Nonlinear Field Effects Research Articles

Thermal scrutinization of a triangular porous fin induced by linear and nonlinear temperature-dependent heat generation and magnetic field effect: the case of Darcy model

Thermal scrutinization of a triangular porous fin induced by linear and nonlinear temperature-dependent heat generation and magnetic field effect: the case of Darcy model

Quantum torque on a non-reciprocal body out of thermal equilibrium and induced by a magnetic field of arbitrary strength

AbstractA stationary body that is out of thermal equilibrium with its environment, and for which the electric susceptibility is non-reciprocal, experiences a quantum torque. This arises from the spatially non-symmetric electrical response of the body to its interaction with the non-equilibrium thermal fluctuations of the electromagnetic field: the non-equilibrium nature of the thermal field fluctuations results in a net energy flow through the body, and the spatially non-symmetric nature of the electrical response of the body to its interaction with these field fluctuations causes that energy flow to be transformed into a rotational motion. We establish an exact, closed-form, analytical expression for this torque in the case that the environment is the vacuum and the material of the body is described by a damped oscillator model, where the non-reciprocal nature of the electric susceptibility is induced by an external magnetic field, as for magneto-optical media. We also generalise this expression to the context in which the body is slowly rotating. By exploring the high-temperature expansion of the torque, we are able to identify the separate contributions from the continuous spectral distribution of the non-reciprocal electric susceptibility, and from the resonance modes. In particular, we find that the torque persists in the limiting case of zero damping parameter, due to the contribution of the resonance modes. We also consider the low-temperature expansion of the torque. This work extends our previous consideration of this model to an external magnetic field of arbitrary strength, thereby including non-linear magnetic field effects.

Nonlinear field effects in the collector ring due to large-amplitude particle oscillations

In the frame of the FAIR project, the Collector Ring (CR) is planned to be built for efficient cooling of antiprotons and rare isotope beams [1]. In order to accept hot beam from separators large acceptances are required. This paper examines the effects which can influence the beam dynamics due to large betatron oscillation amplitude and momentum spread. Using analytic expressions, the amplitude-dependent tune shifts driven by sextupole magnets, the fringe field of quadrupole magnets, and kinematics effects have been calculated. The obtained results have been compared with numerical simulations by means of precise multi-turn particle tracing. The tracking analysis for the CR has been performed considering the real shape of the magnetic field of the wide aperture quadrupole. We report on quantitative studies of the effects on the dynamic aperture of the rings.

Non-linear thermal radiation and magnetic field effects on the flow Carreau nanofluid with convective conditions

Main features of the present analysis is to investigate the MHD non-linear mixed convection flow of Carreau nanofluid. Flow is due to stretching sheet with thermal and solutal convective conditions. Intention in present analysis is to develop a model for nanomaterial. The non-linear ordinary differential systems are obtained. Homotopy algorithm leads to solutions development. Velocity, temperature, nanoparticles concentration, surface drag force, and heat and mass transfer rate are displayed and argued. It is revealed that qualitative behaviors of velocity and layer thickness are reverse for material and magnetic parameters. Temperature field and heat transfer rate are similar observation for thermal Biot numbers. Moreover qualitative behaviors of nanoparticles concentration and mass transfer rate are reverse for larger Brownian motion.

Einstein Relation for a Driven Disordered Quantum Chain in the Subdiffusive Regime

A quantum particle propagates subdiffusively on a strongly disordered chain when it is coupled to itinerant hard-core bosons. We establish a generalized Einstein relation (GER) that relates such subdiffusive spread to an unusual time-dependent drift velocity, which appears as a consequence of a constant electric field. We show that GER remains valid much beyond the regime of the linear response. Qualitatively, it holds true up to strongest drivings when the nonlinear field effects lead to the Stark-like localization. Numerical calculations based on full quantum evolution are substantiated by much simpler rate equations for the boson-assisted transitions between localized Anderson states.

