Wing Height Research Articles

Allometry as evidence of sexual selection in monochromatic birds: the case of the Coscoroba Swan (Anseriformes: Anatidae)

The Coscoroba Swan, Coscoroba coscoroba (Molina, 1782), is a poorly known aberrant Anserine endemic to South America. We captured adult birds (189 male, 157 female) from the largest population in Brazil at the Taim Ecological Reserve, State of Rio Grande do Sul, Brazil. Different patterns between sexes can reflect differences in selection, and positive allometry may indicate that a character is sexually selected. We used body weight and 10 morphological measurements to examine allometric differences between males and females of C. coscoroba. Males were consistently larger than females. Analysis of scaling relationships against body mass showed that nostril, tail, wing and bill height were positively allometric (i.e., heavier birds had relatively larger character lengths), but there were no sexual differences in allometric slopes. However, for a given mass, mature females had longer tails, longer wings (up to metacarpophalangeal articulation) and shorter heads than males. In the light of current debate in the literature, we discuss whether such positively allometric traits and sexual differences in scaling may be indicative of sexual selection. Although Coscoroba Swan is a monogamous species, increasing the size of some attributes may confer some advantage for mate selection or male-male competition and, contrary to other studies, we suggest that positively allometric slopes alone should not be considered as evidence for sexual selection of the considered traits.

Lifting-Line Predictions for Induced Drag and Lift in Ground Effect

Closed-form relations are presented for estimating ratios of the induced-drag and lift coefficients acting on a wing in ground effect to those acting on the same wing outside the influence of ground effect. The closed-form relations for these ground-effect influence ratios were developed by correlating results obtained from numerical solutions to Prandtl’s lifting-line theory. Results show that these influence ratios are not unique functions of the ratio of wing height to wingspan, as is sometimes suggested in the literature. These ground-effect influence ratios also depend on the wing planform, aspect ratio, and lift coefficient.

Role of a collision-sensitive neuron during collision avoidance in flight

Event Abstract Back to Event Role of a collision-sensitive neuron during collision avoidance in flight Raymond W. Chan1*, Fabrizio Gabbiani1, 2 and Reid Harrison3 1 Baylor College of Medicine, United States 2 Rice University, United States 3 Intan Technologies, LLC, United States The neural mechanisms underlying collision avoidance in flight are largely unknown territory. Using a custom designed telemetry chip we record from the DCMD (Descending Contralateral Movement Detector), a collision detecting neuron, and flight muscles of a locust (Schistocerca americana) flying in a wind tunnel. Simultaneously, two high-speed video cameras are used to record flight data of the locust while it performs collision avoidance manoeuvres in response to the simulated approach of an object on a collision course with the animal (i.e., a looming stimulus). Using custom built software, we reconstruct in 3D flight parameters like body orientation and wing height from the stereoscopic videos. Neural data is then correlated with behavioural data to shed light on the neural basis of this behaviour. In addition, we design a filter-based system using the muscle and neural signals to control a virtual drone. Figure 1 Keywords: collision avoidance, DCMD, flight, grasshopper, Locust, Robotics, Wireless Neural Recording Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster (but consider for student poster award) Topic: Sensory: Vision Citation: Chan RW, Gabbiani F and Harrison R (2012). Role of a collision-sensitive neuron during collision avoidance in flight. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00119 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 25 Apr 2012; Published Online: 07 Jul 2012. * Correspondence: Dr. Raymond W Chan, Baylor College of Medicine, Houston, United States, rchan@cns.bcm.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Raymond W Chan Fabrizio Gabbiani Reid Harrison Google Raymond W Chan Fabrizio Gabbiani Reid Harrison Google Scholar Raymond W Chan Fabrizio Gabbiani Reid Harrison PubMed Raymond W Chan Fabrizio Gabbiani Reid Harrison Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Lateral Stability of High Wing Configurations

Existing approximations for the effect of wing height on lateral stability are examined and found to be inadequate for configurations with a large ratio of body diameter to wing span. A closed form expression for elliptically loaded wings is developed that matches prior approximations for conventional configurations while also giving the correct trends for the large body configurations. The method compares favorably with results from a recently completed wind tunnel test. Nomenclature A = Aspect ratio b = Wing span c = Wing chord cl = Airfoil section lift curve slope CL = Wing lift curve slope Cl = Rolling moment coefficient Cl = Rate of change of rolling moment with sideslip (lateral stability) d = Body diameter or diameter of equivalent circular cross-section h = Body height w = Body width z = Height of wing above body centerline

