Showing papers on "Transverse plane published in 1989"

Segmental analysis of the sagittal plane alignment of the normal thoracic and lumbar spines and thoracolumbar junction

Abstract: Recent advances in spinal instrumentation have brought about a new emphasis on the three-dimensional spinal deformity of scoliosis and especially on the restoration of normal sagittal plane contours. Normal alignment in the coronal and transverse planes is easily defined; however, normal sagittal plane alignment is not so simple. This retrospective study was undertaken to increase the understanding of the normal alignment of the spine in the sagittal plane, with a special emphasis on the thoracolumbar junction. Measurements were made from the lateral radiographs of 102 subjects with clinically and radiographically normal spines. Cobb measurements of the thoracic kyphosis (T3-T12), the thoracolumbar junction (T10-T12 and T12-L2), and the lumbar lordosis (L1-L5) were determined. The spices of the thoracic kyphosis and lumbar lordosis also were determined. Using a computerized digitalizing table, the segmental angulation was determined at each level from T1-2 to L5-S1. In conclusion, there is a wide range of normal sagittal alignment of the thoracic and lumbar spines. When using composite measurements of the combined frontal and sagittal plane deformity of scoliosis, this wide range of sagittal variance should be taken into consideration. Using norms established here for segmental alignment, areas of hypokyphosis and hypolordosis commonly seen in scoliosis can be more objectively evaluated. The thoracolumbar junction is for all practical purposes straight; lumbar lordosis usually starts at L1-2 and gradually increases at each level caudally to the sacrum.

Transverse localization of light.

Abstract: We study the propagation of light through a semi-infinite medium with transverse disorder (that is, disorder in two directions only). We show that such a system exhibits strong two-dimensional localization by demonstrating that on propagation a beam expands until the transverse localization length is reached.

Magnetospheric ULF wave coupling in the dipole model: The impulsive excitation

Abstract: The coupling of compressional and transverse hydromagnetic waves is studied in the cold and inhomogeneous outer magnetosphere. A general computer program has been developed for a dipole model. This model allows a realistic spatial variation of Alfven speed and includes dipole geometric effects. The propagation and the structure of each mode are analyzed on a two-dimensional map of a meridian plane. The properties of coupling are also investigated through time histories and wave frequency spectra. The highly spatially structured form of transverse and compressional waves is shown on the meridian plane. The theory of global compressional mode damping is compared with the numerical results. We have found a set of global modes whose spatial structure is complicated due to the inhomogeneity of the dipole geometry. These global modes are strongly coupled to field line resonances when the global mode frequency is harmonically matched to the toroidal resonant frequency. The coupling of the two modes results in relatively large-amplitude oscillations along the resonant field lines.

Prediction of Transverse Cracking and Stiffness Reduction in Cross-Ply Laminated Composites

Abstract: A modified shear lag analysis, taking into account the concept of in terlaminar shear layer, is employed to predict the onset of a transverse crack and multiple transverse cracking. In this analysis, the boundary conditions are satisfied for any trans verse crack spacing. The crack multiplication is simulated by adjusting the crack spacing. Based on this analysis the laminate stiffness reduction due to the multiple transverse crack ing is also evaluated in cross-ply laminated composites. The energy concept is utilized to assess the effect of 90° layer thickness and the constraining effect of 0° layer on the trans verse cracking behavior of cross-ply laminated composites. Predictions of the onset of a transverse crack and stiffness reduction due to transverse cracks are compared with those of previous analyses and existing experimental data. The present analysis is simple, yet its results show reasonable agreement with experimental results.

Three-dimensionality of organized structures in a plane turbulent wake

Abstract: This paper describes a quantitative study of the three-dimensional nature of organized motions in a turbulent plane wake. Coherent structures are detected from the instantaneous, spatially phase-correlated vorticity field using certain criteria based on size, strength and geometry of vortical structures. With several combinations of X-wire rakes, vorticity distributions in the spanwise and transverse planes are measured in the intermediate region (10d [les ] x [les ] 40d) of the plane turbulent wake of a circular cylinder at a Reynolds number of 13000 based on the cylinder diameter d. Spatial correlations of smoothed vorticity signals as well as phase-aligned ensemble-averaged vorticity maps over structure cross-sections yield a quantitative measure of the spatial coherence and geometry of organized structures in the fully turbulent field. The data demonstrate that the organized structures in the nominally two-dimensional wake exhibit significant three-dimensionality even in the near field. Using instantaneous velocity and vorticity maps as well as correlations of vorticity distributions in different planes, some topological features of the dominant coherent structures in a plane wake are inferred.