Study of internal charging of four commonly used polymers through experimental and numerical analysis

This paper focuses on the study of internal charging of four space used polymers: polyetheretherketone, fluorinated ethylene propylene, polyimide films, and epoxy based material (Epoxy FR4). Experiments were carried out for each material using the GEODUR facility (Toulouse, ONERA) that mimics the geostationary space environment behind shielding. Two different irradiation currents have been applied: 1 pA/cm2 and 10 pA/cm2. 1 pA/cm2 is used to analyze the charging behavior and the intrinsic electrical properties of each polymer. 10 pA/cm2 is used to study the influence of high electric field levels on their charging behavior. In this paper, two different numerical tools used for the study of internal charging are presented: Monte-Carlo Internal Charging Tool (MCICT) and Transport of Holes and Electrons Model under Irradiation in Space (THEMIS). MCICT has been used in the space community for several years. THEMIS has been recently developed at ONERA and is compared to MCICT. Both numerical tools showed consistent results for the 1 pA/cm2 integrated current but with deviations for the 10 pA/cm2 integrated current, supposedly due to nonlinear electric field effects on charge transport. THEMIS has a more refined physical model for the conductivity than MCICT. It studies more accurately the electron-polymer interactions and the charge transport kinetics of polymers under space radiations. Subsequently, the analysis of the underlying physical phenomena responsible for the polymers’ charging behaviors will be carried out with THEMIS. In addition, studying these phenomena will permit to assess the risks of electrical discharges that may occur on a spacecraft in orbit (e.g., Geostationary (GEO) spacecraft) or during an elliptic trajectory (e.g., sub-GEO) in an Electric Orbit Raising case [E. Y. Choueiri, A. J. Kelly, and R. G. Jahn, J. Spacecr. Rockets 30(6), 749–754 (1993)].

Spectral investigation of nonlinear local field effects in Ag nanoparticles

The capability of Ag nanoparticles to modulate their optical resonance condition, by optical nonlinearity, without an external feedback system was experimentally demonstrated. These optical nonlinearities were studied in the vicinity of the localized surface plasmon resonance (LSPR), using femtosecond pump-and-probe spectroscopy with a white-light continuum probe. Transient transmission changes ΔT/T exhibited strong photon energy and particle size dependence and showed a complex and non-monotonic change with increasing pump light intensity. Peak position and change of sign redshift with increasing pump light intensity demonstrate the modulation of the LSPR. These features are discussed in terms of the intrinsic feedback via local field enhancement.

Quantum optimal control pathways of ozone isomerization dynamics subject to competing dissociation: A two-state one-dimensional model

We construct a two-state one-dimensional reaction-path model for ozone open → cyclic isomerization dynamics. The model is based on the intrinsic reaction coordinate connecting the cyclic and open isomers with the O2 + O asymptote on the ground-state (1)A(') potential energy surface obtained with the high-level ab initio method. Using this two-state model time-dependent wave packet optimal control simulations are carried out. Two possible pathways are identified along with their respective band-limited optimal control fields; for pathway 1 the wave packet initially associated with the open isomer is first pumped into a shallow well on the excited electronic state potential curve and then driven back to the ground electronic state to form the cyclic isomer, whereas for pathway 2 the corresponding wave packet is excited directly to the primary well of the excited state potential curve. The simulations reveal that the optimal field for pathway 1 produces a final yield of nearly 100% with substantially smaller intensity than that obtained in a previous study [Y. Kurosaki, M. Artamonov, T.-S. Ho, and H. Rabitz, J. Chem. Phys. 131, 044306 (2009)] using a single-state one-dimensional model. Pathway 2, due to its strong coupling to the dissociation channel, is less effective than pathway 1. The simulations also show that nonlinear field effects due to molecular polarizability and hyperpolarizability are small for pathway 1 but could become significant for pathway 2 because much higher field intensity is involved in the latter. The results suggest that a practical control may be feasible with the aid of a few lowly excited electronic states for ozone isomerization.

