A spin polarized disc

We present a solution to the gravitational field equations in a Riemann-Cartan spacetime. The solution describes a disc of infinite radius and finite thickness. The solution has three forms which depend on the size of the acceleration. The matter content of the disc is a rotating spin fluid with a constant z acceleration and a spin density polarized along the axis of rotation. The fluid has zero axial and tangential pressures. There is a radial pressure. The energy density and pressure are finite within the disc.     

Dispersion transition and the nonergodicity of the disordered nanoporous medium-nonwetting liquid system

The experiments in which a nonwetting liquid does not flow from a disordered nanoporous medium are described. The outflow is shown to depend on the degree of filling of the porous medium and its temperature in a critical manner. A physical mechanism is proposed where the transition of a system of liquid nanoclusters in a confinement into a metastable state in narrow filling and temperature ranges results from the appearance of a potential barrier due to the fluctuations of the collective “multiparticle” interaction of liquid nanoclusters in neighboring pores of different sizes at the shell of a percolation cluster of filled pores. The energy of a metastable state forms a potential relief with numerous maxima and minima in the space of a porous medium. The dispersed liquid volume in a metastable state is calculated with an analytical percolation theory for a ground state with an infinite percolation cluster. The outflow time distribution function of pores is calculated, and a power law is obtained for the decrease in nonwetting liquid volume retained in a porous medium with increasing time. The relaxation of the system under study is a multistage process accompanied by discontinuous equilibrium and overcoming of numerous local maxima of a potential relief. The formation of the metastable state of retained nonwetting liquid results from the nonergodicity properties of a disordered porous medium. The proposed model can describe the detected dependences of dispersed liquid volume on the degree of filling and temperature.     

Vibrations of double-string complex system under moving forces. Closed solutions

In this paper the dynamic response of a double-string system traversed by a constant or a harmonically oscillating moving force is considered. The force is moving with a constant velocity on the top string. The strings are identical, parallel, one upon the other and continuously coupled by a linear Winkler elastic element. The classical solution of the response of a double-string system subjected to a force moving with a constant velocity has a form of an infinite series. The main goal of this paper is to show that in the considered case a part of the solution can be presented in a closed, analytical form instead of an infinite series. The presented method of finding the solution in a closed, analytical form is based on the observation that the solution of the system of partial differential equations in the form of an infinite series is also a solution of an appropriate system of ordinary differential equations.     

Radiation impedance of a piston at the wall of a rectangular duct

The radiation impedance of a rectangular piston positioned at the wall of a rectangular duct is theoretically investigated. The dependence of the attached length of the piston on the width of the duct is determined. The dependence shows that, unlike the radiation resistance, the attached length decreases with a decrease in duct width. The results of the study are compared with the data obtained for the attached length of a square orifice in a rectangular baffle in a duct.     

Measuring Light Field of Light Source with High Directional Resolution Using Mirrored Ball and Pinhole Camera

This paper presents a method of measuring a light field of a light source with high directional resolution using a mirrored ball and a pinhole camera. The light field describes a spatial and directional distribution of radiances from the light source. The directional distribution is expanded by a reflection on the mirrored ball, and the radiances are measured by a charge-coupled device (CCD) camera with a pinhole lens. The light source is laterally moved by a robot arm to measure the directionally expanded light field, and each pixel on a CCD can obtain the radiances from the light source through the pinhole lens with high directional resolution. The light field is estimated from the pixel value and the position of each pixel using a ray tracing technique. The light field of a krypton lamp was experimentally measured by the proposed method, and the accuracy of the measurement was evaluated against the irradiances measured by a spectro-radiometer at sample points.     

Effect of interference pattern on femtosecond laser-induced ripple structure

Combined structures composed of a micron-sized periodic structure and a nano-sized quasi-periodic ripple structure were generated by a single process of multiple shots of an interfering femtosecond laser. The former structure was generated by an interference pattern and controlled by a number of beams. The latter structure was generated by a multiple shot method. As a result, multiple periodic structures were generated. The periodicity of the structures was analyzed by two-dimensional (2D) fast Fourier transform (FFT). The most probable period of ripple structure was downsized to 177 nm by restricting irradiated region by a TM wave interference pattern. The smallest period was 105 nm. The dispersion angle of a ripple decreased to about 50%. The period and direction of the ripples were for a first time controlled by using interference.     

