**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**1658

# Search results for: Density wave oscillations

##### 1658 CFD Simulation and Validation of Flap Type Wave-Maker

**Authors:**
Anant Lal,
M. Elangovan

**Abstract:**

**Keywords:**
CFD,
RANSE,
Flap type,
wave-maker,
VOF,
seakeeping,
numerical method.

##### 1657 Energy Density Increasing in the Channel of Super-High Pressure Megaampere Discharge due to Resonance of Different Type Oscillations of the Channel

**Authors:**
Ph. G. Rutberg,
A. V. Budin,
M. E. Pinchuk,
A. A. Bogomaz,
A. G. Leks,
S. Yu. Losev,
andA. A. Pozubenkov

**Abstract:**

Discharges in hydrogen, ignited by wire explosion, with current amplitude up to 1.5 MA were investigated. Channel diameter oscillations were observed on the photostreaks. Voltage and current curves correlated with the photostreaks. At initial gas pressure of 5-35 MPa the oscillation period was proportional to square root of atomic number of the initiating wire material. These oscillations were associated with aligned magnetic and gas-kinetic pressures. At initial pressure of 80-160 MPa acoustic pressure fluctuations on the discharge chamber wall were increased up to 150 MPa and there were the growth of voltage fluctuations on the discharge gap up to 3 kV simultaneously with it. In some experiments it was observed abrupt increase in the oscillation amplitude, which can be caused by the resonance of the acoustic oscillations in discharge chamber volume and the oscillations connected with alignment of the gaskinetic pressure and the magnetic pressure, as far as frequencies of these oscillations are close to each other in accordance with the estimates and the experimental data. Resonance of different type oscillations can produce energy density increasing in the discharge channel. Thus, the appropriate initial conditions in the experiment allow to increase the energy density in the discharge channel

**Keywords:**
High-current gas discharges,
high pressure
hydrogen,
discharge channel oscillations.

##### 1656 Nonlinear Thermal Hydraulic Model to Analyze Parallel Channel Density Wave Instabilities in Natural Circulation Boiling Water Reactor with Asymmetric Power Distribution

**Authors:**
Sachin Kumar,
Vivek Tiwari,
Goutam Dutta

**Abstract:**

**Keywords:**
Asymmetric power distribution,
Density wave oscillations,
In-phase and out-of-phase modes of instabilities,
Natural circulation boiling water reactor

##### 1655 Density Wave Instability of Supercritical Kerosene in Active Cooling Channels of Scramjets

**Authors:**
N. Wang,
Y. Pan,
J. Zhou,
J. Lei,
X. Z. Yang

**Abstract:**

Experimental investigations were made on the instability of supercritical kerosene flowing in active cooling channels. Two approaches were used to control the pressure in the channel. One is the back-pressure valve while the other is the venturi. In both conditions, a kind of low-frequency oscillation of pressure and temperature is observed. And the oscillation periods are calculated. By comparison with the flow time, it is concluded that the instability occurred in active cooling channels is probably one kind of density wave instability. And its period has no relationship with the cooling channel geometry, nor the pressure, but only depends on the flow time of kerosene in active cooling channels. When the mass flow rate, density and pressure drop couple with each other, the density wave instability will appear.

**Keywords:**
scramjets,
active cooling,
instability,
density wave

##### 1654 Influence of Tether Length in the Response Behavior of Square Tension Leg Platform in Regular Waves

**Authors:**
Amr R. El-Gamal,
Ashraf Essa,
Ayman Ismail

**Abstract:**

The tension leg platform (TLP) is a vertically moored structure with excess buoyancy. The TLP is regarded as moored structure in horizontal plan, while inherit stiffness of fixed platform in vertical plane. In this paper, a numerical study using modified Morison equation was carried out in the time domain to investigate the influence of nonlinearities due to hydrodynamic forces and the coupling effect between surge, sway, heave, roll, pitch and yaw degrees of freedom on the dynamic behavior of TLP's. The stiffness of the TLP was derived from a combination of hydrostatic restoring forces and restoring forces due to cables and the nonlinear equations of motion were solved utilizing Newmark’s beta integration scheme. The effect of tethers length and wave characteristics such as wave period and wave height on the response of TLP's was evaluated.

