Design of Permanent Magnet Synchronous Generators for Wave Power Generation

In this paper, a design method for ocean wave permanent magnet synchronous generator(PMSG)is proposed with new performance criteria to obtain better output performance at the cost of less permanent magnet material. Besides, a simple equivalent analytical geometry method is put forward to calculate the sizes of permanent magnets. Based on geometric and electromagnetic models, four types of rotor structures are compared, i.e., embedded, tangential, tile surface mount and convex surface mount structures. The designs and comparisons of machine are performed with the same permanent magnet volume. Moreover, the influences of mechanical pole-arc coefficient of tile surface mount PMSG on electrical efficiency, output power, material corrosion, core loss, and torque ripple are investigated. Finite-element analysis method is applied to verify the results using Ansoft/Maxwell.

Design, Construction and Ocean Testing of Wave Energy Conversion System with Permanent Magnet Tubular Linear Generator

In this paper, the design, construction and ocean testing of a wave energy conversion system are studied. Based on the motion characteristics of double buoys in ocean waves, a wave energy conversion system with permanent magnet tubular linear generator （PMTLG） is proposed to convert ocean wave energy into electricity. The wave energy conversion system was installed in the Yellow Sea near Lianyungang, China. The ocean test re- suits indicate that it had dynamic and static performance, and obtained an expected amount of electricity. The calcu- lation result indicates the average output power was about 1 000 W, and the conversion efficiency from wave en- ergy into electricity was 1.4%. In addition, the wireless data communication, mechanics and oceanography were also discussed.

Adequate Closed Form Wave Solutions to the Generalized KdV Equation in Mathematical Physics

In this paper, we consider the generalized Korteweg-de-Vries (KdV) equations which are remarkable models of the water waves mechanics, the shallow water waves, the quantum mechanics, the ion acoustic waves in plasma, the electro-hydro-dynamical model for local electric field, signal processing waves through optical fibers, etc. We determine the useful and further general exact traveling wave solutions of the above mentioned NLDEs by applying the exp(−τ(ξ))-expansion method by aid of traveling wave transformations. Furthermore, we explain the physical significance of the obtained solutions of its definite values of the involved parameters with graphic representations in order to know the physical phenomena. Finally, we show that the exp(−τ(ξ))-expansion method is convenient, powerful, straightforward and provide more general solutions and can be helping to examine vast amount of travelling wave solutions to the other different kinds of NLDEs.

Study of simple plane wave generator with an air-metal barrier

Plane wave generators(PWGs) are used to accelerate flyer plates to high velocities with their generated plane waves,which are widely used in the test of dynamic properties of materials.The traditional PWG is composed of two explosives with different detonation velocities.It is difficult to implement the related fabrication processes and control the generated waves due to its complicated structures.A simple plane wave generator is presented in this paper,which is composed of two identical cylindrical high explosive(HE) charges and an air-metal barrier.A theoretical model was established based on two different paths of the propagation of detonation waves,based on which the size of air-metal barrier was calculated for a given charge.The corresponding numerical simulations were also carried out by AUTODYN-2D based on the calculated results,which were used to compare with the theoretical calculations.A detonation wave with a flatness of 0.039 μs within the range of 70-percent diameter of the main charge was obtained through the simulations.

NEW THREE PHASE VFVA SINE WAVE GENERATOR AND PWM HARMONICS ANALYSIS

The new three phase VFVA sine wave generator is presented in this paper. A new sampling holding three phase VFVA sine wave generator’s principle, circuit and experimentation waveform are introduced. The principle of this sampling holding circuit is simple and the realization of har’dware circuit is easy. Here we describe the three phase reference sine wave which is produced by this generator’s circuit and is required by PWM inverter is described in this paper, and also introduced the speed control and harmonir analysis of PWM inverter variable frequency.

Plasma Simulation of Dielectric-lined Multiwave Cerenkov Generators Producing High Power Millimeter Waves

This paper presents the concept of a Dielectric-lined Multiwave Cerenkov Generator producing high power millimeter waves, which has been investigated with a two and onehalf dimensional electromagnetic relativistic Particle-in-Cell (PIC) plasma simulation code. Themodified device can operate in a lower diode-voltage regime with much higher radiation efficiencyand slight downshift of operation frequency. There exist the optima for the permittivity of thedielectric liner and for the magnitude of the guiding magnetic field. The required intensity of theguiding field is reduced by the introduction of the liner. The enhanced propagation of the electronbeam is studied in the presence of the liner.

