Coupled mode parametric resonance in a vibrating screen model
Slepyan, Leonid I
2013-01-01
We consider a simple dynamic model of the vibrating screen operating in the parametric resonance (PR) mode. This model was used in the course of designing and setting of such a screen in LPMC. The PR-based screen compares favorably with conventional types of such machines, where the transverse oscillations are excited directly. It is characterized by larger values of the amplitude and by insensitivity to damping in a rather wide range. The model represents an initially strained system of two equal masses connected by a linearly elastic string. Self-equilibrated, longitudinal, harmonic forces act on the masses. Under certain conditions this results in transverse, finite-amplitude oscillations of the string. The problem is reduced to a system of two ordinary differential equations coupled by the geometric nonlinearity. Damping in both the transverse and longitudinal oscillations is taken into account. Free and forced oscillations of this mass-string system are examined analytically and numerically. The energy e...
Dynamic modeling and analysis of axial vibration of a coupled propeller and shaft system
Energy Technology Data Exchange (ETDEWEB)
Li, Chenyang; Huang, Xiuchang; Hua, Hongxing [Shanghai Jiao Tong University, Shanghai (China)
2016-07-15
The dynamic and acoustic characteristics of a coupled propeller and shaft system which is modeled by the transfer matrix method are studied. The elasticity of the propeller is taken into consideration by employing the equivalent reduced modeling method. Thus the influence of the elastic propeller on the vibro-acoustic responses of the coupled system is investigated. To reduce the axial vibration of the coupled propeller-shaft system, the influence and location of the vibration isolator on the structural and acoustic responses is presented. Simulation results demonstrate that utilizing the relationship between the natural frequency of the propeller and the resonance frequency range of the shaft can control the vibration of the coupled system without other vibration control method. Utilizing a vibration isolator is another effective way to control vibration. The optimal position for the isolator installed between the shaft and the thrust bearing is investigated.
Meng, Deshan; Wang, Xueqian; Xu, Wenfu; Liang, Bin
2017-05-01
For a space robot with flexible appendages, vibrations of flexible structure can be easily excited during both orbit and/or attitude maneuvers of the base and the operation of the manipulators. Hence, the pose (position and attitude) of the manipulator's end-effector will greatly deviate from the desired values, and furthermore, the motion of the manipulator will trigger and exacerbate vibrations of flexible appendages. Given lack of the atmospheric damping in orbit, the vibrations will last for quite a while and cause the on-orbital tasks to fail. We derived the rigid-flexible coupling dynamics of a space robot system with flexible appendages and established a coupling model between the flexible base and the space manipulator. A specific index was defined to measure the coupling degree between the flexible motion of the appendages and the rigid motion of the end-effector. Then, we analyzed the dynamic coupling for different conditions, such as modal displacements, joint angles (manipulator configuration), and mass properties. Moreover, the coupling map was adopted and drawn to represent the coupling motion. Based on this map, a trajectory planning method was addressed to suppress structure vibration. Finally, simulation studies of typical cases were performed, which verified the proposed models and method. This work provides a theoretic basis for the system design, performance evaluation, trajectory planning, and control of such space robots.
RESEARCH ON ACTIVE VIBRATION CONTROL BASED ON COMBINED MODEL FOR COUPLED SYSTEMS
Institute of Scientific and Technical Information of China (English)
Niu Junchuan; Zhao Guoqun; Song Kongjie
2004-01-01
A novel combined model of the vibration control for the coupled flexible system and its general mathematic description are developed. In presented model, active and passive controls as well as force and moment controls are combined into a single unit to achieve the efficient vibration control of the flexible structures by multi-approaches. Considering the complexity of the energy transmission in the vibrating system, the transmission channels of the power flow transmitted into the foundation are discussed, and the general forces and the corresponding velocities are combined into a single function, respectively. Under the control strategy of the minimum power flow, the transmission characteristics of the power flow are investigated. From the presented numerical examples, it is obvious that the analytical model is effective, and both force and moment controls are able to depress vibration energy substantially.
Electromechanical coupling model and analysis of transient behavior for inertial vibrating machines
Institute of Scientific and Technical Information of China (English)
HU Ji-yun; YU Cui-ping; YIN Xue-gang
2004-01-01
A mathematical model of electromechanical coupling system for a planar inertial vibrating machine is built by setting up dynamical equations of discrete systems with a matrix methodology proposed. The substance of the transient behavior of the machine is unveiled by analyzing the results of the computer simulation to the model, and new methods are presented for diminishing the transient amplitude of the vibrating machine and improving the transient behavior. The reliable mathematical model is provided for intelligent control of the transient behavior of the equipment.
Flow-induced vibrations of long circular cylinders modeled by coupled nonlinear oscillators
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The dynamics of long slender cylinders undergoing vortex-induced vibrations (VIV) is studied in this work. Long slender cylinders such as risers or tension legs are widely used in the field of ocean engineering. When the sea current flows past a cylinder, it will be excited due to vortex shedding. A three-dimensional time domain model is formulated to describe the response of the cylinder, in which the in-line (IL) and cross-flow (CF) deflections are coupled. The wake dynamics, including in-line and cross-flow vibrations, is represented using a pair of non-linear oscillators distributed along the cylinder. The wake oscillators are coupled to the dynamics of the long cylinder with the acceleration coupling term. A non-linear fluid force model is accounted for to reflect the relative motion of cylinder to current. The model is validated against the published data from a tank experiment with the free span riser. The comparisons show that some aspects due to VIV of long flexible cylinders can be reproduced by the proposed model, such as vibrating frequency, dominant mode number, occurrence and transition of the standing or traveling waves. In the case study, the simulations show that the IL curvature is not smaller than CF curvature, which indicates that both IL and CF vibrations are important for the structural fatigue damage.
Coupled electromechanical model of an imperfect piezoelectric vibrating cylinder gyroscope
CSIR Research Space (South Africa)
Loveday, PW
1996-01-01
Full Text Available which is closed at one end with discrete piezoceramic actuation and sensing elements bonded close to the open end. The operation of the gyroscope and the effect of imperfections are briefly described. The model allows direct comparison with experimental...
Institute of Scientific and Technical Information of China (English)
WANG; Yuanzhan; HUA; Leina; DONG; Shaowei
2004-01-01
Vibrating, sliding and uplift rocking are three elementary motion types of caisson breakwaters. The dynamic model and the numerical simulation method of vibrating-sliding-uplift rocking coupled motion of caisson breakwaters are developed. The histories of displacement, rotation, sliding force and overturning moment of a caisson breakwater under the excitation of breaking wave impact are calculated for the motion models of vibrating, vibrating-sliding, vibrating-uplift rocking and vibrating-sliding-uplift rocking. The effects of various motion models on the stability of caisson breakwaters are investigated. The feasibility of the dynamic design idea that the sliding motion and the uplift rocking motion of caisson breakwaters are allowed under the excitation of breaking wave impact is discussed.
Optimizing Vibrational Coordinates To Modulate Intermode Coupling.
Zimmerman, Paul M; Smereka, Peter
2016-04-12
The choice of coordinate system strongly affects the convergence properties of vibrational structure computations. Two methods for efficient generation of improved vibrational coordinates are presented and justified by analysis of a model anharmonic two-mode Hessian and numerical computations on polyatomic molecules. To produce optimal coordinates, metrics which quantify off-diagonal couplings over a grid of Hessian matrices are minimized through unitary rotations of the vibrational basis. The first proposed metric minimizes the total squared off-diagonal coupling, and the second minimizes the total squared change in off-diagonal coupling. In this procedure certain anharmonic modes tend to localize, for example X-H stretches. The proposed methods do not rely on prior fitting of the potential energy, vibrational structure computations, or localization metrics, so they are unique from previous vibrational coordinate generation algorithms and are generally applicable to polyatomic molecules. Fitting the potential to the approximate n-mode representation in the optimized bases for all-trans polyenes shows that off-diagonal anharmonic couplings are substantially reduced by the new choices of coordinate system. Convergence of vibrational energies is examined in detail for ethylene, and it is shown that coupling-optimized modes converge in vibrational configuration interaction computations to within 1 cm(-1) using only 3-mode couplings, where normal modes require 4-mode couplings for convergence. Comparison of the vibrational configuration interaction convergence with respect to excitation level for the two proposed metrics shows that minimization of the total off-diagonal coupling is most effective for low-cost vibrational structure computations.
Coupling between plate vibration and acoustic radiation
Frendi, Abdelkader; Maestrello, Lucio; Bayliss, Alvin
1993-01-01
A detailed numerical investigation of the coupling between the vibration of a flexible plate and the acoustic radiation is performed. The nonlinear Euler equations are used to describe the acoustic fluid while the nonlinear plate equation is used to describe the plate vibration. Linear, nonlinear, and quasi-periodic or chaotic vibrations and the resultant acoustic radiation are analyzed. We find that for the linear plate response, acoustic coupling is negligible. However, for the nonlinear and chaotic responses, acoustic coupling has a significant effect on the vibration level as the loading increases. The radiated pressure from a plate undergoing nonlinear or chaotic vibrations is found to propagate nonlinearly into the far field. However, the nonlinearity due to wave propagation is much weaker than that due to the plate vibrations. As the acoustic wave propagates into the far field, the relative difference in level between the fundamental and its harmonics and subharmonics decreases with distance.
Pennacchi, Paolo; Vania, Andrea
2008-07-01
The diagnostics of malfunctions that can cause catastrophic failures has to be made in early stage in the industrial environment. Often flexible couplings are employed in industrial rotating machines when gearboxes and heavy thermal gradients are present. The hot and cold alignment of these couplings can be very different. Severe misalignments can generate cracks in the stub shafts, which can propagate in operating condition. Owing to the flexural flexibility of the load coupling, the shaft vibrations may be not noticeably affected by some typical symptoms that usually point out the presence of a crack, like twice per revolution harmonics in the vibration spectrum. Anyhow, suitable diagnostic strategies can detect clear fault symptoms, while model-based methods can confirm the occurrence of the shaft bow induced by the progressive yielding of a load coupling due to a crack. This paper shows as a model-based diagnostic methodology would have allowed a crack in a load coupling of a gas turbine to be identified before a serious failure happened by means of the shaft vibration analysis under operating conditions and rated speed. Finally, the vibrations caused by the shaft bow due to the propagation of a crack in the stub shaft of the coupling have been simulated using suitable equivalent excitations, the magnitude and phase of which have been estimated by means of a model-based identification method.
COUPLING VIBRATION OF VEHICLE-BRIDGE SYSTEM
Institute of Scientific and Technical Information of China (English)
陈炎; 黄小清; 马友发
2004-01-01
By applying the sinusoidal wave mode to simulate the rugged surface of bridge deck,accounting for vehicle-bridge interaction and using Euler-Bernoulli beam theory, a coupling vibration model of vehicle-bridge system was developed. The model was solved by mode analyzing method and Runge-Kutta method, and the dynamic response and the resonance curve of the bridge were obtained. It is found that there are two resonance regions, one represents the main resonance while the other the minor resonance, in the resonance curve. The influence due to the rugged surface, the vibration mode of bridge, and the interaction between vehicle and bridge on vibration of the system were discussed. Numerical results show that the influence due to these parameters is so significant that the effect of roughness of the bridge deck and the mode shape of the bridge can't be ignored and the vehicle velocity should be kept away from the critical speed of the vehicle.
the Analysis of Coupled Lateral Torsional Vibrations
Directory of Open Access Journals (Sweden)
Tomasz Szolc
2000-01-01
Full Text Available In the paper, dynamic investigations of the rotor shaft systems are performed by means of the discrete-continuous mechanical models. In these models the rotor shaft segments are represented by the rotating cylindrical flexurally and torsionally deformable continuous viscoelastic elements. These elements are mutually connected according to the structure of the real system in the form of a stepped shaft which is suspended on concentrated inertial viscoelastic supports of linear or non-linear characteristics. At appropriate shaft crosssections, by means of massless membranes, there are attached rigid rings representing rotors, disks, gears, flywheels and others. The proposed model enables us to investigate coupled linear or non-linear lateral torsional Vibrations of the rotating systems in steady-state and transient operating conditions. As demonstrative examples, for the steam turbo-compressor under coupled lateral torsional vibrations, the transient response due to a blade falling out from the turbine rotor as well as the steady-state response in the form of parametric resonance caused by residual unbalances are presented.
Directory of Open Access Journals (Sweden)
Yufei Liu
2015-01-01
Full Text Available This paper investigates the dynamic of a flexible robotic manipulator (FRM which consists of rigid driving base, flexible links, and flexible joints. With considering the motion fluctuations caused by the coupling effect, such as the motor parameters and mechanism inertias, as harmonic disturbances, the system investigated in this paper remains a parametrically excited system. An elastic restraint model of the FRM with elastic joints (FRMEJ is proposed, which considers the elastic properties of the connecting joints between the flexible arm and the driving base, as well as the harmonic disturbances aroused by the electromechanical coupling effect. As a consequence, the FRMEJ accordingly remains a flexible multibody system which conveys the effects of rigid-flexible couple and electromechanical couple. The Lagrangian function and Hamilton’s principle are used to establish the dynamic model of the FRMEJ. Based on the dynamic model proposed, the vibration power flow is introduced to show the vibration energy distribution. Numerical simulations are conducted to investigate the effect of the joint elasticities and the disturbance excitations, and the influences of the structure parameters and motion parameters on the vibration power flow are studied. The results obtained in this paper contribute to the structure design, motion optimization, and vibration control of FRMs.
Institute of Scientific and Technical Information of China (English)
Fang Wang; Yan-chun Lou; Rui Chen; Zhao-wei Song; Bao-kuan Li
2015-01-01
The vibrating electrode method was proposed in the electro-slag remelting (ESR) process in this paper, and the effect of vibrating electrode on the solidiifcation structure of ingot was studied. A transient three-dimensional (3D) coupled mathematical model was established to simulate the electromagnetic phenomenon, fluid flow as well as pool shape in the ESR process with the vibrating electrode. The finite element volume method is developed to solve the electromagnetic field using ANSYS mechanical APDL software. Moreover, the electromagnetic force and Joule heating are interpolated as the source term of the momentum and energy equations. The multi-physical fields have been investigated and compared between the traditional electrode and the vibrating electrode in the ESR process. The results show that the drop process of metal droplets with the traditional electrode is scattered randomly. However, the drop process of metal droplets with the vibrating electrode is periodic. The highest temperature of slag layer with the vibrating electrode is higher than that with the traditional electrode, which can increase the melting rate due to the enhanced heat transfer in the vicinity of the electrode tip. The results also show that when the amplitude and frequency of the vibrating electrode increase, the cycle of drop process of metal droplets decreases signiifcantly.
Directory of Open Access Journals (Sweden)
Fang Wang
2015-07-01
Full Text Available The vibrating electrode method was proposed in the electro-slag remelting (ESR process in this paper, and the effect of vibrating electrode on the solidification structure of ingot was studied. A transient three-dimensional (3D coupled mathematical model was established to simulate the electromagnetic phenomenon, fluid flow as well as pool shape in the ESR process with the vibrating electrode. The finite element volume method is developed to solve the electromagnetic field using ANSYS mechanical APDL software. Moreover, the electromagnetic force and Joule heating are interpolated as the source term of the momentum and energy equations. The multi-physical fields have been investigated and compared between the traditional electrode and the vibrating electrode in the ESR process. The results show that the drop process of metal droplets with the traditional electrode is scattered randomly. However, the drop process of metal droplets with the vibrating electrode is periodic. The highest temperature of slag layer with the vibrating electrode is higher than that with the traditional electrode, which can increase the melting rate due to the enhanced heat transfer in the vicinity of the electrode tip. The results also show that when the amplitude and frequency of the vibrating electrode increase, the cycle of drop process of metal droplets decreases significantly.
Institute of Scientific and Technical Information of China (English)
GU Ji-jun; AN Chen; LEVI Carlos; SU Jian
2012-01-01
The Generalized Integral Transform Technique (GITT) was applied to predict dynamic response of Vortex-Induced Vibration (VIV) of a long flexible cylinder.A nonlinear wake oscillator model was used to represent the cross-flow force acting on the cylinder,leading to a coupled system of second-order Partial Differential Equations (PDEs) in temporal variable.The GITT approach was used to transform the system of PDEs to a system of Ordinary Differential Equations (ODEs),which was numerically solved by using the Adams-Moulton and Gear method (DIVPAG) developed by the International Mathematics and Statistics Library (IMSL).Numerical results were presented for comparison to those given by the finite difference method and experimental results,allowing a critical evaluation of the technique performance.The influence of variation of mean axial tension induced by elongation of flexible cylinder was evaluated,which was shown to be not negligible in numerical simulation of VIV of a long flexible cylinder.
Diesel engine torsional vibration control coupling with speed control system
Guo, Yibin; Li, Wanyou; Yu, Shuwen; Han, Xiao; Yuan, Yunbo; Wang, Zhipeng; Ma, Xiuzhen
2017-09-01
The coupling problems between shafting torsional vibration and speed control system of diesel engine are very common. Neglecting the coupling problems sometimes lead to serious oscillation and vibration during the operation of engines. For example, during the propulsion shafting operation of a diesel engine, the oscillation of engine speed and the severe vibration of gear box occur which cause the engine is unable to operate. To find the cause of the malfunctions, a simulation model coupling the speed control system with the torsional vibration of deformable shafting is proposed and investigated. In the coupling model, the shafting is simplified to be a deformable one which consists of several inertias and shaft sections and with characteristics of torsional vibration. The results of instantaneous rotation speed from this proposed model agree with the test results very well and are successful in reflecting the real oscillation state of the engine operation. Furthermore, using the proposed model, the speed control parameters can be tuned up to predict the diesel engine a stable and safe running. The results from the tests on the diesel engine with a set of tuned control parameters are consistent with the simulation results very well.
Intermediate coupling vibrational descriptions of odd mass gold isotopes
Vieu, C; Paar, V
1976-01-01
The theoretical analysis of /sup 193-195/Au levels is semi qualitatively performed in the frame of the intermediate coupling vibrational models of Kisslinger-Sorensen and Alaga. From the comparison between the experimental data and the corresponding predictions of the two models, conclusions are drawn on the influence of the clusters and broken pairs.
Amyay, Badr; Robert, Séverine; Herman, Michel; Fayt, André; Raghavendra, Balakrishna; Moudens, Audrey; Thiévin, Jonathan; Rowe, Bertrand; Georges, Robert
2009-09-21
A high temperature source has been developed and coupled to a high resolution Fourier transform spectrometer to record emission spectra of acetylene around 3 mum up to 1455 K under Doppler limited resolution (0.015 cm(-1)). The nu(3)-ground state (GS) and nu(2)+nu(4)+nu(5) (Sigma(u) (+) and Delta(u))-GS bands and 76 related hot bands, counting e and f parities separately, are assigned using semiautomatic methods based on a global model to reproduce all related vibration-rotation states. Significantly higher J-values than previously reported are observed for 40 known substates while 37 new e or f vibrational substates, up to about 6000 cm(-1), are identified and characterized by vibration-rotation parameters. The 3 811 new or improved data resulting from the analysis are merged into the database presented by Robert et al. [Mol. Phys. 106, 2581 (2008)], now including 15 562 lines accessing vibrational states up to 8600 cm(-1). A global model, updated as compared to the one in the previous paper, allows all lines in the database to be simultaneously fitted, successfully. The updates are discussed taking into account, in particular, the systematic inclusion of Coriolis interaction.
LI, M.; YU, L.
2001-05-01
The misalignment of a gear coupling in a multirotor system is an important problem; it can cause various faults. In the present work the non-linear coupled lateral torsional vibration model of rotor-bearing-gear coupling system is developed based on the engagement conditions of gear couplings. Theoretical analysis shows that the forces and moments acting on gear couplings due to the initial misalignment are from the inertia forces of the sleeve and the internal damping between the meshing teeth, and depend on the misalignment, internal damping, the rotating speed, and the structural parameters of the gear coupling. Numerical analysis of the signature of vibration reveals that the even-integer multiples of the rotating speed of lateral vibration and the odd-integer multiples of the torsional vibration occur in the misaligned system, and the integer multiples of vibration are apparent around the gear coupling.
Nonlinear analysis on the coupling process of electromagnetic vibrator and earth
Institute of Scientific and Technical Information of China (English)
CHEN; Zubin; TENG; Jiwen; LIN; Jun; ZHANG; Linhang; JIANG
2005-01-01
The linear model based on the hydraulic pressure vibrator has been no longer adaptable to the electromagnetic vibrator. In order to realize the effective transmission of the limited energy from the vibrator to the ground, it is important to study the coupling model of the electromagnetic vibrator and the earth. In this paper, a nonlinear restore term was introduced to the coupling model because of the existence of a large amount of harmonics in the vibrator baseplate. The nonlinear vibration analysis was applied to the model by the multiscale method. In the course of energy transmission from the vibrator to the ground, ultraharmonic resonance was used to explain the generation of harmonics. An improved scheme was advanced to select the cross correlation reference signal in the vibrator seismic exploration. Good application results were obtained in field experiments.
Communication: Creation of molecular vibrational motions via the rotation-vibration coupling
Energy Technology Data Exchange (ETDEWEB)
Shu, Chuan-Cun [Department of Chemistry, Technical University of Denmark, Building 207, DK-2800 Kongens Lyngby (Denmark); School of Engineering and Information Technology, University of New South Wales at the Australian Defence Force Academy, Canberra, ACT 2600 (Australia); Henriksen, Niels E., E-mail: neh@kemi.dtu.dk [Department of Chemistry, Technical University of Denmark, Building 207, DK-2800 Kongens Lyngby (Denmark)
2015-06-14
Building on recent advances in the rotational excitation of molecules, we show how the effect of rotation-vibration coupling can be switched on in a controlled manner and how this coupling unfolds in real time after a pure rotational excitation. We present the first examination of the vibrational motions which can be induced via the rotation-vibration coupling after a pulsed rotational excitation. A time-dependent quantum wave packet calculation for the HF molecule shows how a slow (compared to the vibrational period) rotational excitation leads to a smooth increase in the average bond length whereas a fast rotational excitation leads to a non-stationary vibrational motion. As a result, under field-free postpulse conditions, either a stretched stationary bond or a vibrating bond can be created due to the coupling between the rotational and vibrational degrees of freedom. The latter corresponds to a laser-induced breakdown of the adiabatic approximation for rotation-vibration coupling.
Martinez, J.; Belahcen, A.; Detoni, J. G.
2016-01-01
This paper presents a coupled Finite Element Model in order to study the vibrations in induction motors under steady-state. The model utilizes a weak coupling strategy between both magnetic and elastodynamic fields on the structure. Firstly, the problem solves the magnetic vector potential in an axial cut and secondly the former solution is coupled to a three dimensional model of the stator. The coupling is performed using projection based algorithms between the computed magnetic solution and the three-dimensional mesh. The three-dimensional model of the stator includes both end-windings and end-shields in order to give a realistic picture of the motor. The present model is validated using two steps. Firstly, a modal analysis hammer test is used to validate the material characteristic of this complex structure and secondly an array of accelerometer sensors is used in order to study the rotating waves using multi-dimensional spectral techniques. The analysis of the radial vibrations presented in this paper firstly concludes that slot harmonic components are visible when the motor is loaded. Secondly, the multidimensional spectrum presents the most relevant mechanical waves on the stator such as the ones produced by the space harmonics or the saturation of the iron core. The direct retrieval of the wave-number in a multi-dimensional spectrum is able to show the internal current distribution in a non-intrusive way. Experimental results for healthy induction motors are showing mechanical imbalances in a multi-dimensional spectrum in a more straightforward form.
COUPLED VIBRATION OF STRUCTURAL THIN-WALLED CORES
Institute of Scientific and Technical Information of China (English)
Shiu Cho; J.S. Kuang
2000-01-01
This paper presents an analysis of the coupled vibration of asymmetric core structures in tall buildings. The governing equation of free vibration and its corresponding eigenvalue problem, which is a set of equations for laterally flexural vibrations in two different directions coupled by a warping-St. Venant torsional vibration, are derived. Based on the Calerkin method, a generalized approximate method is developed for the analysis of coupled vibration and thus proposed for determining the natural fiequeneies and mode shapes of the structure in triply-coupled vibration. The results of the proposed method for the example structure show good agreement with those of the FEM analysis. The proposed method has been shown to provide a sim ple and rapid, yet accurate, means for coupled vibration analysis of core structures.
Vibrationally coupled electron transport through single-molecule junctions
Energy Technology Data Exchange (ETDEWEB)
Haertle, Rainer
2012-04-26
Single-molecule junctions are among the smallest electric circuits. They consist of a molecule that is bound to a left and a right electrode. With such a molecular nanocontact, the flow of electrical currents through a single molecule can be studied and controlled. Experiments on single-molecule junctions show that a single molecule carries electrical currents that can even be in the microampere regime. Thereby, a number of transport phenomena have been observed, such as, for example, diode- or transistor-like behavior, negative differential resistance and conductance switching. An objective of this field, which is commonly referred to as molecular electronics, is to relate these transport phenomena to the properties of the molecule in the contact. To this end, theoretical model calculations are employed, which facilitate an understanding of the underlying transport processes and mechanisms. Thereby, one has to take into account that molecules are flexible structures, which respond to a change of their charge state by a profound reorganization of their geometrical structure or may even dissociate. It is thus important to understand the interrelation between the vibrational degrees of freedom of a singlemolecule junction and the electrical current flowing through the contact. In this thesis, we investigate vibrational effects in electron transport through singlemolecule junctions. For these studies, we calculate and analyze transport characteristics of both generic and first-principles based model systems of a molecular contact. To this end, we employ a master equation and a nonequilibrium Green's function approach. Both methods are suitable to describe this nonequilibrium transport problem and treat the interactions of the tunneling electrons on the molecular bridge non-perturbatively. This is particularly important with respect to the vibrational degrees of freedom, which may strongly interact with the tunneling electrons. We show in detail that the resulting
On Kinetics Modeling of Vibrational Energy Transfer
Gilmore, John O.; Sharma, Surendra P.; Cavolowsky, John A. (Technical Monitor)
1996-01-01
Two models of vibrational energy exchange are compared at equilibrium to the elementary vibrational exchange reaction for a binary mixture. The first model, non-linear in the species vibrational energies, was derived by Schwartz, Slawsky, and Herzfeld (SSH) by considering the detailed kinetics of vibrational energy levels. This model recovers the result demanded at equilibrium by the elementary reaction. The second model is more recent, and is gaining use in certain areas of computational fluid dynamics. This model, linear in the species vibrational energies, is shown not to recover the required equilibrium result. Further, this more recent model is inconsistent with its suggested rate constants in that those rate constants were inferred from measurements by using the SSH model to reduce the data. The non-linear versus linear nature of these two models can lead to significant differences in vibrational energy coupling. Use of the contemporary model may lead to significant misconceptions, especially when integrated in computer codes considering multiple energy coupling mechanisms.
Nonlinear thermoelectric properties of molecular junctions with vibrational coupling
DEFF Research Database (Denmark)
Leijnse, Martin Christian; Wegewijs, M. R.; Flensberg, Karsten
2010-01-01
We present a detailed study of the nonlinear thermoelectric properties of a molecular junction, represented by a dissipative Anderson-Holstein model. A single-orbital level with strong Coulomb interaction is coupled to a localized vibrational mode and we account for both electron and phonon...... exchange with both electrodes, investigating how these contribute to the heat and charge transports. We calculate the efficiency and power output of the device operated as a heat to electric power converter in the regime of weak tunnel coupling and phonon exchange rate and identify the optimal operating...... conditions, which are found to be qualitatively changed by the presence of the vibrational mode. Based on this study of a generic model system, we discuss the desirable properties of molecular junctions for thermoelectric applications....
Modal analysis of coupled vibration of belt drive systems
Institute of Scientific and Technical Information of China (English)
LI Xiao-jun; CHEN Li-qun
2008-01-01
The modal method is applied to analyze coupled vibration of belt drive systems. A belt drive system is a hybrid system consisting of continuous belts modeled as strings as well as discrete pulleys and a tensioner arm. The characteristic equation of the system is derived from the governing equation. Numerical results demenstrate the effects of the transport speed and the initial tension on natural frequencies.
Communication: creation of molecular vibrational motions via the rotation-vibration coupling
DEFF Research Database (Denmark)
Shu, Chuan-Cun; Henriksen, Niels Engholm
2015-01-01
Building on recent advances in the rotational excitation of molecules, we show how the effect of rotation-vibration coupling can be switched on in a controlled manner and how this coupling unfolds in real time after a pure rotational excitation. We present the first examination of the vibrational...... motions which can be induced via the rotation-vibration coupling after a pulsed rotational excitation. A time-dependent quantum wave packet calculation for the HF molecule shows how a slow (compared to the vibrational period) rotational excitation leads to a smooth increase in the average bond length...... whereas a fast rotational excitation leads to a non-stationary vibrational motion. As a result, under field-free postpulse conditions, either a stretched stationary bond or a vibrating bond can be created due to the coupling between the rotational and vibrational degrees of freedom. The latter corresponds...
Analyzing a Vibrating Wire Transducer using Coupled Resonator Circuits
Directory of Open Access Journals (Sweden)
POP, S.
2015-08-01
Full Text Available This paper intends to be an approach on the vibrating wire transducer from the perspective of the necessary rules used for a correct measurement procedure. There are several studies which analyze the vibrating wire transducer as a mechanical system. However, a comparative time-domain analysis between the mechanical and the electrical model is lacking. The transducer analysis is based on a theoretical analysis of the equivalent circuit, on both excitation and response time intervals. The electrical model consists of two magnetic coupled resonating circuits. When connected to an excitation source, there will be an energy transfer from the coil to the wire. The maximum energy transfer will occur at the vibrating wire's frequency of resonance. Using the transient regime analysis, it has been proven that, in the response time interval - when the wire vibrates freely, the current through the circuit that models the wire describes the oscillating movement of the wire. A complex signal is obtained, that contains both coil's and wire's frequencies of resonance, strongly dependent with theirs parasitic elements. The mathematical analysis highlights the similarity between mechanical and electrical model and the procedures in order to determine the wire frequency of resonance from the output signal.
Cases of coupled vibrations and prametric instability in rotating machines
Luneno, Jean-Claude
2012-01-01
The principal task in this research project was to analyse the causes and consequences of coupled vibrations and parametric instability in hydropower rotors; where both horizontal and vertical machines are involved. Vibration is a well-known undesirable behavior of dynamical systems characterised by persistent periodic, quasi-periodic or chaotic motions. Vibrations generate noise and cause fatigue, which initiates cracks in mechanical structures. Motions coupling can in some cases augment the...
Quan Zhang; Chaodong Li; Jiantao Zhang; Jiamei Jin
2016-01-01
This paper addresses the active vibration control and coupled vibration analysis of a planar parallel manipulator (PPM) with three flexible links. Multiple piezoelectric ceramic transducers are integrated with the flexible links to constitute the smart beam structures, and hence the vibration of the flexible link can be self-sensed and self-controlled. To prevent the spillover phenomena and improve the vibration control efficiency, the independent modal space control combined with an input sh...
Directory of Open Access Journals (Sweden)
Zhou Danfeng
2017-01-01
Full Text Available The maglev vehicle-girder coupled vibration problem has been encountered in many maglev test or commercial lines, which significantly degrade the performance of the maglev train. In previous research on the principle of the coupled vibration problem, it has been discovered that the fundamental model of the maglev girder can be simplified as a series of mass-spring resonators of different but related resonance frequencies, and that the stability of the vehicle-girder coupled system can be investigated by separately examining the stability of each mass-spring resonator – electromagnet coupled system. Based on this conclusion, a maglev test platform, which includes a single electromagnetic suspension control system, is built for experimental study of the coupled vibration problem. The guideway of the test platform is supported by a number of springs so as to change its flexibility. The mass of the guideway can also be changed by adjusting extra weights attached to it. By changing the flexibility and mass of the guideway, the rules of the maglev vehicle-girder coupled vibration problem are to be examined through experiments, and related theory on the vehicle-girder self-excited vibration proposed in previous research is also testified.
Intramolecular vibrational dynamical barrier due to extremely irrational couplings
Institute of Scientific and Technical Information of China (English)
2007-01-01
The intramolecular vibrational dynamics due to extremely irrational couplings is demonstrated by contrast to the resonance couplings, for the three-mode case of H2O as an example. The extremely irrational couplings are shown to impose such strong hindrance to intramolecular vibrational relaxation (IVR) that they act as barriers. They restrict the direct action/energy transfer between the two stretching modes, though they allow the transfer between a stretching and a bending modes. In contrast, the resonance is more mediated by the bending mode and leads to chaotic IVR. It is also shown that there is a region in the dynamical space in which resonance and extremely irrational couplings coexist.
Analytical Evaluation of the Nonlinear Vibration of Coupled Oscillator Systems
DEFF Research Database (Denmark)
Bayat, M.; Shahidi, M.; Barari, Amin
2011-01-01
We consider periodic solutions for nonlinear free vibration of conservative, coupled mass-spring systems with linear and nonlinear stiffnesses. Two practical cases of these systems are explained and introduced. An analytical technique called energy balance method (EBM) was applied to calculate ap...... accuracy which is valid for a wide range of vibration amplitudes as indicated in the presented examples.......We consider periodic solutions for nonlinear free vibration of conservative, coupled mass-spring systems with linear and nonlinear stiffnesses. Two practical cases of these systems are explained and introduced. An analytical technique called energy balance method (EBM) was applied to calculate...
Automatic derivation and evaluation of vibrational coupled cluster theory equations
Seidler, Peter; Christiansen, Ove
2009-12-01
A scheme for automatic derivation and evaluation of the expressions occurring in vibrational coupled cluster theory is introduced. The method is based on a Baker-Campbell-Hausdorff expansion of the similarity transformed Hamiltonian and is general both with respect to the excitation level in the parameter space and the mode coupling level in the Hamiltonian. In addition to deriving general expressions, intermediates that lower the computational scaling are automatically detected. The final equations are then evaluated. Due to the commutator based nature of the algorithm, it is also applicable to the evaluation of quantities needed for response theory. Different aspects of the theory and implementation are illustrated by calculations on model systems. Furthermore, all fundamental excitation energies of ethylene oxide are calculated.
VIBRATION ANALYSIS OF TURBINE BASED ON FLUID-STRUCTURE COUPLING
Institute of Scientific and Technical Information of China (English)
LIU Demin; LIU Xiaobing
2008-01-01
The vibration of a Francis turbine is analyzed with the additional quality matrix method based on fluid-structure coupling (FSC). Firstly, the vibration frequency and mode of blade and runner in air and water are calculated. Secondly, the influences to runner frequency domain by large flow, small flow and design flow working conditions are compared. Finally the influences to runner modes by centrifugal forces under three rotating speeds of 400 r/min, 500 r/min and 600 r/min are compared. The centrifugal force and small flow working condition have greatly influence on the vibration of small runner. With the increase of centrifugal force, the vibration frequency of the runner is sharply increased. Some order frequencies are even close to the runner natural frequency in the air. Because the low frequency vibration will severely damage the stability of the turbine, low frequency vibration of units should be avoided as soon as possible.
Global nonresonant vibrational-photoelectron coupling in molecular photoionization
Poliakoff, Erwin; Das, Aloke; Hardy, David; Bozek, John; Aguilar, Alex; Lucchese, Robert
2009-05-01
Using photoelectron spectroscopy and Schwinger variational scattering theory, we have investigated the coupling between vibrational motion and the exiting photoelectron over extended ranges of photoelectron kinetic energy. Photoelectron spectroscopy is performed with vibrational resolution over uncommonly large ranges of energy (ca. 200 eV). We find clear and significant changes in vibrational branching ratios as a function of photon energy, in direct contradiction to predictions of the Franck-Condon principle. While it is well known that resonances lead to coupling between electronic and vibrational degrees of freedom, nonresonant mechanisms that result in such coupling are not expected or well-documented. Photoelectron spectra are presented for several electronic states of N2^+, CO^+, and NO^+, and we find that valence isoelectronic channels behave very differently, which is also surprising. Theoretical results indicate that Cooper minima are the underlying cause of these effects, and we are currently working to understand the reasons for the sensitivity of the Cooper minima on bond length.
Computation of expectation values from vibrational coupled-cluster at the two-mode coupling level
DEFF Research Database (Denmark)
Zoccante, Alberto; Seidler, Peter; Christiansen, Ove
2011-01-01
In this work we show how the vibrational coupled-cluster method at the two-mode coupling level can be used to calculate zero-point vibrational averages of properties. A technique is presented, where any expectation value can be calculated using a single set of Lagrangian multipliers computed...
Computation of expectation values from vibrational coupled-cluster at the two-mode coupling level
DEFF Research Database (Denmark)
Zoccante, Alberto; Seidler, Peter; Christiansen, Ove
2011-01-01
In this work we show how the vibrational coupled-cluster method at the two-mode coupling level can be used to calculate zero-point vibrational averages of properties. A technique is presented, where any expectation value can be calculated using a single set of Lagrangian multipliers computed...
Directory of Open Access Journals (Sweden)
M. Mohammadimehr
2013-12-01
Full Text Available In this article, the bending and free vibration analysis of functionally graded (FG nanocomposites Timoshenko beam model reinforced by single-walled boron nitride nanotube (SWBNNT using micro-mechanical approach embedded in an elastic medium is studied. The modified coupled stress (MCST and nonlocal elasticity theories are developed to take into account the size-dependent effect. The mechanical properties of FG boron nitride nanotube-reinforced composites are assumed to be graded in the thickness direction and estimated through the micro-mechanical approach. The governing equations of motion are obtained using Hamilton’s principle based on Timoshenko beam theory. The Navier's type solution is implemented to solve the equations that satisfy the simply supported boundary conditions. Furthermore, the influences of the slenderness ratio, length of nanocomposite beam, material length scale parameter, nonlocal parameter, power law index, axial wave number, and Winkler and Pasternak coefficients on the natural frequency of nanocomposite beam are investigated. Also, the effect of material length scale parameter on the dimensionless deflection of FG nanocomposite beam is studied.
Wang, Haobin; Thoss, Michael
2016-12-01
The accuracy of the noninteracting electron approximation is examined for a model of vibrationally coupled electron transport in single molecule junction. In the absence of electronic-vibrational coupling, steady state transport in this model is described exactly by Landauer theory. Including coupling, both electronic-vibrational and vibrationally induced electron-electron correlation effects may contribute to the real time quantum dynamics. Using the multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) theory to describe nuclear dynamics exactly while maintaining the noninteracting electron approximation for the electronic dynamics, the correlation effects are analyzed in different physical regimes. It is shown that although the noninteracting electron approximation may be reasonable for describing short time dynamics, it does not give the correct long time limit for certain initial conditions.
Evolution of photoelectron-vibrational coupling with molecular complexity
Energy Technology Data Exchange (ETDEWEB)
Poliakoff, E D [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Lucchese, R R [Department of Chemistry, Texas A and M University, College Station, TX 77843 (United States)
2006-11-15
We review how electronic and vibrational degrees of freedom become coupled in molecular photoionization, and describe effects that emerge as the molecular complexity increases. Molecular photoionization is frequently influenced by the temporary trapping of the continuum electron in the field of the target molecules, which is referred to as a shape resonance, as it depends on the shape of the potential experienced by the exiting photoelectron. Such resonances couple electronic and vibrational motion, and the nature of the coupling can vary widely for polyatomic molecules. We show how vibrationally resolved photoelectron spectra acquired as a function of energy can be used to elucidate such coupling. The experiments are analysed using physically realistic and computationally tractable Schwinger variational theory, and the systems studied to date can be well understood using an independent-particle, adiabatic nuclei framework. As a result, simple and intuitive pictures emerge, even when dealing with scattering phenomena involving complex molecular targets and potentials.
Mechanical Vibrations Modeling and Measurement
Schmitz, Tony L
2012-01-01
Mechanical Vibrations:Modeling and Measurement describes essential concepts in vibration analysis of mechanical systems. It incorporates the required mathematics, experimental techniques, fundamentals of modal analysis, and beam theory into a unified framework that is written to be accessible to undergraduate students,researchers, and practicing engineers. To unify the various concepts, a single experimental platform is used throughout the text to provide experimental data and evaluation. Engineering drawings for the platform are included in an appendix. Additionally, MATLAB programming solutions are integrated into the content throughout the text. This book also: Discusses model development using frequency response function measurements Presents a clear connection between continuous beam models and finite degree of freedom models Includes MATLAB code to support numerical examples that are integrated into the text narrative Uses mathematics to support vibrations theory and emphasizes the practical significanc...
THEORETICAL MODEL OF VIBRATING OBJECT TRANSMITTING NOISE TOWARDS EXTERNAL SOUND
Institute of Scientific and Technical Information of China (English)
姚志远
2002-01-01
On the basic theory of modal method, the coupling relation between the vibration of objects and external sound was analyzed, the theoretical model solving the vibration and noise was provided, the corresponding calculation formula was given. The calculating results show out that this calculation formula is correct.
Molecular Nitrogen Vibrational Temperature in an Inductively Coupled Plasma
Institute of Scientific and Technical Information of China (English)
康正德; 蒲以康
2002-01-01
Using a technique applied previously to vibrationally excited molecular nitrogen (N*2) in the region of daytime and nighttime aurora, the emission intensity of the N2 second positive band system in an inductively coupled plasma (ICP) has been analysed and the vibrational temperature of nitrogen molecules in the ICP is thus determined. The result shows that the vibrational temperature increases with the increase of the neutral gas pressure from 0.04Pa to 10Pa, then decreases with the further increase of the pressure from 10Pa to 100Pa. Also,this is explained by using the Boltzmann relation between the vibrational temperature and the concentration of the vibrationally excited N*2(X1∑+g ) molecules.
DEFF Research Database (Denmark)
Santos, Ilmar; Saracho, C.M.; Smith, J.T.
2004-01-01
This work gives a theoretical and experimental contribution to the problem of rotor-blades dynamic interaction. A validation procedure of mathematical models is carried out with help of a simple test rig, built by a mass-spring system attached to four flexible rotating blades. With this test rig,...
ANALYSIS OF THE IMPACT OF FLEXIBLE COUPLINGS ON GEARBOX VIBRATIONS
Directory of Open Access Journals (Sweden)
Robert GREGA
2016-06-01
Full Text Available Dangerous vibrations of mechanical systems’ components are causes of failures and reduction in service life, as well lead to negative effects on the environment and the health of operators. In order to reduce these unwanted vibrations, it is necessary to pay attention to the proper design of components in mechanical systems. The aim of this article is based on the experimental measurements and demonstration of the effects of different types of flexible couplings on the size of vibration in a gearbox that forms part of a mechanical system.
A comprehensive vibration analysis of a coupled rotor/fuselage system
Yeo, Hyeonsoo
A comprehensive vibration analysis of a coupled rotor/fuselage system for a two-bladed teetering rotor using finite element methods in space and time is developed which incorporates consistent rotor/fuselage structural, aerodynamic, and inertial couplings and a modern free wake model. A coordinate system is developed to take into account a teetering rotor's unique characteristics, such as teetering motion and undersling. Coupled nonlinear periodic blade and fuselage equations are transformed to the modal space in the fixed frame and solved simultaneously. The elastic line and detailed 3-D NASTRAN finite element models of the AH-1G helicopter airframe from the DAMVIBS program are integrated into the elastic rotor finite element model. Analytical predictions of rotor control angles, blade loads, hub forces, and vibration are compared with AH-1G Operation Load Survey flight test data. The blade loads predicted by present analysis show generally fair agreement with the flight test data, especially blade chord bending moment estimation shows good agreement. Calculated 2/rev vertical vibration levels at pilot seat show good correlation with the flight test data both in magnitude and phase, but 4/rev vibration levels show fair correlation only in magnitude. Lateral vibration results show more disagreement than vertical vibration results. Pylon flexibility effect is essential in the two-bladed teetering rotor vibration analysis. The pylon flexibility increases the first lag frequency by about 14%, and decreases 2/rev longitudinal and lateral hub forces by more than half. Rotor/fuselage coupling reduces 2/rev vertical and lateral vibration levels by 60% to 70% and has a small effect on 4/rev vibration levels. Modeling of difficult components (secondary structures, doors/panels, etc) is essential in predicting airframe natural frequencies. Refined aerodynamics such as free wake and unsteady aerodynamics have an important role in the prediction of vibration. For example, free
Source model for blasting vibration
Institute of Scientific and Technical Information of China (English)
DING; Hua(丁桦); ZHENG; Zhemin(郑哲敏)
2002-01-01
By analyzing and comparing the experimental data, the point source moment theory and the cavity theory, it is concluded that the vibrating signals away from the blasting explosive come mainly from the natural vibrations of the geological structures near the broken blasting area. The source impulses are not spread mainly by the inelastic properties (such as through media damping, as believed to be the case by many researchers) of the medium in the propagation pass, but by this structure. Then an equivalent source model for the blasting vibrations of a fragmenting blasting is proposed, which shows the important role of the impulse of the source's time function under certain conditions. For the purpose of numerical simulation, the model is realized in FEM, The finite element results are in good agreement with the experimental data.
An ultrasonic atomizing device using coupled-mode vibration
Toda, Kohji; Akimura, Yoshikazu
1994-10-01
A small, compact ultrasonic atomizing device is composed of a rectangular piezoelectric ceramic bar and a metal plate with minute holes. The resonance arising from the coupling between two vibration modes in the ceramic bar is used for the effective device operation. The best atomizing occurs when one of the coupled-mode resonant frequencies of the atomizing device is equal to that of the device without the metal vibrating plate. For an efficient power usage a self-oscillation type circuit, composed of the atomizing device as a resonant element and a power amplification transistor, is utilized.
Coupling between flexural modes in free vibration of single-walled carbon nanotubes
Directory of Open Access Journals (Sweden)
Rumeng Liu
2015-12-01
Full Text Available The nonlinear thermal vibration behavior of a single-walled carbon nanotube (SWCNT is investigated by molecular dynamics simulation and a nonlinear, nonplanar beam model. Whirling motion with energy transfer between flexural motions is found in the free vibration of the SWCNT excited by the thermal motion of atoms where the geometric nonlinearity is significant. A nonlinear, nonplanar beam model considering the coupling in two vertical vibrational directions is presented to explain the whirling motion of the SWCNT. Energy in different vibrational modes is not equal even over a time scale of tens of nanoseconds, which is much larger than the period of fundamental natural vibration of the SWCNT at equilibrium state. The energy of different modes becomes equal when the time scale increases to the microsecond range.
Coupling between flexural modes in free vibration of single-walled carbon nanotubes
Energy Technology Data Exchange (ETDEWEB)
Liu, Rumeng; Wang, Lifeng, E-mail: walfe@nuaa.edu.cn [State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, 210016 Nanjing (China)
2015-12-15
The nonlinear thermal vibration behavior of a single-walled carbon nanotube (SWCNT) is investigated by molecular dynamics simulation and a nonlinear, nonplanar beam model. Whirling motion with energy transfer between flexural motions is found in the free vibration of the SWCNT excited by the thermal motion of atoms where the geometric nonlinearity is significant. A nonlinear, nonplanar beam model considering the coupling in two vertical vibrational directions is presented to explain the whirling motion of the SWCNT. Energy in different vibrational modes is not equal even over a time scale of tens of nanoseconds, which is much larger than the period of fundamental natural vibration of the SWCNT at equilibrium state. The energy of different modes becomes equal when the time scale increases to the microsecond range.
Directory of Open Access Journals (Sweden)
Xin Lai
2016-01-01
Full Text Available Industrial simulation of real external load using multiple exciting points or increasing exciting force by synchronizing multiple exciting forces requires multiple vibration hammers to be coordinated and work together. Multihammer vibration system which consists of several hammers is a complex electromechanical system with complex electromechanical coupling. In this paper, electromechanical coupling properties of such a multihammer vibration system were studied in detail using theoretical derivation, numerical simulation, and experiment. A kinetic model of multihammer synchronous vibration system was established, and approximate expressions for electromechanical coupling strength were solved using a small parameter periodic averaging method. Basic coupling rules and reasons were obtained. Self-synchronization and frequency hopping phenomenon were also analyzed. Subsequently, numerical simulations were carried out and electromechanical coupling process was obtained for different parameters. Simulation results verify correctness of the proposed model and results. Finally, experiments were carried out, self-synchronization and frequency hopping phenomenon were both observed, and results agree well with theoretical deduction and simulation results. These results provide theoretical foundations for multihammer synchronous vibration system and its synchronous control.
Modelling of vibration of gear transmissions
Zeman, Vladimir; Nemecek, Josef
The method for mathematical modeling of spatial vibrations of the spur gear transmissions is presented. This method enables a substantial reduction of the number of degrees of freedom with relatively high accuracy in calculating vibration amplitude.
Strong Coupling between Surface Plasmon Polaritons and Molecular Vibrations
Memmi, H.; Benson, O.; Sadofev, S.; Kalusniak, S.
2017-03-01
We report on the strong coupling of surface plasmon polaritons and molecular vibrations in an organic-inorganic plasmonic hybrid structure consisting of a ketone-based polymer deposited on top of a silver layer. Attenuated-total-reflection spectra of the hybrid reveal an anticrossing in the dispersion relation in the vicinity of the carbonyl stretch vibration of the polymer with an energy splitting of the upper and lower polariton branch up to 15 meV. The splitting is found to depend on the molecular layer thickness and saturates for micrometer-thick films. This new hybrid state holds a strong potential for application in chemistry and optoelectronics.
Yue, Shuai; Wang, Zhuan; Leng, Xuan; Zhu, Rui-Dan; Chen, Hai-Long; Weng, Yu-Xiang
2017-09-01
Low vibrational modes in a range of 80-400 cm-1 for bacteriochlorophyll a are excited and observed as beating dynamics in two-dimensional electronic spectra. A coupled multi-vibrational mode displaced oscillator model is proposed to account for the vibronic coherence. We found that these low frequency vibrational modes are coupled. By comparing the fitted lifetime of the vibrational modes appearing in the beating dynamics for bacteriochlorophyll a and a protein-bound bacteriochlorophyll a dimer B820 probed by transient grating method, it is suggested that the protein scaffold provides a protection effect on the vibronic coherence where no excitonic coherence has be excited.
National Research Council Canada - National Science Library
Juan Wu Ziming Kou
2016-01-01
Using the mass of time-varying length balance rope focused on the hoisting conveyance, the coupling longi- tudinal-transverse model of mine friction hoist was established by using of the Hamilton＇s principle...
Directory of Open Access Journals (Sweden)
Xiang Xu
2013-09-01
Full Text Available This paper presents a novel method to nonlinearly investigate the dynamics of the coupled axial and torsional vibrations in the circular cross section beam of the steam turbine generator using the FFT analysis. Firstly, the coupled axial and torsional vibrations of a beam are proved by equivalent law of shearing stress and different boundary conditions. Then, a nonlinear mathematical model of the coupled axial and torsional vibrations is established by the Galerkin method. Lastly, the fast Fourier transform (FFT is employed to investigate the coupled effect of the beam vibration. A practical calculation example is calculated numerically and the coupled mechanism of the beam’s axial and torsional vibrations is analyzed in detail. The analysis results show that the frequencies of the coupled response would be existed in some special orders and the coupled response frequencies are smaller than the single vibration. Since for the first time the coupled mechanism of the beam’s axial and torsional vibrations is theoretically analyzed, the findings in this work may provide directive reference for practical engineering problems in design of steam turbine generators.
Diomede, P.; Bruneau, B.; Longo, S.; Johnson, E.; Booth, J. P.
2017-01-01
A comprehensive hybrid model of a hydrogen capacitively coupled plasmas (CCP), including a detailed description of the molecular vibrational kinetics, has been applied to the study of the effect of tailored voltage waveforms (TVWs) on the production kinetics and transport of negative ions in these
Intermediate vibrational coordinate localization with harmonic coupling constraints
Hanson-Heine, Magnus W. D.
2016-05-01
Optimized normal coordinates can significantly improve the speed and accuracy of vibrational frequency calculations. However, over-localization can occur when using unconstrained spatial localization techniques. The unintuitive mixtures of stretching and bending coordinates that result can make interpreting spectra more difficult and also cause artificial increases in mode-coupling during anharmonic calculations. Combining spatial localization with a constraint on the coupling between modes can be used to generate coordinates with properties in-between the normal and fully localized schemes. These modes preserve the diagonal nature of the mass-weighted Hessian matrix to within a specified tolerance and are found to prevent contamination between the stretching and bending vibrations of the molecules studied without a priori classification of the different types of vibration present. Relaxing the constraint can also be used to identify which normal modes form specific groups of localized modes. The new coordinates are found to center on more spatially delocalized functional groups than their fully localized counterparts and can be used to tune the degree of vibrational correlation energy during anharmonic calculations.
Dynamic Characteristics Analysis of the Coupled Lateral-Torsional Vibration with Spur Gear System
Shihua Zhou; Zhaohui Ren; Guiqiu Song; Bangchun Wen
2015-01-01
A sixteen-degree-of-freedom (16-DOF) lumped parameter dynamic model taking into account the gravity, eccentricity, bearing clearance, transmission error, and coupled lateral-torsional vibration is established. Based on the dynamical equation, the dynamic behaviors of the spur gear rotor bearing system are investigated by using Runge-Kutta method. The research focuses on the effect of rotational speed, eccentricity, and bearing clearance and nonlinear response of the coupled multibody dynamics...
Schinabeck, C.; Erpenbeck, A.; Härtle, R.; Thoss, M.
2016-11-01
Within the hierarchical quantum master equation (HQME) framework, an approach is presented, which allows a numerically exact description of nonequilibrium charge transport in nanosystems with strong electronic-vibrational coupling. The method is applied to a generic model of vibrationally coupled transport considering a broad spectrum of parameters ranging from the nonadiabatic to the adiabatic regime and including both resonant and off-resonant transport. We show that nonequilibrium effects are important in all these regimes. In particular, in the off-resonant transport regime, the inelastic cotunneling signal is analyzed for a vibrational mode in full nonequilibrium, revealing a complex interplay of different transport processes and deviations from the commonly used G0/2 rule of thumb. In addition, the HQME approach is used to benchmark approximate master equation and nonequilibrium Green's function methods.
Comparison of Vibrational Relaxation Modeling for Strongly Non-Equilibrium Flows
2014-01-01
145 .98 4396 V. Summary and Conclusions The form of two vibrational relaxation models that are commonly used in DSMC and CFD simula- tions have been...Technical Paper 3. DATES COVERED (From - To) Dec 2013 – Jan 2014 4. TITLE AND SUBTITLE Comparison of Vibrational Relaxation Modeling for Strongly Non...including experimental gas measurement techniques , shock layer vibration-dissociation coupling, and vibrational energy freezing in strong expansions
Dynamic Characteristics Analysis of the Coupled Lateral-Torsional Vibration with Spur Gear System
Directory of Open Access Journals (Sweden)
Shihua Zhou
2015-01-01
Full Text Available A sixteen-degree-of-freedom (16-DOF lumped parameter dynamic model taking into account the gravity, eccentricity, bearing clearance, transmission error, and coupled lateral-torsional vibration is established. Based on the dynamical equation, the dynamic behaviors of the spur gear rotor bearing system are investigated by using Runge-Kutta method. The research focuses on the effect of rotational speed, eccentricity, and bearing clearance and nonlinear response of the coupled multibody dynamics is presented by vibration waveform, spectrum, and 3D frequency spectrum. The results show that the rotational frequency of the driven gear appears in the driving gear, and the dynamic characteristics of gears have obvious differences due to the effects of the gear assembly and the coupled lateral-torsional vibration. The bearing has its own resonance frequency, and the effect of the variable stiffness frequency of the bearings should be avoided during the system design. The results presented in this paper show an analysis of the coupled lateral-torsional vibration of the spur gear system. The study may contribute to a further understanding of the dynamic characteristics of such a spur gear rotor bearing system.
Corrigan, J. C.; Cronkhite, J. D.; Dompka, R. V.; Perry, K. S.; Rogers, J. P.; Sadler, S. G.
1989-01-01
Under a research program designated Design Analysis Methods for VIBrationS (DAMVIBS), existing analytical methods are used for calculating coupled rotor-fuselage vibrations of the AH-1G helicopter for correlation with flight test data from an AH-1G Operational Load Survey (OLS) test program. The analytical representation of the fuselage structure is based on a NASTRAN finite element model (FEM), which has been developed, extensively documented, and correlated with ground vibration test. One procedure that was used for predicting coupled rotor-fuselage vibrations using the advanced Rotorcraft Flight Simulation Program C81 and NASTRAN is summarized. Detailed descriptions of the analytical formulation of rotor dynamics equations, fuselage dynamic equations, coupling between the rotor and fuselage, and solutions to the total system of equations in C81 are included. Analytical predictions of hub shears for main rotor harmonics 2p, 4p, and 6p generated by C81 are used in conjunction with 2p OLS measured control loads and a 2p lateral tail rotor gearbox force, representing downwash impingement on the vertical fin, to excite the NASTRAN model. NASTRAN is then used to correlate with measured OLS flight test vibrations. Blade load comparisons predicted by C81 showed good agreement. In general, the fuselage vibration correlations show good agreement between anslysis and test in vibration response through 15 to 20 Hz.
Optimization of Vibration Reduction Ability of Ladder Tracks by FEM Coupled with ACO
Directory of Open Access Journals (Sweden)
Hao Jin
2015-01-01
Full Text Available Ladder track, which has drawn increased attention in scientific communities, is an effective method for reducing vibrations from underground railways. In order to optimize the vibration reduction ability of ladder track, a new method, that is, the finite element method (FEM coupled with ant colony optimization (ACO, has been proposed in this paper. We describe how to build the FEM model verified by the vibration tests in the Track Vibration Abatement and Control Laboratory and how to couple the FEM with ACO. The density and elasticity modulus of the sleeper pad are optimized using this method. After optimization, the vibration acceleration level of the supporting platform in the 1–200 Hz range was reduced from 102.8 dB to 94.4 dB. The optimized density of the sleeper pad is 620 kg/m3, and the optimized elasticity modulus of the sleeper pad is 6.25 × 106 N/m2.
