scholarly journals Comparison of different methods for extracting bone cross-sectional geometric properties from CT images

2013 ◽  
Vol 10 (2) ◽  
pp. 247-260 ◽  
Author(s):  
Sinisa Ilic ◽  
Sladjan Timotijevic ◽  
Dejan Lazovic ◽  
Petar Spalevic ◽  
Alempije Veljovic
Keyword(s):  
Cross Sections ◽  
Good Accuracy ◽  
Threshold Level ◽  
Ct Images ◽  
Sufficient Accuracy ◽  
The Body ◽  
Cross Sectional ◽  
Geometric Properties ◽  
Moments Of Inertia ◽  
External Forces

Analysis of the geometric properties of bone cross-sections is often used to determine skeletal performance and the ability of the body to resist different external forces. This analysis is dependent on obtaining adequate bone cross-sectional images. CT images can be used for this purpose by performing some pre-processing of images in order to achieve sufficient accuracy. In this paper we have used experiments to show that relatively good accuracy of bone cross sectional areas and moments of inertia can be achieved by simple threshold level filtering of CT images.

Gender determination of caucasoid hair using image analysis

1993 ◽  
Vol 51 ◽  
pp. 216-217
Author(s):  
T.B. Ball ◽  
W.M. Hess
Keyword(s):  
Image Analysis ◽  
Cross Sections ◽  
Scalp Hair ◽  
The Body ◽  
Equivalent Diameter ◽  
Cross Sectional ◽  
Hair Samples ◽  
Length Width ◽  
Morphological Differences

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.

Long bone cross-sectional geometry

2020 ◽  
pp. 307-320
Author(s):  
Christopher B. Ruff ◽  
Ryan W. Higgins ◽  
Kristian J. Carlson
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Lateral Displacement ◽  
Center Of Mass ◽  
Gait Pattern ◽  
Locomotor Behavior ◽  
The Body ◽  
Long Bone ◽  
Cross Sectional ◽  
Body Center

Long bone diaphyseal cross-sectional geometries reflect the mechanical properties of the bones, and can be used to aid in inferences of locomotor behavior in extinct hominins. This chapter considers all available long bone diaphyseal and femoral neck cross-sections of specimens from Sterkfontein Member 4, and presents comparisons of these section properties and other cross-sectional dimensions with those of other early hominins as well as modern samples. The cross-sectional geometry of the Sterkfontein Member 4 long bone specimens suggests some similarities to, but also interesting differences in, mechanical loading of these elements relative to modern humans. The less asymmetric cortical bone distribution in the Sterkfontein femoral necks is consistent with other evidence above indicating an altered gait pattern involving lateral displacement of the body center of mass over the stance limb. The relatively very strong upper limb of StW 431 implies that arboreal behavior formed a significant component of its locomotor repertoire. Bipedal gait may have been less efficient and arboreal climbing more prevalent in the Sterkfontein hominins.

scholarly journals Three-dimensional extension of Lighthill's large-amplitude elongated-body theory of fish locomotion

2011 ◽  
Vol 674 ◽  
pp. 196-226 ◽  
Author(s):  
FABIEN CANDELIER ◽  
FREDERIC BOYER ◽  
ALBAN LEROYER
Keyword(s):  
Cross Sections ◽  
Velocity Potential ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Neumann Boundary ◽  
The Body ◽  
Navier Stokes ◽  
Cross Sectional ◽  
Curvature Effects ◽  
The Cross

The goal of this paper is to derive expressions for the pressure forces and moments acting on an elongated body swimming in a quiescent fluid. The body is modelled as an inextensible and unshearable (Kirchhoff) beam, whose cross-sections are elliptic, undergoing prescribed deformations, consisting of yaw and pitch bending. The surrounding fluid is assumed to be inviscid, and irrotational everywhere, except in a thin vortical wake. The Laplace equation and the corresponding Neumann boundary conditions are first written in terms of the body coordinates of a beam treating the body as a fixed surface. They are then simplified according to the slenderness of the body and its kinematics. Because the equations are linear, the velocity potential is sought as a sum of two terms which are linked respectively to the axial movements of the beam and to its lateral movements. The lateral component of the velocity potential is decomposed further into two sub-components, in order to exhibit explicitly the role of the two-dimensional potential flow produced by the lateral motion of the cross-section, and the role played by the curvature effects of the beam on the cross-sectional flow. The pressure, which is given by Bernoulli's equation, is integrated along the body surface, and the expressions for the resultant and the moment are derived analytically. Thereafter, the validity of the force and moment obtained analytically is checked by comparisons with Navier–Stokes simulations (using Reynolds-averaged Navier–Stokes equations), and relatively good agreements are observed.

