scholarly journals Performance Accuracy of Surfbeat in Modeling Infragravity Waves Near and Inside a Harbor

2021 ◽  
Vol 9 (9) ◽  
pp. 918
Author(s):  
Lidian Guo ◽  
Xiaozhou Ma ◽  
Guohai Dong
Keyword(s):  
Acoustic Waves ◽  
Field Measurements ◽  
Short Wave ◽  
Wave Group ◽  
Open Domain ◽  
Infragravity Waves ◽  
Wave Characteristics ◽  
Performance Accuracy ◽  
University Of Technology ◽  
Wave Heights

Infragravity (IG) waves significantly affect the operational efficiency of ports. Therefore, an accurate prediction of IG waves inside a harbor is necessary. In this study, the accuracy of the wave-group-resolving model XBeach Surfbeat (XB-SB, Delft University of Technology, Delft, The Netherlands) in predicting the IG waves inside a harbor was assessed by comparing its results with field measurements. Field measurements were performed at Hambantota Port in southern Sri Lanka. Three acoustic waves and current sensors were used to observe the wave characteristics inside and outside the harbor. First, the model was validated against observations outside the port. Next, the performance accuracy of XB-SB in modeling the hydrodynamics in the harbor was evaluated by comparing its results with the values measured inside the port. The results of the numerical simulations indicated that both the nearshore short and IG wave heights can be accurately reproduced by XB-SB in an open domain without many obstacles. However, the short wave heights in the harbor are severely underestimated by XB-SB. The IG waves inside the harbor are overestimated most of the time. Moreover, the natural periods of Hambantota Port are well calculated by XB-SB. In general, XB-SB is a reliable tool for predicting nearshore IG waves. However, it requires further improvement to reproduce the hydrodynamics in a well-sheltered harbor, such as Hambantota Port.

scholarly journals PROBABILITIES OF BREAKING WAVE CHARACTERISTICS

1970 ◽  
Vol 1 (12) ◽  
pp. 25 ◽  
Author(s):  
J. Ian Collins
Keyword(s):  
Shallow Water ◽  
Probability Density ◽  
Deep Water ◽  
Surf Zone ◽  
Probability Distributions ◽  
Rayleigh Distribution ◽  
Breaking Wave ◽  
Wave Characteristics ◽  
Probability Densities ◽  
Wave Heights

Utilizing the hydrodynamic relationships for shoaling and refraction of waves approaching a shoreline over parallel bottom contours a procedure is developed to transform an arbitrary probability density of wave characteristics in deep water into the corresponding breaking characteristics in shallow Water A number of probability distributions for breaking wave characteristics are derived m terms of assumed deep water probability densities of wave heights wave lengths and angles of approach Some probability densities for wave heights at specific locations in the surf zone are computed for a Rayleigh distribution in deep water The probability computations are used to derive the expectation of energy flux and its distribution.

Evaluating the Persistence of Post-Wildfire Ash: A Multi-Platform Spatiotemporal Analysis

Fire ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 68
Author(s):  
Sarah A. Lewis ◽  
Peter R. Robichaud ◽  
Andrew T. Hudak ◽  
Eva K. Strand ◽  
Jan U. H. Eitel ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Field Measurements ◽  
Cost Effective ◽  
Spatiotemporal Analysis ◽  
Short Wave ◽  
Hydrologic Model ◽  
Landsat 8 ◽  
Data Volume ◽  
Sentinel 2

As wildland fires amplify in size in many regions in the western USA, land and water managers are increasingly concerned about the deleterious effects on drinking water supplies. Consequences of severe wildfires include disturbed soils and areas of thick ash cover, which raises the concern of the risk of water contamination via ash. The persistence of ash cover and depth were monitored for up to 90 days post-fire at nearly 100 plots distributed between two wildfires in Idaho and Washington, USA. Our goal was to determine the most ‘cost’ effective, operational method of mapping post-wildfire ash cover in terms of financial, data volume, time, and processing costs. Field measurements were coupled with multi-platform satellite and aerial imagery collected during the same time span. The image types spanned the spatial resolution of 30 m to sub-meter (Landsat-8, Sentinel-2, WorldView-2, and a drone), while the spectral resolution spanned visible through SWIR (short-wave infrared) bands, and they were all collected at various time scales. We that found several common vegetation and post-fire spectral indices were correlated with ash cover (r = 0.6–0.85); however, the blue normalized difference vegetation index (BNDVI) with monthly Sentinel-2 imagery was especially well-suited for monitoring the change in ash cover during its ephemeral period. A map of the ash cover can be used to estimate the ash load, which can then be used as an input into a hydrologic model predicting ash transport and fate, helping to ultimately improve our ability to predict impacts on downstream water resources.