Management of Two-Dimensional Channel Flow with a Pair of Streamwise Vortices (Behavior of Streamwise Vortices and Mean Velocity Field)

An experimental study was conducted to examine the management of a two-dimensional turbulent channel flow with a pair of streamwise vortices. A common-flow down type streamwise vortex pair, generated by a pair of half-delta wings mounted on the wall, was introduced into a fully developed turbulent channel flow. The half-delta wings were as high as the inner layer thickness of the channel flow. The mean velocity and Reynolds shear stress distributions were measured and various properties were obtained in order to find meanings of the vortex generator for management of the turbulent channel flow. The convective motion of the secondary current is responsible for most of the streamwise momentum transfer toward the wall in the interaction between the vortices and the shear layer. In the velocity profile averaged over the spanwise extent, the velocity is accelerated below the vortex center and decelerated above the vortex center. Deformation of the mean velocity profile remained at the remarkable downstream distance of 250 times the wing height, which corresponds to 50 times channel the half-width H.

비평면 지면효과를 받는 날개들의 종방향 정안정성

채널 및 레일과 같은 비평면 지면 위를 비행하는 날개들의 정상상태 공력특성 및 종방향 정안정성을 경계요소법을 사용하여 연구하였다. 펜스의 높이가 날개의 위치보다 높을 경우, 펜스와 날개와의 거리가 작아질수록 양력이 증가하고 피칭다운 모멘트가 커졌다. 레일의 폭이 날개 스팬보다 넓을 때, 레일의 높이가 낮을수록 양력이 증가하고 유도항력이 감소하였다. 종방향 정안정성 측면에서 단일 날개의 경우 비평면 지면보다 평지에서 안정한 결과를 나타내었다. 종렬배치형 날개의 경우 채널내를 비행하는 날개가 평지보다 비평면 지면에서 안정적이었다. 본 연구결과는 초고속운송체의 설계에 적용될 수 있을 것으로 기대한다. Longitudinal static stability and steady aerodynamic characteristics of wings flying over nonplanar ground surfaces (rail and channel) are investigated using the boundary-element method. For a channel with it's fence higher than the wing height, the lift and the nose-down pitching moment increase as the gap between the wingtip and the fence decreases. For a rail with it's width wider than the wing span, the lift and the nose-down pitching moment increase as the rail height decreases. Longitudinal static stability of a single wing flying over nonplanar surfaces is worse than the case of the flat ground. In case of tandem wings, longitudinal static stability of the wings flying over the channel is better than the case of the flat ground. It is believed that the present results can be applied to the conceptual design of high-speed ground transporters.

Steady aerodynamic characteristics of a wing flying over a nonplanar ground surface Part I: Rail

The steady aerodynamic characteristics of a wing flying over a channel are investigated using a boundary-element method. The present method is validated by comparing the computed results with the measured data. Compared with a flat ground surface, the channel fence augmented the lift increase and induced drag reduction. When the fence is lower than the wing height, the gap between the wingtip and the fence does not affect the aerodynamic characteristics of the wing much. When the fence is higher than the wing height, the close gap increased the lift. The induced drag is reduced when the wing is placed near the ground or at the same height as the fence. It is believed that present results can be used in the conceptual design of the high-speed ground transporters flying over the channel.

Defect reduction in (11-20) a-plane GaN by two-step epitaxial lateral overgrowth

ABSTRACTWe report a two-step growth method to obtain uniformly coalesced epitaxial lateral overgrown a-plane GaN by metalorganic chemical vapor deposition (MOCVD). By obtaining a large wing height to width aspect ratio in the first step followed by enhanced lateral growth in the second step via controlling the growth temperature, we reduced the tilt angle between the advancing Ga-polar and N-polar wings for improved properties. Transmission electron microscopy (TEM) showed that the threading dislocation density in the wing area was 1.0×108cm−2, more than two orders of magnitude lower than that in the window area (4.2×1010cm−2). However, a high density of basal stacking faults, 1.2×104cm−1, was still observed in the wing area. Near field scanning optical microscopy (NSOM) at room temperature revealed that the luminescence was mainly from the wing regions with very little contribution from the windows and meeting fronts. These observations suggest that due to significant reduction of threading dislocations radiative recombination is enhanced in the wings.

