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Currently, divers face significant safety risks when cleaning marine organisms from the steel structures of offshore underwater platform jackets. Consequently, utilizing robots instead of divers to carry out underwater biofouling removal operations will be an important development direction for the underwater maintenance of offshore platforms in the future. In this study, a wall-climbing robot was designed to clean marine organisms from the underwater surface of a platform jacket leg. The overall structure of the underwater cleaning wall-climbing robot is introduced, including the cleaning actuator and the variable curvature-adapted connecting rod mechanism. The corresponding relationship between the variable curvature-adapted connecting rod mechanism and the jacket leg is analyzed in detail. The variable curvature-adapted connecting rod mechanism was optimized using a genetic algorithm to ensure that the underwater cleaning wall-climbing robot can adapt to a minimum diameter of 1 m for the jacket leg. By drawing on Airy wave theory and random wave theory, the Airy wave parameters for waves were analyzed under different sea conditions, considering practical application scenarios. By using Fluent software 2022, a 2D numerical wave tank was constructed to simulate waves under various sea conditions, and the wave surface shapes for different sea states were determined. By building on the Morison equation, a method for calculating the horizontal wave forces on the underwater cleaning wall-climbing robot using the equivalent area and equivalent volume is proposed. By using the two aforementioned methods, the horizontal wave forces on the underwater cleaning wall-climbing robot under specific sea states were determined. The horizontal wave forces of the underwater cleaning wall-climbing robot under different sea conditions were analyzed and simulated in a 3D numerical wave tank. By comparing the theoretical analysis results with the numerical simulation results, where the maximum difference at the extreme points is approximately 11%, the feasibility of the proposed horizontal wave force estimation method was verified. [ABSTRACT FROM AUTHOR]

Currently, divers face significant safety risks when cleaning marine organisms from the steel structures of offshore underwater platform jackets. Consequently, utilizing robots instead of divers to carry out underwater biofouling removal operations will be an important development direction for the underwater maintenance of offshore platforms in the future. In this study, a wall-climbing robot was designed to clean marine organisms from the underwater surface of a platform jacket leg. The overall structure of the underwater cleaning wall-climbing robot is introduced, including the cleaning actuator and the variable curvature-adapted connecting rod mechanism. The corresponding relationship between the variable curvature-adapted connecting rod mechanism and the jacket leg is analyzed in detail. The variable curvature-adapted connecting rod mechanism was optimized using a genetic algorithm to ensure that the underwater cleaning wall-climbing robot can adapt to a minimum diameter of 1 m for the jacket leg. By drawing on Airy wave theory and random wave theory, the Airy wave parameters for waves were analyzed under different sea conditions, considering practical application scenarios. By using Fluent software 2022, a 2D numerical wave tank was constructed to simulate waves under various sea conditions, and the wave surface shapes for different sea states were determined. By building on the Morison equation, a method for calculating the horizontal wave forces on the underwater cleaning wall-climbing robot using the equivalent area and equivalent volume is proposed. By using the two aforementioned methods, the horizontal wave forces on the underwater cleaning wall-climbing robot under specific sea states were determined. The horizontal wave forces of the underwater cleaning wall-climbing robot under different sea conditions were analyzed and simulated in a 3D numerical wave tank. By comparing the theoretical analysis results with the numerical simulation results, where the maximum difference at the extreme points is approximately 11%, the feasibility of the proposed horizontal wave force estimation method was verified.

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 article solves the problem of theoretically determining the deformable characteristics of railway ballast, considering its condition through mathematical modeling. Different tasks require mathematical models with different levels of detail of certain elements. After a certain limit, excessive detailing only worsens the quality of the model. Therefore, for many problems of the interaction between the track and the rolling stock, it is sufficient to describe the ballast as a homogeneous isotropic layer with a vertical elastic deformation. The elastic deformation of the ballast is formed by the deviation of individual elements; the ballast may have pollutants, the ballast may have places with different levels of compaction, etc. To be able to determine the general characteristics of the layer, a dynamic model of the stress–strain state of the system based on the dynamic problem of the theory of elasticity is applied. The reaction of the ballast to the dynamic load is modeled through the passage of elastic deformation waves. The given results can be applied in the models of the railway track in the other direction as initial data regarding the ballast layer.

