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The real-time monitoring of ocean wave data is a crucial element in marine environmental monitoring and the development of marine resources. It is unfortunate that the majority of wave measurement devices remain challenging, relatively high-priced, and require sophisticated technology. This study investigates the validation of a new type of ocean wave measurement, designed based on the mini wave gauge (MWG), using low-cost materials. The study utilizes an accelerometer sensor, specifically the ADXL335, which is converted to measure wave height, and the GY-271 designed to measure wave direction. This research addresses the validation of MWG by comparing measurements from the acoustic doppler current profiler (ADCP) and HOBO. The validation of wave height demonstrates high accuracy, with a MAPE percentage of 0.46% between MWG and ADCP, and 23.30% between MWG and HOBO. In contrast, the validation of MWG for wave direction by ADCP still requires improvement, with a MAPE of 36.75%. This is due to the sensor's sensitivity to the earth's magnetic field, which requires further improvement of the buoy design to accommodate the direction of incoming waves. Additionally, the MWG's sampling rate in milliseconds allows for analyzing wave characteristics based on wave periods using the fast Fourier transform (FFT) method. [ABSTRACT FROM AUTHOR]

This paper studies the bandgap characteristics of a locally resonant metamaterial beam with time delays. The dispersion relations are addressed based on transfer matrix method. The governing equations of motion of the beam in the frequency domain are given according to spectral element method. The amplitude-frequency responses of the forced beam are determined by solving linear algebraic equations. The obtained results show that the time-delayed feedback control has great relationships with the location, width and number of the bandgaps. It is interesting that the time delay can change the direction of the movement of the bandgap and give rise to the generation of multiple bandgaps. The influences of different combinations of control parameters on the bandgap properties are shown, such as broadening effects. [ABSTRACT FROM AUTHOR]

The risk of typhoon disasters is high in the Zhejiang coastal areas; however, it has been difficult to characterize waves generated by these typhoons, particularly in shallow waters. In this study, the characteristics of nearshore typhoon waves were analyzed using data from 14 typhoon processes from a wave station on the central coast of Zhejiang Province for three consecutive years from 2016 to 2018. According to their paths, these typhoons were divided into landing and nonlanding steering types. Wave parameters were evaluated using statistical analyses and linear regression. Variations in wave parameters and spectra are discussed. We obtained several key results: (1) The dominant wave direction was E-SE and the strong wave direction was SE. (2) There were strong correlations between characteristic wave heights and between characteristic periods. (3) Single-peak spectra were dominant, with a frequency of 92.33%. The minimum peak frequency was 0.06-0.1 Hz and the maximum peak period was 17.7 s. The typhoon waves were mainly composed of swells with a frequency of 94.54%. (4) Affected by Typhoon Maria (No. 201808), a maximum wave height of 8.20 m was observed at 04:00 on July 11, 2018. This study provides an important reference for the design of offshore structures and disaster prevention and mitigation. [ABSTRACT FROM AUTHOR]

Introduction. The growth of domestic tourism in the Russian Federation is forecasted to reach 30 % by the end of 2023 compared to the results of 2022. At the same time, ecological tourism in areas with undeveloped engineering infrastructure has become one of the trends of recent years.Materials and methods. To solve the problems of life support of temporary accommodation facilities (glamping), a technical solution for the conversion of hydraulic wave energy in the coastal zone of Russian sea areas is proposed. The purpose of the research is a feasibility study of the application of innovative life support technology based on renewable wave energy to provide municipal resources, including fresh water, to non-permanent accommodation facilities (beach glamping). To achieve this goal, numerical research methods were used using statistical data and long-term observational data, searching for domestic and foreign sources with analysis and comparison of the contained data.Results. Calculations of fresh water productivity are presented, taking into account the unevenness of wave characteristics (heights, periods) throughout the year using the example of the Black sea and the Sea of Japan. It is established that even taking into account the uneven wave characteristics, the Black Sea coastal zone is a commercially significant territory for implementation. The coastal zone of the Sea of Japan is a promising territory in the case of seasonal operation of facilities with the proposed technology. The payback period of the technology for operation on the Black Sea coast was determined.Conclusions. The proposed pump-compressor is able to replace energy-consuming equipment of reverse osmosis installations — high-pressure pumps for supplying seawater to the membranes. The use of technology on the freezing seas is expedient in the non-year-round operation mode. The payback period, depending on the cost of electricity, does not exceed two years without taking into account the associated removal of useful pneumatic power.

As one of the primary services ports provide, pilotage services aim to ensure the safe passage of vessels when entering and leaving the port. This study uses Taichung Port, located in the central part of the Taiwan Strait, as an example to analyze the impact of monsoon characteristics on wave conditions at pilot boarding points and to highlight their crucial role in safeguarding pilot boarding safety. By analyzing data from the ADCP (Acoustic Doppler Current Profiler) station north of the port’s northern breakwater and the Taichung buoy located southwest of the port, compare wave height distributions at the boarding point. The research addresses the impact of current and planned expansions, including constructing a new LNG receiving terminal with extended breakwaters, on wave dynamics and pilot operations. The study demonstrates that data from multiple sources—such as ADCP and buoy measurements—helps mitigate issues caused by missing data from specific stations. The analysis shows that numerical values differ slightly, while wave height trends at the boarding point are similar under current and expanded port conditions. The study concludes that the proposed expansion will likely affect wave diffraction patterns but will enhance the predictability and safety of boarding operations by reducing uncertainties associated with single measurement stations. Overall, the results of this study can enhance the understanding of marine meteorological information, improve the safety of pilot boarding operations, and thereby increase the efficiency and safety of port operations.

