A Model for the Mechanisms of Charge Transport Controlled by the Short-range Mobility

2013 ◽  
Vol 1556 ◽  
Author(s):  
Valerio Dallacasa
Keyword(s):  
Charge Transport ◽  
Working Conditions ◽  
Short Range ◽  
Low Frequency ◽  
Harmonic Oscillation ◽  
Zno Nanowires ◽  
Sound Waves ◽  
Transport Parameters ◽  
Oscillation Modes ◽  
Piezoelectric Fields

ABSTRACTStudies of carrier motion in a variety of nanostructures have indicated that a modified Drude model can be applied, by considering carrier bound motion from backscattering mechanisms and localized oscillator modes. Based on the results of these studies a model of damped harmonic oscillation modes is suggested to evaluate transport parameters in piezotronic devices. Here, the case of a system subject to static and low frequency piezoelectric fields is considered which corresponds to typical working conditions of nanogenerators and, as a working example, the response of ZnO nanowires excited by sound waves is analyzed.

Chaos in positive ion–negative ion magnetized plasmas

2020 ◽  
Vol 86 (6) ◽  
Author(s):  
Samiran Ghosh ◽  
Biplab Maity ◽  
Swarup Poria
Keyword(s):  
Nonlinear Wave ◽  
Low Frequency ◽  
Negative Ions ◽  
Dynamical Behaviour ◽  
Negative Ion ◽  
Sound Waves ◽  
Weakly Nonlinear ◽  
Positive Ions ◽  
Experimental Parameters ◽  
Map Analysis

The dynamical behaviour of weakly nonlinear, low-frequency sound waves are investigated in a plasma composed of only positive and negative ions incorporating the effects of a weak external uniform magnetic field. In the plasma model the mass (temperature) of the positive ions is smaller (larger) than that of the negative ions. The dynamics of the nonlinear wave is shown to be governed by a novel nonlinear equation. The stationary plane wave (analytical and numerical) nonlinear analysis on the basis of experimental parameters reveals that the nonlinear wave does have quasi-periodic and chaotic solutions. The Poincarè return map analysis confirms these observed complex structures.

scholarly journals Spiral Sound Wave Transducer Based on the Longitudinal Vibration

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3674 ◽  
Author(s):  
Wei Lu ◽  
Yu Lan ◽  
Rongzhen Guo ◽  
Qicheng Zhang ◽  
Shichang Li ◽  
...  
Keyword(s):  
Sound Wave ◽  
Longitudinal Vibration ◽  
Three Dimensional ◽  
Low Frequency ◽  
Sound Field ◽  
Field Measurements ◽  
Sound Waves ◽  
Underwater Sound ◽  
Three Dimensional Finite Element ◽  
Wave Transducer

A spiral sound wave transducer comprised of longitudinal vibrating elements has been proposed. This transducer was made from eight uniform radial distributed longitudinal vibrating elements, which could effectively generate low frequency underwater acoustic spiral waves. We discuss the production theory of spiral sound waves, which could be synthesized by two orthogonal acoustic dipoles with a phase difference of 90 degrees. The excitation voltage distribution of the transducer for emitting a spiral sound wave and the measurement method for the transducer is given. Three-dimensional finite element modeling (FEM)of the transducer was established for simulating the vibration modes and the acoustic characteristics of the transducers. Further, we fabricated a spiral sound wave transducer based on our design and simulations. It was found that the resonance frequency of the transducer was 10.8 kHz and that the transmitting voltage resonance was 140.5 dB. The underwater sound field measurements demonstrate that our designed transducer based on the longitudinal elements could successfully generate spiral sound waves.

scholarly journals A New Asymptotic Treatment of g-modes of a Star

1995 ◽  
Vol 155 ◽  
pp. 285-286
Author(s):  
P. Smeyers ◽  
T. Van Hoolst ◽  
I. De Boeck ◽  
L. Decock
Keyword(s):  
Singular Perturbation ◽  
Fourth Order ◽  
Asymptotic Expansions ◽  
Equilibrium Model ◽  
Asymptotic Representation ◽  
Radial Displacement ◽  
Low Frequency ◽  
Order System ◽  
Oscillation Modes ◽  
Perturbation Problems

An asymptotic representation of low-frequency, linear, isentropic g-modes of a star is developed without the usual neglect of the Eulerian perturbation of the gravitational potential. Our asymptotic representation is based on the use of asymptotic expansions adequate for solutions of singular perturbation problems (see, e.g., Kevorkian & Cole 1981).Linear, isentropic oscillation modes with frequency different from zero are governed by a fourth-order system of linear, homogeneous differential equations in the radial parts of the radial displacement ξ(r) and the divergence α(r). These equations take the formThe symbols have their usual meaning. N2 is the square of the frequency of Brunt-Väisälä. The functions K1 (r), K2 (r), K3 (r), K4 (r), depend on the equilibrium model, e.g.,We introduce the small expansion parameterand assume, for the sake of simplification, N2 to be positive everywhere in the star so that the star is everywhere convectively stable.