Passive multispectral imaging and active bathymetric lidar make a great achievement for bathymetry in optically shallow waters. However, due to the attenuation of the water column precludes deep penetration of the light, accurately obtaining the underwater topography in turbid waters through remote sensing techniques, both passive and active, is still a challenging task. Airborne lidars can obtain water surface topography with high accuracy and resolution, which can further be used to derive the water depth based on wave theory. In this study, an “indirect” method to determine water depth is proposed using airborne lidar measured water surface points. As the wavelength and wave direction can be accurately tracked from the water surface topography, a $20\times20$ m underwater topography near Ganquan Island, South China Sea, is generated with a root mean square error (RMSE) of 0.91 m and a mean absolute percent error (MAPE) of 7.1%. The basic theory of deriving water depths is totally different from airborne lidar bathymetry (ALB), i.e., this method is independent of water clarity and can be used in turbid waters or even works with near infrared airborne lidar that can only obtain water surface points. [ABSTRACT FROM AUTHOR]

The article solves the problem of theoretically determining the deformable characteristics of railway ballast, considering its condition through mathematical modeling. Different tasks require mathematical models with different levels of detail of certain elements. After a certain limit, excessive detailing only worsens the quality of the model. Therefore, for many problems of the interaction between the track and the rolling stock, it is sufficient to describe the ballast as a homogeneous isotropic layer with a vertical elastic deformation. The elastic deformation of the ballast is formed by the deviation of individual elements; the ballast may have pollutants, the ballast may have places with different levels of compaction, etc. To be able to determine the general characteristics of the layer, a dynamic model of the stress–strain state of the system based on the dynamic problem of the theory of elasticity is applied. The reaction of the ballast to the dynamic load is modeled through the passage of elastic deformation waves. The given results can be applied in the models of the railway track in the other direction as initial data regarding the ballast layer. [ABSTRACT FROM AUTHOR]

This paper introduces a new theory in temporal ontology, 'wave theory', and argues for its attractions over and above existing tensed theories of time. [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]

To get a deeper understanding on the synergistic enhancement effect of low frequency artificial seismic wave on foam stability, a micro-kinetic model of enhanced foam stability under low frequency artificial seismic wave is established based on a vertical liquid film drainage model and elastic wave theory. The model is solved by non-dimensional transformation of the high order partial differential equations and a compound solution of implicit and explicit differences and is verified to be accurate. The foam film thickness, surfactant concentration distribution and drainage velocity under the action of low frequency artificial seismic wave are quantitatively analyzed. The research shows that low-frequency vibration can reduce the difference between the maximum and minimum concentrations of surfactant in the foam liquid film at the later stage of drainage, enhance the effect of Marangoni effect, and improve the stability of the foam liquid film. When the vibration frequency is close to the natural frequency of the foam liquid film, the vibration effect is the best, and the best vibration frequency is about 50 Hz. The higher the vibration acceleration, the faster the recovery rate of surfactant concentration in the foam liquid film is. The higher the vibration acceleration, the stronger the ability of Marangoni effect to delay the drainage of foam liquid film and the better the foam stability is. It is not the higher the vibration acceleration, the better. The best vibration acceleration is about 0.5 times of gravity acceleration. Reasonable vibration parameters would greatly enhance the effect of Marangoni effect. The smaller the initial concentration of surfactant, the better the vibration works in enhancing Marangoni effect.

Copyright of International Journal on Criminology is the property of Policy Studies Organization and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Objectives]Resonance Changer (RC) is an effective vibration damping device,which receives much attention in the field of longitudinal vibration control of marine shafting. As the RC's damping effect is closely related to the internal structural parameters,[Methods]an analytical formula of sound pressure propagation in RC was derived based on the wave theory,and the physical relationship between the internal structural parameters and its vibration mechanism was constructed for engineering design. Then,the influence of design parameters of RC's external pipes and cavity on system insertion losses and sound pressure level in broad band as well as the sensitivity were analyzed.[Results]The results show that,RCs can control the resonance peak of the main system well at its natural frequency.[Conclusions]Attention should be paid to the external pipe size of RCs when considering the feature line spectrum suppression,and to the external cavity size when considering the overall control of sound pressure level in broad band.

