WAVE TRANSMISSION THROUGH A DOUBLE-ROW PILE BREAKWATER

Several previous investigators have conducted experiments leading to expressions for predicting the transformation of waves passing through closely-spaced pile or large cylinder breakwaters. The present study extends the earlier experiments which used a single row of piles instead of a double row of piles forming a breakwater. The experiments using the double-pile breakwater were performed in the same facility as the experiments conducted on a single-pile breakwater and employed the same method of analysis for a more meaningful comparison. The experiments consisted of allowing waves to pass through a pile array and measuring the incident and transmitted wave heights. The variables were: depth, period, diameter, monochromatic and random waves. The experimental matrix was three water depths, four wave periods, two pile diameters, two gap dimensions between piles and four random wave spectra: Darbyshire, I.T.T.C., Pierson- Moskowitz and JONSWAP, two pile diameters and two gap dimensions between piles. The two-row breakwater had less wave transmission than the single-row breakwater, as expected. For a gap to a pile diameter ratio, or b/D = 0.2 (where b = gap spacing, D — pile diameter), the wave transmission was reduced by 15 percent, as compared with a single-row breakwater; for a gap ratio of b/D - 0.1, the wave transmission was reduced by 5 to 10 percent.

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COMPARISONS OF NUMERICAL RANDOM WAVE SIMULATORS

Coastal Engineering Proceedings ◽

10.9753/icce.v21.70 ◽

1988 ◽

Vol 1 (21) ◽

pp. 70 ◽

Cited By ~ 1

Author(s):

Josep R. Medina ◽

Carlos R. Sanchez-Carratala

Keyword(s):

Random Wave ◽

Random Numbers ◽

Random Waves ◽

Spectral Parameters ◽

Mean Values ◽

Simulation Techniques ◽

Target Spectrum ◽

Wave Superposition ◽

Wave Heights ◽

Fft Algorithms

A review of unidimensional numerical random sea simulators is provided, centering the attention on the measurement of distortions introduced by the different simulation techniques. Simulators by wave superposition are analyzed, with the conclusion being that they generate significant distortions on the realizations when the number of simulated points are larger than two times the number of wave components. Composed simulators are proposed for the purpose of generating long non-periodic realizations using FFT algorithms. In order to qualify simulators, a justification, based on physical properties of random waves, is given to use mn> m1» Qp and mo as the best spectral parameters to characterize processes. Mean values and variabilities of wave heights and periods are controlled by these parameters. A new robust technique is developed to estimate the parameters of an AR(p) model corresponding to a given target spectrum, S 77 ( f ). MA(q) and ARMA(p,q) approximations are studied. The source of pseudo-random numbers to generate the input white noise has a critical impact on the statistical properties of the output.

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Evaluation of Micropiles With Different Configuration Settings for Landslide Stabilization Based on Large-Scale Experimental Testing

Frontiers in Earth Science ◽

10.3389/feart.2021.693639 ◽

2021 ◽

Vol 9 ◽

Author(s):

Xueling Liu ◽

Jinkai Yan ◽

Bin Tong ◽

Lei Liu

Keyword(s):

Large Scale ◽

Experimental Testing ◽

Bending Moment ◽

Scale Model ◽

Sliding Surface ◽

Double Row ◽

Single Row ◽

Pile Diameter ◽

Negative Bending ◽

Landslide Stabilization

In this study, a large-scale model test was performed to investigate the effect of the single-row and double-row micropiles on the landside stabilization. For two different testing configuration settings, the bending moment along the micropiles, failure mode, and force condition were captured and compared. It is found that the landslide thrust on piles was distributed in a triangular shape. The piles in the front row carried greater pressure than the piles in the rear row. The resistance of the sliding body behind the pile was distributed in a parabolic shape, and mainly concentrated on the middle of the pile. The piles were destroyed due to the combined shearing and bending impact applied near the slipping surface. The boundary of the failure zone was from the position of two times the pile diameter under the slipping surface to the position of two and a half times the pile diameter above the slipping surface. Under the action of the landslide, each row of piles deformed at the same time. The capability of landslide stabilization for double-row piles was better than that of a single-row pile. The sections of the pile above slide surface were mainly subjected to negative bending moments and were distributed mainly within the pile length range of one-third of the anti-sliding section above the sliding surface. The pile body of the embedded section located in the range of ten times the pile diameter below the sliding surface was subjected to a positive bending moment.

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DIFFRACTION DIAGRAMS FOR DIRECTIONAL RANDOM WAVES

Coastal Engineering Proceedings ◽

10.9753/icce.v16.35 ◽

1978 ◽

Vol 1 (16) ◽

pp. 35 ◽

Cited By ~ 3

Author(s):

Yoshimi Goda ◽

Tomotsuka Takayama ◽

Tasumasa Suzuki

Keyword(s):

Wave Diffraction ◽

Spectral Characteristics ◽

Wave Spectrum ◽

Standard Form ◽

Random Wave ◽

Random Waves ◽

Directional Spectrum ◽

Spreading Function ◽

Wave Heights ◽

Directional Wave

Conventional wave diffraction diagrams often yield erroneous estimation of wave heights behind breakwaters in the sea, because they are prepared for monochromatic waves while actual waves in the sea are random with directional spectral characteristics. A proposal is made for the standard form of directional wave spectrum on the basis of Mitsuyasu's formula for directional spreading function. A new set of diffraction diagrams have been constructed for random waves with the proposed directional spectrum. Problems of multi-diffraction and multi-reflection within a harbour can also be solved with serial applications of random wave diffraction.

