demands parameters both at the design level and beyond design level seismic input. For the subject structure, the inclusion of foundation sliding in the analysis is found to have reduced both

  14. Nonlinear soil parameter effects on dynamic embedment of offshore pipeline on soft clay

    Directory of Open Access Journals (Sweden)

    Su Young Yu

    2015-03-01

    Full Text Available In this paper, the effects of nonlinear soft clay on dynamic embedment of offshore pipeline were investigated. Seabed embedment by pipe-soil interactions has impacts on the structural boundary conditions for various subsea structures such as pipeline, riser, pile, and many other systems. A number of studies have been performed to estimate real soil behavior, but their estimation of seabed embedment has not been fully identified and there are still many uncertainties. In this regards, comparison of embedment between field survey and existing empirical models has been performed to identify uncertainties and investigate the effect of nonlinear soil parameter on dynamic embedment. From the comparison, it is found that the dynamic embedment with installation effects based on nonlinear soil model have an influence on seabed embedment. Therefore, the pipe embedment under dynamic condition by nonlinear para- meters of soil models was investigated by Dynamic Embedment Factor (DEF concept, which is defined as the ratio of the dynamic and static embedment of pipeline, in order to overcome the gap between field embedment and currently used empirical and numerical formula. Although DEF through various researches is suggested, its range is too wide and it does not consider dynamic laying effect. It is difficult to find critical parameters that are affecting to the embedment result. Therefore, the study on dynamic embedment factor by soft clay parameters of nonlinear soil model was conducted and the sensitivity analyses about parameters of nonlinear soil model were performed as well. The tendency on dynamic embedment factor was found by conducting numerical analyses using OrcaFlex software. It is found that DEF was influenced by shear strength gradient than other factors. The obtained results will be useful to understand the pipe embedment on soft clay seabed for applying offshore pipeline designs such as on-bottom stability and free span analyses.

  15. Nonlinear effects of energetic particle driven instabilities in tokamaks

    International Nuclear Information System (INIS)

    Bruedgam, Michael

    2010-01-01

    In a tokamak plasma, a population of superthermal particles generated by heating methods can lead to a destabilization of various MHD modes. Due to nonlinear wave-particle interactions, a consequential fast particle redistribution reduces the plasma heating and can cause severe damages to the wall of the fusion device. In order to describe the wave-particle interaction, the drift-kinetic perturbative HAGIS code is applied which evolves the particle trajectories and the waves nonlinearly. For a simulation speed-up, the 6-d particle phase-space is reduced by the guiding centre approach to a 5-d description. The eigenfunction of the wave is assumed to be invariant, but its amplitude and phase is altered in time. A sophisticated δ/f-method is employed to model the change in the fast particle distribution so that numerical noise and the excessive number of simulated Monte-Carlo points are reduced significantly. The original code can only calculate the particle redistribution inside the plasma region. Therefore, a code extension has been developed during this thesis which enlarges the simulation region up to the vessel wall. By means of numerical simulations, this thesis addresses the problem of nonlinear waveparticle interactions in the presence of multiple MHD modes with significantly different eigenfrequencies and the corresponding fast particle transport inside the plasma. In this context, a new coupling mechanism between resonant particles and waves has been identified that leads to enhanced mode amplitudes and fast particle losses. The extension of the code provides for the first time the possibility of a quantitative and qualitative comparison between simulation results and recent measurements in the experiment. The findings of the comparison serve as a validation of both the theoretical model and the interpretation of the experimental results. Thus, a powerful interface tool has been developed for a deeper insight of nonlinear wave-particle interaction. (orig.)

  16. Nonlinear effects of energetic particle driven instabilities in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Bruedgam, Michael

    2010-03-25

    In a tokamak plasma, a population of superthermal particles generated by heating methods can lead to a destabilization of various MHD modes. Due to nonlinear wave-particle interactions, a consequential fast particle redistribution reduces the plasma heating and can cause severe damages to the wall of the fusion device. In order to describe the wave-particle interaction, the drift-kinetic perturbative HAGIS code is applied which evolves the particle trajectories and the waves nonlinearly. For a simulation speed-up, the 6-d particle phase-space is reduced by the guiding centre approach to a 5-d description. The eigenfunction of the wave is assumed to be invariant, but its amplitude and phase is altered in time. A sophisticated {delta}/f-method is employed to model the change in the fast particle distribution so that numerical noise and the excessive number of simulated Monte-Carlo points are reduced significantly. The original code can only calculate the particle redistribution inside the plasma region. Therefore, a code extension has been developed during this thesis which enlarges the simulation region up to the vessel wall. By means of numerical simulations, this thesis addresses the problem of nonlinear waveparticle interactions in the presence of multiple MHD modes with significantly different eigenfrequencies and the corresponding fast particle transport inside the plasma. In this context, a new coupling mechanism between resonant particles and waves has been identified that leads to enhanced mode amplitudes and fast particle losses. The extension of the code provides for the first time the possibility of a quantitative and qualitative comparison between simulation results and recent measurements in the experiment. The findings of the comparison serve as a validation of both the theoretical model and the interpretation of the experimental results. Thus, a powerful interface tool has been developed for a deeper insight of nonlinear wave-particle interaction

  17. Nonlinear effects in propagation of long-range surface plasmon polaritons in gold strip waveguides

    DEFF Research Database (Denmark)

    Lysenko, Oleg; Bache, Morten; Malureanu, Radu

    2016-01-01

    cladding. The optical characterization was performed using a high power picosecond laser at 1064 nm. The experiments reveal two nonlinear optical effects: nonlinear power transmission and spectral broadening of the LRSPP mode in the waveguides. Both nonlinear optical effects depend on the gold layer...

  18. Nonlinear polarization effects in a birefringent single mode optical fiber

    International Nuclear Information System (INIS)

    Ishiekwene, G.C.; Mensah, S.Y.; Brown, C.S.

    2001-04-01

    The nonlinear polarization effects in a birefringent single mode optical fiber is studied using Jacobi elliptic functions. We find that the polarization state of the propagating beam depends on the initial polarization as well as the intensity of the input light in a complicated way. The Stokes polarization parameters are either periodic or aperiodic depending on the value of the Jacobian modulus. Our calculations suggest that the effective beat length of the fiber can become infinite at a higher critical value of the input power when polarization dependent losses are considered. (author)

  19. Non-linear effective Lagrangian treatment of 'Penguin' interaction

    International Nuclear Information System (INIS)

    Pham, T.N.

    1984-01-01

    Using the non-linear effective lagrangian technique, we show explicitly that only derivative coupling is allowed for the K - π, K -> 2 π and K -> 3 π transitions induced by the ΔS = 1 Penguin operator of SVZ in agreement with chiral symmetry requirements. From a derivative coupling (3, anti 3) mass term and the SU(3) breaking effect for fsub(K)/fsub(π), we estimate the strength of the Penguin interactions and find it too small to account for the ΔI = 1/2 amplitude. (orig.)

  20. THEORETICAL EVALUATION OF NONLINEAR EFFECTS ON OPTICAL WDM NETWORKS WITH VARIOUS FIBER TYPES

    Directory of Open Access Journals (Sweden)

    YASIN M. KARFAA

    2010-09-01

    Full Text Available A theoretical study is carried out to evaluate the performance of an opticalwavelength division multiplexing (WDM network transmission system in the presenceof crosstalk due to optical fiber nonlinearities. The most significant nonlinear effects inthe optical fiber which are Cross-Phase Modulation (XPM, Four-Wave Mixing (FWM,and Stimulated Raman Scattering (SRS are investigated. Four types of optical fiber areincluded in the analysis; these are: single-mode fiber (SMF, dispersion compensationfiber (DCF, non-zero dispersion fiber (NZDF, and non-zero dispersion shifted fiber(NZDSF. The results represent the standard deviation of nonlinearity induced crosstalknoise power due to FWM and SRS, XPM power penalty for SMF, DCF, NZDF, andNZDSF types of fiber, besides the Bit Error Rate (BER for the three nonlinear effectsusing standard fiber type (SMF. It is concluded that three significant fiber nonlinearitiesare making huge limitations against increasing the launched power which is desired,otherwise, lower values of launched power limit network expansion including length,distance, covered areas, and number of users accessing the WDM network, unlesssuitable precautions are taken to neutralize the nonlinear effects. Besides, various fibertypes are not behaving similarly towards network parameters.

  1. Simulation of creep effects in framework of a geometrically nonlinear endochronic theory of inelasticity

    Science.gov (United States)

    Zabavnikova, T. A.; Kadashevich, Yu. I.; Pomytkin, S. P.

    2018-05-01

    A geometric non-linear endochronic theory of inelasticity in tensor parametric form is considered. In the framework of this theory, the creep strains are modelled. The effect of various schemes of applying stresses and changing of material properties on the development of creep strains is studied. The constitutive equations of the model are represented by non-linear systems of ordinary differential equations which are solved in MATLAB environment by implicit difference method. Presented results demonstrate a good qualitative agreement of theoretical data and experimental observations including the description of the tertiary creep and pre-fracture of materials.

  2. Local-field enhancement effect on the nonlinear optical response of gold-silver nanoplanets.

    Science.gov (United States)

    Cesca, T; Calvelli, P; Battaglin, G; Mazzoldi, P; Mattei, G

    2012-02-13

    We report on the nonlinear optical properties of Au-Ag nanoplanets produced by ion implantation and irradiation in silica, experimentally investigated by means of the single beam z-scan technique. The measurements provided experimental evidence of the intense local-field enhancement effect theoretically demonstrated for these plasmonic nanosystems. In particular, this has a dramatic impact on their nonlinear absorption behavior and results in a tunable changeover from reverse saturable absorption to saturable absorption by slightly varying the pump intensity and in the possibility to activate and observe nonlinear phenomena of the electron dynamics otherwise unaccessible in the intensity range that can be employed to study these materials. Finally, for the nanoplanet configuration we found a dramatic decrease of the intensity-dependent absorption coefficient, which could be very promising for obtaining optical gain materials.

  3. Viscous Flow over Nonlinearly Stretching Sheet with Effects of Viscous Dissipation

    Directory of Open Access Journals (Sweden)

    Javad Alinejad

    2012-01-01

    Full Text Available The flow and heat transfer characteristics of incompressible viscous flow over a nonlinearly stretching sheet with the presence of viscous dissipation is investigated numerically. The similarity transformation reduces the time-independent boundary layer equations for momentum and thermal energy into a set of coupled ordinary differential equations. The obtained equations, including nonlinear equation for the velocity field and differential equation by variable coefficient for the temperature field , are solved numerically by using the fourth order of Runge-Kutta integration scheme accompanied by shooting technique with Newton-Raphson iteration method. The effect of various values of Prandtl number, Eckert number and nonlinear stretching parameter are studied. The results presented graphically show some behaviors such as decrease in dimensionless temperature due to increase in Pr number, and curve relocations are observed when heat dissipation is considered.

  4. Optical super-resolution effect induced by nonlinear characteristics of graphene oxide films

    Science.gov (United States)

    Zhao, Yong-chuang; Nie, Zhong-quan; Zhai, Ai-ping; Tian, Yan-ting; Liu, Chao; Shi, Chang-kun; Jia, Bao-hua

    2018-01-01

    In this work, we focus on the optical super-resolution effect induced by strong nonlinear saturation absorption (NSA) of graphene oxide (GO) membranes. The third-order optical nonlinearities are characterized by the canonical Z-scan technique under femtosecond laser (wavelength: 800 nm, pulse width: 100 fs) excitation. Through controlling the applied femtosecond laser energy, NSA of the GO films can be tuned continuously. The GO film is placed at the focal plane as a unique amplitude filter to improve the resolution of the focused field. A multi-layer system model is proposed to present the generation of a deep sub-wavelength spot associated with the nonlinearity of GO films. Moreover, the parameter conditions to achieve the best resolution (˜λ/6) are determined entirely. The demonstrated results here are useful for high density optical recoding and storage, nanolithography, and super-resolution optical imaging.

  5. Destruction of Anderson localization by nonlinearity in kicked rotator at different effective dimensions

    International Nuclear Information System (INIS)

    Ermann, L; Shepelyansky, D L

    2014-01-01

    We study numerically the frequency modulated kicked nonlinear rotator with effective dimension d=1,2,3,4. We follow the time evolution of the model up to 10 9 kicks and determine the exponent α of subdiffusive spreading which changes from 0.35 to 0.5 when the dimension changes from d = 1 to 4. All results are obtained in a regime of relatively strong Anderson localization well below the Anderson transition point existing for d = 3, 4. We explain that this variation of the exponent is different from the usual d− dimensional Anderson models with local nonlinearity where α drops with increasing d. We also argue that the renormalization arguments proposed by Cherroret N et al (arXiv:1401.1038) are not valid for this model and the Anderson model with local nonlinearity in d = 3. (paper)

  6. Nonlinear photoresponse of field effect transistors terahertz detectors at high irradiation intensities

    International Nuclear Information System (INIS)

    But, D. B.; Drexler, C.; Ganichev, S. D.; Sakhno, M. V.; Sizov, F. F.; Dyakonova, N.; Drachenko, O.; Gutin, A.; Knap, W.

    2014-01-01

    Terahertz power dependence of the photoresponse of field effect transistors, operating at frequencies from 0.1 to 3 THz for incident radiation power density up to 100 kW/cm 2 was studied for Si metal–oxide–semiconductor field-effect transistors and InGaAs high electron mobility transistors. The photoresponse increased linearly with increasing radiation intensity up to the kW/cm 2 range. Nonlinearity followed by saturation of the photoresponse was observed for all investigated field effect transistors for intensities above several kW/cm 2 . The observed photoresponse nonlinearity is explained by nonlinearity and saturation of the transistor channel current. A theoretical model of terahertz field effect transistor photoresponse at high intensity was developed. The model explains quantitative experimental data both in linear and nonlinear regions. Our results show that dynamic range of field effect transistors is very high and can extend over more than six orders of magnitudes of power densities (from ∼0.5 mW/cm 2 to ∼5 kW/cm 2 )

  7. Nonlinear realizations and effective Lagrangian densities for nonlinear σ-models

    International Nuclear Information System (INIS)

    Hamilton-Charlton, Jason Dominic

    2003-01-01

    Nonlinear realizations of the groups SU(N), SO(m) and SO(t,s) are analysed, described by the coset spaces SU(N) / SU(N-1) x U(1), SO(m) / SO(m-1), SO(1,m-1) / SO(1,m-2) and SO(m) / SO(m-2 x SO(2). The analysis consists of determining the transformation properties of the Goldstone Bosons, constructing the most general possible Lagrangian for the realizations, and as a result identifying the coset space metric. We view the λ matrices of SU(N) as being the basis of an (N 2 - 1) dimensional real vector space, and from this we learn how to construct the basis of a Cartan Subspace associated with a vector. This results in a mathematical structure which allows us to find expressions for coset representative elements used in the analysis. This structure is not only relevant to SU(N) breaking models, but may also be used to find results in SO(m) and SO(1,m - 1) breaking models. (author)

  8. Non-linear effects in the Boltzmann equation

    International Nuclear Information System (INIS)

    Barrachina, R.O.

    1985-01-01

    The Boltzmann equation is studied by defining an integral transformation of the energy distribution function for an isotropic and homogeneous gas. This transformation may be interpreted as a linear superposition of equilibrium states with variable temperatures. It is shown that the temporal evolution features of the distribution function are determined by the singularities of said transformation. This method is applied to Maxwell and Very Hard Particle interaction models. For the latter, the solution of the Boltzmann equation with the solution of its linearized version is compared, finding out many basic discrepancies and non-linear effects. This gives a hint to propose a new rational approximation method with a clear physical meaning. Applying this technique, the relaxation features of the BKW (Bobylev, Krook anf Wu) mode is analyzed, finding a conclusive counter-example for the Krook and Wu conjecture. The anisotropic Boltzmann equation for Maxwell models is solved as an expansion in terms of the eigenfunctions of the corresponding linearized collision operator, finding interesting transient overpopulation and underpopulation effects at thermal energies as well as a new preferential spreading effect. By analyzing the initial collision, a criterion is established to deduce the general features of the final approach to equilibrium. Finally, it is shown how to improve the convergence of the eigenfunction expansion for high energy underpopulated distribution functions. As an application of this theory, the linear cascade model for sputtering is analyzed, thus finding out that many differences experimentally observed are due to non-linear effects. (M.E.L.) [es

  9. Nonlinear vibration behaviors of suspended cables under two-frequency excitation with temperature effects

    Science.gov (United States)

    Zhao, Yaobing; Huang, Chaohui; Chen, Lincong; Peng, Jian

    2018-03-01

    The aim of this paper is to investigate temperature effects on the nonlinear vibration behaviors of suspended cables under two-frequency excitation. For this purpose, two combination and simultaneous resonances are chosen and studied in detail. First of all, based on the assumptions of the temperature effects, the partial differential equations of the in-plane and out-of-plane motions with thermal effects under multi-frequency excitations are obtained. The Galerkin method is adopted to discretize the nonlinear dynamic equations, and the single-mode planar discretization is considered. Then, in the absence of the primary and internal resonances, the frequency response equations are obtained by using the multiple scales method. The stability analyses are conducted via investigating the nature of the singular points of equations. After that, temperature effects on nonlinear vibration characteristics of the first symmetric mode are studied. Parametric investigations of temperature effects on corresponding non-dimensional factors and coefficients of linear and nonlinear terms are performed. Numerical results are presented to show the temperature effects via the frequency-response curves and detuning-phase curves of four different sag-to-span ratios. It is found out that effects of temperature variations would lead to significant quantitative and/or qualitative changes of the nonlinear vibration properties, and these effects are closely related to the sag-to-span ratio and the degree of the temperature variation. Specifically, the softening/hardening-type spring behaviors, the response amplitude, the range of the resonance, the intersection and number of branches, the number and phase of the steady-state solutions are all affected by the temperature changes.

  10. Theory of plasmonic effects in nonlinear optics: the case of graphene

    Science.gov (United States)

    Rostami, Habib; Katsnelson, Mikhail I.; Polini, Marco; Mikhail I. Katsnelson Collaboration; Habib Rostami; Marco Polini Collaboration

    The nonlinear optical properties of two-dimensional electronic systems are beginning to attract considerable interest both in the theoretical and experimental sectors. Recent experiments on the nonlinear optical properties of graphene reveal considerably strong third harmonic generation and four-wave mixing of this single-atomic-layer electronic system. We develop a large-N theory of electron-electron interaction corrections to multi-legged Feynman diagrams describing second- and third-order nonlinear response functions. Our theory is completely general and is useful to understand all second- and third-order nonlinear effects, including harmonic generation, wave mixing, and photon drag. We apply our theoretical framework to the case of graphene, by carrying out microscopic calculations of the second- and third-order nonlinear response functions of an interacting two-dimensional gas of massless Dirac fermions. We compare our results with recent measurements, where all-optical launching of graphene plasmons has been achieved. This work was supported by Fondazione Istituto Italiano di Tecnologia, the European Union's Horizon 2020 research and innovation programme under Grant agreement No. 696656 GrapheneCore, and the ERC Advanced Grant 338957 FEMTO/NANO (M.I.K.).

  11. Nonlinear optical effects in pure and N-doped semiconductors

    International Nuclear Information System (INIS)

    Donlagic, N.S.

    2000-01-01

    Over the last decades, the nonlinear optical properties of condensed matter systems have been an attractive and fruitful field of research. While the linear response functions of solids provide information about the elementary excitations of the systems, nonlinear optical experiments give insight into the dynamics of the fundamental many-body processes which are initiated by the external excitations. Stimulated by the experimental results, new theoretical concepts and methods have been developed in order to relate the observed phenomena to the microscopic properties of the investigated materials. The present work deals with the study of the nonlinear dynamics of the optical interband polarization in pure and n-doped semiconductors.In the first part of the thesis, the relaxation behavior of optically excited electron-hole pairs in a one-dimensional semiconductor, which are coupled to longitudinal optical phonons with an initial lattice temperature T>0, is studied with the help of quantum kinetic equations. Apart from Hartree-Fock-like Coulomb contributions, these equations contain additional Coulomb terms, the so-called vertex corrections, by which the influence of the electron-electron interaction on the electron-phonon scattering processes is taken into account. The numerical studies indicate that the vertex corrections are essential for a correct description of the excitonic dynamics.In the second part of the thesis, the attention is shifted to the characteristics of the optical response of a one-dimensional n-doped two-band semiconductor whose conduction band has been linearized with respect to the two Fermi points. Due to the linearization it is possible to calculate the linear and nonlinear response functions of the interacting electron system exactly. These response functions are then used in order to determine the linear absorption spectrum and the time-integrated signal of a degenerated four-wave-mixing experiment. It is shown that the well-known features

  12. Non-linear direct effects of acid rain on leaf photosynthetic rate of terrestrial plants.

    Science.gov (United States)

    Dong, Dan; Du, Enzai; Sun, Zhengzhong; Zeng, Xuetong; de Vries, Wim

    2017-12-01

    Anthropogenic emissions of acid precursors have enhanced global occurrence of acid rain, especially in East Asia. Acid rain directly suppresses leaf function by eroding surface waxes and cuticle and leaching base cations from mesophyll cells, while the simultaneous foliar uptake of nitrates in rainwater may directly benefit leaf photosynthesis and plant growth, suggesting a non-linear direct effect of acid rain. By synthesizing data from literature on acid rain exposure experiments, we assessed the direct effects of acid rain on leaf photosynthesis across 49 terrestrial plants in China. Our results show a non-linear direct effect of acid rain on leaf photosynthetic rate, including a neutral to positive effect above pH 5.0 and a negative effect below that pH level. The acid rain sensitivity of leaf photosynthesis showed no significant difference between herbs and woody species below pH 5.0, but the impacts above that pH level were strongly different, resulting in a significant increase in leaf photosynthetic rate of woody species and an insignificant effect on herbs. Our analysis also indicates a positive effect of the molar ratio of nitric versus sulfuric acid in the acid solution on leaf photosynthetic rate. These findings imply that rainwater acidity and the composition of acids both affect the response of leaf photosynthesis and therefore result in a non-linear direct effect. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Nonlinear cosmological consistency relations and effective matter stresses

    International Nuclear Information System (INIS)

    Ballesteros, Guillermo; Hollenstein, Lukas; Jain, Rajeev Kumar; Kunz, Martin

    2012-01-01

    We propose a fully nonlinear framework to construct consistency relations for testing generic cosmological scenarios using the evolution of large scale structure. It is based on the covariant approach in combination with a frame that is purely given by the metric, the normal frame. As an example, we apply this framework to the ΛCDM model, by extending the usual first order conditions on the metric potentials to second order, where the two potentials start to differ from each other. We argue that working in the normal frame is not only a practical choice but also helps with the physical interpretation of nonlinear dynamics. In this frame, effective pressures and anisotropic stresses appear at second order in perturbation theory, even for ''pressureless'' dust. We quantify their effect and compare them, for illustration, to the pressure of a generic clustering dark energy fluid and the anisotropic stress in the DGP model. Besides, we also discuss the effect of a mismatch of the potentials on the determination of galaxy bias

  14. Effects of Analog-to-Digital Converter Nonlinearities on Radar Range-Doppler Maps

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dubbert, Dale F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tise, Bertice L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-07-01

    Radar operation, particularly Ground Moving Target Indicator (GMTI) radar modes, are very sensitive to anomalous effects of system nonlinearities. These throw off harmonic spurs that are sometimes detected as false alarms. One significant source of nonlinear behavior is the Analog to Digital Converter (ADC). One measure of its undesired nonlinearity is its Integral Nonlinearity (INL) specification. We examine in this report the relationship of INL to GMTI performance.

  15. Photoconductivity, photoluminescence and optical Kerr nonlinear effects in zinc oxide films containing chromium nanoclusters

    International Nuclear Information System (INIS)

    Torres-Torres, C.; García-Cruz, M.L.; Castañeda, L.; Rangel Rojo, R.; Tamayo-Rivera, L.; Maldonado, A.; Avendaño-Alejo, M.

    2012-01-01

    Chromium doped zinc oxide thin solid films were deposited on soda–lime glass substrates. The photoconductivity of the material and its influence on the optical behavior was evaluated. A non-alkoxide sol–gel synthesis approach was used for the preparation of the samples. An enhancement of the photoluminescence response exhibited by the resulting photoconductive films with embedded chromium nanoclusters is presented. The modification in the photoconduction induced by a 445 nm wavelength was measured and then associated with the participation of the optical absorptive response. In order to investigate the third order optical nonlinearities of the samples, a standard time-resolved Optical Kerr Gate configuration with 80 fs pulses at 830 nm was used and a quasi-instantaneous pure electronic nonlinearity without the contribution of nonlinear optical absorption was observed. We estimate that from the inclusion of Cr nanoclusters into the sample results a strong optical Kerr effect originated by quantum confinement. The large photoluminescence response and the important refractive nonlinearity of the photoconductive samples seem to promise potential applications for the development of multifunctional all-optical nanodevices. - Highlights: ► Enhancement in photoluminescence for chromium doped zinc oxide films is presented. ► A strong and ultrafast optical Kerr effect seems to result from quantum confinement. ► Photoconductive properties for optical and optoelectronic functions were observed.

  16. Photoconductivity, photoluminescence and optical Kerr nonlinear effects in zinc oxide films containing chromium nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Torres, C., E-mail: crstorres@yahoo.com.mx [Seccion de Estudios de Posgrado e Investigacion, ESIME-Z, Instituto Politecnico Nacional, Mexico, DF 07738 (Mexico); Garcia-Cruz, M.L. [Centro de Investigacion en Dispositivos Semiconductores, Benemerita Universidad Autonoma de Puebla, A. P. J-48, Puebla 72570, Mexico (Mexico); Castaneda, L., E-mail: luisca@sirio.ifuap.buap.mx [Instituto de Fisica, Benemerita Universidad Autonoma de Puebla, A. P. J-48, Puebla 72570, Mexico (Mexico); Rangel Rojo, R. [CICESE/Depto. de Optica, A. P. 360, Ensenada, BC 22860 (Mexico); Tamayo-Rivera, L. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Mexico, DF 01000 (Mexico); Maldonado, A. [Depto. de Ing. Electrica, CINVESTAV IPN-SEES, A. P. 14740, Mexico DF 07000 (Mexico); Avendano-Alejo, M., E-mail: imax_aa@yahoo.com.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, A. P. 70-186, 04510, DF (Mexico); and others

    2012-04-15

    Chromium doped zinc oxide thin solid films were deposited on soda-lime glass substrates. The photoconductivity of the material and its influence on the optical behavior was evaluated. A non-alkoxide sol-gel synthesis approach was used for the preparation of the samples. An enhancement of the photoluminescence response exhibited by the resulting photoconductive films with embedded chromium nanoclusters is presented. The modification in the photoconduction induced by a 445 nm wavelength was measured and then associated with the participation of the optical absorptive response. In order to investigate the third order optical nonlinearities of the samples, a standard time-resolved Optical Kerr Gate configuration with 80 fs pulses at 830 nm was used and a quasi-instantaneous pure electronic nonlinearity without the contribution of nonlinear optical absorption was observed. We estimate that from the inclusion of Cr nanoclusters into the sample results a strong optical Kerr effect originated by quantum confinement. The large photoluminescence response and the important refractive nonlinearity of the photoconductive samples seem to promise potential applications for the development of multifunctional all-optical nanodevices. - Highlights: Black-Right-Pointing-Pointer Enhancement in photoluminescence for chromium doped zinc oxide films is presented. Black-Right-Pointing-Pointer A strong and ultrafast optical Kerr effect seems to result from quantum confinement. Black-Right-Pointing-Pointer Photoconductive properties for optical and optoelectronic functions were observed.

  17. Review of radio-frequency, nonlinear effects on the ionosphere

    International Nuclear Information System (INIS)

    Gordon, W.E.; Duncan, L.M.

    1983-01-01

    Modification of the ionosphere by high power radio waves in the megahertz band has been intensively investigated over the past two decades. This research has yielded advances in aeronomy, geophysics, and plasma physics with applications to radio communication and has provided a fruitful interaction of radio theorists and experimentalists. There being almost no linear effects of powerful radio waves on the ionosphere, we concentrate on the nonlinear effects. To put the subject in perspective we trace its history beginning in the early 1930s and highlight the important events up to the late 1960s. We then shift to a phenomenological approach and deal in order with ohmic heating, parametric instabilities, self-focusing and kilometer-scale irregularities, meter-scale irregularities, and a collection of recently discovered effects. We conclude with the observation that stronger international cooperation would benefit this research, and describe a list of promising, difficult challenges

  18. Nonlinear magnetoelectric effect and magnetostriction in piezoelectric CsCuCl{sub 3} in paramagnetic and antiferromagnetic states

    Energy Technology Data Exchange (ETDEWEB)

    Kharkovskiy, A. I., E-mail: akharkovskiy@inbox.ru [International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, 53-421 Wrocław (Poland); L.F. Vereshchagin Institute for High Pressure Physics RAS, 142190 Troitsk, Moscow (Russian Federation); Shaldin, Yu. V. [International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, 53-421 Wrocław (Poland); Institute for Crystallography RAS, Lenin' s Avenue 59, 119333 Moscow (Russian Federation); Nizhankovskii, V. I. [International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, 53-421 Wrocław (Poland)

    2016-01-07

    The direct nonlinear magnetoelectric (ME) effect and the magnetostriction of piezoelectric CsCuCl{sub 3} single crystals were comprehensively studied over a wide temperature range in stationary magnetic fields of up to 14 T. The direct nonlinear ME effect measurements were also performed in pulsed magnetic fields up to 31 T, at liquid helium temperature in the antiferromagnetic (AF) state for the crystallographic direction in which effect has the maximum value. The nonlinear ME effect was quadratic in the paramagnetic state for the whole range of magnetic fields. In the AF state the phase transition between different configurations of spins manifested itself as plateau-like peculiarity on the nonlinear ME effect. The nonlinear ME effect was saturated by the phase transition to the spin-saturated paramagnetic state. Two contributions to the nonlinear ME effects in CsCuCl{sub 3} were extracted from the experimental data: the intrinsic ME effect originated from the magnetoelectric interactions, and the extrinsic one, which resulted from a magnetostriction-induced piezoelectric effect.

  19. The Effect of Friction on the Nonlinear Vibration of the Cracked One-Stage Power Transmission

    Directory of Open Access Journals (Sweden)

    M. Rezaee

    2016-01-01

    Full Text Available : The gear systems are widely used in industry to transmit the power or change the direction of the torque. Due to the extensive usage of the gears, the detailed designing and the subsequent maintenance of these systems are more and more evident. System recognition can be achieved through modeling the system, investigating the system behavior, and comparing the results obtained through the model with the actual system behavior. Up to now, the effect of dry friction has not been taken into account in nonlinear vibration analysis and modeling of a cracked one-stage gear power transmission system. In this paper, the nonlinear vibration of a pair of cracked spur-gear system in presence of dry friction, static transmission error, clearance and time-variant mesh stiffness is investigated. To this end, the time-variant mesh stiffness of an intact tooth is calculated analytically. Then, the tooth root crack is modeled as a cracked cantilever beam. The governing nonlinear equation of motion is extracted accordingly, and in order to consider the effect of dry friction, the governing equation solved by Rung- Kutta method in three separate time spans. Finally, the frequency response and bifurcation diagrams are used to study the effect of the friction and tooth root crack on the nonlinear vibration behavior of the system.

  20. Nonlinear excitation of electron cyclotron waves by a monochromatic strong microwave: computer simulation analysis of the MINIX results

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, H.; Kimura, T.

    1986-01-01

    Triggered by the experimental results of the MINIX, a computer simulation study was initiated on the nonlinear excitation of electrostatic electron cyclotron waves by a monochromatic electromagnetic wave such as the transmitted microwave in the MINIX. The model used assumes that both of the excited waves and exciting (pumping) electromagnetic wave as well as the idler electromagnetic wave propagate in the direction perpendicular to the external magnetic field. The simulation code used for this study was the one-and-two-half dimensional electromagnetic particle code named KEMPO. The simulation result shows the high power electromagnetic wave produces both the backscattered electromagnetic wave and electrostatic electron cyclotron waves as a result of nonlinear parametric instability. Detailed nonlinear microphysics related to the wave excitation is discussed in terms of the nonlinear wave-wave couplings and associated ponderomotive force produced by the high power electromagnetic waves. 2 references, 4 figures.

  1. Nonlinear excitation of electron cyclotron waves by a monochromatic strong microwave: computer simulation analysis of the MINIX results

    International Nuclear Information System (INIS)

    Matsumoto, H.; Kimura, T.

    1986-01-01

    Triggered by the experimental results of the MINIX, a computer simulation study was initiated on the nonlinear excitation of electrostatic electron cyclotron waves by a monochromatic electromagnetic wave such as the transmitted microwave in the MINIX. The model used assumes that both of the excited waves and exciting (pumping) electromagnetic wave as well as the idler electromagnetic wave propagate in the direction perpendicular to the external magnetic field. The simulation code used for this study was the one-and-two-half dimensional electromagnetic particle code named KEMPO. The simulation result shows the high power electromagnetic wave produces both the backscattered electromagnetic wave and electrostatic electron cyclotron waves as a result of nonlinear parametric instability. Detailed nonlinear microphysics related to the wave excitation is discussed in terms of the nonlinear wave-wave couplings and associated ponderomotive force produced by the high power electromagnetic waves. 2 references, 4 figures

  2. Experimental Results and Issues on Equalization for Nonlinear Memory Channel: Pre-Cursor Enhanced Ram-DFE Canceler

    Science.gov (United States)

    Yuan, Lu; LeBlanc, James

    1998-01-01

    This thesis investigates the effects of the High Power Amplifier (HPA) and the filters over a satellite or telemetry channel. The Volterra series expression is presented for the nonlinear channel with memory, and the algorithm is based on the finite-state machine model. A RAM-based algorithm operating on the receiver side, Pre-cursor Enhanced RAM-FSE Canceler (PERC) is developed. A high order modulation scheme , 16-QAM is used for simulation, the results show that PERC provides an efficient and reliable method to transmit data on the bandlimited nonlinear channel. The contribution of PERC algorithm is that it includes both pre-cursors and post-cursors as the RAM address lines, and suggests a new way to make decision on the pre-addresses. Compared with the RAM-DFE structure that only includes post- addresses, the BER versus Eb/NO performance of PERC is substantially enhanced. Experiments are performed for PERC algorithms with different parameters on AWGN channels, and the results are compared and analyzed. The investigation of this thesis includes software simulation and hardware verification. Hardware is setup to collect actual TWT data. Simulation on both the software-generated data and the real-world data are performed. Practical limitations are considered for the hardware collected data. Simulation results verified the reliability of the PERC algorithm. This work was conducted at NMSU in the Center for Space Telemetering and Telecommunications Systems in the Klipsch School of Electrical and Computer Engineering Department.

  3. Recent results on nonlinear delay control systems in honor of Miroslav Krstic

    CERN Document Server

    Pepe, Pierdomenico; Mazenc, Frederic; Karafyllis, Iasson

    2016-01-01

    This volume collects recent advances in nonlinear delay systems, with an emphasis on constructive generalized Lyapunov and predictive approaches that certify stability properties. The book is written by experts in the field and includes two chapters by Miroslav Krstic, to whom this volume is dedicated. This volume is suitable for all researchers in mathematics and engineering who deal with nonlinear delay control problems and students who would like to understand the current state of the art in the control of nonlinear delay systems.

  4. Terahertz Nonlinear Optics in Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias C.

    2013-01-01

    We demonstrate the nonlinear optical effects – selfphase modulation and saturable absorption of a single-cycle THz pulse in a semiconductor. Resulting from THz-induced modulation of Drude plasma, these nonlinear optical effects, in particular, lead to self-shortening and nonlinear spectral...... breathing of a single-cycle THz pulse in a semiconductor....

  5. Study of nonlinear effects in photonic crystals doped with nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R [Department of Physics and Astronomy, University of Western Ontario, London, N6A 3K7 Ontario (Canada)

    2008-07-14

    A theory of nonlinear phenomena has been developed for a photonic crystal in the presence of a pump and a coupling laser field. The crystal is doped with an ensemble of four-level nanoparticle impurities. It is considered that the impurity particles are not only interacting with the photonic crystal but also with each other via dipole-dipole interaction. An expression for the susceptibility has been obtained using the density matrix method. The nonlinear effects due to the coupling and the pump fields have been included in the formulation. The absorption spectrum has been calculated in the presence of the strong coupling and pump fields for an isotropic photonic crystal made from dielectric spheres. The photonic crystal has a gap to midgap ratio of about 21%. It is predicted that the absorption spectrum in the photonic crystal can have zero, one, two or three absorptionless states by tuning one of the transition energies within the bands. This is an interesting phenomenon which can be used to make photonic switching devices. We have also calculated the absorption spectrum in the presence of the dipole-dipole interaction. It is found that a symmetric absorption spectrum changes to an asymmetric one due to this interaction. It is also found that there is a large enhancement in the absorption and the dispersion simultaneously for certain values of the detuning and concentration.

  6. Nonlinear effect of pion production in collisions of atomic nuclei

    International Nuclear Information System (INIS)

    Grin', Yu.T.

    1982-01-01

    The phenomenon of pion production in relativistic nucleon-nucleus and nucleus-nucleus interactions is investigated. The present experimental data are analyzed. It is shown that average multiplicity of pions in the (p, C), (C, C) collision reactions with the momentum p=4.2 GeV/cA and (p, Ar), (Ar, KCl) with the momentum p=2.3 GeV/cA non-linearly depends on the nucleon number. The calculated values of average multiplicity of negative pions per one nucleon of nucleus-pro ectile, probability of pion production and number of nucleon interactions for the investigated reactions are presented as a table. A comparative analysis of average multiplicities of pions per nucleon-participant in the nucleon-nucleus and nucleus-nucleus reactions at the p=2.3 GeV/cA momentum for argon and at the p=4.2 GeV/cA for carbon reveals that decrease of multiplicity by 30-35% is observed in nucleus-nucleus collision. Non-linearity is associated with decrease of effective interaction of each incident nucleon in the collision of nuclei as compared with the number of nucleon interactions in the ''elementary'' nucleon-nucleus reaction. Knock-out of nucleons from the colliding nuclei is the most probable reason for the decrease of the number of interactions

  7. Use of nonlinear dose-effect models to predict consequences

    International Nuclear Information System (INIS)

    Seiler, F.A.; Alvarez, J.L.

    1996-01-01

    The linear dose-effect relationship was introduced as a model for the induction of cancer from exposure to nuclear radiation. Subsequently, it has been used by analogy to assess the risk of chemical carcinogens also. Recently, however, the model for radiation carcinogenesis has come increasingly under attack because its calculations contradict the epidemiological data, such as cancer in atomic bomb survivors. Even so, its proponents vigorously defend it, often using arguments that are not so much scientific as a mix of scientific, societal, and often political arguments. At least in part, the resilience of the linear model is due to two convenient properties that are exclusive to linearity: First, the risk of an event is determined solely by the event dose; second, the total risk of a population group depends only on the total population dose. In reality, the linear model has been conclusively falsified; i.e., it has been shown to make wrong predictions, and once this fact is generally realized, the scientific method calls for a new paradigm model. As all alternative models are by necessity nonlinear, all the convenient properties of the linear model are invalid, and calculational procedures have to be used that are appropriate for nonlinear models

  8. Study of nonlinear effects in photonic crystals doped with nanoparticles

    International Nuclear Information System (INIS)

    Singh, Mahi R

    2008-01-01

    A theory of nonlinear phenomena has been developed for a photonic crystal in the presence of a pump and a coupling laser field. The crystal is doped with an ensemble of four-level nanoparticle impurities. It is considered that the impurity particles are not only interacting with the photonic crystal but also with each other via dipole-dipole interaction. An expression for the susceptibility has been obtained using the density matrix method. The nonlinear effects due to the coupling and the pump fields have been included in the formulation. The absorption spectrum has been calculated in the presence of the strong coupling and pump fields for an isotropic photonic crystal made from dielectric spheres. The photonic crystal has a gap to midgap ratio of about 21%. It is predicted that the absorption spectrum in the photonic crystal can have zero, one, two or three absorptionless states by tuning one of the transition energies within the bands. This is an interesting phenomenon which can be used to make photonic switching devices. We have also calculated the absorption spectrum in the presence of the dipole-dipole interaction. It is found that a symmetric absorption spectrum changes to an asymmetric one due to this interaction. It is also found that there is a large enhancement in the absorption and the dispersion simultaneously for certain values of the detuning and concentration

  9. Ocular-following responses to white noise stimuli in humans reveal a novel nonlinearity that results from temporal sampling.

    Science.gov (United States)

    Sheliga, Boris M; Quaia, Christian; FitzGibbon, Edmond J; Cumming, Bruce G

    2016-01-01

    White noise stimuli are frequently used to study the visual processing of broadband images in the laboratory. A common goal is to describe how responses are derived from Fourier components in the image. We investigated this issue by recording the ocular-following responses (OFRs) to white noise stimuli in human subjects. For a given speed we compared OFRs to unfiltered white noise with those to noise filtered with band-pass filters and notch filters. Removing components with low spatial frequency (SF) reduced OFR magnitudes, and the SF associated with the greatest reduction matched the SF that produced the maximal response when presented alone. This reduction declined rapidly with SF, compatible with a winner-take-all operation. Removing higher SF components increased OFR magnitudes. For higher speeds this effect became larger and propagated toward lower SFs. All of these effects were quantitatively well described by a model that combined two factors: (a) an excitatory drive that reflected the OFRs to individual Fourier components and (b) a suppression by higher SF channels where the temporal sampling of the display led to flicker. This nonlinear interaction has an important practical implication: Even with high refresh rates (150 Hz), the temporal sampling introduced by visual displays has a significant impact on visual processing. For instance, we show that this distorts speed tuning curves, shifting the peak to lower speeds. Careful attention to spectral content, in the light of this nonlinearity, is necessary to minimize the resulting artifact when using white noise patterns undergoing apparent motion.

  10. Estimation of Nonlinear Dynamic Panel Data Models with Individual Effects

    Directory of Open Access Journals (Sweden)

    Yi Hu

    2014-01-01

    Full Text Available This paper suggests a generalized method of moments (GMM based estimation for dynamic panel data models with individual specific fixed effects and threshold effects simultaneously. We extend Hansen’s (Hansen, 1999 original setup to models including endogenous regressors, specifically, lagged dependent variables. To address the problem of endogeneity of these nonlinear dynamic panel data models, we prove that the orthogonality conditions proposed by Arellano and Bond (1991 are valid. The threshold and slope parameters are estimated by GMM, and asymptotic distribution of the slope parameters is derived. Finite sample performance of the estimation is investigated through Monte Carlo simulations. It shows that the threshold and slope parameter can be estimated accurately and also the finite sample distribution of slope parameters is well approximated by the asymptotic distribution.

  11. Exact multiplicity results for quasilinear boundary-value problems with cubic-like nonlinearities

    Directory of Open Access Journals (Sweden)

    Idris Addou

    2000-01-01

    Full Text Available We consider the boundary-value problem $$displaylines{ -(varphi_p (u'' =lambda f(u mbox{ in }(0,1 cr u(0 = u(1 =0,, }$$ where $p>1$, $lambda >0$ and $varphi_p (x =| x|^{p-2}x$. The nonlinearity $f$ is cubic-like with three distinct roots 0=a less than b less than c. By means of a quadrature method, we provide the exact number of solutions for all $lambda >0$. This way we extend a recent result, for $p=2$, by Korman et al. cite{KormanLiOuyang} to the general case $p>1$. We shall prove that when 1less than $pleq 2$ the structure of the solution set is exactly the same as that studied in the case $p=2$ by Korman et al. cite{KormanLiOuyang}, and strictly different in the case $p>2$.

  12. Geometric nonlinear effects on the planar dynamics of a pivoted flexible beam encountering a point-surface impact

    International Nuclear Information System (INIS)

    Li Qing; Wang Tianshu; Ma Xingrui

    2009-01-01

    Flexible-body modeling with geometric nonlinearities remains a hot topic of research by applications in multibody system dynamics undergoing large overall motions. However, the geometric nonlinear effects on the impact dynamics of flexible multibody systems have attracted significantly less attention. In this paper, a point-surface impact problem between a rigid ball and a pivoted flexible beam is investigated. The Hertzian contact law is used to describe the impact process, and the dynamic equations are formulated in the floating frame of reference using the assumed mode method. The two important geometric nonlinear effects of the flexible beam are taken into account, i.e., the longitudinal foreshortening effect due to the transverse deformation, and the stress stiffness effect due to the axial force. The simulation results show that good consistency can be obtained with the nonlinear finite element program ABAQUS/Explicit if proper geometric nonlinearities are included in the floating frame formulation. Specifically, only the foreshortening effect should be considered in a pure transverse impact for efficiency, while the stress stiffness effect should be further considered in an oblique case with much more computational effort. It also implies that the geometric nonlinear effects should be considered properly in the impact dynamic analysis of more general flexible multibody systems

  13. Full non-linear treatment of the global thermospheric wind system. I - Mathematical method and analysis of forces. II - Results and comparison with observations

    Science.gov (United States)

    Blum, P. W.; Harris, I.

    1975-01-01

    The equations of horizontal motion of the neutral atmosphere between 120 and 500 km are integrated with the inclusion of all nonlinear terms of the convective derivative and the viscous forces due to vertical and horizontal velocity gradients. Empirical models of the distribution of neutral and charged particles are assumed to be known. The model of velocities developed is a steady state model. In Part I the mathematical method used in the integration of the Navier-Stokes equations is described and the various forces are analyzed. Results of the method given in Part I are presented with comparison with previous calculations and observations of upper atmospheric winds. Conclusions are that nonlinear effects are only significant in the equatorial region, especially at solstice conditions and that nonlinear effects do not produce any superrotation.

  14. Nonlinear Dynamics and Chaos of Microcantilever-Based TM-AFMs with Squeeze Film Damping Effects

    Directory of Open Access Journals (Sweden)

    Jie-Yu Chen

    2009-05-01

    Full Text Available In Atomic force microscope (AFM examination of a vibrating microcantilever, the nonlinear tip-sample interaction would greatly influence the dynamics of the cantilever. In this paper, the nonlinear dynamics and chaos of a tip-sample dynamic system being run in the tapping mode (TM were investigated by considering the effects of hydrodynamic loading and squeeze film damping. The microcantilever was modeled as a spring-mass-damping system and the interaction between the tip and the sample was described by the Lennard-Jones (LJ potential. The fundamental frequency and quality factor were calculated from the transient oscillations of the microcantilever vibrating in air. Numerical simulations were carried out to study the coupled nonlinear dynamic system using the bifurcation diagram, Poincaré maps, largest Lyapunov exponent, phase portraits and time histories. Results indicated the occurrence of periodic and chaotic motions and provided a comprehensive understanding of the hydrodynamic loading of microcantilevers. It was demonstrated that the coupled dynamic system will experience complex nonlinear oscillation as the system parameters change and the effect of squeeze film damping is not negligible on the micro-scale.

  15. Seasonality Effects on Nonlinear Properties of Hydrometeorological Records: A New Method of Data Analysis

    Science.gov (United States)

    Livina, V. N.; Ashkenazy, Y.; Bunde, A.; Havlin, S.

    2007-12-01

    Climatic time series in general, and hydrological time series in particular, exhibit pronounced annual periodicity. This periodicity and its corresponding harmonics affect the nonlinear properties of the relevant time series (i.e., the long-range volatility correlations and width of multifractal spectrum) and thus have to be filtered out before studying fractal and volatility properties. We compare several filtering techniques (one of them proposed here) and find that in order to eliminate the periodicity effect on the nonlinear properties of the time series (i.e., the volatility and multifractal properties) it is necessary to filter out the seasonal standard deviation in addition to the filtering of the seasonal mean. The obtained results indicate weak volatility correlations (weak nonlinearity) in the river data, and this can be seen using different filterings approaches. [1] Livina~V.~N., Y.~Ashkenazy, A.~Bunde, and S.~Havlin, Seasonality effects on nonlinear properties of hydrometeorological records, in Extremes, Trends, and Correlations in Hydrology and Climate (ed. by J.P.Kropp & H.-J.Schellnhuber), Springer, Berlin, submitted.

  16. New results on the mathematical problems in nonlinear physics; Nuevos resultados sobre problemas matematicos en fisica no-linear

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1980-07-01

    The main topics treated in this report are: I) Existence of generalized Lagrangians. II) Conserved densities for odd-order polynomial evolution equations and linear evolution systems. III ) Conservation laws for Klein-Gordon, Di rae and Maxwell equations. IV) Stability conditions for finite-energy solutions of a non-linear Klein-Gordon equation. V) Hamiltonian approach to non-linear evolution equations and Backlund transformations. VI) Anharmonic vibrations: Status of results and new possible approaches. (Author) 83 refs.

  17. Effect of P T symmetry on nonlinear waves for three-wave interaction models in the quadratic nonlinear media

    Science.gov (United States)

    Shen, Yujia; Wen, Zichao; Yan, Zhenya; Hang, Chao

    2018-04-01

    We study the three-wave interaction that couples an electromagnetic pump wave to two frequency down-converted daughter waves in a quadratic optical crystal and P T -symmetric potentials. P T symmetric potentials are shown to modulate stably nonlinear modes in two kinds of three-wave interaction models. The first one is a spatially extended three-wave interaction system with odd gain-and-loss distribution in the channel. Modulated by the P T -symmetric single-well or multi-well Scarf-II potentials, the system is numerically shown to possess stable soliton solutions. Via adiabatical change of system parameters, numerical simulations for the excitation and evolution of nonlinear modes are also performed. The second one is a combination of P T -symmetric models which are coupled via three-wave interactions. Families of nonlinear modes are found with some particular choices of parameters. Stable and unstable nonlinear modes are shown in distinct families by means of numerical simulations. These results will be useful to further investigate nonlinear modes in three-wave interaction models.

  18. Combined effects of traveling seismic waves and soil nonlinearity on nuclear power plant response

    International Nuclear Information System (INIS)

    Lee, T.H.; Charman, C.M.