Only uni-directional waves in the surge direction was considered in the analysis. It was found that for short wave periods (i.e. 10 sec.), the surge response consisted of small amplitude oscillations about a displaced position that is significantly dependent on tether length, wave height; whereas for longer wave periods, the surge response showed high amplitude oscillations about that is significantly dependent on tether length.

**Keywords:**
Hydrodynamic wave forces,
tension leg platforms,
tethers length,
wave characteristic.

##### 1653 Two-Photon Ionization of Silver Clusters

**Authors:**
V. Paployan,
K. Madoyan,
A. Melikyan,
H. Minassian

**Abstract:**

In this paper, we calculate the two-photon ionization (TPI) cross-section for pump-probe scheme in Ag neutral cluster. The pump photon energy is assumed to be close to the surface plasmon (SP) energy of cluster in dielectric media. Due to this choice, the pump wave excites collective oscillations of electrons-SP and the probe wave causes ionization of the cluster. Since the interband transition energy in Ag exceeds the SP resonance energy, the main contribution into the TPI comes from the latter. The advantage of Ag clusters as compared to the other noble metals is that the SP resonance in silver cluster is much sharper because of peculiarities of its dielectric function. The calculations are performed by separating the coordinates of electrons corresponding to the collective oscillations and the individual motion that allows taking into account the resonance contribution of excited SP oscillations. It is shown that the ionization cross section increases by two orders of magnitude if the energy of the pump photon matches the surface plasmon energy in the cluster.

**Keywords:**
Resonance enhancement,
silver clusters,
surface
plasmon,
two-photon ionization.

##### 1652 Simulation of Irregular Waves by CFD

**Authors:**
Muniyandy Elangovan

**Abstract:**

**Keywords:**
Numerical wave tank,
irregular wave,
FFT,
wavespectrum

##### 1651 Ocean Wave Kinetic Energy Harvesting System for Automated Sub Sea Sensors

**Authors:**
Amir Anvar,
Dong Yang Li

**Abstract:**

This paper presents an overview of the Ocean wave kinetic energy harvesting system. Energy harvesting is a concept by which energy is captured, stored, and utilized using various sources by employing interfaces, storage devices, and other units. Ocean wave energy harvesting in which the kinetic and potential energy contained in the natural oscillations of Ocean waves are converted into electric power. The kinetic energy harvesting system could be used for a number of areas. The main applications that we have discussed in this paper are to how generate the energy from Ocean wave energy (kinetic energy) to electric energy that is to eliminate the requirement for continual battery replacement.

**Keywords:**
Energy harvesting,
power system,
oceanic,
sensors,
autonomous.

##### 1650 Theoretical Calculation of Electrical and Optical Properties of BaZrO3

**Authors:**
Leyla Safaie Kouchaksaraie

**Abstract:**

**Keywords:**
Density Functional Theory (DFT),
Full PotentialLinearized Augmented Plane Wave (Fp-LAPW),
GeneralizedGradient Approximation (GGA),
Linearized Augmented Plane Wave(LAPW),
Local Density Approximation (LDA)

