ESTIMATION FORMULAS FOR WAVE REFLECTION COEFFICIENT OF LONG-PERIOD WAVE ABSORBING MOUND STRUCTURES

2019 ◽  
Vol 75 (2) ◽  
pp. I_787-I_792
Author(s):  
Jun MITSUI ◽  
Iwao HASEGAWA ◽  
Masashi TANAKA ◽  
Akira MATSUMOTO
Keyword(s):  
Reflection Coefficient ◽  
Wave Reflection ◽  
Long Period ◽  
Period Wave

scholarly journals Consideration on Reduction of Long Period Wave Reflection

1998 ◽  
Vol 14 ◽  
pp. 287-292
Author(s):  
Takashi Tomita ◽  
Tetsuya Hiraishi
Keyword(s):  
Wave Reflection ◽  
Long Period ◽  
Period Wave

scholarly journals Wave Force Characteristics of Large-Sized Offshore Wind Support Structures to Sea Levels and Wave Conditions

2019 ◽  
Vol 9 (9) ◽  
pp. 1855
Author(s):  
Youn-Ju Jeong ◽  
Min-Su Park ◽  
Jeongsoo Kim ◽  
Sung-Hoon Song
Keyword(s):  
Shallow Water ◽  
Wave Height ◽  
Wave Force ◽  
Diffraction Effect ◽  
Support Structures ◽  
Sea Levels ◽  
Irregular Wave ◽  
Long Period ◽  
Short Period ◽  
Period Wave

This paper presents the results of wave force tests conducted on three types of offshore support structures considering eight waves and three sea levels to investigate the corresponding wave forces. As a result of this study, it is found that the occurrence of shoaling in shallow water induces a significant increase of the wave force. Most of the test models at the shallow water undergo a nonlinear increase of the wave force with higher wave height increasing. In addition, the larger the diameter of the support structure within the range of this study, the larger the diffraction effect is, and the increase in wave force due to shoaling is suppressed. Under an irregular wave at the shallow water, the wave force to the long-period wave tends to be slightly higher than that of the short period wave since the higher wave height component included in the irregular wave has an influence on the shoaling. In addition, it is found that the influence of shoaling under irregular wave becomes more apparent in the long period.

scholarly journals The application to real data of a technique for measuring the plane‐wave reflection coefficient of the ocean bottom

1982 ◽  
Vol 72 (S1) ◽  
pp. S97-S97
Author(s):  
George V. Frisk ◽  
Douglas R. Mook ◽  
James A. Doutt ◽  
Earl E. Hays ◽  
Alan V. Oppenheim
Keyword(s):  
Reflection Coefficient ◽  
Plane Wave ◽  
Wave Reflection ◽  
Real Data ◽  
Ocean Bottom

WAVE DISSIPATING CHARACTERISTICS OF LONG-PERIOD WAVE ABSORBING MOUNDS WITH WATER CHAMBER

2021 ◽  
Vol 77 (2) ◽  
pp. I_43-I_48
Author(s):  
Jun MITSUI ◽  
Mikihisa WATANABE ◽  
Shin-ichi KUBOTA ◽  
Akira MATSUMOTO
Keyword(s):  
Long Period ◽  
Water Chamber ◽  
Period Wave

scholarly journals Placental vascular abnormalities in the mouse alter umbilical artery wave reflections

2019 ◽  
Vol 316 (3) ◽  
pp. H664-H672 ◽  
Author(s):  
Lindsay S. Cahill ◽  
Yu-Qing Zhou ◽  
Johnathan Hoggarth ◽  
Lisa X. Yu ◽  
Anum Rahman ◽  
...  
Keyword(s):  
Antiretroviral Therapy ◽  
Reflection Coefficient ◽  
Umbilical Artery ◽  
Wave Reflection ◽  
Pressure Waves ◽  
Combination Antiretroviral Therapy ◽  
Wave Reflections ◽  
Vascular Architecture ◽  
Vascular Abnormalities ◽  
The Relationship

Current methods to detect placental vascular pathologies that monitor Doppler ultrasound changes in umbilical artery (UA) pulsatility have only moderate diagnostic utility, particularly in late gestation. In fetal mice, we recently demonstrated that reflected pressure waves propagate counter to the direction of flow in the UA and proposed the measurement of these reflections as a means to detect abnormalities in the placental circulation. In the present study, we used this approach in combination with microcomputed tomography to investigate the relationship between altered placental vascular architecture and changes in UA wave reflection metrics. Fetuses were assessed at embryonic day (E) 15.5 and E17.5 in control C57BL6/J mice and dams treated with combination antiretroviral therapy (cART), a known model of fetal growth restriction. Whereas the reflection coefficient was not different between groups at E15.5, it was 27% higher at E17.5 in cART-treated mice compared with control mice. This increase in reflection coefficient corresponded to a 36% increase in the total number of vessel segments, a measure of overall architectural complexity. Interestingly, there was no difference in UA pulsatility index between groups, suggesting that the wave reflections convey information about vascular architecture that is not captured by conventional ultrasound metrics. The wave reflection parameters were found to be associated with the morphology of the fetoplacental arterial tree, with the area ratio between the UA and first branch points correlating with the reflection coefficient. This study highlights the potential for wave reflection to aid in the noninvasive clinical assessment of placental vascular pathology. NEW & NOTEWORTHY We used a novel ultrasound methodology based on detecting pulse pressure waves that propagate along the umbilical artery to investigate the relationship between changes in wave reflection metrics and altered placental vascular architecture visualized by microcomputed tomography. Using pregnant mice treated with combination antiretroviral therapy, a model of fetal growth restriction, we demonstrated that reflections in the umbilical artery are sensitive to placental vascular abnormalities and associated with the geometry of the fetoplacental tree.

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