Measuring the angle of attack of beating insect wings: robust three-dimensional reconstruction from two-dimensional images

1997 ◽  
Vol 200 (21) ◽  
pp. 2693-2704 ◽  
Author(s):  
A Willmott ◽  
C Ellington
Keyword(s):  
High Speed ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Numerical Algorithms ◽  
Longitudinal Axis ◽  
Wing Motion ◽  
Insect Wings ◽  
High Speed Film ◽  
Dimensional Reconstruction ◽  
Left And Right

A robust technique for determining the angle of attack of insect wings from film of free flight has to date proved elusive. This report describes the development of two new methods ­ the Strips and Planes techniques ­ which were designed to overcome some of the limitations experienced in previous studies. The accuracy and robustness of these novel methods were tested extensively using simulated hawkmoth wing outlines generated for a realistic range of wing positions and torsion. The results were compared with those from two existing methods ­ the Symmetry and Landmarks procedures. The performance of the latter technique will be strongly species-dependent; it could not be successfully applied to hawkmoth flight because of practical difficulties in obtaining suitable landmarks. The Planes method was the least successful of the remaining techniques, especially during those phases of the wingbeat when the orientations of the two wings relative to the camera viewpoint were similar. The Symmetry and Strips methods were tested further to investigate the effects on their performance of introducing additional camber or wing motion asymmetry. The results showed clearly that the Strips method should be the technique of choice wherever the axis of wing torsion is close to the longitudinal axis of the wing. The procedure involves the experimenter matching a model wing divided into chordwise strips to the true wing outline digitized from high-speed film. The use of strips rather than the points digitized in previous studies meant that the analysis required only one wing outline to be digitized. Symmetry of motion between the left and right wings is not assumed. The implications of requiring human input to the Strips method, as opposed to the strictly numerical algorithms of the alternative techniques, are discussed. It is argued that the added flexibility that this provides in dealing with images which have typically been recorded in suboptimal conditions outweighs the introduction of an element of subjectivity. Additional observations arising from the use of the Strips analysis with high-speed video sequences of hawkmoth flight are given.

Mechanics of Forward Flight in Bumblebees: I. Kinematics and Morphology

1990 ◽  
Vol 148 (1) ◽  
pp. 19-52 ◽  
Author(s):  
R. DUDLEY ◽  
C. P. ELLINGTON
Keyword(s):  
High Speed ◽  
Morphological Analysis ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Free Flight ◽  
Forward Flight ◽  
Body Angle ◽  
Dimensional Reconstruction ◽  
High Speed Cinematography ◽  
Wing Tip

Using high-speed cinematography, bumblebees in free flight were filmed over a range of forward airspeeds. A detailed description of the wing tip and body kinematics was obtained from a three-dimensional reconstruction of the twodimensional film image. A technique for determining quantitatively the angle of attack of the wing was developed. Kinematic parameters found to vary consistently with airspeed were body angle, stroke plane angle, geometrical angle of attack, and rotational angles of the wings at the ends of half-strokes. Results of a morphological analysis of the wings and bodies of thoseinsects filmed in free flight are presented for use in later calculations of the lift and power requirements of forward flight.

Three-dimensional reconstruction of metabolic data from quantitative autoradiography of rat brain

1984 ◽  
Vol 247 (3) ◽  
pp. E412-E419 ◽  
Author(s):  
L. S. Hibbard ◽  
R. A. Hawkins
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Image Data ◽  
Brain Structures ◽  
Three Dimensions ◽  
Quantitative Autoradiography ◽  
Alignment Algorithm ◽  
Computer Methods ◽  
Mathematical Properties ◽  
Dimensional Reconstruction

Quantitative autoradiography is a powerful method for studying brain function by the determination of blood flow, glucose utilization, or transport of essential nutrients. Autoradiographic images contain vast amounts of potentially useful information, but conventional analyses can practically sample the data at only a small number of points arbitrarily chosen by the experimenter to represent discrete brain structures. To use image data more fully, computer methods for its acquisition, storage, quantitative analysis, and display are required. We have developed a system of computer programs that performs these tasks and has the following features: 1) editing and analysis of single images using interactive graphics, 2) an automatic image alignment algorithm that places images in register with one another using only the mathematical properties of the images themselves, 3) the calculation of mean images from equivalent images in different experimental serial image sets, 4) the calculation of difference images (e.g., experiment-minus-control) with the option to display only differences estimated to be statistically significant, and 5) the display of serial image metabolic maps reconstructed in three dimensions using a high-speed computer graphics system.

