Energy Exchange Phenomenon Research Articles

Interaction between orthogonal components of single, dual and bound state vector solitons from a fiber laser

We report the interaction between orthogonal components of three types of vector solitons which are generated in a passively mode-locked fiber laser. By adjusting pump power and cavity birefringence, single, dual and bound state vector solitons can be selectively acquired, while all the types of vector solitons reveal energy exchange phenomenon on spectral sidebands. Moreover, the numerical simulation fully reproduces the experimental results, which confirms that the soliton separation is the key parameter that determines the formation of energy exchange sidebands. These results would provide inspirations for the evolution of interaction between solitons and greatly enhance the understanding of soliton dynamics.

Design of an Output Feedback Pressurizer Controller With a Decoupling Precompensator for PWRs

The pressurizer is a crucial component for the safe operation of pressurized water reactors (PWRs). The pressure and level control systems of the pressurizer interact strongly with each other. This cross-coupling between the inputs and outputs makes it difficult for conventional control methods to achieve optimal control effects on both the pressure and level. A simple state feedback control for the pressurizer with a decoupling pressure level precompensator realized using the diagonal matrix method is therefore proposed in this study. A detailed three-zone nonequilibrium dynamic model that reflects the stratification and mass and energy exchange phenomena inside the pressurizer is applied, and a state feedback control that utilizes the physically measurable states of the pressurizer is employed to simplify the state feedback controller to a form that is equivalent to the output feedback control. The improvement of the existing dominant pole placement technique in the feedback controller is described, and the correlation between the parameters and automated tuning methods is also given. The performance of the control system is evaluated through simulations under different operating scenarios to verify the proposed method.

Dynamic Error Correction Method in Tachometric Anemometers for Measurements of Wind Energy

Measurements of air flow velocity are essential at every stage of the design, construction and operation of wind turbines. One of the basic measurement tools in this area is the tachometric anemometer, which is based on the simple physical phenomenon of the air kinetic energy exchange with a rotating measuring element. Tachometric anemometers have favorable operational features and good static metrological parameters. However, in the case of fast-changing flows, the measurement is burdened with a significant dynamic error, and the measured average value of the velocity is overestimated. This article presents the concept and results of pilot studies of a dynamic error correction method of tachometric anemometers. The correction consists of the precise measurement of the rotor’s rotational velocity and determination of the measured air velocity, taking into account the dynamics of the instrument. The developed method can be used in tachometric anemometers intended for laboratory, technical and industrial measurements in time-varying flows. One of the important application areas is the measurement of wind energy.

CFD Study of Airflow and Microclimate Patterns Inside a Multispan Greenhouse

Understanding and improving greenhouses requires the analysis and modelling of energy and mass exchange phenomena. The mastery of all these physical mechanisms can make it possible to propose technological solutions to control the greenhouse climate. This study presents an analysis and simulation of air flow, temperature and humidity patterns ,in ½-ha multi-span greenhouse with oblique side walls,covered by insect proof nets.The site is located in the coastal area of southern Morocco. The fundamental calculation of climatic conditions is based on CFD, wich uses the mass, momentum and energy conservation equations. The dynamic influence of the insect screens and tomato crop on airflow movement, was described ,using the concept of the porous medium approach proposed by Darcy and Forchheimer.The coupling of convective and radiative exchanges at the plastic roof cover is considered. A good agreement was observed between the measured and simulated values for inside air temperatures and relative humidity. Insect screens significantly reduced airflow and increased thermal gradients inside the greenhouse. The results clearly showed the heterogeneity of the greenhouse’s internal climate, which infects agricultural production in quantity and quality

Polarized vector optical compact bright pulse in a weakly anisotropic nonlocal Kerr-like waveguide

A coupled nonlocal nonlinear Schrödinger equation describing the propagation of the polarized vector light pulses in a weakly anisotropic waveguide with nearly instantaneous nonlinear response is introduced in the framework of the slowly varying envelope. This new equation reduces to the scalar nonlocal nonlinear Schrödinger equation in the particular case of a linear polarization of the light beam and, in the dispersionless regime, can support, in addition to the rectilinear polarization, the stable circularly and elliptically polarized compact bright (CB) pulse with an arbitrary nonlinear phase. More interesting, the exact analytical expression of the two-cycle circularly polarized CB pulse is also derived. We believe the results provide useful insight into the interaction between polarized CB pulses, namely, the strength and the period of interaction. It appears that this interaction results from the phenomenon of energy exchange between the two components of CB light pulses and can be suppressed by adjusting either their separation distance and the phase difference or the amplitudes of the two pulses. The efficiency of these analytical results has been confirmed by numerical simulations.