Bifurcation analysis of coupled lateral/torsional vibrations of rotor systems
Lee, Kyoung-Hyun; Han, Hyung-Suk; Park, Sungho
2017-01-01
This paper presents a numerical method to analyze the bifurcation of coupled lateral/torsional vibrations of rotor systems. Based on a Hamiltonian approach, a three degree-of-freedom dynamic model of a rotor is derived. Nonlinear ordinary differential equations are derived from the dynamic model. The stability of the equilibrium and linear normal modes (LNMs) are analyzed using a linearized matrix of the system equation. For bifurcation analysis of the periodic orbits, a nonlinear normal modes (NNMs) computation algorithm is performed using multiple shooting methods and pseudo-arclength continuation. Multiple shooting points are continued from LNMs near equilibrium, bifurcation points of the NNMs are detected from the stability change of the periodic orbits during the continuation. The proposed stability analysis, an NNMs computation of coupled lateral/torsional vibration, is demonstrated using two different rotor models: a system with strong eccentricity, and a system with weak eccentricity.
Molina, Andrew; Smereka, Peter; Zimmerman, Paul M.
2016-03-01
The use of alternate coordinate systems as a means to improve the efficiency and accuracy of anharmonic vibrational structure analysis has seen renewed interest in recent years. While normal modes (which diagonalize the mass-weighted Hessian matrix) are a typical choice, the delocalized nature of this basis makes it less optimal when anharmonicity is in play. When a set of modes is not designed to treat anharmonicity, anharmonic effects will contribute to inter-mode coupling in an uncontrolled fashion. These effects can be mitigated by introducing locality, but this comes at its own cost of potentially large second-order coupling terms. Herein, a method is described which partially localizes vibrations to connect the fully delocalized and fully localized limits. This allows a balance between the treatment of harmonic and anharmonic coupling, which minimizes the error that arises from neglected coupling terms. Partially localized modes are investigated for a range of model systems including a tetramer of hydrogen fluoride, water dimer, ethene, diphenylethane, and stilbene. Generally, partial localization reaches ˜75% of maximal locality while introducing less than ˜30% of the harmonic coupling of the fully localized system. Furthermore, partial localization produces mode pairs that are spatially separated and thus weakly coupled to one another. It is likely that this property can be exploited in the creation of model Hamiltonians that omit the coupling parameters of the distant (and therefore uncoupled) pairs.
Energy Technology Data Exchange (ETDEWEB)
Schröter, M.; Ivanov, S.D.; Schulze, J. [Institut für Physik, Universität Rostock, D-18051 Rostock (Germany); Polyutov, S.P. [Institut für Physik, Universität Rostock, D-18051 Rostock (Germany); Laboratory for Nonlinear Optics and Spectroscopy, Siberian Federal University, Svobodniy, 79, 660041 Krasnoyarsk (Russian Federation); Yan, Y. [Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Normal College, Guizhou 550018 (China); Pullerits, T. [Department of Chemical Physics, Lund University, P.O. Box 124, S-22100 Lund (Sweden); Kühn, O., E-mail: oliver.kuehn@uni-rostock.de [Institut für Physik, Universität Rostock, D-18051 Rostock (Germany)
2015-03-18
The influence of exciton–vibrational coupling on the optical and transport properties of molecular aggregates is an old problem that gained renewed interest in recent years. On the experimental side, various nonlinear spectroscopic techniques gave insight into the dynamics of systems as complex as photosynthetic antennae. Striking evidence was gathered that in these protein–pigment complexes quantum coherence is operative even at room temperature conditions. Investigations were triggered to understand the role of vibrational degrees of freedom, beyond that of a heat bath characterized by thermal fluctuations. This development was paralleled by theory, where efficient methods emerged, which could provide the proper frame to perform non-Markovian and non-perturbative simulations of exciton–vibrational dynamics and spectroscopy. This review summarizes the state of affairs of the theory of exciton–vibrational interaction in molecular aggregates and photosynthetic antenna complexes. The focus is put on the discussion of basic effects of exciton–vibrational interaction from the stationary and dynamics points of view. Here, the molecular dimer plays a prominent role as it permits a systematic investigation of absorption and emission spectra by numerical diagonalization of the exciton–vibrational Hamiltonian in a truncated Hilbert space. An extension to larger aggregates, having many coupled nuclear degrees of freedom, becomes possible with the Multi-Layer Multi-Configuration Time-Dependent Hartree (ML-MCTDH) method for wave packet propagation. In fact it will be shown that this method allows one to approach the limit of almost continuous spectral densities, which is usually the realm of density matrix theory. Real system–bath situations are introduced for two models, which differ in the way strongly coupled nuclear coordinates are treated, as a part of the relevant system or the bath. A rather detailed exposition of the Hierarchy Equations Of Motion (HEOM
Search for particle–vibration coupling in 65Cu
Directory of Open Access Journals (Sweden)
Bocchi Giovanni
2014-03-01
Full Text Available The lifetime of the 9/2+ state of 65Cu, at 2534 keV, has been measured by fast timing techniques, in order to establish wether such state arises from a weak coupling between a p3/2 proton and the 3− octupole vibration at 3.56 MeV in the 64Ni core. The 65Cu nucleus was populated by the reaction 7Li + 64Ni at 32 MeV, at the Horia Hulubei National Institute of Physics and Nuclear Engineering (NIPNE in Bucharest, and its γ-decay was detected by the ROSPHERE array. The measured lifetime coresponds to a B(E3 reduced transition probability to the ground state equal to 8.89 W.u., in agreement with theoretical predictions in the weak coupling limit.
Particle vibrational coupling in covariant density functional theory
Ring, P; 10.1134/S1063778809080055
2009-01-01
A consistent combination of covariant density functional theory (CDFT) and Landau-Migdal Theory of Finite Fermi Systems (TFFS) is presented. Both methods are in principle exact, but Landau-Migdal theory cannot describe ground state properties and density functional theory does not take into account the energy dependence of the self-energy and therefore fails to yield proper single-% particle spectra as well as the coupling to complex configurations in the width of giant resonances. Starting from an energy functional, phonons and their vertices are calculated without any further parameters. They form the basis of particle-vibrational coupling leading to an energy dependence of the self-energy and an induced energy-dependent interaction in the response equation. A subtraction procedure avoids double counting. Applications in doubly magic nuclei and in a chain of superfluid nuclei show excellent agreement with experimental data.
A Coupling Vibration Test Bench and the Simulation Research of a Maglev Vehicle
Directory of Open Access Journals (Sweden)
Weihua Ma
2015-01-01
Full Text Available To study the characteristics of the coupling vibration between a maglev vehicle and its track beam system and to improve the performance of the levitation system, a new type of vibration test bench was developed. Take a single maglev frame as the study object; simulation of the coupling vibration of the maglev vehicle, levitation system, and track beam were achieved. In addition, all types of real track irregularity excitations can be simulated using hydraulic actuators of the test bench. To expand the research scope, a simulation model was developed that can conduct the simulation research synergistically with the test bench. Based on a dynamics model of the test bench, the dynamics simulation method determined the influence on the levitation control performance of three factors: the track beam support stiffness, the track beam mass, and the track irregularity. The vibration resonance phenomenon of the vehicle/track system was reproduced by the dynamics simulation, and a portion of the simulation results were validated by the test results. By combining the test bench and the dynamics model, experiments can be guided by the simulation results, and the experimental results can validate the dynamics simulation results.
Vibration analysis of hydropower house based on fluid-structure coupling numerical method
Directory of Open Access Journals (Sweden)
Shu-he WEI
2010-03-01
Full Text Available By using the shear stress transport (SST model to predict the effect of random flow motion in a fluid zone, and using the Newmark method to solve the oscillation equations in a solid zone, a coupling model of the powerhouse and its tube water was developed. The effects of fluid-structure interaction are considered through the kinematic and dynamic conditions applied to the fluid-structure interfaces (FSI. Numerical simulation of turbulent flow through the whole flow passage of the powerhouse and concrete structure vibration analysis in the time domain were carried out with the model. Considering the effect of coupling the turbulence and the powerhouse structure, the time history response of both turbulent flows through the whole flow passage and powerhouse structure vibration were generated. Concrete structure vibration analysis shows that the displacement, velocity, and acceleration of the dynamo floor respond dramatically to pressure fluctuations in the flow passage. Furthermore, the spectrum analysis suggests that pressure fluctuation originating from the static and dynamic disturbances of hydraulic turbine blades in the flow passage is one of the most important vibration sources.
Institute of Scientific and Technical Information of China (English)
刘波; 王有志; 安俊江; 王艺霖; 袁泉
2014-01-01
为准确模拟行驶车辆作用下刚性路面的动力响应，建立车辆-路面空间耦合振动精细化分析模型。车辆采用质点-弹簧-阻尼器空间整车模型，混凝土刚性路面采用弹性地基板有限元模型，采用改进的谐波叠加法考虑路面平整度的三维空间分布，利用车轮和路面的位移协调方程将车辆振动和路面振动联立求解。实例分析表明，所建立的车-路耦合振动模型能够真实地反映车辆和路面间的空间几何耦合关系和力学耦合关系；在三维路面不平度的激励下，车辆和路面的动态响应均表现出明显的空间分布特性；与瞬态动力分析方法相比，利用考虑路面不平度空间分布的车-路耦合振动模型对混凝土路面进行车辆动力响应分析时，路面弯沉和板底应力有明显增大。%A fine spatial vehicle-pavement coupling vibration model was established to simulate the dynamic responses of rigid pavement under moving vehicle, in which the mass-spring-damper model was adopted for the vehicle and the fi-nite element model based on the Winkler foundation was adopted for the concrete pavement.The improved harmonic su-perposition method was used to consider the 3-D distribution of road surface roughness, and the displacement coordina-tion equation was used for the simultaneous solution of the vehicle and pavement vibration.Example analysis showed that the established vehicle-pavement coupling vibration model could truly reflect the space geometric and mechanical coupling relationship between vehicle and pavement.With the stimulus of three-dimensional road roughness, the dy-namic response of the vehicle and pavement showed significant spatial distribution characteristics.Comparing with the results of the transient dynamic analysis method, the deflection and stress of the pavement significantly increased.
On the Nonlinear Behavior of the Piezoelectric Coupling on Vibration-Based Energy Harvesters
Directory of Open Access Journals (Sweden)
Luciana L. Silva
2015-01-01
Full Text Available Vibration-based energy harvesting with piezoelectric elements has an increasing importance nowadays being related to numerous potential applications. A wide range of nonlinear effects is observed in energy harvesting devices and the analysis of the power generated suggests that they have considerable influence on the results. Linear constitutive models for piezoelectric materials can provide inconsistencies on the prediction of the power output of the energy harvester, mainly close to resonant conditions. This paper investigates the effect of the nonlinear behavior of the piezoelectric coupling. A one-degree of freedom mechanical system is coupled to an electrical circuit by a piezoelectric element and different coupling models are investigated. Experimental tests available in the literature are employed as a reference establishing the best matches of the models. Subsequently, numerical simulations are carried out showing different responses of the system indicating that nonlinear piezoelectric couplings can strongly modify the system dynamics.
Material Model Research on Rubber Vibration Isolators
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
A viscohyperelastic constitutive model is proposed to describe the mechanical behaviour of vibration isolation rubber under broad-band vibration. This constitutive model comprises two parts: a component with three parameters to characterize the hyperelastic static properties of rubber materials,and the other component incorporating two relaxation time parameters, corresponding to high and low strain rates, respectively, to describe the dynamic response under vibration and impact loadings. Based on this proposed constitutive model, a series of experiments were performed on two types of rubber materials over a wide strain rate range. The results predicted from this model are in good agreement with the experimental data.
Optimization procedure to control the coupling of vibration modes in flexible space structures
Walsh, Joanne L.
1987-01-01
As spacecraft structural concepts increase in size and flexibility, the vibration frequencies become more closely-spaced. The identification and control of such closely-spaced frequencies present a significant challenge. To validate system identification and control methods prior to actual flight, simpler space structures will be flown. To challenge the above technologies, it will be necessary to design these structures with closely-spaced or coupled vibration modes. Thus, there exists a need to develop a systematic method to design a structure which has closely-spaced vibration frequencies. This paper describes an optimization procedure which is used to design a large flexible structure to have closely-spaced vibration frequencies. The procedure uses a general-purpose finite element analysis program for the vibration and sensitivity analyses and a general-purpose optimization program. Results are presented from two studies. The first study uses a detailed model of a large flexible structure to design a structure with one pair of closely-spaced frequencies. The second study uses a simple equivalent beam model of a large flexible structure to obtain a design with two pairs of closely-spaced frequencies.
The modelling of industrial robot manipulator vibration
Energy Technology Data Exchange (ETDEWEB)
Marcham, L.J.; Rao, B.K.N.; Noroozi, S.; Penson, R.P. [Southampton Inst. (United Kingdom). Systems Engineering Research Centre
1996-11-01
The work reported in this paper addresses the modelling of robot manipulator vibration, with the specific aim of producing a model suitable to be employed within an active compensation controller. An overview of existing work on the modelling of robot dynamics, both mathematically and empirically, is reported. A model of the dynamics of an industrial manipulator, inclusive of vibration, derived using Lagrangian mechanics is presented and further developed through the application of experimental modal analysis, by which the position dependent modal parameters of an industrial robot manipulator are determined. The model results are compared with experimental vibration data taken from the end-effector of a PUMA562C industrial manipulator using laser interferometry. Control of an end-effector located, active compensator for vibration suppression, based upon the derived model is discussed and recommendations which form the basis of further investigations, currently being undertaken, are presented.
Adamovich, Igor V.; Ploenjes, Elke; Palm, Peter; Rich, J. William; Chernukho, Andrey
1998-10-01
- The paper presents the results of modeling of the optical pumping experiments in CO/N2/O2/Ar mixtures. In these experiments, the low vibrational levels of carbon monoxide (vinfrared and ultraviolet radiation from the excited electronic states is measured by a high-resolution step-scan Fourier transform spectrometer. The kinetic model incorporates coupled master equation for the CO, N2, and O2 vibrational level populations, and Boltzmann equation for the electrons. The comparison of the experimental and synthetic time-resolved spectra allowed inference of the V-V exchange rates for CO-CO up to v=40, cross-sections for the energy transfer between the highly excited CO molecules and electrons, and V-V transfer rates for CO-N2 and CO-O2.
Active Control of Parametric Vibrations in Coupled Rotor-Blade Systems
DEFF Research Database (Denmark)
Christensen, Rene Hardam; Santos, Ilmar
2003-01-01
In rotor-blade systems basis as well as parametric vibration modes will appear due to the vibration coupling among flexible rotating blades and hub rigid body motion. Parametric vibration will typically occur when the hub operates at a constant angular velocity. Operating at constant velocity...
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The torsional oscillation characteristics on the bending and torsion coupled vibration of rotary shaft system were investigated using the elasto-dynamic theory and other mathematic methods, such as difference approach, Fourier transform, and wavelet transform. It is concluded that mass eccentricity and other exciting modalities affect the bending and torsion coupled vibration of rotary shafts. Torsional vibration caused by bending vibration features linearity along with the change of amplitude of bending vibration. Meanwhile, energy spectrum concentrates on high frequency area with the wavelet analysis.
DEFF Research Database (Denmark)
Faber, Rasmus; Sauer, Stephan P. A.
2015-01-01
are in the order of 5 Hz for the one-bond carbon-hydrogen couplings and about 1 Hz or smaller for the other couplings apart from the one-bond carbon-carbon coupling (11 Hz) and the twobond carbon-hydrogen coupling (4 Hz) in ethyne. However, not for all couplings lead the inclusion of zero-point vibrational...
An Intermolecular Vibration Model for Lattice Ice
Directory of Open Access Journals (Sweden)
Quinn M. Brewster
2010-06-01
Full Text Available Lattice ice with tetrahedral arrangement is studied using a modified Einstein’s model that incorporates the hindered translational and rotational vibration bands into a harmonic oscillation system. The fundamental frequencies for hindered translational and rotational vibrations are assigned based on the intermolecular vibration bands as well as thermodynamic properties from existing experimental data. Analytical forms for thermodynamic properties are available for the modified model, with three hindered translational bands at (65, 229, 229 cm-1 and three effective hindered rotational bands at 560 cm-1. The derived results are good for temperatures higher than 30 K. To improve the model below 30 K, Lorentzian broadening correction is added. This simple model helps unveil the physical picture of ice lattice vibration behavior.
Modeling of the vibrating beam accelerometer nonlinearities
Romanowski, P. A.; Knop, R. C.
Successful modeling and processing of the output of a quartz Vibrating Beam Accelerometer (VBA), whose errors are inherently nonlinear with respect to input acceleration, are reported. The VBA output, with two signals that are frequencies of vibrating quartz beams, has inherent higher-order terms. In order to avoid vibration rectification errors, the signal output must be sampled at a rapid rate and the output must be reduced using a nonlinear model. The present model, with acceleration as a function of frequency, is derived by a least-squares process where the covariance matrix is obtained from simulated data. The system performance is found to be acceptable to strategic levels, and it is shown that a vibration rectification error of 400 micrograms/sq g can be reduced to 4 micrograms/sq g by using the processor electronics and a nonlinear model.
Institute of Scientific and Technical Information of China (English)
程廷海; 高焓; 包钢
2011-01-01
A novel ultrasonic vibration approach is introduced into a chloroprene rubber/aluminum friction couple for improving the static friction properties betwesn rubber and metal.Compared to the test results without vibrations,the static friction force of a chloroprene rubber/aluminum couple decreases observably,leading to the ultimate displacement of rubber.The values of the static friction force and ultimate displacement can be ultimately reduced to 23.1％ and 50％ of those without ultrasonic vibrations,respectively.%A novel ultrasonic vibration approach is introduced into a chioroprene rubber/aluminum friction couple for improving the static friction properties between rubber and metal. Compared to the test results without vibrations, the static friction force of a chioroprene rubber/aluminum couple decreases observably, leading to the ultimate displacement of rubber. The values of the static friction force and ultimate displacement can be ultimately reduced to 23.1% and 50% of those without ultrasonic vibrations, respectively.
Experimental validation of a numerical model for subway induced vibrations
Gupta, S.; Degrande, G.; Lombaert, G.
2009-04-01
This paper presents the experimental validation of a coupled periodic finite element-boundary element model for the prediction of subway induced vibrations. The model fully accounts for the dynamic interaction between the train, the track, the tunnel and the soil. The periodicity or invariance of the tunnel and the soil in the longitudinal direction is exploited using the Floquet transformation, which allows for an efficient formulation in the frequency-wavenumber domain. A general analytical formulation is used to compute the response of three-dimensional invariant or periodic media that are excited by moving loads. The numerical model is validated by means of several experiments that have been performed at a site in Regent's Park on the Bakerloo line of London Underground. Vibration measurements have been performed on the axle boxes of the train, on the rail, the tunnel invert and the tunnel wall, and in the free field, both at the surface and at a depth of 15 m. Prior to these vibration measurements, the dynamic soil characteristics and the track characteristics have been determined. The Bakerloo line tunnel of London Underground has been modelled using the coupled periodic finite element-boundary element approach and free field vibrations due to the passage of a train at different speeds have been predicted and compared to the measurements. The correspondence between the predicted and measured response in the tunnel is reasonably good, although some differences are observed in the free field. The discrepancies are explained on the basis of various uncertainties involved in the problem. The variation in the response with train speed is similar for the measurements as well as the predictions. This study demonstrates the applicability of the coupled periodic finite element-boundary element model to make realistic predictions of the vibrations from underground railways.
Directory of Open Access Journals (Sweden)
Qiang Zhang
2015-01-01
Full Text Available An analytical model on electromechanical coupling coefficient and the length optimization of a bending piezoelectric ultrasonic transducer are proposed. The piezoelectric transducer consists of 8 PZT elements sandwiched between four thin electrodes, and the PZT elements are clamped by a screwed connection between fore beam and back beam. Firstly, bending vibration model of the piezoelectric transducer is built based on the Timoshenko beam theory. Secondly, the analytical model of effective electromechanical coupling coefficient is built based on the bending vibration model. Energy method and electromechanical equivalent circuit method are involved in the modelling process. To validate the analytical model, sandwich type piezoelectric transducer example in second order bending vibration mode is analysed. Effective electromechanical coupling coefficient of the transducer is optimized with simplex reflection technique, and the optimized ratio of length of the transducers is obtained. Finally, experimental prototypes of the sandwich type piezoelectric transducers are fabricated. Bending vibration mode and impedance of the experimental prototypes are tested, and electromechanical coupling coefficient is obtained according to the testing results. Results show that the analytical model is in good agreement with the experimental model.
Energy Technology Data Exchange (ETDEWEB)
Yamasaki, Hisatsugu [Department of Applied Physics, Osaka City University, Osaka 558-8585 (Japan); Natsume, Yuhei [Graduate School of Science and Technology, Chiba University, Chiba 263-8522 (Japan); Terai, Akira [Department of Applied Physics, Osaka City University, Osaka 558-8585 (Japan); Nakamura, Katsuhiro [Department of Applied Physics, Osaka City University, Osaka 558-8585 (Japan)
2004-09-01
We investigate the frustrated quantum three-spin model (S{sub 1},S{sub 2},S{sub 3}) of spin = 1/2 on a triangle, in which spins are coupled with lattice-vibrational modes through the antiferromagnetic exchange interaction depending on distances between spin sites. The present model corresponds to the dynamic Jahn-Teller system E{sub g} - e{sub g} proposed by Longuet-Higgins et al (1958 Proc. R. Soc. A 244 1). This correspondence is revealed by using the transformation to Nakamura-Bishop's bases used in Phys. Rev. Lett. 54 861 (1985). Furthermore, we elucidate the relationship between a chiral order parameter {chi}-circumflex = S{sub 1}{center_dot}(S{sub 2}xS{sub 3}) in the spin system and the electronic orbital angular momentum l-circumflex{sub z} in E{sub g} - e{sub g} vibronic model: the regular oscillatory behaviour of the expectation value <{chi}-circumflex> with increasing energy can be found as in the case of
DEFF Research Database (Denmark)
Kuhlman, Thomas Scheby; Sauer, Stephan P.A.; Sølling, Theis I.
2012-01-01
In this paper, we discern two basic mechanisms of internal conversion processes; one direct, where immediate activation of coupling modes leads to fast population transfer and one indirect, where internal vibrational energy redistribution leads to equidistribution of energy, i.e., ergodicity......, and slower population transfer follows. Using model vibronic coupling Hamiltonians parameterized on the basis of coupled-cluster calculations, we investigate the nature of the Rydberg to valence excited-state internal conversion in two cycloketones, cyclobutanone and cyclopentanone. The two basic mechanisms...... can amply explain the significantly different time scales for this process in the two molecules, a difference which has also been reported in recent experimental findings [T. S. Kuhlman, T. I. Sølling, and K. B. Møller, ChemPhysChem. 13, 820 (2012)]...
Godtliebsen, Ian H; Christiansen, Ove
2015-10-07
It is demonstrated how vibrational IR and Raman spectra can be calculated from damped response functions using anharmonic vibrational wave function calculations, without determining the potentially very many eigenstates of the system. We present an implementation for vibrational configuration interaction and vibrational coupled cluster, and describe how the complex equations can be solved using iterative techniques employing only real trial vectors and real matrix-vector transformations. Using this algorithm, arbitrary frequency intervals can be scanned independent of the number of excited states. Sample calculations are presented for the IR-spectrum of water, Raman spectra of pyridine and a pyridine-silver complex, as well as for the infra-red spectrum of oxazole, and vibrational corrections to the polarizability of formaldehyde.
Methodology for Analysing Controllability and Observability of Bladed Disc Coupled Vibrations
DEFF Research Database (Denmark)
Christensen, Rene Hardam; Santos, Ilmar
2004-01-01
Many bladed rotating machines such as helicopters, turbines and compressors are susceptible to blade faults due to vibration problems. Typically, blade vibrations in this kind of machines are suppressed by using passive mechanical components. However, when passive control techniques...... are not efficient enough to suppress vibration problems, active control techniques might become the only feasible way of avoiding vibration problems. Implementing effectively active vibration control into any machine implies that the controllability and observability have to be analysed in order to determine where...... to place sensors and actuators so that all vibration levels can be monitored and controlled. Due to the special dynamic characteristics of rotating coupled bladed discs, where disc lateral motion is coupled to blade flexible motion, such analyses become quite complicated. The dynamics is described...
Particle-vibration coupling: Recent advances in microscopic calculations with the Skyrme Hamiltonian
Energy Technology Data Exchange (ETDEWEB)
Colò, G., E-mail: gianluca.colo@mi.infn.it [Università degli Studi di Milano, Dipartimento di Fisica (Italy); Baldo, M. [Sez. di Catania, Istituto Nazionale di Fisica Nucleare (INFN) (Italy); Bortignon, P. F.; Rizzo, D.; Bocchi, G. [Università degli Studi di Milano, Dipartimento di Fisica (Italy)
2016-11-15
In this contribution, we report some recent progress in our understanding of particle-vibration coupling (PVC) in nuclei. In particular, we first review the formal development that has allowed some of us to deduce the PVC equations within the Green’s functionmethod. Applications are then discussed, both in the case of single-particle states and giant resonances in magic nuclei. We also present a new model that extends the PVC ansatz and is meant to account for the complete low-lying spectra of odd nuclei.
Vibration modeling and supression in tennis racquets.
Energy Technology Data Exchange (ETDEWEB)
Farrar, C. R. (Charles R.); Buechler, M. A. (Miles A.); Espino, Luis; Thompson, G. A. (Gordon A.)
2003-01-01
The size of the 'sweet spot' is one measure of tennis racquet performance. In terms of vibration, the sweet spot is determined by the placement of nodal lines across the racquet head. In this studx the vibrational characteristics of a tennis racquet are explorod to discover the size and location of the sweet spot. A numerical model of the racquet is developed using finite element analysis and the model is verified using the results from an experimental modal analysis. The affects of string tension on the racquet's sweet spot and mode shapes are then quantified. An investigation is also carried out to determine how add-on vibrational datnpers affect the sweet spot.
Institute of Scientific and Technical Information of China (English)
李小珍; 洪沁烨; 耿杰; 刘德军; 单春胜
2015-01-01
研究目的：在我国新建中低速磁浮运营线的背景下，因中低速磁浮轨道梁较为轻巧，为保证磁浮列车行车安全及舒适性，需对其进行磁浮列车－轨道梁耦合振动分析验证。本文以株洲某厂磁浮试验线20 m 简支梁为工程背景，建立车辆为12个自由度的二系悬挂质量－弹簧－阻尼模型，并考虑轨道不平顺对车桥振动的影响，建立磁浮列车－轨道梁竖向耦合振动分析模型，且编制仿真分析软件 VTBIM，通过仿真值与现场试验实测值的对比，验证所建模型的合理性。研究结论：（1）现场试验测试轨道梁基频、振型及轨道梁跨中动挠度／加速度，轨道梁基频及振型测试结果比仿真值略小；（2）磁浮车辆通过简支梁时，梁跨中竖向挠度／加速度的实测值均略小于仿真值，仿真值随车速的变化规律与实测值规律一致，挠度时程曲线仿真值与实测波形基本一致；（3）研究结果表明本文所建立的中低速磁浮列车－轨道梁竖向耦合振动模型合理，编制的仿真分析软件的计算结果可信；（4）该研究结果可用于中低速磁浮轨道梁设计参考。%Research purposes:In our country under the background of new construction of medium and low speed maglev operation,because the low speed maglev rail beam is relatively light,in order to ensure the safety and comfort,the maglev train -track beam coupling vibration should be analyzed and verified.Based on the engineering background of 20 m simply supported beam of maglev test line in a factory of Zhuzhou,this paper establishes the secondary suspension quality -spring - damper model that vehicle is 12 degrees of freedom,builds maglev trains and track beam vertical coupling vibration analysis model considering the impact of track irregularity,and designs the simulation analysis software VTBIM.Through comparing the simulation value with the measured values
Institute of Scientific and Technical Information of China (English)
王光庆; 金文平; 展永政; 陆跃明
2013-01-01
为提高传统压电振动能量采集器集总参数模型的性能预测精度，考虑悬臂梁的振型信息与轴向应变分布情况，提出了一种改进的力电耦合模型，该模型引入无因次幅值修正因子，通过曲线拟合方法确定了修正因子与振型函数和振动幅值之间的关系表达式；利用Rayleigh-Ritz模态分析法确定了力电耦合模型中的集总等效参数(如质量、刚度等)，并根据弹性动力学原理建立了能量采集器的运动控制方程，得到了稳态时能量采集器的力、电输出响应表达式；最后，利用改进的模型对能量采集器的负载电阻和输出功率进行了优化，得到了负载短路和负载开路时能量采集器的最优输出特性。仿真结果与实例对比验证了提出模型的正确性，表明改进的力电耦合模型具有较高的预测精度。%In order to overcome the disadvantages of the traditional lumped parameter model of piezoelectric vibration energy harvester ( PVEH ) , this article presents an improved force-electric coupling model ( FECM ) to predict the output performances of the PVEH by considering the dynamic mode shape and the strain distribution of the bender. A dimensionless correction factor is adopted in the FECM to formulate the relationship expression between the mode shape and the vibration amplitude of the PVEH with curve fitting method. The equivalent parameters(such as mass,stiffness) of FECM are obtained by using the Rayleigh-Ritz modal analysis method,the governing motion equations and the exact analytical solution of cantilevered piezoelectric vibration energy harvester excited by persistent base motions are developed according to the elastic dynamics principle. The steady state electrical and mechanical output response expressions are derived for arbitrary frequency excitations. Finally,the op-timizations of the load resistance and the output power of the PVEH are carried out and the optimized output
Diomede, P.; Bruneau, B.; Longo, S.; Johnson, E.; Booth, J.-P.
2017-07-01
A comprehensive hybrid model of a hydrogen capacitively coupled plasma, including a detailed description of the molecular vibrational kinetics, has been applied to the study of the effect of tailored voltage waveforms (TVWs) on the production kinetics and transport of negative ions in these discharges. Two kinds of TVWs are considered, valleys-to-peaks and saw-tooth, with amplitude and slope asymmetry respectively. By tailoring the voltage waveform only, it is possible to exert substantial control over the peak density and position of negative ions inside the discharge volume. This control is particularly effective for saw-tooth waveforms. Insight into the mechanisms allowing this control is provided by an analysis of the model results. This reveals the roles of the vibrational distribution function and of the electron energy distribution and their correlations, as well as changes in the negative ion transport in the electric field when using different TVWs. Considering the chemical reactivity of H- ions, the possibility of a purely electrical control of the negative ion cloud in a reactor operating with a feedstock gas diluted by hydrogen may find interesting applications. This is the first study of vibrational kinetics in the context of TVWs in molecular gases.
Ro-vibrational averaging of the isotropic hyperfine coupling constant for the methyl radical
Energy Technology Data Exchange (ETDEWEB)
Adam, Ahmad Y.; Jensen, Per, E-mail: jensen@uni-wuppertal.de [Fakultät Mathematik und Naturwissenschaften, Physikalische und Theoretische Chemie, Bergische Universität Wuppertal, D-42097 Wuppertal (Germany); Yachmenev, Andrey; Yurchenko, Sergei N. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)
2015-12-28
We present the first variational calculation of the isotropic hyperfine coupling constant of the carbon-13 atom in the CH{sub 3} radical for temperatures T = 0, 96, and 300 K. It is based on a newly calculated high level ab initio potential energy surface and hyperfine coupling constant surface of CH{sub 3} in the ground electronic state. The ro-vibrational energy levels, expectation values for the coupling constant, and its temperature dependence were calculated variationally by using the methods implemented in the computer program TROVE. Vibrational energies and vibrational and temperature effects for coupling constant are found to be in very good agreement with the available experimental data. We found, in agreement with previous studies, that the vibrational effects constitute about 44% of the constant’s equilibrium value, originating mainly from the large amplitude out-of-plane bending motion and that the temperature effects play a minor role.
Sattar, M.; Wei, C.; Jalali, A.; Sattar, R.
2017-07-01
To address the impact of solar array (SA) anomalies and vibrations on performance of precision space-based operations, it is important to complete its accurate jitter analysis. This work provides mathematical modelling scheme to approximate kinematics and coupled micro disturbance dynamics of rigid load supported and operated by solar array drive assembly (SADA). SADA employed in analysis provides a step wave excitation torque to activate the system. Analytical investigations into kinematics is accomplished by using generalized linear and Euler angle coordinates, applying multi-body dynamics concepts and transformations principles. Theoretical model is extended, to develop equations of motion (EoM), through energy method (Lagrange equation). The main emphasis is to research coupled frequency response by determining energies dissipated and observing dynamic behaviour of internal vibratory systems of SADA. The disturbance model captures discrete active harmonics of SADA, natural modes and vibration amplifications caused by interactions between active harmonics and structural modes of mechanical assembly. The proposed methodology can help to predict true micro disturbance nature of SADA operating rigid load. Moreover, performance outputs may be compared against actual mission requirements to assess precise spacecraft controller design to meet next space generation stringent accuracy goals.
DEFF Research Database (Denmark)
Thomsen, Bo; Hansen, Mikkel Bo; Seidler, Peter
2012-01-01
We report the theory and implementation of vibrational coupled cluster (VCC) damped response functions. From the imaginary part of the damped VCC response function the absorption as function of frequency can be obtained, requiring formally the solution of the now complex VCC response equations...... with results from the recently reported [P. Seidler, M. B. Hansen, W. Györffy, D. Toffoli, and O. Christiansen, J. Chem. Phys. 132, 164105 (2010)] vibrational configuration interaction damped response function calculated using a symmetric Lanczos algorithm. Calculations of IR spectra of oxazole, cyclopropene...
Modified relaxation dynamics and coherent energy exchange in coupled vibration-cavity polaritons
Dunkelberger, A. D.; Spann, B. T.; Fears, K. P.; Simpkins, B. S.; Owrutsky, J. C.
2016-11-01
Coupling vibrational transitions to resonant optical modes creates vibrational polaritons shifted from the uncoupled molecular resonances and provides a convenient way to modify the energetics of molecular vibrations. This approach is a viable method to explore controlling chemical reactivity. In this work, we report pump-probe infrared spectroscopy of the cavity-coupled C-O stretching band of W(CO)6 and the direct measurement of the lifetime of a vibration-cavity polariton. The upper polariton relaxes 10 times more quickly than the uncoupled vibrational mode. Tuning the polariton energy changes the polariton transient spectra and relaxation times. We also observe quantum beats, so-called vacuum Rabi oscillations, between the upper and lower vibration-cavity polaritons. In addition to establishing that coupling to an optical cavity modifies the energy-transfer dynamics of the coupled molecules, this work points out the possibility of systematic and predictive modification of the excited-state kinetics of vibration-cavity polariton systems.
Monitoring Vibration of A Model of Rotating Machine
Directory of Open Access Journals (Sweden)
Arko Djajadi
2012-03-01
Full Text Available Mechanical movement or motion of a rotating machine normally causes additional vibration. A vibration sensing device must be added to constantly monitor vibration level of the system having a rotating machine, since the vibration frequency and amplitude cannot be measured quantitatively by only sight or touch. If the vibration signals from the machine have a lot of noise, there are possibilities that the rotating machine has defects that can lead to failure. In this experimental research project, a vibration structure is constructed in a scaled model to simulate vibration and to monitor system performance in term of vibration level in case of rotation with balanced and unbalanced condition. In this scaled model, the output signal of the vibration sensor is processed in a microcontroller and then transferred to a computer via a serial communication medium, and plotted on the screen with data plotter software developed using C language. The signal waveform of the vibration is displayed to allow further analysis of the vibration. Vibration level monitor can be set in the microcontroller to allow shutdown of the rotating machine in case of excessive vibration to protect the rotating machine from further damage. Experiment results show the agreement with theory that unbalance condition on a rotating machine can lead to larger vibration amplitude compared to balance condition. Adding and reducing the mass for balancing can be performed to obtain lower vibration level.
COUPLED CHEMOTAXIS FLUID MODEL
LORZ, ALEXANDER
2010-06-01
We consider a model system for the collective behavior of oxygen-driven swimming bacteria in an aquatic fluid. In certain parameter regimes, such suspensions of bacteria feature large-scale convection patterns as a result of the hydrodynamic interaction between bacteria. The presented model consist of a parabolicparabolic chemotaxis system for the oxygen concentration and the bacteria density coupled to an incompressible Stokes equation for the fluid driven by a gravitational force of the heavier bacteria. We show local existence of weak solutions in a bounded domain in d, d = 2, 3 with no-flux boundary condition and in 2 in the case of inhomogeneous Dirichlet conditions for the oxygen. © 2010 World Scientific Publishing Company.
Coupling of Excitons and Discrete Acoustic Phonons in Vibrationally Isolated Quantum Emitters.
Werschler, Florian; Hinz, Christopher; Froning, Florian; Gumbsheimer, Pascal; Haase, Johannes; Negele, Carla; de Roo, Tjaard; Mecking, Stefan; Leitenstorfer, Alfred; Seletskiy, Denis V
2016-09-14
The photoluminescence emission by mesoscopic condensed matter is ultimately dictated by the fine-structure splitting of the fundamental exciton into optically allowed and dipole-forbidden states. In epitaxially grown semiconductor quantum dots, nonradiative equilibration between the fine-structure levels is mediated by bulk acoustic phonons, resulting in asymmetric spectral broadening of the excitonic luminescence. In isolated colloidal quantum dots, spatial confinement of the vibrational motion is expected to give rise to an interplay between the quantized electronic and phononic degrees of freedom. In most cases, however, zero-dimensional colloidal nanocrystals are strongly coupled to the substrate such that the charge relaxation processes are still effectively governed by the bulk properties. Here we show that encapsulation of single colloidal CdSe/CdS nanocrystals into individual organic polymer shells allows for systematic vibrational decoupling of the semiconductor nanospheres from the surroundings. In contrast to epitaxially grown quantum dots, simultaneous quantization of both electronic and vibrational degrees of freedom results in a series of strong and narrow acoustic phonon sidebands observed in the photoluminescence. Furthermore, an individual analysis of more than 200 compound particles reveals that enhancement or suppression of the radiative properties of the fundamental exciton is controlled by the interaction between fine-structure states via the discrete vibrational modes. For the first time, pronounced resonances in the scattering rate between the fine-structure states are directly observed, in good agreement with a quantum mechanical model. The unambiguous assignment of mediating acoustic modes to the observed scattering resonances complements the experimental findings. Thus, our results form an attractive basis for future studies on subterahertz quantum opto-mechanics and efficient laser cooling at the nanoscale.
Nonequilibrium electron-vibration coupling and conductance fluctuations in a C60 junction
Ulstrup, Søren; Frederiksen, Thomas; Brandbyge, Mads
2012-12-01
We investigate chemical bond formation and conductance in a molecular C60 junction under finite bias voltage using first-principles calculations based on density functional theory and nonequilibrium Green's functions (DFT-NEGF). At the point of contact formation we identify a remarkably strong coupling between the C60 motion and the molecular electronic structure. This is only seen for positive sample bias, although the conductance itself is not strongly polarity dependent. The nonequilibrium effect is traced back to a sudden shift in the position of the voltage drop with a small C60 displacement. Combined with a vibrational heating mechanism we construct a model from our results that explain the polarity-dependent two-level conductance fluctuations observed in recent scanning tunneling microscopy (STM) experiments [N. Néel , Nano Lett.NALEFD1530-698410.1021/nl201327c 11, 3593 (2011)]. These findings highlight the significance of nonequilibrium effects in chemical bond formation/breaking and in electron-vibration coupling in molecular electronics.
Vibrational resonance, allostery, and activation in rhodopsin-like G protein-coupled receptors
Woods, Kristina N.; Pfeffer, Jürgen; Dutta, Arpana; Klein-Seetharaman, Judith
2016-11-01
G protein-coupled receptors are a large family of membrane proteins activated by a variety of structurally diverse ligands making them highly adaptable signaling molecules. Despite recent advances in the structural biology of this protein family, the mechanism by which ligands induce allosteric changes in protein structure and dynamics for its signaling function remains a mystery. Here, we propose the use of terahertz spectroscopy combined with molecular dynamics simulation and protein evolutionary network modeling to address the mechanism of activation by directly probing the concerted fluctuations of retinal ligand and transmembrane helices in rhodopsin. This approach allows us to examine the role of conformational heterogeneity in the selection and stabilization of specific signaling pathways in the photo-activation of the receptor. We demonstrate that ligand-induced shifts in the conformational equilibrium prompt vibrational resonances in the protein structure that link the dynamics of conserved interactions with fluctuations of the active-state ligand. The connection of vibrational modes creates an allosteric association of coupled fluctuations that forms a coherent signaling pathway from the receptor ligand-binding pocket to the G-protein activation region. Our evolutionary analysis of rhodopsin-like GPCRs suggest that specific allosteric sites play a pivotal role in activating structural fluctuations that allosterically modulate functional signals.
Model reduction and analysis of a vibrating beam microgyroscope
Ghommem, Mehdi
2012-05-08
The present work is concerned with the nonlinear dynamic analysis of a vibrating beam microgyroscope composed of a rotating cantilever beam with a tip mass at its end. The rigid mass is coupled to two orthogonal electrodes in the drive and sense directions, which are attached to the rotating base. The microbeam is driven by an AC voltage in the drive direction, which induces vibrations in the orthogonal sense direction due to rotation about the microbeam axis. The electrode placed in the sense direction is used to measure the induced motions and extract the underlying angular speed. A reduced-order model of the gyroscope is developed using the method of multiple scales and used to examine its dynamic behavior. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.
You, Bin Di; Wen, Jian Min; Zhao, Yang
2014-03-01
In this paper, a nonlinear dynamic modeling method for a rigid-flexible coupling satellite antenna system composed of laminated shell reflector is proposed undergoing a large overall motion. For the study of the characteristics of the reflector using laminated shell structure, the displacement field description of a point in a 3-noded shell element is acquired in conjunction with the length stretch, lateral bending and torsional deformation. Hence, a nonlinear dynamic model of the satellite antenna system is deduced based on Lagrange's equations. The complete expressions of nonlinear terms of elastic deformation and coupling terms between rigid motion and large deflection are considered in the dynamic equations, and the dynamic behavior of the rigid-flexible coupling system is analyzed using linear model and nonlinear model, respectively. In order to eliminate the system vibration, the PD with vibration force feedback control strategy is used to achieve its desired angles and velocity in a much shorter duration, and can further accomplish reduction of residual vibration. Then, the asymptotic stability of the system is proved based on the Lyapunov method. Through numerical computation, the results show that the linear model cannot capture the motion-induced coupling terms and geometric nonlinearity variations. However, the nonlinear model is suitable for dealing with large deformation rigid-flexible problem undergoing large overall motions. Hence, the satellite antenna pointing accuracy would be predicted based on the nonlinear model. Furthermore, the results also show that the proposed control strategy can suppress system vibration quickly. The above conclusions would have important academic significance and engineering value.
Energy Technology Data Exchange (ETDEWEB)
Faber, Rasmus; Sauer, Stephan P. A. [Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø (Denmark)
2015-12-31
We present zero-point vibrational corrections to the indirect nuclear spin-spin coupling constants in ethyne, ethene, cyclopropene and allene. The calculations have been carried out both at the level of the second order polarization propagator approximation (SOPPA) employing a new implementation in the DALTON program, at the density functional theory level with the B3LYP functional employing also the Dalton program and at the level of coupled cluster singles and doubles (CCSD) theory employing the implementation in the CFOUR program. Specialized coupling constant basis sets, aug-cc-pVTZ-J, have been employed in the calculations. We find that on average the SOPPA results for both the equilibrium geometry values and the zero-point vibrational corrections are in better agreement with the CCSD results than the corresponding B3LYP results. Furthermore we observed that the vibrational corrections are in the order of 5 Hz for the one-bond carbon-hydrogen couplings and about 1 Hz or smaller for the other couplings apart from the one-bond carbon-carbon coupling (11 Hz) and the two-bond carbon-hydrogen coupling (4 Hz) in ethyne. However, not for all couplings lead the inclusion of zero-point vibrational corrections to better agreement with experiment.
Coupled flexural-longitudinal vibration of delaminated composite beams with local stability analysis
Szekrényes, András
2014-09-01
A novel analytical model is developed to solve the problem of free vibration of delaminated composite beams. The beam with a single delamination was modelled by six equivalent single layers by establishing the kinematic continuity in the undelaminated portion of the system. In the delaminated region the layers were captured by the traditional theories. First, Timoshenko beam theory is applied to solve the problem, then by reducing the model, the corresponding Euler-Bernoulli solution is presented. Both the free and constrained models were considered. The most important aspect of the present analysis is that the beams of the delaminated region are subjected to normal forces, as well. That is the essential reason for leading to a coupled flexural-longitudinal vibration problem. It is also concluded that delamination buckling can take place if the normal force is compressive in one of the half-periods of the vibration and reaches a critical value. The problem was also investigated experimentally by modal hammer and sweep excitation tests on beams made of E-glass/polyester in order to measure the natural frequencies and mode shapes. The comparison of the analytical and experimental results indicates the importance of the independent rotations provided by Timoshenko beams over the simple beam theory. The delamination buckling of the beams was captured based on the static stability analysis in the first step. Further results show that the problem is more complex than it was thought before, e.g., some nonlinearity, time-dependent stiffness as well as parametric excitation aspects were discovered during the present analysis.
Van Dyke, Michael B.
2013-01-01
Present preliminary work using lumped parameter models to approximate dynamic response of electronic units to random vibration; Derive a general N-DOF model for application to electronic units; Illustrate parametric influence of model parameters; Implication of coupled dynamics for unit/board design; Demonstrate use of model to infer printed wiring board (PWB) dynamics from external chassis test measurement.
Energy transfer efficiency in the chromophore network strongly coupled to a vibrational mode.
Mourokh, Lev G; Nori, Franco
2015-11-01
Using methods from condensed matter and statistical physics, we examine the transport of excitons through the photosynthetic complex from a receiving antenna to a reaction center. Writing the equations of motion for the exciton creation-annihilation operators, we are able to describe the exciton dynamics, even in the regime when the reorganization energy is of the order of the intrasystem couplings. We determine the exciton transfer efficiency in the presence of a quenching field and protein environment. While the majority of the protein vibrational modes are treated as a heat bath, we address the situation when specific modes are strongly coupled to excitons and examine the effects of these modes on the energy transfer efficiency in the steady-state regime. Using the structural parameters of the Fenna-Matthews-Olson complex, we find that, for vibrational frequencies below 16 meV, the exciton transfer is drastically suppressed. We attribute this effect to the formation of a "mixed exciton-vibrational mode" where the exciton is transferred back and forth between the two pigments with the absorption or emission of vibrational quanta, instead of proceeding to the reaction center. The same effect suppresses the quantum beating at the vibrational frequency of 25 meV. We also show that the efficiency of the energy transfer can be enhanced when the vibrational mode strongly couples to the third pigment only, instead of coupling to the entire system.
Takács, Gergely
2012-01-01
Real-time model predictive controller (MPC) implementation in active vibration control (AVC) is often rendered difficult by fast sampling speeds and extensive actuator-deformation asymmetry. If the control of lightly damped mechanical structures is assumed, the region of attraction containing the set of allowable initial conditions requires a large prediction horizon, making the already computationally demanding on-line process even more complex. Model Predictive Vibration Control provides insight into the predictive control of lightly damped vibrating structures by exploring computationally efficient algorithms which are capable of low frequency vibration control with guaranteed stability and constraint feasibility. In addition to a theoretical primer on active vibration damping and model predictive control, Model Predictive Vibration Control provides a guide through the necessary steps in understanding the founding ideas of predictive control applied in AVC such as: · the implementation of ...
On the nonlinear models of the vibrating string
Watzky, Alexandre
2005-09-01
Vibrations of strings (threads, wires, cables...) are of great interest because of their various domains of application. In musical acoustics, phenomena which could have been neglected elsewhere take a particular importance since perception, which is very sensitive to nonlinear effects, is involved. Some phenomena can also be emphasized when a string is coupled to a sound-radiating structure. Reliable physical models are thus necessary to account for these phenomena, and to understand the true behavior of a vibrating string. Despite the fact that the first nonlinear models were published more than one century ago, and that accurate equations of motion can be naturally achieved within a finite displacement continuum mechanics framework, general models never received the attention they deserved, most authors focusing on particular phenomena and often settling on approximate models. This can be explained by the awkward multiplicity of the involved phenomena. The aim of this presentation is to discuss the consequences of some common assumptions and the true nature of some observed couplings. Particular attention will be paid to the preponderance of the spatial shape of the modes, which are usually underestimated with respect to their temporal form.
Uniformly valid solutions of the coupling turning-point problem in revolution shell vibration
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The turning-point problem in free vibration of revolution shells has the coupling property between the bending and membrane solutions. The uniformly valid solutions for this coupling turning-point problem are obtained based on three categories of generalized functions. Furthermore, they are verified to be uniformly valid in the low, turning-point and high frequency ranges. The obtained solutions exhibit a symmetric coupling structure between the bending and membrane solutions.
Acoustic vibration modes and electron-lattice coupling in self-assembled silver nanocolumns.
Burgin, J; Langot, P; Arbouet, A; Margueritat, J; Gonzalo, J; Afonso, C N; Vallée, F; Mlayah, A; Rossell, M D; Van Tendeloo, G
2008-05-01
Using ultrafast spectroscopy, we investigated electron-lattice coupling and acoustic vibrations in self-assembled silver nanocolumns embedded in an amorphous Al2O3 matrix. The measured electron-lattice energy exchange time is smaller in the nanocolumns than in bulk silver, with a value very close to that of isolated nanospheres with comparable surface to volume ratio. Two vibration modes were detected and ascribed to the breathing and extensional mode of the nanocolumns, in agreement with numerical simulations.
Directory of Open Access Journals (Sweden)
Xinwen Yang
2016-01-01
Full Text Available In order to reduce the ground-borne vibration caused by wheel/rail interaction in the ballastless track of high speed railways, viscoelastic asphalt concrete materials are filled between the track and the subgrade to attenuate wheel/rail force. A high speed train-track-subgrade vertical coupled dynamic model is developed in the frequency domain. In this model, coupling effects between the vehicle and the track and between the track and the subgrade are considered. The full vehicle is represented by some rigid body models of one body, two bogies, and four wheelsets connected to each other with springs and dampers. The track and subgrade system is considered as a multilayer beam model in which layers are connected to each other with springs and damping elements. The vertical receptance of the rail is discussed and the receptance contribution of the wheel/rail interaction is investigated. Combined with the pseudoexcitation method, a solution of the random dynamic response is presented. The random vibration responses and transfer characteristics of the ballastless track and subgrade system are obtained under track random irregularity when a high speed vehicle runs through. The influences of asphalt concrete layer’s stiffness and vehicle speed on track and subgrade coupling vibration are analyzed.
Lossouarn, B.; Deü, J.-F.; Aucejo, M.; Cunefare, K. A.
2016-11-01
Multimodal damping can be achieved by coupling a mechanical structure to an electrical network exhibiting similar modal properties. Focusing on a plate, a new topology for such an electrical analogue is found from a finite difference approximation of the Kirchhoff-Love theory and the use of the direct electromechanical analogy. Discrete models based on element dynamic stiffness matrices are proposed to simulate square plate unit cells coupled to their electrical analogues through two-dimensional piezoelectric transducers. A setup made of a clamped plate covered with an array of piezoelectric patches is built in order to validate the control strategy and the numerical models. The analogous electrical network is implemented with passive components as inductors, transformers and the inherent capacitance of the piezoelectric patches. The effect of the piezoelectric coupling on the dynamics of the clamped plate is significant as it creates the equivalent of a multimodal tuned mass damping. An adequate tuning of the network then yields a broadband vibration reduction. In the end, the use of an analogous electrical network appears as an efficient solution for the multimodal control of a plate.
Random gust response statistics for coupled torsion-flapping rotor blade vibrations.
Gaonkar, G. H.; Hohenemser, K. H.; Yin, S. K.
1972-01-01
An analysis of coupled torsion-flapping rotor blade vibrations in response to atmospheric turbulence revealed that at high rotor advance ratios anticipated for future high speed pure or convertible rotorcraft both flapping and torsional vibrations can be severe. While appropriate feedback systems can alleviate flapping, they have little effect on torsion. Dynamic stability margins have also no substantial influence on dynamic torsion loads. The only effective means found to alleviate turbulence caused torsional vibrations and loads at high advance ratio was a substantial torsional stiffness margin with respect to local static torsional divergence of the retreating blade.
Continuum particle-vibration coupling method in coordinate-space representation for finite nuclei
Mizuyama, Kazuhito; Vigezzi, Enrico
2012-01-01
In this paper we present a new formalism to implement the nuclear particle-vibration coupling (PVC) model. The key issue is the proper treatment of the continuum, that is allowed by the coordinate space representation. Our formalism, based on the use of zero-range interactions like the Skyrme forces, is microscopic and fully self-consistent. We apply it to the case of neutron single-particle states in $^{40}$Ca, $^{208}$Pb and $^{24}$O. The first two cases are meant to illustrate the comparison with the usual (i.e., discrete) PVC model. However, we stress that the present approach allows to calculate properly the effect of PVC on resonant states. We compare our results with those from experiments in which the particle transfer in the continuum region has been attempted. The latter case, namely $^{24}$O, is chosen as an example of a weakly-bound system. Such a nucleus, being double-magic and not displaying collective low-lying vibrational excitations, is characterized by quite pure neutron single-particle stat...
Studying and Modeling Vibration Transducers and Accelerometers
Directory of Open Access Journals (Sweden)
Katalin Ágoston
2010-12-01
Full Text Available This paper presents types and operating mode of vibration sensors. Piezoelectric sensing elements are often used in accelerometers. It will be investigate the structure and transfer function of the seismic mass type sensing element. The article presents how the piezoelectric sensing element works and how can be modeled with an electronic circuit. The transfer functions of the electronic circuit models are studied in Matlab and the results are presented. It will be presented the influence of the seismic mass on the accelerometer’s working frequency domain.
Guo, Zhenwu; Zhang, Hongxia; Chen, Xinwei; Jia, Dagong; Liu, Tiegen
2011-07-10
The principle of the mode cross coupling in polarization-maintaining fiber based on white-light interferometry was analyzed. The method of measuring the polarization mode coupling with a spatial Michelson interferometer was presented. Analysis and emulation were carried out for the vibration disturbance signal caused by the mechanical scanning and the influence the vibration imposed on the judgment of coupling intensity. The interference signal envelope is extracted by a Hilbert transform and fitted by a Gaussian least-squares method under the different scanning speed. It is indicated that the detection accuracy varies with the vibration amplitude, which varies with scanning speed. The best scanning speed of the system should be from 0.7 mm/s to 0.9 mm/s to achieve the minimum detection error.
DYNAMIC MODELLING OF VIBRATIONS ASSISTED DRILLING
Directory of Open Access Journals (Sweden)
Mathieu LADONNE
2015-05-01
Full Text Available The number of multi-materials staking configurations for aeronautical structures is increasing, with the evolution of composite and metallic materials. For drilling the fastening holes, the processes of Vibration Assisted Drilling (VAD expand rapidly, as it permits to improve reliability of drilling operations on multilayer structures. Among these processes of VAD, the solution with forced vibrations added to conventional feed to create a discontinuous cutting is the more developed in industry. The back and forth movement allows to improve the evacuation of chips by breaking it. This technology introduces two new operating parameters, the frequency and the amplitude of the oscillation. To optimize the process, the choice of those parameters requires first to model precisely the operation cutting and dynamics. In this paper, a kinematic modelling of the process is firstly proposed. The limits of the model are analysed through comparison between simulations and measurements. The proposed model is used to develop a cutting force model that allows foreseeing the operating conditions which ensure good chips breaking and tool life improvement.
Banik, Subrata; Pal, Sourav; Prasad, M Durga
2010-10-12
An effective operator approach based on the coupled cluster method is described and applied to calculate vibrational expectation values and absolute transition matrix elements. Coupled cluster linear response theory (CCLRT) is used to calculate excited states. The convergence pattern of these properties with the rank of the excitation operator is studied. The method is applied to a water molecule. Arponen-type double similarity transformation in extended coupled cluster (ECCM) framework is also used to generate an effective operator, and the convergence pattern of these properties is compared to the normal coupled cluster (NCCM) approach. It is found that the coupled cluster method provides an accurate description of these quantities for low lying vibrational excited states. The ECCM provides a significant improvement for the calculation of the transition matrix elements.
Chen, X.; Rinkevicius, Z.; Ruud, K.; Ågren, H.
2013-02-01
By analyzing a set of organic π radicals, we demonstrate that zero-point vibrational corrections give significant contributions to carbon hyperfine coupling constants, in one case even inducing a sign reversal for the coupling constant. We discuss the implications of these findings for the computational analysis of electron paramagnetic spectra based on hyperfine coupling constants evaluated at the equilibrium geometry of radicals. In particular, we note that a dynamical description that involves the nuclear motion is in many cases necessary in order to achieve a semi-quantitatively predictive theory for carbon hyperfine coupling constants. In addition, we discuss the implications of the strong dependence of the carbon hyperfine coupling constants on the zero-point vibrational corrections for the selection of exchange-correlation functionals in density functional theory studies of these constants.
Adali, Sarp
2009-05-01
Variational principles are derived for multiwalled carbon nanotubes undergoing vibrations. Derivations are based on the continuum modeling with the Euler-Bernoulli beam representing the nanotubes and small scale effects taken into account via the nonlocal elastic theory. Hamilton's principle for multiwalled nanotubes is given and Rayleigh's quotient for the frequencies is derived for nanotubes undergoing free vibrations. Natural and geometric boundary conditions are derived which lead to a set of coupled boundary conditions due to nonlocal effects.
Lossouarn, B.; Aucejo, M.; Deü, J.-F.
2015-04-01
An elastic lattice of point masses can be a suitable representation of a continuous rod for the study of longitudinal wave propagation. By extrapolating the classical tuned mass damping strategy, a multimodal tuned mass damper is introduced from the coupling of two lattices having the same modal properties. The aim of the study is then to implement this multimodal control on a rod coupled to an electrical network. The electromechanical analogy applied to a lattice gives the required network, and the energy conversion is performed with piezoelectric patches. The coupled problem is modeled by a novel semi-continuous transfer matrix formulation, which is experimentally validated by a setup involving a rod equipped with 20 pairs of piezoelectric patches. The broadband efficiency of the multimodal control is also experimentally proved with vibration reductions up to 25 dB on the four first resonances of the rod. Finally, the practical interest of the network is pointed out, as it limits the required inductance. This is confirmed by the present purely passive setup that only involves standard low value inductors.
A modal approach to modeling spatially distributed vibration energy dissipation.