    1981-01-01

    The effects of ground motion nonuniformity on the seismic input have been actively studied in recent years by considering the passage of traveling seismic waves. These studies gave rise to a new class of soil-structure interaction problems in which the seismic input is modified as a result of the spatial variations of ground motion. The phenomena were usually studied by using the elastic half-space simulation or discrete spring-models for modeling the soil medium. Finite element methods were also used recently on a limited scope. Results obtained from these investigations are often manifested by an attenuation of translational excitation along with an addition of rotational ground motion input. The decrease in structural response resulting from the input loss in the translational component was often insignificant since the response reduction tends to be offset by the effects from rotational input. The traveling wave effects have, so far, been investigated within the framework of linear theory with soil nonlinearity ignored. Conversely, the incorporation of soil nonlinearity in soil-structure interaction analyses has been done without including wave effect. Seismic analyses considering the hysteretic behavior of soil have been performed using highly idealized models for steady-state solution. More elaborate nonlinear seismic models deal with only the strain-dependent soil modulus rather than the transient unloading-reloading type of hysteretic characteristics of soil under a time-function input of earthquake trace. Apparently, the traveling wave effect and soil nonlinearity have been separately treated in the past. The purpose of this paper is to demonstrate that these two major effects can be combined in one model such that the influence of wave passage is reflected through the hysteretic behavior of soil particles, and thereby achieving significant reduction in seismic loads. (orig./RW)

  19. Effect of Nonlinear Hardening of Lead Rubber Bearing on Long Term Behavior of Base Isolated Containment Building

    International Nuclear Information System (INIS)

    Park, Junhee; Choun, Young-Sun; Kim, Min-Kyu

    2015-01-01

    The rubber material used in laminated rubber bearings is the hyper elastic material whose stress-strain relationship can be defined as nonlinearly elastic. From the previous research, it was presented that the rubber hardness and stiffness was increased by the aging of LRB. The mechanical properties of LRB changed by aging can directly affect a nonlinear hardening behavior. Therefore it is needed to consider the nonlinear hardening effect for exactly evaluating the seismic safety of base isolated structure during the life time. In this study, the seismic response analysis of base isolated containment building was performed by using the bilinear model and the hardening model to identify the effect of structural response on the nonlinear hardening behavior of isolator. Moreover the floor response spectrum of base isolated structure considering the aging was analyzed by according to the analysis model of LRB.. The hardening behavior of lead rubber bearing occurs at high strain. Therefore it is reasonable to assume that the hysteretic model of LRB is the nonlinear hardening model for exactly evaluating the seismic response of base isolated structure. The nonlinear analysis of base isolated containment was performed by using the nonlinear hardening variables which was resulted from the test results and finite element analysis. From the analysis results, it was represented that the FRS was higher about 40% with nonlinear hardening model than with the bilinear model. Therefore the seismic response of base isolated structure with bilinear model can be underestimated than the real response. It is desired that the nonlinear hardening model of LRB is applied for the seismic risk evaluation requiring the ultimate state of LRB

  20. Effects of network structure on the synchronizability of nonlinearly coupled Hindmarsh–Rose neurons

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chun-Hsien, E-mail: chli@nknucc.nknu.edu.tw [Department of Mathematics, National Kaohsiung Normal University, Yanchao District, Kaohsiung City 82444, Taiwan (China); Yang, Suh-Yuh, E-mail: syyang@math.ncu.edu.tw [Department of Mathematics, National Central University, Jhongli District, Taoyuan City 32001, Taiwan (China)

    2015-10-23

    This work is devoted to investigate the effects of network structure on the synchronizability of nonlinearly coupled dynamical network of Hindmarsh–Rose neurons with a sigmoidal coupling function. We mainly focus on the networks that exhibit the small-world character or scale-free property. By checking the first nonzero eigenvalue of the outer-coupling matrix, which is closely related to the synchronization threshold, the synchronizabilities of three specific network ensembles with prescribed network structures are compared. Interestingly, we find that networks with more connections will not necessarily result in better synchronizability. - Highlights: • We investigate the effects of network structure on the synchronizability of nonlinearly coupled Hindmarsh–Rose neurons. • We mainly consider the networks that exhibit the small-world character or scale-free property. • The synchronizability of three specific network ensembles with prescribed network structures are compared. • Networks with more connections will not necessarily result in better synchronizability.

  1. Effects of network structure on the synchronizability of nonlinearly coupled Hindmarsh–Rose neurons

    International Nuclear Information System (INIS)

    Li, Chun-Hsien; Yang, Suh-Yuh

    2015-01-01

    This work is devoted to investigate the effects of network structure on the synchronizability of nonlinearly coupled dynamical network of Hindmarsh–Rose neurons with a sigmoidal coupling function. We mainly focus on the networks that exhibit the small-world character or scale-free property. By checking the first nonzero eigenvalue of the outer-coupling matrix, which is closely related to the synchronization threshold, the synchronizabilities of three specific network ensembles with prescribed network structures are compared. Interestingly, we find that networks with more connections will not necessarily result in better synchronizability. - Highlights: • We investigate the effects of network structure on the synchronizability of nonlinearly coupled Hindmarsh–Rose neurons. • We mainly consider the networks that exhibit the small-world character or scale-free property. • The synchronizability of three specific network ensembles with prescribed network structures are compared. • Networks with more connections will not necessarily result in better synchronizability

  2. Non-linear mixed-effects pharmacokinetic/pharmacodynamic modelling in NLME using differential equations

    DEFF Research Database (Denmark)

    Tornøe, Christoffer Wenzel; Agersø, Henrik; Madsen, Henrik

    2004-01-01

    The standard software for non-linear mixed-effect analysis of pharmacokinetic/phar-macodynamic (PK/PD) data is NONMEM while the non-linear mixed-effects package NLME is an alternative as tong as the models are fairly simple. We present the nlmeODE package which combines the ordinary differential...... equation (ODE) solver package odesolve and the non-Linear mixed effects package NLME thereby enabling the analysis of complicated systems of ODEs by non-linear mixed-effects modelling. The pharmacokinetics of the anti-asthmatic drug theophylline is used to illustrate the applicability of the nlme...

  3. Nonlinear Local Deformations of Red Blood Cell Membranes: Effects of Toxins and Pharmaceuticals (Part 2

    Directory of Open Access Journals (Sweden)

    Alexander M. Chernysh

    2018-01-01

    Full Text Available Modifiers of membranes cause local defects on the cell surface. Measurement of the rigidity at the sites of local defects can provide further information about the structure of defects and mechanical properties of altered membranes.The purpose of the study: a step-by-step study of the process of a nonlinear deformation of red blood cells membranes under the effect of modifiers of different physico-chemical nature.Materials and methods. The membrane deformation of a viscoelastic composite erythrocyte construction inside a cell was studied by the atomic force spectroscopy. Nonlinear deformations formed under the effect of hemin, Zn2+ ions, and verapamil were studied.Results. The process of elastic deformation of the membrane with the indentation of a probe at the sites of local defects caused by modifiers was demonstrated. The probe was inserted during the same step of the piezo scanner z displacement; the probe indentation occured at the different discrete values of h, which are the functions of the membrane structure. At the sites of domains, under the effect of the hemin, tension areas and plasticity areas appeared. A mathematical model of probe indentation at the site of membrane defects is presented.Conclusion. The molecular mechanisms of various types of nonlinear deformations occurring under the effect of toxins are discussed. The results of the study may be of interest both for fundamental researchers of the blood cell properties and for practical reanimatology and rehabilitology. 

  4. A NONLINEAR MATHEMATICAL MODEL FOR ASTHMA: EFFECT OF ENVIRONMENTAL POLLUTION

    Directory of Open Access Journals (Sweden)

    NARESHA RAM

    2009-04-01

    Full Text Available In this paper, we explore a nonlinear mathematical model to study the spread of asthma due to inhaled pollutants from industry as well as tobacco smoke from smokers in a variable size population. The model is analyzed using stability theory of differential equations and computer simulation. It is shown that with an increase in the level of air pollutants concentration, the asthmatic (diseased population increases. It is also shown that along with pollutants present in the environment, smoking (active or passive also helps in the spread of asthma. Moreover, with the increase in the rate of interaction between susceptibles and smokers, the persistence of the spread of asthma is higher. A numerical study of the model is also performed to see the role of certain key parameters on the spread of asthma and to support the analytical results.

  5. Nonlinear effects of dark energy clustering beyond the acoustic scales

    International Nuclear Information System (INIS)

    Anselmi, Stefano; Nacir, Diana López; Sefusatti, Emiliano

    2014-01-01

    We extend the resummation method of Anselmi and Pietroni (2012) to compute the total density power spectrum in models of quintessence characterized by a vanishing speed of sound. For standard ΛCDM cosmologies, this resummation scheme allows predictions with an accuracy at the few percent level beyond the range of scales where acoustic oscillations are present, therefore comparable to other, common numerical tools. In addition, our theoretical approach indicates an approximate but valuable and simple relation between the power spectra for standard quintessence models and models where scalar field perturbations appear at all scales. This, in turn, provides an educated guess for the prediction of nonlinear growth in models with generic speed of sound, particularly valuable since no numerical results are yet available

  6. Nonlinear effects of dark energy clustering beyond the acoustic scales

    Energy Technology Data Exchange (ETDEWEB)

    Anselmi, Stefano [Department of Physics/CERCA/ISO, Case Western Reserve University, Cleveland, OH 44106-7079 (United States); Nacir, Diana López [The Abdus Salam International Center for Theoretical Physics, Strada costiera 11, I-34151 Trieste (Italy); Sefusatti, Emiliano, E-mail: stefano.anselmi@case.edu, E-mail: dlopez_n@ictp.it, E-mail: emiliano.sefusatti@brera.inaf.it [INAF - Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Saint Lucia) (Italy)

    2014-07-01

    We extend the resummation method of Anselmi and Pietroni (2012) to compute the total density power spectrum in models of quintessence characterized by a vanishing speed of sound. For standard ΛCDM cosmologies, this resummation scheme allows predictions with an accuracy at the few percent level beyond the range of scales where acoustic oscillations are present, therefore comparable to other, common numerical tools. In addition, our theoretical approach indicates an approximate but valuable and simple relation between the power spectra for standard quintessence models and models where scalar field perturbations appear at all scales. This, in turn, provides an educated guess for the prediction of nonlinear growth in models with generic speed of sound, particularly valuable since no numerical results are yet available.

  7. Nonlinear delta f Simulations of Collective Effects in Intense Charged Particle Beams

    CERN Document Server

    Hong Qi

    2003-01-01

    A nonlinear delta(f) particle simulation method based on the Vlasov-Maxwell equations has been recently developed to study collective processes in high-intensity beams, where space-charge and magnetic self-field effects play a critical role in determining the nonlinear beam dynamics. Implemented in the Beam Equilibrium, Stability and Transport (BEST) code [H. Qin, R.C. Davidson, and W.W. Lee, Physical Review -- Special Topics on Accelerator and Beams 3 (2000) 084401; 3 (2000) 109901.], the nonlinear delta(f) method provides a low-noise and self-consistent tool for simulating collective interactions and nonlinear dynamics of high-intensity beams in modern and next-generation accelerators and storage rings, such as the Spallation Neutron Source and heavy ion fusion drivers. A wide range of linear eigenmodes of high-intensity charged-particle beams can be systematically studied using the BEST code. Simulation results for the electron-proton two-stream instability in the Proton Storage Ring experiment [R. Macek, ...

  8. The Effects of Five-Order Nonlinear on the Dynamics of Dark Solitons in Optical Fiber

    Directory of Open Access Journals (Sweden)

    Feng-Tao He

    2013-01-01

    Full Text Available We study the influence of five-order nonlinear on the dynamic of dark soliton. Starting from the cubic-quintic nonlinear Schrodinger equation with the quadratic phase chirp term, by using a similarity transformation technique, we give the exact solution of dark soliton and calculate the precise expressions of dark soliton's width, amplitude, wave central position, and wave velocity which can describe the dynamic behavior of soliton's evolution. From two different kinds of quadratic phase chirps, we mainly analyze the effect on dark soliton’s dynamics which different fiver-order nonlinear term generates. The results show the following two points with quintic nonlinearities coefficient increasing: (1 if the coefficients of the quadratic phase chirp term relate to the propagation distance, the solitary wave displays a periodic change and the soliton’s width increases, while its amplitude and wave velocity reduce. (2 If the coefficients of the quadratic phase chirp term do not depend on propagation distance, the wave function only emerges in a fixed area. The soliton’s width increases, while its amplitude and the wave velocity reduce.

  9. Game Theory of Tumor–Stroma Interactions in Multiple Myeloma: Effect of Nonlinear Benefits

    Directory of Open Access Journals (Sweden)

    Javad Salimi Sartakhti

    2018-05-01

    Full Text Available Cancer cells and stromal cells often exchange growth factors with paracrine effects that promote cell growth: a form of cooperation that can be studied by evolutionary game theory. Previous models have assumed that interactions between cells are pairwise or that the benefit of a growth factor is a linear function of its concentration. Diffusible factors, however, affect multiple cells and generally have nonlinear effects, and these differences are known to have important consequences for evolutionary dynamics. Here, we study tumor–stroma paracrine signaling using a model with multiplayer collective interactions in which growth factors have nonlinear effects. We use multiple myeloma as an example, modelling interactions between malignant plasma cells, osteoblasts, and osteoclasts. Nonlinear benefits can lead to results not observed in linear models, including internal mixed stable equilibria and cyclical dynamics. Models with linear effects, therefore, do not lead to a meaningful characterization of the dynamics of tumor–stroma interactions. To understand the dynamics and the effect of therapies it is necessary to estimate the shape of the benefit functions experimentally and parametrize models based on these functions.

  10. Nonlinear effect of the structured light profilometry in the phase-shifting method and error correction

    International Nuclear Information System (INIS)

    Zhang Wan-Zhen; Chen Zhe-Bo; Xia Bin-Feng; Lin Bin; Cao Xiang-Qun

    2014-01-01

    Digital structured light (SL) profilometry is increasingly used in three-dimensional (3D) measurement technology. However, the nonlinearity of the off-the-shelf projectors and cameras seriously reduces the measurement accuracy. In this paper, first, we review the nonlinear effects of the projector–camera system in the phase-shifting structured light depth measurement method. We show that high order harmonic wave components lead to phase error in the phase-shifting method. Then a practical method based on frequency domain filtering is proposed for nonlinear error reduction. By using this method, the nonlinear calibration of the SL system is not required. Moreover, both the nonlinear effects of the projector and the camera can be effectively reduced. The simulations and experiments have verified our nonlinear correction method. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  11. Nonlinear Modeling and Simulation of Thermal Effects in Microcantilever Resonators Dynamic

    International Nuclear Information System (INIS)

    Tadayon, M A; Sayyaadi, H; Jazar, G Nakhaie

    2006-01-01

    Thermal dependency of material characteristics in micro electromechanical systems strongly affects their performance, design, and control. Hence, it is essential to understand and model that in MEMS devices to optimize their designs. A thermal phenomenon introduces two main effects: damping due to internal friction, and softening due to Young modulus temperature relation. Based on some reported theoretical and experimental results, we model the thermal phenomena and use two Lorentzian functions to describe the restoring and damping forces caused by thermal phenomena. In order to emphasize the thermal effects, a nonlinear model of the MEMS, by considering capacitor nonlinearity, have been used. The response of the system is developed by employing multiple time scales perturbation method on nondimensionalized form of equations. Frequency response, resonant frequency and peak amplitude are examined for variation of dynamic parameters involved

  12. Geometry effect on energy transfer rate in a coupled-quantum-well structure: nonlinear regime

    International Nuclear Information System (INIS)

    Salavati-fard, T; Vazifehshenas, T

    2014-01-01

    We study theoretically the effect of geometry on the energy transfer rate at nonlinear regime in a coupled-quantum-well system using the balance equation approach. To investigate comparatively the effect of both symmetric and asymmetric geometry, different structures are considered. The random phase approximation dynamic dielectric function is employed to include the contributions from both quasiparticle and plasmon excitations. Also, the short-range exchange interaction is taken into account through the Hubbard approximation. Our numerical results show that the energy transfer rate increases by increasing the well thicknesses in symmetric structures. Furthermore, by increasing spatial asymmetry, the energy transfer rate decreases for the electron temperature range of interest. From numerical calculations, it is obtained that the nonlinear energy transfer rate is proportional to the square of electron drift velocity in all structures and also, found that the influence of Hubbard local field correction on the energy transfer rate gets weaker by increasing the strength of applied electric field. (paper)

  13. Further results on global state feedback stabilization of nonlinear high-order feedforward systems.

    Science.gov (United States)

    Xie, Xue-Jun; Zhang, Xing-Hui

    2014-03-01

    In this paper, by introducing a combined method of sign function, homogeneous domination and adding a power integrator, and overcoming several troublesome obstacles in the design and analysis, the problem of state feedback control for a class of nonlinear high-order feedforward systems with the nonlinearity's order being relaxed to an interval rather than a fixed point is solved. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  14. Nonlinear hybrid simulation of internal kink with beam ion effects in DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Wei; Sheng, Zheng-Mao [Department of Physics, Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Fu, G. Y.; Tobias, Benjamin [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Zeeland, Michael Van [General Atomics, San Diego, California 92186-5608 (United States); Wang, Feng [School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024 (China)

    2015-04-15

    In DIII-D sawteething plasmas, long-lived (1,1) kink modes are often observed between sawtooth crashes. The saturated kink modes have two distinct frequencies. The mode with higher frequency transits to a fishbone-like mode with sufficient on-axis neutral beam power. In this work, hybrid simulations with the global kinetic-magnetohydrodynamic (MHD) hybrid code M3D-K have been carried out to investigate the linear stability and nonlinear dynamics of the n = 1 mode with effects of energetic beam ions for a typical DIII-D discharge where both saturated kink mode and fishbone were observed. Linear simulation results show that the n = 1 internal kink mode is unstable in MHD limit. However, with kinetic effects of beam ions, a fishbone-like mode is excited with mode frequency about a few kHz depending on beam pressure profile. The mode frequency is higher at higher beam power and/or narrower radial profile consistent with the experimental observation. Nonlinear simulations have been performed to investigate mode saturation as well as energetic particle transport. The nonlinear MHD simulations show that the unstable kink mode becomes a saturated kink mode after a sawtooth crash. With beam ion effects, the fishbone-like mode can also transit to a saturated kink mode with a small but finite mode frequency. These results are consistent with the experimental observation of saturated kink mode between sawtooth crashes.

  15. Narrow-linewidth Si/III-V lasers: A study of laser dynamics and nonlinear effects

    Science.gov (United States)

    Vilenchik, Yaakov Yasha

    Narrow-linewidth lasers play an important role in a wide variety of applications, from sensing and spectroscopy to optical communication and on-chip clocks. Current narrow-linewidth systems are usually implemented in doped fibers and are big, expensive, and power-hungry. Semiconductor lasers compete favorably in size, cost, and power consumption, but their linewidth is historically limited to the sub-MHz regime. However, it has been recently demonstrated that a new design paradigm, in which the optical energy is stored away from the active region in a composite high-Q resonator, has the potential to dramatically improve the coherence of the laser. This work explores this design paradigm, as applied on the hybrid Si/III-V platform. It demonstrates a record sub-KHz white-noise-floor linewidth. It further shows, both theoretically and experimentally, that this strategy practically eliminates Henry's linewidth enhancement by positioning a damped relaxation resonance at frequencies as low as 70 MHz, yielding truly quantum limited devices at frequencies of interest. In addition to this empirical contribution, this work explores the limits of performance of this platform. Here, the effect of two-photon-absorption and free-carrier-absorption are analyzed, using modified rate equations and Langevin force approach. The analysis predicts that as the intra-cavity field intensity builds up in the high-Q resonator, non-linear effects cause a new domain of performance-limiting factors. Steady-state behavior, laser dynamics, and frequency noise performance are examined in the context of this unique platform, pointing at the importance of nonlinear effects. This work offers a theoretical model predicting laser performance in light of nonlinear effects, obtaining a good agreement with experimental results from fabricated high-Q Si/III-V lasers. In addition to demonstrating unprecedented semiconductor laser performance, this work establishes a first attempt to predict and demonstrate

  16. The Effect of Adaptive Nonlinear Frequency Compression on Phoneme Perception.

    Science.gov (United States)

    Glista, Danielle; Hawkins, Marianne; Bohnert, Andrea; Rehmann, Julia; Wolfe, Jace; Scollie, Susan

    2017-12-12

    This study implemented a fitting method, developed for use with frequency lowering hearing aids, across multiple testing sites, participants, and hearing aid conditions to evaluate speech perception with a novel type of frequency lowering. A total of 8 participants, including children and young adults, participated in real-world hearing aid trials. A blinded crossover design, including posttrial withdrawal testing, was used to assess aided phoneme perception. The hearing aid conditions included adaptive nonlinear frequency compression (NFC), static NFC, and conventional processing. Enabling either adaptive NFC or static NFC improved group-level detection and recognition results for some high-frequency phonemes, when compared with conventional processing. Mean results for the distinction component of the Phoneme Perception Test (Schmitt, Winkler, Boretzki, & Holube, 2016) were similar to those obtained with conventional processing. Findings suggest that both types of NFC tested in this study provided a similar amount of speech perception benefit, when compared with group-level performance with conventional hearing aid technology. Individual-level results are presented with discussion around patterns of results that differ from the group average.

  17. Nonlinear acoustic properties of ex vivo bovine liver and the effects of temperature and denaturation

    International Nuclear Information System (INIS)

    Jackson, E J; Coussios, C-C; Cleveland, R O

    2014-01-01

    Thermal ablation by high intensity focused ultrasound (HIFU) has a great potential for the non-invasive treatment of solid tumours. Due to the high pressure amplitudes involved, nonlinear acoustic effects must be understood and the relevant medium property is the parameter of nonlinearity B/A. Here, B/A was measured in ex vivo bovine liver, over a heating/cooling cycle replicating temperatures reached during HIFU ablation, adapting a finite amplitude insertion technique, which also allowed for measurement of sound-speed and attenuation. The method measures the nonlinear progression of a plane wave through liver and B/A was chosen so that numerical simulations matched the measured waveforms. To create plane-wave conditions, sinusoidal bursts were transmitted by a 100 mm diameter 1.125 MHz unfocused transducer and measured using a 15 mm diameter 2.25 MHz broadband transducer in the near field. Attenuation and sound-speed were calculated using a reflected pulse from the smaller transducer using the larger transducer as the reflecting interface. Results showed that attenuation initially decreased with heating then increased after denaturation, the sound-speed initially increased with temperature and then decreased, and B/A showed an increase with temperature but no significant post-heating change. The B/A data disagree with other reports that show a significant change and we suggest that any nonlinear enhancement in the received ultrasound signal post-treatment is likely due to acoustic cavitation rather than changes in tissue nonlinearity. (paper)

  18. Current and Future Constraints on Higgs Couplings in the Nonlinear Effective Theory

    Energy Technology Data Exchange (ETDEWEB)

    de Blas, Jorge [INFN, Padua; Eberhardt, Otto [Valencia U., IFIC; Krause, Claudius [Fermilab

    2018-03-02

    We perform a Bayesian statistical analysis of the constraints on the nonlinear Effective Theory given by the Higgs electroweak chiral Lagrangian. We obtain bounds on the effective coefficients entering in Higgs observables at the leading order, using all available Higgs-boson signal strengths from the LHC runs 1 and 2. Using a prior dependence study of the solutions, we discuss the results within the context of natural-sized Wilson coefficients. We further study the expected sensitivities to the different Wilson coefficients at various possible future colliders. Finally, we interpret our results in terms of some minimal composite Higgs models.

  19. Using strong nonlinearity and high-frequency vibrations to control effective mechanical stiffness

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel

    2008-01-01

    the method of direct separation of motions with results of a modified multiple scales ap-proach, valid also for strong nonlinearity, the stiffening ef-fect is predicted for a generic 1-dof system, and results are tested against numerical simulation and ((it is planned)) laboratory experiments.......High-frequency excitation (HFE) can be used to change the effective stiffness of an elastic structure, and related quanti-ties such as resonance frequencies, wave speed, buckling loads, and equilibrium states. There are basically two ways to do this: By using parametrical HFE (with or without non...

  20. Effects of intermode nonlinearity and intramode nonlinearity on modulation instability in randomly birefringent two-mode optical fibers

    Science.gov (United States)

    Li, Jin Hua; Xu, Hui; Sun, Ting Ting; Pei, Shi Xin; Ren, Hai Dong

    2018-05-01

    We analyze in detail the effects of the intermode nonlinearity (IEMN) and intramode nonlinearity (IRMN) on modulation instability (MI) in randomly birefringent two-mode optical fibers (RB-TMFs). In the anomalous dispersion regime, the MI gain enhances significantly as the IEMN and IRMN coefficients increases. In the normal dispersion regime, MI can be generated without the differential mode group delay (DMGD) effect, as long as the IEMN coefficient between two distinct modes is above a critical value, or the IRMN coefficient inside a mode is below a critical value. This critical IEMN (IRMN) coefficient depends strongly on the given IRMN (IEMN) coefficient and DMGD for a given nonlinear RB-TMF structure, and is independent on the input total power, the power ratio distribution and the group velocity dispersion (GVD) ratio between the two modes. On the other hand, in contrast to the MI band arising from the pure effect of DMGD in the normal dispersion regime, where MI vanishes after a critical total power, the generated MI band under the combined effects of IEMN and IRMN without DMGD exists for any total power and enhances with the total power. The MI analysis is verified numerically by launching perturbed continuous waves (CWs) with wave propagation method.

  1. Explanation of the Inverse Doppler Effect Observed in Nonlinear Transmission Lines

    International Nuclear Information System (INIS)

    Kozyrev, Alexander B.; Weide, Daniel W. van der

    2005-01-01

    The theory of the inverse Doppler effect recently observed in magnetic nonlinear transmission lines is developed. We explain the crucial role of the backward spatial harmonic in the occurrence of an inverse Doppler effect and draw analogies of the magnetic nonlinear transmission line to the backward wave oscillator

  2. A Compact Synchronous Cellular Model of Nonlinear Calcium Dynamics: Simulation and FPGA Synthesis Results.

    Science.gov (United States)

    Soleimani, Hamid; Drakakis, Emmanuel M

    2017-06-01

    Recent studies have demonstrated that calcium is a widespread intracellular ion that controls a wide range of temporal dynamics in the mammalian body. The simulation and validation of such studies using experimental data would benefit from a fast large scale simulation and modelling tool. This paper presents a compact and fully reconfigurable cellular calcium model capable of mimicking Hopf bifurcation phenomenon and various nonlinear responses of the biological calcium dynamics. The proposed cellular model is synthesized on a digital platform for a single unit and a network model. Hardware synthesis, physical implementation on FPGA, and theoretical analysis confirm that the proposed cellular model can mimic the biological calcium behaviors with considerably low hardware overhead. The approach has the potential to speed up large-scale simulations of slow intracellular dynamics by sharing more cellular units in real-time. To this end, various networks constructed by pipelining 10 k to 40 k cellular calcium units are compared with an equivalent simulation run on a standard PC workstation. Results show that the cellular hardware model is, on average, 83 times faster than the CPU version.

  3. Effects of error feedback on a nonlinear bistable system with stochastic resonance

    International Nuclear Information System (INIS)

    Li Jian-Long; Zhou Hui

    2012-01-01

    In this paper, we discuss the effects of error feedback on the output of a nonlinear bistable system with stochastic resonance. The bit error rate is employed to quantify the performance of the system. The theoretical analysis and the numerical simulation are presented. By investigating the performances of the nonlinear systems with different strengths of error feedback, we argue that the presented system may provide guidance for practical nonlinear signal processing

  4. Study of dispersive and nonlinear effects of coastal wave dynamics with a fully nonlinear potential flow model

    Science.gov (United States)

    Benoit, Michel; Yates, Marissa L.; Raoult, Cécile

    2017-04-01

    Efficient and accurate numerical models simulating wave propagation are required for a variety of engineering projects including the evaluation of coastal risks, the design of protective coastal structures, and the estimation of the potential for marine renewable energy devices. Nonlinear and dispersive effects are particularly significant in the coastal zone where waves interact with the bottom, the shoreline, and coastal structures. The main challenge in developing a numerical models is finding a compromise between computational efficiency and the required accuracy of the simulated wave field. Here, a potential approach is selected and the (fully nonlinear) water wave problem is formulated using the Euler-Zakharov equations (Zakharov, 1968) describing the temporal evolution of the free surface elevation and velocity potential. The proposed model (Yates and Benoit, 2015) uses a spectral approach in the vertical (i.e. the vertical variation of the potential is approximated by a linear combination of the first NT+1 Chebyshev polynomials, following the work of Tian and Sato (2008)). The Zakharov equations are integrated in time using a fourth-order Runge-Kutta scheme with a constant time step. At each sub-timestep, the Laplace Boundary Value Problem (BVP) is solved to estimate the free surface vertical velocity using the spectral approach, with typical values of NT between 5 to 8 for practical applications. The 1DH version of the code is validated with comparisons to the experimental data set of Becq-Girard et al. (1999), which studied the propagation of irregular waves over a beach profile with a submerged bar. The nonlinear and dispersive capacities of the model are verified with the correct representation of wave-wave interactions, in particular the transfer of energy between different harmonic components during wave propagation (analysis of the transformation of the variance spectrum along the channel). Evolution of wave skewness, asymmetry and kurtosis along the

  5. An effective description of dark matter and dark energy in the mildly non-linear regime

    Energy Technology Data Exchange (ETDEWEB)

    Lewandowski, Matthew; Senatore, Leonardo [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94306 (United States); Maleknejad, Azadeh, E-mail: matthew.lewandowski@cea.fr, E-mail: azade@ipm.ir, E-mail: senatore@stanford.edu [School of Physics, Institute for Research in Fundamental Sciences (IPM), P. Code. 19538-33511, Tehran (Iran, Islamic Republic of)

    2017-05-01

    In the next few years, we are going to probe the low-redshift universe with unprecedented accuracy. Among the various fruits that this will bear, it will greatly improve our knowledge of the dynamics of dark energy, though for this there is a strong theoretical preference for a cosmological constant. We assume that dark energy is described by the so-called Effective Field Theory of Dark Energy, which assumes that dark energy is the Goldstone boson of time translations. Such a formalism makes it easy to ensure that our signatures are consistent with well-established principles of physics. Since most of the information resides at high wavenumbers, it is important to be able to make predictions at the highest wavenumber that is possible. The Effective Field Theory of Large-Scale Structure (EFTofLSS) is a theoretical framework that has allowed us to make accurate predictions in the mildly non-linear regime. In this paper, we derive the non-linear equations that extend the EFTofLSS to include the effect of dark energy both on the matter fields and on the biased tracers. For the specific case of clustering quintessence, we then perturbatively solve to cubic order the resulting non-linear equations and construct the one-loop power spectrum of the total density contrast.

  6. Effect of correlation on covariate selection in linear and nonlinear mixed effect models.

    Science.gov (United States)

    Bonate, Peter L

    2017-01-01

    The effect of correlation among covariates on covariate selection was examined with linear and nonlinear mixed effect models. Demographic covariates were extracted from the National Health and Nutrition Examination Survey III database. Concentration-time profiles were Monte Carlo simulated where only one covariate affected apparent oral clearance (CL/F). A series of univariate covariate population pharmacokinetic models was fit to the data and compared with the reduced model without covariate. The "best" covariate was identified using either the likelihood ratio test statistic or AIC. Weight and body surface area (calculated using Gehan and George equation, 1970) were highly correlated (r = 0.98). Body surface area was often selected as a better covariate than weight, sometimes as high as 1 in 5 times, when weight was the covariate used in the data generating mechanism. In a second simulation, parent drug concentration and three metabolites were simulated from a thorough QT study and used as covariates in a series of univariate linear mixed effects models of ddQTc interval prolongation. The covariate with the largest significant LRT statistic was deemed the "best" predictor. When the metabolite was formation-rate limited and only parent concentrations affected ddQTc intervals the metabolite was chosen as a better predictor as often as 1 in 5 times depending on the slope of the relationship between parent concentrations and ddQTc intervals. A correlated covariate can be chosen as being a better predictor than another covariate in a linear or nonlinear population analysis by sheer correlation These results explain why for the same drug different covariates may be identified in different analyses. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  7. New hybrid non-linear transformations of divergent perturbation series for quadratic Zeeman effects

    International Nuclear Information System (INIS)

    Belkic, D.

    1989-01-01

    The problem of hydrogen atoms in an external uniform magnetic field (quadratic Zeeman effect) is studied by means of perturbation theory. The power series for the ground-state energy in terms of magnetic-field strength B is divergent. Nevertheless, it is possible to induce convergence of this divergent series by applying various non-linear transformations. These transformations of originally divergent perturbation series yield new sequences, which then converge. The induced convergence is, however, quite slow. A new hybrid Shanks-Levin non-linear transform is devised here for accelerating these slowly converging series and sequences. Significant improvement in the convergence rate is obtained. Agreement with the exact results is excellent. (author)

  8. The effect of cochlear nonlinearities on binaural masking level differences

    DEFF Research Database (Denmark)

    Le Goff, Nicolas; Kohlrausch, Armin

    Background The binaural masking level difference (BMLD) has been shown to be constant (10−15dB) for masker spectrum levels from 70dB/Hz down to 30−40dB/Hz and to gradually decrease with lower levels (McFadden, 1968; Hall and Harvey, 1984). The decrease at low levels was larger in an asymmetric...... on the BMLD was investigated using an equalization−cancelation (EC) based binaural model framework. Methods The BMLD was measured for 500−Hz target tones presented in 3−kHz−wide maskers. BMLDs were obtained as a function of masker level in one symmetric and two asymmetric masker conditions: (i) No...... of 20dB/Hz in the non−attenuated ear. An EC based binaural model with a frontend including nonlinear peripheral processing (Jepsen et al., 2011) was used to predict these results. Results The BMLD obtained in the No′Sπ′50 condition was smaller than that obtained in the NoSπ condition at all masker...

  9. Nonlinear drift tearing mode

    International Nuclear Information System (INIS)

    Zelenyj, L.M.; Kuznetsova, M.M.

    1989-01-01

    Nonlinear study of magnetic perturbation development under single-mode conditions in collision-free plasma in configurations with the magnetic field shear is investigated. Results are obtained with regard of transverse component of electrical field and its effect on ion dynamics within wide range of ion Larmor radius value and values of magnetic field shear. Increments of nonlinear drift tearing mode are obtained and it is shown that excitation drastic conditions of even linearly stable modes are possible. Mechanism of instability nonlinear stabilization is considered and the value of magnetic island at the saturation threshold is estimeted. Energy of nonlinear drift tearing mode is discussed

  10. Effect of Nonlinearity by the Amplitude Variation in coherent transmission in Laser Heterodyne Interferometric

    International Nuclear Information System (INIS)

    Chen, H F; Ding, X M; Zhong, Z; Xie, Z L; Yue, H

    2006-01-01

    To reduce the nonlinearity of nanometer measurement in laser heterodyne interferometric, the influence mechanics of the amplitude variation in coherent transmission upon nonlinearity must be confirmed. Based on the mechanics of nonlinearity, the models about how first-harmonic and second-harmonic nonlinearity caused by the amplitude variation in coherent transmission are proposed. The emulation result shows that different amplitude between measurement arm and reference arm increases the first-harmonic nonlinearity when laser beams nonorthogonality errors exist, but it doesn't change the relationship between nonlinearity and half wavelength. When the rotation angle error β of polarizing beam splitter (PBS) exists, amplitude variation only affects the first-harmonic nonlinearity. With a constant rotation angle of PBS β = 4 0 , when the amplitude factor of measurement arm reduces from 1 to 0.6, the nonlinearity increases from 0.25 nm to 3.81 nm, and the nonlinearity is simple superposition of first-harmonic and second-harmonic. Theoretic analysis and emulation show that the reduction of amplitude variation in coherent transmission can reduce influence on nonlinearity

  11. Some New Results in Astrophysical Problems of Nonlinear Theory of Radiative Transfer

    Science.gov (United States)

    Pikichyan, H. V.

    2017-07-01

    In the interpretation of the observed astrophysical spectra, a decisive role is related to nonlinear problems of radiative transfer, because the processes of multiple interactions of matter of cosmic medium with the exciting intense radiation ubiquitously occur in astrophysical objects, and in their vicinities. Whereas, the intensity of the exciting radiation changes the physical properties of the original medium, and itself was modified, simultaneously, in a self-consistent manner under its influence. In the present report, we show that the consistent application of the principle of invariance in the nonlinear problem of bilateral external illumination of a scattering/absorbing one-dimensional anisotropic medium of finite geometrical thickness allows for simplifications that were previously considered as a prerogative only of linear problems. The nonlinear problem is analyzed through the three methods of the principle of invariance: (i) an adding of layers, (ii) its limiting form, described by differential equations of invariant imbedding, and (iii) a transition to the, so-called, functional equations of the "Ambartsumyan's complete invariance". Thereby, as an alternative to the Boltzmann equation, a new type of equations, so-called "kinetic equations of equivalence", are obtained. By the introduction of new functions - the so-called "linear images" of solution of nonlinear problem of radiative transfer, the linear structure of the solution of the nonlinear problem under study is further revealed. Linear images allow to convert naturally the statistical characteristics of random walk of a "single quantum" or their "beam of unit intensity", as well as widely known "probabilistic interpretation of phenomena of transfer", to the field of nonlinear problems. The structure of the equations obtained for determination of linear images is typical of linear problems.

  12. Nonlinear response time-dependent density functional theory combined with the effective fragment potential method

    Energy Technology Data Exchange (ETDEWEB)

    Zahariev, Federico; Gordon, Mark S., E-mail: mark@si.msg.chem.iastate.edu [Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States)

    2014-05-14

    This work presents an extension of the linear response TDDFT/EFP method to the nonlinear-response regime together with the implementation of nonlinear-response TDDFT/EFP in the quantum-chemistry computer package GAMESS. Included in the new method is the ability to calculate the two-photon absorption cross section and to incorporate solvent effects via the EFP method. The nonlinear-response TDDFT/EFP method is able to make correct qualitative predictions for both gas phase values and aqueous solvent shifts of several important nonlinear properties.

  13. Chaos and the quantum: how nonlinear effects can explain certain quantum paradoxes

    Energy Technology Data Exchange (ETDEWEB)

    McHarris, Wm C, E-mail: mcharris@chemistry.msu.edu [Departments of Chemistry and Physics/Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

    2011-07-08

    In recent years we have suggested that many of the so-called paradoxes resulting from the Copenhagen interpretation of quantum mechanics could well have more logical parallels based in nonlinear dynamics and chaos theory. Perhaps quantum mechanics might not be strictly linear as has been commonly postulated, and indeed, during the past year experimentalists have discovered signatures of chaos in a definitely quantum system. As an illustration of what can go wrong when quantum effects are forced into a linear interpretation, I examine Bell-type inequalities. In conventional derivations of such inequalities, classical systems are found to impose upper limits on the statistical correlations between, say, the properties of a pair of separated but entangled particles, whereas quantum systems allow greater correlations. Numerous experiments have upheld the quantum predictions (greater statistical correlations than allowed classically), which has led to inferences such as the instantaneous transmission of information between effectively infinitely separated particles - Einstein's 'spooky action-at-a-distance', incompatible with relativity. I argue that there is nothing wrong with the quantum mechanical side of such derivations (the usual point of attack by those attempting to debunk Bell-type arguments), but implicit in the derivations on the classical side is the assumption of independent, uncorrelated particles. As a result, one is comparing uncorrelated probabilities versus conditional probabilities rather than comparing classical versus quantum mechanics, making moot the experimental inferences. Further, nonlinear classical systems are known to exhibit correlations that can easily be as great as and overlap with quantum correlations - so-called nonextensive thermodynamics with its nonadditive entropy has verified this with numerous examples. Perhaps quantum mechanics does contain fundamental nonlinear elements. Nonlinear dynamics and chaos theory could

  14. Chaos and the quantum: how nonlinear effects can explain certain quantum paradoxes

    International Nuclear Information System (INIS)

    McHarris, Wm C

    2011-01-01

    In recent years we have suggested that many of the so-called paradoxes resulting from the Copenhagen interpretation of quantum mechanics could well have more logical parallels based in nonlinear dynamics and chaos theory. Perhaps quantum mechanics might not be strictly linear as has been commonly postulated, and indeed, during the past year experimentalists have discovered signatures of chaos in a definitely quantum system. As an illustration of what can go wrong when quantum effects are forced into a linear interpretation, I examine Bell-type inequalities. In conventional derivations of such inequalities, classical systems are found to impose upper limits on the statistical correlations between, say, the properties of a pair of separated but entangled particles, whereas quantum systems allow greater correlations. Numerous experiments have upheld the quantum predictions (greater statistical correlations than allowed classically), which has led to inferences such as the instantaneous transmission of information between effectively infinitely separated particles - Einstein's 'spooky action-at-a-distance', incompatible with relativity. I argue that there is nothing wrong with the quantum mechanical side of such derivations (the usual point of attack by those attempting to debunk Bell-type arguments), but implicit in the derivations on the classical side is the assumption of independent, uncorrelated particles. As a result, one is comparing uncorrelated probabilities versus conditional probabilities rather than comparing classical versus quantum mechanics, making moot the experimental inferences. Further, nonlinear classical systems are known to exhibit correlations that can easily be as great as and overlap with quantum correlations - so-called nonextensive thermodynamics with its nonadditive entropy has verified this with numerous examples. Perhaps quantum mechanics does contain fundamental nonlinear elements. Nonlinear dynamics and chaos theory could well provide a

  15. The effect of nonlinear ionospheric conductivity enhancement on magnetospheric substorms

    Directory of Open Access Journals (Sweden)

    E. Spencer

    2013-06-01

    Full Text Available We introduce the effect of enhanced ionospheric conductivity into a low-order, physics-based nonlinear model of the nightside magnetosphere called WINDMI. The model uses solar wind and interplanetary magnetic field (IMF parameters from the ACE satellite located at the L1 point to predict substorm growth, onset, expansion and recovery measured by the AL index roughly 50–60 min in advance. The dynamics introduced by the conductivity enhancement into the model behavior is described, and illustrated through using synthetically constructed solar wind parameters as input. We use the new model to analyze two well-documented isolated substorms: one that occurred on 31 July 1997 from Aksnes et al. (2002, and another on 13 April 2000 from Huang et al. (2004. These two substorms have a common feature in that the solar wind driver sharply decreases in the early part of the recovery phase, and that neither of them are triggered by northward turning of the IMF Bz. By controlling the model parameters such that the onset time of the substorm is closely adhered to, the westward auroral electrojet peaks during substorm expansion are qualitatively reproduced. Furthermore, the electrojet recovers more slowly with enhanced conductivity playing a role, which explains the data more accurately.

  16. Interference effects in the nonlinear charge density wave dynamics

    International Nuclear Information System (INIS)

    Jelcic, D.; Batistic, I.; Bjelis, A.

    1987-12-01

    The main features of the nonlinear charge density wave transport in the external dc-ac field are shown to be the natural consequences of resonant phase slip diffusion. This process is treated numerically within the time dependent Landau-Ginzburg model, developed by Gor'kov. The resonances in the ac field are manifested as Shapiro steps in I-V characteristics, present at all rational ratios of internal frequency of current oscillations and external ac frequency. The origin of Shapiro steps, as well as their forms and heights, are cosidered in detail. In particular, it is shown that close to resonances the phase slip voltage acquires a highly nonsinusoidal modulation which leads to the appearance of low frequency and satellite peaks in the Fourier spectrum. Taking into account the interference of adjacent phase slips and the segment or domain structure of physical samples, we interpret the finite width of steps, side wings, synchronization, incomplete and complete mode locking and some other effects observed in numerous experiments on NbSe 3 and other CDW materials. (author). 36 refs, 12 figs

  17. Piecewise linear emulator of the nonlinear Schroedinger equation and the resulting analytic solutions for Bose-Einstein condensates

    International Nuclear Information System (INIS)

    Theodorakis, Stavros

    2003-01-01

    We emulate the cubic term Ψ 3 in the nonlinear Schroedinger equation by a piecewise linear term, thus reducing the problem to a set of uncoupled linear inhomogeneous differential equations. The resulting analytic expressions constitute an excellent approximation to the exact solutions, as is explicitly shown in the case of the kink, the vortex, and a δ function trap. Such a piecewise linear emulation can be used for any differential equation where the only nonlinearity is a Ψ 3 one. In particular, it can be used for the nonlinear Schroedinger equation in the presence of harmonic traps, giving analytic Bose-Einstein condensate solutions that reproduce very accurately the numerically calculated ones in one, two, and three dimensions

  18. A nonlinear effective thermal conductivity model for carbon nanotube and nanofiber suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Koo, J; Kang, Y [Department of Mechanical Engineering Kyung Hee University, 1, Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Kleinstreuer, C [Department of Mechanical and Aerospace Engineering, North Carolina State University, Campus Box 7910, 3211 Broughton Hall, Raleigh, NC 27695-7910 (United States)], E-mail: jmkoo@khu.ac.kr

    2008-09-17

    It has been experimentally demonstrated that suspensions of carbon nanotubes (CNTs) and nanofibers (CNFs) significantly increase the thermal conductivity of nanofluids; however, a physically sound theory of the underlying phenomenon is still missing. In this study, the nonlinear nature of the effective thermal conductivity enhancement with the particle concentration of CNT and CNF nanofluids is explained physically using the excluded volume concept. Specifically, the number of contacting CNTs and CNFs could be calculated by using the excluded volume concept, where the distance for heat to travel in a cylinder between the contacting cylinders in the thermal network of percolating CNTs and CNFs increased with the excluded volume. In contrast to the effective thermal conductivity model of Sastry et al (2008 Nanotechnology 19 055704) the present revised model could reproduce the nonlinear increase of the thermal conductivity with particle concentration, as well as the dependence on the diameter and aspect ratio of the CNTs and CNFs. It was found that the alignment of CNTs and CNFs due to the long range repulsion force decreases the excluded volume, leading to both the convex and concave nonlinear as well as linear increase of the thermal conductivity with particle concentration. The difference between various carrier fluids of the suspensions could be explained as the result of the change in the excluded volume in different base fluids.

  19. The Non-Linear Effect of Corporate Taxes on Economic Growth

    Directory of Open Access Journals (Sweden)

    Huňady Ján

    2015-03-01

    Full Text Available The paper deals with the problem of taxation and its potential impact on economic growth and presents some new empirical insights into this topic. The main aim of the paper is to verify an assumed nonlinear impact of corporate tax rates on economic growth. Based on the theory of public finance and taxation, we hypothesize that at relatively low tax rates it is possible that the impact of taxation on economic growth become slightly positive. On the other hand when the tax rates are higher a negative impact of taxation on economic growth could be expected. Despite the fact that the most of the existing studies find a negative linear relationship between these variables, we can also find strong support for a non-linear relationship from several theoretical models as well as some empirical studies. Based on panel data fixed-effects econometric models, we, as well, find empirical evidence for a non-linear relationship between nominal and effective corporate tax rates and economic growth. Our data consists of annual observations for the period 1999 to 2011 for EU Member States. Based on the results, we also estimated the optimal level of the corporate tax rate in terms of maximizing economic growth in the average of the EU countries.

  20. Linear and nonlinear optical properties of multilayered spherical quantum dots: Effects of geometrical size, hydrogenic impurity, hydrostatic pressure and temperature

    International Nuclear Information System (INIS)

    Karimi, M.J.; Rezaei, G.; Nazari, M.

    2014-01-01

    Based on the effective mass and parabolic one band approximations, simultaneous effects of the geometrical size, hydrogenic impurity, hydrostatic pressure, and temperature on the intersubband optical absorption coefficients and refractive index changes in multilayered spherical quantum dots are studied. Energy eigenvalues and eigenvectors are calculated using the fourth-order Runge–Kutta method and optical properties are obtained using the compact density matrix approach. The results indicate that the hydrogenic impurity, hydrostatic pressure, temperature and geometrical parameters such as the well and barrier widths have a great influence on the linear, the third-order nonlinear and the total optical absorption coefficients and refractive index changes. -- Highlights: • Hydrogenic impurity effects on the optical properties of a MSQD are investigated. • Hydrostatic pressure and temperature effects are also studied. • Hydrogenic impurity has a great influence on the linear and nonlinear ACs and RICs. • Hydrostatic pressure and temperature change the linear and nonlinear ACs and RICs

  1. Quantum dynamical effects as a singular perturbation for observables in open quasi-classical nonlinear mesoscopic systems

    International Nuclear Information System (INIS)

    Berman, G.P.; Borgonovi, F.; Dalvit, D.A.R.

    2009-01-01

    We review our results on a mathematical dynamical theory for observables for open many-body quantum nonlinear bosonic systems for a very general class of Hamiltonians. We show that non-quadratic (nonlinear) terms in a Hamiltonian provide a singular 'quantum' perturbation for observables in some 'mesoscopic' region of parameters. In particular, quantum effects result in secular terms in the dynamical evolution, that grow in time. We argue that even for open quantum nonlinear systems in the deep quasi-classical region, these quantum effects can survive after decoherence and relaxation processes take place. We demonstrate that these quantum effects in open quantum systems can be observed, for example, in the frequency Fourier spectrum of the dynamical observables, or in the corresponding spectral density of noise. Estimates are presented for Bose-Einstein condensates, low temperature mechanical resonators, and nonlinear optical systems prepared in large amplitude coherent states. In particular, we show that for Bose-Einstein condensate systems the characteristic time of deviation of quantum dynamics for observables from the corresponding classical dynamics coincides with the characteristic time-scale of the well-known quantum nonlinear effect of phase diffusion.

  2. Fitness Effects of Network Non-Linearity Induced by Gene Expression Noise

    Science.gov (United States)

    Ray, Christian; Cooper, Tim; Balazsi, Gabor

    2012-02-01

    In the non-equilibrium dynamics of growing microbial cells, metabolic enzymes can create non-linearities in metabolite concentration because of non-linear degradation (utilization): an enzyme can saturate in the process of metabolite utilization. Increasing metabolite production past the saturation point then results in an ultrasensitive metabolite response. If the production rate of a metabolite depends on a second enzyme or other protein-mediated process, uncorrelated gene expression noise can thus cause transient metabolite concentration bursts. Such bursts are physiologically unnecessary and may represent a source of selection against the ultrasensitive switch, especially if the fluctuating metabolic intermediate is toxic. Selection may therefore favor correlated gene expression fluctuations for enzymes in the same pathway, such as by same-operon membership in bacteria. Using a modified experimental lac operon system, we are undertaking a combined theoretical-experimental approach to demonstrate that (i) the lac operon has an implicit ultrasensitive switch that we predict is avoided by gene expression correlations induced by same-operon membership; (ii) bacterial growth rates are sensitive to crossing the ultrasensitive threshold. Our results suggest that correlations in intrinsic gene expression noise are exploited by evolution to ameliorate the detrimental effects of nonlinearities in metabolite concentrations.

  3. Existence and Multiplicity Results for Nonlinear Differential Equations Depending on a Parameter in Semipositone Case

    Directory of Open Access Journals (Sweden)

    Hailong Zhu

    2012-01-01

    Full Text Available The existence and multiplicity of solutions for second-order differential equations with a parameter are discussed in this paper. We are mainly concerned with the semipositone case. The analysis relies on the nonlinear alternative principle of Leray-Schauder and Krasnosel'skii's fixed point theorem in cones.

  4. Effects of weak nonlinearity on dispersion relations and frequency band-gaps of periodic structures

    DEFF Research Database (Denmark)

    Sorokin, Vladislav; Thomsen, Jon Juel

    2015-01-01

    of these for nonlinear problems is impossible or cumbersome, since Floquet theory is applicable for linear systems only. Thus the nonlinear effects for periodic structures are not yet fully uncovered, while at the same time applica-tions may demand effects of nonlinearity on structural response to be accounted for....... The present work deals with analytically predicting dynamic responses for nonlinear continuous elastic periodic structures. Specifically, the effects of weak nonlinearity on the dispersion re-lation and frequency band-gaps of a periodic Bernoulli-Euler beam performing bending os-cillations are analyzed......The analysis of the behaviour of linear periodic structures can be traced back over 300 years, to Sir Isaac Newton, and still attracts much attention. An essential feature of periodic struc-tures is the presence of frequency band-gaps, i.e. frequency ranges in which waves cannot propagate...

  5. Preheating ablation effects on the Rayleigh-Taylor instability in the weakly nonlinear regime

    International Nuclear Information System (INIS)

    Wang, L. F.; Ye, W. H.; He, X. T.; Sheng, Z. M.; Don, Wai-Sun; Li, Y. J.

    2010-01-01

    The two-dimensional Rayleigh-Taylor instability (RTI) with and without thermal conduction is investigated by numerical simulation in the weakly nonlinear regime. A preheat model κ(T)=κ SH [1+f(T)] is introduced for the thermal conduction [W. H. Ye, W. Y. Zhang, and X. T. He, Phys. Rev. E 65, 057401 (2002)], where κ SH is the Spitzer-Haerm electron thermal conductivity coefficient and f(T) models the preheating tongue effect in the cold plasma ahead of the ablation front. The preheating ablation effects on the RTI are studied by comparing the RTI with and without thermal conduction with identical density profile relevant to inertial confinement fusion experiments. It is found that the ablation effects strongly influence the mode coupling process, especially with short perturbation wavelength. Overall, the ablation effects stabilize the RTI. First, the linear growth rate is reduced, especially for short perturbation wavelengths and a cutoff wavelength is observed in simulations. Second, the second harmonic generation is reduced for short perturbation wavelengths. Third, the third-order negative feedback to the fundamental mode is strengthened, which plays a stabilization role. Finally, on the contrary, the ablation effects increase the generation of the third harmonic when the perturbation wavelengths are long. Our simulation results indicate that, in the weakly nonlinear regime, the ablation effects are weakened as the perturbation wavelength is increased. Numerical results obtained are in general agreement with the recent weakly nonlinear theories as proposed in [J. Sanz, J. Ramirez, R. Ramis et al., Phys. Rev. Lett. 89, 195002 (2002); J. Garnier, P.-A. Raviart, C. Cherfils-Clerouin et al., Phys. Rev. Lett. 90, 185003 (2003)].

