Optimal lift force on vesicles near a compressible substrate
NASA Astrophysics Data System (ADS)
Beaucourt, J.; Biben, T.; Misbah, C.
2004-08-01
The dynamics of vesicles near a compressible substrate mimicking the glycocalyx layer of the internal part of blood vessels reveals the existence of an optimal lift force due to an elasto-hydrodynamic coupling between the counter flow and the deformation of the wall. An estimation of the order of magnitude of the optimal elastic modulus reveals that it lies within the physiological range, which may have important consequences for the dynamic of blood cells (leucocytes or red blood cells).
ERIC Educational Resources Information Center
Weltner, Klaus
1990-01-01
Describes some experiments showing both qualitatively and quantitatively that aerodynamic lift is a reaction force. Demonstrates reaction forces caused by the acceleration of an airstream and the deflection of an airstream. Provides pictures of demonstration apparatus and mathematical expressions. (YP)
Force-controlled lifting of molecular wires
NASA Astrophysics Data System (ADS)
Fournier, N.; Wagner, C.; Weiss, C.; Temirov, R.; Tautz, F. S.
2011-07-01
Lifting a single molecular wire off the surface with a combined frequency-modulated atomic force and tunneling microscope it is possible to monitor the evolution of both the wire configuration and the contacts simultaneously with the transport conductance experiment. In particular, critical points where individual bonds to the surface are broken and instabilities where the wire is prone to change its contact configuration can be identified in the force gradient and dissipation responses of the junction. This additional mechanical information can be used to unambiguously determine the conductance of a true molecular wire, that is, of a molecule that is contacted via a pointlike “crocodile clip” to each of the electrodes but is otherwise free.
Microfluidic particle sorting utilizing inertial lift force.
Nieuwstadt, Harm A; Seda, Robinson; Li, David S; Fowlkes, J Brian; Bull, Joseph L
2011-02-01
A simple passive microfluidic device that continuously separates microparticles is presented. Its development is motivated by the need for specific size micro perfluorocarbon (PFC) droplets to be used for a novel gas embolotherapy method. The device consists of a rectangular channel in which inertial lift forces are utilized to separate particles in lateral distance. At the entrance of the channel, particles are introduced at the center by focusing the flow from a center channel with flow from two side channels. Downstream, large particles will occupy a lateral equilibrium position in shorter axial distance than small particles. At the exit of the channel, flow containing large particles is separated from flow containing small particles. It is shown that 10.2-μm diameter microspheres can be separated from 3.0-μm diameter microspheres with a separation efficiency of 69-78% and a throughput in the order of 2 ·10⁴ particles per minute. Computational Fluid Dynamics (CFD) calculations were done to calculate flow fields and verify theoretical particle trajectories. Theory underlying this research shows that higher separation efficiencies for very specific diameter cut-off are possible. This microfluidic channel design has a simple structure and can operate without external forces which makes it feasible for lab-on-a-chip (LOC) applications.
Anticipatory scaling of grip forces when lifting objects of everyday life.
Hermsdörfer, Joachim; Li, Yong; Randerath, Jennifer; Goldenberg, Georg; Eidenmüller, Sandra
2011-07-01
The ability to predict and anticipate the mechanical demands of the environment promotes smooth and skillful motor actions. Thus, the finger forces produced to grasp and lift an object are scaled to the physical properties such as weight. While grip force scaling is well established for neutral objects, only few studies analyzed objects known from daily routine and none studied grip forces. In the present study, eleven healthy subjects each lifted twelve objects of everyday life that encompassed a wide range of weights. The finger pads were covered with force sensors that enabled the measurement of grip force. A scale registered load forces. In a control experiment, the objects were wrapped into paper to prevent recognition by the subjects. Data from the first lift of each object confirmed that object weight was anticipated by adequately scaled forces. The maximum grip force rate during the force increase phase emerged as the most reliable measure to verify that weight was actually predicted and to characterize the precision of this prediction, while other force measures were scaled to object weight also when object identity was not known. Variability and linearity of the grip force-weight relationship improved for time points reached after liftoff, suggesting that sensory information refined the force adjustment. The same mechanism seemed to be involved with unrecognizable objects, though a lower precision was reached. Repeated lifting of the same object within a second and third presentation block did not improve the precision of the grip force scaling. Either practice was too variable or the motor system does not prioritize the optimization of the internal representation when objects are highly familiar.
Hattori, Y; Ono, Y; Shimaoka, M; Hiruta, S; Kamijima, M; Shibata, E; Ichihara, G; Ando, S; Villaneuva, M B; Takeuchi, Y
1996-06-01
A laboratory study was undertaken to determine the postural and physical characteristics and subjective stress during dynamic lifting of a usual load (10 kg) compared with during isometric lifting. The authors also aimed to clarify the effects of asymmetric lifting on these parameters. The subjects were thirteen male college students. They were asked to lift a box weighing 10 kg. They performed sixteen different lifting tasks from the floor to a height of 71 cm, involving a combination of three independent factors: two lifting modes (isometric lifting and dynamic lifting), four lifting angles in relation to the sagittal plane (sagittal plane, right 45 degree, right 90 degree and left 90 degree planes) and two lifting postures (squat and stoop). For each lifting task, strengths or forces and ground reaction forces were measured. At the end of each task, the authors asked the subjects to rate their perceived exertion (RPE) during lifting at ten sites of the body. Angle factor had a significant effect on isometric strengths and dynamic peak forces. Isometric strengths during the maximum 3 s were highest in lifting in the right 45 degree plane, followed by that in the sagittal plane, while those in the right 90 degree and left 90 degree planes were the lowest. However, peak forces in dynamic lifting were the highest in the lifting in the sagittal plane, followed by that in the right 45 degree plane, while those in the right 90 degree and left 90 degree planes were the lowest. Postural factor had a significant effect on height at peak force, which is higher in squat lifting than in stoop lifting. RPEs for the left arm, the backs and the right whole body in isometric lifting were significantly higher than in dynamic lifting of 10 kg. There were remarkably high RPEs for the ipsilateral thigh to the box in right 90 degree and left 90 degree planes during both isometric and dynamic liftings. Locations of the resultant force consisting of three component forces on the force
Biomechanical simulation of manual lifting using spacetime optimization.
Chang, C C; Brown, D R; Bloswick, D S; Hsiang, S M
2001-04-01
Previous optimization techniques for the prediction of lifting motion patterns often require a change in either the number of variables or the order of the mathematical functions used to express the angular displacement of selected joints in response to change in variant conditions. The resolution of predicted results can also be seriously constrained by the number of variables used. These restrictions may often limit the applicability of these methodologies. In this paper, we proposed a new methodology for generating the optimum motion patterns for para-sagittal lifting tasks. A detailed description of this methodology is introduced. An example of an analysis using this methodology is presented. The computer program generated lifting motion patterns with a reduction of the overall objective function values. The actual versus predicted lifting motion patterns are compared. Using this method, constraints can be added anywhere within the lifting cycle without the need of rewriting the whole program. These features provide for a more flexible and efficient prediction of the lifting motion.
Oscillatory Counter-Centrifugation: Effects of History and Lift Forces
NASA Astrophysics Data System (ADS)
Nadim, Ali
2014-11-01
This work is co-authored with my doctoral student Shujing Xu and is dedicated to the memory of my doctoral advisor Howard Brenner who enjoyed thought experiments related to rotating systems. Oscillatory Counter-Centrifugation refers to our theoretical discovery that within a liquid-filled container that rotates in an oscillatory manner about a fixed axis as a rigid body, a suspended particle can be made to migrate on average in the direction opposite to that of ordinary centrifugation. That is, a heavy (or light) particle can move toward (or away from) the rotation axis, when the frequency of oscillations is high enough. In this work we analyze the effects of the Basset history force and the Saffman lift force on particle trajectories and find that the counter-centrifugation phenomenon persists even when these forces are active.
Optimization-based Dynamic Human Lifting Prediction
2008-06-01
Anith Mathai, Steve Beck,Timothy Marler , Jingzhou Yang, Jasbir S. Arora, Karim Abdel-Malek Virtual Soldier Research Program, Center for Computer Aided...Rahmatalla, S., Kim, J., Marler , T., Beck, S., Yang, J., busek, J., Arora, J.S., and Abdel-Malek, K. Optimization-based dynamic human walking prediction
Multiple element airfoils optimized for maximum lift coefficient.
NASA Technical Reports Server (NTRS)
Ormsbee, A. I.; Chen, A. W.
1972-01-01
Optimum airfoils in the sense of maximum lift coefficient are obtained for incompressible fluid flow at large Reynolds number. The maximum lift coefficient is achieved by requiring that the turbulent skin friction be zero in the pressure rise region on the airfoil upper surface. Under this constraint, the pressure distribution is optimized. The optimum pressure distribution is a function of Reynolds number and the trailing edge velocity. Geometries of those airfoils which will generate these optimum pressure distributions are obtained using a direct-iterative method which is developed in this study. This method can be used to design airfoils consisting of any number of elements. Numerical examples of one- and two-element airfoils are given. The maximum lift coefficients obtained range from 2 to 2.5.
The magnitude of lift forces acting on drops and bubbles in liquids flowing inside microchannels.
Stan, Claudiu A; Ellerbee, Audrey K; Guglielmini, Laura; Stone, Howard A; Whitesides, George M
2013-02-07
Hydrodynamic lift forces offer a convenient way to manipulate particles in microfluidic applications, but there is little quantitative information on how non-inertial lift mechanisms act and compete with each other in the confined space of microfluidic channels. This paper reports measurements of lift forces on nearly spherical drops and bubbles, with diameters from one quarter to one half of the width of the channel, flowing in microfluidic channels, under flow conditions characterized by particle capillary numbers Ca(P) = 0.0003-0.3 and particle Reynolds numbers Re(P) = 0.0001-0.1. For Ca(P) < 0.01 and Re(P) < 0.01 the measured lift forces were much larger than predictions of deformation-induced and inertial lift forces found in the literature, probably due to physicochemical hydrodynamic effects at the interface of drops and bubbles, such as the presence of surfactants. The measured forces could be fit with good accuracy using an empirical formula given herein. The empirical formula describes the power-law dependence of the lift force on hydrodynamic parameters (velocity and viscosity of the carrier phase; sizes of channel and drop or bubble), and includes a numerical lift coefficient that depends on the fluids used. The empirical formula using an average lift coefficient of ~500 predicted, within one order of magnitude, all lift force measurements in channels with cross-sectional dimensions below 1 mm.
The lift forces acting on a submarine composite pipeline in a wave-current coexisting field
Li, Y.C.; Zhang, N.C.
1994-12-31
The composite pipeline is defined as a main big pipe composed with one or several small pipes. The flow behavior around a submarine composite pipeline is more complicated than that around a single submarine pipeline. A series model test of composite pipelines in a wave-current coexisting field was conducted by the authors. Both in-line and lift forces were measured, and the resultant forces are also analyzed. The results of lift forces and resultant forces are reported in this paper. It is found that the lift force coefficients for composite pipelines are well related to the KC number. The lift force coefficients in an irregular wave-current coexisting field are smaller than those in regular wave-current coexisting field. The frequency of lift force is usually the twice or higher than the wave frequency. It is indicated by the authors` test that the resultant forces are larger than in-line forces (horizontal forces) about 10 to 20 percent. The effect of water depth was analyzed. Finally, the relationship between lift force coefficient C{sub l} and KC number, the statistical characteristics of lift and resultant forces, are given in this paper, which may be useful for practical engineering application.
The control of flight force by a flapping wing: lift and drag production.
Sane, S P; Dickinson, M H
2001-08-01
We used a dynamically scaled mechanical model of the fruit fly Drosophila melanogaster to study how changes in wing kinematics influence the production of unsteady aerodynamic forces in insect flight. We examined 191 separate sets of kinematic patterns that differed with respect to stroke amplitude, angle of attack, flip timing, flip duration and the shape and magnitude of stroke deviation. Instantaneous aerodynamic forces were measured using a two-dimensional force sensor mounted at the base of the wing. The influence of unsteady rotational effects was assessed by comparing the time course of measured forces with that of corresponding translational quasi-steady estimates. For each pattern, we also calculated mean stroke-averaged values of the force coefficients and an estimate of profile power. The results of this analysis may be divided into four main points. (i) For a short, symmetrical wing flip, mean lift was optimized by a stroke amplitude of 180 degrees and an angle of attack of 50 degrees. At all stroke amplitudes, mean drag increased monotonically with increasing angle of attack. Translational quasi-steady predictions better matched the measured values at high stroke amplitude than at low stroke amplitude. This discrepancy was due to the increasing importance of rotational mechanisms in kinematic patterns with low stroke amplitude. (ii) For a 180 degrees stroke amplitude and a 45 degrees angle of attack, lift was maximized by short-duration flips occurring just slightly in advance of stroke reversal. Symmetrical rotations produced similarly high performance. Wing rotation that occurred after stroke reversal, however, produced very low mean lift. (iii) The production of aerodynamic forces was sensitive to changes in the magnitude of the wing's deviation from the mean stroke plane (stroke deviation) as well as to the actual shape of the wing tip trajectory. However, in all examples, stroke deviation lowered aerodynamic performance relative to the no
Measuring lifting forces in rock climbing: effect of hold size and fingertip structure.
Bourne, Roger; Halaki, Mark; Vanwanseele, Benedicte; Clarke, Jillian
2011-02-01
This study investigates the hypothesis that shallow edge lifting force in high-level rock climbers is more strongly related to fingertip soft tissue anatomy than to absolute strength or strength to body mass ratio. Fifteen experienced climbers performed repeated maximal single hand lifting exercises on rectangular sandstone edges of depth 2.8, 4.3, 5.8, 7.3, and 12.5 mm while standing on a force measurement platform. Fingertip soft tissue dimensions were assessed by ultrasound imaging. Shallow edge (2.8 and 4.3 mm) lifting force, in newtons or body mass normalized, was uncorrelated with deep edge (12.5 mm) lifting force (r < .1). There was a positive correlation (r = .65, p < .05) between lifting force in newtons at 2.8 mm edge depth and tip of bone to tip of finger pulp measurement (r < .37 at other edge depths). The results confirm the common perception that maximum lifting force on a deep edge ("strength") does not predict maximum force production on very shallow edges. It is suggested that increased fingertip pulp dimension or plasticity may enable increased deformation of the fingertip, increasing the skin to rock contact area on very shallow edges, and thus increase the limit of force production. The study also confirmed previous assumptions of left/right force symmetry in climbers.
Measurements of Shear Lift Force on a Bubble in Channel Flow in Microgravity
NASA Technical Reports Server (NTRS)
Nahra, Henry K.; Motil, Brian J.; Skor, Mark
2003-01-01
Under microgravity conditions, the shear lift force acting on bubbles, droplets or solid particles in multiphase flows becomes important because under normal gravity, this hydrodynamic force is masked by buoyancy. This force plays an important role in furnishing the detachment process of bubbles in a setting where a bubble suspension is needed in microgravity. In this work, measurements of the shear lift force acting on a bubble in channel flow are performed. The shear lift force is deduced from the bubble kinematics using scaling and then compared with predictions from models in literature that address different asymptotic and numerical solutions. Basic trajectory calculations are then performed and the results are compared with experimental data of position of the bubble in the channel. A direct comparison of the lateral velocity of the bubbles is also made with the lateral velocity prediction from investigators, whose work addressed the shear lift on a sphere in different two-dimensional shear flows including Poiseuille flow.
SALEHI SAHL ABADI, Ali; NASL SARAJI, Gebraeil; MAZLOUMI, Adel; ZERAATI, Hojjat; HADIAN, Mohammad Reza; JAFARI, Amir Homayoun
2016-01-01
Background: Low back pain caused by work, ranked the second after cardiovascular diseases, are among the most common reasons of patients’ referral to the physicians in Iran. This study aimed to determine the changes in back compressive force when measuring maximum acceptable weight of lift in Iranian male students. Methods: This experimental study was conducted in 2015 on 15 young male students were recruited from Tehran University of Medical Science. Each participant performed 18 different lifting tasks involving three lifting frequencies, with three lifting heights, and two box sizes. Each set of experiments was conducted during the 20 min work period using free-style lifting technique. The back compressive force evaluated with hand-calculation back compressive force method. Finally, Pearson correlation test, analysis of variance (ANOVA) and t-test were used for data analysis. Results: The mean of back compressive force (BCF) for the small and large boxes at a frequency of 1lift/min at heights of F - K height, were 1001.02 (±86.74), 1210.57 (±93.77) Ib, respectively. There was a significant difference between mean BCF in terms of frequencies of lifts (P=0.02). The result revealed significant difference between frequencies of 1 lift/min and 6.67 lift/min (P=0.01). There was a significant difference between mean BCF in terms of the sizes of the two boxes (P=0.001). There was a significant relationship between the BCF and maximum acceptable weight of lift in all test conditions (P=0.001). Conclusion: BCF is affected by box size, lifting frequency and weight of load. PMID:27957465
High-Lift Optimization Design Using Neural Networks on a Multi-Element Airfoil
NASA Technical Reports Server (NTRS)
Greenman, Roxana M.; Roth, Karlin R.; Smith, Charles A. (Technical Monitor)
1998-01-01
The high-lift performance of a multi-element airfoil was optimized by using neural-net predictions that were trained using a computational data set. The numerical data was generated using a two-dimensional, incompressible, Navier-Stokes algorithm with the Spalart-Allmaras turbulence model. Because it is difficult to predict maximum lift for high-lift systems, an empirically-based maximum lift criteria was used in this study to determine both the maximum lift and the angle at which it occurs. Multiple input, single output networks were trained using the NASA Ames variation of the Levenberg-Marquardt algorithm for each of the aerodynamic coefficients (lift, drag, and moment). The artificial neural networks were integrated with a gradient-based optimizer. Using independent numerical simulations and experimental data for this high-lift configuration, it was shown that this design process successfully optimized flap deflection, gap, overlap, and angle of attack to maximize lift. Once the neural networks were trained and integrated with the optimizer, minimal additional computer resources were required to perform optimization runs with different initial conditions and parameters. Applying the neural networks within the high-lift rigging optimization process reduced the amount of computational time and resources by 83% compared with traditional gradient-based optimization procedures for multiple optimization runs.
Mechanism of the lift force acting on a levitating drop over a moving surface
NASA Astrophysics Data System (ADS)
Saito, Masafumi; Tagawa, Yoshiyuki; Kameda, Masaharu
2014-11-01
The purpose of this study is to understand the levitation mechanism of a drop over a moving surface. In our experiment we softly deposit a silicon-oil drop onto the inner wall of a rotating hollow cylinder. With sufficiently large velocity of the wall, the drop steadily levitates. The drop reaches a stable angular position in the cylinder, where the drag and lift balance the weight of the drop. The lift force, which is vital for the levitation, is generated inside a thin air film existing between the drop and the wall. Here three-dimensional shape of the air film plays a crucial role for the magnitude of the lift force. Note that, although the shapes of some levitating drops had been reported, the lift estimated from the shape had not been validated. Using interferometric technique, we measure the three-dimensional shape of the air film under the drop. We then calculate the lift by applying the lubrication theory. This lift is compared with that estimated from the angular position. Both lifts show a fair agreement. In addition, we investigate the shapes of the air film under drops with various sizes, viscosities and wall velocities. We discuss effects of these parameters on the shape and the lift. JSPS KAKENHI Grant Number 26709007.
NASA Technical Reports Server (NTRS)
Segenreich, S. A.; Mcintosh, S. C., Jr.
1975-01-01
A rigorous optimality criterion is derived and a hybrid weight-reduction algorithm developed for the weight minimization of lifting surfaces with a constraint on flutter speed. The weight-reduction algorithm incorporates a simple recursion formula derived from the optimality criterion. Monotonic weight reduction is accomplished by dynamically adjusting a parameter in the recursion formula so as to achieve a predetermined weight decrease. The algorithm thus combines the simplicity of optimality-criterion methods with the convergence characteristics of mathematical-programming methods. The imposition of the flutter constraint is simplified by forcing to zero the imaginary part of the flutter eigenvalue, with the airspeed fixed. Four examples are discussed. The results suggest that significant improvements in efficiency are possible, in comparison with techniques based purely on mathematical programming.
Optimal Force Generation with Fluid-Structure Interactions
NASA Astrophysics Data System (ADS)
Peng, Diing-wen
Typical computational and experimental methods are unsuitable for studying large scale optimization problems involving complex fluid structure interactions, primarily due to their time-consuming nature. A novel experimental approach is proposed here that provides a high-fidelity and efficient alternative to discover optimal parameters arising from the passive interaction between structural elasticity and fluid dynamic forces. This approach utilizes motors, force transducers, and active controllers to emulate the effects of elasticity, eliminating the physical need to replace structural components in the experiment. A clustering genetic algorithm is then used to tune the structural parameters to achieve desired optimality conditions, resulting in approximated global optimal regions within the search bound. A prototype fluid-structure interaction experiment inspired by the lift generation of flapping wing insects is presented to highlight the capabilities of this approach. The experiment aims to maximize the average lift on a sinusoidally translating plate, by optimizing the damping ratio and natural frequency of the plate's elastic pitching dynamics. Reynolds number, chord length, and stroke length are varied between optimizations to explore their relationships to the optimal structural parameters. The results reveal that only limited ranges of stroke lengths are conducive to lift generation; there also exists consistent trends between optimal stroke length, natural frequency, and damping ratio. The measured lift, pitching angle, and torque on the plate for optimal scenarios exhibit the same frequency as the translation frequency, and the phase angles of the optimal structural parameters at this frequency are found to be independent of the stroke length. This critical phase can be then characterized by a linear function of the chord length and Reynolds number. Particle image velocimetry measurements are acquired for the kinematics generated with optimal and
Chirality-specific lift forces of helix under shear flows: Helix perpendicular to shear plane.
Zhang, Qi-Yi
2017-02-01
Chiral objects in shear flow experience a chirality-specific lift force. Shear flows past helices in a low Reynolds number regime were studied using slender-body theory. The chirality-specific lift forces in the vorticity direction experienced by helices are dominated by a set of helix geometry parameters: helix radius, pitch length, number of turns, and helix phase angle. Its analytical formula is given. The chirality-specific forces are the physical reasons for the chiral separation of helices in shear flow. Our results are well supported by the latest experimental observations.
Optimization of the lithographic performance for lift-off processing
NASA Astrophysics Data System (ADS)
Yin, Wenyan; Fillmore, Ward; Dempsey, Kevin J.
1999-06-01
Shipley MICROPOSIT LOL lift-off technology exploits a develop rate difference in a resist, LOL1000 bi-layer system to generate retrograde profiles. This is an enabling technology for 'additive' processing. Deposition follows lithography and the resist is then 'lifted off' to generate a patterned layer.
Two-Dimensional High-Lift Aerodynamic Optimization Using Neural Networks
NASA Technical Reports Server (NTRS)
Greenman, Roxana M.
1998-01-01
The high-lift performance of a multi-element airfoil was optimized by using neural-net predictions that were trained using a computational data set. The numerical data was generated using a two-dimensional, incompressible, Navier-Stokes algorithm with the Spalart-Allmaras turbulence model. Because it is difficult to predict maximum lift for high-lift systems, an empirically-based maximum lift criteria was used in this study to determine both the maximum lift and the angle at which it occurs. The 'pressure difference rule,' which states that the maximum lift condition corresponds to a certain pressure difference between the peak suction pressure and the pressure at the trailing edge of the element, was applied and verified with experimental observations for this configuration. Multiple input, single output networks were trained using the NASA Ames variation of the Levenberg-Marquardt algorithm for each of the aerodynamic coefficients (lift, drag and moment). The artificial neural networks were integrated with a gradient-based optimizer. Using independent numerical simulations and experimental data for this high-lift configuration, it was shown that this design process successfully optimized flap deflection, gap, overlap, and angle of attack to maximize lift. Once the neural nets were trained and integrated with the optimizer, minimal additional computer resources were required to perform optimization runs with different initial conditions and parameters. Applying the neural networks within the high-lift rigging optimization process reduced the amount of computational time and resources by 44% compared with traditional gradient-based optimization procedures for multiple optimization runs.
Schenk, Peter; Klipstein, Andreas; Spillmann, Susanne; Strøyer, Jesper; Laubli, Thomas
2006-01-01
Evaluation of lifting capacity is widely used as a reliable instrument in order to evaluate maximal and safe lifting capacity. This is of importance in regard to planning rehabilitation programs and determining working ability. The aim of this study was to investigate the influence of basic functions on the lifting capacity measured by the progressive isoinertial lifting evaluation (PILE) and the functional capacity evaluation (FCE) tests in a lower (floor to waist) and an upper (waist to shoulder) setting and compare the two test constructs. Seventy-four female subjects without acute low back pain underwent an examination of their lifting capacities and the following basic functions: (1) strength and endurance of trunk muscles, (2) cardiovascular endurance, (3) trunk mobility and (4) coordination ability. A linear regression model was used to predict lifting capacity by means of the above-mentioned basic functions, where the F statistics of the variables had to be significant at the 0.05 level to remain in the model. Maximal force in flexion showed significant influence on the lifting capacity in both the PILE and the FCE in the lower, as well as in the upper, lifting task. Furthermore, there was a significant influence of cardiovascular endurance on the lower PILE and also of endurance in trunk flexion on the lower FCE. Additional inclusion of individual factors (age, height, weight, body mass index) into the regression model showed a highly significant association between body height and all lifting tasks. The r (2) of the original model used was 0.19/0.18 in the lower/upper FCE and 0.35/0.26 in the lower/upper PILE. The model r (2) increased after inclusion of these individual factors to between 0.3 and 0.4. The fact that only a limited part of the variance in the lifting capacities can be explained by the basic functions analyzed in this study confirms the assumption that factors not related to the basic functions studied, such as lifting technique and motor
Continuum theories for fluid-particle flows: Some aspects of lift forces and turbulence
NASA Technical Reports Server (NTRS)
Mctigue, David F.; Givler, Richard C.; Nunziato, Jace W.
1988-01-01
A general framework is outlined for the modeling of fluid particle flows. The momentum exchange between the constituents embodies both lift and drag forces, constitutive equations for which can be made explicit with reference to known single particle analysis. Relevant results for lift are reviewed, and invariant representations are posed. The fluid and particle velocities and the particle volume fraction are then decomposed into mean and fluctuating parts to characterize turbulent motions, and the equations of motion are averaged. In addition to the Reynolds stresses, further correlations between concentration and velocity fluctuations appear. These can be identified with turbulent transport processes such as eddy diffusion of the particles. When the drag force is dominant, the classical convection dispersion model for turbulent transport of particles is recovered. When other interaction forces enter, particle segregation effects can arise. This is illustrated qualitatively by consideration of turbulent channel flow with lift effects included.
Lift vs. drag based mechanisms for vertical force production in the smallest flying insects.
Jones, S K; Laurenza, R; Hedrick, T L; Griffith, B E; Miller, L A
2015-11-07
We used computational fluid dynamics to determine whether lift- or drag-based mechanisms generate the most vertical force in the flight of the smallest insects. These insects fly at Re on the order of 4-60 where viscous effects are significant. Detailed quantitative data on the wing kinematics of the smallest insects is not available, and as a result both drag- and lift-based strategies have been suggested as the mechanisms by which these insects stay aloft. We used the immersed boundary method to solve the fully-coupled fluid-structure interaction problem of a flexible wing immersed in a two-dimensional viscous fluid to compare three idealized hovering kinematics: a drag-based stroke in the vertical plane, a lift-based stroke in the horizontal plane, and a hybrid stroke on a tilted plane. Our results suggest that at higher Re, a lift-based strategy produces more vertical force than a drag-based strategy. At the Re pertinent to small insect hovering, however, there is little difference in performance between the two strategies. A drag-based mechanism of flight could produce more vertical force than a lift-based mechanism for insects at Re<5; however, we are unaware of active fliers at this scale.
Lift force on an asymmetrical obstacle immersed in a dilute granular flow.
Potiguar, Fabricio Q
2011-12-01
This paper investigates the lift force exerted on an elliptical obstacle immersed in a granular flow through analytical calculations and computer simulations. The results are shown as a function of the obstacle size, orientation with respect to the flow direction (tilt angle), the restitution coefficient and ellipse eccentricity. The theoretical argument, based on the force exerted on the obstacle due to inelastic, frictionless collisions of a very dilute flow, captures the qualitative features of the lift, but fails to reproduce the data quantitatively. The reason behind this disagreement is that the dilute flow assumption on which this argument is built breaks down as a granular shock wave forms in front of the obstacle. More specifically, the shock wave changes the grains impact velocity at the obstacle, decreasing the overall net lift obtained from a very dilute flow.
Weight Lift Capabilities of Air Force Basic Trainees
1983-05-01
month period of data collection. The 63 male Flights were selected at random during the same period. The age range for enlistment in the Air Force is...17 to 35 years. The age range for male subjects in this study was from 17 to 33 years with a mean of 19.75. More than 90 percent of the males were in...the 17 to 22 age group. The older subjects were entering the Air National Guard or the Air Force Reserves. The age range for the female subjects was
NASA Astrophysics Data System (ADS)
Gorchakov, G. I.; Karpov, A. V.; Kopeikin, V. M.; Sokolov, A. V.; Buntov, D. V.
2016-03-01
Quasi-horizontal trajectories of salting sand grains were found using high-speed video-recording in the desertified territory of the Astrakhan region. The sizes and displacement velocities of the saltating sand grains were determined. A piecewise logarithmic approximation of the wind profile in a quasi-stationary wind-sand flow is suggested, which is consistent with the data of observations and modeling. It was established that, in the regime of stationary saltation, the wind profile in the lower saltation layer of the wind-sand flow depends only slightly on the wind profile variations in the upper saltation layer. The vertical profiles of the horizontal wind component gradient in a quasi-stationary wind-sand flow were calculated and plotted. It was shown using high-speed video recording of the trajectory of a sand grain with an approximate diameter of 95 μm that the weightlessness condition in the desertified territory of the Astrakhan region in a stationary wind-sand flow is satisfied at a height of approximately 0.15 mm. The electric parameters of a wind-sand flow, which can provide for compensation of the force of gravity by the electric force, were estimated. In particular, if the specific charge of a sand grain is 100 μC/kg, the force of gravity applied to the sand grain can be compensated by the electric force if the vertical component of the electric field in a wind-sand flow reaches approximately 100 kV/m. It was shown that the quasi-horizontal transport of sand grains in the lower millimeter saltation layer observed in the desertified territory can be explained by the joint action of the aerodynamic drag, the force of gravity, the Saffman force, the lift force, and the electric force.
Measurement of the Shear Lift Force on a Bubble in a Channel Flow
NASA Technical Reports Server (NTRS)
Nahra, Henry K.; Motil, Brian; Skor, Mark
2005-01-01
Two-phase flow systems play vital roles in the design of some current and anticipated space applications of two-phase systems which include: thermal management systems, transfer line flow in cryogenic storage, space nuclear power facilities, design and operation of thermal bus, life support systems, propulsion systems, In Situ Resource Utilization (ISRU), and space processes for pharmaceutical applications. The design of two-phase flow systems for space applications requires a clear knowledge of the behaviors of the dispersed phase (bubble), its interaction with the continuous phase (liquid) and its effect on heat and mass transfer processes, The need to understand the bubble generation process arises from the fact that for all space applications, the size and distribution of bubbles are extremely crucial for heat and mass transfer control. One important force in two-phase flow systems is the lift force on a bubble or particle in a liquid shear flow. The shear lift is usually overwhelmed by buoyancy in normal gravity, but it becomes an important force in reduced gravity. Since the liquid flow is usually sheared because of the confining wall, the trajectories of bubbles and particles injected into the liquid flow are affected by the shear lift in reduced gravity. A series of experiments are performed to investigate the lift force on a bubble in a liquid shear flow and its effect on the detachment of a bubble from a wall under low gravity conditions. Experiments are executed in a Poiseuille flow in a channel. An air-water system is used in these experiments that are performed in the 2.2 second drop tower. A bubble is injected into the shear flow from a small injector and the shear lift is measured while the bubble is held stationary relative to the fluid. The trajectory of the bubble prior, during and after its detachment from the injector is investigated. The measured shear lift force is calculated from the trajectory of the bubble at the detachment point. These
Impact of Airfoils on Aerodynamic Optimization of Heavy Lift Rotorcraft
2006-01-01
Modeling Capability with a Conceptual Rotorcraft Sizing Code,” American Helicopter Society Vertical Lift Aircraft Design Conference, San Francisco...American Helicopter Society International, Inc. All rights reserved. Introduction A new generation of very large, fast rotorcraft is being studied to...Ref. 4). Other codes, including NASTRAN and HeliFoil, were used for subsystem analyses. Reference 1 discusses the integration of the various
Numerical study of lift augmentation in massively separated turbulent flows with forcing
NASA Astrophysics Data System (ADS)
Denny, Andrew Gregory
At high angles of attack the flow over any lifting body experiences massive separation. The resulting shear layers naturally tend to roll up into large vortical structures. The presence and motion of these structures has a significant impact on the continuing flowfield development. By applying an artificial forcing to the shedding shear layer the rollup can be intensified or reduced, and the entire vorticity field may be altered. Control of these vortical structures by forcing to enhance lift has been the goal of numerous investigations, and some progress has been made in understanding how an unsteady forcing can be used to advantage. This study describes work done in determining the effectiveness of using computational simulations to model massively separated, turbulent unsteady flowfields subject to small-amplitude mechanical forcing. Algorithm development and validation highlight certain concerns that arise in the modeling of such unsteady flowfields using the Reynolds-Averaged Navier-Stokes equations, and questions of grid density, numerical diffusion, timestep size, and turbulence modeling are addressed with a suite of sample calculations. Simulation of flowfields undergoing mechanical forcing by flap is accomplished using an overset grid methodology with the flow solver. Excellent agreement is demonstrated for flow over a NACA 63sb3-018 airfoil with a small flap placed near the leading edge separation point. Computed values of the unforced lift and drag coefficients agree with given experimental values to less than 2%. Forcing frequencies for the experimental configuration were in the range of global shedding frequency, and the maximum variation of the aerodynamic coefficients was seen when the forcing frequency was equal to the shedding frequency. Excellent agreement with experiment is also found for the cases involving forcing, and the data is used to explain the effect of forcing in terms of a global receptivity mechanism.
