scholarly journals WAVE BREAKING AND WAVE SETUP OF ARTIFICIAL REEF WITH INCLINED CROWN

2011 ◽  
Vol 1 (32) ◽  
pp. 18
Author(s):  
Keisuke Murakami ◽  
Daisuke Maki
Keyword(s):  
Cross Section ◽  
Wave Height ◽  
Energy Flux ◽  
Incident Wave ◽  
Wave Energy ◽  
Wave Breaking ◽  
Artificial Reef ◽  
The Other ◽  
Wave Setup ◽  
Other Hand

INTRODUCION The beach protection facilities are required in some situations to harmonize with coastal environments and utilizations(National Association of Sea Coast,2004). This study investigates some hydraulic functions of proposed multipurpose artificial reef which has an inclined reef crown. The reef is expected to protect beaches against storm waves, and also facilitates the surfing activities under mild wave conditions. The forced wave breaking on the reef sometimes causes a mass transport and wave setup. This study focuses on the following hydraulic characters to clear the efficiencies of proposed artificial reef with inclined crown. 1) Wave energy dissipation by the reef, 2) Generation of suitable wave breakers for surfing, 3) Wave setup behind the reef. HYDRAULIC EXPERIMENT SETUP A series of hydraulic experiments were carried out with using a two-dimensional wave flume. The model scale was assumed 1/30. Three kinds of cross sections were employed as the model of artificial reef (Fig.-1). Both Case-A and Case-B have the inclined crown. The cross section of Case-C, which has a flat crown, is set as a typical cross section of conventional artificial reef. The reef length of Case-A is the same as that of Case-C, and Case-B is double the length of Case-A. Two different submerged depths of crown, hc=2cm and 5cm, were set in the experiments. In Case-A and Case-B, their submerged depth of crown, hc, were defined as the minimum depth at the onshore edge of the crown. The incident wave heights were changed at 1cm intervals from 4cm to 9cm, and the periods were also chanced at 1 sec. intervals from 1 sec. to 2.4 sec. for each wave height. SUMMARY OF RESULTS The energy flux ratio of transmitted waves in Case-B shows similar values in Case-C under the stormy wave conditions in the case of hc=2cm. The longer reef shows favorable characters in dissipating wave energy as well as in maintaining a wider breaker zone on its crown. On the other hand, the transmitted energy flux in Case-A become slightly higher than that in Case-C. The inclined shape of the reef crown closely relates to both the type of wave breakers and the generation of higher order waves. Wave breakers observed in Case-A and Case-B are almost Plunging breaker or Collapsing breaker, and these breakers are suitable for surfing(Walker, et.al.,1972). In Case-C, on the other hand, most incident waves break at the offshore edge of the crown with backwash(Fig.-2). This means that the slope on the reef crown play an important roll in generating suitable breakers for surfing. Type of wave breakers on the inclined reef were summarized by surf similarity parameter(Battjes,1974). Fig.-3 shows the normalized wave setup behind each reef. The wave setup differs depending the reef sections. Case-A and Case-B check the wave setup effectively in comparison with Case-C. This excellent checking effect can be observed in the wide range of incident wave height and wave period. Through a series of hydraulic experiments, it is cleared that the difference of wave setup observed behind the reefs relates to the wave breaker type and wave breaker point on the reefs.

The Review of Studies on Formulas for Calculating Wave Breaking Height

2013 ◽  
Vol 392 ◽  
pp. 958-961
Author(s):  
Jia Xuan Yang ◽  
Shou Xian Zhu ◽  
Xun Qiang Li ◽  
Wen Jing Zhang ◽  
Lei Wang
Keyword(s):  
Wave Height ◽  
Wave Breaking ◽  
Calculation Model ◽  
The Other ◽  
Breaking Wave ◽  
Present Calculation ◽  
Calculation Methods ◽  
Ocean Engineering ◽  
Wave Calculation ◽  
Computing Models

Wave breaking is the most complex and intensified physical process in coastal zone. And as the maximum in this area, the breaking wave height has a major impact on ocean engineering and ship sailing. In this paper, the present calculation methods for breaking height are concluded and divided into two categories: one is directly computing models using deep wave elements; the other is indirectly calculation models based on the surf wave calculation model and the criterion of breaking.