  6. A nonlinear mixed-effects model for simultaneous smoothing and registration of functional data

    DEFF Research Database (Denmark)

    Raket, Lars Lau; Sommer, Stefan Horst; Markussen, Bo

    2014-01-01

    We consider misaligned functional data, where data registration is necessary for proper statistical analysis. This paper proposes to treat misalignment as a nonlinear random effect, which makes simultaneous likelihood inference for horizontal and vertical effects possible. By simultaneously fitti...

  7. The Non-Linear Relationship between BMI and Health Care Costs and the Resulting Cost Fraction Attributable to Obesity.

    Science.gov (United States)

    Laxy, Michael; Stark, Renée; Peters, Annette; Hauner, Hans; Holle, Rolf; Teuner, Christina M

    2017-08-30

    This study aims to analyse the non-linear relationship between Body Mass Index (BMI) and direct health care costs, and to quantify the resulting cost fraction attributable to obesity in Germany. Five cross-sectional surveys of cohort studies in southern Germany were pooled, resulting in data of 6757 individuals (31-96 years old). Self-reported information on health care utilisation was used to estimate direct health care costs for the year 2011. The relationship between measured BMI and annual costs was analysed using generalised additive models, and the cost fraction attributable to obesity was calculated. We found a non-linear association of BMI and health care costs with a continuously increasing slope for increasing BMI without any clear threshold. Under the consideration of the non-linear BMI-cost relationship, a shift in the BMI distribution so that the BMI of each individual is lowered by one point is associated with a 2.1% reduction of mean direct costs in the population. If obesity was eliminated, and the BMI of all obese individuals were lowered to 29.9 kg/m², this would reduce the mean direct costs by 4.0% in the population. Results show a non-linear relationship between BMI and health care costs, with very high costs for a few individuals with high BMI. This indicates that population-based interventions in combination with selective measures for very obese individuals might be the preferred strategy.

  8. Influence of thermal effects induced by nonlinear absorption on four-wave mixing in silicon waveguides

    DEFF Research Database (Denmark)

    Pu, Minhao; Chen, Yaohui; Yvind, Kresten

    2014-01-01

    Influence of thermal effects induced by nonlinear absorption on four-wave mixing in silicon waveguides is investigated. A conversion bandwidth reduction up to 63% is observed in simulation due to the thermal effects.......Influence of thermal effects induced by nonlinear absorption on four-wave mixing in silicon waveguides is investigated. A conversion bandwidth reduction up to 63% is observed in simulation due to the thermal effects....

  9. Problems in nonlinear acoustics: Pulsed finite amplitude sound beams, nonlinear acoustic wave propagation in a liquid layer, nonlinear effects in asymmetric cylindrical sound beams, effects of absorption on the interaction of sound beams, and parametric receiving arrays

    Science.gov (United States)

    Hamilton, Mark F.

    1990-12-01

    This report discusses five projects all of which involve basic theoretical research in nonlinear acoustics: (1) pulsed finite amplitude sound beams are studied with a recently developed time domain computer algorithm that solves the KZK nonlinear parabolic wave equation; (2) nonlinear acoustic wave propagation in a liquid layer is a study of harmonic generation and acoustic soliton information in a liquid between a rigid and a free surface; (3) nonlinear effects in asymmetric cylindrical sound beams is a study of source asymmetries and scattering of sound by sound at high intensity; (4) effects of absorption on the interaction of sound beams is a completed study of the role of absorption in second harmonic generation and scattering of sound by sound; and (5) parametric receiving arrays is a completed study of parametric reception in a reverberant environment.

  10. All-Optical Control of Linear and Nonlinear Energy Transfer via the Zeno Effect

    Science.gov (United States)

    Guo, Xiang; Zou, Chang-Ling; Jiang, Liang; Tang, Hong X.

    2018-05-01

    Microresonator-based nonlinear processes are fundamental to applications including microcomb generation, parametric frequency conversion, and harmonics generation. While nonlinear processes involving either second- (χ(2 )) or third- (χ(3 )) order nonlinearity have been extensively studied, the interaction between these two basic nonlinear processes has seldom been reported. In this paper we demonstrate a coherent interplay between second- and third- order nonlinear processes. The parametric (χ(2 ) ) coupling to a lossy ancillary mode shortens the lifetime of the target photonic mode and suppresses its density of states, preventing the photon emissions into the target photonic mode via the Zeno effect. Such an effect is then used to control the stimulated four-wave mixing process and realize a suppression ratio of 34.5.

  11. Effects of quadratic and cubic nonlinearities on a perfectly tuned parametric amplifier

    DEFF Research Database (Denmark)

    Neumeyer, Stefan; Sorokin, Vladislav; Thomsen, Jon Juel

    2016-01-01

    We consider the performance of a parametric amplifier with perfect tuning (two-to-one ratio between the parametric and direct excitation frequencies) and quadratic and cubic nonlinearities. A forced Duffing–Mathieu equation with appended quadratic nonlinearity is considered as the model system......, and approximate analytical steady-state solutions and corresponding stabilities are obtained by the method of varying amplitudes. Some general effects of pure quadratic, and mixed quadratic and cubic nonlinearities on parametric amplification are shown. In particular, the effects of mixed quadratic and cubic...... nonlinearities may generate additional amplitude–frequency solutions. In this case an increased response and a more phase sensitive amplitude (phase between excitation frequencies) is obtained, as compared to the case with either pure quadratic or cubic nonlinearity. Furthermore, jumps and bi...

  12. Measuring RF circuits exhibiting nonlinear responses combined with short and long term memory effects

    NARCIS (Netherlands)

    Janssen, E.J.G.; Milosevic, D.; Baltus, P.G.M.

    2010-01-01

    All RF circuits that incorporate active devices exhibit nonlinear behavior. Nonlinearities result in signal distortion, and therefore state the upper limit of the dynamic range of the circuits. A measure for linearity used quite commonly in RF is the P1dB and/or IP3 point. These quantities are

  13. Existence Results for Differential Inclusions with Nonlinear Growth Conditions in Banach Spaces

    Directory of Open Access Journals (Sweden)

    Messaoud Bounkhel

    2013-01-01

    Full Text Available In the Banach space setting, the existence of viable solutions for differential inclusions with nonlinear growth; that is, ẋ(t∈F(t,x(t a.e. on I, x(t∈S, ∀t∈I, x(0=x0∈S, (*, where S is a closed subset in a Banach space , I=[0,T], (T>0, F:I×S→, is an upper semicontinuous set-valued mapping with convex values satisfying F(t,x⊂c(tx+xp, ∀(t,x∈I×S, where p∈ℝ, with p≠1, and c∈C([0,T],ℝ+. The existence of solutions for nonconvex sweeping processes with perturbations with nonlinear growth is also proved in separable Hilbert spaces.

  14. Nonlinear Optics and Applications

    Science.gov (United States)

    Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)

    2007-01-01

    Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.

  15. Intense laser effects on nonlinear optical absorption and optical rectification in single quantum wells under applied electric and magnetic field

    International Nuclear Information System (INIS)

    Duque, C.A.; Kasapoglu, E.; Sakiroglu, S.; Sari, H.; Soekmen, I.

    2011-01-01

    In this work the effects of intense laser on the electron-related nonlinear optical absorption and nonlinear optical rectification in GaAs-Ga 1-x Al x As quantum wells are studied under, applied electric and magnetic field. The electric field is applied along the growth direction of the quantum well whereas the magnetic field has been considered to be in-plane. The calculations were performed within the density matrix formalism with the use of the effective mass and parabolic band approximations. The intense laser effects are included through the Floquet method, by modifying the confining potential associated to the heterostructure. Results are presented for the nonlinear optical absorption, the nonlinear optical rectification and the resonant peak of these two optical processes. Several configurations of the dimensions of the quantum well, the applied electric and magnetic fields, and the incident intense laser radiation have been considered. The outcome of the calculation suggests that the nonlinear optical absorption and optical rectification are non-monotonic functions of the dimensions of the heterostructure and of the external perturbations considered in this work.

  16. Effect of bottom slope on the nonlinear triad interactions in shallow water

    Science.gov (United States)

    Chen, Hongzhou; Tang, Xiaocheng; Zhang, Ri; Gao, Junliang

    2018-05-01

    This paper aims at investigating the effect of bottom slope to the nonlinear triad interactions for irregular waves propagating in shallow water. The physical experiments are conducted in a wave flume with respect to the transformation of waves propagating on three bottom slopes ( β = 1/15, 1/30, and 1/45). Irregular waves with different type of breaking that are mechanically generated based on JONSWAP spectra are used for the test. The obviously different variations of spectra measured on each bottom reveal a crucial role of slope effect in the energy transfer between harmonics. The wavelet-based bispectrum were used to examine the bottom slope effect on the nonlinear triad interactions. Results show that the different bottom slopes which waves are propagated on will cause a significant discrepancy of triad interactions. Then, the discussions on the summed bicoherence which denote the distribution of phase coupling on each frequency further clarify the effect of bottom slope. Furthermore, the summed of the real and imaginary parts of bispectrum which could reflect the intensity of frequency components participating in the wave skewness and asymmetry were also investigated. Results indicate that the value of these parameters will increase as the bottom slope gets steeper.

  17. Transmutation of skyrmions to half-solitons driven by the nonlinear optical spin Hall effect.

    Science.gov (United States)

    Flayac, H; Solnyshkov, D D; Shelykh, I A; Malpuech, G

    2013-01-04

    We show that the spin domains, generated in the linear optical spin Hall effect by the analog of spin-orbit interaction for exciton polaritons, are associated with the formation of a Skyrmion lattice. In the nonlinear regime, the spin anisotropy of the polariton-polariton interactions results in a spatial compression of the domains and in a transmutation of the Skyrmions into oblique half-solitons. This phase transition is associated with both the focusing of the spin currents and the emergence of a strongly anisotropic emission pattern.

  18. Cumulative effect of structural nonlinearities: chaotic dynamics of cantilever beam system with impacts

    International Nuclear Information System (INIS)

    Emans, Joseph; Wiercigroch, Marian; Krivtsov, Anton M.

    2005-01-01

    The nonlinear analysis of a common beam system was performed, and the method for such, outlined and presented. Nonlinear terms for the governing dynamic equations were extracted and the behaviour of the system was investigated. The analysis was carried out with and without physically realistic parameters, to show the characteristics of the system, and the physically realistic responses. Also, the response as part of a more complex system was considered, in order to investigate the cumulative effects of nonlinearities. Chaos, as well as periodic motion was found readily for the physically unrealistic parameters. In addition, nonlinear behaviour such as co-existence of attractors was found even at modest oscillation levels during investigations with realistic parameters. When considered as part of a more complex system with further nonlinearities, comparisons with linear beam theory show the classical approach to be lacking in accuracy of qualitative predictions, even at weak oscillations

  19. Nonlinear Effects in Three-minute Oscillations of the Solar Chromosphere. I. An Analytical Nonlinear Solution and Detection of the Second Harmonic

    International Nuclear Information System (INIS)

    Chae, Jongchul; Litvinenko, Yuri E.

    2017-01-01

    The vertical propagation of nonlinear acoustic waves in an isothermal atmosphere is considered. A new analytical solution that describes a finite-amplitude wave of an arbitrary wavelength is obtained. Although the short- and long-wavelength limits were previously considered separately, the new solution describes both limiting cases within a common framework and provides a straightforward way of interpolating between the two limits. Physical features of the nonlinear waves in the chromosphere are described, including the dispersive nature of low-frequency waves, the steepening of the wave profile, and the influence of the gravitational field on wavefront breaking and shock formation. The analytical results suggest that observations of three-minute oscillations in the solar chromosphere may reveal the basic nonlinear effect of oscillations with combination frequencies, superposed on the normal oscillations of the system. Explicit expressions for a second-harmonic signal and the ratio of its amplitude to the fundamental harmonic amplitude are derived. Observational evidence of the second harmonic, obtained with the Fast Imaging Solar Spectrograph, installed at the 1.6 m New Solar Telescope of the Big Bear Observatory, is presented. The presented data are based on the time variations of velocity determined from the Na i D 2 and H α lines.

  20. Nonlinear Effects in Three-minute Oscillations of the Solar Chromosphere. I. An Analytical Nonlinear Solution and Detection of the Second Harmonic

    Energy Technology Data Exchange (ETDEWEB)

    Chae, Jongchul [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 08826 (Korea, Republic of); Litvinenko, Yuri E. [Department of Mathematics, University of Waikato, P. B. 3105, Hamilton 3240 (New Zealand)

    2017-08-01

    The vertical propagation of nonlinear acoustic waves in an isothermal atmosphere is considered. A new analytical solution that describes a finite-amplitude wave of an arbitrary wavelength is obtained. Although the short- and long-wavelength limits were previously considered separately, the new solution describes both limiting cases within a common framework and provides a straightforward way of interpolating between the two limits. Physical features of the nonlinear waves in the chromosphere are described, including the dispersive nature of low-frequency waves, the steepening of the wave profile, and the influence of the gravitational field on wavefront breaking and shock formation. The analytical results suggest that observations of three-minute oscillations in the solar chromosphere may reveal the basic nonlinear effect of oscillations with combination frequencies, superposed on the normal oscillations of the system. Explicit expressions for a second-harmonic signal and the ratio of its amplitude to the fundamental harmonic amplitude are derived. Observational evidence of the second harmonic, obtained with the Fast Imaging Solar Spectrograph, installed at the 1.6 m New Solar Telescope of the Big Bear Observatory, is presented. The presented data are based on the time variations of velocity determined from the Na i D{sub 2} and H α lines.

  1. Non-linear effects in the Snoek relaxation of Nb-O

    International Nuclear Information System (INIS)

    Hermida, E.B.; Povolo, F.

    1996-01-01

    Internal friction peaks measured as a function of temperature or frequency have been associated to non-linear processes only after studying how the amplitude of the applied stress affects the relaxation process. Here it is demonstrated that the partial derivative of the internal friction with respect to the frequency at constant temperature is a useful tool to determine that non-linear effects are involved. This analysis applied to actual data of the Snoek relaxation in Nb-O, reveals that at high interstitial contents non-linear effects appear. (orig.)

  2. DC magnetic field sensing based on the nonlinear magnetoelectric effect in magnetic heterostructures

    International Nuclear Information System (INIS)

    Burdin, Dmitrii; Chashin, Dmitrii; Ekonomov, Nikolai; Fetisov, Leonid; Fetisov, Yuri; Shamonin, Mikhail

    2016-01-01

    Recently, highly sensitive magnetic field sensors using the magnetoelectric effect in composite ferromagnetic-piezoelectric layered structures have been demonstrated. However, most of the proposed concepts are not useful for measuring dc magnetic fields, because the conductivity of piezoelectric layers results in a strong decline of the sensor’s sensitivity at low frequencies. In this paper, a novel functional principle of magnetoelectric sensors for dc magnetic field measurements is described. The sensor employs the nonlinear effect of voltage harmonic generation in a composite magnetoelectric structure under the simultaneous influence of a strong imposed ac magnetic field and a weak dc magnetic field to be measured. This physical effect arises due to the nonlinear dependence of the magnetostriction in the ferromagnetic layer on the magnetic field. A sensor prototype comprising of a piezoelectric fibre transducer sandwiched between two layers of the amorphous ferromagnetic Metglas ® alloy was fabricated. The specifications regarding the magnetic field range, frequency characteristics, and noise level were studied experimentally. The prototype showed the responsivity of 2.5 V mT −1 and permitted the measurement of dc magnetic fields in the range of ∼10 nT to about 0.4 mT. Although sensor operation is based on the nonlinear effect, the sensor response can be made linear with respect to the measured magnetic field in a broad dynamic range extending over 5 orders of magnitude. The underlying physics is explained through a simplified theory for the proposed sensor. The functionality, differences and advantages of the magnetoelectric sensor compare well with fluxgate magnetometers. The ways to enhance the sensor performance are considered. (paper)

  3. Probabilistic and Scenario Seismic and Liquefaction Hazard Analysis of the Mississippi Embayment Incorporating Nonlinear Site Effects

    Science.gov (United States)

    Cramer, C. H.; Dhar, M. S.

    2017-12-01

    The influence of deep sediment deposits of the Mississippi Embayment (ME) on the propagation of seismic waves is poorly understood and remains a major source of uncertainty for site response analysis. Many researchers have studied the effects of these deposits on seismic hazard of the area using available information at the time. In this study, we have used updated and newly available resources for seismic and liquefaction hazard analyses of the ME. We have developed an improved 3D geological model. Additionally, we used surface geological maps from Cupples and Van Arsdale (2013) to prepare liquefaction hazard maps. Both equivalent linear and nonlinear site response codes were used to develop site amplification distributions for use in generating hazard maps. The site amplification distributions are created using the Monte Carlo approach of Cramer et al. (2004, 2006) on a 0.1-degree grid. The 2014 National Seismic Hazard model and attenuation relations (Petersen et al., 2014) are used to prepare seismic hazard maps. Then liquefaction hazard maps are generated using liquefaction probability curves from Holzer (2011) and Cramer et al. (2015). Equivalent linear response (w/ increased precision, restricted nonlinear behavior with depth) shows similar hazard for the ME compared to nonlinear analysis (w/o pore pressure) results. At short periods nonlinear deamplification dominates the hazard, but at long periods resonance amplification dominates. The liquefaction hazard tends to be high in Holocene and late Pleistocene lowland sediments, even with lowered ground water levels, and low in Pleistocene loess of the uplands. Considering pore pressure effects in nonlinear site response analysis at a test site on the lowlands shows amplification of ground motion at short periods. PGA estimates from ME liquefaction and MMI observations are in the 0.25 to 0.4 g range. Our estimated M7.5 PGA hazard within 10 km of the fault can exceed this. Ground motion observations from

  4. Non-linear Analysis of Scalp EEG by Using Bispectra: The Effect of the Reference Choice

    Directory of Open Access Journals (Sweden)

    Federico Chella

    2017-05-01

    Full Text Available Bispectral analysis is a signal processing technique that makes it possible to capture the non-linear and non-Gaussian properties of the EEG signals. It has found various applications in EEG research and clinical practice, including the assessment of anesthetic depth, the identification of epileptic seizures, and more recently, the evaluation of non-linear cross-frequency brain functional connectivity. However, the validity and reliability of the indices drawn from bispectral analysis of EEG signals are potentially biased by the use of a non-neutral EEG reference. The present study aims at investigating the effects of the reference choice on the analysis of the non-linear features of EEG signals through bicoherence, as well as on the estimation of cross-frequency EEG connectivity through two different non-linear measures, i.e., the cross-bicoherence and the antisymmetric cross-bicoherence. To this end, four commonly used reference schemes were considered: the vertex electrode (Cz, the digitally linked mastoids, the average reference, and the Reference Electrode Standardization Technique (REST. The reference effects were assessed both in simulations and in a real EEG experiment. The simulations allowed to investigated: (i the effects of the electrode density on the performance of the above references in the estimation of bispectral measures; and (ii the effects of the head model accuracy in the performance of the REST. For real data, the EEG signals recorded from 10 subjects during eyes open resting state were examined, and the distortions induced by the reference choice in the patterns of alpha-beta bicoherence, cross-bicoherence, and antisymmetric cross-bicoherence were assessed. The results showed significant differences in the findings depending on the chosen reference, with the REST providing superior performance than all the other references in approximating the ideal neutral reference. In conclusion, this study highlights the importance of

  5. Using nonlinearity and spatiotemporal property modulation to control effective structural properties: dynamic rods

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel; Blekhman, Iliya I.

    2007-01-01

    What are the effective properties of a generally nonlinear material or structure, whose local properties are modulated in both space and time? It has been suggested to use spatiotemporal modulation of structural properties to create materials and structures with adjustable effective properties......, and to call these dynamic materials or spatiotemporal composites. Also, according to theoretical predictions, structural nonlinearity enhances the possibilities of achieving specific effective properties. For example, with an elastic rod having cubical elastic nonlinearities, it seems possible to control......, and exemplified. Then simple approximate analytical expressions are derived for the effective wave speed and natural frequencies for one-dimensional wave propagation in a nonlinear elastic rod, where the spatiotemporal modulation is imposed as a high-frequency standing wave, supposed to be given. Finally the more...

  6. Diffraction corrections for second harmonic beam fields and effects on the nonlinearity parameter evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hyun Jo; Cho, Sung Jong; Nam, Ki Woong; Lee, Jang Hyun [Division of Mechanical and Automotive Engineering, Wonkwang University, Iksan (Korea, Republic of)

    2016-04-15

    The nonlinearity parameter is frequently measured as a sensitive indicator in damaged material characterization or tissue harmonic imaging. Several previous studies have employed the plane wave solution, and ignored the effects of beam diffraction when measuring the non-linearity parameter β. This paper presents a multi-Gaussian beam approach to explicitly derive diffraction corrections for fundamental and second harmonics under quasilinear and paraxial approximation. Their effects on the nonlinearity parameter estimation demonstrate complicated dependence of β on the transmitter-receiver geometries, frequency, and propagation distance. The diffraction effects on the non-linearity parameter estimation are important even in the nearfield region. Experiments are performed to show that improved β values can be obtained by considering the diffraction effects.

  7. Arsenite Effects on Mitochondrial Bioenergetics in Human and Mouse Primary Hepatocytes Follow a Nonlinear Dose Response

    Directory of Open Access Journals (Sweden)

    Hemantkumar Chavan

    2017-01-01

    Full Text Available Arsenite is a known carcinogen and its exposure has been implicated in a variety of noncarcinogenic health concerns. Increased oxidative stress is thought to be the primary cause of arsenite toxicity and the toxic effect is thought to be linear with detrimental effects reported at all concentrations of arsenite. But the paradigm of linear dose response in arsenite toxicity is shifting. In the present study we demonstrate that arsenite effects on mitochondrial respiration in primary hepatocytes follow a nonlinear dose response. In vitro exposure of primary hepatocytes to an environmentally relevant, moderate level of arsenite results in increased oxidant production that appears to arise from changes in the expression and activity of respiratory Complex I of the mitochondrial proton circuit. In primary hepatocytes the excess oxidant production appears to elicit adaptive responses that promote resistance to oxidative stress and a propensity to increased proliferation. Taken together, these results suggest a nonlinear dose-response characteristic of arsenite with low-dose arsenite promoting adaptive responses in a process known as mitohormesis, with transient increase in ROS levels acting as transducers of arsenite-induced mitohormesis.

  8. Dosage-dependent non-linear effect of L-dopa on human motor cortex plasticity.

    Science.gov (United States)

    Monte-Silva, Katia; Liebetanz, David; Grundey, Jessica; Paulus, Walter; Nitsche, Michael A

    2010-09-15

    The neuromodulator dopamine affects learning and memory formation and their likely physiological correlates, long-term depression and potentiation, in animals and humans. It is known from animal experiments that dopamine exerts a dosage-dependent, inverted U-shaped effect on these functions. However, this has not been explored in humans so far. In order to reveal a non-linear dose-dependent effect of dopamine on cortical plasticity in humans, we explored the impact of 25, 100 and 200 mg of L-dopa on transcranial direct current (tDCS)-induced plasticity in twelve healthy human subjects. The primary motor cortex served as a model system, and plasticity was monitored by motor evoked potential amplitudes elicited by transcranial magnetic stimulation. As compared to placebo medication, low and high dosages of L-dopa abolished facilitatory as well as inhibitory plasticity, whereas the medium dosage prolonged inhibitory plasticity, and turned facilitatory plasticity into inhibition. Thus the results show clear non-linear, dosage-dependent effects of dopamine on both facilitatory and inhibitory plasticity, and support the assumption of the importance of a specific dosage of dopamine optimally suited to improve plasticity. This might be important for the therapeutic application of dopaminergic agents, especially for rehabilitative purposes, and explain some opposing results in former studies.

  9. Soil non-linearity and its effect on the dynamic behaviour of offshore platform foundations

    Energy Technology Data Exchange (ETDEWEB)

    Madshus, Christian

    1997-07-01

    This thesis focuses on non-linear soil response to the type of cyclic loading experienced under offshore gravity base platform foundations. These loads are dominated by a cyclic component around the main wave frequency, which may well mobilize soil non-linearity under severe sea-states. Superimposed on this main component are lower level higher frequency loads caused by resonant oscillations of the platform. The thesis presents results of specially designed triaxial tests to simulate this loading condition. The tests simultaneously applied two cyclic load components at different frequencies and amplitudes. The measured soil response to each component has been isolated through a frequency domain separation. It was found that the soil responds to the superimposed high frequency low level component as if the soil had a cyclically time-varying stiffness. If the superimposed component does not lead to load reversals, this stiffness variation is controlled by the frequency and amplitude of the main load component and by the hysteretic non-linearity of the soil. If the superimposed component causes reversals, the influence of the hysteretic non-linearity on the stiffness variation is reduced. The higher the degree of reversal, the more this influence it taken over by the variation in the instantaneous unloading-reloading stiffness of the soil. It was also found that this type of two-frequency cyclic soil testing is generally superior over conventional single-frequency testing in the way it enforces the soil to reveal several of its inherent properties not deducible from ordinary tests. Benefits of analyzing non-linear response in the frequency domain is demonstrated throughout this thesis. The ability of various theoretical soil models to simulate the observed soil behaviour under two-frequency cyclic loading has, been investigated through numerical analyses. It was found that only those models that are based on kinematic hardening are able to reproduce what was observed

  10. Effective response of nonlinear cylindrical coated composites under external AC and DC electric field

    International Nuclear Information System (INIS)

    Yu-Yan, Shen; Xiao-Gang, Chen; Wei, Cui; Yan-Hua, Hao; Qian-Qian, Li

    2009-01-01

    This paper uses the perturbation method to study effective response of nonlinear cylindrical coated composites. Under the external AC and DC electric field E a (1 + sin ωt), the local potentials of composites at all harmonic frequencies are induced. An effective nonlinear response to composite is given for the cylindrical coated inclusions in the dilute limit. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  11. Unexpected nonlinear effects and critical coupling in NbN superconducting microwave resonators

    International Nuclear Information System (INIS)

    Abdo, B.; Buks, E.

    2004-01-01

    Full Text:In this work, we have designed and fabricated several NbN superconducting stripline microwave resonators sputtered on sapphire substrates. The low temperature response exhibits strong and unexpected nonlinear effects, including sharp jumps as the frequency or poser are varied, frequency hysteresis loops changing direction as the input power is varied, and others. Contrary to some other superconducting resonators, a simple model of a one-dimensional Duffing resonator cannot account for the experimental results. Whereas the physical origin of the unusual nonlinear response of our samples remains an open question, our intensive experimental study of these effects under varying conditions provides some important insight. We consider a hypothesis according to which Josephson junctions forming weak links between the grains of the NbN are responsible for the observed behavior. We show that most of the experimental results are qualitatively consistent with such hypothesis. While revealing the underlying physics remains an outstanding challenge for future research, the utilization of the unusual nonlinear response for some novel applications is already demonstrated in the present work. In particular an operate the resonator as an inter modulation amplifier and find that the gain can be as high as 15 dB. To the best of our knowledge, inter modulation gain greater than unity has not been reported before in the scientific literature. In another application we demonstrate for the first time that the coupling between the resonator and its feed line can be made amplitude dependent. This novel mechanism allows us to tune the resonator into critical coupling conditions

  12. Analysis of Conductor Impedances Accounting for Skin Effect and Nonlinear Permeability

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, M P; Ong, M M; Brown, C G; Speer, R D

    2011-07-20

    It is often necessary to protect sensitive electrical equipment from pulsed electric and magnetic fields. To accomplish this electromagnetic shielding structures similar to Faraday Cages are often implemented. If the equipment is inside a facility that has been reinforced with rebar, the rebar can be used as part of a lighting protection system. Unfortunately, such shields are not perfect and allow electromagnetic fields to be created inside due to discontinuities in the structure, penetrations, and finite conductivity of the shield. In order to perform an analysis of such a structure it is important to first determine the effect of the finite impedance of the conductors used in the shield. In this paper we will discuss the impedances of different cylindrical conductors in the time domain. For a time varying pulse the currents created in the conductor will have different spectral components, which will affect the current density due to skin effects. Many construction materials use iron and different types of steels that have a nonlinear permeability. The nonlinear material can have an effect on the impedance of the conductor depending on the B-H curve. Although closed form solutions exist for the impedances of cylindrical conductors made of linear materials, computational techniques are needed for nonlinear materials. Simulations of such impedances are often technically challenging due to the need for a computational mesh to be able to resolve the skin depths for the different spectral components in the pulse. The results of such simulations in the time domain will be shown and used to determine the impedances of cylindrical conductors for lightning current pulses that have low frequency content.

  13. Density gradient effects in weakly nonlinear ablative Rayleigh-Taylor instability

    International Nuclear Information System (INIS)

    Wang, L. F.; Ye, W. H.; He, X. T.

    2012-01-01

    In this research, density gradient effects (i.e., finite thickness of ablation front effects) in ablative Rayleigh-Taylor instability (ARTI), in the presence of preheating within the weakly nonlinear regime, are investigated numerically. We analyze the weak, medium, and strong ablation surfaces which have different isodensity contours, respectively, to study the influences of finite thickness of ablation front on the weakly nonlinear behaviors of ARTI. Linear growth rates, generation coefficients of the second and the third harmonics, and coefficients of the third-order feedback to the fundamental mode are obtained. It is found that the linear growth rate which has a remarkable maximum, is reduced, especially when the perturbation wavelength λ is short and a cut-off perturbation wavelength λ c appears when the perturbation wavelength λ is sufficiently short, where no higher harmonics exists when λ c . The phenomenon of third-order positive feedback to the fundamental mode near the λ c [J. Sanz et al., Phys. Rev. Lett. 89, 195002 (2002); J. Garnier et al., Phys. Rev. Lett. 90, 185003 (2003); J. Garnier and L. Masse, Phys. Plasmas 12, 062707 (2005)] is confirmed in numerical simulations, and the physical mechanism of the third-order positive feedback is qualitatively discussed. Moreover, it is found that generations and growths of the second and the third harmonics are stabilized (suppressed and reduced) by the ablation effect. Meanwhile, the third-order negative feedback to the fundamental mode is also reduced by the ablation effect, and hence, the linear saturation amplitude (typically ∼0.2λ in our simulations) is increased significantly and therefore exceeds the classical prediction 0.1λ, especially for the strong ablation surface with a small perturbation wavelength. Overall, the ablation effect stabilizes the ARTI in the weakly nonlinear regime. Numerical results obtained are in general agreement with the recent weakly nonlinear theories and simulations

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

    International Nuclear Information System (INIS)

    Boca, Madalina; Dinu, Victor; Florescu, Viorica

    2012-01-01

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

  15. GUIDING NONLINEAR FORCE-FREE MODELING USING CORONAL OBSERVATIONS: FIRST RESULTS USING A QUASI-GRAD-RUBIN SCHEME

    Energy Technology Data Exchange (ETDEWEB)

    Malanushenko, A. [Department of Physics, Montana State University, Bozeman, MT (United States); Schrijver, C. J.; DeRosa, M. L. [Lockheed Martin Advanced Technology Center, Palo Alto, CA (United States); Wheatland, M. S.; Gilchrist, S. A. [Sydney Institute for Astronomy, School of Physics, University of Sydney (Australia)

    2012-09-10

    At present, many models of the coronal magnetic field rely on photospheric vector magnetograms, but these data have been shown to be problematic as the sole boundary information for nonlinear force-free field extrapolations. Magnetic fields in the corona manifest themselves in high-energy images (X-rays and EUV) in the shapes of coronal loops, providing an additional constraint that is not at present used as constraints in the computational domain, directly influencing the evolution of the model. This is in part due to the mathematical complications of incorporating such input into numerical models. Projection effects, confusion due to overlapping loops (the coronal plasma is optically thin), and the limited number of usable loops further complicate the use of information from coronal images. We develop and test a new algorithm to use images of coronal loops in the modeling of the solar coronal magnetic field. We first fit projected field lines with those of constant-{alpha} force-free fields to approximate the three-dimensional distribution of currents in the corona along a sparse set of trajectories. We then apply a Grad-Rubin-like iterative technique, which uses these trajectories as volume constraints on the values of {alpha}, to obtain a volume-filling nonlinear force-free model of the magnetic field, modifying a code and method presented by Wheatland. We thoroughly test the technique on known analytical and solar-like model magnetic fields previously used for comparing different extrapolation techniques and compare the results with those obtained by currently available methods relying only on the photospheric data. We conclude that we have developed a functioning method of modeling the coronal magnetic field by combining the line-of-sight component of the photospheric magnetic field with information from coronal images. Whereas we focus on the use of coronal loop information in combination with line-of-sight magnetograms, the method is readily extended to

  16. GUIDING NONLINEAR FORCE-FREE MODELING USING CORONAL OBSERVATIONS: FIRST RESULTS USING A QUASI-GRAD-RUBIN SCHEME

    International Nuclear Information System (INIS)

    Malanushenko, A.; Schrijver, C. J.; DeRosa, M. L.; Wheatland, M. S.; Gilchrist, S. A.

    2012-01-01

    At present, many models of the coronal magnetic field rely on photospheric vector magnetograms, but these data have been shown to be problematic as the sole boundary information for nonlinear force-free field extrapolations. Magnetic fields in the corona manifest themselves in high-energy images (X-rays and EUV) in the shapes of coronal loops, providing an additional constraint that is not at present used as constraints in the computational domain, directly influencing the evolution of the model. This is in part due to the mathematical complications of incorporating such input into numerical models. Projection effects, confusion due to overlapping loops (the coronal plasma is optically thin), and the limited number of usable loops further complicate the use of information from coronal images. We develop and test a new algorithm to use images of coronal loops in the modeling of the solar coronal magnetic field. We first fit projected field lines with those of constant-α force-free fields to approximate the three-dimensional distribution of currents in the corona along a sparse set of trajectories. We then apply a Grad-Rubin-like iterative technique, which uses these trajectories as volume constraints on the values of α, to obtain a volume-filling nonlinear force-free model of the magnetic field, modifying a code and method presented by Wheatland. We thoroughly test the technique on known analytical and solar-like model magnetic fields previously used for comparing different extrapolation techniques and compare the results with those obtained by currently available methods relying only on the photospheric data. We conclude that we have developed a functioning method of modeling the coronal magnetic field by combining the line-of-sight component of the photospheric magnetic field with information from coronal images. Whereas we focus on the use of coronal loop information in combination with line-of-sight magnetograms, the method is readily extended to incorporate

  17. Effect of magnetic field on ablatively driven Richtmyer-Meshkov instability induced by interfacial nonlinear structure

    International Nuclear Information System (INIS)

    Labakanta Mandal; Banerjee, R.; Roy, S.; Khan, M.; Gupta, M.R.

    2010-01-01

    Complete text of publication follows. In an Inertial Confinement Fusion (ICF) situation, laser driven ablation front of an imploding capsule is subjected to the fluid instabilities like Rayleigh-Taylor (RT), Richtmyer-Meshkov (RM) and Kelvin-Helmholtz (KH) instability. In this case dense core is compressed and accelerated by low density ablating plasma. During this process laser driven shocks interact the interface and hence it becomes unstable due to the formation of nonlinear structure like bubble and spike. The nonlinear structure is called bubble if the lighter fluid pushes inside the heavier fluid and spike, if opposite takes place. R-M instability causes non-uniform compression of ICF fuel pellets and needs to be mitigated. Scientists and researchers are much more interested on RM instability both from theoretical and experimental points of view. In this article, we have presented the analytical expression for the growth rate and velocity for the nonlinear structures due to the effect of magnetic field of fluid using potential flow model. The magnetic field is assumed to be parallel to the plane of two fluid interfaces. If the magnetic field is restricted only to either side of interface the R-M instability can be stabilized or destabilized depending on whether the magnetic pressure on the interface opposes the instability driving shock pressure or acts in the same direction. An interesting result is that if both the fluids are magnetized, interface as well as velocity of bubble and spike will show oscillating stabilization and R-M instability is mitigated. All analytical results are also supported by numerical results. Numerically it is seen that magnetic field above certain minimum value reduces the instability for compression the target in ICF.

  18. A Multiphase Non-Linear Mixed Effects Model: An Application to Spirometry after Lung Transplantation

    Science.gov (United States)

    Rajeswaran, Jeevanantham; Blackstone, Eugene H.

    2014-01-01

    In medical sciences, we often encounter longitudinal temporal relationships that are non-linear in nature. The influence of risk factors may also change across longitudinal follow-up. A system of multiphase non-linear mixed effects model is presented to model temporal patterns of longitudinal continuous measurements, with temporal decomposition to identify the phases and risk factors within each phase. Application of this model is illustrated using spirometry data after lung transplantation using readily available statistical software. This application illustrates the usefulness of our flexible model when dealing with complex non-linear patterns and time varying coefficients. PMID:24919830

  19. A multilevel nonlinear mixed-effects approach to model growth in pigs

    DEFF Research Database (Denmark)

    Strathe, Anders Bjerring; Danfær, Allan Christian; Sørensen, H.

    2010-01-01

    Growth functions have been used to predict market weight of pigs and maximize return over feed costs. This study was undertaken to compare 4 growth functions and methods of analyzing data, particularly one that considers nonlinear repeated measures. Data were collected from an experiment with 40...... pigs maintained from birth to maturity and their BW measured weekly or every 2 wk up to 1,007 d. Gompertz, logistic, Bridges, and Lopez functions were fitted to the data and compared using information criteria. For each function, a multilevel nonlinear mixed effects model was employed because....... Furthermore, studies should consider adding continuous autoregressive process when analyzing nonlinear mixed models with repeated measures....

  20. Unexpected Nonlinear Effects in Superconducting Transition-Edge Sensors

    Science.gov (United States)

    Sadleir, John

    2016-01-01

    When a normal metal transitions into the superconducting state the DC resistance drops from a finite value to zero over some finite transition width in temperature, current, and magnetic field. Superconducting transition-edge sensors (TESs) operate within this transition region and uses resistive changes to measure deposited thermal energy. This resistive transition is not perfectly smooth and a wide range of TES designs and materials show sub-structure in the resistive transition (as seen in smooth nonmonotonic behavior, jump discontinuities, and hysteresis in the devices current-voltage relation and derivatives of the resistance with respect to temperature, bias current, and magnetic field). TES technology has advanced to the point where for many applications this structure is the limiting factor in performance and optimization consists of finding operating points away from these structures. For example, operating at or near this structure can lead to nonlinearity in the detectors response and gain scale, limit the spectral range of the detector by limiting the usable resistive range, and degrade energy resolution. The origin of much of this substructure is unknown. This presentation investigates a number of possible sources in turn. First we model the TES as a superconducting weak-link and solve for the characteristic differential equations current and voltage time dependence. We find:(1) measured DC biased current-voltage relationship is the time-average of a much higher frequency limit cycle solution.(2) We calculate the fundamental frequency and estimate the power radiated from the TES treating the bias leads as an antennae.(3) The solution for a set of circuit parameters becomes multivalued leading to current transitions between levels.(4)The circuit parameters can change the measure resistance and mask the true critical current. As a consequence the TES resistance surface is not just a function of temperature, current, and magnetic field but is also a

  1. Noise-induced transitions and resonant effects in nonlinear systems

    Science.gov (United States)

    Zaikin, Alexei

    2003-02-01

    Our every-day experience is connected with different acoustical noise or music. Usually noise plays the role of nuisance in any communication and destroys any order in a system. Similar optical effects are known: strong snowing or raining decreases quality of a vision. In contrast to these situations noisy stimuli can also play a positive constructive role, e.g. a driver can be more concentrated in a presence of quiet music. Transmission processes in neural systems are of especial interest from this point of view: excitation or information will be transmitted only in the case if a signal overcomes a threshold. Dr. Alexei Zaikin from the Potsdam University studies noise-induced phenomena in nonlinear systems from a theoretical point of view. Especially he is interested in the processes, in which noise influences the behaviour of a system twice: if the intensity of noise is over a threshold, it induces some regular structure that will be synchronized with the behaviour of neighbour elements. To obtain such a system with a threshold one needs one more noise source. Dr. Zaikin has analyzed further examples of such doubly stochastic effects and developed a concept of these new phenomena. These theoretical findings are important, because such processes can play a crucial role in neurophysics, technical communication devices and living sciences. Unsere alltägliche Erfahrung ist mit verschiedenen akustischen Einfluessen wie Lärm, aber auch Musik verbunden. Jeder weiss, wie Lärm stören kann und Kommunikation behindert oder gar unterbindet. Ähnliche optische Effekte sind bekannt: starkes Schneetreiben oder Regengüsse verschlechtern die Sicht und lassen uns Umrisse nur noch schemenhaft erkennen. Jedoch koennen ähnliche Stimuli auch sehr positive Auswirkungen haben: Autofahrer fahren bei leiser Musik konzentrierter -- die Behauptung von Schulkindern, nur bei dröhnenden Bässen die Mathehausaufgaben richtig rechnen zu können, ist allerdings nicht wissenschaftlich

  2. Effect of sample shape on nonlinear magnetization dynamics under an external magnetic field

    International Nuclear Information System (INIS)

    Vagin, Dmitry V.; Polyakov, Oleg P.

    2008-01-01

    Effect of sample shape on the nonlinear collective dynamics of magnetic moments in the presence of oscillating and constant external magnetic fields is studied using the Landau-Lifshitz-Gilbert (LLG) approach. The uniformly magnetized sample is considered to be an ellipsoidal axially symmetric particle described by demagnetization factors and uniaxial crystallographic anisotropy formed some angle with an applied field direction. It is investigated as to how the change in particle shape affects its nonlinear magnetization dynamics. To produce a regular study, all results are presented in the form of bifurcation diagrams for all sufficient dynamics regimes of the considered system. In this paper, we show that the sample's (particle's) shape and its orientation with respect to the external field (system configuration) determine the character of magnetization dynamics: deterministic behavior and appearance of chaotic states. A simple change in the system's configuration or in the shapes of its parts can transfer it from chaotic to periodic or even static regime and back. Moreover, the effect of magnetization precession stall and magnetic moments alignment parallel or antiparallel to the external oscillating field is revealed and the way of control of such 'polarized' states is found. Our results suggest that varying the particle's shape and fields' geometry may provide a useful way of magnetization dynamics control in complex magnetic systems

  3. The effects of nonlinear wave propagation on the stability of inertial cavitation

    International Nuclear Information System (INIS)

    Sinden, D; Stride, E; Saffari, N

    2009-01-01

    In the context of forecasting temperature and pressure fields generated by high-intensity focussed ultrasound, the accuracy of predictive models is critical for the safety and efficacy of treatment. In such fields 'inertial' cavitation is often observed. Classically, estimations of cavitation thresholds have been based on the assumption that the incident wave at the surface of a bubble is the same as in the far-field, neglecting the effect of nonlinear wave propagation. By modelling the incident wave as a solution to Burgers' equation using weak shock theory, the effects of nonlinear wave propagation on inertial cavitation are investigated using both numerical and analytical techniques. From radius-time curves for a single bubble, it is observed that there is a reduction in the maximum size of a bubble undergoing inertial cavitation and that the inertial collapse occurs earlier in contrast with the classical case. Corresponding stability thresholds for a bubble whose initial radius is slightly below the critical Blake radius are calculated, providing a lower bound for the onset of instability. Bifurcation diagrams and frequency-response curves are presented associated with the loss of stability. The consequences and physical implications of the results are discussed with respect to the classical results.

  4. A nonlinear flow-induced energy harvester by considering effects of fictitious springs

    Science.gov (United States)

    Zhang, Guangcheng; Lin, Yueh-Jaw

    2018-01-01

    In this paper, a newly proposed energy harvesting approach involving nonlinear coupling effects is demonstrated by utilizing a pair of inducing bluff bodies that are put on both sides of the flag-shaped cantilever beam, and placed in a side-by-side configuration to harvest the energy of the flow. One patch of macro fiber composite is attached to the fixed end of the cantilever beam to facilitate converting the kinetic energy into electric power. It is the first time in recent literature that two fluid dynamic phenomena (i.e. the vortex shedding and the Bernoulli effect) are considered simultaneously in the flow-induced energy harvesting field. The fictitious springs are introduced to explain the nonlinear characteristics of the proposed structure. With the effect of the fictitious springs, the speed range of the flow-induced energy harvester is extended. The proposed structure not only improves the output of the induced-based energy harvester compared to one that has just one cylinder, but can also be utilized in an actual hostile ambient environment. The experimental results for the energy harvester prototype are also investigated. The output power of the energy harvester with two cylinders (D = 25 mm) is measured to be 1.12 μW when the flow speed is 0.325 m s-1 and the center-to-center transverse spacing is 45 mm. This research also delves into the geometric variations of the proposed structure and its optimization.

  5. Analysis of nonlinear vibrations and stability of rotating asymmetrical nano-shafts incorporating surface energy effects

    Science.gov (United States)

    Ghodousi, Maryam; Shahgholi, Majid; Payganeh, Gholamhassan

    2018-03-01

    The objective of the present work is to investigate the nonlinear vibrations of the rotating asymmetrical nano-shafts by considering surface effect. In order to compute the surface stress tensor, the surface elasticity theory is used. The governing nonlinear equations of motion are obtained with the aid of variational approach. Bubnov-Galerkin is a very effective method for exploiting the reduced-order model of the equations of motion. The averaging method is employed to analyze the reduced-order model of the system. For this purpose, the well-known Van der Pol transformation in the complex form and angle-action transformation are utilized. The effect of surface stress on the forward and backward speeds, steady state responses of the system, fixed points, close orbits and stability of the solutions is examined. The preliminary results of the research show that the absolute values of forward and backward whirling speeds in the presence of surface effect with positive residual surface stress are higher than those of regarding the system without surface effect and in the presence of surface effect with negative residual surface stress. In addition, it is seen that the undamped rotating asymmetrical nano-shaft, for specified value of detuning parameter, in the absence or presence of surface effect has various number of stable and unstable periodic solutions. Besides, there is different number of separatrix (homoclinic orbit type). Furthermore, bifurcations, number of solutions and their stability for damped rotating asymmetrical nano-shaft are investigated. Also, the above results have been obtained for rotating symmetrical nano-shaft.

  6. Weakly nonlinear dispersion and stop-band effects for periodic structures

    DEFF Research Database (Denmark)

    Sorokin, Vladislav; Thomsen, Jon Juel

    of frequency band-gaps, i.e. frequency ranges in which elastic waves cannot propagate. Most existing analytical methods in the field are based on Floquet theory [1]; e.g. this holds for the classical Hill’s method of infinite determinants [1,2], and themethod of space-harmonics [3]. However, application...... of these methods for studying nonlinear problems isimpossible or cumbersome, since Floquet theory is applicable only for linear systems. Thus the nonlinear effects for periodic structures are not yet fully uncovered, while at the same time applications may demand effects of nonlinearity on structural response...... to be accounted for.The paper deals with analytically predicting dynamic response for nonlinear elastic structures with a continuous periodic variation in structural properties. Specifically, for a Bernoulli-Euler beam with aspatially continuous modulation of structural properties in the axial direction...

  7. Digital nonlinearity compensation in high-capacity optical communication systems considering signal spectral broadening effect.

    Science.gov (United States)

    Xu, Tianhua; Karanov, Boris; Shevchenko, Nikita A; Lavery, Domaniç; Liga, Gabriele; Killey, Robert I; Bayvel, Polina

    2017-10-11

    Nyquist-spaced transmission and digital signal processing have proved effective in maximising the spectral efficiency and reach of optical communication systems. In these systems, Kerr nonlinearity determines the performance limits, and leads to spectral broadening of the signals propagating in the fibre. Although digital nonlinearity compensation was validated to be promising for mitigating Kerr nonlinearities, the impact of spectral broadening on nonlinearity compensation has never been quantified. In this paper, the performance of multi-channel digital back-propagation (MC-DBP) for compensating fibre nonlinearities in Nyquist-spaced optical communication systems is investigated, when the effect of signal spectral broadening is considered. It is found that accounting for the spectral broadening effect is crucial for achieving the best performance of DBP in both single-channel and multi-channel communication systems, independent of modulation formats used. For multi-channel systems, the degradation of DBP performance due to neglecting the spectral broadening effect in the compensation is more significant for outer channels. Our work also quantified the minimum bandwidths of optical receivers and signal processing devices to ensure the optimal compensation of deterministic nonlinear distortions.

  8. Effect of temperature on the structural, linear, and nonlinear optical properties of MgO-doped graphene oxide nanocomposites

    Science.gov (United States)

    Kimiagar, Salimeh; Abrinaei, Fahimeh

    2018-01-01

    Magnesium oxide (MgO)-graphene oxide (GO) nanocomposites were prepared by the hydrothermal method at different temperatures. The effect of growth temperature on the structural, linear, and nonlinear optical (NLO) parameters was investigated. The decoration of MgO on GO sheets was confirmed by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and UV-visible (UV-vis) spectroscopy analyses. The energy band-gaps of MgO-GO nanocomposites were calculated from UV-vis spectrum using Tauc plot. The NLO parameters of MgO-GO nanocomposites were calculated for the first time by the simple Z-scan technique with nanosecond Nd:YAG laser at 532 nm. The nonlinear absorption coefficient β and nonlinear refractive index n2 for MgO-GO nanocomposites at the laser intensity of 1.1×108 W/cm2 were measured to be in the order of 10-7 cm/W and 10-12 cm2/W, respectively. The third-order NLO susceptibility of MgO-GO nanocomposites was measured in the order of 10-9 esu. The results showed that MgO-GO structures have negative nonlinearity as well as good nonlinear two-photon absorption at 532 nm. Furthermore, the NLO parameters increased by the enhancement of the growth temperature. As the investigation of new materials plays an important role in the advancement of optoelectronics, MgO-GO nanocomposites possess potential applications in NLO devices.

  9. Two-dimensional linear and nonlinear Talbot effect from rogue waves.

    Science.gov (United States)

    Zhang, Yiqi; Belić, Milivoj R; Petrović, Milan S; Zheng, Huaibin; Chen, Haixia; Li, Changbiao; Lu, Keqing; Zhang, Yanpeng

    2015-03-01

    We introduce two-dimensional (2D) linear and nonlinear Talbot effects. They are produced by propagating periodic 2D diffraction patterns and can be visualized as 3D stacks of Talbot carpets. The nonlinear Talbot effect originates from 2D rogue waves and forms in a bulk 3D nonlinear medium. The recurrences of an input rogue wave are observed at the Talbot length and at the half-Talbot length, with a π phase shift; no other recurrences are observed. Differing from the nonlinear Talbot effect, the linear effect displays the usual fractional Talbot images as well. We also find that the smaller the period of incident rogue waves, the shorter the Talbot length. Increasing the beam intensity increases the Talbot length, but above a threshold this leads to a catastrophic self-focusing phenomenon which destroys the effect. We also find that the Talbot recurrence can be viewed as a self-Fourier transform of the initial periodic beam that is automatically performed during propagation. In particular, linear Talbot effect can be viewed as a fractional self-Fourier transform, whereas the nonlinear Talbot effect can be viewed as the regular self-Fourier transform. Numerical simulations demonstrate that the rogue-wave initial condition is sufficient but not necessary for the observation of the effect. It may also be observed from other periodic inputs, provided they are set on a finite background. The 2D effect may find utility in the production of 3D photonic crystals.

  10. Nonlinear susceptibility: A direct test of the quadrupolar Kondo effect in UBe13

    International Nuclear Information System (INIS)

    Ramirez, A.P.; Chandra, P.; Coleman, P.; Fisk, Z.; Smith, J.L.; Ott, H.R.

