scholarly journals Two parameters for three-dimensional wetting transitions

1997 ◽  
Vol 37 (3) ◽  
pp. 207-212 ◽  
Author(s):  
P. S Swain ◽  
A. O Parry
Keyword(s):  
Three Dimensional ◽  
Wetting Transitions ◽  
Two Parameters

Applications of Scanning Microscopy in Biomedical Research

1968 ◽  
Vol 26 ◽  
pp. 354-355
Author(s):  
T. L. Hayes
Keyword(s):  
Information Content ◽  
Biomedical Research ◽  
Biomedical Applications ◽  
Three Dimensional ◽  
Dental Enamel ◽  
Resolving Power ◽  
Whole Mount ◽  
Two Parameters ◽  
Content Information ◽  
Sectioned Tissue

Biomedical applications of the scanning electron microscope (SEM) have increased in number quite rapidly over the last several years. Studies have been made of cells, whole mount tissue, sectioned tissue, particles, human chromosomes, microorganisms, dental enamel and skeletal material. Many of the advantages of using this instrument for such investigations come from its ability to produce images that are high in information content. Information about the chemical make-up of the specimen, its electrical properties and its three dimensional architecture all may be represented in such images. Since the biological system is distinctive in its chemistry and often spatially scaled to the resolving power of the SEM, these images are particularly useful in biomedical research.In any form of microscopy there are two parameters that together determine the usefulness of the image. One parameter is the size of the volume being studied or resolving power of the instrument and the other is the amount of information about this volume that is displayed in the image. Both parameters are important in describing the performance of a microscope. The light microscope image, for example, is rich in information content (chemical, spatial, living specimen, etc.) but is very limited in resolving power.

scholarly journals Coupled Hamiltonians and three-dimensional short-range wetting transitions

1998 ◽  
Vol 250 (1-4) ◽  
pp. 167-230 ◽  
Author(s):  
A.O. Parry ◽  
P.S. Swain
Keyword(s):  
Short Range ◽  
Three Dimensional ◽  
Wetting Transitions

Chaotic Mixing in Time-Periodic 3-D Flows

2002 ◽  
Author(s):  
A. J. S. Rodrigo ◽  
J. P. B. Mota ◽  
E. Saatdjian
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Modulation Frequency ◽  
Outer Cylinder ◽  
Three Dimensional ◽  
Axial Flow ◽  
Cross Sectional ◽  
The Cross ◽  
Two Parameters ◽  
Time Periodic

Mixing in a special class of three-dimensional, non-inertial time-periodic flows is studied quantitatively. In the type of flow considered here, the cross-sectional velocity components are independent of the axial flow which is assumed to be fully developed. Using the eccentric helical annular mixer as a prototype, the time-periodic flow field is induced by adding a sinusoidal component to the rotation speed of the inner cylinder. For a given 3-D mixer geometry, the degree of mixing achieved is a function of two parameters that measure the strength of the cross-sectional stirring protocol relative to the mean residence time of the fluid in the mixer: the average number of turns of the outer cylinder, and the average number of modulation periods. We find that for a given mixer geometry and mean residence time, there is an optimum modulation frequency for which the standard deviation of the temperature field at the exit is a minimum.

scholarly journals Rheology of ice at the bed of Engabreen, Norway

2000 ◽  
Vol 46 (155) ◽  
pp. 611-621 ◽  
Author(s):  
Denis Cohen
Keyword(s):  
Three Dimensional ◽  
Field Measurements ◽  
Element Model ◽  
Basal Ice ◽  
Dimensional Finite Element ◽  
Ice Field ◽  
Frictional Forces ◽  
Two Parameters ◽  
Three Dimensional Finite Element ◽  
Sediment Layers