Clumpy artifacts can be differentiated from tophi with DECT: comparison between gout-free and gouty patients

2021 ◽  
Author(s):  
Dong Han Shin ◽  
You Seon Song ◽  
Yunjung Choi ◽  
Wan-Hee Yoo ◽  
Florian Kummel ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Cross Section ◽  
The Other ◽  
Width Ratio ◽  
Foot And Ankle ◽  
Anatomic Location ◽  
Other Hand ◽  
Almost All ◽  
Oval Shape

Objectives: To accurately differentiate clumpy artifacts and tophi with foot and ankle DECT. Methods and materials: In session 1, 108 clumpy artifacts from 35 patients and 130 tophi images from 25 patients were analyzed. Reviewers classified green pixelation according to anatomic location, shape (linear, stippled, angular, oval), and height and width ratio. In session 2, green pixelation confined to the tendon was evaluated (shape, height and width ratio, occupied area in the tendon, accompanied peritendinous green pixelation). Results: In session 1, while tophi were noted at various locations, almost all clumpy artifacts were located at the tendon (99%, p < 0.0001). Most clumpy artifacts were linear, stippled, and wide, while most tophi were angular and oval (p < 0.05). In session 2, the shape of green pixelation from clumpy artefact and tophi was significantly different (p < 0.0001) and most clumpy artifacts occupied less than 50% of the tendon (p = 0.02), and most tophi were accompanied by peritendinous green pixelation (p < 0.0001). Univariant logistic regression showed that tophi were significantly correlated with peritendinous deposits, angular and oval shape, and more than 50% of the tendon (p < 0.05). Conclusion: Clumpy artifacts can be differentiated from tophi in DECT. Clumpy artifacts typically are located in the tendon with a linear or stippled shape, wide, and less than 50% of a tendon’s cross-section. Tophi, on the other hand, typically are oval, larger than 50% of the tendon’s cross-section, and associated with adjacent peritendinous green pixelation. Advances in knowledge: Clumpy artifacts can be differentiated from tophi in image findings by their location and shape.

scholarly journals Interannual variations of ice cover and wave energy flux in the northeastern Baltic Sea

2013 ◽  
Vol 54 (62) ◽  
pp. 175-182 ◽  
Author(s):  
Inga Zaitseva-Pärnaste ◽  
Tarmo Soomere
Keyword(s):  
Baltic Sea ◽  
Wave Height ◽  
Energy Flux ◽  
Wave Energy ◽  
Bulk Wave ◽  
Wave Energy Flux ◽  
The Mean ◽  
A Site ◽  
The Impact ◽  
Wave Properties

AbstractThe major factor shaping the coast of the micro-tidal Baltic Sea is wave activity, the impact of which is limited by the presence or absence of sea ice. Existing studies have revealed almost no correlation between the annual mean wave height and the duration of the ice season. We attempt to evaluate the correlation between ice season duration and bulk wave energy flux (wave power), mean energy and average wave height over the ice-free season for three segments of the Estonian coast (Vilsandi, Pakri and Narva-Joesuu). Statistically significant correlation at the 95% confidence level exists between the duration of the ice season at Vilsandi (a site fully open to the predominant winds) and bulk wave energy flux derived from both observed and modelled wave properties. Similarly strong correlation exists between the mean wave energy and the duration of the ice season at the largely sheltered Narva-Joesuu site.