The present study is aimed at searching for mechanisms of wave interaction in a supersonic boundary layer on a flat plate with the flow being distorted by a streamwise disturbance generated on a sharp leading edge by a pair of weak shock waves. The space and time distributions and the frequency-wave spectra of oscillations and their wave characteristics in the linear and weakly nonlinear phases of wave train development in a nonhomogeneous boundary layer under conditions of a fixed power of the local source of controlled disturbances are analyzed. Based on experimental results, possible variants of wave interaction in a supersonic boundary layer on a flat plate in the region of the longitudinal wake generated by an N-wave are proposed. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Computational Mechanics / Jisuan Lixue Xuebao is the property of Chinese Journal of Computational Mechanics Editorial Office, Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent decades, renewable energy projects have required careful consideration of environmental factors. This study investigates the impact of a mid-latitude cyclone on planned floating photovoltaic (FPV) facilities in Antalya, Turkey, focusing on the severe thunderstorm events that brought heavy rainfall and tornadoes in January 2019. Synoptic analysis reveals a deep cut-off low over the Genoa Gulf, causing trough formation and vertical cloud development due to moisture convergence. Warm air advection pushed an unstable thunderstorm system northward along an occluded front. Using the Weather Research and Forecast (WRF) model, sensitivity analysis is conducted, highlighting regional variations in wind speeds. The model outputs are compared with observations, identifying the best configuration using statistical indicators. The Mellor–Yamada–Janjic (MYJ) planetary boundary layer (PBL) scheme and the Milbrandt microphysics scheme produced better results in the western and central regions. The model output of the best configurations is used to calculate regional wave characteristics with a modified Shore Protection Manual (SPM) method for water reservoirs. These findings offer invaluable insights for future FPV projects, providing a better understanding of how to address challenges posed by extreme weather conditions and how to enhance system safety and reliability. [ABSTRACT FROM AUTHOR]

This experimental study aims to examine the effect of the surface tension on the characteristics of unidirectional air-liquid interface waves on a horizontal pipe. The pipe used is an acrylic pipe with a diameter of 26 mm. To vary the surface tension, the working fluid consisted of 100% water and water mixed with 2% and 5% butanol. with surface tension (σ) values ​​of 72, 58, and 42.5 mN/m, respectively. The wave characteristics studied in this research include the interface wave structure which is analyzed from visual observations and parameters by image processing. The superficial velocities of gas and liquid were varied in the range of 4-16 m/s and 0.02-0.1 m/s, respectively. Wave velocity and frequency were determined by using cross-correlation and power spectra density (PSD) from time-series data of liquid film thickness. Generally, velocity increases as the gas superficial velocity and surface tension decrease, the high gas superficial velocity the dominant frequency is high.

Ocean energy technologies are in their developmental stages, like other renewable energy sources. To be useable in the energy market, most components of wave energy devices require further improvement. Additionally, wave resource characteristics must be evaluated and estimated correctly to assess the wave energy potential in various coastal areas. Multiple algorithms integrated with numerical models have recently been developed and utilized to estimate, predict, and forecast wave characteristics and wave energy resources. Each algorithm is vital in designing wave energy converters (WECs) to harvest more energy. Although several algorithms based on optimization approaches have been developed for efficiently designing WECs, they are unreliable and suffer from high computational costs. To this end, novel algorithms incorporating machine learning and deep learning have been presented to forecast wave energy resources and optimize WEC design. This review aims to classify and discuss the key characteristics of machine learning and deep learning algorithms that apply to wave energy forecast and optimal configuration of WECs. Consequently, in terms of convergence rate, combining optimization methods, machine learning, and deep learning algorithms can improve the WECs configuration and wave characteristic forecasting and optimization. In addition, the high capability of learning algorithms for forecasting wave resource and energy characteristics was emphasized. Moreover, a review of power take-off (PTO) coefficients and the control of WECs demonstrated the indispensable ability of learning algorithms to optimize PTO parameters and the design of WECs.

Wave spectral characteristics are studied from the measurements made by a moored buoy off Chennai during 2017–2019. Time series wave data in shallow waters off Chennai have been obtained from a coastal buoy in the moored buoy network established and operated by the National Institute of Ocean Technology. Bay of Bengal (BoB) experiences three different weather conditions (i) pre-monsoon (February–May), (ii) South-west (SW)/summer monsoon (June–September), and (iii) North-east (NE)/post-monsoon (October–January). During the period between NE monsoon and SW monsoon (fair-weather), the coast experiences swell domination and, to an extent, wind sea driven and wave spectra are predominantly double peaked. During NE monsoon in November-December, it is a primarily single peaked and spectral peak period for fully developed wind sea equals peak wave period. Short period waves are dominated 65% of the time during the post-monsoon. The peak wave period ranges from 4 to 12 s for 81% of the time, and the predominant mean wave direction is between 135 and 180°. The significant wave height is less than 1.0 m for 61% of the time. The maximum wave height (Hmax) observed is 4.0 m during cyclone Phethai. Two cyclones, Gaja and Phethai, were captured by the moored buoy, and wave spectra were analyzed during cyclone passage. The wave parameters of moored buoy are verified with measurements made by another buoy closely deployed, namely the PP WET buoy (Pilot Project on Wave Measurement, Evaluation and Testing (PP-WET) called PP WET buoy). The comparison shows that the correlation coefficient is 0.96 for significant wave height and 0.91 for the mean wave period for 2018. The comparison between the moored buoy and ERA5 significant wave heights during 2018 produces a higher correlation of 0.90, while the ERA5 data is overestimated by 33% during cyclone Phethai. The implications of this study would be helpful in wave data assimilation and operational forecasting in the coastal waters of the Bay of Bengal. [ABSTRACT FROM AUTHOR]

