scholarly journals Field Observations of Breaking of Dominant Surface Waves

2021 ◽  
Vol 13 (16) ◽  
pp. 3321
Author(s):  
Pavel D. Pivaev ◽  
Vladimir N. Kudryavtsev ◽  
Aleksandr E. Korinenko ◽  
Vladimir V. Malinovsky
Keyword(s):  
Surface Waves ◽  
Strong Dependence ◽  
Field Observations ◽  
Whitecap Coverage ◽  
Dissipation Term ◽  
Video Recordings ◽  
Research Platform ◽  
Oceanographic Research ◽  
Equilibrium Range ◽  
Semi Empirical

The results of field observations of breaking of surface spectral peak waves, taken from an oceanographic research platform, are presented. Whitecaps generated by breaking surface waves were detected using video recordings of the sea surface, accompanied by co-located measurements of waves and wind velocity. Whitecaps were separated according to the speed of their movement, c, and then described in terms of spectral distributions of their areas and lengths over c. The contribution of dominant waves to the whitecap coverage varies with the wave age and attains more than 50% when seas are young. As found, the whitecap coverage and the total length of whitecaps generated by dominant waves exhibit strong dependence on the dominant wave steepness, ϵp, the former being proportional to ϵp6. This result supports a parameterization of the dissipation term, used in the WAM model. A semi-empirical model of the whitecap coverage, where contributions of breaking of dominant and equilibrium range waves are separated, is suggested.

Wave Breaking Dissipation in a Young Wind Sea

2014 ◽  
Vol 44 (1) ◽  
pp. 104-127 ◽  
Author(s):  
Michael Schwendeman ◽  
Jim Thomson ◽  
Johannes R. Gemmrich
Keyword(s):  
Wind Waves ◽  
Phase Speed ◽  
Field Studies ◽  
Turbulent Energy ◽  
Strength Parameter ◽  
Video Recordings ◽  
Sonar System ◽  
Wind Sea ◽  
Equilibrium Range

Abstract Coupled in situ and remote sensing measurements of young, strongly forced wind waves are applied to assess the role of breaking in an evolving wave field. In situ measurements of turbulent energy dissipation from wave-following Surface Wave Instrument Float with Tracking (SWIFT) drifters and a tethered acoustic Doppler sonar system are consistent with wave evolution and wind input (as estimated using the radiative transfer equation). The Phillips breaking crest distribution Λ(c) is calculated using stabilized shipboard video recordings and the Fourier-based method of Thomson and Jessup, with minor modifications. The resulting Λ(c) are unimodal distributions centered around half of the phase speed of the dominant waves, consistent with several recent studies. Breaking rates from Λ(c) increase with slope, similar to in situ dissipation. However, comparison of the breaking rate estimates from the shipboard video recordings with the SWIFT video recordings show that the breaking rate is likely underestimated in the shipboard video when wave conditions are calmer and breaking crests are small. The breaking strength parameter b is calculated by comparison of the fifth moment of Λ(c) with the measured dissipation rates. Neglecting recordings with inconsistent breaking rates, the resulting b data do not display any clear trends and are in the range of other reported values. The Λ(c) distributions are compared with the Phillips equilibrium range prediction and previous laboratory and field studies, leading to the identification of several inconsistencies.

Observation-Consistent Input and Whitecapping Dissipation in a Model for Wind-Generated Surface Waves: Description and Simple Calculations

2012 ◽  
Vol 29 (9) ◽  
pp. 1329-1346 ◽  
Author(s):  
W. Erick Rogers ◽  
Alexander V. Babanin ◽  
David W. Wang
Keyword(s):  
Surface Waves ◽  
Nonlinear Behavior ◽  
Forthcoming Paper ◽  
Relative Reduction ◽  
Strong Wind ◽  
Dissipation Term ◽  
South Wales ◽  
Spectral Models ◽  
Favorable Evaluation ◽  
Wind Input

Abstract A new wind-input and wind-breaking dissipation for phase-averaged spectral models of wind-generated surface waves is presented. Both are based on recent field observations in Lake George, New South Wales, Australia, at moderate-to-strong wind-wave conditions. The respective parameterizations are built on quantitative measurements and incorporate new observed physical features, which until very recently were missing in source terms employed in operational models. Two novel features of the wind-input source function are those that account for the effects of full airflow separation (and therefore relative reduction of the input at strong wind forcing) and for nonlinear behavior of this term. The breaking term also incorporates two new features evident from observational studies; the dissipation consists of two parts—a strictly local dissipation term and a cumulative term—and there is a threshold for wave breaking, below which no breaking occurs. Four variants of the dissipation term are selected for evaluation, with minimal calibration to each. These four models are evaluated using simple calculations herein. Results are generally favorable. Evaluation for more complex situations will be addressed in a forthcoming paper.

