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The Olympic Games (OG) are renowned for their prestige and socio-economic benefits; however, they have suffered criticism for their environmental practices. Unlike existing studies on the matter, which adopt top-down approaches, the purpose of this exploratory study is to conduct bottom-up research to understand Olympians’ perspectives of environmental sustainability within the OG. Data collected through semi-structured interviews with eight Olympians are used in this study to uncover an initial indication of their valuable yet previously undisclosed perspectives. Through the data, the Olympians’ awareness of the symbiotic relationship between sport and the environment is shown, alongside the factors that influence it. Uncovering Olympians’ perspectives allows for their call for change and collaboration with the International Olympic Committee (IOC) to be highlighted, while indicating that existing obstacles might be limiting the athletes and the Olympics in their efforts, progress and internalisation of environmental sustainability. [ABSTRACT FROM AUTHOR]

In order to accurately describe the axial forced vibration law of horizontal well drill string, the equivalent viscous damping method was used to linearize the Coulomb damping and the dynamic analytical model of horizontal well drill string motion was established under the action of axial vibration tool after considering the continuous characteristics of drill string, Coulomb damping, viscous damping of drilling fluid and the displacement excitation of drill string by axial vibration tool, based on the continuous wave theory. The model was verified by the axial vibration tool test experiment. The influence of the frequency of the axial vibration tool and the friction coefficient between the drill string and the wellbore on the axial forced vibration of the horizontal well drill string was analyzed by numerical simulation. The results show that the axial forced vibration response of the drilling string in horizontal wells can be improved by increasing the oscillation frequency of the axial vibration tool in a certain range, and that the effect of friction coefficient between drill string and borehole wall on the axial forced vibration of horizontal well drill string decreases with the increase of drill string length. The research method and models described in this paper can be expected to provide theoretical guidance for improving the use of axial vibration tools in horizontal well operation. [ABSTRACT FROM AUTHOR]

The wave height is the most basic element of wave information, and accurate measurement of wave heights plays a crucial role in both understanding wave theory and verifying numerical models. An improved optical measurement system was proposed based on the principle of binocular stereo vision, which breaks through the limitations of traditional measurement devices such as wave gauges and other single-point measurements, and improves the commonly used optical measurement method relying solely on images by involving the water wave theory into the data post-processing procedure. Through the identification and reconstruction of the unidirectional regular wave surface in a towing tank and the comparison of the results with the wave gauges and theoretical incoming wave parameters for validation, the research shows that, the measuring system has an error of about 1% in the measurement of a wide-area wave surface. Finally, a preliminary attempt was made on the irregular wave surface identification. [ABSTRACT FROM AUTHOR]

• A modified model regarding the viscosity and cavitation criterion was proposed and validated by experimental results. • Various numerical models were evaluated and the turbulence stress should be considered. • Fluid network and wave theory were used to elucidate different modulation mechanism in self-sustained resonating jet. • Cavitation evolution dominates the oscillation frequency of LF nozzle via modifying disturbed volume. • Geometry resonance couples with cavitation collapse and growth to achieve frequency modulation in HF nozzle. Self-sustained oscillating jets are widely utilized in various industries, and their oscillation frequencies are closely related to their performance efficiencies. The oscillation frequency is affected by cavitation in practical situations, and cavitation effects vary with geometry. In the present study, the computation fluid dynamics (CFD)-aided method is used to investigate the different modulation mechanisms induced by cavitation in high-frequency (HF) and low-frequency (LF) nozzles. The results indicate that the modified numerical model can reproduce the cavitation evolution in different nozzles and provide information to aid theoretical and experimental analyses. Based on the wave theory, it is found that the cavitation structures determine the LF nozzle oscillation frequency by dominating the disturbed volume bounded by the shear layer and chamber walls. In the case of HF nozzle, the growth and collapse of cavitation are regarded as the major excitation sources affecting oscillation frequency. In addition, the frequency is predicted using the CFD-aided method at various cavitation numbers, which is beneficial to the utilization of self-sustained oscillating jets. [ABSTRACT FROM AUTHOR]

Based on the wave theory and propagation characteristics of Lamb wave in the thin plate, Lamb wave is excited by signal actuator in the thin plate and signal sensor is received in real time. Employing the superior features of dispersion curve produced the Lamb wave and combining the dichotomy iterative principle with MATLAB tools to solve Lamb wave dispersion equation, the propagation characteristics of the Lamb wave in the thin plate are plotted. It is verified that the excited Lamb wave has multimode characteristics in a certain thickness, and the different modes are related to the frequency-thickness. The wavelength-thickness ratio is defined to simplify the calculation and provide convenience for the frequency bandwidth interception of Lamb wave. The results of the theoretical analysis show that the propagation multimode of Lamb and the distribution characteristics of dispersion curve can effectively simulate the transmission information of damage signal-excited thin plate, and identify damage region and determine the damage degree by S 0 and A 0 mode. The experimental results indicate that the established method to determine damage degree of thin plate attached PZT transducers based on Lamb wave active monitoring technology can achieve a certain precision, and can make a rough quantitative recognition of damage position. [ABSTRACT FROM AUTHOR]

Following the 1st International Workshop on Waves, Storm Surges and Coastal Hazards, which incorporated the 15th session of the long-standing the International Workshop on Wave Hindcasting and Forecasting, in September 2017 in Liverpool, United Kingdom, a topical collection has appeared in recent issues of Ocean Dynamics. Here, we give a brief overview of the 15 papers published in this topical collection as well as an overview of the widening scope of the conference in recent years. The continuing trend towards closer integration between the wave and ocean modeling communities is reflected in this workshop, culminating in the renaming of the workshop, while maintaining the connection with the three-decade long history of the wave workshop. This is also seen in this topical collection, with several papers exploring wave-generated storm surge, wave-tide contributions to coastal flooding, forcing a global ocean model with fluxes from a wave model and interaction between surface waves and sea ice. [ABSTRACT FROM AUTHOR]