Trans*formative Thinking Through Sound: Artistic Research in Gender and Sound Beyond the Human

2021 ◽  
Vol 4 (1) ◽  
pp. 335-346
Author(s):  
Luca Soudant
Keyword(s):  
Queer Theory ◽  
Low Frequency ◽  
Sound Studies ◽  
Sound Design ◽  
Research Practice ◽  
Sound Waves ◽  
Frequency Sound ◽  
Gender Power ◽  
The Relationship ◽  
Artistic Research

Abstract This article reflects on an ongoing artistic research practice that deals with sound, gender, power, spatiality, and human–nonhuman entanglement. Sparked by a sound design for a less crunchy “lady-friendly” crisp, the research inquires the relationship between gender and sound at human–nonhuman encounter through making and thinking. Drawing on queer theory, sound studies, and posthumanism, it aims to transcend essentialist, vision-focused, and anthropocentric conceptualisations of gender and, as an insight gained from working with low-frequency sound waves, it reflects on sound as material-philosophically demonstrating human–nonhuman interconnectedness. The latter, as this article proposes, may encourage us to horizontalise hierarchies between the human and nonhuman. Finally, this text situates sonic thinking as a mode of trans*formative thinking: a process-oriented philosophy that aims to embrace the messy, queer ways of human–nonhuman relationality, which characterises a vibrant space from which this artistic research will further develop.

EFFECTS OF BOUNDARY-LAYER THICKNESS ON FLOW OSCILLATIONS INSIDE OPEN CAVITIES AT SUPERSONIC SPEEDS

2010 ◽  
Vol 24 (04n05) ◽  
pp. 487-493
Author(s):  
DANG-GUO YANG ◽  
ZHAO-LIN FAN ◽  
JIANG-QIANG LI ◽  
DAN YAO
Keyword(s):  
Boundary Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Low Frequency ◽  
Cavity Depth ◽  
Oscillation Modes ◽  
Open Cavities ◽  
Flow Oscillations ◽  
Unsteady Characteristics ◽  
Modified Equation

An experiment was conducted in a wind-tunnel to study the internal acoustic field and flow oscillations inside rectangular-box cavities. The length-to-depth ratio of the cavities was 8. The data presented herein was obtained over a Mach number of 1.5 at a Reynolds number of 2.26×107 per meter with different boundary-layer thicknesses of approximately 24 mm and 5.5 mm. The experimental angle of attack, yawing and rolling angles were 0°. The rules were revealed as governing the effects of boundary-layer thickness on flow oscillations and unsteady characteristics by comparing the experimental results with flow oscillation modes predicated by Rossiter's and Heller's modified equation. The results indicate that a decrease in the ratio of boundary-layer thickness to cavity-depth (δ/D) induces flow oscillations amplification, peak oscillation frequency splitting and shifting phenomena of open cavity tones in the low-frequency region.

New low-frequency waves and negative mass instability in dusty plasmas

2010 ◽  
Vol 76 (6) ◽  
pp. 929-937
Author(s):  
D. P. RESENDES ◽  
R. BINGHAM ◽  
S. MOTA ◽  
V. N. TSYTOVICH
Keyword(s):  
Electron Temperature ◽  
Free Path ◽  
Collision Frequency ◽  
Low Frequency ◽  
Mean Free Path ◽  
Sound Waves ◽  
Ion Temperature ◽  
Plasma Particle ◽  
Charging Mode ◽  
Dust Charging

AbstractLow-frequency dusty plasma waves with frequencies much smaller than the frequency of charging collisions of plasma particles with dust particles are considered taking into account elastic and charging collisions of plasma particles with dust and neutrals. The usual dust sound waves with an upper frequency equal to the dust plasma frequency are found to be present only for wavelengths much smaller than the plasma particle effective mean free path due to the effective collision frequency. The effectice collision frequency is found to be inversely proportional to the square root of the product of the charging frequency and the frequency of particle momentum losses, involving processes due to elastic plasma particle–dust collisions and collisions with neutrals. It is shown that when the wavelength of the wave is much larger than the mean free path for effective collisions, the properties of the waves are different from those considered previously. A negative mass instability is found in this domain of frequencies when the effective mean free path of ions is larger than the effective mean free path of electrons. In the absence of neutrals, this appears to be possible only if the temperature of ions exceeds the electron temperature. This can occur in laboratory experiments and space plasmas but not in plasma-etching experiments. In the absence of instability, a new dust oscillation, a dust charging mode, is found, whose frequency is almost constant over a certain range of wave numbers. It is inversely proportional to the dust mass and charging frequency of the dust. A new dust electron sound wave is found for frequencies less than the frequency of the dust charging mode. The velocity of the dust electron sound wave is determined by the electron temperature but not the ion temperature, as for the usual dust sound waves, with the electron temperature substantially exceeding the ion temperature.

Sign in / Sign up

Export Citation Format

Share Document