A New Generator for Tsunami Wave Generation

A middle size experiental wave generator has been implemented is the Ujikawa Open Laboratory, Disaster Prevention Research Institute, Kyoto University. The generator is composed of a pistontype wave maker, a head strage water tank and a current generator to mainly reproduce long waves like tsunami and storm surge. The paper desribes several experimental series to predict the applicability of the generator to model tests. The three operating sysemes are capable to be controlled in one operating sysytem and start time is contorolled separately according with the target tsunami and storm surge profiles. A sharp tsunami profile is reproduced in adjusting the start timing of piston type wave maker and opening gates of head storage tunk. Any type of tsunami waves are reproduced in the generator and it becomes a storong tool to predict the effective of＂resiliency＂ of hardwares.

Time Series-, Time-Frequency- and Spectral Analyses of Sensor Measurements in an Offshore Wave Energy Converter Based on Linear Generator Technology

Inside the second experimental wave energy converter (WEC) launched at the Lysekil research site on the Swedish west coast in March 2009 a number of sensor systems were installed for measuring the mechanical performance of the WEC and its mechanical subsystems. One of the measurement systems was a set-up of 7 laser triangulation sensors for measuring relative displacement of the piston rod mechanical lead-through transmission in the direct drive. Two measurement periods, separated by 2.5 month, are presented in this paper. One measurement is made two weeks after launch and another 3 months after launch. Comparisons and correlations are made between different sensors measuring simultaneously. Noise levels are investigated. Filtering is discussed for further refinement of the laser triangulation sensor signals in order to separate noise from actual physical displacement and vibration. Measurements are presented from the relative displacement of the piston rod mechanical lead-through, from magnetic flux in the air gap, mechanical strain in the WEC structure, translator position and piston rod axial displacement and active AC power. Investigation into the measurements in the time domain with close-ups, in the frequency domain with Fast Fourier transform (FFT) and with time-frequency analysis with short time Fourier transform (STFT) is carried out to map the spectral content in the measurements. End stop impact is clearly visible in the time-frequency analysis. The FFT magnitude spectra are investigated for identifying the cogging bandwidth among other vibrations. Generator cogging, fluctuations in the damping force and in the Lorenz forces in the stator are distinguished and varies depending on translator speed. Vibrations from cogging seem to be present in the early measurement period while not so prominent in the late measurement period. Vibration frequencies due to wear are recognized by comparing with the noise at generator standstill and the vibration sources in the generator. It is concluded that a moving average is a sufficient filter in the time domain for further analysis of the relative displacement of the piston rod mechanical lead-through transmission.

New exact solitary wave solutions to generalized mKdV equation and generalized Zakharov-Kuzentsov equation

In this paper, based on hyperbolic tanh-function method and homogeneous balance method, and auxiliary equation method, some new exact solitary solutions to the generalized mKdV equation and generalized Zakharov-Kuzentsov equation are constructed by the method of auxiliary equation with function transformation with aid of symbolic computation system Mathematica. The method is of important significance in seeking new exact solutions to the evolution equation with arbitrary nonlinear term.

BIFURCATIONS OF TRAVELLING WAVE SOLUTIONS FOR THE GENERALIZED DODD-BULLOUGH-MIKHAILOV EQUATION

In this paper, the generalized Dodd-Bullough-Mikhailov equation is studied. The existence of periodic wave and unbounded wave solutions is proved by using the method of bifurcation theory of dynamical systems. Under different parametric conditions, various sufficient conditions to guarantee the existence of the above solutions are given.Some exact explicit parametric representations of the above travelling solutions are obtained.

EXISTENCE OF SOLITARY WAVES TO A GENERALIZED KADOMTSEV-PETVIASHVILI EQUATION

In this article, we study the existence of nontrivial solitary waves of a gener- alized Kadomtsev-Petviashvili equation via variational methods.

ORBITAL STABILITY OF PERIODIC TRAVELING WAVE SOLUTIONS TO THE GENERALIZED ZAKHAROV EQUATIONS

This paper investigates the orbital stability of periodic traveling wave solutions to the generalized Zakharov equations {iu ＋uxx = uv ＋ ｜u｜^2u, vtt-vxx=（｜u｜^2）xx.First, we prove the existence of a smooth curve of positive traveling wave solutions of dnoidal type with a fixed fundamental period L for the generalized Zakharov equations. Then, by using the classical method proposed by Benjamin, Bona et al., we show that this solution is orbitally stable by perturbations with period L. The results on the orbital stability of periodic traveling wave solutions for the generalized Zakharov equations in this paper can be regarded as a perfect extension of the results of [15, 16, 19].