Analysis of the seismic response of high CFRDs under non-uniform ground motion input is conducted using a novel non-uniform input motion calculation method combined with nonlinear FEM. The non-uniform input motion calculation method and its basic assumption are validated. The response of CFRDs under uniform and non-uniform input is compared to discuss the necessity of conducting seismic analysis of high CFRDs under realistic non-uniform ground motion input. When the acceleration at the surface of the free field for dynamic simulations with uniform and non-uniform input is kept consistent, the seismic response of CFRDs under non-uniform input is in general significantly smaller, while the dynamic tensile stress around the edges of the concrete face slab is greater. The simulation results suggest that non-uniformity of the ground motion input has important effects on the seismic response of high CFRDs and should be considered in the seismic design of CFRDs. The influence of the incident angle of seismic waves is also investigated, with results indicating that the influence is waveform dependent, while being frequency independent. [ABSTRACT FROM AUTHOR]

Conventional wisdom states that having concave surfaces as the envelope of any occupied space does not produce good sound. The focussing effect of concave surfaces can cause high sound pressure levels, coloration, and echoes. However, throughout history there have been many enclosed rooms with large curved surfaces as envelopes that seem to produce good acoustics. Recent research suggested that wave analysis must be undertaken to establish the impact of concave surfaces. In contrast to Part I of the current investigation, evaluation of the sound pressure level distribution, in rooms with concave surfaces, was performed by solving the governing wave equation. The main reason is that the image-ray theory is valid only at frequencies greater than the Schroeder cut-off frequency. The wave theory is used for frequencies lower than 100 Hz. Finite element modelling was applied to solve for the sound pressure level distribution within rooms with concave surfaces. Three spaces, the Paul Cocker Gallery in Ryerson University, Toronto, St. Pauls Anglican Church in Toronto and Wigmore Hall in London were investigated in this study. The results for three low frequencies (25 Hz, 50 Hz and 100 Hz) as well as their combination will be presented in this paper. [ABSTRACT FROM AUTHOR]

Non-Fourier one-dimensional unsteady heat conduction in a moving medium is investigated by using the Cattaneo-Vernotte- Christov-Jordan (CVCJ) heat flux model for medium speeds less than (sub-critical), equal to (critical), and greater than (super-critical) the thermal wave speed. Coupled partial differential equations are solved simultaneously by a finite volume numerical method. Temperature and heat flux distributions for sub-critical, critical, and super-critical flow conditions are presented for two example problems. The importance of boundary conditions on the thermal wave propagation in both sub-critical and super-critical cases is discussed. Approximate analytical solutions are presented which qualitatively substantiate the numerical results. [ABSTRACT FROM AUTHOR]

Physical limits on the amount of information carried by bandlimited waveforms radiated in one and three dimensions are considered. It is shown that the entropy of radiation can achieve the Bekenstein bound using a 'burst' of energy, whose density vanishes as the radiating system expands. In comparison, black body radiation of infinite bandwidth achieves the same entropy scaling, that is proportional to the volume of the space, but requires an energy density that remains constant as the system expands. Rather than following the standard statistical physics approach of counting the number of eigenstates of the Hamiltonian of the quantum wave field, our derivation first considers an optimal subspace approximation, and then determines the number of bits that are required to represent any waveform in the space spanned by this representation with a minimum quantized energy error. This favors a geometric interpretation where the complexity of state counting is replaced by the one of determining the minimum cardinality covering of the signal space by high-dimensional balls, or boxes, whose size is lower bounded by quantum constraints. All derivations are given for both deterministic and stochastic settings. [ABSTRACT FROM AUTHOR]

Following the 14th International Workshop on Wave Hindcasting and Forecasting and 5th Coastal Hazards Symposium in November 2014 in Key West, Florida, a topical collection has appeared in recent issues of Ocean Dynamics. Here, we give a brief overview of the 16 papers published in this topical collection as well as an overview of the widening scope of the conference in recent years. A general trend in the field has been towards closer integration between the wave and ocean modelling communities. This is also seen in this topical collection, with several papers exploring the interaction between surface waves and mixed layer dynamics and sea ice. [ABSTRACT FROM AUTHOR]

[Display omitted] • Established a mathematical model for the blasting dynamic response of mortar blots. • Calculated the dynamic response of morta bolts in different curing time and rock. • Proposed the blasting safety distance and vibration velocity of the mortar blots. Mortar bolts are an important part of the tunnel support structure, and tunnel blasting can cause vibration hazards to the existing bolt support structure. According to the theory of blasting elastic wave theory, a dynamic mathematical model of bolts mortar bolts considering initial surrounding rock stress was established. Based on the blasting excavation example of the Longnan tunnel of a high-speed railway from Ganzhou to Shenzhen in China, the blasting dynamic response characteristics of mortar bolts in 0 ∼ 3 days, 3 ∼ 7 days, and 7 ∼ 28 days curing time under the blasting excavation of Classification-II, Classification-III, Classification-IV, and Classification-V surrounding rock were calculated and studied. The dynamic failure mechanism of mortar bolts with different curing time under blasting vibration was clarified. According to the limit axial force of the mortar bolts, the blasting safety distance and vibration velocity of the tunnel mortar bolts support structure was proposed. [ABSTRACT FROM AUTHOR]