scholarly journals Vortex flow and cavitation in diesel injector nozzles

2008 ◽  
Vol 610 ◽  
pp. 195-215 ◽  
Author(s):  
A. ANDRIOTIS ◽  
M. GAVAISES ◽  
C. ARCOUMANIS
Keyword(s):  
High Speed ◽  
Fuel Injection ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Fuel Injector ◽  
Flowing Liquid ◽  
Injection Quantity ◽  
Dimensional Reconstruction ◽  
Real Size

Flow visualization as well as three-dimensional cavitating flow simulations have been employed for characterizing the formation of cavitation inside transparent replicas of fuel injector valves used in low-speed two-stroke diesel engines. The designs tested have incorporated five-hole nozzles with cylindrical as well as tapered holes operating at different fixed needle lift positions. High-speed images have revealed the formation of an unsteady vapour structure upstream of the injection holes inside the nozzle volume, which is referred to as ‘string-cavitation’. Computation of the flow distribution and combination with three-dimensional reconstruction of the location of the strings inside the nozzle volume has revealed that strings are found at the core of recirculation zones; they originate either from pre-existing cavitation sites forming at sharp corners inside the nozzle where the pressure falls below the vapour pressure of the flowing liquid, or even from suction of outside air downstream of the hole exit. Processing of the acquired images has allowed estimation of the mean location and probability of appearance of the cavitating strings in the three-dimensional space as a function of needle lift, cavitation and Reynolds number. The frequency of appearance of the strings has been correlated with the Strouhal number of the vortices developing inside the sac volume; the latter has been found to be a function of needle lift and hole shape. The presence of strings has significantly affected the flow conditions at the nozzle exit, influencing the injected spray. The cavitation structures formed inside the injection holes are significantly altered by the presence of cavitation strings and are jointly responsible for up to 10% variation in the instantaneous fuel injection quantity. Extrapolation using model predictions for real-size injectors operating at realistic injection pressures indicates that cavitation strings are expected to appear within the time scales of typical injection events, implying significant hole-to-hole and cycle-to-cycle variations during the corresponding spray development.

scholarly journals Experiment, Optimization, and Design of Electromagnetic Track Brake for High-Speed Railways System

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Chun Xiang ◽  
Jun-Cheng Wang ◽  
Yu-Feng Gu ◽  
Shi-Jin Zhang ◽  
Shi-An Chen
Keyword(s):  
High Speed ◽  
Copper Wire ◽  
Final Height ◽  
Three Dimensional ◽  
Single Layer ◽  
Longitudinal Axis ◽  
Iron Core ◽  
Railway Systems ◽  
Magnetic Circuits ◽  
Final Design

To enhance braking force and control convenience of high-speed railway systems, this paper proposes a new electromagnetic track brake, and the corresponding design, optimization, and experimental test are implemented. The proposed track brake is longitudinal-axis magnetic circuits excited by multiple coils electromagnets, and the pole shoes are extending outward. A preliminary design of an electromagnetic track brake is developed, including iron core height, iron core width, iron core gap, excitation ampere-turn, coil arrangement form, coil thickness, and preliminary height of single-layer coil. The electromagnet number and pole shoe gap are optimized through three-dimensional electromagnetic simulation comparisons. The final design of the electromagnetic track brake is determined, including iron core length, copper wire diameter, coil turn, and final height of single-layer coil. Experimental verification of electromagnetic attractive force is performed through prototype tests, and the newly developed electromagnetic track brake can enhance electromagnetic braking deceleration by 39%.