Supersonic Flow Past Slender Bodies With Discontinuous Profile Slope

1955 ◽  
Vol 6 (2) ◽  
pp. 114-124 ◽  
Author(s):  
L. E. Fraenkel ◽  
H. Portnoy
Keyword(s):  
Internal Flow ◽  
Leading Edge ◽  
Rate Of Change ◽  
The Body ◽  
Cross Sectional ◽  
Slender Body Theory ◽  
Bodies Of Revolution ◽  
Slender Bodies ◽  
External Forces ◽  
Sectional Shape

SummaryWard’s slender-body theory is extended to derive first approximations to the external forces on slender bodies of general cross section with discontinuous profile slope. Two classes of body are considered: bodies whose profile (typified by the local radius) is continuous between the nose and base, and certain bodies whose profile is discontinuous, such as bodies with annular or side air intakes and wing-bodies on which the wing has an unswept leading edge. (Where air intakes are concerned, it is assumed that they are sharp-edged and that there is no “ spillage ” of the internal flow).The following conclusions apply to the former class of bodies. The variation of drag with Mach number is found to depend only on the discontinuities in the longitudinal rate of change of the cross-sectional area, and is thus independent of cross-sectional shape. The drag itself is unchanged if the direction of the flow is reversed. The expressions for lift and moment assume the same forms as for smooth pointed bodies, the lift depending only on conditions at the base of the body.The general theory is applied to winged bodies of revolution with an unswept wing leading edge: the results bear a marked resemblance to those obtained by Ward. The results for wings alone are seen to be applicable, with one modification, to subsonic as well as to supersonic speeds.

Computation of Geometric Properties of Cross Sections With Holes and/or Inserts Based on Scanned Binary Data

1998 ◽  
Author(s):  
Y. C. Pao ◽  
E. L. Ritman
Keyword(s):  
Porous Materials ◽  
Cross Sections ◽  
Binary Data ◽  
Computational Procedure ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Moments Of Inertia ◽  
Interactive Operation ◽  
Direct Use

Abstract Formulas have been derived for computation of the cross sectional area, location of the centroid, and moments of inertia making direct use of the binary-data which are to be collected from computer-tomographical scanning of porous materials. Bone data are applied to demonstrate the developed computational procedure and interactive operation of QuickBASIC programs.

Cross-Sectional Geometries

2017 ◽  
Author(s):  
Elizabeth Weiss
Keyword(s):  
Cross Sections ◽  
Animal Studies ◽  
Long Bones ◽  
Cross Sectional ◽  
Moments Of Inertia ◽  
Tennis Players ◽  
Common Activity ◽  
Bending Stresses

Cross-sectional geometries are examined in chapter 2; long bones can be envisioned as beams that experience biomechanical stresses, such as bending, torsion, and compressive forces, to which they remodel to prevent from breaking. Using cross-sectional measures, such as moments of inertia that represent bone’s ability to resist bending and torsional stresses, researchers can determine the direction of stresses and, therefore, the activities that cause these stresses. One common activity examined is mobility, which leads to anteroposteriorly oriented femoral cross-sections due to bending stresses. Asymmetry studies on tennis players have helped confirm that cross-sectional geometries change in response to activities. Yet animal studies, such as those on baboons, have been key in helping bioarchaeologists understand the non-activity pressures, such as age, sex, and genes, on cross-sectional geometries.

scholarly journals Cross-Sectional Performance of Hollow Square Prisms with Rounded Edges

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 996
Author(s):  
Hiroyuki Shima ◽  
Nao Furukawa ◽  
Yuhei Kameyama ◽  
Akio Inoue ◽  
Motohiro Sato
Keyword(s):  
Mechanical Properties ◽  
Mathematical Model ◽  
Cross Sections ◽  
Cross Sectional ◽  
Hollow Section ◽  
Buckling Resistance ◽  
The Cross ◽  
The Stability ◽  
External Forces ◽  
Sectional Shape

Hollow-section columns are one of the mechanically superior structures with high buckling resistance and high bending stiffness. The mechanical properties of the column are strongly influenced by the cross-sectional shape. Therefore, when evaluating the stability of a column against external forces, it is necessary to reproduce the cross-sectional shape accurately. In this study, we propose a mathematical method to describe a polygonal section with rounded edges and vertices. This mathematical model would be quite useful for analyzing the mechanical properties of plants and designing plant-mimicking functional structures, since the cross-sections of the actual plant culms and stems often show rounded polygons.

scholarly journals Form, function, and divergence of a generic fin shape in small cetaceans

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255464
Author(s):  
Vadim Pavlov ◽  
Cecile Vincent ◽  
Bjarni Mikkelsen ◽  
Justine Lebeau ◽  
Vincent Ridoux ◽  
...  
Keyword(s):  
Body Length ◽  
Cross Sections ◽  
The Body ◽  
Hydrodynamic Characteristics ◽  
Wing Design ◽  
Cross Sectional ◽  
Aquatic Life ◽  
Dorsal Fin ◽  
Primary Function ◽  
Fin Shape