Management of Two-dimensional Channel Flow with a Pair of Streamwise Vortices (Behaviour of Streamwise Vortices and Mean Velocity Field)

An experimental study has been made on the management of a two-dimensional turbulent channel flow with a pair of streamwise vortices. A common-flow down type streamwise vortex pair, which was generated by a pair of half-delta wings mounted on the wall, was introduced into the fully developed turbulent channel flow. The half-delta wings were as high as inner layer thickness of the channel flow. The mean velocity and Reynolds shear stress distributions were measured and some properties were obtained to find meanings of the vortex generator for management of turbulent channel flow. Convective motion of the secondary current is responsible for most of the streamwise momentum transfer toward the wall in the interaction between the vortices and the shear layer. In the velocity profile averaged over spanwise extent, velocity is accelerated below the vortex center and decelerated above the vortex center. Deformation of the mean velocity profile is remained over remarkable long downstream distance of 250 times wing height which corresponds to 50 times channel half-width H.

Design and sled testing of a high back booster seat prototype offering improved side impact protection

Current booster seats do not offer effective protection in side impact. Previous studies have suggested that the level of protection provided by boosters in side impact can be substantially improved through relatively minor design changes to booster seat geometry. Previous studies have also shown that booster seat performance can be significantly enhanced by rigidly anchoring booster seats to the vehicle structure. The aim of this study is to demonstrate how the level of side impact protection in booster seats can be increased through attention to booster seat geometry and booster seat anchorage. A high back booster seat prototype was designed and manufactured. It incorporates a rigid attachment, deep side wings, and a height adjustment system. It was then tested in side impact using a Hybrid III 6 year old dummy on a sled with a non-intruding side door structure. The improved design features of the prototype were then compared, in terms of the level of protection provided to the dummy, to the performance of two current booster seats available on the Australian market. Different upper side wings configurations were also tested. The prototype was also tested in frontal impact to verify that the level of protection had been maintained in that impact direction. Unlike current booster seat designs, the prototype succeeded in fully containing the dummy in all tests, therefore preventing contact with the side door structure. In 90 degree impacts, the prototype was found to reduce the HIC36 results by up two thirds when compared to the two current booster seats. The upper neck loads were also considerably reduced. While side wing height and depth was found to be an important feature in achieving these reductions in injury risk, side wing angle was found to have less of an effect. This study confirms that it is possible to offer significantly improved side impact protection in booster seats by using a rigid anchorage system, deep side wings and a height adjustment system.

Surgical anatomy of the feline sacroiliac joint for lag screw fixation of sacroiliac fracture-luxation

SummaryTwenty-eight feline pelves (56 hemipelves) were examined in order to identify the location for optimal sacroiliac screw placement in sacroiliac fracture-luxation repair. A drill hole was started on the median plane of the hemipelvis in the centre of the body of the first sacral segment until it penetrated the lateral cortex of the ilial wing, thus providing optimal drill hole placement. The position of the drill hole on the articular surface of the sacral wing and on the lateral surface of the ilial wing was measured. The distance of the drill hole from the cranial margin of the sacral wing was 51% of sacral wing length, just cranial to the crescent shaped hyaline cartilage. The distance from the dorsal margin was 47% of sacral wing height. The drill bit direction has to be adjusted to the cranio-caudal inclination (range 10° to 29°) and dorso-ventral inclination (range 2° to 25°) of the sacral wing. A notch in the cranial edge of the sacral wing was present, with variable position, in 34% of the specimens and is consequently not a useful landmark for sacroiliac screw placement. The drill hole on the lateral surface of the ilium was located in craniocaudal direction at a distance of 69% of sacral tuber length, measured from the cranial dorsal iliac spine. The dorso-ventral position of the drill hole was at a distance of 52% of ilial wing height measured from the sacral tuber. The ventral gluteal line, present in 93% of the cases, is a useful landmark to locate optimal screw hole position on the ilial wing.