Waves play a major role in the ocean phenomena in the Gulf of Guinea (GoG). In order to reveal the spatial-temporal distribution characteristics and the propagation mechanism of waves from the South Atlantic Ocean to the GoG, 4 typical points located in mid-latitude of South Atlantic (14°30′W, 30°0′S), south of the GoG (10°30′W, 15°0′S), offshore of the GoG (0°0′, 0°0′) and near shore of the GoG (6°4′58.8″W, 4°3′36″S) are selected, and waves from Atlantic Ocean to GoG are simulated by using a two-layer-nesting wave numerical model SWAN (Simulating Waves Nearshore). The results show that the hybrid waves (waves hereafter) and the swells have strong relationship with local wind in Roaring Forties and at mid-latitude of South Atlantic Ocean, while there is no obvious correlation between waves and local winds in the GoG. Swells are generated in the South Atlantic Ocean and propagate into the GoG. 2D wave spectra at the four selected typical points are simulated. The spectral pattern and wave component structure indicate that the wave system in GoG is dominated by the S–SW swells generated from Roaring Forties and mid-latitude of South Atlantic, whether it is at maximum (2.2–2.8 m), medium (1.8–2.2 m) or minimum (1.2 m) significant wave height in the GoG during simulation period. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The wave and acoustic emission characteristics, as well as the damage evolutions of marble from room temperature to 800°C under uniaxial loading were studied. The results show that for heated marble, the volume increases and the mass and density decrease. 600°C is the threshold temperature for mass and density changes. With the increase of temperature, the peak stress and elastic modulus initially increase then decrease, while the peak strain increases monotonically. With the increase of temperature, the P-wave and S-wave velocity decreases linearly, while the spectrum area, main frequency amplitude and amplitude decrease with a decreased decline rate. It is also found that there exists good consistence between the accumulated AE accounts and the stress-strain curve, which fully reflects the damage evolution law of marble in different stages. Under the effect of high temperature, the failure of marble specimen change from brittle failure to progressive failure, and the failure modes change from shear failure to splitting failure. [ABSTRACT FROM AUTHOR]

The analysis on fixed or floating structures exposed to directional extreme waves has been a topic of keen interest in ocean engineering. In this context, an attempt is made to study the characteristics of laboratory generated directional rogue waves, termed also as focusing waves. The first-order wave paddle displacements were generated using the linear superimposition principle by applying a constant steepness spectrum associated with directional components. The phase angles are set to be constant at a predefined location to create an extreme event. The experimental test cases span from narrow to broadband spectra having two central frequencies, namely, 0.68 and 0.85 Hz. The bandwidth ratios of 0.5 and 0.75 were considered with five discrete directions ranging from −25° to 25°. The tests include spilling breakers and non-breaking waves. The investigation involves studying the variations in the Atiltness parameter (ATP), Crest height ratio, and the nonlinearity parameter provided by Hastings, an index to measure the effect of nonlinearity. In addition, directional studies using the maximum likelihood method (MLM) are also presented. The critical combination of frequency spectrum and bandwidth is identified from the focusing wave characteristics and discussed in this paper for the tested conditions. The shift in directional spectrum due to nonlinearity was noticed in the present study. [ABSTRACT FROM AUTHOR]

This study analyzes the magnetic field wave characteristics of a wireless power transfer (WPT) system from a time-varying view in the nonradiative near field. Phenomena of both forward and backward traveling waves were found. These wave phenomena refer to magnetoinductive waves (MIWs) according to the findings in this study and MIW theory and characteristics. A traditional MIW only appears in the MIW waveguide, which is always constructed by many parallel coils. However, this study analyzed MIWs in a two-coil WPT system, proving that MIWs exist not only in a multi-coil system but also in a basic two-coil system. The velocity of MIWs, a kind of a phase velocity, was calculated. An approximate equation for evaluating wave velocity is proposed. Furthermore, the MIWs in the two-coil WPT system were extended into a more general situation. In this general situation, two separated standing waves were set, and a traveling wave was generated by those two standing waves. The result explains the mechanisms of MIWs in a general situation from a time-varying view. Lastly, a simulation was conducted to verify the accuracy of the study. The results demonstrated that MIWs exist, and the approximate equation is correct. This study presents a novel view on the mechanisms of the WPT system from a wave view. [ABSTRACT FROM AUTHOR]

As a unique landform in the island and reef area, the newborn sandbank is not only the initial stage of island development, but also has a rapid evolution and a complex dynamic mechanism. However, the dynamic geomorphology mechanism of the newborn sandbank is still lacking extensive study and direct evidence of the interaction process between the marine dynamics and the newborn sandbank geomorphology. Therefore, in order to reveal the interaction mechanisms between marine dynamics and newborn sandbanks, a newborn sandbank in the sea area of the Xisha Islands, in the South China Sea, has been selected as the focus of this research. The method of numerical simulation was used to discuss and analyze the wave field characteristics around the newborn sandbank and their impacts on the sandbank's migration and development. The results show that: (1) The islands and reefs have significant refraction, diffraction, and energy dissipation effects on waves, and the newborn sandbank has the same effect, but with a weaker function. The wave height around the reef islands reduced by approximately 60–67% in dominated and strong wave directions. At the same time, the wave height attenuation in the wave shadow zone, behind the newborn sandbank, can reach approximately 27–33%. (2) Wind is important for the evolution of wave fields; in particular, when the wind speed exceeds grades four and five, the effect of the wind on the waves is particularly significant, causing the winds to control the wave characteristics around the islands and newborn sandbanks. This results in significant seasonal differences in wave fields within the sea area. (3) The wave direction primarily controls the migration direction of the newborn sandbank, and the wave height primarily controls the migration speed and distance. After one month of wave action in the strong wave direction, the maximum eastward deposition length was approximately 50 m. After one month of wave action in the dominated wave direction, the maximum eastward deposition length was approximately 60 m. Therefore, the topography of the newborn sandbank affects the wave propagation, meanwhile, the wave conversely determines migration and development of the newborn sandbank in a short term. The dynamic geomorphology action between the wave and newborn sandbank is a fast two-way process, and occurs not only during storms or the winter monsoon, but also during other, more common, weather events. [ABSTRACT FROM AUTHOR]

