Globally subanalytic CMC surfaces in ℝ3 with singularities

2020 ◽  
pp. 1-18
Author(s):  
José Edson Sampaio
Keyword(s):  
Circular Cylinder ◽  
Suitable Condition ◽  
Finite Union ◽  
Circular Cylinders ◽  
Round Sphere ◽  
Isolated Singularities ◽  
Cmc Surfaces ◽  
Locally Lipschitz ◽  
Recent Classification

Abstract In this paper we present a classification of a class of globally subanalytic CMC surfaces in ℝ3 that generalizes the recent classification made by Barbosa and do Carmo in 2016. We show that a globally subanalytic CMC surface in ℝ3 with isolated singularities and a suitable condition of local connectedness is a plane or a finite union of round spheres and right circular cylinders touching at the singularities. As a consequence, we obtain that a globally subanalytic CMC surface in ℝ3 that is a topological manifold does not have isolated singularities. It is also proved that a connected closed globally subanalytic CMC surface in ℝ3 with isolated singularities which is locally Lipschitz normally embedded needs to be a plane or a round sphere or a right circular cylinder. A result in the case of non-isolated singularities is also presented. It also presented some results on regularity of semialgebraic sets and, in particular, it proved a real version of Mumford's Theorem on regularity of normal complex analytic surfaces and a result about C1 regularity of minimal varieties.

Steady approach of unsteady low-Reynolds-number flow past two rotating circular cylinders

2013 ◽  
Vol 736 ◽  
pp. 414-443 ◽  
Author(s):  
Y. Ueda ◽  
T. Kida ◽  
M. Iguchi
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Stokes Equations ◽  
Low Reynolds Number ◽  
Vortex Method ◽  
The Self ◽  
Circular Cylinders ◽  
Far Field ◽  
Flow Past ◽  
Low Reynolds

AbstractThe long-time viscous flow about two identical rotating circular cylinders in a side-by-side arrangement is investigated using an adaptive numerical scheme based on the vortex method. The Stokes solution of the steady flow about the two-cylinder cluster produces a uniform stream in the far field, which is the so-called Jeffery’s paradox. The present work first addresses the validation of the vortex method for a low-Reynolds-number computation. The unsteady flow past an abruptly started purely rotating circular cylinder is therefore computed and compared with an exact solution to the Navier–Stokes equations. The steady state is then found to be obtained for $t\gg 1$ with ${\mathit{Re}}_{\omega } {r}^{2} \ll t$, where the characteristic length and velocity are respectively normalized with the radius ${a}_{1} $ of the circular cylinder and the circumferential velocity ${\Omega }_{1} {a}_{1} $. Then, the influence of the Reynolds number ${\mathit{Re}}_{\omega } = { a}_{1}^{2} {\Omega }_{1} / \nu $ about the two-cylinder cluster is investigated in the range $0. 125\leqslant {\mathit{Re}}_{\omega } \leqslant 40$. The convection influence forms a pair of circulations (called self-induced closed streamlines) ahead of the cylinders to alter the symmetry of the streamline whereas the low-Reynolds-number computation (${\mathit{Re}}_{\omega } = 0. 125$) reaches the steady regime in a proper inner domain. The self-induced closed streamline is formed at far field due to the boundary condition being zero at infinity. When the two-cylinder cluster is immersed in a uniform flow, which is equivalent to Jeffery’s solution, the streamline behaves like excellent Jeffery’s flow at ${\mathit{Re}}_{\omega } = 1. 25$ (although the drag force is almost zero). On the other hand, the influence of the gap spacing between the cylinders is also investigated and it is shown that there are two kinds of flow regimes including Jeffery’s flow. At a proper distance from the cylinders, the self-induced far-field velocity, which is almost equivalent to Jeffery’s solution, is successfully observed in a two-cylinder arrangement.

