Showing papers on "Slab published in 1969"

Flexure of a Floating Ice Tongue

Abstract: Several analyses are given for the flexure of a floating polar ice tongue with the general dimensions of several kilometers wide by 200 in in thickness The lengths considered are from 2 km to in excess of 10 km which is referred to as a long slab The analyses are made under the separate assumptions that ice behaves as (1) an elastic material, (2) an elastic-plastic material, and (3) a fully plastic material, when reacting to flexure due to changes in sea-level The elastic analysis shows that hinge-line stresses could become very high of the order of 15 bar) for slab lengths up to about 3·5 km reacting to sea-level changes of the order of ±50 cm For slab lengths greater than this, the stresses at the hinge, as well as being significantly less than before, become independent of the length of the slab, dependent only on the slab thickness and the amount of deflection of sea-level In the elastic-plastic analysis, the hinge-line stress cannot exceed a value of about 2 bar This yield value is reached when sea-level departs about 50 cm from the mean The fully plastic analysis requires more accurate knowledge of the constants in the flow law and their variation with density, temperature and salinity within the ice However, the theory may be tested by measuring the diurnal change in strain-rate across the hinge-line zone The process of calving of large tabular icebergs from such glacier tongues may demand sea-level changes of more than ± 1 m, or bending about more than one axis of the shelf

Plastic foam seat construction

Abstract: A vehicle seat made up of a supporting slab of relatively hard, high density elastomeric urethane foam and a cushion mounted on said supporting slab of relatively soft, low density elastomeric urethane foam that is softer and more compressible than the material of the supporting slab, with interlocking means between the cushion and slab for preventing relative sliding movement between the cushion and slab. The cushion and slab are detachably secured together against separation by a suitable pressure sensitive adhesive so that the cushion can be removed and replaced when damaged.

Radiative transport in finite homogenous cylinders by the Monte Carlo technique

Abstract: The transfer of resonance line radiation in homogeneous cylinders of various shapes and optical thicknesses is studied by means of the Monte Carlo method in order to investigate the effects of geometry on (non-LTE) source functions and emergent line intensity profiles. It is found that increasing the larger cylinder dimension (radius or length) produces no change in the source function except to extend it at a constant level. For cylinders with the same axial optical thickness as a slab, we find that the axial source function is effectively the same as that of a slab whenever the radius of the cylinder exceeds its length. Further, when the length exceeds the radius, the radial source function approximates the source function for a slab of optical thickness equal to that of the cylinder radius, provided this is less than a thermalization length. Emergent line shapes are calculated and are found to be strongly dependent upon the position and aspect. Scaling laws are given which permit estimation of the source function at an arbitrary point in a cylinder without a detailed solution of the transfer problem.

Reflection of a Plane Transient Electromagnetic Wave From a Cold Lossless Plasma Slab

Abstract: Reflection of a plane transient electromagnetic wave from a plasma half-space and a plasma slab is considered. The plasma is assumed to be cold and collisions are neglected. Under these assumptions, the Laplace transforms may be inverted exactly, yielding a solution in the form of Bessel function series. The numerical results, for the waveform of the reflected field, exhibit features that are easily related to the plasma frequency of the slab and its thickness.

Machine supporting slab

Abstract: A machine supporting slab formed of a rigid body of closed-cell foam resin material of high density covered by a metal sheath spanning the top and extending around the marginal edges of said body. Machine retaining means are anchored to said sheath.

Flux Jumps in Nonideal Type-2 Superconductors. I. Theory of Flux Jumps in Slabs

Abstract: A theory of flux jumps in a slab of a nonideal type-2 superconductor is developed by the use of a phenomenological theory of flux motion To include explicitly in the theory the various quantities which are controllable experimentally, the temperature inside the slab is assumed to be approximately uniform Then a flux jump is characterized by a catastrophically sharp rise of the temperature of the sample The criteria for the occurrence of flux jumps are derived under such an assumption, together with the relation between the value of external magnetic field, at which a flux jump starts, and the sweeping rate of the external magnetic field Various behaviors of flux jumps observed experimentally are reasonably explained by the present theory in a quantitative way

Method and apparatus for controlling a slab reheating furnace

Abstract: In controlling a slab reheat furnace, the average temperature of each slab in a zone is predicted as a function of the ambient temperature, thermal properties, dimensions, location, velocity and past thermal history of the slab. The deviations between the predicted average temperatures and predetermined desired average temperatures are weighted as a function of location before being summed to establish a performance index. Proportional plus integral control techniques are used to determine what change in a zone temperature set point will drive the performance index to zero.