Optimal control of lift/drag ratios on a rotating cylinder
NASA Technical Reports Server (NTRS)
Ou, Yuh-Roung; Burns, John A.
1992-01-01
We present the numerical solution to a problem of maximizing the lift to drag ratio by rotating a circular cylinder in a two-dimensional viscous incompressible flow. This problem is viewed as a test case for the newly developing theoretical and computational methods for control of fluid dynamic systems. We show that the time averaged lift to drag ratio for a fixed finite-time interval achieves its maximum value at an optimal rotation rate that depends on the time interval.
Formal optimization of hovering performance using free wake lifting surface theory
NASA Technical Reports Server (NTRS)
Chung, S. Y.
1986-01-01
Free wake techniques for performance prediction and optimization of hovering rotor are discussed. The influence functions due to vortex ring, vortex cylinder, and source or vortex sheets are presented. The vortex core sizes of rotor wake vortices are calculated and their importance is discussed. Lifting body theory for finite thickness body is developed for pressure calculation, and hence performance prediction of hovering rotors. Numerical optimization technique based on free wake lifting line theory is presented and discussed. It is demonstrated that formal optimization can be used with the implicit and nonlinear objective or cost function such as the performance of hovering rotors as used in this report.
Experimental and numerical research of lift force produced by Coandă effect
NASA Astrophysics Data System (ADS)
Constantinescu, S. G.; Niculescu, M. L.
2013-10-01
The paper presents research results of aerodynamics of Coandă airfoil, that is a key element of drones with jet propulsion. The Coandă propulsion allows drones to monitor quickly the large areas in emergencies: forest fires, earthquakes, meteor attacks and so on. The aim of this work consists in establishment of geometric and aerodynamic parameters at which, the lift force produced by Coandă airfoil is maximal.
Eidenmüller, S; Randerath, J; Goldenberg, G; Li, Y; Hermsdörfer, J
2014-08-01
The scaling of our finger forces according to the properties of manipulated objects is an elementary prerequisite of skilled motor behavior. Lesions of the motor-dominant left brain may impair several aspects of motor planning. For example, limb-apraxia, a tool-use disorder after left brain damage is thought to be caused by deficient recall or integration of tool-use knowledge into an action plan. The aim of the present study was to investigate whether left brain damage affects anticipatory force scaling when lifting everyday objects. We examined 26 stroke patients with unilateral brain damage (16 with left brain damage, ten with right brain damage) and 21 healthy control subjects. Limb apraxia was assessed by testing pantomime of familiar tool-use and imitation of meaningless hand postures. Participants grasped and lifted twelve randomly presented everyday objects. Grip force was measured with help of sensors fixed on thumb, index and middle-finger. The maximum rate of grip force was determined to quantify the precision of anticipation of object properties. Regression analysis yielded clear deficits of anticipation in the group of patients with left brain damage, while the comparison of patient with right brain damage with their respective control group did not reveal comparable deficits. Lesion-analyses indicate that brain structures typically associated with a tool-use network in the left hemisphere play an essential role for anticipatory grip force scaling, especially the left inferior frontal gyrus (IFG) and the premotor cortex (PMC). Furthermore, significant correlations of impaired anticipation with limb apraxia scores suggest shared representations. However, the presence of dissociations, implicates also independent processes. Overall, our findings suggest that the left hemisphere is engaged in anticipatory grip force scaling for lifting everyday objects. The underlying neural substrate is not restricted to a single region or stream; instead it may rely on
Optimal lift and bank modulations for three-dimensional reentry trajectories with heat constraint
NASA Astrophysics Data System (ADS)
Chern, Jeng-Shing; Yang, Ching-Yew; Sheen, Jyh-Jong
For hypersonic reentry flight, the heat problem is usually the most severe problem. Therefore, it is of necessity and interest to consider the heat constraint in solving optimal reentry trajectories. This paper, under the facilities of the continuation method and the multiple shooting method, investigates the optimal lift and bank modulations for three-dimensional reentry trajectories with heating rate constraint. The modified Newton method is used to induce and accelerate convergence. From the variational formulation, the optimal lift and bank control laws and the transversality conditions are derived. The non-constrained optimal trajectories leading to the boundary of the maximum reachable domain of a typical lifting reentry vehicle are solved at first. It is a three-parameter two-point boundary-value problem. Then the heating rate constraint is imposed and the constrained maximum reachable domain is constructed finally. Because the equilibrium glide condition is eliminated in this paper, the maximum reachable domain obtained is larger than the one obtained under the equilibrium glide assumption. Besides, both optimal lift and optimal bank control histories are presented and discussed.
Bot, Patrick; Rabaud, Marc; Thomas, Goulven; Lombardi, Alessandro; Lebret, Charles
2016-12-02
Bluff bodies moving in a fluid experience a drag force which usually increases with velocity. However in a particular velocity range a drag crisis is observed, i.e., a sharp and strong decrease of the drag force. This counterintuitive result is well characterized for a sphere or a cylinder. Here we show that, for an object breaking the up-down symmetry, a lift crisis is observed simultaneously to the drag crisis. The term lift crisis refers to the fact that at constant incidence the time-averaged transverse force, which remains small or even negative at low velocity, transitions abruptly to large positive values above a critical flow velocity. This transition is characterized from direct force measurements as well as from change in the velocity field around the obstacle.
Optimization technology of 9/7 wavelet lifting scheme on DSP*
NASA Astrophysics Data System (ADS)
Chen, Zhengzhang; Yang, Xiaoyuan; Yang, Rui
2007-12-01
Nowadays wavelet transform has been one of the most effective transform means in the realm of image processing, especially the biorthogonal 9/7 wavelet filters proposed by Daubechies, which have good performance in image compression. This paper deeply studied the implementation and optimization technologies of 9/7 wavelet lifting scheme based on the DSP platform, including carrying out the fixed-point wavelet lifting steps instead of time-consuming floating-point operation, adopting pipelining technique to improve the iteration procedure, reducing the times of multiplication calculation by simplifying the normalization operation of two-dimension wavelet transform, and improving the storage format and sequence of wavelet coefficients to reduce the memory consumption. Experiment results have shown that these implementation and optimization technologies can improve the wavelet lifting algorithm's efficiency more than 30 times, which establish a technique foundation for successfully developing real-time remote sensing image compression system in future.
Effects of Deformation on Drag and Lift Forces Acting on a Droplet in a Shear Flow
NASA Astrophysics Data System (ADS)
Suh, Youngho; Lee, Changhoon
2010-11-01
The droplet behavior in a linear shear flow is studied numerically to investigate the effect of deformation on the drag and lift acting on droplet. The droplet shape is calculated by a level set method which is improved by incorporating a sharp-interface modeling technique for accurately enforcing the matching conditions at the liquid- gas interface. By adopting the feedback forces which can maintain the droplet at a fixed position, we determine the acting force on a droplet in shear flow field with efficient handling of deformation. Based on the numerical results, drag and lift forces acting on a droplet are observed to depend strongly on the deformation. Droplet shapes are observed to be spherical, deformed, and oscillating depending on the Reynolds number. Also, the present method is proven to be applicable to a three- dimensional deformation of droplet in the shear flow, which cannot be properly analyzed by the previous studies. Comparisons of the calculated results by the current method with those obtained from body-fitted methods [Dandy and Leal, J. Fluid Mech. 208, 161 (1989)] and empirical models [Feng and Beard, J. Atmos. Sci. 48, 1856 (1991)] show good agreement.
Lift Optimization Study of a Multi-Element Three-Segment Variable Camber Airfoil
NASA Technical Reports Server (NTRS)
Kaul, Upender K.; Nguyen, Nhan T.
2016-01-01
This paper reports a detailed computational high-lift study of the Variable Camber Continuous Trailing Edge Flap (VCCTEF) system carried out to explore the best VCCTEF designs, in conjunction with a leading edge flap called the Variable Camber Krueger (VCK), for take-off and landing. For this purpose, a three-segment variable camber airfoil employed as a performance adaptive aeroelastic wing shaping control effector for a NASA Generic Transport Model (GTM) in landing and take-off configurations is considered. The objective of the study is to define optimal high-lift VCCTEF settings and VCK settings/configurations. A total of 224 combinations of VCK settings/configurations and VCCTEF settings are considered for the inboard GTM wing, where the VCCTEFs are configured as a Fowler flap that forms a slot between the VCCTEF and the main wing. For the VCK settings of deflection angles of 55deg, 60deg and 65deg, 18, 19 and 19 vck configurations, respectively, were considered for each of the 4 different VCCTEF deflection settings. Different vck configurations were defined by varying the horizontal and vertical distance of the vck from the main wing. A computational investigation using a Reynolds-Averaged Navier-Stokes (RANS) solver was carried out to complement a wind-tunnel experimental study covering three of these configurations with the goal of identifying the most optimal high-lift configurations. Four most optimal high-lift configurations, corresponding to each of the VCK deflection settings, have been identified out of all the different configurations considered in this study yielding the highest lift performance.
NASA Technical Reports Server (NTRS)
Pototzky, Anthony S; Murphy, Patrick C.
2014-01-01
Improving aerodynamic models for adverse loss-of-control conditions in flight is an area being researched under the NASA Aviation Safety Program. Aerodynamic models appropriate for loss of control conditions require a more general mathematical representation to predict nonlinear unsteady behaviors. As more general aerodynamic models are studied that include nonlinear higher order effects, the possibility of measurements that confound aerodynamic and structural responses are probable. In this study an initial step is taken to look at including structural flexibility in analysis of rigid-body forced-oscillation testing that accounts for dynamic rig, sting and balance flexibility. Because of the significant testing required and associated costs in a general study, it makes sense to capitalize on low cost analytical methods where possible, especially where structural flexibility can be accounted for by a low cost method. This paper provides an initial look at using linear lifting surface theory applied to rigid-body aircraft roll forced-oscillation tests.
Park, Jae-Sung; Song, Suk-Heung; Jung, Hyo-Il
2009-04-07
We developed a new microfluidic method for focusing microparticles through the combined use of inertial lift forces and turbulent secondary flows generated in a topographically patterned microchannel. The mechanism of particle focusing is based on the hydrodynamic inertial forces exerted on particles migrating along a non-circular microchannel, i.e.tubular pinch effect and wall effect, which induce particle movement away from walls and along a specific lateral position in the microchannel. With the extraordinary geometry of multi-orifice microchannel, an ordered and focused particle distribution was achieved at central or side regions according to a particle Reynolds number (Re(p)) range. The focusing of particles was controlled by the particle Reynolds number, microchannel length, and volume fraction of particles in suspension. This method will be beneficial in particle focusing processes in a microfluidic device since it offers continuous, high-throughput performance and simple operation.
The MANTA: An RPV design to investigate forces and moments on a lifting surface
NASA Technical Reports Server (NTRS)
Bryan, Kevin; Soutar, John; Witty, Peter; Mediate, Bruno; Quast, Thomas; Combs, Dan; Schubert, Martin; Condron, David; Taylor, Scott; Garino, ED
1989-01-01
The overall goal was to investigate and exploit the advantages of using remotely powered vehicles (RPV's) for in-flight data collection at low Reynold's numbers. The data to be collected is on actual flight loads for any type of rectangular or tapered airfoil section, including vertical and horizontal stabilizers. The data will be on a test specimen using a force-balance system which is located forward of the aircraft to insure an undisturbed air flow over the test section. The collected data of the lift, drag and moment of the test specimen is to be radioed to a grand receiver, thus providing real-time data acquisition. The design of the mission profile and the selection of the instrumentation to satisfy aerodynamic requirements are studied and tested. A half-size demonstrator was constructed and flown to test the flight worthiness of the system.
Modulation of rotation-induced lift force for cell filtration in a low aspect ratio microchannel
Zhou, Jian; Giridhar, Premkumar Vummidi; Kasper, Susan; Papautsky, Ian
2014-01-01
Cell filtration is a critical step in sample preparation in many bioapplications. Herein, we report on a simple, filter-free, microfluidic platform based on hydrodynamic inertial migration. Our approach builds on the concept of two-stage inertial migration which permits precise prediction of microparticle position within the microchannel. Our design manipulates equilibrium positions of larger microparticles by modulating rotation-induced lift force in a low aspect ratio microchannel. Here, we demonstrate filtration of microparticles with extreme efficiency (>99%). Using multiple prostate cell lines (LNCaP and human prostate epithelial tumor cells), we show filtration from spiked blood, with 3-fold concentration and >83% viability. Results of a proliferation assay show normal cell division and suggest no negative effects on intrinsic properties. Considering the planar low-aspect-ratio structure and predictable focusing, we envision promising applications and easy integration with existing lab-on-a-chip systems. PMID:25379097
Peak-Seeking Optimization of Spanwise Lift Distribution for Wings in Formation Flight
NASA Technical Reports Server (NTRS)
Hanson, Curtis E.; Ryan, Jack
2012-01-01
A method is presented for the in-flight optimization of the lift distribution across the wing for minimum drag of an aircraft in formation flight. The usual elliptical distribution that is optimal for a given wing with a given span is no longer optimal for the trailing wing in a formation due to the asymmetric nature of the encountered flow field. Control surfaces along the trailing edge of the wing can be configured to obtain a non-elliptical profile that is more optimal in terms of minimum combined induced and profile drag. Due to the difficult-to-predict nature of formation flight aerodynamics, a Newton-Raphson peak-seeking controller is used to identify in real time the best aileron and flap deployment scheme for minimum total drag. Simulation results show that the peak-seeking controller correctly identifies an optimal trim configuration that provides additional drag savings above those achieved with conventional anti-symmetric aileron trim.
Lift-optimal aspect ratio of a revolving wing at low Reynolds number
NASA Astrophysics Data System (ADS)
Jardin, Thierry; Colonius, Tim
2016-11-01
Lentink & Dickinson (2009) showed that rotational acceleration stabilized the leading-edge vortex on revolving, low-aspect-ratio wings, and hypothesized that a Rossby number of around 3, which is achieved during each half-stroke for a variety of hovering insects, seeds, and birds, represents a convergent high-lift solution across a range of scales in nature. Subsequent work has verified that, in particular, the Coriolis acceleration is responsible for LEV stabilization. Implicit in these results is that there exists an optimal aspect ratio for wings revolving about their root, because it is otherwise unclear why, apart from possible physiological reasons, the convergent solution would not occur for an even lower Rossby number. We perform direct numerical simulations of the flow past revolving wings where we vary the aspect ratio and Rossby numbers independently by displacing the wing root from the axis of rotation. We show that the optimal lift coefficient represents a compromise between competing trends where the coefficient of lift increases monotonically with aspect ratio, holding Rossby number constant, but decreases monotonically with Rossby number, when holding aspect ratio constant. For wings revolving about their root, this favors wings of aspect ratio between 3 and 4. The authors gratefully acknowledge support from Fondation ISAE-Supaero.
Relation Between Lift Force and Ball Spin for Different Baseball Pitches.
Nagami, Tomoyuki; Higuchi, Takatoshi; Nakata, Hiroki; Yanai, Toshimasa; Kanosue, Kazuyuki
2016-04-01
Although the lift force (F(L)) on a spinning baseball has been analyzed in previous studies, no study has analyzed such forces over a wide variety of spins. The purpose of this study was to describe the relationship between F(L) and spin for different types of pitches thrown by collegiate pitchers. Four high-speed video cameras were used to record flight trajectory and spin for 7 types of pitches. A total of 75 pitches were analyzed. The linear kinematics of the ball was determined at 0.008-s intervals during the flight, and the resultant fluid force acting on the ball was calculated with an inverse dynamics approach. The initial angular velocity of the ball was determined using a custom-made apparatus. Equations were derived to estimate the F(L) using the effective spin parameter (ESp), which is a spin parameter calculated using a component of angular velocity of the ball with the exception of the gyro-component. The results indicate that F(L) could be accurately explained from ESp and also that seam orientation (4-seam or 2-seam) did not produce a uniform effect on estimating F(L) from ESp.
Ameli, Mitra; Dafotakis, Manuel; Fink, Gereon R; Nowak, Dennis A
2008-01-01
We tested the ability of healthy participants to learn an association between arbitrary sensory cues and the weight of an object to be lifted using a precision grip between the index finger and thumb. Right-handed participants performed a series of grip-lift tasks with each hand. In a first experiment, participants lifted two objects of equal visual appearance which unexpectedly and randomly changed their weight. In two subsequent experiments, the change in object weight was indicated by cues, which were presented (i) visually or (ii) auditorily. When no cue about the weight of the object to be lifted was presented, participants programmed grip force according to the most recent lift, regardless of the hand used. In contrast, participants were able to rapidly establish an association between a particular sensory cue with a given weight and scaled grip force precisely to the actual weight thereafter, regardless of the hand used or the sensory modality of the cue. We discuss our data within the theoretical concept of internal models.
Low-speed aerodynamic characteristics of an airfoil optimized for maximum lift coefficient
NASA Technical Reports Server (NTRS)
Bingham, G. J.; Chen, A. W.
1972-01-01
An investigation has been conducted in the Langley low-turbulence pressure tunnel to determine the two-dimensional characteristics of an airfoil optimized for maximum lift coefficient. The design maximum lift coefficient was 2.1 at a Reynolds number of 9.7 million. The airfoil with a smooth surface and with surface roughness was tested at angles of attack from 6 deg to 26 deg, Reynolds numbers (based on airfoil chord) from 2.0 million to 12.9 million, and Mach numbers from 0.10 to 0.35. The experimental results are compared with values predicted by theory. The experimental pressure distributions observed at angles of attack up to at least 12 deg were similar to the theoretical values except for a slight increase in the experimental upper-surface pressure coefficients forward of 26 percent chord and a more severe gradient just behind the minimum-pressure-coefficient location. The maximum lift coefficients were measured with the model surface smooth and, depending on test conditions, varied from 1.5 to 1.6 whereas the design value was 2.1.
Kim, Hyun-Kyung; Zhang, Yanxin
2016-06-03
Large spinal compressive force combined with axial torsional shear force during asymmetric lifting tasks is highly associated with lower back injury (LBI). The aim of this study was to estimate lumbar spinal loading and muscle forces during symmetric lifting (SL) and asymmetric lifting (AL) tasks using a whole-body musculoskeletal modelling approach. Thirteen healthy males lifted loads of 7 and 12 kg under two lifting conditions (SL and AL). Kinematic data and ground reaction force data were collected and then processed by a whole-body musculoskeletal model. The results show AL produced a significantly higher peak lateral shear force as well as greater peak force of psoas major, quadratus lumborum, multifidus, iliocostalis lumborum pars lumborum, longissimus thoracis pars lumborum and external oblique than SL. The greater lateral shear forces combined with higher muscle force and asymmetrical muscle contractions may have the biomechanical mechanism responsible for the increased risk of LBI during AL. Practitioner Summary: Estimating lumbar spinal loading and muscle forces during free-dynamic asymmetric lifting tasks with a whole-body musculoskeletal modelling in OpenSim is the core value of this research. The results show that certain muscle groups are fundamentally responsible for asymmetric movement, thereby producing high lumbar spinal loading and muscle forces, which may increase risks of LBI during asymmetric lifting tasks.
A hydrodynamic focusing microchannel based on micro-weir shear lift force.
Yang, Ruey-Jen; Hou, Hui-Hsiung; Wang, Yao-Nan; Lin, Che-Hsin; Fu, Lung-Ming
2012-09-01
A novel microflow cytometer is proposed in which the particles are focused in the horizontal and vertical directions by means of the Saffman shear lift force generated within a micro-weir microchannel. The proposed device is fabricated on stress-relieved glass substrates and is characterized both numerically and experimentally using fluorescent particles with diameters of 5 μm and 10 μm, respectively. The numerical results show that the micro-weir structures confine the particle stream to the center of the microchannel without the need for a shear flow. Moreover, the experimental results show that the particles emerging from the micro-weir microchannel pass through the detection region in a one-by-one fashion. The focusing effect of the micro-weir microchannel is quantified by computing the normalized variance of the optical detection signal intensity. It is shown that the focusing performance of the micro-weir structure is equal to 99.76% and 99.57% for the 5-μm and 10-μm beads, respectively. Overall, the results presented in this study confirm that the proposed microcytometer enables the reliable sorting and counting of particles with different diameters.
Effect of chordwise forces and deformations and deformations due to steady lift on wing flutter
NASA Technical Reports Server (NTRS)
Boyd, W. N.
1977-01-01
This investigation explores the effects of chordwise forces and deformations and steady-state deformation due to lift on the static and dynamic aeroelastic stability of a uniform cantilever wing. Results of this analysis are believed to have practical applications for high-performance sailplanes and certain RPV's. The airfoil cross section is assumed to be symmetric and camber bending is neglected. Motions in vertical bending, fore-and-aft bending, and torsion are considered. A differential equation model is developed, which included the nonlinear elastic bending-torsion coupling that accompanies even moderate deflections. A linearized expansion in small time-dependent deflections is made about a steady flight condition. The stability determinant of the linearized system then contains coefficients that depend on steady displacements. Loads derived from two-dimensional incompressible aerodynamic theory are used to obtain the majority of the results, but cases using three-dimensional subsonic compressible theory are also studied. The stability analysis is carried out in terms of the dynamically uncoupled natural modes of vibration of the uniform cantilever.
NASA Astrophysics Data System (ADS)
Kim, Jungwoo; Balachandar, S.
2012-01-01
We perform fully resolved direct numerical simulations of an isolated particle subjected to free-stream turbulence in order to investigate the effect of turbulence on the drag and lift forces at the level of a single particle, following Bagchi and Balachandar's work (Bagchi and Balachandar in Phys Fluids 15:3496-3513, 2003). The particle Reynolds numbers based on the mean relative particle velocity and the particle diameter are Re = 100, 250 and 350, which covers three different regimes of wake evolution in a uniform flow: steady axisymmetric wake, steady planar symmetric wake, and unsteady planar symmetric vortex shedding. At each particle Reynolds number, the turbulent intensity is 5-10% of the mean relative particle velocity, and the corresponding diameter of the particle is comparable to or larger than the Kolmogorov scale. The simulation results show that standard drag values determined from uniform flow simulations can accurately predict the drag force if the turbulence intensity is sufficiently weak (5% or less compared to the mean relative velocity). However, it is shown that for finite-sized particles, flow non-uniformity, which is usually neglected in the case of the small particles, can play an important role in determining the forces as the relative turbulence intensity becomes large. The influence of flow non-uniformity on drag force could be qualitatively similar to the Faxen correction. In addition, finite-sized particles at sufficient Reynolds number are inherently subjected to stochastic forces arising from their self-induced vortex shedding in addition to lift force arising from the local ambient flow properties (vorticity and strain rate). The effect of rotational and strain rate of the ambient turbulence seen by the particle on the lift force is explored based on the conditional averaging using the generalized representation of the quasi-steady force proposed by Bagchi and Balachandar (J Fluid Mech 481:105-148, 2003). From the present study, it
NASA Astrophysics Data System (ADS)
Kommajosyula, Ravikishore; Mazzocco, Thomas; Ambrosini, Walter; Baglietto, Emilio
2016-11-01
Accurate prediction of Bubble Departure and Lift-off Diameters is key for development of closures in two-phase Eulerian CFD simulation of Flow Boiling, owing to its sensitivity in the Heat Flux partitioning approach. Several models ranging from simple correlations to solving complex force balance models have been proposed in literature; however, they rely on data-fitting for specific databases, and have shown to be inapplicable for general flow applications. The aim of this study is to extend the approach by proposing a more consistent and general formulation that accounts for relevant forces acting on the Bubble at the point of Departure and Lift-off. Among the key features of the model, the Bubble Inclination angle is treated as an unknown to be inferred along with the Departure Diameter, and the relative velocity of the bubble sliding on the surface, is modeled to determine the Lift-off Diameter. A novel expression is developed for the bubble growth force in terms of flow quantities, based on extensive data analysis. The model has been validated using 6 different experimental databases with varying flow conditions and 3 fluids. Results show high accuracy of predictions over a broad range, outperforming existing models both in terms of accuracy and generality. CASL - The Consortium for Advanced Simulation of LWRs.
Boulgouris, N V; Tzovaras, D; Strintzis, M G
2001-01-01
The optimal predictors of a lifting scheme in the general n-dimensional case are obtained and applied for the lossless compression of still images using first quincunx sampling and then simple row-column sampling. In each case, the efficiency of the linear predictors is enhanced nonlinearly. Directional postprocessing is used in the quincunx case, and adaptive-length postprocessing in the row-column case. Both methods are seen to perform well. The resulting nonlinear interpolation schemes achieve extremely efficient image decorrelation. We further investigate context modeling and adaptive arithmetic coding of wavelet coefficients in a lossless compression framework. Special attention is given to the modeling contexts and the adaptation of the arithmetic coder to the actual data. Experimental evaluation shows that the best of the resulting coders produces better results than other known algorithms for multiresolution-based lossless image coding.
Ghiasi, Mohammad Sadegh; Arjmand, Navid; Boroushaki, Mehrdad; Farahmand, Farzam
2016-03-01
A six-degree-of-freedom musculoskeletal model of the lumbar spine was developed to predict the activity of trunk muscles during light, moderate and heavy lifting tasks in standing posture. The model was formulated into a multi-objective optimization problem, minimizing the sum of the cubed muscle stresses and maximizing the spinal stability index. Two intelligent optimization algorithms, i.e., the vector evaluated particle swarm optimization (VEPSO) and nondominated sorting genetic algorithm (NSGA), were employed to solve the optimization problem. The optimal solution for each task was then found in the way that the corresponding in vivo intradiscal pressure could be reproduced. Results indicated that both algorithms predicted co-activity in the antagonistic abdominal muscles, as well as an increase in the stability index when going from the light to the heavy task. For all of the light, moderate and heavy tasks, the muscles' activities predictions of the VEPSO and the NSGA were generally consistent and in the same order of the in vivo electromyography data. The proposed methodology is thought to provide improved estimations for muscle activities by considering the spinal stability and incorporating the in vivo intradiscal pressure data.
Optimal Balance Between Force and Velocity Differs Among World-Class Athletes.
Giroux, Caroline; Rabita, Giuseppe; Chollet, Didier; Guilhem, Gaël
2016-02-01
Performance during human movements is highly related to force and velocity muscle capacities. Those capacities are highly developed in elite athletes practicing power-oriented sports. However, it is still unclear whether the balance between their force and velocity-generating capacities constitutes an optimal profile. In this study, we aimed to determine the effect of elite sport background on the force-velocity relationship in the squat jump, and evaluate the level of optimization of these profiles. Ninety-five elite athletes in cycling, fencing, taekwondo, and athletic sprinting, and 15 control participants performed squat jumps in 7 loading conditions (range: 0%-60% of the maximal load they were able to lift). Theoretical maximal power (Pm), force (F0), and velocity (v0) were determined from the individual force-velocity relationships. Optimal profiles were assessed by calculating the optimal force (F0th) and velocity (v0th). Athletic sprinters and cyclists produced greater force than the other groups (P < .05). F0 was significantly lower than F0th, and v0 was significantly higher than v0th for female fencers and control participants, and for male athletics sprinters, fencers, and taekwondo practitioners (P < .05). Our study shows that the chronic practice of an activity leads to differently balanced force-velocity profiles. Moreover, the differences between measured and optimal force-velocity profiles raise potential sources of performance improvement in elite athletes.
Jung, Ku Youl; Min, Byoung-Chul; Ahn, Chiyui; Choi, Gyung-Min; Shin, Il-Jae; Park, Seung-Young; Rhie, Kungwon; Shin, Kyung-Ho
2013-09-01
We present a fabrication method for nano-scale magnetic tunnel junctions (MTJs), employing e-beam lithography and lift-off process assisted by the probe tip of atomic force microscope (AFM). It is challenging to fabricate nano-sized MTJs on small substrates because it is difficult to use chemical mechanical planarization (CMP) process. The AFM-assisted lift-off process enables us to fabricate nano-sized MTJs on small substrates (12.5 mm x 12.5 mm) without CMP process. The e-beam patterning has been done using bi-layer resist, the poly methyl methacrylate (PMMA)/ hydrogen silsesquioxane (HSQ). The PMMA/HSQ resist patterns are used for both the etch mask for ion milling and the self-aligned mask for top contact formation after passivation. The self-aligned mask buried inside a passivation oxide layer, is readily lifted-off by the force exerted by the probe tip. The nano-MTJs (160 nm x 90 nm) fabricated by this method show clear current-induced magnetization switching with a reasonable TMR and critical switching current density.
Lifting speed preferences and their effects on the maximal lifting capacity
LIN, Chiuhsiang Joe; CHENG, Chih-Feng
2016-01-01
The objectives of this study were to evaluate how lifting capacity and subjective preferences are affected by different lifting speeds. The maximum lifting capacity of lift was determined with three independent variables, lifting speed, lifting technique, and lifting height. Questionnaires were evaluated after the experiment by the participants for the lifting speed preferences. This study found that the lifting speed was a significant factor in the lifting capacity (p<0.001); and the lifting height (p<0.001) and the interaction of lifting speed and lifting height (p=0.005) affected the lifting capacity significantly. The maximal lifting capacity was achieved around the optimal speed that was neither too fast nor too slow. Moreover, the participants’ preferred lifting speeds were consistently close to the optimal lifting speed. The results showed that the common lifting practice guideline to lift slowly might make the worker unable to generate a large lifting capacity. PMID:27383532
Lifting speed preferences and their effects on the maximal lifting capacity.
Lin, Chiuhsiang Joe; Cheng, Chih-Feng
2017-02-07
The objectives of this study were to evaluate how lifting capacity and subjective preferences are affected by different lifting speeds. The maximum lifting capacity of lift was determined with three independent variables, lifting speed, lifting technique, and lifting height. Questionnaires were evaluated after the experiment by the participants for the lifting speed preferences. This study found that the lifting speed was a significant factor in the lifting capacity (p<0.001); and the lifting height (p<0.001) and the interaction of lifting speed and lifting height (p=0.005) affected the lifting capacity significantly. The maximal lifting capacity was achieved around the optimal speed that was neither too fast nor too slow. Moreover, the participants' preferred lifting speeds were consistently close to the optimal lifting speed. The results showed that the common lifting practice guideline to lift slowly might make the worker unable to generate a large lifting capacity.
Effects of Buoyancy and Forcing on Transitioning and Turbulent Lifted Flames
NASA Technical Reports Server (NTRS)
Kosaly, George; Kramlich, John C.; Riley, James J.; Nichols, Joseph W.
2003-01-01
The objectives of this paper are two-fold. First, a numerical scheme for the simulation of a buoyant, reacting jet is presented with special attention given to boundary conditions. In the absence of coflow, a jet flame is particularly sensitive to boundary conditions enforced upon the computational domain. However, careful consideration of proper boundary conditions can minimize their effect upon the overall simulation. Second, results of some preliminary simulations are presented over a range of Froude and Damkohler numbers. This range was chosen so as to produce lifted flames in both normal gravity and microgravity environments.
Determining safe limits for significant task parameters during manual lifting.
Singh, Ravindra Pratrap; Batish, Ajay; Singh, Tejinder Pal
2014-04-01
This experimental study investigated the effect of lifting task parameters (i.e., lifting weight, frequency, coupling, asymmetric angle, and vertical, horizontal, and travel distances) for various dynamic human lifting activities on the ground reaction forces of workers. Ten male workers loaded containers from different levels asymmetrically during experimental trials. The experimental design evolved using Taguchi's Fractional Factorial Experiments. Three factors (lifting weight, frequency, and vertical distance) were observed to be significant. The results showed that vertical reaction forces increase when workers lift weight from floor to shoulder height frequently. It was also observed that instantaneous loading rate increases with more weight, vertical distance, and frequency; a significant extra loading rate is required to change the lower level of load, frequency, and vertical distance to higher levels. Safe limits for significant factors were determined to result in optimal performance of the manual lifting task.