New ways of measuring intake, efficiency and behaviour of grazing livestock

2014 ◽  
Vol 54 (10) ◽  
pp. 1796 ◽  
Author(s):  
Paul L. Greenwood ◽  
Philip Valencia ◽  
Leslie Overs ◽  
David R. Paull ◽  
Ian W. Purvis
Keyword(s):  
Feed Efficiency ◽  
Genetic Parameter ◽  
Livestock Management ◽  
Benchmark Data ◽  
Video Recordings ◽  
Research Platform ◽  
Novel Method ◽  
High Degree ◽  
Grazing Livestock

Wireless sensor networks (WSN) offer a novel method for measuring important livestock phenotypes in commercial grazing environments. This information can then be used to inform genetic parameter estimation and improve precision livestock management. Arguably, these technologies are well suited for such tasks due to their small, non-intrusive form, which does not constrain the animals from expressing the genetic drivers for traits of interest. There are many technical challenges to be met in developing WSN technologies that can function on animals in commercial grazing environments. This paper discusses the challenges of the software development required for the collection of data from multiple types of sensors, the management and analyses of the very large volumes of data, determination of which sensing modalities are sufficient and/or necessary, and the management of the constrained power source. Assuming such challenges can be met however, validation of the sensor accuracy against benchmark data for specific traits must be performed before such a sensor can be confidently adopted. To achieve this, a pasture intake research platform is being established to provide detailed estimates of pasture intake by individual animals through chemical markers and biomass disappearance, augmented with highly annotated video recordings of animal behaviours. This provides a benchmark against which any novel sensor can be validated, with a high degree of flexibility to allow experiments to be designed and conducted under continually differing environmental conditions. This paper also discusses issues underlying the need for new and novel phenotyping methods and in the establishment of the WSN and pasture intake research platforms to enable prediction of feed intake and feed efficiency of individual grazing animals.

scholarly journals Disturbed vertical E×B plasma drifts in the equatorial F2 region at solar minimum deduced from observed NmF2 and hmF2 variations

1996 ◽  
Vol 14 (7) ◽  
pp. 733-743 ◽  
Author(s):  
A. V. Mikhailov ◽  
M. Förster ◽  
T. Y. Leschinskaya
Keyword(s):  
Magnetic Field ◽  
Theoretical Model ◽  
Electric Field ◽  
Solar Minimum ◽  
Strong Dependence ◽  
Field Observations ◽  
Model Calculations ◽  
Equatorial Station ◽  
Plasma Drift ◽  
Model Predictions

Abstract. Ground-based ionosonde and magnetic-field observations on the equatorial station Huancayo, ESRO4 neutral-composition measurements, and theoretical model calculations were used to analyze disturbed E×B vertical plasma drift during the phase of solar minimum in 1973. Vertical drifts calculated for disturbed days do not show the systematic decrease often mentioned in publications, and demonstrate strong dependence on IMF-Bz changes. It is confirmed with the help of our drift calculations that Bz turnings to a northward direction result in a decrease (up to reversal) of normal Sq (eastward during daytime and westward at nighttime) in the zonal component of electric field. Southward Bz excursions enhance normal Ey both in daytime and nighttime hours. Model predictions of Ey\\'s reaction to IMF-Bz changes are discussed.

Fuel Optimal Controller for Hydrostatic Drives: A Simulation Study and Model Validation

2014 ◽  
Author(s):  
Joni Backas ◽  
Reza Ghabcheloo ◽  
Mika Hyvönen ◽  
Kalevi Huhtala
Keyword(s):  
Fuel Economy ◽  
High Efficiency ◽  
Fuel Efficiency ◽  
Optimal Controller ◽  
Hydraulic Pump ◽  
Research Platform ◽  
Variable Displacement ◽  
Semi Empirical ◽  
The Hill ◽  
Mobile Machine

