Showing papers on "Transverse plane published in 1975"

Ripple suppression during reconstruction in transverse tomography

Abstract: In many transverse tomographic reconstruction techniques using filtered projections, ringing or overshoot is found in regions where the attenuation suddenly changes. Such artifacts are obtained with iterative techniques as well. A modification of the filter often used in corrected tomography which produces very small ringing in such regions is described. A transmission device such as the EMI Scanner was computer simulated. Projections were calculated through a phantom and the phantom then reconstructed using different filters. The phantom consisted of a disc with diameter 32 arbitrary units centred at the origin of the plane.

Coupling optical waveguides by tapers

Abstract: The coupling of single-mode optical waveguides through the use of expanding and contracting tapers is examined theoretically. In particular, the problems of angular and transverse misalignments of an input and output taper are investigated along with the effects of the taper itself. A tradeoff is found to exist, that is, widening the guide by means of a taper leads to less critical coupling tolerances for transverse displacements, but tighter tolerances for angular misalignment. Similar considerations apply to large core singlemode fibers.

1975 Memorial Award Paper. Image generation and display techniques for CT scan data. Thin transverse and reconstructed coronal and sagittal planes.

Abstract: The various limitations to computerized axial tomographic (CT) interpretation are due in part to the 8-13 mm standard tissue plane thickness and in part to the absence of alternative planes of view, such as coronal or sagittal images. This paper describes a method for gathering multiple overlapped 8 mm transverse sections, subjecting these data to a deconvolution process, and then displaying thin (1 mm) transverse as well as reconstructed coronal and sagittal CT images. Verification of the deconvolution technique with phantom experiments is described. Application of the phantom results to human post mortem CT scan data illustrates this method's faithful reconstruction of coronal and sagittal tissue densities when correlated with actual specimen photographs of a sectioned brain. A special CT procedure, limited basal overlap scanning, is proposed for use on current first generation CT scanners without hardware modification.

Ignition and maintenance of subsonic plasma waves in atmospheric pressure air by cw CO2 laser radiation and their effect on laser beam propagation

Abstract: Laser supported combustion (LSC) waves, subsonically propagating plasma, are ignited from solid targets and maintained in atmospheric pressure air using focused high−power, as high as 15 kW, cw CO2 laser radiation. The intensity necessary to ignite LSC waves, Ii, is measured for steel and aluminum targets as a function of beam focal spot diameter and wind velocity transverse to the beam axis as is the intensity needed to maintain such waves in atmospheric pressure air, Im. In the absence of a transverse wind, the quantities Ii and Im are essentially identical for diameters smaller than 0.1 cm, but Ii is substantially larger at larger diameters. The reason for this is discussed in terms of the ignition mechanism itself. In the presence of a 20−m/sec transverse wind, Im and Ii are essentially identical at 0.2 cm, the largest diameter for which Ii was determined. The measurements of Im extend to 0.5 cm beam diameter and indicate, in the absence of the transverse wind, that while thermal conduction determines...

Bifurcational instability of an atomic lattice

Abstract: I n a recent article N.H. Macmillan and A. Kelly (1972) have confirmed on the basis of a linear eigenvalue analysis that a mechanically stressed perfect crystal can exhibit a bifurcational instability at stresses ranging to 20 per cent below that of the limiting maximum of the primary stress-strain curve. The question thus arises as to whether the branching point is in a non-linear sense either stable or unstable. In the former case, perfect and slightly imperfect crystals would be capable of sustaining stresses over and above the eigenvalue critical stress. In the unstable case, however, this eigenvalue stress would represent the ultimate strength of a perfect solid, while an imperfect crystal would fail at a limiting stress substantially below the eigenvalue. At 20 per cent below the limit point such a branching point is essentially distinct, and the non-linear stability analysis needed to answer this question is provided by a recently established general branching theory for discrete conservative systems. Often, however, the two critical equilibrium states are much nearer than this, and the branching theory is here suitably extended to cover the case of near-compound instabilities. An illustrative study of a close-packed crystal under uniaxial tension is next presented. A kinematically-admissible displacement field is employed and a bifurcation point is located on the primary equilibrium path just before the limiting maximum, the eigenvector being associated with a transverse shearing strain. Under these conditions a corresponding small transverse shearing stress would represent an ‘imperfection’, and the non-linear branching problem is next studied using the new general theory. This shows (in excellent quantitative agreement with an ad hoc numerical solution) that the branching point is non-linearly unstable with a quite severe imperfection-sensitivity which manifests itself as a sharp cusp on the failure-stress locus.