Corroboration with the already described experimental data, an exploration of a more sensitive SPR-based bimetallic fiber optic gas sensor (FOGS) using wave theory by illuminating the Bessel-Gauss beam is analytically proposed and designed here for methane gas sensing. The results are verified with the already reported experimental outcomes presented by Z. Shao et al. 2016 [43]. From a comparative assessment with the existing articles, it is observed that the RI sensitivity is 8936 dB/RIU, and the resolution is 1.12 × 10−6, which is one order superior to the reported FOGSs till date. The vital reason behind adopting the wave theory-based approach is for efficient computation of the coupling coefficient of the generated higher order modes and to acquire the similarities between the methodical and experimental solutions. With this process, first time utilizing the Bessel-Gauss beam, enhanced sensitivity is manifested for bimetallic FOGS. A higher dynamic range of refractive index from 1.06 to 1.22 and the consequences of the coupling of different modes are also discerned here. Here, the minimum detectable concentration is 1 ppm for the minimum change in transmission loss of 0.22 dB/RIU. This idea has various applications with the advantages like enhanced sensitivity, small size and broader detection ranges. • An exploration with the corroboration of already described experimental data. • Highly sensitive SPR and wave theory based bimetallic fiber optic gas sensor. • Results are 1 order superior than the ray theory based reported articles till date. • Achieving better similarity between the analytical and experimental solutions. • Dynamic range of RI is 1.06–1.22 with 1 ppm minimum detectable concentration. • RI sensitivity is 8936 dB/RIU and resolution of 1.12 × 10−6 with Bessel-Gauss beam. [ABSTRACT FROM AUTHOR]

Sound insulation prediction models in European and International Standards use the vibration reduction index to calculate flanking transmission across junctions of walls and floors. These standards contain empirical relationships between the ratio of mass per unit areas for the walls/floors that form the junction and a frequency-independent vibration reduction index. However, calculations using wave theory show that there is a stronger relationship between the ratio of characteristic moment impedances and the transmission loss from which the vibration reduction index can subsequently be calculated. In addition, the assumption of frequency-independent vibration reduction indices has been shown to be incorrect due to in-plane wave generation at the junction. Therefore numerical experiments with FEM, SFEM and wave theory have been used to develop new regression curves between these variables for the low-, mid- and high-frequency ranges. The junctions considered were L-, T- and X-junctions formed from heavyweight walls and floors. These new relationships have been implemented in the prediction models and they tend to improve the agreement between the measured and predicted airborne and impact sound insulation. [ABSTRACT FROM AUTHOR]

The accurate assessment of the dynamic response of the offshore wind turbine is fundamental to its economical and safe design, where the precise characterization of the incident wind and waves is essential. While reliable aerodynamic models can accurately reproduce wind characteristics, the widely-used empirical JONSWAP spectrum in wave field simulation may not capture the multi-modal feature of the mixed wave field near the wind farm. In this study, the stochastic structural responses based on an integrated FE model of the soil-pile-structure system are assessed employing the empirical and actual wave spectra, along with discussions on the impacts of wave theory and wave-structure interaction. The main conclusions are: (1) The empirical wave spectrum can overestimate the dynamic responses compared with the measured swell-dominant one, but the dominant wind load weakens its influence on displacement. (2) When the wave serves as the decisive loading, using the empirical spectrum overestimates the dynamic performance for the swell-dominant wave spectrum while underestimating it for the wind-induced-wave-dominant one. The approximation of the actual wave spectrum to the JONSWAP spectrum is only recommended when the coupling effect of wind and wave is inapparent. (3) The wave theory imposes an evident effect on the dynamic behavior of the offshore wind turbine subject to joint wind and wave loading, where the JONSWAP wave spectrum is more sensitive. (4) The influence of water-monopile interaction is negligible when using the JONSWAP wave spectrum but prominent for the simulation's actual wave spectrum. • An integrated FE model considering soil-pile-structure interaction is developed. • Response discrepancies induced by JONSWAP and actual wave spectra are analyzed. • Influence of spectral disparities induced by inhomogeneous wave field is discussed. • Sensitivities of spectrum influence to wave theory and wave-structure interaction are studied. [ABSTRACT FROM AUTHOR]

This work analyses basic wave properties originating from the interaction between waves and submerged rigid vegetation. First of all, an analytical framework is presented that describes the propagation and dissipation of waves over a rigid and submerged canopy, where the flow resistance is linearised. A nonlinear closure term is introduced to ensure that the work done by the linearised flow resistance equals that of the nonlinear flow resistance. The anisotropic flow resistance is found to have an impact on both the distribution of velocities and pressure inside the canopy and it partly explains the small decrease in flow velocities inside the canopy, which was previously observed experimentally. The following second order wave properties are derived: the wave energy density, the wave energy flux, the vegetated group velocity of the wave energy density, the radiation stress components parallel and perpendicular to the direction of wave propagation, the Eulerian and Lagrangian Stokes velocities and fluxes. The additional Stokes drift due to the discontinuity in the velocity field at the top of the vegetation is derived; the inclusion of this mass flux in the Lagrangian formulation of the Stokes drift is important for the ratio between the Lagrangian and Eulerian Stokes drifts. The relation between the wave energy density and the wave energy flux, i.e. the vegetated group velocity of the wave energy density, is of practical importance for large scale wave modelling. The modification to the vegetated group velocity relative to that derived from linear wave theory on non-dissipative waves is described. It is seen that the corrections to linear wave theory are of H γ , where γ is in the interval 1.5–2.0. [ABSTRACT FROM AUTHOR]