Magnetic String with a NonlinearU(1)Source

Considering the Einstein gravity in the presence of Born-Infeld type electromagnetic fields, we introduce a class of 4-dimensional static horizonless solutions which produce longitudinal magnetic fields. Although these solutions do not have any curvature singularity and horizon, there exists a conic singularity. We investigate the effects of nonlinear electromagnetic fields on the properties of the solutions and find that the asymptotic behavior of the solutions is adS. Next, we generalize the static metric to the case of rotating solutions and find that the value of the electric charge depends on the rotation parameter. Furthermore, conserved quantities will be calculated through the use of the counterterm method. Finally, we extend four-dimensional magnetic solutions to higher dimensional solutions. We present higher dimensional rotating magnetic branes with maximum rotation parameters and obtain their conserved quantities.

How important is nonlinear piezoelectricity in wurtzite GaN/InN/GaN quantum disk-in-nanowire LED structures?

Numerical investigation is carried out to compare the effects of linear and nonlinear piezoelectric fields on the electronic and optical properties of recently-proposed wurtzite GaN/InN/GaN quantum disk-in-wire LED structures. The computational framework employs a combination of fully atomistic valence force-field molecular mechanics and 10-band \(sp^{3}s\)*-SO tight-binding electronic band-structure models, and accurately captures the interplay between the long-range electro-mechanical fields and the quantum atomicity in the device. In particular, to model piezoelectricity in the wurtzite lattice, four different polarization models (based on the experimental and ab initio coefficients) have been considered in increased order of accuracy. In contrast to recent studies on thin-film quantum well structures, simulation results obtained in this work show that the nonlinear (second-order) piezoelectric contribution has insignificant effects on the overall electronic and optical properties in reduced-dimensionality (nanoscale) disk-in-wire LED structures.

Translational and rotational diffusive motion in liquid water in square-wave time-varying electric fields

Non-equilibrium molecular dynamics (NEMD) simulations of liquid water have been performed at 298K in external square-wave electric fields. Significant non-thermal field effects were noted for coupling of rotational and translational motion with marked increases in diffusion. Non-linear field effects were evident above around 0.05VÅ−1, with enhancements in translational and rotational motion. Translational and librational modes orthogonal to the field’s direction were promoted in higher- and lower-frequency fields, respectively, owing to respective coupling of field periods with dipolar and hydrogen bonding relaxation timescales and promotion of libration about a more ‘stationary’ dipolar alignment for more sustained periods.

Accurate Motion Control of Linear Motors With Adaptive Robust Compensation of Nonlinear Electromagnetic Field Effect

Many control methodologies have been applied to the motion control of linear motor drive systems. Compensations of nonlinearities such as frictions and cogging forces have also been carried out to obtain better tracking performance. However, the relationship between the driving current and the resulting motor force has been assumed to be linear, which is invalid for high driving coil currents due to the saturating electromagnetic field effect. This paper focuses on the effective compensation of nonlinear electromagnetic field effect so that the system can be operated at even higher acceleration or heavier load without losing achievable control performance. Specifically, cubic polynomials with unknown weights are used for an effective approximation of the unknown nonlinearity between the electromagnetic force and the driving current. The effectiveness of such an approximation is verified by offline identification experiments. An adaptive robust control (ARC) algorithm with online tuning of the unknown weights and other system parameters is then developed to account for various uncertainties. Theoretically, the proposed ARC algorithm achieves a guaranteed transient and steady-state performance for position tracking, as well as zero steady-state tracking error when subjected to parametric uncertainties only. Comparative experiments of ARC with and without compensation of electromagnetic nonlinearity done on both axes of a linear-motor-driven industrial gantry are shown. The results show that the proposed ARC algorithm achieves better tracking performance than existing ones, validating the effectiveness of the proposed approach in practical applications.