Simple mechanisms organise orientation of escape swimming in embryos and hatchling tadpoles of Xenopus laevis

2000 ◽  
Vol 203 (12) ◽  
pp. 1869-1885 ◽  
Author(s):  
A. Roberts ◽  
N.A. Hill ◽  
R. Hicks
Keyword(s):  
Mathematical Model ◽  
Xenopus Laevis ◽  
High Speed ◽  
Three Dimensional ◽  
Longitudinal Axis ◽  
The Body ◽  
Video Recordings ◽  
Stage Of Development ◽  
Physical Features ◽  
Neutrally Buoyant

Many amphibian tadpoles hatch and swim before their inner ears and sense of spatial orientation differentiate. We describe upward and downward swimming responses in hatchling Xenopus laevis tadpoles from stages 32 to 37/38 in which the body rotates about its longitudinal axis. Tadpoles are heavier than water and, if touched while lying on the substratum, they reliably swim upwards, often in a tight spiral. This response has been observed using stroboscopic photography and high-speed video recordings. The sense of the spiral is not fixed for individual tadpoles. In ‘more horizontal swimming’ (i.e. in directions within +/−30 degrees of the horizontal), the tadpoles usually swim belly-down, but this position is not a prerequisite for subsequent upward spiral swimming. Newly hatched tadpoles spend 99 % of their time hanging tail-down from mucus secreted by a cement gland on the head. When suspended in mid-water by a mucus strand, tadpoles from stage 31 to 37/38 tend to swim spirally down when touched on the head and up when touched on the tail. The three-dimensional swimming paths of stage 33/34 tadpoles were plotted using simultaneous video images recorded from the side and from above. Tadpoles spiralled for 70 % of the swimming time, and the probability of spiralling increased to 1 as swim path angles became more vertical. Tadpoles were neutrally buoyant in Percoll/water mixtures at 1.05 g cm(−)(3), in which anaesthetised tadpoles floated belly-down and head-up at 30 degrees. In water, their centre of mass was ventral to the muscles in the yolk mass. A simple mathematical model suggests that the orientation of tadpoles during swimming is governed by the action of two torques, one of which raises the head (i.e. increases the pitch) and the other rotates (rolls) the body. Consequently, tadpoles (i) swim belly-down when the body is approximately horizontal because the body is ballasted by dense yolk, and (ii) swim spirally at more vertical orientations when the ballasting no longer stabilises orientation. Measurements in tethered tadpoles show that dorsal body flexion, which could produce a dorsal pitch torque, is present during swimming and increases with tailbeat frequency. We discuss how much of the tadpole's behaviour can be explained by our mathematical model and suggest that, at this stage of development, oriented swimming responses may depend on simple touch reflexes, the organisation of the muscles and physical features of the body, rather than on vestibular reflexes.

High-speed intracoronary optical frequency domain imaging: implications for three-dimensional reconstruction and quantitative analysis

2012 ◽  
Vol 7 (10) ◽  
pp. 1216-1226 ◽  
Author(s):  
Takayuki Okamura ◽  
Yoshinobu Onuma ◽  
Hector M. Garcia-Garcia ◽  
Nico Bruining ◽  
Patrick W. Serruys
Keyword(s):  
Quantitative Analysis ◽  
Frequency Domain ◽  
High Speed ◽  
Three Dimensional ◽  
Optical Frequency ◽  
Three Dimensional Reconstruction ◽  
Optical Frequency Domain Imaging ◽  
Dimensional Reconstruction

The wing beat of Drosophila Melanogaster . I. Kinematics

1990 ◽  
Vol 327 (1238) ◽  
pp. 1-18 ◽  
Keyword(s):  
Drosophila Melanogaster ◽  
Special Interest ◽  
Motion Pictures ◽  
Three Dimensional ◽  
Slow Motion ◽  
Published Data ◽  
Wing Beat ◽  
Three Dimensional Reconstruction ◽  
Wing Motion ◽  
Dimensional Reconstruction

The wing beat of small insects attracts special interest because conventional aerodynamics predict a reduction of flight efficiency when aerofoils are small and slow. The kinematics of the wing beat of tethered flying Drosophila melanogaster were investigated by using artificial slow motion pictures which were generated by single strobe flashes triggered in synchrony with the wing beat. The properties of Drosophila wing motion are described qualitatively and compared with the published data for other dipteran insects. Drosophila moves its wings in a pattern that differs considerably from the well-documented wing beat of the bigger blowfly Phormia . By means of a computerized three-dimensional reconstruction, the variables of the wing-beat cycle, such as wing path and angles of attack, are analysed quantitatively. These data will be the basis of aerodynamic calculations presented in accompanying papers.

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