##### 1649 Effect of Tethers Tension Force in the Behavior of a Tension Leg Platform Subjected to Hydrodynamic Force

**Authors:**
Amr R. El-Gamal,
Ashraf Essa,
Ayman Ismail

**Abstract:**

The tension leg platform (TLP) is one of the compliant structures which are generally used for deep water oil exploration. With respect to the horizontal degrees of freedom, it behaves like a floating structure moored by vertical tethers which are pretension due to the excess buoyancy of the platform, whereas with respect to the vertical degrees of freedom, it is stiff and resembles a fixed structure and is not allowed to float freely. In the current study, a numerical study for square TLP using modified Morison equation was carried out in the time domain with water particle kinematics using Airy’s linear wave theory to investigate the effect of changing the tether tension force on the stiffness matrix of TLP's, the dynamic behavior of TLP's; and on the fatigue stresses in the cables. The effect was investigated for different parameters of the hydrodynamic forces such as wave periods, and wave heights. The numerical study takes into consideration the effect of coupling between various degrees of freedom. The stiffness of the TLP was derived from a combination of hydrostatic restoring forces and restoring forces due to cables. Nonlinear equation was solved using Newmark’s beta integration method. Only uni-directional waves in the surge direction was considered in the analysis. It was found that for short wave periods (i.e. 10 sec.), the surge response consisted of small amplitude oscillations about a displaced position that is significantly dependent on tether tension force, wave height; whereas for longer wave periods, the surge response showed high amplitude oscillations that is significantly dependent on wave height, and that special attention should be given to tethers fatigue because of their high tensile static and dynamic stress.

**Keywords:**
Tethers tension,
tension leg platforms,
hydrodynamic wave forces,
wave characteristic.

##### 1648 Synchronization between the Slow Oscillations in the Human Cardiovascular System

**Authors:**
M. D. Prokhorov,
V. I. Ponomarenko,
A. S. Karavaev,
A. R. Kiselev,
V. I. Gridnev

**Abstract:**

**Keywords:**
Cardiovascular system,
slow oscillating processes,
synchronization.

##### 1647 Radiation Damage as Nonlinear Evolution of Complex System

**Authors:**
Pavlo Selyshchev

**Abstract:**

**Keywords:**
Irradiation,
Primary Defects,
Solids,
Self-oscillation.

##### 1646 Collective Oscillations in a Magnetized Plasma Subjected to a Radiation Field

**Authors:**
Daniel Santos,
Bruno Ribeiro,
Marco Amato,
Antonio Fonseca

**Abstract:**

In this paper we discuss the behaviour of the longitudinal modes of a magnetized non collisional plasma subjected to an external electromagnetic field. We apply a semiclassical formalism, with the electrons being studied in a quantum mechanical viewpoint whereas the electromagnetic field in the classical context. We calculate the dielectric function in order to obtains the modes and found that, unlike the Bernstein modes, the presence of radiation induces oscillations around the cyclotron harmonics, which are smoothed as the energy stored in the radiation field becomes small compared to the thermal energy of the electrons. We analyze the influence of the number of photon involved in the electronic transitions between the Landau levels and how the parameters such as the external fields strength, plasma density and temperature affect the dispersion relation

**Keywords:**
Collective oscillations,
External fields,
Dispersion relation.

##### 1645 Identifications and Monitoring of Power System Dynamics Based on the PMUs and Wavelet Technique

**Authors:**
Samir Avdakovic,
Amir Nuhanovic

**Abstract:**

**Keywords:**
Power system oscillations,
Modal analysis,
Prony,
Wavelet,
PMU,
Wide Area Monitoring System.

##### 1644 Unified Power Flow Controller Placement to Improve Damping of Power Oscillations

**Authors:**
M. Salehi,
A. A. Motie Birjandi,
F. Namdari

**Abstract:**

Weak damping of low frequency oscillations is a frequent phenomenon in electrical power systems. These frequencies can be damped by power system stabilizers. Unified power flow controller (UPFC), as one of the most important FACTS devices, can be applied to increase the damping of power system oscillations and the more effect of this controller on increasing the damping of oscillations depends on its proper placement in power systems. In this paper, a technique based on controllability is proposed to select proper location of UPFC and the best input control signal in order to enhance damping of power oscillations. The effectiveness of the proposed technique is demonstrated in IEEE 9 bus power system.

**Keywords:**
Unified power flow controller (UPFC),
controllability,
small signal analysis,
eigenvalues.

##### 1643 Studies on Pre-Ignition Chamber Dynamics of Solid Rockets with Different Port Geometries

**Authors:**
S. Vivek,
Sharad Sharan,
R. Arvind,
D. V. Praveen,
J. Vigneshwar,
S. Ajith,
V. R. Sanal Kumar

**Abstract:**

**Keywords:**
Pre-Ignition chamber dynamics,
starting transient,
solid rockets,
thrust oscillations in SRMs,
ignition transient.