Control of Precision Grip Force in Lifting and Holding of Low-Mass Objects
Kimura, Daisuke; Kadota, Koji; Ito, Taro
2015-01-01
Few studies have investigated the control of grip force when manipulating an object with an extremely small mass using a precision grip, although some related information has been provided by studies conducted in an unusual microgravity environment. Grip-load force coordination was examined while healthy adults (N = 17) held a moveable instrumented apparatus with its mass changed between 6 g and 200 g in 14 steps, with its grip surface set as either sandpaper or rayon. Additional measurements of grip-force-dependent finger-surface contact area and finger skin indentation, as well as a test of weight discrimination, were also performed. For each surface condition, the static grip force was modulated in parallel with load force while holding the object of a mass above 30 g. For objects with mass smaller than 30 g, on the other hand, the parallel relationship was changed, resulting in a progressive increase in grip-to-load force (GF/LF) ratio. The rayon had a higher GF/LF force ratio across all mass levels. The proportion of safety margin in the static grip force and normalized moment-to-moment variability of the static grip force were also elevated towards the lower end of the object mass for both surfaces. These findings indicate that the strategy of grip force control for holding objects with an extremely small mass differs from that with a mass above 30 g. The data for the contact area, skin indentation, and weight discrimination suggest that a decreased level of cutaneous feedback signals from the finger pads could have played some role in a cost function in efficient grip force control with low-mass objects. The elevated grip force variability associated with signal-dependent and internal noises, and anticipated inertial force on the held object due to acceleration of the arm and hand, could also have contributed to the cost function. PMID:26376484
Control of Precision Grip Force in Lifting and Holding of Low-Mass Objects.
Hiramatsu, Yuichi; Kimura, Daisuke; Kadota, Koji; Ito, Taro; Kinoshita, Hiroshi
2015-01-01
Few studies have investigated the control of grip force when manipulating an object with an extremely small mass using a precision grip, although some related information has been provided by studies conducted in an unusual microgravity environment. Grip-load force coordination was examined while healthy adults (N = 17) held a moveable instrumented apparatus with its mass changed between 6 g and 200 g in 14 steps, with its grip surface set as either sandpaper or rayon. Additional measurements of grip-force-dependent finger-surface contact area and finger skin indentation, as well as a test of weight discrimination, were also performed. For each surface condition, the static grip force was modulated in parallel with load force while holding the object of a mass above 30 g. For objects with mass smaller than 30 g, on the other hand, the parallel relationship was changed, resulting in a progressive increase in grip-to-load force (GF/LF) ratio. The rayon had a higher GF/LF force ratio across all mass levels. The proportion of safety margin in the static grip force and normalized moment-to-moment variability of the static grip force were also elevated towards the lower end of the object mass for both surfaces. These findings indicate that the strategy of grip force control for holding objects with an extremely small mass differs from that with a mass above 30 g. The data for the contact area, skin indentation, and weight discrimination suggest that a decreased level of cutaneous feedback signals from the finger pads could have played some role in a cost function in efficient grip force control with low-mass objects. The elevated grip force variability associated with signal-dependent and internal noises, and anticipated inertial force on the held object due to acceleration of the arm and hand, could also have contributed to the cost function.
NASA Technical Reports Server (NTRS)
Henderson, M. L.
1979-01-01
The benefits to high lift system maximum life and, alternatively, to high lift system complexity, of applying analytic design and analysis techniques to the design of high lift sections for flight conditions were determined and two high lift sections were designed to flight conditions. The influence of the high lift section on the sizing and economics of a specific energy efficient transport (EET) was clarified using a computerized sizing technique and an existing advanced airplane design data base. The impact of the best design resulting from the design applications studies on EET sizing and economics were evaluated. Flap technology trade studies, climb and descent studies, and augmented stability studies are included along with a description of the baseline high lift system geometry, a calculation of lift and pitching moment when separation is present, and an inverse boundary layer technique for pressure distribution synthesis and optimization.
Effects of Different Lifting Cadences on Ground Reaction Forces during the Squat Exercise
NASA Technical Reports Server (NTRS)
Bentley, Jason R.; Amonette, William E.; Hagan, R. Donald
2008-01-01
The purpose of this investigation was to determine the effect of different cadences on the ground reaction force (GRF(sub R)) during the squat exercise. It is known that squats performed with greater acceleration will produce greater inertial forces; however, it is not well understood how different squat cadences affect GRF(sub R). It was hypothesized that faster squat cadences will result in greater peak GRF(sub R). METHODS: Six male subjects (30.8+/-4.4 y, 179.5+/-8.9 cm, 88.8+/-13.3 kg) with previous squat experience performed three sets of three squats using three different cadences (FC = 1 sec descent/1 sec ascent; MC = 3 sec descent/1 sec ascent; SC = 4 sec descent/2 sec ascent) with barbell mass equal to body mass. Ground reaction force was used to calculate inertial force trajectories of the body plus barbell (FI(sub system)). Forces were normalized to body mass. RESULTS: Peak GRF(sub R) and peak FI(sub system) were significantly higher in FC squats compared to MC (p=0.0002) and SC (p=0.0002). Range of GRF(sub R) and FI(sub system) were also significantly higher in FC compared to MC (p<0.05), and MC were significantly higher than SC (p<0.05). DISCUSSION: Faster squat cadences result in significantly greater peak GRF(sub R) due to the inertia of the system. GRF(sub R) was more dependent upon decent cadence than on ascent cadence. PRACTICAL APPLICATION: This study demonstrates that faster squat cadences produce greater ground reaction forces. Therefore, the use of faster squat cadences might enhance strength and power adaptations to long-term resistance exercise training. Key Words: velocity, weight training, resistive exercise
Design study of shaft face seal with self-acting lift augmentation. 4: Force balance
NASA Technical Reports Server (NTRS)
Ludwig, L. P.; Zuk, J.; Johnson, R. L.
1972-01-01
A method for predicting the operating film thickness of self-acting seals is described. The analysis considers a 16.76-cm mean diameter seal that is typical of large gas turbines for aircraft. Four design points were selected to cover a wide range of operation for advanced engines. This operating range covered sliding speeds of 61 to 153 m/sec, sealed pressures of 45 to 217 N/sq cm abs, and gas temperatures of 311 to 977 K. The force balance analysis revealed that the seal operated without contact over the operating range with gas film thicknesses ranging between 0.00046 to 0.00119 cm, and with gas leakage rates between 0.01 to 0.39 scmm.
NASA Technical Reports Server (NTRS)
Urnes, James, Sr.; Nguyen, Nhan; Ippolito, Corey; Totah, Joseph; Trinh, Khanh; Ting, Eric
2013-01-01
Boeing and NASA are conducting a joint study program to design a wing flap system that will provide mission-adaptive lift and drag performance for future transport aircraft having light-weight, flexible wings. This Variable Camber Continuous Trailing Edge Flap (VCCTEF) system offers a lighter-weight lift control system having two performance objectives: (1) an efficient high lift capability for take-off and landing, and (2) reduction in cruise drag through control of the twist shape of the flexible wing. This control system during cruise will command varying flap settings along the span of the wing in order to establish an optimum wing twist for the current gross weight and cruise flight condition, and continue to change the wing twist as the aircraft changes gross weight and cruise conditions for each mission segment. Design weight of the flap control system is being minimized through use of light-weight shape memory alloy (SMA) actuation augmented with electric actuators. The VCCTEF program is developing better lift and drag performance of flexible wing transports with the further benefits of lighter-weight actuation and less drag using the variable camber shape of the flap.
Static optimization of muscle forces during gait in comparison to EMG-to-force processing approach.
Heintz, Sofia; Gutierrez-Farewik, Elena M
2007-07-01
Individual muscle forces evaluated from experimental motion analysis may be useful in mathematical simulation, but require additional musculoskeletal and mathematical modelling. A numerical method of static optimization was used in this study to evaluate muscular forces during gait. The numerical algorithm used was built on the basis of traditional optimization techniques, i.e., constrained minimization technique using the Lagrange multiplier method to solve for constraints. Measuring exact muscle forces during gait analysis is not currently possible. The developed optimization method calculates optimal forces during gait, given a specific performance criterion, using kinematics and kinetics from gait analysis together with muscle architectural data. Experimental methods to validate mathematical methods to calculate forces are limited. Electromyography (EMG) is frequently used as a tool to determine muscle activation in experimental studies on human motion. A method of estimating force from the EMG signal, the EMG-to-force approach, was recently developed by Bogey et al. [Bogey RA, Perry J, Gitter AJ. An EMG-to-force processing approach for determining ankle muscle forcs during normal human gait. IEEE Trans Neural Syst Rehabil Eng 2005;13:302-10] and is based on normalization of activation during a maximum voluntary contraction to documented maximal muscle strength. This method was adapted in this study as a tool with which to compare static optimization during a gait cycle. Muscle forces from static optimization and from EMG-to-force muscle forces show reasonably good correlation in the plantarflexor and dorsiflexor muscles, but less correlation in the knee flexor and extensor muscles. Additional comparison of the mathematical muscle forces from static optimization to documented averaged EMG data reveals good overall correlation to patterns of evaluated muscular activation. This indicates that on an individual level, muscular force patterns from mathematical
Powered-lift aircraft technology
NASA Technical Reports Server (NTRS)
Deckert, W. H.; Franklin, J. A.
1989-01-01
Powered lift aircraft have the ability to vary the magnitude and direction of the force produced by the propulsion system so as to control the overall lift and streamwise force components of the aircraft, with the objective of enabling the aircraft to operate from minimum sized terminal sites. Power lift technology has contributed to the development of the jet lift Harrier and to the forth coming operational V-22 Tilt Rotor and the C-17 military transport. This technology will soon be expanded to include supersonic fighters with short takeoff and vertical landing capability, and will continue to be used for the development of short- and vertical-takeoff and landing transport. An overview of this field of aeronautical technology is provided for several types of powered lift aircraft. It focuses on the description of various powered lift concepts and their operational capability. Aspects of aerodynamics and flight controls pertinent to powered lift are also discussed.
Satellite Constellation Optimization for Turkish Armed Forces
2013-03-01
information is estimated to average 1 hour per response, including the time for reviewing instruction, searching existing data sources, gathering and...Communications COTS Commercial Off-the-Shelf CUBESAT Cube Satellite GEO Geostationary Earth Orbit HQ Headquarter ISR Intelligence Surveillance...Turkish Armed Forces have been executing Intelligence Surveillance and Reconnaissance (ISR) missions with a limited number of UAVs and RF-4E
Shahinfar, Saleh; Guenther, Jerry N; Page, C David; Kalantari, Afshin S; Cabrera, Victor E; Fricke, Paul M; Weigel, Kent A
2015-06-01
The common practice on most commercial dairy farms is to inseminate all cows that are eligible for breeding, while ignoring (or absorbing) the costs associated with semen and labor directed toward low-fertility cows that are unlikely to conceive. Modern analytical methods, such as machine learning algorithms, can be applied to cow-specific explanatory variables for the purpose of computing probabilities of success or failure associated with upcoming insemination events. Lift chart analysis can identify subsets of high fertility cows that are likely to conceive and are therefore appropriate targets for insemination (e.g., with conventional artificial insemination semen or expensive sex-enhanced semen), as well as subsets of low-fertility cows that are unlikely to conceive and should therefore be passed over at that point in time. Although such a strategy might be economically viable, the management, environmental, and financial conditions on one farm might differ widely from conditions on the next, and hence the reproductive management recommendations derived from such a tool may be suboptimal for specific farms. When coupled with cost-sensitive evaluation of misclassified and correctly classified insemination events, the strategy can be a potentially powerful tool for optimizing the reproductive management of individual farms. In the present study, lift chart analysis and cost-sensitive evaluation were applied to a data set consisting of 54,806 insemination events of primiparous Holstein cows on 26 Wisconsin farms, as well as a data set with 17,197 insemination events of primiparous Holstein cows on 3 Wisconsin farms, where the latter had more detailed information regarding health events of individual cows. In the first data set, the gains in profit associated with limiting inseminations to subsets of 79 to 97% of the most fertile eligible cows ranged from $0.44 to $2.18 per eligible cow in a monthly breeding period, depending on days in milk at breeding and milk
NASA Astrophysics Data System (ADS)
Darazi, R.; Gouze, A.; Macq, B.
2009-01-01
Reproducing a natural and real scene as we see in the real world everyday is becoming more and more popular. Stereoscopic and multi-view techniques are used for this end. However due to the fact that more information are displayed requires supporting technologies such as digital compression to ensure the storage and transmission of the sequences. In this paper, a new scheme for stereo image coding is proposed. The original left and right images are jointly coded. The main idea is to optimally exploit the existing correlation between the two images. This is done by the design of an efficient transform that reduces the existing redundancy in the stereo image pair. This approach was inspired by Lifting Scheme (LS). The novelty in our work is that the prediction step is been replaced by an hybrid step that consists in disparity compensation followed by luminance correction and an optimized prediction step. The proposed scheme can be used for lossless and for lossy coding. Experimental results show improvement in terms of performance and complexity compared to recently proposed methods.
Evaluation of muscle force predictions using optimization theory
NASA Astrophysics Data System (ADS)
Ziya Arslan, Yunus; Kaya, Motoshi; Herzog, Walter
2013-02-01
Prediction of muscle forces using optimization based models of muscle coordination is an active research area in biomechanics. Theoretical calculation of individual muscle forces depends on solving the redundancy problem. In a musculoskeletal model, redundancy arises since the number of muscles in the model exceeds the number of degrees-of-freedom present. One of the widely used methods to solve this problem is to formulate a physiologically sound cost function and optimize this function subject to mechanical equality and inequality constraint equations. In this study, force predictions obtained from different optimization-based models were compared with those obtained from experimentally measured individual muscle forces recorded during a variety of movement conditions. Advantages and limitations of the tested models were discussed.
Walczyk, Wiktoria; Hain, Nicole; Schönherr, Holger
2014-08-28
We report on an Atomic Force Microscopy (AFM) study of AFM tip-nanobubble interactions in experiments conducted on argon surface nanobubbles on HOPG (highly oriented pyrolytic graphite) in water in tapping mode, lift mode and Force Volume (FV) mode AFM. By subsequent data acquisition on the same nanobubbles in these three different AFM modes, we could directly compare the effect of different tip-sample interactions. The tip-bubble interaction strength was found to depend on the vertical and horizontal position of the tip on the bubble with respect to the bubble center. The interaction forces measured experimentally were in good agreement with the forces calculated using the dynamic interaction model. The strength of the hydrodynamic effect was also found to depend on the direction of the tip movement. It was more pronounced in the FV mode, in which the tip approaches the bubble from the top, than in the lift mode, in which the tip approaches the bubble from the side. This result suggests that the direction of tip movement influences the bubble deformation. The effect should be taken into account when nanobubbles are analysed by AFM in various scanning modes.
One of the major contributions of Greenhouse Gas (GHG) emissions from water resource recovery facilities results from the energy used by the pumping regime of the lift stations. This project demonstrated an energy-efficient control method of lift station system operation that uti...
NASA Technical Reports Server (NTRS)
Yuska, J. A.; Diedrich, J. H.
1972-01-01
Test data are presented for a 38-cm (15-in.) diameter, 1.28 pressure ratio model VTOL lift fan installed in a two-dimensional wing and tested in a 2.74-by 4.58-meter (9-by 15-ft)V/STOL wind tunnel. Tests were run with and without exit louvers over a wide range of crossflow velocities and wing angle of attack. Tests were also performed with annular-inlet vanes, inlet bell-mouth surface disconuities, and fences to induce fan windmilling. Data are presented on the axial force of the fan assembly and overall wing forces and moments as measured on force balances for various static and crossflow test conditions. Midspan wing surface pressure coefficient data are also given.
Oliphant, David; Quilter, Jared; Andersen, Todd; Conroy, Thomas
2011-09-13
An apparatus used for maintaining a wind tower structure wherein the wind tower structure may have a plurality of legs and may be configured to support a wind turbine above the ground in a better position to interface with winds. The lift structure may be configured for carrying objects and have a guide system and drive system for mechanically communicating with a primary cable, rail or other first elongate member attached to the wind tower structure. The drive system and guide system may transmit forces that move the lift relative to the cable and thereby relative to the wind tower structure. A control interface may be included for controlling the amount and direction of the power into the guide system and drive system thereby causing the guide system and drive system to move the lift relative to said first elongate member such that said lift moves relative to said wind tower structure.
NASA Astrophysics Data System (ADS)
Chevrot, Sébastien; Martin, Roland; Komatitsch, Dimitri
2012-12-01
Wavelets are extremely powerful to compress the information contained in finite-frequency sensitivity kernels and tomographic models. This interesting property opens the perspective of reducing the size of global tomographic inverse problems by one to two orders of magnitude. However, introducing wavelets into global tomographic problems raises the problem of computing fast wavelet transforms in spherical geometry. Using a Cartesian cubed sphere mapping, which grids the surface of the sphere with six blocks or 'chunks', we define a new algorithm to implement fast wavelet transforms with the lifting scheme. This algorithm is simple and flexible, and can handle any family of discrete orthogonal or bi-orthogonal wavelets. Since wavelet coefficients are local in space and scale, aliasing effects resulting from a parametrization with global functions such as spherical harmonics are avoided. The sparsity of tomographic models expanded in wavelet bases implies that it is possible to exploit the power of compressed sensing to retrieve Earth's internal structures optimally. This approach involves minimizing a combination of a ℓ2 norm for data residuals and a ℓ1 norm for model wavelet coefficients, which can be achieved through relatively minor modifications of the algorithms that are currently used to solve the tomographic inverse problem.
Optimized free energies from bidirectional single-molecule force spectroscopy.
Minh, David D L; Adib, Artur B
2008-05-09
An optimized method for estimating path-ensemble averages using data from processes driven in opposite directions is presented. Based on this estimator, bidirectional expressions for reconstructing free energies and potentials of mean force from single-molecule force spectroscopy-valid for biasing potentials of arbitrary stiffness-are developed. Numerical simulations on a model potential indicate that these methods perform better than unidirectional strategies.
Jaramillo-Botero, Andres; Naserifar, Saber; Goddard, William A
2014-04-08
First-principles-based force fields prepared from large quantum mechanical data sets are now the norm in predictive molecular dynamics simulations for complex chemical processes, as opposed to force fields fitted solely from phenomenological data. In principle, the former allow improved accuracy and transferability over a wider range of molecular compositions, interactions, and environmental conditions unexplored by experiments. That is, assuming they have been optimally prepared from a diverse training set. The trade-off has been force field engines that are functionally complex, with a large number of nonbonded and bonded analytical forms that give rise to rather large parameter search spaces. To address this problem, we have developed GARFfield (genetic algorithm-based reactive force field optimizer method), a hybrid multiobjective Pareto-optimal parameter development scheme based on genetic algorithms, hill-climbing routines and conjugate-gradient minimization. To demonstrate the capabilities of GARFfield we use it to develop two very different force fields: (1) the ReaxFF reactive force field for modeling the adiabatic reactive dynamics of silicon carbide growth from an methyltrichlorosilane precursor and (2) the SiC electron force field with effective core pseudopotentials for modeling nonadiabatic dynamic phenomena with highly excited electronic states. The flexible and open architecture of GARFfield enables efficient and fast parallel optimization of parameters from quantum mechanical data sets for demanding applications like ReaxFF, electronic fast forward (or electron force field), and others including atomistic reactive charge-optimized many-body interatomic potentials, Morse, and coarse-grain force fields.
Optimal plane changes using third-body forces.
Villac, B F; Scheeres, D J
2004-05-01
The fuel optimality of third-body driven plane changes (i.e., plane changes performed by using third-body forces) over one-impulse transfers is investigated numerically and analytically. In particular, the range of third-body driven plane changes that are realizable is shown to be restricted and one impulse must be used in the uncovered regions. However, when third-body driven plane changes are realizable, it is shown that they are always optimal above a certain critical value (about 40 degrees ) that depends on the initial condition. Contour plots of optimal DeltaV values to perform a desired plane changes are given.
Lift enhancing tabs for airfoils
NASA Technical Reports Server (NTRS)
Ross, James C. (Inventor)
1994-01-01
A tab deployable from the trailing edge of a main airfoil element forces flow onto a following airfoil element, such as a flap, to keep the flow attached and thus enhance lift. For aircraft wings with high lift systems that include leading edge slats, the slats may also be provided with tabs to turn the flow onto the following main element.
... both sides even. If you have already had plastic surgery to lift your upper eyelids, a forehead ... Managing the cosmetic patient. In: Neligan PC, ed. Plastic Surgery . 3rd ed. Philadelphia, PA: Elsevier Saunders; 2013: ...
... after surgery using a needle and syringe. Poor wound healing. Sometimes areas along the incision line heal poorly ... might be given antibiotics if there is a wound healing problem. Scarring. Incision scars from a buttock lift ...
Skov, Søren Nielsen; Røpcke, Diana Mathilde; Ilkjær, Christine; Rasmussen, Jonas; Tjørnild, Marcell Juan; Jimenez, Jorge H; Yoganathan, Ajit P; Nygaard, Hans; Nielsen, Sten Lyager; Jensen, Morten Olgaard
2016-03-21
Limited knowledge exists about the forces acting on mitral valve annuloplasty repair devices. The aim of this study was to develop a new mitral annular force transducer to measure the forces acting on clinically used mitral valve annuloplasty devices. The design of an X-shaped transducer in the present study was optimized for simultaneous in- and out-of-plane force measurements. Each arm was mounted with strain gauges on four circumferential elements to measure out-of-plane forces, and the central parts of the X-arms were mounted with two strain gauges to measure in-plane forces. A dedicated calibration setup was developed to calibrate isolated forces with tension and compression for in- and out-of-plane measurements. With this setup, it was possible with linear equations to isolate and distinguish measured forces between the two planes and minimize transducer arm crosstalk. An in-vitro test was performed to verify the crosstalk elimination method and the assumptions behind it. The force transducer was implanted and evaluated in an 80kg porcine in-vivo model. Following crosstalk elimination, in-plane systolic force accumulation was found to be in average 4.0±0.1N and the out-of-plane annular segments experienced an average force of 1.4±0.4N. Directions of the systolic out-of-plane forces indicated movements towards a saddle shaped annulus, and the transducer was able to measure independent directional forces in individual annular segments. Further measurements with the new transducer coupled with clinical annuloplasty rings will provide a detailed insight into the biomechanical dynamics of these devices.
Framelet lifting in image processing
NASA Astrophysics Data System (ADS)
Lu, Da-Yong; Feng, Tie-Yong
2010-08-01
To obtain appropriate framelets in image processing, we often need to lift existing framelets. For this purpose the paper presents some methods which allow us to modify existing framelets or filters to construct new ones. The relationships of matrices and their eigenvalues which be used in lifting schemes show that the frame bounds of the lifted wavelet frames are optimal. Moreover, the examples given in Section 4 indicate that the lifted framelets can play the roles of some operators such as the weighted average operator, the Sobel operator and the Laplacian operator, which operators are often used in edge detection and motion estimation applications.
Unseren, M.A.
1997-04-20
The paper reviews a method for modeling and controlling two serial link manipulators which mutually lift and transport a rigid body object in a three dimensional workspace. A new vector variable is introduced which parameterizes the internal contact force controlled degrees of freedom. A technique for dynamically distributing the payload between the manipulators is suggested which yields a family of solutions for the contact forces and torques the manipulators impart to the object. A set of rigid body kinematic constraints which restrict the values of the joint velocities of both manipulators is derived. A rigid body dynamical model for the closed chain system is first developed in the joint space. The model is obtained by generalizing the previous methods for deriving the model. The joint velocity and acceleration variables in the model are expressed in terms of independent pseudovariables. The pseudospace model is transformed to obtain reduced order equations of motion and a separate set of equations governing the internal components of the contact forces and torques. A theoretic control architecture is suggested which explicitly decouples the two sets of equations comprising the model. The controller enables the designer to develop independent, non-interacting control laws for the position control and internal force control of the system.
NASA Astrophysics Data System (ADS)
Moore, P.; Sowter, A.
Studies of aerodynamic lift and drag in hyperthermal free molecular flow regimes usually adopt Schamberg's model for gas-surface interaction, utilising the thermal accommodation coefficient. Most authors assume near-diffuse reflection characteristics with constant re-emission speed for all angles of incidence. For modelling atmospheric forces a more natural approach is to utilise normal and tangential momentum coefficients, σ1 and σ respectively. Experimental laboratory data has yielded qualitatively the dependence on the angle of incidence which to good approximation can be represented as ω ≜ ω ' 0,ω 1≜ ∑ω01 - &lim&ω11 sec ɛi where σ0, σ10 and σ1l are constants and ξi is the angle subtended between the incident flow and the surface normal. Adopting these relationships the effects of atmospheric lift on the satellite inclination, i, and atmospheric drag on the semi-major axis, a, and eccentricity, e, have been investigated. Applications to ANS1 (1974-70A) show that the observed perturbation in i can be ascribed to non-zero σ1l whilst perturbations in a and e produce a constraint equation between the three parameters. Present address: GEC-MARCONI RESEARCH CENTRE, CHELMSFORD, U.K.
NASA Astrophysics Data System (ADS)
Hagberg, Mats; Burström, Lage; Ekman, Anna; Vilhelmsson, Rebecka
2006-12-01
This was a cross-sectional study based on material representing the Swedish work-force from a survey conducted in 1999, 2001 and 2003 by Statistics Sweden. Exposure to whole body vibration (WBV) was prevalent among agricultural, forestry, fishery workers and among plant and machinery operators based on a sample of 40,000 employed persons. Approximately 70% responders, that are 9798 persons answered both the interview and the questionnaire for the analysis of exposure-response. Exposure to WBV at least half the working time was associated with prevalence ratios above two for musculoskeletal symptoms in the low back, neck, shoulder/arm and hand among workers. When the exposure factors lifting and frequent bending were added to a multivariate analysis, surprisingly the magnitude of association was low between low back symptoms and WBV exposure. Interestingly, the relation between WBV exposure and symptoms in the neck, shoulder/arm and hand had the same or higher magnitude of association even when the possible confounders were in the model. For the neck, low back and shoulder/arm there was a visible increase in prevalence ratio (as high as 5 times) when combined exposures of WBV, lifting, frequent bending, twisted posture and noise were included in the analysis.
NASA Technical Reports Server (NTRS)
Penland, Jim A.
1961-01-01
Force tests of a series of right circular cones having semivertex angles ranging from 5 deg to 45 deg and a series of right circular cone-cylinder configurations having semivertex angles ranging from 5 deg to 20 deg and an afterbody fineness ratio of 6 have been made in the Langley 11-inch hypersonic tunnel at a Mach number of 6.83, a Reynolds number of 0.24 x 10.6 per inch, and angles of attack up to 130 deg. An analysis of the results made use of the Newtonian and modified Newtonian theories and the exact theory. A comparison of the experimental data of both cone and cone-cylinder configurations with theoretical calculations shows that the Newtonian concept gives excellent predictions of trends of the force characteristics and the locations with respect to angle of attack of the points of maximum lift, maximum drag, and maximum lift-drag ratio. Both the Newtonian a.nd exact theories give excellent predictions of the sign and value of the initial lift-curve slope. The maximum lift coefficient for conical bodies is nearly constant at a value of 0.5 based on planform area for semivertex angles up to 30 deg. The maximum lift-drag ratio for conical bodies can be expected to be not greater than about 3.5, and this value might be expected only for slender cones having semivertex angles of less than 5 deg. The increments of angle of attack and lift coefficient between the maximum lift-drag ratio and the maximum lift coefficient for conical bodies decrease rapidly with increasing semivertex angles as predicted by the modified Newtonian theory.
ERIC Educational Resources Information Center
van Haastert, Ingrid C.; Groenendaal, Floris; van de Waarsenburg, Maria K.; Eijsermans, Maria J. C.; Koopman-Esseboom, Corine; Jongmans, Marian J.; Helders, Paul J. M.; de Vries, Linda S.
2012-01-01
Aim: To explore whether active head lifting from supine (AHLS) in early infancy is associated with cognitive outcome in the second year of life. Method: The presence of AHLS was always recorded in the notes of infants admitted to our tertiary neonatal intensive care unit. Random sampling was used to pair infants with AHLS with two comparison…
NASA Astrophysics Data System (ADS)
Frank, T. D.; Patanarapeelert, K.; Beek, P. J.
2008-05-01
We derive a fundamental relationship between the mean and the variability of isometric force. The relationship arises from an optimal collection of active motor units such that the force variability assumes a minimum (optimal isometric force). The relationship is shown to be independent of the explicit motor unit properties and of the dynamical features of isometric force production. A constant coefficient of variation in the asymptotic regime and a nonequilibrium fluctuation-dissipation theorem for optimal isometric force are predicted.
Rigorous force field optimization principles based on statistical distance minimization
Vlcek, Lukas; Chialvo, Ariel A.
2015-10-14
We use the concept of statistical distance to define a measure of distinguishability between a pair of statistical mechanical systems, i.e., a model and its target, and show that its minimization leads to general convergence of the model’s static measurable properties to those of the target. We exploit this feature to define a rigorous basis for the development of accurate and robust effective molecular force fields that are inherently compatible with coarse-grained experimental data. The new model optimization principles and their efficient implementation are illustrated through selected examples, whose outcome demonstrates the higher robustness and predictive accuracy of the approach compared to other currently used methods, such as force matching and relative entropy minimization. We also discuss relations between the newly developed principles and established thermodynamic concepts, which include the Gibbs-Bogoliubov inequality and the thermodynamic length.
NASA Technical Reports Server (NTRS)
Ostowari, C.; Naik, D.
1986-01-01
The experimental procedure and aerodynamic force and moment measurements for wind tunnel testing of the three lifting surface configuration (TLC) are described. The influence of nonelliptical lift distributions on lift, drag, and static longitudinal stability are examined; graphs of the lift coefficient versus angle of attack, the pitching moment coefficient, drag coefficient, and lift to drag ratio versus lift coefficient are provided. The TLC data are compared with the conventional tail-aft configuration and the canard-wing configuration; it is concluded that the TLC has better lift and high-lift drag characteristics, lift to drag ratio, and zero-lift moments than the other two configurations. The effects of variations in forward and tail wind incidence angles, gap, stagger, and forward wind span on the drag, lift, longitudinal stability, and zero-lift moments of the configuration are studied.
The Third Air Force/NASA Symposium on Recent Advances in Multidisciplinary Analysis and Optimization
NASA Technical Reports Server (NTRS)
1990-01-01
The third Air Force/NASA Symposium on Recent Advances in Multidisciplinary Analysis and Optimization was held on 24-26 Sept. 1990. Sessions were on the following topics: dynamics and controls; multilevel optimization; sensitivity analysis; aerodynamic design software systems; optimization theory; analysis and design; shape optimization; vehicle components; structural optimization; aeroelasticity; artificial intelligence; multidisciplinary optimization; and composites.
Effects of a Belt on Intra-Abdominal Pressure during Weight Lifting.
1988-03-01
potentially injurious b compressive forces on spinal discs during lifting. To investigate the effects of a standard lifting belt on lAP and lifting mechanics...injurious compressive forces on spinal discs during lifting. To investigate the effects of a standard lifting belt on IAP and lifting ! mechanics...pressure has been estimated to reduce spinal disc compressive forces by up to 40% (6,9,12,14). High intra-abdominal pressures have been recorded during
Optimizing significance testing of astronomical forcing in cyclostratigraphy
NASA Astrophysics Data System (ADS)
Kemp, David B.
2016-12-01
The recognition of astronomically forced (Milankovitch) climate cycles in geological archives marked a major advance in Earth science, revealing a heartbeat within the climate system of general importance and key utility. Power spectral analysis is the primary tool used to facilitate identification of astronomical cycles in stratigraphic data, but commonly employed methods for testing the statistical significance of relatively high narrow-band variance of potential astronomical origin in spectra have been criticized for inadequately balancing the respective probabilities of type I (false positive) and type II (false negative) errors. This has led to suggestions that the importance of astronomical forcing in Earth history is overstated. It can be readily demonstrated, however, that the imperfect nature of the stratigraphic record and the quasiperiodicity of astronomical cycles sets an upper limit on the attainable significance of astronomical signals. Optimized significance testing is that which minimizes the combined probability of type I and type II errors. Numerical simulations of stratigraphically preserved astronomical signals suggest that optimum significance levels at which to reject a null hypothesis of no astronomical forcing are between 0.01 and 0.001 (i.e., 99-99.9% confidence level). This is lower than commonly employed in the literature (90-99% confidence levels). Nevertheless, in consonance with the emergent view from other scientific disciplines, fixed-value null hypothesis significance testing of power spectra is implicitly ill suited to demonstrating astronomical forcing, and the use of spectral analysis remains a difficult and subjective endeavor in the absence of additional supporting evidence.
NASA Technical Reports Server (NTRS)
Chen, A. W.
1971-01-01
Optimum airfoils in the sense of maximum lift coefficient are obtained by a newly developed method. The maximum lift coefficient is achieved by requiring that the turbulent skin friction be zero in the pressure rise region on the upper surface. Under this constraint, the pressure distribution is optimized. The optimum pressure distribution consists of a uniform stagnation pressure on the lower surface, a uniform minimum pressure on the upper surface immediately downstream of the front stagnation point followed by a Stratford zero skin friction pressure rise. When multiple-element airfoils are under consideration, this optimum pressure distribution appears on every element. The parameters used to specify the pressure distribution on each element are the Reynolds number and the normalized trailing edge velocity. The newly developed method of design computes the velocity distribution on a given airfoil and modifies the airfoil contour in a systematic manner until the desired velocity distribution is achieved. There are no limitations on how many elements the airfoil to be designed can have.
