Showing papers on "Transverse plane published in 1985"

Shear-wave polarizations on a curved wavefront at an isotropic free surface

Abstract: Summary. We present polarization diagrams of the particle motions at the free surface of an isotropic half-space generated by incident shear waves from a local buried point source. The reflectivity technique is used to calculate synthetic seismograms from which the particle motions are plotted. The particle motions are examined over a range of epicentral distances in a uniform isotropic half-space for different source frequencies and polarization angles, and for different Poisson's ratios. The particle motions due to a curved wavefront possess different characteristics from those generated by plane wavefronts at corresponding incidence angles. A curved wavefront generates a local SP-phase: a P-headwave which propagates along the free surface, and arrives shortly before the direct S-wave. These two arrivals give rise to cruciform particle motions in the sagittal and horizontal planes, which could be misinterpreted as anisotropy-induced shear-wave splitting. An examination of the particle motion in the transverse plane, mutually orthogonal to the sagittal and horizontal planes, can be used to discriminate between isotropic and anisotropic interpretations. The amplitude of the SP-phase is enhanced when it propagates in a low-velocity surface layer overlying the source layer, and may then become the dominant phase on radial-component seismograms. The presence of even a single surface layer may introduce considerable complexity into the seismogram, and we examine the effects of layer thickness, velocity contrast, and source depth on the corresponding polarization diagrams. Reliable information on the source and propagation path characteristics of shear waves from a buried local point source can only be obtained from free-surface records if they are recorded within a very limited epicentral distance range.

Wiggle plane focusing in linear wigglers

Abstract: In a free‐electron laser with a long, linear wiggler, the external focusing required to keep the electron beam from dispersing can seriously degrade the performance of the laser. The transverse focusing modulates the longitudinal velocity of each electron, periodically and nonadiabatically changing the phase of the electron with respect to the electromagnetic wave. Phase changes of order unity over a betatron period can strongly detrap or debunch electrons and greatly reduce the gain of a linear wiggler amplifier. The modulation of the electron’s longitudinal velocity can be prevented if focusing in the plane of the electron’s wiggle motion is provided by parabolically curved magnet pole faces. The focusing and resonance effects of curved pole faces are analytically calculated and numerically confirmed. Numerical simulations of linear wiggler amplifiers are presented to illustrate the effect of the curved pole faces on amplifier performance.

Estimating radiofrequency power deposition in body NMR imaging.

Abstract: Simple theoretical estimates of the average, maximum, and spatial variation of the radiofrequency power deposition (specific absorption rate) during hydrogen nuclear magnetic resonance imaging are deduced for homogeneous spheres and for cylinders of biological tissue with a uniformly penetrating linear rf field directed axially and transverse to the cylindrical axis. These are all simple scalar multiples of the expression for the cylinder in an axial field published earlier (Med. Phys. 8, 510 (1981]. Exact solutions for the power deposition in the cylinder with axial (Phys. Med. Biol. 23, 630 (1978] and transversely directed rf field are also presented, and the spatial variation of power deposition in head and body models is examined. In the exact models, the specific absorption rates decrease rapidly and monotonically with decreasing radius despite local increases in rf field amplitude. Conversion factors are provided for calculating the power deposited by Gaussian and sinc-modulated rf pulses used for slice selection in NMR imaging, relative to rectangular profiled pulses. Theoretical estimates are compared with direct measurements of the total power deposited in the bodies of nine adult males by a 63-MHz body-imaging system with transversely directed field, taking account of cable and NMR coil losses. The results for the average power deposition agree within about 20% for the exact model of the cylinder with axial field, when applied to the exposed torso volume enclosed by the rf coil. The average values predicted by the simple spherical and cylindrical models with axial fields, the exact cylindrical model with transverse field, and the simple truncated cylinder model with transverse field were about two to three times that measured, while the simple model consisting of an infinitely long cylinder with transverse field gave results about six times that measured. The surface power deposition measured by observing the incremental power as a function of external torso radius was comparable to the average value. This is consistent with the presence of a variable thickness peripheral adipose layer which does not substantially increase surface power deposition with increasing torso radius. The absence of highly localized intensity artifacts in 63-MHz body images does not suggest anomalously intense power deposition at localized internal sites, although peak power is difficult to measure.

