Showing papers on "Slab published in 1974"

Slab-coupled waveguides

Abstract: The slab-coupled waveguide, consisting of a dielectric rod lying on a slab that in turn covers a substrate, is a multidielectric waveguide that includes such special cases as the single-material fiber, the rib waveguide, and the strip-loaded film guide. These guides have recently become known as potentially useful either for long-distance optical transmission or for integrated optics. Simple, closed-form, approximate solutions have been found to describe the following properties of the guide: number of modes, their field configurations and propagation constants, numerical aperture, requirements for single-mode operation, field penetration in the slab, tolerance to curvature of the guide axis, dispersion, and impulse response.

Numerical Modelling of Tectonic Flow behind Island Arcs

Abstract: Suniniary High heat flow in marginal basins and island arc volcanism are explained by numerical modelling of flow induced by the downgoing slab. The hypothesis that frictional heating above the slab causes thermal diapirs to rise is mechanically unfeasible since the region above the slab must be fluid enough to convect thermally, yet so viscous that the motion of the slab produces over 2 kilobars of stress. The calculation of induced flow is two-dimensional, time dependent, with a variable viscosity dependent on temperature and pressure. A yield stress was used to approximate fault dislocations. The calculation is very sensitive to the material properties and to localized flow near the base of the interface between the slab and the landward plate. The highest stress occurred at the base of the slab interface. This area ablated creating a narrow channel necessary for separating melt from mostly crystalline mush to establish a source of volcanic magmas. In the marginal basin area, tensile yielding occurred in the plate causing it to thin and raise the heat flow significantly. The yielding continued until a complete rift occurred. Induced flow is, then, a likely explanation for island arc volcanics and high heat flow in marginal basins.

Surface Electromagnetic Modes of a Ferrite Slab

Abstract: The dispersion relationship describing the propagation of electromagnetic (EM) surface modes supported by a ferrite slab of finite thickness magnetized parallel to the planes of its air-ferrite-air or air-ferrite-metal interfaces is investigated. Surface wave propagation at frequencies greater than the ferrite-metal mode resonance is predicted for thick grounded ferrite slabs thereby clarifying prior results based upon semi-infinite and magnetostatic analyses. The relative energy densities of the electromagnetic surface modes is examined at the air-ferrite interfaces of an ungrounded slab.

Transverse coupling in fiber optics part III: Bending losses

Abstract: A general method is proposed to evaluate the radiation loss of bent open waveguides. This method consists in evaluating the coupling between the waveguide mode and the whispering-gallery modes that can be associated with the surrounding medium. The expression obtained for a reactive surface coincides with a previous result by Miller and Talanov.1 We investigate in detail the radiation loss of the fundamental (HE 11 ) mode of a dielectric rod coupled to a slab. This arrangement, described in Part II of this article series,2 provides a useful mode-selection technique. The radiation loss is given by a simple closed-form expression. We find that for a wavelength of 1 µm and a rod radius of 5 µm in physical contact with the slab, the bending loss is less than 1 dB/km if the radius of curvature, in the plane of the slab, exceeds 22 mm.

Analysis of Electromagnetic-Wave Modes in Anisotropic Slab Waveguide

Abstract: Electromagnetic-wave modes propagating in anisotropic slab waveguide are analyzed theoretically in detail The propagation conditions are derived under which waves can propagate along the axis of the guide A two-dimensional three-layered waveguiding structure consisting of an anisotropic dielectric slab coated on, or immersed in, isotropic surrounding substrate materials is considered as a typical configuration of the guide Field-intensity distributions of the propagating modes and their propagation constants are obtained by numerical computations Techniques for achieving the mode discrimination and the single-mode operation are given Some possible applications in integrated optics are suggested

Benchmark Values for the Slab and Sphere Criticality Problem in One-Group Neutron Transport Theory

Abstract: This paper contains benchmark data for the one-group criticality problem for the uniform slab and the uniform sphere in vacuum. The data which were obtained on the basis of the results of analytica...

Lightweight, reinforced foamed organic polymer and cementitious material structure

Abstract: A lightweight, reinforced structural material, having low density and high flexure and compression strengths, is prepared by combining together inorganic cementitious material and organic polymer-forming material to form a mixture and forming the mixture into a slab while embedding an elongate reinforcing members which are relatively rigid in the depth dimension of the slab. Polymerization and setting of the material tensions the reinforcing members.

