A mathematical model of body kinematics in swimming tadpoles

1993 ◽  
Vol 71 (2) ◽  
pp. 407-413 ◽  
Author(s):  
W. M. Oxner ◽  
J. Quinn ◽  
M. E. DeMont
Keyword(s):  
Mathematical Model ◽  
Resonant Frequency ◽  
The Body ◽  
Numerical Techniques ◽  
Cross Sectional ◽  
Finite Dimensional ◽  
Straight Line ◽  
Locomotor Muscles ◽  
Variable Moment ◽  
Good Agreement

A mathematical model is described that predicts the body kinematics of tadpoles swimming in a straight line at constant velocity. The model is a forced beam with a variable moment of inertia and cross-sectional area. The beam is free at both ends and forced cyclically at the position that corresponds to the base of the tail in a real animal. This forcing regime simulates the real contraction of locomotor muscles. Finite-dimensional numerical techniques were used to approximate the solution. The lowest predicted fundamental frequency of vibration should be the resonant frequency of vibration of the tadpole. The predicted resonant frequency and the observed swimming frequencies were in good agreement.

scholarly journals Measuring Aerodynamic Interference Drag Between a Bird Body and the Mounting Strut of a drag Balance

1990 ◽  
Vol 154 (1) ◽  
pp. 439-461 ◽  
Author(s):  
VANCE A. TUCKER
Keyword(s):  
Reynolds Numbers ◽  
The Body ◽  
Peregrine Falcon ◽  
Rigid Surface ◽  
Hand Tools ◽  
Cross Sectional ◽  
Straight Line ◽  
Aerodynamic Interference ◽  
The Relationship

1. The drag of a bird body mounted on the strut of a drag balance in a wind tunnel is more than the sum of the drags of the isolated strut and the isolated body. The strut changes the air flow around the body and generates additional drag, known as interference drag. This paper describes practical methods for measuring the drag of bird bodies: a strain-gauge drag balance, dimensions for struts made with machine or hand tools, and a procedure for correcting drag measurements for interference drag. 2. Interference drag can be measured by extrapolating a relationship between the drag of isolated struts with different crosssectional sizes and shapes and the drag of a body mounted on those struts. The interference length the length of an isolated strut that produces drag equal to the interference drag is a usefulquantity for predicting interference drag. 3. The relationship mentioned above is a straight line for a model peregrine falcon (Falco peregrinus L.) body mounted on smooth struts struts with convex cross-sectional shapes ranging from streamlined to circular. This finding simplifies the determination of interference drag in three ways: (i) the line can be found from measurements with just two struts a standard strut with low drag and a calibration strut with high drag; (ii) the two struts need not have the same shape for example, the standard strut can be changed to a calibration strut by attaching a spoiler without disturbing the body mounted on the strut and (iii) a single value of interference length (33.1mm) describes smooth struts with a range of shapes and sizes. These struts had drag coefficients between 0.33 and 0.91 at Reynolds numbers between 2100 and 10800. 4. The interference length of a strut supporting the actual falcon body with a feathered surface is not significantly different from that of the strut supporting the model body with a rigid surface. 5. As a hypothesis, interference length (hI, in metres) of a smooth strut varieswith the size of the body mounted on it: hI=0.0365m0.333 where m is the body mass (in kg) of the intact bird.

Forced Vibration of a Body on an Elastic Stratum

1957 ◽  
Vol 24 (1) ◽  
pp. 55-58
Author(s):  
G. B. Warburton
Keyword(s):  
Resonant Frequency ◽  
Surface Area ◽  
Forced Vibration ◽  
The Body ◽  
Constant Depth ◽  
Disturbing Force ◽  
Axis Of Symmetry ◽  
Experimental Values ◽  
Circular Base ◽  
Good Agreement

Abstract The paper considers the forced vibration of a body with a circular base resting on a homogeneous elastic stratum of infinite surface area and constant depth. The body is subjected to a vertical disturbing force along the axis of symmetry. After evaluating an integral given by Arnold, Bycroft, and Warburton, curves are given showing the dependence of the resonant frequency on three parameters. Good agreement is obtained between theoretical values of the resonant frequency and experimental values taken from the previous paper.

scholarly journals Three-dimensional flow structures and vorticity control in fish-like swimming

