Wave Zone Research Articles

Massive to gauge field reduction and gravitational wave zone information

We show explicitly that massive, Abelian, vector, just like (properly defined) massive tensor, fields limit smoothly to their massless, gauge, versions: they emit only maximal helicity radiation and mediate Coulomb and (special relativistic) Newtonian, forces between their (conserved) sources. Our main motivation, though, is to show that the recent gravitational wave detection probably cannot directly rule out very long-range gravity: Even though the waves were emitted in a strong field regime, their being detected in the weak field wave zone means the above equivalences apply. There remains the, not unlikely, possibility that no strong field generation of radiation in massive models can reproduce the observed ring-down patterns. Separately, the smooth linear limiting behaviors show that the discontinuity lies not in the mass alone, but rather in Abelian versus non-Abelian, Yang-Mills and General Relativity, regimes, whose respective massive versions are known to be non-physical.

Numerical modeling of 1D heterogeneous combustion in porous media under free convection taking into account dependence of permeability on porosity

Using numerical experiment the one-dimensional unsteady process of heterogeneous combustion in porous object under free convection is considered when the dependence of permeability on porosity is taken into account. The combustion is due to exothermic reaction between the fuel in the solid porous medium and oxidizer contained in the gas flowing through the porous object. In the present work the process is considered under natural convection, i.e. when the flow rate and velocity of the gas at the inlet to the porous objects are unknown, but the gas pressure at object boundaries is known. The influence of changing of permeability due to the changing of porosity on the solution is investigated using original numerical method, which is based on a combination of explicit and implicit finite-difference schemes. It was shown that taking into account the dependence of permeability on porosity, which is described by some known equations, can significantly change the solution in one-dimensional case. The changing of permeability due to the changing of porosity leads to the speed increasing of both cocurrent and the countercurrent combustion waves, and to the temperature increasing in the combustion zone of countercurrent combustion wave.

Inspiralling, nonprecessing, spinning black hole binary spacetime via asymptotic matching

We construct a new global, fully analytic, approximate spacetime which accurately describes the dynamics of non-precessing, spinning black hole binaries during the inspiral phase of the relativistic merger process. This approximate solution of the vacuum Einstein's equations can be obtained by asymptotically matching perturbed Kerr solutions near the two black holes to a post-Newtonian metric valid far from the two black holes. This metric is then matched to a post-Minkowskian metric even farther out in the wave zone. The procedure of asymptotic matching is generalized to be valid on all spatial hypersurfaces, instead of a small group of initial hypersurfaces discussed in previous works. This metric is well suited for long term dynamical simulations of spinning black hole binary spacetimes prior to merger, such as studies of circumbinary gas accretion which requires hundreds of binary orbits.

Numerical simulation of seismic wave field in graded geological media containing multiple cavities

In this study, we develop an efficient boundary integral equation method for estimation of seismic motion in a graded medium with multiple cavities under antiplane strain conditions. This inhomogeneous and heterogeneous medium is subjected to either time-harmonic incident shear seismic waves or to body waves radiating from a point seismic source. Three different types of soil material gradient are considered: (i) density and shear modulus vary proportionally as quadratic functions of depth, but the wave velocity remains constant; (ii) the soil material is viscoelastic, with a shear modulus and density that vary with respect to the spatial coordinates in an arbitrary fashion, so that the wave velocity is both frequency and position-dependent and (iii) the soil material has position-dependent shear modulus and constant density, yielding a linear profile for the wave velocity. Three different, frequency-dependent boundary integral equation schemes are respectively developed for the aforementioned three types of graded soil materials based on: (i) Green's function for the quadratically graded elastic half-plane; (ii) a fundamental solution for the viscoelastic full-plane with position-dependent wave speed profiles and (iii) a fundamental solution for an elastic full-plane with a linearly varying wave speed profile. Next, a number of cases involving geological media with position-dependent material properties and any number of cavities of various shapes and geometry are solved in the frequency domain. The numerical results reveal the dependency of the wave fields and zones of stress concentration on the following key factors: (i) type and properties of the soil material gradient; (ii) type and characteristics of the applied seismic load; (iii) shape, position and number of cavities and (iv) interaction phenomena between the cavities and the free surface.