Thermodynamical properties of the transverse Ising model

Abstract: A new effective field theory is proposed and used to derive the thermodynamical properties of the transverse Ising model. The formalism is based on an exact formal spin identity for the two-state transverse Ising model and utilizes an exponential operator technique. The method, which can explicitly and systematically include correlation effects, is illustrated in several lattice structures by employing its simplest approximation version (in which spin-spin correlations are neglected). The lines of critical points in the Ω- T plane as well as the thermal behaviour of both transverse and longitudinal magnetizations are analysed for square and simple cubic lattices. It is shown that the present formalism, in spite of its simplicity, yields results which represent a remarkable improvement on the standard mean field treatment (MFA).

Longitudinal and Transverse Current Distributions on Microstriplines and Their Closed-Form Expression

Abstract: Simple but accurate closed-form expressions for the normalized longitudinal and transverse current distributions on microstriplines are derived by rising the charge conservation formula and the charge distributions calculated by the Green's function technique. Their dependence on both the relative permittivity of the substrate epsilon* and the shape ratio w/h are explained, and the results are compared with other available results. It is confirmed by comparison with other theoretical results that the present closed-form expressions are valid for an even higher frequency. The reasonable expression for the normalized transverse current distribution is believed to be the first.

Intersecting laser alignment apparatus and method

Abstract: An apparatus and method for determining the proper position of misaligned vehicle parts utilizes an X, Y and Z coordinate system to provide a proper point of position, or alignment, of vehicle parts which are identified in tables by such coordinates. The apparatus includes a framework which is established about the vehicle by transverse bars, datum plane bars, cross bars and a vertical standard, all with scale indicia, and forming a point of origin as on a graph. Lasers emitting planes of visible light are mounted on the datum plane bars and cross bar and project mutually perpendicular, intersecting planes of light. A laser is also mounted on the standard to project a horizontal plane of light that intersects the other two light planes and establishes a point capable of definition by X, Y and Z coordinates. The lasers are adjusted on the bars and standard to the measurements set forth in the table of coordinates and the error noted between the intersection point established by the X, Y and Z coordinates and the actual position of the misaligned part. Bending forces are applied to the frame area, or removal and replacement of parts is accomplished to correct the mispositioning or misalignment.

Fiber-optic rotation sensor

Abstract: A fiber-optic rotation sensor comprises a coil of polarization-holding, single-mode optical fiber (25) having a core (26) with a non-circular cross-section defining two transverse orthogonal axes, the outer surface (28) of said fiber having a non-circular cross-section with a predetermined geometric relationship to said orthogonal transverse axes, a laser source (30) coupled to one end of said fiber (25) for supplying said fiber (25) with an optical signal having a fixed polarization plane, said non-circular outer surface of said fiber (25) forming a reference surface (29) for precisely aligning one of said transverse orthogonal axes of said fiber core (26) with said fixed polarization plane of the optical signal from said laser source (30).

Strain patterns in models of spreading-gliding Nappes

Abstract: Three experiments have been carried out in order to study the progressive and finite strain in nappes where gravitational spreading and gliding occur together. These experimental models were made from analogue materials able to collapse under their own weight on an inclined plane. Throughout most of the models the stretch trajectories in a vertical plane parallel to the flow show a low-amplitude sigmoidal pattern consistent with a previous theoretical model. Other stretch trajectories exist at the front and back ends of each model. The kinematic significance of all these trajectories is discussed in detail. Highest strain intensities are always found next to the base of the model. Strain paths calculated at different stages of flow indicate clearly that nowhere in the model is the motion simple. There is a complex combination in time and space of simple and pure shear, except at the base of the model where the motion approximates a simple shearing. Near the two parallel lateral sides of the model a lateral boundary effect can be observed from the strong curvature of the transverse markers (surface grid and vertical layers). Strain paths have also been estimated in this complex zone where wrench shearing is superimposed upon vertical shortening and thrust shearing. The geological implications of these experimental models are discussed in relation to recent theoretical studies and field work.