Energy Technology Data Exchange (ETDEWEB)
Segalman, Daniel Joseph
2010-08-01
The nonlinear behavior of mechanical joints is a confounding element in modeling the dynamic response of structures. Though there has been some progress in recent years in modeling individual joints, modeling the full structure with myriad frictional interfaces has remained an obstinate challenge. A strategy is suggested for structural dynamics modeling that can account for the combined effect of interface friction distributed spatially about the structure. This approach accommodates the following observations: (1) At small to modest amplitudes, the nonlinearity of jointed structures is manifest primarily in the energy dissipation - visible as vibration damping; (2) Correspondingly, measured vibration modes do not change significantly with amplitude; and (3) Significant coupling among the modes does not appear to result at modest amplitudes. The mathematical approach presented here postulates the preservation of linear modes and invests all the nonlinearity in the evolution of the modal coordinates. The constitutive form selected is one that works well in modeling spatially discrete joints. When compared against a mathematical truth model, the distributed dissipation approximation performs well.
Hydrological model coupling with ANNs
Kamp, R. G.; Savenije, H. H. G.
2006-12-01
Model coupling in general is necessary but complicated. Scientists develop and improve conceptual models to represent physical processes occurring in nature. The next step is to translate these concepts into a mathematical model and finally into a computer model. Problems may appear if the knowledge, encapsulated in a computer model and software program is needed for another purpose. In integrated water management this is often the case when connections between hydrological, hydraulic or ecological models are required. Coupling is difficult for many reasons, related to data formats, compatibility of scales, ability to modify source codes, etc. Hence, there is a need for an efficient and cost effective approach to model-coupling. One solution for model coupling is the use of Artificial Neural Networks (ANNs). The ANN can be used as a fast and effective model simulator which can connect different models. In this paper ANNs are used to couple four different models: a rainfall runoff model, a river channel routing model, an estuarine salt intrusion model, and an ecological model. The coupling as such has proven to be feasible and efficient. However the salt intrusion model appeared difficult to model accurately in an ANN. The ANN has difficulty to represent both short term (tidal) and long term (hydrological) processes.
Institute of Scientific and Technical Information of China (English)
Xue-Liang Zhang; Bang-Chun Wen; Chun-Yu Zhao
2012-01-01
In this paper,the synchronization problem of three homodromy coupled exciters in a non-resonant vibrating system of plane motion is studied.By introducing the average method of modified small parameters,we deduced dimensionless coupling equation of three exciters,which converted the problem of synchronization into that of the existence and stability of zero solutions for the average differential equations of the small parameters.Based on the dimensionless coupling torques and characteristics of the corresponding limited functions,the synchronization criterion for three exciters was derived as the absolute value of dimensionless residual torque difference between arbitrary two motors being less than the maximum of their dimensionless coupling torques.The stability criterion of its synchronous state lies in the double-condition that the inertia coupling matrix is positive definite and all its elements are positive as well.The synchronization determinants are the coefficients of synchronization ability,also called as the general dynamical symmetry coefficients.The double-equilibrium state of the vibrating system is manifested by numeric method,and the numeric and simulation results derived thereof indicate the indispensable and crucial role the structural parameters of the vibrating system play in the stability criterion of synchronous operation.Besides,by adjusting its structural parameters,the elliptical motion of the vibrating system successfully met the requirements in engineering applications.
Vibration Problems of Rotating Machinery due to Coupling Misalignments
1988-05-01
angular miaalignments are universal joints ( commonly called Hooke’s Joints or Cardan Joints). As can be seen in figure 3-3 (a through c), a universal...or Cardan joint consists of a drive yoke which is rigidly fastened to the drive shaft, a driven yoke which is rigidly fastened to the driven shaft...stltted clsks Grid coupling * FIGURE 7-1 121 (Piotrowski, 1986). The fourth and fifth major categories of couplings are the universal or Cardan joints and
Coupled rotor-flexible fuselage vibration reduction using open loop higher harmonic control
Papavassiliou, I.; Friedmann, P. P.; Venkatesan, C.
1991-01-01
A fundamental study of vibration prediction and vibration reduction in helicopters using active controls was performed. The nonlinear equations of motion for a coupled rotor/flexible fuselage system have been derived using computer algebra on a special purpose symbolic computer facility. The trim state and vibratory response of the helicopter are obtained in a single pass by applying the harmonic balance technique and simultaneously satisfying the trim and the vibratory response of the helicopter for all rotor and fuselage degrees of freedom. The influence of the fuselage flexibility on the vibratory response is studied. It is shown that the conventional single frequency higher harmonic control is capable of reducing either the hub loads or only the fuselage vibrations but not both simultaneously. It is demonstrated that for simultaneous reduction of hub shears and fuselae vibrations a new scheme called multiple higher harmonic control is required.
Optimal piezo-electro-mechanical coupling to control plate vibrations
Alessandroni, S; Frezza, F
2010-01-01
A new way of coupling electrical and mechanical waves, using piezoelectric effect, is presented here. Since the energy exchange between two systems supporting wave propagation is maximum when their evolution is governed by similar equations, hence, an optimal electromechanical coupling is obtained by designing an electric network which is "analog" to the mechanical structure to be controlled. In this paper, we exploit this idea to enhance the coupling, between a Kirchhoff-Love plate and one possible synthesis of its circuital analog, as obtained by means of a set of piezoelectric actuators uniformly distributed upon the plate. It is shown how this approach allows for an optimal energy exchange between the mechanic and the electric forms independent of the modal evolution of the structure. Moreover, we show how an efficient electric dissipation of the mechanical energy can be obtained adding dissipative elements in the electric network.
Energy Technology Data Exchange (ETDEWEB)
Albert, Julian; Falge, Mirjam; Hildenbrand, Heiko; Engel, Volker [Universität Würzburg, Institut für Physikalische und Theoretische Chemie, Emil-Fischer-Str. 42, Campus Nord, Am Hubland, 97074 Würzburg (Germany); Gomez, Sandra; Sola, Ignacio R. [Departamento de Quimica Fisica, Universidad Complutense, 28040 Madrid (Spain)
2015-07-28
We theoretically investigate the photon-echo spectroscopy of coupled electron-nuclear quantum dynamics. Two situations are treated. In the first case, the Born-Oppenheimer (adiabatic) approximation holds. It is then possible to interpret the two-dimensional (2D) spectra in terms of vibrational motion taking place in different electronic states. In particular, pure vibrational coherences which are related to oscillations in the time-dependent third-order polarization can be identified. This concept fails in the second case, where strong non-adiabatic coupling leads to the breakdown of the Born-Oppenheimer-approximation. Then, the 2D-spectra reveal a complicated vibronic structure and vibrational coherences cannot be disentangled from the electronic motion.
Directory of Open Access Journals (Sweden)
Dirk Hagelstein
2000-01-01
Full Text Available The increased use of small gas turbines and turbochargers in different technical fields has led to the development of highly-loaded centrifugal compressors with extremely thin blades. Due to high rotational speed and the correspondingly high centrifugal loads, the shape of the impeller hub must also be optimized. This has led to a reduction of the thickness of the impeller disc in the outlet region. The thin parts of the impeller are very sensitive and may be damaged by the excitation of dangerous blade vibrations.
Forced vibration and wave propagation in mono-coupled periodic structures
DEFF Research Database (Denmark)
Ohlrich, Mogens
1986-01-01
This paper describes the wave propagation and vibration characteristics of mono-coupled structures which are of spatially periodic nature. The receptance approach to periodic structure theory is applied to study undamped periodic systems with composite structural elements; particular emphasis...... of the determination of the junction-receptance. The influence of such a disorder is illustrated by a simple example...
Coupling of Flexural and Longitudinal Damped Vibration in a Two-Layered Beam
Directory of Open Access Journals (Sweden)
F. Pourroy
1998-01-01
Full Text Available In dynamics, the effect of varying the constitutive materials’ thickness of a two-layered beam is investigated. Resonance frequencies and damping variations are determined. It is shown that for specific thicknesses the coupling of longitudinal and flexural vibrations influences the global modal damping ratio significantly.
Coupled vibrations in peptides and proteins: Structural information using 2D-IR spectroscopy
Huerta Viga, A.
2014-01-01
We describe experimental evidence of how detecting the coupling between vibrations can give access to structural information of proteins and peptides at the molecular level. We focus on the investigation of the folded and unfolded states of proteins and peptides in equilibrium. We investigate two
Tan, Qing-Hai; Zhang, Xin; Luo, Xiang-Dong; Zhang, Jun; Tan, Ping-Heng
2017-03-01
Two-dimensional transition metal dichalcogenides (TMDs) have attracted extensive attention due to their many novel properties. The atoms within each layer in two-dimensional TMDs are joined together by covalent bonds, while van der Waals interactions combine the layers together. This makes its lattice dynamics layer-number dependent. The evolutions of ultralow frequency ( 50 cm‑1) vibration modes in few-layer TMDs and demonstrate how the interlayer coupling leads to the splitting of high-frequency vibration modes, known as Davydov splitting. Such Davydov splitting can be well described by a van der Waals model, which directly links the splitting with the interlayer coupling. Our review expands the understanding on the effect of interlayer coupling on the high-frequency vibration modes in TMDs and other two-dimensional materials. Project supported by the National Basic Research Program of China (No. 2016YFA0301200), the National Natural Science Foundation of China (Nos. 11225421, 11474277, 11434010, 61474067, 11604326, 11574305 and 51527901), and the National Young 1000 Talent Plan of China.
Abdelkefi, A.; Najar, F.; Nayfeh, A. H.; Ben Ayed, S.
2011-11-01
Recently, piezoelectric cantilevered beams have received considerable attention for vibration-to-electric energy conversion. Generally, researchers have investigated a classical piezoelectric cantilever beam with or without a tip mass. In this paper, we propose the use of a unimorph cantilever beam undergoing bending-torsion vibrations as a new piezoelectric energy harvester. The proposed design consists of a single piezoelectric layer and a couple of asymmetric tip masses; the latter convert part of the base excitation force into a torsion moment. This structure can be tuned to be a broader band energy harvester by adjusting the first two global natural frequencies to be relatively close to each other. We develop a distributed-parameter model of the harvester by using the Euler-beam theory and Hamilton's principle, thereby obtaining the governing equations of motion and associated boundary conditions. Then, we calculate the exact eigenvalues and associated mode shapes and validate them with a finite element (FE) model. We use these mode shapes in a Galerkin procedure to develop a reduced-order model of the harvester, which we use in turn to obtain closed-form expressions for the displacement, twisting angle, voltage output, and harvested electrical power. These expressions are used to conduct a parametric study for the dynamics of the system to determine the appropriate set of geometric properties that maximizes the harvested electrical power. The results show that, as the asymmetry is increased, the harvester's performance improves. We found a 30% increase in the harvested power with this design compared to the case of beams undergoing bending only. We also show that the locations of the two masses can be chosen to bring the lowest two global natural frequencies closer to each other, thereby allowing the harvesting of electrical power from multi-frequency excitations.
Schaefer, Jan; Nagata, Yuki; Bonn, Mischa
2016-01-01
Vibrational coupling is relevant not only for dissipation of excess energy after chemical reactions but also for elucidating molecular structure and dynamics. It is particularly important for OH stretch vibrational spectra of water, for which it is known that in bulk both intra- and intermolecular coupling alter the intensity and line shape of the spectra. In contrast with bulk, the unified picture of the inter/intra-molecular coupling of OH groups at the water-air interface has been lacking. Here, combining sum-frequency generation experiments and simulation for isotopically diluted water and alcohols, we unveil effects of inter- and intramolecular coupling on the vibrational spectra of interfacial water. Our results show that both inter- and intramolecular coupling contribute to the OH stretch vibrational response of the neat H2O surface, with intramolecular coupling generating a double-peak feature, while the intermolecular coupling induces a significant red shift in the OH stretch response.
Body vibrational spectra of metal flute models
Hurtgen, Clare M.; Lawson, Dewey T.
2002-11-01
For years, flutists have argued over the tonal advantages of using different precious metals for their instruments. Occasionally, scientists have entered the fray and attempted to offer an objective point of view based on experimental measurements. However, their research often involved actual instruments and performers, ignoring variations in wall thickness, craftsmanship, and human consistency. These experiments have been conducted using a variety of methods; all have concluded that wall material has no effect on tone. This paper approaches the question using simple tubular models, excited by a wind source through a fipple mouthpiece. The amplitude and phase of the harmonic components of the body vibrational signal were measured with a stereo cartridge. Results demonstrated the existence of complex patterns of wall vibrations in the vicinity of a tone hole lattice, at frequencies that match significant harmonics of the air column. Additionally, the tube wall was found to expand in a nonuniform or ''elliptical'' manner due to the asymmetry of the tone holes. While this method is somewhat removed from direct musical applications, it can provide an objective, quantitative basis for assessing the source of differences among flutes. [Work financed by two Undergraduate Research Support grants from Duke University.
Fermi resonance-algebraic model for molecular vibrational spectra
Institute of Scientific and Technical Information of China (English)
侯喜文; 董世海; 谢汨; 马中骐
1999-01-01
A Fermi resonance-algebraic model is proposed for molecular vibrations, where a U(2) algebra is used for describing the vibrations of each bond, and Fermi resonances between stretching and bending modes are taken into account. The model for a bent molecule XY2 and a molecule XY3 is successfully applied to fitting the recently observed vibrational spectrum of the water molecule and arsine (AsH3), respectively, and the results are compared with those of other models. Calculations show that algebraic approaches can be used as an effective method to describe molecular vibrations with small standard deviations.
A Coupled Helicopter Rotor/Fuselage Dynamics Model Using Finite Element Multi-body
Directory of Open Access Journals (Sweden)
Cheng Qi-you
2016-01-01
Full Text Available To develop a coupled rotor/flexible fuselage model for vibration reduction studies, the equation of coupled rotor-fuselage is set up based on the theory of multi-body dynamics, and the dynamic analysis model is established with the software MSC.ADMAS and MSC.NASTRAN. The frequencies and vibration acceleration responses of the system are calculated with the model of coupled rotor-fuselage, and the results are compared with those of uncoupled modeling method. Analysis results showed that compared with uncoupled model, the dynamic characteristic obtained by the model of coupled rotor-fuselage are some different. The intrinsic frequency of rotor is increased with the increase of rotational velocities. The results also show that the flying speed has obvious influence on the vibration acceleration responses of the fuselage. The vibration acceleration response in the vertical direction is much higher at the low speed and high speed flight conditions.
Lattanzi; di Lauro C
1999-12-01
The mechanism of torsional Coriolis interaction of E(1d) and E(2d) vibrational modes in ethane-like molecules is investigated, and it is shown that this coupling can drastically affect the torsional splitting in the degenerate vibrational states. A basic point of our treatment is that the sets of coordinates of head and tail which combine with the + sign to generate E(1d) normal coordinates are in general different from those which combine with the - sign to generate E(2d) normal coordinates. It is shown that the zeta(gamma) torsional Coriolis coefficients calculated by the usual methods of normal mode analysis are related to the vibrational angular momenta within head and tail referred to the internal rotor axis systems. With knowledge of the L and L(-1) matrices it is possible to transform these coefficients for reference to the molecule-fixed frame. It is peculiar that torsional Coriolis matrix elements occur between E(1d) and E(2d) vibrational components with the same x or y orientation in the molecule-fixed frame. The matrix elements of the torsional Coriolis operator and other operators responsible for the end-to-end coupling are determined, and a method for calculating vibration-torsion energies, and then torsional splittings, in degenerate vibrational states is outlined. Detailed calculations require a global model, involving all the degenerate vibrational basis states in a complex mechanism of interactions, but it is shown that useful information can be obtained by means of simplified models. Our semiempirical rule that degenerate vibrational states with a large negative value of the diagonal vibration-rotation Coriolis coefficient are likely to deviate much from the behavior of E(1d) or E(2d) vibrational states, with a sensible decrease of the torsional splittings, is confirmed. Copyright 1999 Academic Press.
Torsion - Vibration Couplings in the CH{_3}OO{\\cdot} Radical
Huang, Meng; Miller, Terry A.; McCoy, Anne B.; Hsu, Kuo-Hsiang; Huang, Yu-Hsuan; Lee, Yuan-Pern
2016-06-01
A partially rotationally resolved infrared spectrum of CH{_3}OO{\\cdot} in the CH stretch region has been reported. The rotational contour of the {ν_2} CH stretch band in the experimental spectrum can be simulated with an asymmetric rotor model. The simulation shows good agreement with the experimental spectrum except that the broadening of the Q-branch in the experimental spectrum remains unexplained. This broadening is likely due to the sequence band transitions from the torsionally excited levels populated at room temperature to combination levels involving the CH stretch and the same number of torsional quanta. A four dimension model involving three CH stretches and the CH{_3} torsion is applied to the CH{_3}OO{\\cdot} radical to obtain the frequencies and intensities of the vibrational transitions in the CH stretch region. Based on these calculations, the torsional sequence bands are calculated to be slightly shifted from the origin band, because of the couplings between the CH stretches and CH{_3} torsion, thereby causing the apparent broadening observed for the {ν_2} fundamental. Due to the accidental degeneracy of two different CH stretch and CH{_3} torsion combination levels which differ by one quantum in the torsional excitation, the frequencies of the torsional sequence bands will be very sensitive to details of the potential, which makes the shifts difficult to precisely predict with electronic structure calculations. Complementary analyses are now underway for the other two CH stretch vibrational bands, {ν_1} and {ν_9}. K.-H. Hsu, Y.-H. Huang, Y.-P. Lee, M. Huang, T. A. Miller and A. B. McCoy J. Phys. Chem. A, in press, DOI: 10.1021/acs.jpca.5b12334
THERMOELASTICALLY COUPLED AXISYMMETRIC NONLINEAR VIBRATION OF SHALLOW SPHERICAL AND CONICAL SHELLS
Institute of Scientific and Technical Information of China (English)
王永岗; 戴诗亮
2004-01-01
The problem of axisymmetric nonlinear vibration for shallow thin spherical and conical shells when temperature and strain fields are coupled is studied. Based on the large deflection theories of von Krmn and the theory of thermoelasticity, the whole governing equations and their simplified type are derived. The time-spatial variables are separated by Galerkin's technique, thus reducing the governing equations to a system of time-dependent nonlinear ordinary differential equation. By means of regular perturbation method and multiple-scales method, the first-order approximate analytical solution for characteristic relation of frequency vs amplitude parameters along with the decay rate of amplitude are obtained, and the effects of different geometric parameters and coupling factors as well as boundary conditions on thermoelastically coupled nonlinear vibration behaviors are discussed.
Vibrational frequency of a strong-coupling polaron in a quantum rod at finite temperatures
Institute of Scientific and Technical Information of China (English)
Ding Zhao-Hua; Xiao Jing-Lin
2011-01-01
The Hamiltonian of a quantum rod with a boundary is presented after a coordinate transformation that changes the original ellipsoidal boundary into a spherical one. We then study the effect of temperature on the vibrational frequency and the ground state binding energy of the strong-coupling polaron in the rod. The two quantities are expressed as functions of the aspect ratio of the ellipsoid,the transverse and the longitudinal effective confinement lengths,the temperature and the electron-phonon coupling strength by linear combination operator and unitary transformation methods. It is found that the vibrational frequency and the ground state binding energy will increase rapidly with decreasing transverse and longitudinal effective confinement lengths. They are increasing functions of the electronphonon coupling strength but become decreasing ones of the temperature and the aspect ratio.
Institute of Scientific and Technical Information of China (English)
黄毅; 刘辉; 项昌乐; 杨志刚
2014-01-01
随着对齿轮传动系统动态品质要求的提高，仅固有特性及其灵敏度的分析已经无法满足车辆传动系统动态特性分析的要求，对强迫振动下响应特性的灵敏度研究可为减振设计提供进一步的指导。研究非线性动力学响应对轴段扭转刚度、质量点惯量以及轮齿啮合误差的灵敏度。将某车辆传动系统样机作为研究对象，以发动机激励作为输入，建立平移扭转耦合集中参数动力学模型。模型中考虑时变啮合刚度、齿侧间隙、轮齿制造、安装误差以及质量偏心等非线性因素，通过直接求导法建立灵敏度方程，利用数值求解的方法获得动力学响应对设计参数的相对灵敏度并进一步将其转化成工程中有实际意义的物理量的灵敏度结果，为齿轮传动系统基于动态响应的参数修改、模型修正和参数优化等方面提供理论依据。%With increase in requirements of dynamic quality of a transmission system,only the eigensensitivities analysis can not meet the requirements of dynamic characteristics of a vehicle transmission system.It's needed to do response sensitivity study to find a guideline to reduce vibration of a vehicle transmission system in designing stage.Here, the sensitivities of dynamic response with respect to design parameters such as,shaft torsional stiffness,moment of inertia, and transmission errors of gear pairs,et al.were investigated.The translation-torsional coupled dynamic model of a vehicle transmission system taking engine excitation as an input source was built up with the lumped parameter method.The sensitivity equations were derived from dynamic equations containing nonlinear terms, such as, time-varying mesh stiffness,backlash of gear pairs,mass eccentricity,transmission error et al.The relative sensitivities of dynamic response with respect to design parameters then turned into relative sensitivities of force/torque with respect to design
A vibration model for centrifugal contactors
Energy Technology Data Exchange (ETDEWEB)
Leonard, R.A.; Wasserman, M.O.; Wygmans, D.G.
1992-11-01
Using the transfer matrix method, we created the Excel worksheet ``Beam`` for analyzing vibrations in centrifugal contactors. With this worksheet, a user can calculate the first natural frequency of the motor/rotor system for a centrifugal contactor. We determined a typical value for the bearing stiffness (k{sub B}) of a motor after measuring the k{sub B} value for three different motors. The k{sub B} value is an important parameter in this model, but it is not normally available for motors. The assumptions that we made in creating the Beam worksheet were verified by comparing the calculated results with those from a VAX computer program, BEAM IV. The Beam worksheet was applied to several contactor designs for which we have experimental data and found to work well.
Spatial spectrograms of vibrating atomic force microscopy cantilevers coupled to sample surfaces
Energy Technology Data Exchange (ETDEWEB)
Wagner, Ryan; Raman, Arvind, E-mail: raman@purdue.edu [Birck Nanotechnology Center, 1205 W. State Street, Purdue University, West Lafayette, Indiana 47907 (United States); Proksch, Roger, E-mail: Roger.Proksch@oxinst.com [Asylum Research, 6310 Hollister Ave., Santa Barbara, California 93117 (United States)
2013-12-23
Many advanced dynamic Atomic Force Microscopy (AFM) techniques such as contact resonance, force modulation, piezoresponse force microscopy, electrochemical strain microscopy, and AFM infrared spectroscopy exploit the dynamic response of a cantilever in contact with a sample to extract local material properties. Achieving quantitative results in these techniques usually requires the assumption of a certain shape of cantilever vibration. We present a technique that allows in-situ measurements of the vibrational shape of AFM cantilevers coupled to surfaces. This technique opens up unique approaches to nanoscale material property mapping, which are not possible with single point measurements alone.
Musculoskeletal modelling of low-frequency whole-body vibrations
DEFF Research Database (Denmark)
Rasmussen, John; Andersen, Michael Skipper
2012-01-01
This paper presents a musculoskeletal model for assessment of the effect of low-frequency whole-body vibrations on the human body. It is a basic assumption behind the model that the vibrations are slow enough to allow the central nervous system to respond to them in terms of muscle activations...
Experimental and Numerical Investigations on Vibration Characteristics of a Loaded Ship Model
Institute of Scientific and Technical Information of China (English)
Pu Liang; Ming Hong; Zheng Wang
2015-01-01
In this paper, the vibration characteristics of the structure in the finite fluid domain are analyzed using a coupled finite element method. The added mass matrix is calculated with finite element method (FEM) by 8-node acoustic fluid elements. The vibration characteristics of the structure in the finite fluid domain are calculated combining structure FEM mass matrix. By writing relevant programs, the numerical analysis on vibration characteristics of a submerged cantilever rectangular plate in finite fluid domain and loaded ship model is performed. A modal identification experiment for the loaded ship model in air and in water is conducted and the experiment results verify the reliability of the numerical analysis. The numerical method can be used for further research on vibration characteristics and acoustic radiation problems of the structure in the finite fluid domain.
Wang, Xi; Yang, Bintang; Yu, Hu; Gao, Yulong
2017-04-01
The impulse excitation of mechanism causes transient vibration. In order to achieve adaptive transient vibration control, a method which can exactly model the response need to be proposed. This paper presents an analytical model to obtain the response of the primary system attached with dynamic vibration absorber (DVA) under impulse excitation. The impulse excitation which can be divided into single-impulse excitation and multi-impulse excitation is simplified as sinusoidal wave to establish the analytical model. To decouple the differential governing equations, a transform matrix is applied to convert the response from the physical coordinate to model coordinate. Therefore, the analytical response in the physical coordinate can be obtained by inverse transformation. The numerical Runge-Kutta method and experimental tests have demonstrated the effectiveness of the analytical model proposed. The wavelet of the response indicates that the transient vibration consists of components with multiple frequencies, and it shows that the modeling results coincide with the experiments. The optimizing simulations based on genetic algorithm and experimental tests demonstrate that the transient vibration of the primary system can be decreased by changing the stiffness of the DVA. The results presented in this paper are the foundations for us to develop the adaptive transient vibration absorber in the future.
Institute of Scientific and Technical Information of China (English)
孟庆华; 刘清友
2011-01-01
According to the drilling string mechanics and theory of momentum conservation, transverse vibration model of drilling string was established, considerating influence of gas drilling liquid to the drill string internal-external coupling, this model is different from the general vibration model of beam structure, which contained the axial force of drilling string, injection pressure inside drill string, annulus pressure and the gas inside drill string influenced the vibration of the drilling string, the boundary conditions and original conditions were obtained. The paper proved there had only optimum control element using Banach space geometry properties through looking on external active function as control parameters.%根据钻柱力学和动量守恒基本理论,建立了考虑气体钻井液对钻柱内外耦合影响时的钻柱横向振动模型,此模型与一般的梁式结构的振动模型不同,它包含了钻柱轴力、钻柱内注入压力、环空压力和钻柱内气体对钻柱振动的影响.同时给出边界条件和初始条件.通过把系统外激励函数当作控制变量,利用Banach空间几何性质证明了此系统存在唯一最优控制元.
Frame junction vibration transmission with a modified frame deformation model.
Moore, J A
1990-12-01
A previous paper dealt with vibration transmission through junctions of connected frame members where the allowed frame deformations included bending, torsion, and longitudinal motions [J.A. Moore, J. Acoust. Soc. Am. 88, 2766-2776 (1990)]. In helicopter and aircraft structures the skin panels can constitute a high impedance connection along the length of the frames that effectively prohibits in-plane motion at the elevation of the skin panels. This has the effect of coupling in-plane bending and torsional motions within the frame. This paper discusses the transmission behavior through frame junctions that accounts for the in-plane constraint in idealized form by assuming that the attached skin panels completely prohibit inplane motion in the frames. Also, transverse shear deformation is accounted for in describing the relatively deep web frame constructions common in aircraft structures. Longitudinal motion in the frames is not included in the model. Transmission coefficient predictions again show the importance of out-of-plane bending deformation to the transmission of vibratory energy in an aircraft structure. Comparisons are shown with measured vibration transmission data along the framing in the overhead of a helicopter airframe, with good agreement. The frame junction description has been implemented within a general purpose statistical energy analysis (SEA) computer code in modeling the entire airframe structure including skin panels.
Classical and quantum proton vibration in a nonharmonic strongly coupled system
McDonald, K. M.; Thorson, W. R.; Choi, J. H.
1993-09-01
Classical and quantum descriptions of proton vibration are compared for a coupled nonharmonic model based on an ab initio potential for the bifluoride ion, [FHF]-. Accurate quantum calculations and exact classical dynamics are compared with quantum and classical versions of the self-consistent-field (SCF) approximation. Semiclassical and quantum SCF eigenvalues agree within JWKB-type errors. The SCF scheme closely approximates exact quantum states for the lowest 4-5 vibrational levels of each symmetry, except at avoided crossings where strong CI mixing of SCF levels occurs. True classical motion, however, is mainly irregular except at very low energies, and even where it remains regular it may be strongly reorganized by a 1:1 periodic resonance associated with major potential surface features. Strongly mixed CI states at systematic avoided crossings of SCF levels at higher energies do have classical analogs in the reorganized classical motions seen at low energies; stabilized CI components correspond to a stable periodic 1:1 orbit, destabilized components to an unstable periodic 1:1 elliptical orbit. Canonical perturbation theory is used to study further the sense in which the exactly separable classical SCF Hamiltonian is ``close'' to the true Hamiltonian. Where true motion is modal or SCF-like, first-order perturbed trajectories and second-order perturbed energies describe it very accurately. However since the dynamics can be strongly disturbed even at very low energies, correlation effects are obviously not ``small'' in the sense usually meant in classical dynamics, i.e., that regular trajectories mostly remain regular in the nonseparable perturbed system.
Control of Rotor-Blade Coupled Vibrations Using Shaft-Based Actuation
DEFF Research Database (Denmark)
Christensen, Rene H.; Santos, Ilmar
2006-01-01
When implementing active control into bladed rotating machines aiming at reducing blade vibrations, it can be shown that blade as well as rotor vibrations can in fact be controlled by the use of only shaft-based actuation. Thus the blades have to be deliberately mistuned. This paper investigates...... of modal controllability and observability converge toward steady levels as the degree of mistuning is increased. Finally, experimental control results are presented to prove the theoretical conclusions and to show the feasibility of controlling rotor and blade vibrations by means of shaft-based actuation...... the dynamical characteristics of a mistuned bladed rotor and shows how, why and when a bladed rotor becomes controllable and observable if properly mistuned. As part of such investigation modal controllability and observability of a tuned as well as a mistuned coupled rotor-blade system are analysed...
Vibration suppression in a flexible gyroscopic system using modal coupling strategies
Directory of Open Access Journals (Sweden)
Siddiqui Sultan A. Q.
1996-01-01
Full Text Available Several recent studies have shown that vibrations in a two-degree-of-freedom system can be suppressed by using modal coupling based control techniques. This involves making the first two natural frequencies commensurable (e.g, in a ratio of 1:1 or 1:2 to establish a state of Internal Resonance (IR. When the system exhibits IR, vibrations in the two directions are strongly coupled resulting in a beat phenomenon. Upon introducing damping in one direction, oscillations in both directions can be quickly suppressed. In this paper we consider vibration suppression of a flexible two-degree-of-freedom gyroscopic system using 1:1 and 1:2 IR. The possibility of using 1:1 and 1:2 IR to enhance the coupling in the system is established analytically using the perturbation method of multiple scales. The results of IR based control strategy are compared with a new method, which is based on tuning the system parameters to make the mode shapes identical. Results indicate that this new technique is more efficient and easy to implement than IR based control strategies. Another advantage of this method is that there is no restriction on the frequencies as in the case of IR. Finally, a control torque is obtained which on application automatically tunes the system parameters to establish modal coupling.
-ree vibration analysis of cracked thin plates by quasi-convex coupled isogeometric-meshfree method
Institute of Scientific and Technical Information of China (English)
Hanjie ZHANG[1,2; JunzhaoWU[1,2; Dongdong WANG[1,2
2015-01-01
The free vibration analysis of cracked thin plates via a quasi-convex coupled isogeometric-meshfree method is presented. This formulation employs the consistently coupled isogeometric-meshfree strategy where a mixed basis vector of the convex B-splines is used to impose the consistency conditions throughout the whole problem domain. Meanwhile, the rigid body modes related to the mixed basis vector and reproducing conditions are also discussed. The mixed basis vector simultaneously offers the consistent isogeometric-meshfree coupling in the coupled region and the quasi-convex property for the meshfree shape functions in the meshfree region, which is particularly attractive for the vibration analysis. The quasi-convex meshfree shape functions mimic the isogeometric basis function as well as offer the meshfree nodal arrangement flexibility. Subsequently, this approach is exploited to study the free vibration analysis of cracked plates, in which the plate geometry is exactly represented by the isogeometric basis functions, while the cracks are discretized by meshfree nodes and highly smoothing approximation is invoked in the rest of the problem domain. The efficacy of the present method is illustrated through several numerical examples.
Vibrational exciton-mediated quantum state transfert: a simple model
Pouthier, Vincent J C
2012-01-01
A communication protocol is proposed in which quantum state transfer is mediated by a vibrational exciton. We consider two distant molecular groups grafted on the sides of a lattice. These groups behave as two quantum computers where the information in encoded and received. The lattice plays the role of a communication channel along which the exciton propagates and interacts with a phonon bath. Special attention is paid for describing the system involving an exciton dressed by a single phonon mode. The Hamiltonian is thus solved exactly so that the relevance of the perturbation theory is checked. Within the nonadiabatic weak-coupling limit, it is shown that the system supports three quasi-degenerate states that define the relevant paths followed by the exciton to tunnel between the computers. When the model parameters are judiciously chosen, constructive interferences take place between these paths. Phonon-induced decoherence is minimized and a high-fidelity quantum state transfer occurs over a broad temperat...
Wang, Lin; Ishiyama, Tatsuya; Morita, Akihiro
2017-09-14
A flexible and polarizable molecular model of ethanol is developed to extend our investigation of thermodynamic, structural, and vibrational properties of the liquid and interface. A molecular dynamics (MD) simulation with the present model confirmed that this model well reproduces a number of properties of liquid ethanol, including density, heat of vaporization, surface tension, molecular dipole moment, and trans/gauche ratio. In particular, the present model can describe vibrational IR, Raman, and sum frequency generation (SFG) spectra of ethanol and partially deuterated analogues with reliable accuracy. The improved accuracy is largely attributed to proper modeling of the conformational dependence and the intramolecular couplings including Fermi resonance in C-H vibrations. Precise dependence of torsional motions is found to be critical in representing vibrational spectra of the C-H bending. This model allows for further vibrational analysis of complicated alkyl groups widely observed in various organic molecules with MD simulation.
Vibration induced flow in hoppers: DEM 2D polygon model
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
A two-dimensional discrete element model (DEM) simulation of cohesive polygonal particles has been developed to assess the benefit of point source vibration to induce flow in wedge-shaped hoppers. The particle-particle interaction model used is based on a multi-contact principle.The first part of the study investigated particle discharge under gravity without vibration to determine the critical orifice size (Be) to just sustain flow as a function of particle shape. It is shown that polygonal-shaped particles need a larger orifice than circular particles. It is also shown that Be decreases as the number of particle vertices increases. Addition of circular particles promotes flow of polygons in a linear manner.The second part of the study showed that vibration could enhance flow, effectively reducing Be. The model demonstrated the importance of vibrator location (height), consistent with previous continuum model results, and vibration amplitude in enhancing flow.
Directory of Open Access Journals (Sweden)
Dongxiao Hou
2014-01-01
Full Text Available Nonlinear dynamic rolling forces in the vertical and horizontal directions are, respectively, established, considering the impact of vertical and horizontal directions vibration of rolls. Then a vertical-horizontal coupling nonlinear vibration dynamic model of rolling mill rolls is proposed, based on the interactions between this dynamic rolling force and mill structure. The amplitude-frequency equations of the main resonance and inner resonance are carried out by using multiple-scale method. The characteristics of amplitude frequency under nonlinear stiffness, damping, and amplitude of the disturbance are obtained by adopting the actual parameters of 1780 rolling mills. Finally, the bifurcation behavior of the system is studied, and it is found that many dynamic behaviors such as period, period-3 motion, and chaos exist in rolling mill, and this behavior could be restrained effectively by choosing proper system parameters.
Tandem Strip Mill’s Multi-parameter Coupling Dynamic Modeling Based on the Thickness Control
Institute of Scientific and Technical Information of China (English)
PENG Yan; ZHANG Yang; SUN Jianliang; ZANG Yong
2015-01-01
The rolling process is determined by the interaction of a number of different movements, during which the relative movement occurs between the vibrating roll system and the rolled piece, and the roll system’s vibration interacts with the strip’s deformation and rigid movement. So many parameters being involved leads to a complex mechanism of this coupling effect. Through testing and analyzing the vibration signals of the mill in the rolling process, the rolling mill’s coupled model is established with comprehensive consideration of the coupling interaction between the mill’s vertical vibration, its torsional vibration and the working roll’s horizontal vibration, and vibration characteristics of different forms of rolling mill’s vibration are analyzed under the coupling effect. With comprehensive attention to the relationship between the roll system, the moving strip and the rolling parameters’ dynamic properties, and also from the strip thickness control point of view, further research is done on the coupling mechanism between the roll system’s movement and the moving strip’s characteristics in the rolling process. As a result, the law of inertial coupling and the stiffness coupling effect caused by different forms of the roll system’s vibration is determined and the existence of nonlinear characteristics caused by the elastic deformation of moving strip is also found. Furthermore, a multi-parameter coupling-dynamic model is established which takes the tandem strip mill as its research object by making a detailed kinematics analysis of the roll system and using the principle of virtual work. The coupling-dynamic model proposes the instruction to describe the roll system’s movement, and analyzes its dynamic response and working stability, and provides a theoretical basis for the realization of the strip thickness’ dynamic control.
Tandem strip mill's multi-parameter coupling dynamic modeling based on the thickness control
Peng, Yan; Zhang, Yang; Sun, Jianliang; Zang, Yong
2015-03-01
The rolling process is determined by the interaction of a number of different movements, during which the relative movement occurs between the vibrating roll system and the rolled piece, and the roll system's vibration interacts with the strip's deformation and rigid movement. So many parameters being involved leads to a complex mechanism of this coupling effect. Through testing and analyzing the vibration signals of the mill in the rolling process, the rolling mill's coupled model is established with comprehensive consideration of the coupling interaction between the mill's vertical vibration, its torsional vibration and the working roll's horizontal vibration, and vibration characteristics of different forms of rolling mill's vibration are analyzed under the coupling effect. With comprehensive attention to the relationship between the roll system, the moving strip and the rolling parameters' dynamic properties, and also from the strip thickness control point of view, further research is done on the coupling mechanism between the roll system's movement and the moving strip's characteristics in the rolling process. As a result, the law of inertial coupling and the stiffness coupling effect caused by different forms of the roll system's vibration is determined and the existence of nonlinear characteristics caused by the elastic deformation of moving strip is also found. Furthermore, a multi-parameter coupling-dynamic model is established which takes the tandem strip mill as its research object by making a detailed kinematics analysis of the roll system and using the principle of virtual work. The coupling-dynamic model proposes the instruction to describe the roll system's movement, and analyzes its dynamic response and working stability, and provides a theoretical basis for the realization of the strip thickness' dynamic control.
Numerical Investigation of Flapwise-Torsional Vibration Model of a Smart Section Blade with Microtab
Directory of Open Access Journals (Sweden)
Nailu Li
2015-01-01
Full Text Available This study presents a method to develop an aeroelastic model of a smart section blade equipped with microtab. The model is suitable for potential passive vibration control study of the blade section in classic flutter. Equations of the model are described by the nondimensional flapwise and torsional vibration modes coupled with the aerodynamic model based on the Theodorsen theory and aerodynamic effects of the microtab based on the wind tunnel experimental data. The aeroelastic model is validated using numerical data available in the literature and then utilized to analyze the microtab control capability on flutter instability case and divergence instability case. The effectiveness of the microtab is investigated with the scenarios of different output controllers and actuation deployments for both instability cases. The numerical results show that the microtab can effectively suppress both vibration modes with the appropriate choice of the output feedback controller.
Coupled vibrations of rectangular buildings subjected to normally-incident random wind loads
Safak, E.; Foutch, D.A.
1987-01-01
A method for analyzing the three-directional coupled dynamic response of wind-excited buildings is presented. The method is based on a random vibration concept and is parallel to those currently used for analyzing alongwind response. Only the buildings with rectangular cross-section and normally-incident wind are considered. The alongwind pressures and their correlations are represented by the well-known expressions that are available in the literature. The acrosswind forces are assumed to be mainly due to vortex shedding. The torque acting on the building is taken as the sum of the torque due to random alongwind forces plus the torque due to asymmetric acrosswind forces. The study shows the following: (1) amplitude of acrosswind vibrations can be several times greater than that of alongwind vibrations; (2) torsional vibrations are significant if the building has large frontal width, and/or it is asymmetric, and/or its torsional natural frequency is low; (3) even a perfectly symmetric structure with normally incident wind can experience significant torsional vibrations due to the randomness of wind pressures. ?? 1987.
Prospects for coupled modelling
Energy Technology Data Exchange (ETDEWEB)
Savage, D.
2012-07-01
Clay-based buffer and tunnel backfill materials are important barriers in the KBS- 3 repository concept for final disposal of spent nuclear fuel in Finland. Significant changes can be expected to occur to the properties and behaviour of buffer and backfill, especially during re-saturation and through the thermal period. Reactions will occur in response to thermal and chemical gradients, induced by the thermal output of the spent fuel and at interfaces between different barrier materials, such as cement/clay, steel/clay etc. Processes of ion exchange, mineral dissolution and precipitation, and swelling can lead to significant re-distribution of mass and evolution of physical properties so that reliable predictive modelling of future behaviour and properties must be made. This report evaluates the current status of modelling of buffer and backfill evolution and tries to assess the potential future capabilities in the short- to medium-term (5-10 years) in a number of technical areas: (1) Non-isothermal (T-H-M-C-B) modelling and the potential for cementation, (2) The consistency of models, (3) Swelling pressure, (4) Cement-bentonite interactions, (5) Iron-bentonite interactions, (6) Mechanical (shear) behavior, and (7) Bentonite erosion.
Zeighampour, Hamid; Tadi Beni, Y.
2014-07-01
This work investigated vibrations and instability of double-walled carbon nanotube (DWCNT) conveying fluid by a modified couple stress theory. For this purpose, Donnell's shell model was developed and, using the modified couple stress theory, the equations of motion and corresponding classical and non-classical boundary conditions of DWCNT were obtained through Hamilton's principle. Then, DWCNT with simple-simple and clamped-clamped supports were investigated. The effect of the van der Waals (vdW) forces was considered between the two walls, and the DWCNT surroundings were modeled as a visco-Pasternak foundation. The governing equations of motion and corresponding boundary conditions were discretized through differential quadrature method (DQM), and the vibration problem was solved by using the boundary conditions. The results show that the effects of fluid velocity, stiffness and damping of the visco-Pasternak foundation, nanotube length, and size parameter in the modified couple stress theory are stronger than in the classical theory. Finally, the effect of vdW forces and presence of fluid in the DWCNT examined on the natural frequencies of DWCNT.
DEFF Research Database (Denmark)
Thomsen, Bo; Hansen, Mikkel Bo; Seidler, Peter
2012-01-01
We report the theory and implementation of vibrational coupled cluster (VCC) damped response functions. From the imaginary part of the damped VCC response function the absorption as function of frequency can be obtained, requiring formally the solution of the now complex VCC response equations....... The absorption spectrum can in this formulation be seen as a matrix function of the characteristic VCC Jacobian response matrix. The asymmetric matrix version of the Lanczos method is used to generate a tridiagonal representation of the VCC response Jacobian. Solving the complex response equations...... in the relevant Lanczos space provides a method for calculating the VCC damped response functions and thereby subsequently the absorption spectra. The convergence behaviour of the algorithm is discussed theoretically and tested for different levels of completeness of the VCC expansion. Comparison is made...
Shear flow induced vibrations of long slender cylinders with a wake oscillator model
Institute of Scientific and Technical Information of China (English)
Fei Ge; Wei Lu; Lei Wang; You-Shi Hong
2011-01-01
A time domain model is presented to study the vibrations of long slender cylinders placed in shear flow. Long slender cylinders such as risers and tension legs are widely used in the field of ocean engineering. They are subjected to vortex-induced vibrations (VIV) when placed within a transverse incident flow. A three dimensional model coupled with wake oscillators is formulated to describe the response of the slender cylinder in cross-flow and in-line directions.The wake oscillators are distributed along the cylinder and the vortex-shedding frequency is derived from the local current velocity. A non-linear fluid force model is accounted for the coupled effect between cross-flow and in-line vibrations. The comparisons with the published experimental data show that the dynamic features of VIV of long slender cylinder placed in shear flow can be obtained by the proposed model, such as the spanwise average displacement, vibration frequency, dominant mode and the combination of standing and traveling waves. The simulation in a uniform flow is also conducted and the result is compared with the case of nonuniform flow. It is concluded that the flow shear characteristic has significantly changed the cylinder vibration behavior.
Prediction Models of Free-Field Vibrations from Railway Traffic
DEFF Research Database (Denmark)
Malmborg, Jens; Persson, Kent; Persson, Peter
2017-01-01
and railways close to where people work and live. Annoyance from traffic-induced vibrations and noise is expected to be a growing issue. To predict the level of vibration and noise in buildings caused by railway and road traffic, calculation models are needed. In the present paper, a simplified prediction...
Ghorbanpour Arani, A; Abdollahian, M; Jalaei, M H
2015-02-21
This paper aims to investigate vibrational behavior of bioliquid-filled microtubules (MTs) embedded in cytoplasm considering surface effects. The interactions between the MT, considered as an orthotropic beam within the framework of Euler-Bernoulli beam (EBB) and Timoshenko beam (TB) models, and its surrounding elastic media are simulated by Pasternak foundation model. The modified couple stress theory (MCST) is applied so as to consider the small scale effects while motion equations are derived using energy method and Hamilto's principle for both EBB and TB models. Finally, an analytical method is employed to obtain the frequency of a bioliquid-filled MT, and therefore frequency-response curves are plotted to investigate the influences of small scale parameter, mass density of bioliquid, surface layer and surrounding elastic medium graphically. The results indicate that bioliquid and surface layers play a key role on the frequency of MTs and that the frequency of MTs is decreased with increasing of the mass density of the bioliquid. Vibration analysis of MTs is being considered as a vital problem since MTs look like the nervous system of the biological cells and transmit vibrational signals. It should be noted that the results of this work are hoped to be of use in advanced medical applications especially in the forthcoming use of MTs in transporters for bio-nanosensors.
Hubac, Ivan; Babinec, Peter; Polasek, Martin; Urban, Jan; Mach, Pavel; Masik, Jozef; Leszczynski, Jerzy
1998-01-01
The coupling of electronic and vibrational motion is studied by two canonical transformations namely normal coordinate transformation and momentum transformation on molecular Hamiltonian. It is shown that by these transformations we can pass from crude approximation to adiabatic approximation and then to non-adiabatic (diabatic) Hamiltonian. This leads to renormalized fermions and renormalized diabatic phonons. Simple calculations on $H_{2}$, $HD$, and $D_{2}$ systems are performed and compar...
Nonequilibrium electron-vibration coupling and conductance fluctuations in a C-60 junction
DEFF Research Database (Denmark)
Ulstrup, Soren; Frederiksen, Thomas; Brandbyge, Mads
2012-01-01
We investigate chemical bond formation and conductance in a molecular C-60 junction under finite bias voltage using first-principles calculations based on density functional theory and nonequilibrium Green's functions (DFT-NEGF). At the point of contact formation we identify a remarkably strong...... the significance of nonequilibrium effects in chemical bond formation/breaking and in electron-vibration coupling in molecular electronics....
Nonequilibrium electron-vibration coupling and conductance fluctuations in a C60 junction
DEFF Research Database (Denmark)
Ulstrup, Søren; Frederiksen, Thomas; Brandbyge, Mads
2012-01-01
We investigate chemical bond formation and conductance in a molecular C60 junction under finite bias voltage using first-principles calculations based on density functional theory and nonequilibrium Green's functions (DFT-NEGF). At the point of contact formation we identify a remarkably strong...... the significance of nonequilibrium effects in chemical bond formation/breaking and in electron-vibration coupling in molecular electronics....
Quantum theory of collective strong coupling of molecular vibrations with a microcavity mode
Pino, Javier del; Feist, Johannes; García-Vidal, Francisco J.
2015-01-01
We develop a quantum mechanical formalism to treat the strong coupling between an electromagnetic mode and a vibrational excitation of an ensemble of organic molecules. By employing a Bloch-Redfield-Wangsness approach, we show that the influence of dephasing-type interactions, i.e., elastic collisions with a background bath of phonons, critically depends on the nature of the bath modes. In particular, for long-range phonons corresponding to a common bath, the dynamics of the "bright state" (t...
State resolved vibrational relaxation modeling for strongly nonequilibrium flows
Boyd, Iain D.; Josyula, Eswar
2011-05-01
Vibrational relaxation is an important physical process in hypersonic flows. Activation of the vibrational mode affects the fundamental thermodynamic properties and finite rate relaxation can reduce the degree of dissociation of a gas. Low fidelity models of vibrational activation employ a relaxation time to capture the process at a macroscopic level. High fidelity, state-resolved models have been developed for use in continuum gas dynamics simulations based on computational fluid dynamics (CFD). By comparison, such models are not as common for use with the direct simulation Monte Carlo (DSMC) method. In this study, a high fidelity, state-resolved vibrational relaxation model is developed for the DSMC technique. The model is based on the forced harmonic oscillator approach in which multi-quantum transitions may become dominant at high temperature. Results obtained for integrated rate coefficients from the DSMC model are consistent with the corresponding CFD model. Comparison of relaxation results obtained with the high-fidelity DSMC model shows significantly less excitation of upper vibrational levels in comparison to the standard, lower fidelity DSMC vibrational relaxation model. Application of the new DSMC model to a Mach 7 normal shock wave in carbon monoxide provides better agreement with experimental measurements than the standard DSMC relaxation model.
Hosseini Hashemi, Sh.; Es'haghi, M.; Karimi, M.
2010-04-01
Free vibration analysis of annular moderately thick plates integrated with piezoelectric layers is investigated in this study for different combinations of soft simply supported, hard simply supported and clamped boundary conditions at the inner and outer edges of the annular plate on the basis of the Levinson plate theory (LPT). The distribution of electric potential along the thickness direction in the piezoelectric layer is assumed as a sinusoidal function so that the Maxwell static electricity equation is approximately satisfied. The differential equations of motion are solved analytically for various boundary conditions of the plate. In this study the closed-form solution for characteristic equations, displacement components of the plate and electric potential are derived for the first time in the literature. To demonstrate the accuracy of the present solution, comparison studies is first carried out with the available data in the literature and then natural frequencies of the piezoelectric coupled annular plate are presented for different thickness-radius ratios, inner-outer radius ratios, thickness of piezoelectric, material of piezoelectric and boundary conditions. Present analytical model provides design reference for piezoelectric material application, such as sensors, actuators and ultrasonic motors.
Modeling of vibration for functionally graded beams
Directory of Open Access Journals (Sweden)
Yiğit Gülsemay
2016-01-01
Full Text Available In this study, a vibration problem of Euler-Bernoulli beam manufactured with Functionally Graded Material (FGM, which is modelled by fourth-order partial differential equations with variable coefficients, is examined by using the Adomian Decomposition Method (ADM.The method is one of the useful and powerful methods which can be easily applied to linear and nonlinear initial and boundary value problems. As to functionally graded materials, they are composites mixed by two or more materials at a certain rate. This mixture at a certain rate is expressed with an exponential function in order to try to minimize singularities from transition between different surfaces of materials as much as possible. According to the structure of the ADM in terms of initial conditions of the problem, a Fourier series expansion method is used along with the ADM for the solution of simply supported functionally graded Euler-Bernoulli beams. Finally, by choosing an appropriate mixture rate for the material, the results are shown in figures and compared with those of a standard (homogeneous Euler-Bernoulli beam.
Electromagnetic Vibration Energy Harvesting Devices Architectures, Design, Modeling and Optimization
Spreemann, Dirk
2012-01-01
Electromagnetic vibration transducers are seen as an effective way of harvesting ambient energy for the supply of sensor monitoring systems. Different electromagnetic coupling architectures have been employed but no comprehensive comparison with respect to their output performance has been carried out up to now. Electromagnetic Vibration Energy Harvesting Devices introduces an optimization approach which is applied to determine optimal dimensions of the components (magnet, coil and back iron). Eight different commonly applied coupling architectures are investigated. The results show that correct dimensions are of great significance for maximizing the efficiency of the energy conversion. A comparison yields the architectures with the best output performance capability which should be preferably employed in applications. A prototype development is used to demonstrate how the optimization calculations can be integrated into the design–flow. Electromagnetic Vibration Energy Harvesting Devices targets the design...
Vibrational excitation in O2and Cl2inductively-coupled plasmas and DC discharges
Booth, Jean-Paul; Marinov, Daniil; Foucher, Mickael; Annusova, Adriana; Guerra, Vasco
2016-09-01
Low-energy electrons can interact with molecules via resonances to cause vibrational excitation with large cross-sections. Such processes can absorb significant energy from the plasma electrons, affecting the electron energy distribution and potentially (via vibration-translation (VT) energy transfer) causing substantial gas heating. The presence of vibrationally excited molecules may significant increase the rates of collisional processes, including electron dissociative attachment and electron impact dissociation into neutral atoms. However, the cross-sections of these processes are often poorly known since they are extremely difficult to measure directly, and reliable theoretical calculations are only now appearing for simple diatomic molecules. We have measured the vibrational distributions in discharges in pure O2 and pure Cl2, using high-sensitivity ultra-broadband ultraviolet absorption spectroscopy. In O2 plasmas significant vibrational excitation is observed, up to v'' =18, with a tail temperature of around 8000K. In Cl2 excitation is only observed up to v'' =3, and the distribution appears to be in local equilibrium with the gas translational temperature (up to 1500K). We are developing a detailed self-consistent 0D global model of these systems including vibrational excitation. Work performed in the LABEX Plas@par project, with financial state aid (ANR-11-IDEX-0004-02 and ANR-13-BS09-0019).
Ghadiri, Majid; Safarpour, Hamed
2016-09-01
In this paper, size-dependent effect of an embedded magneto-electro-elastic (MEE) nanoshell subjected to thermo-electro-magnetic loadings on free vibration behavior is investigated. Also, the surrounding elastic medium has been considered as the model of Winkler characterized by the spring. The size-dependent MEE nanoshell is investigated on the basis of the modified couple stress theory. Taking attention to the first-order shear deformation theory (FSDT), the modeled nanoshell and its equations of motion are derived using principle of minimum potential energy. The accuracy of the presented model is validated with some cases in the literature. Finally, using the Navier-type method, an analytical solution of governing equations for vibration behavior of simply supported MEE cylindrical nanoshell under combined loadings is presented and the effects of material length scale parameter, temperature changes, external electric potential, external magnetic potential, circumferential wave numbers, constant of spring, shear correction factor and length-to-radius ratio of the nanoshell on natural frequency are identified. Since there has been no research about size-dependent analysis MEE cylindrical nanoshell under combined loadings based on FSDT, numerical results are presented to be served as benchmarks for future analysis of MEE nanoshells using the modified couple stress theory.
Banik, Subrata; Pal, Sourav; Prasad, M Durga
2008-10-07
Vibrational excited state energies have been calculated using vibrational coupled cluster linear response theory (CCLRT). The method has been implemented on formaldehyde and water molecule. Convergence studies have been shown with varying the cluster operator from S(4) to S(6) as well as the excitation operator from four bosons to six bosons. A good agreement with full configuration interaction results has been observed with S(6) truncation at coupled-cluster method level and six bosonic excitations at CCLRT level.
A Simplified Model for Vibration Analysis of Diesel Engine Crankshaft System
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A spatial finite element model for vibration analysis of crankshaft system was proposed. The crankshaft body was simplified as spatial rigid frame by using beam elements based on Timoshenko beam theory. The main bearings in system were simplified as linear springs and dashpots. The natural frequencies of the crankshaft system of a four in-line cylinder engine were calculated and compared with the analytical and experimental values available in other publications. In order to simulate the motion of operating crankshaft system, the gas forces, rotating masses and reciprocating masses were considered, the crankshaft and main bearings were coupled in a rotating coordinate system, and a dynamic model for vibration analysis of crankshaft system was established. By applying the dynamic model, the influence of the mass and moment of inertia of front pulley on the behavior of crankshaft vibration was investigated.
Coupled Boundary and Finite Element Analysis of Vibration from Railway Tunnels
DEFF Research Database (Denmark)
Andersen, Lars; Jones, C. J. C.
2004-01-01
The analysis of vibration from railway tunnels is of growing interest as new and higher-speed railways are built under the ground to address the transport problems of growing modern urban areas around cities. Such analysis can be carried out using numerical methods but models and therefore......-dimensional wave propagation. The aim of this paper is to investigate the quality of the information that can be gained from a two-dimensional model of a railway tunnel. The vibration transmission from the tunnel floor to the ground surface is analysed for the frequency range relevant to the perception of whole...
An active head-neck model in whole-body vibration: vibration magnitude and softening.
Rahmatalla, Salam; Liu, Ye
2012-04-05
An active head-neck model is introduced in this work to predict human-dynamic response to different vibration magnitudes during fore-aft whole-body vibration. The proposed model is a rigid-link dynamic system augmented with passive spring-damper tissue-like elements and additional active dampers that resemble the active part of the muscles. The additional active dampers are functions of the input displacement, velocity, and acceleration and are based on active control theories and a kd-tree data-searching scheme. Five human subjects exposed to random fore-aft vibration with frequency content of 0.5-10 Hz were tested under different vibration with magnitudes of 0.46 m/s(2), 1.32 m/s(2), and 1.66 m/s(2) rms. The results showed that the proposed model was able to reasonably capture the softening characteristics of the human head-neck response during fore-aft whole-body vibration of different magnitudes. Copyright Â© 2012 Elsevier Ltd. All rights reserved.
Institute of Scientific and Technical Information of China (English)
HUANG Xiao-Jiang; XIN Yu; ZHANG Jie; NING Zhao-Yuan
2009-01-01
By using optical emission spectroscopy (OES), N2 and N+2 vibrational temperatures in capacitively coupled plasma discharges with different exciting frequencies are investigated. The vibrational temperatures are acquired by comparing the measured and calculated spectra of selected transitions with a least-square procedure. It is found that 512 and N+2 vibrational temperatures almost increase linearly with increasing exciting frequency up to 23 MHz, then increase slowly or even decrease. The pressure corresponding to the maximum point of N2 vibrational temperature decreases with the increasing exciting frequency. These experimental phenomena are attributed to the increasing electron density, whereas the electron temperature decreases with exciting frequency rising.
Piezoelectric actuator models for active sound and vibration control of cylinders
Lester, Harold C.; Lefebvre, Sylvie
1993-01-01
Analytical models for piezoelectric actuators, adapted from flat plate concepts, are developed for noise and vibration control applications associated with vibrating circular cylinders. The loadings applied to the cylinder by the piezoelectric actuators for the bending and in-plane force models are approximated by line moment and line force distributions, respectively, acting on the perimeter of the actuator patch area. Coupling between the cylinder and interior acoustic cavity is examined by studying the modal spectra, particularly for the low-order cylinder modes that couple efficiently with the cavity at low frequencies. Within the scope of this study, the in-plane force model produced a more favorable distribution of low-order modes, necessary for efficient interior noise control, than did the bending model.
