Active/passive technique for the creation of a low‐frequency traveling wave inside a water‐filled tube

1995 ◽  
Vol 98 (5) ◽  
pp. 2941-2941
Author(s):  
James J. Finneran ◽  
Mardi C. Hastings
Keyword(s):  
Traveling Wave ◽  
Low Frequency ◽  
The Creation ◽  
Passive Technique

A Novel Fault-location Method for HVDC Transmission Lines Based on Concentric Relaxation Principle and Wavelet Packet

2020 ◽  
Vol 13 (5) ◽  
pp. 705-716
Author(s):  
Congshan Li ◽  
Ping He ◽  
Feng Wang ◽  
Cunxiang Yang ◽  
Yukun Tao ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Traveling Wave ◽  
Fault Location ◽  
Wave Attenuation ◽  
Wavelet Packet ◽  
Low Frequency ◽  
Evaluation Process ◽  
Location Method ◽  
Hvdc Transmission ◽  
Instantaneous Energy

Background: A novel fault location method of HVDC transmission line based on a concentric relaxation principle is proposed in this paper. Methods: Due to the different position of fault, the instantaneous energy measured from rectifier and inverter are different, and the ratio k between them is the relationship to the fault location d. Through the analysis of amplitude-frequency characteristics, we found that the wave attenuation characteristic of low frequency in the traveling wave is stable, and the amplitude of energy is larger, so we get the instantaneous energy ratio by using the low-frequency data. By using the method of wavelet packet decomposition, the voltage traveling wave signal was decomposed. Results: Finally, calculate the value k. By using the data fitting, the relative function of k and d can be got, that is the fault location function. Conclusion: After an exhaustive evaluation process considering different fault locations, fault resistances, and noise on the unipolar DC transmission system, four-machine two-area AC/DC parallel system, and an actual complex grid, the method presented here showed a very accurate and robust behavior.

scholarly journals Hearing at threshold intensities: by slow mechanical traveling waves or by fast cochlear fluid pressure waves

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Haim Sohmer
Keyword(s):  
Soft Tissue ◽  
Hair Cells ◽  
Traveling Wave ◽  
Basilar Membrane ◽  
Fluid Pressure ◽  
Low Frequency ◽  
Frequency Discrimination ◽  
Outer Hair Cells ◽  
Common Mechanism ◽  
Frequency Stimulation

The three modes of auditory stimulation (air, bone and soft tissue conduction) at threshold intensities are thought to share a common excitation mechanism: the stimuli induce passive displacements of the basilar membrane propagating from the base to the apex (slow mechanical traveling wave), which activate the outer hair cells, producing active displacements, which sum with the passive displacements. However, theoretical analyses and modeling of cochlear mechanics provide indications that the slow mechanical basilar membrane traveling wave may not be able to excite the cochlea at threshold intensities with the frequency discrimination observed. These analyses are complemented by several independent lines of research results supporting the notion that cochlear excitation at threshold may not involve a passive traveling wave, and the fast cochlear fluid pressures may directly activate the outer hair cells: opening of the sealed inner ear in patients undergoing cochlear implantation is not accompanied by threshold elevations to low frequency stimulation which would be expected to result from opening the cochlea, reducing cochlear impedance, altering hydrodynamics. The magnitude of the passive displacements at threshold is negligible. Isolated outer hair cells in fluid display tuned mechanical motility to fluid pressures which likely act on stretch sensitive ion channels in the walls of the cells. Vibrations delivered to soft tissue body sites elicit hearing. Thus, based on theoretical and experimental evidence, the common mechanism eliciting hearing during threshold stimulation by air, bone and soft tissue conduction may involve the fast-cochlear fluid pressures which directly activate the outer hair cells.

A PHASE-PLANE DESCRIPTION OF NONLINEAR TRAVELING WAVES IN BUBBLY LIQUIDS

1999 ◽  
Vol 07 (02) ◽  
pp. 71-82
Author(s):  
A. NADIM ◽  
D. GOLDMAN ◽  
J. J. CARTMELL ◽  
P. E. BARBONE
Keyword(s):  
Equation Of State ◽  
Fixed Points ◽  
Traveling Wave ◽  
Phase Plane ◽  
Volume Fraction ◽  
Low Frequency ◽  
Traveling Wave Solutions ◽  
Bubbly Liquid ◽  
Phase Plane Analysis ◽  
Bubbly Liquids

One-dimensional traveling wave solutions to the fully nonlinear continuity and Euler equations in a bubbly liquid are considered. The elimination of velocity from the two equations leaves a single nonlinear algebraic relation between the pressure and density profiles in the mixture. On assuming the bubbles to have identical size and taking the volume fraction of bubbles in the medium to be small, an equation of state which relates the mixture pressure to the density and its first two material time-derivatives is derived. When this equation of state is linearized and combined with the laws of conservation of mass and momentum, a nonlinear, second-order, ordinary differential equation is obtained for the density as a function of the single traveling wave coordinate. A phase-plane analysis of this equation reveals the existence of two fixed points, one of which is a saddle and the other a node. A single trajectory connects the two fixed points and corresponds to a traveling shock wave solution when the Mach number of the wave, defined as the ratio of traveling wave speed to the low-frequency speed of sound in the bubbly liquid, exceeds unity. The analysis provides a qualitative explanation of the oscillations behind shocks seen in experiments on bubbly liquids.

