Electrical wave transmission in healthy black pine seedlings

Non-injurious local stimuli, such as a cold shock, and injurious stimuli, such as local burning, punctures or chemicals, were applied to study electrical wave transmission in black pine (Pinus thunbergii) seedlings. The results showed that non-injurious stimuli evoked the action potential (AP) transmission and injurious stimulation induced both AP transmission and the more complex variation (VP) transmission in the seedlings. The causes of these phenomena were discussed. Key words Black pine - Pinus thunbergii - Action potential (AP) - Variation potential (VP) - Electrical wave transmission CLC number S791.256 Document code A Foundation item: This paper was supported by the National Nature Science Foundation of China (grant No. 39670613).Biography: GUO Jian (1971-), male, lecturer in Haikou Bureau of Forestry. Hainan, P. R. China.Responsible editor: Song Funan

Experimental Research on Wave Transmission over Submerged Rubble-Mound Breakwaters

This paper discusses some previous, and presents some new experimental results on wave transmission over submerged breakwaters. The objective of this study is to evaluate wave transmission coefficient and develop a two-dimensional （2D） model as an improvement to the existing wave transmission coefficient models. Factors which affect wave transmission over stbmerged breakwaters are discussed through a series of laboratory experiments. Basic recommendations for evaluation and design of submerged rubble-monud breakwaters are presented. From the test results, a calculation formula of wave transmission coefficient is proposed.

Discussion on Wave Transmission Coefficient Formulae of Submerged Breakwaters

Fifteen formulae of wave transmission coefficient for submerged breakwaters obtained during last 3 decades are presented, compared, and analyzed in this paper. The dimensionless parameters mainly involved in this discussion are the relative submerged depth Re/h, relative wave height Rc/Hi, relative rubble size B/D50, relative breakwater width B√ HiL0 and wave breaker index ξ. It indicates that there exist notable differences among the computed results, which mainly originate from the limited experimental conditions and different analytical methods, even though the major tendency keeps similar. It is necessary to conduct more systematic studies to obtain better understanding about the mechanism of wave transmission over submerged breakwaters.

Approximate Calculation of Oblique Wave Transmission from A Single-Row of Rectangular Piles

Transmissions of oblique incident wave from a row of rectangular piles are analyzed theoretically. The incident angle of plane wave is taken as g = 90° , there then is the transmission coefficient ｜T｜ = 1 （This is a paradox）. In this paper, by means of the approximate relation between the transmitted and incident wave angle found from the shape of a slit, the paradoxical phenomenon is removed. On the basis of the continuality of the pressure and flux and the analysis of flow resistance at the row of rectangular piles, formulas of reflection and transmission coefficients are obtained. The transmission and reflection coefficients predicted by the present model quite agree with those of laboratory experiments in previous references

Fano resonance and wave transmission through a chain structure with an isolated ring composed of defects

We consider a discrete model that describes a linear chain of particles coupled to an isolated ring composed of N defects. This simple system can be regarded as a generalization of the familiar Fano Anderson model. It can be used to model discrete networks of coupled defect modes in photonic crystals and simple waveguide arrays in two-dimensional lattices. The analytical result of the transmission coefficient is obtained, along with the conditions for perfect reflections and transmissions due to either destructive or constructive interferences. Using a simple example, we further investigate the relationship between the resonant frequencies and the number of defects N, and study how to affect the numbers of perfect reflections and transmissions. In addition, we demonstrate how these resonance transmissions and refections can be tuned by one nonlinear defect of the network that possesses a nonlinear Kerr-like response.

Reflection and Transmission of Regular Waves from/Through Single and Double Perforated Thin Walls

In this paper, reflection and transmission coefficients of regular waves from/through perforated thin walls are investigated. Small scale laboratory tests have been performed in a wave flume firstly with single perforated thin Plexiglas plates of various porosities. The plate is placed perpendicular to the flume with the height from the flume bottom to the position above water surface. With this thin wall in the flume wave overtopping is prohibited and incident waves are able to transmit. The porosities of the walls are achieved by perforating the plates with circular holes. Model settings with double perforated walls parallel to each other forming so called chamber system, have been also examined. Several parameters have been used for correlating the laboratory tests’ results. Experimental data are also compared with results from the numerical model by applying the multi-domain boundary element method （MDBEM） with linear wave theory. Wave energy dissipation due to the perforations of the thin wall has been represented by a simple yet effective porosity parameter in the model. The numerical model with the MDBEM has been further validated against the previously published data.