Directory of Open Access Journals (Sweden)
Zheng Min
2016-01-01
Full Text Available In this paper, numerical calculations of harmonic response with acoustic-vibration coupling of the combustion chamber under different combustion conditions has been performed by combining CFD and FEM methods. Temperature and sound pressure fields created by the flame in the combustion chamber are calculated first. And then the results of the CFD are exported to the FEM analysis for the interaction between acoustic waves and wall vibrations. The possible acoustic-vibration coupled eigenfrequencies at given combustion conditions are predicted by the harmonic response analysis.
Boissoles, J.; Boulet, C.; Robert, D.; Green, S.
1987-01-01
Line coupling coefficients resulting from rotational excitation of CO perturbed by He are computed within the infinite order sudden approximation (IOSA) and within the energy corrected sudden approximation (ECSA). The influence of this line coupling on the 1-0 CO-He vibration-rotation band shape is then computed for the case of weakly overlapping lines in the 292-78 K temperature range. The IOS and ECS results differ only at 78 K by a weak amount at high frequencies. Comparison with an additive superposition of Lorentzian lines shows strong modifications in the troughs between the lines. These calculated modifications are in excellent quantitative agreement with recent experimental data for all the temperatures considered. The applicability of previous approaches to CO-He system, based on either the strong collision model or exponential energy gap law, is also discussed.
Analytical model of internally coupled ears
DEFF Research Database (Denmark)
Vossen, Christine; Christensen-Dalsgaard, Jakob; Leo van Hemmen, J
2010-01-01
, data demonstrating an asymmetrical spatial pattern of membrane vibration. As the analytical calculations show, the internally coupled ears increase the directional response, appearing in large directional internal amplitude differences (iAD) and in large internal time differences (iTD). Numerical...... simulations of the eigenfunctions in an exemplary, realistically reconstructed mouth cavity further estimate the effects of its complex geometry....
Madsen, Niels K; Godtliebsen, Ian H; Christiansen, Ove
2017-04-07
Vibrational coupled-cluster (VCC) theory provides an accurate method for calculating vibrational spectra and properties of small to medium-sized molecules. Obtaining these properties requires the solution of the non-linear VCC equations which can in some cases be hard to converge depending on the molecule, the basis set, and the vibrational state in question. We present and compare a range of different algorithms for solving the VCC equations ranging from a full Newton-Raphson method to approximate quasi-Newton models using an array of different convergence-acceleration schemes. The convergence properties and computational cost of the algorithms are compared for the optimization of VCC states. This includes both simple ground-state problems and difficult excited states with strong non-linearities. Furthermore, the effects of using tensor-decomposed solution vectors and residuals are investigated and discussed. The results show that for standard ground-state calculations, the conjugate residual with optimal trial vectors algorithm has the shortest time-to-solution although the full Newton-Raphson method converges in fewer macro-iterations. Using decomposed tensors does not affect the observed convergence rates in our test calculations as long as the tensors are decomposed to sufficient accuracy.
Iskandarov, Ibrokhim; Gianturco, Francesco Antonio; Vera, Mario Hernandez; Wester, Roland; da Silva, Humberto; Dulieu, Olivier
2017-06-01
We present a detailed computational analysis for the interaction between the vibrating/rotating molecular ions H2 +, HD+, D2 + colliding with He atoms employed as buffer gas within ion trap experiments. The production and preparation of these molecular ions from their neutrals usually generate rovibrationally excited species which will therefore require internal energy cooling down to their ground vibrational levels for further experimental handling. In this work we describe the calculation of the full 3D interaction potentials and of the ionic vibrational levels needed to obtain the vibrational coupling potential matrix elements which are needed in the multichannel treatment of the rovibrationally inelastic collision dynamics. The general features of such coupling potential terms are discussed for their employment within a quantum dynamical modeling of the relaxation processes, as well as in connection with their dependence on the initial and final vibrational levels which are directly coupled by the present potentials. As a preliminary test of the potential effects on scattering observables, we perform calculations between H2 + and He atoms at the energies of an ion-trap by using either the rigid rotor (RR) approximation or the more accurate vibrationally averaged (VA) description for the v = 0 state of the target. Both schemes are described in detail in the present paper and the differences found in the scattering results are also analysed and discussed. We further present and briefly discuss some examples of state-to-state rovibrationally inelastic cross sections, involving the two lowest vibrational levels of the H2 + molecular target ion, as obtained from our time-independent multichannel quantum scattering code.
Yoshida, Ken; Matubayasi, Nobuyuki; Uosaki, Yasuhiro; Nakahara, Masaru
2013-04-07
The rotational couplings, which determine the infrared spectral line shape in the low-density supercritical water, were analyzed as functions of the density and the temperature by applying molecular dynamics simulation to a flexible water model, SPC∕Fw and by varying the moment of inertia of the water through substitution for the H atom in H2O by heavy hydrogen isotopes. The differences in the frequency and the relative intensity between the sharp center peak and the rotational broad side-bands were analyzed for the O-H, O-D, and O-T stretch spectra. The frequency differences between the sharp center peak and the rotational broad side-bands are linearly correlated with the inverse of the moment of inertia of the isotope-substituted water species. The intensity of the sharp peak is associated with the long-time component of the reorientational time correlation function for the stretching bond vector. At 400 °C, where a substantial amount of hydrogen bonds are dynamically persisting, an intensity decrease in the rotational broad side-bands was observed with increasing density from 0.01 to 0.40 g cm(-3), respectively, corresponding to 0.56 and 22.2 M (=mol dm(-3)), orders of magnitude higher than the ideal gas densities. This arises from the decrease in the correlation time of the angular velocity and the rotational couplings due to an increase in the hydrogen-bonding perturbation. The intensity decrease of the rotational side-bands with increasing density is more significant for the water isotopes with heavier hydrogens. At a high temperature of 1200 °C, the rotational side-bands at 0.01 to 0.05 g cm(-3) were more distinct than those at 400 °C, and even at a medium density of 0.40 g cm(-3) a significant signal broadening due to the rotational couplings was clearly observed because of the accelerated rotational momentum. The vibrational spectrum cannot be decomposed into definite chemical clusters for the thermodynamic and kinetic analysis because of the dynamic
Coupled flexural-torsional vibration band gap in periodic beam including warping effect
Institute of Scientific and Technical Information of China (English)
Fang Jian-Yu; Yu Dian-Long; Han Xiao-Yun; Cai Li
2009-01-01
The propagation of coupled flexural-torsional vibration in the periodic beam including warping effect is investigated with the transfer matrix theory.The band structures of the periodic beam,both including warping effect and ignoring warping effect,are obtained.The frequency response function of the finite periodic beams is simulated with finite element method,which shows large vibration attenuation in the frequency range of the gap as expected.The effect of warping stiffness on the band structure is studied and it is concluded that substantial error can be produced in high frequency range if the effect is ignored.The result including warping effect agrees quite well with the simulated result.
Directory of Open Access Journals (Sweden)
Runze Zhang
2016-01-01
Full Text Available This paper presents a free vibration analysis of three-dimensional coupled beams with arbitrary coupling angle using an improved Fourier method. The displacement and rotation of the coupled beams are represented by the improved Fourier series which consisted of Fourier cosine series and closed-form auxiliary functions. The coupling and boundary conditions are accomplished by setting coupling and boundary springs and assigning corresponding stiffness values to the springs. Modal parameters are determined through the application of Rayleigh-Ritz procedure to the system energy formulation. The accuracy and convergence of the present method are demonstrated by finite element method (FEM result. Investigation on vibration of the propulsion shafting structure shows the extensive applicability of present method. The studies on the vibration suppression devices are also reported.
Numerical modelling of rubber vibration isolators
Beijers, Clemens A.J.; Boer, de André; Nilsson, A.; Boden, H.
2003-01-01
An important cause for interior noise in vehicles is structure-borne sound from the engine. The vibrations of the source (engine) are transmitted to the receiver structure (the vehicle) causing interior noise in the vehicle. For this reason the engine is supported by rubber isolators for passive iso
Vibration Response of Multi Storey Building Using Finite Element Modelling
Chik, T. N. T.; Zakaria, M. F.; Remali, M. A.; Yusoff, N. A.
2016-07-01
Interaction between building, type of foundation and the geotechnical parameter of ground may trigger a significant effect on the building. In general, stiffer foundations resulted in higher natural frequencies of the building-soil system and higher input frequencies are often associated with other ground. Usually, vibrations transmitted to the buildings by ground borne are often noticeable and can be felt. It might affect the building and become worse if the vibration level is not controlled. UTHM building is prone to the ground borne vibration due to closed distance from the main road, and the construction activities adjacent to the buildings. This paper investigates the natural frequency and vibration mode of multi storey office building with the presence of foundation system and comparison between both systems. Finite element modelling (FEM) package software of LUSAS is used to perform the vibration analysis of the building. The building is modelled based on the original plan with the foundation system on the structure model. The FEM results indicated that the structure which modelled with rigid base have high natural frequency compare to the structure with foundation system. These maybe due to soil structure interaction and also the damping of the system which related to the amount of energy dissipated through the foundation soil. Thus, this paper suggested that modelling with soil is necessary to demonstrate the soil influence towards vibration response to the structure.
Fluid-structure coupling in the guide vanes cascade of a pump-turbine scale model
Energy Technology Data Exchange (ETDEWEB)
Roth, S; Hasmatuchi, V; Botero, F; Farhat, M; Avellan, F, E-mail: steven.roth@epfl.c [Laboratory for Hydraulic Machines, Ecole Polytechnique Federale de Lausanne Av. de Cour 33bis, Lausanne, 1007 (Switzerland)
2010-08-15
The present study concerns fluid-structure coupling phenomena occurring in a guide vane cascade of a pump-turbine scale model placed in the EPFL PF3 test rig. An advanced instrument set is used to monitor both vibrating structures and the surrounding flow. The paper highlights the interaction between vibrating guide vanes and the flow behavior. The pressure fluctuations in the stay vanes region are found to be strongly influenced by the amplitude of the vibrating guide vanes. Moreover, the flow induces different hydrodynamic damping on the vibrating guide vanes depending on the operating point of the pump-turbine.
El Aroudi, Abdelali
2014-05-01
Recently, nonlinearities have been shown to play an important role in increasing the extracted energy of vibration-based energy harvesting systems. In this paper, we study the dynamical behavior of a piecewise linear (PWL) spring-mass-damper system for vibration-based energy harvesting applications. First, we present a continuous time single degree of freedom PWL dynamical model of the system. Different configurations of the PWL model and their corresponding state-space regions are derived. Then, from this PWL model, extensive numerical simulations are carried out by computing time-domain waveforms, state-space trajectories and frequency responses under a deterministic harmonic excitation for different sets of system parameter values. Stability analysis is performed using Floquet theory combined with Filippov method, Poincaré map modeling and finite difference method (FDM). The Floquet multipliers are calculated using these three approaches and a good concordance is obtained among them. The performance of the system in terms of the harvested energy is studied by considering both purely harmonic excitation and a noisy vibrational source. A frequency-domain analysis shows that the harvested energy could be larger at low frequencies as compared to an equivalent linear system, in particular, for relatively low excitation intensities. This could be an advantage for potential use of this system in low frequency ambient vibrational-based energy harvesting applications. © 2014 World Scientific Publishing Company.
Coupled Boundary and Finite Element Analysis of Vibration from Railway Tunnels
DEFF Research Database (Denmark)
Andersen, Lars; Jones, C.J.C.
2006-01-01
The analysis of vibration from railway tunnels is of growing interest as new and higher-speed railways are built under the ground to address the transport problems of growing modern urban areas around cities. Such analysis can be carried out using numerical methods but models and therefore comput...
Research on vibration characteristics of gun barrel based on contact model
Zhao, Yang; Zhou, Qizheng; Yue, Pengfei
2017-04-01
In order to study vibration characteristics of the gun barrel under the action of moving projectile, the gun barrel is simplified to cross sectional cantilever beam such as Euler. Considering contact conditions of inertia effect and projectile with the gun barrel, the equation of lateral vibration of the gun barrel is established under the projectile-gun coupling effect; the modal analysis method is used to give the analytic solutions of equation series. The effect of the motion parameters the projectile on the vibration of gun barrel is discussed, and characteristics of vibration of gun barrel are further studied under two conditions of repeating and projectile with mass eccentricity. The research results show that reasonable control of the acceleration of the projectile in the gun bore, and reduction of projectile mass eccentricity can help reduce the muzzle vibration at the gun firing. The research results can provide reference for overall design of the gun, and the modeling and analysis method used in the paper can be promoted for the solution of vibration of other related projects under the moving excitation.
Modeling of Coupled Chaotic Oscillators
Energy Technology Data Exchange (ETDEWEB)
Lai, Y. [Departments of Physics and Astronomy and of Mathematics, University of Kansas, Lawrence, Kansas 66045 (United States); Grebogi, C. [Institute for Plasma Research, Department of Mathematics, Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States)
1999-06-01
Chaotic dynamics may impose severe limits to deterministic modeling by dynamical equations of natural systems. We give theoretical argument that severe modeling difficulties may occur for high-dimensional chaotic systems in the sense that no model is able to produce reasonably long solutions that are realized by nature. We make these ideas concrete by investigating systems of coupled chaotic oscillators. They arise in many situations of physical and biological interests, and they also arise from discretization of nonlinear partial differential equations. {copyright} {ital 1999} {ital The American Physical Society}
Stereovision vibration measurement test of a masonry building model
Shan, Baohua; Gao, Yunli; Shen, Yu
2016-04-01
To monitor 3D deformations of structural vibration response, a stereovision-based 3D deformation measurement method is proposed in paper. The world coordinate system is established on structural surface, and 3D displacement equations of structural vibration response are acquired through coordinate transformation. The algorithms of edge detection, center fitting and matching constraint are developed for circular target. A shaking table test of a masonry building model under Taft and El Centro earthquake at different acceleration peak is performed in lab, 3D displacement time histories of the model are acquired by the integrated stereovision measurement system. In-plane displacement curves obtained by two methods show good agreement, this suggests that the proposed method is reliable for monitoring structural vibration response. Out-of-plane displacement curves indicate that the proposed method is feasible and useful for monitoring 3D deformations of vibration response.
ELECTRICALLY FORCED THICKNESS-SHEAR VIBRATIONS OF QUARTZ PLATE WITH NONLINEAR COUPLING TO EXTENSION
Institute of Scientific and Technical Information of China (English)
Rongxing Wu; Jiashi Yang; Jianke Du; Ji Wang
2008-01-01
We study electrically forced nonlinear thickness-shear vibrations of a quartz plate resonator with relatively large amplitude. It is shown that thickness-shear is nonlinearly coupled to extension due to the well-known Poynting effect in nonlinear elasticity. This coupling is relatively strong when the resonant frequency of the extensional mode is about twice the resonant frequency of the thickness-shear mode. This happens when the plate length/thickness ratio assumes certain values. With this nonlinear coupling, the thickness-shear motion is no longer sinusoidal. Coupling to extension also affects energy trapping which is related to device mounting. When damping is 0.01, nonlinear coupling causes a frequency shift of the order of 10-e which is not insignificant,and an amplitude change of the order of 10-8. The effects are expected to be stronger under real damping of 10-5 or larger. To avoid nonlinear coupling to extension, certain values of the aspect ratio of the plate should be avoided.
Shim, Sugie
2016-01-01
Dirac coupled channel calculations are performed phenomenologically for the high-lying excited states that belong to the 2$^+$ gamma vibrational band at the 800-MeV polarized proton inelastic scatterings from the s-d shell nuclei, $^{24}$Mg and $^{26}$Mg. Optical potential model is used and scalar and time-like vector potentials are considered as direct potentials. First-order vibrational collective models are used to obtain the transition optical potentials in order to accommodate the high-lying excited vibrational collective states. The complicated Dirac coupled channel equations are solved phenomenologically to reproduce the differential cross section and analyzing power data by varying the optical potential and deformation parameters. It is found that the relativistic Dirac coupled channel calculation could describe the high-lying excited states of the 2$^+$ gamma vibrational band at the 800-MeV polarized proton inelastic scatterings from s-d shell nuclei $^{24}$Mg and $^{26}$Mg reasonably well, showing b...
Directory of Open Access Journals (Sweden)
M Pomarède
2016-09-01
Full Text Available Numerical simulation of Vortex-Induced-Vibrations (VIV of a rigid circular elastically-mounted cylinder submitted to a fluid cross-flow has been extensively studied over the past decades, both experimentally and numerically, because of its theoretical and practical interest for understanding Flow-Induced-Vibrations (FIV problems. In this context, the present article aims to expose a numerical study based on fully-coupled fluid-solid computations compared to previously published work [34], [36]. The computational procedure relies on a partitioned method ensuring the coupling between fluid and structure solvers. The fluid solver involves a moving mesh formulation for simulation of the fluid structure interface motion. Energy exchanges between fluid and solid models are ensured through convenient numerical schemes. The present study is devoted to a low Reynolds number configuration. Cylinder motion magnitude, hydrodynamic forces, oscillation frequency and fluid vortex shedding modes are investigated and the “lock-in” phenomenon is reproduced numerically. These numerical results are proposed for code validation purposes before investigating larger industrial applications such as configurations involving tube arrays under cross-flows [4].
Krishna Bhaskar, K.; Meera Saheb, K.
2015-12-01
A simple but accurate continuum solution for the shear flexible beam problem using the energy method involves in assuming suitable single term admissible functions for the lateral displacement and total rotation. This leads to two non-linear temporal differential equations in terms of the lateral displacement and the total rotation and are difficult, if not impossible, to solve to obtain the large amplitude fundamental frequencies of beams as a function of the amplitude and slenderness ratios of the vibrating beam. This situation can be avoided if one uses the concept of coupled displacement field where in the fields for lateral displacement and the total rotation are coupled through the static equilibrium equation. In this paper the lateral displacement field is assumed and the field for the total rotation is evaluated through the coupling equation. This approach leads to only one undetermined coefficient which can easily be used in the principle of conservation of total energy of the vibrating beam at a given time, neglecting damping. Finally, through a number of algebraic manipulations, one gets a nonlinear equation of Duffing type which can be solved using any standard method. To demonstrate the simplicity of the method discussed above the problem of large amplitude free vibrations of a uniform shear flexible hinged beam at higher modes with ends immovable to move axially has been solved. The numerical results obtained from the present formulation are in very good agreement with those obtained through finite element and other continuum methods for the fundamental mode, thus demonstrating the efficacy of the proposed method. Also some interesting observations are made with variation of frequency Vs amplitude at different modes.
Institute of Scientific and Technical Information of China (English)
Gu Yujiong; He Chengbing; Yang Kun; Zhang Jianqiang
2004-01-01
With the establishment of the nonlinear coupled lateral and torsion vibration equations of rub-impact Jeffcott rotor and through numerical simulations,the influences on lateral and torsion vibration behavior by rotor-to-stator clearance are analyzed,which prove that there is strong impact on coupled lateral and torsion vibration behavior.Smaller the clearance is,more complex the motion of rotor is.When the clearance is larger,the frequency spectrum of rub-impact rotor is mainly composed of 1/2X,1/3X and 1/4X components.With the decrease of clearance,quasi-periodic and chaotic motions will be present.Under different clearances,the bifurcation diagrams of lateral and torsion vibrations can be divided into rub-free zone,rub-light zone and three complex motion zones in which the motion trend of lateral vibration is similar to that of the torsion vibration.Compared with the lateral vibration,the torsion vibration is of more motion forms and more abundant frequency components in amplitude spectrum.
Directory of Open Access Journals (Sweden)
Robert GREGA
2014-12-01
Full Text Available In general, standard of ISO10816 is used for drives of transport mechanisms, determinating general criteria and principles for oscillations of machines. On the basis of evaluative criteria of the standard mentioned above, vibrations of a belt conveyer were measured. By experimental measurements it was found that vibrations of the belt conveyer evidently exceed limiting values defined by the standard. For an improvement of unacceptable state, a consequential solution was suggested. The application of pneumatic flexible coupling in drive of the belt conveyer was one of the possible solution. Consequential experimental measurements for verification of vibrations confirmed that application of pneumatic flexible coupling resulted in decrease of vibrations by 60%. Obtained values of vibrations were lower than limiting values of vibrations required by standard. We can clearly state that by proper application of pneumatic flexible coupling, a positive change in values of vibrations of the belt conveyer was reached, and therefore the belt conveyer meets the evaluating criteria according to the standard of ISO10816. This paper was written in the framework of Grant Project VEGA: „1/0688/12 – Research and application of universal regulation system in order to master the source of mechanical systems excitation”.
The Challenges to Coupling Dynamic Geospatial Models
Energy Technology Data Exchange (ETDEWEB)
Goldstein, N
2006-06-23
Many applications of modeling spatial dynamic systems focus on a single system and a single process, ignoring the geographic and systemic context of the processes being modeled. A solution to this problem is the coupled modeling of spatial dynamic systems. Coupled modeling is challenging for both technical reasons, as well as conceptual reasons. This paper explores the benefits and challenges to coupling or linking spatial dynamic models, from loose coupling, where information transfer between models is done by hand, to tight coupling, where two (or more) models are merged as one. To illustrate the challenges, a coupled model of Urbanization and Wildfire Risk is presented. This model, called Vesta, was applied to the Santa Barbara, California region (using real geospatial data), where Urbanization and Wildfires occur and recur, respectively. The preliminary results of the model coupling illustrate that coupled modeling can lead to insight into the consequences of processes acting on their own.
Nonlinear coupled rotor-fuselage helicopter vibration studies with higher harmonic control
Friedmann, P. P.; Venkatesan, C.; Papavassiliou, I.
1990-01-01
This paper addresses the problem of vibration prediction and vibration reduction in helicopters by means of active control methodologies. The nonlinear equations of a coupled rotor/flexible-fuselage system have been derived using computer algebra, thus relegating this tedious task to the computer. In the solution procedure the trim state and vibratory response of the helicopter are obtained in a single pass by using a harmonic balance technique and simultaneously satisfying the trim and the vibratory response of the helicopter in all the rotor and fuselage degrees of freedom. Using this solution procedure, the influence of the fuselage flexibility on the vibratory response is studied. In addition, it is shown that the conventional single frequency HHC is capable of reducing either the hub loads or only the fuselage vibrations but not both simultaneously. A new scheme called MHHC, having multiple higher harmonic pitch inputs, was used to accomplish this task of simultaneously reducing both the vibratory hub loads and fuselage vibratory response. In addition, the uniqueness of this MHHC scheme is explained in detail.
Grey forecasting model for active vibration control systems
Lihua, Zou; Suliang, Dai; Butterworth, John; Ma, Xing; Dong, Bo; Liu, Aiping
2009-05-01
Based on the grey theory, a GM(1,1) forecasting model and an optimal GM(1,1) forecasting model are developed and assessed for use in active vibration control systems for earthquake response mitigation. After deriving equations for forecasting the control state vector, design procedures for an optimal active control method are proposed. Features of the resulting vibration control and the influence on it of time-delay based on different sampling intervals of seismic ground motion are analysed. The numerical results show that the forecasting models based on the grey theory are reliable and practical in structural vibration control fields. Compared with the grey forecasting model, the optimal forecasting model is more efficient in reducing the influences of time-delay and disturbance errors.
Model independent control of lightly damped noise/vibration systems.
Yuan, Jing
2008-07-01
Feedforward control is a popular strategy of active noise/vibration control. In well-damped noise/vibration systems, path transfer functions from actuators to sensors can be modeled by finite impulse response (FIR) filters with negligible errors. It is possible to implement noninvasive model independent feedforward control by a recently proposed method called orthogonal adaptation. In lightly damped noise/vibration systems, however, path transfer functions have infinite impulse responses (IIRs) that cause difficulties in design and implementation of broadband feedforward controllers. A major source of difficulties is model error if IIR path transfer functions are approximated by FIR filters. In general, active control performance deteriorates as model error increases. In this study, a new method is proposed to design and implement model independent feedforward controllers for broadband in lightly damped noise/vibration systems. It is shown analytically that the proposed method is able to drive the convergence of a noninvasive model independent feedforward controller to improve broadband control in lightly damped noise/vibration systems. The controller is optimized in the minimum H2 norm sense. Experiment results are presented to verify the analytical results.
Mathematical modeling of mechanical vibration assisted conductivity imaging
Ammari, Habib; Kwon, Hyeuknam; Seo, Jin Keun; Woo, Eung Je
2014-01-01
This paper aims at mathematically modeling a new multi-physics conductivity imaging system incorporating mechanical vibrations simultaneously applied to an imaging object together with current injections. We perturb the internal conductivity distribution by applying time-harmonic mechanical vibrations on the boundary. This enhances the effects of any conductivity discontinuity on the induced internal current density distribution. Unlike other conductivity contrast enhancing frameworks, it does not require a prior knowledge of a reference data. In this paper, we provide a mathematical framework for this novel imaging modality. As an application of the vibration-assisted impedance imaging framework, we propose a new breast image reconstruction method in electrical impedance tomography (EIT). As its another application, we investigate a conductivity anomaly detection problem and provide an efficient location search algorithm. We show both analytically and numerically that the applied mechanical vibration increas...
Sharma, Surendra P.; Huo, Winifred M.; Park, Chul
1988-01-01
A theoretical study of vibrational excitations and dissociations of nitrogen undergoing a nonequilibrium relaxation process upon heating and cooling is reported. The rate coefficients for collisional induced vibrational transitions and transitions from a bound vibrational state into a dissociative state have been calculated using an extension of the theory originally proposed by Schwarz (SSH) et al. (1952). High-lying vibrational states and dissociative states were explicitly included but rotational energy transfer was neglected. The transition probabilities calculated from the SSH theory were fed into the master equation, which was integrated numerically to determine the population distribution of the vibrational states as well as bulk thermodynamic properties. The results show that: (1) the transition rates have a minimum near the middle of the bound vibrational levels, causing a bottleneck in the vibrational relaxation and dissociation rates; (2) high vibrational states are always in equilibrium with the dissociative state; (3) for the heating case, only the low vibrational states relax according to the Landau-Teller theory; (4) for the cooling case, vibrational relaxation cannot be described by a rate equation; (5) Park's (1985, 1988) two-temperature model is approximately valid; and (6) the average vibrational energy removed in dissociation is about 30 percent of the dissociation energy.
Exploiting vibrational strong coupling to make an optical parametric oscillator out of a Raman laser
del Pino, Javier; Feist, Johannes
2016-01-01
When the collective coupling of the rovibrational states in organic molecules and confined electromagnetic modes is sufficiently strong, the system enters into vibrational strong coupling, leading to the formation of hybrid light-matter quasiparticles. In this work we demonstrate theoretically how this hybridization in combination with stimulated Raman scattering can be utilized to widen the capabilities of Raman laser devices. We explore the conditions under which the lasing threshold can be diminished and the system can be transformed into an optical parametric oscillator. Finally, we show how the dramatic reduction of the many final molecular states into two collective excitations can be used to create an all-optical switch with output in the mid-infrared.
Exploiting Vibrational Strong Coupling to Make an Optical Parametric Oscillator Out of a Raman Laser
del Pino, Javier; Garcia-Vidal, Francisco J.; Feist, Johannes
2016-12-01
When the collective coupling of the rovibrational states in organic molecules and confined electromagnetic modes is sufficiently strong, the system enters into vibrational strong coupling, leading to the formation of hybrid light-matter quasiparticles. In this Letter, we demonstrate theoretically how this hybridization in combination with stimulated Raman scattering can be utilized to widen the capabilities of Raman laser devices. We explore the conditions under which the lasing threshold can be diminished and the system can be transformed into an optical parametric oscillator. Finally, we show how the dramatic reduction of the many final molecular states into two collective excitations can be used to create an all-optical switch with output in the midinfrared.
Lopes, Patrícia; Ruiz, Jésus Fernández; Alves Costa, Pedro; Medina Rodríguez, L; Cardoso, António Silva
2016-10-15
The present paper focuses on the experimental validation of a numerical approach previously proposed by the authors for the prediction of vibrations inside buildings due to railway traffic in tunnels. The numerical model is based on the concept of dynamic substructuring and is composed by three autonomous models to simulate the following main parts of the problem: i) generation of vibrations (train-track interaction); ii) propagation of vibrations (track-tunnel-ground system); iii) reception of vibrations (building coupled to the ground). The experimental validation consists in the comparison between the results predicted by the proposed numerical model and the measurements performed inside a building due to the railway traffic in a shallow tunnel located in Madrid. Apart from the brief description of the numerical model and of the case study, the main options and simplifications adopted on the numerical modeling strategy are discussed. The balance adopted between accuracy and simplicity of the numerical approach proved to be a path to follow in order to transfer knowledge to engineering practice. Finally, the comparison between numerical and experimental results allowed finding a good agreement between both, fact that ensures the ability of the proposed modeling strategy to deal with real engineering practical problems. Copyright © 2015 Elsevier B.V. All rights reserved.
Vibration analysis of concrete bridges during a train pass-by using various models
Li, Qi; Wang, Ke; Cheng, Shili; Li, Wuqian; Song, Xiaodong
2016-09-01
The vibration of a bridge must be determined in order to predict the bridge noise during a train pass-by. It can be generally solved with different models either in the time domain or the frequency domain. The computation cost and accuracy of these models vary a lot in a wide frequency band. This study aims to compare the results obtained from various models for recommending the most suitable model in further noise prediction. First, train-track-bridge models in the time domain are developed by using the finite element method and mode superposition method. The rails are modeled by Timoshenko beam elements and the bridge is respectively modeled by shell elements and volume elements. Second, power flow models for the coupled system are established in the frequency domain. The rails are modelled by infinite Timoshenko beams and the bridge is respectively represented by three finite element models, an infinite Kirchhoff plate, and an infinite Mindlin plate model. The vibration at given locations of the bridge and the power input to the bridges through the rail fasteners are calculated using these models. The results show that the shear deformation of the bridge deck has significant influences on the bridge vibration at medium-to-high frequencies. The Mindlin plate model can be used to represent the U-shaped girder to obtain the power input to the bridge with high accuracy and efficiency.
Modeling of the Archery Bow and Arrow Vibrations
Directory of Open Access Journals (Sweden)
I. Zaniewski
2009-01-01
Full Text Available Vibration processes in the compound and open kinematical chain with an external link, as a model of an archery bow and arrow system, are evaluated. A mechanical and mathematical model of bend oscillations of the system during accelerate motion of the external link is proposed. Correlation between longitudinal acceleration and natural frequencies is obtained. There are recommendations regarding determination of virtual forms to study arrow vibrations and buckling. The models and methods have been adapted for realization into the engineering method using well-known mathematical software packages.
The Modeling of Vibration Damping in SMA Wires
Energy Technology Data Exchange (ETDEWEB)
Reynolds, D R; Kloucek, P; Seidman, T I
2003-09-16
Through a mathematical and computational model of the physical behavior of shape memory alloy wires, this study shows that localized heating and cooling of such materials provides an effective means of damping vibrational energy. The thermally induced pseudo-elastic behavior of a shape memory wire is modeled using a continuum thermodynamic model and solved computationally as described by the authors in [23]. Computational experiments confirm that up to 80% of an initial shock of vibrational energy can be eliminated at the onset of a thermally-induced phase transformation through the use of spatially-distributed transformation regions along the length of a shape memory alloy wire.
Prediction Model for Vortex-Induced Vibration of Circular Cylinder with Data of Forced Vibration
Institute of Scientific and Technical Information of China (English)
PAN Zhi-yuan; CUI Wei-cheng; LIU Ying-zhong
2007-01-01
A model based on the data from forced vibration experiments is developed for predicting the vortex-induced vibrations (VIV) of elastically mounted circular cylinders in flow. The assumptions for free and forced vibration tests are explored briefly. Energy equilibrium is taken into account to set up the relationship between the dynamic response of self-excited oscillations and the force coefficients from forced vibration experiments. The gap between these two cases is bridged straightforwardly with careful treatment of key parameters. Given reduced mass m* and material damping ratio ζ of an elastically mounted circular cylinder in flow, the response characteristics such as amplitude, frequency, lock-in range, added mass coefficient, cross-flow fluid force and the corresponding phase angle can be predicted all at once. Instances with different combination of reduced mass and material damping ratio are compared to investigate their effects on VIV. The hysteresis phenomenon can be interpreted reasonably. The predictions and the results from recent experiments carried out by Williamson's group are in rather good agreement.
Non-classical method of modelling of vibrating mechatronic systems
Białas, K.; Buchacz, A.
2016-08-01
This work presents non-classical method of modelling of mechatronic systems by using polar graphs. The use of such a method enables the analysis and synthesis of mechatronic systems irrespective of the type and number of the elements of such a system. The method id connected with algebra of structural numbers. The purpose of this paper is also introduces synthesis of mechatronic system which is the reverse task of dynamics. The result of synthesis is obtaining system meeting the defined requirements. This approach is understood as design of mechatronic systems. The synthesis may also be applied to modify the already existing systems in order to achieve a desired result. The system was consisted from mechanical and electrical elements. Electrical elements were used as subsystem reducing unwanted vibration of mechanical system. The majority of vibration occurring in devices and machines is harmful and has a disadvantageous effect on their condition. Harmful impact of vibration is caused by the occurrence of increased stresses and the loss of energy, which results in faster wear machinery. Vibration, particularly low-frequency vibration, also has a negative influence on the human organism. For this reason many scientists in various research centres conduct research aimed at the reduction or total elimination of vibration.
Coupling constant in dispersive model
Indian Academy of Sciences (India)
R Saleh-Moghaddam; M E Zomorrodian
2013-11-01
The average of the moments for event shapes in + - → hadrons within the context of next-to-leading order (NLO) perturbative QCD prediction in dispersive model is studied. Moments used in this article are $\\langle 1 - T \\rangle, \\langle ρ \\rangle, \\langle B_{T} \\rangle$ and $\\langle B_{W} \\rangle$. We extract , the coupling constant in perturbative theory and α0 in the non-perturbative theory using the dispersive model. By fitting the experimental data, the values of $(M_{Z^{°}})$ = 0.1171 ± 0.00229 and 0 ($_{I} = 2{\\text{GeV}}$) = 0.5068 ± 0.0440 are found. Our results are consistent with the above model. Our results are also consistent with those obtained from other experiments at different energies. All these features are explained in this paper.
Influence of subglottic stenosis on the flow-induced vibration of a computational vocal fold model
Smith, Simeon L.; Thomson, Scott L.
2013-04-01
The effect of subglottic stenosis on vocal fold vibration is investigated. An idealized stenosis is defined, parameterized, and incorporated into a two-dimensional, fully coupled finite element model of the vocal folds and laryngeal airway. Flow-induced responses of the vocal fold model to varying severities of stenosis are compared. The model vibration was not appreciably affected by stenosis severities of up to 60% occlusion. Model vibration was altered by stenosis severities of 90% or greater, evidenced by decreased superior model displacement, glottal width amplitude, and flow rate amplitude. Predictions of vibration frequency and maximum flow declination rate were also altered by high stenosis severities. The observed changes became more pronounced with increasing stenosis severity and inlet pressure, and the trends correlated well with flow resistance calculations. Flow visualization was used to characterize subglottal flow patterns in the space between the stenosis and the vocal folds. Underlying mechanisms for the observed changes, possible implications for human voice production, and suggestions for future work are discussed.
Vibrational spectrum of CF4 isotopes in an algebraic model
Indian Academy of Sciences (India)
Joydeep Choudhury; Srinivasa Rao Karumuri; Nirmal Kumar Sarkar; Ramendu Bhattacharjee
2009-11-01
n this paper the stretching vibrational modes of CF4 isotopes are calculated up to first overtone using the one-dimensional vibron model for the first time. The model Hamiltonian so constructed seems to describe the C–F stretching modes accurately using a relatively small set of well-defined parameters.
A microscopic nuclear collective rotation-vibration model: 2D submodel
Gulshani, Parviz
2016-01-01
The previous microscopic collective rotation-vibration model is improved to include interaction between collective oscillations in a pair of spatial directions, and to remove many of the previous-model approximations. As in the previous model, the nuclear Schrodinger equation (instead of the Hamiltonian) is canonically transformed to obtain a Schrodinger equation for collective rotation and vibration of a nucleus coupled to an intrinsic motion, with the related constraints imposed on the wavefunction (rather than on the particle co-ordinates). The resulting equation is then effectively linearized into three self-consistent, time-reversal invariant, cranking-type equations using a variational method. The relation of the equations to the phenomenological hydrodynamic collective Bohr-Davydov-Faessler-Greiner model is discussed. To facilitate the solution of the equations and enhance physical insight, we consider in this article the collective oscillations in only two space directions. For harmonic oscillator mea...
Fuzzy Model-based Pitch Stabilization and Wing Vibration Suppression of Flexible Wing Aircraft.
Ayoubi, Mohammad A.; Swei, Sean Shan-Min; Nguyen, Nhan T.
2014-01-01
This paper presents a fuzzy nonlinear controller to regulate the longitudinal dynamics of an aircraft and suppress the bending and torsional vibrations of its flexible wings. The fuzzy controller utilizes full-state feedback with input constraint. First, the Takagi-Sugeno fuzzy linear model is developed which approximates the coupled aeroelastic aircraft model. Then, based on the fuzzy linear model, a fuzzy controller is developed to utilize a full-state feedback and stabilize the system while it satisfies the control input constraint. Linear matrix inequality (LMI) techniques are employed to solve the fuzzy control problem. Finally, the performance of the proposed controller is demonstrated on the NASA Generic Transport Model (GTM).
Directory of Open Access Journals (Sweden)
M. Li
2012-01-01
Full Text Available This paper proposes a mathematical model of the multirotor system with a flexible coupling on spring supports on Lagrange's approach, which has taken into account the effects of dynamic angular misalignment and mass unbalance. Then its nonlinear dynamic behaviors of the system are discussed based on the method of multiple scales and numerical technique, respectively. The results show that the responses of the system in lateral directions contain a similar component to that of the mass unbalanced system on both the vibrating frequency and amplitude and involve the typical nonlinear components such as the ones from some combined frequencies; the results also reveal that the numerical agreements on the above-mentioned methods are perfect for the transient responses.
Directory of Open Access Journals (Sweden)
Colò Gianluca
2016-01-01
Full Text Available In this contribution, we shall describe a formalism that goes beyond the simple time-dependent mean field and is based on particle-vibration coupling (PVC. Such a formalism has been developed with the idea of being self-consistent. It makes use of Skyrme effective forces, and has been used for several applications. We will focus on charge-exchange transitions, namely we will show that our model describes well both the Gamow-Teller giant resonance width, and the low-lying transitions associated with β-decay. In this latter case, including PVC produces a significant improvement of the half-lives obtained at mean-field level, and leads to a good agreement with experimental data. We will end by discussing particle-phonon multiplets in odd nuclei.
Mechanical model of carbon dioxide vibrational spectrum
Aldoshin, G. T.; Yakovlev, S. P.
2016-12-01
Classical dynamics methods have been used to study the nonlinear vibrations of a CO2 molecule. Consideration includes not only the anharmonicity valence angle, which enables one to explain the Fermi resonance, but also the physical nonlinearity of the force field (stiffness and softness of springs). In the farthest neighbor approximation (with regard to oxygen-oxygen interaction), a set of nonlinear differential equations in the Lagrangian form has been derived. Their analytical solution has been derived using the method of invariant normalization. The occurrence of a strange attractor has been discovered by numerical simulation. Recommendations for the selection of initial conditions are given that take into account the possibility of regular beatings that change into to chaotic beatings.
Neural Network Modeling of UH-60A Pilot Vibration
Kottapalli, Sesi
2003-01-01
Full-scale flight-test pilot floor vibration is modeled using neural networks and full-scale wind tunnel test data for low speed level flight conditions. Neural network connections between the wind tunnel test data and the tlxee flight test pilot vibration components (vertical, lateral, and longitudinal) are studied. Two full-scale UH-60A Black Hawk databases are used. The first database is the NASMArmy UH-60A Airloads Program flight test database. The second database is the UH-60A rotor-only wind tunnel database that was acquired in the NASA Ames SO- by 120- Foot Wind Tunnel with the Large Rotor Test Apparatus (LRTA). Using neural networks, the flight-test pilot vibration is modeled using the wind tunnel rotating system hub accelerations, and separately, using the hub loads. The results show that the wind tunnel rotating system hub accelerations and the operating parameters can represent the flight test pilot vibration. The six components of the wind tunnel N/rev balance-system hub loads and the operating parameters can also represent the flight test pilot vibration. The present neural network connections can significandy increase the value of wind tunnel testing.
Directory of Open Access Journals (Sweden)
XU, F.
2013-05-01
Full Text Available Orbital Friction Vibration Actuator (OFVA is a core component of Orbital Friction Welding (OFW, which is a novel apertureless welding technology utilizing friction heat to implement solid-state joining. In this paper, topology and operational principle of OFVA are introduced, the analytical formulas of the electromagnetic force for the x and y directions, which can drive the mover to generate a circular motion trajectory, are derived, and the characteristic of static electromagnetic force is predicted by analytical method and 2-D (two-dimensional FEM (finite element method, 3-D and measurement. The coupled magnetic field-circuit-motion simulation models which are driven by current and voltage source are established, respectively, and some of its operational characteristics are analyzed. Simulation and experiment validate theoretical analysis and the feasibility of the fabricated prototype, demonstrate the good performance of the OFVA, and provide valuable reference for engineering applications.
Pollard, Benjamin; Muller, Eric A; Hinrichs, Karsten; Raschke, Markus B
2014-04-11
Molecular self-assembly, the function of biomembranes and the performance of organic solar cells rely on nanoscale molecular interactions. Understanding and control of such materials have been impeded by difficulties in imaging their properties with the desired nanometre spatial resolution, attomolar sensitivity and intermolecular spectroscopic specificity. Here we implement vibrational scattering-scanning near-field optical microscopy with high spectral precision to investigate the structure-function relationship in nano-phase separated block copolymers. A vibrational resonance is used as a sensitive reporter of the local chemical environment and we image, with few nanometre spatial resolution and 0.2 cm(-1) spectral precision, solvatochromic Stark shifts and line broadening correlated with molecular-scale morphologies. We discriminate local variations in electric fields between nano-domains with quantitative agreement with dielectric continuum models. This ability to directly resolve nanoscale morphology and associated intermolecular interactions can form a basis for the systematic control of functionality in multicomponent soft matter systems.
Energy Technology Data Exchange (ETDEWEB)
Atabakhshian, V.; Shooshtari, A.; Karimi, M., E-mail: karimi_mh@yahoo.com
2015-01-01
In this study, nonlinear vibration and stability of a fluid-conveying nanotube (FCNT), elastically coupled to a smart piezoelectric polymeric beam (PPB) is investigated based on nonlocal elasticity theory, Euler–Bernoulli beam model and energy approach. In order to obtain an active instability control of FCNT, the PPB is longitudinally polarized as an actuator while in the absence of an imposed electric field it is also possible to be used as an alarm biosensor. Simulating the above smart coupled nanobeam system alike the double nanobeam systems (which are relatively developed by other authors) leads to obtain nonlinear differential equations of motion. The linear natural and damping frequencies are achieved by ignoring all the system nonlinearities which are then considered to obtain nonlinear frequencies using an iterative method. The effects of geometric nonlinearity, small scale parameter, coupled medium constants, Knudsen number, temperature change, aspect ratio and external applied voltage on critical flow velocity are studied in details. It is concluded that applying an electric voltage on PPB will increase the stability of FCNT. It is hoped that this research will provide a new approach to smart instability control of FCNTs which is no yet reported.
Atabakhshian, V.; Shooshtari, A.; Karimi, M.
2015-01-01
In this study, nonlinear vibration and stability of a fluid-conveying nanotube (FCNT), elastically coupled to a smart piezoelectric polymeric beam (PPB) is investigated based on nonlocal elasticity theory, Euler-Bernoulli beam model and energy approach. In order to obtain an active instability control of FCNT, the PPB is longitudinally polarized as an actuator while in the absence of an imposed electric field it is also possible to be used as an alarm biosensor. Simulating the above smart coupled nanobeam system alike the double nanobeam systems (which are relatively developed by other authors) leads to obtain nonlinear differential equations of motion. The linear natural and damping frequencies are achieved by ignoring all the system nonlinearities which are then considered to obtain nonlinear frequencies using an iterative method. The effects of geometric nonlinearity, small scale parameter, coupled medium constants, Knudsen number, temperature change, aspect ratio and external applied voltage on critical flow velocity are studied in details. It is concluded that applying an electric voltage on PPB will increase the stability of FCNT. It is hoped that this research will provide a new approach to smart instability control of FCNTs which is no yet reported.
Jacobs, M. H.; Van Den Berg, A. P.
2013-12-01
Thermodynamic databases are indispensable tools in materials science and mineral physics to derive thermodynamic properties in regions of pressure-temperature-composition space for which experimental data are not available or scant. Because the amount of phases and substances in a database is arbitrarily large, thermodynamic formalisms coupled to these databases are often kept as simple as possible to sustain computational efficiency. Although formalisms based on parameterizations of 1 bar thermodynamic data, commonly used in Calphad methodology, meet this requirement, physically unrealistic behavior in properties hamper the application in the pressure regime prevailing in the Earth's lower mantle. The application becomes especially cumbersome when they are applied to planetary mantles of massive super earth exoplanets or in the development of pressure scales, where Hugoniot data at extreme conditions are involved. Methods based on the Mie-Grüneisen-Debye formalism have the advantage that physically unrealistic behavior in thermodynamic properties is absent, but due to the simple construction of the vibrational density of states (VDoS), they lack engineering precision in the low-pressure regime, especially at 1 bar pressure, hampering application of databases incorporating such formalism to industrial processes. To obtain a method that is generally applicable in the complete stability range of a material, we developed a method based on an alternative use of Kieffer's lattice vibrational formalism. The method requires experimental data to constrain the model parameters and is therefore semi-empirical. It has the advantage that microscopic properties for substances, such as the VDoS, Grüneisen parameters and electronic and static lattice properties resulting from present-day ab-initio methods can be incorporated to constrain a thermodynamic analysis of experimental data. It produces results free from physically unrealistic behavior at high pressure and temperature
A Nonlinear Vortex Induced Vibration Model of Marine Risers
Institute of Scientific and Technical Information of China (English)
LIU Juan; HUANG Weiping
2013-01-01
With the exploitation of oil and gas in deep water,the traditional vortex induced vibration (VIV) theory is challenged by the unprecedented flexibility of risers.A nonlinear time-dependent VIV model is developed in this paper based on a VIV lift force model and the Morison equation.Both the inline vibration induced by the flow due to vortex shedding and the fluid-structure interaction in the transverse direction are included in the model.One of the characteristics of the model is the response-dependent lift force with nonlinear damping,which is different from other VIV models.The calculations show that the model can well describe the VIV of deepwater risers with the results agreeing with those calculated by other models.
Directory of Open Access Journals (Sweden)
Yanwei Guan
2016-04-01
Full Text Available In this paper, a new micromachined tuning fork gyroscope (TFG with an anchored diamond coupling mechanism is proposed while the mode ordering and the vibration sensitivity are also investigated. The sense-mode of the proposed TFG was optimized through use of an anchored diamond coupling spring, which enables the in-phase mode frequency to be 108.3% higher than the anti-phase one. The frequencies of the in- and anti-phase modes in the sense direction are 9799.6 Hz and 4705.3 Hz, respectively. The analytical solutions illustrate that the stiffness difference ratio of the in- and anti-phase modes is inversely proportional to the output induced by the vibration from the sense direction. Additionally, FEM simulations demonstrate that the stiffness difference ratio of the anchored diamond coupling TFG is 16.08 times larger than the direct coupling one while the vibration output is reduced by 94.1%. Consequently, the proposed new anchored diamond coupling TFG can structurally increase the stiffness difference ratio to improve the mode ordering and considerably reduce the vibration sensitivity without sacrificing the scale factor.
Guan, Yanwei; Gao, Shiqiao; Liu, Haipeng; Jin, Lei; Niu, Shaohua
2016-04-02
In this paper, a new micromachined tuning fork gyroscope (TFG) with an anchored diamond coupling mechanism is proposed while the mode ordering and the vibration sensitivity are also investigated. The sense-mode of the proposed TFG was optimized through use of an anchored diamond coupling spring, which enables the in-phase mode frequency to be 108.3% higher than the anti-phase one. The frequencies of the in- and anti-phase modes in the sense direction are 9799.6 Hz and 4705.3 Hz, respectively. The analytical solutions illustrate that the stiffness difference ratio of the in- and anti-phase modes is inversely proportional to the output induced by the vibration from the sense direction. Additionally, FEM simulations demonstrate that the stiffness difference ratio of the anchored diamond coupling TFG is 16.08 times larger than the direct coupling one while the vibration output is reduced by 94.1%. Consequently, the proposed new anchored diamond coupling TFG can structurally increase the stiffness difference ratio to improve the mode ordering and considerably reduce the vibration sensitivity without sacrificing the scale factor.
Hashemi, Seyed M.; Roach, Andrew
2011-12-01
The application of a Dynamic Finite Element (DFE) technique to the extensional-torsional free vibration analysis of nonuniform composite beams, in the absence of flexural coupling, is presented. The proposed method is a fusion of the Galerkin weighted residual formulation and the Dynamic Stiffness Matrix (DSM) method, where the basis functions of approximation space are assumed to be the closed form solutions of the differential equations governing uncoupled extensional and torsional vibrations of the beam. The use of resulting dynamic trigonometric interpolation (shape) functions leads to a frequency dependent stiffness matrix, representing both mass and stiffness properties of the beam element. Assembly of the element matrices and the application of the boundary conditions then leads to a frequency dependent nonlinear eigenproblem, which is solved to evaluate the system natural frequencies and modes. Two illustrative examples of uniform and tapered cantilevered, Circumferentially Uniform Stiffness ( CUS), hollow, composite beams are presented. The influence of ply fibre-angle on the natural frequencies is also studied. The correctness of the theory and the superiority of the proposed DFE over the contrasting DSM and conventional FEM methods are confirmed by the published results and numerical checks. The discussion of results is followed by some concluding remarks.
Modeling of cable vibration effects of cable-stayed bridges
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The analysis of dynamic responses of cable-stayed bridges subjected to wind and earthquake loads generallyconsiders only the motions of the bridge deck and pylons. The influence of the stay cable vibration on the responses of the bridgeis either ignored or considered by approximate procedures. The transverse vibration of the stay cables, which can be significant insome cases, are usually neglected in previous research. In the present study, a new three-node cable element has been developed tomodel the transverse motions of the cables. The interactions between the cable behavior and the other parts of the bridgesuperstructure are considered by the concept of dynamic stiffness. The nonlinear effect of the cable caused by its self-weight isincluded in the formulation. Numerical examples are presented to demonstrate the accuracy and efficiency of the proposed model.The impact of cable vibration behavior on the dynamic characteristics of cable-stayed bridges is discussed.
Institute of Scientific and Technical Information of China (English)
Ta Na; Qiu Jiajun; Cai Ganhua
2005-01-01
Zero mode natural frequency (ZMNF) is found during experiments. The ZMNF and vibrations resulted by it are studied. First, calculating method of the ZMNF excited by electromagnetic in vibrational system of coupled mechanics and electrics are given from the view of magnetic energy.Laws that the ZMNF varies with active power and exciting current are obtained and are verified by experiments. Then, coupled lateral and torsional vibration of rotor shaft system is studied by considering rest eccentricity, rotating eccentricity and swing eccentricity. Using Largrange-Maxwell equation when three phases are asymmetric derives differential equation of the coupled vibration. With energy method of nonlinear vibration, amplitude-frequency characteristics of resonance are studied when rotating speed of rotor equals to ZMNF. The results show that ZMNF will occur in turbine generators by the action of electromagnetic. Because ZMNF varies with electromagnetic parameters,resonance can occur when exciting frequency of the rotor speed is fixed whereas exciting current change. And also find that a generator is in the state of large amplitude in rated exciting current.
Modeling and vibration control of an active membrane mirror
Ruggiero, Eric J.; Inman, Daniel J.
2009-09-01
The future of space satellite technology lies in ultra-large mirrors and radar apertures for significant improvements in imaging and communication bandwidths. The availability of optical-quality membranes drives a parallel effort for structural models that can capture the dominant dynamics of large, ultra-flexible satellite payloads. Unfortunately, the inherent flexibility of membrane mirrors wreaks havoc with the payload's on-orbit stability and maneuverability. One possible means of controlling these undesirable dynamics is by embedding active piezoelectric ceramics near the boundary of the membrane mirror. In doing so, active feedback control can be used to eliminate detrimental vibration, perform static shape control, and evaluate the health of the structure. The overall motivation of the present work is to design a control system using distributed bimorph actuators to eliminate any detrimental vibration of the membrane mirror. As a basis for this study, a piezoceramic wafer was attached in a bimorph configuration near the boundary of a tensioned rectangular membrane sample. A finite element model of the system was developed to capture the relevant system dynamics from 0 to 300 Hz. The finite element model was compared against experimental results, and fair agreement found. Using the validated finite element models, structural control using linear quadratic regulator control techniques was then used to numerically demonstrate effective vibration control. Typical results show that less than 12 V of actuation voltage is required to eliminate detrimental vibration of the membrane samples in less than 15 ms. The functional gains of the active system are also derived and presented. These spatially descriptive control terms dictate favorable regions within the membrane domain for placing sensors and can be used as a design guideline for structural control applications. The results of the present work demonstrate that thin plate theory is an appropriate modeling
Coupled Boundary and Finite Element Analysis of Vibration from Railway Tunnels
DEFF Research Database (Denmark)
Andersen, Lars; Jones, C.J.C.
2006-01-01
The analysis of vibration from railway tunnels is of growing interest as new and higher-speed railways are built under the ground to address the transport problems of growing modern urban areas around cities. Such analysis can be carried out using numerical methods but models and therefore...... computing times can be large. There is a need to be able to apply very fast calculations that can be used in tunnel design and studies of environmental impacts. Taking advantage of the fact that tunnels often have a two-dimensional geometry in the sense that the cross section is constant along the tunnel...
Coupled Boundary and Finite Element Analysis of Vibration from Railway Tunnels
DEFF Research Database (Denmark)
Andersen, Lars; Jones, C. J. C.
2004-01-01
The analysis of vibration from railway tunnels is of growing interest as new and higher-speed railways are built under the ground to address the transport problems of growing modern urban areas around cities. Such analysis can be carried out using numerical methods but models and therefore...... computing times can be large. There is a need to be able to apply very fast calculations that can be used in tunnel design and studies of environmental impacts. Taking advantage of the fact that tunnels often have a two-dimensional geometry in the sense that the cross section is constant along the tunnel...
Dynamics modeling and vibration analysis of a piezoelectric diaphragm applied in valveless micropump
He, Xiuhua; Xu, Wei; Lin, Nan; Uzoejinwa, B. B.; Deng, Zhidan
2017-09-01
This paper presents the dynamical model involved with load of fluid pressure, electric-solid coupling simulation and experimental performance of the piezoelectric diaphragm fabricated and applied in valveless micropump. The model is based on the theory of plate-shell with small deflection, considering the two-layer structure of piezoelectric ceramic and elastic substrate. The high-order non-homogeneous vibration equation of the piezoelectric diaphragm, derived in the course of the study, was solved by being divided into a homogeneous Bessel equation and a non-homogeneous static equation according to the superposition principle. The amplitude of the piezoelectric diaphragm driven by sinusoidal voltage against the load of fluid pressure was obtained from the solution of the vibration equation. Also, finite element simulation of electric-solid coupling between displacement of piezoelectric diaphragm due to an applied voltage and resulting deformation of membrane was considered. The simulation result showed that the maximum deflection of diaphragm is 9.51 μm at a quarter cycle time when applied a peak-to-peak voltage of 150VP-P with a frequency of 90 Hz, and the displacement distribution according to the direction of the radius was demonstrated. Experiments were performed to verify the prediction of the dynamic modeling and the coupling simulation, the experimental data showed a good agreement with the dynamical model and simulation.
Nonlinear dynamic modeling and resonance tuning of Galfenol vibration absorbers
Scheidler, Justin J.; Dapino, Marcelo J.
2013-08-01
This paper investigates the semi-active control of a magnetically-tunable vibration absorber’s resonance frequency. The vibration absorber that is considered is a metal-matrix composite containing the magnetostrictive material Galfenol (FeGa). A single degree of freedom model for the nonlinear vibration of the absorber is presented. The model is valid under arbitrary stress and magnetic field, and incorporates the variation in Galfenol’s elastic modulus throughout the composite as well as Galfenol’s asymmetric tension-compression behavior. Two boundary conditions—cantilevered and clamped-clamped—are imposed on the composite. The frequency response of the absorber to harmonic base excitation is calculated as a function of the operating conditions to determine the composite’s capacity for resonance tuning. The results show that nearly uniform controllability of the vibration absorber’s resonance frequency is possible below a threshold of the input power amplitude using weak magnetic fields of 0-8 kA m-1. Parametric studies are presented to characterize the effect on resonance tunability of Galfenol volume fraction and Galfenol location within the composite. The applicability of the results to composites of varying geometry and containing different Galfenol materials is discussed.
A multilingual programming model for coupled systems.
Energy Technology Data Exchange (ETDEWEB)
Ong, E. T.; Larson, J. W.; Norris, B.; Tobis, M.; Steder, M.; Jacob, R. L.; Mathematics and Computer Science; Univ. of Wisconsin; Univ. of Chicago; The Australian National Univ.
2008-01-01
Multiphysics and multiscale simulation systems share a common software requirement-infrastructure to implement data exchanges between their constituent parts-often called the coupling problem. On distributed-memory parallel platforms, the coupling problem is complicated by the need to describe, transfer, and transform distributed data, known as the parallel coupling problem. Parallel coupling is emerging as a new grand challenge in computational science as scientists attempt to build multiscale and multiphysics systems on parallel platforms. An additional coupling problem in these systems is language interoperability between their constituent codes. We have created a multilingual parallel coupling programming model based on a successful open-source parallel coupling library, the Model Coupling Toolkit (MCT). This programming model's capabilities reach beyond MCT's native Fortran implementation to include bindings for the C++ and Python programming languages. We describe the method used to generate the interlanguage bindings. This approach enables an object-based programming model for implementing parallel couplings in non-Fortran coupled systems and in systems with language heterogeneity. We describe the C++ and Python versions of the MCT programming model and provide short examples. We report preliminary performance results for the MCT interpolation benchmark. We describe a major Python application that uses the MCT Python bindings, a Python implementation of the control and coupling infrastructure for the community climate system model. We conclude with a discussion of the significance of this work to productivity computing in multidisciplinary computational science.
