Velocity Field Computation in Plastic Flow in Non-Circular Tubes Using Natural Coordinates

2012 ◽  
Author(s):  
Mario F. Letelier ◽  
Juan S. Stockle
Keyword(s):  
Velocity Field ◽  
Plastic Flow ◽  
Momentum Equation ◽  
Senior Author ◽  
Radius Of Curvature ◽  
Natural Coordinates ◽  
Cross Sectional ◽  
Relevant Variable ◽  
Bingham Plastic ◽  
Circular Tubes

A numerical method to determine the velocity field, and related variables, in plastic flow in non-circular straight ducts is presented. The method is an extension of previous work of the senior author related to modeling laminar flow in pipes of arbitrary cross-sectional contours using natural coordinates. In this case the concept of “natural coordinates” is applied to the system of orthogonal curves determined by the plane isovels and their normal counterparts. The momentum equation for the axial velocity is expressed in natural coordinates in which one relevant variable is the radius of curvature of isovels. The method is applied to a selected set of shapes when the fluid is a Bingham plastic. Isovels and plug zones are determined drawing on the properties of the isolvels and normal curves. Computations start at the pipe perimeter and advance toward the center.

scholarly journals Publishing at any cost: a cross-sectional study of the amount that medical researchers spend on open access publishing each year

BMJ Open ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. e047107
Author(s):  
Mallory K. Ellingson ◽  
Xiaoting Shi ◽  
Joshua J. Skydel ◽  
Kate Nyhan ◽  
Richard Lehman ◽  
...  
Keyword(s):  
Open Access ◽  
Senior Author ◽  
High Impact ◽  
Open Access Publishing ◽  
Original Research ◽  
Potential Cost ◽  
Cross Sectional ◽  
Review Articles ◽  
Open Access Journals ◽  
Medical Researchers

ObjectiveTo estimate the financial costs paid by individual medical researchers from meeting the article processing charges (APCs) levied by open access journals in 2019.DesignCross-sectional analysis.Data sourcesScopus was used to generate two random samples of researchers, the first with a senior author article indexed in the ‘Medicine’ subject area (general researchers) and the second with an article published in the ten highest-impact factor general clinical medicine journals (high-impact researchers) in 2019. For each researcher, Scopus was used to identify all first and senior author original research or review articles published in 2019. Data were obtained from Scopus, institutional profiles, Journal Citation Reports, publisher databases, the Directory of Open Access Journals, and individual journal websites.Main outcome measuresMedian APCs paid by general and high-impact researchers for all first and senior author research and review articles published in 2019.ResultsThere were 241 general and 246 high-impact researchers identified as eligible for our study. In 2019, the general and high-impact researchers published a total of 914 (median 2, IQR 1–5) and 1471 (4, 2–8) first or senior author research or review articles, respectively. 42% (384/914) of the articles from the general researchers and 29% (428/1471) of the articles from the high-impact medical researchers were published in fully open access journals. The median total APCs paid by general researchers in 2019 was US$191 (US$0–US$2500) and the median total paid by high-impact researchers was US$2900 (US$0–US$5465); the maximum paid by a single researcher in total APCs was US$30115 and US$34676, respectively.ConclusionsMedical researchers in 2019 were found to have paid between US$0 and US$34676 in total APCs. As journals with APCs become more common, it is important to continue to evaluate the potential cost to researchers, especially on individuals who may not have the funding or institutional resources to cover these costs.

Stiffness Constants for Composite Beams Including Large Initial Twist and Curvature Effects

1995 ◽  
Vol 48 (11S) ◽  
pp. S61-S67 ◽  
Author(s):  
Carlos E. S. Cesnik ◽  
Dewey H. Hodges
Keyword(s):  
Wave Length ◽  
Three Dimensional ◽  
Radius Of Curvature ◽  
Cross Sectional ◽  
Curvature Effects ◽  
Three Dimensional Representation ◽  
Stiffness Model ◽  
Sectional Analysis ◽  
Three Dimensional Elasticity ◽  
Coupling Phenomena

An asymptotically exact methodology, based on geometrically nonlinear, three-dimensional elasticity, is presented for cross-sectional analysis of initially curved and twisted, nonhomogeneous, anisotropic beams. Through accounting for all possible deformation in the three-dimensional representation, the analysis correctly accounts for the complex elastic coupling phenomena in anisotropic beams associated with shear deformation. The analysis is subject only to the restrictions that the strain is small relative to unity and that the maximum dimension of the cross section is small relative to the wave length of the deformation and to the minimum radius of curvature and/or twist. The resulting cross-sectional elastic constants exhibit second-order dependence on the initial curvature and twist. As is well known, the associated geometrically-exact, one-dimensional equilibrium and kinematical equations also depend on initial twist and curvature. The corrections to the stiffness model derived herein are also necessary in general for proper representation of initially curved and twisted beams.

