scholarly journals Waveguide efficient directional coupling and decoupling via an integrated plasmonic nanoantenna

2021 ◽  
Author(s):  
Valentina KRACHMALNICOFF ◽  
Guillaume Blanquer ◽  
Vivien Loo ◽  
Nancy Rahbany ◽  
Christophe Couteau ◽  
...  
Keyword(s):  
Directional Coupling

scholarly journals Wave Directions in a Narrow Bay

2010 ◽  
Vol 40 (1) ◽  
pp. 155-169 ◽  
Author(s):  
Heidi Pettersson ◽  
Kimmo K. Kahma ◽  
Laura Tuomi
Keyword(s):  
Wave Model ◽  
Wave Climate ◽  
Spectral Peak ◽  
Step Size ◽  
Weakly Nonlinear ◽  
Spectral Wave Model ◽  
Directional Coupling ◽  
Directional Wave ◽  
The Baltic ◽  
The Waves

Abstract In slanting fetch conditions the direction of actively growing waves is strongly controlled by the fetch geometry. The effect was found to be pronounced in the long and narrow Gulf of Finland in the Baltic Sea, where it significantly modifies the directional wave climate. Three models with different assumptions on the directional coupling between the wave components were used to analyze the physics responsible for the directional behavior of the waves in the gulf. The directionally decoupled model produced the direction at the spectral peak correctly when the slanting fetch geometry was narrow but gave a weaker steering than observed when the fetch geometry was broader. The method of Donelan estimated well the direction at the spectral peak in well-defined slanting fetch conditions, but overestimated the longer fetch components during wave growth from a more complex shoreline. Neither the decoupled nor the Donelan model reproduced the observed shifting of direction with the frequency. The performance of the third-generation spectral wave model (WAM) in estimating the wave directions was strongly dependent on the grid resolution of the model. The dominant wave directions were estimated satisfactorily when the grid-step size was dropped to 5 km in the gulf, which is 70 km in its narrowest part. A mechanism based on the weakly nonlinear interactions is proposed to explain the strong steering effect in slanting fetch conditions.

scholarly journals Blue-shifted contra-directional coupling between a periodic and conventional dielectric waveguides

2010 ◽  
Vol 18 (9) ◽  
pp. 9341 ◽  
Author(s):  
Linfang Shen ◽  
Xudong Chen ◽  
Xufeng Zhang ◽  
Li Pan
Keyword(s):  
Dielectric Waveguides ◽  
Directional Coupling

scholarly journals Assessing the impact of hydrodynamics on large-scale flood wave propagation – a case study for the Amazon Basin

2017 ◽  
Vol 21 (1) ◽  
pp. 117-132 ◽  
Author(s):  
Jannis M. Hoch ◽  
Arjen V. Haag ◽  
Arthur van Dam ◽  
Hessel C. Winsemius ◽  
Ludovicus P. H. van Beek ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Hydrodynamic Model ◽  
Large Scale ◽  
Hydrologic Model ◽  
Flood Events ◽  
Coupled Models ◽  
Validation Parameters ◽  
Directional Coupling ◽  
Inundation Extent ◽  
The Impact

Abstract. Large-scale flood events often show spatial correlation in neighbouring basins, and thus can affect adjacent basins simultaneously, as well as result in superposition of different flood peaks. Such flood events therefore need to be addressed with large-scale modelling approaches to capture these processes. Many approaches currently in place are based on either a hydrologic or a hydrodynamic model. However, the resulting lack of interaction between hydrology and hydrodynamics, for instance, by implementing groundwater infiltration on inundated floodplains, can hamper modelled inundation and discharge results where such interactions are important. In this study, the global hydrologic model PCR-GLOBWB at 30 arcmin spatial resolution was one-directionally and spatially coupled with the hydrodynamic model Delft 3D Flexible Mesh (FM) for the Amazon River basin at a grid-by-grid basis and at a daily time step. The use of a flexible unstructured mesh allows for fine-scale representation of channels and floodplains, while preserving a coarser spatial resolution for less flood-prone areas, thus not unnecessarily increasing computational costs. In addition, we assessed the difference between a 1-D channel/2-D floodplain and a 2-D schematization in Delft 3D FM. Validating modelled discharge results shows that coupling PCR-GLOBWB to a hydrodynamic routing scheme generally increases model performance compared to using a hydrodynamic or hydrologic model only for all validation parameters applied. Closer examination shows that the 1-D/2-D schematization outperforms 2-D for r2 and root mean square error (RMSE) whilst having a lower Kling–Gupta efficiency (KGE). We also found that spatial coupling has the significant advantage of a better representation of inundation at smaller streams throughout the model domain. A validation of simulated inundation extent revealed that only those set-ups incorporating 1-D channels are capable of representing inundations for reaches below the spatial resolution of the 2-D mesh. Implementing 1-D channels is therefore particularly of advantage for large-scale inundation models, as they are often built upon remotely sensed surface elevation data which often enclose a strong vertical bias, hampering downstream connectivity. Since only a one-directional coupling approach was tested, and therefore important feedback processes are not incorporated, simulated discharge and inundation extent for both coupled set-ups is generally overpredicted. Hence, it will be the subsequent step to extend it to a two-directional coupling scheme to obtain a closed feedback loop between hydrologic and hydrodynamic processes. The current findings demonstrating the potential of one-directionally and spatially coupled models to obtain improved discharge estimates form an important step towards a large-scale inundation model with a full dynamic coupling between hydrology and hydrodynamics.

On Magnetostrictive Transducer Applications

1999 ◽  
Vol 604 ◽  
Author(s):  
Alison B. Flatau ◽  
Marcelo J. Dapino ◽  
Frederick T. Calkins
Keyword(s):  
Acoustic Waves ◽  
Smart Structure ◽  
Sensors And Actuators ◽  
Figures Of Merit ◽  
Magnetostrictive Materials ◽  
Giant Magnetostrictive Materials ◽  
Directional Coupling ◽  
Magnetostrictive Sensor ◽  
Target Characteristics ◽  
Magnetostrictive Transducer

AbstractThis paper provides an overview of magnetostrictive transducer technology. The bi-directional coupling between the magnetic and mechanical states of a magnetostrictive material provides a transduction mechanism that can be used both for actuation and sensing. The current interest in design of adaptive smart structures, coupled with the advent of materials that exhibit high sensor figures of merit, such as Metglas and giant magnetostrictive materials such as Terfenol-D has lead to a renewed interest in the engineering of optimized magnetostrictive transducer designs. A survey of recent applications for giant magnetostrictive materials as both sensors and actuators and their use in smart structure applications will be presented along with a brief discussion of some pertinent device design issues. Examples of magnetostrictive actuation used to produce displacements, force and acoustic waves are summarized. Magnetostrictive sensor configurations that measure motion, stress or force, torque, magnetic fields and target characteristics are discussed. A very brief look at transducer modeling and experimental results is included and schematics of a number of actuator and sensor configurations are presented.

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