Elasticity Solution for a Radially Nonhomogeneous Hollow Circular Cylinder

1999 ◽  
Vol 66 (3) ◽  
pp. 598-606 ◽  
Author(s):  
Xiangzhou Zhang ◽  
Norio Hasebe
Keyword(s):  
Circular Cylinder ◽  
Continuous Functions ◽  
Variable Coefficients ◽  
Circular Cylinders ◽  
Explicit Solutions ◽  
Elasticity Solution ◽  
First Order ◽  
Hollow Circular Cylinder ◽  
Homogeneous Elasticity ◽  
Ordinary Differential Equation Systems

An exact elasticity solution is developed for a radially nonhomogeneous hollow circular cylinder of exponential Young’s modulus and constant Poisson’s ratio. In the solution, the cylinder is first approximated by a piecewise homogeneous one, of the same overall dimension and composed of perfectly bonded constituent homogeneous hollow circular cylinders. For each of the constituent cylinders, the solution can be obtained from the theory of homogeneous elasticity in terms of several constants. In the limit case when the number of the constituent cylinders becomes unboundedly large and their thickness tends to infinitesimally small, the piecewise homogeneous hollow circular cylinder reverts to the original nonhomogeneous one, and the constants contained in the solutions for the constituent cylinders turn into continuous functions. These functions, governed by some systems of first-order ordinary differential equations with variable coefficients, stand for the exact elasticity solution of the nonhomogeneous cylinder. Rigorous and explicit solutions are worked out for the ordinary differential equation systems, and used to generate a number of numerical results. It is indicated in the discussion that the developed method can also be applied to hollow circular cylinders with arbitrary, continuous radial nonhomogeneity.

scholarly journals A57 THE USE AND INTERPRETATION OF HLA-DQ2/DQ8 GENOTYPING BY PEDIATRIC GASTROENTEROLOGISTS

2021 ◽  
Vol 4 (Supplement_1) ◽  
pp. 14-15
Author(s):  
B Moreau ◽  
E Robidoux
Keyword(s):  
Risk Groups ◽  
Risk Classification ◽  
Low Risk ◽  
Risk Alleles ◽  
Seronegative Patient ◽  
Espghan Guidelines ◽  
Recent Classification ◽  
American Society ◽  
Hla Dq2

Abstract Background A recent classification of high and low risk alleles associated with celiac disease (CD) shows that the presence of a single allele (DQA1*05 or DQB1*02; coding together for HLA-DQ2), without a positive genotype (HLA-DQ2 and or HLA-DQ8), represents a risk of developing the disease. Aims The aim of this study is to evaluate the use and interpretation of the HLA-DQ2/DQ8 genotyping by pediatric gastroenterologists, as there is no study on the matter and the latest guidelines do not address this risk classification. Methods A web-based survey was sent by email to all NASPGHAN (North American society of pediatric gastroenterolgy, hepatology and nutrition) members. Results Results 294 pediatric gastroenterologists sent a complete survey. 86,1% use the HLA-DQ2/DQ8 genotyping according mainly to the NASPGHAN and ESPGHAN guidelines. The main indications considered were to exclude CD in a patient on a gluten-free diet with a resolution of his symptoms and in a seronegative patient with equivocal biopsies. A minority would consider the genotyping for screening high risk groups or for making a diagnosis in children with high specific CD antibodies and strong clinical suspicion without performing biopsies, as suggested by the ESPGHAN guidelines. The alleles associated with CD are not well known, but 76,7% the participants are aware of the risk classification. While only 62,8% have access to the complete genotype, 47,8% consider it useful. Nevertheless, 82,6% would still want to know the presence of a low risk allele. Conclusions The risk classification of alleles related to CD warrants a modification of the genotyping result with access to the alleles and an adaptation of the guidelines. Funding Agencies None

scholarly journals Neuropathology of Temporal Lobe Epilepsy

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Fahd Al Sufiani ◽  
Lee Cyn Ang
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Temporal Lobe ◽  
Focal Cortical Dysplasia ◽  
Cortical Dysplasia ◽  
Wide Range ◽  
Pathologic Findings ◽  
Pathologic Lesions ◽  
Recent Classification ◽  
Associated Tumors

Pathologic findings in surgical resections from patients with temporal lobe epilepsy include a wide range of diagnostic possibilities that can be categorized into different groups on the basis of etiology. This paper outlines the various pathologic entities described in temporal lobe epilepsy, including some newly recognized epilepsy-associated tumors, and briefly touch on the recent classification of focal cortical dysplasia. This classification takes into account coexistent pathologic lesions in focal cortical dysplasia.

