Showing papers on "Slab published in 1983"

Long range correlations for stochastic lattice gases in a non-equilibrium steady state

Abstract: The author considers a system with a single locally-conserved field ( identical to density) in a slab geometry with different densities maintained at the two surfaces of the slab. On the basis of fluctuating hydrodynamics, he shows that the static density-density correlations are long ranged and decay as -1/ mod x-y mod d-2 for dimension d>or=3 over distances small compared to the size of the slab. This effect vanishes to first order in the density difference. As a particle model he investigates a stochastic lattice gas with Kawasaki dynamics. He establishes the connection to fluctuating hydrodynamics. In the case of hard core interaction only he proves the validity of fluctuating hydrodynamics and obtain, presumably model dependent, corrections.

Nonlinear waves guided by a dielectric slab

Abstract: We consider dispersion relations and field structure of TE-polarized guided waves travelling along an asymmetric dielectric slab surrounded by two different nonlinear media. For a given configuration there are four types of guided waves. Three of this four types possess at least one field maximum outside the slab region and have no counterpart in linear waveguide optics. The solutions of the dispersion relations depend now on an additional parameter making them more flexible with respect to the linear limit.

Reduced thermal focusing and birefringence in zig-zag slab geometry crystalline lasers

Abstract: Replacing the rod in a Nd:YAG laser with a zig-zag slab resulted in a very substantial reduction of the thermally induced optical distortion without sacrifice of output power or efficiency This reduction was possible after simple measures were taken to eliminate end and edge effects

Complex distribution of large thrust and normal fault earthquakes in the Chilean subduction zone

Abstract: Summary. We present the results of a systematic study of events with M, > 6 in northern Chile (20-33"S), for the period between 1963 and 1971. Medium to large earthquakes near the coast of this region are of three types: (1) Interplate events at the interface between the downgoing slab and the overriding South American plate. These events can be very large reaching magnitudes greater than 8. (2) Intra-plate earthquakes 20-30 km inside the downgoing slab. They have fault mechanisms indicating extension along the dip of the slab and may have magnitudes up to 7.5. (3) Less frequent,M, - 6 events that occur near the top of the downgoing slab and have thrust mechanisms with an almost horizontal E-W compressional axis. This type of mechanism is very different from that of the events of type 1 which are due to shallow dipping reverse faulting. There is a rotation of about 30" of the compressional axis in the vertical plane between events of types (1) and (3). Three groups of events near 32.5", 25.5" and 21"s were studied in detail. Depth and mechanisms were redetermined by P- wave modelling and relative locations were obtained by a master event technique. Near 32.5"S, only events of types 1 and 2 were found in the time period of this study. At the two other sites, the three types of events were identified. This shows clearly that there are compressive stresses at the top of the slab and extension at the centre, a situation which is usually found in the areas where a double Benioff-zone has been identified in the seismicity.

Surface polariton reflection and radiation at end faces

Abstract: A theoretical investigation has been made of surface polariton reflection and radiation at the end face of a metal slab Dielectric materials of dielectric constants ed and e′d lie above and beyond the end of the metal slab, respectively Energy transmission and reflection coefficients have been calculated for a surface polariton incident on the end face of the metal slab for various slab thicknesses when ed =ed=1 and ωp/ω=4 The energy reflection coefficient has also been investigated as a function of ed with e′d=1 The angular distribution of the radiation pattern has also been studied for two different ed

Tests of composite beams with web holes

Abstract: Tests of composite beams comprising a concrete slab supported on a steel deck and a steel wide-flange shape containing large web openings are described. Special attention is directed to the amount ...

Yield‐Line Analysis of Slabs‐on‐Grade

Abstract: A yield line method is developed to analyze reinforced concrete slabs‐on‐grade to determine collapse loads. The particular cases discussed are: (1) A one‐way slab with a line load at mid‐span; (2) a slab with a central load; (3) a slab with a load at a free edge; and (4) a slab with a load at a free corner. For each case, an expression for the collapse load is given in terms of material and geometric parameters. Plots of collapse load magnitude vs. a load distribution parameter are presented for the proposed analysis method and compared to analyses found in previous literature.

Experience with shear frames

Abstract: The shear frame is a simple in situ device for indexing the shear strength of thin weak layers. The index is sensitive to shear-frame geometry, rate-of-pull, and shear-frame mass. It is time-consuming to carefully align the device on the Gleitschicht (shear failure plane) in a slab avalanche zone. The ratio shear frame index/shear stress of the Gleitschicht has a high variance, and may not be a fundamental measure of slab avalanche stability. Corrections for the normal stress on the Gleitschicht reduce the variance only slightly. Despite these limitations, the shear frame is a useful tool for gathering statistical data on strength distributions and anisotropies of the Gleitschicht until a more fundamental technique is developed.