Finite Element Analysis of Slabs on Elastic Solids

Abstract: A finite element method programmed for a high speed computer was developed for analyzing concrete slabs on an elastic continuum. The method differs from conventional in that an iterative scheme is employed. The iterative scheme has the major advantage of reducing the computer storage and can be used for analyzing two slabs with load transfer at the joint. A comparison between the finite element and the analytical solutions indicates that the finite element method is accurate enough for engineering applications. Comparisons of the stresses and deflections obtained by the method with those measured in the Arlington test for various conditions of loading and warping also show good agreements. It was found that the agreement based on full contact between the slab and the subgrade was not as good as that based on the assumption that part of the slab near to the edge is not in contact with the subgrade.

Modes in inhomogeneous slab waveguides

Abstract: In this correspondence we have developed the perturbation approach for the calculation of propagation constants for some of the practical slab waveguides and have shown the applicability of the approach to systems of practical interest.

Thermal Stresses in Chemically Hardening Elastic Media With Application to the Molding Process

Abstract: A method has been formulated for the determination of thermal stresses in materials which harden in the presence of an exothermic chemical reaction. Hardening is described by the transformation of the material from an inviscid liquid-like state into an elastic solid, where intermediate states consist of a mixture of the two, in a ratio which is determined by the degree of chemical reaction. The method is illustrated in terms of an infinite slab cast between two rigid mold surfaces. It is found that the stress component normal to the slab surfaces vanishes in the residual state, so that removal of the slab from the mold leaves the remaining residual stress unchanged. On the other hand, the residual stress component parallel to the slab surfaces does not vanish. Its distribution is described as a function of the parameters of the hardening process.

Effect of spatial dispersion on the S‐polarized optical properties of a slab dielectric

Abstract: A microscopic theory of the reflection, transmission, and absorption of S‐polarized light by a slab dielectric consisting of N planes of molecules is developed. The interactions between molecules are assumed to be of the point dipole type. The change in the internal and exciting electric fields in the surface planes is included since a rigorous solution of Maxwell's equations is obtained. The results of the macroscopic theory of Kliewer and Fuchs are recovered in the limit that dipole interactions between crystal planes are negligible compared to interactions within a plane. Calculations exploring the effects of spatial dispersion and slab thickness on the power spectra are described.

Perforated interlocking slab

Abstract: A perforated interlocking concrete slab, for example moulded from cement, intended for use for example for consolidating turfed areas or sloping banks, has an outline which includes portions that project and portions that are withdrawn with respect to a notional base line that forms a rectangle with sides twice as long as its ends are wide; the projections and withdrawn portions being arranged so that it is possible to lay against half the length of a side of the slab (regarded as extending from a corner) another like slab oriented at will either with its end abutting that half length or with half the length of its side abutting that half length, so that by their interengagement relative displacement longitudinally with respect to that half length is prevented; the perforations passing from the face to the back of the slab and being disposed in first rows that extend parallel to each other and in second rows that extend at right angles to the first rows and parallel to each other, the first and second rows extending obliquely with respect to the rectangular base line. The first rows of perforations can extend in the same direction as the diagonal of the rectangular base line (one of the first rows being situated on that diagonal). Recesses at the corners and midway of the longitudinal sides, combine in an array of such slabs to form perforations of like shape and area as the perforations of the slab.

Process and apparatus for modifying the cross section of a slab

Abstract: There is disclosed a method and an apparatus for modifying the cross section of a metal slab, which may be a continuously cast slab coming from a caster, to prepare the slab for reduction to strip in a cyclic mill, e.g. a planetary mill. The slab is advanced at constant speed by independent means, while pairs of pressing tools are caused to operate on all four sides of the slab in repeated and coordinated reciprocating action. The thickness of the slab may be reduced as much as 70%, and the width may be maintained constant, or increased, or decreased as desired. The frame of the apparatus carries the shaft driven by suitable means; and the shaft has two pairs of eccentrics oriented at 180* to each other. Each pair of eccentrics actuates a pressing tool, one operating on the top of the slab, and one operating on the underside of the slab. As the pressing tools thus reciprocate they act on opposite sides of the slab to reduce its thickness. The tools are arranged for a slight rocking movement so that they do not retard the forward movement of the slab. Other tools are arranged in pairs to operate on opposed sides of the slab in a similar manner. For substantial widening of the slab the pressing tools may be disposed at an angle to the centerline of the entering slab.

