scholarly journals Long‐Term Regularity of 3D Gravity Water Waves

2021 ◽  
Author(s):  
Fan Zheng
Keyword(s):  
Water Waves ◽  
3D Gravity

Calibration of SWAN Model for Wave Simulation in Bohai Sea

2013 ◽  
Vol 423-426 ◽  
pp. 1344-1350
Author(s):  
Xiang Cui Lv ◽  
Dao Sheng Wang ◽  
De Kui Yuan ◽  
Jian Hua Tao
Keyword(s):  
Water Waves ◽  
Bohai Sea ◽  
Sensitivity Analyses ◽  
Short Term ◽  
Wave Source ◽  
The Bohai Sea ◽  
Swan Model ◽  
Wave Data ◽  
Wave Characteristics

It is necessary to obtain a further understanding of the behaviors and characteristics of water waves in the Bohai Sea for the coastal engineering construction and environment protection in this area. The SWAN (Simulating Waves Nearshore) model, a third-generation wave spectral model on the basis of wave action conservation has been applied to study the water waves in the Bohai Sea by several researchers, and encouraging results have been obtained. However, the calibrated parameter for a wave process at an individual station does not have universal applicability for other stations, which causing problems to anyalyze the wave characteristics in the Bohai Sea. Thus, in this study how to calibrate the SWAN model in the Bohai Sea was analyzed carefully in terms of five sets of short-term wave data and one set of long-term wave data at Tanggu. It was found that wind, whitecapping, bottom mechanisms of wave source function and tide current are the four main factors in the process of wave development. A set of optimized parameters suitable for both long-term and short-term wave processes in the Bohai Sea is suggested through the sensitivity analyses of these elements. Comparisons between the simulated results and the field measured data show that the validated model can provide more accurate results for both long-term and short-term simulations and can be used to study the wave characteristics in the Bohai Sea.

scholarly journals Harvest of Motion

2008 ◽  
Vol 130 (09) ◽  
pp. 56-58 ◽  
Author(s):  
Brian S. Hendrickson ◽  
Stuart B. Brown
Keyword(s):  
Energy Harvesting ◽  
Water Waves ◽  
Electric Energy ◽  
Low Frequency ◽  
Rechargeable Batteries ◽  
Small Scale ◽  
Catch And Release ◽  
Limited Life ◽  
Initial Research

This article discusses that a small-scale generator uses a catch-and-release strategy that can turn a casual stroll into useful electric energy. Many devices now require fractions of a watt continuously, often with occasional bursts of 1 to 10 W during peak activity. However, batteries occupy device volume and have limited life. Even rechargeable batteries can withstand only a finite number of charge cycles and, perhaps most important, recharging them can be inconvenient or expensive. Engineers must develop strategies to harness the abundant energy in low-frequency, time-varying motion before energy harvesting can achieve its greatest potential. Water waves, swaying and bouncing structures, and biomechanics are potential environmental energy sources that are largely out of the reach of the current vibration-inspired, motion harvesting technologies. Being able to economically convert low-speed motion to electricity will be a key to realizing practical long-term power generation for distributed devices. The Veryst energy-harvesting concept is one approach that intends to do just that. As with other energy harvesting projects, much work remains, but initial research and development suggest strong potential.

Study on Characteristics of Water Waves in Bohai Sea Using SWAN Model

2014 ◽  
Vol 522-524 ◽  
pp. 983-989
Author(s):  
Dao Sheng Wang ◽  
Xiang Cui Lv ◽  
De Kui Yuan
Keyword(s):  
Wave Height ◽  
Water Waves ◽  
Bohai Sea ◽  
Measured Data ◽  
Wave Direction ◽  
Short Term ◽  
The Bohai Sea ◽  
Good Agreement ◽  
Term Field

The SWAN (Simulating WAves Nearshore) model was applied to study the characteristics of water waves in the Bohai Sea. The model was calibrated against both short-term and long-term field measured data from six different stations in the Bohai Sea and the computational results are in good agreement with the measured data. Then the wave process during 1999 to 2009 in the Bohai Sea was simulated using the calibrated model. The wave characteristics such as significant wave height, average period, dominant wave direction and their seasonal variations were analyzed based on the simulated results. The distributions of wave height and wave period are similar to those of the previous studies, but the wave height is slightly smaller than that given by other researchers.

scholarly journals Third-order theory for multi-directional irregular waves

2012 ◽  
Vol 698 ◽  
pp. 304-334 ◽  
Author(s):  
Per A. Madsen ◽  
David R. Fuhrman
Keyword(s):  
Water Waves ◽  
Velocity Potential ◽  
Transfer Functions ◽  
Order Theory ◽  
Irregular Waves ◽  
Third Order ◽  
Finite Water Depth ◽  
Wave Trains ◽  
Harmonic Resonance

AbstractA new third-order solution for multi-directional irregular water waves in finite water depth is presented. The solution includes explicit expressions for the surface elevation, the amplitude dispersion and the vertical variation of the velocity potential. Expressions for the velocity potential at the free surface are also provided, and the formulation incorporates the effect of an ambient current with the option of specifying zero net volume flux. Harmonic resonance may occur at third order for certain combinations of frequencies and wavenumber vectors, and in this situation the perturbation theory breaks down due to singularities in the transfer functions. We analyse harmonic resonance for the case of a monochromatic short-crested wave interacting with a plane wave having a different frequency, and make long-term simulations with a high-order Boussinesq formulation in order to study the evolution of wave trains exposed to harmonic resonance.