NASA Technical Reports Server (NTRS)
Sullivan, J. P.; Schneider, S. P.; Hoffenberg, R.
1996-01-01
The behavior of wakes in adverse pressure gradients is critical to the performance of high-lift systems for transport aircraft. Wake deceleration is known to lead to sudden thickening and the onset of reversed flow; this 'wake bursting' phenomenon can occur while surface flows remain attached. Although known to be important for high-lift systems, few studies of such decelerated wakes exist. In this study, the wake of a flat plate has been subjected to an adverse pressure gradient in a two-dimensional diffuser, whose panels were forced to remain attached by use of slot blowing. Pitot probe surveys, L.D.V. measurements, and flow visualization have been used to investigate the physics of this decelerated wake, through the onset of reversed flow.
A generalized formula for inertial lift on a sphere in microchannels.
Liu, Chao; Xue, Chundong; Sun, Jiashu; Hu, Guoqing
2016-03-07
Inertial microfluidics has been widely used in high-throughput manipulation of particles and cells by hydrodynamic forces, without the aid of externally applied fields. The performance of inertial microfluidic devices largely relies on precise prediction of particle trajectories that are determined by inertial lift acting on particles. The only way to accurately obtain lift forces is by direct numerical simulation (DNS); however, it is burdensome when applied to practical microchannels with complex geometries. Here, we propose a fitting formula for inertial lift on a sphere drawn from DNS data obtained in straight channels. The formula consists of four terms that represent the shear-gradient-induced lift, the wall-induced lift, the slip-shear lift, and the correction of the shear-gradient-induced lift, respectively. Notably, as a function of the parameters of a local flow field, it possesses good adaptability to complex channel geometries. This generalized formula is further implemented in the Lagrangian particle tracking method to realize fast prediction of particle trajectories in two types of widely used microchannels: a long serpentine and a double spiral microchannel, demonstrating its ability to efficiently design and optimize inertial microfluidic devices.
Efficient retrieval of landscape Hessian: Forced optimal covariance adaptive learning
NASA Astrophysics Data System (ADS)
Shir, Ofer M.; Roslund, Jonathan; Whitley, Darrell; Rabitz, Herschel
2014-06-01
Knowledge of the Hessian matrix at the landscape optimum of a controlled physical observable offers valuable information about the system robustness to control noise. The Hessian can also assist in physical landscape characterization, which is of particular interest in quantum system control experiments. The recently developed landscape theoretical analysis motivated the compilation of an automated method to learn the Hessian matrix about the global optimum without derivative measurements from noisy data. The current study introduces the forced optimal covariance adaptive learning (FOCAL) technique for this purpose. FOCAL relies on the covariance matrix adaptation evolution strategy (CMA-ES) that exploits covariance information amongst the control variables by means of principal component analysis. The FOCAL technique is designed to operate with experimental optimization, generally involving continuous high-dimensional search landscapes (≳30) with large Hessian condition numbers (≳104). This paper introduces the theoretical foundations of the inverse relationship between the covariance learned by the evolution strategy and the actual Hessian matrix of the landscape. FOCAL is presented and demonstrated to retrieve the Hessian matrix with high fidelity on both model landscapes and quantum control experiments, which are observed to possess nonseparable, nonquadratic search landscapes. The recovered Hessian forms were corroborated by physical knowledge of the systems. The implications of FOCAL extend beyond the investigated studies to potentially cover other physically motivated multivariate landscapes.
Efficient retrieval of landscape Hessian: forced optimal covariance adaptive learning.
Shir, Ofer M; Roslund, Jonathan; Whitley, Darrell; Rabitz, Herschel
2014-06-01
Knowledge of the Hessian matrix at the landscape optimum of a controlled physical observable offers valuable information about the system robustness to control noise. The Hessian can also assist in physical landscape characterization, which is of particular interest in quantum system control experiments. The recently developed landscape theoretical analysis motivated the compilation of an automated method to learn the Hessian matrix about the global optimum without derivative measurements from noisy data. The current study introduces the forced optimal covariance adaptive learning (FOCAL) technique for this purpose. FOCAL relies on the covariance matrix adaptation evolution strategy (CMA-ES) that exploits covariance information amongst the control variables by means of principal component analysis. The FOCAL technique is designed to operate with experimental optimization, generally involving continuous high-dimensional search landscapes (≳30) with large Hessian condition numbers (≳10^{4}). This paper introduces the theoretical foundations of the inverse relationship between the covariance learned by the evolution strategy and the actual Hessian matrix of the landscape. FOCAL is presented and demonstrated to retrieve the Hessian matrix with high fidelity on both model landscapes and quantum control experiments, which are observed to possess nonseparable, nonquadratic search landscapes. The recovered Hessian forms were corroborated by physical knowledge of the systems. The implications of FOCAL extend beyond the investigated studies to potentially cover other physically motivated multivariate landscapes.
Aerodynamic lift effect on satellite orbits
NASA Technical Reports Server (NTRS)
Karr, G. R.; Cleland, J. G.; Devries, L. L.
1975-01-01
Numerical quadrature is employed to obtain orbit perturbation results from the general perturbation equations. Both aerodynamic lift and drag forces are included in the analysis of the satellite orbit. An exponential atmosphere with and without atmospheric rotation is used. A comparison is made of the perturbations which are caused by atmospheric rotation with those caused by satellite aerodynamic effects. Results indicate that aerodynamic lift effects on the semi-major axis and orbit inclination can be of the same order as the effects of atmosphere rotation depending upon the orientation of the lift vector. The results reveal the importance of including aerodynamic lift effects in orbit perturbation analysis.
Total facelift: forehead lift, midface lift, and neck lift.
Park, Dong Man
2015-03-01
Patients with thick skin mainly exhibit the aging processes of sagging, whereas patients with thin skin develop wrinkles or volume loss. Asian skin is usually thicker than that of Westerners; and thus, the sagging of skin due to aging, rather than wrinkling, is the chief problem to be addressed in Asians. Asian skin is also relatively large in area and thick, implying that the weight of tissue to be lifted is considerably heavier. These factors account for the difficulties in performing a facelift in Asians. Facelifts can be divided into forehead lift, midface lift, and lower face lift. These can be performed individually or with 2-3 procedures combined.
Total Facelift: Forehead Lift, Midface Lift, and Neck Lift
2015-01-01
Patients with thick skin mainly exhibit the aging processes of sagging, whereas patients with thin skin develop wrinkles or volume loss. Asian skin is usually thicker than that of Westerners; and thus, the sagging of skin due to aging, rather than wrinkling, is the chief problem to be addressed in Asians. Asian skin is also relatively large in area and thick, implying that the weight of tissue to be lifted is considerably heavier. These factors account for the difficulties in performing a facelift in Asians. Facelifts can be divided into forehead lift, midface lift, and lower face lift. These can be performed individually or with 2-3 procedures combined. PMID:25798381
Unsteady Lift Generation for MAVs
2010-10-22
canonical pitch - up , pitch -down wing maneuver, in 39th AIAA Fluid Dynamics Conference, AIAA 2009-3687, San Antonio, TX, 22-25 June 2009. [7] C. P. Ellington...unsteady lift generation on three-dimensional flapping wings in the MAV flight regime and, if a leading edge vortex develops at MAV-like Reynolds numbers... wing rotates in a propeller-like motion through a wing stroke angle up to 90 degrees. Unsteady lift and drag force data was acquired throughout the
Influence of Lift Offset on Rotorcraft Performance
NASA Technical Reports Server (NTRS)
Johnson, Wayne
2009-01-01
The influence of lift offset on the performance of several rotorcraft configurations is explored. A lift-offset rotor, or advancing blade concept, is a hingeless rotor that can attain good efficiency at high speed by operating with more lift on the advancing side than on the retreating side of the rotor disk. The calculated performance capability of modern-technology coaxial rotors utilizing a lift offset is examined, including rotor performance optimized for hover and high-speed cruise. The ideal induced power loss of coaxial rotors in hover and twin rotors in forward flight is presented. The aerodynamic modeling requirements for performance calculations are evaluated, including wake and drag models for the high-speed flight condition. The influence of configuration on the performance of rotorcraft with lift-offset rotors is explored, considering tandem and side-by-side rotorcraft as well as wing-rotor lift share.
Influence of Lift Offset on Rotorcraft Performance
NASA Technical Reports Server (NTRS)
Johnson, Wayne
2008-01-01
The influence of lift offset on the performance of several rotorcraft configurations is explored. A lift-offset rotor, or advancing blade concept, is a hingeless rotor that can attain good efficiency at high speed, by operating with more lift on the advancing side than on the retreating side of the rotor disk. The calculated performance capability of modern-technology coaxial rotors utilizing a lift offset is examined, including rotor performance optimized for hover and high-speed cruise. The ideal induced power loss of coaxial rotors in hover and twin rotors in forward flight is presented. The aerodynamic modeling requirements for performance calculations are evaluated, including wake and drag models for the high speed flight condition. The influence of configuration on the performance of rotorcraft with lift-offset rotors is explored, considering tandem and side-by-side rotorcraft as well as wing-rotor lift share.
An Optimization of the Maintenance Assets Distribution Network in the Argentine Air Force
2015-03-26
AN OPTIMIZATION OF THE MAINTENANCE ASSETS DISTRIBUTION NETWORK IN THE ARGENTINE AIR FORCE...copyright protection in the United States. AFIT-ENS-MS-15-M-152 AN OPTIMIZATION OF THE MAINTENANCE ASSETS DISTRIBUTION NETWORK IN THE ARGENTINE AIR...PUBLIC RELEASE; DISTRIBUTION UNLIMITED. AFIT-ENS-MS-15-M-152 AN OPTIMIZATION OF THE MAINTENANCE ASSETS DISTRIBUTION NETWORK IN THE ARGENTINE AIR
Waters, Thomas; Occhipinti, Enrico; Colombini, Daniela; Alvarez-Casado, Enrique; Fox, Robert
2015-01-01
Objective: We seek to develop a new approach for analyzing the physical demands of highly variable lifting tasks through an adaptation of the Revised NIOSH (National Institute for Occupational Safety and Health) Lifting Equation (RNLE) into a Variable Lifting Index (VLI). Background: There are many jobs that contain individual lifts that vary from lift to lift due to the task requirements. The NIOSH Lifting Equation is not suitable in its present form to analyze variable lifting tasks. Method: In extending the prior work on the VLI, two procedures are presented to allow users to analyze variable lifting tasks. One approach involves the sampling of lifting tasks performed by a worker over a shift and the calculation of the Frequency Independent Lift Index (FILI) for each sampled lift and the aggregation of the FILI values into six categories. The Composite Lift Index (CLI) equation is used with lifting index (LI) category frequency data to calculate the VLI. The second approach employs a detailed systematic collection of lifting task data from production and/or organizational sources. The data are organized into simplified task parameter categories and further aggregated into six FILI categories, which also use the CLI equation to calculate the VLI. Results: The two procedures will allow practitioners to systematically employ the VLI method to a variety of work situations where highly variable lifting tasks are performed. Conclusions: The scientific basis for the VLI procedure is similar to that for the CLI originally presented by NIOSH; however, the VLI method remains to be validated. Application: The VLI method allows an analyst to assess highly variable manual lifting jobs in which the task characteristics vary from lift to lift during a shift. PMID:26646300
Global optimization of parameters in the reactive force field ReaxFF for SiOH.
Larsson, Henrik R; van Duin, Adri C T; Hartke, Bernd
2013-09-30
We have used unbiased global optimization to fit a reactive force field to a given set of reference data. Specifically, we have employed genetic algorithms (GA) to fit ReaxFF to SiOH data, using an in-house GA code that is parallelized across reference data items via the message-passing interface (MPI). Details of GA tuning turn-ed out to be far less important for global optimization efficiency than using suitable ranges within which the parameters are varied. To establish these ranges, either prior knowledge can be used or successive stages of GA optimizations, each building upon the best parameter vectors and ranges found in the previous stage. We have finally arrive-ed at optimized force fields with smaller error measures than those published previously. Hence, this optimization approach will contribute to converting force-field fitting from a specialist task to an everyday commodity, even for the more difficult case of reactive force fields.
Optimizing the post-START US strategic nuclear force mix
Leary, D.A.
1990-08-01
The United States and the Soviet Union have been negotiating Strategic Arms Reduction Talks (START) since 1981. This agreement will result in major reductions in the strategic nuclear forces of both countries. This balance between the three legs of the Triad (the number of intercontinental ballistic missiles compared with the number of bombers and the number of submarine-launched ballistic missiles) will become increasingly important. This paper examines the current as well as a proposed post-START force mix , the effect this treaty will have on existing forces, and the changes in targeting priorities. The proposed force mix would require major changes in only the intercontinental ballistic missile leg of the Triad. The submarine-launched ballistic missile and bomber legs would need minimal changes.
Cadwallader, L.C.
1997-03-01
This report presents safety information about powered industrial trucks. The basic lift truck, the counterbalanced sit down rider truck, is the primary focus of the report. Lift truck engineering is briefly described, then a hazard analysis is performed on the lift truck. Case histories and accident statistics are also given. Rules and regulations about lift trucks, such as the US Occupational Safety an Health Administration laws and the Underwriter`s Laboratories standards, are discussed. Safety issues with lift trucks are reviewed, and lift truck safety and reliability are discussed. Some quantitative reliability values are given.
Optimal control of an influenza model with seasonal forcing and age-dependent transmission rates.
Lee, Jeehyun; Kim, Jungeun; Kwon, Hee-Dae
2013-01-21
This study considers an optimal intervention strategy for influenza outbreaks. Variations in the SEIAR model are considered to include seasonal forcing and age structure, and control strategies include vaccination, antiviral treatment, and social distancing such as school closures. We formulate an optimal control problem by minimizing the incidence of influenza outbreaks while considering intervention costs. We examine the effects of delays in vaccine production, seasonal forcing, and age-dependent transmission rates on the optimal control and suggest some optimal strategies through numerical simulations.
Tissue Contraction Force Microscopy for Optimization of Engineered Cardiac Tissue
Schaefer, Jeremy A.
2016-01-01
We developed a high-throughput screening assay that allows for relative comparison of the twitch force of millimeter-scale gel-based cardiac tissues. This assay is based on principles taken from traction force microscopy and uses fluorescent microspheres embedded in a soft polydimethylsiloxane (PDMS) substrate. A gel-forming cell suspension is simply pipetted onto the PDMS to form hemispherical cardiac tissue samples. Recordings of the fluorescent bead movement during tissue pacing are used to determine the maximum distance that the tissue can displace the elastic PDMS substrate. In this study, fibrin gel hemispheres containing human induced pluripotent stem cell-derived cardiomyocytes were formed on the PDMS and allowed to culture for 9 days. Bead displacement values were measured and compared to direct force measurements to validate the utility of the system. The amplitude of bead displacement correlated with direct force measurements, and the twitch force generated by the tissues was the same in 2 and 4 mg/mL fibrin gels, even though the 2 mg/mL samples visually appear more contractile if the assessment were made on free-floating samples. These results demonstrate the usefulness of this assay as a screening tool that allows for rapid sample preparation, data collection, and analysis in a simple and cost-effective platform. PMID:26538167
1990-05-17
e 9 (January-February 1990). Rakow . William M. "Rapid Response Planning." Ma,-ine Corps Ga:zette, 73 (June 1989). Ropecewsaki: Robert R. "Marines...Compilation of LIC References and Bibliography, Vol. II. Langley Air Force Base, Va.: Army-Air Force Center for Low Intensity Conflict, 1982. Metz, Steven
NASA Astrophysics Data System (ADS)
Ye, Chang-Qing; Ma, Guang-Tong; Liu, Kun; Wang, Jia-Su
2017-01-01
The superconducting levitation realized by immersing the high-temperature superconductors (HTSs) into nonuniform magnetic field is deemed promising in a wide range of industrial applications such as maglev transportation and kinetic energy storage. Using a well-established electromagnetic model to mathematically describe the HTS, we have developed an efficient scheme that is capable of intelligently and globally optimizing the permanent magnet guideway (PMG) with single or multiple HTSs levitated above for the maglev transportation applications. With maximizing the levitation force as the principal objective, we optimized the dimensions of a Halbach-derived PMG to observe how the field, current and force distribute inside the HTSs when the optimized situation is achieved. Using a pristine PMG as a reference, we have analyzed the critical issues for enhancing the levitation force through comparing the field, current and force distributions between the optimized and pristine PMGs. It was also found that the optimized dimensions of the PMG are highly dependent upon the levitated HTS. Moreover, the guidance force is not always contradictory to the levitation force and may also be enhanced when the levitation force is prescribed to be the principle objective, depending on the configuration of levitation system and lateral displacement.
NASA Technical Reports Server (NTRS)
1979-01-01
Latest results of programs exploring new propulsion technology for powered-lift aircraft systems are presented. Topics discussed include results from the 'quiet clean short-haul experimental engine' program and progress reports on the 'quiet short-haul research aircraft' and 'tilt-rotor research aircraft' programs. In addition to these NASA programs, the Air Force AMST YC 14 and YC 15 programs were reviewed.
Muscle Synergies May Improve Optimization Prediction of Knee Contact Forces During Walking
Walter, Jonathan P.; Kinney, Allison L.; Banks, Scott A.; D'Lima, Darryl D.; Besier, Thor F.; Lloyd, David G.; Fregly, Benjamin J.
2014-01-01
The ability to predict patient-specific joint contact and muscle forces accurately could improve the treatment of walking-related disorders. Muscle synergy analysis, which decomposes a large number of muscle electromyographic (EMG) signals into a small number of synergy control signals, could reduce the dimensionality and thus redundancy of the muscle and contact force prediction process. This study investigated whether use of subject-specific synergy controls can improve optimization prediction of knee contact forces during walking. To generate the predictions, we performed mixed dynamic muscle force optimizations (i.e., inverse skeletal dynamics with forward muscle activation and contraction dynamics) using data collected from a subject implanted with a force-measuring knee replacement. Twelve optimization problems (three cases with four subcases each) that minimized the sum of squares of muscle excitations were formulated to investigate how synergy controls affect knee contact force predictions. The three cases were: (1) Calibrate+Match where muscle model parameter values were calibrated and experimental knee contact forces were simultaneously matched, (2) Precalibrate+Predict where experimental knee contact forces were predicted using precalibrated muscle model parameters values from the first case, and (3) Calibrate+Predict where muscle model parameter values were calibrated and experimental knee contact forces were simultaneously predicted, all while matching inverse dynamic loads at the hip, knee, and ankle. The four subcases used either 44 independent controls or five synergy controls with and without EMG shape tracking. For the Calibrate+Match case, all four subcases closely reproduced the measured medial and lateral knee contact forces (R2 ≥ 0.94, root-mean-square (RMS) error < 66 N), indicating sufficient model fidelity for contact force prediction. For the Precalibrate+Predict and Calibrate+Predict cases, synergy controls yielded better contact force
Force-based optimization of pseudopotentials for non-equilibrium configurations
NASA Astrophysics Data System (ADS)
Brock, Casey N.; Paikoff, Brandon C.; Md Sallih, Muhammad I.; Tackett, Alan R.; Walker, D. Greg
2016-04-01
We have used a multi-objective genetic algorithm to optimize pseudopotentials for force accuracy and computational efficiency. Force accuracy is determined by comparing interatomic forces generated using the pseudopotentials and forces generated using the full-potential linearized augmented-plane wave method. This force-based optimization approach is motivated by applications where interatomic forces are important, including material interfaces, crystal defects, and molecular dynamics. Our method generates Pareto sets of optimized pseudopotentials containing various compromises between accuracy and efficiency. We have tested our method for LiF, Si0.5Ge0.5, and Mo and compared the performance of our pseudopotentials with pseudopotentials available from the ABINIT library. We show that the optimization can generate pseudopotentials with comparable accuracy (in terms of force matching and equation of state) to pseudopotentials in the literature while sometimes significantly improving computational efficiency. For example, we generated pseudopotentials for one system tested that reduced computational work by 71% without loss of accuracy. These results suggest our method can be used to generate pseudopotentials on demand that are tuned for a user's specific application, affording gains in computational efficiency.
Optimizing Long-Term Capital Planning for Special Operations Forces
2015-06-01
optimization, United States Special Operations Command, capital planning, modernization , Binary Knapsack Model, Bounded Integer Knapsack Model...procurement money over the entire planning horizon. This thesis presents proof-of-principle models to improve the LRCPT by incorporating goal programming...test our models with a 30-year planning horizon including 68 projects and one category of money . We validate the BK model by analyzing the effect of
Optimizing the US Navy’s Combat Logistics Force
2008-01-01
of four basic commodities for each client ship, navigational issues such as slow passages through canals , and the possibility of several client ships... canal or restricted passage). This Figure 2. Worldwide sea route network. This particular network is for a case with 13 battle group customers...shuttle capacity. For exploratory optimization to merely assemble and fil - ter scenario data for errors—preparatory exercises we admit take much more of
Analytic theory of optimal plane change by low aerodynamic forces
NASA Astrophysics Data System (ADS)
Ma, Der-Ming; Wu, Chi-Hang; Vinh, Nguyen X.
The properites of the optimal and sub-optimal solutions to multiple-pass aeroassisted plane change were previously studied in terms of the trajectory variables. The solutions show the strong orbital nature. Then, it is proposed to obtain the variational equations of the orbital elements. We shall use these equations and the approximate control derived in Vinh and Ma (1990) to calculate the trajectories. In this respect, the approximate control law and the transversality condition are transformed in terms of the orbital elements. Following the above results, we can reduce the computational task by further simplification. Within omega and Omega being small and returning to the value of zero after each revolution, we neglect the equations for omega, and Omega. Also, since omega approximately equal to 0, that is alpha approximately equal to f, we can neglect the equation for the alpha and have only three state equations for the integration. Still the computation over several revolutions is long since it is performed using the eccentric anomaly along the osculating orbit as the independent variable. Here, we shall use the method of averaging as applied to the problem of orbit contraction to solve the problem of optimal plane change. This will lead to the integration of a reduced set of two nonlinear equations.
Measuring Lift with the Wright Airfoils
ERIC Educational Resources Information Center
Heavers, Richard M.; Soleymanloo, Arianne
2011-01-01
In this laboratory or demonstration exercise, we mount a small airfoil with its long axis vertical at one end of a nearly frictionless rotating platform. Air from a leaf blower produces a sidewise lift force L on the airfoil and a drag force D in the direction of the air flow (Fig. 1). The rotating platform is kept in equilibrium by adding weights…
Force control of a tri-layer conducting polymer actuator using optimized fuzzy logic control
NASA Astrophysics Data System (ADS)
Itik, Mehmet; Sabetghadam, Mohammadreza; Alici, Gursel
2014-12-01
Conducting polymers actuators (CPAs) are potential candidates for replacing conventional actuators in various fields, such as robotics and biomedical engineering, due to their advantageous properties, which includes their low cost, light weight, low actuation voltage and biocompatibility. As these actuators are very suitable for use in micro-nano manipulation and in injection devices in which the magnitude of the force applied to the target is of crucial importance, the force generated by CPAs needs to be accurately controlled. In this paper, a fuzzy logic (FL) controller with a Mamdani inference system is designed to control the blocking force of a trilayer CPA with polypyrrole electrodes, which operates in air. The particle swarm optimization (PSO) method is employed to optimize the controller’s membership function parameters and therefore enhance the performance of the FL controller. An adaptive neuro-fuzzy inference system model, which can capture the nonlinear dynamics of the actuator, is utilized in the optimization process. The optimized Mamdani FL controller is then implemented on the CPA experimentally, and its performance is compared with a non-optimized fuzzy controller as well as with those obtained from a conventional PID controller. The results presented indicate that the blocking force at the tip of the CPA can be effectively controlled by the optimized FL controller, which shows excellent transient and steady state characteristics but increases the control voltage compared to the non-optimized fuzzy controllers.
The protein folding problem: global optimization of the force fields.
Scheraga, H A; Liwo, A; Oldziej, S; Czaplewski, C; Pillardy, J; Ripoll, D R; Vila, J A; Kazmierkiewicz, R; Saunders, J A; Arnautova, Y A; Jagielska, A; Chinchio, M; Nanias, M
2004-09-01
The evolutionary development of a theoretical approach to the protein folding problem, in our laboratory, is traced. The theoretical foundations and the development of a suitable empirical all-atom potential energy function and a global optimization search are examined. Whereas the all-atom approach has thus far succeeded for relatively small molecules and for alpha-helical proteins containing up to 46 residues, it has been necessary to develop a hierarchical approach to treat larger proteins. In the hierarchical approach to single- and multiple-chain proteins, global optimization is carried out for a simplified united residue (UNRES) description of a polypeptide chain to locate the region in which the global minimum lies. Conversion of the UNRES structures in this region to all-atom structures is followed by a local search in this region. The performance of this approach in successive CASP blind tests for predicting protein structure by an ab initio physics-based method is described. Finally, a recent attempt to compute a folding pathway is discussed.
Secondary lift for magnetically levitated vehicles
Cooper, Richard K.
1976-01-01
A high-speed terrestrial vehicle that is magnetically levitated by means of magnets which are used to induce eddy currents in a continuous electrically conductive nonferromagnetic track to produce magnetic images that repel the inducing magnet to provide primary lift for the vehicle. The magnets are arranged so that adjacent ones have their fields in opposite directions and the magnets are spaced apart a distance that provides a secondary lift between each magnet and the adjacent magnet's image, the secondary lift being maximized by optimal spacing of the magnets.
Numerical investigation on feedback control of flow around an oscillating hydrofoil by Lorentz force
NASA Astrophysics Data System (ADS)
Liu, Zong-Kai; Zhou, Ben-Mou; Liu, Hui-Xing; Ji, Yan-Liang; Huang, Ya-Dong
2013-06-01
In order to improve the hydrodynamic characteristics of a hydrofoil (NACA0012), this paper investigates an oscillating hydrofoil immersed in seawater (an electrically poorly conducting fluid) with feedback control of electromagnetic force (Lorentz force). This method is used in the iterative process, by forecasting the location of boundary layer separation points and attack angle at the next time step and figuring out the optimal force distribution function based on these parameters, then returns to the current time step and applies the optimal force onto the leeside to control the flow separation. Based on the basic flow governing equations, the flow field structures, lift evolutions and energy consumptions (the input impulse of Lorentz force) have been numerically investigated. Numerical results show that with this control, the flow separation could be fully suppressed. Meanwhile, the lift increases dramatically and oscillation is suppressed successfully. Furthermore, under similar lift improvement and control effects, the feedback control optimal ratio is 72.58%.
Unseren, M.A.
1997-09-01
The report reviews a method for modeling and controlling two serial link manipulators which mutually lift and transport a rigid body object in a three dimensional workspace. A new vector variable is introduced which parameterizes the internal contact force controlled degrees of freedom. A technique for dynamically distributing the payload between the manipulators is suggested which yields a family of solutions for the contact forces and torques the manipulators impart to the object. A set of rigid body kinematic constraints which restricts the values of the joint velocities of both manipulators is derived. A rigid body dynamical model for the closed chain system is first developed in the joint space. The model is obtained by generalizing the previous methods for deriving the model. The joint velocity and acceleration variables in the model are expressed in terms of independent pseudovariables. The pseudospace model is transformed to obtain reduced order equations of motion and a separate set of equations governing the internal components of the contact forces and torques. A theoretic control architecture is suggested which explicitly decouples the two sets of equations comprising the model. The controller enables the designer to develop independent, non-interacting control laws for the position control and internal force control of the system.
Muscle optimization techniques impact the magnitude of calculated hip joint contact forces.
Wesseling, Mariska; Derikx, Loes C; de Groote, Friedl; Bartels, Ward; Meyer, Christophe; Verdonschot, Nico; Jonkers, Ilse
2015-03-01
In musculoskeletal modelling, several optimization techniques are used to calculate muscle forces, which strongly influence resultant hip contact forces (HCF). The goal of this study was to calculate muscle forces using four different optimization techniques, i.e., two different static optimization techniques, computed muscle control (CMC) and the physiological inverse approach (PIA). We investigated their subsequent effects on HCFs during gait and sit to stand and found that at the first peak in gait at 15-20% of the gait cycle, CMC calculated the highest HCFs (median 3.9 times peak GRF (pGRF)). When comparing calculated HCFs to experimental HCFs reported in literature, the former were up to 238% larger. Both static optimization techniques produced lower HCFs (median 3.0 and 3.1 pGRF), while PIA included muscle dynamics without an excessive increase in HCF (median 3.2 pGRF). The increased HCFs in CMC were potentially caused by higher muscle forces resulting from co-contraction of agonists and antagonists around the hip. Alternatively, these higher HCFs may be caused by the slightly poorer tracking of the net joint moment by the muscle moments calculated by CMC. We conclude that the use of different optimization techniques affects calculated HCFs, and static optimization approached experimental values best.
Optimal impedance on transmission of Lorentz force EMATs
NASA Astrophysics Data System (ADS)
Isla, Julio; Seher, Matthias; Challis, Richard; Cegla, Frederic
2016-02-01
Electromagnetic-acoustic transducers (EMATs) are attractive for non-destructive inspections because direct contact with the specimen under test is not required. This advantage comes at a high cost in sensitivity and therefore it is important to optimise every aspect of an EMAT. The signal strength produced by EMATs is in part determined by the coil impedance regardless of the transduction mechanism (e.g. Lorentz force, magnetostriction, etc.). There is very little literature on how to select the coil impedance that maximises the wave intensity; this paper addresses that gap. A transformer circuit is used to model the interaction between the EMAT coil and the eddy currents that are generated beneath the coil in the conducting specimen. Expressions for the coil impedances that satisfy the maximum efficiency and maximum power transfer conditions on transmission are presented. To support this analysis, a tunable coil that consists of stacked identical thin layers independently accessed is used so that the coil inductance can be modified while leaving the radiation pattern of the EMAT unaffected.
Sensorimotor Memory Biases Weight Perception During Object Lifting
van Polanen, Vonne; Davare, Marco
2015-01-01
When lifting an object, the brain uses visual cues and an internal object representation to predict its weight and scale fingertip forces accordingly. Once available, tactile information is rapidly integrated to update the weight prediction and refine the internal object representation. If visual cues cannot be used to predict weight, force planning relies on implicit knowledge acquired from recent lifting experience, termed sensorimotor memory. Here, we investigated whether perception of weight is similarly biased according to previous lifting experience and how this is related to force scaling. Participants grasped and lifted series of light or heavy objects in a semi-randomized order and estimated their weights. As expected, we found that forces were scaled based on previous lifts (sensorimotor memory) and these effects increased depending on the length of recent lifting experience. Importantly, perceptual weight estimates were also influenced by the preceding lift, resulting in lower estimations after a heavy lift compared to a light one. In addition, weight estimations were negatively correlated with the magnitude of planned force parameters. This perceptual bias was only found if the current lift was light, but not heavy since the magnitude of sensorimotor memory effects had, according to Weber’s law, relatively less impact on heavy compared to light objects. A control experiment tested the importance of active lifting in mediating these perceptual changes and showed that when weights are passively applied on the hand, no effect of previous sensory experience is found on perception. These results highlight how fast learning of novel object lifting dynamics can shape weight perception and demonstrate a tight link between action planning and perception control. If predictive force scaling and actual object weight do not match, the online motor corrections, rapidly implemented to downscale forces, will also downscale weight estimation in a proportional manner
An actuator line model simulation with optimal body force projection length scales
NASA Astrophysics Data System (ADS)
Martinez-Tossas, Luis; Churchfield, Matthew J.; Meneveau, Charles
2016-11-01
In recent work (Martínez-Tossas et al. "Optimal smoothing length scale for actuator line models of wind turbine blades", preprint), an optimal body force projection length-scale for an actuator line model has been obtained. This optimization is based on 2-D aerodynamics and is done by comparing an analytical solution of inviscid linearized flow over a Gaussian body force to the potential flow solution of flow over a Joukowski airfoil. The optimization provides a non-dimensional optimal scale ɛ / c for different Joukowski airfoils, where ɛ is the width of the Gaussian kernel and c is the chord. A Gaussian kernel with different widths in the chord and thickness directions can further reduce the error. The 2-D theory developed is extended by simulating a full scale rotor using the optimal body force projection length scales. Using these values, the tip losses are captured by the LES and thus, no additional explicit tip-loss correction is needed for the actuator line model. The simulation with the optimal values provides excellent agreement with Blade Element Momentum Theory. This research is supported by the National Science Foundation (Grant OISE-1243482, the WINDINSPIRE project).