Conceptual Foundations of Soliton Versus Particle Dualities Toward a Topological Model for Matter

The idea that fermions could be solitons was actually confirmed in theoretical models in 1975 in the case when the space-time is two-dimensional and with the sine-Gordon model. More precisely S. Coleman showed that two different classical models end up describing the same fermions particle, when the quantum theory is constructed. But in one model the fermion is a quantum excitation of the field and in the other model the particle is a soliton. Hence both points of view can be reconciliated.The principal aim in this paper is to exhibit a solutions of topological type for the fermions in the wave zone, where the equations of motion are non-linear field equations, i.e. using a model generalizing sine- Gordon model to four dimensions, and describe the solutions for linear and circular polarized waves. In other words, the paper treat fermions as topological excitations of a bosonic field.

Influences of the Cloud Shape of Fuel-Air Mixtures on the Overpressure Field

This paper presents an experiment system in the open field, which comprises a charge structure (approximately 166.2 kg), a high-speed camera subsystem, and a pressure measurement subsystem. Through a series of experiments under the cylindrical clouds with different diameters, heights, and diameter-to-height ratios (D : H), the influences of various cloud shapes on the overpressure field were analyzed and discussed. Based on the experimental results, the overpressure field was divided into two zones: detonation wave zone and shock wave zone. It is found that the overpressure of shock waves at the same distance from the explosion center increased with the diameters, but the variations of heights had little impact on the overpressure. Therefore, the pancake-shaped cloud of fuel-air mixtures is the optimal shape for obtaining the wider overpressure field. Moreover, it is found that the overpressure field gets the maximum under the diameter-to-height ratios of 5.7 in the same distance within the studied range.

Spectral characteristics of Acoustic Emission of rock based on Singular point of HHT Analysis

The sandstone test of uniaxial compression acoustic emission (AE) test has been studied, the HHT analysis is applied to AE signal processing, and through the analysis of AE signal to reveal the process of rock fracture. The results show that HHT is a method that based on principal component analysis of time-frequency analysis. The method of HHT can very convenient to deal the singular signal; it can be determine the main composition of singular signal. The instantaneous frequency can be used to describe precisely the time-frequency characteristics of singular signal. The method has a very important significance to reveal the frequency characteristics of AE signal. The EMD signal is decomposed into 8 IMF components in the failure process of rock sound. The component of IMF1 ~ IMF4 is the main component, and the IMF5 ~ IMF8 for low frequency noise signal. Through the EMD of AE signal frequency, the rock fracture has been decomposition into three stages: the initial zone, wave zone, quiet zone. This shows that in the analysis of rupture must eliminate noise interference signal characteristics of AE.

Investigation of parameters of terahertz pulses generated in single-domain LiNbO3 crystal by step-wise phase mask

A new scheme for the efficient generation of broadband terahertz radiation via optical rectification of femtosecond laser pulses in the single-domain lithium niobate crystal equipped with the step-wise phase mask (SPM) is investigated. It is shown that using the SPM one can provide the phase matching for all the spectral components of a terahertz pulse by providing the effective conversion of laser radiation in the terahertz region. The angular distribution of spectral components, as well as the temporal shape of terahertz pulses in the wave zone is studied. These results can be applied in the time-domain spectroscopy, the imaging of hidden objects, and etc.