scholarly journals An electronic device for long-term snow wetness recording

1994 ◽  
Vol 19 ◽  
pp. 104-106 ◽  
Author(s):  
A. Denoth
Keyword(s):  
Water Waves ◽  
Water Distribution ◽  
Data Transfer ◽  
Electronic Device ◽  
Measurement Data ◽  
Field Measurements ◽  
Microwave Remote Sensing ◽  
Capacitive Sensor ◽  
Snow Hydrology

Water content, water distribution and variations with time of these quantities in the natural snow cover are important parameters for microwave remote-sensing studies, snow stability investigations and snow hydrology studies. The most promising method for snow wetness determination is the measurement of the dielectric constant at radio frequencies. Recent developments of electronic devices for long-term recording of snow wetness are reported. The measurement system consists of two parts: the tuning and display unit with the battery pack and the flat capacitive sensor. The system is controlled by a built-in low-power microcomputer, the operation frequency for the sensor is 20.00 MHz. Measurement data are displayed on an LCD and are also stored in a RAM; data transfer for a PC for further data processing is possible by a built-in V24 interface. Up to four individual sensors can be operated simultaneously. Field measurements of long-term variations in snow wetness during diurnal cycles and registrations of penetrating meltwater or rain-water waves with the formation of water shock fronts are presented.

scholarly journals An electronic device for long-term snow wetness recording

1994 ◽  
Vol 19 ◽  
pp. 104-106 ◽  
Author(s):  
A. Denoth
Keyword(s):  
Water Waves ◽  
Water Distribution ◽  
Data Transfer ◽  
Electronic Device ◽  
Measurement Data ◽  
Field Measurements ◽  
Microwave Remote Sensing ◽  
Capacitive Sensor ◽  
Snow Hydrology

Water content, water distribution and variations with time of these quantities in the natural snow cover are important parameters for microwave remote-sensing studies, snow stability investigations and snow hydrology studies. The most promising method for snow wetness determination is the measurement of the dielectric constant at radio frequencies. Recent developments of electronic devices for long-term recording of snow wetness are reported. The measurement system consists of two parts: the tuning and display unit with the battery pack and the flat capacitive sensor. The system is controlled by a built-in low-power microcomputer, the operation frequency for the sensor is 20.00 MHz. Measurement data are displayed on an LCD and are also stored in a RAM; data transfer for a PC for further data processing is possible by a built-in V24 interface. Up to four individual sensors can be operated simultaneously. Field measurements of long-term variations in snow wetness during diurnal cycles and registrations of penetrating meltwater or rain-water waves with the formation of water shock fronts are presented.

scholarly journals On Determining the Onset and Strength of Breaking for Deep Water Waves. Part I: Unforced Irrotational Wave Groups

2002 ◽  
Vol 32 (9) ◽  
pp. 2541-2558 ◽  
Author(s):  
Jin-Bao Song ◽  
Michael L. Banner
Keyword(s):  
Growth Rate ◽  
Nonlinear Wave ◽  
Deep Water ◽  
Water Waves ◽  
Wave Group ◽  
Two Dimensional ◽  
Wave Groups ◽  
Average Growth ◽  
Deep Water Waves

Abstract Finding a robust threshold variable that determines the onset of breaking for deep water waves has been an elusive problem for many decades. Recent numerical studies of the unforced evolution of two-dimensional nonlinear wave trains have highlighted the complex evolution to recurrence or breaking, together with the fundamental role played by nonlinear intrawave group dynamics. In Part I of this paper the scope of two-dimensional nonlinear wave group calculations is extended by using a wave-group-following approach applied to a wider class of initial wave group geometries, with the primary goal of identifying the differences between evolution to recurrence and to breaking onset. Part II examines the additional influences of wind forcing and background shear on these evolution processes. The present investigation focuses on the long-term evolution of the maximum of the local energy density along wave groups. It contributes a more complete picture, both long-term and short-term, of the approach to breaking and identifies a dimensionless local average growth rate parameter that is associated with the mean convergence of wave-coherent energy at the wave group maximum. This diagnostic growth rate appears to have a common threshold for all routes to breaking in deep water that have been examined and provides an earlier and more decisive indicator for the onset of breaking than previously proposed breaking thresholds. The authors suggest that this growth rate may also provide an indicative measure of the strength of wave breaking events.

Therapy and prevention for mental health: What if mental diseases are mostly not brain disorders?

2019 ◽  
Vol 42 ◽  
Author(s):  
John P. A. Ioannidis
Keyword(s):  
Mental Health ◽  
Mental Disease ◽  
Brain Disorders ◽  
Social Stressors ◽  
Labor Education ◽  
Mental Diseases ◽  
Long Term Follow Up ◽  
Political Decisions

AbstractNeurobiology-based interventions for mental diseases and searches for useful biomarkers of treatment response have largely failed. Clinical trials should assess interventions related to environmental and social stressors, with long-term follow-up; social rather than biological endpoints; personalized outcomes; and suitable cluster, adaptive, and n-of-1 designs. Labor, education, financial, and other social/political decisions should be evaluated for their impacts on mental disease.

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