With the continuous development of marine economy and port construction in West Africa, it is important to be aware of the hydrodynamic characteristics of ocean waves in West African waters, especially the spatial and temporal distribution of wave characteristics. The temporal and spatial distribution of the effective wave heights and periods of combined wave, swell and wind wave in West Africa was analyzed based on the hourly wave characteristics data from the ERA -5reanalysis dataset of the European Center for Medium-Range Weather Forecasts (ECWMF) for 42 years (1979 to 2020). The wave characteristics in dry season and rainy season are significantly different. In terms of spatial distribution, significant wave height of swell and combined wave in West African waters increase from nearshore to offshore and from low latitude to high latitude. The period of swell and combined wave increases from the central region to the periphery. The wave height and period of wind waves gradually increase from south and north sides in the north of the equator, and firstly increase and then decrease from south to north in the south of the equator. The monthly distribution of swell and combined wave mainly presents three characteristics, which are non-peak type with little monthly variation, and Ω type and inverted Ω type with obvious monthly variation. In addition, through the analysis of wave risk, it is found that the risk gradually increases from the nearshore area of central West Africa to the offshore area and from low latitudes to high latitudes, with the highest risk in the southern part of West African waters, followed by the northern part of Cape Verde. [ABSTRACT FROM AUTHOR]

Stilling basin with a negative step is an important structure in hydraulic systems, because it can avoid atomization and decrease scouring problems. Although stilling basins with a negative step have attracted much attention from researchers, few researchers have focused on the wave characteristics. In this research, an experimental study on the wave characteristics of stilling basins with a negative step was carried out. The wave height, average period, wave probability density and power spectrum along the flow direction of different stilling basins with a negative step were described based on the wave theory, and the results indicate discharge and step height have a significant effect on the wave characteristics. The relationships between the different characteristic wave heights, and the empirical formula for the relative characteristic wave height are obtained. Finally, the dimensionless standard deviation at the end of the stilling basin with a negative step is linearly related to the flow-energy ratio and the relative step height under B-jump. [ABSTRACT FROM AUTHOR]

[Introduction] According to the measured wave data of one year in the deep water area of Eastern Guangdong, this paper mainly studies the basic characteristics of annual waves in the sea area. [Method] Firstly, the eigenvalues of wave height and period were counted month by month, get the basic distribution characteristics of the whole year; Then made statistics for the wave direction, obtain the seasonal characteristics of wave direction; Furthermore, the joint distribution of wave height and period and the relationship between wave height and period were explored; Finally, the characteristics of typical typhoon waves were studied. [Result] The results showed that: (1) The annual average Hs is 1.52 m, the Hmax is 15.97 m, the highest mean value of Hs in December, January and February, the Hmax is caused by Typhoon Mangkhut; (2) Affected by monsoon season and tropical cyclone, the normal wave direction and strong wave direction are ENE and SE respectively; (3) The main wave type in the whole year is wind wave component, the correlation between wave height and period is fitted; (4) According to the measured data of typhoon wave of Mangkhut, both wave height and period have a significant increase and decrease process. Through wave spectrum analysis during the typhoon, it experienced the evolution from double-peaked spectrum to single-peaked spectrum, it shows that the wave type during typhoon is mainly wind-surge mixed wave, the peak value reached 96.74 m2/Hz at 6:00 on September 16, peak frequency is 0.07 Hz. [Conclusion] The research results of this paper can provides technical reference for the design of related marine engineering.

The operation of tidal turbines is inevitably influenced by waves, and extensive research has undoubtedly been conducted on this topic. However, most investigations of such studies have utilized small-scale turbines, with a primary focus on the load characteristics of the turbines themselves. There is a slight deficiency in attention to the wave characteristics that contribute to these loads. To bridge this gap, this study develops a computational fluid dynamics (CFD) model of a full-scale tidal turbine. The model's accuracy is assessed through flume experiments using a scaled-down version, validating the numerical approach against wave conditions. Employing actual tidal flow velocity and wave data as input, this study specifically examines how variations in wave period and height affect turbine performance. The analysis reveals a nuanced decrease in time-averaged performance with increases in wave period and height. Load fluctuations arise from wave impacts, turbine rotor rotation, and their interaction. With the increase in wave period or height, the fluctuations caused by the wave impacts and the interaction increase, while those induced by rotor rotation exhibit a slow growth trend but essentially remain stable. • Establishment of a full-scale tidal turbine model using the CFD method. • Validation of the numerical method through a scaled-down experiment. • Exploration of the influences of wave period and height on turbine performance. • In-depth study of both time-averaged performance and load fluctuations. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sifnioti, D.E.; Dolphin, T.J., and Vincent, C.E., 2020. Performance of hindcast wave model data used in UK coastal waters. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 1284–1290. Coconut Creek (Florida), ISSN 0749-0208. Long-term wave data are a necessity for various marine applications, but wave observations can be temporally and spatially sparse, are often absent in the required locations and can be costly and often cannot be obtained in a short notice. The models used are the UK's Met Office's European 38-year wave hindcast "ReMap", which has spatial resolution of 8 km and temporal step of 3 hours, and ECMWF's (European Centre for Medium-Range Weather Forecasts) "ERA5" reanalysis dataset from 1979 to present with a spatial resolution of 31 km and a temporal step of 1 hour. Both datasets include wave and wind parameters, thus providing valuable long-term data that can be used in coastal regions where wave observations are unavailable. In this paper we assess the errors in performance of the ReMap and ERA5 data by comparing these with wave observations made at two coastal sites in the southern North Sea. ReMap and ERA5 showed a strong correlation with measured waves for significant wave height (Hs) (r = 0.84 - 0.9), fair correlation for peak wave period (Tp) (r = 0.58 - 0.68) and good correlation for mean zero up-crossing wave period (Tz) (r = 0.73 – 0.79), with different error statistics per location and per dataset. Analysis of the 90th percentile shows that the ReMap and ERA5 overestimated Hs by approximately 0.5 m, and by up to 1.2 s for Tp and 0.6s for Tz. Monthly and annual means are also presented and discussed. Overall the performances of ReMap and ERA5 against the measured waves were similar. It is concluded that the ReMap and ERA5 data can be used with reasonable confidence in coastal regions where no direct measurements are available for 'average' conditions, but caution needs to be taken for extreme conditions as an over prediction for extremes is likely. [ABSTRACT FROM AUTHOR]