    1994-01-01

    We present the nonlinear susceptibility as a direct test of the quadrupolar Kondo scenario for heavy fermion behavior, and apply it to the case of cubic crystal-field symmetry. Within a single-ion model we compute the nonlinear susceptibility resulting from low-lying Γ 3 (5f 2 ) and Kramers (5f 3 ) doublets. We find that nonlinear susceptibility measurements on single-crystal UBe 13 are inconsistent with a quadrupolar (5f 2 ) ground state of the uranium ion; the experimental data indicate that the low-lying magnetic excitations of UBe 13 are predominantly dipolar in character

  11. Non-linear effects and plasma heating by lower-hybrid waves in the Petula tokamak

    International Nuclear Information System (INIS)

    Briand, P.; Dupas, L.; Golovato, S.N.; Singh, C.M.; Melin, G.; Grelot, P.; Legardeur, R.; Zymanski, S.

    1979-01-01

    Lower hybrid waves were excited by a two-waveguide 'grill' (nsub(parallel) approximately 1-10, Esub(grill) approximately 3kVcm -1 , Psub(grill) approximately 5kWcm -2 ) at 1.25GHz, 3ms, 600kW. Plasma heating was observed separately as due to non-linear effects alone as well as to a combination of linear and non-linear mechanisms. (author)

  12. The AOLI low-order non-linear curvature wavefront sensor: laboratory and on-sky results

    Science.gov (United States)

    Crass, Jonathan; King, David; MacKay, Craig

    2014-08-01

    Many adaptive optics (AO) systems in use today require the use of bright reference objects to determine the effects of atmospheric distortions. Typically these systems use Shack-Hartmann Wavefront sensors (SHWFS) to distribute incoming light from a reference object between a large number of sub-apertures. Guyon et al. evaluated the sensitivity of several different wavefront sensing techniques and proposed the non-linear Curvature Wavefront Sensor (nlCWFS) offering improved sensitivity across a range of orders of distortion. On large ground-based telescopes this can provide nearly 100% sky coverage using natural guide stars. We present work being undertaken on the nlCWFS development for the Adaptive Optics Lucky Imager (AOLI) project. The wavefront sensor is being developed as part of a low-order adaptive optics system for use in a dedicated instrument providing an AO corrected beam to a Lucky Imaging based science detector. The nlCWFS provides a total of four reference images on two photon-counting EMCCDs for use in the wavefront reconstruction process. We present results from both laboratory work using a calibration system and the first on-sky data obtained with the nlCWFS at the 4.2 metre William Herschel Telescope, La Palma. In addition, we describe the updated optical design of the wavefront sensor, strategies for minimising intrinsic effects and methods to maximise sensitivity using photon-counting detectors. We discuss on-going work to develop the high speed reconstruction algorithm required for the nlCWFS technique. This includes strategies to implement the technique on graphics processing units (GPUs) and to minimise computing overheads to obtain a prior for a rapid convergence of the wavefront reconstruction. Finally we evaluate the sensitivity of the wavefront sensor based upon both data and low-photon count strategies.

  13. Development of nonperturbative nonlinear optics models including effects of high order nonlinearities and of free electron plasma: Maxwell–Schrödinger equations coupled with evolution equations for polarization effects, and the SFA-like nonlinear optics model

    International Nuclear Information System (INIS)

    Lorin, E; Bandrauk, A D; Lytova, M; Memarian, A

    2015-01-01

    This paper is dedicated to the exploration of non-conventional nonlinear optics models for intense and short electromagnetic fields propagating in a gas. When an intense field interacts with a gas, usual nonlinear optics models, such as cubic nonlinear Maxwell, wave and Schrödinger equations, derived by perturbation theory may become inaccurate or even irrelevant. As a consequence, and to include in particular the effect of free electrons generated by laser–molecule interaction, several heuristic models, such as UPPE, HOKE models, etc, coupled with Drude-like models [1, 2], were derived. The goal of this paper is to present alternative approaches based on non-heuristic principles. This work is in particular motivated by the on-going debate in the filamentation community, about the effect of high order nonlinearities versus plasma effects due to free electrons, in pulse defocusing occurring in laser filaments [3–9]. The motivation of our work goes beyond filamentation modeling, and is more generally related to the interaction of any external intense and (short) pulse with a gas. In this paper, two different strategies are developed. The first one is based on the derivation of an evolution equation on the polarization, in order to determine the response of the medium (polarization) subject to a short and intense electromagnetic field. Then, we derive a combined semi-heuristic model, based on Lewenstein’s strong field approximation model and the usual perturbative modeling in nonlinear optics. The proposed model allows for inclusion of high order nonlinearities as well as free electron plasma effects. (paper)

  14. The Effect of Foreign Direct Investment in Economic Growth from the Perspective of Nonlinear Dynamics

    Directory of Open Access Journals (Sweden)

    Ch. K. Volos

    2015-09-01

    Full Text Available In today’s globalized economy one of the most crucial factors for the economic growth of a country, especially of a developing country, is the foreign direct investment, not only because of the transfer of capital but also of technology. In this work, the effect of foreign direct investments in a county’s economic growth by using tools of nonlinear dynamics is studied. As a model of the economic growth of a country, a well-known nonlinear discrete-time dynamical system, the Logistic map, is used. The system under study consists of two countries with a strong economic relationship. The source country of foreign direct investments is an industrialized, economically powerful and technologically advanced country that makes significant investments in the host country, which is a developing country and strong dependent from the source country. Simulation results of system’s behavior and especially the bifurcation diagrams reveal the strong connection between the countries of the proposed system and the effect of foreign direct investments in the economic growth of the host country.

  15. Estimation of Synaptic Conductances in Presence of Nonlinear Effects Caused by Subthreshold Ionic Currents

    Directory of Open Access Journals (Sweden)

    Catalina Vich

    2017-07-01

    Full Text Available Subthreshold fluctuations in neuronal membrane potential traces contain nonlinear components, and employing nonlinear models might improve the statistical inference. We propose a new strategy to estimate synaptic conductances, which has been tested using in silico data and applied to in vivo recordings. The model is constructed to capture the nonlinearities caused by subthreshold activated currents, and the estimation procedure can discern between excitatory and inhibitory conductances using only one membrane potential trace. More precisely, we perform second order approximations of biophysical models to capture the subthreshold nonlinearities, resulting in quadratic integrate-and-fire models, and apply approximate maximum likelihood estimation where we only suppose that conductances are stationary in a 50–100 ms time window. The results show an improvement compared to existent procedures for the models tested here.

  16. Estimation of Synaptic Conductances in Presence of Nonlinear Effects Caused by Subthreshold Ionic Currents

    DEFF Research Database (Denmark)

    Vich, Catalina; Berg, Rune W.; Guillamon, Antoni

    2017-01-01

    Subthreshold fluctuations in neuronal membrane potential traces contain nonlinear components, and employing nonlinear models might improve the statistical inference. We propose a new strategy to estimate synaptic conductances, which has been tested using in silico data and applied to in vivo...... recordings. The model is constructed to capture the nonlinearities caused by subthreshold activated currents, and the estimation procedure can discern between excitatory and inhibitory conductances using only one membrane potential trace. More precisely, we perform second order approximations of biophysical...... models to capture the subthreshold nonlinearities, resulting in quadratic integrate-and-fire models, and apply approximate maximum likelihood estimation where we only suppose that conductances are stationary in a 50–100 ms time window. The results show an improvement compared to existent procedures...

  17. Effective connectivity between superior temporal gyrus and Heschl's gyrus during white noise listening: linear versus non-linear models.

    Science.gov (United States)

    Hamid, Ka; Yusoff, An; Rahman, Mza; Mohamad, M; Hamid, Aia

    2012-04-01

    This fMRI study is about modelling the effective connectivity between Heschl's gyrus (HG) and the superior temporal gyrus (STG) in human primary auditory cortices. MATERIALS #ENTITYSTARTX00026; Ten healthy male participants were required to listen to white noise stimuli during functional magnetic resonance imaging (fMRI) scans. Statistical parametric mapping (SPM) was used to generate individual and group brain activation maps. For input region determination, two intrinsic connectivity models comprising bilateral HG and STG were constructed using dynamic causal modelling (DCM). The models were estimated and inferred using DCM while Bayesian Model Selection (BMS) for group studies was used for model comparison and selection. Based on the winning model, six linear and six non-linear causal models were derived and were again estimated, inferred, and compared to obtain a model that best represents the effective connectivity between HG and the STG, balancing accuracy and complexity. Group results indicated significant asymmetrical activation (p(uncorr) Model comparison results showed strong evidence of STG as the input centre. The winning model is preferred by 6 out of 10 participants. The results were supported by BMS results for group studies with the expected posterior probability, r = 0.7830 and exceedance probability, ϕ = 0.9823. One-sample t-tests performed on connection values obtained from the winning model indicated that the valid connections for the winning model are the unidirectional parallel connections from STG to bilateral HG (p model comparison between linear and non-linear models using BMS prefers non-linear connection (r = 0.9160, ϕ = 1.000) from which the connectivity between STG and the ipsi- and contralateral HG is gated by the activity in STG itself. We are able to demonstrate that the effective connectivity between HG and STG while listening to white noise for the respective participants can be explained by a non-linear dynamic causal model with

  18. Nonlinear refractive index measurements and self-action effects in Roselle-Hibiscus Sabdariffa solutions

    Science.gov (United States)

    Henari, F. Z.; Al-Saie, A.

    2006-12-01

    We report the observation of self-action phenomena, such as self-focusing, self-defocusing, self-phase modulation and beam fanning in Roselle-Hibiscus Sabdariffa solutions. This material is found to be a new type of natural nonlinear media, and the nonlinear reflective index coefficient has been determined using a Z-scan technique and by measuring the critical power for the self-trapping effect. Z-scan measurements show that this material has a large negative nonlinear refractive index, n 2 = 1 × 10-4 esu. A comparison between the experimental n 2 values and the calculated thermal value for n 2 suggests that the major contribution to nonlinear response is of thermal origin.

  19. Threshold effect under nonlinear limitation of the intensity of high-power light

    International Nuclear Information System (INIS)

    Tereshchenko, S A; Podgaetskii, V M; Gerasimenko, A Yu; Savel'ev, M S

    2015-01-01

    A model is proposed to describe the properties of limiters of high-power laser radiation, which takes into account the threshold character of nonlinear interaction of radiation with the working medium of the limiter. The generally accepted non-threshold model is a particular case of the threshold model if the threshold radiation intensity is zero. Experimental z-scan data are used to determine the nonlinear optical characteristics of media with carbon nanotubes, polymethine and pyran dyes, zinc selenide, porphyrin-graphene and fullerene-graphene. A threshold effect of nonlinear interaction between laser radiation and some of investigated working media of limiters is revealed. It is shown that the threshold model more adequately describes experimental z-scan data. (nonlinear optical phenomena)

  20. Relativistic effects on large amplitude nonlinear Langmuir waves in a two-fluid plasma

    International Nuclear Information System (INIS)

    Nejoh, Yasunori

    1994-07-01

    Large amplitude relativistic nonlinear Langmuir waves are analyzed by the pseudo-potential method. The existence conditions for nonlinear Langmuir waves are confirmed by considering relativistic high-speed electrons in a two-fluid plasma. The significant feature of this investigation is that the propagation of nonlinear Langmuir waves depends on the ratio of the electron streaming velocity to the velocity of light, the normalized potential and the ion mass to electron mass ratio. The constant energy is determined by the specific range of the relativistic effect. In the non-relativistic limit, large amplitude relativistic Langmuir waves do not exist. The present investigation predicts new findings of large amplitude nonlinear Langmuir waves in space plasma phenomena in which relativistic electrons are important. (author)

  1. Assessing robustness of designs for random effects parameters for nonlinear mixed-effects models.

    Science.gov (United States)

    Duffull, Stephen B; Hooker, Andrew C

    2017-12-01

    Optimal designs for nonlinear models are dependent on the choice of parameter values. Various methods have been proposed to provide designs that are robust to uncertainty in the prior choice of parameter values. These methods are generally based on estimating the expectation of the determinant (or a transformation of the determinant) of the information matrix over the prior distribution of the parameter values. For high dimensional models this can be computationally challenging. For nonlinear mixed-effects models the question arises as to the importance of accounting for uncertainty in the prior value of the variances of the random effects parameters. In this work we explore the influence of the variance of the random effects parameters on the optimal design. We find that the method for approximating the expectation and variance of the likelihood is of potential importance for considering the influence of random effects. The most common approximation to the likelihood, based on a first-order Taylor series approximation, yields designs that are relatively insensitive to the prior value of the variance of the random effects parameters and under these conditions it appears to be sufficient to consider uncertainty on the fixed-effects parameters only.

  2. Effect of size and indium-composition on linear and nonlinear optical absorption of InGaN/GaN lens-shaped quantum dot

    International Nuclear Information System (INIS)

    Jbara, Ahmed S; Othaman, Zulkafli; Saeed, M A

    2016-01-01

    Based on the Schrödinger equation for envelope function in the effective mass approximation, linear and nonlinear optical absorption coefficients in a multi-subband lens quantum dot are investigated. The effects of quantum dot size on the interband and intraband transitions energy are also analyzed. The finite element method is used to calculate the eigenvalues and eigenfunctions. Strain and In-mole-fraction effects are also studied, and the results reveal that with the decrease of the In-mole fraction, the amplitudes of linear and nonlinear absorption coefficients increase. The present computed results show that the absorption coefficients of transitions between the first excited states are stronger than those of the ground states. In addition, it has been found that the quantum dot size affects the amplitudes and peak positions of linear and nonlinear absorption coefficients while the incident optical intensity strongly affects the nonlinear absorption coefficients. (paper)

  3. Nonlinear effects in the radiation force generated by amplitude-modulated focused beams

    Science.gov (United States)

    González, Nuria; Jiménez, Noé; Redondo, Javier; Roig, Bernardino; Picó, Rubén; Sánchez-Morcillo, Víctor; Konofagou, Elisa E.; Camarena, Francisco

    2012-10-01

    Harmonic Motion Imaging (HMI) uses an amplitude-modulated (AM) beam to induce an oscillatory radiation force before, during and after ablation. In this paper, the findings from a numerical analysis of the effects related with the nonlinear propagation of AM focused ultrasonic beams in water on the radiation force and the location of its maxima will be presented. The numerical modeling is performed using the KZK nonlinear parabolic equation. The radiation force is generated by a focused transducer with a gain of 18, a carrier frequency of 1 MHz and a modulation frequency of 25 kHz. The modulated excitation generates a spatially-invariant force proportional to the intensity. Regarding the nonlinear wave propagation, the force is no longer proportional to the intensity, reaching a factor of eight between the nonlinear and linear estimations. Also, a 9 mm shift in the on-axis force peak occurs when the initial pressure increased from 1 to 300 kPa. This spatial shift, due to the nonlinear effects, becomes dynamic in AM focused beams, as the different signal periods have different amplitudes. This study shows that both the value and the spatial position of the force peak are affected by the nonlinear propagation of the ultrasonic waves.

  4. Application of nonlinear rheology to assess the effect of secondary nanofiller on network structure of hybrid polymer nanocomposites

    Science.gov (United States)

    Kamkar, Milad; Aliabadian, Ehsan; Shayesteh Zeraati, Ali; Sundararaj, Uttandaraman

    2018-02-01

    Carbon nanotube (CNT)/polymer nanocomposites exhibit excellent electrical properties by forming a percolated network. Adding a secondary filler can significantly affect the CNTs' network, resulting in changing the electrical properties. In this work, we investigated the effect of adding manganese dioxide nanowires (MnO2NWs) as a secondary nanofiller on the CNTs' network structure inside a poly(vinylidene fluoride) (PVDF) matrix. Incorporating MnO2NWs to PVDF/CNT samples produced a better state of dispersion of CNTs, as corroborated by light microscopy and transmission electron microscopy. The steady shear and oscillatory shear flows were employed to obtain a better insight into the nanofiller structure and viscoelastic behavior of the nanocomposites. The transient response under steady shear flow revealed that the stress overshoot of hybrid nanocomposites (two-fillers), PVDF/CNT/MnO2NWs, increased dramatically in comparison to binary nanocomposites (single-filler), PVDF/CNT and PVDF/MnO2NWs. This can be attributed to microstructural changes. Large amplitude oscillatory shear characterization was also performed to further investigate the effect of the secondary nanofiller on the nonlinear viscoelastic behavior of the samples. The nonlinear rheological observations were explained using quantitative nonlinear parameters [strain-stiffening ratio (S) and shear-thickening ratio (T)] and Lissajous-Bowditch plots. Results indicated that a more rigid nanofiller network was formed for the hybrid nanocomposites due to the better dispersion state of CNTs and this led to a more nonlinear viscoelastic behavior.

  5. Effect of window function for measurement of ultrasonic nonlinear parameter using fast fourier transform of tone-burst signal

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyoung Jun; Kim, Jong Beom; Song, Dong Gil; Jhang, Kyung Young [Dept. of Mechanical Engineering, Hanyang University, Seoul (Korea, Republic of)

    2015-08-15

    In ultrasonic nonlinear parameter measurement using the fast Fourier transform(FFT) of tone-burst signals, the side lobe and leakage on spectrum because of finite time and non-periodicity of signals makes it difficult to measure the harmonic magnitudes accurately. The window function made it possible to resolve this problem. In this study, the effect of the Hanning and Turkey window functions on the experimental measurement of nonlinear parameters was analyzed. In addition, the effect of changes in tone burst signal number with changes in the window function on the experimental measurement was analyzed. The result for both window functions were similar and showed that they enabled reliable nonlinear parameter measurement. However, in order to restore original signal amplitude, the amplitude compensation coefficient should be considered for each window function. On a separate note, the larger number of tone bursts was advantageous for stable nonlinear parameter measurement, but this effect was more advantageous in the case of the Hanning window than the Tukey window.

  6. Nonlinear effects in the damping of third-sound pulses

    International Nuclear Information System (INIS)

    Browne, D.A.

    1984-01-01

    We show that nonlinearities in the equations of motion for a third-sound pulse in a thick superfluid film lead to the production of short-wavelength solitons. The soliton damping arises from viscous stresses in the film, rather than from coupling to thermal currents in the vapor and the substrate as in the hydrodynamic regime. These solitons are more strongly damped than a long-wavelength third-sound wave and lead to a larger attenuation of the pulse. We show that this mechanism can account for the discrepancy between attenuation calculated theoretically for the long-wavelength limit and the experimentally observed attenuation of low-amplitude third-sound pulses

  7. Nanoscale nonlinear effects in Erbium-implanted Yttrium Orthosilicate

    Energy Technology Data Exchange (ETDEWEB)

    Kukharchyk, Nadezhda, E-mail: nadezhda.kukharchyk@physik.uni-saarland.de [Experimentalphysik, Universität des Saarlandes, D-66123 Saarbrücken (Germany); Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Shvarkov, Stepan [Optoelektronische Materialien und Bauelemente, Universität Paderborn, D-33098 Padeborn (Germany); Probst, Sebastian [Quantronics group, Service de Physique de l' Etat Condense, DSM/IRAMIS/SPEC, CNRS UMR 3680, CEA-Saclay, 91191 Gif-sur-Yvette cedex (France); Xia, Kangwei [3. Physikalisches Institut, Universität Stuttgart, D-70569 Stuttgart (Germany); Becker, Hans-Werner [RUBION, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Pal, Shovon [Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); AG THz Spectroscopie und Technologie, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Markmann, Sergej [AG THz Spectroscopie und Technologie, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Kolesov, Roman; Siyushev, Petr; Wrachtrup, Jörg [3. Physikalisches Institut, Universität Stuttgart, D-70569 Stuttgart (Germany); Ludwig, Arne [Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Ustinov, Alexey V. [Physikalisches Institut, Karlsruhe Institute of Technology, D-76128 Karlsruhe (Germany); Wieck, Andreas D. [Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); and others

    2016-09-15

    Doping of substrates at desired locations is a key technology for spin-based quantum memory devices. Focused ion beam implantation is well-suited for this task due to its high spacial resolution. In this work, we investigate ion-beam implanted Erbium ensembles in Yttrium Orthosilicate crystals by means of confocal photoluminescence spectroscopy. The sample temperature and the post-implantation annealing step strongly reverberate in the properties of the implanted ions. We find that hot implantation leads to a higher activation rate of the ions. At high enough fluences, the relation between the fluence and final concentration of ions becomes non-linear. Two models are developed explaining the observed behavior.

  8. Nonlinear and hysteretic twisting effects in ocean cable laying

    International Nuclear Information System (INIS)

    Shashaty, A.J.

    1983-01-01

    Armored ocean cable unlays under the action of installation tensions and restraining moments applied by the ocean bottom and the ship's bow sheave. The process of elongation and twist is nonlinear and hysteretic. This process has often been assumed linear and reversible. The equations describing the moment which is developed in laying cable on the ocean bottom are worked out, without assuming linearity and reversibility. These equations are applied to some cases likely to arise. For a typical armored coaxial cable laid in 3700m (2,000 fathoms) depth without bottom tension, a steady-state laying-up moment of 134Nm (99 lbs. ft.) is developed. For the reversible case, no moment is developed. If the bottom tension is increased from zero to 33,375N (7500 lbs.) and then returned to zero, a peak moment of 198Nm (146 lbs. ft.) is developed

  9. Terahertz semiconductor nonlinear optics

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias

    2013-01-01

    In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz...... nonlinearity in doped semiconductors originates from the near-instantaneous heating of free electrons in the ponderomotive potential created by electric field of the THz pulse, leading to ultrafast increase of electron effective mass by intervalley scattering. Modification of effective mass in turn leads...... to a decrease of plasma frequency in semiconductor and produces a substantial modification of THz-range material dielectric function, described by the Drude model. As a result, the nonlinearity of both absorption coefficient and refractive index of the semiconductor is observed. In particular we demonstrate...

  10. Analysis of adjusting effects of mounting force on frequency conversion of mounted nonlinear optics.

    Science.gov (United States)

    Su, Ruifeng; Liu, Haitao; Liang, Yingchun; Lu, Lihua

    2014-01-10

    Motivated by the need to increase the second harmonic generation (SHG) efficiency of nonlinear optics with large apertures, a novel mounting configuration with active adjusting function on the SHG efficiency is proposed and mechanically and optically studied. The adjusting effects of the mounting force on the distortion and stress are analyzed by the finite element methods (FEM), as well as the contribution of the distortion and stress to the change in phase mismatch, and the SHG efficiency are theoretically stated. Further on, the SHG efficiency is calculated as a function of the mounting force. The changing trends of the distortion, stress, and the SHG efficiency with the varying mounting force are obtained, and the optimal ones are figured out. Moreover, the mechanism of the occurrence of the optimal values is studied and the adjusting strategy is put forward. Numerical results show the robust adjustment of the mounting force, as well as the effectiveness of the mounting configuration, in increasing the SHG efficiency.

  11. Turing instability for a competitor-competitor-mutualist model with nonlinear cross-diffusion effects

    International Nuclear Information System (INIS)

    Wen, Zijuan; Fu, Shengmao

    2016-01-01

    This paper deals with a strongly coupled reaction-diffusion system modeling a competitor-competitor-mutualist three-species model with diffusion, self-diffusion and nonlinear cross-diffusion and subject to Neumann boundary conditions. First, we establish the persistence of a corresponding reaction-diffusion system without self- and cross-diffusion. Second, the global asymptotic stability of the unique positive equilibrium for weakly coupled PDE system is established by using a comparison method. Moreover, under certain conditions about the intra- and inter-species effects, we prove that the uniform positive steady state is linearly unstable for the cross-diffusion system when one of the cross-diffusions is large enough. The results indicate that Turing instability can be driven solely from strong diffusion effect of the first species (or the second species or the third species) due to the pressure of the second species (or the first species).

  12. Single-particle And Collective Effects Of Cubic Nonlinearity In The Beam Dynamics Of Proton Synchrotrons

    CERN Document Server

    Tran Hy, J

    1998-01-01

    This thesis describes some new studies of the effects of cubic nonlinearities arising from image-charge forces and octupole magnets on the transverse beam dynamics of proton synchrotrons and storage rings, and also a study of the damping of coherent oscillations using a feed-back damper. In the latter case, various corrective algorithms were modeled using linear one-turn maps. Kicks of fixed amplitude but appropriate sign were shown to provide linear damping and no coherent tune shift, though the rate predicted analytically was somewhat higher than that observed in simulations. This algorithm gave much faster damping (for equal power) than conventional proportional kicks, which damp exponentially. Two single-particle effects of the image-change force were investigated: distortion of the momentum dispersion function and amplitude dependence of the betatron tunes (resulting in tune spread). The former is calculated using transfer maps and the method of undetermined coefficients, the latter by solving the cubic ...

  13. Stretched-exponential relaxation of the nonlinear dielectric effect in a critical binary solution

    Science.gov (United States)

    Rzoska, Sylwester J.; Górny, Michał; Zioło, Jerzy

    1991-01-01

    An experimental confirmation is given of the existence of a stretched-exponential relaxation of the form exp[-(t/τ)x] with x~=0.39 in a binary solution with an upper critical point. The nonlinear dielectric effect (NDE) method was used for this experiment. Results obtained are similar to those reported earlier by Piazza et al. [J. Opt. Soc. Am. B 3, 1642 (1986); Phys. Rev. B 38, 7223 (1988)] based on the Kerr-effect measurements in solutions with a lower critical point. Studies could be carried out in the immediate vicinity of the critical point, because the application of the NDE is not restricted by the appearance of the critical opalescence.

  14. Nonlinear Elliptic Differential Equations with Multivalued Nonlinearities

    Indian Academy of Sciences (India)

    In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities. First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is defined on all R R . Assuming the existence of an upper and of a lower ...

  15. Observation of confinement effects through liner and nonlinear absorption spectroscopy in cuprous oxide

    Science.gov (United States)

    Sekhar, H.; Rakesh Kumar, Y.; Narayana Rao, D.

    2015-02-01

    Cuprous oxide nano clusters, micro cubes and micro particles were successfully synthesized by reducing copper (II) salt with ascorbic acid in the presence of sodium hydroxide via a co-precipitation method. The X-ray diffraction studies revealed the formation of pure single phase cubic. Raman spectrum shows the inevitable presence of CuO on the surface of the Cu2O powders which may have an impact on the stability of the phase. Transmission electron microscopy (TEM) data revealed that the morphology evolves from nanoclusters to micro cubes and micro particles by increasing the concentration of NaOH. Linear optical measurements show that the absorption peak maximum shifts towards red with changing morphology from nano clusters to micro cubes and micro particles. The nonlinear optical properties were studied using open aperture Z-scan technique with 532 nm, 6 ns laser pulses. Samples exhibited saturable as well as reverse saturable absorption. The results show that the transition from SA to RSA is ascribed to excited-state absorption (ESA) induced by two-photon absorption (TPA) process. Due to confinement effects (enhanced band gap) we observed enhanced nonlinear absorption coefficient (βeff) in the case of nano-clusters compared to their micro-cubes and micro-particles.

  16. A Nonlinear Dynamics-Based Estimator for Functional Electrical Stimulation: Preliminary Results From Lower-Leg Extension Experiments.

    Science.gov (United States)

    Allen, Marcus; Zhong, Qiang; Kirsch, Nicholas; Dani, Ashwin; Clark, William W; Sharma, Nitin

    2017-12-01

    Miniature inertial measurement units (IMUs) are wearable sensors that measure limb segment or joint angles during dynamic movements. However, IMUs are generally prone to drift, external magnetic interference, and measurement noise. This paper presents a new class of nonlinear state estimation technique called state-dependent coefficient (SDC) estimation to accurately predict joint angles from IMU measurements. The SDC estimation method uses limb dynamics, instead of limb kinematics, to estimate the limb state. Importantly, the nonlinear limb dynamic model is formulated into state-dependent matrices that facilitate the estimator design without performing a Jacobian linearization. The estimation method is experimentally demonstrated to predict knee joint angle measurements during functional electrical stimulation of the quadriceps muscle. The nonlinear knee musculoskeletal model was identified through a series of experiments. The SDC estimator was then compared with an extended kalman filter (EKF), which uses a Jacobian linearization and a rotation matrix method, which uses a kinematic model instead of the dynamic model. Each estimator's performance was evaluated against the true value of the joint angle, which was measured through a rotary encoder. The experimental results showed that the SDC estimator, the rotation matrix method, and EKF had root mean square errors of 2.70°, 2.86°, and 4.42°, respectively. Our preliminary experimental results show the new estimator's advantage over the EKF method but a slight advantage over the rotation matrix method. However, the information from the dynamic model allows the SDC method to use only one IMU to measure the knee angle compared with the rotation matrix method that uses two IMUs to estimate the angle.

  17. Relativistic effects on linear and nonlinear polarizabilities studied by effective-core potential, Douglas-Kroll, and Dirac-Hartree-Fock response theory

    DEFF Research Database (Denmark)

    Norman, Patrick; Schimmelpfennig, Bernd; Ruud, Kenneth

    2002-01-01

    A systematic investigation of a hierarchy of methods for including relativistic effects in the calculation of linear and nonlinear optical properties was carried out. The simple ECP method and the more involved spin-averaged Douglas-Kroll approximation were compared to benchmark results obtained...

  18. Self-transparency effects in heterogeneous nonlinear scattering media and their possible use in lasers

    International Nuclear Information System (INIS)

    Al'tshuler, G.B.; Ermolaev, V.S.; Krylov, K.I.; Manenkov, A.A.; Prokhorov, A.M.

    1986-01-01

    Transmission of intense laser beams through heterogeneous scattering media is considered. Effects of intensity limitation, self-recovery of the wave front of a transmitted beam, and bistable reflection associated with the laser-induced self-transparency (suppression of scattering) of such media are predicted because of the compensation of the linear refractive-index difference Δn/sub L/ of the heterocomponents of a medium by nonlinear change Δn/sub N//sub L/ for different mechanisms of nonlinearity. Applications of these effects in lasers for Q switching and mode locking are discussed. The observation of self-transparency effects in several heterogeneous media (glass particles in toluene and nitrobenzene, and lead molybdenite powder) for cw Ar- and pulsed Nd- and CO 2 -laser radiation is reported. Q switching and mode locking have also been demonstrated with a YAG:Nd laser using nonlinear scattering in a heterogeneous cell as a control element in a laser resonator

  19. Estimation of non-linear effective permeability of magnetic materials with fine structure

    International Nuclear Information System (INIS)

    Waki, H.; Igarashi, H.; Honma, T.

    2006-01-01

    This paper describes a homogenization method for magnetic materials with fine structure. In this method, the structures of the magnetic materials are assumed to be periodic, and the unit cell is defined. The effective permeability is determined on the basis of magnetic energy balance in the unit cell. This method can be applied not only for linear problems but also for non-linear ones. In this paper, estimation of the effective permeability of non-linear magnetic materials by using the homogenization method is described in detail, and then the validity for the non-liner problems is tested for two-dimensional problems. It is shown that this homogenization method gives accurate non-linear effective permeability

  20. Thermal effects, creep and nonlinear responde of concrete reactor vessels

    International Nuclear Information System (INIS)

    Bazant, Z.P.

    1978-01-01

    A new mathematical model for prediction of pore pressure and moisture transfer in concrete heated well beyond 100 0 C is outlined. The salient features of the model are:(1) the hypothesis taht the pore space available to capillary water grows with increasing temperature as well as increasing pressure in excess of saturation pressure, and (2) the hypothesis that moisture permeability increases by two orders of magnitude when passing 100 0 C. Permaability below 100 0 C is controlled by migration of adsorbed water through gel-pore sized necks on passages through the material; these necks are lost above 100 0 C and viscosity then governs. The driving force of moisture transfer may be considered as the gradient of pore pressure, which is defined as pressure of vapor rather than liquid water if concrete is not saturated. Thermodynamic properties of water may be used to determine sorption isotherms in saturated concrete. The theory is the necessary first step in rationally predicting thermal stresses and deformations, and assessing the danger of explosive spalling. However, analysis of creep and nonlinear triaxial behavior is also needed for this purpose. A brief review of recent achievements in these subjects is also given. (Author)

  1. Non-linear effects in transition edge sensors for X-ray detection

    International Nuclear Information System (INIS)

    Bandler, S.R.; Figueroa-Feliciano, E.; Iyomoto, N.; Kelley, R.L.; Kilbourne, C.A.; Murphy, K.D.; Porter, F.S.; Saab, T.; Sadleir, J.

    2006-01-01

    In a microcalorimeter that uses a transition-edge sensor to detect energy depositions, the small signal energy resolution improves with decreasing heat capacity. This improvement remains true up to the point where non-linear and saturation effects become significant. This happens when the energy deposition causes a significant change in the sensor resistance. Not only does the signal size become a non-linear function of the energy deposited, but also the noise becomes non-stationary over the duration of the pulse. Algorithms have been developed that can calculate the optimal performance given this non-linear behavior that typically requires significant processing and calibration work-both of which are impractical for space missions. We have investigated the relative importance of the various non-linear effects, with the hope that a computationally simple transformation can overcome the largest of the non-linear and non-stationary effects, producing a highly linear 'gain' for pulse-height versus energy, and close to the best energy resolution at all energies when using a Wiener filter

  2. Measuring of nonlinearity of dye doped liquid crystals using of self phase modulation effect

    International Nuclear Information System (INIS)

    Abedi, M.; Jafari, A.; Tajalli, H.

    2007-01-01

    Self phase modulation in dye doped liquid crystals has investigated and the nonlinearity of dye doped liquid crystals is measured by this effect. The Self phase modulation effect can be used for producing optical micro rings that have many applications in photonics and laser industries.

  3. Using strong nonlinearity and high-frequency vibrations to control effective properties of discrete elastic waveguides

    DEFF Research Database (Denmark)

    Lazarov, Boyan Stefanov; Thomsen, Jon Juel; Snaeland, Sveinn Orri

    2008-01-01

    The aim of this article is to investigate how highfrequency (HF) excitation, combined with strong nonlinear elastic material behavior, influences the effective material or structural properties for low-frequency excitation and wave propagation. The HF effects are demonstrated on discrete linear s...

  4. Characterization of nonlinear effects in a two-dimensional dielectric elastomer actuator

    International Nuclear Information System (INIS)

    Jhong, Y; Mikolas, D; Fu, C; Yeh, T; Fang, W; Shaw, D; Chen, J

    2010-01-01

    Dielectric elastomer actuators (DEAs) possess great potential for the realization of lightweight and inexpensive multiple-degrees-of-freedom (multi-DOF) biomimetic robotics. In this study, a two-dimensional DEA was built and tested in order to characterize the issues associated with the use in multi-DOF actuation. The actuator is a single circular DEA film with four, electrically isolated quadrant electrode areas. The actuator was driven in a quasi-circular manner by applying sine and cosine signals to orthogonal pairs of electrodes, and the resultant motion was recorded using image processing techniques. The effects of nonlinear voltage–strain behavior, creep and stress relaxation on the motion were all pronounced and clearly differentiated. A simple six-parameter empirical model was used and showed excellent agreement with the measured data

  5. Nonlinear effects in optical pumping of a cold and slow atomic beam

    KAUST Repository

    Porfido, N.

    2015-10-12

    By photoionizing hyperfine (HF) levels of the Cs state 62P3/2 in a slow and cold atom beam, we find how their population depends on the excitation laser power. The long time (around 180μs) spent by the slow atoms inside the resonant laser beam is large enough to enable exploration of a unique atom-light interaction regime heavily affected by time-dependent optical pumping. We demonstrate that, under such conditions, the onset of nonlinear effects in the population dynamics and optical pumping occurs at excitation laser intensities much smaller than the conventional respective saturation values. The evolution of population within the HF structure is calculated by numerical integration of the multilevel optical Bloch equations. The agreement between numerical results and experiment outcomes is excellent. All main features in the experimental findings are explained by the occurrence of “dark” and “bright” resonances leading to power-dependent branching coefficients.

  6. Electromagnetic effects on the self-modulation of nonlinear lower hybrid waves

    International Nuclear Information System (INIS)

    Hsu, P.; Kuehl, H.H.

    1983-01-01

    Electromagnetic effects on the self-modulation of nonlinear lower hybrid waves in an inhomogeneous plasma are studied for both broad and narrow spectrum excitations. For broad spectrum excitation, the complex modified Korteweg--de Vries equation is modified by two additional terms due to the electromagnetic correction and inhomogeneity. Numerical solutions of this equation for typical tokamak parameters show that these terms suppress soliton formation. For narrow spectrum excitation, the electromagnetic correction produces an additional dispersive term in the differential equation governing the wave envelope. This term opposes thermal dispersion, resulting in significant self-modulation. Numerical solutions show constriction and splitting of the envelope as well as spreading of the Fourier spectrum

  7. The effect of nonlinear propagation on heating of tissue: A numerical model of diagnostic ultrasound beams

    Science.gov (United States)

    Cahill, Mark D.; Humphrey, Victor F.; Doody, Claire

    2000-07-01

    Thermal safety indices for diagnostic ultrasound beams are calculated under the assumption that the sound propagates under linear conditions. A non-axisymmetric finite difference model is used to solve the KZK equation, and so to model the beam of a diagnostic scanner in pulsed Doppler mode. Beams from both a uniform focused rectangular source and a linear array are considered. Calculations are performed in water, and in attenuating media with tissue-like characteristics. Attenuating media are found to exhibit significant nonlinear effects for finite-amplitude beams. The resulting loss of intensity by the beam is then used as the source term in a model of tissue heating to estimate the maximum temperature rises. These are compared with the thermal indices, derived from the properties of the water-propagated beams.

  8. Effects of plasma current on nonlinear interactions of ITG turbulence, zonal flows and geodesic acoustic modes

    International Nuclear Information System (INIS)

    Angelino, P; Bottino, A; Hatzky, R; Jolliet, S; Sauter, O; Tran, T M; Villard, L

    2006-01-01

    The mutual interactions of ion temperature gradient (ITG) driven modes, zonal flows and geodesic acoustic modes (GAM) in tokamak plasmas are investigated using a global nonlinear gyrokinetic formulation with totally unconstrained evolution of temperature gradient and profile. A series of numerical simulations with the same initial temperature and density profile specifications is performed using a sequence of ideal MHD equilibria differing only in the value of the total plasma current, in particular with identical magnetic shear profiles and shapes of magnetic surfaces. On top of a bursty or quasi-steady state behaviour the zonal flows oscillate at the GAM frequency. The amplitude of these oscillations increases with the value of the safety factor q, resulting in a less effective suppression of ITG turbulence by zonal flows at a lower plasma current. The turbulence-driven volume-averaged radial heat transport is found to scale inversely with the total plasma current

  9. The effect of nonlinear forces on coherently oscillating space-charge-dominated beams

    International Nuclear Information System (INIS)

    Celata, C.M.

    1987-03-01

    A particle-in-cell computer simulation code has been used to study the transverse dynamics of nonrelativistic misaligned space-charge-dominated coasting beams in an alternating gradient focusing channel. In the presence of nonlinear forces due to dodecapole or octupole imperfections of the focusing fields or to image forces, the transverse rms emittance grows in a beat pattern. Analysis indicates that this emittance dilution is due to the driving of coherent modes of the beam near their resonant frequencies by the nonlinear force. The effects of the dodecapole and images forces can be made to effectively cancel for some boundary conditions, but the mechanism is not understood at this time

  10. Nonlinear damage effect in graphene synthesis by C-cluster ion implantation

    International Nuclear Information System (INIS)

    Zhang Rui; Zhang Zaodi; Wang Zesong; Wang Shixu; Wang Wei; Fu Dejun; Liu Jiarui

    2012-01-01

    We present few-layer graphene synthesis by negative carbon cluster ion implantation with C 1 , C 2 , and C 4 at energies below 20 keV. The small C-clusters were produced by a source of negative ion by cesium sputtering with medium beam current. We show that the nonlinear effect in cluster-induced damage is favorable for graphene precipitation compared with monomer carbon ions. The nonlinear damage effect in cluster ion implantation shows positive impact on disorder reduction, film uniformity, and the surface smoothness in graphene synthesis.

  11. Nonlinear simulations of particle source effects on edge localized mode

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J.; Tang, C. J. [College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Chen, S. Y., E-mail: sychen531@163.com [College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Southwestern Institute of Physics, Chengdu 610041 (China); Wang, Z. H. [Southwestern Institute of Physics, Chengdu 610041 (China)

    2015-12-15

    The effects of particle source (PS) with different intensities and located positions on Edge Localized Mode (ELM) are systematically studied with BOUT++ code. The results show the ELM size strongly decreases with increasing the PS intensity once the PS is located in the middle or bottom of the pedestal. The effects of PS on ELM depend on the located position of PS. When it is located at the top of the pedestal, peeling-ballooning (P-B) modes can extract more free energy from the pressure gradient and grow up to be a large filament at the initial crash phase and the broadening of mode spectrum can be suppressed by PS, which leads to more energy loss. When it is located in the middle or bottom of the pedestal, the extraction of free energy by P-B modes can be suppressed, and a small filament is generated. During the turbulence transport phase, the broader mode spectrum suppresses the turbulence transport when PS is located in the middle, while the zonal flow plays an important role in damping the turbulence transport when PS is located at the bottom.

  12. Single nano-hole as a new effective nonlinear element for third-harmonic generation

    International Nuclear Information System (INIS)

    Melentiev, P N; Konstantinova, T V; Afanasiev, A E; Balykin, V I; Kuzin, A A; Baturin, A S; Tausenev, A V; Konyaschenko, A V

    2013-01-01

    In this letter, we report on a particularly strong optical nonlinearity at the nanometer scale in aluminum. A strong optical nonlinearity of the third order was demonstrated on a single nanoslit. Single nanoslits of different aspect ratio were excited by a laser pulse (120 fs) at the wavelength 1.5 μm, leading predominantly to third-harmonic generation (THG). It has been shown that strong surface plasmon resonance in a nanoslit allows the realization of an effective nanolocalized source of third-harmonic radiation. We show also that a nanoslit in a metal film has a significant advantage in nonlinear processes over its Babinet complementary nanostructure (nanorod): the effective abstraction of heat in a film with a slit makes it possible to use much higher laser radiation intensities. (letter)

  13. Single nano-hole as a new effective nonlinear element for third-harmonic generation

    Science.gov (United States)

    Melentiev, P. N.; Konstantinova, T. V.; Afanasiev, A. E.; Kuzin, A. A.; Baturin, A. S.; Tausenev, A. V.; Konyaschenko, A. V.; Balykin, V. I.

    2013-07-01

    In this letter, we report on a particularly strong optical nonlinearity at the nanometer scale in aluminum. A strong optical nonlinearity of the third order was demonstrated on a single nanoslit. Single nanoslits of different aspect ratio were excited by a laser pulse (120 fs) at the wavelength 1.5 μm, leading predominantly to third-harmonic generation (THG). It has been shown that strong surface plasmon resonance in a nanoslit allows the realization of an effective nanolocalized source of third-harmonic radiation. We show also that a nanoslit in a metal film has a significant advantage in nonlinear processes over its Babinet complementary nanostructure (nanorod): the effective abstraction of heat in a film with a slit makes it possible to use much higher laser radiation intensities.

  14. Nonlinear Delta-f Particle Simulations of Collective Effects in High-Intensity Bunched Beams

    CERN Document Server

    Qin, Hong; Hudson, Stuart R; Startsev, Edward

    2005-01-01

    The collective effects in high-intensity 3D bunched beams are described self-consistently by the nonlinear Vlasov-Maxwell equations.* The nonlinear delta-f method,** a particle simulation method for solving the nonlinear Vlasov-Maxwell equations, is being used to study the collective effects in high-intensity 3D bunched beams. The delta-f method, as a nonlinear perturbative scheme, splits the distribution function into equilibrium and perturbed parts. The perturbed distribution function is represented as a weighted summation over discrete particles, where the particle orbits are advanced by equations of motion in the focusing field and self-consistent fields, and the particle weights are advanced by the coupling between the perturbed fields and the zero-order distribution function. The nonlinear delta-f method exhibits minimal noise and accuracy problems in comparison with standard particle-in-cell simulations. A self-consistent 3D kinetic equilibrium is first established for high intensity bunched beams. The...

  15. Joint nonlinearity effects in the design of a flexible truss structure control system

    Science.gov (United States)

    Mercadal, Mathieu

    1986-01-01

    Nonlinear effects are introduced in the dynamics of large space truss structures by the connecting joints which are designed with rather important tolerances to facilitate the assembly of the structures in space. The purpose was to develop means to investigate the nonlinear dynamics of the structures, particularly the limit cycles that might occur when active control is applied to the structures. An analytical method was sought and derived to predict the occurrence of limit cycles and to determine their stability. This method is mainly based on the quasi-linearization of every joint using describing functions. This approach was proven successful when simple dynamical systems were tested. Its applicability to larger systems depends on the amount of computations it requires, and estimates of the computational task tend to indicate that the number of individual sources of nonlinearity should be limited. Alternate analytical approaches, which do not account for every single nonlinearity, or the simulation of a simplified model of the dynamical system should, therefore, be investigated to determine a more effective way to predict limit cycles in large dynamical systems with an important number of distributed nonlinearities.

  16. Optimization of piezoelectric cantilever energy harvesters including non-linear effects

    International Nuclear Information System (INIS)

    Patel, R; McWilliam, S; Popov, A A

    2014-01-01

    This paper proposes a versatile non-linear model for predicting piezoelectric energy harvester performance. The presented model includes (i) material non-linearity, for both substrate and piezoelectric layers, and (ii) geometric non-linearity incorporated by assuming inextensibility and accurately representing beam curvature. The addition of a sub-model, which utilizes the transfer matrix method to predict eigenfrequencies and eigenvectors for segmented beams, allows for accurate optimization of piezoelectric layer coverage. A validation of the overall theoretical model is performed through experimental testing on both uniform and non-uniform samples manufactured in-house. For the harvester composition used in this work, the magnitude of material non-linearity exhibited by the piezoelectric layer is 35 times greater than that of the substrate layer. It is also observed that material non-linearity, responsible for reductions in resonant frequency with increases in base acceleration, is dominant over geometric non-linearity for standard piezoelectric harvesting devices. Finally, over the tested range, energy loss due to damping is found to increase in a quasi-linear fashion with base acceleration. During an optimization study on piezoelectric layer coverage, results from the developed model were compared with those from a linear model. Unbiased comparisons between harvesters were realized by using devices with identical natural frequencies—created by adjusting the device substrate thickness. Results from three studies, each with a different assumption on mechanical damping variations, are presented. Findings showed that, depending on damping variation, a non-linear model is essential for such optimization studies with each model predicting vastly differing optimum configurations. (paper)

  17. Controller Design of Complex System Based on Nonlinear Strength

    Directory of Open Access Journals (Sweden)

    Rongjun Mu

    2015-01-01

    Full Text Available This paper presents a new idea of controller design for complex systems. The nonlinearity index method was first developed for error propagation of nonlinear system. The nonlinearity indices access the boundary between the strong and the weak nonlinearities of the system model. The algorithm of nonlinearity index according to engineering application is first proposed in this paper. Applying this method on nonlinear systems is an effective way to measure the nonlinear strength of dynamics model over the full flight envelope. The nonlinearity indices access the boundary between the strong and the weak nonlinearities of system model. According to the different nonlinear strength of dynamical model, the control system is designed. The simulation time of dynamical complex system is selected by the maximum value of dynamic nonlinearity indices. Take a missile as example; dynamical system and control characteristic of missile are simulated. The simulation results show that the method is correct and appropriate.

  18. Effects of non-linearity of material properties on the coupled mechanical-hydraulic-thermal behavior in rock mass

    International Nuclear Information System (INIS)

    Kobayashi, Akira; Ohnishi, Yuzo

    1986-01-01

    The nonlinearity of material properties used in the coupled mechanical-hydraulic-thermal analysis is investigated from the past literatures. Some nonlinearity that is respectively effective for the system is introduced into our computer code for analysis such a coupling problem by using finite element method. And the effects of nonlinearity of each material property on the coupled behavior in rock mass are examined for simple model and Stripa project model with the computer code. (author)

  19. Size effects in non-linear heat conduction with flux-limited behaviors

    Science.gov (United States)

    Li, Shu-Nan; Cao, Bing-Yang

    2017-11-01

    Size effects are discussed for several non-linear heat conduction models with flux-limited behaviors, including the phonon hydrodynamic, Lagrange multiplier, hierarchy moment, nonlinear phonon hydrodynamic, tempered diffusion, thermon gas and generalized nonlinear models. For the phonon hydrodynamic, Lagrange multiplier and tempered diffusion models, heat flux will not exist in problems with sufficiently small scale. The existence of heat flux needs the sizes of heat conduction larger than their corresponding critical sizes, which are determined by the physical properties and boundary temperatures. The critical sizes can be regarded as the theoretical limits of the applicable ranges for these non-linear heat conduction models with flux-limited behaviors. For sufficiently small scale heat conduction, the phonon hydrodynamic and Lagrange multiplier models can also predict the theoretical possibility of violating the second law and multiplicity. Comparisons are also made between these non-Fourier models and non-linear Fourier heat conduction in the type of fast diffusion, which can also predict flux-limited behaviors.

  20. Nonlinear optics

    CERN Document Server

    Boyd, Robert W

    2013-01-01

    Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q

  1. Nonlinear Acoustic Waves Generated by Surface Disturbances and Their Effects on Lower Thermospheric Composition

    Science.gov (United States)

    Pineyro, B.; Snively, J. B.

    2017-12-01

    Recent 1D and 2D nonlinear atmospheric models have provided important insight into acoustic waves generated by seismic events, which may steepen into shocks or saw-tooth trains while also dissipating strongly in the thermosphere [e.g., Chum et al., JGR, 121, 2016; Zettergren et al., JGR, 122, 2017]. Although they have yield results that agree with with observations of ionospheric perturbations, dynamical models for the diffusive and stratified lower thermosphere [e.g., Snively and Pasko, JGR, 113, 2008] often use single gas approximations with height-dependent physical properties (e.g. mean molecular weight, specific heats) that do not vary with time (fixed composition). This approximation is simpler and less computationally expensive than a true multi-fluid model, yet captures the important physical transition between molecular and atomic gases in the lower thermosphere. Models with time-dependent composition and properties have been shown to outperform commonly used models with fixed properties; these time-dependent effects have been included in a one-gas model by adding an advection equation for the molecular weight, finding closer agreement to a true binary-gas model [Walterscheid and Hickey, JGR, 106, 2001 and JGR, 117, 2012]. Here, a one-dimensional nonlinear mass fraction approach to multi-constituent gas modeling, motivated by the results of Walterscheid and Hickey [2001, 2012], is presented. The finite volume method of Bale et al. [SIAM JSC, 24, 2002] is implemented in Clawpack [http://www.clawpack.org; LeVeque, 2002] with a Riemann Solver to solve the Euler Equations including multiple species, defined by their mass fractions, as they undergo advection. Viscous dissipation and thermal conduction are applied via a fractional step method. The model is validated with shock tube problems for two species, and then applied to investigate propagating nonlinear acoustic waves from ground to thermosphere, such as following the 2011 Tohoku Earthquake [e

  2. Day of the week effect on the Zimbabwe Stock Exchange: A non-linear GARCH analysis

    Directory of Open Access Journals (Sweden)

    Batsirai Winmore Mazviona

    2015-11-01

    Full Text Available This study analysed the day of the week effect on the Zimbabwe Stock Exchange (ZSE by taking into account volatility of returns. The purpose of the study was to establish whether daily mean returns across a trading week differ from each other. We employ a non-linear approach in modelling the day of the week effects. In particular, we used the Generalised Autoregressive Conditional Heteroscedasticity (GARCH and the Exponential GARCH (EGARCH models. We used industrial and mining daily closing indices data from 19 February 2009 to 31 December 2013. The data was retrieved from the ZSE website. EViews 7 software was utilised for data analysis. In order to test the null hypothesis of equality of daily mean returns, a Wald test was carried out. The Wald F-statistic rejected the null hypothesis of equality of mean returns for the industrial index. We found the traditional negative Monday and positive Friday effect for the industrial index in GARCH (1,1 and EGARCH (1,1 models. The GARCH (1,1 detected a negative Friday effect and the EGARCH (1,1 detected negative Wednesday effect for the mining index. We found evidence of model dependency for the mining index results.

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

    International Nuclear Information System (INIS)

    Seshadri, S.R.