Reflection and transmission of electromagnetic waves normally incident on a plasma slab moving uniformly along a magnetostatic field

Abstract: Power reflection and transmission coefficients are found for linearly and circularly polarized plane electromagnetic waves, normally incident on a plasma slab, moving uniformly along a magnetostatic field, normal to the slab boundaries. The solution is found by applying the boundary conditions in the rest frame, and then using relativistic transformations for the fields and the plasma parameters to find the reflection and transmission coefficients observed in the laboratory frame. The results for the circularly polarized incident waves are found in closed form. Numerical results are presented for linearly polarized incident waves. It is found that with an increase in the magnetostatic field, the absolute maximum of the reflection coefficient increases at different velocities. An increase in the magnetostatic field makes the slab more transparent at velocities for which the transmission coefficient with no magnetostatic field is very small. A dielectric-like behavior is observed for large magnetostatic fields. The sum of the power reflection and power transmission coefficients is found to be no longer equal to unity for velocity different from zero.

Reflection and Refraction of Electromagnetic Waves by a Moving Uniaxially Anisotropic Slab

Abstract: The reflection, refraction, and transmission characteristics of a plane electromagnetic wave incident from an isotropic medium, through a moving uniaxial slab, and into another isotropic medium are studied. The conceptual equivalence of a moving medium and a stationary anisotropic one with suitably defined permittivity and permeability tensors is used for the analysis. Complete field expressions are obtained in all three regions for an arbitrary orientation of the plane of incidence and an arbitrary angle of incidence. Special cases where the plane of incidence is parallel, or perpendicular, to the direction of slab motion are considered for both an incident E wave and an incident H wave. Some interesting numerical results are presented for the transmission coefficient at normal incidence when the moving slab is a magnetoionic plasma subject to a strong magnetic field and when the moving slab is a uniaxial crystal.

Load-carrying capacity of slab strips restrained against longitudinal expansion

Abstract: THE RESULTS OF TESTS ON 36 BEAMS (CONSTRUCTED TO REPRESENT SLAB-STRIPS) RESTRAINED AGAINST LONGITUDINAL EXPANSION ARE REPORTED, AND A THEORY, WHICH IS BASED ON THE RIGID-PLASTIC APPROACH, PUT FORWARD FOR THEIR BEHAVIOR. IT WAS FOUND THAT IN MANY CASES THE EXPERIMENTAL MAXIMUM LOAD WAS EVEN GREATER THAN PREDICTED BY THIS THEORY, WHICH CAN BE EXPLAINED BY ASSUMING THAT THE CRUSHING STRENGTH OF THE CONCRETE WAS GREATER THAN THE CUBE STRENGTH. SUPPLEMENTARY TESTS ARE DESCRIBED WHICH SUPPORT THAT ASSUMPTION. IT IS SHOWN THAT THE DEFLECTION AT MAXIMUM LOADS IS NOT A FIXED PROPORTION OF THE THICKNESS OF THE SLAB, AS HAS BEEN ASSUMED IN SOME THEORIES. /AUTHOR/

Radiation detector comprising semi-conductor body incorporating a two-dimensional array of p-i-n-devices

Abstract: A radiation detector comprises a slab of semi-conductor material having a p-i-n structure with ribs formed on opposite sides of the slabs, in p-i and n-i junctions lying within the ribs. The ribs on one side of the slab are so aligned as to traverse those on the other side of the body.

Melting of a finite paraffin slab as applied to phase-change thermalcontrol.

Abstract: An approximate mathematical model was established for the melting of a finite paraffin slab, a problem of interest for phase-change thermal control devices. The method is based on the numerical computer solution of the two-phase, one-dimensional heat-conduction equations with moving interface and variable thermal properties in both the solid and liquid regions. Results from the theoretical model are compared with experimental results for n-octadecane in a bellows-type test cell, and with information published in the literature. The numerical analysis appears to provide a good rigorous treatment of the unidimensional melting problem in an idealized model.