Off-Surface Aerodynamic Measurements of a Wing in Ground Effect

The off-surface aerodynamic characteristics of a wing in ground effect are investigated using a number of methods including laser Doppler anemometry and particle image velocimetry. The study focuses on two aspects of the flow: turbulent wake and edge vortex. These features are closely associated with the behavior of the aerodynamic force in ground effect. The size of the wake increases in proximity to the ground. A downward shift of the path of the wake is also observed. Discrete vortex shedding is seen to occur behind the wing. As the wing height is reduced, separation occurred on the suction surface of the wing, and the spanwise vortex shedding is found to couple with a flapping motion of the wake in the transverse direction. An edge vortex is also observed off the edge of the end plate of the wing, which contributes to force enhancement and helps to define the force behavior in the force enhancement region. The rate of change in the downforce vs height curve is linked to the strength of the edge vortex. The vortex breakdown signals a slowdown in the force enhancement. When the maximum downforce height is reached, the edge vortex breaks down completely.

空力浮上形輸送システムの空力特性とその安定性に関する研究

New ground transport system, Ground Effect Transport System (GETS), which has potential for solving the green house problem of the earth by saving fuel to transport because the system is expected to have high lift-to-drag ratio, had been newly proposed, and fundamental investigations needed to develop such transport system has been conducted in university laboratory level. In the present study, some of the essential aerodynamic characteristics of an wing-in-ground effect of the GETS is investigated experimentally. Namely, effect of the tandem wing height from the ground and the wing interference are investigated. The results are compared with the numerical simulation results. It was shown that the effect of the interference of the wings could be ignored when the distance became more than 2.5 times the chord length of the wings. It was also found to be important that the boundary layer of the ground plate should be eliminated in the experimental study of such system that required very small gap between the wing and the ground plate.

A design method for scale-up of selective agglomeration plant for upgrading coal with respect to sulfur and mineral matter content

A theoretical model is described for using laboratory batch experimental data to design industrial plant for the upgrading of coal by selective agglomeration. The maximum velocity gradient and the real residence time are used as the two criteria in designing the stirred tanks that are the main components of the plant. The first criterion is determined as the product of impeller diameter and impeller rotation speed. The second criterion is the product of number of impeller wings, impeller wing height and number of parallel operating tanks, divided by the overall slurry flow rate. Formulae for required power and specific energy consumption are derived and recommended for optimization of the plant. As data are not available from large plants, calculations on hypothetical plants are provided to illustrate the use of this technique for scale-up.

Wind-tunnel investigation of wing-in-ground effects

Wing-in-Ground effects from a wind-tunnel study of a NACA 4415-profile wing model with an aspect ratio of 2.33 are described. The wing model contains a 20%-chord, full-span, adjustable flap and removable end and enter plates. Ground boards are used in the wind tunnel to simulate the ground. In this study, the ground effects are expressed as variations to the aerodynamic coefficients (lift and drag) and lift-to-drag ratio. The ground effects are described in terms of angle of attack, flap angle, wing height above ground and use and size of end and center plates.

Simulation of a delta wing with two jets in ground effect

Numerical simulations of the flow about a 60° delta planform wing, equipped with two thrust reverser jets, in ground effect are presented. These simulations are based on the solution of the three-dimensional thin-layer Navier-Stokes equations on a body-conforming, overset, multiple grid topology. An implicit, two-factor, numerical scheme with flux-splitting in the streamwise direction is used. The first set of simulations involves the validation of the numerical scheme by studying the impact of numerical parameters (e.g. grid refinement and dissipation levels) on the solution. The second set of simulations is performed to understand the effect of flow-field parameters (such as the height of the delta wing above the ground plane, the jet size, and the jet exit temperature) on the solution. Flow features such as jet deformation and ground vortex formation observed in experimental flow visualizations are captured. Comparisons with experimental data confirm the ability to simulate the loss of wing-borne lift, commonly referred to as “suck-down,” as the delta planform flies at slow speeds in close proximity to the ground. Detailed analysis of the numerical results has given insight into the structure of the ground vortex and the mechanisms of lift loss.