Partition and growth of convection patterns in Poiseuille-Rayleigh-Bnard flow

The natural phenomena which we are familiar with, such as the convections in reservoir, ocean, atmosphere, etc., all occur in nonequilibrium open systems away from heat equilibria. The Poiseuille-Rayleigh-Bnard flow in a horizontal fluid layer heated from below has always been a typical experimental system for studying the nonlinear problem and the pattern formation. The experimental system can be accurately described by the full hydrodynamic equations. Therefore, the researches of the convection spatiotemporal structure, stability and the nonlinear dynamics by using the Poiseuille-Rayleigh-Bnard flow model possess certain representative and theoretical significance and practical value. So far, the investigation on the Poiseuille-Rayleigh-Bnard flow in a horizontal layer heated from below has concentrated mainly on the stability and made remarkable progress. However, a partition of convection pattern and growths of different patterns in the Poiseuille-Rayleigh-Bnard flow have been seldom studied in theory. By using a two-dimensional numerical simulation of the fully hydrodynamic equations in this paper, the research is conducted on the partition of convection pattern, growth and the effects of horizontal flow on the characteristic parameters of different patterns in the Poiseuille-Rayleigh-Bnard flow in a rectangular at an aspect ratio of 10. The SIMPLE algorithm is used to numerically simulate the two-dimensional fully hydrodynamic equations. The basic equations are solved in primitive variables in two-dimensional staggered grids with a uniform spatial resolution based on the control volume method. The power law scheme is used to treat the convective-diffusive terms in the discrete formulation. Results show that a flow zone is divided into three zones by the upper and lower critical Reynolds numbers Reu and Rel, i.e., traveling wave zone, localized traveling wave zone, and horizontal flow zone, where each of the Rel and Reu is a function of reduced Rayleigh number r and increases with increasing r. In the growth stage of the convection pattern, the growth processes of three kinds of patterns with time are different, but the convection rolls all start to grow from the downstream. The variations of characteristic parameters with time are also different, with maximum vertical velocity wmax and Nusselt number Nu of traveling wave and localized traveling wave entering into the stable stage of the cycle variation after the exponential growth stage, and the wmax and Nu of horizontal flow pattern decrease down to a stable constant after slow increase. The values of wmax and Nu of three types of patterns decrease with increasing Reynold number Re, with different laws being in the different pattern areas. In this paper, formulas for computing the Rel and Reu varying with r and formulas for computing the wmax and Nu varying with Re in different convection patterns are suggested.

Tracking the radiation reaction energy when charged bodies accelerate

We consider radiation reaction and energy conservation in classical electromagnetism. We first treat the well-known problem of energy accounting during radiation from a uniformly accelerating particle. This gives rise to the following paradox: when the self-force vanishes, the system providing the applied force does only enough work to give the particle its kinetic energy—so where does the energy that is eventually radiated away come from? We answer this question using a modern treatment of radiation reaction and self-force, as it appears in the expression due to Eliezer and Ford and O'Connell. We clarify the influence of the Schott force, and we find that the radiated power is 2q2a0·f0/(3mc3), which differs from Larmor's formula. Finally, we present a simple and highly visual argument that enables one to track the radiated energy without the need to appeal to the far field in the distant future (the “wave zone”).

Generation of acoustic waves by a vorticity wave in a shear flow

A two-dimensional problem of acoustic wave generation by initial distributions of vorticity in a shear flow is investigated. The case of a singular distribution of vorticity is considered, in which the vorticity is concentrated near one of the horizontal coordinates and is periodic with respect to the other coordinate. This distribution induces a periodic chain of localized vortices, the motion of which is accompanied by the radiation of acoustic waves. To find the parameters of acoustic radiation, a linearized system of gasdynamical equations is reduced to a single equation for the amplitude of the tangential velocity component. An asymptotic solution of this equation for weak velocity shear is represented in terms of the Airy function. The estimates of the wave amplitudes and the wave energy flux in the far wave zone are obtained.

Multiple-unit antennas on paraboloidal lattices of dielectric resonators

Introduction. Today a multiple-unit antenna properties, containing big number DRs are studied inefficiently. At present article a possibility of the antennas building produced on paraboloidal lattices consisting DRs of the cylindrical form with lowest magnetic type resonances is considered. The results. Calculation results of the antenna parameters on dielectric resonator paraboloidal lattices are presented. The space distribution of the radiation field patterns in the near and wave zones is considered. Reflection coefficient frequency dependence of the antennas is calculated. Possibility narrowing of the directional pattern is showed. Signals frequency selection performing as well as increased electromagnetic compatibility of the suggested structures is noticed. Conclusion. Adduced calculations indicate capability of the practical application lattices on DRs as well as building on their base a wide class of the frequency selective antennas in millimeter and sub millimeter wavelength ranges. Such antennas will have enhanced electromagnetic compatibility.