Sukegawa, Junpei; Schubert, Christina; Zhu, Xiaozhang; Tsuji, Hayato; Guldi, Dirk M; Nakamura, Eiichi
2014-10-01
Electron transfer (ET) is a fundamental process in a wide range of biological systems, photovoltaics and molecular electronics. Therefore to understand the relationship between molecular structure and ET properties is of prime importance. For this purpose, photoinduced ET has been studied extensively using donor-bridge-acceptor molecules, in which π-conjugated molecular wires are employed as bridges. Here, we demonstrate that carbon-bridged oligo-p-phenylenevinylene (COPV), which is both rigid and flat, shows an 840-fold increase in the ET rate compared with the equivalent flexible molecular bridges. A 120-fold rate enhancement is explained in terms of enhanced electronic coupling between the electron donor and the electron acceptor because of effective conjugation through the COPVs. The remainder of the rate enhancement is explained by inelastic electron tunnelling through COPV caused by electron-vibration coupling, unprecedented for organic molecular wires in solution at room temperature. This type of nonlinear effect demonstrates the versatility and potential practical utility of COPVs in molecular device applications.
Giant electromechanical coupling of relaxor ferroelectrics controlled by polar nanoregion vibrations
Manley, Michael E.; Abernathy, Douglas L.; Sahul, Raffi; Parshall, Daniel E.; Lynn, Jeffrey W.; Christianson, Andrew D.; Stonaha, Paul J.; Specht, Eliot D.; Budai, John D.
2016-01-01
Relaxor-based ferroelectrics are prized for their giant electromechanical coupling and have revolutionized sensor and ultrasound applications. A long-standing challenge for piezoelectric materials has been to understand how these ultrahigh electromechanical responses occur when the polar atomic displacements underlying the response are partially broken into polar nanoregions (PNRs) in relaxor-based ferroelectrics. Given the complex inhomogeneous nanostructure of these materials, it has generally been assumed that this enhanced response must involve complicated interactions. By using neutron scattering measurements of lattice dynamics and local structure, we show that the vibrational modes of the PNRs enable giant coupling by softening the underlying macrodomain polarization rotations in relaxor-based ferroelectric PMN-xPT {(1 − x)[Pb(Mg1/3Nb2/3)O3] – xPbTiO3} (x = 30%). The mechanism involves the collective motion of the PNRs with transverse acoustic phonons and results in two hybrid modes, one softer and one stiffer than the bare acoustic phonon. The softer mode is the origin of macroscopic shear softening. Furthermore, a PNR mode and a component of the local structure align in an electric field; this further enhances shear softening, revealing a way to tune the ultrahigh piezoelectric response by engineering elastic shear softening. PMID:27652338
Some results from 1/8-scale Shuttle model vibration studies
Pinson, L. D.; Leadbetter, S. A.
1978-01-01
Highlights of experimental and analytical vibration studies of a 1/8-scale structural dynamic model of the Space Shuttle are presented. The Space Shuttle is a launch vehicle with elements assembled in an asymmetric manner. Responses of the assembled vehicle are characterized by directional coupling and high modal density at low frequencies. Effects of distortion of structure near element interfaces are shown to be significant and predictable with highly detailed mathematical models. Acquisition of modal data by single-point random excitation is shown to be viable for these complex structures. Element studies reveal large liquid-structure interactions and a wide range of structural damping.
Energy Technology Data Exchange (ETDEWEB)
Monahan, Daniele M.; Whaley-Mayda, Lukas; Fleming, Graham R., E-mail: grfleming@lbl.gov [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720 (United States); Ishizaki, Akihito [Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585 (Japan)
2015-08-14
Coherence oscillations measured in two-dimensional (2D) electronic spectra of pigment-protein complexes may have electronic, vibrational, or mixed-character vibronic origins, which depend on the degree of electronic-vibrational mixing. Oscillations from intrapigment vibrations can obscure the inter-site coherence lifetime of interest in elucidating the mechanisms of energy transfer in photosynthetic light-harvesting. Huang-Rhys factors (S) for low-frequency vibrations in Chlorophyll and Bacteriochlorophyll are quite small (S ≤ 0.05), so it is often assumed that these vibrations influence neither 2D spectra nor inter-site coherence dynamics. In this work, we explore the influence of S within this range on the oscillatory signatures in simulated 2D spectra of a pigment heterodimer. To visualize the inter-site coherence dynamics underlying the 2D spectra, we introduce a formalism which we call the “site-probe response.” By comparing the calculated 2D spectra with the site-probe response, we show that an on-resonance vibration with Huang-Rhys factor as small as S = 0.005 and the most strongly coupled off-resonance vibrations (S = 0.05) give rise to long-lived, purely vibrational coherences at 77 K. We moreover calculate the correlation between optical pump interactions and subsequent entanglement between sites, as measured by the concurrence. At 77 K, greater long-lived inter-site coherence and entanglement appear with increasing S. This dependence all but vanishes at physiological temperature, as environmentally induced fluctuations destroy the vibronic mixing.
Transition densities in the context of the generalized rotation-vibration model
Morales Botero, D. F.; Chamon, L. C.; Carlson, B. V.
2017-10-01
A collective model for the description of heavy-ion nuclear structure, called the generalized rotation-vibration model (GRVM), was proposed in an earlier paper. In the present work, we use this model to study transition densities for the low-lying states of several nuclei. In order to evaluate the accuracy of the model, we test the GRVM transition densities in the description of experimental results corresponding to elastic and inelastic electron-nucleus scattering. We also compare the GRVM densities with those arising from microscopic Dirac-Hartree-Bogoliubov theoretical calculations. The GRVM transition densities can be used in future works to calculate folding-type coupling potentials in coupled-channel data analyses for heavy-ion systems.
Institute of Scientific and Technical Information of China (English)
李典灿
2013-01-01
To study boom system harmonic vibration of the concrete pump truck caused by the periodical load and frictional force in the delivery pipe, a virtual prototype model of rigid-flexible coupling body of actual pump truck boom system was created to simulate harmonic vibration analysis. First, the file of modal neutral file is created in the software Ansys; then, the file is imported into the software ADAMS. The simulation result shows that one order modal frequency of boom system is 0.71 Hz. In X direction and Y direction, displacement amplitude of frequency response is the maximal. Two order modal frequency of boom system is 0. 89 Hz, and vibration displacement and acceleration in Z direction of two order modal frequency is maximal.%主要研究了混凝土泵车输送管在周期性载荷作用下造成泵车臂架系统的谐响应振动问题.采用刚-柔耦合模型理论对某型号的泵车臂架系统创建虚拟样机模型,首先在Ansys中生成模态中性文件,然后将该文件导入ADAMS软件生成刚-柔耦合虚拟模型并进行谐响应动力学仿真分析.仿真分析结果表明臂架系统的1阶模态振动频率为0.71Hz,在X和Y方向上,1阶模态的位移频率响应幅值最大；臂架系统的2阶模态振动频率为0.89 Hz.臂架系统的2阶模态Z方向的振动位移和加速度同时达到最大.
Meng, Qingyong; Meyer, Hans-Dieter
2015-10-28
Molecular-surface studies are often done by assuming a corrugated, static (i.e., rigid) surface. To be able to investigate the effects that vibrations of surface atoms may have on spectra and cross sections, an expansion Hamiltonian model is proposed on the basis of the recently reported [R. Marquardt et al., J. Chem. Phys. 132, 074108 (2010)] SAP potential energy surface (PES), which was built for the CO/Cu(100) system with a rigid surface. In contrast to other molecule-surface coupling models, such as the modified surface oscillator model, the coupling between the adsorbed molecule and the surface atoms is already included in the present expansion SAP-PES model, in which a Taylor expansion around the equilibrium positions of the surface atoms is performed. To test the quality of the Taylor expansion, a direct model, that is avoiding the expansion, is also studied. The latter, however, requests that there is only one movable surface atom included. On the basis of the present expansion and direct models, the effects of a moving top copper atom (the one to which CO is bound) on the energy levels of a bound CO/Cu(100) system are studied. For this purpose, the multiconfiguration time-dependent Hartree calculations are carried out to obtain the vibrational fundamentals and overtones of the CO/Cu(100) system including a movable top copper atom. In order to interpret the results, a simple model consisting of two coupled harmonic oscillators is introduced. From these calculations, the vibrational levels of the CO/Cu(100) system as function of the frequency of the top copper atom are discussed.
Energy Technology Data Exchange (ETDEWEB)
Meng, Qingyong, E-mail: mengqingyong@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, 116023 Dalian (China); Meyer, Hans-Dieter, E-mail: hans-dieter.meyer@pci.uni-heidelberg.de [Theoretische Chemie, Physikalisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)
2015-10-28
Molecular-surface studies are often done by assuming a corrugated, static (i.e., rigid) surface. To be able to investigate the effects that vibrations of surface atoms may have on spectra and cross sections, an expansion Hamiltonian model is proposed on the basis of the recently reported [R. Marquardt et al., J. Chem. Phys. 132, 074108 (2010)] SAP potential energy surface (PES), which was built for the CO/Cu(100) system with a rigid surface. In contrast to other molecule-surface coupling models, such as the modified surface oscillator model, the coupling between the adsorbed molecule and the surface atoms is already included in the present expansion SAP-PES model, in which a Taylor expansion around the equilibrium positions of the surface atoms is performed. To test the quality of the Taylor expansion, a direct model, that is avoiding the expansion, is also studied. The latter, however, requests that there is only one movable surface atom included. On the basis of the present expansion and direct models, the effects of a moving top copper atom (the one to which CO is bound) on the energy levels of a bound CO/Cu(100) system are studied. For this purpose, the multiconfiguration time-dependent Hartree calculations are carried out to obtain the vibrational fundamentals and overtones of the CO/Cu(100) system including a movable top copper atom. In order to interpret the results, a simple model consisting of two coupled harmonic oscillators is introduced. From these calculations, the vibrational levels of the CO/Cu(100) system as function of the frequency of the top copper atom are discussed.
Plenio, M B; Huelga, S F
2013-01-01
We demonstrate that the coupling of excitonic and vibrational motion in biological complexes can provide mechanisms to explain the long-lived oscillations that have been obtained in non linear spectroscopic signals of different photosynthetic pigment protein complexes and we discuss the contributions of excitonic versus purely vibrational components to these oscillatory features. Considering a dimer model coupled to a structured spectral density we exemplify the fundamental aspects of the electron-phonon dynamics, and by analyzing separately the different contributions to the non linear signal, we show that for realistic parameter regimes purely electronic coherence is of the same order as purely vibrational coherence in the electronic ground state. Moreover, we demonstrate how the latter relies upon the excitonic interaction to manifest. These results link recently proposed microscopic, non-equilibrium mechanisms to support long lived coherence at ambient temperatures with actual experimental observations of...
Alijah, Alexander
2015-01-01
Vibrational energies and wave functions of the triplet state of the H3+ ion have been determined. In the calculations, the ground and first excited triplet electronic states are included as well as the non-Born-Oppenheimer coupling between them. A diabatization procedure transforming the two adiabatic ab initio potential energy surfaces of the triplet-H3+ state into a 2x2 matrix is employed. The diabatization takes into account the non-Born-Oppenheimer coupling and the effect of the geometrical phase due to the conical intersection between the two adiabatic potential surfaces. The results are compared to the calculation involving only the lowest adiabatic potential energy surface of the triplet-H3+ ion and neglecting the geometrical phase. The energy difference between results with and without the non-adiabatic coupling and the geometrical phase is about a wave number for the lowest vibrational levels.
Directory of Open Access Journals (Sweden)
Lianchao Sheng
2017-01-01
Full Text Available Due to the complexity of the dynamic model of a planar 3-RRR flexible parallel manipulator (FPM, it is often difficult to achieve active vibration control algorithm based on the system dynamic model. To establish a simple and efficient dynamic model of the planar 3-RRR FPM to study its dynamic characteristics and build a controller conveniently, firstly, considering the effect of rigid-flexible coupling and the moment of inertia at the end of the flexible intermediate link, the modal function is determined with the pinned-free boundary condition. Then, considering the main vibration modes of the system, a high-efficiency coupling dynamic model is established on the basis of guaranteeing the model control accuracy. According to the model, the modal characteristics of the flexible intermediate link are analyzed and compared with the modal test results. The results show that the model can effectively reflect the main vibration modes of the planar 3-RRR FPM; in addition the model can be used to analyze the effects of inertial and coupling forces on the dynamics model and the drive torque of the drive motor. Because this model is of the less dynamic parameters, it is convenient to carry out the control program.
Koroma, S. G.; Thompson, D. J.; Hussein, M. F. M.; Ntotsios, E.
2017-07-01
This paper presents a methodology for studying ground vibration in which the railway track is modelled in the space-time domain using the finite element method (FEM) and, for faster computation, discretisation of the ground using either FEM or the boundary element method (BEM) is avoided by modelling it in the wavenumber-frequency domain. The railway track is coupled to the ground through a series of rectangular strips located at the surface of the ground; their vertical interaction is described by a frequency-dependent dynamic stiffness matrix whose elements are represented by discrete lumped parameter models. The effectiveness of this approach is assessed firstly through frequency domain analysis using as excitation a stationary harmonic load applied on the rail. The interaction forces at the ballast/ground interface are calculated using the FE track model in the space-time domain, transformed to the wavenumber domain, and used as input to the ground model for calculating vibration in the free field. Additionally, time domain simulations are also performed with the inclusion of nonlinear track parameters. Results are presented for the coupled track/ground model in terms of time histories and frequency spectra for the track vibration, interaction forces and free-field ground vibration. For the linear track model, the results from the mixed formulation are in excellent agreement with those from a semi-analytical model formulated in the wavenumber-frequency domain, particularly in the vicinity of the loading point. The accuracy of the mixed formulation away from the excitation point depends strongly on the inclusion of through-ground coupling in the lumped parameter model, which has been found to be necessary for both track dynamics and ground vibration predictions.
Optimal vibration control of curved beams using distributed parameter models
Liu, Fushou; Jin, Dongping; Wen, Hao
2016-12-01
The design of linear quadratic optimal controller using spectral factorization method is studied for vibration suppression of curved beam structures modeled as distributed parameter models. The equations of motion for active control of the in-plane vibration of a curved beam are developed firstly considering its shear deformation and rotary inertia, and then the state space model of the curved beam is established directly using the partial differential equations of motion. The functional gains for the distributed parameter model of curved beam are calculated by extending the spectral factorization method. Moreover, the response of the closed-loop control system is derived explicitly in frequency domain. Finally, the suppression of the vibration at the free end of a cantilevered curved beam by point control moment is studied through numerical case studies, in which the benefit of the presented method is shown by comparison with a constant gain velocity feedback control law, and the performance of the presented method on avoidance of control spillover is demonstrated.
Vibration analysis with MADYMO human models
Verver, M.M.; Hoof, J.F.A.M. van
2002-01-01
The importance of comfort for the automotive industry is increasing. Car manufacturers use comfort to distinguish their products from their competitors. However, the development and design of a new car seat or interior is very time consuming and expensive. The introduction of computer models of huma
An Improved Lumped Parameter Model for a Piezoelectric Energy Harvester in Transverse Vibration
Directory of Open Access Journals (Sweden)
Guang-qing Wang
2014-01-01
Full Text Available An improved lumped parameter model (ILPM is proposed which predicts the output characteristics of a piezoelectric vibration energy harvester (PVEH. A correction factor is derived for improving the precisions of lumped parameter models for transverse vibration, by considering the dynamic mode shape and the strain distribution of the PVEH. For a tip mass, variations of the correction factor with PVEH length are presented with curve fitting from numerical solutions. The improved governing motion equations and exact analytical solution of the PVEH excited by persistent base motions are developed. Steady-state electrical and mechanical response expressions are derived for arbitrary frequency excitations. Effects of the structural parameters on the electromechanical outputs of the PVEH and important characteristics of the PVEH, such as short-circuit and open-circuit behaviors, are analyzed numerically in detail. Accuracy of the output performances of the ILPM is identified from the available lumped parameter models and the coupled distributed parameter model. Good agreement is found between the analytical results of the ILPM and the coupled distributed parameter model. The results demonstrate the feasibility of the ILPM as a simple and effective means for enhancing the predictions of the PVEH.
A semi-analytical beam model for the vibration of railway tracks
Kostovasilis, D.; Thompson, D. J.; Hussein, M. F. M.
2017-04-01
The high frequency dynamic behaviour of railway tracks, in both vertical and lateral directions, strongly affects the generation of rolling noise as well as other phenomena such as rail corrugation. An improved semi-analytical model of a beam on an elastic foundation is introduced that accounts for the coupling of the vertical and lateral vibration. The model includes the effects of cross-section asymmetry, shear deformation, rotational inertia and restrained warping. Consideration is given to the fact that the loads at the rail head, as well as those exerted by the railpads at the rail foot, may not act through the centroid of the section. The response is evaluated for a harmonic load and the solution is obtained in the wavenumber domain. Results are presented as dispersion curves for free and supported rails and are validated with the aid of a Finite Element (FE) and a waveguide finite element (WFE) model. Closed form expressions are derived for the forced response, and validated against the WFE model. Track mobilities and decay rates are presented to assess the potential implications for rolling noise and the influence of the various sources of vertical-lateral coupling. Comparison is also made with measured data. Overall, the model presented performs very well, especially for the lateral vibration, although it does not contain the high frequency cross-section deformation modes. The most significant effects on the response are shown to be the inclusion of torsion and foundation eccentricity, which mainly affect the lateral response.
Generalized coupling in the Kuramoto model
DEFF Research Database (Denmark)
Filatrella, G.; Pedersen, Niels Falsig; Wiesenfeld, K.
2007-01-01
We propose a modification of the Kuramoto model to account for the effective change in the coupling constant among the oscillators, as suggested by some experiments on Josephson junction, laser arrays, and mechanical systems, where the active elements are turned on one by one. The resulting model...... with the behavior of Josephson junctions coupled via a cavity....
Spin-orbit coupling mechanism of singlet oxygen a1Δg quenching by solvent vibrations
Minaev, B. F.
2017-02-01
Degenerate character of the O2(a1Δg) state and of the charge-transfer configurations (CTCs) from solvent to the oxygen open-shell orbitals explains the enhancement of spin-orbit coupling (SOC) which is necessary to overcome spin prohibition during singlet oxygen a1Δg quenching. The former mechanism of non-radiative transition O2(a1Δg) → O2(X3 Σg-) based on electronic energy transfer to the solvent vibrational levels (e-v mechanism) is supplemented here by explicit analysis of SOC effects mediated by solvent and O2 vibrations. The SOC matrix element between one component of the initial electronic excited singlet a1Δg state and the final ground triplet X3 Σg- state in the oxygen moiety is not equal to zero (as in free O2) in the collision complex with solvent molecule (M) when all possible CTCs of the type O2- …M+ are accounted for. Intermolecular configuration interaction between CTC and locally excited states obeys a simple symmetry selection rule which provides finally the SOC matrix element with a guarantee of large orbital rotation around the molecular oxygen axis creating a torque. The CTCs admixtures into the singlet and triplet wave functions in the collision complex O2…M ensure the SOC enhancement inside the O2 moiety and let the spin-prohibited singlet oxygen a1Δg quenching to become effectively allowed in terms of e-v mechanism. In the new model the solvent is not only a passive "sink" for the singlet oxygen excitation energy but serves as an active perturber of the oxygen open shell and finally - of the whole spin dynamics in the collision system.
Convectively coupled Kelvin waves in CMIP5 coupled climate models
Wang, Lu; Li, Tim
2016-04-01
This study provided a quantitative evaluation of convectively coupled Kelvin waves (CCKWs) over the Indian Ocean and the Pacific Ocean simulated by 20 coupled climate models that participated in Coupled Model Intercomparison Project phase 5. The two leading empirical orthogonal function (EOF) modes of filtered daily precipitation anomalies are used to represent the eastward propagating CCKWs in both observations and simulations. The eigenvectors and eigenvalues of the EOF modes represent the spatial patterns and intensity of CCKWs respectively, and the lead-lag relationship between the two EOF principle components describe the phase propagation of CCKWs. A non-dimensional metric was designed in consideration of all the three factors (i.e., pattern, amplitude and phase propagation) for evaluation. The relative rankings of the models based on the skill scores calculated by the metric are conducted for the Indian Ocean and the Pacific Ocean, respectively. Two models (NorESM1-M and MPI-ESM-LR) are ranked among the best 20 % for both the regions. Three models (inmcm4, MRI-CGCM3 and HadGEM2-ES) are ranked among the worst 20 % for both the regions. While the observed CCKW amplitude is greater north of the equator in the Pacific, some models overestimate the CCKW ampliutde in the Southern Hemisphere. This bias is related to the mean state precipitation bias along the south Pacific convergence zone.
Convectively coupled Kelvin waves in CMIP5 coupled climate models
Wang, Lu; Li, Tim
2017-02-01
This study provided a quantitative evaluation of convectively coupled Kelvin waves (CCKWs) over the Indian Ocean and the Pacific Ocean simulated by 20 coupled climate models that participated in Coupled Model Intercomparison Project phase 5. The two leading empirical orthogonal function (EOF) modes of filtered daily precipitation anomalies are used to represent the eastward propagating CCKWs in both observations and simulations. The eigenvectors and eigenvalues of the EOF modes represent the spatial patterns and intensity of CCKWs respectively, and the lead-lag relationship between the two EOF principle components describe the phase propagation of CCKWs. A non-dimensional metric was designed in consideration of all the three factors (i.e., pattern, amplitude and phase propagation) for evaluation. The relative rankings of the models based on the skill scores calculated by the metric are conducted for the Indian Ocean and the Pacific Ocean, respectively. Two models (NorESM1-M and MPI-ESM-LR) are ranked among the best 20 % for both the regions. Three models (inmcm4, MRI-CGCM3 and HadGEM2-ES) are ranked among the worst 20 % for both the regions. While the observed CCKW amplitude is greater north of the equator in the Pacific, some models overestimate the CCKW ampliutde in the Southern Hemisphere. This bias is related to the mean state precipitation bias along the south Pacific convergence zone.
Performance of a reduced-order FSI model for flow-induced vocal fold vibration
Chang, Siyuan; Luo, Haoxiang; Luo's lab Team
2016-11-01
Vocal fold vibration during speech production involves a three-dimensional unsteady glottal jet flow and three-dimensional nonlinear tissue mechanics. A full 3D fluid-structure interaction (FSI) model is computationally expensive even though it provides most accurate information about the system. On the other hand, an efficient reduced-order FSI model is useful for fast simulation and analysis of the vocal fold dynamics, which is often needed in procedures such as optimization and parameter estimation. In this work, we study the performance of a reduced-order model as compared with the corresponding full 3D model in terms of its accuracy in predicting the vibration frequency and deformation mode. In the reduced-order model, we use a 1D flow model coupled with a 3D tissue model. Two different hyperelastic tissue behaviors are assumed. In addition, the vocal fold thickness and subglottal pressure are varied for systematic comparison. The result shows that the reduced-order model provides consistent predictions as the full 3D model across different tissue material assumptions and subglottal pressures. However, the vocal fold thickness has most effect on the model accuracy, especially when the vocal fold is thin. Supported by the NSF.
Bayesian Model comparison of Higgs couplings
Bergstrom, Johannes
2014-01-01
We investigate the possibility of contributions from physics beyond the Standard Model (SM) to the Higgs couplings, in the light of the LHC data. The work is performed within an interim framework where the magnitude of the Higgs production and decay rates are rescaled though Higgs coupling scale factors. We perform Bayesian parameter inference on these scale factors, concluding that there is good compatibility with the SM. Furthermore, we carry out Bayesian model comparison on all models where any combination of scale factors can differ from their SM values and find that typically models with fewer free couplings are strongly favoured. We consider the evidence that each coupling individually equals the SM value, making the minimal assumptions on the other couplings. Finally, we make a comparison of the SM against a single "not-SM" model, and find that there is moderate to strong evidence for the SM.
Directory of Open Access Journals (Sweden)
Wei Jing
2016-01-01
Full Text Available In order to study the vibration problem of liquid-solid coupling of rectangular liquid-storage structure with horizontal elastic baffle, ignoring the influence of surface gravity wave, two different velocity potential functions corresponding to the liquid above and below the elastic baffle are assumed; based on the theory of mathematical equation and energy method, the formulas of basic frequency of liquid-solid coupling vibration system are derived, the baffle joined to the tank wall with 3 kinds of boundary conditions, namely, four edges simply supported, two opposite edges clamped and two opposite edges simply supported, and four edges clamped; the influence rules of baffle length-width ratio, the ratio of baffle height to liquid level, baffle elastic modulus, baffle density, baffle thickness, and liquid density on the coupling vibration performance are studied. The results show that the frequency of the clamped boundary is minimum; the influences of baffle length-width ratio and relative height on the basic frequency are much greater than that of the other system parameters; the relation between baffle length-width ratio and the frequency is exponential, while baffle relative height has a parabola relation with the frequency; the larger the baffle length-width ratio, the closer the baffle to the liquid level; the coupling frequency will be reduced more obviously.
Detailed model of bouncing drops on a bounded, vibrated bath
Blanchette, Francois; Gilet, Tristan
2014-11-01
We present a detailed model of drops bouncing on a bounded vibrated bath. These drops are known to bounce indefinitely and to exhibit complex and varied vertical dynamics depending on the acceleration of the bath. In addition, in a narrow parameter regime, these drops travel horizontally while being guided by the waves they generate. Our model tracks the drop's vertical radius and position, as well as the eigenmodes of the waves generated via ordinary differential equations only. We accurately capture the vertical dynamics, as well as some of the horizontal dynamics. Our model may be extended to account for interactions with other drops or obstacles, such as slits and corrals.
A fluctuating quantum model of the CO vibration in carboxyhemoglobin.
Falvo, Cyril; Meier, Christoph
2011-06-07
In this paper, we present a theoretical approach to construct a fluctuating quantum model of the CO vibration in heme-CO proteins and its interaction with external laser fields. The methodology consists of mixed quantum-classical calculations for a restricted number of snapshots, which are then used to construct a parametrized quantum model. As an example, we calculate the infrared absorption spectrum of carboxy-hemoglobin, based on a simplified protein model, and found the absorption linewidth in good agreement with the experimental results.
Directory of Open Access Journals (Sweden)
A. Ghorbanpour-Arani
2013-06-01
Full Text Available In this study, forced-vibration analysis of a coupled system of single layered graphene sheets (SLGSs subjected to the moving nano-particle is carried out based on nonlocal elasticity theory of orthotropic plate. Two SLGSs are coupled with elastic medium which is simulated by Pasternak and Visco-Pasternak models. Using Hamilton’s principle, governing differential equations of motion are derived and solved analytically. The effects of small scale, aspect ratio, velocity of nano-particle, time parameter, mechanical properties of graphene sheets, Visco-elastic medium on the maximum dynamic responses of each SLGSs are studied. Results indicate that, if the medium (elastic or visco-elastic medium of coupled system becomes more rigid, the maximum dynamic displacements of both SLGSs will be closer together.
Diagnosis and Model Based Identification of a Coupling Misalignment
Directory of Open Access Journals (Sweden)
P. Pennacchi
2005-01-01
Full Text Available This paper is focused on the application of two different diagnostic techniques aimed to identify the most important faults in rotating machinery as well as on the simulation and prediction of the frequency response of rotating machines. The application of the two diagnostics techniques, the orbit shape analysis and the model based identification in the frequency domain, is described by means of an experimental case study that concerns a gas turbine-generator unit of a small power plant whose rotor-train was affected by an angular misalignment in a flexible coupling, caused by a wrong machine assembling. The fault type is identified by means of the orbit shape analysis, then the equivalent bending moments, which enable the shaft experimental vibrations to be simulated, have been identified using a model based identification method. These excitations have been used to predict the machine vibrations in a large rotating speed range inside which no monitoring data were available. To the best of the authors' knowledge, this is the first case of identification of coupling misalignment and prediction of the consequent machine behaviour in an actual size rotating machinery. The successful results obtained emphasise the usefulness of integrating common condition monitoring techniques with diagnostic strategies.
A Solvatochromic Model Calibrates Nitriles’ Vibrational Frequencies to Electrostatic Fields
Bagchi, Sayan; Fried, Stephen D.; Boxer, Steven G.
2012-01-01
Electrostatic interactions provide a primary connection between a protein’s three-dimensional structure and its function. Infrared (IR) probes are useful because vibrational frequencies of certain chemical groups, such as nitriles, are linearly sensitive to local electrostatic field, and can serve as a molecular electric field meter. IR spectroscopy has been used to study electrostatic changes or fluctuations in proteins, but measured peak frequencies have not been previously mapped to total electric fields, because of the absence of a field-frequency calibration and the complication of local chemical effects such as H-bonds. We report a solvatochromic model that provides a means to assess the H-bonding status of aromatic nitrile vibrational probes, and calibrates their vibrational frequencies to electrostatic field. The analysis involves correlations between the nitrile’s IR frequency and its 13C chemical shift, whose observation is facilitated by a robust method for introducing isotopes into aromatic nitriles. The method is tested on the model protein Ribonuclease S (RNase S) containing a labeled p-CN-Phe near the active site. Comparison of the measurements in RNase S against solvatochromic data gives an estimate of the average total electrostatic field at this location. The value determined agrees quantitatively with MD simulations, suggesting broader potential for the use of IR probes in the study of protein electrostatics. PMID:22694663
A solvatochromic model calibrates nitriles' vibrational frequencies to electrostatic fields.
Bagchi, Sayan; Fried, Stephen D; Boxer, Steven G
2012-06-27
Electrostatic interactions provide a primary connection between a protein's three-dimensional structure and its function. Infrared probes are useful because vibrational frequencies of certain chemical groups, such as nitriles, are linearly sensitive to local electrostatic field and can serve as a molecular electric field meter. IR spectroscopy has been used to study electrostatic changes or fluctuations in proteins, but measured peak frequencies have not been previously mapped to total electric fields, because of the absence of a field-frequency calibration and the complication of local chemical effects such as H-bonds. We report a solvatochromic model that provides a means to assess the H-bonding status of aromatic nitrile vibrational probes and calibrates their vibrational frequencies to electrostatic field. The analysis involves correlations between the nitrile's IR frequency and its (13)C chemical shift, whose observation is facilitated by a robust method for introducing isotopes into aromatic nitriles. The method is tested on the model protein ribonuclease S (RNase S) containing a labeled p-CN-Phe near the active site. Comparison of the measurements in RNase S against solvatochromic data gives an estimate of the average total electrostatic field at this location. The value determined agrees quantitatively with molecular dynamics simulations, suggesting broader potential for the use of IR probes in the study of protein electrostatics.
Role of vibrationally excited HBr in a HBr/He inductively coupled plasma used for etching of silicon
Tinck, Stefan; Bogaerts, Annemie
2016-06-01
In this work, the role of vibrationally excited HBr (HBr(vib)) is computationally investigated for a HBr/He inductively coupled plasma applied for Si etching. It is found that at least 50% of all dissociations of HBr occur through HBr(vib). This additional dissociation pathway through HBr(vib) makes the plasma significantly more atomic. It also results in a slightly higher electron temperature (i.e. about 0.2 eV higher compared to simulation results where HBr(vib) is not included), as well as a higher gas temperature (i.e. about 50 K higher than without including HBr(vib)), due to the enhanced Franck-Condon heating through HBr(vib) dissociation, at the conditions investigated. Most importantly, the calculated etch rate with HBr(vib) included in the model is a factor 3 higher than in the case without HBr(vib), due to the higher fluxes of etching species (i.e. H and Br), while the chemical composition of the wafer surface shows no significant difference. Our calculations clearly show the importance of including HBr(vib) for accurate modeling of HBr-containing plasmas.
Brenna, Marco
2014-01-01
The self-consistent mean-field (SCMF) theory describes many properties of the ground state and excited states of the atomic nucleus, such as masses, radii, deformations and giant resonance energies. SCMF models are based on the independent particle picture where nucleons are assumed to move in a self-generated average potential. In the first part of this work, we apply a state-of-the-art SCMF approach, based on the Skyrme effective interaction, to two different excitations (viz. the pygmy dipole resonance and the isovector giant quadrupole resonance), investigating their relation with the nuclear matter symmetry energy, which corresponds to the energy cost for changing protons into neutrons and is a key parameter for the nuclear equation of state. However, SCMF models present well known limitations which require the inclusion of further dynamical correlations, e.g. the ones coming from the interweaving between single-particle and collective degrees of freedom (particle-vibration coupling - PVC). In the second...
A tightly coupled non-equilibrium model for inductively coupled radio-frequency plasmas
Energy Technology Data Exchange (ETDEWEB)
Munafò, A., E-mail: munafo@illinois.edu; Alfuhaid, S. A., E-mail: alfuhai2@illinois.edu; Panesi, M., E-mail: mpanesi@illinois.edu [Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Talbot Laboratory, 104 S. Wright St., Urbana, Illinois 61801 (United States); Cambier, J.-L., E-mail: jean-luc.cambier@us.af.mil [Edwards Air Force Base Research Laboratory, 10 E. Saturn Blvd., Edwards AFB, California 93524 (United States)
2015-10-07
The objective of the present work is the development of a tightly coupled magneto-hydrodynamic model for inductively coupled radio-frequency plasmas. Non Local Thermodynamic Equilibrium (NLTE) effects are described based on a hybrid State-to-State approach. A multi-temperature formulation is used to account for thermal non-equilibrium between translation of heavy-particles and vibration of molecules. Excited electronic states of atoms are instead treated as separate pseudo-species, allowing for non-Boltzmann distributions of their populations. Free-electrons are assumed Maxwellian at their own temperature. The governing equations for the electro-magnetic field and the gas properties (e.g., chemical composition and temperatures) are written as a coupled system of time-dependent conservation laws. Steady-state solutions are obtained by means of an implicit Finite Volume method. The results obtained in both LTE and NLTE conditions over a broad spectrum of operating conditions demonstrate the robustness of the proposed coupled numerical method. The analysis of chemical composition and temperature distributions along the torch radius shows that: (i) the use of the LTE assumption may lead to an inaccurate prediction of the thermo-chemical state of the gas, and (ii) non-equilibrium phenomena play a significant role close the walls, due to the combined effects of Ohmic heating and macroscopic gradients.
Papavassiliou, I.; Venkatesan, C.; Friedmann, P. P.
1990-01-01
A fundamental study of vibration prediction and vibration reduction in helicopters using active controls was performed. The nonlinear equations of motion for a coupled rotor/flexible fuselage system have been derived using computer algebra on a special purpose symbolic computing facility. The details of the derivation using the MACSYMA program are described. The trim state and vibratory response of the helicopter are obtained in a single pass by applying the harmonic balance technique and simultaneously satisfying the trim and the vibratory response of the helicopter for all rotor and fuselage degrees of freedom. The influence of the fuselage flexibility on the vibratory response is studied. It is shown that the conventional single frequency higher harmonic control (HHC) capable of reducing either the hub loads or only the fuselage vibrations but not both simultaneously. It is demonstrated that for simultaneous reduction of hub shears and fuselage vibrations a new scheme called multiple higher harmonic control (MHHC) is required. The fundamental aspects of this scheme and its uniqueness are described in detail, providing new insight on vibration reduction in helicopters using HHC.
Next-Generation Modeling, Analysis, and Testing of the Vibration of Mistuned Bladed Disks
2007-12-21
August 2007. [22] Whitehead, D. S., "Effect of Mistuning on the Vibration of Turbomachine Blades Induced by Wakes," Journal of Mechanical Engineering...14-17. [27] Wagner, J. T., "Coupling of Turbomachine Blade Vibrations Through the Rotor," Journal of Engineering for Power, Vol. 89, No. 3, 1967, pp
Institute of Scientific and Technical Information of China (English)
李晓妮; 向宇; 黄玉盈; 袁丽芸; 陆静
2011-01-01
The commonly used model for dynamic analysis of the shell with active constrained layer damping (ACLD) is a simply coupled electro-mechanical model (SCEM). In this model the electric field is assumed to be negligible in the in-plane directions of piezoelectric layer and to be constant throughout the thickness in the normal direction. The reason for ineffectiveness of SCEM was analyzed theoretically and a fully coupled electro-mechanical model (FCEM) was further developed. Then a first-order differential matrix equation for FCEM of thin ACLD circular cylindrical shell was derived. A high precision and high efficiency transfer matrix method based on the extended homogeneous capacity precision integration approach was employed to solve the matrix equation. Compared with the classical 3D method, the proposed method can greatly simplify computation, and can be applied to analyze the vibration control problems of thin circular cylindrical shell partially treated with ACLD under arbitrary boundary conditions. Numerical results were given to compare the two kinds of models ( SCEM and FCEM) in a wider frequency range. The results by both models agree exactly in the lowfrequency range, whereas differ significantly in the high-frequency range. This confirms sufficiently SCME is only applicable to low-frequency vibration problems while FCEM can be used in a wider frequency range.%目前在ACLD薄壳结构的动力学分析中,通常采用一种忽略压电约束层面内电场强度,仅考虑在厚度方向为常量分布的法向电场强度的简化力电耦合模型.首先从理论上分析了简化力电耦合模型的局限性,进而提出了一种新的完全力电耦合模型,以此为基础导出了该模型下ACLD圆柱壳的一阶常微分矩阵状态方程,并结合传递矩阵法和齐次扩容精细积分法求解该方程.相对于传统三维模型方法,所建立的新模型和求解方法不仅大幅度简化了计算,而且适用于分析部分覆盖和任
Tang, Xiaolin; Yang, Wei; Hu, Xiaosong; Zhang, Dejiu
2017-02-01
In this study, based on our previous work, a novel simplified torsional vibration dynamic model is established to study the torsional vibration characteristics of a compound planetary hybrid propulsion system. The main frequencies of the hybrid driveline are determined. In contrast to vibration characteristics of the previous 16-degree of freedom model, the simplified model can be used to accurately describe the low-frequency vibration property of this hybrid powertrain. This study provides a basis for further vibration control of the hybrid powertrain during the process of engine start/stop.
Mielke, Steven L; Chakraborty, Arindam; Truhlar, Donald G
2013-08-15
We present vibrational configuration interaction calculations employing the Watson Hamiltonian and a multimode expansion. Results for the lowest 36 eigenvalues of the zero total angular momentum rovibrational spectrum of methane agree with the accurate benchmarks of Wang and Carrington to within a mean unsigned deviation of 0.68, 0.033, and 0.014 cm(-1) for 4-mode, 5-mode, and 6-mode representations, respectively. We note that in the case of the 5-mode results, this is a factor of 10 better agreement than for 5-mode calculations reported earlier by Wu, Huang, Carter, and Bowman for the same set of eigenvalues, which indicates that the multimode expansion is even more rapidly convergent than previously demonstrated. Our largest calculations employ a tiered approach with matrix elements treated using a variable-order multimode expansion with orders ranging from 4-mode to 7-mode; strategies for assigning matrix elements to particular multimode tiers are discussed. Improvements of 7-mode coupling over 6-mode coupling are small (averaging 0.002 cm(-1) for the first 36 eigenvalues) suggesting that 7-mode coupling is sufficient to fully converge the results. A number of approximate treatments of the computationally expensive vibrational angular momentum terms are explored. The use of optimized vibrational quadratures allows rapid integration of the matrix elements, especially the vibrational angular momentum terms, which require significantly fewer quadrature points than are required to integrate the potential. We assign the lowest 243 states and compare our results to those of Wang and Carrington, who provided assignments for the same set of states. Excellent agreement is observed for most states, but our results are lower for some of the higher-energy states by as much as 20 cm(-1), with the largest deviations being for the states with six quanta of excitation in the F2 bends, suggesting that the earlier results were not fully converged with respect to the basis set. We
Towards a comprehensive model for the electronic and vibrational structure of the Creutz-Taube ion.
Reimers, Jeffrey R; Wallace, Brett B; Hush, Noel S
2008-01-13
Since the synthesis of the Creutz-Taube ion, the nature of its charge localization has been of immense scientific interest, this molecule providing a model system for the understanding of the operation of biological photosynthetic and electron-transfer processes. However, recent work has shown that its nature remains an open question. Many systems of this type, including photosynthetic reaction centres, are of current research interest, and thereby the Creutz-Taube ion provides an important chemical paradigm: the key point of interest is the details of how such molecules behave. We lay the groundwork for the construction of a comprehensive model for its chemical and spectroscopic properties. Advances are described in some of the required areas including: simulation of electronic absorption spectra; quantitative depiction of the large interaction of the ion's electronic description with solvent motions; and the physics of Ru-NH3 spectator-mode vibrations. We show that details of the solvent electron-phonon coupling are critical in the interpretation of the spectator-mode vibrations, as these strongly mix with solvent motions when 0.75<2J/lambda<1. In this regime, a double-well potential exists which does not support localized zero-point vibration, and many observed properties of the Creutz-Taube ion are shown to be consistent with the hypothesis that the ion has this character.
Directory of Open Access Journals (Sweden)
H. F. Wang
2014-01-01
Full Text Available Support looseness fault is a type of common fault in aeroengine. Serious looseness fault would emerge under larger unbalanced force, which would cause excessive vibration and even lead to rubbing fault, so it is important to analyze and recognize looseness fault effectively. In this paper, based on certain type turbofan engine structural features, a rotor-support-casing whole model for certain type turbofan aeroengine is established. The rotor and casing systems are modeled by means of the finite element beam method; the support systems are modeled by lumped-mass model; the support looseness fault model is also introduced. The coupled system response is obtained by numerical integral method. In this paper, based on the casing acceleration signals, the impact characteristics of symmetrical stiffness and asymmetric stiffness models are analyzed, finding that the looseness fault would lead to the longitudinal asymmetrical characteristics of acceleration time domain wave and the multiple frequency characteristics, which is consistent with the real trial running vibration signals. Asymmetric stiffness looseness model is verified to be fit for aeroengine looseness fault model.
Vibration acceleration promotes bone formation in rodent models
Uchida, Ryohei; Nakata, Ken; Kawano, Fuminori; Yonetani, Yasukazu; Ogasawara, Issei; Nakai, Naoya; Mae, Tatsuo; Matsuo, Tomohiko; Tachibana, Yuta; Yokoi, Hiroyuki; Yoshikawa, Hideki
2017-01-01
All living tissues and cells on Earth are subject to gravitational acceleration, but no reports have verified whether acceleration mode influences bone formation and healing. Therefore, this study was to compare the effects of two acceleration modes, vibration and constant (centrifugal) accelerations, on bone formation and healing in the trunk using BMP 2-induced ectopic bone formation (EBF) mouse model and a rib fracture healing (RFH) rat model. Additionally, we tried to verify the difference in mechanism of effect on bone formation by accelerations between these two models. Three groups (low- and high-magnitude vibration and control-VA groups) were evaluated in the vibration acceleration study, and two groups (centrifuge acceleration and control-CA groups) were used in the constant acceleration study. In each model, the intervention was applied for ten minutes per day from three days after surgery for eleven days (EBF model) or nine days (RFH model). All animals were sacrificed the day after the intervention ended. In the EBF model, ectopic bone was evaluated by macroscopic and histological observations, wet weight, radiography and microfocus computed tomography (micro-CT). In the RFH model, whole fracture-repaired ribs were excised with removal of soft tissue, and evaluated radiologically and histologically. Ectopic bones in the low-magnitude group (EBF model) had significantly greater wet weight and were significantly larger (macroscopically and radiographically) than those in the other two groups, whereas the size and wet weight of ectopic bones in the centrifuge acceleration group showed no significant difference compared those in control-CA group. All ectopic bones showed calcified trabeculae and maturated bone marrow. Micro-CT showed that bone volume (BV) in the low-magnitude group of EBF model was significantly higher than those in the other two groups (3.1±1.2mm3 v.s. 1.8±1.2mm3 in high-magnitude group and 1.3±0.9mm3 in control-VA group), but BV in the
Force Limited Random Vibration Test of TESS Camera Mass Model
Karlicek, Alexandra; Hwang, James Ho-Jin; Rey, Justin J.
2015-01-01
The Transiting Exoplanet Survey Satellite (TESS) is a spaceborne instrument consisting of four wide field-of-view-CCD cameras dedicated to the discovery of exoplanets around the brightest stars. As part of the environmental testing campaign, force limiting was used to simulate a realistic random vibration launch environment. While the force limit vibration test method is a standard approach used at multiple institutions including Jet Propulsion Laboratory (JPL), NASA Goddard Space Flight Center (GSFC), European Space Research and Technology Center (ESTEC), and Japan Aerospace Exploration Agency (JAXA), it is still difficult to find an actual implementation process in the literature. This paper describes the step-by-step process on how the force limit method was developed and applied on the TESS camera mass model. The process description includes the design of special fixtures to mount the test article for properly installing force transducers, development of the force spectral density using the semi-empirical method, estimation of the fuzzy factor (C2) based on the mass ratio between the supporting structure and the test article, subsequent validating of the C2 factor during the vibration test, and calculation of the C.G. accelerations using the Root Mean Square (RMS) reaction force in the spectral domain and the peak reaction force in the time domain.
Coupling dark energy with Standard Model states
Bento, M C; Bertolami, O
2009-01-01
In this contribution one examines the coupling of dark energy to the gauge fields, to neutrinos, and to the Higgs field. In the first case, one shows how a putative evolution of the fundamental couplings of strong and weak interactions via coupling to dark energy through a generalized Bekenstein-type model may cause deviations on the statistical nuclear decay Rutherford-Soddy law. Existing bounds for the weak interaction exclude any significant deviation. For neutrinos, a perturbative approach is developed which allows for considering viable varying mass neutrino models coupled to any quintessence-type field. The generalized Chaplygin model is considered as an example. For the coupling with the Higgs field one obtains an interesting cosmological solution which includes the unification of dark energy and dark matter.
Numerical modelling of ground-borne noise and vibration in buildings due to surface rail traffic
Fiala, P.; Degrande, G.; Augusztinovicz, F.
2007-04-01
This paper deals with the numerical computation of the structural and acoustic response of a building to an incoming wave field generated by high-speed surface railway traffic. The source model consists of a moving vehicle on a longitudinally invariant track, coupled to a layered ground modelled with a boundary element formulation. The receiver model is based on a substructuring formulation and consists of a boundary element model of the soil and a finite element model of the structure. The acoustic response of the building's rooms is computed by means of a spectral finite element formulation. The paper investigates the structural and acoustic response of a multi-story portal frame office building up to a frequency of 150 Hz to the passage of a Thalys high-speed train at constant velocity. The isolation performance of three different vibration countermeasures: a floating-floor, a room-in-room, and base-isolation, are examined.
Scheidler, Justin J.; Asnani, Vivake M.
2017-03-01
This paper presents a linear model of the fully-coupled electromechanical behavior of a generally-shunted magnetostrictive transducer. The impedance and admittance representations of the model are reported. The model is used to derive the effect of the shunt’s electrical impedance on the storage modulus and loss factor of the transducer without neglecting the inherent resistance of the transducer’s coil. The expressions are normalized and then shown to also represent generally-shunted piezoelectric materials that have a finite leakage resistance. The generalized expressions are simplified for three shunts: resistive, series resistive-capacitive, and inductive, which are considered for shunt damping, resonant shunt damping, and stiffness tuning, respectively. For each shunt, the storage modulus and loss factor are plotted for a wide range of the normalized parameters. Then, important trends and their impact on different applications are discussed. An experimental validation of the transducer model is presented for the case of resistive and resonant shunts. The model closely predicts the measured response for a variety of operating conditions. This paper also introduces a model for the dynamic compliance of a vibrating structure that is coupled to a magnetostrictive transducer for shunt damping and resonant shunt damping applications. This compliance is normalized and then shown to be analogous to that of a structure that is coupled to a piezoelectric material. The derived analogies allow for the observations and equations in the existing literature on structural vibration control using shunted piezoelectric materials to be directly applied to the case of shunted magnetostrictive transducers.
Ghadiri, Majid; Shafiei, Navvab
2016-04-01
In this study, thermal vibration of rotary functionally graded Timoshenko microbeam has been analyzed based on modified couple stress theory considering temperature change in four types of temperature distribution on thermal environment. Material properties of FG microbeam are supposed to be temperature dependent and vary continuously along the thickness according to the power-law form. The axial forces are also included in the model as the thermal and true spatial variation due to the rotation. Governing equations and boundary conditions have been derived by employing Hamiltonian's principle. The differential quadrature method is employed to solve the governing equations for cantilever and propped cantilever boundary conditions. Validations are done by comparing available literatures and obtained results which indicate accuracy of applied method. Results represent effects of temperature changes, different boundary conditions, nondimensional angular velocity, length scale parameter, different boundary conditions, FG index and beam thickness on fundamental, second and third nondimensional frequencies. Results determine critical values of temperature changes and other essential parameters which can be applicable to design micromachines like micromotor and microturbine.
The vibrating reed frequency meter: digital investigation of an early cochlear model
Directory of Open Access Journals (Sweden)
Andrew Bell
2015-10-01
Full Text Available The vibrating reed frequency meter, originally employed by Békésy and later by Wilson as a cochlear model, uses a set of tuned reeds to represent the cochlea’s graded bank of resonant elements and an elastic band threaded between them to provide nearest-neighbour coupling. Here the system, constructed of 21 reeds progressively tuned from 45 to 55 Hz, is simulated numerically as an elastically coupled bank of passive harmonic oscillators driven simultaneously by an external sinusoidal force. To uncover more detail, simulations were extended to 201 oscillators covering the range 1–2 kHz. Calculations mirror the results reported by Wilson and show expected characteristics such as traveling waves, phase plateaus, and a response with a broad peak at a forcing frequency just above the natural frequency. The system also displays additional fine-grain features that resemble those which have only recently been recognised in the cochlea. Thus, detailed analysis brings to light a secondary peak beyond the main peak, a set of closely spaced low-amplitude ripples, rapid rotation of phase as the driving frequency is swept, frequency plateaus, clustering, and waxing and waning of impulse responses. Further investigation shows that each reed’s vibrations are strongly localised, with small energy flow along the chain. The distinctive set of equally spaced ripples is an inherent feature which is found to be largely independent of boundary conditions. Although the vibrating reed model is functionally different to the standard transmission line, its cochlea-like properties make it an intriguing local oscillator model whose relevance to cochlear mechanics needs further investigation.
The Estimation of Vibrational Energy of Two Coupled (Welded Plates Using Statistical Energy Analysis
Directory of Open Access Journals (Sweden)
Hawraa S. Ibraham
2011-01-01
Full Text Available This paper deals with a method called Statistical Energy Analysis that can be applied to the mechanical and acoustical systems like buildings, bridges and aircrafts etc. S.E.A as a tool can be applied to the resonant systems in the circumstances of high frequency or/and complex structure». The parameters of S.E.A such as coupling loss factor, internal loss factor, modal density and input power are clarified in this work ; coupled plate sub-systems and explanations are presented for these parameters. The developed system is assumed to be resonant, conservative, linear and there is an equipartition of energy between all the resonant modes within a given frequency band in a given sub-system. The aim of this work is to find the energy stored in the sub-systems for two coupled (welded plates in rectangular angle systems and study the effect of changing sub-systems dimensions, the results shows that as surface area of directly driven plates A1 increases energy level of plate 1 increases while a reduction in the energy level of indirectly driven plate (plate 2 is noticed. This is because of the strength of coupling decreases towards the weak coupling condition and this leads to a reduction in the power transferred from plate 1 to plate 2 and consequently a lower energy level for plate 2. In addition the effect of changing the internal loss factor for a range of (0.00001-0.1 causes a reduction of the values of energy level in these sub-systems. because the increasing of internal loss factor values led to the increasing of the material resistance and that will dissipate the energy flow across those sub-systems. A comparison is made between S.E.A models built by FORTRAN program and Finite Element model solved by ANSYS package.
National Research Council Canada - National Science Library
Yao, Jiannan; Deng, Yong; Xiao, Xingming
2017-01-01
To avoid catenary collision in a multi-rope friction mine hoist, in this study, the relevant hoisting parameters based on the multi-source coupled vibration characteristics of hoisting catenaries are optimized...
NONLINEAR FLUID DAMPING IN STRUCTURE-WAKE OSCILLATORS IN MODELING VORTEX-INDUCED VIBRATIONS
Institute of Scientific and Technical Information of China (English)
LIN Li-ming; LING Guo-can; WU Ying-xiang; ZENG Xiao-hui
2009-01-01
A Nonlinear Fluid Damping(NFD)in the form of the square-velocity is applied in the response analysis of Vortex-Induced Vibrations(VIV).Its nonlinear hydrodynamic effects on the coupled wake and structure oscillators are investigated.A comparison between the coupled systems with the linear and nonlinear fluid dampings and experiments shows that the NFD model can well describe response characteristics,such as the amplification of body displacement at lock-in and frequency lock-in,both at high and low mass ratios.Particularly,the predicted peak amplitude of the body in the Griffin plot is in good agreement with experimental data and empirical equation,indicating the significant effect of the NFD on the structure motion.
Generalized circuit model for coupled plasmonic systems
Benz, Felix; Tserkezis, Christos; Chikkaraddy, Rohit; Sigle, Daniel O; Pukenas, Laurynas; Evans, Stephen D; Aizpurua, Javier; Baumberg, Jeremy J
2015-01-01
We develop an analytic circuit model for coupled plasmonic dimers separated by small gaps that provides a complete account of the optical resonance wavelength. Using a suitable equivalent circuit, it shows how partially conducting links can be treated and provides quantitative agreement with both experiment and full electromagnetic simulations. The model highlights how in the conducting regime, the kinetic inductance of the linkers set the spectral blue-shifts of the coupled plasmon.
Institute of Scientific and Technical Information of China (English)
胡启国; 李力克; 陈万德
2013-01-01
Noise analysis for the diesel engine oil pan casing vibration analysis only and ignore the lubricating fluid and cavity effects. The use of acoustic-liquid-vibration coupling finite element theory, coupling system element model is established of oil pan, oil and internal cavity of oil pan, and the modal of the finite element is analysised, then the vibration frequency of the oil pan is measured and analysised. Research oil pan system in the acoustic fluid coupled vibration mode was significantly lower vibration and noise enhancement, especially in the strong coupling 118.26 Hz modal frequencies. Lubricating fluid in the oil pan when the low-frequency sound vibration coupled system is less liquid, at high frequencies is more significant impact on the system.%针对柴油机油底壳噪声分析中只分析壳体振动而忽略了润滑液和空腔影响,利用声液振耦合有限元理论,建立油底壳结构有限元模型,润滑油、内部空腔声学有限元模型,油底壳声液振耦合系统有限元模型,并对各有限元模型进行模态研究,然后对实际油底壳振动频谱特性进行验证分析.通过研究得到油底壳在声液振耦合系统模态下振动和噪声值明显增强,特别是在118.26 Hz强耦合模态频率下.油底壳中润滑液在低频时对声液振耦合系统影响较小,在高频时对系统影响较为明显.
Institute of Scientific and Technical Information of China (English)
柯世堂; 王同光
2015-01-01
A fast method to calculate aero-elastic responses of wind turbine based on a tower-blade coupled structure model was proposed.By taking the 5 MW wind turbine system designed by Nanjing University of Aeronautics and Astronautics as an example,a finite element model for investigating the wind turbine tower-blade coupled vibration was established to obtain the information of its dynamic characteristics.The harmonic superposition method and the modified blade element momentum theory were applied to calculate the aerodynamic load,considering the influence of yaw conditions.The mode superposition method was used to solve the kinetic equation of wind turbine system,the blade velocity and dynamic load were updated through iterative loop,and then the aero-elastic responses of wind turbine system were calculated.The influence of yaw angle on wind-induced responses was discussed.The research contributes a scientific basis to the wind-resistant structure design for the tower-blade system of large-scale wind turbines.%提出一套快速预测偏航状态下风力机全机结构气弹响应的分析方法。以南京航空航天大学自主研发的5MW特大型概念风力机为例，建立风力机塔架－叶片耦合模型获取模态信息；采用谐波叠加法和改进的叶素－动量理论计算气动荷载，并考虑了偏航角对诱导速度的影响；再运用模态叠加法求解风力机耦合动力学方程，通过迭代循环更新叶片速度和气动力，对风力机塔架－叶片耦合结构进行气动载荷和气弹响应计算，并通过参数分析归纳出偏航角和气动弹性对风力机全机动态响应的影响规律。研究结论可为此类特大型风力机塔架－叶片耦合结构的抗风设计提供科学依据。
Nonlinear dynamic model for magnetically-tunable Galfenol vibration absorbers
Scheidler, Justin J.; Dapino, Marcelo J.
2013-03-01
This paper presents a single degree of freedom model for the nonlinear vibration of a metal-matrix composite manufactured by ultrasonic additive manufacturing that contains seamlessly embedded magnetostrictive Galfenol alloys (FeGa). The model is valid under arbitrary stress and magnetic field. Changes in the composite's natural frequency are quantified to assess its performance as a semi-active vibration absorber. The effects of Galfenol volume fraction and location within the composite on natural frequency are quantified. The bandwidth over which the composite's natural frequency can be tuned with a bias magnetic field is studied for varying displacement excitation amplitudes. The natural frequency is tunable for all excitation amplitudes considered, but the maximum tunability occurs below an excitation amplitude threshold of 1 × 10-6 m for the composite geometry considered. Natural frequency shifts between 6% and 50% are found as the Galfenol volume fraction varies from 25% to 100% when Galfenol is located at the composite neutral axis. At a modest 25% Galfenol by volume, the model shows that up to 15% shifts in composite resonance are possible through magnetic bias field modulation if Galfenol is embedded away from the composite midplane. As the Galfenol volume fraction and distance between Galfenol and composite midplane are increased, linear and quadratic increases in tunability result, respectively.
Energy Technology Data Exchange (ETDEWEB)
Adly, A.A. [Electrical Power and Machines Department, Faculty of Engineering, Cairo University, Giza 12211 (Egypt)], E-mail: adlyamr@gmail.com; Abd-El-Hafiz, S.K. [Department of Engineering Mathematics, Faculty of Engineering, Cairo University, Giza 12211 (Egypt)], E-mail: salwahafiz@link.net
2008-02-01
Magnetic materials exhibiting gigantic magnetostriction are currently being used in various actuator devices and vibration damping applications. Recently, a new family of efficient Preisach-type vector hysteresis models having coupled elementary operators has been introduced. The purpose of this paper is to extend the applicability of those recently introduced models to magnetostriction simulation. Details of the model, its identification, and experimental testing are presented in the paper.