Optimal Shape for Forces and Moments on a Multi-Element Hydrofoil
2007-10-01
Hydrofoil DISTRIBUTION: Approved for public release; distribution is unlimited. This paper is part of the following report: TITLE: International...Michigan, 5-8 August 2007 Optimal Shape for Forces and Moments on a Multi-Element Hydrofoil Yu-Tai Lee1, Vineet Ahuja 2, Ashvin Hosangadi 2 and Michael...forces and The Tab Assisted Control (TAC) foil used for moments acting on the hydrofoil with adequate underwater control surfaces, shown in Fig. la, was
Hudes, Gary R.; Carducci, Michael A.; Choueiri, Toni K.; Esper, Peg; Jonasch, Eric; Kumar, Rashmi; Margolin, Kim A.; Michaelson, M. Dror; Motzer, Robert J.; Pili, Roberto; Roethke, Susan; Srinivas, Sandy
2015-01-01
The outcome of patients with metastatic renal cell carcinoma has been substantially improved with administration of the currently available molecularly targeted therapies. However, proper selection of therapy and management of toxicities remain challenging. NCCN convened a multidisciplinary task force panel to address the clinical issues associated with these therapies in attempt to help practicing oncologists optimize patient outcomes. This report summarizes the background data presented at the task force meeting and the ensuing discussion. PMID:21335444
Optimization of force in the Wingate Test for children with a neuromuscular disease.
Van Mil, E; Schoeber, N; Calvert, R E; Bar-or, O
1996-09-01
Determination of the optimal braking force (Fopt in the Wingate Anaerobic Test (WAnT) among healthy people has been determined based on total body mass. The abnormal muscle mass to total body mass ratio in individuals with neuromuscular disabilities invalidates this approach. This study was intended to validate the optimal force obtained from the Force Velocity Test (FVT) and from an estimate of lean arm volume as two alternative predictors for the Fopt. Twenty-eight 6- to 16-yr-old girls and boys with neuromuscular diseases performed the arm WAnT six times (three trials in each of two visits) against various braking forces to directly determine Fopt. They also performed the arm Force Velocity Test to assess optimal force (FoptFVT). Lean arm volume was determined by anthropometry (ALV) and water displacement (WLV). Correlations between Fopt on the one hand, and FoptFVT, WLV, and ALV on the other, were: R2 = 0.91, 0.81, and 0.82, respectively. Total body mass was the worst predictor (R2 = 0.65). Thus, Fopt obtained from either FVT or lean arm volume estimate is a useful predictor of the Fopt for mean power of the WAnT in children and adolescents with a neuromuscular disability.
Optimization of cascade blade mistuning under flutter and forced response constraints
NASA Technical Reports Server (NTRS)
Murthy, D. V.; Haftka, R. T.
1984-01-01
In the development of modern turbomachinery, problems of flutter instabilities and excessive forced response of a cascade of blades that were encountered have often turned out to be extremely difficult to eliminate. The study of these instabilities and the forced response is complicated by the presence of mistuning; that is, small differences among the individual blades. The theory of mistuned cascade behavior shows that mistuning can have a beneficial effect on the stability of the rotor. This beneficial effect is produced by the coupling between the more stable and less stable flutter modes introduced by mistuning. The effect of mistuning on the forced response can be either beneficial or adverse. Kaza and Kielb have studied the effects of two types of mistuning on the flutter and forced response: alternate mistuning where alternte blades are identical and random mistuning. The objective is to investigate other patterns of mistuning which maximize the beneficial effects on the flutter and forced response of the cascade. Numerical optimization techniques are employed to obtain optimal mistuning patterns. The optimization program seeks to minimize the amount of mistuning required to satisfy constraints on flutter speed and forced response.
Design optimization of piezoresistive cantilevers for force sensing in air and water
Doll, Joseph C.; Park, Sung-Jin; Pruitt, Beth L.
2009-01-01
Piezoresistive cantilevers fabricated from doped silicon or metal films are commonly used for force, topography, and chemical sensing at the micro- and macroscales. Proper design is required to optimize the achievable resolution by maximizing sensitivity while simultaneously minimizing the integrated noise over the bandwidth of interest. Existing analytical design methods are insufficient for modeling complex dopant profiles, design constraints, and nonlinear phenomena such as damping in fluid. Here we present an optimization method based on an analytical piezoresistive cantilever model. We use an existing iterative optimizer to minimimize a performance goal, such as minimum detectable force. The design tool is available as open source software. Optimal cantilever design and performance are found to strongly depend on the measurement bandwidth and the constraints applied. We discuss results for silicon piezoresistors fabricated by epitaxy and diffusion, but the method can be applied to any dopant profile or material which can be modeled in a similar fashion or extended to other microelectromechanical systems. PMID:19865512
Experimental determination of baseball spin and lift.
Alaways, L W; Hubbard, M
2001-05-01
The aim of this study was to develop a new method for the determination of lift on spinning baseballs. Inertial trajectories of (a) ball surface markers during the first metre of flight and (b) the centre of mass trajectory near home-plate were measured in a pitch using high-speed video. A theoretical model was developed, incorporating aerodynamic Magnus-Robins lift, drag and cross forces, which predicts the centre of mass and marker trajectories. Parameters including initial conditions and aerodynamic coefficients were estimated iteratively by minimizing the error between predicted and measured trajectories. We compare the resulting lift coefficients and spin parameter values with those of previous studies. Lift on four-seam pitches can be as much as three times that of two-seam pitches, although this disparity is reduced for spin parameters greater than 0.4.
Optimization of the energy complex “NPP-accumulator” in case of force majeure
NASA Astrophysics Data System (ADS)
Zaluzhnaya, G.; Zagrebaev, A.
2017-01-01
We consider a problem of optimization of NPP with accumulator operation mode in case of force majeure. A mathematical formulation and solving of problem of energy output’s time behavior is provided. A mathematical formulation and solving of problem of energy’s optimum allocation to consumers with different priorities. Mathematically, the problem reduces to linear programming problem. We received that optimal time behavior is uniform energy output, and one should start with consumer with highest priority.
NASA Astrophysics Data System (ADS)
Scheller, Johannes; Braza, Marianna; Triantafyllou, Michael
2016-11-01
Bats and other animals rapidly change their wingspan in order to control the aerodynamic forces. A NACA0013 type airfoil with dynamically changing span is proposed as a simple model to experimentally study these biomimetic morphing wings. Combining this large-scale morphing with inline motion allows to control both force magnitude and direction. Force measurements are conducted in order to analyze the impact of the 4 degree of freedom flapping motion on the flow. A blade-element theory augmented unsteady aerodynamic model is then used to derive optimal flapping trajectories.
Modeling lift operations with SASmacr Simulation Studio
NASA Astrophysics Data System (ADS)
Kar, Leow Soo
2016-10-01
Lifts or elevators are an essential part of multistorey buildings which provide vertical transportation for its occupants. In large and high-rise apartment buildings, its occupants are permanent, while in buildings, like hospitals or office blocks, the occupants are temporary or users of the buildings. They come in to work or to visit, and thus, the population of such buildings are much higher than those in residential apartments. It is common these days that large office blocks or hospitals have at least 8 to 10 lifts serving its population. In order to optimize the level of service performance, different transportation schemes are devised to control the lift operations. For example, one lift may be assigned to solely service the even floors and another solely for the odd floors, etc. In this paper, a basic lift system is modelled using SAS Simulation Studio to study the effect of factors such as the number of floors, capacity of the lift car, arrival rate and exit rate of passengers at each floor, peak and off peak periods on the system performance. The simulation is applied to a real lift operation in Sunway College's North Building to validate the model.
Dynamic topology multi force particle swarm optimization algorithm and its application
NASA Astrophysics Data System (ADS)
Chen, Dongning; Zhang, Ruixing; Yao, Chengyu; Zhao, Zheyu
2016-01-01
Particle swarm optimization (PSO) algorithm is an effective bio-inspired algorithm but it has shortage of premature convergence. Researchers have made some improvements especially in force rules and population topologies. However, the current algorithms only consider a single kind of force rules and lack consideration of comprehensive improvement in both multi force rules and population topologies. In this paper, a dynamic topology multi force particle swarm optimization (DTMFPSO) algorithm is proposed in order to get better search performance. First of all, the principle of the presented multi force particle swarm optimization (MFPSO) algorithm is that different force rules are used in different search stages, which can balance the ability of global and local search. Secondly, a fitness-driven edge-changing (FE) topology based on the probability selection mechanism of roulette method is designed to cut and add edges between the particles, and the DTMFPSO algorithm is proposed by combining the FE topology with the MFPSO algorithm through concurrent evolution of both algorithm and structure in order to further improve the search accuracy. Thirdly, Benchmark functions are employed to evaluate the performance of the DTMFPSO algorithm, and test results show that the proposed algorithm is better than the well-known PSO algorithms, such as µPSO, MPSO, and EPSO algorithms. Finally, the proposed algorithm is applied to optimize the process parameters for ultrasonic vibration cutting on SiC wafer, and the surface quality of the SiC wafer is improved by 12.8% compared with the PSO algorithm in Ref. [25]. This research proposes a DTMFPSO algorithm with multi force rules and dynamic population topologies evolved simultaneously, and it has better search performance.
Gunter, L.W.
1992-08-11
A device is described for lifting catwalk grates comprising an elongated bent member with a handle at one end and a pair of notched braces and a hook at the opposite end that act in conjunction with each other to lock onto the grate and give mechanical advantage in lifting the grate. 10 figs.
Gunter, Larry W.
1992-01-01
A device for lifting catwalk grates comprising an elongated bent member with a handle at one end and a pair of notched braces and a hook at the opposite end that act in conjunction with each other to lock onto the grate and give mechanical advantage in lifting the grate.
NASA Technical Reports Server (NTRS)
Sullivan, John; Schneider, Steve; Campbell, Bryan; Bucci, Greg; Boone, Rod; Torgerson, Shad; Erausquin, Rick; Knauer, Chad
1994-01-01
The current program is aimed at providing a physical picture of the flow physics and quantitative turbulence data of the interaction of a high Reynolds number wake with a flap element. The impact of high lift on aircraft performance is studied for a 150 passenger transport aircraft with the goal of designing optimum high lift systems with minimum complexity.
NASA Technical Reports Server (NTRS)
Weddendorf, Bruce
1993-01-01
Portable lifting machine assists user in rising from seated position to standing position, or in sitting down. Small and light enough to be carried like briefcase. Used on variety of chairs and benches. Upholstered aluminum box houses mechanism of lifting seat. Springs on outer shaft-and-arm subassembly counterbalance part of user's weight to assist motor.
ERIC Educational Resources Information Center
Silva, J.; Soares, A. A.
2010-01-01
The conventional explanation of aerodynamic lift based on Bernoulli's equation is one of the most common mistakes in presentations to school students and is found in children's science books. The fallacies in this explanation together with an alternative explanation for aerofoil lift have already been presented in an excellent article by Babinsky…
NASA Technical Reports Server (NTRS)
Weddendorf, Bruce (Inventor)
1994-01-01
A portable seat lift that can help individuals either (1) lower themselves to a sitting position or (2) raise themselves to a standing position is presented. The portable seat lift consists of a seat mounted on a base with two levers, which are powered by a drive unit.
NASA Technical Reports Server (NTRS)
Huff, Edward M.; Lewicki, David G.; Tumer, Irem Y.; Decker, Harry; Barszez, Eric; Zakrajsek, James J.; Norvig, Peter (Technical Monitor)
2000-01-01
As part of a collaborative research program between NASA Ames Research Center (ARC), NASA Glenn Research Center (GRC), and the US Army Laboratory, a series of experiments is being performed in GRC's 500 HP OH-58 Transmission Test Rig facility and ARC's AH-I Cobra and OH-58c helicopters. The findings reported in this paper were drawn from Phase-I of a two-phase test-rig experiment, and are focused on the vibration response of an undamaged pinion gear operating in the transmission test rig. To simulate actual flight conditions, the transmission system was run at three torque levels, as well as two mast lifting and two mast bending levels. The test rig was also subjected to disassembly and reassembly of the main pinion housing to simulate the effect of maintenance operations. An analysis of variance based on the total power of the spectral distribution indicates the relative effect of each experimental factor, including Wong interactions with torque. Reinstallation of the main pinion assembly is shown to introduce changes in the vibration signature, suggesting the possibility of a strong effect of maintenance on HUMS design and use. Based on these results, further research will be conducted to compare these vibration responses with actual OH58c helicopter transmission vibration patterns.
Stredde, H.; /Fermilab
1998-05-27
A lifting fixture has been designed to handle the Samus counters. These counters are being removed from the D-zero area and will be transported off site for further use at another facility. This fixture is designed specifically for this particular application and will be transferred along with the counters. The future use of these counters may entail installation at a facility without access to a crane and therefore a lift fixture suitable for both crane and/or fork lift usage has been created The counters weigh approximately 3000 lbs. and have threaded rods extended through the counter at the top comers for lifting. When these counters were first handled/installed these rods were used in conjunction with appropriate slings and handled by crane. The rods are secured with nuts tightened against the face of the counter. The rod thread is M16 x 2({approx}.625-inch dia.) and extends 2-inch (on average) from the face of the counter. It is this cantilevered rod that the lift fixture engages with 'C' style plates at the four top comers. The strongback portion of the lift fixture is a steel rectangular tube 8-inch (vertical) x 4-inch x .25-inch wall, 130-inch long. 1.5-inch square bars are welded perpendicular to the long axis of the rectangular tube at the appropriate lift points and the 'C' plates are fastened to these bars with 3/4-10 high strength bolts -grade 8. Two short channel sections are positioned-welded-to the bottom of the rectangular tube on 40 feet centers, which are used as locators for fork lift tines. On the top are lifting eyes for sling/crane usage and are rated at 3500 lbs. safe working load each - vertical lift only.
Parameterization and optimization of the menthol force field for molecular dynamics simulations.
Jasik, Mateusz; Szefczyk, Borys
2016-10-01
Menthol's various biological properties render it a useful component for medical and cosmetological applications, while its three centers of asymmetry mean that it can be used in a range of organic reactions. Menthol-substituted ionic liquids (ILs) have been found to exhibit promising antimicrobial and antielectrostatic properties, as well as being useful in organic catalysis and biochemical studies. However, so far, a force field designed and validated specifically for the menthol molecule has not been constructed. In the present work, the validation and optimization of force field parameters with regard to the ability to reproduce the macroscopic properties of menthol is presented. The set of optimized potentials for liquid simulations all atom (OPLS-AA) compatible parameters was tested and carefully tuned. The refinement of parameters included fitting of partial atomic charges, optimization of Lennard-Jones parameters, and recalculation of the dihedral angle parameters needed to reproduce quantum energy profiles. To validate the force field, a variety of physicochemical properties were calculated for liquid menthol. Both thermodynamic and kinetic properties were taken into account, including density, surface tension, enthalpy of vaporization, and shear viscosity. The obtained force field was proven to accurately reproduce the properties of the investigated compound while being fully compatible with the OPLS-AA force field.
Vergadou, Niki; Androulaki, Eleni; Hill, Jörg-Rüdiger; Economou, Ioannis G
2016-03-07
Imidazolium-based ionic liquids (ILs) incorporating the tricyanomethanide ([TCM(-)]) anion are studied using an optimized classical force field. These ILs are very promising candidates for use in a wide range of cutting-edge technologies and, to our knowledge, it is the first time that this IL family is subject to a molecular simulation study with the use of a classical atomistic force field. The [C4mim(+)][TCM(-)] ionic liquid at 298.15 K and at atmospheric pressure was used as the basis for force field optimization which primarily involved the determination of the Lennard-Jones parameters of [TCM(-)] and the implementation of three quantum mechanical schemes for the calculation of the partial charge distribution and the identification of the appropriate scaling factor for the reduction of the total ionic charge. The optimized force field was validated by performing simulations of the 1-alkyl-3-methylimidazolium tricyanomethanide ([Cnmim(+)][TCM(-)], n = 2, 4, 6, and 8) IL family at various temperatures. The results for density, self-diffusivity and viscosity are in very good agreement with the available experimental data for all ILs verifying that the force field reliably reproduces the behaviour of the imidazolium-based [TCM(-)] IL family in a wide temperature range. Furthermore, a detailed analysis of the microscopic structure and the complex dynamic behaviour of the ILs under study was performed.
Optimal satellite formation reconfiguration actuated by inter-satellite electromagnetic forces
NASA Astrophysics Data System (ADS)
Cai, Wei-wei; Yang, Le-ping; Zhu, Yan-wei; Zhang, Yuan-wen
2013-08-01
The inter-satellite electromagnetic forces generated by the magnetic dipoles on neighboring satellites provide an attractive control actuation alternative for satellite formation flight due to the prominent advantages of no propellant consumption or plume contamination. However, the internal force nature as well as the inherent high nonlinearity and coupling of electromagnetic forces bring unique dynamic characteristics and challenges. This paper investigates the nonlinear translational dynamics, trajectory planning and control of formation reconfiguration actuated by inter-satellite electromagnetic forces. The nonlinear translational dynamic model is derived by utilizing analytical mechanics theory; and analysis on the dynamic characteristics is put forward. Optimal reconfiguration trajectories of electromagnetic force actuated formation are studied by applying optimal control theory and the Gauss pseudospectral method. Considering the high nonlinearity and uncertainty in the dynamic model, an inner-and-outer loop combined control strategy based on feedback linearization theory and adaptive terminal sliding mode control is proposed with finite-time convergence capability and good robust performance. Theoretical analysis and numerical simulation results are presented to validate the feasibility of the proposed translational model, reconfiguration trajectory optimization approach and control strategy.
Network-Based Approach to Optimize Personnel Recovery for the Joint Force
2011-05-26
NUMBER Andrew M . Smith , Major, USAF 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES...NETWORK-BASED APPROACH TO OPTIMIZE PERSONNEL RECOVERY FOR THE JOINT FORCE by Andrew M . Smith Major, USAF A paper submitted to the
Allometry of hummingbird lifting performance.
Altshuler, D L; Dudley, R; Heredia, S M; McGuire, J A
2010-03-01
Vertical lifting performance in 67 hummingbird species was studied across a 4000 m elevational gradient. We used the technique of asymptotic load-lifting to elicit maximum sustained muscle power output during loaded hovering flight. Our analysis incorporated direct measurements of maximum sustained load and simultaneous wingbeat kinematics, together with aerodynamic estimates of mass-specific mechanical power output, all within a robust phylogenetic framework for the Trochilidae. We evaluated key statistical factors relevant to estimating slopes for allometric relationships by performing analyses with and without phylogenetic information, and incorporating species-specific measurement error. We further examined allometric relationships at different elevations because this gradient represents a natural experiment for studying physical challenges to animal flight mechanics. Maximum lifting capacity (i.e. vertical force production) declined with elevation, but was either isometric or negatively allometric with respect to both body and muscle mass, depending on elevational occurrence of the corresponding taxa. Maximum relative muscle power output exhibited a negative allometry with respect to muscle mass, supporting theoretical predictions from muscle mechanics.
Optimization of levitation and guidance forces in a superconducting Maglev system
NASA Astrophysics Data System (ADS)
Yildizer, Irfan; Cansiz, Ahmet; Ozturk, Kemal
2016-09-01
Optimization of the levitation for superconducting Maglev systems requires effective use of vertical and guidance forces during the operation. In this respect the levitation and guidance forces in terms of various permanent magnet array configurations are analyzed. The arrangements of permanent magnet arrays interacting with the superconductor are configured for the purpose of increasing the magnetic flux density. According to configurations, modeling the interaction forces between the permanent magnet and the superconductor are established in terms of the frozen image model. The model is complemented with the analytical calculations and provides a reasonable agreement with the experiments. The agreement of the analytical calculation associated with the frozen image model indicates a strong case to establish an optimization, in which provides preliminary analysis before constructing more complex Maglev system.
Cholewicki, J; McGill, S M
1994-10-01
There are two basic approaches to estimate individual muscle forces acting on a joint, given the indeterminacy of moment balance equations: optimization and electromyography (EMG) assisted. Each approach is characterized by unique advantages and liabilities. With this in mind, a new hybrid method which combines the advantages of both of these traditional approaches, termed 'EMG assisted optimization' (EMGAO), was described. In this method, minimal adjustments are applied to the individual muscle forces estimated from EMG, so that all moment equilibrium equations are satisfied in three dimensions. The result is the best possible match between physiologically observed muscle activation patterns and the predicted forces, while satisfying the moment constraints about all three joint axes. Several forms of the objective function are discussed and their effect on individual muscle adjustments is illustrated in a simple two-dimensional example.
Pyzer-Knapp, Edward O; Thompson, Hugh P G; Day, Graeme M
2016-08-01
We present a re-parameterization of a popular intermolecular force field for describing intermolecular interactions in the organic solid state. Specifically we optimize the performance of the exp-6 force field when used in conjunction with atomic multipole electrostatics. We also parameterize force fields that are optimized for use with multipoles derived from polarized molecular electron densities, to account for induction effects in molecular crystals. Parameterization is performed against a set of 186 experimentally determined, low-temperature crystal structures and 53 measured sublimation enthalpies of hydrogen-bonding organic molecules. The resulting force fields are tested on a validation set of 129 crystal structures and show improved reproduction of the structures and lattice energies of a range of organic molecular crystals compared with the original force field with atomic partial charge electrostatics. Unit-cell dimensions of the validation set are typically reproduced to within 3% with the re-parameterized force fields. Lattice energies, which were all included during parameterization, are systematically underestimated when compared with measured sublimation enthalpies, with mean absolute errors of between 7.4 and 9.0%.
Pyzer-Knapp, Edward O.; Thompson, Hugh P. G.; Day, Graeme M.
2016-01-01
We present a re-parameterization of a popular intermolecular force field for describing intermolecular interactions in the organic solid state. Specifically we optimize the performance of the exp-6 force field when used in conjunction with atomic multipole electrostatics. We also parameterize force fields that are optimized for use with multipoles derived from polarized molecular electron densities, to account for induction effects in molecular crystals. Parameterization is performed against a set of 186 experimentally determined, low-temperature crystal structures and 53 measured sublimation enthalpies of hydrogen-bonding organic molecules. The resulting force fields are tested on a validation set of 129 crystal structures and show improved reproduction of the structures and lattice energies of a range of organic molecular crystals compared with the original force field with atomic partial charge electrostatics. Unit-cell dimensions of the validation set are typically reproduced to within 3% with the re-parameterized force fields. Lattice energies, which were all included during parameterization, are systematically underestimated when compared with measured sublimation enthalpies, with mean absolute errors of between 7.4 and 9.0%. PMID:27484370
Wingless Flight: The Lifting Body Story
NASA Technical Reports Server (NTRS)
Reed, R. Dale; Lister, Darlene (Editor); Huntley, J. D. (Editor)
1997-01-01
Force Base (AFB) in California were experiencing our own fascination with the lifting-body concept. A model-aircraft builder and private pilot on my own time, I found the lifting-body idea intriguing. I built a model based on Eggers' design, tested it repeatedly, made modifications in its control and balance characteristics along the way, then eventually presented the concept to others at the Center, using a film of its flights that my wife, Donna and I had made with our 8-mm home camera.
HSR High Lift Program and PCD2 Update
NASA Technical Reports Server (NTRS)
Kemmerly, Guy T.; Coen, Peter; Meredith, Paul; Clark, Roger; Hahne, Dave; Smith, Brian
1999-01-01
The mission of High-Lift Technology is to develop technology allowing the design of practical high lift concepts for the High-Speed Civil Transport (HSCT) in order to: 1) operate safely and efficiently; and 2) reduce terminal control area and community noise. In fulfilling this mission, close and continuous coordination will be maintained with other High-Speed Research (HSR) technology elements in order to support optimization of the overall airplane (rather than just the high lift system).
Optimization of the OPLS-AA Force Field for Long Hydrocarbons.
Siu, Shirley W I; Pluhackova, Kristyna; Böckmann, Rainer A
2012-04-10
The all-atom optimized potentials for liquid simulations (OPLS-AA) force field is a popular force field for simulating biomolecules. However, the current OPLS parameters for hydrocarbons developed using short alkanes cannot reproduce the liquid properties of long alkanes in molecular dynamics simulations. Therefore, the extension of OPLS-AA to (phospho)lipid molecules required for the study of biological membranes was hampered in the past. Here, we optimized the OPLS-AA force field for both short and long hydrocarbons. Following the framework of the OPLS-AA parametrization, we refined the torsional parameters for hydrocarbons by fitting to the gas-phase ab initio energy profiles calculated at the accurate MP2/aug-cc-pVTZ theory level. Additionally, the depth of the Lennard-Jones potential for methylene hydrogen atoms was adjusted to reproduce the densities and the heats of vaporization of alkanes and alkenes of different lengths. Optimization of partial charges finally allowed to reproduce the gel-to-liquid-phase transition temperature for pentadecane and solvation free energies. It is shown that the optimized parameter set (L-OPLS) yields improved hydrocarbon diffusion coefficients, viscosities, and gauche-trans ratios. Moreover, its applicability for lipid bilayer simulations is shown for a GMO bilayer in its liquid-crystalline phase.
Optimization of Active Muscle Force-Length Models Using Least Squares Curve Fitting.
Mohammed, Goran Abdulrahman; Hou, Ming
2016-03-01
The objective of this paper is to propose an asymmetric Gaussian function as an alternative to the existing active force-length models, and to optimize this model along with several other existing models by using the least squares curve fitting method. The minimal set of coefficients is identified for each of these models to facilitate the least squares curve fitting. Sarcomere simulated data and one set of rabbits extensor digitorum II experimental data are used to illustrate optimal curve fitting of the selected force-length functions. The results shows that all the curves fit reasonably well with the simulated and experimental data, while the Gordon-Huxley-Julian model and asymmetric Gaussian function are better than other functions in terms of statistical test scores root mean squared error and R-squared. However, the differences in RMSE scores are insignificant (0.3-6%) for simulated data and (0.2-5%) for experimental data. The proposed asymmetric Gaussian model and the method of parametrization of this and the other force-length models mentioned above can be used in the studies on active force-length relationships of skeletal muscles that generate forces to cause movements of human and animal bodies.
Lift mechanics of downhill skiing and snowboarding
NASA Astrophysics Data System (ADS)
Wu, Qianhong; Igci, Yesim; Andreopoulos, Yiannis
2005-11-01
A simplified mathematical model is derived to describe the lift mechanics of downhill skiing and snowboarding, where the lift contributions due to both the transiently trapped air and the compressed snow crystals are determined for the first time. Using Shimizu's empirical relation to predict the local variation in snow permeability, we employ force and moment analysis to predict the angle of attack of the planing surface, the penetration depth at the leading edge and the shift in the center of pressure for two typical snow types, fresh and wind-packed snow. We present numerical solutions for snowboarding and asymptotic analytic solutions for skiing for the case where there are no edging or turning maneuvers, which shows that approximately 50% of the total lift force is generated by the trapped air in the case of wind-packed snow for snowboarding and 40% for skiing. For highly permeable fresh powder snow the lift contribution from the pore air pressure drops to < 20%. This new theory is an extension of the series of studies on lift generation in highly compressible porous media.
FREIGHT CONTAINER LIFTING STANDARD
POWERS DJ; SCOTT MA; MACKEY TC
2010-01-13
This standard details the correct methods of lifting and handling Series 1 freight containers following ISO-3874 and ISO-1496. The changes within RPP-40736 will allow better reading comprehension, as well as correcting editorial errors.
Advanced underwater lift device
NASA Technical Reports Server (NTRS)
Flanagan, David T.; Hopkins, Robert C.
1993-01-01
Flexible underwater lift devices ('lift bags') are used in underwater operations to provide buoyancy to submerged objects. Commercially available designs are heavy, bulky, and awkward to handle, and thus are limited in size and useful lifting capacity. An underwater lift device having less than 20 percent of the bulk and less than 10 percent of the weight of commercially available models was developed. The design features a dual membrane envelope, a nearly homogeneous envelope membrane stress distribution, and a minimum surface-to-volume ratio. A proof-of-concept model of 50 kg capacity was built and tested. Originally designed to provide buoyancy to mock-ups submerged in NASA's weightlessness simulators, the device may have application to water-landed spacecraft which must deploy flotation upon impact, and where launch weight and volume penalties are significant. The device may also be useful for the automated recovery of ocean floor probes or in marine salvage applications.
NASA Technical Reports Server (NTRS)
2004-01-01
The grant closure report is organized in the following four chapters: Chapter describes the two research areas Design optimization and Solid mechanics. Ten journal publications are listed in the second chapter. Five highlights is the subject matter of chapter three. CHAPTER 1. The Design Optimization Test Bed CometBoards. CHAPTER 2. Solid Mechanics: Integrated Force Method of Analysis. CHAPTER 3. Five Highlights: Neural Network and Regression Methods Demonstrated in the Design Optimization of a Subsonic Aircraft. Neural Network and Regression Soft Model Extended for PX-300 Aircraft Engine. Engine with Regression and Neural Network Approximators Designed. Cascade Optimization Strategy with Neural network and Regression Approximations Demonstrated on a Preliminary Aircraft Engine Design. Neural Network and Regression Approximations Used in Aircraft Design.
NASA Technical Reports Server (NTRS)
Raiszadeh, Behzad; Queen, Eric M.; Hotchko, Nathaniel J.
2009-01-01
A capability to simulate trajectories of multiple interacting rigid bodies has been developed, tested and validated. This capability uses the Program to Optimize Simulated Trajectories II (POST 2). The standard version of POST 2 allows trajectory simulation of multiple bodies without force interaction. In the current implementation, the force interaction between the parachute and the suspended bodies has been modeled using flexible lines, allowing accurate trajectory simulation of the individual bodies in flight. The POST 2 multibody capability is intended to be general purpose and applicable to any parachute entry trajectory simulation. This research paper explains the motivation for multibody parachute simulation, discusses implementation methods, and presents validation of this capability.
Performance Optimization of Force Feedback Control System in Virtual Vascular Intervention Surgery
Cai, Ping; Qin, Peng; Xie, Le
2014-01-01
In virtual surgery of minimally invasive vascular intervention, the force feedback is transmitted through the flexible guide wire. The disturbance caused by the flexible deformation would affect the fidelity of the VR (virtual reality) training. SMC (sliding mode control) strategy with delayed-output observer is adopted to suppress the effect of flexible deformation. In this study, the control performance of the strategy is assessed when the length of guide wire between actuator and the operating point changes. The performance assessment results demonstrate the effectiveness of the proposed method and find the optimal length of guide wire for the force feedback control. PMID:25254063
The optimization of force inputs for active structural acoustic control using a neural network
NASA Technical Reports Server (NTRS)
Cabell, R. H.; Lester, H. C.; Silcox, R. J.
1992-01-01
This paper investigates the use of a neural network to determine which force actuators, of a multi-actuator array, are best activated in order to achieve structural-acoustic control. The concept is demonstrated using a cylinder/cavity model on which the control forces, produced by piezoelectric actuators, are applied with the objective of reducing the interior noise. A two-layer neural network is employed and the back propagation solution is compared with the results calculated by a conventional, least-squares optimization analysis. The ability of the neural network to accurately and efficiently control actuator activation for interior noise reduction is demonstrated.
Bats dynamically change wingspan to enhance lift and efficiency
NASA Astrophysics Data System (ADS)
Wang, Shizhao; Zhang, Xing; He, Guowei; Liu, Tianshu; Turbulence Team
2016-11-01
Bats can dynamically change the wingspan by controlling the joints on the wings. This work focuses on the effect of dynamically changing wingspan on the lift and efficiency in slow-flying bats. The geometry and kinematics of the bat model is constructed based on the experimental measurements of Wolf et al.. The Navier-Stokes equations for incompressible flows are solved numerically to investigate the 3D unsteady flows around the bat model. It is found that the dynamically changing wingspan can significantly enhance the lift and efficiency. The lift enhancement is contributed by both lifting surface area extended during the downstroke and the vortex force associated with the leading-edge vortices intensified by the dynamically changing wingspan. The nonlinear interaction between the dynamically changing wing and the vortex structures plays an important role in the lift enhancement of a slow-flying bat in addition to the geometrical effect of changing the lifting-surface area in a flapping cycle.
ERIC Educational Resources Information Center
Gamble, Reed
1989-01-01
Discusses pupil misconceptions concerning forces. Summarizes some of Assessment of Performance Unit's findings on meaning of (1) force, (2) force and motion in one dimension and two dimensions, and (3) Newton's second law. (YP)
Anisotropic force ellipsoid based multi-axis motion optimization of machine tools
NASA Astrophysics Data System (ADS)
Peng, Fangyu; Yan, Rong; Chen, Wei; Yang, Jianzhong; Li, Bin
2012-09-01
The existing research of the motion optimization of multi-axis machine tools is mainly based on geometric and kinematic constraints, which aim at obtaining minimum-time trajectories and finding obstacle-free paths. In motion optimization, the stiffness characteristics of the whole machining system, including machine tool and cutter, are not considered. The paper presents a new method to establish a general stiffness model of multi-axis machining system. An analytical stiffness model is established by Jacobi and point transformation matrix method. Based on the stiffness model, feed-direction stiffness index is calculated by the intersection of force ellipsoid and the cutting feed direction at the cutter tip. The stiffness index can help analyze the stiffness performance of the whole machining system in the available workspace. Based on the analysis of the stiffness performance, multi-axis motion optimization along tool paths is accomplished by mixed programming using Matlab and Visual C++. The effectiveness of the motion optimization method is verified by the experimental research about the machining performance of a 7-axis 5-linkage machine tool. The proposed research showed that machining stability and production efficiency can be improved by multi-axis motion optimization based on the anisotropic force ellipsoid of the whole machining system.