scholarly journals Could Emotional Intelligence Ability Predict Salary? A Cross-Sectional Study in a Multioccupational Sample

2021 ◽  
Vol 18 (3) ◽  
pp. 1322
Author(s):  
Martin Sanchez-Gomez ◽  
Edgar Breso ◽  
Gabriele Giorgi
Keyword(s):  
Emotional Intelligence ◽  
Interpersonal Relationships ◽  
Work Experience ◽  
Ad Hoc ◽  
Preliminary Evidence ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Repair Capacity ◽  
Relevant Variable ◽  
Correlation And Regression Analysis

The study of emotional intelligence (EI) in work environments is a trending topic. However, few studies have examined the relationship between EI and salary. Therefore, the presented research aims to analyze the influence of EI on salary using a multioccupational sample. The participants were 785 subjects aged between 18 and 58 years (M = 39.41; SD = 10.95). EI ability was measured using the Mobile Emotional Intelligence Test (MEIT), while the salary was collected together with other sociodemographic variables in a questionnaire created ad hoc. After controlling for the age, gender, social class, educational level, and work experience variables, the results of correlation and regression analysis showed that participants with higher EI and emotional-repair capacity generally have higher salary. These findings provide preliminary evidence that EI is a relevant variable in achieving career success. The ability to channel and manage emotions could help employees develop stronger interpersonal relationships, leading to higher positions and greater financial compensation.

Prediction for Post-Forming Spring Back of CICC in the Superconducting Tokamak Fusion Device via Virtual Manufacturing

2000 ◽  
Author(s):  
Yeong Sung Suh ◽  
Jong Sung Ahn ◽  
Sun Woong Choi ◽  
Hyun Ki Park ◽  
Yong Jin Kim ◽  
...  
Keyword(s):  
Residual Stress ◽  
Cross Section ◽  
Virtual Manufacturing ◽  
Von Mises Stress ◽  
Radius Of Curvature ◽  
Spring Back ◽  
Cross Sectional ◽  
Fusion Device ◽  
Roll Bending ◽  
Superconducting Tokamak

Abstract To construct the CICC for the superconducting Tokamak fusion device, the 3-roll bending, that inherently has a difficulty to form the coil with accurate radius of curvature, is used for continuous winding. In order to obtain precise dimension, a trial-an-error operation is inevitable. To reduce the effort of tryout, a relation between travel of the bending roller and spring back displacement was obtained via virtual manufacturing. The radius of CICC after forming was expressed as a function of the bend-roll travel. Next, the variation of the CICC cross-section (reduction of the conduit cross-section) was investigated during the first turn and during conduit bending with largest curvature. With largest curvature, the cross-sectional area was not much reduced. Finally, the residual stress on the CICC before roll bending was measured in order to examine the influence of the original residual stress on the final deformation behavior. The principal stress and von Mises stress were measured at the surface of CICC using specially designed strain gauge. The measured values were considered in the virtual forming. The results indicate that the residual stresses generated during the fabrication of the CICC (before coiling) do not have much influence on the final stress state.

scholarly journals Correlation of refractive error with axial length and corneal topography

2016 ◽  
Vol 15 (1) ◽  
pp. 25-33
Author(s):  
Surabhi Ruia ◽  
Poonam Kishore ◽  
Vinita Singh ◽  
Nitin Chaudhary
Keyword(s):  
Negative Correlation ◽  
Refractive Error ◽  
Axial Length ◽  
Corneal Topography ◽  
Radius Of Curvature ◽  
Cross Sectional ◽  
Positive Correlation ◽  
Study Materials ◽  
Group 5 ◽  
Group 2