Joint Use of Traveling Wave Dielectrophoresis and AC-Electroosmosis for Particle Manipulation

2009 ◽  
Author(s):  
Sophie Loire ◽  
Igor Mezic
Keyword(s):  
Fluid Flow ◽  
Traveling Wave ◽  
Rectangular Channel ◽  
Low Frequency ◽  
Joint Effect ◽  
Electrode Arrays ◽  
Ac Electroosmosis ◽  
Phase Signal ◽  
Output Concentration ◽  
Traveling Wave Dielectrophoresis

Joint effect of traveling wave dielectrophoresis and AC electroosmotic fluid flow is used to sort bacteria from other particles and increase the bacteria output concentration in a microfluidic device. The device consists of a thin and long rectangular channel with two interdigitated electrode arrays, one at the bottom and one at the top of the channel, that are used to generate a nonuniform electric field. A four-phase signal at high frequency superposed on a low frequency signal is applied. At the end of the channel, the fluid is collected in two outputs: the bacteria are collected on one side and fluid without bacteria is collected on the other side. We have previously demonstrated a method to optimize cell separation using multiple frequency dielectrophoresis. The device presented here illustrates a novel use of multiple frequencies that permits the combined use of traveling wave dielectrophoresis and AC electroosmotic fluid flow.

Research on High Bandwidth Rogowski Coil for Measuring Lightning Traveling Wave Current on Double Circuit Transmission Line

2014 ◽  
Vol 986-987 ◽  
pp. 1558-1564
Author(s):  
Cheng Ju Yang ◽  
Cheng Wei Zhang ◽  
Geng Bin Zhang ◽  
Pei Ling Chen ◽  
Shi Jun Xie
Keyword(s):  
Transmission Line ◽  
Traveling Wave ◽  
High Frequency ◽  
Power Grid ◽  
Low Frequency ◽  
Rogowski Coil ◽  
The Self ◽  
Equivalent Model ◽  
High Bandwidth ◽  
Frequency Components

Double circuit transmission line is an important part of the power grid, which is vulnerable to lightning and may endanger the security and stability of the power grid. In order to design a sensor which can monitor the lightning traveling wave current on double circuit transmission line, simulations of lightning on the double circuit transmission line were conducted. The simulation result shows that besides high frequency components, the traveling wave contains a lot of low frequency components. Based on the equivalent model and the frequency response of the self-integrated Rogowski coil, it turns out that the widely used self-integrated Rogowski coil is not suitable for this application as the problem of low frequency distortion. In this paper, through theoretical analysis and simulations in Matlab, an improved Rogowski coil with analog integrator is proposed which can correct the low frequency distortion of the self-integrated Rogowski coil. All the simulations, experiments and operating data installed to a double circuit transmission line in China verify the validity of the high bandwidth Rogowski coil.

Inversion for Biot-consistent material properties in subresonant oscillation experiments with fluid-saturated porous rock

Geophysics ◽  
2018 ◽  
Vol 83 (2) ◽  
pp. MR67-MR79 ◽  
Author(s):  
Igor B. Morozov ◽  
Wubing Deng
Keyword(s):  
Traveling Wave ◽  
Seismic Waves ◽  
Rock Specimen ◽  
Low Frequency ◽  
P Wave ◽  
Axial Deformation ◽  
Porous Rock ◽  
Frequency Dependent ◽  
Shear Moduli ◽  
Young’S Moduli