A Model for High-Reynolds-Number Flow Past Rough-Walled Circular Cylinders

1977 ◽  
Vol 99 (3) ◽  
pp. 486-493 ◽  
Author(s):  
O. Gu¨ven ◽  
V. C. Patel ◽  
C. Farell
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Circular Cylinder ◽  
Turbulent Boundary Layer ◽  
Pressure Coefficient ◽  
Empirical Relation ◽  
Reynolds Numbers ◽  
Boundary Layer Separation ◽  
Circular Cylinders ◽  
Mean Flow

A simple analytical model for two-dimensional mean flow at very large Reynolds numbers around a circular cylinder with distributed roughness is presented and the results of the theory are compared with experiment. The theory uses the wake-source potential-flow model of Parkinson and Jandali together with an extension to the case of rough-walled circular cylinders of the Stratford-Townsend theory for turbulent boundary-layer separation. In addition, a semi-empirical relation between the base-pressure coefficient and the location of separation is used. Calculation of the boundary-layer development, needed as part of the theory, is accomplished using an integral method, taking into account the influence of surface roughness on the laminar boundary layer and transition as well as on the turbulent boundary layer. Good agreement with experiment is shown by the results of the theory. The significant effects of surface roughness on the mean-pressure distribution on a circular cylinder at large Reynolds numbers and the physical mechanisms giving rise to these effects are demonstrated by the model.

A Global Phylogenomic Study of the Thelypteridaceae

2021 ◽  
Vol 46 (4) ◽  
pp. 891-915
Author(s):  
Susan Fawcett ◽  
Alan R. Smith ◽  
Michael Sundue ◽  
J. Gordon Burleigh ◽  
Emily B. Sessa ◽  
...  
Keyword(s):  
Morphological Characters ◽  
Morphological Evidence ◽  
Phylogenetic Studies ◽  
The Family ◽  
Likelihood Analysis ◽  
Single Genus ◽  
The Subject ◽  
Recent Classification ◽  
Phylogenomic Study

Abstract— The generic classification of the Thelypteridaceae has been the subject of much controversy. Proposed taxonomic systems have varied from recognizing the approximately 1200 species in the family within the single genus Thelypteris, to systems favoring upwards of 30 genera. Insights on intrafamilial relationships, especially for neotropical taxa, have been gained from recent phylogenetic studies; however, in the most recent classification, 10 of 30 recognized genera are either non-monophyletic or untested. We sequenced 407 nuclear loci for 621 samples, representing all recognized genera and approximately half the known species diversity. These were analyzed using both maximum likelihood analysis of a concatenated matrix and multi-species coalescent methods. Our phylogenomic results, informed by recently published morphological evidence, provide the foundation for a generic classification which recircumscribed 14 genera and recognized seven new genera. The 37 monophyletic genera sampled demonstrate greater geographic coherence than previous taxonomic concepts suggested. Additionally, our results demonstrate that certain morphological characters, such as frond division, are evolutionarily labile and are thus inadequate for defining genera.

scholarly journals The Investigation of Mutual Interference Vortex Flow around Two Circular Cylinders by Flow Visualization and Pressure Measurement