人－桥竖向耦合振动计算方法%Calculation method for human-bridge vertically coupled vibration
Institute of Scientific and Technical Information of China (English)
谢旭; 钟婧如; 张鹤; 张治成
2016-01-01
In order to investigate the human-bridge vertically coupled vibration of lightweight footbridges,a human-bridge vertically coupled vibration equitation based on a bipedal pedestrian model was developed.A comparison between the simulated foot force on rigid ground and the foot force time history curve presented in reference showed that the human body bipedal walking model provided here can simulate the features of ground reaction force properly.Reasonable ranges of the parameters of this bipedal model were discussed.A 22.8m-span aluminum alloy footbridge (with the 1st vertical bending vibration natural frequency of 7.23 Hz)was taken as an example to calculate the structural dynamic responses under vertical crowd-bridge interaction.Stochastic crowd walking parameters were generated by Monte-Carlo method to simulate the random crowd conditions of different densities,and the direct integral method was used to compute the dynamic response of the foot bridge considering crowd-bridge vertically coupled vibration.The results indicated that as the crowd density rises,the predominant frequencies of the human-bridge coupled vibration tend to dispersing,the vibration responses are much smaller than those not considering the coupling effect.%为了分析轻质人行桥的人－桥竖向耦合振动，建立了基于双脚支撑人体计算模型的人－桥耦合振动方程。根据行人在刚性地面行走时的步伐荷载计算结果与文献给出的步伐荷载时程曲线对比，验证了双脚支撑人体计算模型能较好地模拟行人的脚步力特性并讨论了合理的人体参数取值范围。以一座跨度22．8 m、第一阶竖弯自振频率7．23 Hz 的铝合金人行桥为例，运用 Monte Carlo 法模拟人群的步行参数，形成不同密度人群过桥的随机工况，并用直接积分法计算了考虑人群－桥竖向耦合振动的铝合金人行桥动力响应。计算结果表明，当人群密度较大时，考虑人桥耦合的人
On the Elastic Vibration Model for High Length-Diameter Ratio Rocket with Attitude Control System
Institute of Scientific and Technical Information of China (English)
朱伯立; 杨树兴
2003-01-01
An elastic vibration model for high length-diameter ratio spinning rocket with attitude control system which can be used for trajectory simulation is established. The basic theory of elastic dynamics and vibration dynamics were both used to set up the elastic vibration model of rocket body. In order to study the problem more conveniently, the rocket's body was simplified to be an even beam with two free ends. The model was validated by simulation results and the test data.
Li, Xiaochen; Liao, Shijun
2016-01-01
A system of two-dimensional, two coupled Faraday interfacial waves is experimentally observed at the two interfaces of the three layers of fluids (air, pure ethanol and silicon oil) in a sealed Hele-Shaw cell with periodic vertical vibration. The upper and lower Faraday waves coexist: the upper vibrates vertically, but the crests of the lower one oscillate horizontally with unchanged wave height and a frequency equal to the half of the forcing one of the vertically vibrating basin, while the troughs of the lower one always stay in the same place (relative to the basin). Besides, they are strongly coupled: the wave height of the lower Faraday wave is either a linear function (in the case of a fixed forcing frequency) or a parabolic function (in the case of a fixed acceleration amplitude) of that of the upper, with the same wave length. In addition, the upper Faraday wave temporarily loses its smoothness at around $t=T/4$ and $t=3T/4$, where $T$ denotes the wave period, and thus has fundamental difference from ...
Saffar, Saber; Abdullah, Amir
2014-03-01
Vibration amplitude of transducer's elements is the influential parameters in the performance of high power airborne ultrasonic transducers to control the optimum vibration without material yielding. The vibration amplitude of elements of provided high power airborne transducer was determined by measuring temperature of the provided high power airborne transducer transducer's elements. The results showed that simple thermocouples can be used both to measure the vibration amplitude of transducer's element and an indicator to power transmission to the air. To verify our approach, the power transmission to the air has been investigated by other common method experimentally. The experimental results displayed good agreement with presented approach. Copyright © 2013 Elsevier B.V. All rights reserved.
Stochastic modeling of friction force and vibration analysis of a mechanical system using the model
Energy Technology Data Exchange (ETDEWEB)
Kang, Won Seok; Choi, Chan Kyu; Yoo, Hong Hee [Hanyang University, Seoul (Korea, Republic of)
2015-09-15
The squeal noise generated from a disk brake or chatter occurred in a machine tool primarily results from friction-induced vibration. Since friction-induced vibration is usually accompanied by abrasion and lifespan reduction of mechanical parts, it is necessary to develop a reliable analysis model by which friction-induced vibration phenomena can be accurately analyzed. The original Coulomb's friction model or the modified Coulomb friction model employed in most commercial programs employs deterministic friction coefficients. However, observing friction phenomena between two contact surfaces, one may observe that friction coefficients keep changing due to the unevenness of contact surface, temperature, lubrication and humidity. Therefore, in this study, friction coefficients are modeled as random parameters that keep changing during the motion of a mechanical system undergoing friction force. The integrity of the proposed stochastic friction model was validated by comparing the analysis results obtained by the proposed model with experimental results.
Raytracing simulations of coupled dark energy models
Pace, Francesco; Moscardini, Lauro; Bacon, David; Crittenden, Robert
2014-01-01
Dark matter and dark energy are usually assumed to be independent, coupling only gravitationally. An extension to this simple picture is to model dark energy as a scalar field which is directly coupled to the cold dark matter fluid. Such a non-trivial coupling in the dark sector leads to a fifth force and a time-dependent dark matter particle mass. In this work we examine the impact that dark energy-dark matter couplings have on weak lensing statistics by constructing realistic simulated weak-lensing maps using raytracing techniques through a suite of N-body cosmological simulations. We construct maps for an array of different lensing quantities, covering a range of scales from a few arcminutes to several degrees. The concordance $\\Lambda$CDM model is compared to different coupled dark energy models, described either by an exponential scalar field potential (standard coupled dark energy scenario) or by a SUGRA potential (bouncing model). We analyse several statistical quantities, in particular the power spect...
Directory of Open Access Journals (Sweden)
M. Sanbi
2015-01-01
Full Text Available Theoretical and numerical results of the modeling of a smart plate are presented for optimal active vibration control. The smart plate consists of a rectangular aluminum piezocomposite plate modeled in cantilever configuration with surface bonded thermopiezoelectric patches. The patches are symmetrically bonded on top and bottom surfaces. A generic thermopiezoelastic theory for piezocomposite plate is derived, using linear thermopiezoelastic theory and Kirchhoff assumptions. Finite element equations for the thermopiezoelastic medium are obtained by using the linear constitutive equations in Hamilton’s principle together with the finite element approximations. The structure is modelled analytically and then numerically and the results of simulations are presented in order to visualize the states of their dynamics and the state of control. The optimal control LQG-Kalman filter is applied. By using this model, the study first gives the influences of the actuator/sensor pair placement and size on the response of the smart plate. Second, the effects of thermoelastic and pyroelectric couplings on the dynamics of the structure and on the control procedure are studied and discussed. It is shown that the effectiveness of the control is not affected by the applied thermal gradient and can be applied with or without this gradient at any time of plate vibrations.
Dijkstra, Arend G
2015-01-01
We study hole, electron and exciton transport in a charge transfer system in the presence of underdamped vibrational motion. We analyze the signature of these processes in the linear and third-, and fifth-order nonlinear electronic spectra. Calculations are performed with a numerically exact hierarchical equations of motion method for an underdamped Brownian oscillator spectral density. We find that combining electron, hole and exciton transfer can lead to non-trivial spectra with more structure than with excitonic coupling alone. Traces taken during the waiting time of a two-dimensional spectrum are dominated by vibrational motion and do not reflect the electron, hole, and exciton dynamics directly. We find that the fifth-order nonlinear response is particularly sensitive to the charge transfer process. While third-order 2D spectroscopy detects the correlation between two coherences, fifth-order 2D spectroscopy (2D population spectroscopy) is here designed to detect correlations between the excited states du...
Experimental Study on Coupled Cross-Flow and in-Line Vortex-Induced Vibration of Flexible Risers
Institute of Scientific and Technical Information of China (English)
GUO Hai-yan; LOU Min
2008-01-01
In this work, we study the coupled cross-flow and in-line vortex-induced vibration (VIV) of a fixedly mounted flexible pipe, which is free to move in cross-flow (Y-) and in-line (X-) direction in a fluid flow where the mass and natural frequencies are precisely the same in both X- and Y-direction. The fluid speed varies from low to high with the corresponding vortex shedding frequency varying from below the first natural frequency to above the second natural frequency of the flexible pipe. Particular emphasis was placed on the investigation of the relationship between in-line and cross-flow vibration. The experimental results analyzed by using these measurements exhibits several valuable features.
Directory of Open Access Journals (Sweden)
Pei Yang
Full Text Available G-protein coupled receptors (GPCRs are integral membrane proteins involved in a wide variety of biological processes in eukaryotic cells, and are targeted by a large fraction of marketed drugs. GPCR kinases (GRKs play important roles in feedback regulation of GPCRs, such as of β-adrenergic receptors in the heart, where GRK2 and GRK5 are the major isoforms expressed. Membrane targeting is essential for GRK function in cells. Whereas GRK2 is recruited to the membrane by heterotrimeric Gβγ subunits, the mechanism of membrane binding by GRK5 is not fully understood. It has been proposed that GRK5 is constitutively associated with membranes through elements located at its N-terminus, its C-terminus, or both. The membrane orientation of GRK5 is also a matter of speculation. In this work, we combined sum frequency generation (SFG vibrational spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR to help determine the membrane orientation of GRK5 and a C-terminally truncated mutant (GRK51-531 on membrane lipid bilayers. It was found that GRK5 and GRK51-531 adopt a similar orientation on model cell membranes in the presence of PIP2 that is similar to that predicted for GRK2 in prior studies. Mutation of the N-terminal membrane binding site of GRK5 did not eliminate membrane binding, but prevented observation of this discrete orientation. The C-terminus of GRK5 does not have substantial impact on either membrane binding or orientation in this model system. Thus, the C-terminus of GRK5 may drive membrane binding in cells via interactions with other proteins at the plasma membrane or bind in an unstructured manner to negatively charged membranes.
Coupled Vibration of Long-Span Railway Curved Girder Bridges and Vehicles
Institute of Scientific and Technical Information of China (English)
Shan Deshan; Li Qiao
2005-01-01
The structure of a long curved girder bridge is represented with a three-dimensional curved finite element model. Each 4-axle vehicle is modeled by a dynamic system of 35 degrees of freedom. The random irregularities of the track are generated from a power spectral density function under the given track condition. The dynamic interaction between the bridge and train is realized through the contact forces between the wheels and track. Then based on these models, the coupled equations of motion are solved by applying the time-integration and iteration techniques to the coupled system. The proposed formulation and the associated computer program are then applied to a real curved girder bridge. The dynamic responses of the bridge-vehicle system and the derailments and offload factors related to the riding and running safeties of vehicles are computed. The results show that the formulation presented in this paper can well predict dynamic behaviors of both bridge and train with reasonable computation efforts.
Fujihashi, Yuta; Ishizaki, Akihito
2015-01-01
In 2D electronic spectroscopy studies, long-lived quantum beats have recently been observed in photosynthetic systems, and it has been suggested that the beats are produced by quantum mechanically mixed electronic and vibrational states. Concerning the electronic-vibrational quantum mixtures, the impact of protein-induced fluctuations was examined by calculating the 2D electronic spectra of a weakly coupled dimer with vibrational modes in the resonant condition [J. Chem. Phys. 142, 212403 (2015)]. This analysis demonstrated that quantum mixtures of the vibronic resonance are rather robust under the influence of the fluctuations at cryogenic temperatures, whereas the mixtures are eradicated by the fluctuations at physiological temperatures. However, this conclusion cannot be generalized because the magnitude of the coupling inducing the quantum mixtures is proportional to the inter-pigment coupling. In this study, we explore the impact of the fluctuations on electronic-vibrational quantum mixtures in a strongl...
Standard-model coupling constants from compositeness
Besprosvany, J
2003-01-01
A coupling-constant definition is given based on the compositeness property of some particle states with respect to the elementary states of other particles. It is applied in the context of the vector-spin-1/2-particle interaction vertices of a field theory, and the standard model. The definition reproduces Weinberg's angle in a grand-unified theory. One obtains coupling values close to the experimental ones for appropriate configurations of the standard-model vector particles, at the unification scale within grand-unified models, and at the electroweak breaking scale.
Cronkhite, J. D.
1976-01-01
NASTRAN was evaluated for vibration analysis of the helicopter airframe. The first effort involved development of a NASTRAN model of the AH-1G helicopter airframe and comprehensive documentation of the model. The next effort was to assess the validity of the NASTRAN model by comparisons with static and vibration tests.
Dual coupling effective band model for polarons
Marchand, Dominic J. J.; Stamp, Philip C. E.; Berciu, Mona
2017-01-01
Nondiagonal couplings to a bosonic bath completely change polaronic dynamics, from the usual diagonally coupled paradigm of smoothly varying properties. We study, using analytic and numerical methods, a model having both diagonal Holstein and nondiagonal Su-Schrieffer-Heeger (SSH) couplings. The critical coupling found previously in the pure SSH model, at which the k =0 effective mass diverges, now becomes a transition line in the coupling constant plane—the form of the line depends on the adiabaticity parameter. Detailed results are given for the quasiparticle and ground-state properties, over a wide range of couplings and adiabaticity ratios. The new paradigm involves a destabilization, at the transition line, of the simple Holstein polaron to one with a finite ground-state momentum, but with everywhere a continuously evolving band shape. No "self-trapping transition" exists in any of these models. The physics may be understood entirely in terms of competition between different hopping terms in a simple renormalized effective band theory. The possibility of further transitions is suggested by the results.
Vibration modeling of structural fuzzy with continuous boundary
DEFF Research Database (Denmark)
Friis, Lars; Ohlrich, Mogens
2008-01-01
From experiments it is well known that the vibration response of a main structure with many attached substructures often shows more damping than structural losses in the components can account for. In practice, these substructures, which are not attached in an entirely rigid manner, behave like...... a multitude of different sprung masses each strongly resisting any motion of the main structure (master) at their base antiresonance. The “theory of structural fuzzy” is intended for modeling such high damping. In the present article the theory of fuzzy structures is briefly outlined and a method of modeling...... effect of the fuzzy with spatial memory is demonstrated by numerical simulations of a main beam structure with fuzzy attachments. It is shown that the introduction of spatial memory reduces the damping effect of the fuzzy and in certain cases the damping effect may even be eliminated completely....
Modeling and analysis of the transient vibration of camshaft in multi-cylinder diesel engine
Jie Guo; Wenping Zhang; Xinyu Zhang
2015-01-01
The dynamics and vibrations of camshaft excited by multi-follower elements are modeled and analyzed. A pushrod valve train system from a four-cylinder diesel engine is selected as the case study. The camshaft is modeled to analyze the interactions of multi-follower elements. Both the camshaft angular vibration and bending vibration are taken into consideration. Each follower element is simplified as a multi-mass system. The lumped masses are connected by the spring elements and the damping el...
Plenio, M B; Almeida, J; Huelga, S F
2013-12-21
We demonstrate that the coupling of excitonic and vibrational motion in biological complexes can provide mechanisms to explain the long-lived oscillations that have been obtained in nonlinear spectroscopic signals of different photosynthetic pigment protein complexes and we discuss the contributions of excitonic versus purely vibrational components to these oscillatory features. Considering a dimer model coupled to a structured spectral density we exemplify the fundamental aspects of the electron-phonon dynamics, and by analyzing separately the different contributions to the nonlinear signal, we show that for realistic parameter regimes purely electronic coherence is of the same order as purely vibrational coherence in the electronic ground state. Moreover, we demonstrate how the latter relies upon the excitonic interaction to manifest. These results link recently proposed microscopic, non-equilibrium mechanisms to support long lived coherence at ambient temperatures with actual experimental observations of oscillatory behaviour using 2D photon echo techniques to corroborate the fundamental importance of the interplay of electronic and vibrational degrees of freedom in the dynamics of light harvesting aggregates.
Energy Technology Data Exchange (ETDEWEB)
Plenio, M. B.; Almeida, J.; Huelga, S. F. [Institute for Theoretical Physics, Albert-Einstein-Allee 11, University Ulm, D-89069 Ulm (Germany)
2013-12-21
We demonstrate that the coupling of excitonic and vibrational motion in biological complexes can provide mechanisms to explain the long-lived oscillations that have been obtained in nonlinear spectroscopic signals of different photosynthetic pigment protein complexes and we discuss the contributions of excitonic versus purely vibrational components to these oscillatory features. Considering a dimer model coupled to a structured spectral density we exemplify the fundamental aspects of the electron-phonon dynamics, and by analyzing separately the different contributions to the nonlinear signal, we show that for realistic parameter regimes purely electronic coherence is of the same order as purely vibrational coherence in the electronic ground state. Moreover, we demonstrate how the latter relies upon the excitonic interaction to manifest. These results link recently proposed microscopic, non-equilibrium mechanisms to support long lived coherence at ambient temperatures with actual experimental observations of oscillatory behaviour using 2D photon echo techniques to corroborate the fundamental importance of the interplay of electronic and vibrational degrees of freedom in the dynamics of light harvesting aggregates.
Hampton, R. David; Whorton, Mark S.
2000-01-01
Many space science experiments need an active isolation system to provide them with the requisite microgravity environment. The isolation systems planned for use with the International Space Station have been appropriately modeled using relative position, relative velocity, and acceleration states. In theory, frequency design filters can be applied to these state-space models, in order to develop optimal H, or mixed-norm controllers with desired stability- and performance characteristics. In practice. however, the kinematic coupling among the various states can lead, through the associated frequency-weighting-filters, to conflicting demands on the Riccati design "machinery." The results can be numerically ill-conditioned regulator and estimator Riccati equations and/or reduced intuition in the design process. In addition, kinematic coupling can result in a redundancy in the demands imposed by the frequency weights. Failure properly to account for this type of coupling can lead to an unnecessary increase in controller dimensionality and, in turn, controller complexity. This paper suggests a rational approach to the assignment of frequency weighting design filters, in the presence of the kinematic coupling among states that exists in the microgravity vibration isolation problem.
An Appraisal of Coupled Climate Model Simulations
Energy Technology Data Exchange (ETDEWEB)
Sperber, K; Gleckler, P; Covey, C; Taylor, K; Bader, D; Phillips, T; Fiorino, M; Achutarao, K
2004-02-24
In 2002, the Program for Climate Model Diagnosis and Intercomparison (PCMDI) proposed the concept for a state-of-the-science appraisal of climate models to be performed approximately every two years. Motivation for this idea arose from the perceived needs of the international modeling groups and the broader climate research community to document progress more frequently than provided by the Intergovernmental Panel on Climate Change (IPCC) Assessment Reports. A committee of external reviewers, which included senior researchers from four leading international modeling centers, supported the concept by stating in its review: ''The panel enthusiastically endorses the suggestion that PCMDI develop an independent appraisal of coupled model performance every 2-3 years. This would provide a useful 'mid-course' evaluation of modeling progress in the context of larger IPCC and national assessment activities, and should include both coupled and single-component model evaluations.''
Fractional dynamical model for neurovascular coupling
Belkhatir, Zehor
2014-08-01
The neurovascular coupling is a key mechanism linking the neural activity to the hemodynamic behavior. Modeling of this coupling is very important to understand the brain function but it is at the same time very complex due to the complexity of the involved phenomena. Many studies have reported a time delay between the neural activity and the cerebral blood flow, which has been described by adding a delay parameter in some of the existing models. An alternative approach is proposed in this paper, where a fractional system is used to model the neurovascular coupling. Thanks to its nonlocal property, a fractional derivative is suitable for modeling the phenomena with delay. The proposed model is coupled with the first version of the well-known balloon model, which relates the cerebral blood flow to the Blood Oxygen Level Dependent (BOLD) signal measured using functional Magnetic Resonance Imaging (fMRI). Through some numerical simulations, the properties of the fractional model are explained and some preliminary comparisons to a real BOLD data set are provided. © 2014 IEEE.
Hot rolling mill horizontal-vertical coupling vibration%热连轧机横向-垂向耦合振动研究
Institute of Scientific and Technical Information of China (English)
范小彬; 臧勇
2011-01-01
In order to study the vibration of a hot strip mill,according to stick-slip rolling interface friction features and the contact non-linearity between roller bearing and mill stand,the horizontal - vertical vibration model of modal coupling was established when the gap between roller bearing and mill stand appearing. It shows that when the system stiffness and the excitation frequency is in a certain section,the amplitude of horizontal and vertical vibration fluctuated sharply. So in rolling production, it should avoid this range. When the clearance appearing, the roller jump vibration occurs, roller lateral response curve has a clear cut top and its dynamic performance becomes worse.%为了研究某热连轧机组的振动特性,根据轧制界面粘滑摩擦特性和轧辊轴承座-牌坊接触非线性,建立轧辊-轴承座有无间隙时的轧辊横-垂向模态耦合振动模型.分析表明,当系统刚度和外激励频率处于某区段时轧辊横向和垂向振动幅值均出现大幅波动的现象,轧制生产中应避开此范围;机座有间隙时,轧辊出现跳振,轧辊横向响应曲线有明显的削顶现象,辊系动力学性能变差.
Mixed finite element models for free vibrations of thin-walled beams
Noor, Ahmed K.; Peters, Jeanne M.; Min, Byung-Jin
1989-01-01
Simple, mixed finite element models are developed for the free vibration analysis of curved thin-walled beams with arbitrary open cross section. The analytical formulation is based on a Vlasov's type thin-walled beam theory with the effects of flexural-torsional coupling, transverse shear deformation and rotary inertia included. The fundamental unknowns consist of seven internal forces and seven generalized displacements of the beam. The element characteristic arrays are obtained by using a perturbed Lagrangian-mixed variational principle. Only C(sup o) continuity is required for the generalized displacements. The internal forces and the Lagrange multiplier are allowed to be discontinuous at interelement boundaries. Numerical results are presented to demonstrate the high accuracy and effectiveness of the elements developed. The standard of comparison is taken to be the solutions obtained by using 2-D plate/shell models for the beams.
Analysis of an algebraic model for the chromophore vibrations of CF$_3$CHFI
Jung, C; Taylor, H S
2004-01-01
We extract the dynamics implicit in an algebraic fitted model Hamiltonian for the hydrogen chromophore's vibrational motion in the molecule $CF_3CHFI$. The original model has 4 degrees of freedom, three positions and one representing interbond couplings. A conserved polyad allows the reduction to 3 degrees of freedom. For most quantum states we can identify the underlying motion that when quantized gives the said state. Most of the classifications, identifications and assignments are done by visual inspection of the already available wave function semiclassically transformed from the number representation to a representation on the reduced dimension toroidal configuration space corresponding to the classical action and angle variables. The concentration of the wave function density to lower dimensional subsets centered on idealized simple lower dimensional organizing structures and the behavior of the phase along such organizing centers already reveals the atomic motion. Extremely little computational work is...
Venuti, Fiammetta; Racic, Vitomir; Corbetta, Alessandro
2016-09-01
After 15 years of active research on the interaction between moving people and civil engineering structures, there is still a lack of reliable models and adequate design guidelines pertinent to vibration serviceability of footbridges due to multiple pedestrians. There are three key issues that a new generation of models should urgently address: pedestrian "intelligent" interaction with the surrounding people and environment, effect of human bodies on dynamic properties of unoccupied structure and inter-subject and intra-subject variability of pedestrian walking loads. This paper presents a modelling framework of human-structure interaction in the vertical direction which addresses all three issues. The framework comprises two main models: (1) a microscopic model of multiple pedestrian traffic that simulates time varying position and velocity of each individual pedestrian on the footbridge deck, and (2) a coupled dynamic model of a footbridge and multiple walking pedestrians. The footbridge is modelled as a SDOF system having the dynamic properties of the unoccupied structure. Each walking pedestrian in a group or crowd is modelled as a SDOF system with an adjacent stochastic vertical force that moves along the footbridge following the trajectory and the gait pattern simulated by the microscopic model of pedestrian traffic. Performance of the suggested modelling framework is illustrated by a series of simulated vibration responses of a virtual footbridge due to light, medium and dense pedestrian traffic. Moreover, the Weibull distribution is shown to fit well the probability density function of the local peaks in the acceleration response. Considering the inherent randomness of the crowd, this makes it possible to determine the probability of exceeding any given acceleration value of the occupied bridge.
Vibration Analysis of Rotating Tapered Timoshenko Beams by a New Finite Element Model
Directory of Open Access Journals (Sweden)
Bulent Yardimoglu
2006-01-01
Full Text Available A new finite element model is developed and subsequently used for transverse vibrations of tapered Timoshenko beams with rectangular cross-section. The displacement functions of the finite element are derived from the coupled displacement field (the polynomial coefficients of transverse displacement and cross-sectional rotation are coupled through consideration of the differential equations of equilibrium approach by considering the tapering functions of breadth and depth of the beam. This procedure reduces the number of nodal variables. The new model can also be used for uniform beams. The stiffness and mass matrices of the finite element model are expressed by using the energy equations. To confirm the accuracy, efficiency, and versatility of the new model, a semi-symbolic computer program in MATLAB® is developed. As illustrative examples, the bending natural frequencies of non-rotating/rotating uniform and tapered Timoshenko beams are obtained and compared with previously published results and the results obtained from the finite element models of solids created in ABAQUS. Excellent agreement is found between the results of new finite element model and the other results.
Institute of Scientific and Technical Information of China (English)
张明金; 李永乐; 汪斌
2016-01-01
In a wind-vehicle-bridge (WVB) system, there are various interactions among wind, vehicle and bridge. The mechanism for coupling vibration of wind-vehicle-bridge systems is explored to demonstrate the effects of fundamental factors, such as mean wind, fluctuating wind, buffeting, rail irregularities, light rail vehicle vibration and bridge stiffness. A long cable-stayed bridge which carries light rail traffic is regarded as a numerical example. Firstly, a finite element model is built for the long cable-stayed bridge. The deck can generally be idealized as three-dimensional spine beam while cables are modeled as truss elements. Vehicles are modeled as mass-spring-damper systems. Rail irregularities and wind fluctuation are simulated in time domain by spectrum representation method. Then, aerodynamic loads on vehicle and bridge deck are measured by section model wind tunnel tests. Eight vertical and torsional flutter derivatives of bridge deck are identified by weighting ensemble least-square method. Finally, dynamic responses of the WVB system are analyzed in a series of cases. The results show that the accelerations of the vehicle are excited by the fluctuating wind and the track irregularity to a great extent. The transverse forces of wheel axles mainly depend on the track irregularity. The displacements of the bridge are predominantly determined by the mean wind and restricted by its stiffness. And the accelerations of the bridge are enlarged after adding the fluctuating wind.
Application of coupled analysis methods for prediction of blast-induced dominant vibration frequency
Li, Haibo; Li, Xiaofeng; Li, Jianchun; Xia, Xiang; Wang, Xiaowei
2016-03-01
Blast-induced dominant vibration frequency (DVF) involves a complex, nonlinear and small sample system considering rock properties, blasting parameters and topography. In this study, a combination of grey relational analysis and dimensional analysis procedures for prediction of dominant vibration frequency are presented. Six factors are selected from extensive effect factor sequences based on grey relational analysis, and then a novel blast-induced dominant vibration frequency prediction is obtained by dimensional analysis. In addition, the prediction is simplified by sensitivity analysis with 195 experimental blast records. Validation is carried out for the proposed formula based on the site test database of the firstperiod blasting excavation in the Guangdong Lufeng Nuclear Power Plant (GLNPP). The results show the proposed approach has a higher fitting degree and smaller mean error when compared with traditional predictions.
Ultrafast Relaxation Dynamics of Photoexcited Zinc-Porphyrin: Electronic-Vibrational Coupling.
Abraham, Baxter; Nieto-Pescador, Jesus; Gundlach, Lars
2016-08-18
Cyclic tetrapyrroles are the active core of compounds with crucial roles in living systems, such as hemoglobin and chlorophyll, and in technology as photocatalysts and light absorbers for solar energy conversion. Zinc-tetraphenylporphyrin (Zn-TPP) is a prototypical cyclic tetrapyrrole that has been intensely studied in past decades. Because of its importance for photochemical processes the optical properties are of particular interest, and, accordingly, numerous studies have focused on light absorption and excited-state dynamics of Zn-TPP. Relaxation after photoexcitation in the Soret band involves internal conversion that is preceded by an ultrafast process. This relaxation process has been observed by several groups. Hitherto, it has not been established if it involves a higher lying "dark" state or vibrational relaxation in the excited S2 state. Here we combine high time resolution electronic and vibrational spectroscopy to show that this process constitutes vibrational relaxation in the anharmonic S2 potential.
Ambient vibrations of unstable rock slopes - insights from numerical modeling
Burjanek, Jan; Kleinbrod, Ulrike; Fäh, Donat
2017-04-01
The recent events in Nepal (2015 M7.8 Gorkha) and New Zealand (2016 M7.8 Kaikoura) highlighted the importance of earthquake-induced landslides, which caused significant damages. Moreover, landslide created dams present a potential developing hazard. In order to reduce the costly consequences of such events it is important to detect and characterize earthquake susceptible rock slope instabilities before an event, and to take mitigation measures. For the characterisation of instable slopes, acquisition of ambient vibrations might be a new alternative to the already existing methods. We present both observations and 3D numerical simulations of the ambient vibrations of unstable slopes. In particular, models of representative real sites have been developed based on detailed terrain mapping and used for the comparison between synthetics and observations. A finite-difference code has been adopted for the seismic wave propagation in a 3D inhomogeneous visco-elastic media with irregular free surface. It utilizes a curvilinear grid for a precise modeling of curved topography and local mesh refinement to make computational mesh finer near the free surface. Topographic site effects, controlled merely by the shape of the topography, do not explain the observed seismic response. In contrast, steeply-dipping compliant fractures have been found to play a key role in fitting observations. Notably, the synthetized response is controlled by inertial mass of the unstable rock, and by stiffness, depth and network density of the fractures. The developed models fit observed extreme amplification levels (factors of 70!) and show directionality as well. This represents a possibility to characterize slope structure and infer depth or volume of the slope instability from the ambient noise recordings in the future.
Modeling of Coupled Nano-Cavity Lasers
DEFF Research Database (Denmark)
Skovgård, Troels Suhr
Modeling of nanocavity light emitting semiconductor devices is done using the semiconductor laser rate equations with spontaneous and stimulated emission terms modified for Purcell enhanced recombination. The modified terms include details about the optical and electronic density......, coupled photonic crystal nanocavity structures are simulated. The resonance frequencies of in-phase and out-of-phase coupled quadrupole modes in rectangular photonic crystal H1 cavities are extracted and are found to vary non-trivially with the intercavity separation. A qualitative explanation is given...... in terms of the in-plane mode profiles. Fareld emission patterns for the structures are calculated based on the finite-dierence time-domain simulations. It is found that only systems with an even number of holes separating the cavities show clear signs of being coupled. This non-trivial coupling behavior...
Institute of Scientific and Technical Information of China (English)
叶拥拥; 叶林昌; 张栋; 沈建平
2012-01-01
以LS型高弹性联轴器作为研究对象,采用软件仿真与试验验证相结合的方法对高弹性联轴器隔振性能预测技术进行了研究。基于有限元理论提出了高弹性联轴器隔振性能计算评估方法,计算分析了弹性联轴器的模态特性和隔振性能。通过试验研究得到高弹的模态频率、振型及隔振性能曲线。计算值与实测值吻合较好,验证了高弹性联轴器隔振性能有限元评估方法的可行性。%Choosing the LStype flexible coupling as the research object, the forecast technologies of the vibration isolation performance for high flexible couplings were researched by combining software simula tion and test validation. The estimation methods of the vibration isolation performance for flexible cou plings were given based on the finite element theory. The modal feature and vibration isolation perform ance of the flexible couplings were computed and analyzed. The modal frequency, vibration model and vibration isolation performance curve of the flexible couplings were gained by research on the test results. The simulation and test results coincide well with each other, thus verifies the feasibility of the finite ele ment estimation methods for the flexible coupling.
Vibrational Spectroscopy of Methyl benzoate
Maiti, Kiran Sankar
2014-01-01
Methyl benzoate (MB) is studied as a model compound for the development of new IR pulse schemes with possible applicability to biomolecules. Anharmonic vibrational modes of MB are calculated on different level (MP2, SCS, CCSD(T) with varying basis sets) ab-initio PESs using the vibrational self-consistent field (VSCF) method and its correlation corrected extensions. Dual level schemes, combining different quantum chemical methods for diagonal and coupling potentials, are systematically studied and applied successfully to reduce the computational cost. Isotopic substitution of {\\beta}-hydrogen by deuterium is studied to obtain a better understanding of the molecular vibrational coupling topology.
Pietanza, L. D.; Colonna, G.; D'Ammando, G.; Capitelli, M.
2017-01-01
A time-dependent self-consistent model based on the coupling of the Boltzmann equation for the electron energy distribution function (EEDF) with the non-equilibrium vibrational kinetics of the asymmetric mode, as well as a simplified global model, have been implemented for a pure CO2 plasma. The simplified time-dependent global model takes into account dissociation and ionization as well as the reverse of these processes. It also takes into account the excitation/de-excitation of an electronic excited state at 10.5 eV. The model has been applied to describe the discharge and post-discharge conditions typically met in an atmospheric-pressure dielectric barrier discharge (DBD) and in a moderate-pressure microwave discharge. The reported results show the strong coupling between the excited state and the electron energy distribution kinetics due to superelastic (vibrational and electronic) collisions. Moreover, the dissociation rate from a pure vibrational mechanism can become competitive with the corresponding rate from the direct electron impact mechanism at high values of vibrational temperature.
Woys, Ann Marie; Almeida, Aaron M; Wang, Lu; Chiu, Chi-Cheng; McGovern, Michael; de Pablo, Juan J; Skinner, James L; Gellman, Samuel H; Zanni, Martin T
2012-11-21
Infrared spectroscopy is playing an important role in the elucidation of amyloid fiber formation, but the coupling models that link spectra to structure are not well tested for parallel β-sheets. Using a synthetic macrocycle that enforces a two stranded parallel β-sheet conformation, we measured the lifetimes and frequency for six combinations of doubly (13)C═(18)O labeled amide I modes using 2D IR spectroscopy. The average vibrational lifetime of the isotope labeled residues was 550 fs. The frequencies of the labels ranged from 1585 to 1595 cm(-1), with the largest frequency shift occurring for in-register amino acids. The 2D IR spectra of the coupled isotope labels were calculated from molecular dynamics simulations of a series of macrocycle structures generated from replica exchange dynamics to fully sample the conformational distribution. The models used to simulate the spectra include through-space coupling, through-bond coupling, and local frequency shifts caused by environment electrostatics and hydrogen bonding. The calculated spectra predict the line widths and frequencies nearly quantitatively. Historically, the characteristic features of β-sheet infrared spectra have been attributed to through-space couplings such as transition dipole coupling. We find that frequency shifts of the local carbonyl groups due to nearest neighbor couplings and environmental factors are more important, while the through-space couplings dictate the spectral intensities. As a result, the characteristic absorption spectra empirically used for decades to assign parallel β-sheet secondary structure arises because of a redistribution of oscillator strength, but the through-space couplings do not themselves dramatically alter the frequency distribution of eigenstates much more than already exists in random coil structures. Moreover, solvent exposed residues have amide I bands with >20 cm(-1) line width. Narrower line widths indicate that the amide I backbone is solvent
Yuan, G.; Wang, D. H.
2017-03-01
Multi-directional and multi-degree-of-freedom (multi-DOF) vibration energy harvesting are attracting more and more research interest in recent years. In this paper, the principle of a piezoelectric six-DOF vibration energy harvester based on parallel mechanism is proposed to convert the energy of the six-DOF vibration to single-DOF vibrations of the limbs on the energy harvester and output voltages. The dynamic model of the piezoelectric six-DOF vibration energy harvester is established to estimate the vibrations of the limbs. On this basis, a Stewart-type piezoelectric six-DOF vibration energy harvester is developed and explored. In order to validate the established dynamic model and the analysis results, the simulation model of the Stewart-type piezoelectric six-DOF vibration energy harvester is built and tested with different vibration excitations by SimMechanics, and some preliminary experiments are carried out. The results show that the vibration of the limbs on the piezoelectric six-DOF vibration energy harvester can be estimated by the established dynamic model. The developed Stewart-type piezoelectric six-DOF vibration energy harvester can harvest the energy of multi-directional linear vibration and multi-axis rotating vibration with resonance frequencies of 17 Hz, 25 Hz, and 47 Hz. Moreover, the resonance frequencies of the developed piezoelectric six-DOF vibration energy harvester are not affected by the direction changing of the vibration excitation.
Playing with fermion couplings in Higgsless models
Casalbuoni, R; Dolce, D; Dominici, Daniele
2005-01-01
We discuss the fermion couplings in a four dimensional SU(2) linear moose model by allowing for direct couplings between the left-handed fermions on the boundary and the gauge fields in the internal sites. This is realized by means of a product of non linear $\\sigma$-model scalar fields which, in the continuum limit, is equivalent to a Wilson line. The effect of these new non local couplings is a contribution to the $\\epsilon_3$ parameter which can be of opposite sign with respect to the one coming from the gauge fields along the string. Therefore, with some fine tuning, it is possible to satisfy the constraints from the electroweak data.
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Multi-motor vibratory transmission systems have been wide used in large vibratory machines, and four-motor linear vibratory machine is one typical equipment of them. Under non-forcible synchronization condition zero-phase synchronization of the machine is non-stationary and π-phase synchronization is stable. Under half-forcible synchronization condition in which only one motor is controlled being synchronous to another, only lag synchronization near zero-phase synchronization can be realized. Both of the characteristics have never been revealed with classical theory quantitatively. The problem is solved by means of establishing an electromechanical coupling mathematical model of the system and numerical analysis of the starting processes.
DEFF Research Database (Denmark)
Kiel, Nikolaj; Andersen, Lars Vabbersgaard; Niu, Bin
2012-01-01
As a result of the increasing interest of constructing environmentally friendly lightweight buildings, analyses of vibrational and acoustical transmission in these buildings have become increasingly important. Structures where vibrational transmission may result in undesirable vibrations....... With the number of modules in the three axial directions defined, wall and floor panels are constructed, placed and coupled in the global model. The core of this modular finite element model consists of connecting the different panels to each other in a rational manner, where the accuracy is as high as possible...... of a similar construction without a skeleton. These parameters are selected in a way where decoupled pseudo-modes of the skeleton are avoided, alongside the insignificant influence of the overall structure achieved with a low mass, small profile, and a relatively low Young's modulus, approximately 1...
Nicolas, Maxime
2016-01-01
Engineering school; This course is designed for students of Polytech Marseille, engineering school. It covers first the physics of vibration of the harmonic oscillator with damping and forcing, coupled oscillators. After a presentation of the wave equation, the vibration of strings, beams and membranes are studied.
Vibration enhanced quantum transport
Semião, F L; Milburn, G J
2009-01-01
In this paper, we study the role of a collective vibrational motion in the phenomenon of electronic energy transfer (EET) between chromophores with different electronic transition frequencies. Previous experimental work on EET in conjugated polymer samples has suggested that the common structural framework of the macromolecule introduce correlations in the energy gap fluctuations which cause coherent EET. We present a simple model describing the coupling between the chromophores and a common vibrational mode, and find that vibration can indeed lead to an enhancement in the transport of excitations across the quantum network. Furthermore, in our model phase information is partially retained in the transfer process from a donor to an acceptor, as experimentally demonstrated in the conjugated polymer system. Consequently, this mechanism of vibration enhanced quantum transport might find applications in quantum information transfer of qubit states or entanglement.
Lenci, Stefano; Rega, Giuseppe
2016-06-01
The nonlinear free oscillations of a straight planar Timoshenko beam are investigated analytically by means of the asymptotic development method. Attention is focused for the first time, to the best of our knowledge, on the nonlinear coupling between the axial and the transversal oscillations of the beam, which are decoupled in the linear regime. The existence of coupled and uncoupled motion is discussed. Furthermore, the softening versus hardening nature of the backbone curves is investigated in depth. The results are summarized by means of behaviour charts that illustrate the different possible classes of motion in the parameter space. New, and partially unexpected, phenomena, such as the changing of the nonlinear behaviour from softening to hardening by adding/removing the axial vibrations, are highlighted.
Niu, Y F; Vigezzi, E; Bai, C L; Sagawa, H
2016-01-01
We propose a self-consistent quasi-particle random phase approximation (QRPA) plus quasi-particle-vibration coupling (QPVC) model with Skyrme interactions to describe the width and the line shape of giant resonances in open-shell nuclei, in which the effect of superfluidity should be taken into account in both the ground state and the excited states. We apply the new model to the Gamow-Teller resonance in the superfluid nucleus $^{120}$Sn, including both the isoscalar spin-triplet and the isovector spin-singlet pairing interactions. The strength distribution in $^{120}$Sn is well reproduced and the underlying microscopic mechanisms, related to QPVC and also to isoscalar pairing, are analyzed in detail.
Reheating in nonminimal derivative coupling model
Sadjadi, H Mohseni
2012-01-01
We consider a model with nonminimal derivative coupling of inflaton to gravity. The reheating process during rapid oscillation of the inflaton is studied and the reheating temperature is obtained. Behaviors of the inflaton and produced radiation in this era are discussed.
Holliday, Ezekiel S. (Inventor)
2014-01-01
Vibrations at harmonic frequencies are reduced by injecting harmonic balancing signals into the armature of a linear motor/alternator coupled to a Stirling machine. The vibrations are sensed to provide a signal representing the mechanical vibrations. A harmonic balancing signal is generated for selected harmonics of the operating frequency by processing the sensed vibration signal with adaptive filter algorithms of adaptive filters for each harmonic. Reference inputs for each harmonic are applied to the adaptive filter algorithms at the frequency of the selected harmonic. The harmonic balancing signals for all of the harmonics are summed with a principal control signal. The harmonic balancing signals modify the principal electrical drive voltage and drive the motor/alternator with a drive voltage component in opposition to the vibration at each harmonic.
Parallelization of the Coupled Earthquake Model
Block, Gary; Li, P. Peggy; Song, Yuhe T.
2007-01-01
This Web-based tsunami simulation system allows users to remotely run a model on JPL s supercomputers for a given undersea earthquake. At the time of this reporting, predicting tsunamis on the Internet has never happened before. This new code directly couples the earthquake model and the ocean model on parallel computers and improves simulation speed. Seismometers can only detect information from earthquakes; they cannot detect whether or not a tsunami may occur as a result of the earthquake. When earthquake-tsunami models are coupled with the improved computational speed of modern, high-performance computers and constrained by remotely sensed data, they are able to provide early warnings for those coastal regions at risk. The software is capable of testing NASA s satellite observations of tsunamis. It has been successfully tested for several historical tsunamis, has passed all alpha and beta testing, and is well documented for users.
Directory of Open Access Journals (Sweden)
Pan Fang
Full Text Available A new mechanism is proposed to implement synchronization of the two unbalanced rotors in a vibration system, which consists of a double vibro-body, two induction motors and spring foundations. The coupling relationship between the vibro-bodies is ascertained with the Laplace transformation method for the dynamics equation of the system obtained with the Lagrange's equation. An analytical approach, the average method of modified small parameters, is employed to study the synchronization characteristics between the two unbalanced rotors, which is converted into that of existence and the stability of zero solutions for the non-dimensional differential equations of the angular velocity disturbance parameters. By assuming the disturbance parameters that infinitely approach to zero, the synchronization condition for the two rotors is obtained. It indicated that the absolute value of the residual torque between the two motors should be equal to or less than the maximum of their coupling torques. Meanwhile, the stability criterion of synchronization is derived with the Routh-Hurwitz method, and the region of the stable phase difference is confirmed. At last, computer simulations are preformed to verify the correctness of the approximate solution of the theoretical computation for the stable phase difference between the two unbalanced rotors, and the results of theoretical computation is in accordance with that of computer simulations. To sum up, only the parameters of the vibration system satisfy the synchronization condition and the stability criterion of the synchronization, the two unbalanced rotors can implement the synchronization operation.
Cost-effective and detailed modelling of compressor manifold vibrations
Eijk, A.; Egas, G.; Smeulers, J.P.M.
1996-01-01
In systems with large reciprocating compressors, so-called compressor manifold vibrations can contribute to fatigue failure of the pipe system. These vibrations are excited by pulsation-induced forces and by forces generated by the compressor. This paper describes an advanced and accurate method for
Modeling vibrational resonance in linear hydrocarbon chain with a mixed quantum-classical method.
Gelman, David; Schwartz, Steven D
2009-04-07
The quantum dynamics of a vibrational excitation in a linear hydrocarbon model system is studied with a new mixed quantum-classical method. The method is suited to treat many-body systems consisting of a low dimensional quantum primary part coupled to a classical bath. The dynamics of the primary part is governed by the quantum corrected propagator, with the corrections defined in terms of matrix elements of zeroth order propagators. The corrections are taken to the classical limit by introducing the frozen Gaussian approximation for the bath degrees of freedom. The ability of the method to describe dynamics of multidimensional systems has been tested. The results obtained by the method have been compared to previous quantum simulations performed with the quasiadiabatic path integral method.
VCD Robustness of the Amide-I and Amide-II Vibrational Modes of Small Peptide Models.
Góbi, Sándor; Magyarfalvi, Gábor; Tarczay, György
2015-09-01
The rotational strengths and the robustness values of amide-I and amide-II vibrational modes of For(AA)n NHMe (where AA is Val, Asn, Asp, or Cys, n = 1-5 for Val and Asn; n = 1 for Asp and Cys) model peptides with α-helix and β-sheet backbone conformations were computed by density functional methods. The robustness results verify empirical rules drawn from experiments and from computed rotational strengths linking amide-I and amide-II patterns in the vibrational circular dichroism (VCD) spectra of peptides with their backbone structures. For peptides with at least three residues (n ≥ 3) these characteristic patterns from coupled amide vibrational modes have robust signatures. For shorter peptide models many vibrational modes are nonrobust, and the robust modes can be dependent on the residues or on their side chain conformations in addition to backbone conformations. These robust VCD bands, however, provide information for the detailed structural analysis of these smaller systems.
Coupling GIS with Nitrogen Leaching Models
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Geographical information systems (GIS) are increasingly being applied to surface and subsurface flow and transport modeling issues. In this paper, more attentions are focused on the methodology and strategies of coupling GIS with non-point pollution models. Suggestions are made on how to best integrate current available or selected nitrogen leaching models, especially in the aspect of programming development so as to effectively and flexibly address the specific tasks. The new possibilities for dealing with non-point pollution problems at a regional scale are provided in the resulting integrated approach, including embedding grid-based GIS components in models.
Institute of Scientific and Technical Information of China (English)
Samad Mehrzad; Ilgar Javanshir; Ahmad Rahbar Ranji; Seyyed Hadi Taheri
2015-01-01
Dynamics and vibration of control valves under flow-induced vibration are analyzed. Hydrodynamic load characteristics and structural response under flow-induced vibration are mainly influenced by inertia, damping, elastic, geometric characteristics and hydraulic parameters. The purpose of this work is to investigate the dynamic behavior of control valves in the response to self-excited fluid flow. An analytical and numerical method is developed to simulate the dynamic and vibrational behavior of sliding dam valves, in response to flow excitation. In order to demonstrate the effectiveness of proposed model, the simulation results are validated with experimental ones. Finally, to achieve the optimal valve geometry, numerical results for various shapes of valves are compared. Rounded valve with the least amount of flow turbulence obtains lower fluctuations and vibration amplitude compared with the flat and steep valves. Simulation results demonstrate that with the optimal design requirements of valves, vibration amplitude can be reduced by an average to 30%.
Vibrations of liquid drops in film boiling phenomena: the mathematical model
Casal, Pierre
2008-01-01
Flattened liquid drops poured on a very hot surface evaporate quite slowly and float on a film of their own vapour. In the cavities of a surface, an unusual type of vibrational motions occurs. Large vibrations take place and different forms of dynamic drops are possible. They form elliptic patterns with two lobes or hypotrochoid patterns with three lobes or more. The lobes are turning relatively to the hot surface. We present a model of vibrating motions of the drops. Frequencies of the vibrations are calculated regarding the number of lobes. The computations agree with experiments.
Institute of Scientific and Technical Information of China (English)
XIAO Yong-gang; FU Yi-ming; ZHA Xu-dong
2005-01-01
Based on Reissner plate theory and Hamilton variational principle, the nonlinear equations of motion were derived for the moderate thickness rectangular plates with transverse surface penetrating crack on the two-parameter foundation. Under the condition of free boundary, a set of trial functions satisfying all boundary conditions and crack's continuous conditions were proposed. By employing the Galerkin method and the harmonic balance method, the nonlinear vibration equations were solved and the nonlinear vibration behaviors of the plate were analyzed. In numerical computation, the effects of the different location and depth of crack, the different structural parameters of plates and the different physical parameters of foundation on the nonlinear amplitude frequency response curves of the plate were discussed.
Ning, Fuda; Wang, Hui; Cong, Weilong; Fernando, P K S C
2017-04-01
Rotary ultrasonic machining (RUM) has been investigated in machining of brittle, ductile, as well as composite materials. Ultrasonic vibration amplitude, as one of the most important input variables, affects almost all the output variables in RUM. Numerous investigations on measuring ultrasonic vibration amplitude without RUM machining have been reported. In recent years, ultrasonic vibration amplitude measurement with RUM of ductile materials has been investigated. It is found that the ultrasonic vibration amplitude with RUM was different from that without RUM under the same input variables. RUM is primarily used in machining of brittle materials through brittle fracture removal. With this reason, the method for measuring ultrasonic vibration amplitude in RUM of ductile materials is not feasible for measuring that in RUM of brittle materials. However, there are no reported methods for measuring ultrasonic vibration amplitude in RUM of brittle materials. In this study, ultrasonic vibration amplitude in RUM of brittle materials is investigated by establishing a mechanistic amplitude model through cutting force. Pilot experiments are conducted to validate the calculation model. The results show that there are no significant differences between amplitude values calculated by model and those obtained from experimental investigations. The model can provide a relationship between ultrasonic vibration amplitude and input variables, which is a foundation for building models to predict other output variables in RUM.
Coupled Seepage and Heat Transfer Intake Model
Institute of Scientific and Technical Information of China (English)
WU Junhua; YOU Shijun; ZHANG Huan; LI Haishan
2009-01-01
In the beach well intake system, heat is transferred from soil to fluid when seawater is filtered through the aquifer, providing higher temperature source water to the seawater source heat pump (SWHP) system in winter. A 3-D coupled seepage and heat transfer model for studying beach well intake system is established by adopting the computer code FLUENT. Numerical results of this model are compared with the experimental results under the same conditions. Based on the experiment-verified coupled model, numerical simulation of the supply water temperature is studied over a heating season. Results show that the minimum temperature of supply water is 275.2 K when this intake system continuously provides seawater with flow rate of 35 m3/h to SWHP. Results also indicate that the supply water temperature is higher than seawater, and that the minimum temperature of supply water lags behind seawater, ensuring effective and reliable operation of SWHP.
Institute of Scientific and Technical Information of China (English)
额尔敦朝鲁; 乌云其木格; 肖欣; 韩超; 辛伟
2012-01-01
Based on the Huybrechts＇ linear-combination operator, effects of thermal lattice vibration on the effective potential of weak-coupling bipolaron in semiconductor quantum dots are studied by using the LLP variational method and quantum statistical theory. The results show that the absolute value of the induced potential of the bipolaron increases with increasing the electron-phonon coupling strength, but decreases with increasing the temperature and the distance of electrons, respectively; the absolute value of the effective potential increases with increasing the radius of the quantum dot, electron-phonon coupling strength and the distance of electrons, respectively, but decreases with increasing the temperature; the temperature and electron-phonon interaction have the important influence on the formation and state properties of the bipolaron： the bipolarons in the bound state are closer and more stable when the electron-phonon coupling strength is larger or the temperature is lower; the confinement potential and coulomb repulsive potential between electrons are unfavorable to the formation of bipolarons in the bound state.
2006-01-01
This paper presents the methodology for the energy flow analysis of coupled Timoshenko beam structures and various numerical applications to verify the developed methodology. To extend the application of the energy flow model for corrected flexural waves in the Timoshenko beam, which is developed in the other companion paper, to coupled structures, the wave transmission analyses of general coupled Timoshenko beam systems are performed. First, power transmission and reflection coefficients for...
Directory of Open Access Journals (Sweden)
Daniel Zurita-Millán
2016-01-01
Full Text Available Vibration monitoring plays a key role in the industrial machinery reliability since it allows enhancing the performance of the machinery under supervision through the detection of failure modes. Thus, vibration monitoring schemes that give information regarding future condition, that is, prognosis approaches, are of growing interest for the scientific and industrial communities. This work proposes a vibration signal prognosis methodology, applied to a rotating electromechanical system and its associated kinematic chain. The method combines the adaptability of neurofuzzy modeling with a signal decomposition strategy to model the patterns of the vibrations signal under different fault scenarios. The model tuning is performed by means of Genetic Algorithms along with a correlation based interval selection procedure. The performance and effectiveness of the proposed method are validated experimentally with an electromechanical test bench containing a kinematic chain. The results of the study indicate the suitability of the method for vibration forecasting in complex electromechanical systems and their associated kinematic chains.
Active control of structural vibration with on-line secondary path modeling
Institute of Scientific and Technical Information of China (English)
YANG Tiejun; GU Zhongquan
2004-01-01
An active control strategy with on-line secondary path modeling is proposed and applied in active control of helicopter structural vibration. Computer simulations of the secondary path modeling performance demonstrate the superiorities of the active control strategy. A 2-input 4-output active control simulation for a helicopter model is performed and great reduction of structural vibration is achieved. 2-input 2-output and 2-input 4-output experimental studies of structural vibration control for a free-free beam are also carried out in laboratory to simulate a flying helicopter. The experimental results also show better reduction of the structural vibration, which verifies that the proposed method is effective and practical in structural vibration reduction.
Model of Head-Positioning Error Due to Rotational Vibration of Hard Disk Drives
Matsuda, Yasuhiro; Yamaguchi, Takashi; Saegusa, Shozo; Shimizu, Toshihiko; Hamaguchi, Tetsuya
An analytical model of head-positioning error due to rotational vibration of a hard disk drive is proposed. The model takes into account the rotational vibration of the base plate caused by the reaction force of the head-positioning actuator, the relationship between the rotational vibration and head-track offset, and the sensitivity function of track-following feedback control. Error calculated by the model agrees well with measured error. It is thus concluded that this model can predict the data transfer performance of a disk drive in read mode.
Implementation of a vibrationally linked chemical reaction model for DSMC
Carlson, A. B.; Bird, Graeme A.
1994-01-01
A new procedure closely linking dissociation and exchange reactions in air to the vibrational levels of the diatomic molecules has been implemented in both one- and two-dimensional versions of Direct Simulation Monte Carlo (DSMC) programs. The previous modeling of chemical reactions with DSMC was based on the continuum reaction rates for the various possible reactions. The new method is more closely related to the actual physics of dissociation and is more appropriate to the particle nature of DSMC. Two cases are presented: the relaxation to equilibrium of undissociated air initially at 10,000 K, and the axisymmetric calculation of shuttle forebody heating during reentry at 92.35 km and 7500 m/s. Although reaction rates are not used in determining the dissociations or exchange reactions, the new method produces rates which agree astonishingly well with the published rates derived from experiment. The results for gas properties and surface properties also agree well with the results produced by earlier DSMC models, equilibrium air calculations, and experiment.
Energy flow analysis of out-of-plane vibration in coplanar coupled finite Mindlin plates
Directory of Open Access Journals (Sweden)
Park Young-Ho
2015-01-01
Full Text Available In this paper, an Energy Flow Analysis (EFA for coplanar coupled Mindlin plates was performed to estimate their dynamic responses at high frequencies. Mindlin plate theory can consider the effects of shear distortion and rotatory inertia, which are very important at high frequencies. For EFA for coplanar coupled Mindlin plates, the wave transmission and reflection relationship for progressing out-of-plane waves (out-of-plane shear wave, bending dominant flexural wave, and shear dominant flexural wave in coplanar coupled Mindlin plates was newly derived. To verify the validity of the EFA results, numerical analyses were performed for various cases where coplanar coupled Mindlin plates are excited by a harmonic point force, and the energy flow solutions for coplanar coupled Mindlin plates were compared with the classical solutions in the various conditions.
Directory of Open Access Journals (Sweden)
Peng Guo
2012-12-01
Full Text Available With appropriate vibration modeling and analysis the incipient failure of key components such as the tower, drive train and rotor of a large wind turbine can be detected. In this paper, the Nonlinear State Estimation Technique (NSET has been applied to model turbine tower vibration to good effect, providing an understanding of the tower vibration dynamic characteristics and the main factors influencing these. The developed tower vibration model comprises two different parts: a sub-model used for below rated wind speed; and another for above rated wind speed. Supervisory control and data acquisition system (SCADA data from a single wind turbine collected from March to April 2006 is used in the modeling. Model validation has been subsequently undertaken and is presented. This research has demonstrated the effectiveness of the NSET approach to tower vibration; in particular its conceptual simplicity, clear physical interpretation and high accuracy. The developed and validated tower vibration model was then used to successfully detect blade angle asymmetry that is a common fault that should be remedied promptly to improve turbine performance and limit fatigue damage. The work also shows that condition monitoring is improved significantly if the information from the vibration signals is complemented by analysis of other relevant SCADA data such as power performance, wind speed, and rotor loads.
Coupled intertwiner dynamics - a toy model for coupling matter to spin foam models
Steinhaus, Sebastian
2015-01-01
The universal coupling of matter and gravity is one of the most important features of general relativity. In quantum gravity, in particular spin foams, matter couplings have been defined in the past, yet the mutual dynamics, in particular if matter and gravity are strongly coupled, are hardly explored, which is related to the definition of both matter and gravitational degrees of freedom on the discretisation. However extracting this mutual dynamics is crucial in testing the viability of the spin foam approach and also establishing connections to other discrete approaches such as lattice gauge theories. Therefore, we introduce a simple 2D toy model for Yang--Mills coupled to spin foams, namely an Ising model coupled to so--called intertwiner models defined for $\\text{SU}(2)_k$. The two systems are coupled by choosing the Ising coupling constant to depend on spin labels of the background, as these are interpreted as the edge lengths of the discretisation. We coarse grain this toy model via tensor network renor...
