Timing of Wave Disturbance and the Resistance and Recovery of a Freshwater Epilithic Microalgal Community

1990 ◽  
Vol 9 (1) ◽  
pp. 54-67 ◽  
Author(s):  
Christopher G. Peterson ◽  
Kyle D. Hoagland ◽  
R. Jan Stevenson
Keyword(s):  
Wave Disturbance ◽  
Microalgal Community

scholarly journals An Underwater Quadrotor Control with Wave-disturbance Compensation by a UKF

2020 ◽  
Vol 53 (2) ◽  
pp. 9017-9022
Author(s):  
T. Ohhira ◽  
A. Kawamura ◽  
A. Shimada ◽  
T. Murakami
Keyword(s):  
Wave Disturbance ◽  
Disturbance Compensation ◽  
Quadrotor Control

Tidal excitation of hydromagnetic waves and their damping in the Earth

1994 ◽  
Vol 274 ◽  
pp. 219-241 ◽  
Author(s):  
R. R. Kerswell
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Outer Core ◽  
Decay Rates ◽  
Wave Disturbance ◽  
Instability Mechanism ◽  
The Earth ◽  
Elliptical Instability ◽  
Hydromagnetic Waves

We examine the possibility that the Earth's outer core, as a tidally distorted fluid-filled rotating spheroid, may be the seat of an elliptical instability. The instability mechanism is described within the framework of a simple Earth-like model. The preferred forms of wave disturbance are explored and a likely growth rate supremum deduced. Estimates are made of the Ohmic and viscous decay rates of such hydromagnetic waves in the outer core. Rather than a conclusive disparity of scales, we find that typical elliptical growth rates, Ohmic decay rates and viscous decay rates all have the same order for plausible core fields and core-to-mantle conductivities. This study is all the more timely considering the recent realization that the Earth's precession may also drive similar instabilities at comparable strengths in the outer core.

scholarly journals Dynamics of microalgal communities in the water-column/sediment interface of the inner shelf off Parana State, Southern Brazil

2004 ◽  
Vol 52 (3-4) ◽  
pp. 183-194 ◽  
Author(s):  
Ricardo Luiz Queiroz ◽  
Frederico Pereira Brandini ◽  
Franciane Maria Pellizzari
Keyword(s):  
Water Column ◽  
Cyanobacterial Bloom ◽  
Interface Layer ◽  
Benthic Diatoms ◽  
Southern Brazil ◽  
Planktonic Diatoms ◽  
Cell Densities ◽  
Sediment Interface ◽  
Microalgal Community

The composition and biomass of the microalgal community at the water-column/sediment interface on the continental shelf off Parana State (Brazil) were studied every 2 months during 1999. Samples for cell identification and determination of chlorophyll a were taken from the interface layer and at discrete depths up to 4 m above the sediment. Results showed a community mainly formed by benthic and planktonic diatoms >30 µm, benthic diatoms <30 µm and cyanobacteria. Cell densities were generally higher at the interface layer. Resuspension and sedimentation events seemed to be a paramount factor regulating the composition and biomass of these communities, and affected differently cells of different size classes. Cells >30 µm, which accounted for most of the pigment biomass, were resuspended from the interface after turbulent periods, and may take advantage of calm periods to stay and grow at the interface. Small benthic diatoms were more susceptible to wind-induced turbulence occurring in higher densities in the water column just above the water-sediment interface. A cyanobacterial bloom (Trichodesmiun) was observed at these bottom layers in the spring-summer periods.

scholarly journals Minor Structures for the Improvement of Wave Disturbance in a Small Harbor

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
A. Sulis
Keyword(s):  
Boussinesq Equations ◽  
Wave Disturbance ◽  
Comprehensive Description ◽  
New Energy ◽  
Efficient Alternative ◽  
Operational Activities ◽  
Traditional Structures ◽  
Energy Absorbing ◽  
Incident Waves ◽  
Large Research

A very important aspect in the planning, design, and maintenance of a harbor is to determine the response of the harbor basin to incident waves. The Saras harbor in South Sardinia (Italy) has been experiencing significant wave disturbance that affects the safety of mooring and operational activities. In the framework of a large research, this paper summarises a comprehensive description of new energy absorbing structures that can be seen as an efficient alternative to more traditional structures when limited by economic or technical constraints. Specifically, the paper presents the results of a graphical preliminary approach and a numerical modelling that solves the enhanced Boussinesq equations in two horizontal dimensions.

Influence of Water Surface Wave Disturbance on Wireless Optical Communication

2021 ◽  
Vol 41 (7) ◽  
pp. 0706005
Author(s):  
李军 Li Jun ◽  
罗江华 Luo Jianghua ◽  
元秀华 Yuan Xiuhua
Keyword(s):  
Surface Wave ◽  
Optical Communication ◽  
Water Surface ◽  
Wave Disturbance ◽  
Wireless Optical Communication ◽  
Influence Of Water

Nonlinear Wave Disturbance Around a Vertical Circular Column

2002 ◽  
Author(s):  
C. T. Stansberg ◽  
H. Braaten
Keyword(s):  
Linear Prediction ◽  
Harmonic Component ◽  
Nonlinear Effects ◽  
Second Order ◽  
Wave Disturbance ◽  
Difference Frequency ◽  
Irregular Waves ◽  
Order Effects ◽  
Sum Frequency ◽  
Circular Column

The wave disturbance close to vertical columns is analysed. In particular, the deviations from linear predictions are investigated, by experimental as well as by numerical methods. Thus a second-order numerical diffraction model is established by means of a diffraction analysis code (WAMIT) and compared to model tests with a single, fixed column with diameter 16m. Tests in regular, bi-chromatic as well as irregular waves are run. Significant nonlinear effects are observed, especially in steep waves, with the maximum elevation in front of the column increasing from 11.5m in a linear prediction to around 19m, in a 12s regular wave with 22m wave height. The main nonlinear effects in front of the column are identified as second-order sum-frequency and difference-frequency terms, plus a significant nonlinear increase in the first harmonic component. The WAMIT prediction of the second-order effects agrees fairly well with the measurements, although with some overprediction and underprediction, respectively, of the sum-frequency and difference-frequency (LF and mean set-up) terms in the steepest waves. For the underprediction of the first harmonic, however, a theory beyond second order is required.

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