##### 1642 The Photon-Drag Effect in Cylindrical Quantum Wire with a Parabolic Potential

**Authors:**
Hoang Van Ngoc,
Nguyen Thu Huong,
Nguyen Quang Bau

**Abstract:**

Using the quantum kinetic equation for electrons interacting with acoustic phonon, the density of the constant current associated with the drag of charge carriers in cylindrical quantum wire by a linearly polarized electromagnetic wave, a DC electric field and a laser radiation field is calculated. The density of the constant current is studied as a function of the frequency of electromagnetic wave, as well as the frequency of laser field and the basic elements of quantum wire with a parabolic potential. The analytic expression of the constant current density is numerically evaluated and plotted for a specific quantum wires GaAs/AlGaAs to show the dependence of the constant current density on above parameters. All these results of quantum wire compared with bulk semiconductors and superlattices to show the difference.

**Keywords:**
Photon-drag effect,
constant current density,
quantum wire,
parabolic potential.

##### 1641 Synchronization of 0.1 Hz Oscillations in Heart Rate and Blood Pressure: Application to Treatment of Myocardial Infarction Patients

**Authors:**
M. D. Prokhorov,
A. R. Kiselev,
A. S. Karavaev,
O. M. Posnenkova,
V. I. Gridnev,
V. I. Ponomarenko

**Abstract:**

Synchronization between 0.1 Hz oscillations in heart rate and blood pressure is studied and its change during vertical tilt is evaluated in 37 myocardial infarction patients. Two groups of patients are identified with decreased and increased, respectively, synchronization of the studied oscillations as a response to a tilt test. It is shown that assessment of synchronization of 0.1 Hz oscillations as a response to vertical tilt can be used as a guideline for selecting optimal dose of beta-blocker treatment in post-myocardial infarction patients.

**Keywords:**
Cardiovascular system,
heart rate variability,
synchronization.

##### 1640 Simulation of Acoustic Properties of Borate and Tellurite Glasses

**Authors:**
M. S. Gaafar,
S. Y. Marzouk,
I. S. Mahmoud,
S. Al-Zobaidi

**Abstract:**

**Keywords:**
Glasses,
ultrasonic wave velocities,
elastic moduli,
Makishima and Mackenzie model.

##### 1639 Design of Power System Stabilizer with Neuro-Fuzzy UPFC Controller

**Authors:**
U. Ramesh Babu,
V. Vijay Kumar Reddy,
S. Tara Kalyani

**Abstract:**

**Keywords:**
Power System,
UPFC,
(ANFIS) Adaptive Neuro
Fuzzy Inference System,
transient,
Low frequency oscillations.

##### 1638 A Comparative Study on Optimized Bias Current Density Performance of Cubic ZnB-GaN with Hexagonal 4H-SiC Based Impatts

**Authors:**
Arnab Majumdar,
Srimani Sen

**Abstract:**

In this paper, a vivid simulated study has been made on 35 GHz Ka-band window frequency in order to judge and compare the DC and high frequency properties of cubic ZnB-GaN with the existing hexagonal 4H-SiC. A flat profile p^{+}pnn^{+} DDR structure of impatt is chosen and is optimized at a particular bias current density with respect to efficiency and output power taking into consideration the effect of mobile space charge also. The simulated results obtained reveals the strong potentiality of impatts based on both cubic ZnB-GaN and hexagonal 4H-SiC. The DC-to-millimeter wave conversion efficiency for cubic ZnB-GaN impatt obtained is 50% with an estimated output power of 2.83 W at an optimized bias current density of 2.5×10^{8} A/m^{2}. The conversion efficiency and estimated output power in case of hexagonal 4H-SiC impatt obtained is 22.34% and 40 W respectively at an optimum bias current density of 0.06×10^{8} A/m^{2}.