This paper presents an optimal controller for fuel efficiency of a hydraulic mobile machine with hydrostatic drive (HSD). The solution is validated using a semi-empirical simulated research platform. The drive transmission of the machine includes one variable displacement hydraulic pump and four two-speed hub motors. There is no energy storage installed. Thus, the structure of the HSD and presented improvements in fuel economy are comparable to traditional machines. The optimal controller is compared to a baseline controller that intuitively keeps the components at their high efficiency regions. In simulated hill tests, fuel economy was improved by up to 25.9 % depending on the slope of the hill and velocity reference.

scholarly journals Field Observations of Directional Spectra in Coastal Region using Ocean Research Platform

1992 ◽  
Vol 1992 (171) ◽  
pp. 501-509
Author(s):  
Wataru Koterayama ◽  
Akira Sasaki ◽  
Kenji Marubayashi ◽  
Michiyoshi Ishibashi
Keyword(s):  
Coastal Region ◽  
Field Observations ◽  
Research Platform

scholarly journals FILM DOKUMENTER EKSISTENSI TARIAN DAN KESENIAN SAKRAL WAYANG WONG DESA ADAT SIDAN

2019 ◽  
Vol 5 (02) ◽  
pp. 251-264
Author(s):  
I Nyoman Anom Fajaraditya Setiawan ◽  
I Nyoman Widhi Adnyana ◽  
Komang Redy Winatha ◽  
I Nyoman Yoga Trisemarawima
Keyword(s):  
Data Collection ◽  
Qualitative Method ◽  
Documentary Film ◽  
Local Community ◽  
Observation Data ◽  
Field Observations ◽  
Digital Documents ◽  
Video Recordings ◽  
The Arts

AbstrakSeni pertunjukan wayang wong adalah salah satu kesenian di Bali dan masih ditarikan di daerah desa tradisional Sidan, Kecamatan Petang, Kabupaten Badung, Bali. Kesenian wayang wong ini menjadi menarik, karena merupakan salah satu kesenian yang dianggap sakral oleh masyarakat setempat. Tetapi di Desa Sidan, wayang wong hanya ditarikan saat upacara keagamaan khusus. Pada prosesi sebelum pertunjukan ditarikan oleh masyarakat setempat, dilakukan ritual khusus pada para penari. Pengamatan lapangan tidak ditemukan adanya dokumentasi dalam bentuk apapun yang mengacu pada rangkaian acara tersebut, termasuk foto ataupun rekaman video. Berdasarkan wawancara dengan kelompok penari, regenerasi dilakukan dari generasi ke generasi secara langsung. Tidak adanya dokumen fisik atau digital, memotivasi tindak lanjut untuk mengeksplorasi fenomena kesenian ini. Metode kualitatif melalui pengumpulan data observasi tempat rangkaian prosesi kesenian wayang wong dan wawancara dilakukan pada anggota penari serta pimpinan desa adat yang mengetahui eksistensi kesenian ini. Kemudian dikomparasikan dengan proses perancangan video, sehingga didapatkan rangkaian cerita dalam bentuk film dokumenter. Finalisasi film dokumenter kemudian didelegasikan secara langsung pada masyarakat setempat, sehingga dapat digunakan sebagai acuan kajian lebih lanjut oleh para akademisi ataupun praktisi seni. Hal ini bertujuan untuk melestarikan kesenian wayang wong sakral yang telah langka di Bali. Kata Kunci: film, dokumenter, tari, wayang wong, Bali AbstractWayang wong performance art is one of the arts in Bali and is still danced in the traditional village area of Sidan, Petang District, Badung Regency, Bali. Wayang wong art is interesting because it is one of the arts that are considered sacred by the local community. But in Sidan Village, wayang wong is only danced during special religious ceremonies. In the procession, before the performance was danced by the local community, a special ritual was performed for the dancers. Field observations were not found in any form of documentation that refers to the series of events, including photographs or video recordings. Based on interviews with dancer groups, regeneration is carried out from generation to generation directly. The absence of physical or digital documents motivates follow-up to explore this artistic phenomenon. The qualitative method was through observation data collection where a series of wayang wong art processions and interviews were conducted with dancers and traditional village leaders who knew the existence of this art. Then it is compared with the video design process so that a series of stories is obtained in the form of a documentary film. The finalization of the documentary was then delegated directly to the local community so that it could be used as a reference for further studies by academics or arts practitioners. It aims to preserve the art of the sacred wayang wong which has been rare in Bali. Keywords: film, documentary, dance, wayang wong, Bali