2002 ◽  
Vol 468 ◽  
pp. 1-28 ◽  
Author(s):  
Q. ZHU ◽  
M. J. WOLFGANG ◽  
D. K. P. YUE ◽  
M. S. TRIANTAFYLLOU
Keyword(s):  
Structural Model ◽  
Three Dimensional ◽  
Travelling Wave ◽  
The Body ◽  
Cross Sectional ◽  
Propulsive Efficiency ◽  
Straight Line ◽  
Giant Danio ◽  
Oscillating Plate ◽  
High Thrust

We employ a three-dimensional, nonlinear inviscid numerical method, in conjunction with experimental data from live fish and from a fish-like robotic mechanism, to establish the three-dimensional features of the flow around a fish-like body swimming in a straight line, and to identify the principal mechanisms of vorticity control employed in fish-like swimming. The computations contain no structural model for the fish and hence no recoil correction. First, we show the near-body flow structure produced by the travelling-wave undulations of the bodies of a tuna and a giant danio. As revealed in cross-sectional planes, for tuna the flow contains dominant features resembling the flow around a two-dimensional oscillating plate over most of the length of the fish body. For the giant danio, on the other hand, a mixed longitudinal–transverse structure appears along the hind part of the body. We also investigate the interaction of the body-generated vortices with the oscillating caudal fin and with tail-generated vorticity. Two distinct vorticity interaction modes are identified: the first mode results in high thrust and is generated by constructive pairing of body-generated vorticity with same-sign tail-generated vorticity, resulting in the formation of a strong thrust wake; the second corresponds to high propulsive efficiency and is generated by destructive pairing of body-generated vorticity with opposite-sign tail-generated vorticity, resulting in the formation of a weak thrust wake.

scholarly journals Mechanical work rate minimization and freely chosen stride frequency of human walking: a mathematical model

1992 ◽  
Vol 170 (1) ◽  
pp. 19-34 ◽  
Author(s):  
A. E. Minetti ◽  
F. Saibene
Keyword(s):  
Mathematical Model ◽  
Work Rate ◽  
The Body ◽  
Mechanical Work ◽  
Stride Frequency ◽  
External Work ◽  
High Speeds ◽  
Theoretical Predictions ◽  
Work Done ◽  
Good Agreement

The interplay between the work done to move the body centre of mass with respect to the environment (external work) and the work done to move the limbs with respect to the body (internal work) has been shown experimentally partially to determine the freely chosen stride frequency during walking. A mathematical model that estimates the two components of the mechanical work is proposed. The model, according to the criterion of work rate minimization (both positive and positive plus negative), is able to predict the natural stride frequency as a function of the average progression speed. The adequacy of the model and the validity of the assumptions have been checked against measurements of natural stride frequency in 11 subjects walking on a treadmill at several speeds (range 1–3 m s-1). Comparison with theoretical predictions shows good agreement with the minimization of positive work rate at low speeds, while at high speeds the stride frequency is better explained by the model for minimum positive plus negative work rate.

Further Results on the Analysis of Penetrator Stability in Sand and Soil Targets — I

2005 ◽  
Author(s):  
Courtney H. Graham ◽  
S. E. Jones ◽  
Mary L. Hughes ◽  
Kathryn G. Lee
Keyword(s):  
Stability Estimate ◽  
The Body ◽  
Regular Perturbation ◽  
Cross Sectional ◽  
Crude Approximation ◽  
Long Rod ◽  
The Stability ◽  
Specific Concern ◽  
Good Agreement ◽  
Made In

In an earlier paper [1], a fundamental analysis of penetrator stability was presented that resulted in a simple criterion for penetrator design. This criterion was based on some features of long rod penetrator design that could be anticipated: namely, length, cross-sectional area of the shank, area moment of inertia of the cross-section, and the elastic properties of the body material. A number of approximations were made in this early work to reduce the complexity of the modeling effort. Of course, this led to some uncertainties in the results. The purpose of this paper is to explore some of the more prominent sources of uncertainty and to refine the stability estimate. Of specific concern is the effect of a crude approximation on the lowest Eigen function in the problem. In this paper, a small parameter is identified and used to find a regular perturbation solution. The results are found to be in good agreement with those presented earlier.