General propagation properties and universal curves are given for double clad single mode fibers with inner cladding index higher or lower than the outer cladding index, using the parameter: inner cladding/core radii ratio. Mode cut-off conditions are also examined for the cases. It is shown that dispersion properties largely differ from the single clad single mode fiber case, leading to large new possibilities for extension of single mode operation for large wavelength range. Paper demonstrates that how substantially we can extend the single mode operation range by using the raised inner cladding fiber. Throughout we have applied our own computations technique to find out the eigenvalue for a given modes. Detail derivations with all trivial mathematics for eigenmode equation are derived for each case. Paper also demonstrates that there is not much use of using depressed inner cladding fiber. We have also concluded that using the large inner cladding/inner core radius we can significantly increase the single mode operation range for the large wavelength region. [ABSTRACT FROM AUTHOR]

The developed technique makes possible to investigate the impact on oscillations of flexible elements of drive systems and transportation of nonlinear forces, the speed of longitudinal movement and perturbations of boundary conditions. Based on the obtained results it is proved that even for the linear analogue system the slowly time-dependent variable of the distance between the flexible elements (SE) contact points and the pulleys causes the change of the basic parameters of the waves. The limits of applying the wave theory of motion in the case of nonlinear oscillations of flexible elements of drive systems under slowly varying boundary conditions are expanded. The basic computations to analyze the main parameters of the dynamic process depending on motion speed of flexible element, tension force, and the ratio describing the motion principle of the contact point of flexible element and the pulley, are made. [ABSTRACT FROM AUTHOR]

This paper contains a commented translation to Portuguese of Thomas Young's On the theory of light and colours, published in the Philosophical Transactions of the Royal Society of London in 1802. With this translation, we intend to discuss the contribution of Young to the development of the wave theory of light and also to offer resources to promote discussions about the nature of scientific knowledge in teaching and learning of Science. [ABSTRACT FROM AUTHOR]

Two electromagnetic models were used to simulate snow emission at L-band from in situ measurements of snow properties collected at Dome C in Antarctica. Two different approaches were used: one based on the radiative transfer theory and the other on the wave approach. The soil moisture ocean salinity (SMOS) satellite observations performed at 1.4 GHz (21 cm) were used to check the validity of these models. Model results based on the wave approach were in good agreement with SMOS observations, particularly for incidence angles lower than 55°. Comparisons suggest that the wave approach is more suitable to simulate brightness temperature at L-band than the transfer radiative theory, because interference between the layers of the snowpack is better taken into account. The model based on the wave approach was then used to investigate several L-band characteristics at Dome C. The emission e-folding depth, i.e., 67% of the signal, was estimated at 250 m, and 99% of the signal emanated from the top 900 m. L-band brightness temperature is only slightly affected by seasonal variations in surface temperature, confirming the high temporal stability of snow emission at low frequency. Sensitivity tests showed that good knowledge of density variability in the snowpack is essential for accurate simulations in L-band. [ABSTRACT FROM PUBLISHER]

To unify different seismic geometries, the concept of generalized offset is defined and the expressions for Fresnel zones of different order on a plane are presented. Based on wave theory, the equation of the lateral wave-field stacking for generalized-offset Fresnel zones is derived. For zero and nonzero offsets, the lateral stacking amplitude of diffraction bins of different sizes is analyzed by referring to the shape of the Fresnel zones of different order. The results suggest the following. First, the contribution of diffraction bins to wave-field stacking is related to the offset, surface relief, interface dip, the depth of the shot point to the reflection interface, the observational geometry, and the size of the interference stacking region. Second, the first-order Fresnel zone is the main constructive interference, and its contribution to the reflection amplitude is slightly smaller than half the contribution of all Fresnel zones. Finally, when the size of the diffraction bin is smaller than the first-order Fresnel zone, the larger the size of the diffraction bin, the larger is the amplitude of the receiver, even in the nonzero offset-case. [ABSTRACT FROM AUTHOR]

Following the 13th International Workshop on Wave Hindcasting and Forecasting and 4th Coastal Hazards Symposium in October 2013 in Banff, Canada, a topical collection has appeared in recent issues of Ocean Dynamics. Here, we give a brief overview of the history of the conference since its inception in 1986 and of the progress made in the fields of wind-generated ocean waves and the modelling of coastal hazards before we summarize the main results of the papers that have appeared in the topical collection. [ABSTRACT FROM AUTHOR]

Understanding and modeling wave attenuation by flexible vegetation have emerged as essential issues in coastal and ocean engineering. Given that the existing XBeach phase-averaged wave model can only simulate wave attenuation by rigid vegetation, and previous studies of wave energy dissipation by vegetation are mainly restricted to linear wave theory. This study aims to extend the XBeach phase-averaged wave model to simulate wave attenuation by both homogeneous and heterogeneous submerged flexible vegetation, and determine wave attenuation simulation deviation based on different wave theories. Hence, the existing flexible vegetation dynamic model is incorporated into the XBeach phase-averaged wave model. The reliability of the coupled model in simulating wave attenuation by both homogeneous and heterogeneous submerged flexible vegetation is revealed. Simulation results also demonstrate that the computed wave attenuation rate based on Stokes second-order wave theory is larger than that based on linear wave theory within the parameters used in this investigation. Meanwhile, wave attenuation simulation deviation between these two wave theories enlarges as the Ursell number increases within the parameters used in this investigation. This study can broaden the application of the XBeach model and lay the technical foundation for future engineering practice of nature-based coastal defence. • The XBeach phase-averaged wave model is extended and coupled with a flexible vegetation dynamic model. • The coupled model can simulate wave attenuation by submerged both homogeneous and heterogeneous flexible vegetation. • Different wave theories can affect wave attenuation rate, simulated discrepancy enlarges as the wave nonlinearity increases. [ABSTRACT FROM AUTHOR]