Yang, Jian; Cong, Weijian; Chen, Yang; Fan, Jingfan; Liu, Yue; Wang, Yongtian
2014-02-21
The clinical value of the 3D reconstruction of a coronary artery is important for the diagnosis and intervention of cardiovascular diseases. This work proposes a method based on a deformable model for reconstructing coronary arteries from two monoplane angiographic images acquired from different angles. First, an external force back-projective composition model is developed to determine the external force, for which the force distributions in different views are back-projected to the 3D space and composited in the same coordinate system based on the perspective projection principle of x-ray imaging. The elasticity and bending forces are composited as an internal force to maintain the smoothness of the deformable curve. Second, the deformable curve evolves rapidly toward the true vascular centerlines in 3D space and angiographic images under the combination of internal and external forces. Third, densely matched correspondence among vessel centerlines is constructed using a curve alignment method. The bundle adjustment method is then utilized for the global optimization of the projection parameters and the 3D structures. The proposed method is validated on phantom data and routine angiographic images with consideration for space and re-projection image errors. Experimental results demonstrate the effectiveness and robustness of the proposed method for the reconstruction of coronary arteries from two monoplane angiographic images. The proposed method can achieve a mean space error of 0.564 mm and a mean re-projection error of 0.349 mm.
Edwards, Devin T; Faulk, Jaevyn K; Sanders, Aric W; Bull, Matthew S; Walder, Robert; LeBlanc, Marc-Andre; Sousa, Marcelo C; Perkins, Thomas T
2015-10-14
Atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS) is widely used to mechanically measure the folding and unfolding of proteins. However, the temporal resolution of a standard commercial cantilever is 50-1000 μs, masking rapid transitions and short-lived intermediates. Recently, SMFS with 0.7-μs temporal resolution was achieved using an ultrashort (L = 9 μm) cantilever on a custom-built, high-speed AFM. By micromachining such cantilevers with a focused ion beam, we optimized them for SMFS rather than tapping-mode imaging. To enhance usability and throughput, we detected the modified cantilevers on a commercial AFM retrofitted with a detection laser system featuring a 3-μm circular spot size. Moreover, individual cantilevers were reused over multiple days. The improved capabilities of the modified cantilevers for SMFS were showcased by unfolding a polyprotein, a popular biophysical assay. Specifically, these cantilevers maintained a 1-μs response time while eliminating cantilever ringing (Q ≅ 0.5). We therefore expect such cantilevers, along with the instrumentational improvements to detect them on a commercial AFM, to accelerate high-precision AFM-based SMFS studies.
DETAIL VIEW OF BRIDGE CRANE USED TO LIFT DOMED LIDS ...
DETAIL VIEW OF BRIDGE CRANE USED TO LIFT DOMED LIDS OF THE ALTITUDE CHAMBERS, FACING SOUTHWEST - Cape Canaveral Air Force Station, Launch Complex 39, Altitude Chambers, First Street, between Avenue D and Avenue E, Cape Canaveral, Brevard County, FL
Optimal force distribution for payload positioning using a planar dual-arm robot
NASA Technical Reports Server (NTRS)
Carignan, C. R.; Akin, D. L.
1989-01-01
This paper presents a parameter optimization technique for deciding the force distribution on a payload being transported along a predetermined trajectory using two planar manipulator arms. The methodology begins by transforming the singular dynamics of two-arm transport to an ordinary set of differential equations and then proceeds to obtain a relation between the torques exerted by each arm. This relation is then used in a quadratic torque cost which is subsequently minimized to yield an optimal torque distribution. Significant savings in energy were found to occur when the arms were allowed to interact by transmission of forces through the payload. Even more significant are the savings found over one-arm transport of payloads where the arm torques are fixed by the prescribed trajectory.
NASA Technical Reports Server (NTRS)
Soloway, Donald I.; Alberts, Thomas E.
1989-01-01
It is often proposed that the redundancy in choosing a force distribution for multiple arms grasping a single object should be handled by minimizing a quadratic performance index. The performance index may be formulated in terms of joint torques or in terms of the Cartesian space force/torque applied to the body by the grippers. The former seeks to minimize power consumption while the latter minimizes body stresses. Because the cost functions are related to each other by a joint angle dependent transformation on the weight matrix, it might be argued that either method tends to reduce power consumption, but clearly the joint space minimization is optimal. A comparison of these two options is presented with consideration given to computational cost and power consumption. Simulation results using a two arm robot system are presented to show the savings realized by employing the joint space optimization. These savings are offset by additional complexity, computation time and in some cases processor power consumption.
Optimized Reduction of Unsteady Radial Forces in a Singlechannel Pump for Wastewater Treatment
NASA Astrophysics Data System (ADS)
Kim, Jin-Hyuk; Cho, Bo-Min; Choi, Young-Seok; Lee, Kyoung-Yong; Peck, Jong-Hyeon; Kim, Seon-Chang
2016-11-01
A single-channel pump for wastewater treatment was optimized to reduce unsteady radial force sources caused by impeller-volute interactions. The steady and unsteady Reynolds- averaged Navier-Stokes equations using the shear-stress transport turbulence model were discretized by finite volume approximations and solved on tetrahedral grids to analyze the flow in the single-channel pump. The sweep area of radial force during one revolution and the distance of the sweep-area center of mass from the origin were selected as the objective functions; the two design variables were related to the internal flow cross-sectional area of the volute. These objective functions were integrated into one objective function by applying the weighting factor for optimization. Latin hypercube sampling was employed to generate twelve design points within the design space. A response-surface approximation model was constructed as a surrogate model for the objectives, based on the objective function values at the generated design points. The optimized results showed considerable reduction in the unsteady radial force sources in the optimum design, relative to those of the reference design.
Gouveia, Ricardo M; González-Andrades, Elena; Cardona, Juan C; González-Gallardo, Carmen; Ionescu, Ana M; Garzon, Ingrid; Alaminos, Miguel; González-Andrades, Miguel; Connon, Che J
2017-03-01
Ideally, biomaterials designed to play specific physical and physiological roles in vivo should comprise components and microarchitectures analogous to those of the native tissues they intend to replace. For that, implantable biomaterials need to be carefully designed to have the correct structural and compositional properties, which consequently impart their bio-function. In this study, we showed that the control of such properties can be defined from the bottom-up, using smart surface templates to modulate the structure, composition, and bio-mechanics of human transplantable tissues. Using multi-functional peptide amphiphile-coated surfaces with different anisotropies, we were able to control the phenotype of corneal stromal cells and instruct them to fabricate self-lifting tissues that closely emulated the native stromal lamellae of the human cornea. The type and arrangement of the extracellular matrix comprising these corneal stromal Self-Lifting Analogous Tissue Equivalents (SLATEs) were then evaluated in detail, and was shown to correlate with tissue function. Specifically, SLATEs comprising aligned collagen fibrils were shown to be significantly thicker, denser, and more resistant to proteolytic degradation compared to SLATEs formed with randomly-oriented constituents. In addition, SLATEs were highly transparent while providing increased absorption to near-UV radiation. Importantly, corneal stromal SLATEs were capable of constituting tissues with a higher-order complexity, either by creating thicker tissues through stacking or by serving as substrate to support a fully-differentiated, stratified corneal epithelium. SLATEs were also deemed safe as implants in a rabbit corneal model, being capable of integrating with the surrounding host tissue without provoking inflammation, neo-vascularization, or any other signs of rejection after a 9-months follow-up. This work thus paves the way for the de novo bio-fabrication of easy-retrievable, scaffold-free human
Structural Optimization of a Force Balance Using a Computational Experiment Design
NASA Technical Reports Server (NTRS)
Parker, P. A.; DeLoach, R.
2002-01-01
This paper proposes a new approach to force balance structural optimization featuring a computational experiment design. Currently, this multi-dimensional design process requires the designer to perform a simplification by executing parameter studies on a small subset of design variables. This one-factor-at-a-time approach varies a single variable while holding all others at a constant level. Consequently, subtle interactions among the design variables, which can be exploited to achieve the design objectives, are undetected. The proposed method combines Modern Design of Experiments techniques to direct the exploration of the multi-dimensional design space, and a finite element analysis code to generate the experimental data. To efficiently search for an optimum combination of design variables and minimize the computational resources, a sequential design strategy was employed. Experimental results from the optimization of a non-traditional force balance measurement section are presented. An approach to overcome the unique problems associated with the simultaneous optimization of multiple response criteria is described. A quantitative single-point design procedure that reflects the designer's subjective impression of the relative importance of various design objectives, and a graphical multi-response optimization procedure that provides further insights into available tradeoffs among competing design objectives are illustrated. The proposed method enhances the intuition and experience of the designer by providing new perspectives on the relationships between the design variables and the competing design objectives providing a systematic foundation for advancements in structural design.
Paramfit: automated optimization of force field parameters for molecular dynamics simulations.
Betz, Robin M; Walker, Ross C
2015-01-15
The generation of bond, angle, and torsion parameters for classical molecular dynamics force fields typically requires fitting parameters such that classical properties such as energies and gradients match precalculated quantum data for structures that scan the value of interest. We present a program, Paramfit, distributed as part of the AmberTools software package that automates and extends this fitting process, allowing for simplified parameter generation for applications ranging from single molecules to entire force fields. Paramfit implements a novel combination of a genetic and simplex algorithm to find the optimal set of parameters that replicate either quantum energy or force data. The program allows for the derivation of multiple parameters simultaneously using significantly fewer quantum calculations than previous methods, and can also fit parameters across multiple molecules with applications to force field development. Paramfit has been applied successfully to systems with a sparse number of structures, and has already proven crucial in the development of the Assisted Model Building with Energy Refinement Lipid14 force field.
Genetic algorithm optimization of point charges in force field development: challenges and insights.
Ivanov, Maxim V; Talipov, Marat R; Timerghazin, Qadir K
2015-02-26
Evolutionary methods, such as genetic algorithms (GAs), provide powerful tools for optimization of the force field parameters, especially in the case of simultaneous fitting of the force field terms against extensive reference data. However, GA fitting of the nonbonded interaction parameters that includes point charges has not been explored in the literature, likely due to numerous difficulties with even a simpler problem of the least-squares fitting of the atomic point charges against a reference molecular electrostatic potential (MEP), which often demonstrates an unusually high variation of the fitted charges on buried atoms. Here, we examine the performance of the GA approach for the least-squares MEP point charge fitting, and show that the GA optimizations suffer from a magnified version of the classical buried atom effect, producing highly scattered yet correlated solutions. This effect can be understood in terms of the linearly independent, natural coordinates of the MEP fitting problem defined by the eigenvectors of the least-squares sum Hessian matrix, which are also equivalent to the eigenvectors of the covariance matrix evaluated for the scattered GA solutions. GAs quickly converge with respect to the high-curvature coordinates defined by the eigenvectors related to the leading terms of the multipole expansion, but have difficulty converging with respect to the low-curvature coordinates that mostly depend on the buried atom charges. The performance of the evolutionary techniques dramatically improves when the point charge optimization is performed using the Hessian or covariance matrix eigenvectors, an approach with a significant potential for the evolutionary optimization of the fixed-charge biomolecular force fields.
Cianchetti, Flor A.
2010-01-01
Moving our fingertips toward objects to produce well-directed forces immediately upon contact is fundamental to dexterous manipulation. This apparently simple motion-to-force transition in fact involves a time-critical, predictive switch in control strategy. Given that dexterous manipulation must accommodate multiple mechanical conditions, we investigated whether and how this transition adapts to task difficulty. Eight adults (19–39 yr) produced ramps of isometric vertical fingertip force against a rigid surface immediately following a tapping motion. By changing target surface friction and size, we defined an easier (sandpaper, 11 mm diam) versus a more difficult (polished steel, 5 mm diam) task. As in prior work, we assembled fine-wire electromyograms from all seven muscles of the index finger into a seven-dimensional vector defining the full muscle coordination pattern—and quantified its temporal evolution as its alignment with a reference coordination pattern vector for steady-state force production. As predicted by numerical optimizations to neuromuscular delays, our empirical and sigmoidal nonlinear regression analyses show that the coordination pattern transitions begin sooner for the more difficult tasks than for the easier tasks (∼120 ms, P < 0.02, and ∼115 ms, P < 0.015, respectively) and that the coordination pattern transition in alignment is well represented by a sigmoidal trend (R^2 > 0.7 in most cases). Importantly, the force vector following contact had smaller directional error (P < 0.02) for the more difficult task even though the transition in coordination pattern was less stereotypical and uniform than for the easier task. These adaptations of transition strategy to task difficulty are compatible with an optimization to counteract neuromuscular delays and noise to enable this fundamental element of dexterous manipulation. PMID:19889857
Cianchetti, Flor A; Valero-Cuevas, Francisco J
2010-01-01
Moving our fingertips toward objects to produce well-directed forces immediately upon contact is fundamental to dexterous manipulation. This apparently simple motion-to-force transition in fact involves a time-critical, predictive switch in control strategy. Given that dexterous manipulation must accommodate multiple mechanical conditions, we investigated whether and how this transition adapts to task difficulty. Eight adults (19-39 yr) produced ramps of isometric vertical fingertip force against a rigid surface immediately following a tapping motion. By changing target surface friction and size, we defined an easier (sandpaper, 11 mm diam) versus a more difficult (polished steel, 5 mm diam) task. As in prior work, we assembled fine-wire electromyograms from all seven muscles of the index finger into a seven-dimensional vector defining the full muscle coordination pattern-and quantified its temporal evolution as its alignment with a reference coordination pattern vector for steady-state force production. As predicted by numerical optimizations to neuromuscular delays, our empirical and sigmoidal nonlinear regression analyses show that the coordination pattern transitions begin sooner for the more difficult tasks than for the easier tasks ( approximately 120 ms, P < 0.02, and approximately 115 ms, P < 0.015, respectively) and that the coordination pattern transition in alignment is well represented by a sigmoidal trend (R;2 > 0.7 in most cases). Importantly, the force vector following contact had smaller directional error (P < 0.02) for the more difficult task even though the transition in coordination pattern was less stereotypical and uniform than for the easier task. These adaptations of transition strategy to task difficulty are compatible with an optimization to counteract neuromuscular delays and noise to enable this fundamental element of dexterous manipulation.
Optimized Feedback Control of Vortex Shedding on an Inclined Flat Plate
NASA Astrophysics Data System (ADS)
Joe, Won Tae
This thesis examines flow control and the potentially favorable effects of feedback, associated with unsteady actuation in separated flows over airfoils. The objective of the flow control is to enhance lift at post-stall angles of attack by changing the dynamics of the wake vortices. We present results from a numerical study of unsteady actuation on a two-dimensional flat plate at post-stall angles of attack at Reynolds number (Re) of 300 and 3000. At Re=300, the control waveform is optimized and a feedback strategy is developed to optimize the phase of the control relative to the lift with either a sinusoidal or the optimized waveform, resulting in a high-lift limit cycle of vortex shedding. Also at Re=3000, we show that certain frequencies and actuator waveforms lead to stable (high-lift) limit cycles, in which the flow is phase locked to the actuation. First, a two-dimensional flat plate model at a high angle of attack at a Re of 300 is considered. We design the feedback to slightly adjust the frequency and/or phase of actuation to lock it to a particular phase of the lift, thus achieving a phase-locked flow with the maximal period-averaged lift over every cycle of acutation. With the sinusoidal forcing and feedback, we show that it is possible to optimize the phase of the control relative to the lift in order to achieve the highest possible period-averaged lift in a consistent fashion. However, continuous sinusoidal forcing could be adding circulation when it is unnecessary, or undesirable. Thus we employ an adjoint-based optimization in order to find the waveform (time history of the jet velocty) that maximizes the lift for a given actuation amplitude. The adjoint of the linearized perturbed equations is solved backwards in time to obtain the gradient of the lift to changes in actuation (the jet velocity), and this information is used to iteratively improve the controls. Optimal control provides a periodic control waveform, resulting in high lift shedding
Liu Yu; Guo Qiuquan; Nie Hengyong; Lau, W. M.; Yang Jun
2009-12-15
The mechanism of dynamic force modes has been successfully applied to many atomic force microscopy (AFM) applications, such as tapping mode and phase imaging. The high-order flexural vibration modes are recent advancement of AFM dynamic force modes. AFM optical lever detection sensitivity plays a major role in dynamic force modes because it determines the accuracy in mapping surface morphology, distinguishing various tip-surface interactions, and measuring the strength of the tip-surface interactions. In this work, we have analyzed optimization and calibration of the optical lever detection sensitivity for an AFM cantilever-tip ensemble vibrating in high-order flexural modes and simultaneously experiencing a wide range and variety of tip-sample interactions. It is found that the optimal detection sensitivity depends on the vibration mode, the ratio of the force constant of tip-sample interactions to the cantilever stiffness, as well as the incident laser spot size and its location on the cantilever. It is also found that the optimal detection sensitivity is less dependent on the strength of tip-sample interactions for high-order flexural modes relative to the fundamental mode, i.e., tapping mode. When the force constant of tip-sample interactions significantly exceeds the cantilever stiffness, the optimal detection sensitivity occurs only when the laser spot locates at a certain distance from the cantilever-tip end. Thus, in addition to the 'globally optimized detection sensitivity', the 'tip optimized detection sensitivity' is also determined. Finally, we have proposed a calibration method to determine the actual AFM detection sensitivity in high-order flexural vibration modes against the static end-load sensitivity that is obtained traditionally by measuring a force-distance curve on a hard substrate in the contact mode.
Muscle force regulates bone shaping for optimal load-bearing capacity during embryogenesis.
Sharir, Amnon; Stern, Tomer; Rot, Chagai; Shahar, Ron; Zelzer, Elazar
2011-08-01
The vertebrate skeleton consists of over 200 individual bones, each with its own unique shape, size and function. We study the role of intrauterine muscle-induced mechanical loads in determining the three-dimensional morphology of developing bones. Analysis of the force-generating capacity of intrauterine muscles in mice revealed that developing bones are subjected to significant and progressively increasing mechanical challenges. To evaluate the effect of intrauterine loads on bone morphogenesis and the contribution of the emerging shape to the ability of bones to withstand these loads, we monitored structural and mineral changes during development. Using daily micro-CT scans of appendicular long bones we identify a developmental program, which we term preferential bone growth, that determines the specific circumferential shape of each bone by employing asymmetric mineral deposition and transient cortical thickening. Finite element analysis demonstrates that the resulting bone structure has optimal load-bearing capacity. To test the hypothesis that muscle forces regulate preferential bone growth in utero, we examine this process in a mouse strain (mdg) that lacks muscle contractions. In the absence of mechanical loads, the stereotypical circumferential outline of each bone is lost, leading to the development of mechanically inferior bones. This study identifies muscle force regulation of preferential bone growth as the module that shapes the circumferential outline of bones and, consequently, optimizes their load-bearing capacity during development. Our findings invoke a common mechanism that permits the formation of different circumferential outlines in different bones.
NASA Astrophysics Data System (ADS)
Elfgen, Roman; Hülsmann, Marco; Krämer, Andreas; Köddermann, Thorsten; Kirschner, Karl N.; Reith, Dirk
2016-10-01
Molecular simulations are an important tool in the study of aqueous salt solutions. To predict the physical properties accurately and reliably, the molecular models must be tailored to reproduce experimental data. In this work, a combination of recent global and local optimization tools is used to derive force fields for MgCl2 (aq) and CaCl2 (aq). The molecular models for the ions are based on a Lennard-Jones (LJ) potential with a superimposed point charge. The LJ parameters are adjusted to reproduce the bulk density and shear viscosity of the different solutions at 1 bar and temperatures of 293.15, 303.15, and 318.15 K. It is shown that the σ-value of chloride consistently has the strongest influence on the system properties. The optimized force field for MgCl2 (aq) provides both properties in good agreement with the experimental data over a wide range of salt concentrations. For CaCl2 (aq), a compromise was made between the bulk density and shear viscosity, since reproducing the two properties requires two different choices of the LJ parameters. This is demonstrated by studying metamodels of the simulated data, which are generated to visualize the correlation between the parameters and observables by using projection plots. Consequently, in order to derive a transferable force field, an error of ˜3% on the bulk density has to be tolerated to yield the shear viscosity in satisfactory agreement with experimental data.
NASA Astrophysics Data System (ADS)
Cheung, Y. L.; Wong, W. O.; Cheng, L.
2013-02-01
A recently reported design of a hybrid vibration absorber (HVA) which is optimized to suppress resonant vibration of a single degree-of-freedom (SDOF) system is re-optimized for suppressing wide frequency band vibration of the SDOF system under stationary random force excitation. The proposed HVA makes use of the feedback signals from the displacement and velocity of the absorber mass for minimizing the vibration response of the dynamic structure based on the H2 optimization criterion. The objective of the optimal design is to minimize the mean square vibration amplitude of a dynamic structure under a wideband excitation, i.e., the total area under the vibration response spectrum is minimized in this criterion. One of the inherent limitations of the traditional passive vibration absorber is that its vibration suppression is low if the mass ratio between the absorber mass and the mass of the primary structure is low. The active element of the proposed HVA helps further reduce the vibration of the controlled structure and it can provide significant vibration absorption performance even at a low mass ratio. Both the passive and active elements are optimized together for the minimization of the mean square vibration amplitude of the primary system. The proposed HVA are tested on a SDOF system and continuous vibrating structures with comparisons to the traditional passive vibration absorber.
Palstra, Arjan P.; Mes, Daan; Kusters, Kasper; Roques, Jonathan A. C.; Flik, Gert; Kloet, Kees; Blonk, Robbert J. W.
2015-01-01
Swimming exercise at optimal speed may optimize growth performance of yellowtail kingfish in a recirculating aquaculture system. Therefore, optimal swimming speeds (Uopt in m s−1 or body lengths s−1, BL s−1) were assessed and then applied to determine the effects of long-term forced and sustained swimming at Uopt on growth performance of juvenile yellowtail kingfish. Uopt was quantified in Blazka-type swim-tunnels for 145, 206, and 311 mm juveniles resulting in values of: (1) 0.70 m s−1 or 4.83 BL s−1, (2) 0.82 m s−1 or 3.25 BL s−1, and (3) 0.85 m s−1 or 2.73 BL s−1. Combined with literature data from larger fish, a relation of Uopt (BL s−1) = 234.07(BL)−0.779 (R2 = 0.9909) was established for this species. Yellowtail kingfish, either forced to perform sustained swimming exercise at an optimal speed of 2.46 BL s−1 (“swimmers”) or allowed to perform spontaneous activity at low water flow (“resters”) in a newly designed 3600 L oval flume (with flow created by an impeller driven by an electric motor), were then compared. At the start of the experiment, ten fish were sampled representing the initial condition. After 18 days, swimmers (n = 23) showed a 92% greater increase in BL and 46% greater increase in BW as compared to resters (n = 23). As both groups were fed equal rations, feed conversion ratio (FCR) for swimmers was 1.21 vs. 1.74 for resters. Doppler ultrasound imaging showed a statistically significant higher blood flow (31%) in the ventral aorta of swimmers vs. resters (44 ± 3 vs. 34 ± 3 mL min−1, respectively, under anesthesia). Thus, growth performance can be rapidly improved by optimal swimming, without larger feed investments. PMID:25620933
Ergonomic Assessment of Floor-based and Overhead Lifts
Waters, Thomas R.; Dick, Robert; Lowe, Brian; Werren, Dwight; Parsons, Kelley
2015-01-01
Manual full-body vertical lifts of patients have high risk for developing musculoskeletal disorders. Two primary types of battery-powered lift assist devices are available for these tasks: floor-based and overhead-mounted devices. Studies suggest that the operation of floor-based devices may require excessive pushing and pulling forces and that overhead-mounted devices are safer and require lower operating forces. This study evaluated required operating hand forces and resulting biomechanical spinal loading for overhead-mounted lifts versus floor-based lifts across various floor surfaces and patient weight conditions. We did not examine differences in how operators performed the tasks, but rather focused on differences in required operating forces and estimated biomechanical loads across various exposure conditions for a typical operator. Findings show that the floor-based lifts exceeded recommended exposure limits for pushing and pulling for many of the floor/weight conditions and that the overhead-mounted lifts did not. As expected, forces and spinal loads were greater for nonlinoleum floor surfaces compared with linoleum floors. Based on these findings, it is suggested that overhead-mounted devices be used whenever possible, particularly in instances where carpeted floors would be encountered. PMID:26550545
Ravera, Emiliano Pablo; Crespo, Marcos José; Braidot, Ariel Andrés Antonio
2016-01-01
Clinical gait analysis provides great contributions to the understanding of gait patterns. However, a complete distribution of muscle forces throughout the gait cycle is a current challenge for many researchers. Two techniques are often used to estimate muscle forces: inverse dynamics with static optimization and computer muscle control that uses forward dynamics to minimize tracking. The first method often involves limitations due to changing muscle dynamics and possible signal artefacts that depend on day-to-day variation in the position of electromyographic (EMG) electrodes. Nevertheless, in clinical gait analysis, the method of inverse dynamics is a fundamental and commonly used computational procedure to calculate the force and torque reactions at various body joints. Our aim was to develop a generic musculoskeletal model that could be able to be applied in the clinical setting. The musculoskeletal model of the lower limb presents a simulation for the EMG data to address the common limitations of these techniques. This model presents a new point of view from the inverse dynamics used on clinical gait analysis, including the EMG information, and shows a similar performance to another model available in the OpenSim software. The main problem of these methods to achieve a correct muscle coordination is the lack of complete EMG data for all muscles modelled. We present a technique that simulates the EMG activity and presents a good correlation with the muscle forces throughout the gait cycle. Also, this method showed great similarities whit the real EMG data recorded from the subjects doing the same movement.
NASA Astrophysics Data System (ADS)
Müller, Mathias S.; Hoffmann, Lars; Buck, Thorbjörn C.; Wojtech, Rolf; Koch, Alexander W.
2011-05-01
Force-torque sensors are key elements in modern force feedback and robotic control applications. For special applications resistance against electromagnetic interference, high amount of load cycles or chemical resistance are important. For these applications, fiber-Bragg-grating based force torque sensors have been seen as possible solutions. Yet the implementation of a force-torque-sensor with six degrees of freedom and well conditioned sensitivities is still lacking demonstration. In this work, we demonstrate the design of a miniaturized fiber-Bragg-grating based force-torque sensor with six degrees of freedom using a numerical nonlinear programming technique. We implement the optimized structure and show its feasibility and sensitivity.
NASA Technical Reports Server (NTRS)
Tolleson, William
2012-01-01
A document describes designing, building, testing, and certifying a customized crane (Lifting Device LD) with a strong back (cradle) to facilitate the installation of long wall panels and short door panels for the GHe phase of the James Webb Space Telescope (JWST). The LD controls are variable-frequency drive controls designed to be adjustable for very slow and very-short-distance movements throughout the installation. The LD has a lift beam with an electric actuator attached at the end. The actuator attaches to a rectangular strong back (cradle) for lifting the long wall panels and short door panels from a lower angle into the vertical position inside the chamber, and then rotating around the chamber for installation onto the existing ceiling and floor. The LD rotates 360 (in very small increments) in both clockwise and counterclockwise directions. Eight lifting pads are on the top ring with 2-in. (.5-cm) eye holes spaced evenly around the ring to allow for the device to be suspended by three crane hoists from the top of the chamber. The LD is operated by remote controls that allow for a single, slow mode for booming the load in and out, with slow and very slow modes for rotating the load.
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Breast lift (mastopexy) - slideshow
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NASA Technical Reports Server (NTRS)
Terrell, Kyle (Inventor)
1990-01-01
A piston and cylinder assembly is disclosed which is constructed of polyvinyl chloride that uses local water pressure to perform small lifting tasks. The chamber is either pressurized to extend the piston or depressurized to retract the piston. The present invention is best utilized for raising and lowering toilet seats.
ERIC Educational Resources Information Center
Sullivan, Debra R.
2009-01-01
This article addresses leadership themes and answers leadership questions presented to "Exchange" by the Panel members who attended the "Exchange" Panel of 300 Reception in Dallas, Texas, last November. There is an old proverb that encourages people to lift as they climb: "While you climb a mountain, you must not forget others along the way." With…
Cai, Jiandong; Wang, Michael Yu; Zhang, Li
2015-12-01
In multifrequency atomic force microscopy (AFM), probe's characteristic of assigning resonance frequencies to integer harmonics results in a remarkable improvement of detection sensitivity at specific harmonic components. The selection criterion of harmonic order is based on its amplitude's sensitivity on material properties, e.g., elasticity. Previous studies on designing harmonic probe are unable to provide a large design capability along with maintaining the structural integrity. Herein, we propose a harmonic probe with step cross section, in which it has variable width in top and bottom steps, while the middle step in cross section is kept constant. Higher order resonance frequencies are tailored to be integer times of fundamental resonance frequency. The probe design is implemented within a structural optimization framework. The optimally designed probe is micromachined using focused ion beam milling technique, and then measured with an AFM. The measurement results agree well with our resonance frequency assignment requirement.
Specialty Task Force: A Strategic Component to Electronic Health Record (EHR) Optimization.
Romero, Mary Rachel; Staub, Allison
2016-01-01
Post-implementation stage comes after an electronic health record (EHR) deployment. Analyst and end users deal with the reality that some of the concepts and designs initially planned and created may not be complementary to the workflow; creating anxiety, dissatisfaction, and failure with early adoption of system. Problems encountered during deployment are numerous and can vary from simple to complex. Redundant ticket submission creates backlog for Information Technology personnel resulting in delays in resolving concerns with EHR system. The process of optimization allows for evaluation of system and reassessment of users' needs. A solid and well executed optimization infrastructure can help minimize unexpected end-user disruptions and help tailor the system to meet regulatory agency goals and practice standards. A well device plan to resolve problems during post implementation is necessary for cost containment and to streamline communication efforts. Creating a specialty specific collaborative task force is efficacious and expedites resolution of users' concerns through a more structured process.
Lisunova, Y; Heidler, J; Levkivskyi, I; Gaponenko, I; Weber, A; Caillier, Ch; Heyderman, L J; Kläui, M; Paruch, P
2013-03-15
Using single-walled carbon nanotubes homogeneously coated with ferromagnetic metal as ultra-high resolution magnetic force microscopy probes, we investigate the key image formation parameters and their dependence on coating thickness. The crucial step of introducing molecular beam epitaxy for deposition of the magnetic coating allows highly controlled fabrication of tips with small magnetic volume, while retaining high magnetic anisotropy and prolonged lifetime characteristics. Calculating the interaction between the tips and a magnetic sample, including hitherto neglected thermal noise effects, we show that optimal imaging is achieved for a finite, intermediate-thickness magnetic coating, in excellent agreement with experimental observations. With such optimal tips, we demonstrate outstanding resolution, revealing sub-10 nm domains in hard magnetic samples, and non-perturbative imaging of nanoscale spin structures in soft magnetic materials, all at ambient conditions with no special vacuum, temperature or humidity controls.
Cai, Jiandong; Zhang, Li; Wang, Michael Yu
2015-12-15
In multifrequency atomic force microscopy (AFM), probe’s characteristic of assigning resonance frequencies to integer harmonics results in a remarkable improvement of detection sensitivity at specific harmonic components. The selection criterion of harmonic order is based on its amplitude’s sensitivity on material properties, e.g., elasticity. Previous studies on designing harmonic probe are unable to provide a large design capability along with maintaining the structural integrity. Herein, we propose a harmonic probe with step cross section, in which it has variable width in top and bottom steps, while the middle step in cross section is kept constant. Higher order resonance frequencies are tailored to be integer times of fundamental resonance frequency. The probe design is implemented within a structural optimization framework. The optimally designed probe is micromachined using focused ion beam milling technique, and then measured with an AFM. The measurement results agree well with our resonance frequency assignment requirement.
Simultaneous optimization of force and placement of friction dampers under seismic loading
NASA Astrophysics Data System (ADS)
Fleck Fadel Miguel, Letícia; Fleck Fadel Miguel, Leandro; Holdorf Lopez, Rafael
2016-04-01
It is known that the use of passive energy-dissipation devices, such as friction dampers, reduces considerably the dynamic response of a structure subjected to earthquake ground motions. Nevertheless, the parameters of each damper and the best placement of these devices remain difficult to determine. Some articles on optimum design of tuned mass dampers and viscous dampers have been published; however, there is a lack of studies on optimization of friction dampers. The main contribution of this article is to propose a methodology to simultaneously optimize the location of friction dampers and their friction forces in structures subjected to seismic loading, to achieve a desired level of reduction in the response. For this purpose, the recently developed backtracking search optimization algorithm (BSA) is employed, which can deal with optimization problems involving mixed discrete and continuous variables. For illustration purposes, two different structures are presented. The first is a six-storey shear building and the second is a transmission line tower. In both cases, the forces and positions of friction dampers are the design variables, while the objective functions are to minimize the interstorey drift for the first case and to minimize the maximum displacement at the top of the tower for the second example. The results show that the proposed method was able to reduce the interstorey drift of the shear building by more than 65% and the maximum displacement at the top of the tower by approximately 55%, with only three friction dampers. The proposed methodology is quite general and it could be recommended as an effective tool for optimum design of friction dampers for structural response control. Thus, this article shows that friction dampers can be designed in a safe and economic way.