Prediction of Characteristics of Wave Breaking in Shallow Water Using Neural Network Techniques

2017 ◽  
Author(s):  
Nicholas Kouvaras ◽  
Manhar R. Dhanak
Keyword(s):  
Neural Network ◽  
Wave Height ◽  
Predictive Models ◽  
Wave Breaking ◽  
Laboratory Experiments ◽  
Network Models ◽  
Classification Model ◽  
Neural Network Models ◽  
Wave Setup ◽  
Fringing Reef

The characteristics of wave breaking over a fringing reef are considered using a set of laboratory experiments and the results are used to develop associated predictive models. Various methods are typically used to estimate the characteristics of nearshore wave breaking, mostly based on empirical, analytical and numerical techniques. Deo et al. (2003) used an artificial neural network approach to predict the breaking wave height and breaking depth for waves transforming over a range of simply sloped bottoms. The approach is based on using available representative data to train appropriate neural network models. The Deo et al. (2003) approach is extended here to predict other characteristics of wave breaking, including the type of wave breaking, and the position of breaking over a fringing reef, as well as the associated wave setup, and the rate of dissipation of wave energy, based on observations from a series of laboratory experiments involving monochromatic waves impacting on an idealized reef. Yao et al. (2013) showed that for such geometry, the critical parameter is the ratio of deep-water wave height to the depth of the shallow reef flat downstream of the position of wave breaking, H1/hs, rather than the slope of the reef. H1/hs, and the wave frequency parameter, fH1/g, are provided as inputs to the neural network models of the feed-forward type that are developed to predict the above characteristics of wave breaking. The models are trained using the experimental data. The breaker type classification model has a success rate of over 95%, implying that the neural networks method outperforms previously used criteria for classifying breaker types. The numeric prediction model for the dimensionless position of wave breaking also performs well, with a high degree of correlation between the predicted and actual positions of wave breaking. The performance is higher when only the plunging breaker instances are considered, but lower when only the spilling breaker instances are considered. The corresponding neural network models for wave setup within the surf zone and the difference in energy flux between the incident and broken wave have success rates of approximately 89% and 94% respectively. The method may be extended to provide predictive models for consideration of a range of natural coastal conditions, random waves, and various bottom profiles and complex geometry, based on training and testing of the models using representative field and laboratory observational data, in support of accurate prediction of near-shore wave phenomena.

scholarly journals Wave-Driven Circulation of a Coastal Reef–Lagoon System

2009 ◽  
Vol 39 (4) ◽  
pp. 873-893 ◽  
Author(s):  
Ryan J. Lowe ◽  
James L. Falter ◽  
Stephen G. Monismith ◽  
Marlin J. Atkinson
Keyword(s):  
Wave Height ◽  
Incident Wave ◽  
Surf Zone ◽  
Frictional Resistance ◽  
Morphological Properties ◽  
Wave Setup ◽  
Wave Forcing ◽  
Kaneohe Bay ◽  
Reef Lagoon ◽  
Lagoon System

Abstract The response of the circulation of a coral reef system in Kaneohe Bay, Hawaii, to incident wave forcing was investigated using field data collected during a 10-month experiment. Results from the study revealed that wave forcing was the dominant mechanism driving the circulation over much of Kaneohe Bay. As predicted theoretically, wave setup generated near the reef crest resulting from wave breaking established a pressure gradient that drove flow over the reef and out of the two reef channels. Maximum reef setup was found to be roughly proportional to the offshore wave energy flux above a threshold root-mean-square wave height of 0.7 m (at which height setup was negligible). On the reef flat, the wave-driven currents increased approximately linearly with incident wave height; however, the magnitude of these currents was relatively weak (typically &lt;20 cm s−1) because of (i) the mild fore-reef slope of Kaneohe Bay that reduced setup resulting from a combination of frictional wave damping and its relatively wide surf zone compared to steep-faced reefs, and (ii) the presence of significant wave setup inside its coastally bounded lagoon, resulting from frictional resistance on the lagoon–channel return flows, which reduced cross-reef setup gradients by 60%–80%. In general, the dynamics of these wave-driven currents roughly matched predictions derived from quasi-one-dimensional mass and momentum balances that incorporated radiation stresses, setup gradients, bottom friction, and the morphological properties of the reef–lagoon system.