Abstract 14614: The Automatically Assessed P-wave Notch Predicts Cardiovascular Events in Patients With Cardiovascular Risks: The Japan Morning Surge Home Blood Pressure (J-HOP) Study

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Tomoyuki Kabutoya ◽  
Satoshi Hoshide ◽  
Kazuomi Kario
Keyword(s):  
Left Atrial ◽  
Cardiovascular Events ◽  
Left Ventricular ◽  
Hazard Ratio ◽  
P Wave ◽  
Control Group ◽  
Atrial Remodeling ◽  
Wave Group ◽  
Left Atrial Diameter ◽  
Wave Characteristics

Background: The notched P-wave characteristics is associated with atrial remodeling. However, the relationship between notched P-wave characteristics and long-term cardiovascular events remains unclear. Hypothesis: We hypothesized that the notched P-wave would be associated with cardiovascular events. Methods: We enrolled 810 subjects from the J-HOP Study who had ≥1 of four cardiovascular risk factors. Twelve-lead electrocardiography was conducted, and the peak-to-peak distance in the M-shape was calculated automatically using a 12-lead ECG Analysis system (Fukuda Denshi, Tokyo). We compared two definitions: P waves were defined as "notched" if the peak-to-peak distance in the M-shape was ≥20 msec or ≥40 msec in lead II. The primary endpoints were fatal/nonfatal cardiovascular events: myocardial infarction, stroke, hospitalization for heart failure, and aortic dissection. We assessed the left atrial diameter and left ventricular mass index (LVMI) by echocardiography. Results: The mean follow-up period was 101±34 months, and 85 cardiovascular events occurred. When we defined a notched P wave as ≥20msec in the M shape (n=92), a notched P wave was a significant predictor of cardiovascular events after adjustment for age, gender, and comorbidity (hazard ratio 1.80, 95%CI: 1.06-3.05). When we defined a notched P wave as ≥40msec in the M shape (n=25), the hazard ratio of cardiovascular events in the notched P-wave group was significantly borderline after adjustment for covariates (hazard ratio 2.23, 95%CI: 0.90-5.56). The left atrial diameter and LVMI in the patients in the notched P-wave group (≥20 msec in the M shape) were significantly higher than those in the control group (left atrial dia. 38.8±5.9 vs. 36.8±5.0 mm, p=0.001; LVMI 103.9±27.7 vs. 96.3±25.7 g/m 2 , p=0.010). Conclusion: The automatically assessed notched P wave was associated with cardiovascular events, left atrial enlargement and left ventricular hypertrophy.

scholarly journals A COMPARISON OF NATURE WAVES AND MODEL WAVES WITH SPECIAL REFERENCE TO WAVE GROUPING

1980 ◽  
Vol 1 (17) ◽  
pp. 177 ◽  
Author(s):  
Hans F. Burcharth
Keyword(s):  
Phase Distribution ◽  
Random Phase ◽  
Power Spectra ◽  
Height Distribution ◽  
Wave Group ◽  
Storm Waves ◽  
Wave Height Distribution ◽  
Storm Wave ◽  
Wave Heights ◽  
The Impact

This paper represents a comparative analysis of the occurrence of wave grouping in field storm waves and laboratory waves with similar power spectra and wave height distribution. Two wave patterns - runs of waves and jumps in wave heights - which have significant influence on the impact on coastal structures were included in the analysis of storm wave records off the coasts of Cornwall, U.K. and Jutland, Denmark. Two different laboratory wave generator systems, based on random phase distribution of component waves, were used. Within the limitations given by the relatively small number of analysed records it is shown that wave group statistics can be satisfactorily reproduced by random phase generators that are not based on a limited number of component waves, but for example based on filtering of white noise. It is also shown that the statistics of large waves and wave groups containing large waves depend on whether the waves are defined from zero-upcrossings or zero-downcrossings. Although very similar seas were chosen for the analysis it was found that significant differences in the wave group statistics from the two locations existed. Also a considerable scatter in the wave group statistics throughout the storms was found.

Uncertainties in Extreme Wave Height Estimates for Hurricane-Dominated Regions

2007 ◽  
Vol 129 (4) ◽  
pp. 300-305 ◽  
Author(s):  
Philip Jonathan ◽  
Kevin Ewans
Keyword(s):  
Wave Height ◽  
Significant Wave Height ◽  
Small Data ◽  
Extreme Wave ◽  
Significant Wave ◽  
Wave Characteristics ◽  
Height Estimates ◽  
Wave Heights ◽  
Using Data ◽  
High Percentile

Inherent uncertainties in estimation of extreme wave heights in hurricane-dominated regions are explored using data from the GOMOS Gulf of Mexico hindcast for 1900–2005. In particular, the effect of combining correlated values from a neighborhood of 72 grid locations on extreme wave height estimation is quantified. We show that, based on small data samples, extreme wave heights are underestimated and site averaging usually improves estimates. We present a bootstrapping approach to evaluate uncertainty in extreme wave height estimates. We also argue in favor of modeling supplementary indicators for extreme wave characteristics, such as a high percentile (95%) of the distribution of 100-year significant wave height, in addition to its most probable value, especially for environments where the distribution of 100-year significant wave height is strongly skewed.