**Keywords:**
Cubic ZnB-GaN,
hexagonal 4H-SiC,
Double drift impatt diode,
millimeter wave,
optimized bias current density,
wide band gap semiconductor.

##### 1637 Pressure Induced Isenthalpic Oscillations with Condensation and Evaporation in Saturated Two-Phase Fluids

**Authors:**
Joel V. Madison,
Hans E. Kimmel

**Abstract:**

**Keywords:**
condensation,
evaporation,
non-linear oscillations,
pressure induced,
two-phase flow

##### 1636 Research of Amplitude-Frequency Characteristics of Nonlinear Oscillations of the Interface of Two-Layered Liquid

**Authors:**
Win Ko Ko,
A. N. Temnov

**Abstract:**

The problem of nonlinear oscillations of a two-layer liquid completely filling a limited volume is considered. Using two basic asymmetric harmonics excited in two mutually perpendicular planes, ordinary differential equations of nonlinear oscillations of the interface of a two-layer liquid are investigated. In this paper, hydrodynamic coefficients of linear and nonlinear problems in integral relations were determined. As a result, the instability regions of forced oscillations of a two-layered liquid in a cylindrical tank occurring in the plane of action of the disturbing force are constructed, as well as the dynamic instability regions of the parametric resonance for different ratios of densities of the upper and lower liquids depending on the amplitudes of liquids from the excitations frequencies. Steady-state regimes of fluid motion were found in the regions of dynamic instability of the initial oscillation form. The Bubnov-Galerkin method is used to construct instability regions for approximate solution of nonlinear differential equations.

**Keywords:**
Hydrodynamic coefficients,
instability region,
nonlinear oscillations,
resonance frequency,
two-layered liquid.

##### 1635 The Light-Effect in Cylindrical Quantum Wire with an Infinite Potential for the Case of Electrons: Optical Phonon Scattering

**Authors:**
Hoang Van Ngoc,
Nguyen Vu Nhan,
Nguyen Quang Bau

**Abstract:**

The light-effect in cylindrical quantum wire with an infinite potential for the case of electrons, optical phonon scattering, is studied based on the quantum kinetic equation. The density of the direct current in a cylindrical quantum wire by a linearly polarized electromagnetic wave, a DC electric field, and an intense laser field is calculated. Analytic expressions for the density of the direct current are studied as a function of the frequency of the laser radiation field, the frequency of the linearly polarized electromagnetic wave, the temperature of system, and the size of quantum wire. The density of the direct current in cylindrical quantum wire with an infinite potential for the case of electrons – optical phonon scattering is nonlinearly dependent on the frequency of the linearly polarized electromagnetic wave. The analytic expressions are numerically evaluated and plotted for a specific quantum wire, GaAs/GaAsAl.

**Keywords:**
The light-effect,
cylindrical quantum wire with an infinite potential,
the density of the direct current,
electrons - optical phonon scattering.

##### 1634 Effects of Synthetic Jet in Suppressing Cavity Oscillations

**Abstract:**

**Keywords:**
Cavity oscillation,
Large Eddy Simulation,
Synthetic
Jet,
Flow Control,
Turbulence

##### 1633 A Study of the Relation of Wave Height and Erosion at Bangkhuntien Shoreline, Thailand

**Authors:**
Prasertsak Ekphisutsuntorn,
Prungchan Wongwises,
Chaiyuth Chinnarasri,
Usa Humphries,
Suphat Vongvisessomjai

**Abstract:**

In this paper, the significant wave height at the Upper Gulf of Thailand and the changing of wave height at Bangkhuntien shoreline were simulated by using the Simulating WAves Nearshore Model (SWAN) version 40.51. The simulated results indicated that the significant wave height by SWAN model corresponded with the observed data. The results showed that the maximum significant wave height at the Bangkhuntien shoreline were 1.06-2.05 m. and the average significant wave height at the Bangkhuntien shoreline were 0.30-0.47 m. The significant wave height can be used to calculate the erosion through the Bangkhuntien shoreline. The erosion rates at the Bangkhuntien shoreline were prepared by using the aerial photo and they were about 1.80 m/yr. from 1980- 1986, 4.75 m/yr from 1987-1993, 15.28 m/yr from 1994-1996 and 10.03 m/yr from 1997-2002. The relation between the wave energy and the erosion were in good agreement. Therefore, the significant wave height was one of the major factors of the erosion at the Bangkhuntien shoreline.