Macro-and Micro-Structure of Continuously Cast Slab

Abstract: Synopsis: Macro-and micro-structure of continuously cast slab are studied. Macro-structure is mainly dependent on casting temperature. Because of its high solidification rate, macro-segregation hardly takes place. Macro-structure is composed of columnar dendrite, brached dendrite and equiaxed crystal. Micro-segregation takes place not only between dendrite stem and interdendrite, but also inside and outside of equi—axed crystal. Micro-segregation is causative of center line segregation of continuously cast slab when solute enriched melt is squeezed from interdendrite into cavity which is formed by solidification shrinkage or bulging of solidified shell by ferrostatic pressure. (Received May 16, 1973)

Method for manufacturing cold rolled, non-directional electrical steel sheets and strips having a high magnetic flux density

Abstract: A method for manufacturing cold rolled, nondirectional electrical steel sheets and strips having a high magnetic flux density wherein a molten steel is solidified to obtain a slab in a manner that columnar grains develop predominantly from the surface in the direction of thickness of the slab up to a depth of more than 50%; said slab is heated to a temperature above 1000°C without cogging and rolling to form γ-phase at least more than about 10% of said slab, and hot rolled strongly with a draft of more than 98% without reheating to obtain a hot rolled steel sheet; and said hot rolled steel sheet is cold rolled with a draft of 64 - 84%, heated with a heating velocity of more than 1.6°C/sec., and annealed at a temperature of 600° - 1200°C.

Magnetostatic Surface Waves in Ferrite Slab Adjacent to Semiconductor (Short Papers)

Abstract: Magnetostatic surface waves propagating along the ferrite slab adjacent to a semiconductor are discussed in this paper. Our numerical results indicate that the conductivity of the semiconductor plays an important role in the determination of the dispersion relation in the case of nondrifting carriers. The backward wave appears for a finite value of the conductivity.

Pulse spreading in multimode, planar, optical fibers

Abstract: A dielectric slab can keep optical beams confined transversely in its plane if it is tapered, with the slab thickness having a maximum along some straight line. When the square of the local wave number of the slab (k2) is a quadratic function of the transverse coordinate (y), the rays in the plane of the slab are sinusoids whose optical length is almost independent of the amplitude. For thin slabs (2d « λ) as well as for thick slabs (2d » λ), pulse spreading is large because the ratio of the local phase to group velocity is strongly dependent on the distance (y) from axis. We show that pulse spreading is almost negligible, however, if the thickness of the slab is properly chosen. For example, if the slab thickness on axis is 2.5 micrometers and the refractive index of the slab is 1 percent higher than that of the surrounding medium, pulse spreading is only 0.05 nanosecond per kilometer at a wavelength of 1 micrometer. Pulses in clad fibers having the same width (0.2 millimeter) and carrying the same number of modes (15) spread 50 times faster. Splicing and matching to injection lasers may be easier with planar fibers than with conventional fibers. Low-dispersion planar fibers are therefore attractive when used in conjunction with sources that are multimoded in one dimension. Closed-form expressions are given for square-law and linear-law profiles.

Wrapper for chocolate slab - opening seam along first break off position of slab

Abstract: A sleeve wrapper for slab shaped piece goods especially for chocolate slabs which can be broken up in individual bars includes a longitudinal seam (32) positioned along a first break off position (29) of the slab (10). In a square chocolate slab with preferably four strips the longitudinal seam (32) of the packing (23) is positioned between the first and the second strip (11, 12) of the slab. The longitudinal seam (32) is formed by two outwardly projecting flaps (24, 25) which are joined together along their inner surfaces (26, 27).

Slab-coupled optical waveguide

Abstract: This application describes an optical waveguide comprising an optical fiber having a refractive index n2 and diameter d, and a slab of refractive index n and thickness t. The fiber and slab are separated by a distance D by means of a dielectric material of refractive index n3, where n > n3 and n2 > n3. For a given group of materials, the guided modes are determined by the ratio of d to t. The loss per unit length for the leaky modes, and the loss experienced by the guided modes as the waveguide is bent in the plane of the slab is a function of D.

Method of vibration dampening by surface griding

Abstract: The invention refers to a method of vibration damping in order to reduce vibrations of supports of slabs, for surface grinding. Individual supports, regularly arranged over the surface of a grinding table consist of hydraulic cylinders communicating with each other and lockable in reached final positions in contact with the slab. Between groups of cylinders valves are arranged for accommodating the number of active cylinders to the size of the slab on the table.