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Arthroscopic Single-Row Versus Double-Row Suture Anchor Rotator Cuff Repair

Yearbook of Hand and Upper Limb Surgery ◽

10.1016/s1551-7977(08)70223-1 ◽

2007 ◽

Vol 2007 ◽

pp. 30-31 ◽

Cited By ~ 1

Author(s):

R.J. Goitz

Keyword(s):

Rotator Cuff ◽

Rotator Cuff Repair ◽

Suture Anchor ◽

Double Row ◽

Single Row ◽

Cuff Repair

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Clinical & Radiological Assessment of Rotator Cuff Healing After Single Row Vs. Double Row Rotator Cuff Repair

Case Medical Research ◽

10.31525/ct1-nct03885856 ◽

2019 ◽

Author(s):

Keyword(s):

Rotator Cuff ◽

Rotator Cuff Repair ◽

Radiological Assessment ◽

Double Row ◽

Single Row ◽

Cuff Repair

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Time Scale for Scour Beneath Pipelines Due to Long-Crested and Short-Crested Nonlinear Random Waves Plus Current

Journal of Marine Science and Engineering ◽

10.3390/jmse9020114 ◽

2021 ◽

Vol 9 (2) ◽

pp. 114

Author(s):

Dag Myrhaug ◽

Muk Chen Ong

Keyword(s):

Time Scale ◽

Current Flow ◽

Irregular Waves ◽

Wave Crest ◽

Random Wave ◽

Random Waves ◽

Flow Conditions ◽

Regular Waves ◽

Nonlinear Random Waves ◽

2D And 3D

This article derives the time scale of pipeline scour caused by 2D (long-crested) and 3D (short-crested) nonlinear irregular waves and current for wave-dominant flow. The motivation is to provide a simple engineering tool suitable to use when assessing the time scale of equilibrium pipeline scour for these flow conditions. The method assumes the random wave process to be stationary and narrow banded adopting a distribution of the wave crest height representing 2D and 3D nonlinear irregular waves and a time scale formula for regular waves plus current. The presented results cover a range of random waves plus current flow conditions for which the method is valid. Results for typical field conditions are also presented. A possible application of the outcome of this study is that, e.g., consulting engineers can use it as part of assessing the on-bottom stability of seabed pipelines.

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Fixationssysteme und Techniken zur arthroskopischen Rotatorenmanschettenrekonstruktion

Arthroskopie ◽

10.1007/s00142-021-00440-3 ◽

2021 ◽

Author(s):

Paul Borbas ◽

Karl Wieser ◽

Florian Grubhofer

Keyword(s):

Double Row ◽

Single Row ◽

Suture Bridge

ZusammenfassungArthroskopische Rotatorenmanschettenrekonstruktionen wurden initial mit einer einreihigen („single row“) Technik beschrieben. Im Rahmen technischer Weiterentwicklungen der arthroskopischen Chirurgie wurden diverse Techniken zur zweireihigen („double row“), transossären und transossär-äquivalenten Sehnenfixation entwickelt, nicht zuletzt durch eine zunehmende Verbreitung knotenloser Anker. Die klinischen Ergebnisse zeigen keine relevanten Unterschiede zwischen den jeweiligen Techniken. Biomechanisch sind zweireihige Rekonstruktionen jedoch durch Vergrößerung der Kontaktfläche an der Insertionsstelle und der erreichten Stabilität überlegen, insbesondere mit medial geknoteten Fäden, welche in eine laterale Reihe als sog. Suture-Bridge abgespannt werden. Klassischerweise wurden Schraubanker aus Metall für eine arthroskopische Sehnenfixierung verwendet. Im Laufe der letzten Jahre wurde das Anker-Portfolio jedoch durch moderne bioresorbierbare und nichtresorbierbare (PEEK) Schraub- und Einschlaganker sowie auch um reine Fadenanker (All-suture) erweitert. Ein allgemeingültiger Goldstandard für die Ankerverwendung existiert bis dato nicht, wobei die meisten gängigen Anker – zumindest bei guter Knochenqualität – ausreichende Stabilität gewährleisten. Beim Nahtmaterial kam es ebenso zu relevanten Weiterentwicklungen, sodass dem Versagen der Nähte heutzutage weniger Bedeutung zukommt. Das Aufkommen von bandartigem Nahtmaterial (Tapes) konnte in diversen biomechanischen Studien seine Überlegenheit nachweisen, jedoch ist bei geknoteten Techniken mit Tapes aufgrund des womöglich negativen Einflusses durch größere Knoten Vorsicht geboten. Nicht zuletzt ist die mediale Stichposition möglichst nahe des Rotatorenkabels von großer Bedeutung, da der häufigste Versagensmechanismus einer Rotatorenmanschettenrekonstruktion mit modernem Naht- und Ankermaterial weiterhin ein Hindurchschneiden der Fäden durch das vorgeschädigte Sehnengewebe ist.

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