The influence of perforated plates on wave transmission and hydrodynamic performance of pontoon floating breakwater

In this study, a perforated pontoon floating breakwater（FB） consisting of an impermeable plate and a perforated plate was designed to untangle the effect of a perforated plate on wave transmission and hydrodynamic performance of floating breakwater. A series of 2-D physical model experiments were conducted to measure the wave transmission coefficient, tension acting on the mooring line, and motion response of FB under a regular wave. The experimental results of the motion responses and mooring lines indicated that the new perforated plate was evidently effective. Furthermore, the study also discussed and analyzed the influence of the perforated plate on transmission coefficients. The experimental results showed that the new perforated plate did not lead to obvious improvement in the transmission performance

WAVE TRANSMISSION AND REFIECTION DUE TO A THIN VERTICAL BARRIER

WT5”BZ]A numerical method, the boundary fitted coordinate method (BFC), was used to investigate the transmission and reflection of water waves due to a rigid thin vertical barrier descending from the water surface to a depth, i.e., a curtain-wall type breakwater. A comparison between the present computed results and previous experimental and analytical results was carried out which verifies the prediction of the BFC method. Wave transmission and reflection due to the barrier were computed, and the transmission and refiection coefficients were given in a figure. [WT5”HZ]

Modelling of wave transmission through a pneumatic breakwater

A theoretical approach is derived to study interaction of linear water waves with an air bubble curtain used as a pneumatic breakwater. Modelling of wave transmission through an aerial barrier is a complex task due to a need to cover processes associated with wave-current interaction, effects of two-phase flows, wave damping, etc.. An initial boundary-value problem is solved by applying an efficient eigenfunction expansion method and a time-stepping procedure. The derived semi-analytical solution is used to study the effect of basic parameters of the model on wave dissipative properties of the pneumatic breakwater. Results show that wave damping by the breakwater is mainly affected by an air flow rate. The increased air discharge results in higher velocities of ascending bubbles and increases aerial barrier width. This leads to a substantial reduction of transmitted wave heights, especially for waves of intermediate length and short waves. In order to verify the applicability of the presented theoretical approach, laboratory experiments are conducted in a wave flume for different wave regimes and pneumatic breakwater characteristics. The analysis of a wave trans- mission coefficient calculated numerically and measured in the laboratory confirms that the derived model can be used for a certain range of wave conditions.

Long Wave Reflection and Transmission over A Sloping Step

This investigation examines long wave reflection and transmission induced by a sloping step. Bellman and Kalaba's (1959) invariant imbedding is introduced to find wave reflection. An alternative method matching both the surface elevation and its surface slope of each region at the junction is applied to the determination of wave reflection and transmission. The proposed methods are compared with the accurate numerical results of Porter and Porter (2000) and those of Mei (1983) for a vertical step. The wave reflection obtained for a mildly sloping step differs significantly from the result of Mei. The wave reflection is found to fluctuate owing to wave trapping for the mild sloping step. The height and the face slope of the step are important for determining wave reflection and transmission coefficients.

Boundary element method for calculation of elastic wave transmission in two-dimensional phononic crystals

A boundary element method(BEM) is presented to compute the transmission spectra of two-dimensional(2-D) phononic crystals of a square lattice which are finite along the x-direction and infinite along the y-direction.The cross sections of the scatterers may be circular or square.For a periodic cell,the boundary integral equations of the matrix and the scatterers are formulated.Substituting the periodic boundary conditions and the interface continuity conditions,a linear equation set is formed,from which the elastic wave transmission can be obtained.From the transmission spectra,the band gaps can be identified,which are compared with the band structures of the corresponding infinite systems.It is shown that generally the transmission spectra completely correspond to the band structures.In addition,the accuracy and the efficiency of the boundary element method are analyzed and discussed.