Tests of A Two-Way Reinforced Concrete Floor Slabs

Abstract: Construction and testing of a nine-panel two-way reinforced concrete floor slab are described. The panels were 5 ft sq. Stresses, strains, deflections, and cracking observed during the tests are described. Bending moments derived from measured strains are presented and are shown to be substantially different than the design moments at many design sections. The measured beam moments were appreciably lower than the design moments, but many of the slab sections were underdesigned. The slab design load was 145 psf and the failure load with all panels loaded was 537 psf. This compared favorably with the 529 psf predicted for the same failure mechanism by means of yield-line analysis methods.

Effect of boundary conditions on the propagation of surface magnetostatic waves in a transversely magnetised thin y.i.g. slab

Abstract: The letter deals with the theory of propagation of surface magnetostatic waves in a transversely magnetised thin y.i.g. slab. The effect of boundary conditions on the propagation characteristics of these waves are emphasised. Particular attention is paid to the lowest-order (n=0) mode.

Concrete slab with improved fastening means

Abstract: A concrete slab having a number of peripheral recesses and fastening means disposed in each recess, respectively. In one embodiment, the fastening means includes an angle member having one portion secured to the slab and a second portion with holes therethrough for receiving mounting studs. A connector plate is provided to interconnect the studs passing through the angle members of adjacent slabs. In a second embodiment, the fastening means includes an angle member rigidly secured to the slab and having an angle element rigidly secured thereto to define a space for receiving a bolt. The slab is adapted for use in a number of different building applications and is particularly suitable for use in forming the floor of a building.

Test of Reinforced Concrete Flat Slab

Abstract: The behavior of a flat slab, the second of the 5 test structures built and tested in the course of an investigation of multiple-panel reinforced concrete floor slabs, is described and analyzed. The test structure, which comprised 9 5-ft square panels, was designed essentially on the basis of the ACI Building Code (ACI 318-56). Test data included deflections at 33 locations, reinforcement strains at 335 locations, and all three components of each of the 16 column reactions. Moments computed from measured reinforcement strains were compared with the ACI design moments and indicated that the total amount of reinforcement was sufficient but was in some cases inefficiently distributed. Although the overall factor of safety of the structure was adequate, the tests clearly indicated that the service-load behavior was marginal and that excessive cracking and deflections can be expected in such structures designed for and subjected to high permanent live loads.

Cast-in-place structural truss slab and manufactured pan

Abstract: A structural two-way truss slab of egg-crate form is provided with manufactured pans that have openings in the sidewalls thereof with interconnecting members between the openings. The arrangement is such that the pan can remain in place and thus provide a finished ceiling effect. The system further provides an ability to run air-conditioning, electrical, plumbing and other conduits through the slab itself after the slab has been poured. The slab is structurally equivalent to conventional two-way slabs but is of less gross weight.

Method and apparatus for casting concrete and other settable materials

Abstract: A METHOD AND APPARATUS ARE PROVIDED BY WHICH CONCRETE OR SIMILAR CASTABLE MATERIAL CAN BE FORMED IN A VERTICAL STACK USING A SINGLE FRAME THE INITIAL SLAB OR FORM IS POURED ONTO A PLATFORM WITH OR WITHOUT RE-ENFORCING STEEL LYING THEREON WHEN THE INITIAL SLAB HAS BEEN POURED WITHIN THE SURROUNDING FRAME OR MOLD AND AT LEAST PARTIALLY SET, THE FRAME IS ELEVATED A PREDETERMINED DISTANCE, A SUITABLE BOND BREAKING AGENT SUCH AS, FOR EXAMPLE, A CARBOARD SHEET, HAVING THE APPROXIMATE DIMENSIONS OF THE PREVIOUS SLAB, IS PLACED OVER THE TOP OF THE LATTER, RE-ENFORCING STEEL PLACED THEREON AND THE CONCRETE POURING STEP REPEATED THE FRESHLY POURED CONCRETE IS SMOOTHED OUT BY THE USE OF VIBRATORS, TROWELS AND LEVELING BARS THE CASTING FRAME MAY BE SO CONSTRUCTED AS TO FORM TWO OR MORE MOLDED FORMS WHILE SAID FRAME IS AT ONE HORIZONTAL POSITION