Volumetric flow rate determination in conduits not directly accessible

Abstract: A catheter, particularly adapted for cardiac output determination, comprises an elongated tube (20) of flexible material, the tube (20) having a substantially rigid distal portion (10) on which is disposed an ultrasonic transducer (38) and a proximate, inflateble balloon (36). The ultrasonic transducer (38) is arranged so as to direct a beam of ultrasound toward a transverse plane (PL) that bisects the balloon (36), and is connected by appropriate leads (28, 46) to a conventional Doppler circuit. With the balloon (36) deflated, the signal from the Doppler circuit is sensed to measure blood velocity. Thereafter, the balloon (36) is inflated so that it has a predetermined cross-sectional area in the transverse plane (PL). The signal from the Doppler circuit is again sensed to measure blood velocity. Using a simple mathematical relationship, the effective internal cross-sectional area of the blood vessel is determined from the two measured velocities and from the predetermined cross-sectional area of the balloon (36) when inflated. The volumetric flow rate is then determined by multiplying the first measured velocity by the effective internal cross-sectional area.

Infrared focal plane module with stacked IC module body

Abstract: An infrared detection module is disclosed for interfacing a plurality of detector elements to external electronics. The module is formed of a plurality of multi-channel integrated circuits stacked in substantially overlapping registry with adjacent integrated circuits separated by an insulating layer. Each integrated circuit is formed to have exposed conductive areas along first and second edge portions thereof. Each detector array segment is disposed transverse to the plane of the integrated circuits and connected to conductive areas on each integrated circuit along first edge portions thereof. A module header interface is disposed transverse to the plane of the integrated circuits and is electrically connected to the conductive areas along the integrated circuit second edge portions.

Temperature fluctuations and heat flux in grid-generated isotropic turbulence with streamwise and transverse mean-temperature gradients

Abstract: A screen of closely spaced, parallel, thin wires was placed downstream of a grid generating nearly isotropic turbulence. The screen was normal to the flow and was heated in one of two modes : (1) periodically in time, to generate a train of transversely uniform streamwise thermal ramps, each with a uniform streamwise gradient, and (2) steadily, with transverse non-uniformity, to generate a uniform transverse thermal ramp. The simple temperature and temperature-gradient fluctuation statistical properties in both cases were found to be comparable to those encountered in earlier works with a steadily heated grid producing a uniform transverse thermal ramp. In both modes of heating the temperature fluctuations decreased initially behind the screen and then increased monotonically. The turbulent heat-transfer correlation coefficient attained an asymptotic magnitude between 0.7 and 0.8 for both modes of heating. The skewness of the temperature-fluctuation derivative in the direction of the mean gradient was founded to be non-zero despite the absence of mean shear.

Method for adjusting coupling optics and the end of a waveguide relative to a semiconductor laser

Abstract: A method and apparatus for positioning a laser diode with respect to a coupling optic for a waveguide to obtain the optimum light transmission characterized by providing a reflecting reference plane or surface extending perpendicular to the axis of the waveguide adjacent the coupling optic, projecting light through the waveguide and coupling optic onto the reflecting surface, measuring the amount of light reflected into the waveguide and adjusting the axial position of the waveguide and optic relative to the reflecting surface to obtain the optimum value, then placing the semiconductor with the facet in the reference plane and either operating the semiconductor to provide light for coupling into the waveguide and adjusting the relative positions in a transverse plane to the axis of the waveguide to obtain the optimum transmission or operating the semiconductor laser as a detector and coupling light into the waveguide at a point spaced from the laser to project into the detector and making adjustments in the transverse direction to obtain the optimum reading. The reflecting surface can be either a separate reflecting device or the facet of the laser. The apparatus includes two members each having an abutting surface with one of the members positioning the waveguide with the coupling optic to lie along an axis perpendicular to the abutting surface and the other member positioning the semiconductor laser with the facet lying in the plane of the abutting surface.

Winding machine for winding and/or unwinding web-like guided materials

Abstract: To simplify and accelerate the chucking of a journal-free beam or roll mandrel in a winding machine and also to automate and accelerate the alignment of the winding machine and the journal-free beam or roll mandrel in relation to a creel middle plane or centerline, a displacement device is connected to an auxiliary side stand by at least one first extension link or hollow spindle and is also connected with a displaceable support by at least one second extension link or solid spindle. To achieve these effects, the first and second extension links or spindles are moved or positively controlled in opposite displacement directions through respectively equal distances relative to a spatially fixed plane passing through the displacement device and which plane extends transverse to the direction of displacement of the winding machine.