To quantitatively interpret the results of a subresonant laboratory or numerical experiment with wet porous rock, it is insufficient to merely state the measured frequency-dependent viscoelastic moduli and [Formula: see text]-factors. The measured properties are apparent, i.e., dependent on the experimental setup such as the length of the sample and boundary conditions for pore flows. To reveal the true properties of the material, all experimental factors need to be accurately modeled and corrected for. Here, such correction is performed by developing an effective Biot’s model for the material and using it to predict driven oscillations of a cylindrical rock specimen. The model explicitly describes elastic and inertial effects, Biot’s flows, and viscous internal friction within the solid frame and pore fluid, and it approximates squirt and other wave-induced flow effects. The model predicts the dynamic permeability of the specimen, fast (traveling) and slow (diffusive) P- and axial-deformation waves, and it allows accurate modeling of any other ultrasonic or seismic-frequency experiments with the same rock. To illustrate the approach, attenuation and dispersion data from two laboratory and numerical experiments with sandstones are inverted for effective, frequency-dependent moduli of drained sandstone. Several observations from this inversion may be useful for interpreting experiments with porous rock. First, Young’s moduli measured in a short rock cylinder differ from those in a traveling wave within an infinite rod. In particular, for the modeled 8 cm long rock specimen, modulus dispersion and attenuation ([Formula: see text]) are approximately 10 times greater than for a traveling wave. Second, P-wave moduli cannot be derived from the measured Young’s and shear moduli by using conventional (visco)elastic relations. Third, because of wavelengths comparable with the size of the specimen, slow waves contribute to its quasistatic and low-frequency behaviors. Similar observations should also apply to seismic waves traveling through approximately 10 cm layering in the field.

scholarly journals Gravity Field (Low Frequency) of Planet Earth Described by Theory of New Axioms and Laws

2021 ◽  
Vol 4 (3) ◽  
Keyword(s):  
Classical Field Theory ◽  
Low Frequency ◽  
The Body ◽  
Longitudinal Vortex ◽  
The Sun ◽  
Cylindrical Resonator ◽  
Outer Planets ◽  
The Earth ◽  
Planetary Model ◽  
The Creation

The theory of new axioms and laws is published by the same author. It describes nonparametric and nonlinear processes and contains 2 new axioms and 8 new laws. Unlike Classical field theory, it describes longitudinal or transverse non-uniform motions which are accelerating or decelerating. According to the Axiom 1 every unevenly rotation of one vector forms open vortex which can be transverse or longitudinal and accelerating or decelerating. From the planetary model of Rutherford it is known that there is analogy between the electrons and an planets including the planet Earth. By analogy - the electrons and the internal planets are similar Gravitational bodies. According the Law 1 the model of the electron or the Earth represents a decelerating transverse vortex rolled into a plane (2D) and generating in its center accelerating longitudinal Gravity Funnel in (3D), perpendicular to the same plane. Inside- the primary accelerating longitudinal Gravity vectors are with decreasing dimensions and forms the decelerating Magnetic Field as a Back wave passing through the center of Earth. Outside- because of resistance of environment in periphery, is formed Back wave or decelerating Gravity vortex that passes outside the body of Earth. According Axiom 2 the reason for the creation of the electron is the generation by the corresponding proton. By analogythe reason for the creation of internal planets, including the planet Earth is in the generation of a specific vortex inside the corresponding for Earth resonator in the volume of the Sun. It is Low Frequency vortex which is formed in the third cylindrical resonator that corresponds to Earth. According Law 2 the proton or the resonator inside Sun is generated by a decelerating longitudinal vortex with direction from outside to inside which creates an accelerating transverse vortex from inside to outside in the perpendicular plane. As it is strongly accelerated this vortex from inside to outside it shoots itself into space in direction to the Earth. Due to the friction it decelerates and according to the previous Law 1 it winds into as a decelerating transverse vortex generating the body of Earth. According Law 5 decelerating vortex emits decelerating cross vortices from itself to outside. This decelerating vortices in periphery of the Earth emit energy and warm the center of the Earth. That is why the periphery of Earth is cool ,but the center of Earth is hot . According Law 6 the accelerating cross vortex sucks accelerating cross vortices to itself . This accelerating cross vortex at center of the Sun sucks energy and warm from center and emits them to periphery of Sun. That is why the center of Sun is cool but the periphery is extremely accelerated and hot. The described generating mechanism only applies to the inner planets. For the outer planets, the generation algorithm is orthogonal and will be described further

scholarly journals A Novel Pix2Pix Enabled Traveling Wave-Based Fault Location Method

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1633
Author(s):  
Jinxian Zhang ◽  
Qingwu Gong ◽  
Haojie Zhang ◽  
Yubo Wang ◽  
Yilin Wang
Keyword(s):  
Traveling Wave ◽  
Fault Location ◽  
Arrival Time ◽  
Low Frequency ◽  
Recognition Algorithm ◽  
Estimation Accuracy ◽  
Test Results ◽  
Accuracy Test ◽  
Image Translation ◽  
Component Image

This paper proposes a new Image-to-Image Translation (Pix2Pix) enabled deep learning method for traveling wave-based fault location. Unlike the previous methods that require a high sampling frequency of the PMU, the proposed method can translate the scale 1 detail component image provided by the low frequency PMU data to higher frequency ones via the Pix2Pix. This allows us to significantly improve the fault location accuracy. Test results via the YOLO v3 object recognition algorithm show that the images generated by pix2pix can be accurately identified. This enables to improve the estimation accuracy of the arrival time of the traveling wave head, leading to better fault location outcomes.

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