Purpose: To collect and analyze normative data about corneal topography and axial length in various refractive errors in Indian population.Design: Cross-sectional observational study. Materials and Method: Three hundred eyes (150 patients) of age group 12-35 yrs were arranged in 5 groups according to refractive status; Group 1 (n=44): myopia of SphericalEquivalent (SE) > 6 D; Group 2 (n=67): myopia of SE >0.5 D to 6 D; Group 3 (n=88): nearly emmetropic of SE -0.5 D to +0.5 D; Group 4 (n=59): hypermetropia of SE >0.5 to 6 D; Group 5 (n=42): hypermetropia of SE > 6 D. Axial length(AL), central radius of curvature of cornea (CR), central power of cornea (CK) , Al/CR ratio for each group were documented . Correlation with SE and among each other was studied. Results: Mean AL (in mm) of myopic patients (n=111) was 24.23 ± 1.34, emmetropic (n=88) 22.62 ± 0.94 and hypermetropics (n=101) 20.73 ±0.94. Mean CR (in mm) of myopic patients was 7.55 ± 0.35, emmetropics was 7.70 ±0.32, and hypermetropes was 7.99 ±0.35. Mean CK (in D) of myopics was 44.86±2.59, emmetropes was 43.91±1.76, and hypermetropes was 42.32±1.89. Mean AL/CR ratio of myopics was 3.22 ± 0.29, emmetropics 2.94± 0.07, and hypermetropics 2.60 ± 0.19. AL was negatively correlated with SE(r=-0.91, p<0.0001) and positively with AL/CR(r=0.88, p<0.0001) and CK (r=0.36, p<0.0001). CR was negatively correlated with AL/CR (r=-0.74, p<0.0001) while positively correlated with SE (r=0.62, p<0.0001). CK showed positive correlation with AL/CR (r=0.75, p<0.0001) while negative correlation with SE (r=-0.61, p<0.0001). AL/CR was negatively correlated withSE(r=-0.95, p<0.0001). Conclusion: This study showed a negative correlation between axial length and refractive error and between AL/CR ratio and refractive error with stronger inverse relationship in hypermetropes than myopes. There was a positive correlation of CR with SE with a weaker direct relationship in myopes than hypermetropes. 

On the Plastic Flow of Coulomb Solids Beyond Original Failure

1959 ◽  
Vol 26 (4) ◽  
pp. 599-602
Author(s):  
A. W. Jenike ◽  
R. T. Shield
Keyword(s):  
Velocity Field ◽  
Stress Field ◽  
Plastic Flow ◽  
Yield Function ◽  
Two Dimensions ◽  
Rigid Plastic ◽  
Variable Yield ◽  
Angle Of Friction ◽  
Effective Angle

Abstract Principles developed for rigid-plastic solids exhibiting Coulomb’s properties are adapted to the analysis of flow beyond original failure. A variable yield function is proposed to account for the changes of cohesion during flow and equations are evolved for the stress field in two dimensions. It is shown that, while in the stress field an effective angle of friction larger than the actual angle of friction is mandatory for these materials, in the velocity field the materials can be assumed incompressible.

Approximation of Physical Spline with Large Deflections

2021 ◽  
pp. 3-18
Author(s):  
Viktor Korotkiy ◽  
Igor' Vitovtov
Keyword(s):  
Mathematical Problem ◽  
Minimum Energy ◽  
Internal Stresses ◽  
Radius Of Curvature ◽  
Large Deflections ◽  
Bezier Curves ◽  
Bézier Curves ◽  
Cross Sectional ◽  
Elastic Line ◽  
Average Curvature

Physical spline is a resilient element whose cross-sectional dimensions are very small compared to its axis’s length and radius of curvature. Such a resilient element, passing through given points, acquires a "nature-like" form, having a minimum energy of internal stresses, and, as a consequence, a minimum of average curvature. For example, a flexible metal ruler, previously used to construct smooth curves passing through given coplanar points, can be considered as a physical spline. The theoretical search for the equation of physical spline’s axis is a complex mathematical problem with no elementary solution. However, the form of a physical spline passing through given points can be obtained experimentally without much difficulty. In this paper polynomial and parametric methods for approximation of experimentally produced physical spline with large deflections are considered. As known, in the case of small deflections it is possible to obtain a good approximation to a real elastic line by a set of cubic polynomials ("cubic spline"). But as deflections increase, the polynomial model begins to differ markedly from the experimental physical spline, that limits the application of polynomial approximation. High precision approximation of an elastic line with large deflections is achieved by using a parameterized description based on Ferguson or Bézier curves. At the same time, not only the basic points, but also the tangents to the elastic line of the real physical spline should be given as boundary conditions. In such a case it has been shown that standard cubic Bézier curves have a significant computational advantage over Ferguson ones. Examples for modelling of physical splines with free and clamped ends have been considered. For a free spline an error of parametric approximation is equal to 0.4 %. For a spline with clamped ends an error of less than 1.5 % has been obtained. The calculations have been performed with SMath Studio computer graphics system.

On the determination of a velocity field for a perfectly plastic flow: The case of the general plane problem

2001 ◽  
Vol 46 (8) ◽  
pp. 596-601 ◽  
Author(s):  
D. D. Ivlev ◽  
L. A. Maksimova ◽  
R. I. Nepershin
Keyword(s):  
Velocity Field ◽  
Plastic Flow ◽  
Plane Problem ◽  
Perfectly Plastic ◽  
General Plane
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