Coupled atmosphere-wildland fire modelling
Directory of Open Access Journals (Sweden)
Jacques Henri Balbi
2009-10-01
Full Text Available Simulating the interaction between fire and atmosphere is critical to the estimation of the rate of spread of the fire. Wildfire’s convection (i.e., entire plume can modify the local meteorology throughout the atmospheric boundary layer and consequently affect the fire propagation speed and behaviour. In this study, we use for the first time the Méso-NH meso-scale numerical model coupled to the point functional ForeFire simplified physical front-tracking wildfire model to investigate the differences introduced by the atmospheric feedback in propagation speed and behaviour. Both numerical models have been developed as research tools for operational models and are currently used to forecast localized extreme events. These models have been selected because they can be run coupled and support decisions in wildfire management in France and Europe. The main originalities of this combination reside in the fact that Méso-NH is run in a Large Eddy Simulation (LES configuration and that the rate of spread model used in ForeFire provides a physical formulation to take into account the effect of wind and slope. Simulations of typical experimental configurations show that the numerical atmospheric model is able to reproduce plausible convective effects of the heat produced by the fire. Numerical results are comparable to estimated values for fire-induced winds and present behaviour similar to other existing numerical approaches.
Modeling for IFOG Vibration Error Based on the Strain Distribution of Quadrupolar Fiber Coil.
Gao, Zhongxing; Zhang, Yonggang; Zhang, Yunhao
2016-07-21
Improving the performance of interferometric fiber optic gyroscope (IFOG) in harsh environment, especially in vibrational environment, is necessary for its practical applications. This paper presents a mathematical model for IFOG to theoretically compute the short-term rate errors caused by mechanical vibration. The computational procedures are mainly based on the strain distribution of quadrupolar fiber coil measured by stress analyzer. The definition of asymmetry of strain distribution (ASD) is given in the paper to evaluate the winding quality of the coil. The established model reveals that the high ASD and the variable fiber elastic modulus in large strain situation are two dominant reasons that give rise to nonreciprocity phase shift in IFOG under vibration. Furthermore, theoretical analysis and computational results indicate that vibration errors of both open-loop and closed-loop IFOG increase with the raise of vibrational amplitude, vibrational frequency and ASD. Finally, an estimation of vibration-induced IFOG errors in aircraft is done according to the proposed model. Our work is meaningful in designing IFOG coils to achieve a better anti-vibration performance.
Modeling for IFOG Vibration Error Based on the Strain Distribution of Quadrupolar Fiber Coil
Directory of Open Access Journals (Sweden)
Zhongxing Gao
2016-07-01
Full Text Available Improving the performance of interferometric fiber optic gyroscope (IFOG in harsh environment, especially in vibrational environment, is necessary for its practical applications. This paper presents a mathematical model for IFOG to theoretically compute the short-term rate errors caused by mechanical vibration. The computational procedures are mainly based on the strain distribution of quadrupolar fiber coil measured by stress analyzer. The definition of asymmetry of strain distribution (ASD is given in the paper to evaluate the winding quality of the coil. The established model reveals that the high ASD and the variable fiber elastic modulus in large strain situation are two dominant reasons that give rise to nonreciprocity phase shift in IFOG under vibration. Furthermore, theoretical analysis and computational results indicate that vibration errors of both open-loop and closed-loop IFOG increase with the raise of vibrational amplitude, vibrational frequency and ASD. Finally, an estimation of vibration-induced IFOG errors in aircraft is done according to the proposed model. Our work is meaningful in designing IFOG coils to achieve a better anti-vibration performance.
Variational principles for buckling and vibration of MWCNTs modeled by strain gradient theory
Institute of Scientific and Technical Information of China (English)
徐晓建; 邓子辰
2014-01-01
Variational principles for the buckling and vibration of multi-walled carbon nanotubes (MWCNTs) are established with the aid of the semi-inverse method. They are used to derive the natural and geometric boundary conditions coupled by small scale parameters. Hamilton’s principle and Rayleigh’s quotient for the buckling and vibration of the MWCNTs are given. The Rayleigh-Ritz method is used to study the buckling and vibration of the single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) with three typical boundary conditions. The numerical results reveal that the small scale parameter, aspect ratio, and boundary conditions have a profound effect on the buckling and vibration of the SWCNTs and DWCNTs.
Towards Better Coupling of Hydrological Simulation Models
Penton, D.; Stenson, M.; Leighton, B.; Bridgart, R.
2012-12-01
Standards for model interoperability and scientific workflow software provide techniques and tools for coupling hydrological simulation models. However, model builders are yet to realize the benefits of these and continue to write ad hoc implementations and scripts. Three case studies demonstrate different approaches to coupling models, the first using tight interfaces (OpenMI), the second using a scientific workflow system (Trident) and the third using a tailored execution engine (Delft Flood Early Warning System - Delft-FEWS). No approach was objectively better than any other approach. The foremost standard for coupling hydrological models is the Open Modeling Interface (OpenMI), which defines interfaces for models to interact. An implementation of the OpenMI standard involves defining interchange terms and writing a .NET/Java wrapper around the model. An execution wrapper such as OatC.GUI or Pipistrelle executes the models. The team built two OpenMI implementations for eWater Source river system models. Once built, it was easy to swap river system models. The team encountered technical challenges with versions of the .Net framework (3.5 calling 4.0) and with the performance of the execution wrappers when running daily simulations. By design, the OpenMI interfaces are general, leaving significant decisions around the semantics of the interfaces to the implementer. Increasingly, scientific workflow tools such as Kepler, Taverna and Trident are able to replace custom scripts. These tools aim to improve the provenance and reproducibility of processing tasks. In particular, Taverna and the myExperiment website have had success making many bioinformatics workflows reusable and sharable. The team constructed Trident activities for hydrological software including IQQM, REALM and eWater Source. They built an activity generator for model builders to build activities for particular river systems. The models were linked at a simulation level, without any daily time
Vibration measurements of a wire scanner - Experimental setup and models
Herranz, Juan; Barjau, Ana; Dehning, Bernd
2016-03-01
In the next years the luminosity of the LHC will be significantly increased. This will require a much higher accuracy of beam profile measurement than actually achievable by the current wire scanner. The new performance demands a wire travelling speed up to 20 m s-1 and a position measurement accuracy of the order of 1 μm. The vibrations of the mechanical parts of the system and particularly the vibrations of the thin carbon wire have been identified as the major error sources of wire position uncertainty. Therefore the understanding of the wire vibrations has been given high priority for the design and operation of the new device. This article presents a new strategy to measure the wire vibrations based on the piezoresistive effect of the wire itself. An electronic readout system based on a Wheatstone bridge is used to measure the variation of the carbon wire resistance, which is directly proportional to the wire elongation caused by the oscillations.
Coupled transverse and torsional vibrations in a mechanical system with two identical beams
Vlase, S.; Marin, M.; Scutaru, M. L.; Munteanu, R.
2017-06-01
The paper aims to study a plane system with bars, with certain symmetries. Such problems can be encountered frequently in industry and civil engineering. Considerations related to the economy of the design process, constructive simplicity, cost and logistics make the use of identical parts a frequent procedure. The paper aims to determine the properties of the eigenvalues and eigenmodes for transverse and torsional vibrations of a mechanical system where two of the three component bars are identical. The determination of these properties allows the calculus effort and the computation time and thus increases the accuracy of the results in such matters.
Lei, Yaguo; Liu, Zongyao; Lin, Jing; Lu, Fanbo
2016-05-01
Condition monitoring and fault diagnosis of epicyclic gearboxes using vibration signals are not as straightforward as that of fixed-axis gearboxes since epicyclic gearboxes behave quite differently from fixed-axis gearboxes in many aspects, like spectral structures. Aiming to present the spectral structures of vibration signals of epicyclic gearboxes, phenomenological models of vibration signals of epicyclic gearboxes are developed by algebraic equations and spectral structures of these models are deduced using Fourier series analysis. In the phenomenological models, all the possible vibration transfer paths from gear meshing points to a fixed transducer and the effects of angular shifts of planet gears on the spectral structures are considered. Accordingly, time-varying vibration transfer paths from sun-planet/ring-planet gear meshing points to the fixed transducer due to carrier rotation are given by window functions with different amplitudes. And an angular shift in one planet gear position is introduced in the process of modeling. After the theoretical derivations, three experiments are conducted on an epicyclic gearbox test rig and the spectral structures of collected vibration signals are analyzed. As a result, the effects of angular shifts of planet gears are verified, and the phenomenological models of vibration signals when a local fault occurs on the sun gear and the planet gear are validated, respectively. The experiment results demonstrate that the established phenomenological models in this paper are helpful to the condition monitoring and fault diagnosis of epicyclic gearboxes.
Kaliski, S
2013-01-01
This book gives a comprehensive overview of wave phenomena in different media with interacting mechanical, electromagnetic and other fields. Equations describing wave propagation in linear and non-linear elastic media are followed by equations of rheological models, models with internal rotational degrees of freedom and non-local interactions. Equations for coupled fields: thermal, elastic, electromagnetic, piezoelectric, and magneto-spin with adequate boundary conditions are also included. Together with its companion volume Vibrations and Waves. Part A: Vibrations this work provides a wealth
Morgan, Sarah E; Chin, Alex W
2016-01-01
Collective protein modes are expected to be important for facilitating energy transfer in the Fenna-Matthews-Olson (FMO) complex, however to date little work has focussed on the microscopic details of these vibrations. The nonlinear network model (NNM) provides a computationally inexpensive approach to studying vibrational modes at the microscopic level, whilst incorporating anharmonicity in the inter-residue interactions which can influence protein dynamics. We apply the NNM to the FMO complex and find evidence for the existence of nonlinear discrete breather modes. These modes tend to transfer energy to the highly connected core pigments, potentially opening up alternative excitation energy transfer routes. Incorporating localised modes based on these discrete breathers in the optical spectra calculations for FMO using ab initio site energies and excitonic couplings can substantially improve their agreement with experimental results.
Morgan, Sarah E.; Cole, Daniel J.; Chin, Alex W.
2016-11-01
Collective protein modes are expected to be important for facilitating energy transfer in the Fenna-Matthews-Olson (FMO) complex of photosynthetic green sulphur bacteria, however to date little work has focussed on the microscopic details of these vibrations. The nonlinear network model (NNM) provides a computationally inexpensive approach to studying vibrational modes at the microscopic level in large protein structures, whilst incorporating anharmonicity in the inter-residue interactions which can influence protein dynamics. We apply the NNM to the entire trimeric FMO complex and find evidence for the existence of nonlinear discrete breather modes. These modes tend to transfer energy to the highly connected core pigments, potentially opening up alternative excitation energy transfer routes through their influence on pigment properties. Incorporating localised modes based on these discrete breathers in the optical spectra calculations for FMO using ab initio site energies and excitonic couplings can substantially improve their agreement with experimental results.
Guo, Junhong; Chen, Jiangyi; Pan, Ernian
2017-03-01
Based on the modified couple-stress theory, three-dimensional analytical solutions of free vibration of a simply supported, multilayered and anisotropic composite nanoplate are derived by solving an eigenvalue system and using the propagator matrix method. By expanding the solutions of the extended displacements in terms of two-dimensional Fourier series, the final governing equations of motion with modified couple-stress effect are reduced to an eigenvalue system of ordinary differential equations. Analytical expressions for the natural frequencies and mode shapes of multilayered anisotropic composite plates with modified couple-stress effect are then derived via the propagator matrix method. Numerical examples are carried out for homogeneous thick-plates and sandwich composite plates to show the effect of the non-local parameter in different layers and stacking sequence on the mode shapes. The present solutions can serve as benchmarks to various thick-plate theories and numerical methods, and could be further useful for designing layered composite structures involving small scale.
Energy Technology Data Exchange (ETDEWEB)
Dijkstra, Arend G., E-mail: arend.dijkstra@mpsd.mpg.de, E-mail: tanimura@kuchem.kyoto-u.ac.jp [Max Planck Institute for the Structure and Dynamics of Matter, Hamburg (Germany); Tanimura, Yoshitaka, E-mail: arend.dijkstra@mpsd.mpg.de, E-mail: tanimura@kuchem.kyoto-u.ac.jp [Department of Chemistry, Kyoto University, Kyoto (Japan)
2015-06-07
We study hole, electron, and exciton transports in a charge transfer system in the presence of underdamped vibrational motion. We analyze the signature of these processes in the linear and third-, and fifth-order nonlinear electronic spectra. Calculations are performed with a numerically exact hierarchical equations of motion method for an underdamped Brownian oscillator spectral density. We find that combining electron, hole, and exciton transfers can lead to non-trivial spectra with more structure than with excitonic coupling alone. Traces taken during the waiting time of a two-dimensional (2D) spectrum are dominated by vibrational motion and do not reflect the electron, hole, and exciton dynamics directly. We find that the fifth-order nonlinear response is particularly sensitive to the charge transfer process. While third-order 2D spectroscopy detects the correlation between two coherences, fifth-order 2D spectroscopy (2D population spectroscopy) is here designed to detect correlations between the excited states during two different time periods.
Dijkstra, Arend G; Tanimura, Yoshitaka
2015-06-01
We study hole, electron, and exciton transports in a charge transfer system in the presence of underdamped vibrational motion. We analyze the signature of these processes in the linear and third-, and fifth-order nonlinear electronic spectra. Calculations are performed with a numerically exact hierarchical equations of motion method for an underdamped Brownian oscillator spectral density. We find that combining electron, hole, and exciton transfers can lead to non-trivial spectra with more structure than with excitonic coupling alone. Traces taken during the waiting time of a two-dimensional (2D) spectrum are dominated by vibrational motion and do not reflect the electron, hole, and exciton dynamics directly. We find that the fifth-order nonlinear response is particularly sensitive to the charge transfer process. While third-order 2D spectroscopy detects the correlation between two coherences, fifth-order 2D spectroscopy (2D population spectroscopy) is here designed to detect correlations between the excited states during two different time periods.
DEFF Research Database (Denmark)
Friis, Lars; Ohlrich, Mogens
2008-01-01
-dimensional continuous boundary. Additionally, a simple method for determining the so-called equivalent coupling factor is presented. The validity of this method is demonstrated by numerical simulations of the vibration response of a master plate structure with fuzzy attachments. It is revealed that the method performs...
Van Buren, Kendra L.; Ouisse, Morvan; Cogan, Scott; Sadoulet-Reboul, Emeline; Maxit, Laurent
2017-09-01
In the development of numerical models, uncertainty quantification (UQ) can inform appropriate allocation of computational resources, often resulting in efficient analysis for activities such as model calibration and robust design. UQ can be especially beneficial for numerical models with significant computational expense, such as coupled models, which require several subsystem models to attain the performance of a more complex, inter-connected system. In the coupled model paradigm, UQ can be applied at either the subsystem model level or the coupled model level. When applied at the subsystem level, UQ is applied directly to the physical input parameters, which can be computationally expensive. In contrast, UQ at the coupled level may not be representative of the physical input parameters, but comes at the benefit of being computationally efficient to implement. To be physically meaningful, analysis at the coupled level requires information about how uncertainty is propagated through from the subsystem level. Herein, the proposed strategy is based on simulations performed at the subsystem level to inform a covariance matrix for UQ performed at the coupled level. The approach is applied to a four-subsystem model of mid-frequency vibrations simulated using the Statistical Modal Energy Distribution Analysis, a variant of the Statistical Energy Analysis. The proposed approach is computationally efficient to implement, while simultaneously capturing information from the subsystem level to ensure the analysis is physically meaningful.
A Unified Mutual Coupling Model for Multiple Antenna Systems
Institute of Scientific and Technical Information of China (English)
WU Yu-jiang; NIE Zai-ping
2006-01-01
A unified mutual coupling model for multiple antenna communication systems based on moment methods is proposed. This model combines antenna coupling and RF front-end circuit coupling, thus providing a more accurate and complete analysis of the mutual coupling effect on multiple antenna systems.
Coupled electrothermal modeling of microheaters using SPICE
Swart, Nicholas R.; Nathan, Arokia
1994-06-01
A novel simulation approach that computes both the transient and steady state electrothermal behavior in integrated circuit (IC) compatible thermally isolated microheaters is reported. The resulting distribution of heat, current density and temperature, as well as the electrical terminal behavior have been obtained for realistic device structures. The results are based on a two-dimensional solution of the coupled system of partial differential equations that govern both electrical and heat transport in the device. Unlike standard numerical approaches for coupled systems, our technique is based on the behavioural models, available in most commercial circuit simulators (e.g., HSPICE), that allow synthesis of complex, nonlinear, and coupled circuit elements. The simulation results are in excellent agreement with measurement data of steady state and transient terminal characteristics, obtained under conditions of vacuum. We note that this modeling approach allows concurrent simulation (and subsequent optimization) of the performance of both the control electronics as well as the thermal element(s), within the same IC design environment.
The standard model with gravity couplings
Chang, L N; Lay Nam Chang; Chopin Soo
1996-01-01
ABSTRACT-The Standard Model with Gravity Couplings-Lay Nam Chang(Virginia Tech) & Chopin Soo(Penn State)--- It has been shown by Ashtekar, and many others after him, that classical gravity in four dimensions can be described equally well by (anti)self-dual variables instead of the conventional variables. In this paper, we examine the coupling of matter fields to gravity from this perspective, and show that the known quark and lepton multiplets in the Standard Model of particle physics can be introduced into the theory in a manner which ensures the cancellation of perturbative chiral gauge anomalies, despite the fact that the the Ashtekar-Sen connection allows for couplings only to left-handed Weyl fermions. We also explore a global anomaly associated with the theory, and argue that its removal requires that the number of fundamental fermions in the theory must be multiples of 16. In addition, we investigate the behavior of the theory under discrete transformations P, C and T, and discuss possible violatio...
Parra, J.; Vicuña, Cristián Molina
2017-08-01
Planetary gearboxes are important components of many industrial applications. Vibration analysis can increase their lifetime and prevent expensive repair and safety concerns. However, an effective analysis is only possible if the vibration features of planetary gearboxes are properly understood. In this paper, models are used to study the frequency content of planetary gearbox vibrations under non-fault and different fault conditions. Two different models are considered: phenomenological model, which is an analytical-mathematical formulation based on observation, and lumped-parameter model, which is based on the solution of the equations of motion of the system. Results of both models are not directly comparable, because the phenomenological model provides the vibration on a fixed radial direction, such as the measurements of the vibration sensor mounted on the outer part of the ring gear. On the other hand, the lumped-parameter model provides the vibrations on the basis of a rotating reference frame fixed to the carrier. To overcome this situation, a function to decompose the lumped-parameter model solutions to a fixed reference frame is presented. Finally, comparisons of results from both model perspectives and experimental measurements are presented.
Institute of Scientific and Technical Information of China (English)
Ning WANG; Kui-hua WANG; Wen-bing WU
2013-01-01
In this paper,a model named fictitious soil pile was introduced to solve the boundary coupled problem at the pile tip.In the model,the soil column between pile tip and bedrock was treated as a fictitious pile,which has the same properties as the local soil.The tip of the fictitious soil pile was assumed to rest on a rigid rock and no tip movement was allowed.In combination with the plane strain theory,the analytical solutions of vertical vibration response of piles in a frequency domain and the corresponding semi-analytical solutions in a time domain were obtained using the Laplace transforms and inverse Fourier transforms.A parametric study of pile response at the pile tip and head showed that the thickness and layering of the stratum between pile tip and bedrock have a significant influence on the complex impedances.Finally,two applications of the analytical model were presented.One is to identify the defects of the pile shaft,in which the proposed model was proved to be accurate to identify the location as well as the length of pile defects.Another application of the model is to identify the sediment thickness under the pile tip.The results showed that the sediment can lead to the decrease of the pile stiffness and increase of the damping,especially when the pile is under a low frequency load.
Fitts' law model and target size of pointing devices in a vibration environment.
Liu, Chi No; Lin, Chiuhsiang Joe; Chao, Chin Jung
2007-12-01
This study examined models of Fitts' law and effective target widths of three pointing devices in vibration environments. From a research institute 10 employees, ages 26 to 31 years were recruited as paid subjects. Pointing tasks consisted of four square target sizes, four movement distances, and four target angles and were performed on a motion platform using a touch screen, a mouse, and a track ball. The platform simulated two levels of sea wave vibration environments besides a static one. Analysis showed effective target widths increased with vibration, indicating increased variability of the pointing task under vibration. The increase in the track ball was smaller, indicating resistance to motion disturbance. The study also suggests an enlarged target (button) size for the touch screen under the vibration environment. The findings have implications in motor control and human-computer interfacing.
CALCULATIONS OF STRETCHING VIBRATIONAL ENERGYLEVELS OF THE CH3I MOLECULE BY A NONLINEAR MODEL
Institute of Scientific and Technical Information of China (English)
ZHU JUN; GOU QING-QUAN
2001-01-01
A nonlinear model, i.e. the quantized discrete self-trapping equation, is applied to calculate the highly excited CH stretching vibrational energy levels of the CH3I molecule in the liquid phase at the electronic ground state up to n=8. The obtained results agree well with the experimental data and with those obtained from local mode model calculations. We note that the dominant feature of the methyl CH stretching vibrational energy levels of the CH3I molecule is a pattern of local mode pairs. When n ＞ 7, all the vibrational energy of the CH3 group can nearly be localized on a single CH bond.
Modeling on thermally induced coupled micro-motions of satellite with complex flexible appendages
Directory of Open Access Journals (Sweden)
Zhicheng Zhou
2015-06-01
Full Text Available To describe the characteristics of thermally induced coupled micro-motions more exactly, a numerical model is proposed for a satellite system consisting of a rigid body and the complex appendages. The coupled governing equations including the effects of transient temperature differences are formulated within the framework of the Lagrangian Method based on the finite element models of flexible structures. Meanwhile, the problem of coupling between attitude motions of rigid body and vibrations of flexible attachments are addressed with explicit expressions. Thermally induced micro-motions are examined in detail for a simple satellite with a large solar panel under the disturbance of thermal environment from earth shadow to sunlight area in the earth orbit. The results show that the thermal–mechanical performances of an on-orbit satellite can be well predicted by the proposed finite element model.
Structure and vibrational spectra of a model of a-Si:H with periodic boundary conditions
Energy Technology Data Exchange (ETDEWEB)
Winer, K.; Wooten, F.
1983-08-01
A ball-and -stick model of a-Si:H with periodic boundary conditions has been constructed. A computer replica of the structure has been relaxed and the density, radial distribution function and vibrational spectra calculated.
2011-01-01
This paper deals with a method called Statistical Energy Analysis that can be applied to the mechanical and acoustical systems like buildings, bridges and aircrafts etc. S.E.A as a tool can be applied to the resonant systems in the circumstances of high frequency or/and complex structure». The parameters of S.E.A such as coupling loss factor, internal loss factor, modal density and input power are clarified in this work ; coupled plate sub-systems and explanations are presented for these par...
Coupling a Terrestrial Biogeochemical Model to the Common Land Model
Institute of Scientific and Technical Information of China (English)
SHI Xiaoying; MAd Jiafu; WANG Yingping; DAI Yongjiu; TANG Xuli
2011-01-01
A terrestrial biogeochemical model (CASACNP) was coupled to a land surtace model (the Common Ｌand Model,CoLM) to simulate the dynamics of carbon substrate in soil and its limitation on soil respiration.The combined model,CoLM_CASACNP,was able to predict long-term carbon sources and sinks that CoLM alone could not.The coupled model was tested using measurenents of belowground respiration and surface fluxes from two forest ecosystems.The combined model simulated reasonably well the diurnal and seasonal variations of net ecosystem carbon exchange,as well as seasonal variation in the soil respiration rate of both the forest sites chosen for this study.However,the agreement between model simulations and actual measurements was poorer under dry conditions.The model should be tested against more measurements before being applied globally to investigate the feedbacks between the carbon cycle and climate change.
Directory of Open Access Journals (Sweden)
Young-Ho Park
2006-01-01
Full Text Available This paper presents the methodology for the energy flow analysis of coupled Timoshenko beam structures and various numerical applications to verify the developed methodology. To extend the application of the energy flow model for corrected flexural waves in the Timoshenko beam, which is developed in the other companion paper, to coupled structures, the wave transmission analyses of general coupled Timoshenko beam systems are performed. First, power transmission and reflection coefficients for all kinds of propagating waves in the general, coupled Timoshenko beam structures are derived by the wave transmission approach. In numerical applications, the energy flow solutions using the derived coefficients agree well with the classical solutions for various exciting frequencies, damping loss factors, and coupled Timoshenko beam structures. Additionally, the numerical results for the Timoshenko beam are compared with those for the Euler-Bernoulli beam.
Analysis and Modelling of Muscles Motion during Whole Body Vibration
Directory of Open Access Journals (Sweden)
La Gatta A
2010-01-01
Full Text Available The aim of the study is to characterize the local muscles motion in individuals undergoing whole body mechanical stimulation. In this study we aim also to evaluate how subject positioning modifies vibration dumping, altering local mechanical stimulus. Vibrations were delivered to subjects by the use of a vibrating platform, while stimulation frequency was increased linearly from 15 to 60 Hz. Two different subject postures were here analysed. Platform and muscles motion were monitored using tiny MEMS accelerometers; a contra lateral analysis was also presented. Muscle motion analysis revealed typical displacement trajectories: motion components were found not to be purely sinusoidal neither in phase to each other. Results also revealed a mechanical resonant-like behaviour at some muscles, similar to a second-order system response. Resonance frequencies and dumping factors depended on subject and his positioning. Proper mechanical stimulation can maximize muscle spindle solicitation, which may produce a more effective muscle activation.
Zai, Behzad Ahmed; Sami, Saad; Khan, M. Amir; Ahmad, Furqan; Park, Myung Kyun
2015-09-01
Geometric or sub-scale modeling techniques are used for the evaluation of large and complex dynamic structures to ensure accurate reproduction of load path and thus leading to true dynamic characteristics of such structures. The sub-scale modeling technique is very effective in the prediction of vibration characteristics of original large structure when the experimental testing is not feasible due to the absence of a large testing facility. Previous researches were more focused on free and harmonic vibration case with little or no consideration for readily encountered random vibration. A sub-scale modeling technique is proposed for estimating the vibration characteristics of any large scale structure such as Launch vehicles, Mega structures, etc., under various vibration load cases by utilizing precise scaled-down model of that dynamic structure. In order to establish an analytical correlation between the original structure and its scaled models, different scale models of isotropic cantilever beam are selected and analyzed under various vibration conditions( i.e. free, harmonic and random) using finite element package ANSYS. The developed correlations are also validated through experimental testing. The prediction made from the vibratory response of the scaled-down beam through the established sets of correlation are found similar to the response measured from the testing of original beam structure. The established correlations are equally applicable in the prediction of dynamic characteristics of any complex structure through its scaled-down models. This paper presents modified sub-scale modeling technique that enables accurate prediction of vibration characteristics of large and complex structure under not only sinusoidal but also for random vibrations.
Song, O; Jeong, N H; Librescu, L
2001-03-01
Problems related with the implications of conservative and gyroscopic forces on vibration and the stability of a circular cylindrical shaft modeled as a thin-walled composite beam and spinning with constant angular speed about its longitudinal axis are addressed. Taking into account the directionality property of fiber reinforced composite materials, it is shown that for a shaft featuring flapwise-chordwise-bending coupling, a dramatic enhancement of both the vibrational and stability behavior can be reached. In addition, the effects played in the same context by transverse shear, rotatory inertias as well as by the various boundary conditions are discussed and pertinent conclusions are outlined.
Langevin model of the temperature and hydration dependence of protein vibrational dynamics.
Moritsugu, Kei; Smith, Jeremy C
2005-06-23
The modification of internal vibrational modes in a protein due to intraprotein anharmonicity and solvation effects is determined by performing molecular dynamics (MD) simulations of myoglobin, analyzing them using a Langevin model of the vibrational dynamics and comparing the Langevin results to a harmonic, normal mode model of the protein in vacuum. The diagonal and off-diagonal Langevin friction matrix elements, which model the roughness of the vibrational potential energy surfaces, are determined together with the vibrational potentials of mean force from the MD trajectories at 120 K and 300 K in vacuum and in solution. The frictional properties are found to be describable using simple phenomenological functions of the mode frequency, the accessible surface area, and the intraprotein interaction (the displacement vector overlap of any given mode with the other modes in the protein). The frictional damping of a vibrational mode in vacuum is found to be directly proportional to the intraprotein interaction of the mode, whereas in solution, the friction is proportional to the accessible surface area of the mode. In vacuum, the MD frequencies are lower than those of the normal modes, indicating intramolecular anharmonic broadening of the associated potential energy surfaces. Solvation has the opposite effect, increasing the large-amplitude vibrational frequencies relative to in vacuum and thus vibrationally confining the protein atoms. Frictional damping of the low-frequency modes is highly frequency dependent. In contrast to the damping effect of the solvent, the vibrational frequency increase due to solvation is relatively temperature independent, indicating that it is primarily a structural effect. The MD-derived vibrational dynamic structure factor and density of states are well reproduced by a model in which the Langevin friction and potential of mean force parameters are applied to the harmonic normal modes.
Modeling and characterization of multiple coupled lines
Tripathi, Alok
1999-10-01
A configuration-oriented circuit model for multiple coupled lines in an inhomogeneous medium is developed and presented in this thesis. This circuit model consists of a network of uncoupled transmission lines and is readily modeled with simulation tools like LIBRA© and SPICE ©. It provides an equivalent circuit representation which is simple and topologically meaningful as compared to the model based on modal decomposition. The configuration-oriented model is derived by decomposing the immittance matrices associated with an n coupled line 2n-port system. Time- and frequency- domain simulations of typical coupled line multiports are included to exemplify the utility of the model. The model is useful for the simulation and design of general single and multilayer coupled line components, such as filters and couplers, and for the investigation of signal integrity issues including crosstalk in interconnects associated with high speed digital and mixed signal electronic modules and packages. It is shown that multiconductor lossless structures in an inhomogeneous medium can be characterized by multiport time-domain reflection (MR) measurements. A synthesis technique of an equivalent lossless (non-dispersive) uniform multiconductor n coupled lines (UMCL) 2n-port system from the measured discrete time-domain reflection response is presented. This procedure is based on the decomposition of the characteristic immittance matrices of the UMCL in terms of partial mode immittance matrices. The decomposition scheme leads to the discrete transition matrix function of a UMCL 2n-port system. This in turn establishes a relationship between the normal-mode parameters of the UMCL and the measured impulse reflection and transmission response. Equivalence between the synthesis procedure presented in this thesis and the solution of a special form of an algebraic Riccati matrix equation whose solution can lead to the normal-mode parameters and a real termination network is illustrated. In
Quantum Ising model coupled with conducting electrons
Energy Technology Data Exchange (ETDEWEB)
Yamashita, Yasufumi; Yonemitsu, Kenji [Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585 (Japan); Graduate University for Advanced studies, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585 (Japan)
2005-01-01
The effect of photo-doping on the quantum paraelectric SrTiO{sub 3} is studied by using the one-dimensional quantum Ising model, where the Ising spin describes the effective lattice polarization of an optical phonon. Two types of electron-phonon couplings are introduced through the modulation of transfer integral via lattice deformations. After the exact diagonalization and the perturbation studies, we find that photo-induced low-density carriers can drastically alter quantum fluctuations when the system locates near the quantum critical point between the quantum para- and ferro-electric phases.
Quantum Ising model coupled with conducting electrons
Yamashita, Yasufumi; Yonemitsu, Kenji
2005-01-01
The effect of photo-doping on the quantum paraelectric SrTiO3 is studied by using the one-dimensional quantum Ising model, where the Ising spin describes the effective lattice polarization of an optical phonon. Two types of electron-phonon couplings are introduced through the modulation of transfer integral via lattice deformations. After the exact diagonalization and the perturbation studies, we find that photo-induced low-density carriers can drastically alter quantum fluctuations when the system locates near the quantum critical point between the quantum para- and ferro-electric phases.
Ding, Hu; Zu, Jean W.
2013-11-01
This study focuses on the nonlinear steady-state response of a belt-drive system with a one-way clutch. A dynamic model is established to describe the rotations of the driving pulley, the driven pulley, and the accessory shaft. Moreover, the model considers the transverse vibration of the translating belt spans for the first time in belt-drive systems coupled with a one-way clutch. The excitation of the belt-drive system is derived from periodic fluctuation of the driving pulley. In automotive systems, this kind of fluctuation is induced by the engine firing harmonic pulsations. The derived coupled discrete-continuous nonlinear equations consist of integro-partial-differential equations and piece-wise ordinary differential equations. Using the Galerkin truncation, a set of nonlinear ordinary differential equations is obtained from the integro-partial-differential equations. Applying the Runge-Kutta time discretization, the time histories of the dynamic response are numerically solved for the driven pulley and the accessory shaft and the translating belt spans. The resonance areas of the coupled belt-drive system are determined using the frequency sweep. The effects of the one-way clutch on the belt-drive system are studied by comparing the frequency-response curves of the translating belt with and without one-way clutch device. Furthermore, the results of 2-term and 4-term Galerkin truncation are compared to determine the numerical convergence. Moreover, parametric studies are conducted to understand the effects of the system parameters on the nonlinear steady-state response. It is concluded that one-way clutch not only decreases the resonance amplitude of the driven pulley and shaft's rotational vibration, but also reduces the resonance region of the belt's transverse vibration.
Institute of Scientific and Technical Information of China (English)
殷雨时; 武斌; 殷井奎
2011-01-01
通过对汽车振动模型简化成平面两自由度振动体系的基础上,对车桥耦合作用的机理进行了力学分析,并结合MATLAB强大的数值计算功能对车桥耦合振动问题进行数值模拟.%Through simplifying the vehicle vibration model to planar two-freedom vibration systems, the mechanical analysis of the role of bridge coupling mechanism are made, and the numerical simulation of bridge vibration problems with the powerful numerical calculation function of MATLAB.
Energy Technology Data Exchange (ETDEWEB)
Guy, Aurélien, E-mail: aurelien.guy@onera.fr; Bourdon, Anne, E-mail: anne.bourdon@lpp.polytechnique.fr; Perrin, Marie-Yvonne, E-mail: marie-yvonne.perrin@ecp.fr [CNRS, UPR 288, Laboratoire d' Énergétique Moléculaire et Macroscopique, Combustion (EM2C), Grande Voie des Vignes, 92295 Châtenay-Malabry (France); Ecole Centrale Paris, Grande Voie des Vignes, 92295 Châtenay-Malabry (France)
2015-04-15
In this work, a state-to-state vibrational and electronic collisional model is developed to investigate nonequilibrium phenomena behind a shock wave in an ionized nitrogen flow. In the ionization dynamics behind the shock wave, the electron energy budget is of key importance and it is found that the main depletion term corresponds to the electronic excitation of N atoms, and conversely the major creation terms are the electron-vibration term at the beginning, then replaced by the electron ions elastic exchange term. Based on these results, a macroscopic multi-internal-temperature model for the vibration of N{sub 2} and the electronic levels of N atoms is derived with several groups of vibrational levels of N{sub 2} and electronic levels of N with their own internal temperatures to model the shape of the vibrational distribution of N{sub 2} and of the electronic excitation of N, respectively. In this model, energy and chemistry source terms are calculated self-consistently from the rate coefficients of the state-to-state database. For the shock wave condition studied, a good agreement is observed on the ionization dynamics as well as on the atomic bound-bound radiation between the state-to-state model and the macroscopic multi-internal temperature model with only one group of vibrational levels of N{sub 2} and two groups of electronic levels of N.
Mizuyama, Kazuhito
2012-01-01
The microscopic description of neutron scattering by $^{16}$O below 30 MeV is carried out by means of the continuum particle-vibration coupling (cPVC) method with the Skyrme nucleon-nucleon ($NN$) effective interaction. In the cPVC method, a proper boundary condition on a nucleon in continuum states is imposed, which enables one to evaluate the transition matrix in a straightforward manner. Experimental data of the total and total-elastic cross sections are reproduced quite well by the cPVC method. An important feature of the result is the fragmentation of the single-particle resonance into many peaks as well as the shift of its centroid energy. Thus, some part of the fine structure of the experimental cross sections at lower energies is well described by the cPVC framework. The cPVC method based on a real $NN$ effective interaction is found to successfully explain about 85% of the reaction cross section, through explicit channel-coupling effects.
Train-induced ground vibrations: modeling and experiments
Ditzel, A.
2003-01-01
Ground vibrations generated by high-speed trains are of great concern because of the possible damage they can cause to buildings or other structures near the track, and the annoyance to the public living in the vicinity of the track. Particularly in soft-soil regions, where the wave speed is compara
A Biological Model for Directional Sensing of Seismic Vibration
2007-11-02
186: 695-705. Cokl, A., Otto, C. and Kalmring, K. 1985. The processing of directional vibratory signals in the ventral nerve cord of Locusta ... migratoria . J. Comp. Physiol. A 156:45-52. Cokl, A., M. Virant-Doberlet, and A. McDowell. 1999. Vibrational directionality in the southern green stink bug
Finite Element Modeling of Vibrations in Canvas Paintings
Chiriboga Arroyo, P.G.
2013-01-01
Preventing vibration damage from occurring to valuable and sensitive canvas paintings is of main concern for museums and art conservation institutions. This concern has grown in recent years due to the increasing demand of paintings for exhibitions worldwide and the concomitant need for their handli
Coupled hydroelastic vibrations of an elliptical cylindrical tank with an elastic bottom
Institute of Scientific and Technical Information of China (English)
HASHEMINEJAD Seyyed M.; TAFANI Mostafa
2014-01-01
An exact three-dimensional analysis based on the linear potential theory and the elaborated method of eigenfunction expansion in elliptic coordinates are presented to study the free coupled elasto-hyrodynamic characteristics of an upright non-deformable cylindrical container of elliptical planform with a flexible bottom plate, filled to an arbitrary depth with an inviscid incompressible liquid. Extensive numerical data are presented in an orderly fashion for the first few symmetric/anti-symmetric coupled hydroelastic natural frequencies as a function of fluid depth parameter for two plate aspect ratios. Also, selected hydrodynamic and structural deformation modes shapes are presented in graphical form. The effects of liquid level, bottom plate elasticity, and cross sectional aspect ratio on the sloshing frequencies and hydrodynamic pressure modes are examined. The validity of the results is examined through computations using a commercial finite element package as well as by comparison with the data available in literature.
Coupled vibration of driving sections for an electromechanical integrated harmonic piezodrive system
Directory of Open Access Journals (Sweden)
Chong Li
2014-03-01
Full Text Available An electromechanical integrated harmonic piezodrive system was developed that elicits fast responses with nanoscale accuracy and large torque density. The operating principle of the drive system is discussed and its dynamic equations are deduced. Coupled with boundary conditions and continuity conditions, these equations provide the natural frequencies and modal functions. The effects of the principal factors affecting the natural frequencies are investigated. These results provide a basis for improving the rotational accuracy of such systems.
A new coupled model for alloy solidification
Institute of Scientific and Technical Information of China (English)
LI Daming; LI Ruo; ZHANG Pingwen
2004-01-01
A new coupled model in the binary alloy solidification has been developed. The model is based on the cellular automaton (CA)technique to calculate the evolution of the interface governed by temperature, solute diffusion and Gibbs-Thomson effect. The diffusion equation of temperature with the release of latent heat on the solid/liquid (S/L) interface is valid in the entire domain.The temperature diffusion without the release of latent heat and solute diffusion are solved in the entire domain. In the interface cells, the energy and solute conservation, thermodynamic and chemical potential equilibrium are adopted to calculate the temperature, solid concentration, liquid concentration and the increment of solid fraction. Compared with other models where the release of latent heat is solved in implicit or explicit form according to the solid/liquid (S/L) interface velocity, the energy diffusion and the release of latent heat in this model are solved at differentscales, I.e. The macro-scale and micro-scale. The variation ofsolid fraction in this model is solved using several algebraicrelations coming from the chemical potential equilibrium andthermodynamic equilibrium which can be cheaply solved insteadof the calculation of S/L interface velocity. With the assumptionof the solute conservation and energy conservation, the solidfraction can be directly obtained according to the thermodynamicdata. This model is natural to be applied to multiple (>2)spatial dimension case and multiple (>2) component alloy. Themorphologies of equiaxed dendrite are obtained in numericalexperiments.
Institute of Scientific and Technical Information of China (English)
闫晓强
2011-01-01
全世界薄板坯连铸连轧机在轧制薄规格带钢时都出现不同程度的严重振动现象,导致带钢和轧辊生成明显振痕,从而影响企业的产品质量、外部形象和经济效益.利用自制综合遥测系统对轧机振动参数、力能参数、电参数和工艺参数等进行全面的现场综合测试,经过对测试信号的时域分析和频域分析获得振动的特征及规律;通过理论研究和仿真研究,发现轧机确实存在扭垂耦合振动、机电耦合振动和液机耦合振动现象,确定轧机振动的性质为机电液多态耦合振动.据此对电气传动控制系统和AGC系统进行参数修改和优化,将设计的二阶扭振抑制器应用在主传动控制系统中和对AGC参数进行优化,辊系振动明显降低,有效地抑制了轧机机电液耦合振动现象,取得了显著的经济效益和社会效益.%Thin slab continuous-casting and continuous-rolling mill appear different degree of serious vibration phenomenon when rolling thin strip in the world. The vibration phenomenon lead the strip and rolls to generate obvious stripe, which affects product quality and enterprise external image and economic benefits. Using self-made comprehensive telemetry system test the rolling mills vibration parameters, force and energy parameters, electric parameters and technological parameters in the site. Analysing the test signal in the time and frequency domain, characteristics and rules of vibration can be obtain. Through the theoretical and simulation research, it is found that rolling mill do exist vertical-twist coupling vibration, electro-mechanical coupling vibration and liquid-mechanical coupling vibration phenomenon. So confirming the nature of the rolling mill vibration is mechanical-electrical-liquid coupling vibration. Based on modification and optimization of the electric drive control system and AGC system, applying the designing second order torsional vibration observer in the main drive
Simple supersymmetric strongly coupled preon model
Fajfer, S.; Tadić, D.
1988-08-01
This supersymmetric-SU(5) composite model is a natural generalization of the usual strong-coupling models. Preon superfields are in representations 5* and 10. The product representations 5*×10, 5×10, 5×5, and 5*×5 contain only those strongly hypercolor bound states which are needed in the standard electroweak theory. There are no superfluous quarklike states. The neutrino is massless. Only one strongly hypercolor bound singlet (10×10*) can exist as a free particle. At higher energies one should expect to see a plethora of new particles. Grand unification happens at the scale M~1014 GeV. Cabibbo mixing can be incorporated by using a transposed Kobayashi-Maskawa mixing matrix.
The Standard Model Coupled to Quantum Gravitodynamics
Aldabe, Fermin
2016-01-01
We show that the renormalizable SO(4) X U (1) X SU (2) X SU (3) Yang Mills coupled to matter and the Higgs field fits all the experimentally observed differential cross sections known in nature. This extended Standard Model reproduces the experimental gravitational differential cross sections without resorting to the graviton field and instead by exchanging SO(4) gauge fields. By construction, each SO(4) generator in quantum gravitodynamics does not commute with the Dirac gamma matrices. This produces additional interactions absent to non-Abelian gauge fields in the Standard Model. The contributions from these new terms yield differential cross sections consistent with the Newtonian and post Newtonian interactions derived from General Relativity. Dimensional analysis of the Lagrangian shows that all its terms have total dimensionality four or less and therefore that all physical quantities in the theory renormalize by finite amounts. These properties make QGD the only renormalizable 4-dimensional theory descr...
The standard model coupled to quantum gravitodynamics
Aldabe, Fermin
2017-01-01
We show that the renormalizable SO(4)× U(1)× SU(2)× SU(3) Yang-Mills coupled to matter and the Higgs field fits all the experimentally observed differential cross sections known in nature. This extended Standard Model reproduces the experimental gravitational differential cross sections without resorting to the graviton field and instead by exchanging SO(4) gauge fields. By construction, each SO(4) generator in quantum gravitodynamics does not commute with the Dirac gamma matrices. This produces additional interactions absent to non-Abelian gauge fields in the Standard Model. The contributions from these new terms yield differential cross sections consistent with the Newtonian and post-Newtonian interactions derived from General Relativity. Dimensional analysis of the Lagrangian shows that all its terms have total dimensionality four or less and therefore that all physical quantities in the theory renormalize by finite amounts. These properties make QGD the only renormalizable four-dimensional theory describing gravitational interactions.
The standard model coupled to quantum gravitodynamics
Energy Technology Data Exchange (ETDEWEB)
Aldabe, Fermin
2017-01-15
We show that the renormalizable SO(4) x U(1) x SU(2) x SU(3) Yang-Mills coupled to matter and the Higgs field fits all the experimentally observed differential cross sections known in nature. This extended Standard Model reproduces the experimental gravitational differential cross sections without resorting to the graviton field and instead by exchanging SO(4) gauge fields. By construction, each SO(4) generator in quantum gravitodynamics does not commute with the Dirac gamma matrices. This produces additional interactions absent to non-Abelian gauge fields in the Standard Model. The contributions from these new terms yield differential cross sections consistent with the Newtonian and post-Newtonian interactions derived from General Relativity. Dimensional analysis of the Lagrangian shows that all its terms have total dimensionality four or less and therefore that all physical quantities in the theory renormalize by finite amounts. These properties make QGD the only renormalizable four-dimensional theory describing gravitational interactions. (orig.)
Kim, Joohyun; Huang, Rong; Kubelka, Jan; Bou Rcaron, Petr; Keiderling, Timothy A
2006-11-23
Vibrational spectra of a 12-residue beta-hairpin peptide, RYVEVBGKKILQ (HBG), stabilized by an Aib-Gly turn sequence (B = Aib) were investigated theoretically using a combination of molecular dynamics (MD) and density functional theory (DFT) calculations. Selected conformations of HBG were extracted from a classical MD trajectory and used for spectral simulations. DFT calculations, based on the Cartesian coordinate spectral property transfer protocol, were carried out for peptide structures in which all residues are replaced with Ala, except for the Aib and Gly residues, but the backbone (phi, psi, omega) structure of the original configuration is retained. The simulations provide a basis for interpretation of the HBG amide I infrared spectra in terms of structural variables such as detailed secondary structure and thermal conformational fluctuation as well as vibrational coupling as indicated by spectra of 13C isotope-labeled variants. The characteristic amide I band shape of such small beta-hairpin peptides appears to arise from the structure of the short antiparallel beta-sheet strands. The role of structural parameter fluctuation in vibrational coupling is evaluated by comparison of DFT-derived amide coupling constants for selected configurations and from transition dipole coupling calculations of coupling parameters between (13)C isotopically labeled residues for a MD-derived ensemble of configurations. Calculated results were compared with the experimentally obtained spectra for several (13)C isotope-labeled peptides of this sequence.
Cooperative Effects of Noise and Coupling on Stochastic Dynamics of a Membrane-Bulk Coupling Model
Institute of Scientific and Technical Information of China (English)
TANG Jun; JIA Ya; YI Ming
2009-01-01
Based on a membrane-bulk coupling cell model proposed by Gomez-Marin et al. [ Phys. Rev. Lett. 98 (2007) 168303], the cooperative effects of noise and coupling on the stochastic dynamical behavior are investigated, For parameters in a certain region, the oscillation can be induced by the cooperative effect of noise and coupling. Whether considering the coupling or not, corresponding coherence resonance phenomena are observed. Furthermore, the effects of two coupling parameters, cell size L and coupling intensity k, on the noise-induced oscillation of membranes are studied. Contrary effects of noise are found in and out of the deterministic oscillatory regions.
Stabilization for the Vibrations Modeled by the `Standard Linear Model' of Viscoelasticity
Indian Academy of Sciences (India)
Ganesh C Gorain
2010-09-01
We study the stabilization of vibrations of a flexible structure modeled by the `standard linear model’ of viscoelasticity in a bounded domain in $\\mathbb{R}^n$ with a smooth boundary. We prove that amplitude of the vibrations remains bounded in the sense of a suitable norm in a space $\\mathbb{X}$, defined explicitly in (22) subject to a restriction on the uncertain disturbing forces on $\\mathbb{X}$. We also estimate the total energy of the system over time interval [0,] for any >0, with a tolerance level of the disturbances. Finally, when the input disturbances are insignificant, uniform exponential stabilization is obtained and an explicit form for the energy decay rate is derived. These results are achieved by a direct method under undamped mixed boundary conditions.
Ground vibrations due to pile and sheet pile driving : prediction models of today
Deckner, Fanny; Viking, Kenneth; Hintze, Staffan
2012-01-01
As part of aconstruction work pile and sheet pile driving unavoidably generates vibrations.As of today construction works are often located in urban areas and along withsociety’s increasing concern of environmental impact the need for vibrationprediction prior to construction is of immediate interest. This study presents a review of the predictionmodels existing today. For prediction of ground vibrations from pile and sheetpile driving there are roughly three different types of models; empiri...
Jiménez-Alonso, J. F.; Sáez, A.
2014-01-01
Although the scientific community had knowledge of the human induced vibration problems in structures since the end of the 19th century, it was not until the occurrence of the vibration phenomenon happened in the Millennium Bridge (London, 2000) that the importance of the problem revealed and a higher level of attention devoted. Despite the large advances achieved in the determination of the human-structure interaction force, one of the main deficiencies of the existing models is the exclusio...
Anharmonic double-{gamma} vibrations in nuclei and their description in the interacting boson model
Energy Technology Data Exchange (ETDEWEB)
Garcia-Ramos, J.E.; Alonso, C.E.; Arias, J.M. [Sevilla Univ. (Spain). Departamento de Fisica Atomica, Molecular y Nuclear; Van Isacker, P. [Grand Accelerateur National d`Ions Lourds, 14 - Caen (France)
1998-07-01
Double-{gamma} vibrations in deformed nuclei are studied in the context of the interacting boson model with special reference to their anharmonic character. It is shown that large anharmonicities can be obtained with interactions that are (at least) of three-body nature between the bosons. As an example the {gamma} vibrations of the nucleus {sub 68}{sup 166}Er{sub 98} are studied in detail. (author) 28 refs.
Sánchez-Castellanos, Mariano; Bucio, María A; Hernández-Barragán, Angelina; Joseph-Nathan, Pedro; Cuevas, Gabriel; Quijano, Leovigildo
2015-03-01
The absolute configuration of was deduced by vibrational circular dichroism together with the evaluation of the Flack and Hooft X-ray parameters. Vibrational circular dichroism exciton coupling, using the carbonyl group signals, confirmed the absolute configuration of . In addition, sodium borohydride reduction of the 11,13-double bond of 6-epi-desacetyllaurenobiolide () yields an almost equimolecular mixture of C11 epimers, while reduction of the same double bond of 6-epi-laurenobiolide () provided almost exclusively the (11S) diastereoisomer . © 2015 Wiley Periodicals, Inc.
Study on electromechanical coupling nonlinear vibration of flywheel energy storage system
Institute of Scientific and Technical Information of China (English)
JIANG; Shuyun
2006-01-01
The electromechanical coupling dynamics of the flywheel energy storage system (FESS) with a hybrid permanent magnetic-dynamic spiral groove bearing has been studied. The functions of the kinetic energy, the potential energys, the magnetic field energy in air gap of the flywheel motor and the energy dissipation of the whole system were obtained, and the differential equations set with electromagnetic parameters of FESS was established by applying the extended Lagrange-Maxwell equation. The four-order implicit Runge-Kutta formula to the equations was derived, and the nonlinear algebraic equations were solved by using the Gauss-Newton method. The analytical solution of an example shows that the upper damping coefficient, the lower damping coefficient and the residual magnetic induction of the rare earth permanent magnet play an important role in electromechanical resonance of the flywheel rotor system. There is a small change for the electromechanical coupling resonance frequency with the upper damping coefficient increasing, but the resonance amplitude decreases with the upper damping coefficient increasing. With the lower damping coefficient increasing, the resonance frequency increases, and the resonance amplitude decreases. With the residual magnetic induction of the permanent magnet increasing, the resonance frequency decreases, and the resonance amplitude increases.
Toutounji, Mohamad
2005-03-22
While an optical linear response function of linearly and quadratically coupled mixed quantum-classical condensed-phase systems was derived by Toutounji [J. Chem. Phys. 121, 2228 (2004)], the corresponding analytical optical line shape is derived. The respective nonlinear correlation functions are also derived. Model calculations involving photon-echo, pump-probe, and hole-burning signals of model systems with both linear and quadratic coupling are provided. Hole-burning formula of Hayes-Small is compared to that of Mukamel in mixed quantum-classical systems.
Modeling and analysis of the transient vibration of camshaft in multi-cylinder diesel engine
Directory of Open Access Journals (Sweden)
Jie Guo
2015-11-01
Full Text Available The dynamics and vibrations of camshaft excited by multi-follower elements are modeled and analyzed. A pushrod valve train system from a four-cylinder diesel engine is selected as the case study. The camshaft is modeled to analyze the interactions of multi-follower elements. Both the camshaft angular vibration and bending vibration are taken into consideration. Each follower element is simplified as a multi-mass system. The lumped masses are connected by the spring elements and the damping elements. The contact force model at the cam–tappet interfaces was developed based on the elasto-hydrodynamic lubrication theory of finite line conjunction. From the analysis results, it can be seen that the bending vibration of camshaft is mainly in the normal direction at the cam–tappet interfaces. Moreover, the bending vibration is mainly influenced by the overlapping of inlet cam function and exhaust cam function of each cylinder. The angular vibration of camshaft mainly focuses at the fundamental frequency and the harmonic frequency corresponding to the cylinder number.
Thawing model and symmetry breaking in a coupled quintessence model
Honardoost, M; Sepangi, H R
2015-01-01
We consider the thawing model in the framework of coupled quintessence scenario. The effective potential has $Z_2$ symmetry which is broken spontaneously when dark matter density becomes less than a critical value leading the quintessence equation of state parameter to deviate from -1. Conditions required for this procedure are obtained and analytical solution for the equation of state parameter is derived.
Vibration energy harvesting by a Timoshenko beam model and piezoelectric transducer
Stoykov, S.; Litak, G.; Manoach, E.
2015-11-01
An electro-mechanical system of vibrational energy harvesting is studied. The beam is excited by external and kinematic periodic forces and damped by an electrical resistor through the coupled piezoelectric transducer. Nonlinearities are introduced by stoppers limiting the transverse displacements of the beam. The interaction between the beam and the stoppers is modeled as Winkler elastic foundation. The mechanical properties of the piezoelectric layer are taken into account and the beam is modeled as a composite structure. For the examined composite beam, the geometrically nonlinear version of the Timoshenko's beam theory is assumed. The equations of motion are derived by the principle of virtual work considering large deflections. An isogeometric approach is applied for space discretization and B-Splines are used as shape functions. Finally, the power output and the efficiency of the system due to harmonic excitations are discussed. The influence of the position of the stoppers and their length on the dynamics of the beam and consequently on the power output are analyzed and presented.
Coupled dynamics of vortex-induced vibration and stationary wall at low Reynolds number
Li, Zhong; Jaiman, Rajeev K.; Khoo, Boo Cheong
2017-09-01
The flow past an elastically mounted circular cylinder placed in proximity to a plane wall is numerically studied in both two dimensions (2D) and three dimensions (3D). This paper aims to explain the mechanism of the cylinder bottom shear layer roll-up suppression in the context of laminar vortex-induced vibration (VIV) of a cylinder placed in the vicinity of a plane stationary wall. In 2D simulations, VIV of a near-wall cylinder with structure-to-displaced fluid mass ratios of m* = 2 and 10 is investigated at the Reynolds number of Re = 100 at a representative gap ratio of e/D = 0.90, where e denotes the gap distance between the cylinder surface and the plane wall. First, the cylinder is placed at five different upstream distances, LU, to study the effects of the normalized wall boundary layer thickness, δ /D , on the hydrodynamic quantities involved in the VIV of a near-wall cylinder. It is found that the lock-in range shifts towards the direction of the higher reduced velocity Ur as δ /D increases and that the lock-in range widens as m* reduces. Second, via visualization of the vortex shedding patterns, four different modes are classified and the regime maps are provided for both m* = 2 and 10. Third, the proper orthogonal decomposition analysis is employed to assess the cylinder bottom shear layer roll-up suppression mechanism. For 3D simulations at Re = 200, the circular cylinder of a mass ratio of m* = 10 with a spanwise length of 4D is placed at a gap ratio of e/D = 0.90 and an upstream distance of LU = 10D. The 3D vortex patterns are investigated to re-affirm the vortex shedding suppression mechanism. The pressure distributions around the cylinder are identified within one oscillation cycle of VIV. The pressure and the shear stress distributions on the bottom wall are examined to demonstrate the effects of near-wall VIV on the force distributions along the plane wall. It is found that both the suction pressure and the shear stress right below the cylinder
An Economic Model of Coupled Exponential Maps
López-Ruiz, R; Cosenza, M G; Sánchez, J R
2007-01-01
In this work, an ensemble of economic interacting agents is considered. The agents are arranged in a linear array where only local couplings are allowed. The deterministic dynamics of each agent is given by a map. This map is expressed by two factors. The first one is a linear term that models the expansion of the agent's economy and that is controlled by the {\\it growth capacity parameter}. The second one is an inhibition exponential term that is regulated by the {\\it local environmental pressure}. Depending on the parameter setting, the system can display Pareto or Boltzmann-Gibbs behavior in the asymptotic dynamical regime. The regions of parameter space where the system exhibits one of these two statistical behaviors are delimited. Other properties of the system, such as the mean wealth, the standard deviation and the Gini coefficient, are also calculated.
Teaching Couples Counseling: An Integrative Model
Long, Lynn L.; Burnett, Judith A.
