scholarly journals Low Frequency Guided Wave Transmission in Water Pipe Systems

2015 ◽  
Vol 120 ◽  
pp. 1257-1260 ◽  
Author(s):  
S. Wöckel ◽  
U. Steinmann ◽  
H. Arndt
Keyword(s):  
Low Frequency ◽  
Guided Wave ◽  
Wave Transmission ◽  
Water Pipe ◽  
Pipe Systems

Foreshock wave transmission into the magnetosheath and magnetosphere: results from global hybrid-Vlasov simulations

2021 ◽  
Author(s):  
Lucile Turc ◽  
Markus Battarbee ◽  
Urs Ganse ◽  
Andreas Johlander ◽  
Yann Pfau-Kempf ◽  
...  
Keyword(s):  
Solar Wind ◽  
Mach Number ◽  
Cone Angle ◽  
Low Frequency ◽  
Compressional Wave ◽  
Wave Transmission ◽  
Wave Power ◽  
Solar Wind Flow ◽  
Magnetic Pulsations ◽  
Wave Properties

<p>The foreshock, extending upstream of the quasi-parallel shock and populated with shock-reflected particles, is home to intense wave activity in the ultra-low frequency range.<em> </em>The most commonly observed of these waves are the “30 s” waves, fast magnetosonic waves propagating sunward in the plasma rest frame, but carried earthward by the faster solar wind flow. These waves are thought to be the main source of Pc3 magnetic pulsations (10 – 45 s) in the dayside magnetosphere. A handful of case studies with suitable spacecraft conjunctions have allowed simultaneous investigations of the wave properties in different geophysical regions, but the global picture of the wave transmission from the foreshock through the magnetosheath into the magnetosphere is still not known. In this work, we use global simulations performed with the hybrid-Vlasov model Vlasiator to study the Pc3 wave properties in the foreshock, magnetosheath and magnetosphere for different solar wind conditions. We find that in all three regions the wave power peaks at higher frequencies when the interplanetary magnetic field strength is larger, consistent with previous studies. While the transverse wave power decreases with decreasing Alfvén Mach number in the foreshock, the compressional wave power shows little variation. In contrast, in the magnetosheath and the magnetosphere, the compressional wave power decreases with decreasing Mach number. Inside the magnetosphere, the distribution of wave power varies with the IMF cone angle. We discuss the implications of these results for the propagation of foreshock waves across the different geophysical regions, and in particular their transmission through the bow shock.</p>

scholarly journals New Age Advanced Smart Water Pipe Systems Using Textile Reinforced Concrete

2018 ◽  
Vol 21 ◽  
pp. 376-383 ◽  
Author(s):  
Till Quadflieg ◽  
Yiska Goldfeld ◽  
Goezdem Dittel ◽  
Thomas Gries
Keyword(s):  
Reinforced Concrete ◽  
New Age ◽  
Water Pipe ◽  
Textile Reinforced Concrete ◽  
Smart Water ◽  
Pipe Systems

Experimental and Analytical of Ultrasonic Elliptical Vibration Cutting of Micro-pyramid Reflective Mold Based on Guided Wave Transmission

2021 ◽  
Author(s):  
Tao Jiang ◽  
Jintao Yang ◽  
Jun Pi ◽  
Wenyu Luo ◽  
Jun Zhang
Keyword(s):  
High Frequency ◽  
Deflection Angle ◽  
Guided Wave ◽  
Wave Transmission ◽  
Wave Band ◽  
Bending Vibration ◽  
Elliptical Vibration Cutting ◽  
Vibration Cutting ◽  
Elliptical Vibration ◽  
Ultrasonic Elliptical Vibration