MECHANISM AND COUNTERMEASURES OF WAVE OVERTOPPING FOR LONG-PERIOD SWELL IN COMPLEX BATHYMETRY

2012 ◽  
Vol 1 (33) ◽  
pp. 45
Author(s):  
Hiroaki Kashima ◽  
Katsuya Hirayama
Keyword(s):  
Deep Water ◽  
Wave Energy ◽  
Spatial Relationship ◽  
Wave Transformation ◽  
Wave Overtopping ◽  
Long Period ◽  
Wave Characteristics ◽  
Water Region ◽  
Wave Heights ◽  
Shallow Water Region

Recently, coastal disasters due to long-period swells induced by heavy storms and catastrophic typhoons have increased at Japanese coasts and harbors. Long-period swells are more susceptible to the bottom bathymetry of the offshore deep water region and their wave heights locally increase due to the concentration of wave energy caused by the complex bottom bathymetry in the relatively shallow water region. In addition, the wave overtopping rate may increase due to the long waves in front of the seawall induced by the long-period swells. However, the spatial relationship between wave characteristics and wave overtopping discharges in the complex bathymetry are not well known owing to a lack of detailed measurements. In this study, model experiments were conducted by using a large basin to investigate the spatial characteristics of wave transformation and wave overtopping focusing on the heavy wave overtopping damages caused by the arrivals of long-period swells at the Shimoniikawa Coast in 2008. Effective countermeasures against wave overtopping are also discussed based on their characteristics.

Environmental Forces on Offshore LNG Terminals: The Complications of Shallow Water

2004 ◽  
Author(s):  
George Z. Forrsitall
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Field Measurements ◽  
Review Of The Literature ◽  
Water Demands ◽  
Local Measurements ◽  
Wave Heights ◽  
Overall Reliability ◽  
Water Depths ◽  
Water Bottom

Construction of large and expensive facilities in relatively shallow water demands that additional effort be paid to the extreme environmental conditions expected there. A review of the literature on waves in shallow water shows that many processes must be considered there which are not important in deep water. Bottom friction under waves depends on the detailed bottom conditions and parameterizing it properly may require calibration to local measurements. The limits on wave heights over the nearly flat bottoms that are common in water depths of 10–30 m are poorly known. Additional laboratory and field measurements appear to be necessary before depth limited waves can be confidently specified. The structures often respond differently to wave from different directions, so directional criteria could be useful. Commonly used methods of specifying directional criteria are un-conservative, but it is possible to adjust them so that the overall reliability of the structure is preserved.

Numerical Simulation of Breaking Waves in a Wave Group by SPH

2015 ◽  
Vol 776 ◽  
pp. 151-156
Author(s):  
Ni Nyoman Pujianiki
Keyword(s):  
Surf Zone ◽  
Breaking Waves ◽  
Return Flow ◽  
Wave Group ◽  
Regular Waves ◽  
Wave Groups ◽  
Smoothed Particle ◽  
Wave Heights ◽  
Smoothed Particle Hydrodynamic ◽  
Wave Break

Smoothed Particle Hydrodynamic (SPH) numerical model is used to investigate wave group effects at breaking and after breaking by comparing individual waves in a group with equivalent regular waves. Regular wave break almost at the same position and with the same wave height. Meanwhile in a wave group, the wave breaks in the variant positions and with variant wave heights. These phenomena cause the breaking point to be more scattered in a wave group rather than in regular waves. Return flow due to the breaking of wave groups appears more significant and is extended to the full depth in the surf zone rather than in regular waves. Swash oscillations of the wave group in the surf zone appear irregular. Meanwhile in regular waves, swash oscillations are almost constant.

scholarly journals Analytical Investigation of Surface Wave Characteristics of Piezoelectromagnetics of Class 6 mm

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Aleksey A. Zakharenko
Keyword(s):  
Surface Wave ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Transversely Isotropic ◽  
Analytical Investigation ◽  
Wave Characteristics ◽  
Surface Wave Propagation ◽  
Theoretical Investigations ◽  
Derivatives Of ◽  
Shear Horizontal

This short work copes with theoretical investigations of some surface wave characteristics for transversely isotropic piezoelectromagnetic composites of class 6 mm. In the composite materials, the surface Bleustein-Gulyaev-Melkumyan wave and some new shear-horizontal surface acoustic waves (SH-SAWs) recently discovered by the author can propagate. The phase velocities of the SH-SAWs can have complicated dependencies on the coefficient of the magnetoelectromechanical coupling (CMEMC) which depends on the electromagnetic constant of the composites. Therefore, the analytical finding of the first and second partial derivatives of the represents the main purpose of this study. It is thought that the results of this short letter can help for theoreticians and experimentalists working in the research arena of opto-acoustoelectronics to completely understand some problems of surface wave propagation in piezoelectromagnetics.

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