The derivation of string theory from the two paradigms of wave theory and of relativity is a stage 14 task. The wave theory may partially be represented by the acoustic wave equation for a fluid in one dimension. The stages of development of the wave equation can be is presented in terms of increasing orders of hierarchical complexity. The derivation, shown from order 8 concrete to 13 paradigmatic is presented as a schema where it is specified how a higher order is created by coordinating elements from the respective previous order. The wave equation at the paradigmatic order is created by coordinating the three metasystematic relationships: Newton's Law of Motion, the Constitutive equation and the Ideal gas law. These three relationships in turn coordinate the variables force, density and acceleration, all being systematic since they are functions of time and location. This result gives an understanding of how knowledge is organized in the acoustic domain and in adjacent domains such as classical and solid mechanics. This paradigm is also combined with notions from general relativity to show that the two paradigms may be combined to form a crossparadigmatic task. One result is string theory. It also serves as an illustrative example of the principles of MHC. [ABSTRACT FROM AUTHOR]

A low-cost, non-toxic and effective adsorbent constituted by a montmorillonite coated by iron oxides (montmorillonite-iron oxide composite) was prepared to assess its effectiveness in the removal of Cs and Sr from aqueous solution. Dynamic adsorption experiments were carried out at room temperature under the effect of various operating parameters such as bed depth Z (5-15 cm), initial cation concentration C (2-50 mg L) and volumetric flow rate Q (0.5-8 mL min). Column performance has been modeled with constant-pattern wave approach combined to the Freundlich isotherm model and artificial neural network (ANN) models. The time, initial cation concentration, bed depth and volumetric flow rate were chosen as the input variables whereas, the outlet concentration C was considered as the output variable. The developed network was found to be useful in predicting the breakthrough curves. Experimental data for the used system were well fitted with ANN than the combined constant-pattern wave approach. [ABSTRACT FROM AUTHOR]

By the shock relationships, the wavy characteristics and the forming conditions of a shock wave are analyzed. The wavy characteristics of an Euler system are studied theoretically. The present research focuses on the wavy characteristics of Tollmien-Schlichting (T-S) waves, the excitation conditions of shocklets in compressible boundary layers, and the viscous effect on shock. The possibility of existence of shocklets in the compressible boundary layer and the physical mechanism of formation are theoretically interpreted. [ABSTRACT FROM AUTHOR]

Highlights: [•] The controller speeds up significantly the start-up of the process. [•] It shows good disturbance rejection, stability. [•] It allows the optimization of the operating conditions even with very little prior knowledge of the adsorption characteristics. [•] It is able to compensate for plant-model mismatch situations, and modeling errors. [•] It can be implemented on plants with different sensor configurations showing good stability properties. [Copyright &y& Elsevier]

Problems of acoustic wave propagation near the interface between media are discussed. The processes that occur at a liquid-gas interface are considered, and their characteristic features related to the effect of inhomogeneous waves are pointed out. The transmission factors of spherical and cylindrical waves incident on the aforementioned interface are calculated with allowance for the contribution of the inhomogeneous component. Experimental dependences of the transmission factor on frequency and source depth measured with respect to the interface are presented. It is shown that the lower the frequency generated by the source and the closer the source to the water-air interface, the higher the acoustic transparency of the interface. [ABSTRACT FROM AUTHOR]

We show that the population ecology of the 9- to 10-year cyclic, broadleaf-defoliating winter moth ( Operophtera brumata) and other early-season geometrids cannot be fully understood on a local scale unless population behaviour is known on a European scale., Qualitative and quantitative data on O. brumata outbreaks were obtained from published sources and previously unpublished material provided by authors of this article. Data cover six decades from the 1950s to the first decade of twenty-first century and most European countries, giving new information fundamental for the understanding of the population ecology of O. brumata., Analyses on epicentral, regional and continental scales show that in each decade, a wave of O. brumata outbreaks travelled across Europe., On average, the waves moved unidirectionally ESE-WNW, that is, toward the Scandes and the Atlantic. When one wave reached the Atlantic coast after 9-10 years, the next one started in East Europe to travel the same c. 3000 km distance., The average wave speed and wavelength was 330 km year−1 and 3135 km, respectively, the high speed being incongruous with sedentary geometrid populations., A mapping of the wave of the 1990s revealed that this wave travelled in a straight E-W direction. It therefore passed the Scandes diagonally first in the north on its way westward. Within the frame of the Scandes, this caused the illusion that the wave moved N-S. In analogy, outbreaks described previously as moving S-N or occurring contemporaneously along the Scandes were probably the result of continental-scale waves meeting the Scandes obliquely from the south or in parallel., In the steppe zone of eastern-most and south-east Europe, outbreaks of the winter moth did not participate in the waves. Here, broadleaved stands are small and widely separated. This makes the zone hostile to short-distance dispersal between O. brumata subpopulations and prevents synchronization within meta-populations., We hypothesize that hostile boundary models, involving reciprocal host-herbivore-enemy reactions at the transition between the steppe and the broadleaved forest zones, offer the best explanation to the origin of outbreak waves. These results have theoretical and practical implications and indicate that multidisciplinary, continentally coordinated studies are essential for an understanding of the spatio-temporal behaviour of cyclic animal populations. [ABSTRACT FROM AUTHOR]