2019 ◽  
Vol 291 ◽  
pp. 02001
Author(s):  
Yoshifumi Yokoi ◽  
Rut Vitkovičová
Keyword(s):  
Circular Cylinder ◽  
Pressure Measurement ◽  
Pressure Coefficient ◽  
Visual Observation ◽  
Mutual Interference ◽  
Circular Cylinders ◽  
Cylinder Surface ◽  
Visualization Experiment ◽  
Flow Apparatus ◽  
Measurement Experiment

In order to understand the aspect of the mutual interference flow from two circular cylinders, the visual observation experiment and the pressure measurement experiment were performed by use a water flow apparatus. Two circular cylinders with a diameter of D=10mm were used, and they have been arranged at staggered or tandem. The flow velocity was U=0.25m/s (Re=UD/í, í is kinematic viscosity of fluid). The dye oozing streak method was used in the visualization experiment. In the pressure measurement experiment, the pressure on the surface of a circular cylinder was detected by the single tube manometer, and measurement was performed by image processing using a computer. As a result, distribution of the circular cylinder surface pressure coefficient CP corresponding to the flow pattern and it in each circular cylinder arrangement was obtained. The drag coefficient CD was calculated from the pressure coefficient CP, and change of the resistance in each arrangement was found.

SCALING THEORY AND THE CLASSIFICATION OF PHASE TRANSITIONS

1992 ◽  
Vol 06 (13) ◽  
pp. 773-784 ◽  
Author(s):  
R. HILFER
Keyword(s):  
Phase Transitions ◽  
Statistical Physics ◽  
Thermodynamic Description ◽  
Classification Theory ◽  
Nonequilibrium Phase Transitions ◽  
Critical Limit ◽  
Scaling Hypothesis ◽  
Recent Classification ◽  
Thermodynamics And Statistical Mechanics

The recent classification theory for phase transitions (R. Hilfer, Physica Scripta 44, 321 (1991)) and its relation with the foundations of statistical physics is reviewed. First it is outlined how Ehrenfests classification scheme can be generalized into a general thermodynamic classification theory for phase transitions. The classification theory implies scaling and multiscaling thereby eliminating the need to postulate the scaling hypothesis as a fourth law of thermodynamics. The new classification has also led to the discovery and distinction of nonequilibrium transitions within equilibrium statistical physics. Nonequilibrium phase transitions are distinguished from equilibrium transitions by orders less than unity and by the fact that equilibrium thermodynamics and statistical mechanics become inapplicable at the critical point. The latter fact requires a change in the Gibbs assumption underlying the canonical and grandcanonical ensembles in order to recover the thermodynamic description in the critical limit.

Three-dimensional wakes behind cylinders of square and circular cross-section: early and long-time dynamics

2019 ◽  
Vol 870 ◽  
pp. 419-432 ◽  
Author(s):  
G. Agbaglah ◽  
C. Mavriplis
Keyword(s):  
Circular Cylinder ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Early Time ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Square Cylinder ◽  
Saturation Regime ◽  
Time Dynamics ◽  
Significant Difference

The flow in the near wake of a square cylinder at Reynolds numbers of 205 and 225, corresponding to three-dimensional wake instability modes $A$ and $B$, respectively, and that of the square’s circumscribed circular cylinder are examined by using three-dimensional Navier–Stokes numerical simulations. At small times, prior to the streamwise vortex shedding, a self-similar velocity is observed in the wake and no significant difference is observed in the dynamics of the flows past the square and the circular cylinders. The exponential growth of the three-dimensional instability reaches a saturation regime during this early time for the considered Reynolds numbers. Vortical structures in the wake at long times and shedding frequencies are very close for the square and the circular cylinders. The flow separation on the forward top and bottom corners of the square cylinder have the effect of increasing its effective width, making it comparable with the diameter of the circumscribed circular cylinder. Thus, Floquet multipliers and modes of the associated three-dimensional instabilities are shown to be very close for the two cylinders when using the circumscribed circular cylinder as the basis for a characteristic length scale. Most importantly, the wavenumber with the maximum growth rate, for modes $A$ and $B$, is approximately identical for the two cylinders.

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