Search Results - "WILLATZEN, M."

Parity-Time Synthetic Phononic Media by Christensen, J, Willatzen, M, Velasco, V R, Lu, M-H

“…Classical systems containing cleverly devised combinations of loss and gain elements constitute extremely rich building units that can mimic non-Hermitian…”
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Mechanically Bent Graphene as an Effective Piezoelectric Nanogenerator by Duggen, L, Willatzen, M, Wang, Z. L

“…Recent density functional theory (DFT) calculations have demonstrated the potential of mechanically bent graphene as a piezoelectric energy harvesting…”
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Effective Hamiltonians for phosphorene and silicene by Lew Yan Voon, L C, Lopez-Bezanilla, A, Wang, J, Zhang, Y, Willatzen, M

“…We derived the effective Hamiltonians for silicene and phosphorene with strain, electric field and magnetic field using the method of invariants. Our paper…”
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Acoustic wave propagation and stochastic effects in metamaterial absorbers by Christensen, J., Willatzen, M.

“…We show how stochastic variations of the effective parameters of anisotropic structured metamaterials can lead to increased absorption of sound. For this, we…”
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Extraordinary absorption of sound in porous lamella-crystals by Christensen, J., Romero-García, V., Picó, R., Cebrecos, A., de Abajo, F. J. García, Mortensen, N. A., Willatzen, M., Sánchez-Morcillo, V. J.

“…We present the design of a structured material supporting complete absorption of sound with a broadband response and functional for any direction of incident…”
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Tunable acoustic double negativity metamaterial by Liang, Z., Willatzen, M., Li, J., Christensen, J.

“…Man-made composite materials called “metamaterials” allow for the creation of unusual wave propagation behavior. Acoustic and elastic metamaterials in…”
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Metadevices for the confinement of sound and broadband double-negativity behavior by Christensen, J., Liang, Z., Willatzen, M.

“…We show that the acoustic response of perforated and elastically filled rigid screens can give rise to a broad landscape of tunable devices. We begin…”
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Flow-induced resonance shift in sonic slit array metamaterials by Christensen, J., Willatzen, M.

“…A modal analysis of flow-acoustic wave propagation through slit array metamaterials is presented. It is demonstrated that the transmission-coefficient change…”
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Flow acoustics modelling and implications for ultrasonic flow measurement based on the transit-time method by Willatzen, M.

“…A comparison between three mathematical models frequently used in flow acoustics is presented and discussed with respect to ultrasonic flow-meter performance…”
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Minimal model for spoof acoustoelastic surface states by Christensen, J., Liang, Z., Willatzen, M.

“…Similar to textured perfect electric conductors for electromagnetic waves sustaining artificial or spoof surface plasmons we present an equivalent phenomena…”
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Tunable acoustic double negativity metamaterial by Liang, Z., Willatzen, M., Li, J., Christensen, J.

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Acoustic gain in piezoelectric semiconductors at epsilon -near-zero response by Willatzen, M, Christensen, J

“…We demonstrate strong acoustic gain in electric-field biased piezoelectric semiconductors at frequencies near the plasmon frequency in the terahertz range…”
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EXACT POWER SERIES SOLUTIONS FOR AXISYMMETRIC VIBRATIONS OF CIRCULAR AND ANNULAR MEMBRANES WITH CONTINUOUSLY VARYING DENSITY IN THE GENERAL CASE by WILLATZEN, M.

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SOUND PROPAGATION IN A MOVING FLUID CONFINED BY CYLINDRICAL WALLS—A COMPARISON BETWEEN AN EXACT ANALYSIS AND THE LOCAL-PLANE-WAVE APPROXIMATION by WILLATZEN, M.

“…A discussion of sound propagation in a moving fluid confined by cylindrical walls is presented. Based on the continuity equation and the Euler equation, a…”
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Perturbation theory applied to sound propagation in flowing media confined by a cylindrical waveguide by Willatzen, M

“…First-order perturbation theory is employed to examine sound propagation in flowing media confined by a cylindrical waveguide. The use of perturbation theory…”
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Phase shift and attenuation characteristics of acoustic waves in a flowing gas confined by cylindrical walls by Willatzen, M.

“…Wave propagation in flowing ideal gases confined by cylindrical waveguides is described in the low-frequency range using an iterative Frobenius series…”
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Effective computation of complex-shaped quantum-dot structures by Lassen, B., Willatzen, M.

“…The possibility of growing complex-shaped nanodot structures of various material composition allows optimization of certain physical parameters. In the present…”
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Extension of the Landau theory for hysteretic electric dynamics in ferroelectric ceramics by Wang, L. X., Willatzen, M.

“…In this paper, a macroscopic differential model for the nonlinear dynamics of the electric field in ferroelectric ceramics is developed on the basis of…”
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Ultrasonic flow measurement and wall acoustic impedance effects by Willatzen, M.

“…An examination of the influence of wall acoustic impedance effects on sound propagation in flowing liquids confined by cylindrical walls is presented. Special…”
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Ultrasonic flowmeters: temperature gradients and transducer geometry effects by Willatzen, M.

“…Ultrasonic flowmeter performance is addressed for the case of cylindrically shaped flowmeters employing two reciprocal ultrasonic transducers A and B so as to…”
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