The Karnataka coast is subjected to high wave activity during the southwest monsoon when most of the sandy beaches undergo erosion. Based on the littoral cell concept, the Karnataka coast is broadly divided into 14 major littoral cells and 26 stations are selected in the present study. WaveWatch III global wave model data at 0.5° interval were used to derive the nearshore wave characteristics from XBeach numerical model. The model results were validated with the measured wave rider buoy data of the Indian National Centre for Ocean Information Services. The beach orientation, nearshore slope, median sediment size, significant wave height, mean wave direction, and the peak wave period were used in the estimation of longshore sediment transport rate. The mean significant wave height along the Karnataka coast was about 0.86 m, wave direction was about 210° and peak wave period was about 13 sec. The wave height during southwest monsoon (June–September) was higher, post-monsoon (October–December) was moderate and pre-monsoon (January–May) was the calmest period. Direction of longshore sediment transport was southwards during pre- and post-monsoons when waves were from the south–southwest. Whereas, northwards during monsoon when the wave approach from west–southwest to west. The annual net longshore sediment transport rate estimated was about 0.65×106 m3 towards the south and the sediment budget investigation depicts the loss of 0.067×106 m3 during the study period. Highlights: WaveWatch III global wave model data at 0.5° interval were used as input to derive the nearshore wave characteristics from XBeach numerical model. The wave height during southwest monsoon (June to September) was higher, post-monsoon (October to December) was moderate and pre-monsoon (January to May) was the calmest period. Direction of longshore sediment transport was southwards during pre- and post-monsoons when waves were from the south-southwest. Whereas, northwards during monsoon when the wave approach from west-southwest to west. The annual net longshore sediment transport rate estimated was about 0.65×106 m3 towards the south, and the sediment budget investigation depicts the loss of 0.067×106 m3 during the study period. [ABSTRACT FROM AUTHOR]

Intelligent mining on working face requires reliable geological guarantee technology. Transmitted channel wave detection is an effective method to detect geological structures in working face. However, three-component channel wave field characteristics of detecting the erosion zone have not been revealed, which results in difficulty in fine imaging of scour zones. In this paper, numerical modeling and field tests were conducted. The results indicate that when seismic source is excited, the body waves propagating along the roof and floor and the channel waves propagating in the coal seam. When the channel wave propagating in the erosion zone and then produces diffraction wave which propagating along the seam behind the erosion zone, and the rest continues to propagate forward. Owing to absence of coal seam in erosion zone, transmitted channel wave is converted to S-wave on entering the erosion zone, therefore the seismic record shows the partial absence of the transmitted channel wave in Event, and the converted S-wave propagates along roof and floor of coal seam, and they are not able to form channel waves with higher energy. Besides, the Y-component of the channel wave is suitable for detecting erosion zone, because it has high amplitude and it can be easily distinguished. The attenuation imaging method based on eigenvalue limitation has high imaging resolution and good abrupt convergence. Three-component transmitted P-wave and S-wave have no obvious response to erosion zone and cannot be used as characteristic waves for the erosion zone detection. [ABSTRACT FROM AUTHOR]

Nearshore wave characteristics and its variations at Ganpatipule coast, eastern Arabian Sea, for the past 4 decades (1979–2016) have been examined. The study is based on European Centre for Medium‐Range Weather Forecasts Re‐Analysis‐Interim wave data at ~50 m water depth and the nearshore wave parameters estimated using the numerical model Simulating WAves Nearshore, executed from the Delft3D dashboard considering shallow water wave propagation, wave setup, and breaking. The littoral drift is estimated based on bulk transport formula of the Coastal Engineering Research Centre with the input from the hydrodynamic module. The model shows good agreement with wave rider buoy measured wave parameters at 14‐m water depth. Anomalies of breaker height, period, and direction vary in the range of −0.35–0.4 m, −0.80–1 s, and − 16 to 12°, respectively during the study period. A detailed analysis of monthly variations of breaker height along the study region suggests a significant increasing trend during the Asian summer monsoon, whereas a decreasing trend is identified during the nonmonsoon period. The study region accounts for a northerly net transport of 3.9 × 105 m3 yr−1 with a significant increasing trend of 1,840 m3 yr−1. The strong wind field region along the central Arabian Sea (65–70°E and 15–20°N) gives a strengthened positive correlation (r > 0.7) with the littoral drift. Impacts of Pacific climate variability on interannual and decadal timescales are observed in the littoral drift rates. Key Points: Investigates nearshore wave climate and littoral drift for past 4 decades (1979–2016) at a location in eastern Arabian SeaBreaker height shows a significant increasing trend during the Asian Summer monsoon (June‐September)An increasing trend in the net littoral drift is observed (1,840 m3 yr−1)Impact of Pacific climate variability on littoral drift is observed during 1979–1989 [ABSTRACT FROM AUTHOR]