Investigation of causes of geometric distortion in 180 degrees and 360 degrees angular sampling in SPECT.

Abstract: To investigate geometric distortion when 180 degrees or 360 degrees angular sampling techniques are used in single photon emission computed tomography (SPECT), a study of point sources imaged at different positions in a water filled cylindrical phantom, and reconstructed using filtered back projection, was conducted. A simulation study, based upon a serial model of the system point spread function (PSF), was used to investigate the contributions of attenuation, spatial resolution and scatter on distortion of the reconstructed PSFs. To study the geometric distortion in transverse (x-y plane), coronal (x-z plane), and sagittal (y-z plane) sections, the ratios of the full widths at half maximum (FWHM) and full widths at tenth maximum (FWTM) in the x/y, x/z, and y/z directions were calculated for the real and simulated PSFs. These results showed that, in an attenuating medium, there is more distortion of point sources into ovals for 180 degrees than for 360 degrees sampling. The simulation study indicated that the primary cause of geometrical distortion in SPECT studies, is the inconsistency of projections due to variable attenuation and spatial resolution. The impact of scatter on geometric distortion was small as measured by the ratios of FWHMs and FWTMs for PSFs. Attenuation correction applied to acquired PSFs significantly reduced geometric distortion in both 180 degrees and 360 degrees studies. To investigate distortion in extended objects, an Iowa heart phantom was placed inside an Alderson body phantom and 201Tl heart SPECT studies acquired. The phantom images confirmed the conclusion that in transverse sections of 360 degrees studies with arithmetic averaging of opposite views, geometric distortion is reduced compared to 180 degrees. The coronal and sagittal sections were equally distorted in both, the 180 degrees and 360 degrees studies, and the 180 degrees studies yielded better contrast.

Methods for determining transverse dispersion coefficients of porous media in laboratory column experiments

Abstract: Continuous point source and instantaneous finite source methods are presented for determining the transverse dispersion coefficient of saturated porous media in laboratory column experiments. The methods entail injecting a conservative tracer from an injector embedded in a porous medium, monitoring concentration variations with time within the column upgradient from where the tracer impinges on the column wall, and extracting longitudinal and transverse dispersion coefficient values from relative concentration-time data using three-dimensional advection-dispersion formulations. The methods were tested in a column packed with glass beads for comparison with reported flow tank tests. The transverse dispersion coefficient values calculated using column test data agree closely with flow tank results. The methods presented offer new approaches for investigating dispersion phenomena in porous media and especially offer the potential for determining the transverse as well as the longitudinal dispersion coefficient of undisturbed core samples.

Transverse laser-mode structure determination from spatial coherence measurements: Experimental results

Abstract: We demonstrate experimentally the feasibility of a certain coherence-theoretic algorithm for determining the relative modal weights of a laser beam that consists of multiple Hermite-Gaussian transverse modes. A computer-controlled Young's two-pinhole interferometer with a linear CCD array is used for the coherence measurements. The required scaling parameter (beam width) is obtained iteratively by library routines. Numerical simulations on the stability of the algorithm in the presence of experimental noise are also presented.

A posteriori estimates for shear correction factors in multilayered composite cylinders

Abstract: A predictor-corrector approach is presented for calculating the composite shear correction factors and analyzing multilayered composite cylinders. In the predictor phase a two-dimensional first-order shear deformation theory is used to predict the gross response characteristics of the cylinder (vibration frequencies, average through-the-thickness displacements, rotations, and transverse shear strain energy per unit area) as well as the in-plane strains and stresses in the thickness direction. The three-dimensional equilibrium equations and constitutive relations are then used to compute the transverse stresses and strains as well as the transverse shear factors, and they are also used to correct the predicted response quantities of the cylinder. For simply supported multilayered cylinders the response quantities obtained by using the proposed approach are shown to be in close agreement with three-dimensional elasticity solutions for a wide range of lamination and geometric parameters. Also, the potential of the proposed approach for use in conjunction with large-scale finite element models of composite cylinders is outlined.