AbstractA three-dimensional finite-element model is used to analyze field data collected as dirty basal ice flowed past an instrumented obstacle at the bed of Engabreen, a temperate glacier in northern Norway The ice is modeled as an incompressible power-law fluid, with viscosity , where ΠD is the second invariant of the stretching tensor, and B and n are two parameters. Using measurements obtained in 1996 and 1997, two values of B are obtained, one using the measured normal stress difference across the obstacle, and the other using the measured bed-parallel force over the instrument. These two values are not equal, probably owing to small frictional forces at the bed unaccounted for in the numerical model. Hence, B ranges between 1.9 × 107 and 3.2 × 107 Pa s1/3 in 1996, and between 2.2 × 107 and 4.1 × 107 Pa s1/3 in 1997. These values are smaller than measured elsewhere for clean glacier or laboratory ice. Field measurements of water content, fabric and texture of the basal ice suggest that unbound water between thin sediment layers and lamellae of clean ice may act as a lubricant and significantly weaken the ice. Near-isotropic fabrics indicate that preferred fabric orientation does not enhance the deformation.

Anatomical Study of the Radius and Center of Curvature of the Distal Femoral Condyle

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Jürgen Kosel ◽  
Ioanna Giouroudi ◽  
Cornie Scheffer ◽  
Edwin Dillon ◽  
Pieter Erasmus
Keyword(s):  
Laser Scanning ◽  
Femoral Condyle ◽  
Three Dimensional ◽  
Anatomical Study ◽  
Surface Curvature ◽  
Cartilage Tissue ◽  
B Splines ◽  
Flexion Extension ◽  
Total Knee ◽  
Two Parameters

In this anatomical study, the anteroposterior curvature of the surface of 16 cadaveric distal femurs was examined in terms of radii and center point. Those two parameters attract high interest due to their significance for total knee arthroplasty. Basically, two different conclusions have been drawn in foregoing studies: (1) The curvature shows a constant radius and (2) the curvature shows a variable radius. The investigations were based on a new method combining three-dimensional laser-scanning and planar geometrical analyses. This method is aimed at providing high accuracy and high local resolution. The high-precision laser scanning enables the exact reproduction of the distal femurs—including their cartilage tissue—as a three-dimensional computer model. The surface curvature was investigated on intersection planes that were oriented perpendicularly to the surgical epicondylar line. Three planes were placed at the central part of each condyle. The intersection of either plane with the femur model was approximated with the help of a b-spline, yielding three b-splines on each condyle. The radii and center points of the circles, approximating the local curvature of the b-splines, were then evaluated. The results from all three b-splines were averaged in order to increase the reliability of the method. The results show the variation in the surface curvatures of the investigated samples of condyles. These variations are expressed in the pattern of the center points and the radii of the curvatures. The standard deviations of the radii for a 90 deg arc on the posterior condyle range from 0.6 mm up to 5.1 mm, with an average of 2.4 mm laterally and 2.2 mm medially. No correlation was found between the curvature of the lateral and medial condyles. Within the range of the investigated 16 samples, the conclusion can be drawn that the condyle surface curvature is not constant and different for all specimens when viewed along the surgical epicondylar axis. For the portion of the condylar surface that articulates with the tibia during knee flexion-extension, the determined center points approximate the location of the centers of rotation. The results suggest that the concept of a fixed flexion-extension axis is not applicable for every specimen.

The Euler number of certain primitive Calabi–Yau threefolds

2000 ◽  
Vol 128 (1) ◽  
pp. 79-86
Author(s):  
MEI-CHU CHANG ◽  
HOIL KIM
Keyword(s):  
Moduli Space ◽  
Moduli Spaces ◽  
Three Dimensional ◽  
Building Blocks ◽  
K3 Surfaces ◽  
Physical Models ◽  
Ample Divisor ◽  
K3 Surface ◽  
Superstring Theory ◽  
Two Parameters