Host detection and rate of parasitism by Acroricnus seductor (Hymenoptera: Ichneumonidae), a natural enemy of mud-dauber wasps (Hymenoptera: Sphecidae)

2011 ◽  
Vol 61 (1) ◽  
pp. 57-73 ◽  
Author(s):  
Matteo Federici ◽  
Jesús Selfa ◽  
Francesco Andrietti ◽  
Pablo Mendiola ◽  
Carlo Polidori
Keyword(s):  
Natural Enemy ◽  
Behavioural Ecology ◽  
Brood Cell ◽  
Field Observations ◽  
Suitable Host ◽  
Host Nest ◽  
Video Recordings ◽  
Significant Difference ◽  
Host Detection ◽  
Behavioural Sequence

AbstractThe behavioural ecology of ichneumonid wasps that attack aculeate Hymenoptera is still largely unknown. Field observations and morphological analyses were devoted to investigate host detection and rate of parasitism by Acroricnus seductor (Scopoli), a natural enemy of the black and yellow mud dauber wasp Sceliphron caementarium (Drury). At the study site, about half of the host nests suffered parasitism by A. seductor. No significant difference was found between the rate of parasitism in sheltered (inside human building) and unsheltered (outside building) nests. Larger nests did not suffer a higher rate of parasitism, and larger brood cells were not more likely to be parasitized. As revealed by contents of parasitized cells, A. seductor appeared to act as a kleptoparasitoid, devouring spider prey and young host larvae. Analysis of video recordings obtained in the field revealed the basic behavioural sequence of host detection. Acroricnus seductor female taps with the antennae the host nest surface and, once a suitable host brood cell is found, inserts the ovipositor through the mud wall, possibly facilitated by the secretion of a mud-softening substance. Behavioural data, together with the presence of modified tips on the apex of female antennae and the relative thicknesses of female fore tibiae, strongly suggest that A. seductor uses echolocation to detect the host.

Numerical Modeling of Fetch-Limited Waves in the Gulf of Tehuantepec

2010 ◽  
Vol 40 (3) ◽  
pp. 466-486 ◽  
Author(s):  
Leonel Romero ◽  
W. Kendall Melville
Keyword(s):  
Degree Of Saturation ◽  
Wave Energy Dissipation ◽  
Dissipation Term ◽  
Resonant Interactions ◽  
Wave Measurements ◽  
Gulf Of Tehuantepec ◽  
Wind Input ◽  
Equilibrium Range ◽  
Nonlinear Energy ◽  
Rms Errors

Abstract During the Gulf of Tehuantepec Experiment (GOTEX), conducted in February 2004, surface-wave measurements were collected using a scanning lidar [Airborne Topographic Mapper (ATM)] on the National Science Foundation (NSF)/NCAR C-130 aircraft during fetch-limited conditions with winds speeds ranging from 10 to 25 m s−1. The authors present direct comparisons between the observed evolution of the wave field and numerical simulations using a parameterization of the wave energy dissipation. For low and intermediate wavenumbers, the dissipation corresponds to the saturation-based parameterization by Alves and Banner. However, at higher wavenumbers, their formulation cannot maintain saturation of the spectrum. Here, the authors use a dissipation term that forces the spectrum to match the empirical degree of saturation and explicitly balances the wind input and the nonlinear energy fluxes. All model simulations were carried out with “exact” computations of the nonlinear energy transfer because of four-wave resonant interactions and two empirical wind input functions. There is a good agreement for the integral parameters between the observations and the simulations, with root-mean-square (rms) errors between 5% and 12%. The tail of the computed omnidirectional wavenumber spectrum ϕ(k) can be approximated by two ranges: an equilibrium range, where ϕ ∝ k−5/2, and a saturation range, where ϕ = Bk−3, where B is the empirically determined degree of saturation. However, within the equilibrium range, the modeled ϕ overestimates the energy with rms errors between 20% and 50%, and the computed spectra are found to be narrower than the observations by about 10°. Similarly, the modeled bimodal directional distributions, at wavenumbers higher than the spectral peak, exhibit lobe separations and amplitudes that are consistently smaller than the observations. The lobe separation of the bimodal directional distribution for all simulations approximately scales with the square root of the wave age, which is consistent with the observations. The reasons for differences between the measurements and the simulations are discussed.

Sign in / Sign up

Export Citation Format

Share Document