Axial tomography and three dimensional image reconstruction

Abstract: A number of existing $gamma$ cameras for imaging of radioisotope distributions give depth information about the distribution. These devices have in common that they provide tomographic images of the object, that is, that images of a given object plane have that plane in focus and all other object planes contribute an out-of-focus background superimposed on the in-focus image. A method is described for three dimensional reconstruction of these axial tomographic images which removes the blurred off-plane activity from a number of transverse planes simultaneously. The method is applicable to a number of tomographic cameras, such as the multiple single-pinhole camera, the rotating slanted-hole collimator, the Anger focussing tomographic scanner, and the positron camera. The method can be implemented on a small computer having a disc system. (auth)

The effect of interlayers on the transverse stresses in fiber composites

Abstract: Numerical results are given of calculations of the radial, transverse, and shear stresses in the matrix surrounding a cylindrical inclusion in plane strain perpendicular to the cylinder axis, this being taken as a model of a fiber composite under transverse loading. It is shown that the presence of an interlayer on the fiber at a thickness which is a small fraction of the fiber diameter can significantly affect the stress concentrations in the matrix. The interlayer-fiber ‘composite’ can be ‘matched’ to the matrix by suitable choice of interlayer elastic moduli. In particular, if the shear modulus of the interlayer is smaller than that of the matrix and its Poisson's ratio is very small, the stress concentrations in the matrix are considerably reduced and the composite should be less subject to failure by delamination.

X-ray diffraction gratings

Abstract: An x-ray diffraction grating consisting of a structure having a surface capable of reflecting x-rays, said surface being grooved so that in cross-section the profile of said surface alternates regularly between geometrically similar lines, in which the height of the alternation varies significantly over the area of the surface. The grating may be plane or curved; the variation in height may occur as a single step, a plurality of steps or may be continuous; the variation may occur either transverse to or parallel to the grooving.

Transverse oscillations of a circular cylinder in uniform flow.

Abstract: : The mean in-line force and the time dependent transverse force acting on a circular cylinder undergoing periodic transverse oscillations in an otherwise steady flow was measured for various amplitudes and frequencies of oscillation at several steady flow velocities. The experiments were carried out in a recirculating water tunnel operating as a closed channel at the test section. The mean in-line force has been expressed in terms of a mean drag coefficient C sub di and plotted as a function of A/D and D/VT. The time dependent transverse force has been expressed in terms of the Fourier-averaged drag and inertia coefficients C sub di and C sub ml and plotted as functions of the relative amplitude A/D and the period parameter VT/D. The results have shown that the mean in-line force is significantly larger than that corresponding to steady flow about a non-oscillating cylinder and that energy may be transferred to the oscillating cylinder from the fluid at or near the vortex-shedding frequencies for the A/D values tested. (Author)

A transverse loading system applied to a modified Harrington instrumentation.

Abstract: Observations using standard Harrington Instrumentation revealed that while maximal distractive forces are applied it is possible to produce further correction of spinal deformity by applying a lateral force. Modifications to the standard Harrington Instrumentation by applying a transverse loading system have been made in order to produce this added correction. The transverse load is applied as nearly as possible in the same plane as the bearing points of hooks, i.e., below the axis of the rods. Transverse loading helps to reduce the distance from the apex of the curve to the midline, thereby producing a more stable spine as well as providing additional support on the convex side. The system is ideal for flexible curves with little kyphosis. Photogrammetry reveals that there was no significant rotation occurring after the application of the transverse load. To date, Instrumentation has been used in 10 patients with success.

Thin Plate Design for Transverse Loading

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Honeycomb structure with high thermal shock resistance

Abstract: A honeycomb structure is formed with a plurality of interconnected partitions which are unidirectionally discontinuous in a plane transverse to the longitudinal axis of the structure and which form a plurality of diamond-shaped cellular open portions extending longitudinally through the structure, to thereby provide a honeycomb structure with a relatively low bulk modulus and substantially isotropic moduli in transverse planes perpendicular to the longitudinal axis of the honeycomb structure, thus providing improved thermal shock resistance.

Photoelastic Investigation of a Thick Plate With a Transverse Crack

Abstract: The purpose of this investigation was to experimentally test one of the assumptions of a recent modified version of the theory of generalized plane stress. The form postulated by the theory for the stress variation through the thickness of a plate containing a crack will be compared with that obtained by three-dimensional photoelastic analysis. Specimens covering the range from thin to moderately thick plates were examined by the frozen stress technique. The experimentally measured transverse variation of the in-plane stress components σx and σy was in excellent agreement with that postulated by the theory.