Elastic parameters are important parameters in the study of shale anisotropy, exploration, and development, and their accuracy is of great significance. In this study, shale in the lower Silurian Longmaxi Formation of southeastern Chongqing was investigated by obtaining the acoustic velocity of the partial bedding angle through an acoustic transmission experiment based on the elastic wave theory of the VTI medium and the least squares method, thus establishing a shale elastic parameter inversion method for improved accuracy. Results found that (1) the stratification angle was negatively correlated with the wave velocity; (2) velocity results calculated using the inversion-obtained elastic parameter were consistent with the measured results, with a maximum relative error of less than 1.52%, demonstrating that elastic parameters obtained by the proposed inversion method are valid; and (3) Longmaxi Formation shale has strong anisotropy, with the most significant direction of shear wave splitting being the direction in which the bedding angle is 0°. The results of this study provide a working foundation for using acoustic logging data to more accurately obtain the elastic parameters of shale and to study shale anisotropy characteristics, which have important theoretical value and practical significance. [ABSTRACT FROM AUTHOR]

The paper analyzes the two theories of conducted light signal for Bragg fiber with high-index core, namely total internal reflection and photonic bandgap. From the perspective of the wave equation, the distribution of the electromagnetic field and the conditions for forming the guided mode when the optical signal is transmitted in the core of fiber are explained. The analysis of photonic bandgap adopts the band structure principle of natural crystals for analogy. Then, the formation process of the photonic bandgap is elaborated on.

Featured Application: Main gas and oil pipelines are critical elements of the world's infrastructure. The integrity of pipelines during earthquakes is a subject of intensive research. At present, underground pipelines' strength to the effect of seismic loads (seismic resistance) is calculated incorrectly. The existing methods do not consider seismic (dynamic) pressure, i.e., the stress normal to the pipeline's outer surface arising from the propagation of a seismic wave in the soil. This leads to an incorrect determination of the pipeline's stress; the longitudinal stress calculations leads to errors of 100% or more. A potential application of the results obtained is the calculation of seismic stability of underground pipelines. The object of the research is an underground straight horizontal pipeline subjected to seismic impact. The research method was analytical. The results were compared with the experimental results of other authors and computer calculations. It was shown that the main disadvantage of the dynamic theory of seismic resistance of underground pipelines is the neglect of the dynamic stress state in soil under seismic wave propagation. The next drawback of the dynamic theory is an inaccurate, approximate accounting for the displacement of the soil medium to which the underground pipeline is embedded. The complete interaction process includes the stages of nonlinear changes in the interaction force (the friction force) by manifesting its peak value and the Coulomb friction. The contact layer of soil undergoes shear deformations until complete structural destruction of the soil contact layer. The interaction force is the friction force, and its peak value does not appear. The seismic resistance of underground pipelines should be considered based on the theory of propagating seismic waves in a soil medium and the interaction of seismic waves with underground pipelines, i.e., based on the wave theory of seismic resistance of underground pipelines. A one-dimensional coupled problem of seismic resistance of underground pipelines under seismic impacts was posed based on the wave theory. An algorithm and a program for the numerical solution of the stated wave problems were developed using the method of characteristics and the method of finite differences. An analysis of the laws of interaction of underground pipelines with soil under seismic influences shows that it is necessary to use in the calculations the laws of interaction that account for the complete interaction processes observed in experiments. The analysis of the obtained numerical solutions and the posed coupled problems of the wave theory of seismic resistance of underground pipelines show the occurrence mechanisms of longitudinal stresses in underground pipelines under seismic influences. The results of calculations stated that an account for the dynamic stress normal to the underground pipeline's outer surface leads to multiple increases in longitudinal stress in the underground pipeline. This multiple increase is due to the transformation of the interaction force into an active frictional force, resulting from a greater strain in soil than the one in the underground pipeline. Based on the analysis results, a theory of the seismic wave propagation process in an underground pipeline and surrounding soil was proposed. [ABSTRACT FROM AUTHOR]

Under conditions when the particles' thermal gyro-radii are smaller than the Debye length λ D , the magnetic field influence on the collision dynamics and associated transport processes becomes significant and has to be considered. In this paper, derivation of the kinetic equation based on the Fokker–Planck approach is reviewed for uniform magnetized plasmas with ρ the < λ D < ρ thi , where ρ the and ρ thi are the electron and ion thermal gyro-radii, respectively. Generally speaking, current tokamak plasmas lie in the above studied parameter range. Serving as an example for the application of the derived magnetized kinetic equation and demonstrating the modifications to the transport coefficients from a strong magnetic field, the electron-ion temperature relaxation is reviewed. The relaxation time exhibits a noticeable magnetic field dependence. [ABSTRACT FROM AUTHOR]