Convection in the mantle wedge above the slab and tectonic processes in subduction zones

Abstract: Some nonconductive heat transport in the mantle wedge above the subducting lithosphere is necessary to explain the volcanic and thermal activities in subduction zones. The physical mechanisms that have been proposed to explain the observed thermal processes are classified into the following three categories: (1) secondary convection mechanically driven by the motion of the slab, (2) thermal convection due to a large horizontal temperature gradient associated with the presence of the cool slab, and (3) flow induced by ascending mantle diapirs containing low-density melt. The relative importance of these three mechanisms is evaluated, using a simple model in which the conduit of the convective flow is prescribed. The first mechanism of mechanically driven flow dominates the other two when the effective viscosity of the mantle wedge exceeds 1020 Pa s (1021 P). Known estimates of wedge viscosity suggest that either the second or third mechanism is more likely to be the one that actually governs the tectonic process. It is proposed that both the second and third mechanisms are realized in different stages of a single tectonic sequence and that arc volcanism and back arc spreading occur, corresponding to these different modes of convection.

Lateral-Load Tests of R/C Slab-Column Connections

Abstract: The response of interior reinforced concrete plate column connections in a laterally loaded structure is investigated. Nine specimens were tested, five statically and four dynamically to simulate earthquake loading. This paper describes results from statically tested specimens. Experimental variables include reinforcement ratio and amount of superimposed slab load. Nominal slab dimensions were 6×6ft(1.8×1.8m). Slab thickness was 6 in. (76 mm). The column was square with plan dimensions of 1.0 ft (0.3 m) by 1.0 ft (0.3 m). Reinforcement layout in the slab was isotropic. Statically tested specimens provided data on influence of reinforcement amount and slab load oh stiffness and strength. In the range of joint rotations less than 4%, strength was controlled by torsional stiffness of the slab. Slab shear failures were observed for the specimens with slab load at joint rotations over 4%. A numerical model was developed to enable calculation of the overall moment‐rotation response.

Apparatus and procedure for forming pre-shaped interlocking cement slabs

Abstract: The invention pertains to a cementitious slab and to apparatus and procedure for making it in such a manner that it may be used in an interconnected relation for providing a longitudinally extending side edging along a street or roadway. The slab product is made in a frame assembly that is positioned for turnover movement on a pair of stands. The frame assembly in its upper or mold space defining positioning has an integral enclosing side wall frame and a bottom wall, with one pair of side walls of the frame spaced from ends of the bottom wall and adapted to removably receive a pair of opposed end wall forming members for completing the mold cavity and providing the cementitious slab with tongue and groove portions. After the concrete or cement has been poured into the mold cavity, the opposed end wall members are removed and a pair of cross-ending support members are secured across a pair of the side walls to support the slab when it is turned-over or rotated 180° to a position in which its former top side faces the ground. The pair of cross-extending support members are than removed and the assembly tapped to drop the slab a short distance onto a suitable receiving means, such as forks of a fork lift truck. The bottom plate forms a smooth-finished upper face of the slab and is employed to position a pair of lift lugs that are internally threaded and extend into the mold cavity for embedment in the slab, with the threaded end exposed to provide means for facilitating lifting and transporting of the slab.

Travelling Waves in a Dielectric Slab with an Abrupt Change in Thickness

Abstract: If a slab (or tube) of dielectric material of uniform thickness is surrounded by a medium of lower dielectric constant it can support travelling waves that propagate without attenuation. If there is an abrupt change in the slab thickness, reflexion and radiation will occur. This paper deals with the simplest prototype case, in which a transverse magnetic travelling wave, whose length is large compared with slab thickness, encounters such a change in geometry. At points very close to the junction the field is modelled by a quasistatic solution. An outer approximation is calculated, based on the idea of replacing the actual slab by a hypothetical surface of infinitesimal thickness, with appropriate discontinuity conditions. A solution is determined in the form of an inverse Fourier integral, and explicit results are given for the reflexion and transmission coefficients.

Method for producing a grain-oriented electrical steel sheet having a high magnetic flux density

Abstract: The present invention relates to a method for producing a grain-oriented electrical steel sheet. A feature of the present invention is to set S≦0.007%, Mn=0.08˜0.45%, P=0.015˜0.45% in a slab. The present inventive idea does away with the conventional concept of using MnS as an inhibitor. The present invention present incomplete secondary recrystallization by the S content, which is decreased to a level as low as possible. In addition, a product having a high magnetic flux density can be successfully produced by adding appropriate amounts of Mn and P. Due to these advantages a high Si content of a slab, which leads to a watt loss reduction, can also be employed in the present invention. Furthermore, the watt loss of a product produced by a low-temperature slob-heating is considerably lower than a product produced by a high-temperature slab-heating.