Abstract: Attempts to explain the redistribution of energy in interference has been done from time to time, under two of the most accepted theories, wave and quantum; however its mechanism still lacks clear interpretation. In this study, a new experiment has been designed and conducted to observe the redistributed energy in wave interference. Experimental observations on the redistributed energy that occurs in two interfering coherent waves are presented. Re-distributed energy at a certain region, (single bright fringe) in space due to interference of two waves was isolated at a plane and measured at a distant plane away from the isolated plane. The measured energy distribution of the isolated interference pattern was compared with the resultant calculated from the two individual interfering components based on wave theory. The calculated resultant due to the two individual components does not tally with the experimental observed pattern. Hence, the outcome of this experiment is in disagreement with the expected predictions as per the wave theory. [Copyright &y& Elsevier]

Abstract: During the past few decades, wave energy has received significant attention for harnessing ocean energy. Industry has proposed many technologies and, based on their working principle, these technologies generally can be categorized into oscillating water columns, point absorbers, overtopping systems, and bottom-hinged systems. In particular, many researchers have focused on modeling the point absorber, which is thought to be the most cost-efficient technology to extract wave energy. To model such devices, several modeling methods have been used such as analytical methods, boundary integral equation methods and Navier–Stokes equation methods. The first two are generally combined with the use of empirical solution to represent the viscous damping effect, while the last one is directly included in the solution. To assist the development of wave energy conversion (WEC) technologies, this paper extensively reviews the methods for modeling point absorbers. [Copyright &y& Elsevier]

Despite the importance of both response probability and response time for testing models of choice, there is a dearth of chronometric studies examining systematic asymmetries that occur over time- and space-orders in the method of paired comparisons. In this study, systematic asymmetries in discriminating the magnitude of paired visual stimuli are examined by way of log odds ratios of binary responses as well as by signed response speed. Hierarchical Bayesian modeling is used to map response probabilities and response speed onto constituent psychological process, and processing capacity is also assessed using response time distribution hazard functions. The findings include characteristic order effects that change systematically in magnitude and direction with changes in the magnitude and separation of the stimuli. After Hellström (1979, 2000), sensation weighting (SW) model analyses show that such order effects are reflected in the weighted accumulation of noisy information about the difference between stimulus values over time, and interindividual differences in weightings asymmetries are related to the relative processing capacity of participants. An account of SW based on the use of reference level information and maximization of signal-to-noise ratios is posited, which finds support from theoretically driven analyses of behavioral data. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, an evaluation of the method of experimental seismic simulation of vertical free-field ground motion by wave-absorbing boundary and centrifuge modeling is presented. By means of a large soil container with Ductseal lining and an in-box shake-table system, a series of seismic tests on a sand stratum model of uniform density and a large width-to-depth ratio was conducted at multiple g-levels. With a focus on the vertical motion produced, the time-domain data was processed using the transfer function approach. By examining the measured resonant regimes for the vertical mode as a function of the g-level or length scale over the frequency spectrum, the capability of the Ductseal boundary approach in simulating vertical free-field motions in one-dimensional inhomogeneous site response theory is highlighted. In seeking a comprehensive basis of synthesis for the modeling methodology, the benefits of using the three-dimensional elastodynamic model in the interpretation of the vertical free-field measurements are demonstrated. [Copyright &y& Elsevier]

A generalized radar scattering model based on wave theory is described. The model predicts polarimetric radar backscattering coefficients for structurally complex vegetation comprised of multiple species and layers. Compared to conventional two-layer crown-trunk models, modeling of actual forests has been improved substantially, allowing better understanding of microwave interaction with vegetation. The model generalizes an existing single-species discrete scatterer model and, by including scattering and propagation effects through judiciously defined vegetation layers, enables its application to an arbitrary number of species types. The scatterers within each layer are modeled as finite cylinders or disks having arbitrary size, density, and orientation, as in the predecessor model. The distorted Born approximation is used to represent the propagation through each layer, while scattering from each is modeled as a linear superposition of scattering from its respective random collection of scatterers. Interactions of waves within and between each layer and direct scattering from the ground are accounted for. Validation of the model is presented based on its application to 23 wooded savanna sites located in Queensland, Australia, and comparison with Advanced Land Observing Satellite (ALOS) Phased Arrayed L-band Synthetic Aperture Radar (PALSAR) and National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory (JPL) Airborne Synthetic Aperture Radar (AIRSAR) data. Results indicate good agreement between simulated and actual backscattering coefficients, particularly at HH and VV polarizations. More discrepancies are found at HV polarizations and can be explained by uncertainties in the knowledge of input parameters, such as inaccuracies in the surface model, surface roughness parameterization, and soil moisture. [ABSTRACT FROM PUBLISHER]

Abstract: In this work a new approach to the control of simulated moving bed (SMB) chromatographic separation processes is presented. This approach is based on the combination of the wave theory and Multi-Model Predictive Control (MMPC). The wave theory provides the theoretical framework in which the control law is formulated whereas receding-horizon MPC is used for determining the appropriate controller parameters. As SMB plants are distributed parameter systems (DPS) with nonlinearity arising from the expression of the adsorption isotherms, classical numerical methods for the solution of DPS are computationally demanding for MPC purposes. Reduced-order models are therefore derived using the proper orthogonal decomposition (POD) technique. To ensure stability, the POD model is updated on-line, resulting in MMPC. [ABSTRACT FROM AUTHOR]

The article discusses the work of German experimental psychologist Gustav Theodor Fechner, focusing on his theory of inner psychophysics developed in the book "Elements of Psychophysics." While Fechner is well known for his theories on outer psychophysics, the author seeks to understand why the work on inner psychophysics has been largely ignored by psychologists. The influence of German psychologist Ernst Heinrich Weber on the work of Fechner is described, including Fechner's creation of the "Weber law." The development of Fechner's wave model of inner psychophysics, and its relationship to pantheism, is outlined.