    1976-01-01

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

  4. Influence of nonlinear effects on the neutral gas transport in tokamaks

    International Nuclear Information System (INIS)

    Behringer, T.

    1992-06-01

    The linear Monte Carlo computer code EIRENE for calculation of free molecular flow of neutral gases through a background plasma has been extended to the non-linear transition flow regime (Knudsen number 0.1-10). Motivation arose from higher gas densities in the range of 10 13 -10 15 cm -3 appearing in the srape-off layer and in parts of the vacuum system of advanced tokamak experiments. To treat the problem, the Direct Monte Carlo Simulation Method after Bird, a kinetic approach, was chosen, since the conditions for application of continuum theory are not met. First results with the extended code were obtained in calculating the conductance of plasma-free short cylindrical ducts and elbows. A steady increase in conductance with decreasing Knudsen number was found, which is in good agreement with experimental data. Further calculations for transition flows through fixed background plasmas were made. In these, solutions obtained were represented as differences from solutions obtained by linear calculations. Simulation of a 1-D plasma slab configuration (related to the gaseous divertor concept) revealed markedly varying neutral gas profiles due to neutral-neutral collisions. In addition, in these runs neutral-neutral inelastic collision processes turned out to be negligible. Finally, neutral gas behaviour at higher densities in pump limiter geometries was studied, related to experiments on the tokamak TEXTOR. An increase in conductance in the direction to the pumps of up to 25% relative to linear results was found. Recently obtained experimental data on the impact of non-linear neutral effects upon conductance could be confirmed. (orig.) [de

  5. Beam-beam interaction and Pacman effects in the SSC with random nonlinear multipoles

    International Nuclear Information System (INIS)

    Goderre, G.P.; Ohnuma, S.

    1988-01-01

    In order to find the combined effects of beam-beam interaction (head-on and long-range) and random nonlinear multipoles in dipole magnets, transverse tunes and smears have been calculated as a function of oscillation amplitudes. Two types of particles, ''regular'' and ''Pacman,'' have been investigated using a modified version of tracking code TEAPOT. Regular particles experience beam-beam interactions in all four interaction regions (IR's), both head-on and long range, while pacman particles interact with bunches of the other beam in one medium-beta and one low-beta IR's only. The model for the beam-beam interaction is of weak-strong type and the strong beam is assumed to have a round Gaussian charge distribution. Furthermore, it is assumed that the vertical closed orbit deviation arising from the finite crossing angle of 70 μrad is perfectly compensated for regular particles. The same compensation applied to pacman particles creates a closed orbit distortion. Linear tunes are adjusted for regular particles to the design values but there are no nonlinear corrections except for chromaticity correcting sextupoles in two families. Results obtained in this study do not show any reduction of dynamic or linear aperture for pacman particles but some doubts exist regarding the validity of defining the linear aperture from the smear alone. Preliminary results are given for regular particles when (Δp/p) is modulated by the synchrotron oscillation. For these, fifty oscillations corresponding to 26,350 revolutions have been tracked. A very slow increase in the horizontal amplitude, /approximately/4 /times/ 10/sup /minus/4//oscillation (relative), is a possibility but this should be confirmed by trackings of larger number of revolutions. 11 refs., 18 figs., 2 tabs

  6. Effects of nonlinear phase modulation on Bragg scattering in the low-conversion regime

    DEFF Research Database (Denmark)

    Andersen, Lasse Mejling; Cargill, D. S.; McKinstrie, C. J.

    2012-01-01

    In this paper, we consider the effects of nonlinear phase modulation on frequency conversion by four-wave mixing (Bragg scattering) in the low-conversion regime. We derive the Green functions for this process using the time-domain collision method, for partial collisions, in which the four fields...... interact at the beginning or the end of the fiber, and complete collisions, in which the four fields interact at the midpoint of the fiber. If the Green function is separable, there is only one output Schmidt mode, which is free from temporal entanglement. We find that nonlinear phase modulation always...... chirps the input and output Schmidt modes and renders the Green function formally nonseparable. However, by pre-chirping the pumps, one can reduce the chirps of the Schmidt modes and enable approximate separability. Thus, even in the presence of nonlinear phase modulation, frequency conversion...

  7. Probing Anderson localization of light by weak non-linear effects

    International Nuclear Information System (INIS)

    Sperling, T; Bührer, W; Maret, G; Ackermann, M; Aegerter, C M

    2014-01-01

    Breakdown of wave transport due to strong disorder is a universal phenomenon known as Anderson localization (AL). It occurs because of the macroscopic population of reciprocal multiple scattering paths, which in three dimensional systems happens at a critical scattering strength. Intensities on these random loops should thus be highly increased relative to those of a diffusive sample. In order to highlight localized modes of light, we exploit the optical nonlinearities of TiO 2 . Power dependent and spectrally resolved time of flight distribution measurements in transmission through slabs of TiO 2 powders at various turbidities reveal that mostly long loops are affected by nonlinearities and that the deviations from diffusive transport observed at long times are due to these localized modes. Our data are a first step in the experimental investigation of the interplay between nonlinear effects and AL in 3D. (fast track communication)

  8. Effects of Exponential Nonlinear Electrodynamics and External Magnetic Field on Holographic Superconductors

    Science.gov (United States)

    Sheykhi, A.; Abdollahzadeh, Z.

    2018-03-01

    We investigate the effects of an external magnetic field as well as exponential nonlinear electrodynamics on the properties of s-wave holographic superconductors. Our strategy for this study is the matching method, which is based on the match of the solutions near the horizon and on the boundary at some intermediate point. When the magnetic field is turned off, we obtain the critical temperature as well as the condensation operator and show that the critical exponent is still 1/2, which is the universal value in the mean field theory. Then, we turn on the magnetic field and obtain the critical magnetic field, B c , in order to study its behavior in terms of the temperature. Interestingly enough, we find that in the presence of exponential nonlinear electrodynamics, the critical temperature decreases, while the critical magnetic field increases compared to the Maxwell case. We also observe that the critical magnetic field increases with increasing the nonlinear parameter b.

  9. Nonlinear dynamic effects in a two-wave CO2 laser

    International Nuclear Information System (INIS)

    Gorobets, V A; Kozlov, K V; Kuntsevich, B F; Petukhov, V O

    1999-01-01

    Theoretical and experimental investigations were made of nonlinear dynamic regimes of the operation of a two-wave CO 2 laser with cw excitation in an electric discharge and loss modulation in one of the channels. Nonlinear amplitude - frequency characteristics of each of the laser channels have two low-frequency resonance spikes, associated with forced linear oscillations of two coupled oscillators, and high-frequency spikes, corresponding to doubling of the period of the output radiation oscillations. At low loss-modulation frequencies the intensity oscillations of the output radiation in the coupled channels are in antiphase, whereas at high modulation frequencies the dynamics is cophasal. Nonlinear dynamic effects, such as doubling of the period and of the repetition frequency of the pulses and chaotic oscillations of the output radiation intensity, are observed for certain system parameters. (control of laser radiation parameters)

  10. Effects of heat exchange and nonlinearity on acoustic streaming in a vibrating cylindrical cavity.

    Science.gov (United States)

    Gubaidullin, Amir A; Yakovenko, Anna V

    2015-06-01

    Acoustic streaming in a gas filled cylindrical cavity subjected to the vibration effect is investigated numerically. Both thermally insulated walls and constant temperature walls are considered. The range of vibration frequencies from low frequencies, at which the process can be described by an approximate analytical solution, to high frequencies giving rise to strong nonlinear effects is studied. Frequencies lower than the resonant one are chosen, and nonlinearity is achieved due to the large amplitude. The problem is solved in an axisymmetric statement. The dependence of acoustic streaming in narrow channels at vibration frequencies lower than the resonant one on the type of thermal boundary conditions is shown. The streaming vortices' directions of rotation in the case of constant temperature walls are found to be opposite to those in the case of thermally insulated walls. Different nonlinear effects, which increase with the frequency of vibration, are obtained. Nonlinear effects manifesting as the nonuniformity of average temperature, pressure, and density are in turn found to be influencing the streaming velocity and streaming structure.

  11. Application of perturbation theory to the non-linear vibration analysis of a string including the bending moment effects

    International Nuclear Information System (INIS)

    Esmaeilzadeh Khadem, S.; Rezaee, M.

    2001-01-01

    In this paper the large amplitude and non-linear vibration of a string is considered. The initial tension, lateral vibration amplitude, diameter and the modulus of elasticity of the string have main effects on its natural frequencies. Increasing the lateral vibration amplitude makes the assumption of constant initial tension invalid. In this case, therefore, it is impossible to use the classical equation of string with small amplitude transverse motion assumption. On the other hand, by increasing the string diameter, the bending moment effect will increase dramatically, and acts as an impressive restoring moment. Considering the effects of the bending moments, the nonlinear equation governing the large amplitude transverse vibration of a string is derived. The time dependent portion of the governing equation has the from of Duff ing equation is solved using the perturbation theory. The results of the analysis are shown in appropriate graphs, and the natural frequencies of the string due to the non-linear factors are compared with the natural frequencies of the linear vibration os a string without bending moment effects

  12. The effects of relativistic and non-local non-linearities on modulational instabilities in non-uniform plasma

    International Nuclear Information System (INIS)

    Mohamed, B.F.; El-Shorbagy, Kh.H.

    2000-01-01

    A general detailed analysis for the nonlinear generation of localized fields due to the existence of a strong pump field inside the non-uniform plasma has been considered. We have taken into account the effects of relativistic and non-local nonlinearities on the structure of plasma resonance region. The nonlinear Schrodinger equation described the localized fields are investigated. Besides, the generalized dispersion relation is obtained to study the modulational instabilities in different cases. Keywords: Wave-plasma interaction, Nonlinear effects, Modulation instabilities

  13. Comparison of the effect of annular and solid electron beams on linear and nonlinear traveling wave tube

    Directory of Open Access Journals (Sweden)

    F. Sheykhe

    Full Text Available The present paper, compares the effect of the annular and solid electron beam on the efficiency of linear and nonlinear TWTs. To do this, first we introduce four different geometric structure of the beam-helix. Then, we calculate the output power of each structure, in linear and nonlinear modes, at different frequencies using the numerical solution of the mathematical equations of the multi-frequency Eulerian model. Now, plot the output power in terms of distance for each structure at different frequencies and compare them. In a linear tube, the effect of annular beams on the output power is better than the solid beam, while this affects the frequency in nonlinear tubes. It is shown that in linear regime the power increase linearly with frequency but for nonlinear regimes is nonlinear. Keywords: Annular beam, Solid beam, Circuit power, Nonlinear, Traveling wave tube, Helix

  14. Thermal stratification effects on MHD radiative flow of nanofluid over nonlinear stretching sheet with variable thickness

    Directory of Open Access Journals (Sweden)

    Yahaya Shagaiya Daniel

    2018-04-01

    Full Text Available The combined effects of thermal stratification, applied electric and magnetic fields, thermal radiation, viscous dissipation and Joules heating are numerically studied on a boundary layer flow of electrical conducting nanofluid over a nonlinearly stretching sheet with variable thickness. The governing equations which are partial differential equations are converted to a couple of ordinary differential equations with suitable similarity transformation techniques and are solved using implicit finite difference scheme. The electrical conducting nanofluid particle fraction on the boundary is passively rather than actively controlled. The effects of the emerging parameters on the electrical conducting nanofluid velocity, temperature, and nanoparticles concentration volume fraction with skin friction, heat transfer characteristics are examined with the aids of graphs and tabular form. It is observed that the variable thickness enhances the fluid velocity, temperature, and nanoparticle concentration volume fraction. The heat and mass transfer rate at the surface increases with thermal stratification resulting to a reduction in the fluid temperature. Electric field enhances the nanofluid velocity which resolved the sticking effects caused by a magnetic field which suppressed the profiles. Radiative heat transfer and viscous dissipation are sensitive to an increase in the fluid temperature and thicker thermal boundary layer thickness. Comparison with published results is examined and presented. Keywords: MHD nanofluid, Variable thickness, Thermal radiation, Similarity solution, Thermal stratification

  15. Effect of temperature on the structural, linear, and nonlinear optical properties of MgO-doped graphene oxide nanocomposites

    Directory of Open Access Journals (Sweden)

    Kimiagar Salimeh

    2018-01-01

    Full Text Available Magnesium oxide (MgO-graphene oxide (GO nanocomposites were prepared by the hydrothermal method at different temperatures. The effect of growth temperature on the structural, linear, and nonlinear optical (NLO parameters was investigated. The decoration of MgO on GO sheets was confirmed by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and UV-visible (UV-vis spectroscopy analyses. The energy band-gaps of MgO-GO nanocomposites were calculated from UV-vis spectrum using Tauc plot. The NLO parameters of MgO-GO nanocomposites were calculated for the first time by the simple Z-scan technique with nanosecond Nd:YAG laser at 532 nm. The nonlinear absorption coefficient β and nonlinear refractive index n2 for MgO-GO nanocomposites at the laser intensity of 1.1×108 W/cm2 were measured to be in the order of 10−7 cm/W and 10−12 cm2/W, respectively. The third-order NLO susceptibility of MgO-GO nanocomposites was measured in the order of 10−9 esu. The results showed that MgO-GO structures have negative nonlinearity as well as good nonlinear two-photon absorption at 532 nm. Furthermore, the NLO parameters increased by the enhancement of the growth temperature. As the investigation of new materials plays an important role in the advancement of optoelectronics, MgO-GO nanocomposites possess potential applications in NLO devices.

  16. Nonlinear Model of Pseudoelastic Shape Memory Alloy Damper Considering Residual Martensite Strain Effect

    Directory of Open Access Journals (Sweden)

    Y. M. Parulekar

    2012-01-01

    Full Text Available Recently, there has been increasing interest in using superelastic shape memory alloys for applications in seismic resistant-design. Shape memory alloys (SMAs have a unique property by which they can recover their original shape after experiencing large strains up to 8% either by heating (shape memory effect or removing stress (pseudoelastic effect. Many simplified shape memory alloy models are suggested in the past literature for capturing the pseudoelastic response of SMAs in passive vibration control of structures. Most of these models do not consider the cyclic effects of SMA's and resulting residual martensite deformation. Therefore, a suitable constitutive model of shape memory alloy damper which represents the nonlinear hysterical dynamic system appropriately is essential. In this paper a multilinear hysteretic model incorporating residual martensite strain effect of pseudoelastic shape memory alloy damper is developed and experimentally validated using SMA wire, based damper device. A sensitivity analysis is done using the proposed model along with three other simplified SMA models. The models are implemented on a steel frame representing an SDOF system and the comparison of seismic response of structure with all the models is made in the numerical study.

  17. Experimental and theoretical studies of spectral alteration in ultrasonic waves resulting from nonlinear elastic response in rock

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, P.A.; McCall, K.R.; Meegan, G.D. Jr. [Los Alamos National Lab., NM (United States)

    1993-11-01

    Experiments in rock show a large nonlinear elastic wave response, far greater than that of gases, liquids and most other solids. The large response is attributed to structural defects in rock including microcracks and grain boundaries. In the earth, a large nonlinear response may be responsible for significant spectral alteration at amplitudes and distances currently considered to be well within the linear elastic regime.

  18. Experimental and theoretical studies of spectral alteration in ultrasonic waves resulting from nonlinear elastic response in rock

    International Nuclear Information System (INIS)

    Johnson, P.A.; McCall, K.R.; Meegan, G.D. Jr.

    1993-01-01

    Experiments in rock show a large nonlinear elastic wave response, far greater than that of gases, liquids and most other solids. The large response is attributed to structural defects in rock including microcracks and grain boundaries. In the earth, a large nonlinear response may be responsible for significant spectral alteration at amplitudes and distances currently considered to be well within the linear elastic regime

  19. Effect of temperature and pressure on non-linear conduction in GeTeSe chalcogenide glass

    International Nuclear Information System (INIS)

    El-Mansy, M.K.

    1998-01-01

    The I-V characteristic curves were studied in the temperature range 301-359 K and pressure range up to 7.15 x 10 9 Pa which illustrate a non-linear behaviour below (high-resistance region) and beyond (negative-resistance region) a breakdown point characterising Ge 27 Te 62 Se 11 chalcogenide glasses. The general behaviour is shifted towards lower voltage and higher current when the ambient temperature and/or the applied pressure were increased. The non-linear behaviour in the pre breakdown region is discussed according to the Poole-Frenkel field emission of electrons from deep traps located at a depth equal to 0.372eV. The analysis of the effect of field on the non-linear conduction in Ge 27 Te 62 Se 11 chalcogenide glass suggests a modification of the energy difference between filled and empty sites, where the effect of pressure suggests a reduction of the energy gap width. The analysis based on simple thermal effects in the region closer to the breakdown point implies the electrothermal process initiating the negative resistance region. The results of post breakdown region (negative-resistance region) imply the electron hopping between filled and empty localised states at Fermi level. The density of localised states is estimated which lies in the range 5.7 x 10 16 -1.84 x 10 18 cm -3 /eV

  20. The relative effects of cavitation and nonlinear ultrasound propagation on HIFU lesion dynamics in a tissue phantom

    Science.gov (United States)

    Khokhlova, Vera A.; Bailey, Michael R.; Reed, Justin; Kaczkowski, Peter J.

    2004-05-01

    The relative importance of the effects of acoustic nonlinearity and cavitation in HIFU lesion production is studied experimentally and theoretically in a polyacrylamide gel. A 2-MHz transducer of 40-mm diameter and 45-mm focal length was operated at different regimes of power, and in cw or duty-cycle regimes with equal mean intensity. Elevated static pressure was applied to suppress bubbles, increase boiling temperature, and thus to isolate the effect of acoustic nonlinearity in the enhancement of lesion production. Experimental data were compared with the results of simulations performed using a KZK acoustic model combined with the bioheat equation and thermal dose formulation. Boiling and the typical tadpole-shaped lesion shifting towards the transducer were observed under standard atmospheric pressure. No boiling was detected and a symmetric thermal lesion formed in the case of overpressure. A delay in lesion inception time was registered with overpressure, which was hypothesized to be due to suppressed microbubble dynamics. The effect of acoustic nonlinearity was revealed as a substantial decrease in the lesion inception time and an increase in the lesion size for high-amplitude waves under both standard and overpressure conditions. [Work supported by ONRIFO, NASA/NSBRI, NIH Fogarty, and CRDF grants.

  1. Problems in nonlinear acoustics: Scattering of sound by sound, parametric receiving arrays, nonlinear effects in asymmetric sound beams and pulsed finite amplitude sound beams

    Science.gov (United States)

    Hamilton, Mark F.

    1989-08-01

    Four projects are discussed in this annual summary report, all of which involve basic research in nonlinear acoustics: Scattering of Sound by Sound, a theoretical study of two nonconlinear Gaussian beams which interact to produce sum and difference frequency sound; Parametric Receiving Arrays, a theoretical study of parametric reception in a reverberant environment; Nonlinear Effects in Asymmetric Sound Beams, a numerical study of two dimensional finite amplitude sound fields; and Pulsed Finite Amplitude Sound Beams, a numerical time domain solution of the KZK equation.

  2. Nonlinear effects in low-dimensional magnetism: Solitons and vortices

    International Nuclear Information System (INIS)

    Bishop, A.R.; Kawabata, C.; Mertens, F.G.; Wysin, G.M.

    1987-07-01

    The report outlines recent results on the dynamics of easy-plane classical ferromagnetic spin in two spatial dimensions emphasising possible signatures of unbound vortices above the Kosterlitz-Thouless topological phase transition. 18 refs, 1 fig

  3. EFFECTS OF THE NEUTRINO MASS SPLITTING ON THE NONLINEAR MATTER POWER SPECTRUM

    International Nuclear Information System (INIS)

    Wagner, Christian; Verde, Licia; Jimenez, Raul

    2012-01-01

    We have performed cosmological N-body simulations which include the effect of the masses of the individual neutrino species. The simulations were aimed at studying the effect of different neutrino hierarchies on the matter power spectrum. Compared to the linear theory predictions, we find that nonlinearities enhance the effect of hierarchy on the matter power spectrum at mildly nonlinear scales. The maximum difference between the different hierarchies is about 0.5% for a sum of neutrino masses of 0.1 eV. Albeit this is a small effect, it is potentially measurable from upcoming surveys. In combination with neutrinoless double-β decay experiments, this opens up the possibility of using the sky to determine if neutrinos are Majorana or Dirac fermions.

  4. Isogeometric analysis of free-form Timoshenko curved beams including the nonlinear effects of large deformations

    Science.gov (United States)

    Hosseini, Seyed Farhad; Hashemian, Ali; Moetakef-Imani, Behnam; Hadidimoud, Saied

    2018-03-01

    In the present paper, the isogeometric analysis (IGA) of free-form planar curved beams is formulated based on the nonlinear Timoshenko beam theory to investigate the large deformation of beams with variable curvature. Based on the isoparametric concept, the shape functions of the field variables (displacement and rotation) in a finite element analysis are considered to be the same as the non-uniform rational basis spline (NURBS) basis functions defining the geometry. The validity of the presented formulation is tested in five case studies covering a wide range of engineering curved structures including from straight and constant curvature to variable curvature beams. The nonlinear deformation results obtained by the presented method are compared to well-established benchmark examples and also compared to the results of linear and nonlinear finite element analyses. As the nonlinear load-deflection behavior of Timoshenko beams is the main topic of this article, the results strongly show the applicability of the IGA method to the large deformation analysis of free-form curved beams. Finally, it is interesting to notice that, until very recently, the large deformations analysis of free-form Timoshenko curved beams has not been considered in IGA by researchers.

  5. Isotopic effects on non-linearity, molecular radius and intermolecular ...

    Indian Academy of Sciences (India)

    water is used in nuclear reactors and is about to become an important fuel analog for possible control of thermonuclear processes. Various physicochemical proper- .... This results in the fact that in the region of standard thermodynamic temperature, the replacement of hydrogen by deuterium either hardly changes the.

  6. Model for predicting non-linear crack growth considering load sequence effects (LOSEQ)

    International Nuclear Information System (INIS)

    Fuehring, H.

    1982-01-01

    A new analytical model for predicting non-linear crack growth is presented which takes into account the retardation as well as the acceleration effects due to irregular loading. It considers not only the maximum peak of a load sequence to effect crack growth but also all other loads of the history according to a generalised memory criterion. Comparisons between crack growth predicted by using the LOSEQ-programme and experimentally observed data are presented. (orig.) [de

  7. The hair-trigger effect for a class of nonlocal nonlinear equations

    Science.gov (United States)

    Finkelshtein, Dmitri; Tkachov, Pasha

    2018-06-01

    We prove the hair-trigger effect for a class of nonlocal nonlinear evolution equations on which have only two constant stationary solutions, 0 and . The effect consists in that the solution with an initial condition non identical to zero converges (when time goes to ) to θ locally uniformly in . We also find sufficient conditions for existence, uniqueness and comparison principle in the considered equations.

  8. Self-consistency and coherent effects in nonlinear resonances

    International Nuclear Information System (INIS)

    Hofmann, I.; Franchetti, G.; Qiang, J.; Ryne, R. D.

    2003-01-01

    The influence of space charge on emittance growth is studied in simulations of a coasting beam exposed to a strong octupolar perturbation in an otherwise linear lattice, and under stationary parameters. We explore the importance of self-consistency by comparing results with a non-self-consistent model, where the space charge electric field is kept 'frozen-in' to its initial values. For Gaussian distribution functions we find that the 'frozen-in' model results in a good approximation of the self-consistent model, hence coherent response is practically absent and the emittance growth is self-limiting due to space charge de-tuning. For KV or waterbag distributions, instead, strong coherent response is found, which we explain in terms of absence of Landau damping

  9. Nonlinear frequency compression: effects on sound quality ratings of speech and music.

    Science.gov (United States)

    Parsa, Vijay; Scollie, Susan; Glista, Danielle; Seelisch, Andreas

    2013-03-01

    Frequency lowering technologies offer an alternative amplification solution for severe to profound high frequency hearing losses. While frequency lowering technologies may improve audibility of high frequency sounds, the very nature of this processing can affect the perceived sound quality. This article reports the results from two studies that investigated the impact of a nonlinear frequency compression (NFC) algorithm on perceived sound quality. In the first study, the cutoff frequency and compression ratio parameters of the NFC algorithm were varied, and their effect on the speech quality was measured subjectively with 12 normal hearing adults, 12 normal hearing children, 13 hearing impaired adults, and 9 hearing impaired children. In the second study, 12 normal hearing and 8 hearing impaired adult listeners rated the quality of speech in quiet, speech in noise, and music after processing with a different set of NFC parameters. Results showed that the cutoff frequency parameter had more impact on sound quality ratings than the compression ratio, and that the hearing impaired adults were more tolerant to increased frequency compression than normal hearing adults. No statistically significant differences were found in the sound quality ratings of speech-in-noise and music stimuli processed through various NFC settings by hearing impaired listeners. These findings suggest that there may be an acceptable range of NFC settings for hearing impaired individuals where sound quality is not adversely affected. These results may assist an Audiologist in clinical NFC hearing aid fittings for achieving a balance between high frequency audibility and sound quality.

  10. Hydrostatic pressure and temperature effects on nonlinear optical rectification in a lens shape InAs/GaAs quantum dot

    International Nuclear Information System (INIS)

    Bouzaïene, L.; Ben Mahrsia, R.; Baira, M.; Sfaxi, L.; Maaref, H.

    2013-01-01

    We have performed theoretical calculation of the nonlinear optical rectification in a lens shape InAs/GaAs quantum dot (0D). The combined effects of hydrostatic pressure and temperature on the nonlinear optical rectification in lens-shaped InAs QDs are studied under the compact density matrix formalism and the effective mass approximation. From our calculation, it is found that the subband energies and optical rectification susceptibility are quite sensitive to the applied hydrostatic pressure and temperature. The results show that the resonant peak of the optical rectification can be red-shifted or blue-shifted and their intensity also varied by external probes such as hydrostatic pressure and temperature. In addition, the oscillator strength is strongly affected by these parameters. - Highlights: ► Theoretical calculation of the nonlinear optical rectification in a lens shape InAs/GaAs quantum dot was performed. ► Optical rectification susceptibility is quite sensitive to the applied hydrostatic pressure and temperature. ► The oscillator strength is strongly affected by the applied hydrostatic pressure and temperature.

  11. A multivariate nonlinear mixed effects method for analyzing energy partitioning in growing pigs

    DEFF Research Database (Denmark)

    Strathe, Anders Bjerring; Danfær, Allan Christian; Chwalibog, André

    2010-01-01

    to the multivariate nonlinear regression model because the MNLME method accounted for correlated errors associated with PD and LD measurements and could also include the random effect of animal. It is recommended that multivariate models used to quantify energy metabolism in growing pigs should account for animal......Simultaneous equations have become increasingly popular for describing the effects of nutrition on the utilization of ME for protein (PD) and lipid deposition (LD) in animals. The study developed a multivariate nonlinear mixed effects (MNLME) framework and compared it with an alternative method...... for estimating parameters in simultaneous equations that described energy metabolism in growing pigs, and then proposed new PD and LD equations. The general statistical framework was implemented in the NLMIXED procedure in SAS. Alternative PD and LD equations were also developed, which assumed...

  12. Optical authentication based on moiré effect of nonlinear gratings in phase space

    International Nuclear Information System (INIS)

    Liao, Meihua; He, Wenqi; Wu, Jiachen; Lu, Dajiang; Liu, Xiaoli; Peng, Xiang

    2015-01-01

    An optical authentication scheme based on the moiré effect of nonlinear gratings in phase space is proposed. According to the phase function relationship of the moiré effect in phase space, an arbitrary authentication image can be encoded into two nonlinear gratings which serve as the authentication lock (AL) and the authentication key (AK). The AL is stored in the authentication system while the AK is assigned to the authorized user. The authentication procedure can be performed using an optoelectronic approach, while the design process is accomplished by a digital approach. Furthermore, this optical authentication scheme can be extended for multiple users with different security levels. The proposed scheme can not only verify the legality of a user identity, but can also discriminate and control the security levels of legal users. Theoretical analysis and simulation experiments are provided to verify the feasibility and effectiveness of the proposed scheme. (paper)

  13. Nonlinear effects on Turing patterns: Time oscillations and chaos

    KAUST Repository

    Aragón, J. L.

    2012-08-08

    We show that a model reaction-diffusion system with two species in a monostable regime and over a large region of parameter space produces Turing patterns coexisting with a limit cycle which cannot be discerned from the linear analysis. As a consequence, the patterns oscillate in time. When varying a single parameter, a series of bifurcations leads to period doubling, quasiperiodic, and chaotic oscillations without modifying the underlying Turing pattern. A Ruelle-Takens-Newhouse route to chaos is identified. We also examine the Turing conditions for obtaining a diffusion-driven instability and show that the patterns obtained are not necessarily stationary for certain values of the diffusion coefficients. These results demonstrate the limitations of the linear analysis for reaction-diffusion systems. © 2012 American Physical Society.

  14. Nonlinear effect of climate on plague during the third pandemic in China

    Science.gov (United States)

    Xu, Lei; Liu, Qiyong; Stige, Leif Chr.; Ben Ari, Tamara; Fang, Xiye; Chan, Kung-Sik; Wang, Shuchun; Stenseth, Nils Chr.; Zhang, Zhibin

    2011-01-01

    Over the years, plague has caused a large number of deaths worldwide and subsequently changed history, not the least during the period of the Black Death. Of the three plague pandemics, the third is believed to have originated in China. Using the spatial and temporal human plague records in China from 1850 to 1964, we investigated the association of human plague intensity (plague cases per year) with proxy data on climate condition (specifically an index for dryness/wetness). Our modeling analysis demonstrates that the responses of plague intensity to dry/wet conditions were different in northern and southern China. In northern China, plague intensity generally increased when wetness increased, for both the current and the previous year, except for low intensity during extremely wet conditions in the current year (reflecting a dome-shaped response to current-year dryness/wetness). In southern China, plague intensity generally decreased when wetness increased, except for high intensity during extremely wet conditions of the current year. These opposite effects are likely related to the different climates and rodent communities in the two parts of China: In northern China (arid climate), rodents are expected to respond positively to high precipitation, whereas in southern China (humid climate), high precipitation is likely to have a negative effect. Our results suggest that associations between human plague intensity and precipitation are nonlinear: positive in dry conditions, but negative in wet conditions. PMID:21646523

  15. Nonlinear mixed effects modelling approach in investigating phenobarbital pharmacokinetic interactions in epileptic patients.

    Science.gov (United States)

    Vučićević, Katarina; Jovanović, Marija; Golubović, Bojana; Kovačević, Sandra Vezmar; Miljković, Branislava; Martinović, Žarko; Prostran, Milica

    2015-02-01

    The present study aimed to establish population pharmacokinetic model for phenobarbital (PB), examining and quantifying the magnitude of PB interactions with other antiepileptic drugs concomitantly used and to demonstrate its use for individualization of PB dosing regimen in adult epileptic patients. In total 205 PB concentrations were obtained during routine clinical monitoring of 136 adult epilepsy patients. PB steady state concentrations were measured by homogeneous enzyme immunoassay. Nonlinear mixed effects modelling (NONMEM) was applied for data analyses and evaluation of the final model. According to the final population model, significant determinant of apparent PB clearance (CL/F) was daily dose of concomitantly given valproic acid (VPA). Typical value of PB CL/F for final model was estimated at 0.314 l/h. Based on the final model, co-therapy with usual VPA dose of 1000 mg/day, resulted in PB CL/F average decrease of about 25 %, while 2000 mg/day leads to an average 50 % decrease in PB CL/F. Developed population PB model may be used in estimating individual CL/F for adult epileptic patients and could be applied for individualizing dosing regimen taking into account dose-dependent effect of concomitantly given VPA.

  16. Characterization of a viscoelastic heterogeneous object with an effective model by nonlinear full waveform inversion

    Science.gov (United States)

    Mesgouez, A.

    2018-05-01

    The determination of equivalent viscoelastic properties of heterogeneous objects remains challenging in various scientific fields such as (geo)mechanics, geophysics or biomechanics. The present investigation addresses the issue of the identification of effective constitutive properties of a binary object by using a nonlinear and full waveform inversion scheme. The inversion process, without any regularization technique or a priori information, aims at minimizing directly the discrepancy between the full waveform responses of a bi-material viscoelastic cylindrical object and its corresponding effective homogeneous object. It involves the retrieval of five constitutive equivalent parameters. Numerical simulations are performed in a laboratory-scale two-dimensional configuration: a transient acoustic plane wave impacts the object and the diffracted fluid pressure, solid stress or velocity component fields are determined using a semi-analytical approach. Results show that the retrieval of the density and of the real parts of both the compressional and the shear wave velocities have been carried out successfully regarding the number and location of sensors, the type of sensors, the size of the searching space, the frequency range of the incident plane pressure wave, and the change in the geometric or mechanical constitution of the bi-material object. The retrieval of the imaginary parts of the wave velocities can reveal in some cases the limitations of the proposed approach.

  17. The effect of sheared axial flow on nonlinear Z-pinch dynamics

    International Nuclear Information System (INIS)

    Kassapakis, N.

    2000-01-01

    A two dimensional Eulerian fluid code has been used to study three problems related to Z-pinch and laser produced plasmas. a) The nonlinear evolution of a localised m=0 MHD mode neck is studied in order to extract some scaling laws for the size and form of the artificial neck. We examine whether the ubiquitous m=0 instability could be beneficially used to assist in the formation of a transient localised dense plasma. The results obtained were in satisfactory agreement with experiments and other theoretical work where available. b) The development of the m=0 instability on a Z-pinch although beneficial in the previous case, is detrimental from a stability point of view and thus to the utilisation of the device as a fusion reactor by itself. This is because the timescales of the instability development are faster than the confinement time needed for fusion to occur. Sheared axial flow is a proposed mechanism for the non-linear saturation of this particular instability. Indeed the linear growth rate also can be substantially reduced. It is hoped that it can inhibit the growth of the instabilities or at least delay their development sufficiently for fusion to take place. The numerical study of the effect of sheared axial flow on the nonlinear dynamics of the Z-pinch carried out, demonstrates that sheared flow with velocity u z z >4 Alfven speed other modes, of the Kelvin-Helmholtz type, are excited which take over from the fastest growing mode in the static case. c) The expansion of the ablated plasma in laser-solid interactions is an important phenomenon for a plethora of reasons one of which is ICF. The simulations were in direct agreement with previous experimental work regarding the bulk properties of the ablation surface. They also provided justification for some assumptions made during the analysis of the observations and helped to confirm the calibration of the diagnostics timewise. The most striking feature of the experiments, namely the density dip on the

  18. Effect of pulse width on near-infrared supercontinuum generation in nonlinear fiber amplifier

    Science.gov (United States)

    Song, Rui; Lei, Cheng-Min; Chen, Sheng-Ping; Wang, Ze-Feng; Hou, Jing

    2015-08-01

    The effect of pulse width on near-infrared supercontinuum generation in nonlinear fiber amplifier is investigated theoretically and experimentally. The complex Ginzburg-Landau equation and adaptive split-step Fourier method are used to simulate the propagation of pulses with different pulse widths in the fiber amplifier, and the results show that a longer pulse is more profitable in near-infrared supercontinuum generation if the central wavelength of the input laser lies in the normal dispersion region of the gain fiber. A four-stage master oscillator power amplifier configuration is adopted and the output spectra under picosecond and nanosecond input pulses are compared with each other. The experimental results are in good accordance with the simulations which can provide some guidance for further optimization of the system. Project supported by the National Natural Science Foundation of China (Grant Nos. 11404404 and 11274385) and the Outstanding Youth Fund Project of Hunan Province and the Fund of Innovation of National University of Defense Technology, China (Grant No. B120701).

  19. Macroeconomic effects on mortality revealed by panel analysis with nonlinear trends.

    Science.gov (United States)

    Ionides, Edward L; Wang, Zhen; Tapia Granados, José A

    2013-10-03

    Many investigations have used panel methods to study the relationships between fluctuations in economic activity and mortality. A broad consensus has emerged on the overall procyclical nature of mortality: perhaps counter-intuitively, mortality typically rises above its trend during expansions. This consensus has been tarnished by inconsistent reports on the specific age groups and mortality causes involved. We show that these inconsistencies result, in part, from the trend specifications used in previous panel models. Standard econometric panel analysis involves fitting regression models using ordinary least squares, employing standard errors which are robust to temporal autocorrelation. The model specifications include a fixed effect, and possibly a linear trend, for each time series in the panel. We propose alternative methodology based on nonlinear detrending. Applying our methodology on data for the 50 US states from 1980 to 2006, we obtain more precise and consistent results than previous studies. We find procyclical mortality in all age groups. We find clear procyclical mortality due to respiratory disease and traffic injuries. Predominantly procyclical cardiovascular disease mortality and countercyclical suicide are subject to substantial state-to-state variation. Neither cancer nor homicide have significant macroeconomic association.

  20. Nonlinear effects contributing to hand-stopping tones in a horn.

    Science.gov (United States)

    Ebihara, Takayasu; Yoshikawa, Shigeru

    2013-05-01

    Hand stopping is a technique for playing the French horn while closing the bell relatively tightly using the right hand. The resulting timbre is called "penetrating" and "metallic." The effect of hand stopping on the horn input impedance has been studied, but the tone quality has hardly ever been considered. In the present paper, the dominant physical cause of the stopped-tone quality is discussed in detail. Numerical calculations of the transmission function of the stopped-horn model and the measurements of both sound pressure and wall vibration in hand stopping are carried out. They strongly suggest that the metallicness of the stopped tone is characterized by the generation of higher harmonics extending over 10 kHz due to the rapidly corrugating waveform and that the associated wall vibration on the bell may be responsible for this higher harmonic generation. However, excitation experiments and immobilization experiments performed to elucidate the relationship between sound radiation and wall vibration deny their correlation. Instead, the measurement result of the mouthpiece pressure in hand stopping suggests that minute wave corrugations peculiar to the metallic stopped tones are probably formed by nonlinear sound propagation along the bore.

  1. The effect of nonlinearity in CO2 heating rates on the attribution of stratospheric ozone and temperature changes

    Directory of Open Access Journals (Sweden)

    T. G. Shepherd

    2009-11-01

    Full Text Available An analysis of the attribution of past and future changes in stratospheric ozone and temperature to anthropogenic forcings is presented. The analysis is an extension of the study of Shepherd and Jonsson (2008 who analyzed chemistry-climate simulations from the Canadian Middle Atmosphere Model (CMAM and attributed both past and future changes to changes in the external forcings, i.e. the abundances of ozone-depleting substances (ODS and well-mixed greenhouse gases. The current study is based on a new CMAM dataset and includes two important changes. First, we account for the nonlinear radiative response to changes in CO2. It is shown that over centennial time scales the radiative response in the upper stratosphere to CO2 changes is significantly nonlinear and that failure to account for this effect leads to a significant error in the attribution. To our knowledge this nonlinearity has not been considered before in attribution analysis, including multiple linear regression studies. For the regression analysis presented here the nonlinearity was taken into account by using CO2 heating rate, rather than CO2 abundance, as the explanatory variable. This approach yields considerable corrections to the results of the previous study and can be recommended to other researchers. Second, an error in the way the CO2 forcing changes are implemented in the CMAM was corrected, which significantly affects the results for the recent past. As the radiation scheme, based on Fomichev et al. (1998, is used in several other models we provide some description of the problem and how it was fixed.

  2. Ground Based Experiments in Support of Microgravity Research Results-Vapor Growth of Organic Nonlinear Optical Thin Film

    Science.gov (United States)

    Zugrav, M. Ittu; Carswell, William E.; Haulenbeek, Glen B.; Wessling, Francis C.

    2001-01-01

    This work is specifically focused on explaining previous results obtained for the crystal growth of an organic material in a reduced gravity environment. On STS-59, in April 1994, two experiments were conducted with N,N-dimethyl-p-(2,2-dicyanovinyl) aniline (DCVA), a promising nonlinear optical (NLO) material. The space experiments were set to reproduce laboratory experiments that yielded small, bulk crystals of DCVA. The results of the flight experiment, however, were surprising. Rather than producing a bulk single crystal, the result was the production of two high quality, single crystalline thin films. This result was even more intriguing when it is considered that thin films are more desirable for NLO applications than are bulk single crystals. Repeated attempts on the ground to reproduce these results were fruitless. A second set of flight experiments was conducted on STS-69 in September 1995. This time eight DCVA experiments were flown, with each of seven experiments containing a slight change from the first reference experiment. The reference experiment was programmed with growth conditions identical to those of the STS-59 mission. The slight variations in each of the other seven were an attempt to understand what particular parameter was responsible for the preference of thin film growth over bulk crystal growth in microgravity. Once again the results were surprising. In all eight cases thin films were grown again, albeit with varying quality. So now we were faced with a phenomenon that not only takes place in microgravity, but also is very robust, resisting all attempts to force the growth of bulk single crystals.

  3. Effects produced by oscillations applied to nonlinear dynamic systems: a general approach and examples

    DEFF Research Database (Denmark)

    Blekhman, I. I.; Sorokin, V. S.

    2016-01-01

    A general approach to study effects produced by oscillations applied to nonlinear dynamic systems is developed. It implies a transition from initial governing equations of motion to much more simple equations describing only the main slow component of motions (the vibro-transformed dynamics.......g., the requirement for the involved nonlinearities to be weak. The approach is illustrated by several relevant examples from various fields of science, e.g., mechanics, physics, chemistry and biophysics....... equations). The approach is named as the oscillatory strobodynamics, since motions are perceived as under a stroboscopic light. The vibro-transformed dynamics equations comprise terms that capture the averaged effect of oscillations. The method of direct separation of motions appears to be an efficient...

  4. Wave transmission in nonlinear lattices

    International Nuclear Information System (INIS)

    Hennig, D.; Tsironis, G.P.

    1999-01-01

    The interplay of nonlinearity with lattice discreteness leads to phenomena and propagation properties quite distinct from those appearing in continuous nonlinear systems. For a large variety of condensed matter and optics applications the continuous wave approximation is not appropriate. In the present review we discuss wave transmission properties in one dimensional nonlinear lattices. Our paradigmatic equations are discrete nonlinear Schroedinger equations and their study is done through a dynamical systems approach. We focus on stationary wave properties and utilize well known results from the theory of dynamical systems to investigate various aspects of wave transmission and wave localization. We analyze in detail the more general dynamical system corresponding to the equation that interpolates between the non-integrable discrete nonlinear Schroedinger equation and the integrable Albowitz-Ladik equation. We utilize this analysis in a nonlinear Kronig-Penney model and investigate transmission and band modification properties. We discuss the modifications that are effected through an electric field and the nonlinear Wannier-Stark localization effects that are induced. Several applications are described, such as polarons in one dimensional lattices, semiconductor superlattices and one dimensional nonlinear photonic band gap systems. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  5. Nonlinear Effects in Transformation Optics-Based Metamaterial Shields for Counter Directed Energy Weapon Defense

    Science.gov (United States)

    2016-06-01

    employs the in- variance of the Maxwell equations under coordinate transformations to convert the free- space wave solutions in a coordinate... ENERGY WEAPON DEFENSE by Jacob D. Thompson June 2016 Thesis Co-Advisors: James Luscombe Brett Borden Approved for public release; distribution is...2014 to 06-17-2016 4. TITLE AND SUBTITLE NONLINEAR EFFECTS IN TRANSFORMATION OPTICS-BASED METAMATE- RIAL SHIELDS FOR COUNTER DIRECTED ENERGY WEAPON

  6. Effects of Nonlinear Absorption in BK7 and Color Glasses at 355 nm

    International Nuclear Information System (INIS)

    Adams, J J; McCarville, T; Bruere, J; McElroy, J; Peterson, J

    2003-01-01

    We have demonstrated a simple experimental technique that can be used to measure the nonlinear absorption coefficients in glasses. We determine BK7, UG1, and UG11 glasses to have linear absorption coefficients of 0.0217 ± 10% cm -1 , 1.7 ± 10% cm -1 , and 0.82 ± 10% cm -1 , respectively, two-photon absorption cross-sections of 0.025 ± 20% cm/GW, 0.035 ± 20% cm/GW, and 0.047 ± 20% cm/GW, respectively, excited-state absorption cross-sections of 8.0 x 10 -18 ± 20% cm 2 , 2.8 x 10 -16 ± 20% cm 2 , and 5 x 10 -17 ± 20% cm 2 , respectively, and solarization coefficients of 8.5 x 10 -20 ± 20% cm 2 , 2.5 x 10 -18 ± 20% cm 2 , and 1.3 x 10 -19 ± 20% cm 2 , respectively. For our application, nonlinear effects in 10-cm of BK7 are small ((le) 2%) for 355-nm fluences 2 for flat-top pulses. However, nonlinear effects are noticeable for 355-nm fluences at 0.8 J/cm 2 . In particular, we determine a 20% increase in the instantaneous absorption from linear, a solarization rate of 4% per 100 shots, and a 10% temporal droop introduced in the pulse, for 355-nm flat-top pulses at a fluence of 0.8 J/cm 2 . For 0.5-cm of UG1 absorbing glass the non-linear absorption has a similar effect as that from 10-cm of BK7 on the pulse shape; however, the effects in UG11 are much smaller

  7. Toroidal effects on the non-linearly saturated m = 1 island in tokamaks

    International Nuclear Information System (INIS)

    Avinash, K.; Haas, F.A.; Thyagaraja, A.

    1990-01-01

    This paper investigates the influence of toroidal effects (due to the coupling of various poloidal harmonics) on the non-linear saturation of the m=1 island. Bounds are obtained relating the aspect ratio, the shear at the q=1 surface and the saturated island width. Provided these bounds are satisfied, then we find that the cylindrical m=1 island theory is valid for toroidal geometry. (author)

  8. Testing nonlinear electrodynamics in waveguides: the effect of magnetostatic fields on the transmitted power

    Energy Technology Data Exchange (ETDEWEB)

    Ferraro, Rafael, E-mail: ferraro@iafe.uba.a [Instituto de AstronomIa y Fisica del Espacio, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina); Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina)

    2010-05-14

    In Born-Infeld theory and other nonlinear electrodynamics, the presence of a magnetostatic field modifies the dispersion relation and the energy velocity of waves propagating in a hollow waveguide. As a consequence, the transmitted power along a waveguide suffers slight changes when a magnetostatic field is switched on and off. This tiny effect could be better tested by operating the waveguide at a frequency close to the cutoff frequency.

  9. Testing nonlinear electrodynamics in waveguides: the effect of magnetostatic fields on the transmitted power

    International Nuclear Information System (INIS)

    Ferraro, Rafael

    2010-01-01

    In Born-Infeld theory and other nonlinear electrodynamics, the presence of a magnetostatic field modifies the dispersion relation and the energy velocity of waves propagating in a hollow waveguide. As a consequence, the transmitted power along a waveguide suffers slight changes when a magnetostatic field is switched on and off. This tiny effect could be better tested by operating the waveguide at a frequency close to the cutoff frequency.

  10. Influence of nonlinear effects on the development of Rayleigh-Taylor instability of F layer

    International Nuclear Information System (INIS)

    Kolesnikov, A.F.; Krivorutskij, Eh.N.

    1989-01-01

    Within the framework of weak turbulence in the approximation of accidental phases the influence of different nonlinear effects on the level and anisotropy of the F layer inhomogeneities is considered. To describe the F layer plasma, approximation of two-liquid hydrodynamics is used. The inertia of electrons and ions, as well as temperature inhomogeneity are neglected. The considered processes are assumed to be isothermal

  11. A Nonlinear Mixed Effects Model for the Prediction of Natural Gas Consumption by Individual Customers

    Czech Academy of Sciences Publication Activity Database

    Brabec, Marek; Konár, Ondřej; Pelikán, Emil; Malý, Marek

    2008-01-01

    Roč. 24, č. 4 (2008), s. 659-678 ISSN 0169-2070 R&D Projects: GA AV ČR 1ET400300513 Institutional research plan: CEZ:AV0Z10300504 Keywords : individual gas consumption * nonlinear mixed effects model * ARIMAX * ARX * generalized linear mixed model * conditional modeling Subject RIV: JE - Non-nuclear Energetics, Energy Consumption ; Use Impact factor: 1.685, year: 2008

  12. Approximate effective nonlinear coefficient of second-harmonic generation in KTiOPO(4).

    Science.gov (United States)

    Asaumi, K

    1993-10-20

    A simplified approximate expression for the effective nonlinear coefficient of type-II second-harmonicgeneration in KTiOPO(4) was obtained by observing that the difference between the refractive indices n(x) and n(y) is 1 order of magnitude smaller than the difference between n(z) and n(y) (or n(x)). The agreement of this approximate equation with the true definition is good, with a maximum discrepancy of 4%.

  13. Nonlinear optical rectification in vertically coupled InAs/GaAs quantum dots under electromagnetic fields, pressure and temperature effects

    Energy Technology Data Exchange (ETDEWEB)

    Choubani, M., E-mail: mohsenchoubani3@yahoo.fr; Ben Mahrsia, R.; Bouzaiene, L.; Maaref, H.

    2013-12-15

    In this paper we explore the effects of the structural dimensions, applied electromagnetic fields, hydrostatic pressure and temperature on the nonlinear optical rectification (NOR) in Vertically Coupled InAs/GaAs Quantum Dots (VCQDs). The analytical expression of the NOR is analyzed by using the density matrix formalism, the effective mass and the Finite Difference Method (FDM). Obtained results show that the NOR obtained with this coupled system is not a monotonic function of the barrier width, electromagnetic fields, pressure and temperature. Also, calculated results reveal that the resonant peaks of the NOR can be blue-shifted or red-shifted energies depending on the energy of the lowest confined states in the VCQDs structure. In addition, this condition can be controlled by changes in the structural dimensions and the external proofs mentioned above. -- Highlights: • In this paper we explore the effects of the barrier width, applied electromagnetic fields, hydrostatic pressure and temperature on the nonlinear optical rectification (NOR) in Vertically Coupled InAs/GaAs Quantum Dots (VCQDs). • The calculated results reveal that the resonant peaks of the NOR can be blue-shifted to large photon energies or red-shifted to lower photon energies. • In this paper, all parameters: electromagnetic fields, pressure and temperature effects are introduced and investigated. • The resonant energy and the magnitude of the NOR are controlled and adjusted.

  14. Vacuum nonlinear electrodynamic polarization effects in hard emission of pulsars and magnetars

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, V.I.; Sokolov, V.A.; Svertilov, S.I., E-mail: vid.msu@yandex.ru, E-mail: sokolov.sev@inbox.ru, E-mail: sis@coronas.ru [Physics Department, Moscow State University, Moscow (Russian Federation)

    2017-09-01

    The nonlinear electrodynamics influence of pulsar magnetic field on the electromagnetic pulse polarization is discussed from the point of observation interpretation. The calculations of pulsar magnetic field impact on the electromagnetic pulse polarization are made in such a way to make it easier to interpret these effects in space experiments. The law of hard emission pulse propagation in the pulsar magnetic field according to the vacuum (nonlinear electrodynamics is obtained. It has been shown, that due to the birefringence in the vacuum the front part of any hard emission pulse coming from a pulsar should be linearly polarized and the rest of pulse can have arbitrary polarization. The observational possibilities of vacuum birefringence are discussed. In this paper we give the estimations of detector parameters such as effective area, exposure time and necessity of polarization measurements with high accuracy. The combination of large area and extremely long exposure time gives the good opportunity to search the fine polarization effects like vacuum nonlinear electrodynamics birefringence.