A Study of an Algorithm for the Surface Temperature Forecast: From Road Ice Risk to Farmland Application

The presence of road ice has always been a key issue during winter months. A reliable forecast system capable of predicting the Land Surface Temperature (LST) and, consequently, its formation is one of the best strategies to operate towards reducing both vehicles accidents and waste of chemical solvents used for prevention which have a significant economic and environmental impact. Hence, the Meteo Expert Centre (MEC) has developed an algorithm for LST forecasts able to issue ice risk warnings as well. This algorithm operationally works every day in real-time and it is here tested, first, on a paved area of the Pedemontana Lombarda motorway and the Milano Linate airport airstrip, and, afterwards, since the LST plays a crucial role in understanding phenomena of energy exchange between soil, vegetation, and atmosphere, its knowledge and prediction becomes relevant also for other purposes such as agricultural management and irrigation system control, further experiments are carried out over two agricultural fields, one in the North and the other in the South of Italy during the SIM (Smart Irrigation Management) project. All LST analyses showed encouraging results with reasonable high values of statistical scores, in both applications on asphalted and different vegetated terrains, demonstrating that the developed algorithm has a high versatility even on completely different types of surfaces, and it can be applied as a valid tool for road ice risk warnings too.

Development and validation of a Monte Carlo-based numerical model for solar analyses in urban canyon configurations

Highly- and retro-reflective materials have recently been investigated and proposed as a new urban coating solution to reduce the so-called urban heat island effect. The present study aims at providing a numerical model for assessing inter-buildings solar reflections when these materials are applied to urban canyon's surfaces. The proposed model includes a function that accounts for sunray angle dependency of the solar reflectance, which is specifically important with regard to retro-reflective behavior. The novelty of this numerical model based on a Monte Carlo simulation approach implemented in the Matlab simulation environment is to conduct full ray-tracing solar analyses which can reproduce the energy exchange phenomena and simulate optical material properties. Experimental validation and inter-software comparison are carried out with measured data collected in an experimental facility in La Rochelle, France, in addition to simulation results from the Radiance-based Diva for Rhino tool. The results of the numerical model developed are in line with the values measured in the physical model (daily percent variation of 1.3% in summer) and within the boundary conditions defined in the present work. The residues, which were calculated for the hourly values throughout the day, are found to be in the range of ± 10 W/m2, with the arithmetic average and standard deviation equal to – 2 W/m2 and 7 W/m2 respectively.

Estimation of Growth Rate of Electromagnetic Plasma Wave through Vlasov-Maxwell Mathematical Frame in Ionospheric Plasma

Unique forms of nonlinear wave energy exchange phenomena are observed in the Earth’sionosphere region. Energy upconversion of nonresonant plasma waves in the top ionospheric and auroral zone are noticed.Origin of these phenomena are tried to explained by linear andnonlinear theoretical approach.Wave-wave and wave-particle-wave interaction processes may be possible role takes place here.In this theoretical investigation we wish to derive probable growthrate expression of high frequency electromagnetic O-mode wave in the presence of low frequency electrostatic ion sound wave through wave-particle interaction process known as plasma maserinstability and estimate its value by using observational data.

Gain-modulated plasmonic Rabi oscillations of coupled nanocomplex

Strong coupling in nanostructures can bring intriguing optical phenomena such as ultrafast Rabi oscillation—periodical energy exchange phenomenon between two modes. Rabi splitting appears in the frequency-domain spectra for strong coupling system. However, in metallic nanosystems the time-domain Rabi oscillations are hard to be observed because the plasmon lifetime is limited by the heavy ohmic losses. Here we report a theoretical investigation of surface plasmon coupling behaviour of two gold nanorods with one being a core-shell rod filled with a gain material and find the periodic energy exchange phenomenon which recalls the concept of Rabi oscillation. The gain material-cored gold-shell structure dipolar mode hybridizes with the solid gold rod quadrupolar mode to form the Fano resonances. Energy exchange between the two rods happens through the near field coupling. Two approaches, to prolong plasmon lifetime by increasing the gain efficiency and to increase Rabi oscillation frequency by increasing the coupling strength, are suggested to increase the Rabi oscillation cycles. Our results offer a way to achieve unique control of light at the nanoscale and further to explore plasmonic Rabi oscillation phenomena in plasmonic nanosystems.