Abstract: So far the electro-acoustical equivalent circuit analysis has been widely used to analyse micro-perforated panel (MPP) absorbers, however, as for the double-leaf MPP the equivalent circuit analysis inevitably includes an approximation. In this paper, the sound absorption characteristics of a double-leaf MPP absorber backed by a rigid wall are analysed by wave theory using Helmholtz–Kirchhoff integral formulation to obtain a strict solution. The present wave theory is experimentally validated with existing measured results. The theory is also compared with the equivalent circuit solutions so that the differences between the two theories appear and the effect of the approximation is clarified. The comparison shows that the difference mainly appears in the vicinity of the resonance peaks: the differences occur in the resonance frequencies and the absorption coefficient at frequencies between the two resonance peaks. [Copyright &y& Elsevier]

The numerical modeling and wave theory are used in tsunami mitigation analysis. It is assumed sea forest is simulating offshore structure submitted to wave loads. The sea forest acts simulate break waves in conservation of coastal territory and facility installed over there. The result reveal that mathematical modeling and numerical simulation can be used to understand tsunami ability in design and urban construction, the research indicates reduction of water deep by sea forest resulted in reducing geometry and all wave ability. [ABSTRACT FROM AUTHOR]

Abstract: The cyclic water gas-shift reactor (CWGSR) is a cyclically operated fixed bed reactor for the removal of carbon monoxide from reformate gases. It is based on the repeated reduction of iron oxide by reformate gases and its subsequent oxidation by steam. To evaluate the thermodynamic limits of this reactor, we develop a model under the assumption of chemical equilibrium. For this purpose, we conduct a wave analysis which shows that the reactor behaviour is dominated by the movement of sharp reaction fronts. Depending on the positions of these fronts at cyclic steady state, five different operating regimes of the CWGSR can be identified. Besides the qualitative analysis of the regimes, the equilibrium model also offers a first quantitative analysis regarding the two performance parameters, i.e. fuel utilisation and product concentration. At 750°C, a fuel utilisation of 55% can be achieved, and the molar hydrogen fraction in the product stream is up to 70%. The equilibrium model can be used for a first estimate of favourable design and operating parameters of the CWGSR. [Copyright &y& Elsevier]

Dynamic characteristics and wave attenuation mechanism of flexible vegetation have propelled to the forefront in investigations of coastal engineering. Given that existing studies of wave nonlinearity are mainly restricted to rigid vegetation assumptions, this study was undertaken to quantitatively determine the effect of wave nonlinearity on submerged flexible vegetation dynamics as well as wave attenuation based on flexible vegetation dynamic model and experimental results. Meanwhile, the influence of different wave theories along with different determination methods of characteristic wave velocity was evaluated quantitatively. Results reveal that wave nonlinearity exerts substantial nonlinear and nonmonotonic effects upon flexible vegetation dynamics and wave attenuation rate. The maximum horizontal force, stem tip excursion, and wave height attenuation rate increase as the dimensionless Ursell number increases on the whole under the present investigation conditions. Moreover, it is suggested that different wave theories and determination methods of characteristic wave velocity can result in slight discrepancies of flexible vegetation dynamics, which may further affect wave attenuation by flexible vegetation. Determining the impacts of wave nonlinearity, wave theory, and characteristic wave velocity provides clearer insight into the wave attenuation mechanism of flexible vegetation, which is of great benefit to the flexible vegetation dynamics and related wave attenuation model improvement. • Wave nonlinearity exerts nonlinear and nonmonotonic effects upon flexible vegetation dynamics and wave attenuation rate. • The maximum horizontal force, stem tip excursion, and wave attenuation increase as the Ursell number increases on the whole. • Different wave theories and determination methods of characteristic wave velocity can affect flexible vegetation dynamics. [ABSTRACT FROM AUTHOR]

The Salton Sea is the largest lake, on a surface area basis, in California (939 km2). Although saline (>44 g/l) and shallow (mean depth approximately 9.7 m), it provides valuable habitat for a number of endangered species. The distribution of sediments and their properties within the Salton Sea are thought to have significant influence on benthic ecology and water quality. Sediment properties and their distribution were quantified and compared with predicted distributions using several sediment distribution models. Sediment samples ( n = 90) were collected using a regular staggered-start sampling grid and analyzed for water content, organic carbon (C), calcium carbonate, total nitrogen (N), total phosphorus (P), organic phosphorus, and other properties. Water content, total N, and total and organic P concentrations were all highly correlated with organic C content. The organic C concentration showed a non-linear increase with depth, with low organic C contents (typically 1–2%) present in sediments found in depths up to 9 m, followed by a strong increase in organic C at greater depths (to about 12% at 15 m depth). The models of Hakanson, Rowan et al., Blais and Kalff, and Carper and Bachmann yielded very different predicted critical depths for accumulation (10.5–22.8 m) and areas of accumulation (0–49.5%). Hakanson’s dynamic ratio model more reasonably reproduced the observed zone of elevated organic C concentrations in the Salton Sea than either exposure- or slope-based equations. Wave theory calculations suggest that strong winds occurring less than 1% of the time are sufficient to minimize accumulation of organic matter in sediments that lie at depths less than 9 m in this system. [ABSTRACT FROM AUTHOR]