Abstract The ultrasonic elliptical vibration cutting (UEVC) technique has been found to be a promising technique for ultraprecision machining of microstructural functional surfaces. However, the current UEVC technique can’t achieve higher frequency ultrasonic cutting due to its rigid orthogonal vibration transmission. To further study the cutting mechanism and removal characteristics in high frequency UEVC of microstructural surface, the UEVC based on flexible guided wave transmission is proposed which can achieve 96.8 kHz. The influence of bending vibration of guided wave band on longitudinal vibration is elaborated with the model of the bending vibration dynamic model of the guided wave. The model of elliptical trajectory deflection of tool tip is established. Based on the theoretical modeling and finite element simulation, the residual height and material removal characteristics of elliptic trajectory with variable deflection angle are simulated and analyzed. The results show that when the deflection angle is between 10° and 70°, the tangential force is small and stable. Finally, the cutting experiments of micro-pyramid reflective mold in guided wave UEVC and conventional cutting (CC) are carried out. Compared with CC, high-frequency UEVC can obtain micro-pyramid elements with average roughness of 5.21 nm, that verifies the applicability of high-frequency UEVC in precision machining of microstructure.

scholarly journals Core–skin debonding detection in honeycomb sandwich structures through guided wave wavefield analysis

2018 ◽  
Vol 30 (9) ◽  
pp. 1306-1317 ◽  
Author(s):  
Lingyu Yu ◽  
Zhenhua Tian ◽  
Xiaopeng Li ◽  
Rui Zhu ◽  
Guoliang Huang
Keyword(s):  
Guided Waves ◽  
Sandwich Structures ◽  
Lamb Waves ◽  
Laser Doppler Vibrometer ◽  
Low Frequency ◽  
Guided Wave ◽  
Honeycomb Sandwich ◽  
Debonding Detection ◽  
The Waves ◽  
Detection And Quantification

Ultrasonic guided waves have proven to be an effective and efficient method for damage detection and quantification in various plate-like structures. In honeycomb sandwich structures, wave propagation and interaction with typical defects such as hidden debonding damage are complicated; hence, the detection of defects using guided waves remains a challenging problem. The work presented in this article investigates the interaction of low-frequency guided waves with core–skin debonding damage in aluminum core honeycomb sandwich structures using finite element simulations. Due to debonding damage, the waves propagating in the debonded skin panel change to fundamental antisymmetric Lamb waves with different wavenumber values. Exploiting this mechanism, experimental inspection using a non-contact laser Doppler vibrometer was performed to acquire wavefield data from pristine and debonded structures. The data were then processed and analyzed with two wavefield data–based imaging approaches, the filter reconstruction imaging and the spatial wavenumber imaging. Both approaches can clearly indicate the presence, location, and size of the debonding in the structures, thus proving to be effective methods for debonding detection and quantification for honeycomb sandwich structures.

scholarly journals Improving accuracy through density correction in guided wave tomography

2016 ◽  
Vol 472 (2186) ◽  
pp. 20150832 ◽  
Author(s):  
P. Huthwaite
Keyword(s):  
Guided Waves ◽  
Low Frequency ◽  
Region Of Interest ◽  
Density Variation ◽  
Pressure Vessels ◽  
Guided Wave ◽  
Wave Tomography ◽  
Wall Loss ◽  
Improving Accuracy ◽  
The Waves

The accurate quantification of wall loss caused by corrosion is critical to the reliable life estimation of pipes and pressure vessels. Traditional thickness gauging by scanning a probe is slow and requires access to all points on the surface; this is impractical in many cases as corrosion often occurs where access is restricted, such as beneath supports where water collects. Guided wave tomography presents a solution to this; by transmitting guided waves through the region of interest and exploiting their dispersive nature, it is possible to build up a map of thickness. While the best results have been seen when using the fundamental modes A0 and S0 at low frequency, the complex scattering of the waves causes errors within the reconstruction. It is demonstrated that these lead to an underestimate in wall loss for A0 but an overestimate for S0. Further analysis showed that this error was related to density variation, which was proportional to thickness. It was demonstrated how this could be corrected for in the reconstructions, in many cases resulting in the near-elimination of the error across a range of defects, and greatly improving the accuracy of life estimates from guided wave tomography.

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