NASA Astrophysics Data System (ADS)
Modgil, Girish A.
Gas turbine engines for aerospace applications have evolved dramatically over the last 50 years through the constant pursuit for better specific fuel consumption, higher thrust-to-weight ratio, lower noise and emissions all while maintaining reliability and affordability. An important step in enabling these improvements is a forced response aeromechanics analysis involving structural dynamics and aerodynamics of the turbine. It is well documented that forced response vibration is a very critical problem in aircraft engine design, causing High Cycle Fatigue (HCF). Pushing the envelope on engine design has led to increased forced response problems and subsequently an increased risk of HCF failure. Forced response analysis is used to assess design feasibility of turbine blades for HCF using a material limit boundary set by the Goodman Diagram envelope that combines the effects of steady and vibratory stresses. Forced response analysis is computationally expensive, time consuming and requires multi-domain experts to finalize a result. As a consequence, high-fidelity aeromechanics analysis is performed deterministically and is usually done at the end of the blade design process when it is very costly to make significant changes to geometry or aerodynamic design. To address uncertainties in the system (engine operating point, temperature distribution, mistuning, etc.) and variability in material properties, designers apply conservative safety factors in the traditional deterministic approach, which leads to bulky designs. Moreover, using a deterministic approach does not provide a calculated risk of HCF failure. This thesis describes a process that begins with the optimal aerodynamic design of a turbomachinery blade developed using surrogate models of high-fidelity analyses. The resulting optimal blade undergoes probabilistic evaluation to generate aeromechanics results that provide a calculated likelihood of failure from HCF. An existing Rolls-Royce High Work Single
Analysis and correlation with theory of rotor lift-limit test data
NASA Technical Reports Server (NTRS)
Sheffler, M.
1979-01-01
A wind tunnel test program to define the cruise performance and determine any limitations to lift and propulsive force of a conventional helicopter rotor is described. A 2.96 foot radius model rotor was used. The maximum lift and propulsive force obtainable from an articulated rotor for advance ratios of 0.4 to 0.67, and the blade load growth as the lift approaches the limit are determined. Cruise rotor performance for advance ratios of 0.4 to 0.67 and the sensitivity of the rotor forces and moments to rotor control inputs as the lift limit is approached are established.
Helicopter Toy and Lift Estimation
ERIC Educational Resources Information Center
Shakerin, Said
2013-01-01
A $1 plastic helicopter toy (called a Wacky Whirler) can be used to demonstrate lift. Students can make basic measurements of the toy, use reasonable assumptions and, with the lift formula, estimate the lift, and verify that it is sufficient to overcome the toy's weight. (Contains 1 figure.)
Quantifying feedforward control: a linear scaling model for fingertip forces and object weight
Lu, Ying; Bilaloglu, Seda; Aluru, Viswanath
2015-01-01
The ability to predict the optimal fingertip forces according to object properties before the object is lifted is known as feedforward control, and it is thought to occur due to the formation of internal representations of the object's properties. The control of fingertip forces to objects of different weights has been studied extensively by using a custom-made grip device instrumented with force sensors. Feedforward control is measured by the rate of change of the vertical (load) force before the object is lifted. However, the precise relationship between the rate of change of load force and object weight and how it varies across healthy individuals in a population is not clearly understood. Using sets of 10 different weights, we have shown that there is a log-linear relationship between the fingertip load force rates and weight among neurologically intact individuals. We found that after one practice lift, as the weight increased, the peak load force rate (PLFR) increased by a fixed percentage, and this proportionality was common among the healthy subjects. However, at any given weight, the level of PLFR varied across individuals and was related to the efficiency of the muscles involved in lifting the object, in this case the wrist and finger extensor muscles. These results quantify feedforward control during grasp and lift among healthy individuals and provide new benchmarks to interpret data from neurologically impaired populations as well as a means to assess the effect of interventions on restoration of feedforward control and its relationship to muscular control. PMID:25878151
Lip Lifting: Unveiling Dental Beauty.
Stanley, Kyle; Caligiuri, Matthew; Schlichting, Luís Henrique; Bazos, Panaghiotis K; Magne, Michel
2017-01-01
The focus for the achievement of complete success in the esthetic zone has traditionally been on addressing deficiencies of intraoral hard and soft tissue. Often, these deficiencies are accompanied by esthetic concerns regarding the lips that are routinely neglected by the dental team. A predictable plastic surgery technique - the lip lift - has been used for decades to enhance lip esthetics by shortening the senile upper lip to achieve a more youthful appearance. Over the years, this technique has been refined and used in many different ways, allowing its routine incorporation into full facial esthetic planning. Through restoration of the upper lip to its optimal position, the artistry of the dentist and dental technician can truly be appreciated in the rejuvenated smile. By the introduction of this minimally invasive surgical technique to the dental community, patients stand to benefit from a comprehensive orofacial approach to anterior dental esthetic planning.
NASA Astrophysics Data System (ADS)
Arabi, Alya A.
2016-11-01
Modelling dispersion interactions with traditional density functional theory (DFT) is a challenge that has been extensively addressed in the past decade. The exchange-dipole moment (XDM), among others, is a non-empirical add-on dispersion correction model in DFT. The functional PW86+PBE+XDM for exchange, correlation and dispersion, respectively, compromises an accurate functional for thermochemistry and for van der Waals (vdW) complexes at equilibrium and non-equilibrium geometries. To use this functional in optimizing vdW complexes, rather than computing single point energies, it is necessary to evaluate accurate forces. The purpose of this paper is to validate that, along the potential energy surface, the distance at which the energy is minimum is commensurate with the distance at which the forces vanish to zero. This test was validated for 10 rare gas diatomic molecules using various integration grids and different convergence criteria. It was found that the use of either convergence criterion, 10-6 or 10-8, in Gaussian09, does not affect the accuracy of computed optimal distances and binding energies. An ultra-fine grid needs to be used when computing accurate energies using generalized gradient approximation functionals. This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.
Arabi, Alya A
2016-11-13
Modelling dispersion interactions with traditional density functional theory (DFT) is a challenge that has been extensively addressed in the past decade. The exchange-dipole moment (XDM), among others, is a non-empirical add-on dispersion correction model in DFT. The functional PW86+PBE+XDM for exchange, correlation and dispersion, respectively, compromises an accurate functional for thermochemistry and for van der Waals (vdW) complexes at equilibrium and non-equilibrium geometries. To use this functional in optimizing vdW complexes, rather than computing single point energies, it is necessary to evaluate accurate forces. The purpose of this paper is to validate that, along the potential energy surface, the distance at which the energy is minimum is commensurate with the distance at which the forces vanish to zero. This test was validated for 10 rare gas diatomic molecules using various integration grids and different convergence criteria. It was found that the use of either convergence criterion, 10(-6) or 10(-8), in Gaussian09, does not affect the accuracy of computed optimal distances and binding energies. An ultra-fine grid needs to be used when computing accurate energies using generalized gradient approximation functionals.This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.
NASA Technical Reports Server (NTRS)
Garcia, F., Jr.
1974-01-01
A study of the solution problem of a complex entry optimization was studied. The problem was transformed into a two-point boundary value problem by using classical calculus of variation methods. Two perturbation methods were devised. These methods attempted to desensitize the contingency of the solution of this type of problem on the required initial co-state estimates. Also numerical results are presented for the optimal solution resulting from a number of different initial co-states estimates. The perturbation methods were compared. It is found that they are an improvement over existing methods.
NASA Technical Reports Server (NTRS)
Hahne, David E.; Glaab, Louis J.
1999-01-01
An investigation was performed to evaluate leading-and trailing-edge flap deflections for optimal aerodynamic performance of a High-Speed Civil Transport concept during takeoff and approach-to-landing conditions. The configuration used for this study was designed by the Douglas Aircraft Company during the 1970's. A 0.1-scale model of this configuration was tested in the Langley 30- by 60-Foot Tunnel with both the original leading-edge flap system and a new leading-edge flap system, which was designed with modem computational flow analysis and optimization tools. Leading-and trailing-edge flap deflections were generated for the original and modified leading-edge flap systems with the computational flow analysis and optimization tools. Although wind tunnel data indicated improvements in aerodynamic performance for the analytically derived flap deflections for both leading-edge flap systems, perturbations of the analytically derived leading-edge flap deflections yielded significant additional improvements in aerodynamic performance. In addition to the aerodynamic performance optimization testing, stability and control data were also obtained. An evaluation of the crosswind landing capability of the aircraft configuration revealed that insufficient lateral control existed as a result of high levels of lateral stability. Deflection of the leading-and trailing-edge flaps improved the crosswind landing capability of the vehicle considerably; however, additional improvements are required.
Optimal design of force magnification frame of a piezoelectric stack energy harvester
NASA Astrophysics Data System (ADS)
Chen, Shubin; Wang, Lirong; Zhou, Wanlu; Musgrave, Patrick; Xu, Tian-Bing; Zuo, Lei
2015-04-01
With the rapid development of portable electrical devices, the demand for batteries to power these portable devices increases dramatically. However, the development of the battery technology is slow in energy storage capability and cannot meet such requirements. This paper proposed an optimal frame design for a kind of portable piezoelectric stack energy harvesters, with large force magnification ratio and high energy transmission ratio. Two kinds of design approaches have been studied and explored, i.e., flexure compliant mechanism math based and finite element analysis (FEA) based. Prototypes are fabricated and assembled. Experiments with both static test and dynamic test have been conducted to approve the effectiveness of the proposed design. The measured force magnification ratio of 6.13 times and 21.8 times for the first-stage harvester and the dual-stage harvester are close to the design objective of 7.17 times and 24.4 times. The designed single stage harvester can generate 20.7mW/g2 at resonance frequency of 160Hz with optimal resistance of 393Ω under 0.8g base excitation with 100gram top mass, and the dual stage harvester has power generation of 487mW/g2 at resonance frequency of 38.9Hz with optimal resistance of 818Ω under 1.94g base excitation with 100gram top mass. The proposed two-stage PZT energy harvester can be used to develop portable power regenerator to compensate the urgent battery needs in remote area for both civic and military application.
Reese, T.E.
1983-05-17
A device for lifting liquid from boreholes comprises a pump which is located downhole in the region of a production formation and which consists of a fluid-actuated, double-action piston. The pump is connected by fluid pressure lines to a source of fluid pressure disposed above ground and a switching valve is connected to provide fluid pressure to alternate sides of the piston to effect reciprocation thereof.
Enhanced Rescue Lift Capability
NASA Technical Reports Server (NTRS)
Young, Larry A.
2007-01-01
The evolving and ever-increasing demands of emergency response and disaster relief support provided by rotorcraft dictate, among other things, the development of enhanced rescue lift capability for these platforms. This preliminary analysis is first-order in nature but provides considerable insight into some of the challenges inherent in trying to effect rescue using a unique form of robotic rescue device deployed and operated from rotary-wing aerial platforms.
A design and analysis approach for drag reduction on aircraft with adaptive lifting surfaces
NASA Astrophysics Data System (ADS)
Cusher, Aaron Anthony
distributions are produced which match the classical result for minimum induced drag. Application of the profile drag reduction schemes produce solutions which force the wing to operate in the low-drag-ranges of the natural-laminar-flow airfoil sections, thereby lowering profile drag. The total drag reduction schemes use a curve-fit routine that generates airfoil drag polars given flap angle and Reynolds number. The approximated drag polars allow the prediction of profile drag values to be combined with induced drag values to form a total drag function, which is utilized with a constrained nonlinear optimizer that determines best flap angles for total drag and trim. The different drag reduction schemes each produce independent flap-angle solutions and lift distributions for a given aircraft configuration and operating condition, and provide valuable insight for aerodynamic design and trade studies. The drag reduction approach is intended to be applicable to arbitrary aircraft configurations, and can be adapted to use surface incidence, twist, and flap angles as optimization variables, thereby creating a powerful and flexible aerodynamic design and analysis tool.
Lift, drag and flow-field measurements around a small ornithopter
Balakumar, B J; Chavez - Alarcon, Ramiro; Shu, Fangjun
2011-01-12
The aerodynamics of a flight-worthy, radio controlled ornithopter is investigated using a combination of Particle-Image Velocimetry (PIV), load cell measurements, and high-speed photography of smoke visualizations. The lift and thrust forces of the ornithopter are measured at various flow speeds, flapping frequencies and angles of attack to characterize the flight performance. These direct force measurements are then compared with forces estimated using control volume analysis on PIV data. High-speed photography of smoke streaks is used to visualize the evolution of leading edge vortices, and to qualitatively infer the effect of wing deformation on the net downwash. Vortical structures in the wake are compared to previous studies on root flapping, and direct measurements of flapping efficiency are used to argue that the current ornithopter operates sub-optimally in converting the input energy into propulsive work.
bOptimizing atomic force microscopy for characterization of diamond-protein interfaces
2011-01-01
Atomic force microscopy (AFM) in contact mode and tapping mode is employed for high resolution studies of soft organic molecules (fetal bovine serum proteins) on hard inorganic diamond substrates in solution and air. Various effects in morphology and phase measurements related to the cantilever spring constant, amplitude of tip oscillations, surface approach, tip shape and condition are demonstrated and discussed based on the proposed schematic models. We show that both diamond and proteins can be mechanically modified by Si AFM cantilever. We propose how to choose suitable cantilever type, optimize scanning parameters, recognize and minimize various artifacts, and obtain reliable AFM data both in solution and in air to reveal microscopic characteristics of protein-diamond interfaces. We also suggest that monocrystalline diamond is well defined substrate that can be applicable for fundamental studies of molecules on surfaces in general. PMID:21711846
Detail of lift wire rope attachment to lift span at ...
Detail of lift wire rope attachment to lift span at southeast corner. Note rope-adjustment turnbuckle with strap keepers to prevent its rotation, which could pull the bridge out of alignment. A single rope and light-gauge attachment at each corner were adequate for lifting the span because most of its weight was balanced by the two counterweights. - Potomac Edison Company, Chesapeake & Ohio Canal Bridge, Spanning C & O Canal South of U.S. 11, Williamsport, Washington County, MD
NASA Astrophysics Data System (ADS)
Finley, James P.; Chaudhuri, Rajat K.; Freed, Karl F.
1996-07-01
High-order multireference perturbation theory is applied to the 1S states of the beryllium atom using a reference (model) space composed of the \\|1s22s2> and the \\|1s22p2> configuration-state functions (CSF's), a system that is known to yield divergent expansions using Mo/ller-Plesset and Epstein-Nesbet partitioning methods. Computations of the eigenvalues are made through 40th order using forced degeneracy (FD) partitioning and the recently introduced optimization (OPT) partitioning. The former forces the 2s and 2p orbitals to be degenerate in zeroth order, while the latter chooses optimal zeroth-order energies of the (few) most important states. Our methodology employs simple models for understanding and suggesting remedies for unsuitable choices of reference spaces and partitioning methods. By examining a two-state model composed of only the \\|1s22p2> and \\|1s22s3s> states of the beryllium atom, it is demonstrated that the full computation with 1323 CSF's can converge only if the zeroth-order energy of the \\|1s22s3s> Rydberg state from the orthogonal space lies below the zeroth-order energy of the \\|1s22p2> CSF from the reference space. Thus convergence in this case requires a zeroth-order spectral overlap between the orthogonal and reference spaces. The FD partitioning is not capable of generating this type of spectral overlap and thus yields a divergent expansion. However, the expansion is actually asymptotically convergent, with divergent behavior not displayed until the 11th order because the \\|1s22s3s> Rydberg state is only weakly coupled with the \\|1s22p2> CSF and because these states are energetically well separated in zeroth order. The OPT partitioning chooses the correct zeroth-order energy ordering and thus yields a convergent expansion that is also very accurate in low orders compared to the exact solution within the basis.
Florio, C S
2015-04-01
Improved methods to analyze and compare the muscle-based influences that drive bone strength adaptation can aid in the understanding of the wide array of experimental observations about the effectiveness of various mechanical countermeasures to losses in bone strength that result from age, disuse, and reduced gravity environments. The coupling of gradient-based and gradientless numerical optimization routines with finite element methods in this work results in a modeling technique that determines the individual magnitudes of the muscle forces acting in a multisegment musculoskeletal system and predicts the improvement in the stress state uniformity and, therefore, strength, of a targeted bone through simulated local cortical material accretion and resorption. With a performance-based stopping criteria, no experimentally based or system-based parameters, and designed to include the direct and indirect effects of muscles attached to the targeted bone as well as to its neighbors, shape and strength alterations resulting from a wide range of boundary conditions can be consistently quantified. As demonstrated in a representative parametric study, the developed technique effectively provides a clearer foundation for the study of the relationships between muscle forces and the induced changes in bone strength. Its use can lead to the better control of such adaptive phenomena.
NASA Astrophysics Data System (ADS)
Eslami, Babak
The overall goals of this project are (i) to improve the current dynamic modes of atomic force microscopy (AFM) with the focus of multifrequency AFM measurements on soft matters in ambient air and liquid environments and (ii) to develop a new methodology for mechanically characterizing the subsurface of soft samples, allowing users to gradually, controllably and reversibly reveal features that are buried under the surface. This dissertation includes a wide range of studies on multifrequency atomic force microscopy. Firstly, the imaging parameters (drive amplitude and frequency) of each eigenmode is studied, optimized based on the observables. Secondly, a new mutltifrequency AFM technique with capability of imaging subsurface features has been developed and verified through experiments. Based on the first goal of the project, an experimental protocol to select excitation frequency in air for single tapping mode and bimodal AFM are provided. Additionally, a rigorous guideline for the selection of drive frequency in ambient air, liquid environment based on the energy quantities and slope of the cantilever's phase response is established. Finally, an advantage of using higher and stiffer eigenmodes for imaging soft matters has been proposed and verified experimentally. By this technique, subsurface imaging capabilities of AFM are expanded.
Development of devices for self-injection: using tribological analysis to optimize injection force
Lange, Jakob; Urbanek, Leos; Burren, Stefan
2016-01-01
This article describes the use of analytical models and physical measurements to characterize and optimize the tribological behavior of pen injectors for self-administration of biopharmaceuticals. One of the main performance attributes of this kind of device is its efficiency in transmitting the external force applied by the user on to the cartridge inside the pen in order to effectuate an injection. This injection force characteristic is heavily influenced by the frictional properties of the polymeric materials employed in the mechanism. Standard friction tests are available for characterizing candidate materials, but they use geometries and conditions far removed from the actual situation inside a pen injector and thus do not always generate relevant data. A new test procedure, allowing the direct measurement of the coefficient of friction between two key parts of a pen injector mechanism using real parts under simulated use conditions, is presented. In addition to the absolute level of friction, the test method provides information on expected evolution of friction over lifetime as well as on expected consistency between individual devices. Paired with an analytical model of the pen mechanism, the frictional data allow the expected overall injection system force efficiency to be estimated. The test method and analytical model are applied to a range of polymer combinations with different kinds of lubrication. It is found that material combinations used without lubrication generally have unsatisfactory performance, that the use of silicone-based internal lubricating additives improves performance, and that the best results can be achieved with external silicone-based lubricants. Polytetrafluoroethylene-based internal lubrication and external lubrication are also evaluated but found to provide only limited benefits unless used in combination with silicone. PMID:27274319
The effects of obesity on lifting performance.
Xu, Xu; Mirka, Gary A; Hsiang, Simon M
2008-01-01
Obesity in the workforce is a growing problem worldwide. While the implications of this trend for biomechanical loading of the musculoskeletal system seem fairly straightforward, the evidence of a clear link between low back pain (LBP) and body mass index (BMI) (calculated as whole body mass in kilograms divided by the square of stature in meters) has not been shown in the epidemiology literature addressing this topic. The approach pursued in the current study was to evaluate the lifting kinematics and ground reaction forces of a group of 12 subjects -- six with a BMI of less than 25 kg/m(2) (normal weight) and six with a BMI of greater than 30 kg/m(2) (obese). These subjects performed a series of free dynamic lifting tasks with varied levels of load (10% and 25% of capacity) and symmetry (sagittally symmetric and 45 degrees asymmetric). The results showed that BMI had a significant effect (p<0.05) on trunk kinematics with the high BMI group exhibiting higher peak transverse plane (twisting) velocity (59% higher) and acceleration (57% higher), and exhibiting higher peak sagittal plane velocity (30% higher) and acceleration (51% higher). When normalized to body weight, there were no significant differences in the ground reaction forces between the two groups. This study provides quantitative data describing lifting task performance differences between people of differing BMI levels and may help to explain why there is no conclusive epidemiological evidence of a relationship between BMI and LBP.
Using Maximal Isometric Force to Determine the Optimal Load for Measuring Dynamic Muscle Power
NASA Technical Reports Server (NTRS)
Spiering, Barry A.; Lee, Stuart M. C.; Mulavara, Ajitkumar P.; Bentley, Jason R.; Nash, Roxanne E.; Sinka, Joseph; Bloomberg, Jacob J.
2009-01-01
Maximal power output occurs when subjects perform ballistic exercises using loads of 30-50% of one-repetition maximum (1-RM). However, performing 1-RM testing prior to power measurement requires considerable time, especially when testing involves multiple exercises. Maximal isometric force (MIF), which requires substantially less time to measure than 1-RM, might be an acceptable alternative for determining the optimal load for power testing. PURPOSE: To determine the optimal load based on MIF for maximizing dynamic power output during leg press and bench press exercises. METHODS: Twenty healthy volunteers (12 men and 8 women; mean +/- SD age: 31+/-6 y; body mass: 72 +/- 15 kg) performed isometric leg press and bench press movements, during which MIF was measured using force plates. Subsequently, subjects performed ballistic leg press and bench press exercises using loads corresponding to 20%, 30%, 40%, 50%, and 60% of MIF presented in randomized order. Maximal instantaneous power was calculated during the ballistic exercise tests using force plates and position transducers. Repeated-measures ANOVA and Fisher LSD post hoc tests were used to determine the load(s) that elicited maximal power output. RESULTS: For the leg press power test, six subjects were unable to be tested at 20% and 30% MIF because these loads were less than the lightest possible load (i.e., the weight of the unloaded leg press sled assembly [31.4 kg]). For the bench press power test, five subjects were unable to be tested at 20% MIF because these loads were less than the weight of the unloaded aluminum bar (i.e., 11.4 kg). Therefore, these loads were excluded from analysis. A trend (p = 0.07) for a main effect of load existed for the leg press exercise, indicating that the 40% MIF load tended to elicit greater power output than the 60% MIF load (effect size = 0.38). A significant (p . 0.05) main effect of load existed for the bench press exercise; post hoc analysis indicated that the effect of
Lift generation by a two-dimensional symmetric flapping wing
NASA Astrophysics Data System (ADS)
Inamuro, Takaji; Ota, Keigo; Suzuki, Kosuke
2010-11-01
Two-dimensional symmetric flapping flight is investigated by an immersed boundary-lattice Boltzmann method. In the method we can treat the moving boundary problem efficiently on the Cartesian grid. First, we investigate the effect of the Reynolds number on flows around symmetric flapping wings under no-gravity field and find that at high Reynolds numbers asymmetric vortices are appeared and the time-averaged lift force is induced on the wings, while at low Reynolds numbers only symmetric vortices are appeared around the wings and no lift force is induced. Also, the effect of the initial position of the wings on the lift force is investigated. Secondly, we carry out free flight simulations under gravity field for various Reynolds and Froude numbers and find the region where upward flights are possible.
NASA Astrophysics Data System (ADS)
Nguyen, Q. H.; Choi, S. B.; Lee, Y. S.; Han, M. S.
2013-11-01
This paper focuses on the optimal design of a compact and high damping force engine mount featuring magnetorheological fluid (MRF). In the mount, a MR valve structure with both annular and radial flows is employed to generate a high damping force. First, the configuration and working principle of the proposed MR mount is introduced. The MRF flows in the mount are then analyzed and the governing equations of the MR mount are derived based on the Bingham plastic behavior of the MRF. An optimal design of the MR mount is then performed to find the optimal structure of the MR valve to generate a maximum damping force with certain design constraints. In addition, the gap size of MRF ducts is empirically chosen considering the ‘lockup’ problem of the mount at high frequency. Performance of the optimized MR mount is then evaluated based on finite element analysis and discussions on performance results of the optimized MR mount are given. The effectiveness of the proposed MR engine mount is demonstrated via computer simulation by presenting damping force and power consumption.
Effects of height and load weight on shoulder muscle work during overhead lifting task.
Blache, Y; Desmoulins, L; Allard, P; Plamondon, A; Begon, M
2015-01-01
Few musculoskeletal models are available to assess shoulder deeper muscle demand during overhead lifting tasks. Our objective was to implement a musculoskeletal model to assess the effect of lifting height and load on shoulder muscle work. A musculoskeletal model scaled from 15 male subjects was used to calculate shoulder muscle work during six lifting tasks. Boxes containing three different loads (6, 12 and 18 kg) were lifted by the subjects from the waist to shoulder or eye level. After optimisation of the maximal isometric force of the model's muscles, the bio-fidelity of the model was improved by 19%. The latter was able to reproduce the subjects' lifting movements. Mechanical work of the rotator cuff muscles, upper trapezius and anterior deltoid was increased with lifting load and height augmentation. In conclusion, the use of a musculoskeletal model validated by electromyography enabled to evaluate the muscle demand of deep muscles during lifting tasks.
Investigation of Maximum Blade Loading Capability of Lift-Offset Rotors
NASA Technical Reports Server (NTRS)
Yeo, Hyeonsoo; Johnson, Wayne
2013-01-01
Maximum blade loading capability of a coaxial, lift-offset rotor is investigated using a rotorcraft configuration designed in the context of short-haul, medium-size civil and military missions. The aircraft was sized for a 6600-lb payload and a range of 300 nm. The rotor planform and twist were optimized for hover and cruise performance. For the present rotor performance calculations, the collective pitch angle is progressively increased up to and through stall with the shaft angle set to zero. The effects of lift offset on rotor lift, power, controls, and blade airloads and structural loads are examined. The maximum lift capability of the coaxial rotor increases as lift offset increases and extends well beyond the McHugh lift boundary as the lift potential of the advancing blades are fully realized. A parametric study is conducted to examine the differences between the present coaxial rotor and the McHugh rotor in terms of maximum lift capabilities and to identify important design parameters that define the maximum lift capability of the rotor. The effects of lift offset on rotor blade airloads and structural loads are also investigated. Flap bending moment increases substantially as lift offset increases to carry the hub roll moment even at low collective values. The magnitude of flap bending moment is dictated by the lift-offset value (hub roll moment) but is less sensitive to collective and speed.
Transonic wind-tunnel tests of a lifting parachute model
NASA Technical Reports Server (NTRS)
Foughner, J. T., Jr.; Reed, J. F.; Wynne, E. C.
1976-01-01
Wind-tunnel tests have been made in the Langley transonic dynamics tunnel on a 0.25-scale model of Sandia Laboratories' 3.96-meter (13-foot), slanted ribbon design, lifting parachute. The lifting parachute is the first stage of a proposed two-stage payload delivery system. The lifting parachute model was attached to a forebody representing the payload. The forebody was designed and installed in the test section in a manner which allowed rotational freedom about the pitch and yaw axes. Values of parachute axial force coefficient, rolling moment coefficient, and payload trim angles in pitch and yaw are presented through the transonic speed range. Data are presented for the parachute in both the reefed and full open conditions. Time history records of lifting parachute deployment and disreefing tests are included.
A Near-Term, High-Confidence Heavy Lift Launch Vehicle
NASA Technical Reports Server (NTRS)
Rothschild, William J.; Talay, Theodore A.
2009-01-01
The use of well understood, legacy elements of the Space Shuttle system could yield a near-term, high-confidence Heavy Lift Launch Vehicle that offers significant performance, reliability, schedule, risk, cost, and work force transition benefits. A side-mount Shuttle-Derived Vehicle (SDV) concept has been defined that has major improvements over previous Shuttle-C concepts. This SDV is shown to carry crew plus large logistics payloads to the ISS, support an operationally efficient and cost effective program of lunar exploration, and offer the potential to support commercial launch operations. This paper provides the latest data and estimates on the configurations, performance, concept of operations, reliability and safety, development schedule, risks, costs, and work force transition opportunities for this optimized side-mount SDV concept. The results presented in this paper have been based on established models and fully validated analysis tools used by the Space Shuttle Program, and are consistent with similar analysis tools commonly used throughout the aerospace industry. While these results serve as a factual basis for comparisons with other launch system architectures, no such comparisons are presented in this paper. The authors welcome comparisons between this optimized SDV and other Heavy Lift Launch Vehicle concepts.
Effects of range and mode on lifting capability and lifting time.
Lee, Tzu-Hsien
2012-01-01
This study examined the effects of 3 lifting ranges and 3 lifting modes on maximum lifting capability and total lifting time. The results demonstrated that the maximum lifting capability for FK (from floor to knuckle height) was greater than that for KS (from knuckle height to shoulder height) or FS (from floor to shoulder height). Additionally, asymmetric lifting with initial trunk rotation decreased maximum lifting capability compared with symmetric lifting or asymmetric lifting with final trunk rotation. The difference in total lifting time between KS and FS was not significant, while FK increased total lifting time by ~20% compared with FS even though the travel distance was 50% shorter.
Lift evaluation of a two-dimensional pitching flat plate
NASA Astrophysics Data System (ADS)
Xia, X.; Mohseni, K.
2013-09-01
Several previous experimental and theoretical studies have shown that a leading edge vortex (LEV) on an airfoil or wing can provide lift enhancement. In this paper, unsteady two-dimensional (2D) potential flow theory is employed to model the flow field of a pitching flat plate wing. A multi-vortices model is developed to model both the leading edge and trailing edge vortices (TEVs), which offers improved accuracy compared with using only single vortex at each separation location. The lift is obtained by integrating the unsteady Blasius equation. It is found that the motion of vortices contributes significantly to the overall aerodynamic force on the flat plate. A Kutta-like condition is used to determine the vortex intensity and location at the leading edge for large angle of attack cases; however, it is proposed to relax this condition for small angle of attack cases and apply a 2D shear layer model to calculate the circulation of the new added vortex. The results of the simulation are then compared with classical numerical, theoretical, and experimental data for canonical unsteady flat plat problems. Good agreement with these data is observed. Moreover, these results suggested that the leading edge vortex shedding for small angles of attack should be modeled differently than that for large angles of attack. Finally, the results of vortex motion vs. lift indicate that the slow convection of the LEV creates less negative lift while the rapid shedding of the TEV creates more positive lift. The difference between these two contributions of lift results in a total positive lift that lasts for about two chord-length travel of the plate. It is therefore concluded that the lift enhancement during the LEV "stabilization" above the wing is a combined effect of both the LEV and TEV motion. This also provides the insights for future active flow control of micro aerial vehicles (MAVs) that the formation and shedding process of LEVs and TEVs can be manipulated to provide lift
Pneumatic Spoiler Controls Airfoil Lift
NASA Technical Reports Server (NTRS)
Hunter, D.; Krauss, T.
1991-01-01
Air ejection from leading edge of airfoil used for controlled decrease of lift. Pneumatic-spoiler principle developed for equalizing lift on helicopter rotor blades. Also used to enhance aerodynamic control of short-fuselage or rudderless aircraft such as "flying-wing" airplanes. Leading-edge injection increases maneuverability of such high-performance fixed-wing aircraft as fighters.
ERIC Educational Resources Information Center
Norton, Michael; Piccinino, Kelly
2014-01-01
Research for Action (RFA) is currently in the second year of a five-year external evaluation of the Project Leadership and Investment for Transformation (LIFT) Initiative in the Charlotte-Mecklenburg School District (CMS). Project LIFT is a public-private partnership between CMS and the local philanthropic and business communities in Charlotte,…
ERIC Educational Resources Information Center
Norton, Michael; Piccinino, Kelly
2014-01-01
Research for Action (RFA) has completed its second year of a five-year external evaluation of the Project Leadership and Investment for Transformation (LIFT) Initiative in the Charlotte-Mecklenburg School District (CMS). Project LIFT is a public-private partnership between CMS and the local philanthropic and business communities in Charlotte,…
Espinoza, Kathy
2013-09-01
In a perfect world, a "safe" lift would be 51 pounds if the object is within 7 inches from the front of the body, if it is at waist height, if it is directly in front of the person, if there is a handle on the object, and if the load inside the box/bucket doesn't shift once lifted. If the load to be lifted does not meet all of these criteria, then it is an unsafe lift, and modifications must be made. Modifications would include lightening the load, getting help, or using a mechanical lifting device. There is always a way to turn an unsafe lift into a safer lift. An excellent resource for anyone interested in eliminating some of the hazards associated with lifting is the "Easy Ergonomics" publication from Cal/OSHA. This booklet offers practical advice on how to improve the workplace using engineering and administrative controls, problem-solving strategies and solutions, and a vast amount of ergonomics information and resources. "Easy Ergonomics" can be obtained by calling Cal/OSHA's education and training unit in Sacramento at 800-963-9424. A free copy can be obtained via www.dir.ca.gov/dosh/puborder.asp.