  15. Effects of nonlinearity in the materials used for the semi-rigid pedicle screw systems on biomechanical behaviors of the lumbar spine after surgery

    International Nuclear Information System (INIS)

    Kim, Hyun; Lee, Sung-Jae; Lim, Do-Hyung; Oh, Hyun-Ju; Lee, Kwon-Yong

    2011-01-01

    Recently, various types of semi-rigid pedicle screw fixation systems have been developed for the surgical treatment of the lumbar spine. They were introduced to address the adverse issues commonly found in traditional rigid spinal fusion--abnormally large motion at the adjacent level and subsequent degeneration. The semi-rigid system uses more compliant materials (nitinol or polymers) and/or changes in rod design (coiled or twisted rods) as compared to the conventional rigid straight rods made of Ti alloys (E = 114 GPa, υ = 0.32). However, biomechanical studies on the semi-rigid pedicle screw systems were usually limited to linear modeling of the implant and anatomic elements, which may not be capable of reflecting realistic post-operative motions of the spine. In this study, we evaluated the effects of nonlinearity in materials used for semi-rigid pedicle screw fixation systems to evaluate the changes in biomechanical behaviors using finite element analysis. Changes in range of motion (ROM) and center of rotation (COR) were assessed at the operated and adjacent levels. Actual load-displacement results of the semi-rigid rod from mechanical test were carried out to reflect the nonlinearity of the implant. In addition, nonlinear material properties of various spinal ligaments studies were used for the finite element modeling. The post-operative models were constructed by modifying the previously validated intact model of the L1-S1 spine. Eight different post-operative models were made to address the effects of nonlinearity-with a traditional stiffness modulus rod (with linear ligaments, case 1; with nonlinear ligaments, case 5), with a rigid rod (with linear ligaments, case 2; with nonlinear ligaments, case 6), with a soft rod (with linear ligaments, case 3; with nonlinear ligaments, case 7), and with a nonlinear rod (with linear ligaments, case 4; with nonlinear ligaments, case 8). To simulate the load on the lumbar spine in a neutral posture, follower load (400 N

  16. Modeling of periodic great earthquakes on the San Andreas fault: Effects of nonlinear crustal rheology

    Science.gov (United States)

    Reches, Ze'ev; Schubert, Gerald; Anderson, Charles

    1994-01-01

    We analyze the cycle of great earthquakes along the San Andreas fault with a finite element numerical model of deformation in a crust with a nonlinear viscoelastic rheology. The viscous component of deformation has an effective viscosity that depends exponentially on the inverse absolute temperature and nonlinearity on the shear stress; the elastic deformation is linear. Crustal thickness and temperature are constrained by seismic and heat flow data for California. The models are for anti plane strain in a 25-km-thick crustal layer having a very long, vertical strike-slip fault; the crustal block extends 250 km to either side of the fault. During the earthquake cycle that lasts 160 years, a constant plate velocity v(sub p)/2 = 17.5 mm yr is applied to the base of the crust and to the vertical end of the crustal block 250 km away from the fault. The upper half of the fault is locked during the interseismic period, while its lower half slips at the constant plate velocity. The locked part of the fault is moved abruptly 2.8 m every 160 years to simulate great earthquakes. The results are sensitive to crustal rheology. Models with quartzite-like rheology display profound transient stages in the velocity, displacement, and stress fields. The predicted transient zone extends about 3-4 times the crustal thickness on each side of the fault, significantly wider than the zone of deformation in elastic models. Models with diabase-like rheology behave similarly to elastic models and exhibit no transient stages. The model predictions are compared with geodetic observations of fault-parallel velocities in northern and central California and local rates of shear strain along the San Andreas fault. The observations are best fit by models which are 10-100 times less viscous than a quartzite-like rheology. Since the lower crust in California is composed of intermediate to mafic rocks, the present result suggests that the in situ viscosity of the crustal rock is orders of magnitude

  17. The Non-Linear Effect of Chinese Financial Developments on Energy Supply Structures

    Directory of Open Access Journals (Sweden)

    Jian Chai

    2016-10-01

    Full Text Available Currently, oversupply coal and coal-based power in China poses a great challenge to energy structure optimization and emissions reduction. The energy industry, however, is closely linked to the financial sector. In view of this, using a non-linear Panel Smooth Transition Regression (PSTR model, this paper examines the threshold effects of financial developments on energy supply structures for 17 energy supply provinces in China observed over 2000–2014. The main results are: (1 The ratio of coal supply (LCSR specification is seen to be a four-regime PSTR model with added value in the financial industry/GDP (LFIR as the threshold variable. The LFIR and LCSR show a positive correlation, and the elastic coefficients change between 0.02 and ~0.085; the impact of financial institutions’ loan balance/GDP (LLAN on LCSR takes on an inverse U-shaped curve: first positive, then negative, and again positive with the financial crisis in 2008 as the turning point; (2 The ratio of thermal power generation (LTPG specification is seen to be a two-regime PSTR model with investment in the coal industry/GDP (LCIR as the threshold variable. Results show that LFIR has a negative effect on LTPG, and the coefficients in the low regime tend to be 0.344%, then gradually decrease to 0.051% in the high regime. The influence of LLAN on the LTPG is positive before and negative after the financial crisis. The influence of the foreign direct investment GDP proportion (LFDI, the degree of financial openness on the LCSR and LTPG both remain negative. Therefore, in the process of formulating energy conservation policies and adjusting energy-intensive industrial structures, the government should fully consider the effect of financial developments.

  18. Effect of weak nonsphericity on linear and nonlinear optical properties of small particle composites

    International Nuclear Information System (INIS)

    Goncharenko, A.V.; Popelnukh, V.V.; Venger, E.F.

    2002-01-01

    A small particle composite in which the inclusions are slightly nonspherical and distributed in shape is considered. Within the framework of the mean-field approximation, the functions of linear and nonlinear optical responses are calculated in terms of a nonsphericity parameter specifying the width of the distribution function in shape. To estimate the effect of weak nonsphericity on the functions, their second derivatives with respect to the nonsphericity parameter are computed. The derivatives are shown to be complexly structured surfaces in the coordinates (Re(ε i /ε m ), Im(ε i /ε m )), where ε i and ε m are the inclusion and matrix permittivity, respectively. Based on the results obtained, applicability area of the classical Maxwell Garnett theory is discussed. The main conclusion is that weak nonsphericity is significant only in the close vicinity of a dipole resonance of a single ball made of inclusion material. At the same time, the role of nonsphericity increases with decreasing the imaginary part of inclusion permittivity. (author)

  19. Nonlinear dynamic analysis of framed structures including soil-structure interaction effects

    International Nuclear Information System (INIS)

    Mahmood, M.N.; Ahmed, S.Y.

    2008-01-01

    The role of oil-structure interaction on seismic behavior of reinforced concrete structures is investigated in this paper. A finite element approach has been adopted to model the interaction system that consists of the reinforced concrete plane frame, soil deposit and interface which represents the frictional between foundation of the structure and subsoil. The analysis is based on the elasto-plastic behavior of the frame members (beams and columns) that is defined by the ultimate axial force-bending moment interaction curve, while the cap model is adopted to govern the elasto-plastic behavior of the soil material. Mohr-Coulomb failure law is used to determine the initiation of slippage at the interface, while the separation is assumed to determine the initiation of slippage at the interface, while the separation is assumed to occur when the stresses at the interface becomes tension stresses. New-Mark's Predictor-Corrector algorithm is adopted for nonlinear dynamic analysis. The main aim of present work is to evaluate the sensitivity of structures to different behavior of the soil and interface layer when subjected to an earthquake excitation. Predicted results of the dynamic analysis of the interaction system indicate that the soil-structure interaction problem can have beneficial effects on the structural behavior when different soil models (elastic and elasto-plastic) and interface conditions (perfect bond and permitted slip)are considered. (author)

  20. Nonlinear side effects of fs pulses inside corneal tissue during photodisruption

    Science.gov (United States)

    Heisterkamp, A.; Ripken, T.; Mamom, T.; Drommer, W.; Welling, H.; Ertmer, W.; Lubatschowski, H.

    In order to evaluate the potential for refractive surgery, fs laser pulses of 150-fs pulse duration were used to process corneal tissue of dead and living animal eyes. By focusing the laser radiation down to spot sizes of several microns, very precise cuts could be achieved inside the treated cornea, accompanied with minimum collateral damage to the tissue by thermal or mechanical effects. During histo-pathological analysis by light and transmission electron microscopy considerable side effects of fs photodisruption were found. Due to the high intensities at the focal region several nonlinear effects occurred. Self-focusing, photodissociation, UV-light production were observed, leading to streak formation inside the cornea.

  1. Reduced, three-dimensional, nonlinear equations for high-β plasmas including toroidal effects

    International Nuclear Information System (INIS)

    Schmalz, R.

    1980-11-01

    The resistive MHD equations for toroidal plasma configurations are reduced by expanding to the second order in epsilon, the inverse aspect ratio, allowing for high β = μsub(o)p/B 2 of order epsilon. The result is a closed system of nonlinear, three-dimensional equations where the fast magnetohydrodynamic time scale is eliminated. In particular, the equation for the toroidal velocity remains decoupled. (orig.)

  2. A Comparison of Two-Stage Approaches for Fitting Nonlinear Ordinary Differential Equation Models with Mixed Effects.

    Science.gov (United States)

    Chow, Sy-Miin; Bendezú, Jason J; Cole, Pamela M; Ram, Nilam

    2016-01-01

    Several approaches exist for estimating the derivatives of observed data for model exploration purposes, including functional data analysis (FDA; Ramsay & Silverman, 2005 ), generalized local linear approximation (GLLA; Boker, Deboeck, Edler, & Peel, 2010 ), and generalized orthogonal local derivative approximation (GOLD; Deboeck, 2010 ). These derivative estimation procedures can be used in a two-stage process to fit mixed effects ordinary differential equation (ODE) models. While the performance and utility of these routines for estimating linear ODEs have been established, they have not yet been evaluated in the context of nonlinear ODEs with mixed effects. We compared properties of the GLLA and GOLD to an FDA-based two-stage approach denoted herein as functional ordinary differential equation with mixed effects (FODEmixed) in a Monte Carlo (MC) study using a nonlinear coupled oscillators model with mixed effects. Simulation results showed that overall, the FODEmixed outperformed both the GLLA and GOLD across all the embedding dimensions considered, but a novel use of a fourth-order GLLA approach combined with very high embedding dimensions yielded estimation results that almost paralleled those from the FODEmixed. We discuss the strengths and limitations of each approach and demonstrate how output from each stage of FODEmixed may be used to inform empirical modeling of young children's self-regulation.

  3. The effect of gas and fluid flows on nonlinear lateral vibrations of rotating drill strings

    Science.gov (United States)

    Khajiyeva, Lelya; Kudaibergenov, Askar; Kudaibergenov, Askat

    2018-06-01

    In this work we develop nonlinear mathematical models describing coupled lateral vibrations of a rotating drill string under the effect of external supersonic gas and internal fluid flows. An axial compressive load and a torque also affect the drill string. The mathematical models are derived by the use of Novozhilov's nonlinear theory of elasticity with implementation of Hamilton's variation principle. Expressions for the gas flow pressure are determined according to the piston theory. The fluid flow is considered as added mass inside the curved tube of the drill string. Using an algorithm developed in the Mathematica computation program on the basis of the Galerkin approach and the stiffness switching method the numerical solution of the obtained approximate differential equations is found. Influences of the external loads, drill string angular speed of rotation, parameters of the gas and fluid flows on the drill string vibrations are shown.

  4. Effect of Friction-Induced Nonlinearity on OMA-Identified Dynamic Characteristics of Offshore Platform Models

    DEFF Research Database (Denmark)

    Friis, Tobias; Orfanos, Antonios; Katsanos, Evangelos

    The identification of the modal characteristics of engineering systems under operational conditions is commonly conducted with the use of the Operational Modal Analysis (OMA), being a class of useful tools employed within various fields of structural, mechanical as well as marine and naval...... engineering. The current OMA methods have been advanced on the basis of two fundamental, though, restrictive assumptions: (i) linearity and (ii) stationarity. Nevertheless, there are several applications that are inherently related to various nonlinear mechanisms, which, in turn, violate the two cornerstones...... of OMA and hence, question its robustness and efficiency. Along these lines, the current study addresses the effect of friction-induced nonlinearity on OMA-identified dynamic characteristics of an experimental set up consisting of a pair of reduced scale offshore platform models that are connected...

  5. Pulse carving using nanocavity-enhanced nonlinear effects in photonic crystal Fano structures

    DEFF Research Database (Denmark)

    Bekele, Dagmawi Alemayehu; Yu, Yi; Hu, Hao

    2018-01-01

    We experimentally demonstrate the use of a photonic crystal Fano resonance for carving-out short pulses from long-duration input pulses. This is achieved by exploiting an asymmetric Fano resonance combined with carrier-induced nonlinear effects in a photonic crystal membrane structure. The use...... of a nanocavity concentrates the input field to a very small volume leading to an efficient nonlinear resonance shift that carves a short pulse out of the input pulse. Here, we demonstrate shortening of ∼500  ps and ∼100  ps long pulses to ∼30  ps and ∼20  ps pulses, respectively. Furthermore, we demonstrate...

  6. Nonlinear interplay of TEM and ITG turbulence and its effect on transport

    Science.gov (United States)

    Merz, F.; Jenko, F.

    2010-05-01

    The dominant source of anomalous transport in fusion plasmas on ion scales is turbulence driven by trapped electron modes (TEMs) and ion temperature gradient (ITG) modes. While the individual properties of each of these two instabilities and the corresponding microturbulence have been examined in detail in the past, the effects of a coexistence of the two modes and the phenomena of transitions between the TEM and ITG dominated regimes are not well studied. In many experimental situations, the temperature and density gradients support both microinstabilities simultaneously, so that transitional regimes are important for a detailed understanding of fusion plasmas. In this paper, this issue is addressed, using the gyrokinetic code GENE for a detailed investigation of the dominant and subdominant linear instabilities and the corresponding nonlinear system. A simple quasilinear model based on eigenvalue computations is presented which is shown to reproduce important features of the nonlinear TEM-ITG transition.

  7. The effect of magnetic field on bistability in 1D photonic crystal doped by magnetized plasma and coupled nonlinear defects

    International Nuclear Information System (INIS)

    Mehdian, H.; Mohammadzahery, Z.; Hasanbeigi, A.

    2014-01-01

    In this work, we study the defect mode and bistability behavior of 1-D photonic band gap structure with magnetized plasma and coupled nonlinear defects. The transfer matrix method has been employed to investigate the magnetic field effect on defect mode frequency and bistability threshold. The obtained results show that the frequency of defect mode and bistability threshold can be altered, without changing the structure of the photonic multilayer. Therefore, the bistability behavior of the subjected structure in the presence of magnetized plasma can be utilized in manufacturing wide frequency range devices

  8. High-speed optical three-axis vector magnetometry based on nonlinear Hanle effect in rubidium vapor

    Science.gov (United States)

    Azizbekyan, Hrayr; Shmavonyan, Svetlana; Khanbekyan, Aleksandr; Movsisyan, Marina; Papoyan, Aram

    2017-07-01

    The magnetic-field-compensation optical vector magnetometer based on the nonlinear Hanle effect in alkali metal vapor allowing two-axis measurement operation has been further elaborated for three-axis performance, along with significant reduction of measurement time. The upgrade was achieved by implementing a two-beam resonant excitation configuration and a fast maximum searching algorithm. Results of the proof-of-concept experiments, demonstrating 1 μT B-field resolution, are presented. The applied interest and capability of the proposed technique is analyzed.

  9. Characterizing the Effective Bandwidth of Nonlinear Vibratory Energy Harvesters Possessing Multiple Stable Equilibria

    Science.gov (United States)

    Panyam Mohan Ram, Meghashyam

    In the last few years, advances in micro-fabrication technologies have lead to the development of low-power electronic devices spanning critical fields related to sensing, data transmission, and medical implants. Unfortunately, effective utilization of these devices is currently hindered by their reliance on batteries. In many of these applications, batteries may not be a viable choice as they have a fixed storage capacity and need to be constantly replaced or recharged. In light of such challenges, several novel concepts for micro-power generation have been recently introduced to harness, otherwise, wasted ambient energy from the environment and maintain these low-power devices. Vibratory energy harvesting is one such concept which has received significant attention in recent years. While linear vibratory energy harvesters have been well studied in the literature and their performance metrics have been established, recent research has focused on deliberate introduction of stiffness nonlinearities into the design of these devices. It has been shown that, nonlinear energy harvesters have a wider steady-state frequency bandwidth as compared to their linear counterparts, leading to the premise that they can used to improve performance, and decrease sensitivity to variations in the design and excitation parameters. This dissertation aims to investigate this premise by developing an analytical framework to study the influence of stiffness nonlinearities on the performance and effective bandwidth of nonlinear vibratory energy harvesters. To achieve this goal, the dissertation is divided into three parts. The first part investigates the performance of bi-stable energy harvesters possessing a symmetric quartic potential energy function under harmonic excitations and carries out a detailed analysis to define their effective frequency bandwidth. The second part investigates the relative performance of mono- and bi-stable energy harvesters under optimal electric loading

  10. Effects of applied electromagnetic fields on the linear and nonlinear optical properties in an inverse parabolic quantum well

    International Nuclear Information System (INIS)

    Ungan, F.; Yesilgul, U.; Kasapoglu, E.; Sari, H.; Sökmen, I.

    2012-01-01

    In this present work, we have investigated theoretically the effects of applied electric and magnetic fields on the linear and nonlinear optical properties in a GaAs/Al x Ga 1−x As inverse parabolic quantum well for different Al concentrations at the well center. The Al concentration at the barriers was always x max =0.3. The energy levels and wave functions are calculated within the effective mass approximation and the envelope function approach. The analytical expressions of optical properties are obtained by using the compact density-matrix approach. The linear, third-order nonlinear and total absorption and refractive index changes depending on the Al concentration at the well center are investigated as a function of the incident photon energy for the different values of the applied electric and magnetic fields. The results show that the applied electric and magnetic fields have a great effect on these optical quantities. - Highlights: ► The x c concentration has a great effect on the optical characteristics of these structures. ► The EM fields have a great effect on the optical properties of these structures. ► The total absorption coefficients increased as the electric and magnetic field increases. ► The RICs reduced as the electric and magnetic field increases.

  11. Interface width effect on the classical Rayleigh-Taylor instability in the weakly nonlinear regime

    International Nuclear Information System (INIS)

    Wang, L. F.; Ye, W. H.; Li, Y. J.

    2010-01-01

    In this paper, the interface width effects (i.e., the density gradient effects or the density transition layer effects) on the Rayleigh-Taylor instability (RTI) in the weakly nonlinear (WN) regime are investigated by numerical simulation (NS). It is found that the interface width effects dramatically influence the linear growth rate in the linear growth regime and the mode coupling process in the WN growth regime. First, the interface width effects decrease the linear growth rate of the RTI, particularly for the short perturbation wavelengths. Second, the interface width effects suppress (reduce) the third-order feedback to the fundamental mode, which induces the nonlinear saturation amplitude (NSA) to exceed the classical prediction, 0.1λ. The wider the density transition layer is, the larger the NSA is. The NSA in our NS can reach a half of its perturbation wavelength. Finally, the interface width effects suppress the generation and the growth of the second and the third harmonics. The ability to suppress the harmonics' growth increases with the interface width but decreases with the perturbation wavelength. On the whole, in the WN regime, the interface width effects stabilize the RTI, except for an enhancement of the NSA, which is expected to improve the understanding of the formation mechanism for the astrophysical jets, and for the jetlike long spikes in the high energy density physics.

  12. A numerical approach for assessing effects of shear on equivalent permeability and nonlinear flow characteristics of 2-D fracture networks

    Science.gov (United States)

    Liu, Richeng; Li, Bo; Jiang, Yujing; Yu, Liyuan

    2018-01-01

    Hydro-mechanical properties of rock fractures are core issues for many geoscience and geo-engineering practices. Previous experimental and numerical studies have revealed that shear processes could greatly enhance the permeability of single rock fractures, yet the shear effects on hydraulic properties of fractured rock masses have received little attention. In most previous fracture network models, single fractures are typically presumed to be formed by parallel plates and flow is presumed to obey the cubic law. However, related studies have suggested that the parallel plate model cannot realistically represent the surface characters of natural rock fractures, and the relationship between flow rate and pressure drop will no longer be linear at sufficiently large Reynolds numbers. In the present study, a numerical approach was established to assess the effects of shear on the hydraulic properties of 2-D discrete fracture networks (DFNs) in both linear and nonlinear regimes. DFNs considering fracture surface roughness and variation of aperture in space were generated using an originally developed code DFNGEN. Numerical simulations by solving Navier-Stokes equations were performed to simulate the fluid flow through these DFNs. A fracture that cuts through each model was sheared and by varying the shear and normal displacements, effects of shear on equivalent permeability and nonlinear flow characteristics of DFNs were estimated. The results show that the critical condition of quantifying the transition from a linear flow regime to a nonlinear flow regime is: 10-4 〈 J hydraulic gradient. When the fluid flow is in a linear regime (i.e., J reduce the equivalent permeability significantly in the orientation perpendicular to the sheared fracture as much as 53.86% when J = 1, shear displacement Ds = 7 mm, and normal displacement Dn = 1 mm. By fitting the calculated results, the mathematical expression for δ2 is established to help choose proper governing equations when

  13. Integrability and soliton in a classical one dimensional site dependent biquadratic Heisenberg spin chain and the effect of nonlinear inhomogeneity

    International Nuclear Information System (INIS)

    Kavitha, L.; Daniel, M.

    2002-07-01

    The integrability of one dimensional classical continuum inhomogeneous biquadratic Heisenberg spin chain and the effect of nonlinear inhomogeneity on the soliton of an underlying completely integrable spin model are studied. The dynamics of the spin system is expressed in terms of a higher order generalized nonlinear Schroedinger equation through a differential geometric approach which becomes integrable for a particular choice of the biquadratic exchange interaction and for linear inhomogeneity. The effect of nonlinear inhomogeneity on the spin soliton is studied by carrying out a multiple scale perturbation analysis. (author)

  14. Shaking table testing of a HTGR reactor core, comparison with the results obtained using a nonlinear mathematical model

    International Nuclear Information System (INIS)

    Berriaud, C.; Cebe, E.; Livolant, M.; Buland, P.

    1975-01-01

    Two series of horizontal tests have been performed at Saclay on the shaking table VESUVE: sinusoidal test and time history response. Sinusoidal tests have shown the strongly nonlinear dynamic behavior of the core. The resonant frequency of the core is dependent on the level of the excitation. These phenomena have been explained by a computer code, which is a lumped mass nonlinear model. El Centro time history displacement at the level of PCRV was reproduced on the shaking table. The analytical model was applied to this excitation and good comparison was obtained for forces and velocities [fr

  15. Effect of nonlinear crystal thickness on the parameters of the autocorrelator of femtosecond light pulses

    International Nuclear Information System (INIS)

    Masalov, Anatolii V; Chudnovsky, Aleksandr V

    2004-01-01

    It is shown that the finite thickness of the second-harmonic crystal distorts the results of measurements in nonlinear autocorrelators intended for measuring the durations and fields of femtosecond light pulses mainly due to dispersive broadening (or compression) of the pulses being measured, as well as due to the group velocity mismatch between the fundamental and sum-frequency pulses. The refractive index dispersion of the crystal, scaled by half its thickness, distorts the pulse duration to a certain extent depending on its initial chirp and thus determines the width of the energy distribution recorded in the autocorrelator. As the crystal thickness increases, the group velocity mismatch leads to a transformation of the recorded distribution from the correlation function of intensity to the squared modulus of the field correlation function. In the case of Gaussian pulses, such a transformation does not affect significantly the recorded distribution. Errors of pulse duration measurements are estimated. (nonlinear optical phenomena)

  16. Effect of nonlinear void reactivity on bifurcation characteristics of a lumped-parameter model of a BWR: A study relevant to RBMK

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Dinkar, E-mail: dinkar@iitk.ac.in [Nuclear Engineering and Technology Program, Indian Institute of Technology Kanpur, Kanpur 208 016 (India); Kalra, Manjeet Singh, E-mail: drmanjeet.singh@dituniversity.edu.in [DIT University, Dehradun 248 009 (India); Wahi, Pankaj, E-mail: wahi@iitk.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)

    2017-04-15

    Highlights: • A simplified model with nonlinear void reactivity feedback is studied. • Method of multiple scales for nonlinear analysis and oscillation characteristics. • Second order void reactivity dominates in determining system dynamics. • Opposing signs of linear and quadratic void reactivity enhances global safety. - Abstract: In the present work, the effect of nonlinear void reactivity on the dynamics of a simplified lumped-parameter model for a boiling water reactor (BWR) is investigated. A mathematical model of five differential equations comprising of neutronics and thermal-hydraulics encompassing the nonlinearities associated with both the reactivity feedbacks and the heat transfer process has been used. To this end, we have considered parameters relevant to RBMK for which the void reactivity is known to be nonlinear. A nonlinear analysis of the model exploiting the method of multiple time scales (MMTS) predicts the occurrence of the two types of Hopf bifurcation, namely subcritical and supercritical, leading to the evolution of limit cycles for a range of parameters. Numerical simulations have been performed to verify the analytical results obtained by MMTS. The study shows that the nonlinear reactivity has a significant influence on the system dynamics. A parametric study with varying nominal reactor power and operating conditions in coolant channel has also been performed which shows the effect of change in concerned parameter on the boundary between regions of sub- and super-critical Hopf bifurcations in the space constituted by the two coefficients of reactivities viz. the void and the Doppler coefficient of reactivities. In particular, we find that introduction of a negative quadratic term in the void reactivity feedback significantly increases the supercritical region and dominates in determining the system dynamics.

  17. Ab initio studies on the optical effects in the deep ultraviolet nonlinear optical crystals of the KBe2BO3F2 family

    International Nuclear Information System (INIS)

    Kang Lei; Luo Siyang; Huang Hongwei; Lin, Z S; Chen, C T; Zheng Tao

    2012-01-01

    Electronic structures of the deep ultraviolet nonlinear optical crystals of the KBe 2 BO 3 F 2 (KBBF) family, including KBBF, RbBe 2 BO 3 F 2 and CsBe 2 BO 3 F 2 , have been investigated based on a plane-wave pseudopotential method. Their linear and nonlinear optical coefficients are also calculated, and are in good agreement with the experimental results. A real-space atom-cutting method is adopted to analyze the respective contributions of the alkali metal cations and anionic groups to optical response. The results show that the contributions of anionic groups to the nonlinear optical anisotropic responses are dominant, but the influence of the A-site alkali metal cations becomes slightly more pronounced with the increase of their radius. Moreover, the birefringence difference among these crystals strongly depends on the volume effect, i.e., the spatial density of the (BO 3 ) 3- anionic groups. (paper)

  18. Effects of combined linear and nonlinear periodic training on physical fitness and competition times in finswimmers.

    Science.gov (United States)

    Yu, Kyung-Hun; Suk, Min-Hwa; Kang, Shin-Woo; Shin, Yun-A

    2014-10-01

    The purpose of this study was to investigate the effect of combined linear and nonlinear periodic training on physical fitness and competition times in finswimmers. The linear resistance training model (6 days/week) and nonlinear underwater training (4 days/week) were applied to 12 finswimmers (age, 16.08± 1.44 yr; career, 3.78± 1.90 yr) for 12 weeks. Body composition measures included weight, body mass index (BMI), percent fat, and fat-free mass. Physical fitness measures included trunk flexion forward, trunk extension backward, sargent jump, 1-repetition-maximum (1 RM) squat, 1 RM dead lift, knee extension, knee flexion, trunk extension, trunk flexion, and competition times. Body composition and physical fitness were improved after the 12-week periodic training program. Weight, BMI, and percent fat were significantly decreased, and trunk flexion forward, trunk extension backward, sargent jump, 1 RM squat, 1 RM dead lift, and knee extension (right) were significantly increased. The 50- and 100-m times significantly decreased in all 12 athletes. After 12 weeks of training, all finswimmers who participated in this study improved their times in a public competition. These data indicate that combined linear and nonlinear periodic training enhanced the physical fitness and competition times in finswimmers.

  19. Nonlinear electrostatic ion-acoustic "oscilliton" waves driven by charge non-neutrality effects

    Directory of Open Access Journals (Sweden)

    J. Z. G. Ma

    2011-01-01

    Full Text Available Nonlinear "oscilliton" structures features a low-frequency (LF solitary envelope, the amplitude of which is modulated violently by superimposed high-frequency (HF oscillations. We have studied the charge non-neutrality effects on the excitation of electrostatic ion-acoustic (IA oscillitons. A two-fluid, warm plasma model is employed, and a set of nonlinear self-similar equations is solved in a cylindrical geometry. Under charge-neutrality conditions, three conventional IA structures (namely, sinusoidal, sawtooth, and spicky/bipolar are obtained. By contrast, under charge non-neutrality conditions, oscilliton structures are excited, where the LF envelope is in the sound-wave (SW mode, while the HF ingredients include the IA mode and the ion-Langmiur (IL mode. The amplitudes of the SW wave are violently modulated by the IA oscillations, whereas the upward sides of the IA amplitudes are modulated by the IL oscillations of smaller amplitudes, and the downward sides are modulated by hybrid IA/IL oscillations. The nonlinear oscillitons are found to be dependent not only upon the input parameters (e.g., the Mach number, the Debye length, and the initial temperature of particles, but on initial conditions as well.

  20. Grain size effects on stability of nonlinear vibration with nanocrystalline NiTi shape memory alloy

    Science.gov (United States)

    Xia, Minglu; Sun, Qingping

    2017-10-01

    Grain size effects on stability of thermomechanical responses for a nonlinear torsional vibration system with nanocrystalline superelastic NiTi bar are investigated in the frequency and amplitude domains. NiTi bars with average grain size from 10 nm to 100 nm are fabricated through cold-rolling and subsequent annealing. Thermomechanical responses of the NiTi bar as a softening nonlinear damping spring in the torsional vibration system are obtained by synchronised acquisition of rotational angle and temperature under external sinusoidal excitation. It is shown that nonlinearity and damping capacity of the NiTi bar decrease as average grain size of the material is reduced below 100 nm. Therefore jump phenomena of thermomechanical responses become less significant or even vanish and the vibration system becomes more stable. The work in this paper provides a solid experimental base for manipulating the undesired jump phenomena of thermomechanical responses and stabilising the mechanical vibration system through grain refinement of NiTi SMA.

  1. ac electrokinetic micropumps: The effect of geometrical confinement, Faradaic current injection, and nonlinear surface capacitance

    DEFF Research Database (Denmark)

    Olesen, Laurits Højgaard; Bruus, Henrik; Ajdari, A.

    2006-01-01

    therefore extend the latter theories to account for three experimentally relevant effects: (i) vertical confinement of the pumping channel, (ii) Faradaic currents from electrochemical reactions at the electrodes, and (iii) nonlinear surface capacitance of the Debye layer. We report here that these effects......Recent experiments have demonstrated that ac electrokinetic micropumps permit integrable, local, and fast pumping (velocities similar to mm/s) with low driving voltage of a few volts only. However, they also displayed many quantitative and qualitative discrepancies with existing theories. We...

  2. Generalized effective potential in nonlinear theories of the 4-th order

    International Nuclear Information System (INIS)

    Ananikyan, N.S.; Savvidy, G.K.

    1980-01-01

    By means of the Legendre transformations in the framework of nonlinear theories of the 4-th order a generalized effective potential GITA(phi, G, H, S) is constructed. It depends on PHI, a possible expectation value of the quantum field; on G, H, possible expectation values of the 2- a.nd 3-point connected Green functions and on S= a possible expectation value of the classical action. The expansion for the functional GITA(phi, G, H, S) is obtained, which is similar to the loop expansion for the effective action GITA(phi)

  3. Analysis and simulation of nonlinearity and effects of spontaneous emission in Schottky-junction-based plasmonic amplifiers.

    Science.gov (United States)

    Livani, Abdolber Mallah; Kaatuzian, Hassan

    2015-07-01

    An amplifier that operates on surface plasmon polaritons has been analyzed and simulated. Nonlinearity behavior and the spontaneous emission effects of the plasmonic amplifier are investigated in this paper. A rate equations approach has been used in which parameters are derived from simulation results of the plasmonic amplifier (Silvaco/ATLAS). Details on the method of this derivation are included, which were not previously reported. Rate equations are solved numerically by MATLAB codes. These codes verify the Silvaco results. The plasmonic amplifier operates on surface plasmons with a free-space wavelength of 1550 nm. Results show that, even without the effect of spontaneous emission, gain of the plasmonic amplifier saturates in high input levels. Saturation power, which can be used for comparing nonlinearity of different amplifiers, is 2.1 dBm for this amplifier. Amplified spontaneous emission reduces the gain of the amplifiers, which is long. There is an optimum value for the length of the amplifier. For the amplifier of this work, the optimum length for the small signal condition is 265 μm.

  4. Study on the contact ratio of base mat of reactor buildings considering nonlinear soil-structure interaction effects

    International Nuclear Information System (INIS)

    Aihara, S.; Atsumi, K.; Ujiie, K.; Emori, K.; Odajima, M.; Masuda, K.

    1983-01-01

    The objective of this paper is to evaluate the nonlinear soil-structure interaction effects resulting from base mat uplift for static lateral loads. Nonlinear soil-structure interaction effects are modeled through the use of equivalent soil-structure interaction frictional and axial springs, which properties are determined by results of experimental data. It is assumed that normal stresses in compression and corresponding shear stresses, and friction, can occur in the area of contact between the embedded structure and soil. The remaining parts of the structure and soil are based on elastic analysis. A two-dimensional finite element method with incremental loadings is applied. The substructuring technique is used to reduce computation time. The results of this method with respect to the contact ratio of the base mat are compared with the values obtained by static elastic calculation which is simply derived from an overturning moment and a vertical load of the structure. This analytical concept will be developed into dynamic problems, and then it will be possible to state whether or not this concept can represent a true alternative for the contact ratio of the base mat of a structure. (orig./HP)

  5. Nonlinear effects in parallel magnetic fields in vanadyl and iron (111) ions solutions

    International Nuclear Information System (INIS)

    Ryzhov, V.A.; Fomichev, V.N.

    1983-01-01

    Nonlinear effects (NE) in vanadyl (VOSO 4 ) and iron (FeCl 3 x6H 2 O) solutions are investigated experimentally in the 268-323 K temperature range in parallel constant and variable linearly polarized magnetic fields, including conditions when EPR spectra are lacking due to strong resonance transition widening. It is shown that nonlinear effects are specified, on the one side, by the effect of a variable field on the relaxation processes and, on the other side, by resonance transitions in parallel fields. The relaxation and resonance effects contribute to different phase components of the second harmonic of magnetization, recorded in the experiment, at low frequences of a variable field (as compared to characteristic frequences of lattice motion). Therefore, separate analysis of the effects is possible. The presence of NE effects under conditions, when the EPR signal is not observed, and the possibility of the inverse problem solution using the variation technique on the base of simple models reveal that NE in parallel magnetic fields may be used for the investigation of paramagnets with a large EPR resonance transitions width

  6. Performance of nonlinear mixed effects models in the presence of informative dropout.

    Science.gov (United States)

    Björnsson, Marcus A; Friberg, Lena E; Simonsson, Ulrika S H

    2015-01-01

    Informative dropout can lead to bias in statistical analyses if not handled appropriately. The objective of this simulation study was to investigate the performance of nonlinear mixed effects models with regard to bias and precision, with and without handling informative dropout. An efficacy variable and dropout depending on that efficacy variable were simulated and model parameters were reestimated, with or without including a dropout model. The Laplace and FOCE-I estimation methods in NONMEM 7, and the stochastic simulations and estimations (SSE) functionality in PsN, were used in the analysis. For the base scenario, bias was low, less than 5% for all fixed effects parameters, when a dropout model was used in the estimations. When a dropout model was not included, bias increased up to 8% for the Laplace method and up to 21% if the FOCE-I estimation method was applied. The bias increased with decreasing number of observations per subject, increasing placebo effect and increasing dropout rate, but was relatively unaffected by the number of subjects in the study. This study illustrates that ignoring informative dropout can lead to biased parameters in nonlinear mixed effects modeling, but even in cases with few observations or high dropout rate, the bias is relatively low and only translates into small effects on predictions of the underlying effect variable. A dropout model is, however, crucial in the presence of informative dropout in order to make realistic simulations of trial outcomes.

  7. Linear and nonlinear relations between psychosocial job characteristics, subjective outcomes, and sickness absence : baseline results from SMASH

    NARCIS (Netherlands)

    Jonge, J. de; Houtman, I.L.D.; Bongers, P.M.; Reuvers, M.M.E.N.; Kompier, M.A.J.

    2000-01-01

    This study investigates the demand-control-support (DCS) model by (a) using a more focused measure of job control, (b) testing for interactive and nonlinear relationships, and (c) further extending the model to the prediction of an objective outcome measure (i.e., company-administrated sickness

  8. Linear and non-linear relations between psychosocial job characteristics, subjective outcomes, and sickness absence: baseline results from SMASH

    NARCIS (Netherlands)

    Jonge, J. de; Reuvers, M.M.E.N.; Houtman, I.L.D.; Bongers, P.M.; Kompier, M.A.J.

    2000-01-01

    This study investigates the demand-control-support (DCS) model by (a) using a more focused measure of job control, (b) testing for interactive and nonlinear relationships, and (c) further extending the model to the prediction of an objective outcome measure (i.e., company-administrated sickness

  9. Nonlinear beam dynamics experimental program at SPEAR

    International Nuclear Information System (INIS)

    Tran, P.; Pellegrini, C.; Cornacchia, M.; Lee, M.; Corbett, W.

    1995-01-01

    Since nonlinear effects can impose strict performance limitations on modern colliders and storage rings, future performance improvements depend on further understanding of nonlinear beam dynamics. Experimental studies of nonlinear beam motion in three-dimensional space have begun in SPEAR using turn-by-turn transverse and longitudinal phase-space monitors. This paper presents preliminary results from an on-going experiment in SPEAR

  10. A New Result Concerning the Solvability of a Class of General Systems of Variational Equations with Nonmonotone Operators: Applications to Dirichlet and Neumann Nonlinear Problems

    Directory of Open Access Journals (Sweden)

    Luisa Toscano

    2016-01-01

    Full Text Available A new result of solvability for a wide class of systems of variational equations depending on parameters and governed by nonmonotone operators is found in a Banach real and reflexive space with applications to Dirichlet and Neumann problems related to nonlinear elliptic systems.

  11. Nature of dislocation hysteresis losses and nonlinear effect in lead at high vibration amplitudes

    International Nuclear Information System (INIS)

    Lomakin, V.V.; Pal-Val, L.N.; Platkov, V.Y.; Roshchupkin, A.M.

    1982-01-01

    The nature of the dislocation hysteresis was established and changes in this hysteresis were determined by investigating the dependence of the dislocation-induced absorption of ultrasound (coefficient α) on the amplitude of ultrasound epsilon-c 0 in single crystals of pure lead and of lead containing Tl and Sn impurities. The investigation was carried out in a wide range of epsilon-c 0 under superconducting transition conditions. In the superconducting (s) state both pure Pb and that doped with T1 exhibited a maximum in the dependence α(epsilon-c 0 ) at high values of epsilon-c 0 ; on transition to the normal (n) state this maximum changed to a plateau. This provided a direct proof of a change in the static nature of the dislocation hysteresis to the dynamic process because of an increase in the coefficient of the electron drag of dislocations. Estimates were obtained of the range of lengths of dislocation loops: 2.4 x 10 - 4 cm - 4 cm. In the case of lead containing Sn the dynamic hysteresis occurred both in the normal and superconducting states. In the range of amplitudes above that of the maximum and at the beginning of the plateau all single crystals exhibited a rise of α on increase of epsilon-c 0 in the superconducting and normal states; this rise was due to nonlinear effects observed in the case of strong bending of L/sub N/ loops. An analysis was made of the amplitude dependence of the losses associated with this effect. The results were in good agreement with the experimental data

  12. The non-linear, interactive effects of population density and climate drive the geographical patterns of waterfowl survival

    Science.gov (United States)

    Zhao, Qing; Boomer, G. Scott; Kendall, William L.

    2018-01-01

    On-going climate change has major impacts on ecological processes and patterns. Understanding the impacts of climate on the geographical patterns of survival can provide insights to how population dynamics respond to climate change and provide important information for the development of appropriate conservation strategies at regional scales. It is challenging to understand the impacts of climate on survival, however, due to the fact that the non-linear relationship between survival and climate can be modified by density-dependent processes. In this study we extended the Brownie model to partition hunting and non-hunting mortalities and linked non-hunting survival to covariates. We applied this model to four decades (1972–2014) of waterfowl band-recovery, breeding population survey, and precipitation and temperature data covering multiple ecological regions to examine the non-linear, interactive effects of population density and climate on waterfowl non-hunting survival at a regional scale. Our results showed that the non-linear effect of temperature on waterfowl non-hunting survival was modified by breeding population density. The concave relationship between non-hunting survival and temperature suggested that the effects of warming on waterfowl survival might be multifaceted. Furthermore, the relationship between non-hunting survival and temperature was stronger when population density was higher, suggesting that high-density populations may be less buffered against warming than low-density populations. Our study revealed distinct relationships between waterfowl non-hunting survival and climate across and within ecological regions, highlighting the importance of considering different conservation strategies according to region-specific population and climate conditions. Our findings and associated novel modelling approach have wide implications in conservation practice.

  13. Nonlinear effects of group size on the success of wolves hunting elk

    Science.gov (United States)

    MacNulty, Daniel R.; Smith, Douglas W.; Mech, L. David; Vucetich, John A.; Packer, Craig

    2012-01-01

    Despite the popular view that social predators live in groups because group hunting facilitates prey capture, the apparent tendency for hunting success to peak at small group sizes suggests that the formation of large groups is unrelated to prey capture. Few empirical studies, however, have tested for nonlinear relationships between hunting success and group size, and none have demonstrated why success trails off after peaking. Here, we use a unique dataset of observations of individually known wolves (Canis lupus) hunting elk (Cervus elaphus) in Yellowstone National Park to show that the relationship between success and group size is indeed nonlinear and that individuals withholding effort (free riding) is why success does not increase across large group sizes. Beyond 4 wolves, hunting success leveled off, and individual performance (a measure of effort) decreased for reasons unrelated to interference from inept hunters, individual age, or size. But performance did drop faster among wolves with an incentive to hold back, i.e., nonbreeders with no dependent offspring, those performing dangerous predatory tasks, i.e., grabbing and restraining prey, and those in groups of proficient hunters. These results suggest that decreasing performance was free riding and that was why success leveled off in groups with >4 wolves that had superficially appeared to be cooperating. This is the first direct evidence that nonlinear trends in group hunting success reflect a switch from cooperation to free riding. It also highlights how hunting success per se is unlikely to promote formation and maintenance of large groups.

  14. Nonlinear behaviour of cantilevered carbon nanotube resonators based on a new nonlinear electrostatic load model

    Science.gov (United States)

    Farokhi, Hamed; Païdoussis, Michael P.; Misra, Arun K.

    2018-04-01

    The present study examines the nonlinear behaviour of a cantilevered carbon nanotube (CNT) resonator and its mass detection sensitivity, employing a new nonlinear electrostatic load model. More specifically, a 3D finite element model is developed in order to obtain the electrostatic load distribution on cantilevered CNT resonators. A new nonlinear electrostatic load model is then proposed accounting for the end effects due to finite length. Additionally, a new nonlinear size-dependent continuum model is developed for the cantilevered CNT resonator, employing the modified couple stress theory (to account for size-effects) together with the Kelvin-Voigt model (to account for nonlinear damping); the size-dependent model takes into account all sources of nonlinearity, i.e. geometrical and inertial nonlinearities as well as nonlinearities associated with damping, small-scale, and electrostatic load. The nonlinear equation of motion of the cantilevered CNT resonator is obtained based on the new models developed for the CNT resonator and the electrostatic load. The Galerkin method is then applied to the nonlinear equation of motion, resulting in a set of nonlinear ordinary differential equations, consisting of geometrical, inertial, electrical, damping, and size-dependent nonlinear terms. This high-dimensional nonlinear discretized model is solved numerically utilizing the pseudo-arclength continuation technique. The nonlinear static and dynamic responses of the system are examined for various cases, investigating the effect of DC and AC voltages, length-scale parameter, nonlinear damping, and electrostatic load. Moreover, the mass detection sensitivity of the system is examined for possible application of the CNT resonator as a nanosensor.

  15. Large Spatial and Temporal Separations of Cause and Effect in Policy Making - Dealing with Non-linear Effects

    Science.gov (United States)

    McCaskill, John

    There can be large spatial and temporal separation of cause and effect in policy making. Determining the correct linkage between policy inputs and outcomes can be highly impractical in the complex environments faced by policy makers. In attempting to see and plan for the probable outcomes, standard linear models often overlook, ignore, or are unable to predict catastrophic events that only seem improbable due to the issue of multiple feedback loops. There are several issues with the makeup and behaviors of complex systems that explain the difficulty many mathematical models (factor analysis/structural equation modeling) have in dealing with non-linear effects in complex systems. This chapter highlights those problem issues and offers insights to the usefulness of ABM in dealing with non-linear effects in complex policy making environments.

  16. Nonlinear effects caused by coupling misalignment in rotors equipped with journal bearings

    Science.gov (United States)

    Pennacchi, Paolo; Vania, Andrea; Chatterton, Steven

    2012-07-01

    Misalignment is one of the most common sources of trouble of rotating machinery when rigid couplings connect the shafts. Ideal alignment of the shafts is difficult to be obtained and rotors may present angular and/or parallel misalignment (defined also as radial misalignment or offset). During a complete shaft revolution, a periodical change of the bearings load occurs in hyperstatic shaft-lines, if coupling misalignment between the shafts is excessive. If the rotating machine is equipped with fluid-film journal bearings, the change of the loads on the bearing causes also the variation of their instantaneous dynamic characteristics, i.e. damping and stiffness, and the complete system cannot be considered any longer as linear. Despite misalignment is often observed in the practice, there are relatively few studies about this phenomenon in literature and their results are sometimes conflicting. The authors aim at modeling accurately this phenomenon, for the first time in this paper, and giving pertinent diagnostic information. The proposed method is suitable for every type of shaft-line supported by journal bearings. A finite element model is used for the hyperstatic shaft-line, while bearing characteristics are calculated by integrating Reynolds equation as a function of the instantaneous load acting on the bearings, caused also by the coupling misalignment. The results obtained by applying the proposed method are shown by means of the simulation, in the time domain, of the dynamical response of a hyperstatic shaft-line. Nonlinear effects are highlighted and the spectral components of the system response are analyzed, in order to give diagnostic information about the signature of this type of fault.

  17. Effects of Fluid Environment Properties on the Nonlinear Vibrations of AFM Piezoelectric Microcantilevers

    Directory of Open Access Journals (Sweden)

    Masoud Ahmadi

    2017-12-01

    Full Text Available Nowadays, atomic-force microscopy plays a significant role in nanoscience and nanotechnology, and is widely used for direct measurement at atomic scale and scanning the sample surfaces. In tapping mode, the microcantilever of atomic-force microscope is excited at resonance frequency. Therefore, it is important to study its resonance. Moreover, atomic-force microscopes can be operated in fluid environments such as their applications in chemical and biological sensors. Additionally, piezoelectric microcantilevers are used to enhance atomic-force microscope scanning. Motivated by these considerations, presented herein is a finite element investigation into the nonlinear vibration behavior of piezoelectric microcantilever of atomic-force microscopes in fluid environment. For this purpose, a 3D finite element model coupled with a computational fluid dynamics model is introduced based upon a fluid-solid interaction analysis. First, the reliability of present fluid-solid interaction analysis is revealed by comparison with experimental data available in the literature. Then, numerical results are presented to study the influences of fluid dynamic viscosity and density on the resonance frequency, resonance amplitude and time response of piezoelectric microcantilever. It was shown that increasing the fluid density and dynamic viscosity results in the decrease of resonance frequency. For example, for density equal to 1000 kg/m3 , increasing the viscosity of fluid environment from 0.1 to 1, 10 and 20 mPa.s leads to decrease of resonance frequency about 3%, 29% and 42%, respectively. Also, the resonance amplitude of microcantilever increases as the density increases, while increasing dynamic viscosity has a decreasing effect on the resonance amplitude.

  18. FY 1991 Report on the results of the researches on nonlinear photoelectronic materials; 1991 nendo hisenkei hikari denshi zairyo no kenkyu kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1992-03-01

    The nonlinear optics with light-light conversion and electro-optical effects are expected to be the optical materials of the next generation for their functions of, e.g., conversion of the infrared laser beams into visual light, and optical switching. The efforts are directed to development of the procedures for exploring and designing various raw materials, and technologies for synthesizing the raw materials and for producing and evaluating the materials, in order to develop highly nonlinear, high-speed responding materials. Three areas are studied; for the organic materials, the chiral nonlinear effects are demonstrated and the new procedure for determining electrical susceptibility ({gamma}) is developed; for the dispersed materials, highly nonlinear susceptibility of glass dispersed with fine particles of semiconductors, e.g., CuCl, is realized, and possibility of controlled dispersion of fine semiconductor particles in an organic polymer is established; and for development of the superlattice-based materials, the layered structures of thin organic superlattice films are studied, the thin semiconductor films of high purity and little defects are prepared, and development of the three-dimensional structures is started. The individual researches are conducted, 3 for the organic materials, 4 for the dispersed materials, and 2 for the superlattice-based materials. The targets of susceptibility and response are 10{sup -8}esu or more and 10ps or less, respectively. (NEDO)

  19. Radiation effects in ice: New results

    International Nuclear Information System (INIS)

    Baragiola, R.A.; Fama, M.; Loeffler, M.J.; Raut, U.; Shi, J.

    2008-01-01

    Studies of radiation effects in ice are motivated by intrinsic interest and by applications in astronomy. Here we report on new and recent results on radiation effects induced by energetic ions in ice: amorphization of crystalline ice, compaction of microporous amorphous ice, electrostatic charging and dielectric breakdown and correlated structural/chemical changes in the irradiation of water-ammonia ices

  20. Nonlinear terms in storm surge predictions: Effect of tide and shelf geometry with case study from Hurricane Rita

    Science.gov (United States)

    Rego, JoãO. L.; Li, Chunyan

    2010-06-01

    This study applied the finite volume coastal ocean model (FVCOM) to the storm surge induced by Hurricane Rita along the Louisiana-Texas coast. The model was calibrated for tides and validated with observed water levels. Peak water levels were shown to be lower than expected for a landfall at high tide. For low- and high-tide landfalls, nonlinear effects due to tide-surge coupling were constructive and destructive to total storm tide, respectively, and their magnitude reached up to 70% of the tidal amplitude in the Rita application. Tide-surge interaction was further examined using a standard hurricane under idealized scenarios to evaluate the effects of various shelf geometries, tides, and landfall timings (relative to tide). Nonlinearity was important between landfall position and locations within 2.5 × radius of maximum winds. On an idealized wide continental shelf, nonlinear effects reached up to 80% of the tidal amplitude with an S2 tide and up to 47% with a K1 tide. Increasing average depths by 4 m reduced nonlinear effects to 41% of the tidal amplitude; increasing the slope by a factor of 3 produced nonlinearities of just 26% of tide (both with a K1 tide). The nonlinear effect was greatest for landfalls at low tide, followed by landfalls at high tide and then by landfalls at midebb or midflood.

  1. Electron thermal effect on linear and nonlinear coupled Shukla-Varma and convective cell modes in dust-contaminated magnetoplasma

    Science.gov (United States)

    Masood, W.; Mirza, Arshad M.

    2010-11-01

    Linear and nonlinear properties of coupled Shukla-Varma (SV) and convective cell modes in the presence of electron thermal effects are studied in a nonuniform magnetoplasma composed of electrons, ions, and extremely massive and negatively charged immobile dust grains. In the linear case, the modified dispersion relation is given and, in the nonlinear case, stationary solutions of the nonlinear equations that govern the dynamics of coupled SV and convective cell modes are obtained. It is found that electrostatic dipolar and vortex street type solutions can appear in such a plasma. The relevance of the present investigation with regard to the Earth's mesosphere as well as in ionospheric plasmas is also pointed out.

  2. Electron thermal effect on linear and nonlinear coupled Shukla-Varma and convective cell modes in dust-contaminated magnetoplasma

    International Nuclear Information System (INIS)

    Masood, W.; Mirza, Arshad M.