Nonlinear dynamics of an asymmetric rotor-bearing system with coupling faults of crack and rub-impact under oil-film forces

The parametric instability of a rotor-bearing system with coupling faults of crack and rub-impact under nonlinear oil-film force is studied in this paper. A model considering time-varying crack stiffness, rub-impact force and nonlinear oil-film force is put forward to analyze the complicated nonlinear behaviors of the rotor-bearing system. The numerical simulation focuses on the effects of crack depth and the stator stiffness on the onset of instability and nonlinear responses of the rotor-bearing system by using bifurcation diagrams, Poincare maps, largest Lyapunov exponent and frequency spectrum. The multiple periodic, quasiperiodic and chaotic motions are observed in this study. The results indicate that crack depth and stator stiffness have influences on the vibration and instability of the rotor-bearing system with varied rotating speed. The motion of the system with coupling faults shows strong nonlinearity and instability in high speed region. Moreover, crack depth and stator stiffness interfere with the formation of oil whirl, thus, making the oil whirl appear later. There also exists interaction among coupling multiple faults. The research discloses the worthy energy exchange phenomenon of multi-fault system and is helpful for fault diagnosis and vibration control of real rotor-bearing systems.

Nonlinear optical vibrations of single-walled carbon nanotubes. 1. Energy exchange and localization of low-frequency oscillations

We present the results of analytical study and molecular dynamics simulation of low energy nonlinear non-stationary dynamics of single-walled carbon nanotubes (CNTs). New phenomena of intense energy exchange between different parts of CNT and weak energy localization in the excited part of CNT are analytically predicted in the framework of the continuum shell theory. Their origin is clarified by means of the concept of Limiting Phase Trajectory, and the analytical results are confirmed by the molecular dynamics simulation of simply supported CNTs.

Формалізація в процесах взаємоперетворення енергії в єдиній теорії взаємодій

Unified theory of interactions is based on reciprocity effects of energy conversion. The reciprocity principle, proposed by the author to explain the mutual transformation of energy between matter and space, contributes to this. It allows combining the processes that take place in the macro- and micro-world. The obtained results explain the phenomenon of energy exchange between matter and space by means of dynamic constants derived in general relativity and formed with the help of gravitational constant and velocity of light. In order to explain the energy exchange between matter and the space, this theory uses the analogy with similar phenomena that occur in the electric oscillatory circuit in which the mutual exchange of energy is carried out through the inertial properties of the components involved in the interaction. This allowed introducing a measure of space inertia along with mass as a measure of substance inertia to explain the phenomena of gravitational transformations. Gravitational forces, acting in the macrocosm, and electromagnetic ones, responsible for the formation of atomic structure, have common nature according to their physical properties and are distinguished only by the intensity of energy exchange processes.

Dynamic simulation and experimental study of an asymmetric double-disk rotor-bearing system with rub-impact and oil-film instability

This study deals with numerical analysis and experimental investigations where the nonlinear dynamic behaviors of an asymmetric double-disk rotor-bearing system are reproduced considering rub-impact and oil-film instability. A dedicated experimental setup was designed to validate the interaction between rubs and oil-film vibration. A model considering nonlinear rub-impact forces and nonlinear oil-film forces is put forward to analyze the complicated nonlinear vibrations of the rotor-bearing system. The experimental study focuses on the interaction of oil-whirl/whip and rub-impact faults, and the results show that the oil-whirl is restrained or even removed, but the whip is uninfluenced when the rub becomes heavy contact. The numerical simulation focuses on the effect of eccentricity and the stator stiffness on the onset of instability and nonlinear responses of the rotor-bearing system by using bifurcation diagrams, Poincare maps, frequency spectrum and three-dimension spectral plots. Agreeing with the experimental results, the results from simulation indicate that the motion of system becomes simple and the oil-whirl gets diminished or even disappeared, but the whip keeps unchanged when the eccentricity or the stator stiffness increases. The research discloses the worthy energy exchange phenomenon of multi-fault system and presents the nonlinear dynamical characteristics of the interaction between rub-impact and oil-film instability for such a rotor-bearing system.

Potential Application in Energy Harvesting of Intermodal Energy Exchange in a Frame: FEM Analysis

This paper presents a Finite Element Analysis (FEA) of modal energy exchange and harvesting in a simple portal frame structure. We consider both horizontal and vertical support excitations resonant first with the first mode (sway mode) and latter with the second mode (the first symmetrical mode). As 2:1 internal resonance is present between these two modes, the phenomena of mode saturation and energy exchange (modal coupling) may occur. Thus, energy pumped into the system through one of the modes, is partially transferred to the other mode, not directly excited. An evaluation of the energy available for harvesting in each of the considered mode is computed.

Near Field Resonator Isolation System: Theory to Implementation

The absence of electromagnetic wave motivates various studies of new communication channels in near field regime. An approach studied here is based on resonant inductive coupling and the use of Resonator Isolation (RI) system. The main concept of the RI system is to physically isolate two inductively coupled resonators from the signal input/output components. The resonators are charged with initial energy, and communicate by exchanging this energy according to the fundamental phenomenon of electromagnetic theory. Analyzing the energy exchange phenomenon, this paper presents two corresponding communication channel models for the RI system. Based on these channel models, the system architecture of the RI system is implemented at a chip level which consists of three components: resonator, analog switch, and digital process.