Recently Calabi–Yau threefolds have been studied intensively by physicists and mathematicians. They are used as physical models of superstring theory [Y] and they are one of the building blocks in the classification of complex threefolds [KMM]. These are three dimensional analogues of K3 surfaces. However, there is a fundamental difference as is to be expected. For K3 surfaces, the moduli space N of K3 surfaces is irreducible of dimension 20, inside which a countable number of families Ng with g [ges ] 2 of algebraic K3 surfaces of dimension 19 lie as a dense subset. More explicitly, an element in Ng is (S, H), where S is a K3 surface and H is a primitive ample divisor on S with H2 = 2g − 2. For a generic (S, H), Pic (S) is generated by H, so that the rank of the Picard group of S is 1. A generic surface S in N is not algebraic and it has Pic (S) = 0, but dim N = h1(S, TS) = 20 [BPV]. It is quite an interesting problem whether or not the moduli space M of all Calabi–Yau threefolds is irreducible in some sense [R]. A Calabi–Yau threefold is algebraic if and only if it is Kaehler, while every non-algebraic K3 surface is still Kaehler. Inspired by the K3 case, we define Mh,d to be {(X, H)[mid ]H3 = h, c2(X) · H = d}, where H is a primitive ample divisor on a smooth Calabi–Yau threefold X. There are two parameters h, d for algebraic Calabi–Yau threefolds, while there is only one parameter g for algebraic K3 surfaces. (Note that c2(S) = 24 for every K3 surface.) We know that Ng is of dimension 19 for every g and is irreducible but we do not know the dimension of Mh,d and whether or not Mh,d is irreducible. In fact, the dimension of Mh,d = h1(X, TX), where (X, H) ∈ Mh,d. Furthermore, it is well known that χ(X) = 2 (rank of Pic (X) − h1(X, TX)), where χ(X) is the topological Euler characteristic of X. Calabi–Yau threefolds with Picard rank one are primitive [G] and play an important role in the moduli spaces of all Calabi–Yau threefolds. In this paper we give a bound on c3 of Calabi–Yau threefolds with Picard rank 1.

scholarly journals Three-dimensional instability of axisymmetric flow in a rotating lid–cylinder enclosure

2001 ◽  
Vol 438 ◽  
pp. 363-377 ◽  
Author(s):  
A. Yu. GELFGAT ◽  
P. Z. BAR-YOSEPH ◽  
A. SOLAN
Keyword(s):  
Stability Problem ◽  
Axisymmetric Flow ◽  
Three Dimensional ◽  
Phase Velocities ◽  
Discrete Values ◽  
The Stability ◽  
Two Parameters ◽  
Dimensional Instability ◽  
Axisymmetric Instability ◽  
Axisymmetric Perturbations

The axisymmetry-breaking three-dimensional instability of the axisymmetric flow between a rotating lid and a stationary cylinder is analysed. The flow is governed by two parameters – the Reynolds number Re and the aspect ratio γ (=height/radius). Published experimental results indicate that in different ranges of γ axisymmetric or non-axisymmetric instabilities can be observed. Previous analyses considered only axisymmetric instability. The present analysis is devoted to the linear stability of the basic axisymmetric flow with respect to the non-axisymmetric perturbations. After the linearization the stability problem separates into a family of quasi-axisymmetric subproblems for discrete values of the azimuthal wavenumber k. The computations are done using the global Galerkin method. The stability analysis is carried out at various densely distributed values of γ in the range 1 < γ < 3.5. It is shown that the axisymmetric perturbations are dominant in the range 1.63 < γ < 2.76. Outside this range, for γ < 1.63 and for γ > 2.76, the instability is three-dimensional and sets in with k = 2 and k = 3 or 4, respectively. The azimuthal periodicity, patterns, characteristic frequencies and phase velocities of the dominant perturbations are discussed.

scholarly journals Layout Effect of Two Autonomous Underwater Vehicles on the Hydrodynamics Performances

2020 ◽  
Vol 19 ◽  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Autonomous Underwater Vehicles ◽  
Three Dimensional ◽  
Pressure Change ◽  
Underwater Vehicles ◽  
Optimal Layout ◽  
Minimum Drag ◽  
Computational Fluid Dynamics Cfd ◽  
Two Parameters