scholarly journals LIGHT LEPTOQUARKS AND HIGGS PAIR PRODUCTION

2016 ◽  
pp. 40-48
Author(s):  
Ts Enkhbat
Keyword(s):  
Pair Production ◽  
Cross Section ◽  
Decay Channel ◽  
Production Cross ◽  
Decay Rates ◽  
The Other ◽  
Experimental Program ◽  
Simultaneous Presence ◽  
Data Set ◽  
Other Hand

The data collected by the LHC experiments at 7 and 8 TeV with ~5 and 20fb-1 respectively is refining the details of the Higgs like resonances found last year [1,2]. Many decay channels have been searched for and the individual channels so far have given us a consistent picture with what one expects from the SM Higgs. On the other hand, the self interaction of the Higgs, which is probed by the Higgs pair production [3-7], is too feeble in the SM to be detected with these early data set. Even at 14 TeV run, the luminosity required for probing this process is very high [7-17]. This fact, namely the smallness of the corresponding Higgs pair production cross-section, makes it sensitive to a presence of a new physics [18-31]. In particular, relatively light colored particles are known to affect the cross-section substantially [18-22]. As a mater of fact there are many models with various motivations including models of GUT remnants [32-39], composite models [40-48] or a radiative neutrino mass models [49-51] which may give such contributions. Among these the scalars are interesting as they may play crucial role in the spontaneous symmetry breaking through additional terms with large portal couplings in the scalar potential. In the present work we study the phenomenological consequences of the Standard Model extension by two or more colored scalar particles. As a case study we take several leptoquarks (LQ) since there is an active experimental program by both ATLAS and CMS [52-57] and the lower bounds on their masses have now reached impressive levels some as high as a TeV value. On the other hand simultaneous presence of several LQs, may open up additional channels and therefore weakens these bounds. Specific models where the LQs are introduced to explain a certain phenomenon usually requires more than one LQs as in the model we study here. I examine a possibility of the existence of LQs with masses as light as ~180 GeV and study their effect for the single and di Higgs productions. As we will see the Higgs pair production is substantially altered in the low mass range below 300 GeV without too much change in the Higss diphoton decay channel if portal couplings are large. These couplings are required to have opposite signs by the latest Higgs data or small in magnitude. The model I consider has two LQs, an SU(2) doublet ω and a singlet χ. As we will see their simultaneous presence still allows them to have relatively light masses and escape the current bounds. In particular, the current bounds do not include LQs decaying to τt the masses below 200 GeV. Such a scenario, for example, has appeared in a model considered by Babu and Julio [49], where the light neutrino masses are induced by two-loop effects from LQs. If their masses are only of order few hundred GeV, as it is required in this case, the scenario can be probed or even excluded with the data from the LHC. Therefore this is one of the easiest model which can be tested and is the subject of the current study. Although I consider a particular model, it should be stressed that other models with colored particles can affect the pair productions in a similar manner.In Section II, I briefly list the current experimental status on the Higgs production and decay rates. Then I introduce the model I examined in the paper. Section III contains main part of this work where the numerical results for the single and pair Higgs productions are presented. The conclusion is given in Section IV.

scholarly journals An investigation on the properties of polyester textured yarns produced with different fiber cross-sectional shapes

2018 ◽  
Vol 69 (04) ◽  
pp. 270-276
Author(s):  
HACIOĞULLARI SELCEN ÖZKAN ◽  
BABAARSLAN OSMAN
Keyword(s):  
Cross Section ◽  
Linear Density ◽  
The Other ◽  
Cross Sectional ◽  
Round Cross Section ◽  
Breaking Elongation ◽  
Other Hand ◽  
Density Values ◽  
Yarn Tenacity ◽  
Round Cross