    2010-01-01

    Linear and nonlinear properties of coupled Shukla-Varma (SV) and convective cell modes in the presence of electron thermal effects are studied in a nonuniform magnetoplasma composed of electrons, ions, and extremely massive and negatively charged immobile dust grains. In the linear case, the modified dispersion relation is given and, in the nonlinear case, stationary solutions of the nonlinear equations that govern the dynamics of coupled SV and convective cell modes are obtained. It is found that electrostatic dipolar and vortex street type solutions can appear in such a plasma. The relevance of the present investigation with regard to the Earth's mesosphere as well as in ionospheric plasmas is also pointed out.

  3. Effects of breathing patterns and light exercise on linear and nonlinear heart rate variability.

    Science.gov (United States)

    Weippert, Matthias; Behrens, Kristin; Rieger, Annika; Kumar, Mohit; Behrens, Martin

    2015-08-01

    Despite their use in cardiac risk stratification, the physiological meaning of nonlinear heart rate variability (HRV) measures is not well understood. The aim of this study was to elucidate effects of breathing frequency, tidal volume, and light exercise on nonlinear HRV and to determine associations with traditional HRV indices. R-R intervals, blood pressure, minute ventilation, breathing frequency, and respiratory gas concentrations were measured in 24 healthy male volunteers during 7 conditions: voluntary breathing at rest, and metronome guided breathing (0.1, 0.2 and 0.4 Hz) during rest, and cycling, respectively. The effect of physical load was significant for heart rate (HR; p < 0.001) and traditional HRV indices SDNN, RMSSD, lnLFP, and lnHFP (p < 0.01 for all). It approached significance for sample entropy (SampEn) and correlation dimension (D2) (p < 0.1 for both), while HRV detrended fluctuation analysis (DFA) measures DFAα1 and DFAα2 were not affected by load condition. Breathing did not affect HR but affected all traditional HRV measures. D2 was not affected by breathing; DFAα1 was moderately affected by breathing; and DFAα2, approximate entropy (ApEn), and SampEn were strongly affected by breathing. DFAα1 was strongly increased, whereas DFAα2, ApEn, and SampEn were decreased by slow breathing. No interaction effect of load and breathing pattern was evident. Correlations to traditional HRV indices were modest (r from -0.14 to -0.67, p < 0.05 to <0.01). In conclusion, while light exercise does not significantly affect short-time HRV nonlinear indices, respiratory activity has to be considered as a potential contributor at rest and during light dynamic exercise.

  4. Alleviating Border Effects in Wavelet Transforms for Nonlinear Time-varying Signal Analysis

    Directory of Open Access Journals (Sweden)

    SU, H.

    2011-08-01

    Full Text Available Border effects are very common in many finite signals analysis and processing approaches using convolution operation. Alleviating the border effects that can occur in the processing of finite-length signals using wavelet transform is considered in this paper. Traditional methods for alleviating the border effects are suitable to compression or coding applications. We propose an algorithm based on Fourier series which is proved to be appropriate to the application of time-frequency analysis of nonlinear signals. Fourier series extension method preserves the time-varying characteristics of the signals. A modified signal duration expression for measuring the extent of border effects region is presented. The proposed algorithm is confirmed to be efficient to alleviate the border effects in comparison to the current methods through the numerical examples.

  5. Probing hysteretic elasticity in weakly nonlinear materials

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Paul A [Los Alamos National Laboratory; Haupert, Sylvain [UPMC UNIV PARIS; Renaud, Guillaume [UPMC UNIV PARIS; Riviere, Jacques [UPMC UNIV PARIS; Talmant, Maryline [UPMC UNIV PARIS; Laugier, Pascal [UPMC UNIV PARIS

    2010-12-07

    Our work is aimed at assessing the elastic and dissipative hysteretic nonlinear parameters' repeatability (precision) using several classes of materials with weak, intermediate and high nonlinear properties. In this contribution, we describe an optimized Nonlinear Resonant Ultrasound Spectroscopy (NRUS) measuring and data processing protocol applied to small samples. The protocol is used to eliminate the effects of environmental condition changes that take place during an experiment, and that may mask the intrinsic elastic nonlinearity. As an example, in our experiments, we identified external temperature fluctuation as a primary source of material resonance frequency and elastic modulus variation. A variation of 0.1 C produced a frequency variation of 0.01 %, which is similar to the expected nonlinear frequency shift for weakly nonlinear materials. In order to eliminate environmental effects, the variation in f{sub 0} (the elastically linear resonance frequency proportional to modulus) is fit with the appropriate function, and that function is used to correct the NRUS calculation of nonlinear parameters. With our correction procedure, we measured relative resonant frequency shifts of 10{sup -5} , which are below 10{sup -4}, often considered the limit to NRUS sensitivity under common experimental conditions. Our results show that the procedure is an alternative to the stringent control of temperature often applied. Applying the approach, we report nonlinear parameters for several materials, some with very small nonclassical nonlinearity. The approach has broad application to NRUS and other Nonlinear Elastic Wave Spectroscopy approaches.

  6. Cosmological leverage from the matter power spectrum in the presence of baryon and nonlinear effects

    International Nuclear Information System (INIS)

    Bielefeld, Jannis; Huterer, Dragan; Linder, Eric V.

    2015-01-01

    We investigate how the use of higher wavenumbers (smaller scales) in the galaxy clustering power spectrum influences cosmological constraints. We take into account uncertainties from nonlinear density fluctuations, (scale dependent) galaxy bias, and baryonic effects. Allowing for substantially model independent uncertainties through separate fit parameters in each wavenumber bin that also allow for the redshift evolution, we quantify strong gains in dark energy and neutrino mass leverage with increasing maximum wavenumber, despite marginalizing over numerous (up to 125) extra fit parameters. The leverage is due to not only an increased number of modes but, more significantly, breaking of degeneracies beyond the linear regime

  7. Third-order perturbations of a zero-pressure cosmological medium: Pure general relativistic nonlinear effects

    International Nuclear Information System (INIS)

    Hwang, Jai-chan; Noh, Hyerim

    2005-01-01

    We consider a general relativistic zero-pressure irrotational cosmological medium perturbed to the third order. We assume a flat Friedmann background but include the cosmological constant. We ignore the rotational perturbation which decays in expanding phase. In our previous studies we discovered that, to the second-order perturbation, except for the gravitational wave contributions, the relativistic equations coincide exactly with the previously known Newtonian ones. Since the Newtonian second-order equations are fully nonlinear, any nonvanishing third- and higher-order terms in the relativistic analyses are supposed to be pure relativistic corrections. In this work, we derive such correction terms appearing in the third order. Continuing our success in the second-order perturbations, we take the comoving gauge. We discover that the third-order correction terms are of φ v order higher than the second-order terms where φ v is a gauge-invariant combination related to the three-space curvature perturbation in the comoving gauge; compared with the Newtonian potential, we have δΦ∼(3/5)φ v to the linear order. Therefore, the pure general relativistic effects are of φ v order higher than the Newtonian ones. The corrections terms are independent of the horizon scale and depend only on the linear-order gravitational potential (curvature) perturbation strength. From the temperature anisotropy of cosmic microwave background, we have (δT/T)∼(1/3)δΦ∼(1/5)φ v ∼10 -5 . Therefore, our present result reinforces our previous important practical implication that near the current era one can use the large-scale Newtonian numerical simulation more reliably even as the simulation scale approaches near (and goes beyond) the horizon

  8. The effect of Moidal non-linear blending function for dual-energy CT on CT image quality

    International Nuclear Information System (INIS)

    Zhang Fan; Yang Li

    2011-01-01

    Objective: To compare the difference between linear blending and non-linear blending function for dual-energy CT, and to evaluate the effect on CT image quality. Methods: The model was made of a piece of fresh pork liver inserted with 5 syringes containing various concentrations of iodine solutions (16.3, 26.4, 48.7, 74.6 and 112.3 HU). Linear blending images were automatically reformatted after the model was scanned in the dual-energy mode. Non-linear blending images were reformatted using the software of optimal contrast in Syngo workstation. Images were divided into 3 groups, including linear blending group, non-linear blending group and 120 kV group. Contrast noise ratio (CNR) were measured and calculated respectively in the 3 groups and the different figure of merit (FOM) values between the groups were compared using one-way ANOVA. Twenty patients scanned in the dual-energy mode were randomly selected and the SNR of their liver, renal cortex, spleen, pancreas and abdominal aorta were measured. The independent sample t test was used to compare the difference of signal to noise ratio (SNR) between linear blending group and non linear blending group. Two readers' agreement score and single-blind method were used to investigate the conspicuity difference between linear blending group and non linear blending group. Results: With models of different CT values, the FOM values in non-linear blending group were 20.65± 8.18, 11.40±4.25, 1.60±0.82, 2.40±1.13, 45.49±17.86. In 74.6 HU and 112.3 HU models, the differences of the FOM values observed among the three groups were statistically significant (P<0.05), which were 0.30±0.06 and 14.43±4.59 for linear blending group, and 0.22±0.05 and 15.31±5.16 for 120 kV group. And non-linear blending group had a better FOM value. The SNR of renal cortex and abdominal aorta were 19.2±5.1 and 36.5±13.9 for non-linear blending group, while they were 12.4±3.8 and 22.6±7.0 for linear blending group. There were statistically

  9. Applicability of a panel method, which includes nonlinear effects, to a forward-swept-wing aircraft

    Science.gov (United States)

    Ross, J. C.

    1984-01-01

    The ability of a lower order panel method VSAERO, to accurately predict the lift and pitching moment of a complete forward-swept-wing/canard configuration was investigated. The program can simulate nonlinear effects including boundary-layer displacement thickness, wake roll up, and to a limited extent, separated wakes. The predictions were compared with experimental data obtained using a small-scale model in the 7- by 10- Foot Wind Tunnel at NASA Ames Research Center. For the particular configuration under investigation, wake roll up had only a small effect on the force and moment predictions. The effect of the displacement thickness modeling was to reduce the lift curve slope slightly, thus bringing the predicted lift into good agreement with the measured value. Pitching moment predictions were also improved by the boundary-layer simulation. The separation modeling was found to be sensitive to user inputs, but appears to give a reasonable representation of a separated wake. In general, the nonlinear capabilities of the code were found to improve the agreement with experimental data. The usefullness of the code would be enhanced by improving the reliability of the separated wake modeling and by the addition of a leading edge separation model.

  10. Nonlinear effect in vibroseis data; Vibroseis kiroku ni oite mitomerareru hisenkei koka

    Energy Technology Data Exchange (ETDEWEB)

    Saeki, T [Japan National Oil Corp., Tokyo (Japan)

    1997-05-27

    This paper describes nonlinear effect recognized in Vibroseis data. Harmonics is a wave of frequency in integer factors generated in association with basic sweep vibrated by Vibroseis. Harmonics is generated because vibration in the vicinity of seismic source contains nonlinear terms. Seismic exploration using the reflection method often discusses propagation of seismic waves hypothesized as a linear phenomenon. Vibroseis data analysis, however, requires evaluation of the effect of the harmonics on accuracy. Vibroseis investigation measures may be taken by eliminating n-order harmonics by using the phase control method, and generating seismic source sweep in which the phase is shifted by 180/(n-1) each time in order to leave the basic sweep. Methods to increase the sweep length include a method to expel strain to a location outside the range of the subject travel time. Up-sweep (a sweep changing from low frequencies to higher frequencies) is also a means capable of avoiding harmonics effects. Vibroseis investigations currently performed adopt this method frequently because of it having little technological and economic problems. 10 refs., 3 figs.

  11. Nonlinear thermal convection in a layer of nanofluid under G-jitter and internal heating effects

    Directory of Open Access Journals (Sweden)

    Bhadauria B. S.

    2014-01-01

    Full Text Available This paper deals with a mathematical model of controlling heat transfer in nanofluids. The time-periodic vertical vibrations of the system are considered to effect an external control of heat transport along with internal heating effects. A weakly non-linear stability analysis is based on the five-mode Lorenz model using which the Nusselt number is obtained as a function of the thermal Rayleigh number, nano-particle concentration based Rayleigh number, Prandtl number, Lewis number, modified diffusivity ratio, amplitude and frequency of modulation. It is shown that modulation can be effectively used to control convection and thereby heat transport. Further, it is found that the effect of internal Rayleigh number is to enhance the heat and nano-particles transport.

  12. Non-linear phonon Peltier effect in dissipative quantum dot systems.

    Science.gov (United States)

    De, Bitan; Muralidharan, Bhaskaran

    2018-03-26

    Solid state thermoelectric cooling is based on the electronic Peltier effect, which cools via an electronic heat current in the absence of an applied temperature gradient. In this work, we demonstrate that equivalently, a phonon Peltier effect may arise in the non-linear thermoelectric transport regime of a dissipative quantum dot thermoelectric setup described via Anderson-Holstein model. This effect leads to an electron induced phonon heat current in the absence of a thermal gradient. Utilizing the modification of quasi-equilibrium phonon distribution via charge induced phonon accumulation, we show that in a special case the polarity of the phonon heat current can be reversed so that setup can dump heat into the hotter reservoirs. In further exploring possibilities that can arise from this effect, we propose a novel charge-induced phonon switching mechanism that may be incited via electrostatic gating.

  13. Two-fluid and nonlinear effects of tearing and pressure-driven resistive modes in reversed field pinches

    International Nuclear Information System (INIS)

    Mirnov, V.V.

    2002-01-01

    Large-scale tearing instabilities have long been considered to underlie transport and dynamo processes in the reversed field pinch (RFP). The vast majority of theoretical and computational RFP work has focused on pressureless, single-fluid MHD in cylindrical plasmas driven solely by a toroidal electric field. We report results of five investigations covering two-fluid dynamos, toroidal nonlinear MHD computation, nonlinear computation of Oscillating Field Current Drive (OFCD), the effect of shear flow on tearing instability, and the effect of pressure on resistive instability. The key findings are: (1) two-fluid dynamo arising from the Hall term is much larger than the standard MHD dynamo present in a single-fluid treatment, (2) geometric coupling from toroidicity precludes the occurrence of laminar single helicity states, except for nonreversed plasmas, (3) OFCD, a form of AC helicity injection, can sustain the RFP plasma current, although magnetic fluctuations are enhanced, (4) edge shear flow can destabilize the edge resonant m=0 modes, which occur as spikes in experiment, and (5) pressure driven modes are resistive at low beta, only becoming ideal at extremely high beta. (author)

  14. Suppression of the Nonlinear Zeeman Effect and Heading Error in Earth-Field-Range Alkali-Vapor Magnetometers.

    Science.gov (United States)

    Bao, Guzhi; Wickenbrock, Arne; Rochester, Simon; Zhang, Weiping; Budker, Dmitry

    2018-01-19

    The nonlinear Zeeman effect can induce splitting and asymmetries of magnetic-resonance lines in the geophysical magnetic-field range. This is a major source of "heading error" for scalar atomic magnetometers. We demonstrate a method to suppress the nonlinear Zeeman effect and heading error based on spin locking. In an all-optical synchronously pumped magnetometer with separate pump and probe beams, we apply a radio-frequency field which is in phase with the precessing magnetization. This results in the collapse of the multicomponent asymmetric magnetic-resonance line with ∼100  Hz width in the Earth-field range into a single peak with a width of 22 Hz, whose position is largely independent of the orientation of the sensor within a range of orientation angles. The technique is expected to be broadly applicable in practical magnetometry, potentially boosting the sensitivity and accuracy of Earth-surveying magnetometers by increasing the magnetic-resonance amplitude, decreasing its width, and removing the important and limiting heading-error systematic.

  15. Nonlinearity effect of electro-optical modulator response in double spread CDMA radio-over-fiber transmissions

    Science.gov (United States)

    Huang, Jen-Fa; Yen, Chih-Ta; Li, Tzung-Yen

    2008-07-01

    This study presents a double-spread code-division multiple-access (CDMA) scheme for radio-over-fiber (RoF) transmissions. The network coder/decoders (codecs) are implemented using arrayed-waveguide grating (AWG) routers coded with maximal-length sequence ( M-sequence) codes. The effects of phase-induced intensity noise (PIIN) and multiple-access interference (MAI) on the system performance are evaluated numerically for different values of the optical modulation index (OMI) during the nonlinear electro-optical modulator (EOM) response. At low OMI optical device noise is dominant, but at high OMI nonlinear effect becomes significant. Numerical result shows that the system performance is highly sensitive to the OMI. Therefore, specifying an appropriate value of the OMI is essential in optimizing the system performance. The influence of the degree of polarization (DOP) in the system is also discussed. By employing the scrambler in front of the balanced photo-detector, the system performance can be enhanced. The high-performance, low-cost characteristics of the double-spread CDMA render the scheme an ideal solution for radio-CDMA wireless system cascaded with optical CDMA network.

  16. Suppression of the Nonlinear Zeeman Effect and Heading Error in Earth-Field-Range Alkali-Vapor Magnetometers

    Science.gov (United States)

    Bao, Guzhi; Wickenbrock, Arne; Rochester, Simon; Zhang, Weiping; Budker, Dmitry

    2018-01-01

    The nonlinear Zeeman effect can induce splitting and asymmetries of magnetic-resonance lines in the geophysical magnetic-field range. This is a major source of "heading error" for scalar atomic magnetometers. We demonstrate a method to suppress the nonlinear Zeeman effect and heading error based on spin locking. In an all-optical synchronously pumped magnetometer with separate pump and probe beams, we apply a radio-frequency field which is in phase with the precessing magnetization. This results in the collapse of the multicomponent asymmetric magnetic-resonance line with ˜100 Hz width in the Earth-field range into a single peak with a width of 22 Hz, whose position is largely independent of the orientation of the sensor within a range of orientation angles. The technique is expected to be broadly applicable in practical magnetometry, potentially boosting the sensitivity and accuracy of Earth-surveying magnetometers by increasing the magnetic-resonance amplitude, decreasing its width, and removing the important and limiting heading-error systematic.

  17. Non-linear effects of the U.S. Monetary Policy in the Long Run

    OpenAIRE

    Olmos, Lorena; Sanso Frago, Marcos

    2014-01-01

    We find non-linearities in the U.S. long-run relationships among trend inflation, growth rate and financial frictions. Moreover, our results show that mismeasurements of the natural rate of interest deviate the trend inflation from its target, which is especially clear when monetary policy reacts preventively against inflation deviations. The long-run growth rate, the trend inflation and the natural rate of interest, specified as time-varying, are jointly estimated over the period 1960:Q1-201...

  18. Donor impurity states and related terahertz range nonlinear optical response in GaN cylindrical quantum wires: Effects of external electric and magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Correa, J. D. [Departamento de Ciencias Básicas, Universidad de Medellín, Medellín (Colombia); Mora-Ramos, M. E., E-mail: memora@uaem.mx [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca, Morelos (Mexico); Duque, C. A. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)

    2014-06-07

    We report a study on the optical absorption coefficient associated to hydrogenic impurity interstate transitions in zinc-blende GaN quantum wires of cylindrical shape taking into account the effects of externally applied static electric and magnetic fields. The electron states emerge within the effective mass approximation, via the exact diagonalization of the donor-impurity Hamiltonian with parabolic confinement and external field effects. The nonlinear optical absorption is calculated using a recently derived expression for the dielectric susceptibility, obtained via a nonperturbative solution of the density-matrix Bloch equation. Our results show that this treatment eliminates not only the intensity-dependent bleaching effect but also the change in sign of the nonlinear contribution due to the combined effect of asymmetric impurity location and the applied electric field.

  19. Nonlinear analysis of reinforced concrete beam with/without tension stiffening effect

    International Nuclear Information System (INIS)

    Dede, T.; Ayvaz, Y.

    2009-01-01

    The aim of this paper is to do materially nonlinear failure analysis of RC beam by using finite element method. In the finite element modeling, two different approaches and different tension stress-strain models with/without tension stiffening effect are used by considering two different mesh sizes. In the first approach, the material matrices of concrete and reinforcement are constructed separately, and then superimposed to obtain the element stiffness matrix. In the second approach, the reinforcement is assumed to be uniformly distributed throughout the beam. So, the beam is modeled as a single composite element with increasing the modulus of elasticity of concrete by considering the reinforcement ratio. For these two approaches, elastic-perfectly plastic stress-strain relationship is used for concrete in compression. For the concrete in tension, a stress-strain relationship with/without tension stiffening is used. It is concluded that the approaches and the models considered in this study can be effectively used in the materially nonlinear analysis of RC beams.

  20. High-sensitivity dc field magnetometer using nonlinear resonance magnetoelectric effect

    International Nuclear Information System (INIS)

    Burdin, D.A.; Chashin, D.V.; Ekonomov, N.A.; Fetisov, Y.K.; Stashkevich, A.A.

    2016-01-01

    The design and operation principle of dc field magnetometer using nonlinear resonance magnetoelectric effect in a ferromagnetic–piezoelectric structure are described. It is shown that under action of ac pumping magnetic field the structure generates the output voltage containing higher harmonics whose amplitudes depend on the dc magnetic field. Best performance of the device is obtained if the signal of the third harmonics is used for the dc field measurement. The sensitivity can be considerably (by approximately three orders of magnitude) increased if advantage is taken of the acoustic resonance of the structure at this frequency. There exists the optimal pumping field ensuring the highest sensitivity. Further increasing of this field expands the range of measurable dc fields at the expense of deteriorated sensitivity. The magnetometer fabricated on the basis of a planar langatate-Metglas structure had sensitivity up to ~1 V/Oe and allowed detection of the fields as low as ~10"−"5 Oe. - Highlights: • Operational principle and design of new type dc field magnetometer is described. • Magnetometer uses nonlinear magnetoelectric effect in a langatate-Metglas structure. • Magnetometer has sensitivity of ~1 V/Oe and detects fields as low as 10"−"5 Oe. • The proposed magnetometer can compete with well known fluxgate sensors.

  1. High-sensitivity dc field magnetometer using nonlinear resonance magnetoelectric effect

    Energy Technology Data Exchange (ETDEWEB)

    Burdin, D.A.; Chashin, D.V.; Ekonomov, N.A. [Moscow State University of Information Technologies, Radio Engineering and Electronics, Moscow (Russian Federation); Fetisov, Y.K., E-mail: fetisov@mirea.ru [Moscow State University of Information Technologies, Radio Engineering and Electronics, Moscow (Russian Federation); Stashkevich, A.A. [LSPM (CNRS-UPR 3407), Université Paris 13, Sorbonne Paris Cité, 93430 Villetaneuse (France)

    2016-05-01

    The design and operation principle of dc field magnetometer using nonlinear resonance magnetoelectric effect in a ferromagnetic–piezoelectric structure are described. It is shown that under action of ac pumping magnetic field the structure generates the output voltage containing higher harmonics whose amplitudes depend on the dc magnetic field. Best performance of the device is obtained if the signal of the third harmonics is used for the dc field measurement. The sensitivity can be considerably (by approximately three orders of magnitude) increased if advantage is taken of the acoustic resonance of the structure at this frequency. There exists the optimal pumping field ensuring the highest sensitivity. Further increasing of this field expands the range of measurable dc fields at the expense of deteriorated sensitivity. The magnetometer fabricated on the basis of a planar langatate-Metglas structure had sensitivity up to ~1 V/Oe and allowed detection of the fields as low as ~10{sup −5} Oe. - Highlights: • Operational principle and design of new type dc field magnetometer is described. • Magnetometer uses nonlinear magnetoelectric effect in a langatate-Metglas structure. • Magnetometer has sensitivity of ~1 V/Oe and detects fields as low as 10{sup −5} Oe. • The proposed magnetometer can compete with well known fluxgate sensors.

  2. Effect of nonlinear wave-particle interaction on electron-cyclotron absorption

    Energy Technology Data Exchange (ETDEWEB)

    Tsironis, C; Vlahos, L [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2006-09-15

    We perform a self-consistent analysis of the nonlinear interaction of magnetized plasmas with electron-cyclotron (EC) waves. A closed set of equations is derived, which consists of the relativistic equations of motion under the wave field and the wave equation for the vector potential. The plasma is described in terms of ensembles of electrons which collectively determine the evolution of the wave amplitude and frequency through the current response. This description allows for effects of the electron motions on the efficiency of the wave absorption, for example, the asynchrony between the wave phase and the gyroperiod. As an application, we study the absorption of an EC wave beam in a simplified tokamak geometry, for plasma parameters relevant to current and future fusion experiments. We conclude that, within the limits of our model, there are cases where the linear theory for the absorption of EC waves, used widely in the current literature, may overestimate the energy deposition. In such cases, nonlinear effects are essential for the accurate estimation of the plasma-wave coupling and their inclusion should be considered, especially when the wave power is dramatically increased as in the case of ITER.

  3. Effect of nonlinear wave-particle interaction on electron-cyclotron absorption

    International Nuclear Information System (INIS)

    Tsironis, C; Vlahos, L

    2006-01-01

    We perform a self-consistent analysis of the nonlinear interaction of magnetized plasmas with electron-cyclotron (EC) waves. A closed set of equations is derived, which consists of the relativistic equations of motion under the wave field and the wave equation for the vector potential. The plasma is described in terms of ensembles of electrons which collectively determine the evolution of the wave amplitude and frequency through the current response. This description allows for effects of the electron motions on the efficiency of the wave absorption, for example, the asynchrony between the wave phase and the gyroperiod. As an application, we study the absorption of an EC wave beam in a simplified tokamak geometry, for plasma parameters relevant to current and future fusion experiments. We conclude that, within the limits of our model, there are cases where the linear theory for the absorption of EC waves, used widely in the current literature, may overestimate the energy deposition. In such cases, nonlinear effects are essential for the accurate estimation of the plasma-wave coupling and their inclusion should be considered, especially when the wave power is dramatically increased as in the case of ITER

  4. Nonlinear and diffraction effects in propagation of N-waves in randomly inhomogeneous moving media.

    Science.gov (United States)

    Averiyanov, Mikhail; Blanc-Benon, Philippe; Cleveland, Robin O; Khokhlova, Vera

    2011-04-01

    Finite amplitude acoustic wave propagation through atmospheric turbulence is modeled using a Khokhlov-Zabolotskaya-Kuznetsov (KZK)-type equation. The equation accounts for the combined effects of nonlinearity, diffraction, absorption, and vectorial inhomogeneities of the medium. A numerical algorithm is developed which uses a shock capturing scheme to reduce the number of temporal grid points. The inhomogeneous medium is modeled using random Fourier modes technique. Propagation of N-waves through the medium produces regions of focusing and defocusing that is consistent with geometrical ray theory. However, differences up to ten wavelengths are observed in the locations of fist foci. Nonlinear effects are shown to enhance local focusing, increase the maximum peak pressure (up to 60%), and decrease the shock rise time (about 30 times). Although the peak pressure increases and the rise time decreases in focal regions, statistical analysis across the entire wavefront at a distance 120 wavelengths from the source indicates that turbulence: decreases the mean time-of-flight by 15% of a pulse duration, decreases the mean peak pressure by 6%, and increases the mean rise time by almost 100%. The peak pressure and the arrival time are primarily governed by large scale inhomogeneities, while the rise time is also sensitive to small scales.

  5. Nonlinear excitations in biomolecules

    International Nuclear Information System (INIS)

    Peyrard, M.

    1995-01-01

    The aim of the workshop entitled ''Nonlinear Excitations in Biomolecules'' is to attempt to bridge the gap between the physicists and biologists communities which is mainly due to language and cultural barriers. The progress of nonlinear science in the last few decades which have shown that the combination of nonlinearity, which characterize most biological phenomena, and cooperative effects in a system having a large number of degrees of freedom, can give rise to coherent excitations with remarkable properties. New concepts, such as solitons nd nonlinear energy localisation have become familiar to physicists and applied mathematicians. It is thus tempting to make an analogy between these coherent excitations and the exceptional stability of some biological processes, such as for instance DNA transcription, which require the coordination of many events in the ever changing environment of a cell. Physicists are now invoking nonlinear excitations to describe and explain many bio-molecular processes while biologists often doubt that the seemingly infinite variety of phenomena that they are attempting to classify can be reduced to such simple concepts. A large part of the meeting is devoted to tutorial lectures rather than to latest research results. The book provides a pedagogical introduction to the two topics forming the backbone of the meeting: the theory of nonlinear excitations and solitons, and their application in biology; and the structure and function of biomolecules, as well as energy and charge transport in biophysics. In order to emphasize the link between physics and biology, the volume is not divided along these two topics but according to biological subjects. Each chapter starts with a short introduction attempting to help the reader to find his way among the contributions and point out the connection between them. 23 lectures over the 32 presented have been selected and refers to quantum properties of macro-molecules. (J.S.)

  6. Probability of atrial fibrillation after ablation: Using a parametric nonlinear temporal decomposition mixed effects model.

    Science.gov (United States)

    Rajeswaran, Jeevanantham; Blackstone, Eugene H; Ehrlinger, John; Li, Liang; Ishwaran, Hemant; Parides, Michael K

    2018-01-01

    Atrial fibrillation is an arrhythmic disorder where the electrical signals of the heart become irregular. The probability of atrial fibrillation (binary response) is often time varying in a structured fashion, as is the influence of associated risk factors. A generalized nonlinear mixed effects model is presented to estimate the time-related probability of atrial fibrillation using a temporal decomposition approach to reveal the pattern of the probability of atrial fibrillation and their determinants. This methodology generalizes to patient-specific analysis of longitudinal binary data with possibly time-varying effects of covariates and with different patient-specific random effects influencing different temporal phases. The motivation and application of this model is illustrated using longitudinally measured atrial fibrillation data obtained through weekly trans-telephonic monitoring from an NIH sponsored clinical trial being conducted by the Cardiothoracic Surgery Clinical Trials Network.

  7. Nonlinear Effects of Remittances on Per Capita GDP Growth in Bangladesh

    Directory of Open Access Journals (Sweden)

    Gazi Mainul Hassan

    2017-07-01

    Full Text Available This paper examines the impact of inward remittances flows on per capita gross domestic product (GDP growth in Bangladesh during 1976–2012. We find that the growth effect of remittances is negative at first but becomes positive at a later stage, evidence of a non-linear relationship. Unproductive use of remittances was rampant in the beginning when they were received by migrant families, but better social and economic investments led to more productive utilization of remittances receipts at later periods. This suggests a U-shaped relationship between remittances and per capita GDP growth. Unlike what is suggested in the literature, that the effect of remittances is more pronounced in a less financially developed economy, our evidence does not show that the effect of remittances on per capita GDP growth in Bangladesh is conditional on the level of financial development.

  8. No-Reference Stereoscopic IQA Approach: From Nonlinear Effect to Parallax Compensation

    Directory of Open Access Journals (Sweden)

    Ke Gu

    2012-01-01

    Full Text Available The last decade has seen a booming of the applications of stereoscopic images/videos and the corresponding technologies, such as 3D modeling, reconstruction, and disparity estimation. However, only a very limited number of stereoscopic image quality assessment metrics was proposed through the years. In this paper, we propose a new no-reference stereoscopic image quality assessment algorithm based on the nonlinear additive model, ocular dominance model, and saliency based parallax compensation. Our studies using the Toyama database result in three valuable findings. First, quality of the stereoscopic image has a nonlinear relationship with a direct summation of two monoscopic image qualities. Second, it is a rational assumption that the right-eye response has the higher impact on the stereoscopic image quality, which is based on a sampling survey in the ocular dominance research. Third, the saliency based parallax compensation, resulted from different stereoscopic image contents, is considerably valid to improve the prediction performance of image quality metrics. Experimental results confirm that our proposed stereoscopic image quality assessment paradigm has superior prediction accuracy as compared to state-of-the-art competitors.

  9. Unidirectional reflection and invisibility in nonlinear media with an incoherent nonlinearity

    Science.gov (United States)

    Mostafazadeh, Ali; Oflaz, Neslihan

    2017-11-01

    We give explicit criteria for the reflectionlessness, transparency, and invisibility of a finite-range potential in the presence of an incoherent (intensity-dependent) nonlinearity that is confined to the range of the potential. This allows us to conduct a systematic study of the effects of such a nonlinearity on a locally periodic class of finite-range potentials that display perturbative unidirectional invisibility. We use our general results to examine the effects of a weak Kerr nonlinearity on the behavior of these potentials and show that the presence of nonlinearity destroys the unidirectional invisibility of these potentials. If the strength of the Kerr nonlinearity is so weak that the first-order perturbation theory is reliable, the presence of nonlinearity does not affect the unidirectional reflectionlessness and transmission reciprocity of the potential. We show that the expected violation of the latter is a second order perturbative effect.

  10. Analysis and compensation for the joint effects of HPA nonlinearity, I/Q imbalance and crosstalk in MIMO beamforming systems

    KAUST Repository

    Qi, Jian

    2011-03-01

    In this paper, we investigate the joint effects of high-power amplifier (HPA) nonlinearity, in-phase/quadrature-phase (I/Q) imbalance and crosstalk, on the performance of multiple-input multiple-output (MIMO) transmit beamforming (TB) systems, and propose a compensation method for the three impairments together. The performance of the MIMO TB system equipped with the proposed compensation scheme is evaluated in terms of average symbol error probability and capacity when transmissions are performed over uncorrelated Rayleigh fading channels. Numerical results are provided and show the effects on performance of several system parameters, namely, the HPA parameters, image-leakage ratio, crosstalk, numbers of antennas, length of pilot symbols and phase-shift keying modulation order. © 2011 IEEE.

  11. Effects of geometric nonlinearity in an adhered microbeam for measuring the work of adhesion

    Science.gov (United States)

    Fang, Wenqiang; Mok, Joyce; Kesari, Haneesh

    2018-03-01

    Design against adhesion in microelectromechanical devices is predicated on the ability to quantify this phenomenon in microsystems. Previous research related the work of adhesion for an adhered microbeam to the beam's unadhered length, and as such, interferometric techniques were developed to measure that length. We propose a new vibration-based technique that can be easily implemented with existing atomic force microscopy tools or similar metrology systems. To make such a technique feasible, we analysed a model of the adhered microbeam using the nonlinear beam theory put forth by Woinowsky-Krieger. We found a new relation between the work of adhesion and the unadhered length; this relation is more accurate than the one by Mastrangelo & Hsu (Mastrangelo & Hsu 1993 J. Microelectromech. S., 2, 44-55. (doi:10.1109/84.232594)) which is commonly used. Then, we derived a closed-form approximate relationship between the microbeam's natural frequency and its unadhered length. Results obtained from this analytical formulation are in good agreement with numerical results from three-dimensional nonlinear finite-element analysis.

  12. Non-linear effects of drought under shade: reconciling physiological and ecological models in plant communities.

    Science.gov (United States)

    Holmgren, Milena; Gómez-Aparicio, Lorena; Quero, José Luis; Valladares, Fernando

    2012-06-01

    The combined effects of shade and drought on plant performance and the implications for species interactions are highly debated in plant ecology. Empirical evidence for positive and negative effects of shade on the performance of plants under dry conditions supports two contrasting theoretical models about the role of shade under dry conditions: the trade-off and the facilitation hypotheses. We performed a meta-analysis of field and greenhouse studies evaluating the effects of drought at two or more irradiance levels on nine response variables describing plant physiological condition, growth, and survival. We explored differences in plant response across plant functional types, ecosystem types and methodological approaches. The data were best fit using quadratic models indicating a humped-back shape response to drought along an irradiance gradient for survival, whole plant biomass, maximum photosynthetic capacity, stomatal conductance and maximal photochemical efficiency. Drought effects were ameliorated at intermediate irradiance, becoming more severe at higher or lower light levels. This general pattern was maintained when controlling for potential variations in the strength of the drought treatment among light levels. Our quantitative meta-analysis indicates that dense shade ameliorates drought especially among drought-intolerant and shade-tolerant species. Wet tropical species showed larger negative effects of drought with increasing irradiance than semiarid and cold temperate species. Non-linear responses to irradiance were stronger under field conditions than under controlled greenhouse conditions. Non-linear responses to drought along the irradiance gradient reconciliate opposing views in plant ecology, indicating that facilitation is more likely within certain range of environmental conditions, fading under deep shade, especially for drought-tolerant species.

  13. Effect of initial chirp on near-infrared supercontinuum generation by a nanosecond pulse in a nonlinear fiber amplifier

    International Nuclear Information System (INIS)

    Song Rui; Hou Jing; Wang Ze-Feng; Lu Qi-Sheng; Xiao Rui

    2013-01-01

    Theoretical and experimental research on the effect of initial chirp on near-infrared supercontinuum generation by a nanosecond pulse in a nonlinear fiber amplifier is carried out. The complex Ginzburg—Landau equation is used to simulate the propagation of the pulse in the fiber amplifier and the results show that pulses with negative initial chirp produce the widest supercontinuum and pulses with positive initial chirp produce the narrowest supercontinuum when the central wavelength of the pump lies in the normal dispersion region of the gain fiber. A self-made line width narrowing system is utilized to control the initial chirp of the nanosecond pump pulse and a four-stage master oscillator power amplifier configuration is adopted to produce a high power near-infrared suppercontinuum. The experimental results are in good agreement with simulations which can provide some guidance on further optimization of the system in future work. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  14. Effects of magnetic non-linearities on a stored proton beam and their implications for superconducting storage rings

    International Nuclear Information System (INIS)

    Cornacchia, M.; Evans, L.

    1985-06-01

    A nonlinear lens may be used to study the effect of high-order multipolar field imperfections on a stored proton beam. Such a nonlinear lens is particulary suitable to simulate field imperfections of the types encountered in coil dominated superconducting magnets. We have studied experimentally at the SPS the effect of high order (5th and 8th) single isolated resonances driven by the nonlinear lens. The width of these resonances is of the order one expects to be caused by field errors in superconducting magnets of the SSC type. The experiment shows that, in absence of tune modulation, these resonances are harmless. Slow crossings of the resonance, on the other hand, have destructive effects on the beam, much more so than fast crossings caused by synchrotron oscillations. In the design of future storage rings, sources of low-frequency tune modulation should be avoided as a way to reduce the harmful effects of high order multipolar field imperfection

  15. Analytical results for a conditional phase shift between single-photon pulses in a nonlocal nonlinear medium

    Science.gov (United States)

    Viswanathan, Balakrishnan; Gea-Banacloche, Julio

    2018-03-01

    It has been suggested that second-order nonlinearities could be used for quantum logic at the single-photon level. Specifically, successive two-photon processes in principle could accomplish the phase shift (conditioned on the presence of two photons in the low-frequency modes) |011 〉→i |100 〉→-|011 〉 . We have analyzed a recent scheme proposed by Xia et al. [Phys. Rev. Lett. 116, 023601 (2016)], 10.1103/PhysRevLett.116.023601 to induce such a conditional phase shift between two single-photon pulses propagating at different speeds through a nonlinear medium with a nonlocal response. We present here an analytical solution for the most general case, i.e., for an arbitrary response function, initial state, and pulse velocity, which supports their numerical observation that a π phase shift with unit fidelity is possible, in principle, in an appropriate limit. We also discuss why this is possible in this system, despite the theoretical objections to the possibility of conditional phase shifts on single photons that were raised some time ago by Shapiro [Phys. Rev. A 73, 062305 (2006)], 10.1103/PhysRevA.73.062305 and by Gea-Banacloche [Phys. Rev. A 81, 043823 (2010)], 10.1103/PhysRevA.81.043823 one of us.

  16. Parameterisation effect on the behaviour of a head-dependent hydro chain using a nonlinear model

    International Nuclear Information System (INIS)

    Catalao, J.P.S.; Mariano, S.J.P.S.; Mendes, V.M.F.; Ferreira, L.A.F.M.

    2006-01-01

    This paper is on the problem of short-term hydro scheduling (STHS), particularly concerning a head-dependent hydro chain. We use a method based on nonlinear programming (NLP), namely quadratic programming, to consider hydroelectric power generation a function of water discharge and of the head. The method has been applied successfully to solve a test case based on a realistic cascaded hydro system with a negligible computational time requirement and is also applied to show that the role played by reservoirs in the hydro chain do not depend only on their relative position. As a new contribution to earlier studies, which presented reservoir operation rules mainly for medium and long-term planning procedures, we show that the physical data defining hydro chain parameters used in the nonlinear model have an effect on the STHS, implying different optimal storage trajectories for the reservoirs accordingly not only with their position in the hydro chain but also with the new parameterisation defining the data for the hydro system. Moreover, considering head dependency in the hydroelectric power generation, usually neglected for hydro plants with a large storage capacity, provides a better short-term management of the conversion of the potential energy available in the reservoirs into electric energy, which represents a major advantage for the hydroelectric utilities in a competitive electricity market. (author)

  17. Effects of periodic modulation on the nonlinear Landau–Zener tunneling

    International Nuclear Information System (INIS)

    Li-Hua, Wu; Wen-Shan, Duan

    2009-01-01

    We study the Landau–Zener tunneling of a nonlinear two-level system by applying a periodic modulation on its energy bias. We find that the two levels are splitting at the zero points of the zero order Bessel function for high-frequency modulation. Moreover, we obtain the effective coupling constant between two levels at the zero points of the zero order Bessel function by calculating the final tunneling probability at these points. It seems that the effective coupling constant can be regarded as the approximation of the higher order Bessel function at these points. For the low-frequency modulation, we find that the final tunneling probability is a function of the interaction strength. For the weak inter-level coupling case, we find that the final tunneling probability is more disordered as the interaction strength becomes larger. (general)

  18. Cost-effective degradation test plan for a nonlinear random-coefficients model

    International Nuclear Information System (INIS)

    Kim, Seong-Joon; Bae, Suk Joo

    2013-01-01

    The determination of requisite sample size and the inspection schedule considering both testing cost and accuracy has been an important issue in the degradation test. This paper proposes a cost-effective degradation test plan in the context of a nonlinear random-coefficients model, while meeting some precision constraints for failure-time distribution. We introduce a precision measure to quantify the information losses incurred by reducing testing resources. The precision measure is incorporated into time-varying cost functions to reflect real circumstances. We apply a hybrid genetic algorithm to general cost optimization problem with reasonable constraints on the level of testing precision in order to determine a cost-effective inspection scheme. The proposed method is applied to the degradation data of plasma display panels (PDPs) following a bi-exponential degradation model. Finally, sensitivity analysis via simulation is provided to evaluate the robustness of the proposed degradation test plan.

  19. A Method to Construct Plasma with Nonlinear Density Enhancement Effect in Multiple Internal Inductively Coupled Plasmas

    International Nuclear Information System (INIS)

    Chen Zhipeng; Li Hong; Liu Qiuyan; Luo Chen; Xie Jinlin; Liu Wandong

    2011-01-01

    A method is proposed to built up plasma based on a nonlinear enhancement phenomenon of plasma density with discharge by multiple internal antennas simultaneously. It turns out that the plasma density under multiple sources is higher than the linear summation of the density under each source. This effect is helpful to reduce the fast exponential decay of plasma density in single internal inductively coupled plasma source and generating a larger-area plasma with multiple internal inductively coupled plasma sources. After a careful study on the balance between the enhancement and the decay of plasma density in experiments, a plasma is built up by four sources, which proves the feasibility of this method. According to the method, more sources and more intensive enhancement effect can be employed to further build up a high-density, large-area plasma for different applications. (low temperature plasma)

  20. Diagnostic tool for structural health monitoring: effect of material nonlinearity and vibro-impact process

    Science.gov (United States)

    Hiwarkar, V. R.; Babitsky, V. I.; Silberschmidt, V. V.

    2013-07-01

    Numerous techniques are available for monitoring structural health. Most of these techniques are expensive and time-consuming. In this paper, vibration-based techniques are explored together with their use as diagnostic tools for structural health monitoring. Finite-element simulations are used to study the effect of material nonlinearity on dynamics of a cracked bar. Additionally, several experiments are performed to study the effect of vibro-impact behavior of crack on its dynamics. It was observed that a change in the natural frequency of the cracked bar due to crack-tip plasticity and vibro-impact behavior linked to interaction of crack faces, obtained from experiments, led to generation of higher harmonics; this can be used as a diagnostic tool for structural health monitoring.

  1. Extremely Large Magnetoresistance at Low Magnetic Field by Coupling the Nonlinear Transport Effect and the Anomalous Hall Effect.

    Science.gov (United States)

    Luo, Zhaochu; Xiong, Chengyue; Zhang, Xu; Guo, Zhen-Gang; Cai, Jianwang; Zhang, Xiaozhong

    2016-04-13

    The anomalous Hall effect of a magnetic material is coupled to the nonlinear transport effect of a semiconductor material in a simple structure to achieve a large geometric magnetoresistance (MR) based on a diode-assisted mechanism. An extremely large MR (>10(4) %) at low magnetic fields (1 mT) is observed at room temperature. This MR device shows potential for use as a logic gate for the four basic Boolean logic operations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Numerical study of surface plasmon enhanced nonlinear absorption and refraction.

    Science.gov (United States)

    Kohlgraf-Owens, Dana C; Kik, Pieter G

    2008-07-07

    Maxwell Garnett effective medium theory is used to study the influence of silver nanoparticle induced field enhancement on the nonlinear response of a Kerr-type nonlinear host. We show that the composite nonlinear absorption coefficient, beta(c), can be enhanced relative to the host nonlinear absorption coefficient near the surface plasmon resonance of silver nanoparticles. This enhancement is not due to a resonant enhancement of the host nonlinear absorption, but rather due to a phase shifted enhancement of the host nonlinear refractive response. The enhancement occurs at the expense of introducing linear absorption, alpha(c), which leads to an overall reduced figure of merit beta(c)/alpha(c) for nonlinear absorption. For thin (< 1 microm) composites, the use of surface plasmons is found to result in an increased nonlinear absorption response compared to that of the host material.

  3. Effects of delayed nonlinear response on wave packet dynamics in one-dimensional generalized Fibonacci chains

    International Nuclear Information System (INIS)

    Zhang, Jianxin; Zhang, Zhenjun; Tong, Peiqing

    2013-01-01

    We investigate the spreading of an initially localized wave packet in one-dimensional generalized Fibonacci (GF) lattices by solving numerically the discrete nonlinear Schrödinger equation (DNLSE) with a delayed cubic nonlinear term. It is found that for short delay time, the wave packet is self-trapping in first class of GF lattices, that is, the second moment grows with time, but the corresponding participation number does not grow. However, both the second moment and the participation number grow with time for large delay time. This illuminates that the wave packet is delocalized. For the second class of GF lattices, the dynamic behaviors of wave packet depend on the strength of on-site potential. For a weak on-site potential, the results are similar to the case of the first class. For a strong on-site potential, both the second moment and the participation number does not grow with time in the regime of short delay time. In the regime of large delay time, both the second moment and the participation number exhibit stair-like growth

  4. Effects of delayed nonlinear response on wave packet dynamics in one-dimensional generalized Fibonacci chains

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jianxin; Zhang, Zhenjun [Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023 (China); Tong, Peiqing, E-mail: pqtong@njnu.edu.cn [Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems, Nanjing Normal University, Nanjing 210023 (China)

    2013-07-15

    We investigate the spreading of an initially localized wave packet in one-dimensional generalized Fibonacci (GF) lattices by solving numerically the discrete nonlinear Schrödinger equation (DNLSE) with a delayed cubic nonlinear term. It is found that for short delay time, the wave packet is self-trapping in first class of GF lattices, that is, the second moment grows with time, but the corresponding participation number does not grow. However, both the second moment and the participation number grow with time for large delay time. This illuminates that the wave packet is delocalized. For the second class of GF lattices, the dynamic behaviors of wave packet depend on the strength of on-site potential. For a weak on-site potential, the results are similar to the case of the first class. For a strong on-site potential, both the second moment and the participation number does not grow with time in the regime of short delay time. In the regime of large delay time, both the second moment and the participation number exhibit stair-like growth.

  5. Distributed nonlinear optical response

    DEFF Research Database (Denmark)

    Nikolov, Nikola Ivanov

    2005-01-01

    of bound states of out of phase bright solitons and dark solitons. Also, the newly introduced analogy between the nonlocal cubic nonlinear and the quadratic nonlinear media, presented in paper B and Chapter 3 is discussed. In particular it supplies intuitive physical meaning of the formation of solitons...... in quadratic nonlinear media. In the second part of the report (Chapter 4), the possibility to obtain light with ultrabroad spectrum due to the interplay of many nonlinear effects based on cubic nonlinearity is investigated thoroughly. The contribution of stimulated Raman scattering, a delayed nonlinear...... a modified nonlinear Schroedinger model equation. Chapter 4 and papers D and E are dedicated to this part of the research....

  6. Stagnation point flow and heat transfer over a nonlinear shrinking sheet with slip effects

    Directory of Open Access Journals (Sweden)

    N.F. Fauzi

    2015-12-01

    Full Text Available In this paper, an investigation is performed to analyze the effects of the slip parameters A and B on the steady stagnation-point flow and heat transfer due to a shrinking sheet in a viscous and incompressible fluid. Using similarity transformations, the governing boundary layer equations are transformed into the nonlinear ordinary (similar differential equations. The transformed equations are solved numerically using the shooting method. The dual solutions for velocity and temperature distribution exist for certain values of the positive constant velocity and temperature slip parameters. Likewise, a stability analysis has been performed to find the nature of the dual solutions. The velocity slip will delay the boundary layer separation whereas the temperature slip does not affect the boundary layer separation.

  7. Impurity-related nonlinear optical properties in delta-doped quantum rings: Electric field effects

    Energy Technology Data Exchange (ETDEWEB)

    Restrepo, R.L., E-mail: rrestre@gmail.com [Escuela de Ingeniería de Antioquia-EIA, Medellín (Colombia); Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Morales, A.L. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Martínez-Orozco, J.C. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, CP 98060, Zacatecas (Mexico); Baghramyan, H.M.; Barseghyan, M.G. [Department of Solid State Physics, Yerevan State University, Al. Manookian 1, 0025 Yerevan (Armenia); Mora-Ramos, M.E. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Duque, C.A. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)

    2014-11-15

    Using a variational procedure within the effective mass approximation, we have calculated the donor impurity binding energy for the ground (1s-like) and the excited (2p{sub z}-like) states as well as the impurity-related nonlinear optical absorption and relative changes in the refraction index in a GaAs single quantum ring with axial n-type delta-doping. The delta-like potential along the z-direction is an approximate model analytically described using a Lorentzian function with two parameters. Additionally we consider the application of an electric field along the z-direction. It is found that the changes in the geometry of the quantum ring, the change in the 2D impurity density of the delta-like doping, and different values of the electric field lead to a shifting of the resonant peaks of the optical responses spectrum.

  8. Non-linear sputtering effects induced by MeV energy gold clusters

    International Nuclear Information System (INIS)

    Boussofiane-Baudin, K.; Brunelle, A.; Chaurand, P.; Della-Negra, S.; Depauw, J.; Le Beyec, Y.; Hakansson, P.

    1993-09-01

    Gold clusters Au n + with 1 < n ≤ 4, accelerated to MeV energies at the Orsay tandem accelerator, have been used to induce secondary ion emission from the surface of thin organic and inorganic films. A non-linear enhancement of the secondary ion yields is observed when cluster impacts are compared to single atom impacts at the same velocity. It has been shown that the collective effects propagate in the solid over a depth larger than 2000 A. The equilibrium charge state of cluster constituents after their passage through a thin carbon foil (1000 A) has been measured. The mean value for the cluster constituents is the same as for single atoms at the same velocity. (authors). 41 refs., 8 figs., 1 tab

  9. Impurity-related nonlinear optical properties in delta-doped quantum rings: Electric field effects

    International Nuclear Information System (INIS)

    Restrepo, R.L.; Morales, A.L.; Martínez-Orozco, J.C.; Baghramyan, H.M.; Barseghyan, M.G.; Mora-Ramos, M.E.; Duque, C.A.