Frequency-dependent viscoelasticity effects on the wave attenuation performance of multi-layered periodic foundations

In this paper,layered periodic foundations(LPFs)are numerically examined for their responses to longitudinal and transverse modes in the time and frequency domains.Three different unit-cells,i.e.,2-layer,4-layer,and 6-layer unit-cells,comprising concrete/rubber,concrete/rubber/steel/rubber,and concrete/rubber/steel/rubber/lead/rubber materials,respectively,are taken into account.Also,the viscoelasticity behavior of the rubber is modeled with two factors,i.e.,a frequency-independent(FI)loss factor and a linear frequency-dependent(FD)loss factor.Following the extraction of the complex dispersion curves and the identification of the band gaps(BGs),the simulations of wave transmission in the time and frequency domains are performed using the COMSOL software.Subsequent parametric studies evaluate the effects of the rubber viscoelasticity models on the dispersion curves and the wave transmission for the longitudinal and transverse modes.The results show that considering the rubber viscoelasticity enhances the wave attenuation performance.Moreover,the transverse-mode damping is more sensitive to the viscoelasticity model than its longitudinal counterpart.The 6-layer unit-cell LPF exhibits the lowest BG,ranging from 4.8 Hz to 6.5 Hz.

A planar chiral nanostructure with asymmetric transmission of linearly polarized wave and huge optical activity in near-infrared band

Just like an electronic diode that allows the electrical current to flow in one direction only, a kind of chiral metamaterial structure with a similar functionality for the electromagnetic wave is proposed. The designed nanostructure that consists of twisted metallic split-ring resonators on both sides of a dielectric substrate achieves asymmetric transmission for a forward and backward propagating linearly polarized wave by numerical simulation in near-infrared band. Difference in transmission efficiency of the optimized structure between the same polarized waves incident from opposite directions can reach a maximum at the communication wavelength （1.55 μm）. Moreover, the simulation results of this structure also exhibit strong optical activity and circular dichroism.

A Theoretical Model for the Asymmetric Transmission of Powerful Acoustic Wave in Double-Layer Liquids

A theoretical model which couples the oscillation of cavitation bubbles with the equation of an acoustic wave is utilized to describe the sound fields in double-layer liquids, which can be used to realize the asymmetric transmission of acoustic waves. Numerical simulations show that the asymmetry is related to the properties of the host liquids and the input acoustic wave. Asymmetry can be enhanced if the maximum number density or the ambient radius of the cavitation bubbles in the low cavitation threshold liquid increases. Moreover, the direction of rectification will be reversed if the amplitude of the input acoustic wave becomes high enough.

Hydrodynamic Performance of Vertical Porous Structures Under Regular Waves

The hydrodynamic efficiency of the vertical porous structures is investigated under regular waves by use of physical models. The hydrodynamic efficiency of the breakwater is presented in terms of the wave transmission （kt）, reflection （kr） and energy dissipation （ka） coefficients. Different wave and structural parameters affecting the breakwater efficiency are tested. It is found that, the transmission coefficient （kt） decreases with the increase of the relative water depth （h/L）, the wave steepness （Hi^L）, the relative breakwater widths （B/L, B/h）, the relative breakwater height （D/h）, and the breakwater porosity （n）. The reflection coefficient （kr） takes the opposite trend of kt when D/h=l.25 and it decreases with the increasing h/L, HJL and B/L when D/h〈1.0. The dissipation coefficient （kd） increases with the increasing h/L, HilL and B/L when D/h〈_l.O and it decreases when D/h=l.25. In which, it is possible to achieve values ofkt smaller than 0.3, k~ larger than 0.5, and kd larger than 0.6 when D/h=1.25, B/h=0.6, h/L〉0.22, B/L〉O. 13, and H/L 〉0.04. Empirical equations are developed for the estimation of the transmission and reflection coefficients. The results of these equations are compared with other experimental and theoretical results and a reasonable agreement is obtained.

Effect of seismic waves on the hydro-mechanical properties of fractured rock masses

The transmission of seismic waves in a particular region may influence the hydraulic properties of a rock mass, including permeability, which is one of the most important. To determine the effect of a seismic wave on the hydraulic behavior of a fractured rock mass, systematic numerical modeling was conducted. A number of discrete fracture network（DFN） models with a size of 20 m × 20 m were used as geometrical bases, and a discrete element method（DEM） was employed as a numerical simulation tool. Three different boundary conditions without（Type Ⅰ） and with static（Type Ⅱ） and dynamic（Type Ⅲ） loading were performed on the models, and then their permeability was calculated. The results showed that permeability in Type Ⅲ models was respectively 62.7% and 44.2% higher than in Type I and Type Ⅱ models. This study indicates that seismic waves can affect deep earth, and, according to the results, seismic waves increase the permeability and change the flow rate patterns in a fractured rock mass.

