Reduction of wave drift force on a truncated cylinder in a wide frequency band using the defect effects on cloaking phenomenon

2020 ◽  
Vol 203 ◽  
pp. 107241 ◽  
Author(s):  
Zhigang Zhang ◽  
Guanghua He ◽  
Wei Wang ◽  
Shuang Liu ◽  
Zhengke Wang
Keyword(s):  
Frequency Band ◽  
Wide Frequency Band ◽  
Wave Drift ◽  
Drift Force ◽  
Truncated Cylinder

Mean Wave Drift Force on a Barge-Type Floating Wind Turbine With Moonpools

2021 ◽  
Author(s):  
Lei Tan ◽  
Tomoki Ikoma ◽  
Yasuhiro Aida ◽  
Koichi Masuda
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Offshore Wind ◽  
Hydrodynamic Performance ◽  
Vertical Axis Wind Turbine ◽  
Rotating Speed ◽  
Wave Drift ◽  
Floating Offshore Wind Turbines ◽  
Drift Force ◽  
Gyroscopic Effects

Abstract The barge-type foundation with moonpool(s) is a promising type of platform for floating offshore wind turbines, since the moonpool(s) could improve the hydrodynamic performance at particular frequencies and reduce the costs of construction. In this paper, the horizontal mean drift force and yaw drift moment of a barge-type platform with four moonpools are numerically and experimentally investigated. Physical model tests are carried out in a wave tank, where a 2MW vertical-axis wind turbine is modelled in the 1:100 scale. By varying the rotating speed of the turbine and the mass of the blades, the gyroscopic effects due to turbine rotations on the mean drift forces are experimentally examined. The wave diffraction and radiation code WAMIT is used to carry out numerical analysis of wave drift force and moment. The experimental results indicate that the influence of the rotations of a vertical-axis wind turbine on the sway drift force is generally not very significant. The predictions by WAMIT are in reasonable agreement with the measured data. Numerical results demonstrate that the horizontal mean drift force and yaw drift moment at certain frequencies could be reduced by moonpool(s).

scholarly journals Physical Principles of a Piezo Accelerometer Sensitive to a Nearly Constant Signal

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3258 ◽  
Author(s):  
Valery Gupalov ◽  
Alexander Kukaev ◽  
Sergey Shevchenko ◽  
Egor Shalymov ◽  
Vladimir Venediktov
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Frequency Band ◽  
Linear Acceleration ◽  
High Sensitivity ◽  
Element Model ◽  
Wide Frequency Band ◽  
Piezoelectric Accelerometer ◽  
The Finite Element Model ◽  
Physical Principles

The paper considers the construction of a piezoelectric accelerometer capable of measuring constant linear acceleration. A number of designs are proposed that make it possible to achieve high sensitivity with small dimensions and a wide frequency band (from 10−5 Hz). The finite element model of the proposed design was investigated, and its output characteristic and scale factor (36 mV/g) were obtained.

scholarly journals Flexible ultrathin metamaterial absorber for wide frequency band, based on conductive fibers

2018 ◽  
Vol 19 (1) ◽  
pp. 711-717 ◽  
Author(s):  
Young Ju Kim ◽  
Ji Sub Hwang ◽  
Bui Xuan Khuyen ◽  
Bui Son Tung ◽  
Ki Won Kim ◽  
...  
Keyword(s):  
Frequency Band ◽  
Metamaterial Absorber ◽  
Wide Frequency Band ◽  
Conductive Fibers

scholarly journals Nonlinearity Measurements Using Alternating Current

1978 ◽  
Vol 5 (2) ◽  
pp. 91-98 ◽  
Author(s):  
Vladimír Ryšánek ◽  
Carlo Corsi ◽  
Arnaldo d'Amico
Keyword(s):  
Frequency Band ◽  
Measurement Technique ◽  
Alternating Current ◽  
Noise Measurement ◽  
Wide Frequency Band ◽  
Semiconductor Structures ◽  
Different Types ◽  
Homogeneous Structures ◽  
Lock In

The nonlinearity measurement technique described uses an adapted conventional lock-in-amplifier. This technique enables us to measure small nonlinearities over a wide frequency band and is more sensitive than the 1/f noise measurement used to detect non-homogeneous structures in conductors, resistors and semiconductor components. Results illustrating uses of this method are presented for different types of resistor and semiconductor structures.

Wide Frequency Band Characterization

2013 ◽  
pp. 603-638
Author(s):  
D. Flandre ◽  
J.-p. Raskin ◽  
V. Kilchytska
Keyword(s):  
Frequency Band ◽  
Wide Frequency Band

scholarly journals Unidirectional Invisibility Induced by Complex Anti-Parity–Time Symmetric Periodic Lattices

2019 ◽  
Vol 9 (18) ◽  
pp. 3808 ◽  
Author(s):  
Hui Cao ◽  
Dong Zhao ◽  
Ming Fang ◽  
Huang Guo ◽  
Yonghong Hu ◽  
...  
Keyword(s):  
Reflection Coefficient ◽  
Parameter Space ◽  
Frequency Band ◽  
Angular Frequency ◽  
Lateral Shift ◽  
The Other ◽  
Wide Frequency Band ◽  
Highly Sensitive ◽  
Highly Sensitive Sensors

Complex anti-parity-time symmetric periodic lattices, in a wide frequency band, can act as unidirectional invisible media. The reflection from one end is suppressed while it is enhanced from the other. Furthermore, unidirectional laser points (ULPs) which correspond to the poles of reflection from one end, arise in the parameter space composed of the permittivity and angular frequency. The phase of the reflection coefficient changes sharply near the ULPs. Subsequently, large lateral shift which is proportional to the slope of phase could be induced for the reflected beam. The study may find great applications in unidirectional invisibility, unidirectional lasers and highly sensitive sensors.

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