    2014-01-01

    Using a variational procedure within the effective mass approximation, we have calculated the donor impurity binding energy for the ground (1s-like) and the excited (2p z -like) states as well as the impurity-related nonlinear optical absorption and relative changes in the refraction index in a GaAs single quantum ring with axial n-type delta-doping. The delta-like potential along the z-direction is an approximate model analytically described using a Lorentzian function with two parameters. Additionally we consider the application of an electric field along the z-direction. It is found that the changes in the geometry of the quantum ring, the change in the 2D impurity density of the delta-like doping, and different values of the electric field lead to a shifting of the resonant peaks of the optical responses spectrum

  10. Finite-temperature Casimir effect in the presence of nonlinear dielectrics

    DEFF Research Database (Denmark)

    Kheirandish, Fardin; Amooghorban, Ehsan; Soltani, Morteza

    2011-01-01

    Starting from a Lagrangian, the electromagnetic field in the presence of a nonlinear dielectric medium is quantized using path-integral techniques, and correlation functions of different fields are calculated. The susceptibilities of the nonlinear medium are obtained, and their relations to coupl......Starting from a Lagrangian, the electromagnetic field in the presence of a nonlinear dielectric medium is quantized using path-integral techniques, and correlation functions of different fields are calculated. The susceptibilities of the nonlinear medium are obtained, and their relations...

  11. Nonlinear Poisson equation for heterogeneous media.

    Science.gov (United States)

    Hu, Langhua; Wei, Guo-Wei

    2012-08-22

    The Poisson equation is a widely accepted model for electrostatic analysis. However, the Poisson equation is derived based on electric polarizations in a linear, isotropic, and homogeneous dielectric medium. This article introduces a nonlinear Poisson equation to take into consideration of hyperpolarization effects due to intensive charges and possible nonlinear, anisotropic, and heterogeneous media. Variational principle is utilized to derive the nonlinear Poisson model from an electrostatic energy functional. To apply the proposed nonlinear Poisson equation for the solvation analysis, we also construct a nonpolar solvation energy functional based on the nonlinear Poisson equation by using the geometric measure theory. At a fixed temperature, the proposed nonlinear Poisson theory is extensively validated by the electrostatic analysis of the Kirkwood model and a set of 20 proteins, and the solvation analysis of a set of 17 small molecules whose experimental measurements are also available for a comparison. Moreover, the nonlinear Poisson equation is further applied to the solvation analysis of 21 compounds at different temperatures. Numerical results are compared to theoretical prediction, experimental measurements, and those obtained from other theoretical methods in the literature. A good agreement between our results and experimental data as well as theoretical results suggests that the proposed nonlinear Poisson model is a potentially useful model for electrostatic analysis involving hyperpolarization effects. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  12. The Effect of Surface Topography on the Nonlinear Dynamics of Rossby Waves

    Science.gov (United States)

    Abarzhi, S. I.; Desjardins, O.; Pitsch, H.

    2003-01-01

    Boussinesq convection in rotating systems attracts a sustained attention of the fluid dynamics community, because it has intricate non-linear dynamics (Cross & Hohenberg 1993) and plays an important role in geophysical and astrophysical applications, such as the motion of the liquid outer core of Earth, the Red Spot in Jupiter, the giant cells in the Sun etc. (Alridge et al. 1990). A fundamental distinction between the real geo- and astrophysical problems and the idealized laboratory studies is that natural systems are inhomogeneous (Alridge et al. 1990). Heterogeneities modulate the flow and influence significantly the dynamics of convective patterns (Alridge et al. 1990; Hide 1971). The effect of modulations on pattern formation and transition to turbulence in Boussinesq convection is far from being completely understood (Cross & Hohenberg 1993; Aranson & Kramer 2002). It is generally accepted that in the liquid outer core of the Earth the transport of the angular momentum and internal heat occurs via thermal Rossby waves (Zhang et al. 2001; Kuang & Bloxham 1999). These waves been visualized in laboratory experiments in rotating liquid-filled spheres and concentric spherical shells (Zhang et al. 2001; Kuang & Bloxham 1999). The basic dynamical features of Rossby waves have been reproduced in a cylindrical annulus, a system much simpler than the spherical ones (Busse & Or 1986; Or & Busse 1987). For convection in a cylindrical annulus, the fluid motion is two-dimensional, and gravity is replaced by a centrifugal force, (Busse & Or 1986; Or & Busse 1987). Hide (1971) has suggested that the momentum and heat transport in the core might be influenced significantly by so-called bumps, which are heterogeneities on the mantle-core boundary. To model the effect of surface topography on the transport of momentum and energy in the liquid outer core of the Earth, Bell & Soward (1996), Herrmann & Busse (1998) and Westerburg & Busse (2001) have studied the nonlinear dynamics

  13. A Nonlinear Dynamic Approach Reveals a Long-Term Stroke Effect on Cerebral Blood Flow Regulation at Multiple Time Scales

    Science.gov (United States)

    Hu, Kun; Lo, Men-Tzung; Peng, Chung-Kang; Liu, Yanhui; Novak, Vera

    2012-01-01

    Cerebral autoregulation (CA) is an important vascular control mechanism responsible for relatively stable cerebral blood flow despite changes of systemic blood pressure (BP). Impaired CA may leave brain tissue unprotected against potentially harmful effects of BP fluctuations. It is generally accepted that CA is less effective or even inactive at frequencies >∼0.1 Hz. Without any physiological foundation, this concept is based on studies that quantified the coupling between BP and cerebral blood flow velocity (BFV) using transfer function analysis. This traditional analysis assumes stationary oscillations with constant amplitude and period, and may be unreliable or even invalid for analysis of nonstationary BP and BFV signals. In this study we propose a novel computational tool for CA assessment that is based on nonlinear dynamic theory without the assumption of stationary signals. Using this method, we studied BP and BFV recordings collected from 39 patients with chronic ischemic infarctions and 40 age-matched non-stroke subjects during baseline resting conditions. The active CA function in non-stroke subjects was associated with an advanced phase in BFV oscillations compared to BP oscillations at frequencies from ∼0.02 to 0.38 Hz. The phase shift was reduced in stroke patients even at > = 6 months after stroke, and the reduction was consistent at all tested frequencies and in both stroke and non-stroke hemispheres. These results provide strong evidence that CA may be active in a much wider frequency region than previously believed and that the altered multiscale CA in different vascular territories following stroke may have important clinical implications for post-stroke recovery. Moreover, the stroke effects on multiscale cerebral blood flow regulation could not be detected by transfer function analysis, suggesting that nonlinear approaches without the assumption of stationarity are more sensitive for the assessment of the coupling of nonstationary

  14. Symmetries in Hall-like systems: microwave and nonlinear transport effects

    International Nuclear Information System (INIS)

    Torres, Manuel; Kunold, Alejandro

    2008-01-01

    In this work, we present a model to describe the nonlinear response to a dc electrical current of a two-dimensional electron system subjected to magnetic and microwave fields. Considering the separation of the electron coordinates into the non-commuting relative and guiding center coordinates, we obtain a unitary transformation that exactly solves the time-dependent Schroedinger equation in the presence of arbitrarily strong electric, magnetic and microwave fields. Based on this formalism, we provide a Kubo-like formula that takes into account the oscillatory Floquet structure of the problem. We discuss results related to the recently discovered zero-resistance states and to the microwave-induced resistivity oscillations and the Hall-induced resistivity oscillations

  15. Nonlinear effects during sound propagation in n-InSb at 4.20K

    International Nuclear Information System (INIS)

    Ilisavskij, Yu.V.; Chiplis, D.

    1975-01-01

    The absorption of transverse sound and the influence of longitudinal electric and magnetic fields thereon were studied in n-InSb at 4.2 0 K over a wide range of frequencies and intensities. The electron absorption of sound was found to depend strongly on input intensity due to the heating of electrons by the sound wave. It was discovered that the observed non-linearity was suppressed by the electric field. On the basis of comparison of the experimental results with the existing theories it is concluded that during the heating of electrons by sound, apart from changes in mobility, the carrier concentration in the conductivity band is also substantially changed. The measurements in the magnetic field agree qualitatively with the two-band conductivity model. (author)

  16. Effects of indirect lightning strokes on lossy power distribution lines in the presence of nonlinear loads

    International Nuclear Information System (INIS)

    Rahimian, M. S.; Sadeghi, S. H. H.; Moini, R.

    2003-01-01

    Cloud-to-ground lightning strokes can include dangerous overvoltage on power distribution overhead lines. In this paper, a new algorithm is propagated within a distribution network including nonlinear apparatus. The coupling between the lightning channel and the overhead line is based on an antenna theory model and employs the method of moment for solving the governing electric field integral equation. The computed induced overvoltage is then used in the electromagnetic transient program to analyze its propagation within the distribution network. In this regard, the accuracy of the new coupling method is demonstrated by comparing the calculated induced over voltages using the new method and those obtained using the conventional methods. Simulation results are presented to show how the induced overvoltage is penetrated in a typical distribution network, consisting of overhead lines and underground cables, a distribution transformer protected by surge arresters and a three-phase resistive load

  17. Nonlinear Dynamical Analysis of Hydraulic Turbine Governing Systems with Nonelastic Water Hammer Effect

    Directory of Open Access Journals (Sweden)

    Junyi Li

    2014-01-01

    Full Text Available A nonlinear mathematical model for hydroturbine governing system (HTGS has been proposed. All essential components of HTGS, that is, conduit system, turbine, generator, and hydraulic servo system, are considered in the model. Using the proposed model, the existence and stability of Hopf bifurcation of an example HTGS are investigated. In addition, chaotic characteristics of the system with different system parameters are studied extensively and presented in the form of bifurcation diagrams, time waveforms, phase space trajectories, Lyapunov exponent, chaotic attractors, and Poincare maps. Good correlation can be found between the model predictions and theoretical analysis. The simulation results provide a reasonable explanation for the sustained oscillation phenomenon commonly seen in operation of hydroelectric generating set.

  18. Effect of state-dependent delay on a weakly damped nonlinear oscillator.

    Science.gov (United States)

    Mitchell, Jonathan L; Carr, Thomas W

    2011-04-01

    We consider a weakly damped nonlinear oscillator with state-dependent delay, which has applications in models for lasers, epidemics, and microparasites. More generally, the delay-differential equations considered are a predator-prey system where the delayed term is linear and represents the proliferation of the predator. We determine the critical value of the delay that causes the steady state to become unstable to periodic oscillations via a Hopf bifurcation. Using asymptotic averaging, we determine how the system's behavior is influenced by the functional form of the state-dependent delay. Specifically, we determine whether the branch of periodic solutions will be either sub- or supercritical as well as an accurate estimation of the amplitude. Finally, we choose a few examples of state-dependent delay to test our analytical results by comparing them to numerical continuation.

  19. Effects of collisions on linear and non-linear spectroscopic line shapes

    International Nuclear Information System (INIS)

    Berman, P.R.

    1978-01-01

    A fundamental physical problem is the determination of atom-atom, atom-molecule and molecule-molecule differential and total scattering cross sections. In this work, a technique for studying atomic and molecular collisions using spectroscopic line shape analysis is discussed. Collisions occurring within an atomic or molecular sample influence the sample's absorptive or emissive properties. Consequently the line shapes associated with the linear or non-linear absorption of external fields by an atomic system reflect the collisional processes occurring in the gas. Explicit line shape expressions are derived characterizing linear or saturated absorption by two-or three-level 'active' atoms which are undergoing collisions with perturber atoms. The line shapes may be broadened, shifted, narrowed, or distorted as a result of collisions which may be 'phase-interrupting' or 'velocity-changing' in nature. Systematic line shape studies can be used to obtain information on both the differential and total active atom-perturber scattering cross sections. (Auth.)

  20. Quantum Effect in a Diode Included Nonlinear Inductance-Capacitance Mesoscopic Circuit

    International Nuclear Information System (INIS)

    Yan Zhanyuan; Zhang Xiaohong; Ma Jinying

    2009-01-01

    The mesoscopic nonlinear inductance-capacitance circuit is a typical anharmonic oscillator, due to diodes included in the circuit. In this paper, using the advanced quantum theory of mesoscopic circuits, which based on the fundamental fact that the electric charge takes discrete value, the diode included mesoscopic circuit is firstly studied. Schroedinger equation of the system is a four-order difference equation in p-circumflex representation. Using the extended perturbative method, the detail energy spectrum and wave functions are obtained and verified, as an application of the results, the current quantum fluctuation in the ground state is calculated. Diode is a basis component in a circuit, its quantization would popularize the quantum theory of mesoscopic circuits. The methods to solve the high order difference equation are helpful to the application of mesoscopic quantum theory.

  1. Nonlinear dynamics of human locomotion: effects of rhythmic auditory cueing on local dynamic stability

    Directory of Open Access Journals (Sweden)

    Philippe eTerrier

    2013-09-01

    Full Text Available It has been observed that times series of gait parameters (stride length (SL, stride time (ST and stride speed (SS, exhibit long-term persistence and fractal-like properties. Synchronizing steps with rhythmic auditory stimuli modifies the persistent fluctuation pattern to anti-persistence. Another nonlinear method estimates the degree of resilience of gait control to small perturbations, i.e. the local dynamic stability (LDS. The method makes use of the maximal Lyapunov exponent, which estimates how fast a nonlinear system embedded in a reconstructed state space (attractor diverges after an infinitesimal perturbation. We propose to use an instrumented treadmill to simultaneously measure basic gait parameters (time series of SL, ST and SS from which the statistical persistence among consecutive strides can be assessed, and the trajectory of the center of pressure (from which the LDS can be estimated. In 20 healthy participants, the response to rhythmic auditory cueing (RAC of LDS and of statistical persistence (assessed with detrended fluctuation analysis (DFA was compared. By analyzing the divergence curves, we observed that long-term LDS (computed as the reverse of the average logarithmic rate of divergence between the 4th and the 10th strides downstream from nearest neighbors in the reconstructed attractor was strongly enhanced (relative change +47%. That is likely the indication of a more dampened dynamics. The change in short-term LDS (divergence over one step was smaller (+3%. DFA results (scaling exponents confirmed an anti-persistent pattern in ST, SL and SS. Long-term LDS (but not short-term LDS and scaling exponents exhibited a significant correlation between them (r=0.7. Both phenomena probably result from the more conscious/voluntary gait control that is required by RAC. We suggest that LDS and statistical persistence should be used to evaluate the efficiency of cueing therapy in patients with neurological gait disorders.

  2. A kinetic formulation of piezoresistance in N-type silicon: Application to non-linear effects

    Science.gov (United States)

    Charbonnieras, A. R.; Tellier, C. R.

    1999-07-01

    This paper is devoted to the theoretical study of the influence of the temperature and of the doping on the piezoresistance of N-type silicon. In the first step the fractional change in the resistivity caused by stresses is calculated in the framework of a multivalley model using a kinetic transport formulation based on the Boltzmann transport equation. In the second step shifts in the minima of the conduction band and the resulting shift of the Fermi level are expressed in terms of deformation potentials and of stresses. General expressions for the fundamental linear, π_{11} and π_{12}, and non-linear, π_{111}, π_{112}, π_{122} and π_{123}, piezoresistance coefficients are then derived. Plots of the non-linear piezoresistance coefficients against the reduced shift of the Fermi level or against temperature allow us to characterize the influence of doping and temperature. Finally some attempts are made to estimate the non-linearity for heavily doped semiconductor gauges. Cette publication est consacrée à l'étude théorique de l'influence de la température et du dopage sur la piezorésistivité du silicium type N. Dans une première étape nous adoptons le modèle de vallées et nous utilisons une formulation cinétique du transport électronique faisant appel à l'équation de transport de Boltzmann pour calculer la variation de la résistivité du semiconducteur sous contrainte. Dans la deuxième étape nous exprimons les déplacements des minima de la bande de conduction et du niveau de Fermi en termes de potentiels de déformation et de contraintes. Nous proposons ensuite des expressions générales pour les coefficients piezorésistifs fondamentaux linéaires, π_{11} et π_{12}, et non-linéaires, π_{111}, π_{112}, π_{122} et π_{123}. Des représentations graphiques des variations des coefficients non-linéaires permettent de caractériser l'influence du dopage et de la température. Enfin nous fournissons une première pré-estimation des effets

  3. Beach steepness effects on nonlinear infragravity-wave interactions : A numerical study

    NARCIS (Netherlands)

    De Bakker, A. T M; Tissier, M.F.S.; Ruessink, B. G.

    2016-01-01

    The numerical model SWASH is used to investigate nonlinear energy transfers between waves for a diverse set of beach profiles and wave conditions, with a specific focus on infragravity waves. We use bispectral analysis to study the nonlinear triad interactions, and estimate energy transfers to

  4. Beach steepness effects on nonlinear infragravity-wave interactions : A numerical study

    NARCIS (Netherlands)

    de Bakker, A. T M; Tissier, M. F S; Ruessink, B. G.

    2016-01-01

    The numerical model SWASH is used to investigate nonlinear energy transfers between waves for a diverse set of beach profiles and wave conditions, with a specific focus on infragravity waves. We use bispectral analysis to study the nonlinear triad interactions, and estimate energy transfers to

  5. Finite Element Modeling and Analysis of Nonlinear Impact and Frictional Motion Responses Including Fluid—Structure Coupling Effects

    Directory of Open Access Journals (Sweden)

    Yong Zhao

    1997-01-01

    Full Text Available A nonlinear three dimensional (3D single rack model and a nonlinear 3D whole pool multi-rack model are developed for the spent fuel storage racks of a nuclear power plant (NPP to determine impacts and frictional motion responses when subjected to 3D excitations from the supporting building floor. The submerged free standing rack system and surrounding water are coupled due to hydrodynamic fluid-structure interaction (FSI using potential theory. The models developed have features that allow consideration of geometric and material nonlinearities including (1 the impacts of fuel assemblies to rack cells, a rack to adjacent racks or pool walls, and rack support legs to the pool floor; (2 the hydrodynamic coupling of fuel assemblies with their storing racks, and of a rack with adjacent racks, pool walls, and the pool floor; and (3 the dynamic motion behavior of rocking, twisting, and frictional sliding of rack modules. Using these models 3D nonlinear time history dynamic analyses are performed per the U.S. Nuclear Regulatory Commission (USNRC criteria. Since few such modeling, analyses, and results using both the 3D single and whole pool multiple rack models are available in the literature, this paper emphasizes description of modeling and analysis techniques using the SOLVIA general purpose nonlinear finite element code. Typical response results with different Coulomb friction coefficients are presented and discussed.

  6. Is more always better? An examination of the nonlinear effects of perceived organizational support on individual outcomes.

    Science.gov (United States)

    Harris, Kenneth J; Kacmar, K Michele

    2018-01-01

    A wide range of research has accumulated detailing the positive associations of perceived organizational support (POS) with desirable workplace outcomes (e.g., high performance, high commitment, low deviance). In the process, there has been an implicit assumption that these relationships are linear, with ever-increasing POS resulting in ever-increasing positive outcomes. However, there are theoretical and practical reasons to question whether these relationships may be nonlinear rather than linear. Our results offer support for the notion that the relationships between POS and key individual outcomes rated by the supervisor may best be represented as nonlinear. We conclude by highlighting the implications for both theory and practice.

  7. Effect of Magnetic Twist on Nonlinear Transverse Kink Oscillations of Line-tied Magnetic Flux Tubes

    Science.gov (United States)

    Terradas, J.; Magyar, N.; Van Doorsselaere, T.

    2018-01-01

    Magnetic twist is thought to play an important role in many structures of the solar atmosphere. One of the effects of twist is to modify the properties of the eigenmodes of magnetic tubes. In the linear regime standing kink solutions are characterized by a change in polarization of the transverse displacement along the twisted tube. In the nonlinear regime, magnetic twist affects the development of shear instabilities that appear at the tube boundary when it is oscillating laterally. These Kelvin–Helmholtz instabilities (KHI) are produced either by the jump in the azimuthal component of the velocity at the edge of the sharp boundary between the internal and external part of the tube or by the continuous small length scales produced by phase mixing when there is a smooth inhomogeneous layer. In this work the effect of twist is consistently investigated by solving the time-dependent problem including the process of energy transfer to the inhomogeneous layer. It is found that twist always delays the appearance of the shear instability, but for tubes with thin inhomogeneous layers the effect is relatively small for moderate values of twist. On the contrary, for tubes with thick layers, the effect of twist is much stronger. This can have some important implications regarding observations of transverse kink modes and the KHI itself.

  8. Effect of nonlinearity of connecting dampers on vibration control of connected building structures

    Directory of Open Access Journals (Sweden)

    Masatoshi eKasagi

    2016-01-01

    Full Text Available The connection of two building structures with dampers is one of effective vibration control systems. In this vibration control system, both buildings have to possess different vibration properties in order to provide a higher vibration reduction performance. In addition to such condition of different vibration properties of both buildings, the connecting dampers also play an important role in the vibration control mechanism. In this paper, the effect of nonlinearity of connecting dampers on the vibration control of connected building structures is investigated in detail. A high-damping rubber damper and an oil damper with and without relief mechanism are treated. It is shown that, while the high-damping rubber damper is effective in a rather small deformation level, the linear oil damper is effective in a relatively large deformation level. It is further shown that, while the oil dampers reduce the response in the same phase as the case without dampers, the high-damping rubber dampers change the phase. The merit is that the high-damping rubber can reduce the damper deformation and keep the sufficient space between both buildings. This can mitigate the risk of building pounding.

  9. Photoinduced nonlinear optical effects in Nd-doped δ-BiB3O6 crystals

    International Nuclear Information System (INIS)

    Majchrowski, A.; Wojciechowski, A.; Kityk, I.V.; Chrunik, M.; Jaroszewicz, L.R.; Michalski, E.

    2014-01-01

    Highlights: • New type of optically operated rare earth doped borates is proposed. • Principal role of the phonon subsystem in photoinduced electrooptics, SHG and piezooptics is shown. • The possibility to create the laser operated materials is shown for the such kind of sold state alloys. - Abstract: The studies of the second harmonic generation, Pockels effect and piezoelectricity were performed for the new synthesized δ-BiB 3 O 6 single crystals. The incorporation of Nd 3+ ions into these crystals plays an important role for the increasing of the photoinduced nonlinear optical properties. Temperature dependences of the optical and piezoelectric features showed existence of some anomalies in the vicinity of 160 K and 220 K. This may confirm a principal role of the photopolarization and of the localized impurity states which give additional contribution into the observed effect. It is crucial that the effect is dependent on the number of the photoinducing pulses. The effect is completely reversible after switching off of the photoinducing laser beam

  10. Self-Focusing of Quadruple Gaussian Laser Beam in an Inhomogenous Magnetized Plasma with Ponderomotive Non-Linearity: Effect of Linear Absorption

    International Nuclear Information System (INIS)

    Aggarwal, Munish; Vij, Shivani; Kant, Niti

    2015-01-01

    The propagation of quadruple Gaussian laser beam in a plasma characterized by axial inhomogeneity and nonlinearity due to ponderomotive force in the paraxial ray approximation is investigated. An appropriate expression for the nonlinear dielectric constant has been developed in the presence of external magnetic field, with linear absorption and due to saturation effects for arbitrary large intensity. The effects of different types of plasma axial inhomogeneities on self-focusing of laser beam have been studied with the typical laser and plasma parameters. Self-focusing of quadruple Gaussian laser beam in the presence of externally applied magnetic field and saturating parameter is found significantly improved in the case of extraordinary mode. Our results reveal that initially converging beam shows oscillatory convergence whereas initially diverging beam shows oscillatory divergence. The beam is more focussed at lower intensity in both cases viz. extraordinary and ordinary mode. (paper)

  11. Influence of heart rate in nonlinear HRV indices as a sampling rate effect evaluated on supine and standing

    Directory of Open Access Journals (Sweden)

    Juan Bolea

    2016-11-01

    Full Text Available The purpose of this study is to characterize and attenuate the influence of mean heart rate (HR on nonlinear heart rate variability (HRV indices (correlation dimension, sample and approximate entropy as a consequence of being the HR the intrinsic sampling rate of HRV signal. This influence can notably alter nonlinear HRV indices and lead to biased information regarding autonomic nervous system (ANS modulation.First, a simulation study was carried out to characterize the dependence of nonlinear HRV indices on HR assuming similar ANS modulation. Second, two HR-correction approaches were proposed: one based on regression formulas and another one based on interpolating RR time series. Finally, standard and HR-corrected HRV indices were studied in a body position change database.The simulation study showed the HR-dependence of non-linear indices as a sampling rate effect, as well as the ability of the proposed HR-corrections to attenuate mean HR influence. Analysis in a body position changes database shows that correlation dimension was reduced around 21% in median values in standing with respect to supine position (p < 0.05, concomitant with a 28% increase in mean HR (p < 0.05. After HR-correction, correlation dimension decreased around 18% in standing with respect to supine position, being the decrease still significant. Sample and approximate entropy showed similar trends.HR-corrected nonlinear HRV indices could represent an improvement in their applicability as markers of ANS modulation when mean HR changes.

  12. Simulation of High-current Pulse Effect on the Electrode with Nonlinear Material Characteristics and Phase Transitions Taken into Account

    Directory of Open Access Journals (Sweden)

    R. V. Arutjunjan

    2016-01-01

    Full Text Available The article investigates the thermal and electrical processes when heating the metal electrode by a high current pulse. The aim is to understand an impact nature of the nonlinearities of thermal parameters, the phase transitions of melting and evaporation, and the type of boundary conditions in the current spot. To solve the problem was formulated a mathematical model, and were also developed a finite-difference method and computer programmes which allow an effective computer simulations of thermal and electrical processes under the high current pulse impact on the metal electrodes. The Stefan problem is solved by the through "enthalpy" method. Calculation of the electric field is performed by Seidel iteration. Thermal and current balance and comparison with solution results of model problems allow computer error monitoring.The work involved a series of calculations for an informative case of iron. It enabled to find a significant influence of the nonlinearities of thermal parameters, the phase transitions of melting and evaporation, the type of boundary conditions on the values of the temperature and electric fields, especially in the vicinity of the current spot. The presence of high current density and temperature, respectively, in the vicinity of the current spot edge confirms the well-known hypothesis about the causes of contact welding on the edges of the contact area. It has been found that the impact of losses on radiation and convection cooling is negligible. The article continues and complements the well-known research in the theory of electrical contacts and welding processes based on detailed consideration of the electrode material properties, the nonlinearities, and a type of boundary conditions for temperature and electric fields.The results can be used in the practice in research and design of electrical machines and other electrical devices.The study has revealed the need to improve the enthalpy finite- difference method for

  13. The effective reflection of a pulse sequence from a four-wave mirror with thermal nonlinearity under parametric feedback

    Science.gov (United States)

    Barashkov, M. S.; Bel'Diugin, I. M.; Zolotarev, M. V.; Kruzhilin, Iu. I.; Krymskii, M. I.

    1989-04-01

    A four-wave mirror with thermal nonlinearity has been experimentally realized with the interaction of corunning waves under parametric feedback with a nonreciprocal element. The effective reflection of a sequence of pulses with duration of about 300 ns from a neodymium-glass laser with maximal reflection coefficients greater than 30 has been demonstrated. The quality of the radiation reflected from the mirror is studied. A significant reduction in the steady-state lasing threshold has been shown with thermal nonlinearity at small angles of the interacting beam convergence, compared to the case of counterrunning convergence.

  14. Effects from fully nonlinear irregular wave forcing on the fatigue life of an offshore wind turbine and its monopile foundation

    DEFF Research Database (Denmark)

    Schløer, Signe; Bredmose, Henrik; Bingham, Harry B.

    2013-01-01

    The effect from fully nonlinear irregular wave forcing on the fatigue life of the foundation and tower of an offshore wind turbine is investigated through aeroelastic calculations. Five representative sea states with increasing significant wave height are considered in a water depth of 40 m....... The waves are both linear and fully nonlinear irregular 2D waves. The wind turbine is the NREL 5-MW reference wind turbine. Fatigue analysis is performed in relation to analysis of the sectional forces in the tower and monopile. Impulsive excitation of the sectional force at the bottom of the tower is seen...

  15. The Effect of Creative Tasks on Electrocardiogram: Using Linear and Nonlinear Features in Combination with Classification Approaches

    Directory of Open Access Journals (Sweden)

    Sahar Zakeri

    2017-02-01

    Full Text Available Objective: Interest in the subject of creativity and its impacts on human life is growing extensively. However, only a few surveys pay attention to the relation between creativity and physiological changes. This paper presents a novel approach to distinguish between creativity states from electrocardiogram signals. Nineteen linear and nonlinear features of the cardiac signal were extracted to detect creativity states. Method: ECG signals of 52 participants were recorded while doing three tasks of Torrance Tests of Creative Thinking (TTCT/ figural B. To remove artifacts, notch filter 50 Hz and Chebyshev II were applied. According to TTCT scores, participants were categorized into the high and low creativity groups: Participants with scores higher than 70 were assigned into the high creativity group and those with scores less than 30 were considered as low creativity group. Some linear and nonlinear features were extracted from the ECGs. Then, Support Vector Machine (SVM and Adaptive Neuro-Fuzzy Inference System (ANFIS were used to classify the groups.Results: Applying the Wilcoxon test, significant differences were observed between rest and each three tasks of creativity. However, better discrimination was performed between rest and the first task. In addition, there were no statistical differences between the second and third task of the test. The results indicated that the SVM effectively detects all the three tasks from the rest, particularly the task 1 and reached the maximum accuracy of 99.63% in the linear analysis. In addition, the high creative group was separated from the low creative group with the accuracy of 98.41%.Conclusion: the combination of SVM classifier with linear features can be useful to show the relation between creativity and physiological changes.

  16. Analysis and compensation for the joint effects of HPA nonlinearity, I/Q imbalance and crosstalk in MIMO beamforming systems

    KAUST Repository

    Qi, Jian; Aissa, Sonia

    2011-01-01

    In this paper, we investigate the joint effects of high-power amplifier (HPA) nonlinearity, in-phase/quadrature-phase (I/Q) imbalance and crosstalk, on the performance of multiple-input multiple-output (MIMO) transmit beamforming (TB) systems

  17. Non-linear effects in electron cyclotron current drive applied for the stabilization of neoclassical tearing modes

    NARCIS (Netherlands)

    Ayten, B.; Westerhof, E.; ASDEX Upgrade team,

    2014-01-01

    Due to the smallness of the volumes associated with the flux surfaces around the O-point of a magnetic island, the electron cyclotron power density applied inside the island for the stabilization of neoclassical tearing modes (NTMs) can exceed the threshold for non-linear effects as derived

  18. Linear Text vs. Non-Linear Hypertext in Handheld Computers: Effects on Declarative and Structural Knowledge, and Learner Motivation

    Science.gov (United States)

    Son, Chanhee; Park, Sanghoon; Kim, Minjeong

    2011-01-01

    This study compared linear text-based and non-linear hypertext-based instruction in a handheld computer regarding effects on two different levels of knowledge (declarative and structural knowledge) and learner motivation. Forty four participants were randomly assigned to one of three experimental conditions: linear text, hierarchical hypertext,…

  19. Suppression of period-doubling and nonlinear parametric effects in periodically perturbed systems

    International Nuclear Information System (INIS)

    Bryant, P.; Wiesenfeld, K.

    1986-01-01

    We consider the effect on a generic period-doubling bifurcation of a periodic perturbation, whose frequency ω 1 is near the period-doubled frequency ω 0 /2. The perturbation is shown to always suppress the bifurcation, shifting the bifurcation point and stabilizing the behavior at the original bifurcation point. We derive an equation characterizing the response of the system to the perturbation, analysis of which reveals many interesting features of the perturbed bifurcation, including (1) the scaling law relating the shift of the bifurcation point and the amplitude of the perturbation, (2) the characteristics of the system's response as a function of bifurcation parameter, (3) parametric amplification of the perturbation signal including nonlinear effects such as gain saturation and a discontinuity in the response at a critical perturbation amplitude, (4) the effect of the detuning (ω 1 -ω 0 /2) on the bifurcation, and (5) the emergence of a closely spaced set of peaks in the response spectrum. An important application is the use of period-doubling systems as small-signal amplifiers, e.g., the superconducting Josephson parametric amplifier

  20. Field-effect transistors as electrically controllable nonlinear rectifiers for the characterization of terahertz pulses

    Science.gov (United States)

    Lisauskas, Alvydas; Ikamas, Kestutis; Massabeau, Sylvain; Bauer, Maris; ČibiraitÄ--, DovilÄ--; Matukas, Jonas; Mangeney, Juliette; Mittendorff, Martin; Winnerl, Stephan; Krozer, Viktor; Roskos, Hartmut G.

    2018-05-01

    We propose to exploit rectification in field-effect transistors as an electrically controllable higher-order nonlinear phenomenon for the convenient monitoring of the temporal characteristics of THz pulses, for example, by autocorrelation measurements. This option arises because of the existence of a gate-bias-controlled super-linear response at sub-threshold operation conditions when the devices are subjected to THz radiation. We present measurements for different antenna-coupled transistor-based THz detectors (TeraFETs) employing (i) AlGaN/GaN high-electron-mobility and (ii) silicon CMOS field-effect transistors and show that the super-linear behavior in the sub-threshold bias regime is a universal phenomenon to be expected if the amplitude of the high-frequency voltage oscillations exceeds the thermal voltage. The effect is also employed as a tool for the direct determination of the speed of the intrinsic TeraFET response which allows us to avoid limitations set by the read-out circuitry. In particular, we show that the build-up time of the intrinsic rectification signal of a patch-antenna-coupled CMOS detector changes from 20 ps in the deep sub-threshold voltage regime to below 12 ps in the vicinity of the threshold voltage.

  1. Nonlinear dynamics of shells conveying pulsatile flow with pulse-wave propagation. Theory and numerical results for a single harmonic pulsation

    Science.gov (United States)

    Tubaldi, Eleonora; Amabili, Marco; Païdoussis, Michael P.

    2017-05-01

    In deformable shells conveying pulsatile flow, oscillatory pressure changes cause local movements of the fluid and deformation of the shell wall, which propagate downstream in the form of a wave. In biomechanics, it is the propagation of the pulse that determines the pressure gradient during the flow at every location of the arterial tree. In this study, a woven Dacron aortic prosthesis is modelled as an orthotropic circular cylindrical shell described by means of the Novozhilov nonlinear shell theory. Flexible boundary conditions are considered to simulate connection with the remaining tissue. Nonlinear vibrations of the shell conveying pulsatile flow and subjected to pulsatile pressure are investigated taking into account the effects of the pulse-wave propagation. For the first time in literature, coupled fluid-structure Lagrange equations of motion for a non-material volume with wave propagation in case of pulsatile flow are developed. The fluid is modeled as a Newtonian inviscid pulsatile flow and it is formulated using a hybrid model based on the linear potential flow theory and considering the unsteady viscous effects obtained from the unsteady time-averaged Navier-Stokes equations. Contributions of pressure and velocity propagation are also considered in the pressure drop along the shell and in the pulsatile frictional traction on the internal wall in the axial direction. A numerical bifurcation analysis employs a refined reduced order model to investigate the dynamic behavior of a pressurized Dacron aortic graft conveying blood flow. A pulsatile time-dependent blood flow model is considered by applying the first harmonic of the physiological waveforms of velocity and pressure during the heart beating period. Geometrically nonlinear vibration response to pulsatile flow and transmural pulsatile pressure, considering the propagation of pressure and velocity changes inside the shell, is here presented via frequency-response curves, time histories, bifurcation

  2. Nonlinear optics

    International Nuclear Information System (INIS)

    Boyd, R.W.

    1992-01-01

    Nonlinear optics is the study of the interaction of intense laser light with matter. This book is a textbook on nonlinear optics at the level of a beginning graduate student. The intent of the book is to provide an introduction to the field of nonlinear optics that stresses fundamental concepts and that enables the student to go on to perform independent research in this field. This book covers the areas of nonlinear optics, quantum optics, quantum electronics, laser physics, electrooptics, and modern optics

  3. Assessment of Effects of a Delay Block and a Nonlinear Block in Systems with Chaotic Behavior Using Lyapunov Exponents

    Directory of Open Access Journals (Sweden)

    Pablo César Rodríguez Gómez

    2017-05-01

    Full Text Available Context: Because feedback systems are very common and widely used, studies of the structural characteristics under which chaotic behavior is generated have been developed. These can be separated into a nonlinear system and a linear system at least of the third order. Methods such as the descriptive function have been used for analysis. Method: A feedback system is proposed comprising a linear system, a nonlinear system and a delay block, in order to assess his behavior using Lyapunov exponents. It is evaluated with three different linear systems, different delay values and different values for parameters of nonlinear characteristic, aiming to reach chaotic behavior. Results: One hundred experiments were carried out for each of the three linear systems, by changing the value of some parameters, assessing their influence on the dynamics of the system. Contour plots that relate these parameters to the Largest Lyapunov exponent were obtained and analyzed. Conclusions: In spite non-linearity is a condition for the existence of chaos, this does not imply that any nonlinear characteristic generates a chaotic system, it is reflected by the contour plots showing the transitions between chaotic and no chaotic behavior of the feedback system. Language: English

  4. Non-linear Simulations of MHD Instabilities in Tokamaks Including Eddy Current Effects and Perspectives for the Extension to Halo Currents

    International Nuclear Information System (INIS)

    Hoelzl, M; Merkel, P; Lackner, K; Strumberger, E; Huijsmans, G T A; Aleynikova, K; Liu, F; Atanasiu, C; Nardon, E; Fil, A; McAdams, R; Chapman, I

    2014-01-01

    The dynamics of large scale plasma instabilities can be strongly influenced by the mutual interaction with currents flowing in conducting vessel structures. Especially eddy currents caused by time-varying magnetic perturbations and halo currents flowing directly from the plasma into the walls are important. The relevance of a resistive wall model is directly evident for Resistive Wall Modes (RWMs) or Vertical Displacement Events (VDEs). However, also the linear and non-linear properties of most other large-scale instabilities may be influenced significantly by the interaction with currents in conducting structures near the plasma. The understanding of halo currents arising during disruptions and VDEs, which are a serious concern for ITER as they may lead to strong asymmetric forces on vessel structures, could also benefit strongly from these non-linear modeling capabilities. Modeling the plasma dynamics and its interaction with wall currents requires solving the magneto-hydrodynamic (MHD) equations in realistic toroidal X-point geometry consistently coupled with a model for the vacuum region and the resistive conducting structures. With this in mind, the non-linear finite element MHD code JOREK [1, 2] has been coupled [3] with the resistive wall code STARWALL [4], which allows us to include the effects of eddy currents in 3D conducting structures in non-linear MHD simulations. This article summarizes the capabilities of the coupled JOREK-STARWALL system and presents benchmark results as well as first applications to non-linear simulations of RWMs, VDEs, disruptions triggered by massive gas injection, and Quiescent H-Mode. As an outlook, the perspectives for extending the model to halo currents are described

  5. Stationary nonlinear Airy beams

    International Nuclear Information System (INIS)

    Lotti, A.; Faccio, D.; Couairon, A.; Papazoglou, D. G.; Panagiotopoulos, P.; Tzortzakis, S.; Abdollahpour, D.

    2011-01-01

    We demonstrate the existence of an additional class of stationary accelerating Airy wave forms that exist in the presence of third-order (Kerr) nonlinearity and nonlinear losses. Numerical simulations and experiments, in agreement with the analytical model, highlight how these stationary solutions sustain the nonlinear evolution of Airy beams. The generic nature of the Airy solution allows extension of these results to other settings, and a variety of applications are suggested.

  6. Modulated Langmuir waves and nonlinear Landau damping

    International Nuclear Information System (INIS)

    Yajima, Nobuo; Oikawa, Masayuki; Satsuma, Junkichi; Namba, Chusei.

    1975-01-01

    The nonlinear Schroedinger euqation with an integral term, iusub(t)+P/2.usub(xx)+Q/u/ 2 u+RP∫sub(-infinity)sup(infinity)[/u(x',t)/ 2 /(x-x')]dx'u=0, which describes modulated Langmuir waves with the nonlinear Landau damping effect, is solved by numerical calculations. Especially, the effects of nonlinear Landau damping on solitary wave solutions are studied. For both cases, PQ>0 and PQ<0, the results show that the solitary waves deform in an asymmetric way changing its velocity. (auth.)

  7. Linear stability analysis and nonlinear simulation of the channeling effect on viscous fingering instability in miscible displacement

    Science.gov (United States)

    Shahnazari, M. R.; Maleka Ashtiani, I.; Saberi, A.

    2018-03-01

    In this paper, the effect of channeling on viscous fingering instability of miscible displacement in porous media is studied. In fact, channeling is introduced as a solution to stabilize the viscous fingering instability. In this solution, narrow channels were placed next to the walls, and by considering an exponential function to model the channeling effect, a heterogeneous media is assumed. In linear stability analysis, the governing equations are transferred to Fourier space, and by introducing a novel numerical method, the transferred equations are analyzed. The growth rate based on the wave number diagram has been drawn up in three sections of the medium. It is found that the flow becomes more stable at the center and unstable along the walls when the permeability ratio is increased. Also when the permeability ratio is approximately equal to one, the channeling has no significant effect. In nonlinear simulations, by using stream function and vortices, new equations have been rewritten and it is shown that channeling has a profound effect on the growth of the fingers and mechanisms. In addition to the superposition of velocity vectors and concentration contours, the development of instability is investigated using the mixing length and sweep efficiency diagram. The results show that although channeling reduces instability, it increases the displacement process time.

  8. The effect of quintic nonlinearity on the propagation characteristics of dispersion managed optical solitons

    International Nuclear Information System (INIS)

    Konar, S.; Mishra, Manoj; Jana, S.

    2006-01-01

    The role of quintic nonlinearity on the propagation characteristics of optical solitons in dispersion managed optical communication systems has been presented in this paper. It has been shown that quintic nonlinearity has only marginal influence on single pulse propagation. However, numerical simulation has been undertaken to reveal that quintic nonlinearity reduces collision distance between neighbouring pulses of the same channel. It is found that for lower map strength the collapse distance between intra channel pulses is very much sensitive to the dispersion map strength

  9. An effective method for finding special solutions of nonlinear differential equations with variable coefficients

    International Nuclear Information System (INIS)

    Qin Maochang; Fan Guihong

    2008-01-01

    There are many interesting methods can be utilized to construct special solutions of nonlinear differential equations with constant coefficients. However, most of these methods are not applicable to nonlinear differential equations with variable coefficients. A new method is presented in this Letter, which can be used to find special solutions of nonlinear differential equations with variable coefficients. This method is based on seeking appropriate Bernoulli equation corresponding to the equation studied. Many well-known equations are chosen to illustrate the application of this method

  10. Unusual motions due to nonlinear effects in a driven vibrating string

    Science.gov (United States)

    Hanson, Roger J.

    2005-09-01

    Usual nonlinear effects observed in a sinusoidally driven vibrating string include generation of motion perpendicular to the driving plane, sudden jumps of amplitude and associated hysteresis, and generation of higher harmonics. In addition, under some conditions, there can be a rich variety of unusual, very complex motions of a point on the string, the pattern of which, together with associated harmonic (and sometimes subharmonic) content, can change dramatically with a slight change in driving frequency or sometimes with constant driving frequency and force. Intrinsic string asymmetries can also have a profound effect on the behavior. In a brass harpsichord string (wire) such asymmetries can cause a small splitting of each natural frequency of free vibration into two closely spaced frequencies (relative separation ~0.2% to 2%, strongly dependent on tension.) The two frequency components are associated, respectively, with the transverse motion along two orthogonal characteristic wire axes. Emphasis will be on display of optically detected unusual motion patterns of a point on the string, including an example of a pattern period of 10 s when driving at 50 Hz. See R. J. Hanson et al., J. Acoust. Soc. Am. 117, 400-412 (2005) for a more complete treatment.

  11. Nonlinear Parametric Excitation Effect Induces Stability Transitions in Swimming Direction of Flexible Superparamagnetic Microswimmers.

    Science.gov (United States)

    Harduf, Yuval; Jin, Dongdong; Or, Yizhar; Zhang, Li

    2018-04-05

    Microscopic artificial swimmers have recently become highly attractive due to their promising potential for biomedical microrobotic applications. Previous pioneering work has demonstrated the motion of a robotic microswimmer with a flexible chain of superparamagnetic beads, which is actuated by applying an oscillating external magnetic field. Interestingly, they have shown that the microswimmer's orientation undergoes a 90°-transition when the magnetic field's oscillation amplitude is increased above a critical value. This unexpected transition can cause severe problems in steering and manipulation of flexible magnetic microrobotic swimmers. Thus, theoretical understanding and analysis of the physical origins of this effect are of crucial importance. In this work, we investigate this transition both theoretically and experimentally by using numerical simulations and presenting a novel flexible microswimmer with an anisotropic superparamagnetic head. We prove that this effect depends on both frequency and amplitude of the oscillating magnetic field, and demonstrate existence of an optimal amplitude achieving maximal swimming speed. Asymptotic analysis of a minimal two-link model reveals that the changes in the swimmer's direction represent stability transitions, which are induced by a nonlinear parametric excitation.

  12. Effects of initial radius of the interface and Atwood number on nonlinear saturation amplitudes in cylindrical Rayleigh-Taylor instability

    International Nuclear Information System (INIS)

    Liu, Wanhai; Yu, Changping; Li, Xinliang

    2014-01-01

    Nonlinear saturation amplitudes (NSAs) of the first two harmonics in classical Rayleigh-Taylor instability (RTI) in cylindrical geometry for arbitrary Atwood numbers have been analytically investigated considering nonlinear corrections up to the fourth-order. The NSA of the fundamental mode is defined as the linear (purely exponential) growth amplitude of the fundamental mode at the saturation time when the growth of the fundamental mode (first harmonic) is reduced by 10% in comparison to its corresponding linear growth, and the NSA of the second harmonic can be obtained in the same way. The analytic results indicate that the effects of the initial radius of the interface (r 0 ) and the Atwood number (A) play an important role in the NSAs of the first two harmonics in cylindrical RTI. On the one hand, the NSA of the fundamental mode first increases slightly and then decreases quickly with increasing A. For given A, the smaller the r 0 /λ (with λ perturbation wavelength) is, the larger the NSA of the fundamental mode is. When r 0 /λ is large enough (r 0 ≫λ), the NSA of the fundamental mode is reduced to the prediction of previous literatures within the framework of third-order perturbation theory [J. W. Jacobs and I. Catton, J. Fluid Mech. 187, 329 (1988); S. W. Haan, Phys. Fluids B 3, 2349 (1991)]. On the other hand, the NSA of the second harmonic first decreases quickly with increasing A, reaching a minimum, and then increases slowly. Furthermore, the r 0 can reduce the NSA of the second harmonic for arbitrary A at r 0 ≲2λ while increase it for A ≲ 0.6 at r 0 ≳2λ. Thus, it should be included in applications where the NSA has a role, such as inertial confinement fusion ignition target design

  13. Predicting the effect of ionising radiation on biological populations: testing of a non-linear Leslie model applied to a small mammal population

    International Nuclear Information System (INIS)

    Monte, Luigi

    2013-01-01

    The present work describes the application of a non-linear Leslie model for predicting the effects of ionising radiation on wild populations. The model assumes that, for protracted chronic irradiation, the effect-dose relationship is linear. In particular, the effects of radiation are modelled by relating the increase in the mortality rates of the individuals to the dose rates through a proportionality factor C. The model was tested using independent data and information from a series of experiments that were aimed at assessing the response to radiation of wild populations of meadow voles and whose results were described in the international literature. The comparison of the model results with the data selected from the above mentioned experiments showed that the model overestimated the detrimental effects of radiation on the size of irradiated populations when the values of C were within the range derived from the median lethal dose (L 50 ) for small mammals. The described non-linear model suggests that the non-expressed biotic potential of the species whose growth is limited by processes of environmental resistance, such as the competition among the individuals of the same or of different species for the exploitation of the available resources, can be a factor that determines a more effective response of population to the radiation effects. -- Highlights: • A model to assess the radiation effects on wild population is described. • The model is based on non-linear Leslie matrix. • The model is applied to small mammals living in an irradiated meadow. • Model output is conservative if effect-dose factor estimated from L 50 is used. • Systemic response to stress of populations in competitive conditions may be more effective

  14. Nonlinear optics

    CERN Document Server

    Bloembergen, Nicolaas

    1996-01-01

    Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe

  15. Nonlinear Dirac Equations

    Directory of Open Access Journals (Sweden)

    Wei Khim Ng

    2009-02-01

    Full Text Available We construct nonlinear extensions of Dirac's relativistic electron equation that preserve its other desirable properties such as locality, separability, conservation of probability and Poincaré invariance. We determine the constraints that the nonlinear term must obey and classify the resultant non-polynomial nonlinearities in a double expansion in the degree of nonlinearity and number of derivatives. We give explicit examples of such nonlinear equations, studying their discrete symmetries and other properties. Motivated by some previously suggested applications we then consider nonlinear terms that simultaneously violate Lorentz covariance and again study various explicit examples. We contrast our equations and construction procedure with others in the literature and also show that our equations are not gauge equivalent to the linear Dirac equation. Finally we outline various physical applications for these equations.

  16. Nonlinear screening effect in an ultrarelativistic degenerate electron-positron gas

    International Nuclear Information System (INIS)

    Tsintsadze, N. L.; Rasheed, A.; Shah, H. A.; Murtaza, G.

    2009-01-01

    Nonlinear screening process in an ultrarelativistic degenerate electron-positron gas has been investigated by deriving a generalized nonlinear Poisson equation for the electrostatic potential. In the simple one-dimensional case, the nonlinear Poisson equation leads to Debye-like (Coulomb-like) solutions at distances larger (less) than the characteristic length. When the electrostatic energy is larger than the thermal energy, this nonlinear Poisson equation converts into the relativistic Thomas-Fermi equation whose asymptotic solution in three dimensions shows that the potential field goes to zero at infinity much more slowly than the Debye potential. The possibility of the formation of a bound state in electron-positron plasma is also indicated. Further, it is investigated that the strong spatial fluctuations of the potential field may reduce the screening length and that the root mean square of this spatial fluctuating potential goes to zero for large r rather slowly as compared to the case of the Debye potential.

  17. Nonlinear optics at interfaces

    International Nuclear Information System (INIS)

    Chen, C.K.

    1980-12-01

    Two aspects of surface nonlinear optics are explored in this thesis. The first part is a theoretical and experimental study of nonlinear intraction of surface plasmons and bulk photons at metal-dielectric interfaces. The second part is a demonstration and study of surface enhanced second harmonic generation at rough metal surfaces. A general formulation for nonlinear interaction of surface plasmons at metal-dielectric interfaces is presented and applied to both second and third order nonlinear processes. Experimental results for coherent second and third harmonic generation by surface plasmons and surface coherent antiStokes Raman spectroscopy (CARS) are shown to be in good agreement with the theory

  18. Nonlinear dynamics in Nuclotron

    International Nuclear Information System (INIS)

    Dinev, D.

    1997-01-01

    The paper represents an extensive study of the nonlinear beam dynamics in the Nuclotron. Chromatic effects, including the dependence of the betatron tunes on the amplitude, and chromatic perturbations have been investigated taking into account the measured field imperfections. Beam distortion, smear, dynamic aperture and nonlinear acceptance have been calculated for different particle energies and betatron tunes

  19. Effect of Linear and Non-linear Resistance Exercise on Anaerobic Performance among Young Women

    OpenAIRE

    Homa Esmaeili; Ali Reza Amani; Taher Afsharnezhad

    2015-01-01

    The main goals of strength training are improving muscle strength, power and muscle endurance. The objective of the current study is to compare two popular linear and nonlinear resistance exercises interventions on the anaerobic power.  Previous research has shown differences intervention by the linear and non-linear resistance exercise in performance and strength in male athletes. By the way there are not enough data regarding female subjects. Eighteen young women subjects participated in th...

  20. Nonlinear effects on the rotor driven by a motor with limited power

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav

    2007-01-01

    Roč. 1, č. 2 (2007), s. 603-612 ISSN 1802-680X. [Computational Mechanics 2007. Hrad Nečtiny, 05.11.2007-07.11.2007] R&D Projects: GA ČR GA101/06/0063 Institutional research plan: CEZ:AV0Z20760514 Keywords : rotor dynamics * nonlinear oscillations * weak energy source * nonlinear magnetic flux Subject RIV: BI - Acoustics