While the propagation of stress wave generated by dynamic compaction in dry or saturated granular soil has received much coverage in the research literature, attention to situations with dry soil overlying saturated soil, or mixed-phase ground, is limited. In such cases, the compressional waves have to propagate from a dry layer above the groundwater table to saturated soil below the groundwater table. In this paper, the transient wave propagation characteristics in a mixed-phase ground with an idealized interface between the dry and saturated layer is studied. As the time domain solutions for such problems are often unavailable using analytical methods, a numerical approach based on a dual-phase coupled finite element method implemented on a commercial software platform is adopted. The wave behaviour across the interface is studied and the energy transmission and reflection mechanism from dry to saturated layer is examined. The amplitude, speed and attenuation of the compressional waves and their dependencies on the soil permeability, skeleton stiffness and load duration are quantitatively evaluated via a comprehensive parametric study. As a precursor to the numerical investigation of wave propagation in a mixed-phase ground due to dynamic compaction, the results presented in this study are likely to help in providing a better understanding of the ground improvement effect of dynamic compaction in soil involving a groundwater table. [ABSTRACT FROM AUTHOR]

Yu, M. and Du, H., 2019. Numerical analysis of long period wave characteristics in sea area based on mathematical probability and statistics. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 119–124. Coconut Creek (Florida), ISSN 0749-0208. In order to improve the numerical analysis ability of long period wave characteristics in sea area, a numerical analysis method of long period wave feature in sea area based on mathematical probability statistics is proposed. The big data statistical analysis model of long period wave feature analysis in sea area is constructed, and the feature modeling and probability density feature analysis of long period wave data in sea area are carried out by using fuzzy association rule feature mining method. Combined with the mathematical probability statistical method, the fuzzy regional clustering processing of the long period wave data in the sea area is realized, and the feature quantity of the association rules of the long period wave in the sea area is extracted. The fuzzy clustering of the long period wave in the sea area is carried out by using the fuzzy C means clustering fusion method, and the random probability density distribution characteristic quantity of the long period wave in the sea area is excavated in the data clustering center. Combined with the feature space distributed structure reorganization method, the long period wave data is reorganized in the sea area, and the transmission control and feature numerical analysis optimization of the long period wave data in the sea area are realized. The simulation results show that the numerical analysis of long period wave characteristics in sea area is accurate and the data clustering performance is better, which improves the evaluation ability of long period wave dynamic evolution in sea area. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Experimental investigations on control and shear deficient RC beams using controlled damage through actuator. • Measurements of AE signals during damage progression in RC components. • Processing of AE to arrive at the sensitive parameters which are able to detect damage in concrete. • Comparative evaluation of AE parameters from control, deficient and strengthened beams. • Application of ISA and Ib for severity and pattern of damage. Abstract Shear deficiency in reinforced concrete (RC) structures brings the vulnerability of brittle and abrupt failure to those structures, and thus, provides very little time for taking any precautionary actions. The present study focuses on the investigations on damage progression in shear deficient RC components using acoustic wave propagation technique. Three levels of shear deficiency with respect to the control beam are considered. Various acoustic parameters are considered to determine their efficacy in identifying the initiation and propagation of crack in concrete structures. Few of the acoustic parameters are identified to be very effective and able to clearly differentiate the tensile and shear cracking in concrete. Intensity characteristics, as identified in the present study, can be used to classify the type of damage (progression of shear and tensile cracks) under different stages of loading. Further, the acoustic emission monitoring technique is employed for detecting the crack initiation in strengthened beams where the critical shear deficient beam was strengthened using two layers of GFRP fabric in the shear zone. It is found that, unlike the original deficient beams, AE signals obtained from the strengthened beam clearly indicate the clear shift from shear failure to flexural failure. The present study underlines that the acoustic wave propagation technique can be effectively used to monitor the health of the reinforced concrete structures and to uniquely assess the appropriateness of any scheme(s) for strengthening of the deficient concrete structures. [ABSTRACT FROM AUTHOR]

Wave-induced Longshore Sediment Transport (LST) play an important role in the dynamics of the Dhanushkodi sandspit located southeast of Rameshwaram. The LST along the Dhanushkodi coast is studied based on data collected simultaneously in Gulf of Mannar (GoM) and Palk Bay (PB) using directional waverider buoys. The numerical model REF/DIF1 was used to calculate the nearshore waves and the LST rate was estimated using three different formulae. The model validation was done based on the measured nearshore waves using InterOcean S4DW. Numerical model LITPACK was also used for simulating non-cohesive sediment transport and the LITLINE module was used to study the shoreline evolution over 5 years. Low net annual LST along PB (~0.01 × 106 m3) compared to the GoM region (0.3 × 106 m3) were due to the weak waves. Accretion in the region led to growth of the Dhanushkodi sandspit by 65 m during the period 2010-2015.

The water wave characteristics of Bragg reflections from a train of fixed floating pontoon breakwaters was studied numerically. A numerical model of boundary discretization type was developed to calculate the wave field. The model was verified by comparing to analytical data in literature and good agreements were achieved. Series of parametric studies were conducted systematically to investigate the dependence of the reflected coefficients by the Bragg scattering on the design variables, including the spacing between the breakwaters, the total number of installed breakwaters, the draft and width do the breakwater, and wave length. Certain wave characteristics of the Bragg reflections were observed and discussed in details which might be of help for practical engineering applications in shoreline protection from incident waves.