Energy exchange and transition to localization in the asymmetric Fermi-Pasta-Ulam oscillatory chain

A finite (periodic) FPU chain is chosen as a convenient point for investigating the energy exchange phenomenon in nonlinear oscillatory systems. As we have recently shown, this phenomenon may occur as a consequence of the resonant interaction between high-frequency nonlinear normal modes. This interaction determines both the complete energy exchange between different parts of the chain and the transition to energy localization in an excited group of particles. In the paper, we demonstrate that this mechanism can exist in realistic (asymmetric) models of atomic or molecular oscillatory chains. Also, we study the resonant interaction of conjugated nonlinear normal modes and prove a possibility of linearization of the equations of motion. The theoretical constructions developed in this paper are based on the concepts of "effective particles" and Limiting Phase Trajectories. In particular, an analytical description of energy exchange between the "effective particles" in the terms of non-smooth functions is presented. The analytical results are confirmed with numerical simulations.

Efficient energy transfer between four-wave-mixing and six-wave-mixing processes via atomic coherence

We demonstrate efficient energy exchange during propagation between four-wave-mixing (FWM) and six-wave-mixing (SWM) signals generated in a four-level inverted-Y atomic system, which fall in the electromagnetically induced transparency window. After an initial growth distance for both FWM and SWM fields in the atomic medium, these two nonlinear optical processes compete and exchange energy between them, and eventually reach their respective steady-state values at long interaction distance. This energy exchange phenomenon can be explained by considering established atomic coherences among various atomic states and quantum interferences between three-photon and five-photon excitation pathways. Understanding these high-order nonlinear optical processes and interplays between them can be very important for correlated FWM (or SWM) photon-pair generations and quantum information processing.

A statistical approach for the evaluation of the thermal behavior of dry assembled PCM containing walls

Adequate estimation of the energetic improvements which derived from the insertion of phase change materials (PCM) inside light dry assembled walls is an important step in order to quantify the comfort advantages that can derive from the use of such materials. The use of a statistic approach based fundamentally on the time series analysis method may represent a valid information instrument in support of all the technical analysis carried out in order to evaluate the effects of thermal inertia increase on the heat transmission process that occurs between the elements of a building. PCM containing walls, tested at the “Renewable Energies Outdoor Laboratory” of the Polytechnic University of Marche during the summer of 2003, present delicate problems relative to the identification of physical models relating to dynamics of heat exchange between building components. The application of a vector auto regressive (VAR) estimation model allows, using high frequency experimental data, obtaining consistent estimates regarding the physical phenomenon of energy exchange which intervene inside buildings—both between the walls, and through the walls—occurring during the observation period. The results of this approach are twofold: firstly, they demonstrate the existence of statistically significant linear dependencies among the variables used, and secondly, they highlight the comfort conditions’ improvements due to the insertion of PCM inside dry assembled walls.

A method for determining the states of gas molecules and radicals participating in heterogeneous chemical reactions

A new method is proposed for monitoring the participation of free, preadsorbed, and chemisorbed gas species in chemical reactions at a solid-gas interface. The phenomena of energy exchange in the layer of adsorbed radicals, leading to an increase in the rate of heterogeneous recombination processes, were observed.

Parametric resonance energy exchange and induction phenomenon in a one-dimensional nonlinear oscillator chain

We study analytically the induction phenomenon in the Fermi-Pasta-Ulam beta oscillator chain under initial conditions consisting of single mode excitation. Our study is based on the analytical computation of the largest characteristic exponent of an approximate version of the variational equation. The main results can be summarized as follows: (1) the energy density epsilon scaling of the induction time T is given by T approximately epsilon(-1), and T becomes smaller for higher-frequency mode excitation; (2) there is a threshold energy density epsilon(c) such that the induction time diverges when epsilon<epsilon(c)=pi(2)/6betaN2, where N is the system size and beta the nonlinearity parameter, and this expression for epsilon(c) is correct in the limit N-->infinity; (3) the threshold epsilon(c) vanishes as epsilon(c) approximately N-2 in the limit N-->infinity; (4) the threshold epsilon(c) does not depend on the mode number k that is excited in the initial condition; (5) the two modes k+/-m have the largest exponential growth rate, and m increases with increasing epsilon as m/N=sqrt[3betaepsilon]/pi. The above analytical results are thoroughly verified in numerical experiments. Moreover, we discuss the energy exchange process after the induction period in some energy density regimes, based on the numerical results.