High performance composite floor structure

Abstract: A composite floor structure is disclosed in which a plurality of corrugated sheets having crest portions which slope downwardly at each end thereof are supported on the top surface of a plurality of spaced I-section supporting beams. Studs are welded directly to the top surface of the I-beams directly over the beam's webbing to securely connect the beams to an overlying concrete slab, thereby creating a composite action between the beam and slab and increasing the load carrying ability of the I-beams. By providing a sufficient volume of concrete around the studs, each stud is completely effective. Embossments may be provided in the sheets to also create a composite action between the sheets and the slab causing the entire structure to act as a single composite unit to resist vertical gravity loads (bending) and in plane horizontal wind or seismic loads (shear).

Some results of ionospheric slab thickness observations at Lunping

Abstract: The subject of the present study is to analyze the characteristic variations of the ionospheric slab thickness observed at Lunping Observatory. The slab thickness data obtained from March 1977 to February 1982 were used to analyze the diurnal, seasonal, and solar cycle variations. The diurnal variation showed an unusually large peak that appeared in pre-sunrise hours, especially during winter time. Lunar variations of slab thickness were obtained by Chapman-Miller method and discussed. The storm time variation and disturbance daily variation of slab thickness were obtained by selecting 138 strong and weak geomagnetic storms. Superposed epoch method was also used to analyze the geomagnetic activity effect on the variation of slab thickness.

Method and apparatus for cooling a slab laser

Abstract: In a high average power slab laser, heat generated in the laser slab is conducted through a thin layer of thermally conductive gas, such as hydrogen, helium or air, and then through an optically transparent window into a flow of liquid coolant. In a preferred embodiment, a second flow of liquid coolant is employed for cooling of the pumping lamps such lamp liquid coolant flow being partitioned from the slab liquid coolant flow by means of an optically transparent partition through which the pump radiation is directed from the lamps to the slab. In another embodiment, the slab coolant flow is controlled so as to operate the laser slab in a self-annealing temperature regime, whereby thermal stresses are annealed out in use and higher average output beam power is obtained.

Apparatus for positioning and stabilizing a concrete slab

Abstract: A method of lifting and stabilizing a concrete slab having an opening therein in which a plate is attached to the top surface of the slab, the plate having an opening coinciding with the opening in the slab, a hydraulic jack having a downwardly extending piston is removeably secured to the plate and a series of tubular shafts are forced downwardly through the opening in the plate and the slab to penetrate the earth beneath the slab and apply lifting force. When the slab has been lifted to the desired elevation, grout, such as a concrete slurry, can be injected below the slab so that the slab is stabilized in the selected elevational position. After the plate is removed the hole in the slab is filled.

Multi-layer insulating slab and process for manufacture thereof

Abstract: A multi-layer insulating slab having a core layer of oriented mineral fibres and at least one cover layer is designed, in order to achieve higher compressive stress resistance, transverse tensile strength and flexural strength, in such a manner that the core layer (13) is a self-supporting lamella element (13) of oriented mineral fibres, which is built up of a multiplicity of longitudinal bars (14a to 14e), which are bonded together at their side surfaces (15a to 15d) and are sections of mineral fibre slabs (10), and that the core layer (13) is firmly bonded on one or both sides to a curable or prefabricated cover layer. An advantageous process for manufacturing the multi-layer insulating slab consists in bonding a multiplicity of mineral-fibre slabs of desired length and with fibres lying in the plane of the slab in a laminated state to form a block, which is cut lengthways and perpendicular to the plane of the bonded mineral-fibre slabs in each case to form a lamella element of the desired thickness, which comprises longitudinal bars, which are firmly bonded together, in the form of a self-supporting slab of lamella construction, in which the mineral fibres are essentially arranged in one plane, which plane extends parallel to the bonded-together side surfaces of the longitudinal bars of this lamella element, after which the resulting lamella element is firmly bonded to at least one curable or prefabricated cover layer to form the multi-layer insulating slab.

A reexamination of earthquakes previously thought to have occurred within the slab between the trench axis and double seismic zone, northern Honshu arc.

Abstract: We have studied earthquakes along the northern Honshu arc, Japan, which were previously thought to have occurred within the downgoing slab, landward of the trench axis and seaward of the double seismic zone. We used P-wave synthetic seismograms to determine precise source depths and mechanisms. We examined six earthquakes in the zone from 50km to 150km landward of the trench axis whose published focal mechanisms showed normal faulting or T axes subparallel to the dip of the slab. These events were thought to have occurred within the slab due to their focal mechanisms. When we computed body-wave synthetics, however, five of these six events were shown to be of thrust type and located at the plate interface. Our symthetics confirm that the sixth event (March 16, 1969, mb=5.5, Ms=5.5), located about 100km landward of the trench axis, definitely occurred within the slab 15km below the plate interface. We obtain a focal mechanism with T axis dipping at an angle of 60°. The location of this event is about 50km seaward from the edge of the double seismic zone. The bending-unbending theory of an elastic-plastic plate cannot explain the stress axis of this event; however, the gravitational pull or sagging of the downgoing slab is consistent with this stress orientation.