Method of forming continuous pre-stressed concrete slabs

Abstract: This disclosure relates to a method of producing hollow cored concrete slabs in a continuous operation from an initial concrete material having a slump test in the range of 0.5 to 4.0 per ASTM testing. More particularly, the method of the invention is a continuous one to produce the slabs wherein they are continuously formed, vibrated and trowelled, and wherein the concrete material is extruded to produce an elongated prestressed reinforced cored concrete slab.

System for producing modular building blocks

Abstract: The disclosure sets forth a system for prefabricating modular boxlike units of concrete, in which the upper slab or top slab is poured together with the walls and then subsequently is lifted and placed upon a lower slab form, whereby the lower slab is poured to create monolithic structure with the top, side and partition walls. The outside walls and partition walls may also be precast and then placed in position with the pouring of the upper or top slab and then stripped monolithically with the upper slab.

Slab laser system with means to overcome the positive lens effect caused by the thermal gradient in the laser rod

Abstract: In a glass laser system, the laser glass is in the shape of an elongated slab, which is excited by being irradiated through the larger sidewalls thereof. A calcite block plate in combination with quarter and half wave plates laterally shift the laser rays in the laser cavity to compensate for a positive lens effect caused by one dimensional thermal gradient in the laser glass. The calcite block and quarter and half wave plates also function to polarize the laser rays to have their E vectors parallel with the larger sidewalls of the slab.

Effective Dynamic Properties of a Fiber‐Reinforced Material and the Propagation of Sinusoidal Waves

Abstract: A theoretical study is presented on the propagation of a plane sinusoidal wave through a material that is reinforced with parallel fibers in one direction. The wave propagates in a direction normal to the fibers, and both fiber and matrix are made of linear elastic materials. An integral formulation for the scattered‐wave solution of an isolated fiber is used to study the multiple scattering in an infinite slab of the composite material. The transmitted and reflected waves from the composite and from a homogeneous slab are shown to be similar. By matching the two sets of results, formulas expressed in terms of the isolated‐fiber solution are derived for the wave speed, the effective density, and the modulus of the composite. In general, the effective density and modulus so defined are complex numbers and depend on the wave frequency. This fact indicates the possible existence of dissipation and dispersion in the composite under dynamic loadings. A series solution is presented for a composite containing ci...

Mattress for clinical and other purposes

Abstract: A MATTRESS COMPRISING A LOWER SLAB WITH A FLAT BASE AND TWO UPPER INCLINED SURFACES SLOPING FROM THE EXTREMITIES TOWARDS THE CENTER AND AN UPPER SLAB WITH A FLAT TOP AND TWO LOWER INCLINED SURFACES SLOPING FROM THE CENTER TOWARDS THE EXTREMITIES, THE UPPER SLAB BEING SHORTER THAN THE LOWER SLAB AND THE INCLINED SURFACES OF THE UPPER SLAB CORRESPONDING TO THOSE OF THE LOWER SLAB.

Two-slab laser system with compensation for lens power

Abstract: A glass laser system comprises two slabs of laser glass in the laser cavity. The slab shape together with the thermal gradient induced by the flashlamps causes the slabs to act as cylindrical lenses. A prism is provided in the cavity between the slabs to laterally shift the laser rays to compensate for the cylindrical lens effect.

Icemaker cutter-grid-mounting means

Abstract: Apparatus for releasably mounting a subdividing heated wire grid in the cabinet of an icemaker in which a slab of ice is formed and this slab transferred to the slab dividing grid all within the cabinet. This invention includes improved means including interengaging projections and projection receiving means such as slots together with movable catches for some of the slots with the result that the interengagement of the projections and slots provides effective but easily released mounting means for positioning the subdividing grid in the cabinet. The invention is particularly useful for large commercial icemakers in which there is located a plurality of the ice slab forming means positioned closely together vertically and in which the subdividing means or heated grid is located closely adjacent each vertical pair of slab forming means which in each instance is usually a refrigerant evaporator plate.