Fragmentation experiment and model for falling mercury drops

The experiment consists of counting and measuring the size of the many fragments observed after the fall of a mercury drop on the floor. The size distribution follows a power-law for large enough fragments. We address the question of a possible crossover to a second, different power-law for small enough fragments. Two series of experiments were performed. The first uses a traditional film photographic camera, and the picture is later treated on a computer in order to count the fragments and classify them according to their sizes. The second uses a modern digital camera. The first approach has the advantage of a better resolution for small fragment sizes. The second, although with a poorer size resolution, is more reliable concerning the counting of all fragments up to its resolution limit. Both together clearly indicate the real existence of the quoted crossover.     

Use of a joint transform correlator architecture for study of speckle displacements

The optical speckle–displacement correlation technique (OSDCT) is proposed for study of in-plane speckle displacements. The joint transform correlator architecture is used to evaluate the displacements of speckle subimages of strained surfaces. The procedure of the correlation response producing as a result of cross-correlation of strainless and strained surfaces in a conventional joint transform correlator (JTC) is considered. The convenient techniques for a joint power spectrum transformation are selected. The systematic and random errors of a mean speckle pattern displacement of a rigid body motion calculated by using the OSDCT and the digital speckle–displacement measurement technique are compared. The robustness of some JTC versions (a conventional JTC, a JTC with median thresholding, a JTC with subset median thresholding, and a fringe adjusted filter JTC) to input noise of speckle patterns and output noise of a correlation response is studied.     

Formation of a misorientation band in the elastic field of a disclination dipole

The formation of a misorientation band in the elastic field of a disclination dipole is considered and simulated using a kinetic approach. The dipole is artificially located on a grain boundary or induced by plastic deformation on a double ledge in a grain boundary in a bicrystal. The simulation results agree well with the results obtained earlier in a continuum approximation. The dislocation structure of the misorientation band that forms during accommodation slip is shown to be a dynamic steady-state structure, and its appearance has a kinetic nature.     

Optical pulse velocity and frequency variations during cascade parametric interaction with a high powered reference pulse

The effect of a frequency shift and time delay during the cascade parametric interaction of a weak signal pulse with a high powered reference pulse is demonstrated for the first time. The conditions of total reflection of a pulse signal in a crystal with quadratic nonlinearity are found. The equation for the frequency shift of a reflected wave is derived.     

Pressure dependence of the electrical potential and electrontemperature in a microwave-generated plasma

The electron temperature in a stationary hydrogen plasma has been studied using a Langmuir probe. The measurements have been carried out over the pressure range from 3 mbar (2.25 torr) to 25 mbar (18.75 torr). The applied microwave power was varied from 50 to 450 W. The electron temperature shows a linear dependence on the applied microwave power. The self-space-charge field (in volts) of a hydrogen plasma shows a saturation behavior at higher microwave powers. The maximum value at the saturation of the field equals 6.8 V at a gas pressure of 15 mbar (11.25 torr) for all values of the input microwave radiation power. The polarities of the self-space-charge electric field are similar above this value and below it     

The trapping of potassium atoms by a polycrystalline tungsten surface as a function of energy and angle of incidence

The trapping probability of potassium atoms on a polycrystalline tungsten surface has been measured as a function of the angle of incidence and as a function of the energy of the incoming atoms. Below an energy of 1 eV the trapping was complete; above 20 eV only reflection occurred. The trapping probability increased with increasing angle of incidence. The measurements are compared with a simple model of the fraction of atoms initially trapped. The model, a one-dimensional cube model including a Boltzmann distribution of the velocities of oscillating surface atoms, partially explains the data. The trapping probability as a function of incoming energy is well described for normal incidence, justifying the inclusion of thermal motion of the surface atoms in the model. The angular dependence can be explained in a qualitative way, although there is a substantial discrepancy for large angles of incidence, showing the presence of surface structure.     

Volt-ampere characteristics of a nitrogen DC plasma arc with anode melting

The characteristics of a nitrogen arc using a graphite cathode and a melting anode in a pilot-scale plasma furnace are investigated. The voltage is examined as a function of current and apparent plasma length. The voltage increases non-linearly with the increase of apparent plasma length, with the current fixed. The experimental data so obtained are compared with the predictions of the Bowman model for the electric arc, and with numerical simulations as well. The level of agreement between the experimental data at the melting anode and the numerical predictions confirms the suitability of the proposed the Bowman model. These characteristics are relevant to the engineering design and evaluation of a DC plasma furnace and reactor for the treatment of hazardous fly ash waste.     

