Method for calculating the velocity field and the ?suspension? model of a nonlinearly viscous liquid in cylindrical channels with an arbitrary transverse cross section

1986 ◽  
Vol 51 (4) ◽  
pp. 1190-1195
Author(s):  
Yu. G. Nazmeev ◽  
N. M. Zobin ◽  
G. P. Lagutin
Keyword(s):  
Velocity Field ◽  
Viscous Liquid ◽  
Cross Section ◽  
Transverse Cross Section ◽  
Suspension Model

Adaptation of Cardinal Points Symmetry Landmarks Distribution Model to in-vivo B-Mode Ultrasound Images of Transverse Cross-section of Carotid Arteries

2021 ◽  
Vol 6 (7) ◽  
pp. 107-113
Author(s):  
Charles Nnamdi Udekwe ◽  
Akinlolu Adediran Ponnle
Keyword(s):  
Carotid Artery ◽  
Cross Section ◽  
Carotid Arteries ◽  
Region Of Interest ◽  
Transverse Cross Section ◽  
Transverse Plane ◽  
Distribution Model ◽  
Ultrasound Images ◽  
Symmetry Line

The geometry of the imaged transverse cross-section of carotid arteries in in-vivo B-mode ultrasound images are most times irregular, unsymmetrical, full of speckles and usually non-uniform. We had earlier developed a technique of cardinal point symmetry landmark distribution model (CPS-LDM) to completely characterize the Region of Interest (ROI) of the geometric shape of thick-walled simulated B-mode ultrasound images of carotid artery imaged in the transverse plane, but this was based on the symmetric property of the image. In this paper, this developed technique was applied to completely characterize the region of interest of the geometric shape of in-vivo B-mode ultrasound images of non-uniform carotid artery imaged in the transverse plane. In order to adapt the CPS-LD Model to the in-vivo carotid artery images, the single VS-VS vertical symmetry line common to the four ROIs of the symmetric image is replaced with each ROI having its own VS-VS vertical symmetry line. This adjustment enables the in-vivo carotid artery images possess symmetric properties, hence, ensuring that all mathematical operations of the CPS-LD Model are conveniently applied to them. This adaptability was observed to work well in segmenting the in-vivo carotid artery images. This paper shows the adaptive ability of the developed CPS-LD Model to successfully annotate and segment in-vivo B-mode ultrasound images of carotid arteries in the transverse cross-sectional plane either they are symmetrical or unsymmetrical.

Magnetohydrodynamic flow due to the discharge of an electric current in a hemispherical container

1976 ◽  
Vol 73 (4) ◽  
pp. 641-650 ◽  
Author(s):  
C. Sozou ◽  
W. M. Pickering
Keyword(s):  
Free Surface ◽  
Velocity Field ◽  
Flow Field ◽  
Electric Current ◽  
Cross Section ◽  
Analytic Solution ◽  
Closed Loops ◽  
Slow Viscous Flow ◽  
Axial Cross Section ◽  
Section Form

In this paper we consider the flow field induced in an incompressible viscous conducting fluid in a hemispherical bowl by a symmetric discharge of electric current from a point source at the centre of the plane end of the hemisphere. This plane end is a free surface. We construct an analytic solution for the slow viscous flow and a numeriacl solution for the nonlinear problem. The streamlines in an axial cross-section form two sets of closed loops, one on either side of the axis. Our computations indicate that, for a given fluid, when the discharged current reaches a certain magnitude the velocity field breaks down. This breakdown probably originates at the vertex of the hemispherical container.

Curvature and Out-of-Plane-Strain for Generalized Plane Strain

1972 ◽  
Vol 39 (3) ◽  
pp. 827-829 ◽  
Author(s):  
V. J. Parks
Keyword(s):  
Plane Strain ◽  
Cross Section ◽  
Central Region ◽  
Transverse Cross Section ◽  
Infinite Length ◽  
Out Of Plane ◽  
Plane Solution ◽  
Generalized Plane Strain

Out-of-plane strains and stresses are determined using reciprocity for the central region of very long bars (approaching infinite length) of uniform transverse cross section subjected to the same in-plane loads on every cross section. The loading explicitly specifies no end loads on the bars. The results are obtained without recourse to the in-plane solution. Conversely the end force and moment are determined for the case where the out-of-plane strain is zero.

Finite element modeling of guyed back spars in cable logging

2004 ◽  
Vol 34 (4) ◽  
pp. 817-828 ◽  
Author(s):  
Albert Saravi ◽  
C Kevin Lyons
Keyword(s):  
Finite Element ◽  
Normal Stress ◽  
Cross Section ◽  
A Priori ◽  
Element Model ◽  
Transverse Cross Section ◽  
Stress Fields ◽  
Stress Concentrations ◽  
Maximum Normal Stress ◽  
Tree Method

In this study a finite element model of a back spar system was developed with three guylines opposing the skyline strap tension. In this paper the allowable skyline strap tension is the tension in the skyline strap that results in the maximum normal stress on a transverse cross section of the tree being equal to an assumed allowable stress. An iterative routine was developed to find the allowable skyline strap tension, and this routine was found to converge rapidly from initial values that were below and above the allowable skyline strap tension. Two algorithms were developed for finding the maximum normal stress on a transverse cross section of a tree, method 1 and method 2. If the plane that the tree displaced in was known a priori, then method 2 could be used, and it was found to be less sensitive to mesh coarseness. If the plane that the tree displaced in was not known a priori, then method 1 had to be used with a less coarse mesh. It was found that the stress concentrations due to simplified cable connections were not significant for rigging configurations that allowed a larger rigging point displacement. The rigging configurations that allowed larger rigging point displacements have stress fields that are dominated by bending, while for rigging configurations that allow only small rigging point displacements, the stress fields are dominated by axial compression.