Abstract: The centrifugal atomisation of metallic melts using a rotating disk is an important process for powder production and spray deposition. The theoretical prediction of powder particle size is desirable for the design of atomisers. In this paper, wave theory was applied to analyse the disintegration of metallic melts in the film disintegration regime during centrifugal atomisation using a rotating disk. A mathematical model was proposed to predict the spray parameters. The governing equation for the fastest-growing wave number was developed and solved numerically. The effect of the variation in film thickness during film extension was taken into account. Film length and powder particle size were calculated and compared with available experimental data in the literature, and a good agreement was achieved. The influence of the break-up parameter was studied, and it is shown that the break-up parameter is not sensitive to the predicted powder particle size. Both simulated results and experimental data showed that fine powders can be produced by increasing disk speed. [Copyright &y& Elsevier]

Abstract: Carbon fixed-beds are usually used to remove organic contaminants. Adsorption in a carbon filter is a dynamic, non-steady process which is not yet completely understood. The objective of this paper is to establish a methodology to simplify the study of this process based on the wave theory, rapid small-scale column test and experimental design/surface response analysis. The constant pattern wave hypothesis was confirmed by the experimental data. The influence of the inlet concentration of p-nitrophenol and the flow rate on dynamic adsorption was studied at 20°C following a central composite design using a second-order model. Both parameters have an important influence on the response variables studied. The methodology used is a useful tool for studying the dynamic process and shows interactions that are difficult to verify by the classical step-by-step method. [Copyright &y& Elsevier]

Abstract: The reliability analysis of offshore structures under wave and wind actions is considered using second order random wave theory. To represent non-Gaussian properties of the resulting wave kinematics, the Hermite moment transformation is used. Further, the so-called sample-specific linearization method developed already (to be used in conjunction with the directional simulation method and the linear wave theory) will be extended to take into account both (1) non-Gaussianity of wave/wind load due to nonlinear load processes and also (2) the non-Gaussianity of wave kinematics due to the nonlinear wave theory. This allows an out-crossing approach to be used to assess the structural probability of failure and the involving out-crossing rate (which is not generally available for non-Gaussian processes) is required to be estimated. Using the proposed procedure, simple structures are analyzed in one- and multi-dimensional cases and the results for structural probability of failure are compared with those obtained using simple linear wave theory. Outcomes show that the use of nonlinear wave theory may affect the results considerably. [Copyright &y& Elsevier]

By applying the kinematic wave method to a homogeneous, rectangular overland plane, the influence of the constant and proportional-loss models on the design discharge are examined. The examination shows that with the use of the proportional-loss model, there is no partial-area effect and the design discharge is governed by the full-area contribution. On the other hand, with the use of the constant-loss model, there is no partial-area effect if the loss rate is small. For larger loss rates, there is a partial-area effect; and for this case, the design is complicated, since there is a need to search for the critical storm that governs the partial-area effect. The characteristic of the critical storm is that its rate of decrease in rainfall intensity with duration equals the corresponding rate of increase in the contributing area. The preceding findings are consistent with the design concept in the rational method that uses the proportional-loss model, and the results from earlier studies that used the constant-loss model. [ABSTRACT FROM AUTHOR]

Some recent developments in the formation of extreme waves, kinematics of steep waves, the phenomenon of ringing and currents in the ocean induced by internal waves are reviewed. Formation of extreme waves are simulated by means of a rapid fully nonlinear model. A large wave event taking place in a wave group is characterized by an elevation being significantly larger than the initial amplitude of the group. Recurrence occurs. PIV measurements of Stokes waves exhibit an exponential velocity profile all the way up to the surface elevation (wave slope up to 0.16). The computed velocity profile under crest of an extreme wave corresponds also to an exponential profile. Experimental results of the horizontal force on a vertical circular cylinder in long and steep waves exhibit a secondary cycle of high frequency in the force history. This typically occurs for waves longer than about 10 times the cylinder diameter and a Froude number ωηm/√ of gD larger than about 0.4, ω the wave frequency, ηm the maximal elevation, g the acceleration of gravity, D the cylinder diameter. Properties of internal solitons and the induced fluid velocities are described in terms of weakly and fully nonlinear models supported by PIV measurements. A rapid scheme for fully nonlinear interfacial waves in three dimensions is derived, complementing the rapid model of free surface waves. [Copyright &y& Elsevier]

• The validity of wave theory in a short, physical, wave flume is assessed using free surface elevation and PIV measurements. • Ten different regular waves of varying steepness in deep and intermediate water conditios are analysed. • The tested deep water waves show relatively small reflection coefficients, compared to intermediate water waves. • Stokes 2nd order wave theory shows validity as a function of the reflection coefficient. The modelling of ocean waves is an integral part of coastal and offshore engineering. Both theoretical and experimental modelling methods are available and are commonly used in support of each other. In particular, due to the difficulty in measuring the velocity throughout the water column, the wave kinematics are often derived, by means of wave theory, from a measurement of the free surface elevation. However, wave theory is often based upon idealistic conditions, such as infinite spatial domains and time lengths. The question therefore arises, how well are the wave kinematics in an experimental wave tank described by wave theory? The present paper compares theoretical solutions against experimental data, for the free surface elevation and the velocity throughout the water column, to assess the ability of Stokes' wave theory to describe the kinematics of regular waves in a short, physical, wave flume. Experimentally, the free surface elevation is measured with a set of resistive wave probes, while wave kinematic data is acquired with particle image velocimetry (PIV). For this study, ten different regular waves, of varying steepness, are generated in a 35 m long and 0.7 m deep wave flume. The theoretical solutions are computed based on Stokes 2 nd order wave theory. The presented results show error values of the order of 10–20%, indicating validity of the employed wave theory as a function of the reflection coefficient achieved in the physical wave flume. These result highlight the potential inaccuracies incurred in any wave tank if the wave theory is used to derive the kinematics from the free surface elevation without having detailed knowledge of the reflection characteristics at the point of interest in the tank. [ABSTRACT FROM AUTHOR]