Propagation of plane P-waves at interface between elastic solid and unsaturated poroelastic medium

A linear viscoporoelastic model is developed to describe the problem of reflection and transmission of an obliquely incident plane P-wave at the interface between an elastic solid and an unsaturated poroelastic medium, in which the solid matrix is filled with two weakly coupled fluids （liquid and gas）. The expressions for the amplitude reflection coefficients and the amplitude transmission coefficients are derived by using the potential method. The present derivation is subsequently applied to study the energy conversions among the incident, reflected, and transmitted wave modes. It is found that the reflection and transmission coefficients in the forms of amplitude ratios and energy ratios are functions of the incident angle, the liquid saturation, the frequency of the incident wave, and the elastic constants of the upper and lower media. Numerical results are presented graphically. The effects of the incident angle, the frequency, and the liquid saturation on the amplitude and the energy reflection and transmission coefficients are discussed. It is verified that in the transmission process, there is no energy dissipation at the interface.

Full Wave Solution for Hydrodynamic Behaviors of Pile Breakwater

Rayleigh expansion is used to study the water-wave interaction with a row of pile breakwater in finite water depth. Evanescent waves, the wave energy dissipated on the fluid resistance and the thickness of the breakwater are totally included in the model. The formulae of wave reflection and transmission coefficients are obtained. The accuracy of the present model is verified by a comparison with existing results. It is found that the predicted wave reflection and transmission coefficients for the zero order are all highly consistent with the experimental data （Hagiwara, 1984; Isaacson et al., 1998） and plane wave solutions （Zhu, 2011）. The losses of the wave energy for the fluid passing through slits play an important role, which removes the phenomena of enhanced wave transmission.

Hydroelastic Investigation on A Pile Breakwater Integrated with A Flexible Tail for Long-Wave Attenuation

A novel concept of wave attenuator is proposed for the defense of long waves,through integrating a flexible tail to the lee-side surface of a pile breakwater.The flexible tail works as a floating blanket made up of hinged blocks,whose scale and stiffness can be easily adjusted.A two-phase-flow numerical model is established based on the open-source computational fluid dynamics(CFD)code OpenFOAM to investigate its wave attenuation performance.Incompressible Navier−Stokes equations are solved in the fluid domain,where an additional computational solid mechanics(CSM)solver is embedded to describe the elastic deformation of the floating tail.The coupling of fluid dynamics and structural mechanics is solved in a full manner to allow assess of wave variation along the deforming body.The accuracy of the numerical model is validated through comparison with experimental data.Effects of the flexible tail on performance of the pile breakwater are investigated systematically.Dynamic behaviours of the tail are examined,and characteristics of its natural frequency are identified.For safety reasons,the wave loads impacting on the main body of the pile breakwater and the stress distribution over the tail are specially examined.It is found that both the length and stiffness of the tail can affect the wave-attenuation performance of the breakwater.A proper choice of the length and stiffness of the tail can greatly improve the long-wave defending capability of the pile breakwater.The maximum stress over the flexible tail can be restrained through optimising the deformation and stiffness of the tail.

Hydrodynamic Coefficient Investigation on a Partial Permeable Stepped Breakwater Under Regular Waves

Traditional breakwater takes the advantage of high protection performance and has been widely used.However,it contributes to high wave reflection in the seaside direction and poor water exchange capacity between open seawater and an inside harbor.Consequently,a partially permeable stepped breakwater(PPSB)is proposed to ensure safety and good water exchange capacity for an inside harbor,and a 3-D computational fluid dynamics(CFD)mathematical model was used to investigate the hydrodynamic coefficients using Reynolds-Averaged Navier-Stokes equations,Re-Normalization Group(RNG)k-εequations,and the VOF technique.A series of experiments are conducted to measure the wave heights for validating the mathematical model,and a series of dimensionless parameters considering wave and PPSB effects were presented to assess their relationships with hydrodynamic coefficients,respectively.With the increase in the reciprocal value of PPSB slope,incident wave steepness and permeable ratio below still water level(SWL),the wave reflection coefficient decreases.The wave transmission coefficient decreases with an increase in the reciprocal value of the PPSB slope and incident wave steepness;however,it increases with the increase in the permeable ratio below SWL.With increases in the reciprocal value of the PPSB slope,permeable ratio below SWL and incident wave steepness for relatively high wave period scenarios,the wave energy dissipation coefficient increases;however,it decreases slightly with increases in the incident wave steepness for the smallest wave period scenarios.Furthermore,simple prediction formulas are conducted for predicting the hydrodynamic coefficients and they are well validated with the related data.