Adaptive Robust Precision Motion Control of Linear Motors With Integrated Compensation of Nonlinearities and Bearing Flexible Modes

To realize the high performance potential of linear motor drive systems, various nonlinearities inherited to the system and their compensations have been extensively studied during the past decade. However, existing research tends to focus on one or several types of nonlinearities at a time and thus do not offer a complete overall solution. This paper studies precision motion control of linear motors in the presence of parameter variations and disturbances. An adaptive robust control (ARC) algorithm with simultaneous compensation of all significant nonlinearities is developed. Those nonlinearities include Coulomb friction, cogging force, and nonlinear electromagnetic field effect. The proposed ARC with and without nonlinearity compensation have also been implemented on the Y-axis of a linear-motor-driven industrial gantry. Comparative experimental results show that the proposed ARC algorithm with simultaneous compensation of all significant nonlinearities achieves better motion tracking performance than existing ones. In addition, high-frequency structural flexible modes due to bearing, which are neglected in the previous researches, are explicitly identified experimentally, and their effects are carefully examined. Theoretical analysis is then conducted to generate a set of practically useful guidelines on the tuning of controller gains to optimize the achievable performance in practice.

Zeeman Splitting and Nonlinear Field-Dependence in Superfluid 3He

We have studied the acoustic Faraday effect in superfluid 3He up to significantly larger magnetic fields than in previous experiments achieving rotations of the polarization of transverse sound as large as 1710^{\circ}. We report nonlinear field effects, and use the linear results to determine the Zeeman splitting of the imaginary squashing mode (ISQ) frequency in 3He-B.

Acceleration and vacuum temperature

The quantum fluctuations of an "accelerated" vacuum state, that is vacuum fluctuations in the presence of a constant electromagnetic field, can be described by the temperature $\TEH$. Considering $\TEH$ for the gyromagnetic factor $g=1$ we show that $\TEH(g=1)=\THU$, where $\THU$ is the Unruh temperature experienced by an accelerated observer. We conjecture that both particle production and nonlinear field effects inherent in the Unruh accelerated observer case are described by the case $g=1$ QED of strong fields. We present rates of particle production for $g=0,1,2$ and show that the case $g=1$ is experimentally distinguishable from $g=0,2$. Therefore, either accelerated observers are distinguishable from accelerated vacuum or there is unexpected modification of the theoretical framework.

Finite homogeneous electric fields in the projector augmented wave formalism: Applications to linear and nonlinear response

Computation of the effect of finite homogeneous electric fields in periodic systems is described in the context of the projector augmented wave formalism. Generalizing previous norm-conserving implementations, we compute the polarization using the approach of King-Smith and Vanderbilt [Phys. Rev. B 47 (1993) 1651] fully within the projector augmented wave framework, and then minimizing the electric field enthalpy. Applications to simple systems are provided, including both linear and nonlinear field effects, and photoelastic response.

Coupling of translational and rotational motion in chiral liquids in electromagnetic and circularly polarised electric fields

Non-equilibrium molecular dynamics simulations of R and S enantiomers of 1,1-chlorofluoroethane, both for pure liquids and racemic mixtures, have been performed at 298 K in the absence and presence of both electromagnetic (e/m) and circularly polarised electric (CP) fields of varying frequency (100-2200 GHz) and intensity (0.025-0.2 V Å(-1) (rms)). Significant non-thermal field effects were noted in the coupling of rotational and translational motion; for instance, in microwave and far-infrared (MW/IR) e/m fields, marked increases in rotational and translational diffusion vis-à-vis the zero-field case took place at 0.025-0.1 V Å(-1) (rms), with a reduction in translational diffusion vis-à-vis the zero-field case above 0.1 V Å(-1) (rms) above 100 GHz. This was due to enhanced direct coupling of rotational motion with the more intense e/m field at the ideal intrinsic rotational coupling frequency (approximately 700 GHz) leading to such rapidly oscillating rotational motion that extent of translational motion was effectively reduced. In the case of CP fields, rotational and translational diffusion was also enhanced for all intensities, particularly at approximately 700 GHz. For both MW/IR and CP fields, non-linear field effects were evident above around 0.1 V Å(-1) (rms) intensity, in terms of enhancements in translational and rotational motion. Simulation of 90-10 mol. % liquid mixtures of a Lennard-Jones solvent with R and S enantiomer-solutes in MW/IR and CP fields led to more limited promotion of rotational and translational diffusion, due primarily to increased frictional effects. For both e/m and CP fields, examination of the laboratory- and inertial-frame auto- and cross-correlation functions of velocity and angular velocity demonstrated the development of explicit coupling with the external fields at the applied frequencies, especially so in the more intense fields where nonlinear effects come into play. For racemic mixtures, elements of the laboratory- and inertial-frame velocity and angular velocity were found to couple with each other to a lesser extent.