Mean flow and turbulence measurements in a half-delta wing vortex

A subsonic experimental study has been conducted to examine the mean and turbulent properties of a single longitudinal vortex generated by a half-delta wing. Measurements were made on fine cross-plane grids at seven streamwise locations using hot cross-wires. The evaluated streamwise vorticity contours indicated that the initially distorted vortex at a streamwise station equivalent to a half wing height became round by about three wing heights. In this initial "transition" region, where the vortex was still rolling-up, the peak vorticity dropped by about 50% following a X-1/2 decay. In this region, the generator wake remained distinct from the region of maximum vorticity, although the two regions were seen to slowly merge together. The Reynolds stress contours were also distorted initially with the maximum values occurring in the generator wake region, rather than in the vortex core, but these also decayed rapidly. Downstream of the transition region, the vortex appeared to reach an equilibrium state with the regions of maximum vorticity and turbulent kinetic energy coincident and the levels approximately constant with increasing streamwise distance. Comparison with previous data on vortices produced by double-branched generators further confirmed that the present vortex had achieved a fully developed state, and in a relatively short streamwise distance.

The Surgical Anatomy of the Canine Sacrum for Lag Screw Fixation of the Sacroiliac Joint

One hundred canine sacral bone specimens were examined to identify surgical landmarks that may improve screw placement in sacroiliac repair. A lateral view of the sacral wing was studied, as this structure is most easily identified in the dorsal approach used for sacroiliac repair. The height and length of each sacral wing were measured. Four other features of the canine sacrum were identified and measured in comparison with the sacral wing height and length. The cranial overlap of the sacral wing over the intervertebral space of L7‐S1 was found to have a mean of 14% of the length of the sacral wing. The ventral overlap of the sacral wing over the pelvic canal was found to be 21% of the height of the sacral wing. The ventral limit of the spinal canal (dorsal limit of the sacral body) was 45% of the sacral wing height. The first pelvic foramen was located at a mean distance of 64% of the sacral wing length and 20% of the sacral wing height. Using these four features, a composite view of the sacral wing is described to illustrate the area of the sacral body where screw placement is optimal.

A Simple Method of Measuring Landing and Take-Off Speed

T of the most difficult performance characteristics of aircraft to measure are the true landing and take-off speeds. The airplane airspeed indicator is not suited for obtaining these velocities because of the difficulty in calibrating the pitot-static head for position error at angles near the stall, particularly where the angle changes rapidly and also because the presence of the ground generally modifies any free flight calibration. At the present time, many photographic methods involving the use of high speed cameras taking up to 100 photographs per second are used to take pictures of the airplane as it lands on a runway marked off in known distances. The space-time curve is derived knowing the actual camera speed. The velocity of the airplane added to the measured wind velocity gives the landing speed. For accurate work, only electrically driven cameras are satisfactory as spring driven cameras almost always vary too greatly in speed, requiring involved calibration. This method naturally cannot be used with seaplanes. I t is generally unsatisfactory because the piloting technique is very difficult, inasmuch as the pilot must make a minimum speed spot-landing fairly close to the cameras. In some cases, the camera is mounted inside the airplane, taking pictures of the lines through a cabin window as the ship lands. The exact point of contact must be noted by a ground observer. The above are only two of a large number of camera methods of measuring speeds. All involve the use of a fairly large ground crew and none of the camera methods can be more accurate than the measurement of the wind velocity and the atmospheric pressure and temperature, which are used to correct the speeds to sea level air density. The air temperature must be carefully obtained outside the airplane at wing height in a shaded location away from ground radiation and direct sunlight. Computing the results of a camera test is a tedious task and the results are not immediately obtainable. The cost of such testing is very high. In order to obtain greater accuracy, simplicity, and ease of testing, the writer devised a very simple method of measuring velocities near the ground which eliminates all the objections to the camera system. A swiveling pitot-static head is located on the airplane away from slipstream effects and the boundary layer of any part of the ship. The head swivels about the spanwise axis of the airplane, and it may be located on the fuselage nose, above or beneath the wing or any such place regardless of position error due to local flow velocities. The pitot or total pressure lead only is used while the aircraft is in motion. I t is directly connected by a fairly large line (Vs in. inside diameter) to a verysensitive total pressure gage capable of measuring from 1.7 to 5.0 inches of water pressure above static pressure with the desired accuracy. At the instant of landing or taking off (as indicated by a signal light connected to each landing gear shock strut), the total pressure is read on the gage. When the airplane comes to a stop after landing, it is taxied back to the approximate landing or take-off point, headed into the wind and the gage switched over to a line connected with the static openings in the swiveling pitot-static head or opened to cockpit pressure. A second reading is taken on the pressure gage. If the runway has no slope, the second reading may be taken any place on the field. The difference between the pressure on landing and when stopped gives the true impact pressure at landing speed or