scholarly journals Spin Density Matrix Elements in Exclusive Production of Omega Mesons at HERMES

2016 ◽  
Vol 40 ◽  
pp. 1660063
Author(s):  
Hrachya Marukyan
Keyword(s):  
Density Matrix ◽  
Spin Density ◽  
Cross Section ◽  
Transverse Cross Section ◽  
Spin Density Matrix ◽  
Pion Pole ◽  
Matrix Elements ◽  
Unnatural Parity ◽  
Proton Data ◽  
Parity Exchange

Exclusive electroproduction of [Formula: see text] mesons on unpolarized hydrogen and deuterium targets is studied at HERMES in the kinematic region of [Formula: see text], [Formula: see text], and [Formula: see text]. The data were accumulated during the 1996-2007 running period using the [Formula: see text] longitudinally polarized electron or positron beams at HERA. The determination of the virtual-photon longitudinal-to-transverse cross-section ratio shows that a considerable part of the cross section arises from transversely polarized photons. Spin density matrix elements are derived and presented in projections of [Formula: see text] or [Formula: see text]. Violation of s-channel helicity conservation is observed for some of these elements. A sizable contribution from unnatural-parity-exchange amplitudes is found and the phase shift between those amplitudes that describe transverse [Formula: see text] production by longitudinal and transverse virtual photons is determined for the first time. Good agreement is found between the HERMES proton data and results of a pQCD-inspired phenomenological model that includes pion-pole contributions.

Experimental Study of Rotating Stalls in a Four-Stage Axial Compressor

2002 ◽  
Author(s):  
Y. Levy ◽  
J. Pismenny ◽  
A. Reissner ◽  
W. Riess
Keyword(s):  
Cross Section ◽  
Axial Compressor ◽  
Pressure Oscillation ◽  
Transverse Cross Section ◽  
Rotating Stall ◽  
Pressure Variation ◽  
Time Diagram ◽  
Rotor Speed ◽  
Axial Compressors

The relationships between the frequencies of pressure oscillation ωOSC and the rotor speed (frequencies of rotor rotation) ωRR, as well as between the phases of pressure oscillation and geometrical angles of the sensor locations on the compressor casing (in the transverse cross-section) were determined experimentally. In addition, the phase–location relation permitted determination of the number of stall cells under established rotating stall. Literature on rotating stall in axial compressors typically refers to rotating stall with frequencies less than the rotor speed. This paper is concerned with two types of rotating stall, observed during experiments in a four-stage axial compressor, operating at the same rotor speed, n/nd = 0.95, where n is the rotor speed and nd the rotor data-sheet speed. The rotating stall frequencies were both, smaller and larger than the rotor speed. The relationships between ωOSC and ωRR were determined by four methods: directly from the time diagram of the pressure oscillation, from the diagrams of pressure variation in space and time, from the autocorrelation characteristics, and from the frequency characteristics of the pressure signals. All methods indicated values of ωOSC/ωRR in the form of integer ratios, 3:7 and 11:2. The phases of pressure oscillation in the transverse cross-section are equal to the sensor angles in compressor stator (in the case ωOSC/ωRR = 3:7) or are three times larger (in the case ωOSC/ωRR = 11:2), in accordance with the classical theory of single-cell and three-cell configurations of rotating stall, respectively.

Velocity Field and Energy Dissipation in Viscoplastic Flow in Tubes of Non-Circular Cross-Section

2014 ◽  
Author(s):  
Mario F. Letelier ◽  
Dennis A. Siginer ◽  
Felipe Godoy
Keyword(s):  
Energy Dissipation ◽  
Velocity Field ◽  
Yield Stress ◽  
Cross Section ◽  
Mechanical Energy ◽  
Longitudinal Velocity ◽  
Circular Cross Section ◽  
Viscoplastic Flow ◽  
Entire Cross Section ◽  
Cross Sectional

An analytical method for determining the velocity field, shear stress and energy dissipation in viscoplastic flow in non-circular straight tubes is presented. Bingham’s model of fluid is used for the case of tubes with several cross-sectional contours that can be arbitrarily chosen through a shape factor imposed in the solution for the longitudinal velocity. The analysis is extended to steady flow in tubes in which the cross-section contour exhibits sharp corners. In these cases three flow zones are distinguished: stagnant, non-zero deformation, and plug zones. The method provides the expressions for determining the boundaries and characteristics of those three zones for a wide variety of cross-section shapes. In particular the dynamics of plug-zones for large values of the yield stress and for contours that markedly differ from circumferences is analyzed. Energy dissipation is determined throughout the entire cross-section, so that the effect of shape on mechanical energy loss is assessed in terms of the yield stress and viscosity of the fluid. Some general expressions that help understand energy dissipation mechanisms are derived by using natural coordinates for the velocity field and related variables. These results draw on several recent works from other researchers and the present authors, which have highlighted the significant difficulty of determining the zones of zero deformation in viscoplastic flow when the related solid boundaries are not elementary.

Sign in / Sign up

Export Citation Format

Share Document