Characteristics of deep cyclones and extreme waves in the North Atlantic from the ERA-Interim reanalysis data

Analyzed is the relation of the trajectories of zones of hazardous waves in the North Atlantic to prevailing patterns of atmospheric circulation basing on the ERA-Interim reanalysis data. It is demonstrated that these trajectories depend on the combination of the phases of the North Atlantic and East Atlantic oscillations. Obtained are the characteristics of deep cyclones in the North Atlantic in winter (December–February) in 1989–2008.

Internal tidal fronts in the coastal zone of the Japan Sea

Presented are the results of the studies of internal tidal fronts in the coastal zone of the Japan Sea carried out in October 2012 using the anchored buoy stations which were installed on the route situated along the normal to the isobaths of the coastal zone. The analysis demonstrated that there are fast-moving internal tidal fronts in the field of coastal water temperature. These fronts represent the lifting of the thermocline limited in space and reaching 1/3 of the depth of the coastal zone with the steep leading edge and with the nonstationary wave zone adjoining it. This zone is filled with high-frequency pulsations having the periods of 3–5 minutes and amplitudes up to 10 m. It is revealed that internal tidal fronts propagate with the velocity of the first mode of the internal wave and with the frequency of the tidal harmonic M2. They are the highly nonlinear formations (the parameter of nonlinearity is ∼0.3) filled with high-frequency (the frequency ω ∼ 20 cycle/hour) amplitude-modulated disturbances with the steepness of the wave front of ∼8 cm/s; their length is ∼1 km.

Instantaneous Rock Blasting Wave and Its Microscopic Characteristics during Interaction with Concrete

This paper uses improved technology for dynamic strain measurement to investigate the dynamic strain signals of blasting wave action tested in the range of 8–16 cm from the central blast. Based on the blasting mechanism and on the analysis of signal characteristics, blasting waves are recognized and divided into three zones, namely, shock wave zone, stress wave zone, and gas-expanding zone. This paper studies the relationships between stress, strain, and time of every zone. The tensile and compressive stresses of stress wave are considered. After the blasting test, four cracks from the borehole center toward the minimum burden appear at the model surface. The relationship between blasting wave and concrete damage is analyzed.

Gravitational wave recoils in non-axisymmetric Robinson–Trautman spacetimes

We examine the gravitational wave recoil waves and the associated net kick velocities in non-axisymmetric Robinson-Trautman spacetimes. We use characteristic initial data for the dynamics corresponding to non-head-on collisions of black holes. We make a parameter study of the kick distributions, corresponding to an extended range of the incidence angle $\rho_0$ in the initial data. For the range of $\rho_0$ examined ($3^{\circ} \leq \rho_0 \leq 110^{\circ}$) the kick distributions as a function of the symmetric mass parameter $\eta$ satisfy a law obtained from an empirical modification of the Fitchett law, with a parameter $C$ that accounts for the non-zero net gravitational momentum wave fluxes for the equal mass case. The law fits accurately the kick distributions for the range of $\rho_0$ examined, with a rms normalized error of the order of $5 \%$. For the equal mass case the nonzero net gravitational wave momentum flux increases as $\rho_0$ increases, up to $\rho_0 \simeq 55^{\circ}$ beyond which it decreases. The maximum net kick velocity is about $190 {\rm km/s}$ for for the boost parameter considered. For $\rho_0 \geq 50^{\circ}$ the distribution is a monotonous function of $\eta$. The angular patterns of the gravitational waves emitted are examined. Our analysis includes the two polarization modes present in wave zone curvature.