A MATHEMATICAL MODEL AND A SIMULATIONAL INVESTIGATION OF A PLANAR SYSTEM UNDER OBLIQUE MULTIPOINT IMPACT WITH FRICTION

Tribologia ◽  
2020 ◽  
Vol 291 (3) ◽  
pp. 53-62
Author(s):  
Mariusz Warzecha
Keyword(s):  
Mathematical Model ◽  
The Body ◽  
Force Model ◽  
Angle Of Incidence ◽  
Planar System ◽  
First Case ◽  
The Coefficient Of Friction ◽  
Parameter Values ◽  
Impact With Friction ◽  
Good Agreement

This article presents a mathematical model of a planar system for the multipoint, oblique, and eccentric impact of rough bodies. The created model served for numerical investigations of the system’s behaviour. To analyse the influence of various parameters, three simplified cases were defined. Each of these cases focused on different aspects of the simulation. The first case was used to determine how many contacting bodies undergo impact at a given time point. This result was then compared with the experimental observations, which gave good agreement. The second case investigated the influence of the body configuration and the coefficient of friction (COF) on the sliding process during impact. Depending on the parameter values, the sliding process was divided into three main areas: slip-reversal slip, slip-stick, and continuous slip with increasing sliding velocity. The third case focused on the energy dissipation expressed by the coefficient of restitution (COR) and the angle of incidence of the initiating impact; this case showed possible improvement areas of the used impact force model.

X-ray micro tomography in the scanning electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 106-107 ◽  
Author(s):  
W. Brünger
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Target Surface ◽  
The Body ◽  
X Rays ◽  
Cross Sectional ◽  
X Ray ◽  
Micro Tomography ◽  
Scanning Electron

Reconstructive tomography is a new technique in diagnostic radiology for imaging cross-sectional planes of the human body /1/. A collimated beam of X-rays is scanned through a thin slice of the body and the transmitted intensity is recorded by a detector giving a linear shadow graph or projection (see fig. 1). Many of these projections at different angles are used to reconstruct the body-layer, usually with the aid of a computer. The picture element size of present tomographic scanners is approximately 1.1 mm2.Micro tomography can be realized using the very fine X-ray source generated by the focused electron beam of a scanning electron microscope (see fig. 2). The translation of the X-ray source is done by a line scan of the electron beam on a polished target surface /2/. Projections at different angles are produced by rotating the object.During the registration of a single scan the electron beam is deflected in one direction only, while both deflections are operating in the display tube.

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.

PEMBELAJARAN SIMULASI PENCITRAAN CT DENGAN MENGGUNAKAN PRINSIP REKONSTRUKSI CITRA DALAM SOFTWARE MATLAB

2015 ◽  
Vol 8 (3) ◽  
pp. 161
Author(s):  
Samuel Gideon
Keyword(s):  
Image Reconstruction ◽  
Ct Imaging ◽  
The Body ◽  
Reconstruction Technique ◽  
Imaging Features ◽  
Back Projection ◽  
Cross Sectional ◽  
Low Contrast ◽  
Image Reconstruction Technique ◽  
Imaging Algorithms

This research was conducted as a learning alternatives for study of CT (computed tomograpghy) imaging using image reconstruction technique which are inversion matrix, back projection and filtered back projection. CT imaging can produce images of objects that do not overlap. Objects more easily distinguishable although given the relatively low contrast. The image is generated on CT imaging is the result of reconstruction of the original object. Matlab allows us to create and write imaging algorithms easily, easy to undersand and gives applied and exciting other imaging features. In this study, an example cross-sectional image recon-struction performed on the body of prostate tumors using. With these methods, medical prac-titioner (such as oncology clinician, radiographer and medical physicist) allows to simulate the reconstruction of CT images which almost resembles the actual CT visualization techniques.Keywords : computed tomography (CT), image reconstruction, Matlab

Effect of Varied Probe Length on the Resonant Frequency of a Circular Cross-Sectional Cavity

2005 ◽  
Vol 2 (2) ◽  
pp. 79
Author(s):  
Mohd Khairul Mohd Salleh ◽  
Mohamad Syukri Suhaili ◽  
Zuhani Ismail ◽  
Zaiki Awang
Keyword(s):  
Resonant Frequency ◽  
Cavity Resonator ◽  
Simple Design ◽  
Cross Sectional ◽  
Probe Length ◽  
Mode Wave ◽  
The One

A simple design of a metallic circular cross-sectional air-filled cavity is presented. Two probes of varied lengths are used to excite TE112-mode wave into the cavity to give a resonant frequency of 5.86 GHz. The experiments show that the resonant frequency of the cavity resonator decreases as the lengths of the probes are increased. The shortest probe in the range of study gives the closest resonant frequency to the one desired.

Sign in / Sign up

Export Citation Format

Share Document