Scattering, energy loss and X-ray production of protons of 150–275 keV at grazing incidence on tungsten crystals

Abstract: Experiments are reported in which a finely collimated beam of protons were incident on a flat tungsten crystal or an amorphous WO3 surface, The yields of W (M shell) or O (K shell) X-rays were measured as a function of proton energy (150–275 keV) and orientation; also detected were the scattered protons and their energy spectrum. The observations are discussed in terms of channelling theory and projected motion in the plane transverse to the atomic rows. By a combination of analytical theory and computer simulation it is shown that in this plane the kinetic energy ψ2 E 1 and the direction of incidence β in should be the determining factors of yield and scattering. The observations bear this out and special two-dimensional processes can be identified such as trajectory focusing, quasi-planar channelling and surface semi channelling. Oxygen in the crystal surface is detected and shown to lie on a different lattice from the tungsten, to have a surface stoichiometry close to WO3 and to extend some 10...

Biomechanics of water-pumping by chaetopterus variopedatus renier. skeletomusculature and kinematics.

Abstract: 1. The skeletomusculature of the water-pumping segments of Chaetopterus variopedatus was examined in detail and the behavior of the segments during active water-propulsion was analyzed using cinemaphotographic techniques. 2. The musculature of the pumping segments consists largely of thin sheets of radial, transverse, and circular fibers, located immediately beneath the thin integument. Exceptions to this are the numerous isolated fibers running axially across the coelomic cavity of the parapodial rim and the major remotor muscles which originate in the neuropodial "sucker" of the adjacent posterior segment. 3. The motion of the pump segments is basically reciprocative, with the axial displacement during power and recovery strokes approximating a sine function. Centrifugal radial displacements (during the power stroke) effectively seal the lumen of the tube; centripital radial displacements (during the recovery stroke) allow water from the inlet side of the tube to by-pass the pump segment. 4. Comparison of the muscle anatomy with the displacements and shape changes which take place during water-propulsion permitted analysis of the muscle actions during the pump cycle. It is concluded that: (a) both axial and radial displacements during the power stroke are caused by a single set of muscles (remotors); (b) maintenance of the extended-disk configuration is consequent upon coelomic fluid being forced into the parapodial rim, with the axial muscle fibers acting as guy-wires to resist overexpansion; (c) most of the sheet-like muscle groups contract during the recovery stroke, thereby causing the segment to assume a nearly spherical configuration; and (d) two sets of muscles (promotors, oblique parapodial) are responsible for the axial displacement during recovery. 5. The water-pumping mechanism of Chaetopterus is compared to those of the majority of worms, which are based on persistaltic or undulatory movements.

Trailer for farm machinery

Abstract: A trailer construction in which the trailer bed is articulated into a plurality of sections for relative pivotal movement about one or more transverse horizontal axes, and which includes means for temporarily lowering the bed of the trailer to rest directly on the ground, for unimpeded loading by movement transverse of the bed, longitudinal loading from behind still being available as well.

Direction-indicating surface marker and the like

Abstract: A distinctively and unambiguously marking of the directions of travel on motoring highways, airports and other surfaces with the aid of a thin novel saw-tooth marker strip that is adhered to the traveling surface and has distinctively colored successive surfaces of retroreflecting materials, including transverse cylindrical refractive elements embedded between wedges in the thin strip.

Electrical connector and method of making same

Abstract: A plurality of conductor grasping and piercing ridges are selectively disposed at an oblique angle to the longitudinal axis of a metallic crimpable ferrule and extend outwardly from its interior wire receiving surface so that upon crimping the ferrule about a wire inserted therewithin, the ridges penetrate the periphery of the wire along an obliquely oriented path defining a number of incrementally displaced transverse planes longitudinally offset from one another to avoid shearing or severing the wire along any one common transverse plane.