Laser contour cut door beams

Abstract: A contour cut door beam for automobiles, and apparatus and method of forming same. A steel tube is contour cut with a laser beam from a source offset from an operative axis coincident with the tube axis, using simultaneous rotational and linear advancement between the tube and cutting beam to form an arcuate outer end terminus on the tube in a plane transverse to the axis, an arcuate inner terminus on the opposite side of the tube in a second plane transverse to the axis, and a pair of mirror image contoured edges joining said termini, with all portions being on radii relative to said axis.

High power single spatial mode semiconductor laser

Abstract: A high power single spatial mode semiconductor laser provides strong lateral index guiding to maintain single transverse mode output and yet has a large cavity area. The large cavity area provides low series resistance, low thermal resistance, and lower operating current densities and photon densities than can be achieved by conventional cavity designs. The result is a laser which can operate at high output power at a single transverse mode. In the plane of the p-n junction, the active layer has a cross-section including a waveguide section of width between 1-2 microns which provides lateral mode stability and discrimination against high order transverse modes with a directly adjacent amplifier section consisting of a layer of about 5-20 microns width and several hundred microns in length. Due to the large cross section area of the amplifier section, the majority of the current flows through the amplifier section where most of the heat is generated. The device has only a few ohms series resistance and significantly lower thermal impedances than conventional narrow cavity design.

Method for measuring fastener stress utilizing longitudinal and transverse ultrasonic wave time-of-flight

Abstract: A method and apparatus for measuring tensile stress in a fastener already in place. This method capitalizes on the discovery that a longitudinal wave will travel roughly twice as fast as a transverse wave and the times-of-flight of the two waves are affected to different degrees by tensile stress. Longitudinal and transverse ultrasonic signals are applied to a first end of the fastener. The longitudinal and transverse signals are detected at this same first end of the fastener after they are reflected off of the second end of the fastener. The time-of-flight for each of the longitudinal and transverse waves is measured. The tensile stress, T, in the fastener is then determined by applying substantially the following equation: ##EQU1## where v 10 and v 20 =the velocities of the longitudinal and transverse signals, respectively, in a similar fastener not under stress; k=the length of the unstressed portion of the fastener; λ and μ=Lame' constants for the fastener material; and D 1 and D 2 =material constants for the fastener representing a simplified combination of second and third order elastic material constants.

Large-Amplitude Oscillations of Unsymmetrically Laminated Anisotropic Rectangular Plates Including Shear, Rotatory Inertia, and Transverse Normal Stress

Abstract: This paper is concerned with nonlinear free vibrations of generally laminated anisotropic elastic plates. Based on Reissner’s variational principle a nonlinear plate theory is developed. The effects of transverse shear, rotatory inertia, transverse normal stress, and transverse normal contraction or extension are included in this theory. Using the Galerkin procedure and principle of harmonic balance, approximate solutions to governing equations of unsymmetrically laminated rectangular plates including transverse shear, rotatory inertia, and transverse normal stress are formulated for various boundary conditions. Numerical results for the ratio of nonlinear frequency to linear frequency of unsymmetric angle-ply and cross-ply laminates are presented graphically for various values of elastic properties, fiber orientation angle, number of layers, and aspect ratio and for different boundary conditions. Present results are also compared with available data.

Propagation of bounded ultrasonic beams in anisotropic media

Abstract: A method of computing the elastic displacement and stress in an anisotropic elastic medium (crystal) when the medium is excited at its surface by a given displacement or stress is developed. In particular, it is shown how arbitrary boundary conditions generally induce both diagonal and off‐diagonal stresses and longitudinal, as well as transverse, displacements. A number of special cases which can be handled analytically are discussed in detail, and a perturbation theory for narrow angle beams is developed. Comparisons are made with previous works which considered propagation of plane waves in nonpure mode directions.

Composite pulses for time reversal in nmr imaging

Abstract: Composite pulses are employed in NMR imaging for time-reversal of nuclear spins in a transverse planar region of a sample to produce spin-echo signals. The composite pulses comprise a sequence of pulses for producing a 90° rotation of the spins about a first transverse axis, a 180° rotation of the spins about a substantially orthogonal transverse axis, and a 90° rotation of the nuclear spins about the first transverse axis. The composite pulses minimize time-reversal errors caused by static magnetic field and RF field inhomogeneities, and afford multiple spin-echo NMR imaging sequences.

Importance of imaging plane for magnetic resonance imaging of the normal left ventricle.