2005-01-01
Traditionally, training in couples counseling has not received equal status as other counseling modalities. Recently, there is renewed interest in specific training for couples counseling as more emphasis is placed on the stability of couple relationships as an important factor for helping families and children function in a society of frequent…
Directory of Open Access Journals (Sweden)
Chunyu Zhao
2009-01-01
Full Text Available The paper focuses on the quantitative analysis of the coupling dynamic characteristics of two non-identical exciters in a non-resonant vibrating system. The load torque of each motor consists of three items, including the torque of sine effect of phase angles, that of coupling sine effect and that of coupling cosine effect. The torque of frequency capture results from the torque of coupling cosine effect, which is equal to the product of the coupling kinetic energy, the coefficient of coupling cosine effect, and the sine of phase difference of two exciters. The motions of the system excited by two exciters in the same direction make phase difference close to π and that in opposite directions makes phase difference close to 0. Numerical results show that synchronous operation is stable when the dimensionless relative moments of inertia of two exciters are greater than zero and four times of their product is greater than the square of their coefficient of coupling cosine effect. The stability of the synchronous operation is only dependent on the structural parameters of the system, such as the mass ratios of two exciters to the vibrating system, and the ratio of the distance between an exciter and the centroid of the system to the equivalent radius of the system about its centroid.
Entanglement of resonantly coupled field modes in cavities with vibrating boundaries
Andreata, M A; Dodonov, V V
2002-01-01
We study time dependence of various measures of entanglement (covariance entanglement coefficient, purity entanglement coefficient, normalized distance coefficient, entropic coefficients) between resonantly coupled modes of the electromagnetic field in ideal cavities with oscillating boundaries. Two types of cavities are considered: a three-dimensional cavity possessing eigenfrequencies $\\omega_3=3\\omega_1$, whose wall oscillates at the frequency $\\omega_w=2\\omega_1$, and a one-dimensional (Fabry--Perot) cavity with an equidistant spectrum $\\omega_n= n\\omega_1$, when the distance between perfect mirrors oscillates at the frequencies $\\omega_1$ and $2\\omega_1$. The behaviour of entanglement measures in these cases turns out to be completely different, although all three coefficients demonstrate qualitatively similar time dependences in each case (except for some specific situations, where the covariance entanglement coefficient, based on traces of covariance submatrices, seems to be essentially more sensitive ...
Nucleon scattering on actinides using a dispersive optical model with extended couplings
SoukhovitskiÄ©, E. Sh.; Capote, R.; Quesada, J. M.; Chiba, S.; Martyanov, D. S.
2016-12-01
The Tamura coupling model [Rev. Mod. Phys. 37, 679 (1965), 10.1103/RevModPhys.37.679] has been extended to consider the coupling of additional low-lying rotational bands to the ground-state band. Rotational bands are built on vibrational bandheads (even-even targets) or single-particle bandheads (odd-A targets) including both axial and nonaxial deformations. These additional excitations are introduced as a perturbation to the underlying axially symmetric rigid-rotor structure of the ground-state rotational band. Coupling matrix elements of the generalized optical model are derived for extended multiband transitions in even-even and odd-A nuclei. Isospin symmetric formulation of the optical model is employed. A coupled-channels optical-model potential (OMP) containing a dispersive contribution is used to fit simultaneously all available optical experimental databases including neutron strength functions for nucleon scattering on 232Th,233,235,238U, and 239Pu nuclei. Quasielastic (p ,n ) scattering data on 232Th and 238U to the isobaric analog states of the target nucleus are also used to constrain the isovector part of the optical potential. Lane consistent OMP is derived for all actinides if corresponding multiband coupling schemes are defined. For even-even (odd-A ) actinides almost all low-lying collective levels below 1 MeV (0.5 MeV) of excitation energy are coupled. OMP parameters show a smooth energy dependence and energy-independent geometry. A phenomenological optical-model potential that couples multiple bands in odd-A actinides is published for a first time. Calculations using the derived OMP potential reproduce measured total cross-section differences between several actinide pairs within experimental uncertainty for incident neutron energies from 50 keV up to 150 MeV. The importance of extended coupling is studied. Multiband coupling is stronger in even-even targets owing to the collective nature of the coupling; the impact of extended coupling on
DEFF Research Database (Denmark)
Zhang, Zili; Nielsen, Søren R. K.; Basu, Biswajit
2015-01-01
Tuned liquid dampers (TLDs) utilize the sloshing motion of the fluid to suppress structural vibrations and become a natural candidate for damping vibrations in rotating wind turbine blades. The centrifugal acceleration at the tip of a wind turbine blade can reach a magnitude of 7–8g. This facilit......Tuned liquid dampers (TLDs) utilize the sloshing motion of the fluid to suppress structural vibrations and become a natural candidate for damping vibrations in rotating wind turbine blades. The centrifugal acceleration at the tip of a wind turbine blade can reach a magnitude of 7–8g...... studied in the numerical simulation. It is shown that the one-mode model is able to predict the sloshing force and the damped structural response accurately, since the primary damping effect on the structure is achieved by the first sloshing mode of the fluid. Although it is unable to predict the fluid...
Microscopic derivation of nuclear rotation-vibration model, axially symmetric case
Gulshani, Parviz
2015-01-01
We derive from first principles the successful phenomenological hydrodynamic model of Bohr-Davydov-Faessler-Greiner for rotation-vibration motion of an axially symmetric deformed nucleus. The derivation is not limited to small oscillation amplitude, and provides microscopic expressions for the interaction operators among the rotation, vibration, and intrinsic motions, for the moment of inertia, vibration mass, and for the deformation variables. The method uses canonical transformations to collective co-ordinates, followed by a constrained variational method, with the associated constraints imposed on the wavefunction rather than on the particle co-ordinates. The approach yields three self-consistent, time-reversal invariant, cranking-type Schrodinger equations for the rotation-vibration and intrinsic motions, and a self-consistency equation. For deformed harmonic oscillator mean-field potentials, these equations are solved in closed forms for the energies, moments of inertia, quadrupole moments and transition...
Jeong, M K; Hwang, C; Nam, H; Cho, Y S; Kang, B Y; Cho, E C
2017-02-01
The purpose of this study was to determine how the energies supplied from a cosmetic vibrator are deeply or far transferred into organs and tissues, and how these depths or distances are influenced by tissue elasticity. External vibration energy was applied to model skin surfaces through a facial cleansing vibrator, and we measured a distance- and depth-dependent energy that was transferred to model skin matrices. As model skin matrices, we synthesized hard and soft poly(dimethylsiloxane) (PDMS) gels, as well as hydrogels with a modulus of 2.63 MPa, 0.33 MPa and 21 kPa, respectively, mostly representing those of skin and other organs. The transfer of vibration energy was measured either by increasing the separation distances or by increasing the depth from the vibrator. The energies were transmitted deeper into the hard PDMS than into the soft PDMS and hydrogel matrices. This finding implies that the vibration forces influence a larger area of the gel matrices when the gels are more elastic (or rigid). There were no appreciable differences between the soft PDMS and hydrogel matrices. However, the absorbed energies were more concentrated in the area closest to the vibrator with decreasing elasticity of the matrix. Softer materials absorbed most of the supplied energy around the point of the vibrator. In contrast, harder materials scattered the external energy over a broad area. The current results are the first report in estimating how the external energy is deeply or distantly transferred into a model skins depending on the elastic moduli of the models skins. In doing so, the results would be potentially useful in predicting the health of cells, tissues and organs exposed to various stimuli. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.
Mosavi, A. A.; Dickey, D.; Seracino, R.; Rizkalla, S.
2012-01-01
This paper presents a study for identifying damage locations in an idealized steel bridge girder using the ambient vibration measurements. A sensitive damage feature is proposed in the context of statistical pattern recognition to address the damage detection problem. The study utilizes an experimental program that consists of a two-span continuous steel beam subjected to ambient vibrations. The vibration responses of the beam are measured along its length under simulated ambient vibrations and different healthy/damage conditions of the beam. The ambient vibration is simulated using a hydraulic actuator, and damages are induced by cutting portions of the flange at two locations. Multivariate vector autoregressive models were fitted to the vibration response time histories measured at the multiple sensor locations. A sensitive damage feature is proposed for identifying the damage location by applying Mahalanobis distances to the coefficients of the vector autoregressive models. A linear discriminant criterion was used to evaluate the amount of variations in the damage features obtained for different sensor locations with respect to the healthy condition of the beam. The analyses indicate that the highest variations in the damage features were coincident with the sensors closely located to the damages. The presented method showed a promising sensitivity to identify the damage location even when the induced damage was very small.
Institute of Scientific and Technical Information of China (English)
HE Zheng-You; ZHOU Yu-Rong
2011-01-01
The vibrational resonance and stochastic resonance phenomena in the FitzHugh-Nagumo (FHN) neural model,driven by a high-frequency (HF) signal and a low-frequency (LF) signal and by coupled multiplicative and additive noises,is investigated.For the case that the frequency of the HF signal is much higher than that of the LF signal,under the adiabatic approximation condition,the expression of the signal-to-noise ratio (SNR) with respect to the LF signal is obtained.It is shown that the SNR is a non-monotonous function of the amplitude and frequency of the HF signal In addition,the SNR varies non-monotonically with the increasing intensities of the multiplicative and additive noise as well as with the increasing system parameters of the FHN model The influence of the coupling strength between the multiplicative and additive noises on the SNR is discussed.Stochastic resonance (SR) describes the phenomenon where an appropriate amount of noise is of constructive use in the sense that a weak signal becomes amplified upon harvesting the ambient noise in nonlinear systems.[1] Since its first discovery in the early eighties,SR has been observed in a great variety of systems pertaining to different disciplines such as physics,chemistry,engineering,biology and biomedical sciences.[1-4] The phenomenon vibrational resonance (VR) was named by Landa and McClintock.[5]%The vibrational resonance and stochastic resonance phenomena in the FitzHugh-Nagumo (FHN) neural model, driven by a high-frequency (HF) signal and a low-frequency (LF) signal and by coupled multiplicative and additive noises, is investigated. For the case that the frequency of the HF signal is much higher than that of the LF signal, under the adiabatic approximation condition, the expression of the signal-to-noise ratio (SNR) with respect to the LF signal is obtained. It is shown that the SNR is a non-monotonous function of the amplitude and frequency of the HF signal. In addition, the SNR varies non
Plattenburg, Joseph; Dreyer, Jason T.; Singh, Rajendra
2016-06-01
This paper proposes a new analytical model for a thin cylindrical shell that utilizes a homogeneous cardboard liner to increase modal damping. Such cardboard liners are frequently used as noise and vibration control devices for cylindrical shell-like structures in automotive drive shafts. However, most prior studies on such lined structures have only investigated the associated damping mechanisms in an empirical manner. Only finite element models and experimental methods have been previously used for characterization, whereas no analytical studies have addressed sliding friction interaction at the shell-liner interface. The proposed theory, as an extension of a prior experimental study, uses the Rayleigh-Ritz method and incorporates material structural damping along with frequency-dependent viscous and Coulomb interfacial damping formulations for the shell-liner interaction. Experimental validation of the proposed model, using a thin cylindrical shell with three different cardboard liner thicknesses, is provided to validate the new model, and to characterize the damping parameters. Finally, the model is used to investigate the effect of the liner and the damping parameters on the modal attenuation of the shell vibration, in particular for the higher-order coupled shell modes.
Ghadiri, Majid; Shafiei, Navvab; Alireza Mousavi, S.
2016-09-01
Due to having difficulty in solving governing nonlinear differential equations of a non-uniform microbeam, a few numbers of authors have studied such fields. In the present study, for the first time, the size-dependent vibration behavior of a rotating functionally graded (FG) tapered microbeam based on the modified couple stress theory is investigated using differential quadrature element method (DQEM). It is assumed that physical and mechanical properties of the FG microbeam are varying along the thickness that will be defined as a power law equation. The governing equations are determined using Hamilton's principle, and DQEM is presented to obtain the results for cantilever and propped cantilever boundary conditions. The accuracy and validity of the results are shown in several numerical examples. In order to display the influence of size on the first two natural frequencies and consequently changing of some important microbeam parameters such as material length scale, rate of cross section, angular velocity and gradient index of the FG material, several diagrams and tables are represented. The results of this article can be used in designing and optimizing elastic and rotary-type micro-electro-mechanical systems like micro-motors and micro-robots including rotating parts.
Struts, A. V.; Barmasov, A. V.; Brown, M. F.
2015-05-01
Here we review the application of modern spectral methods for the study of G-protein-coupled receptors (GPCRs) using rhodopsin as a prototype. Because X-ray analysis gives us immobile snapshots of protein conformations, it is imperative to apply spectroscopic methods for elucidating their function: vibrational (Raman, FTIR), electronic (UV-visible absorption, fluorescence) spectroscopies, and magnetic resonance (electron paramagnetic resonance, EPR), and nuclear magnetic resonance (NMR). In the first of the two companion articles, we discuss the application of optical spectroscopy for studying rhodopsin in a membrane environment. Information is obtained regarding the time-ordered sequence of events in rhodopsin activation. Isomerization of the chromophore and deprotonation of the retinal Schiff base leads to a structural change of the protein involving the motion of helices H5 and H6 in a pH-dependent process. Information is obtained that is unavailable from X-ray crystallography, which can be combined with spectroscopic studies to achieve a more complete understanding of GPCR function.
Wang, Chang; Wu, Hong-Lin; Song, Yun-Fei; He, Xing; Yang, Yan-Qiang; Tan, Duo-Wang
2016-11-01
The structural deformation induced by intense laser field of liquid nitrobenzene (NB) molecule, a typical molecule with restricting internal rotation, is tracked by time- and frequency-resolved coherent anti-Stokes. Raman spectroscopy (CARS) technique with an intense pump laser. The CARS spectra of liquid NB show that the NO2 torsional mode couples with the NO2 symmetric stretching mode, and the NB molecule undergoes ultrafast structural deformation with a relaxation time of 265 fs. The frequency of NO2 torsional mode in liquid NB (42 cm-1) at room temperature is found from the sum and difference combination bands involving the NO2 symmetric stretching mode and torsional mode in time- and frequency-resolved CARS spectra. Project supported by the National Natural Science Foundation of China (Grant Nos. 21173063 and 21203047), the Foundation of Heilongjiang Bayi Agricultural University, China (Grant No. XZR2014-16), NSAF (Grant No. U1330106), and the Special Research Project of National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics (Grant No. 2012-S-07).
Developing Uncertainty Models for Robust Flutter Analysis Using Ground Vibration Test Data
Potter, Starr; Lind, Rick; Kehoe, Michael W. (Technical Monitor)
2001-01-01
A ground vibration test can be used to obtain information about structural dynamics that is important for flutter analysis. Traditionally, this information#such as natural frequencies of modes#is used to update analytical models used to predict flutter speeds. The ground vibration test can also be used to obtain uncertainty models, such as natural frequencies and their associated variations, that can update analytical models for the purpose of predicting robust flutter speeds. Analyzing test data using the -norm, rather than the traditional 2-norm, is shown to lead to a minimum-size uncertainty description and, consequently, a least-conservative robust flutter speed. This approach is demonstrated using ground vibration test data for the Aerostructures Test Wing. Different norms are used to formulate uncertainty models and their associated robust flutter speeds to evaluate which norm is least conservative.
Dynamic model of vertical vehicle-subgrade coupled system under secondary suspension
Institute of Scientific and Technical Information of China (English)
LIANG Bo; LUO Hong; MA Xue-ning
2007-01-01
As it is known, track transportation can be divided into track system above and track system below. While the train is moving, the parts above and below are interacted and influenced. Therefore, in fact, the problem of track transportation is the match between the vehicle and the railway line system. In this paper, on a basis of dynamic analysis of the vehicle-subgrade model of vertical coupled system under primary suspension,utilizing track maintenance standard and simulating track irregularity excitation, the dynamic interaction of vehicle-track-subgrade system is researched in theory and dynamic model of the vertical vehicle-track-subgrade coupled system under secondary suspension is established by compatibility condition of deformation. Even this model considers the actual structure of a vehicle, also considers vibration characteristic of the substructure of track including subgrade and foundation. All these work want to be benefit for understanding and design about the dynamic characters of subgrade in high speed railway.
DEFF Research Database (Denmark)
Dantan, Aurélien; Marler, Joan; Albert, Magnus
2010-01-01
We report on a novel noninvasive method to determine the normal mode frequencies of ion Coulomb crystals in traps based on the resonance enhanced collective coupling between the electronic states of the ions and an optical cavity field at the single photon level. Excitations of the normal modes...... are observed through a Doppler broadening of the resonance. An excellent agreement with the predictions of a zero-temperature uniformly charged liquid plasma model is found. The technique opens up for investigations of the heating and damping of cold plasma modes, as well as the coupling between them....
Toutounji, Mohamad
2004-08-01
Optical linear response function of linearly and quadratically coupled mixed quantum-classical condensed phase systems is derived. The linear response function is derived using Kapral's formalism of statistical mechanics in mixed quantum-classical systems. Our mixed quantum-classical linear dipole moment correlation function J(t) is compared with the full quantum J(t) [Y. J. Yan and S. Mukamel, J. Chem. Phys. 85, 5908 (1986)] in the high temperature limit. Model calculations and discussion of our results are presented. Various formulas of Franck-Condon factors for both linear and quadratic coupling are discussed. (c) 2004 American Institute of Physics.
Ansari, R.; Rouhi, S.; Aryayi, M.
2016-01-01
The vibrational behavior of double-walled carbon nanotubes is studied by the use of the molecular structural and cylindrical shell models. The spring elements are employed to model the van der Waals interaction. The effects of different parameters such as geometry, chirality, atomic structure and end constraint on the vibration of nanotubes are investigated. Besides, the results of two aforementioned approaches are compared. It is indicated that by increasing the nanotube side length and radius, the computationally efficient cylindrical shell model gives rational results.
MODELING INFLUENCE OF ROLLING BEARING BUSH AND VIBRATION DAMPING IN CATCHING OF TOOTHED WHEELS
Directory of Open Access Journals (Sweden)
P. V. Diachenko
2010-11-01
Full Text Available On the base of dynamic scheme of toothing, a mathematical model for study of the influence of constructive parameters of radial bearings such as a factor of friction, reduced masses and stiffnesses on damping the vibrations in gearing is developed. The solution for the model is obtained using a simulation modeling in the Simulink environment with checking the validity of results in the system MathCad. The oscillograms of the vibrations under investigation and the conclusions on the base of their analysis are presented.
Boz, Utku; Basdogan, Ipek
2015-12-01
Structural vibrations is a major cause for noise problems, discomfort and mechanical failures in aerospace, automotive and marine systems, which are mainly composed of plate-like structures. In order to reduce structural vibrations on these structures, active vibration control (AVC) is an effective approach. Adaptive filtering methodologies are preferred in AVC due to their ability to adjust themselves for varying dynamics of the structure during the operation. The filtered-X LMS (FXLMS) algorithm is a simple adaptive filtering algorithm widely implemented in active control applications. Proper implementation of FXLMS requires availability of a reference signal to mimic the disturbance and model of the dynamics between the control actuator and the error sensor, namely the secondary path. However, the controller output could interfere with the reference signal and the secondary path dynamics may change during the operation. This interference problem can be resolved by using an infinite impulse response (IIR) filter which considers feedback of the one or more previous control signals to the controller output and the changing secondary path dynamics can be updated using an online modeling technique. In this paper, IIR filtering based filtered-U LMS (FULMS) controller is combined with online secondary path modeling algorithm to suppress the vibrations of a plate-like structure. The results are validated through numerical and experimental studies. The results show that the FULMS with online secondary path modeling approach has more vibration rejection capabilities with higher convergence rate than the FXLMS counterpart.
Vortex-induced vibration of a slender single-span cylinder
Oikou, N.
2014-01-01
The goal of this paper is to study the vortex-induced vibration of slender cylindrical structures. For this purpose, a 2D model that calculates the coupled cross-flow and in-line vibrations of a flexible single span beam is developed. A wake oscillator known to match well with free vibration experim
Directory of Open Access Journals (Sweden)
Xu Liu
2015-01-01
Full Text Available Unsteady aerodynamic system modeling is widely used to solve the dynamic stability problems encountering aircraft design. In this paper, single degree-of-freedom (SDF vibration model and forced simple harmonic motion (SHM model for dynamic derivative prediction are developed on the basis of modified Etkin model. In the light of the characteristics of SDF time domain solution, the free vibration identification methods for dynamic stability parameters are extended and applied to the time domain numerical simulation of blunted cone calibration model examples. The dynamic stability parameters by numerical identification are no more than 0.15% deviated from those by experimental simulation, confirming the correctness of SDF vibration model. The acceleration derivatives, rotary derivatives, and combination derivatives of Army-Navy Spinner Rocket are numerically identified by using unsteady N-S equation and solving different SHV patterns. Comparison with the experimental result of Army Ballistic Research Laboratories confirmed the correctness of the SHV model and dynamic derivative identification. The calculation result of forced SHM is better than that by the slender body theory of engineering approximation. SDF vibration model and SHM model for dynamic stability parameters provide a solution to the dynamic stability problem encountering aircraft design.
Energy Technology Data Exchange (ETDEWEB)
Bhaskar, K. Krishna; Saheb, K. Meera [University College of Engineering, Kakinada (India)
2017-05-15
We propose a novel method, known as Coupled displacement field (CDF) method, an alternative to study large amplitude free vibration behavior of moderately thick rectangular plates. An admissible trial function was assumed for one of the variables, say, the total rotations (in both X, Y directions). The function for lateral displacement field is derived in terms of the total rotations with the help of coupling equations, where the two independent variables become dependent on one another. This method makes use of the energy formulation, where it contains only half the number of undetermined coefficients when compared with conventional Rayleigh-Ritz method. The vibration problem is simplified significantly due to the reduction in number of undetermined coefficients. The frequency -amplitude relationship for the moderately thick rectangular plates with various aspect ratios for all edges simply supported and clamped boundary conditions was obtained. Closed form expressions for linear and nonlinear fundamental frequency parameters were derived.
Coupling approaches used in atmospheric entry models
Gritsevich, M. I.
2012-09-01
While a planet orbits the Sun, it is subject to impact by smaller objects, ranging from tiny dust particles and space debris to much larger asteroids and comets. Such collisions have taken place frequently over geological time and played an important role in the evolution of planets and the development of life on the Earth. Though the search for near-Earth objects addresses one of the main points of the Asteroid and Comet Hazard, one should not underestimate the useful information to be gleaned from smaller atmospheric encounters, known as meteors or fireballs. Not only do these events help determine the linkages between meteorites and their parent bodies; due to their relative regularity they provide a good statistical basis for analysis. For successful cases with found meteorites, the detailed atmospheric path record is an excellent tool to test and improve existing entry models assuring the robustness of their implementation. There are many more important scientific questions meteoroids help us to answer, among them: Where do these objects come from, what are their origins, physical properties and chemical composition? What are the shapes and bulk densities of the space objects which fully ablate in an atmosphere and do not reach the planetary surface? Which values are directly measured and which are initially assumed as input to various models? How to couple both fragmentation and ablation effects in the model, taking real size distribution of fragments into account? How to specify and speed up the recovery of a recently fallen meteorites, not letting weathering to affect samples too much? How big is the pre-atmospheric projectile to terminal body ratio in terms of their mass/volume? Which exact parameters beside initial mass define this ratio? More generally, how entering object affects Earth's atmosphere and (if applicable) Earth's surface? How to predict these impact consequences based on atmospheric trajectory data? How to describe atmospheric entry
Analysis of Vibrations Generated by the Presence of Corrugation in a Modeled Tram Track
Directory of Open Access Journals (Sweden)
Julia I. Real Herráiz
2015-01-01
Full Text Available In recent years, there has been a significant increase in the development of the railway system. Despite the huge benefits of railways, one of the main drawbacks of this mode of transport is vibrations caused by vehicles in service, especially in the case of trams circulating in urban areas. Moreover, this undesirable phenomenon may be exacerbated by the presence of irregularities in the rail-wheel contact. Thus, an analytical model able to reproduce the vibrational behavior of a real stretch of tram track was implemented. Besides, a simulation of different types of corrugation was carried out by calculating in an auxiliary model the dynamic overloads generated by corrugation. These dynamic overloads fed the main model to obtain the vibrations generated and then transmitted to the track.
Vibrational spectroscopy modeling of a drug in molecular solvents and enzymes
Devereux, Christian J.; Fulfer, Kristen D.; Zhang, Xiaoliu; Kuroda, Daniel G.
2017-09-01
Modeling of drugs in enzymes is of immensurable value to many areas of science. We present a theoretical study on the vibrational spectroscopy of Rilpivirine, a HIV reverse transcriptase inhibitor, in conventional solvents and in clinically relevant enzymes. The study is based on vibrational spectroscopy modeling of the drug using molecular dynamics simulations, DFT frequency maps, and theory. The modeling of the infrared lineshape shows good agreement with experimental data for the drug in molecular solvents where the local environment motions define the vibrational band lineshape. On the other hand, the theoretical description of the drug in the different enzymes does not match previous experimental findings indicating that the utilized methodology might not apply to heterogeneous environments. Our findings show that the lack of reproducibility might be associated with the development of the frequency map which does not contain all of the possible interactions observed in such systems.
Explicit Correlated Exciton-Vibrational Dynamics of the FMO Complex
Schulze, Jan
2015-01-01
The coupled exciton-vibrational dynamics of a 3-site FMO model is investigated using the numerically exact multilayer multiconfiguration time-dependent Hartree approach. Thereby the vibrational mode specific coupling to local electronic transitions is adapted from a discretized experimental spectral density. The solution of the resulting time-dependent Schr\\"odinger equation including three electronic and 450 vibrational degrees of freedom is analyzed in terms of excitonic populations and coherences. Emphasis is put onto the role of specific ranges of vibrational frequencies. It is observed that modes between 160 and 300 cm$^{-1}$ are responsible for the subpicosecond population and coherence decay.
A THERMO-ELECTRO-HYDRODYNAMIC MODEL FOR VIBRATION-ELECTROSPINNING PROCESS
Lan Xu; Liang Wang; Naeem Faraz
2011-01-01
In this paper, a thermo-electro-hydrodynamic model of the vibration- electrospinning process is first established. The model can offer in-depth insight into physical understanding of many complex phenomena which can not be fully explained experimentally. It is a powerful tool to controlling over physical characters.
A THERMO-ELECTRO-HYDRODYNAMIC MODEL FOR VIBRATION-ELECTROSPINNING PROCESS
Directory of Open Access Journals (Sweden)
Lan Xu
2011-01-01
Full Text Available In this paper, a thermo-electro-hydrodynamic model of the vibration- electrospinning process is first established. The model can offer in-depth insight into physical understanding of many complex phenomena which can not be fully explained experimentally. It is a powerful tool to controlling over physical characters.
DEFF Research Database (Denmark)
Sørensen, Paul Haase; Baungaard, Jens Rane
1996-01-01
A general model for a rotating homogenous flexible robot link is developed. The model describes two-dimensional transverse vibrations induced by the actuator due to misalignment of the actuator axis of rotation relative to the link symmetry axis and due to translational acceleration of the link...
Weigel, Alexander; Dobryakov, Alexander L; Veiga, Manoel; Pérez Lustres, J Luis
2008-11-27
Femtosecond dynamics of riboflavin, the parent chromophore of biological blue-light receptors, was measured by broadband transient absorption and stationary optical spectroscopy in polar solution. Rich photochemistry is behind the small spectral changes observed: (i) loss of oscillator strength around time zero, (ii) sub-picosecond (ps) spectral relaxation of stimulated emission (SE), and (iii) coherent vibrational motion along a' (in-) and a'' (out-of-plane) modes. Loss of oscillator strength is deduced from the differences in the time-zero spectra obtained in water and DMSO, with stationary spectroscopy and fluorescence decay measurements providing additional support. The spectral difference develops faster than the time resolution (20 fs) and is explained by formation of a superposition state between the optically active (1pi pi*) S1 and closely lying dark (1n pi*) states via vibronic coupling. Subsequent spectral relaxation involves decay of weak SE in the blue, 490 nm, together with rise and red shift of SE at 550 nm. The process is controlled by solvation (characteristic times 0.6 and 0.8 ps in water and DMSO, respectively). Coherent oscillations for a' and a'' modes show up in different regions of the SE band. a'' modes emerge in the blue edge of the SE and dephase faster than solvation. In turn, a' oscillations are found in the SE maximum and dephase on the solvation timescale. The spectral distribution of coherent oscillations according to mode symmetry is used to assign the blue edge of the SE band to a 1n pi*-like state (A''), whereas the optically active 1pi pi* (A') state emits around the SE maximum. The following model comes out: optical excitation occurs to the Franck-Condon pi pi* state, a pi pi*-n pi* superposition state is formed on an ultrafast timescale, vibrational coherence is transferred from a' to a'' modes by pi pi*-n pi* vibronic coupling, and subsequent solvation dynamics alters the pi pi*/n pi* population ratio.
Kryvohuz, M; Marcus, R A
2010-06-14
A classical theory is proposed to describe the non-RRKM effects in activated asymmetric top triatomic molecules observed numerically in classical molecular dynamics simulations of ozone. The Coriolis coupling is shown to result in an effective diffusive energy exchange between the rotational and vibrational degrees of freedom. A stochastic differential equation is obtained for the K-component of the rotational angular momentum that governs the diffusion.
Jacobs, M.H.G.; van den Berg, A.P.; Schmid-Fetzer, R.
2013-01-01
We use Kieffer's model to represent the vibrational density of states (VDoS) and thermodynamic properties of pure substances in pressure-temperature space. We show that this model can be simplified to a vibrational model in which the VDoS is represented by multiple Einstein frequencies without
Modeling of wave propagation in drill strings using vibration transfer matrix methods.
Han, Je-Heon; Kim, Yong-Joe; Karkoub, Mansour
2013-09-01
In order to understand critical vibration of a drill bit such as stick-slip and bit-bounce and their wave propagation characteristics through a drill string system, it is critical to model the torsional, longitudinal, and flexural waves generated by the drill bit vibration. Here, a modeling method based on a vibration transfer matrix between two sets of structural wave variables at the ends of a constant cross-sectional, hollow, circular pipe is proposed. For a drill string system with multiple pipe sections, the total vibration transfer matrix is calculated by multiplying all individual matrices, each is obtained for an individual pipe section. Since drill string systems are typically extremely long, conventional numerical analysis methods such as a finite element method (FEM) require a large number of meshes, which makes it computationally inefficient to analyze these drill string systems numerically. The proposed "analytical" vibration transfer matrix method requires significantly low computational resources. For the validation of the proposed method, experimental and numerical data are obtained from laboratory experiments and FEM analyses conducted by using a commercial FEM package, ANSYS. It is shown that the modeling results obtained by using the proposed method are well matched with the experimental and numerical results.
Finite element modeling and modal analysis of the human spine vibration configuration.
Guo, Li-Xin; Zhang, Yi-Min; Zhang, Ming
2011-10-01
This study was designed to investigate the modal characteristics of the human spine. A 3-D finite element model of the spine T12-Pelvis segment was used to extract resonant frequencies and modal modes of the human spine. By finite element modal analysis and harmonic response analysis, several lower vibration modes in the flexion-extension, lateral bending, and vertical directions were obtained and its vibration configurations were shown in this paper. The results indicate that the lowest resonant frequency of the model is in the flexion-extension direction. The second-order resonant frequency is in the lateral bending direction and the third-order resonant frequency of the T12-Pelvis model is in the vertical direction. The results also show that lumbar spinal vertebrae conduct the rotation action during whole body vibration (WBV). The vibration configurations of the lumbar spine can explore the motion mechanism of different lumbar components under WBV and make us to understand the vibration-induced spine diseases. The findings in this study will be helpful to understand WBV-related injury of the spine in clinics and the ergonomics design and development of mechanical production to protect human spine safety.
Energy Technology Data Exchange (ETDEWEB)
Brahma, K.C.; Pal, B.K.; Das, C. [CMPDI, Bhubaneswar (India)
2005-07-01
Different models of vibration studies are examined. A case analysis to determine the parameters governing the prediction of blast vibration in an opencast coal mine is described. A regression model was developed to evaluate peak particle velocity (PPV) of the blast. The results are applicable to forecasting ground vibration before blasting and to the design of various parameters in controlled blasting. 16 refs., 1 fig., 1 tab.
Modeling the coupling effect of jitter and attitude control on TDICCD camera imaging
Li, Yulun; Yang, Zhen; Ma, Xiaoshan; Ni, Wei
2016-10-01
The vibration has an important influence on space-borne TDICCD imaging quality. It is generally aroused by an interaction between satellite jitter and attitude control. Previous modeling for this coupling relation is mainly concentrating on accurate modal analysis, transfer path and damping design, etc. Nevertheless, when controlling attitude, the coupling terms among three body axes are usually ignored. This is what we try to study in this manuscript. Firstly, a simplified formulation dedicated to this problem is established. Secondly, we use Dymola 2016 to execute the simulation model profiting Modelica synchronous feature, which has been proposed in recent years. The results demonstrate that the studied effect can introduce additional oscillatory modes and lead the attitude stabilization process slower. In addition, when fully stabilized, there seems time-statistically no difference but it still intensifies the motion-blur by a tiny amount. We state that this effect might be worth considering in image restoration.
Lorenz, U.; Saalfrank, P.
2017-01-01
We present a rigorous method to set up a system-bath Hamiltonian for the coupling of adsorbate vibrations (the system) to surface phonons (the bath). The Hamiltonian is straightforward to derive and exact up to second order in the environment coordinates, thus capable of treating one- and two-phonon contributions to vibration-phonon coupling. The construction of the Hamiltonian uses orthogonal coordinates for system and bath modes, is based on an embedded cluster approach, and generalizes previous Hamiltonians of a similar type, but avoids several (additional) approximations. While the parametrization of the full Hamiltonian is in principle feasible by a first principles quantum mechanical treatment, here we adopt in the spirit of a QM/MM model a combination of density functional theory ("QM", for the system) and a semiempirical forcefield ("MM", for the bath). We apply the Hamiltonian to a fully H-covered Si(100)-(2 × 1) surface, using Fermi's Golden Rule to obtain vibrational relaxation rates of various H-Si bending modes of this system. As in earlier work it is found that the relaxation is dominated by two-phonon contributions because of an energy gap between the Si-H bending modes and the Si phonon bands. We obtain vibrational lifetimes (of the first excited state) on the order of 2 ps at T = 0 K. The lifetimes depend only little on the type of bending mode (symmetric vs. antisymmetric, parallel vs. perpendicular to the Si2H2 dimers). They decrease by a factor of about two when heating the surface to 300 K. We also study isotope effects by replacing adsorbed H atoms by deuterium, D. The Si-D bending modes are shifted into the Si phonon band of the solid, opening up one-phonon decay channels and reducing the lifetimes to few hundred fs.
Benjamin, Stan; Sun, Shan; Grell, Georg; Green, Benjamin; Bleck, Rainer; Li, Haiqin
2017-04-01
Extreme events for subseasonal duration have been linked to multi-week processes related to onset, duration, and cessation of blocking events or, more generally, quasi-stationary waves. Results will be shown from different sets of 32-day prediction experiments (3200 runs each) over a 16-year period for earth system processes key for subseasonal prediction for different resolution, numerics, and physics using the FIM-HYCOM coupled model. The coupled atmosphere (FIM) and ocean (HYCOM) modeling system is a relatively new coupled atmosphere-ocean model developed for subseasonal to seasonal prediction (Green et al. 2017 Mon.Wea.Rev. accepted, Bleck et al 2015 Mon. Wea. Rev.). Both component models operate on a common icosahedral horizontal grid and use an adaptive hybrid vertical coordinate (sigma-isentropic in FIM and sigma-isopycnic in HYCOM). FIM-HYCOM has been used to conduct 16 years of subseasonal retrospective forecasts following the NOAA Subseasonal (SubX) NMME protocol (32-day forward integrations), run with 4 ensemble members per week. Results from this multi-year FIM-HYCOM hindcast include successful forecasts out to 14-20 days for stratospheric warming events (from archived 10 hPa fields), improved MJO predictability (Green et al. 2017) using the Grell-Freitas (2014, ACP) scale-aware cumulus scheme instead of the Simplified Arakawa-Schubert scheme, and little sensitivity to resolution for blocking frequency. Forecast skill of metrics from FIM-HYCOM including 500 hPa heights and MJO index is at least comparable to that of the operational Climate Forecast System (CFSv2) used by the National Centers for Environmental Prediction. Subseasonal skill is improved with a limited multi-model (FIM-HYCOM and CFSv2), consistent with previous seasonal multi-model ensemble results. Ongoing work will also be reported on for adding inline aerosol/chemistry treatment to the coupled FIM-HYCOM model and for advanced approaches to subgrid-scale clouds to address regional biases
Directory of Open Access Journals (Sweden)
Myriam Rocío Pallares Muñoz
2010-05-01
Full Text Available Designing mechanical systems which are submitted to vibration requires calculation methods which are very different to those u-sed in other disciplines because, when this occurs, the magnitude of the forces becomes secondary and the frequency with which the force is repeated becomes the most important aspect. It must be taken care of, given that smaller periodic forces can prompt disasters than greater static forces. The article presents a representative problem regarding systems having forced vibration, the mathematical treatment of differential equations from an electrical and mechanical viewpoint, an electrical analogy, numerical modeling of circuits using ANSYS finite element software, analysis and comparison of numerical modeling results compared to test values, the post-processing of results and conclusions regarding electrical analogy methodology when analysing forced vibra-tion systems.
Does more sophisticated modeling reduce model uncertainty? A case study on vibration predictions
Waarts, P.H.; Wit, M.S. de
2004-01-01
In this paper, the reliability of vibration predictions in civil engineering is quantified. Emphasis is laid on the vibration predictions for road- and rail traffic and vibrations from building activities such as (sheet)pile driving. Several kinds of prediction techniques were investigated: expert o
非线性部件的轴系动稳态响应研究%RESEARCH ON STEADY VIBRATION RESPONSE OF SHAFTING WITH NONLINEAR COUPLING
Institute of Scientific and Technical Information of China (English)
龚宪生; 谢志江; 唐一科
2001-01-01
对有局部非线性的船舶推进轴系振动稳态响应进行理论和试验研究。在考虑联轴器非线性刚度和阻尼的情况下,以GLM(Galerkin-Levenberg-Marquardt)法为基础,提出一种分离变换法并编制相应计算程序。用此方法及程序对一单圆盘轴系振动稳态响应进行计算并进行试验。结果表明,计算所获振动稳态响应时间历程与试验所获振动稳态响应时间历程吻合好。%Theoretical and experimental research on steady vibration response of shipping propulsion shafting with local nonlinear characteristics are done. Owing to the coupling with the nonlinear characteristics, it is difficult that steady vibration response of the shafting is got fen by regular solutions. On the basis of GLM(Galerkin-Levenberg-Marquardt) method, a new method that is called the separating and transform algorithm is proposed and programmed. It can be used for calculating steady vibration response of the shafting with the coupling. Steady vibration response of a single disk rotor is calculated using the program and is tested. The results show that the method and the program are useful for calculating steady vibration response of the shafting with local nonlinear dynamic stiffness and damping. Theoretical results obtained by calculating are coincident with experimental one.
Fluid Model of Waveguide Transverse Coupling
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
In this paper, optical fluid is firstly defined. By using the movement law of hydrodynamics, the transverse coupling of waveguides is discussed. The result fully coincides with the electromagnetic solution.
Dompka, R. V.
1989-01-01
Under the NASA-sponsored Design Analysis Methods for VIBrationS (DAMVIBS) program, a series of ground vibration tests and NASTRAN finite element model (FEM) correlations were conducted on the Bell AH-1G helicopter gunship to investigate the effects of difficult components on the vibration response of the airframe. Previous correlations of the AH-1G showed good agreement between NASTRAN and tests through 15 to 20 Hz, but poor agreement in the higher frequency range of 20 to 30 Hz. Thus, this effort emphasized the higher frequency airframe vibration response correlations and identified areas that need further R and T work. To conduct the investigations, selected difficult components (main rotor pylon, secondary structure, nonstructural doors/panels, landing gear, engine, fuel, etc.) were systematically removed to quantify their effects on overall vibratory response of the airframe. The entire effort was planned and documented, and the results reviewed by NASA and industry experts in order to ensure scientific control of the testing, analysis, and correlation exercise. In particular, secondary structure and damping had significant effects on the frequency response of the airframe above 15 Hz. Also, the nonlinear effects of thrust stiffening and elastomer mounts were significant on the low frequency pylon modes below main rotor 1p (5.4 Hz). The results of the ground vibration testing are presented.
Control of a coupled map lattice model for vortex shedding in the wake of a cylinder
Indian Academy of Sciences (India)
G Balasubramanian; D J Olinger; M A Demetriou
2002-07-01
The ﬂow behind a vibrating ﬂexible cable at low Reynolds numbers can exhibit complex wake structures such as lace-like patterns, vortex dislocations and frequency cells. These structures have been observed in experiments and numerical simulations, and are predicted by a previously developed low-order coupled map lattice (CML). The discrete (in time and space) CML models consist of a series of diffusively coupled circle map oscillators along the cable span. Motivated by a desire to modify the complex wake patterns behind ﬂexible vibrating cables, we have studied the addition of control terms into the highly efﬁcient CML models and explored the resulting dynamics. Proportional, adaptive proportional and discontinuous non-linear (DNL) control methods were used to derive the control laws. The ﬁrst method employed occasional proportional feedback. The adaptive method used spatio-temporal feedback control. The DNL method used a discontinuous feedback linearization procedure, and the controller was designed for the resulting linearized system using eigenvalue assignment. These techniques were applied to a modeled vortex dislocation structure in the wake of a vibrating cable in uniform freestream ﬂow. Parallel shedding patterns were achieved for a range of forcing frequency-forcing amplitude combinations studied to validate the control theory. The adaptive proportional and DNL methods were found to be more effective than the proportional control method due to the incorporation of a spatially varying feedback gain across the cylinder span. The DNL method was found to be the most efﬁcient controller of the low-order CML model. The required control level across the cable span was correlated to the 1/1 lock-on behavior of the temporal circle map.
Kumar, Manoranjan; Soos, Zolt'an G.
2011-01-01
The bond order wave (BOW) phase of the extended Hubbard model (EHM) in one dimension (1D) is characterized at intermediate correlation $U = 4t$ by exact treatment of $N$-site systems. Linear coupling to lattice (Peierls) phonons and molecular (Holstein) vibrations are treated in the adiabatic approximation. The molar magnetic susceptibility $\\chi_M(T)$ is obtained directly up to $N = 10$. The goal is to find the consequences of a doubly degenerate ground state (gs) and finite magnetic gap $E_...
Hu, Yan-Gao; Liew, K M; Wang, Q
2011-12-01
Free transverse, longitudinal and torsional vibrations of single-walled carbon nanotubes (SWCNTs) are investigated through nonlocal beam model, nonlocal rod model and verified by molecular dynamics (MD) simulations. The nonlocal Timoshenko beam model offers a better prediction of the fundamental frequencies of shorter SWCNTs, such as a (5, 5) SWCNT shorter than 3.5 nm, than local beam models. The nonlocal rod model is employed to study the longitudinal and torsional vibrations of SWCNT and found to enable a good prediction of the MD results for shorter SWCNTs. Nonlocal and local continuum models provide a good agreement with MD results for relatively longer SWCNTs, such as (5, 5) SWCNTs longer than 3.5 nm. The scale parameter in nonlocal beam and rod models is estimated by calibrations from MD results.
Ong, S W; Lee, B X B; Kang, H C
2011-09-14
We have performed Car-Parrinello molecular dynamics (CPMD) calculations of the hydrogen-bonded NH(3)-HCl dimer. Our main aim is to establish how ionic-orbital coupling in CPMD affects the vibrational dynamics in hydrogen-bonded systems by characterizing the dependence of the calculated vibrational frequencies upon the orbital mass in the adiabatic limit of Car-Parrinello calculations. We use the example of the NH(3)-HCl dimer because of interest in its vibrational spectrum, in particular the magnitude of the frequency shift of the H-Cl stretch due to the anharmonic interactions when the hydrogen bond is formed. We find that an orbital mass of about 100 a.u. or smaller is required in order for the ion-orbital coupling to be linear in orbital mass, and the results for which can be accurately extrapolated to the adiabatic limit of zero orbital mass. We argue that this is general for hydrogen-bonded systems, suggesting that typical orbital mass values used in CPMD are too high to accurately describe vibrational dynamics in hydrogen-bonded systems. Our results also show that the usual application of a scaling factor to the CPMD frequencies to correct for the effects of orbital mass is not valid. For the dynamics of the dimer, we find that the H-Cl stretch and the N-H-Cl bend are significantly coupled, suggesting that it is important to include the latter degree of freedom in quantum dynamical calculations. Results from our calculations with deuterium-substitution show that both these degrees of freedom have significant anharmonic interactions. Our calculated frequency for the H-Cl stretch using the Becke-exchange Lee-Yang-Parr correlation functional compares reasonably well with a previous second-order Møller-Plesset calculation with anharmonic corrections, although it is low compared to the experimental value for the dimer trapped in a neon-matrix. © 2011 American Institute of Physics
Liao, Chan-Yi; Wu, Yi-Chuang; Chang, Ching-Yuan; Ma, Chien-Ching
2017-04-01
This study combined theoretical, experimental, and numerical analysis to investigate the vibration characteristics of a thin rectangular plate positioned horizontally at the bottom of a rectangular container filled with liquid. Flow field pressure was derived using an equation governing the behavior of incompressible fluids. Analytic solutions to vibrations in a thin plate in air served as the fundamental function of the thin plate coupled with liquid. We then used liquid pressure, and the out-of-plane deflection of the thin plate for the construction of frequency response functions for the analysis of vibration characteristics in the liquid-plate coupling system. Two experimental methods were employed to measure the vibration characteristics of the thin plate immersed in water. The first involved using sensors of polyvinylidene difluoride (PVDF) to measure transient signals of fluid-plate system subjected an impact at the thin plate. These were then converted to the frequency domain in order to obtain the resonant frequencies of the fluid-plate coupling system. The second method was amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI), which was used to measure the dynamic characteristics of the thin plate in the flow field. This method was paired with the image processing techniques, temporal speckle pattern interferometry (TSPI) and temporal standard deviation (TSTD), to obtain clear mode shapes of the thin plate and resonant frequencies. Comparison of the results from theoretical analysis, finite element method, and experimental measurements confirmed the accuracy of our theoretical analysis, which was superior to the conventional approach based on beam mode shape functions. The experimental methods proposed in this study can be used to measure the resonant frequencies of underwater thin plates, and clear mode shapes can be obtained using AF-ESPI. Our results indicate that the resonant frequencies of thin plates underwater are lower than
Kiani, Keivan
2017-02-01
A novel surface energy-based model is developed to examine more precisely vibrations of current-carrying double-nanowire-systems immersed in a longitudinal magnetic field. Using Biot-Savart and Lorentz laws, a more refined version of interwire interactional magnetic forces is presented. By employing Rayleigh beam theory, the equations of motion are derived. In fact, these are coupled integro-differential equations which are more accurate with respect to those of the previously developed models. For simply supported and clamped nanosystems, governing equations are analyzed via assumed mode method. The effects of interwire distance, slenderness ratio, electric current, magnetic field strength, and surface effect on the fundamental frequency are addressed carefully. The obtained results display the importance of exploiting the refined model for vibration analysis of nanosystems with low interwire distance, high electric current, and high magnetic field strength.
Three-dimensional modeling of supine human and transport system under whole-body vibration.
Wang, Yang; Rahmatalla, Salam
2013-06-01
The development of predictive computer human models in whole-body vibration has shown some success in predicting simple types of motion, mostly for seated positions and in the uniaxial vertical direction. The literature revealed only a handful of papers that tackled supine human modeling in response to vertical vibration. The objective of this work is to develop a predictive, multibody, three-dimensional human model to simulate the supine human and underlying transport system in response to multidirectional whole-body vibration. A three-dimensional dynamic model of a supine human and its underlying transport system is presented in this work to predict supine-human biodynamic response under three-dimensional input random whole-body vibration. The proposed supine-human model consists of three interconnected segments representing the head, torso-arms, and pelvis-legs. The segments are connected via rotational and translational joints that have spring-damper components simulating the three-dimensional muscles and tissuelike connecting elements in the three x, y, and z directions. Two types of transport systems are considered in this work, a rigid support and a long spinal board attached to a standard military litter. The contact surfaces between the supine human and the underlying transport system are modeled using spring-damper components. Eight healthy supine human subjects were tested under combined-axis vibration files with a magnitude of 0.5 m/s2 (rms) and a frequency content of 0.5-16 Hz. The data from seven subjects were used in parameter identification for the dynamic model using optimization schemes in the frequency domain that minimize the differences between the magnitude and phase of the predicted and experimental transmissibility. The predicted accelerations in the time and frequency domains were comparable to those gathered from experiments under different anthropometric, input vibration, and transport conditions under investigation. Based on the
On the Modeling of a MEMS Based Capacitive Accelerometer for Measurement of Tractor Seat Vibration
Directory of Open Access Journals (Sweden)
M. Alidoost
2010-04-01
Full Text Available Drivers of heavy vehicles often face with higher amplitudes of frequencies range between 1-80 Hz. Hence, this range of frequency results in temporary or even sometimes permanent damages to the health of drivers. Examples for these problems are damages to the vertebral column and early tiredness, which both reduce the driver’s performance significantly. One solution to this problem is to decrease the imposed vibration to the driver’s seat by developing an active seat system. These systems require an online measuring unit to sense vibrations transferred to the seat. The measuring unit can include a capacitive micro-accelerometer on the basis of MEMS which measure online vibrations on the seat. In this study, the mechanical behavior of a capacitive micro-accelerometer for the vibration range applied to a tractor seat has been simulated. The accelerometer is capable to measure step, impact and harmonic external excitations applied to the system. The results of the study indicate that, with increasing the applied voltage, the system sensitivity also increases, but the measuring range of vibrations decreases and vice versa. The modeled accelerometer, at damping ratio of 0.67 is capable to measure accelerations within the frequency range of lower than 130 Hz.
Secondary flows enhance mixing in a model of vibration-assisted dialysis
Pitre, John; Mueller, Bruce; Lewis, Susan; Bull, Joseph
2014-11-01
Hemodialysis is an integral part of treatment for patients with end stage renal disease. While hemodialysis has traditionally been described as a diffusion-dominated process, recent in vitro work has shown that vibration of the dialyzer can enhance the clearance of certain solutes during treatment. We hypothesize that the addition of vibration generates secondary flows in the dialysate compartment. These flows, perpendicular to the longitudinal axis of the dialysis fibers, advect solute away from the fiber walls, thus maintaining a larger concentration gradient and enhancing diffusion. Using the finite element method, we simulated the flow of dialysate through a hexagonally-packed array of cylinders and the transport of solute away from the cylinder walls. The addition of vibration was modeled using sinusoidal body forces of various frequencies and amplitudes. Using the variance of the concentration field as a metric, we found that vibration improves mixing according to a power law dependency on frequency. We will discuss the implications of these computational results on our understanding of the in vitro experiments and propose optimal vibration patterns for improving clearance in dialysis treatments. This work was supported by the Michigan Institute for Clinical and Health Research and NIH Grant UL1TR000433.
Mathematical modelling of friction-vibration interactions of nuclear fuel rods
Directory of Open Access Journals (Sweden)
Zeman V.
2016-06-01
Full Text Available Nuclear fuel rods (FRs are transverselly linked to each other by three spacer grid cells at several vertical levels inside a fuel assembly (FA. Vibration of FA components, caused by the motion of FA support plates in the reactor core, generates variable contact forces between FRs and spacer grid cells. Friction effects in contact surfaces have an influence on the expected lifetime period of nuclear FA in terms of FR cladding fretting wear. This paper introduces an original approach to mathematical modelling and simulation analysis of FR nonlinear vibrations and fretting wear taking into consideration friction forces at all levels of spacer grids.
Comprehensive vibrational analysis of CO2 based on a polyad-preserving model*
Bermudez-Montaña, Marisol; Lemus, Renato; Pérez-Bernal, Francisco; Carvajal, Miguel
2017-06-01
We present a polyad-preserving algebraic approach to molecular structure and, as an application, we fit the model parameters to reproduce an extensive experimental data set of vibrational energies of carbon dioxide in its ground electronic state. The data set includes levels with vibrational angular momentum ℓ = 1, ...,6 and some recently obtained term values that have not been previously considered. The obtained results are close to experimental uncertainty and we compare the results obtained making use of the three most common polyad schemes that can be found in the literature for this molecular species.
Liu, Yang; Shu, Dong-Wei
2014-08-01
Delaminations in structures may significantly reduce the stiffness and strength of the structures and may affect their vibration characteristics. As structural components, beams have been used for various purposes, in many of which beams are often subjected to axial loads and static end moments. In the present study, an analytical solution is developed to study the coupled bending-torsion vibration of a homogeneous beam with a single delamination subjected to axial loads and static end moments. Euler-Bernoulli beam theory and the "free mode" assumption in delamination vibration are adopted. This is the first study of the influences of static end moments upon the effects of delaminations on natural frequencies, critical buckling loads and critical moments for lateral instability. The results show that the effects of delamination on reducing natural frequencies, critical buckling load and critical moment for lateral instability are aggravated by the presence of static end moment. In turn, the effects of static end moments on vibration and instability characteristics are affected by the presence of delamination. The analytical results of this study can serve as a benchmark for finite element method and other numerical solutions.
Vibration measurement of a model wind turbine using high speed photogrammetry
Kalpoe, D.; Khoshelham, K.; Gorte, B.
2011-01-01
We investigate the application of the photogrammetric approach to measuring the vibration of a model wind turbine in a sequence of stereo image pairs acquired by high speed cameras. The challenge of the photogrammetric measurement of a highly dynamic phenomenon is the efficiency of the point measure
DEFF Research Database (Denmark)
Darula, Radoslav; Stein, George Juraj; Kallesøe, Carsten Skovmose
2012-01-01
Electromechanical systems for vibration control exhibit complex non-linear behaviour. Therefore advanced mathematical tools and appropriate simplifications are required for their modelling. To properly understand the dynamics of such a non-linear system, it is necessary to identify the parameters...
Fractal Theory and Contact Dynamics Modeling Vibration Characteristics of Damping Blade
Directory of Open Access Journals (Sweden)
Ruishan Yuan
2014-01-01
Full Text Available The contact surface structure of dry friction damper is complicate, irregular, and self-similar. In this paper, contact surface structure is described with the fractal theory and damping blade is simplified as 2-DOF cantilever beam model with lumped masses. By changing the position of the damper, lacing and shroud structure are separately simulated to study vibration absorption effect of damping blade. The results show that both shroud structure and lacing could not only dissipate energy but also change stiffness of blade. Under the same condition of normal pressure and contact surface, the damping effect of lacing is stronger than that of shroud structure. Meanwhile, the effect on changing blade stiffness of shroud structure is stronger than that of lacing. This paper proposed that there is at least one position of the blade, at which the damper dissipates the most vibration energy during a vibration cycle.
Directory of Open Access Journals (Sweden)
Asan Gani
2010-09-01
Full Text Available Active vibration control of the first three modes of a vibrating cantilever beam using collocated piezoelectric sensor and actuator is examined in this paper. To achieve this, a model based on Euler-Bernoulli beam equation is adopted and extended to the case of three bonded piezoelectric patches that act as sensor, actuator and exciter respectively. A compensated inverse PID controller has been designed and developed to damp first three modes of vibration. Controllers have been designed for each mode and these are later combined in parallel to damp any of the three modes. Individual controller gives better reduction in sensor output for the second and third modes while the combined controller performs better for the first mode. Simulation studies are carried out using MATLAB. These results are compared and verified experimentally and the real-time implementation is carried out with xPC-target toolbox in MATLAB
Directory of Open Access Journals (Sweden)
Yun Wang
2015-06-01
Full Text Available This article conceptually proposes a new method to tune the resonance frequency of piezoelectric vibration energy harvesters, in which the supporting position of the vibrator can be adjusted for frequency tuning. The corresponding analytical model is established to predict the performances of the harvester based on the principles of energy. First, the equivalent stiffness and mass of the vibrator in bending mode are derived explicitly for the different supporting positions. A simple analysis method is then established for the frequency, output voltage, and output power. Finally, some numerical examples are given to demonstrate the presented method. The results are also compared with those by finite element method and good agreement is observed.
Stochastic Response of Energy Balanced Model for Vortex-Induced Vibration
DEFF Research Database (Denmark)
Nielsen, Søren R.K.; Krenk, S.
of lightly damped structures are found on two branches, with the highest amplification branch on the low-frequency branch. The effect free wind turbulence is to destabilize the vibrations on the high amplification branch, thereby reducing the oscillation amplitude. The effect is most pronounced for very......A double oscillator model for vortex-induced oscillations of structural elements based on exact power exchange between fluid and structure, recently proposed by authors, is extended to include the effect of the turbulent component of the wind. In non-turbulent flow vortex-induced vibrations...... lightly damped structures. The character of the structural vibrations changes with increasing turbulence and damping from nearly regular harmonic oscillation to typical narrow-banded stochastic response, closely resembling observed behaviour in experiments and full-scale structures....
Design for Vibrator Field Experiment Based- on Vibrator- earth System
Institute of Scientific and Technical Information of China (English)
Chen Zubin; Lin Jun; Liang Tiecheng; Zhang Linhang
2000-01-01
Source- generated energy in seismic vibrator records high frequency harmonic behavior. Conventional vibratorearth coupling model was set up on the linear system. Some assumptions in the application of linear theory to the vibrator problem play an insignificant role in the overall coupling structure. Obviously, non- linear behaviors can be modeled using a "hard - spring" form of the Duffing equation. Model dedicates that a qualitatively similar harmonic component is present for a broad range of possible mathematical descriptions. After some qualitative analysis about the non- linear system, some conclusion can be drawn. Firstly, The design of the vibrator weight should be abided by two points as followed: In order to avoid decoupling for the vibrator to the earth, the weight should be greater than the peak of the driving force amplitude as to keep the resultant force pointing to the earth's core. On the other hand, for the limited energy output, the vibrator overweight may damage the system high - frequency ability. Secondly, as the driving force frequency approaching to the ground hard- spring inherent frequency, the energy transmission was found to climb its peak from the system energy absorbed curve. At last, due to the non- linear coupling model system, its load curve would come into unstable frequency range,which might limit the application of the Vibroseis conventional sweeping pattern - linear sweep. A new sweeping pattern was listed: the driving signal was the pseudo- random sequence modulated by a fixed frequency cosine signal satisfying with the exploration precision and absorbing efficiency. The synthesized signal was ready to be realized by the electromagnetic driven system. Even the side- lobes noise of its auto- correlation function was restrained well. The theory coming from the Vibrator- earth coupling model was applied to the design of the Portable High- frequency Vibrator System (PHVS), and the good result was obtained. By the analysis of the