Three-dimensional computational fluid dynamics (CFD) is used for the design optimization of the layout of an autonomous underwater vehicles (AUV) containing three torpedo-shaped hulls. The AUV layout is defined by two parameters a and b present the stance following YY and XX respectively. several simulations are carried on the AUV with different positions of the torpedo in order to define the optimal layout which designates the minimum drag. the numerical results approve that the variation in the drag coefficient of the AUV is the to the interaction of the flow rate and the pressure change between the both hulls. in addition, an optimal layout for the minimum AUV drag with two torpedoes is found which provides a drag reduce of about 11.4% lower than a single UV with a single torpedo.

scholarly journals 3D microstructure and critical current properties of ultra-fine-grain Ba(Fe,Co)2As2 bulk superconductors

2021 ◽  
Author(s):  
Yusuke Shimada ◽  
Shinnosuke Tokuta ◽  
Akinori Yamanaka ◽  
Akiyasu Yamamoto ◽  
Toyohiko. J Konno
Keyword(s):  
Grain Boundaries ◽  
Critical Current ◽  
Weak Link ◽  
Three Dimensional ◽  
High Energy ◽  
Dimensional Structure ◽  
Polycrystalline Materials ◽  
Fine Grain ◽  
Pore Length ◽  
Two Parameters

Abstract In iron-based superconductors, randomly oriented grain boundaries have a strong influence on the transport properties via intrinsic weak-link and flux pinning mechanisms. Herein we report the critical current density (Jc) and the three-dimensional microstructure of polycrystalline bulk Co-doped Ba122 superconductors, with highly dense grain boundaries (grain size smaller than 50 nm), produced by high-energy milling. Three-dimensional electron microscopy revealed that the anomalous growth of secondary particles (aggregation) and the inter-aggregation structures were significantly different in the samples with finer grains, which may have extrinsically limited Jc. These important microstructural features were quantified as two parameters—local thickness and total pore length—by reconstructing the three-dimensional structure of the superconducting phase using the adaptive thresholding method. The results obtained in this study suggest that understanding and controlling the microstructural formation process by sintering are instrumental for improving the Jc properties of 122 polycrystalline materials consisting of ultrafine grains.

scholarly journals Emergent Collective Locomotion in an Active Polymer Model of Entangled Worm Blobs

2021 ◽  
Vol 9 ◽  
Author(s):  
Chantal Nguyen ◽  
Yasemin Ozkan-Aydin ◽  
Harry Tuazon ◽  
Daniel. I. Goldman ◽  
M. Saad Bhamla ◽  
...  
Keyword(s):  
Collective Behavior ◽  
Three Dimensional ◽  
Lumbriculus Variegatus ◽  
Polymer Model ◽  
Active Motion ◽  
Arthropod Species ◽  
Dry Conditions ◽  
Two Parameters ◽  
Collective Survival ◽  
Collective Locomotion

Numerous worm and arthropod species form physically-connected aggregations in which interactions among individuals give rise to emergent macroscale dynamics and functionalities that enhance collective survival. In particular, some aquatic worms such as the California blackworm (Lumbriculus variegatus) entangle their bodies into dense blobs to shield themselves against external stressors and preserve moisture in dry conditions. Motivated by recent experiments revealing emergent locomotion in blackworm blobs, we investigate the collective worm dynamics by modeling each worm as a self-propelled Brownian polymer. Though our model is two-dimensional, compared to real three-dimensional worm blobs, we demonstrate how a simulated blob can collectively traverse temperature gradients via the coupling between the active motion and the environment. By performing a systematic parameter sweep over the strength of attractive forces between worms, and the magnitude of their directed self-propulsion, we obtain a rich phase diagram which reveals that effective collective locomotion emerges as a result of finely balancing a tradeoff between these two parameters. Our model brings the physics of active filaments into a new meso- and macroscale context and invites further theoretical investigation into the collective behavior of long, slender, semi-flexible organisms.

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