Flower pot carrying tray with restraining means for plural pots

Abstract: A tray is disclosed for retaining a flower pot having a pot bottom with drain holes. The tray has a planar bottom wall for supporting the pot bottom and restrains the pot from moving parallel to the plane of the tray bottom wall. A protrusion is formed in the tray bottom wall in registration with a pot drain hole. The protrusion has a transverse lip adapted to overlie the pot bottom and restrains transverse movement relative to the plane of the tray bottom wall.

Transverse-electric and transverse-magnetic waves in nonlinear isotropic waveguides

Abstract: A full theory of the interaction between nonlinear transverse-electric and transverse-magnetic waves is derived. A new form of third-order tensor that accounts for the presence of the two polarizations is described and a mathematical discussion of the first integral is presented. The theory is illustrated by a full set of numerical results both for single-interface and thin-film structures.

Process for continuous particle and polymer separation in split-flow thin cells using flow-dependent lift forces

Abstract: A process for continuous particle and polymer separation comprising injecting a stream of carrier fluid containing the material to be separated into the inlet end of a thin channel, adjusting the flow rate to a sufficiently high level that flow-dependent lift forces the different components to different transverse positions by the time they reach the end of the channel, splitting the outlet flow into at least two substreams by means of physical splitters, adjusting the flowrates of the multiple substreams such that the transverse position of the outlet splitting plane divides the particles into enriched fractions, collecting the enriched or separated components from the emerging outlet streams.

Double-layer papermaking fabric having a single system of non-symmetrically extending longitudinal threads

Abstract: A double-layer fabric for the sheetforming section of a papermaking machine which is referred to as a sheet forming fabric or a dewatering fabric consists of an upper layer (1) of transverse threads (3) and a lower layer (2) of transverse threads (4) and (8) which are interwoven with a single system of longitudinal threads (5). Successive transverse threads (4, 8) of the lower layer (2) form pairs and within each pair the lowest points (7) of the transverse thread floats (6) are in alignment. The lowest point (7) of the float of the one transverse thread (4) of a pair is offset from the center of the float (6) in the direction opposite to the direction in which the lowest point (7) of the float (6) of the other transverse thread (6) is offset.

Higher order transverse mode suppression in surface acoustic wave resonators

Abstract: A technique for adjusting the frequency of odd mode transverse waves propagating in a SAW device is described. A pair of localized regions of frequency determining trimming material are deposited onto selected portions of a surface wave propagating surface, to provide localized regions on said surface where the odd order transverse mode has energy maxima. These regions change the acoustic properties and hence the velocity characteristics of the surface wave propagating surface in said regions. The frequency of the odd mode transverse wave is changed accordingly and is preferably changed to match that of the fundamental transverse propagating wave. This decreases the insertion loss of the device at the fundamental frequency and eliminates the odd mode transverse wave propagation characteristic within the operating frequency range of the resonator. In a preferred embodiment, the SAW device further includes an acoustically matched piezoelectric transparent cover disposed over the surface wave propagating surface having disposed thereon a trim pad which is selectively removed to provide the localized regions and thus the localized alterations in the acoustic properties of the surface acoustic wave device.

Characteristics of a longitudinal/transverse coupling slot in crossed rectangular waveguides

Abstract: A rigorous analysis of a broad-wall slot coupler between two crossed rectangular waveguides is presented. The slot is longitudinal and offset from the center line in the main guide and is centered transverse in the branch guide. Integral equations are developed, taking into account finite wall thickness. The integral equations are then solved for the aperture electric field. Coupling slot characteristics are obtained, including the resonant length and dominant mode scattering. Numerical results for resonant length and scattering parameters are presented over a range of offsets, waveguide dimensions, and frequencies. >

High speed perforation machine for perforating predetermined repetitive patterns in a continuous moving web

Abstract: An method and an apparatus for high speed cutting, a predetermined repetitive pattern in a continuous moving web of material. The web is supported and displaced in a flat plane, and a sensor is utilized to detect the lateral position of the web on this plane. At least one cutting element, herein a high pressure water jet, is displaceably supported for movement on two transverse axes in a horizontal plane adjacent a face of the web and generates a cutting beam to cut a predetermined repetitive pattern through the web. The cutting element is secure to a guide member which is displaced in the horizontal plane adjacent the web, and its displacement and rate of speed are controlled by a control device.