In this study, the effects of different fiber cross-sectional shapes and yarn linear density values on Partially Oriented Yarn (POY) and textured yarn characteristics have been examined. In experiment, five different cross-sectional shapes, namely round, trilobal, tetra, hexsa and octolobal and two different linear densities have been used and tenacityelongation, crimp and shrinkage tests have been applied to the yarns. As a result, the round and octolobal crosssectional shapes lead to yarn formation with high tenacity and breaking elongation, on the other hand trilobal and hexsa cause low tenacity and breaking elongation. The round cross-section has provided yarn formation with high crimp and low shrinkage, the hexsa and tetra cross-sectional shapes have caused lower crimp and high shrinkage. It was also observed that the increase in the linear density has caused a decrease in yarn tenacity, however this has increased the crimp and shrinkage behaviours of the yarns.

scholarly journals WAVE SETUP ON VEGETATED BEACH: LABORATORY EXPERIMENTS

2017 ◽  
pp. 4 ◽  
Author(s):  
Yavuz Ozeren ◽  
Daniel Wren ◽  
Weiming Wu
Keyword(s):  
Wave Height ◽  
Wave Breaking ◽  
Wave Attenuation ◽  
Irregular Waves ◽  
Wave Tank ◽  
Wave Setup ◽  
Irregular Wave ◽  
Rigid Vegetation ◽  
Flexible Vegetation ◽  
Vegetation Models

In this study, wave height evolution and wave setup were measured in a laboratory wave tank with a sloping beach covered with rigid and flexible artificial vegetation under regular and irregular wave conditions. The experiments were conducted in a 20.6 m long, 0.69 m wide and 1.22 m deep wave tank at the USDA-ARS National Sedimentation Laboratory, Oxford, MS, USA. Regular and irregular waves were generated using a computer controlled piston type wave generator. A plane wooden beach with a 1:21 slope was constructed at the down-wave end of the wave tank, 11.5 m away from the wave paddle. Rigid vegetation was constructed out of wooden dowels and flexible vegetation was constructed using polyurethane tubes. Both vegetation models were 3.1 mm in diameter and 0.2 m long and had a population density of 3,182 stems/m2. The results were compared with those from experiments on a non-vegetated plane beach. Both rigid and flexible vegetation models reduced the wave height and wave setup substantially, but rigid vegetation typically performed better in reducing wave setup. For some of the experiments, no wave breaking was observed over the vegetated models, indicating that wave attenuation due to vegetation reduced the shoaling rate. For other experiments, wave breaking was observed and wave height attenuation was very small; however, wave setup was still significantly lower than in the plane beach experiments.

Numerical Analysis of the Oscillating Water Column (OWC) Wave Energy Converter (WEC) Considering Different Incident Wave Height

2017 ◽  
Vol 370 ◽  
pp. 120-129
Author(s):  
Mateus das Neves Gomes ◽  
Eduardo Alves Amado ◽  
Elizaldo Domingues dos Santos ◽  
Liércio André Isoldi ◽  
Luiz Alberto Oliveira Rocha
Keyword(s):  
Water Column ◽  
Wave Height ◽  
Incident Wave ◽  
Wave Energy ◽  
Amplification Factor ◽  
Wave Energy Converter ◽  
Geometric Shape ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Incident Waves

The ocean wave energy conversion into electricity has been increasingly researched in the last years. There are several proposed converters, among them the Oscillating Water Column (OWC) device has been widely studied. The present paper presents a two-dimensional numerical investigation about the fluid dynamics behavior of an OWC Wave Energy Converter (WEC) into electrical energy. The main goal of this work was to numerically analyze the optimized geometric shape obtained in previous work under incident waves with different heights. To do so, the OWC geometric shape was kept constant while the incident wave height was varied. For the numerical solution it was used the Computational Fluid Dynamic (CFD) commercial code FLUENT®, based on the Finite Volume Method (FVM). The multiphasic Volume of Fluid (VOF) model was applied to tackle with the water-air interaction. The computational domain is represented by the OWC device coupled with the wave tank. This work allowed to check the influence of the incident wave height on the hydropneumatic power and the amplification factor of the OWC converter. It was possible to identify that the amplification factor increases as the wave period increases, thereby improving the OWC performance. It is worth to highlight that in the real phenomenon the incident waves on the OWC device have periods, lengths and height variables.

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