**Keywords:**
significant wave height,
erosion,
SWAN,
relation,
Bangkhuntien shoreline

##### 1632 Noise Performance of Millimeter-wave Silicon Based Mixed Tunneling Avalanche Transit Time(MITATT) Diode

**Authors:**
Aritra Acharyya,
Moumita Mukherjee,
J. P. Banerjee

**Abstract:**

**Keywords:**
Noise Analysis,
Silicon MITATT,
Admittancecharacteristics,
Noise spectral density.

##### 1631 Wave Vortex Parameters as an Indicator of Breaking Intensity

**Authors:**
B. Robertson,
K. Hall

**Abstract:**

The study of the geometric shape of the plunging wave enclosed vortices as a possible indicator for the breaking intensity of ocean waves has been ongoing for almost 50 years with limited success. This paper investigates the validity of using the vortex ratio and vortex angle as methods of predicting breaking intensity. Previously published works on vortex parameters, based on regular wave flume results or solitary wave theory, present contradictory results and conclusions. Through the first complete analysis of field collected irregular wave breaking vortex parameters it is illustrated that the vortex ratio and vortex angle cannot be accurately predicted using standard breaking wave characteristics and hence are not suggested as a possible indicator for breaking intensity.

**Keywords:**
Breaking Wave Measurement,
Wave Vortex Parameters,
Analytical Techniques,
Ocean Remote Sensing.

##### 1630 Application of Method of Symmetries at a Calculation and Planning of Circular Plate with Variable Thickness

**Authors:**
Kirill Trapezon,
Alexandr Trapezon

**Abstract:**

A problem is formulated for the natural oscillations of a circular plate of linearly variable thickness on the basis of the symmetry method. The equations of natural frequencies and forms for a plate are obtained, providing that it is rigidly fixed along the inner contour. The first three eigenfrequencies are calculated, and the eigenmodes of the oscillations of the acoustic element are constructed. An algorithm for applying the symmetry method and the factorization method for solving problems in the theory of oscillations for plates of variable thickness is shown. The effectiveness of the approach is demonstrated on the basis of comparison of known results and those obtained in the article. It is shown that the results are more accurate and reliable.

**Keywords:**
Vibrations,
plate,
thickness,
symmetry,
factorization,
approximation.

##### 1629 Pilot Induced Oscillations Adaptive Suppression in Fly-By-Wire Systems

**Authors:**
Herlandson C. Moura,
Jorge H. Bidinotto,
Eduardo M. Belo

**Abstract:**

The present work proposes the development of an adaptive control system which enables the suppression of Pilot Induced Oscillations (PIO) in Digital Fly-By-Wire (DFBW) aircrafts. The proposed system consists of a Modified Model Reference Adaptive Control (M-MRAC) integrated with the Gain Scheduling technique. The PIO oscillations are detected using a Real Time Oscillation Verifier (ROVER) algorithm, which then enables the system to switch between two reference models; one in PIO condition, with low proneness to the phenomenon and another one in normal condition, with high (or medium) proneness. The reference models are defined in a closed loop condition using the Linear Quadratic Regulator (LQR) control methodology for Multiple-Input-Multiple-Output (MIMO) systems. The implemented algorithms are simulated in software implementations with state space models and commercial flight simulators as the controlled elements and with pilot dynamics models. A sequence of pitch angles is considered as the reference signal, named as Synthetic Task (Syntask), which must be tracked by the pilot models. The initial outcomes show that the proposed system can detect and suppress (or mitigate) the PIO oscillations in real time before it reaches high amplitudes.

**Keywords:**
Adaptive control,
digital fly-by-wire,
oscillations suppression,
PIO.