Within Terrorism Studies, Rapoport, D. C.'s (2004. The Four Waves of Modern Terrorism. In A. Cronin, & J. Ludes (Eds.), Attacking Terrorism: Elements of a Grand Strategy (pp. 47–65). Washington, DC: Georgetown University Press.) Wave Theory is a theoretical landmark that covers modern terrorism since 1880. However, this masterpiece neglects Eco-Terrorism, a phenomenon starred by the Animal Liberation Front (ALF), the Earth Liberation Front (ELF) and some other ideologically similar organizations. Even though it has been catching authorities' attention around the world, such negligence towards the phenomenon has been replicated by others working on Rapoport's Wave Theory, leaving a question unaddressed: 'Was/Is there an 'Eco-Terrorist Wave'?' Methodologically built upon a Time Series analysis on the Global Terrorism Database (GTD) (1970–2017), the present research harmonizes Eco-Terrorism under Rapoport's Wave Theory. Based on the evidence collected, the phenomenon has been evolving in a Rapoportian 'Wave-Like' pattern since 1972. [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]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The object of the research is an underground straight horizontal pipeline subjected to seismic impact. The research method was analytical. The results were compared with the experimental results of other authors and computer calculations. It was shown that the main disadvantage of the dynamic theory of seismic resistance of underground pipelines is the neglect of the dynamic stress state in soil under seismic wave propagation. The next drawback of the dynamic theory is an inaccurate, approximate accounting for the displacement of the soil medium to which the underground pipeline is embedded. The complete interaction process includes the stages of nonlinear changes in the interaction force (the friction force) by manifesting its peak value and the Coulomb friction. The contact layer of soil undergoes shear deformations until complete structural destruction of the soil contact layer. The interaction force is the friction force, and its peak value does not appear. The seismic resistance of underground pipelines should be considered based on the theory of propagating seismic waves in a soil medium and the interaction of seismic waves with underground pipelines, i.e., based on the wave theory of seismic resistance of underground pipelines. A one-dimensional coupled problem of seismic resistance of underground pipelines under seismic impacts was posed based on the wave theory. An algorithm and a program for the numerical solution of the stated wave problems were developed using the method of characteristics and the method of finite differences. An analysis of the laws of interaction of underground pipelines with soil under seismic influences shows that it is necessary to use in the calculations the laws of interaction that account for the complete interaction processes observed in experiments. The analysis of the obtained numerical solutions and the posed coupled problems of the wave theory of seismic resistance of underground pipelines show the occurrence mechanisms of longitudinal stresses in underground pipelines under seismic influences. The results of calculations stated that an account for the dynamic stress normal to the underground pipeline’s outer surface leads to multiple increases in longitudinal stress in the underground pipeline. This multiple increase is due to the transformation of the interaction force into an active frictional force, resulting from a greater strain in soil than the one in the underground pipeline. Based on the analysis results, a theory of the seismic wave propagation process in an underground pipeline and surrounding soil was proposed.

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]

Subaerial landslide-generated impulse waves were investigated in a rectangular prismatic channel based on the Froude similarity criterion. Landslides were modeled with a deformable granular material, and were controlled by a landslide generator. Four dominant parameters, namely, the slide Froude number F, the relative landslide thickness S, the relative landslide length L and the landslide impact angle α, were determined using dimensional analysis. According to the experimental results, the initial flow regime of impulse waves was subdivided into separated and unseparated, and the length of the impulse wave generation zone was provided by empirical equations. Moreover, the wave types were classified as Stokes-like waves, cnoidal-like waves and solitary-like waves. On this basis, a relationship between the dominant parameters and wave types was developed. Furthermore, by taking the propagation characteristics of an impulse wave, such as its amplitude, wave height and period, into consideration, an equation for the free surface was presented for estimating the Stokes-like waves. These semi-theoretical free surfaces were in good agreement with the experimental data. [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]

Copyright of Scientific Bulletin of National Mining University is the property of National Mining University, State Higher Educational Institution and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Zhengzhou University (Natural Science Edition) is the property of Journal of Zhengzhou University (Natural Science Edition) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

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.

[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]

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]

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]

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]

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]

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]

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]