Nonlinear traveling-wave field effect transistors for amplification of short electrical pulses

We investigated the properties of pulse propagation on nonlinear traveling-wave field effect transistors (TW-FET) to develop a method for amplifying short electrical pulses. TW-FETs are a special type of FET whose electrodes are employed not only as electrical contacts but also as transmission lines. Due to the presence of electromagnetic couplings between the gate and drain lines, two different propagation modes called the c mode and π mode are developed on a TW-FET. Moreover, the Schottky contact beneath the gate electrode creates an ideal source of nonlinearity for soliton-like propagation. We can design the TW-FET to amplify only soliton-like pulses carried by one of the two modes and attenuate the ones carried by the other mode. This paper discusses the fundamental properties of a nonlinear TW-FET, including the width and velocity of a soliton-like pulse carried by c and π modes, and gives design criteria of amplification of soliton-like pulses.

Generation of short electrical pulses using nonlinear traveling-wave field effect transistors

We investigated the properties of pulse propagation on nonlinear traveling-wave field effect transistors (TWFET) in order to develop a method for generating short electrical pulses. We considered the case where a decreasing voltage pulse is applied to the gate line and an increasing one is simultaneously applied to the drain line. By properly designing the top and bottom levels of the applied pulses, every FET simulates an electronic switch (the switch is open for voltages greater than some fixed threshold, and closed otherwise). On a line with such switches, a pulse experiences great shortening by the development of steep exponential wave; therefore, a TWFET operates as a short pulse generator.

A comprehensive model for piezoceramic actuators: modelling, validation andapplication

This paper presents a comprehensive model for piezoceramic actuators (PAs), whichaccounts for hysteresis, non-linear electric field and dynamic effects. The hysteresismodel is based on the widely used general Maxwell slip model, while an enhancedelectro-mechanical non-linear model replaces the linear constitutive equations commonlyused. Further on, a linear second order model compensates the frequency response of theactuator. Each individual model is fully characterized from experimental datayielded by a specific PA, then incorporated into a comprehensive ‘direct’ modelable to determine the output strain based on the applied input voltage, fullycompensating the aforementioned effects, where the term ‘direct’ represents anelectrical-to-mechanical operating path. The ‘direct’ model was implemented in aMatlab/Simulink environment and successfully validated via experimental results,exhibiting higher accuracy and simplicity than many published models. This simplicitywould allow a straightforward inclusion of other behaviour such as creep, ageing, materialnon-linearity, etc, if such parameters are important for a particular application.Based on the same formulation, two other models are also presented: the first is an‘alternate’ model intended to operate within a force-controlled scheme (instead of adisplacement/position control), thus able to capture the complex mechanical interactionsoccurring between a PA and its host structure. The second development is an ‘inverse’model, able to operate within an open-loop control scheme, that is, yielding a ‘linearized’PA behaviour. The performance of the developed models is demonstrated via anumerical sample case simulated in Matlab/Simulink, consisting of a PA coupled to asimple mechanical system, aimed at shifting the natural frequency of the latter.