In order to improve the numerical analysis ability of long period wave characteristics in sea area, a numerical analysis method of long period wave feature in sea area based on mathematical probability statistics is proposed. The big data statistical analysis model of long period wave feature analysis in sea area is constructed, and the feature modeling and probability density feature analysis of long period wave data in sea area are carried out by using fuzzy association rule feature mining method. Combined with the mathematical probability statistical method, the fuzzy regional clustering processing of the long period wave data in the sea area is realized, and the feature quantity of the association rules of the long period wave in the sea area is extracted. The fuzzy clustering of the long period wave in the sea area is carried out by using the fuzzy C means clustering fusion method, and the random probability density distribution characteristic quantity of the long period wave in the sea area is excavated in the data clustering center. Combined with the feature space distributed structure reorganization method, the long period wave data is reorganized in the sea area, and the transmission control and feature numerical analysis optimization of the long period wave data in the sea area are realized. The simulation results show that the numerical analysis of long period wave characteristics in sea area is accurate and the data clustering performance is better, which improves the evaluation ability of long period wave dynamic evolution in sea area. [ABSTRACT FROM AUTHOR]

Abstract The proper shape of the ship was resulting lowering shear stress that caused reduction on energy losses in the boundary layer, vortices and flow separation which prevent an increase pressure in the aftbody. Multihull had a much lower resistance components (shear stress and pressure) with the result that requires significantly less horsepower (power energy) than monohull. The total resistance of multihull not only the sum of the individual resistances of each hull. There were interactions between main hull and side hull related to stagger, clearance and speeds. This research was to investigate characteristics of pentamaran based on Michell's thin ship theory and be adjusted with the experimental on towing test for several configurations on clearance and stagger. The pentamaran with an arrow formation consist of main hull represents a hard chine recommended from Savitsky model and side with V shape, which each of two side hulls located in the same longitudinal. Changing of side hull on clearance strongly affects the resistance characteristics than stagger. The configuration of pentamaran with centerline of the main hull to each of front-side hull approximately 15o-18o could be an effective manner to reduce resistance. In general, thin ship theory from Michell to prediction coefficient component resistance of model with warp-chine yields quite good results with the experiments at Fn > 0.4. [ABSTRACT FROM AUTHOR]

Storms play a significant role in coastal zone hydrodynamics, morphodynamics and flooding. The US Northeast is influenced by both extratropical (e.g. nor'easters) and tropical cyclones, which produce extreme winds, storm surges and waves, and as a result erosion and coastal damage. In this study, simulations of 100 of the most severe historical extratropical cyclones in this region were used to evaluate a new, rapid numerical wave model that is a candidate model for ensemble forecasting and hazard assessment. The main tool used was a coupled hydrodynamic-wave model, forced by wind and pressure from preexisting meteorological reanalysis datasets. The coupled models were the Stevens institute Estuarine and Coastal Ocean hydrodynamic Model (sECOM) and the Mellor et al. (2008) (hereafter MDO) wave model, and includes several important physical interactions (e.g. wave setup). Wave model results were compared to offshore buoy observational data from 1980 to 2012, and a sensitivity analysis was used to evaluate important model parameters. Results show that the wave model is very accurate for wave height ( H s ), with an average RMSE of 0.92 m and skill ranging from 0.7 to 0.9. Results were less accurate for average wave period ( T avg ), with an average RMSE of 1.97 s and skill ranging from 0.5 to 0.7. However, a comparison with a more widely used existing rapid wave model shows a substantial improvement over those T avg results. Large waves approach the coast in Massachusetts Bay during extratropical cyclones, leading to important wave impacts including setup, and modeled storm surge is shown to have good accuracy and no bias at Boston. These results demonstrate the strengths and weaknesses of the model for rapid simulations of waves under history's most extreme extratropical cyclones, and the evaluation results and sensitivity analysis are used to suggest its appropriate uses and possible avenues of improvement. [ABSTRACT FROM AUTHOR]

Wave behavior is investigated in a piezoelectric coupled laminated fiber-reinforced composite cylindrical shell by considering the transverse shear effects and rotary inertia. A mathematical model is presented for analysis of wave propagation in a laminated fiber-reinforced composite cylindrical shell coated with the piezoelectric layer. By solving an eigenvalue problem, dispersion characteristics for different wave modes are obtained. Piezoelectric effect on dispersion curve is investigated. The effects of material properties of host substrate shell, laminate stacking sequence, and fiber orientation on dispersion curve are examined as well. In addition, a comparison of dispersion solutions from different shell theories with different axial and circumferential wave numbers and piezoelectric layer thickness is provided to illustrate the transverse shear and rotary inertia effects on wave behavior of a laminated fiber-reinforced composite shell. The results of this paper can be used for studies on wave propagation in piezoelectric coupled laminated composite shell structures and in design of smart composite shell structures with the piezoelectric material for health monitoring and dynamic stability evaluation. [ABSTRACT FROM AUTHOR]

The erosion of the world's coasts and the shortage of sand to mitigate beach erosion are leading to the increasingly common use of gravel for coastal protection and beach nourishment. Therefore, in order to determine the amount of gravel required for such actions, it is important to know perfectly the equilibrium profile of gravel beaches. However, at present, this profile is obtained from formulas obtained mainly after channel tests, and therefore most of them do not adapt to the real profiles formed by gravel beaches in nature. In this article, 31 variables related to sedimentology, waves, morphology and marine vegetation present on the beaches are studied to determine which are the most influential in the profile. From the study carried out, it is obtained that these variables are the steepness and probability of occurrence of the wave perpendicular to the coast, the profile starting slope (between MWL and − 2 m), the energy reduction coefficient due to Posidonia oceanica as well as the width of the meadow. Using these variables, different numerical models were generated to predict accurately the gravel beach profile, which will lead to a saving in the volume of material used in the order of 1300 m 3 /ml of beach with respect to current formulations, and a greater certainty that the beach nourishment carried out will have the desired effect. [ABSTRACT FROM AUTHOR]

The nearshore wave characteristics and variations in littoral drift (longshore sediment transport; LST) are estimated based on different approaches for four years along the Vengurla coast, with comparable wind-sea and swell energy assessed. The waverider buoy-measured data at 15 m water depth is utilized as the input wave parameters along with the reanalysis model data, and the numerical wave model Delft-3D is used for estimating the nearshore wave parameters. The relative contribution of wind-seas and swells on LST rates are specifically examined. The clear prevalence of west-southwest waves implies the prevalence of south to north longshore sediment transport with net transport varying from 0.19−0.37 × 105 m3/yr. LST is strongly dependent on the breaker angle and a small change in the wave direction substantially alters the LST, and hence reanalysis/model data with coarse resolutions produce large errors (~38%) in the LST estimate. The annual gross LST rate based on integral wave parameters is only 58% considering the wind-seas and swells separately, since the wind-sea energy is comparable to swell energy, and the direction of these two systems differs significantly.