A spherical plasmoid with a diffuse boundary in a linearly polarized quasistatic electromagnetic field

The problem of a spherically symmetric plasmoid placed in a linearly polarized uniform quasistatic electromagnetic field is considered. The electric field in the vicinity of a plasmoid with a Gaussian electron density distribution is calculated. The results of calculations are compared with the known solution for a spherical plasmoid with a uniform density. The possibility of the transformation of an initial plasmoid that arises in an electrodeless microwave gas discharge into a microwave streamer is discussed.     

The effect of the nonparabolicity of the free carriers dispersion law on the propagation of surface polaritons in a semiconductor-metal structure

The results of a study on the influence of the nonparabolicity of the free carriers dispersion law on the propagation of surface polaritons (SPs) located near the interface between an n-type semiconductor and a metal arc reported. The semiconductor plasma is assumed to be warm and nonisothermal. The nonparabolicity of the electron dispersion law has two effects. The first one is associated with nonlinear self-interaction of the SPs. The nonlinear dispersion equation and the nonlinear Schrodinger equation for the amplitude of the SP envelope are obtained. The nonlinear evolution of the SP is studied on the base of the above mentioned equations. The second effect results in third harmonics generation. Analysis shows that these third harmonics may appear as a pure surface polariton, a pseudosurface polariton, or a superposition of a volume wave and a SP depending on the wave frequency, electron density and lattice dielectric constant.     

Heat bath coupling effects on interaction between Fröhlich vibration systems

The energy supplied to the Fröhlich vibration system in a living cell may condense in certain normal modes provided the coupling of the vibration system with a heat bath is nonlinear. The strong coupling of a coherent vibration system with a heat bath causes reduced energy condensation; high frequency modes are not excited and the energy condensed in the lowest frequency mode is smaller than the energy condensed in a system with weak coupling. The vibrations are polar and generate an electromagnetic field. The electromagnetic field mediates a long range interaction between the Fröhlich vibration systems; the interaction depends on the intensity of the generated electromagnetic field, and, therefore, on the energy condensed in the vibration system. The systems with strong coupling with a heat bath have weak interaction forces, which may be attractive as well as repulsive. The effect of coupling with a heat bath on interaction between the Fröhlich systems is a new contribution of this paper. The coherent vibration systems are assumed to be excited in protein molecules in cellular membranes. Protein phosphorylation may cause the strong Coulomb coupling of vibration systems with a heat bath and may have a fundamental effect on energy condensation.The work was supported, in part, by grant COST 244.     

Resonantly enhanced strip-line technique to measure microwave permeability of thin films

The sensitivity of a reflective single-port strip-line technique is increased by 10-20 times by amplification of a measured reflectivity response at a set of resonance frequencies. The resonant behavior is organized by connecting the strip cell to a network analyzer through a capacitor with a long coaxial cable. The capacitance defines the amplification; the cable length defines the resonance frequencies. S-parameters of the coaxial-to-strip junction and the field inhomogeneity inside the cell are accounted for by a reference measurement of sample with known constitutive parameters. Two methods for permeability calculation are suggested. The fist method is based on the comparison of Lorentzian parameters of resonance reflectivity curves. The second method is based on numerical solution of Fresnel's equation. The enhancement is essential at low-frequency part of the band, where the cell reflectivity is close to unity and the sensitivity of non-resonant technique is poor. The technique sensitivity is estimated by permeability measurements of Al stripes with different cross-section.     

On the interaction of a sound pulse with the shear layer of an axisymmetric jet,II: Heated jets

The fluctuating field of a heated jet excited by a sound pulse is simulated numerically. The fluctuations in both the flow field and the far field are studied. The flow field results depend crucially on the stability properties of the heated jet. The altered stability properties due to the heating cause a reduction in the overall fluctuations and a shift of the instability waves into lower frequencies. These changes cause a similar downward shift in the far field spectrum and a reduction in the total far field noise. The results provide a partial explanation in terms of stability theory of experimentally observed properties of the noise of heated jets.     

Single Photon Scattering in a Pair of Waveguides Coupled by a Whispering-Gallery Resonator Interacting with a Semiconductor Quantum Dot

The single photon scattering properties in a pair of waveguides coupled by a whispering-gallery resonator interacting with a semiconductor quantum dot are investigated theoretically.The two waveguides support four possible ports for an incident single photon.The quantum dot is considered a V-type system.The incident direction-dependent single photon scattering properties are studied and equal-output probability from the four ports for a single photon incident is discussed.The influences of backscattering between the two modes of the whispering-gallery resonator for incident direction-dependent single photon scattering properties are also presented.