An algorithm for three-dimensional reconstruction incorporating cross-plane rays

Abstract: Conventional multislice positron cameras reconstruct a three-dimensional distribution of a positron-emitting radioscope as a set of two-dimensional transverse sections. Consequently, annihilation photons which cross two or more planes are eliminated from the data. Such an approach makes efficient use of the emitted photon flux. A method is proposed which makes more efficient use of the available photons by including both oblique and transverse section in the reconstruction. The implementation of the method consists of centering a scaled convolution filter on each detected coincidence event line and backprojecting the filter values through the three-dimensional reconstruction volume. The final image is normalized to allow for the different number of oblique and transverse sections that contribute to each point in the imaging volume. The method has been evaluated using both simulated data and measured data obtained with a routing area detector positron camera. >

A database of isoinertial trunk strength tests against three resistance levels in sagittal, frontal, and transverse planes in normal male subjects.

Abstract: Spatial joint complexes, such as the spine, require multiaxial systems to adequately assess their functional capacity. The B200 Isostation (Isotechnologies, Inc., Carrboro, North Carolina) is a triaxial system that has three hydraulic pumps under control of an IBM-XT. The transducers measure the torque, angular position, and velocity for all axes simultaneously. There is no isoinertial data base available for strength at different resistances in the sagittal, coronal, and transverse planes. A normal data base for dynamic performance against resistances equal to 30%, 50%, and 70% of the maximum isometric strength of trunk muscles in all three planes was established.

Magnetic sensor with rectangular field distorting flux bar

Abstract: A magnetic sensor for use in measuring the position, velocity, and/or direction of movement of an object having alternating zones of magnetic conductivity with a permanent magnet member having a pole face facing the moving object and having an axis transverse to the direction of movement thereof. A ferromagnetic strip of high permeability is mounted on the face of the magnet coaxial therewith having a length dimension in the direction of movement of the object greater than the width dimension transverse to the direction of movement. The ferromagnetic strip distorts the field of the permanent magnetic member in the area of a pair of the sensor elements such that the flux lines in the area of each of the sensors are urged toward a transverse direction relative to the direction of movement of the object, whereby the flux field in the area of each of the sensor is uniform.

Apparatus for molding tire treads

Abstract: An apparatus for molding articles, particularly tires, of different diameters/circumferences including a plurality of pitches defining a mold cavity, the pitches having transverse faces in generally face-to-face abutment in a closed position of the mold cavity, and at least several of the pitches being of different lengthwise sizes. The pitches in the closed position of the mold cavity defining a predetermined mold configuration which includes portions at angles to the length of the article molded in the mold cavity. The mold configuration matches lengthwise across all of the transverse faces irrespective of the location of the pitches relative to each other and irrespective of the number of the pitches. The latter arrangement permits articles, such as new or retread tires, of different lengths but of the generally same predetermined mold configuration to be molded in a single mold.

On electron acceleration by plane transverse electromagnetic pulses in vacuum

Abstract: The longitudinal acceleration of electrons by the transverse electromagnetic field of laser pulses of definite shapes is studied. It is shown that already a pulse of the length of a half wavelength from a CO 2 laser is sufficient to accelerate an electron to energies up to the order of TeV if intensities of 10 22 W/cm 2 are applied. Various aspects of the electron acceleration by this method are discussed.

Analysis of internal target effects in light ion storage rings

Abstract: This paper considers the rate of beam phase space growth and beam losses caused by thin internal targets in light ion storage rings without beam cooling. The analysis of transverse emittance growth and beam losses by small angle Coulomb scattering is recapitulated. The formalism is extended to analyze the effects of transverse and longitudinal emittance growth by energy loss fluctuations. All target effects can be parametrized by two quantities, the mean square values θ rms 2 and δ rms 2 of the small angle scattering and relative momentum straggling per target traversal. This paper presents simple expressions for the transverse and longitudinal emittance growth, the beam survival probability and the quantities θ rms 2 and δ rms 2 .