GENERALIZED WAVE EQUATION FINITE ELEMENT METHOD FOR SOLVING TWO-DIMENSIONAL TIDAL WAVES

The study of tidal circulation has a long history . The numerical simulation of tidal flow has been developed greatly with the development of computer techniques in the past two decades. The generalized wave equation finite-element method is a relatively new numerical model for studying shallow water flow . This method was used to simulate tidal waves of the Gulf of St. Lawrence in Canada . The very good agreement of the numerical results with the field data indicated that the model is an effective and promising numerical method for solving two-dimensional tidal wave problems .

Bifurcation analysis and exact traveling wave solutions for (2+1)-dimensional generalized modified dispersive water wave equation

We investigate (2+1)-dimensional generalized modified dispersive water wave (GMDWW) equation by utilizing the bifurcation theory of dynamical systems. We give the phase portraits and bifurcation analysis of the plane system corresponding to the GMDWW equation. By using the special orbits in the phase portraits, we analyze the existence of the traveling wave solutions. When some parameter takes special values, we obtain abundant exact kink wave solutions, singular wave solutions, periodic wave solutions, periodic singular wave solutions, and solitary wave solutions for the GMDWW equation.

THEORETICAL MEAN WAVE RESISTANCE OF PRECURSOR SOLITON GENERATION IN TWO-LAYER FLOW

A new concept of pseudo mean wave resistance is introduced to find theoretical mean wave resistances of the precursor soliton generation in two-layer how over a localized topography at near-resonance in this paper. The pseudo mean wave resistance of the precursor soliton generation of two-layer how is determined in terms of the AfKdV equation. From the theoretical results it is shown that the theoretical mean wave resistance is equal to the pseudo mean wave resistance times 1/m(1), where m(1) is the coefficient of the fKdV equation. From the regional distribution of the energy of the precursor soliton generation at the resonant points, it is shown that ratios of the theoretical mean wave resistance and regional mean energy to the total mean energy are invariant constants, i.e. <(E)over circle (1)>/(E) over circle : <(E)over circle (2)>/(E) over circle: <(E)over circle (3)>(E) over circle :< D > /(E) over circle = (1/2) : (-1/2) : 1 : 1, in which <(E)over circle 1>,<(E)over circle (2)> and <(E)over circle (3)> are the mean energy of the generating regions of the precursor solitons, of the depression and of the trailing wavetrain at the resonant points respectively, (E) over circle and < D > are the total energy of the system and the theoretical mean wave resistance at the resonant points. A prediction of the theoretical mean wave resistances of two-layer how over the semicircular topography is carried out in terms of the theoretical results of the present paper. The comparison shows that the theoretical mean wave resistance is in good agreement with the numerical calculation.

Travelling solitary wave solutions for the generalized Burgers-Huxley equation with nonlinear terms of any order

In this paper, the travelling wave solutions for the generalized Burgers-Huxley equation with nonlinear terms of any order are studied. By using the first integral method, which is based on the divisor theorem, some exact explicit travelling solitary wave solutions for the above equation are obtained. As a result, some minor errors and some known results in the previousl literature are clarified and improved.

Influence of Generalized （r, q） Distribution Function on Electrostatic Waves

Non-Maxwellian particle distribution functions possessing high energy tail and shoulder in the profile of distribution function considerably change the damping characteristics of the waves. In the present paper Landau damping of electron plasma （Langmuir） waves and ion-acoustic waves in a hot, isotropic, unmagnetized plasma is studied with the generalized （r, q） distribution function. The results show that for the Langmuir oscillations Landau damping becomes severe as the spectral index r or q reduces. However, for the ion-acoustic waves Landau damping is more sensitive to the ion temperature than the spectral indices.

Solitary Wave Solutions of a Generalized Derivative Nonlinear Schrdinger Equation

With the aid of a class of nonlinear ordinary differential equation （ODE） and its various positive solutions, four types of exact solutions of the generalized derivative nonlinear Sehrodinger equation （GDNLSE） have been found out, which are the bell-type solitary wave solution, the algebraic solitary wave solution, the kink-type solitary wave solution and the sinusoidal traveling wave solution, provided that the coefficients of GDNLSE satisfy certain constraint conditions. For more general GDNLSE, the similar results are also given.

Global Well-posedness of the Generalized Long-short Wave Equations

In the present paper, we investigate the well-posedness of the global solutionfor the Cauchy problem of generalized long-short wave equations. Applying Kato＇s methodfor abstract quasi-linear evolution equations and a priori estimates of solution,we get theexistence of globally smooth solution.