Cueing device for phonographs

Abstract: The cueing device, to facilitate the operation of bringing the stylus of a phonograph pickup into engagement with a selected unrecorded zone of a phonograph record, so that the next recorded zone will be played, may include a light source mounted on the pickup for providing a light beam to be reflected from the face of the record to a photoelectric device on the pickup. A utilization device, preferably including a visual signal mounted on the pickup, is operated when the reflected light beam is received by the photoelectric device from the unrecorded zones. The light source, the photoelectric device and the light path therebetween are preferably mounted in a transverse perpendicular plane, transverse to the record grooves and generally perpendicular to the record face. The light reflected by the unrecorded zones is given a polarization in a plane transverse to such transverse perpendicular plane. A polarized light transmitting device, such as means forming a slit, is preferably mounted on the pickup between the record and the photoelectric device and is oriented to favor the transmission of the light polarized by the reflection from the unrecorded zones. The slit may have its longer dimension transverse to the plane of the light path. This construction produces an increased change in the photoelectric signal when the light beam makes a transition between recorded and unrecorded zones.

Apparatus for contouring magnetic head surfaces and method therefor

Abstract: A spherical wasp-waist shaped contour is formed on the surface of a magnetic head by rotating a lap plate against a single contact point on the head surface at a time. An arc along the head's length is defined by a fixed longitudinal radius. For each increment along the longitudinal arc, a different arc transverse thereto is defined by a variable transverse radius. The point of contact between the head and the lap plate moves along each transverse arc in sequence from one end of the longitudinal arc to the other and back again until the desired shape and depths are achieved. The longitudinal radius is fixed by the spacing selected between the lap plate on one side of the head and a longitudinal head rocking axis on the other side of the head. The transverse radius is determined by the spacing chosen between the lap plate and a transverse rocking axis placed on the same side of the head as the longitudinal rocking axis. The head is incremented to move its point of contact with the lapping plate along the longitudinal arc under the control of prespecified quantities. For each longitudinal increment, the contact point is moved along a transverse arc defined for that point on the longitudinal arc by prespecified quantities. The head is fed closer to the lap plate in steps until a predetermined quantity of surface material is removed.

Improved Structural Analysis Technique for Orthogonal Weave Carbon-Carbon Materials

Abstract: An approximate technique is presented that enables one to use two-dimensional axisymmetric solid computer codes for the analysis of three-dimensi onal rectangularly orthotropic materials fabricated into axisymmetric shapes and loaded axisymmetrically. The technique consists of modifying the polar coordinate constitutive relations to accomodate a rectangularly orthotropic material Specifically the proposed constitutive modification: accounts for the transverse orthotropy by including Gxy in the equations as an independent variable; degenerates to the transversely isotropic relations for Ex = Ey = E and Gxy = Ex/2(l + vxy); and accurately predicts the stresses in a rotating and thermally loaded rectangularly orthotropic disk whereas analyses restricted to the assumption of transverse isotropy can lead to significant errors.

Load handling apparatus

Abstract: A load handling apparatus including a frame, an apparatus head mounted on the frame and rotatable in a horizontal plane and an arm mounted on the apparatus head. The arm has an inner portion which is in the form of a parallelogram linkage with two parallel longitudinal links which are swingable in a vertical plane relative to the apparatus head and are connected by joints, at their ends, to an outer transverse link and an inner transverse link parallel thereto. The arm also has an outer portion which is an extension of the transverse outer link of the inner portion and supports, at its outer extremity, a holder for a load. The joint between the inner transverse link and a first of the longitudinal links is adjustable in a vertical direction by shifting relative to the apparatus head. The second of the longitudinal links has a follower which is spaced from the joint associated with the inner transverse link, is guided to follow a horizontal path once the arm is swung and is located on a straight line through the outer extremity of the outer portion and the adjustable joint.

TM waves in nonlinear self‐focusing media

Abstract: In this paper, properties of stationary waves of the transverse magnetic (TM) type which have two electric field components, i.e., axial and transverse ones, in a nonlinear self-focusing medium are discussed. Waves of the TM type are categorized into a solitary wave and several types of waves oscillating in the transverse plane. Analytical expressions of oscillating waves are obtained by using an asymptotic expansion and its extension for the large nonlinearity as well as the small one of the medium. A solitary wave is also discussed numerically, and some differences between the solitary waves of TE and TM types are mentioned.

Cleated conveyor belt

Abstract: An improved conveyor belt for use in a magnetic waste separator characterized by the provision of protective cleats mounted transverse the conveyor belt. The cleats are strategically positioned to protect the belt from abrasion caused by the sharp-edged metal fragments being processed. Further, the particular configuration and spacing of the cleats enhances tumbling or bouncing of the separated metal fragments which serves to reduce the amount of entrained nonmagnetic materials, thereby increasing separator efficiency.