This paper illustrates a methodology to get a reliable estimation of the local wave properties, based on the reconstruction of the motion of a moving sailboat by means of GNSS receivers installed on board and an original kinematic positioning approach. The wave parameters reconstruction may be used for many useful practical purposes, e.g., to improve of autopilots, for real-time control systems of ships, to analyze and improve the performance of race sailboats, and to estimate the local properties of the waves. A Class 40 oceanic vessel (ECO40) left from the port of “Riva di Traiano” located close to Rome (Italy) on 19 October 2014 to perform a non-stop sailing alone around the world in energy and food self-sufficiency. The proposed system was installed on ECO40 and the proposed method was applied to estimate the wave properties during a storm in the Western Mediterranean Sea. The results compared against two sets of hindcast data and wave buoy records demonstrated the reliability of the method.

The intense increase in offshore operational activities warrants periodical and accurate prediction of the wave characteristics. Usually, complex numerical models that require high computational power are used in this prediction. To overcome these challenges of these numerical models, in this paper, we propose the use of an ensemble of Extreme Learning Machine (Ens-ELM) to predict the daily wave height. We exploit the randomness of initialization in ELM to obtain better generalization performance. This is done by constructing an Ensemble of ELM, with the parameters of each ELM initialized in distinct regions of the input space. For each sample in the data set, the output of the ELM with the least mean square for each sample in the data set is reported as its output. We study the performance of the Ens-ELM to predict the daily wave height in 10 stations of varying terrains from Gulf of Mexico, Brazil and Korean region. The Ens-ELM network is trained using the past wave data and the measured atmospheric conditions obtained in these stations between Jan 1, 2011 and Dec 31, 2014 and is tested with data in these stations between Jan 1, 2015 and Aug 30, 2015. In this study, the performance of Ens-ELM is evaluated in comparison with ELM, Online Sequential ELM (OS-ELM), and Support Vector Regression (SVR). From this study, we infer that the Ens-ELM out performs ELM, OS-ELM and SVR in the daily wave height prediction. [ABSTRACT FROM AUTHOR]

An experimental study is conducted using a 0.152-m ID facility to investigate the wave characteristics of two-phase stratified wavy flow in horizontal pipelines. The experiments are conducted under low liquid loading condition, which is very commonly observed in wet gas pipelines. The experiments are conducted with water as the liquid phase, and repeated with 51 wt % of monoethylene glycol (MEG) in the aqueous phase to analyze the effects of MEG presence on wave characteristics. The experimental range of this study covers superficial gas velocity, vSg, values of 9-23 m/s and superficial liquid velocity, vSL, values of 0.01-0.02 m/s. Similar test matrices are completed for the cases with and without MEG in the aqueous phase. A conductivity probe system is used to measure the wave characteristics at the liquid-gas interface. These characteristics include the wave celerity, frequency, amplitude, length, and liquid film thickness. The experimental oil-air wave characteristics data of Gawas et al. (Int J Multiphase Flow. 2014;63:93-104) is also used for comparison purposes. The trends in the resulting wave characteristics with respect to input parameters are investigated, for oil, water, or MEG-water mixture as the liquid phase. Common predictive methods for interfacial wave celerity, including shallow water theory, Watson (Proceedings of the 4th International Conference in Multi-Phase Flows, Nice, France. 1989:495-512), Paras et al. (Int J Multiphase Flow. 1994;20(5):939-956), Al-Sarkhi et al. (AIChE J. 2012;58(4):1018-1029), and Gawas et al. (Int J Multiphase Flow. 2014;63:93-104) are evaluated in comparison with the experimental data. The results of the wave frequency correlation of Al-Sarkhi et al. (AIChE J. 2012;58(4):1018-1029) are also compared with the experimental wave frequency data. Lastly, a correlation is developed to predict the relative wave amplitude, as a function of superficial gas Weber number and liquid velocity number. Most of the commonly used two-phase stratified flow models are developed with the assumption of steady-state conditions, and neglect the transient wave effects. This study provides valuable experimental results on wave characteristics of stratified wavy flow for different types of liquid phase. Moreover, a comprehensive analysis of the parameters affecting the wave characteristics of stratified wavy flow is presented. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3177-3186, 2017 [ABSTRACT FROM AUTHOR]

The characteristics of elastic waves in granular assemblies of spherical particles, which translate and spin, are analyzed by a continuumnization technique. The continuumnized governing equations for equal spheres in three-dimensional lattices are first obtained, accompanied by auxiliary tensors corresponding to the macroscopic material properties. The property tensors, i.e., the stiffness, coupling, and spinning tensors, given in neat analytical form, are solely determined by the micro-mechanics (the normal and tangential spring constants) and the microstructures of the lattices (the unit vectors connecting the centers of neighboring particles). The general formulas are then applied for two types of closest packed lattices. Theoretical wave velocities for p- and s-waves in such lattices are derived, together with the frequency for the pure spin mode and the group velocity for the spin motion coupled with s-waves. Two interesting findings of the physics of lattices of spheres are revealed: the s-wave coupled with spin motion in the lattices can be understood as acoustic and optical branches of waves in the diatomic model in solid-state physics; the anisotropic closest packed lattices would degenerate into a special isotropic state with zero Poisson’s ratio and a constant velocity ratio of 2 between p- and s-waves. How the wave velocities and the anisotropy are influenced by the spring constant ratios are also analyzed. The theoretical results obtained can be used for quantitative verification and for parameter calibration of discrete-element-method simulations using spherical particles. [ABSTRACT FROM AUTHOR]