Tail flukes as well as the dorsal fin are the apomorphic traits of cetaceans which appeared during the evolutionary process of adaptation to the aquatic life. Both appendages present a wing-like shape associated with lift generation and low drag. We hypothesized that the evolution of fins as lifting structures led to a generic wing design, where the dimensionless parameters of the fin cross-sections are invariant with respect to the body length and taxonomy of small cetaceans (Hypothesis I). We also hypothesized that constraints on variability of a generic fin shape are associated with the primary function of the fin as a fixed or flapping hydrofoil (Hypothesis II). To verify these hypotheses, we examined how the variation in the fin’s morphological traits is linked to the primary function, species and body length. Hydrodynamic characteristics of the fin cross-sections were examined with the CFD software and compared with similar engineered airfoils. Generic wing design of both fins was found in a wing-like planform and a streamlined cross-sectional geometry optimized for lift generation. Divergence in a generic fin shape both on the planform and cross-sectional level was found to be related with the fin specialization in fixed or flapping hydrofoil function. Cross-sections of the dorsal fin were found to be optimized for the narrow range of small angles of attack. Cross-sections of tail flukes were found to be more stable for higher angles of attack and had gradual stall characteristics. The obtained results provide an insight into the divergent evolutionary pathways of a generic wing-like shape of the fins of cetaceans under specific demands of thrust production, swimming stability and turning control.

scholarly journals Effect of chronic undernutrition on body mass and mechanical bone quality under normoxic and altitude hypoxic conditions

2016 ◽  
Vol 115 (9) ◽  
pp. 1687-1695 ◽  
Author(s):  
Christian Lezon ◽  
Clarisa Bozzini ◽  
Alan Agûero Romero ◽  
Patricia Pinto ◽  
Graciela Champin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Body Mass ◽  
Food Restriction ◽  
The Body ◽  
Male Rats ◽  
Bending Test ◽  
Cross Sectional ◽  
Geometric Properties ◽  
Left Femur ◽  
Catch Up

AbstractBoth undernutrition and hypoxia exert a negative influence on both growth pattern and bone mechanical properties in developing rats. The present study explored the effects of chronic food restriction on both variables in growing rats exposed to simulated high-altitude hypoxia. Male rats (n 80) aged 28 d were divided into normoxic (Nx) and hypoxic (Hx) groups. Hx rats were exposed to hypobaric air (380 mmHg) in decompression chambers. At T0, Nx and Hx rats were subdivided into four equal subgroups: normoxic control and hypoxic controls, and normoxic growth-restricted and hypoxic growth-restricted received 80 % of the amount of food consumed freely by their respective controls for a 4-week period. Half of these animals were studied at the end of this period (T4). The remaining rats in each group continued under the same environmental conditions, but food was offered ad libitum to explore the type of catch-up growth during 8 weeks. Structural bone properties (strength and stiffness) were evaluated in the right femur midshaft by the mechanical three-point bending test; geometric properties (length, cross-sectional area, cortical mass, bending cross-sectional moment of inertia) and intrinsic properties of the bone tissue (elastic modulus) were measured or derived from appropriate equations. Bone mineralisation was assessed by ash measurement of the left femur. These data indicate that the growth-retarded effects of diminished food intake, induced either by food restriction or hypoxia-related inhibition of appetite, generated the formation of corresponding smaller bones in which subnormal structural and geometric properties were observed. However, they seemed to be appropriate to the body mass of the animals and suggest, therefore, that the bones were not osteopenic. When food restriction was imposed in Hx rats, the combined effects of both variables were additive, inducing a further reduction of bone mass and bone load-carrying capacity. In all cases, the mechanical properties of the mineralised tissue were unaffected. This and the capacity of the treated bones to undergone complete catch-up growth with full restoration of the biomechanical properties suggest that undernutrition, under either Nx or Hx conditions, does not affect bone behaviour because it remains appropriate to its mechanical functions.

scholarly journals Microfluidics in structured multimaterial fibers

2018 ◽  
Vol 115 (46) ◽  
pp. E10830-E10838 ◽  
Author(s):  
Rodger Yuan ◽  
Jaemyon Lee ◽  
Hao-Wei Su ◽  
Etgar Levy ◽  
Tural Khudiyev ◽  
...  
Keyword(s):  
Cross Sections ◽  
Cell Separation ◽  
Degrees Of Freedom ◽  
Microfluidic Channels ◽  
Drawing Process ◽  
Cross Sectional ◽  
Separation Device ◽  
Chip Format ◽  
External Forces ◽  
Thermal Drawing

Traditional fabrication techniques for microfluidic devices utilize a planar chip format that possesses limited control over the geometry of and materials placement around microchannel cross-sections. This imposes restrictions on the design of flow fields and external forces (electric, magnetic, piezoelectric, etc.) that can be imposed onto fluids and particles. Here we report a method of fabricating microfluidic channels with complex cross-sections. A scaled-up version of a microchannel is dimensionally reduced through a thermal drawing process, enabling the fabrication of meters-long microfluidic fibers with nonrectangular cross-sectional shapes, such as crosses, five-pointed stars, and crescents. In addition, by codrawing compatible materials, conductive domains can be integrated at arbitrary locations along channel walls. We validate this technology by studying unexplored regimes in hydrodynamic flow and by designing a high-throughput cell separation device. By enabling these degrees of freedom in microfluidic device design, fiber microfluidics provides a method to create microchannel designs that are inaccessible using planar techniques.

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