Experimental study of circulation flow in a light dispersion hydrocyclone

The circulation flow, in light dispersion hydrocyclones and the effects of various parameters on this flow were studied quantitatively through measurements of the axial velocity field. A phase Doppler particle analyzer (PDPA) system was developed to measure the axial velocity field in axial cross sections in ∅ 35mm hydrocyclones with various vortex finders lengths, overflow orifice diameters, cone angles, inlet flow rates, and split ratios. The results showed that the zero-axial-velocity wave zone (ZAVWZ), which is responsible for the coupling of circular and closed flow in most axial cross sections, is caused by the velocity gradient and can be described as the location of the circulation flow. The mechanism of circulation flow and cyclone separation was revealed by the formation mechanism of the circulation flow. A new equation for calculating the circulation flow rate is proposed. By studying the effects of the geometric and operating parameters on the circulation flow, it was observed that smaller distribution areas and rates of circulation flow usually result in higher separation efficiency in a hydrocyclone.

Insights from archaeological analysis and interpretation of marine data sets to inform marine cultural heritage management and planning of wave and tidal energy development for Orkney Waters and the Pentland Firth, NE Scotland

The Orkney archipelago has a rich heritage that includes the Heart of Neolithic Orkney World Heritage Site, Viking settlements, harbours supplying Hudson's Bay Company ships, and the wartime naval base of Scapa Flow. This rich history has left its mark on the seabed but accurate maps showing the location and character of surviving seabed archaeology do not exist to the same extent as for archaeology on land. ORCA Marine was commissioned by Historic Scotland to work with the Royal Commission on the Ancient and Historical Monuments of Scotland in interrogating marine data sets to enhance historic environment records of Orkney Waters and the Pentland Firth. These waters were prioritised for their history of maritime activity and to help guide planning and developments in an area highlighted by the Scottish Government for marine renewable energy.A variety of recent and legacy datasets, including wreck databases; sonar data gathered by public sector bodies; aerial photography; seabed cores; Admiralty charts; and local knowledge, were examined for their effectiveness in discovering and interpreting marine cultural heritage cost-effectively. A methodology was developed that enabled marine cultural heritage information to be quickly assimilated within the national and regional inventories for dissemination online. Polygonisation of records resulted in GIS-based shapefiles identifying site extents, and areas of archaeological potential in relation to wrecks, submerged prehistoric landscapes, anchorages and fishing areas.Substantial gaps in data coverage were identified and areas of the seabed have been surveyed at resolutions that are sufficient to detect large upstanding remains such as iron shipwrecks but insufficient to identify smaller archaeological features. Other geophysical datasets have been created at a resolution detailed enough to allow the recognition of smaller anomalies but in some cases processing of the data has removed small anomalies of interest to archaeologists. Intensively used marine areas often contain the most artefactual remains such as historic ports being developed to service the marine renewable industry. Zones of high wave and tidal energy favoured for renewable energy devices include navigation channels and hazards where a large number of wrecks are documented. Transmission cable routes cross deep water where 20th-century wartime losses occurred. Planning and development of infrastructure relating to renewables may also interact with significant built heritage and archaeology on the foreshore and coast edge.

Note on Coriolis-Stokes force and energy

In this study, we consider the origin of the Coriolis-Stokes (CS) force in the wave-averaged momentum and energy equations and make a short analysis of possible energy input to the ocean circulation (i.e., Eulerian mean velocity) from the CS force. Essentially, we find that the CS force appears naturally when considering vertically integrated quantities and that the CS force will not provide any energy input into the system for this case. However, by including the “Hasselmann force”, we show some inconsistencies regarding the vertical structure of the CS force in the Eulerian framework and find that there is a distinct vertical structure of the energy input and that the net input strongly depends on whether the wave zone is included in the analysis or not. We therefore question the introduction of the “Hasselmann force” into the system of equations, as the CS force appears naturally in the vertically integrated equations or when Lagrangian vertical coordinates are used.

Simulations of Transition Radiation from a Flat Target using CST Particle Studio

Numerical simulations of Backward Transition Radiation originating from a flat ideally conducting target inclined at 45 degrees with respect to a charge propagation direction are presented in this paper. The simulation results are compared with the theory for the wave and pre-wave zones. The main characteristics of the simulated radiation distributions are discussed in detail.