Abstract: Visualization of the left ventricle by magnetic resonance imaging (MRI) is largely a function of imaging planes. The best depiction of the myocardium is possible when the imaging plane is perpendicular to the region of interest. The effect of imaging plane on the visualization of the left ventricle has not been fully described. To assess this effect, 10 normal adults underwent electrocardiogram-gated multiplanar cardiac MRI. The imaging planes being evaluated were standard planes, transverse, sagittal and coronal, and modified planes relating to the left ventricular (LV) long axis: coronal long axis parallel to the ventricular septum (VS), sagittal long axis perpendicular to the VS and transverse short axis perpendicular to the VS and long axis. The myocardium was separated into 9 segments. Using each plane, the LV segments were evaluated for quality of LV depiction. The planes based on the LV long axis were superior to standard planes in depicting the LV segments.

Radiative collimation of atomic beams through two-dimensional cooling of atoms by laser-radiation pressure

Abstract: The transverse cooling of a beam of sodium atoms in an axisymmetric light field formed by a reflecting axicon is studied. It is shown that transverse cooling leads to a decrease in angular divergence (collimation) of the atomic beam. The transverse velocities of the beam are reduced from 5.5 × 102 to 1.6 × 102 cm/sec, which corresponds to the decrease in effective transverse temperature of the beam from T = 42 to T = 3.3 mK. The spatial and velocity distributions of the atomic beam are calculated numerically. It is found that theory and experiment are in good agreement.

Transverse modes of gain‐guided coupled‐stripe lasers: External cavity control of the emitter spacing

Abstract: By means of an external grating cavity, the dispersion relation of the transverse modes of gain‐guided coupled‐stripe laser diodes is determined. The parabolic relation obtained indicates (despite the stripes) a relatively flat gain profile similar to a broad area laser. Accordingly, higher order transverse modes are possible and are demonstrated with near and far fields exhibiting one and two emitters per stripe.

Equations for Plane, Moderately Curved Open Channel Flows

Abstract: Plane flow with moderately curved and involved bounding streamlines is investigated by accounting for the transverse variations of the velocities. The result is a highly nonlinear version of the corresponding Boussinesg relation (valid only for weakly curved and sloped stream lines). Applications include the computation of the cnoidal and solitary wave profiles and indicate a clear advantage of the present formulation over previous ones.

Compartmented storage container

Abstract: A compartmented storage container for use in an automatic parts storage and retrieval system comprising a one-piece thin-wall molded plastic body having a rectangular shape adapted to fit within the rectangular rim of a tray, an outside edge portion, an inside edge portion, a bottom portion and at least one transverse divider wall portion, all of said portions being integral with one another and with the transverse divider wall portion having a vertical height measured from a bottom plane less than the vertical height of the outside and inside edge portion.

Elastic constants of a monocrystalline nickel-base superalloy

Abstract: The interest in using a monocrystalline superalloy for turbine blades makes it imperative to understand the elastic response of the monocrystalline superalloy under external stress. While the elastic response in the direction of loading is well known for monocrystals, the transverse response under longitudinal loading is not well characterized. The present work presents an experimental measurement and an analytical treatment for characterizing the transverse elastic response under longitudinal loading. The work indicates that the transverse elastic response, in general, is sinusoidal. The in-plane transverse direction, therefore, affects the elastic deformation in the transverse direction under unit longitudinal load, and a proper choice of the in-plane crystallographic direction minimizes the in-plane transverse strain. By fitting the experimental data to an analytical equation, the elastic constants can be obtained from a cylindrical monocrystal of arbitrary axial orientation.

Gravity driven slow creeping flow of a viscous body at elevated temperatures

Abstract: The flow of a thermoviscous body at elevated temperature under gravity is described by the mass, momentum, and energy balances of an incompressible, homogeneous, heat conducting, nonlinearly viscous fluid, in which the shear response includes a strongly temperature‐dependent rate factor. A scale analysis and coordinate stretching, appropriate for flows down an inclined surface, reflect the properties that depth‐to‐length ratios are different in both the “downhill” direction and perpendicular to it and that the flow is essentially from higher altitudes to lower ones. The normalized energy equation shows that, for the applications considered, in‐plane and out‐of plane (transverse) advections are important and that transverse diffusion and dissipation are both significant. Analogously, the stress‐deviator‐stretching relationship exhibits a conspicuous temperature dependence. Hence, there is strong ther-momechanical coupling. The small aspect ratio parameters of the nondimensional equations permit deduction o...