NASA Technical Reports Server (NTRS)
Lancaster, J. W.
1975-01-01
Various types of lighter-than-air vehicles from fully buoyant to semibuoyant hybrids were examined. Geometries were optimized for gross lifting capabilities for ellipsoidal airships, modified delta planform lifting bodies, and a short-haul, heavy-lift vehicle concept. It is indicated that: (1) neutrally buoyant airships employing a conservative update of materials and propulsion technology provide significant improvements in productivity; (2) propulsive lift for VTOL and aerodynamic lift for cruise significantly improve the productivity of low to medium gross weight ellipsoidal airships; and (3) the short-haul, heavy-lift vehicle, consisting of a simple combination of an ellipsoidal airship hull and existing helicopter componentry, provides significant potential for low-cost, near-term applications for ultra-heavy lift missions.
Optimizing the inner loop of the gravitational force interaction on modern processors
Warren, Michael S
2010-12-08
We have achieved superior performance on multiple generations of the fastest supercomputers in the world with our hashed oct-tree N-body code (HOT), spanning almost two decades and garnering multiple Gordon Bell Prizes for significant achievement in parallel processing. Execution time for our N-body code is largely influenced by the force calculation in the inner loop. Improvements to the inner loop using SSE3 instructions has enabled the calculation of over 200 million gravitational interactions per second per processor on a 2.6 GHz Opteron, for a computational rate of over 7 Gflops in single precision (700/0 of peak). We obtain optimal performance some processors (including the Cell) by decomposing the reciprocal square root function required for a gravitational interaction into a table lookup, Chebychev polynomial interpolation, and Newton-Raphson iteration, using the algorithm of Karp. By unrolling the loop by a factor of six, and using SPU intrinsics to compute on vectors, we obtain performance of over 16 Gflops on a single Cell SPE. Aggregated over the 8 SPEs on a Cell processor, the overall performance is roughly 130 Gflops. In comparison, the ordinary C version of our inner loop only obtains 1.6 Gflops per SPE with the spuxlc compiler.
Nielsen, Jakob T; Eghbalnia, Hamid R; Nielsen, Niels Chr
2012-01-01
The exquisite sensitivity of chemical shifts as reporters of structural information, and the ability to measure them routinely and accurately, gives great import to formulations that elucidate the structure-chemical-shift relationship. Here we present a new and highly accurate, precise, and robust formulation for the prediction of NMR chemical shifts from protein structures. Our approach, shAIC (shift prediction guided by Akaikes Information Criterion), capitalizes on mathematical ideas and an information-theoretic principle, to represent the functional form of the relationship between structure and chemical shift as a parsimonious sum of smooth analytical potentials which optimally takes into account short-, medium-, and long-range parameters in a nuclei-specific manner to capture potential chemical shift perturbations caused by distant nuclei. shAIC outperforms the state-of-the-art methods that use analytical formulations. Moreover, for structures derived by NMR or structures with novel folds, shAIC delivers better overall results; even when it is compared to sophisticated machine learning approaches. shAIC provides for a computationally lightweight implementation that is unimpeded by molecular size, making it an ideal for use as a force field.
Wing flexibility enhances load-lifting capacity in bumblebees.
Mountcastle, Andrew M; Combes, Stacey A
2013-05-22
The effect of wing flexibility on aerodynamic force production has emerged as a central question in insect flight research. However, physical and computational models have yielded conflicting results regarding whether wing deformations enhance or diminish flight forces. By experimentally stiffening the wings of live bumblebees, we demonstrate that wing flexibility affects aerodynamic force production in a natural behavioural context. Bumblebee wings were artificially stiffened in vivo by applying a micro-splint to a single flexible vein joint, and the bees were subjected to load-lifting tests. Bees with stiffened wings showed an 8.6 per cent reduction in maximum vertical aerodynamic force production, which cannot be accounted for by changes in gross wing kinematics, as stroke amplitude and flapping frequency were unchanged. Our results reveal that flexible wing design and the resulting passive deformations enhance vertical force production and load-lifting capacity in bumblebees, locomotory traits with important ecological implications.
Dragonfly flight. III. Lift and power requirements.
Wakeling, JM; Ellington, CP
1997-02-01
A mean lift coefficient quasi-steady analysis has been applied to the free flight of the dragonfly Sympetrum sanguineum and the damselfly Calopteryx splendens. The analysis accommodated the yaw and accelerations involved in free flight. For any given velocity or resultant aerodynamic force (thrust), the damselfly mean lift coefficient was higher than that for the dragonfly because of its clap and fling. For both species, the maximum mean lift coefficient L was higher than the steady CL,max. Both species aligned their strokes planes to be nearly normal to the thrust, a strategy that reduces the L required for flight and which is different from the previously published hovering and slow dragonfly flights with stroke planes steeply inclined to the horizontal. Owing to the relatively low costs of accelerating the wing, the aerodynamic power required for flight represents the mechanical power output from the muscles. The maximum muscle mass-specific power was estimated at 156 and 166 W kg-1 for S. sanguineum and C. splendens, respectively. Measurements of heat production immediately after flight resulted in mechanical efficiency estimates of 13 % and 9 % for S. sanguineum and C. splendens muscles, respectively.
Summary of Lift and Lift/Cruise Fan Powered Lift Concept Technology
NASA Technical Reports Server (NTRS)
Cook, Woodrow L.
1993-01-01
A summary is presented of some of the lift and lift/cruise fan technology including fan performance, fan stall, ground effects, ingestion and thrust loss, design tradeoffs and integration, control effectiveness and several other areas related to vertical short takeoff and landing (V/STOL) aircraft conceptual design. The various subjects addressed, while not necessarily pertinent to specific short takeoff/vertical landing (STOVL) supersonic designs being considered, are of interest to the general field of lift and lift/cruise fan aircraft designs and may be of importance in the future. The various wind tunnel and static tests reviewed are: (1) the Doak VZ-4 ducted fan, (2) the 0.57 scale model of the Bell X-22 ducted fan aircraft, (3) the Avrocar, (4) the General Electric lift/cruise fan, (5) the vertical short takeoff and landing (V/STOL) lift engine configurations related to ingestion and consequent thrust loss, (6) the XV-5 and other fan-in-wing stall consideration, (7) hybrid configurations such as lift fan and lift/cruise fan or engines, and (8) the various conceptual design studies by air-frame contractors. Other design integration problems related to small and large V/STOL transport aircraft are summarized including lessons learned during more recent conceptual design studies related to a small executive V/STOL transport aircraft.
In-Flight Subsonic Lift and Drag Characteristics Unique to Blunt-Based Lifting Reentry Vehicles
NASA Technical Reports Server (NTRS)
Saltzman, Edwin J.; Wang, K. Charles; Iliff, Kenneth W.
2007-01-01
Lift and drag measurements have been analyzed for subsonic flight conditions for seven blunt-based reentry-type vehicles. Five of the vehicles are lifting bodies (M2-F1, M2-F2, HL-10, X-24A, and X-24B) and two are wing-body configurations (the X-15 and the Space Shuttle Enterprise). Base pressure measurements indicate that the base drag for full-scale vehicles is approximately three times greater than predicted by Hoerner's equation for three-dimensional bodies. Base drag and forebody drag combine to provide an optimal overall minimum drag (a drag "bucket") for a given configuration. The magnitude of this optimal drag, as well as the associated forebody drag, is dependent on the ratio of base area to vehicle wetted area. Counter-intuitively, the flight-determined optimal minimum drag does not occur at the point of minimum forebody drag, but at a higher forebody drag value. It was also found that the chosen definition for reference area for lift parameters should include the projection of planform area ahead of the wing trailing edge (i.e., forebody plus wing). Results are assembled collectively to provide a greater understanding of this class of vehicles than would occur by considering them individually.
Formation and decay of sensorimotor and associative memory in object lifting.
Nowak, Dennis A; Koupan, Christina; Hermsdörfer, Joachim
2007-08-01
The temporal dynamics of the formation and decay of the memory processes underlying the specification of force when lifting objects of either the same or different weight were investigated. Sensorimotor memory enables rapid force programming to the physical object properties. Associative memory may be used to establish a memory link between a colour cue and object weight. In experiment 1, subjects lifted a constant weight in sets of ten lifts 10 s, 5 min, 1 h and 24 h apart. In experiment 2, subjects learned to associate a colour to two different weights to be lifted in alternation within sets of ten lifts 10 s, 5 min, 1 h and 24 h apart. Results of experiment 1 suggest that the memory related to the physical properties of a given object is rapidly established within a few lifts. However, there is a drift of accuracy of force programming that is observed as early as 10 s after the initial set of lifts. Results of experiment 2 imply that people are able to quickly establish an association between visual colour cues and particular object weights. Importantly, the formation of such memory appears to reduce the drift in accuracy observed in experiment 1 and provides the precise programming of grip and lift forces according to the physical object properties for up to 24 h.
ERIC Educational Resources Information Center
Barnes, Francis; Potter, Ann
1974-01-01
Presents theoretical fundamentals of sideways forces exerted on a cricket ball, an aerofoil, and a yacht, involving the properties of boundary layers and a description of velocity and circulation. (CC)
Maximum isometric lifting strengths of men in teamwork.
Lee, Tzu-Hsien
2004-01-01
This study reexamined the additivity of maximum isometric teamwork lifting strength using experienced and height-matched young male participants. The maximum isometric lifting strength was measured for four exertion heights (45, 75, 105, and 140 cm) and four lifting styles (one-, two, three-, and four-person exertions). The results showed that actual teamwork strength could be greater or lower than the sum of individual strengths. If it was greater, the difference between the two could be either significant or nonsignificant, but if it was lower, there was no significant difference between the two. Actual teamwork strength ranged from 90.0% to 134.8% of the sum of individual strengths, indicating that experienced and height-matched participants could overcome the problem of lack of coordination in isometric teamwork lifting. The results also showed that some teamwork members, especially weaker members, might be forced to exert strengths higher than their maximum individual voluntary strengths in teamwork lifting. To avoid such overexertion in teamwork, it is recommended that the weight of the handled load be controlled and lower than the sum of all members' strengths. Additionally, members with significantly different strength abilities should not be assigned to the same team. Actual or potential applications of this research include designing member assignments in teamwork lifting tasks.
Lifting strength in two-person teamwork.
Lee, Tzu-Hsien
2016-01-01
This study examined the effects of lifting range, hand-to-toe distance, and lifting direction on single-person lifting strengths and two-person teamwork lifting strengths. Six healthy males and seven healthy females participated in this study. Two-person teamwork lifting strengths were examined in both strength-matched and strength-unmatched groups. Our results showed that lifting strength significantly decreased with increasing lifting range or hand-to-toe distance. However, lifting strengths were not affected by lifting direction. Teamwork lifting strength did not conform to the law of additivity for both strength-matched and strength-unmatched groups. In general, teamwork lifting strength was dictated by the weaker of the two members, implying that weaker members might be exposed to a higher potential danger in teamwork exertions. To avoid such overexertion in teamwork, members with significantly different strength ability should not be assigned to the same team.
NASA Astrophysics Data System (ADS)
Yeh, Po-Chen; Chung, Tien-Kan; Lai, Chen-Hung; Wang, Chieh-Min
2016-01-01
This paper presents a magnetic-piezoelectric smart material-structure using a novel magnetic-force-interaction approach to optimize the sensitivity of conventional piezoelectric current sensing technologies. The smart material-structure comprises a CuBe-alloy cantilever beam, a piezoelectric PZT sheet clamped to the fixed end of the beam, and an NdFeB permanent magnet mounted on the free end of the beam. When the smart material-structure is placed close to an AC conductor, the magnet on the beam of the smart structure experiences an alternating magnetic attractive and repulsive force produced by the conductor. Thus, the beam vibrates and subsequently generates a strain in the PZT sheet. The strain produces a voltage output because of the piezoelectric effect. The magnetic force interaction is specifically enhanced through the optimization approach (i.e., achieved by using SQUID and machining method to reorient the magnetization to different directions to maximize the magnetic force interaction). After optimizing, the beam's vibration amplitude is significantly enlarged and, consequently, the voltage output is substantially increased. The experimental results indicated that the smart material-structure optimized by the proposed approach produced a voltage output of 4.01 Vrms with a sensitivity of 501 m Vrms/A when it was placed close to a conductor with a current of 8 A at 60 Hz. The optimized voltage output and sensitivity of the proposed smart structure were approximately 316 % higher than those (1.27 Vrms with 159 m Vrms/A) of representative piezoelectric-based current sensing technologies presented in other studies. These improvements can significantly enable the development of more self-powered wireless current sensing applications in the future.
Hydro-resistive measurement of dynamic lifting strength.
Pinder, A D; Grieve, D W
1997-04-01
A device is described for measuring strength and power outputs of dynamic vertical lifts between heights of 0.4 and 2.2 m. The device is safe, robust, and easily transportable. It consists of a water-filled tube 2 m high and 200 mm internal diameter. The subject pulls vertically on a handle which is connected with flexible wire rope via a series of pulleys to a piston suspended inside the tube. The piston has holes which can be closed with bungs. The drag force is proportional to the square of the velocity. The constant of proportionality can be chosen over a more than 100-fold range and is independent of temperature. Manual force is measured using a strain gauged cantilever over which the rope passes. Rope movement is monitored with a shaft encoder. These devices are sampled synchronously by an interfaced computer. Velocity and power are derived from the measurements of displacement, time and force. The device is highly accurate. Power measurements are not significantly different on two separate days although repetitions on one day show a warming-up effect. This device allows the study of dynamic lifts ranging from slow, high force, quasi-isokinetic lifts to lifts where high velocities and accelerations occur.
Detail of counterweight wire rope attachment to lift span at ...
Detail of counterweight wire rope attachment to lift span at southwest corner. The plates with three pins serve to equalize the forces on the counterweight ropes. - Potomac Edison Company, Chesapeake & Ohio Canal Bridge, Spanning C & O Canal South of U.S. 11, Williamsport, Washington County, MD
On the lift induced drag in viscous flows
NASA Astrophysics Data System (ADS)
Tognaccini, Renato; Marongiu, Claudio; Ueno, Makoto
2012-11-01
As stated by Spalart (JFM, 2008): ``An ambition which will have to wait is a rigorous definition of induced drag in viscous flows.'' The idea that there is a link between the aerodynamic force and the Lamb vector, defined as the cross product of fluid vorticity and velocity dates back to Prandtl. Saffman (``Vortex Dynamics,'' 1992) and, more recently, Wu J.-Z. et al. (JFM, 2007) suggested an expression of the lift induced drag in terms of vortex force (the volume integral of the Lamb vector). In this paper we analyze the steady incompressible flow around a 3D lifting body at high Reynolds numbers. The suggested connection between vortex force and induced drag is discussed in detail. In particular, a rigorous definition of the lift induced drag in viscous flows without ambiguities is proposed. A numerical experiment: the analysis of the flow around an elliptic wing will confirm the theoretical analysis. The aerodynamic force and its lift and drag components are computed by integration of the Lamb vector field as obtained by a numerical solution and will be compared with classical expressions.
Using Statcast to lift the discussion of projectile motion
NASA Astrophysics Data System (ADS)
Siegel, P. B.
2017-04-01
Home run data from Major League Baseball's Statcast can be described by adding a lift force to the equations of projectile motion commonly used in undergraduate computational physics courses. We discuss how the Statcast data can be implemented in the classroom.
Fixed Wordsize Implementation of Lifting Schemes
NASA Astrophysics Data System (ADS)
Karp, Tanja
2006-12-01
We present a reversible nonlinear discrete wavelet transform with predefined fixed wordsize based on lifting schemes. Restricting the dynamic range of the wavelet domain coefficients due to a fixed wordsize may result in overflow. We show how this overflow has to be handled in order to maintain reversibility of the transform. We also perform an analysis on how large a wordsize of the wavelet coefficients is needed to perform optimal lossless and lossy compressions of images. The scheme is advantageous to well-known integer-to-integer transforms since the wordsize of adders and multipliers can be predefined and does not increase steadily. This also results in significant gains in hardware implementations.
The mechanisms of lift enhancement in insect flight
NASA Astrophysics Data System (ADS)
Lehmann, Fritz-Olaf
Recent studies have revealed a diverse array of fluid dynamic phenomena that enhance lift production during flapping insect flight. Physical and analytical models of oscillating wings have demonstrated that a prominent vortex attached to the wing's leading edge augments lift production throughout the translational parts of the stroke cycle, whereas aerodynamic circulation due to wing rotation, and possibly momentum transfer due to a recovery of wake energy, may increase lift at the end of each half stroke. Compared to the predictions derived from conventional steady-state aerodynamic theory, these unsteady aerodynamic mechanisms may account for the majority of total lift produced by a flying insect. In addition to contributing to the lift required to keep the insect aloft, manipulation of the translational and rotational aerodynamic mechanisms may provide a potent means by which a flying animal can modulate direction and magnitude of flight forces for manoeuvring flight control and steering behaviour. The attainment of flight, including the ability to control aerodynamic forces by the neuromuscular system, is a classic paradigm of the remarkable adaptability that flying insects have for utilising the principles of unsteady fluid dynamics. Applying these principles to biology broadens our understanding of how the diverse patterns of wing motion displayed by the different insect species have been developed throughout their long evolutionary history.
Crossflow force transducer. [LMFBR
Mulcahy, T M
1982-05-01
A force transducer for measuring lift and drag coefficients for a circular cylinder in turbulent water flow is presented. In addition to describing the actual design and construction of the strain-gauged force- ring based transducer, requirements for obtained valid fluid force test data are discussed, and pertinent flow test experience is related.
High-lift calculations using Navier-Stokes methods
NASA Astrophysics Data System (ADS)
Larsson, Torbjoern
Wing sections on an aircraft are designed for optimal cruise performance, whereas during the take-off and landing phase totally different lift-to-drag characteristics are needed. High lift and low drag is essential while taking off, on the other hand high lift and high drag is favorable when landing. The design and shaping of the high-lift system can have a major influence on the overall economy and safety of the aircraft. In a historical perspective experimental investigations have been the only way to gain any deeper knowledge of the performance of a given wing-flap configuration. Today, computational methods for high-lift systems based on the viscid-inviscid interaction approach with integral methods for boundary layers and wakes are quite common. Although fast solutions can be obtained with these methods it is highly desirable to have a numerical method that captures the flow physics in a more detailed and adequate way. The present wotk demonstrates that Navier-Stokes methods can be used with good results for simulating high-lift flow fields, but also points to the area where further research is needed.
Vigouroux, Laurent; Quaine, Franck; Labarre-Vila, Annick; Amarantini, David; Moutet, François
2007-01-01
Determining tendon tensions of the finger muscles is crucial for the understanding and the rehabilitation of hand pathologies. Since no direct measurement is possible for a large number of finger muscle tendons, biomechanical modelling presents an alternative solution to indirectly evaluate these forces. However, the main problem is that the number of muscles spanning a joint exceeds the number of degrees of freedom of the joint resulting in mathematical under-determinate problems. In the current study, a method using both numerical optimization and the intra-muscular electromyography (EMG) data was developed to estimate the middle finger tendon tensions during static fingertip force production. The method used a numerical optimization procedure with the muscle stress squared criterion to determine a solution while the EMG data of three extrinsic hand muscles serve to enforce additional inequality constraints. The results were compared with those obtained with a classical numerical optimization and a method based on EMG only. The proposed method provides satisfactory results since the tendon tension estimations respected the mechanical equilibrium of the musculoskeletal system and were concordant with the EMG distribution pattern of the subjects. These results were not observed neither with the classical numerical optimization nor with the EMG-based method. This study demonstrates that including the EMG data of the three extrinsic muscles of the middle finger as inequality constraints in an optimization process can yield relevant tendon tensions with regard to individual muscle activation patterns, particularly concerning the antagonist muscles.
Null lifts and projective dynamics
Cariglia, Marco
2015-11-15
We describe natural Hamiltonian systems using projective geometry. The null lift procedure endows the tangent bundle with a projective structure where the null Hamiltonian is identified with a projective conic and induces a Weyl geometry. Projective transformations generate a set of known and new dualities between Hamiltonian systems, as for example the phenomenon of coupling-constant metamorphosis. We conclude outlining how this construction can be extended to the quantum case for Eisenhart–Duval lifts.
Vortex Lift Augmentation by Suction
NASA Technical Reports Server (NTRS)
Taylor, A. H.; Jackson, L. R.; Huffman, J. K.
1983-01-01
Lift performance is improved on a 60 degrees swept Gothic wing. Vortex lift at moderate to high angles of attack on highly swept wings used to improve takeoff performance and maneuverability. New design proposed in which suction of propulsion system augments vortex. Turbofan placed at down stream end of leading-edge vortex system induces vortex to flow into inlet which delays onset of vortex breakdown.
Estimation of unsteady lift on a pitching airfoil from wake velocity surveys
NASA Technical Reports Server (NTRS)
Zaman, K. B. M. Q.; Panda, J.; Rumsey, C. L.
1993-01-01
The results of a joint experimental and computational study on the flowfield over a periodically pitched NACA0012 airfoil, and the resultant lift variation, are reported in this paper. The lift variation over a cycle of oscillation, and hence the lift hysteresis loop, is estimated from the velocity distribution in the wake measured or computed for successive phases of the cycle. Experimentally, the estimated lift hysteresis loops are compared with available data from the literature as well as with limited force balance measurements. Computationally, the estimated lift variations are compared with the corresponding variation obtained from the surface pressure distribution. Four analytical formulations for the lift estimation from wake surveys are considered and relative successes of the four are discussed.
Isokinetic and isometric lifting capacity of Chinese in relation to the physical demand of job.
Luk, K D K; Lu, W W; Kwan, W W; Hu, Y; Wong, Y W; Law, K K P; Leong, J C Y
2003-03-01
The aim of the study was to formulate normative data for the lifting capacities of a normal Chinese population, in order to establish a basic foundation for further studies and to investigate the relationship between individual attributes including age, gender, height, weight, job physical demand and each type of lifting capacity. Isokinetic and isometric lifting strength at low, waist and shoulder assessment levels were measured using the LIDO Workset II based on a sample of 93 normal Chinese adults (63 men and 30 women) between the ages of 21-51. The 50th percentile score for adult Chinese female's lifting strength was 17.71% lower than the American female while the adult Chinese male's lifting strength was 14.94% lower than the American male. Lifting forces were higher in the 20-40 year age group. The isometric work mode had considerable impact on the lifting capacities, with shoulder level having the highest lifting capacities. The gender and body weight had a significant positive correlation to lifting capacity while job physical demand had a moderate correlation. Age and body heights were weakly correlated to lifting capacity.
Properties of the optimal trajectories for coplanar, aeroassisted orbital transfer
NASA Technical Reports Server (NTRS)
Miele, A.; Wang, T.; Deaton, A. W.
1990-01-01
The optimization of trajectories for coplaner, aeroassisted orbital transfer (AOT) from a high Earth orbit (HEO) to a low Earth orbit (LEO) is examined. In particular, HEO can be a geosynchronous Earth orbit (GEO). It is assumed that the initial and final orbits are circular, that the gravitational field is central and is governed by the inverse square law, and that two impulses are employed, one at HEO exit and one at LEO entry. During the atmospheric pass, the trajectory is controlled via the lift coefficient in such a way that the total characteristic velocity is minimized. First, an ideal optimal trajectory is determined analytically for lift coefficient unbounded. This trajectory is called grazing trajectory, because the atmospheric pass is made by flying at constant altitude along the edge of the atmosphere until the excess velocity is depleted. For the grazing trajectory, the lift coefficient varies in such a way that the lift, the centrifugal force due to the Earth's curvature, the weight, and the Coriolis force due to the Earth's rotation are in static balance. Also, the grazing trajectory minimizes the total characteristic velocity and simultaneously nearly minimizes the peak values of the altitude drop, dynamic pressure, and heating rate. Next, starting from the grazing trajectory results, a real optimal trajectory is determined numerically for the lift coefficient bounded from both below and above. This trajectory is characterized by atmospheric penetration with the smallest possible entry angle, followed by flight at the lift coefficient lower bound. Consistently with the grazing trajectory behavior, the real optimal trajectory minimizes the total characteristic velocity and simultaneously nearly minimizes the peak values of the altitude drop, the dynamic pressure, and the heating rate.
Properties of the optimal trajectories for coplanar, aeroassisted orbital transfer
NASA Astrophysics Data System (ADS)
Miele, A.; Wang, T.; Deaton, A. W.
The optimization of trajectories for coplaner, aeroassisted orbital transfer (AOT) from a high Earth orbit (HEO) to a low Earth orbit (LEO) is examined. In particular, HEO can be a geosynchronous Earth orbit (GEO). It is assumed that the initial and final orbits are circular, that the gravitational field is central and is governed by the inverse square law, and that two impulses are employed, one at HEO exit and one at LEO entry. During the atmospheric pass, the trajectory is controlled via the lift coefficient in such a way that the total characteristic velocity is minimized. First, an ideal optimal trajectory is determined analytically for lift coefficient unbounded. This trajectory is called grazing trajectory, because the atmospheric pass is made by flying at constant altitude along the edge of the atmosphere until the excess velocity is depleted. For the grazing trajectory, the lift coefficient varies in such a way that the lift, the centrifugal force due to the Earth's curvature, the weight, and the Coriolis force due to the Earth's rotation are in static balance. Also, the grazing trajectory minimizes the total characteristic velocity and simultaneously nearly minimizes the peak values of the altitude drop, dynamic pressure, and heating rate. Next, starting from the grazing trajectory results, a real optimal trajectory is determined numerically for the lift coefficient bounded from both below and above. This trajectory is characterized by atmospheric penetration with the smallest possible entry angle, followed by flight at the lift coefficient lower bound. Consistently with the grazing trajectory behavior, the real optimal trajectory minimizes the total characteristic velocity and simultaneously nearly minimizes the peak values of the altitude drop, the dynamic pressure, and the heating rate.
Advances in Engineering Software for Lift Transportation Systems
NASA Astrophysics Data System (ADS)
Kazakoff, Alexander Borisoff
2012-03-01
In this paper an attempt is performed at computer modelling of ropeway ski lift systems. The logic in these systems is based on a travel form between the two terminals, which operates with high capacity cabins, chairs, gondolas or draw-bars. Computer codes AUTOCAD, MATLAB and Compaq-Visual Fortran - version 6.6 are used in the computer modelling. The rope systems computer modelling is organized in two stages in this paper. The first stage is organization of the ground relief profile and a design of the lift system as a whole, according to the terrain profile and the climatic and atmospheric conditions. The ground profile is prepared by the geodesists and is presented in an AUTOCAD view. The next step is the design of the lift itself which is performed by programmes using the computer code MATLAB. The second stage of the computer modelling is performed after the optimization of the co-ordinates and the lift profile using the computer code MATLAB. Then the co-ordinates and the parameters are inserted into a program written in Compaq Visual Fortran - version 6.6., which calculates 171 lift parameters, organized in 42 tables. The objective of the work presented in this paper is an attempt at computer modelling of the design and parameters derivation of the rope way systems and their computer variation and optimization.
Laser-induced forward transfer (LIFT) of congruent voxels
NASA Astrophysics Data System (ADS)
Piqué, Alberto; Kim, Heungsoo; Auyeung, Raymond C. Y.; Beniam, Iyoel; Breckenfeld, Eric
2016-06-01
Laser-induced forward transfer (LIFT) of functional materials offers unique advantages and capabilities for the rapid prototyping of electronic, optical and sensor elements. The use of LIFT for printing high viscosity metallic nano-inks and nano-pastes can be optimized for the transfer of voxels congruent with the shape of the laser pulse, forming thin film-like structures non-lithographically. These processes are capable of printing patterns with excellent lateral resolution and thickness uniformity typically found in 3-dimensional stacked assemblies, MEMS-like structures and free-standing interconnects. However, in order to achieve congruent voxel transfer with LIFT, the particle size and viscosity of the ink or paste suspensions must be adjusted to minimize variations due to wetting and drying effects. When LIFT is carried out with high-viscosity nano-suspensions, the printed voxel size and shape become controllable parameters, allowing the printing of thin-film like structures whose shape is determined by the spatial distribution of the laser pulse. The result is a new level of parallelization beyond current serial direct-write processes whereby the geometry of each printed voxel can be optimized according to the pattern design. This work shows how LIFT of congruent voxels can be applied to the fabrication of 2D and 3D microstructures by adjusting the viscosity of the nano-suspension and laser transfer parameters.
A design method for constellation of lifting reentry vehicles
NASA Astrophysics Data System (ADS)
Xiang, Yu; Kun, Liu
2017-03-01
As the reachable domain of a single lifting reentry vehicle is not large enough to cover the whole globe in a short time, which is disadvantageous to responsive operation, it is of great significance to study on how to construct a constellation of several lifting reentry vehicles to responsively reach any point of the globe. This paper addresses a design method for such a constellation. Firstly, an approach for calculating the reachable domain of a single lifting reentry vehicle is given, using the combination of Gauss Pseudospectral Method and SQP method. Based on that, the entire reachable domain taking the limit of responsive time into consideration is simplified reasonably to reduce the complexity of the problem. Secondly, a Streets-of-Coverage (SOC) method is used to design the constellation and the parameters of the constellation are optimized through simple analysis and comparison. Lastly, a point coverage simulation method is utilized to verify the correctness of the optimization result. The verified result shows that 6 lifting reentry vehicles whose maximum lift-to-drag ratio is 1.7 can reach nearly any point on the earth's surface between -50° and 50° in less than 90 minutes.
Managing tradeoffs in geoengineering through optimal choice of non-uniform radiative forcing
NASA Astrophysics Data System (ADS)
MacMartin, D. G.; Keith, D.; Kravitz, B.; Caldeira, K.
2012-12-01
Solar radiation management (SRM) could be used to offset some or all anthropogenic radiative forcing, with the goal of reducing some of the associated climatic change. However, the degree of compensation will vary, with residual climate changes larger in some regions than others. Similarly, the insolation reduction that best compensates climate changes in one region may not be the same as for another, leading to concerns about equity. We show that optimizing the latitudinal and seasonal distribution of insolation reduction can improve the fidelity with which SRM offsets anthropogenic climate change. Using the HadCM3L general circulation model, we consider three trade-offs: the trade-off between minimizing global rms climate changes and minimizing residual changes at the worst-off location, the trade-off between minimizing global rms climate changes and the average solar reduction required to do so, and the trade-off between minimizing global rms climate changes and maximizing Northern Hemisphere September sea ice, for a given average solar reduction. First, the residual temperature and precipitation changes in the worst-off region can be reduced by 30% relative to uniform insolation reduction, with only a modest impact on global root-mean-square (rms) changes; this has implications for managing regional inequalities. Second, the same rms residual climate changes can be obtained with up to 30% less insolation reduction than with a uniform distribution, implying that it may be possible to reduce side effects and risks of SRM (e.g., ozone depletion from sulfate). Finally, allowing spatial and temporal variability increases the range of trade-offs to be considered, such as the relative importance of restoring Northern Hemisphere sea ice versus minimizing overall climate impacts, or the relative weighting between temperature and precipitation residuals. This raises the question of how to weight different objectives. In summary, decisions involving SRM do not need to be
Gayeski, N.; Armstrong, Peter; Alvira, M.; Gagne, J.; Katipamula, Srinivas
2011-11-30
KGS Buildings LLC (KGS) and Pacific Northwest National Laboratory (PNNL) have developed a simplified control algorithm and prototype low-lift chiller controller suitable for model-predictive control in a demonstration project of low-lift cooling. Low-lift cooling is a highly efficient cooling strategy conceived to enable low or net-zero energy buildings. A low-lift cooling system consists of a high efficiency low-lift chiller, radiant cooling, thermal storage, and model-predictive control to pre-cool thermal storage overnight on an optimal cooling rate trajectory. We call the properly integrated and controlled combination of these elements a low-lift cooling system (LLCS). This document is the final report for that project.
Lift-Off Dynamics in a Simple Jumping Robot
NASA Astrophysics Data System (ADS)
Aguilar, Jeffrey; Lesov, Alex; Wiesenfeld, Kurt; Goldman, Daniel I.
2012-10-01
We study vertical jumping in a simple robot comprising an actuated mass-spring arrangement. The actuator frequency and phase are systematically varied to find optimal performance. Optimal jumps occur above and below (but not at) the robot’s resonant frequency f0. Two distinct jumping modes emerge: a simple jump, which is optimal above f0, is achievable with a squat maneuver, and a peculiar stutter jump, which is optimal below f0, is generated with a countermovement. A simple dynamical model reveals how optimal lift-off results from nonresonant transient dynamics.
Ooe, Hiroaki; Fujii, Mikihiro; Tomitori, Masahiko; Arai, Toyoko
2016-02-01
High-Q factor retuned fork (RTF) force sensors made from quartz tuning forks, and the electric circuits for the sensors, were evaluated and optimized to improve the performance of non-contact atomic force microscopy (nc-AFM) performed under ultrahigh vacuum (UHV) conditions. To exploit the high Q factor of the RTF sensor, the oscillation of the RTF sensor was excited at its resonant frequency, using a stray capacitance compensation circuit to cancel the excitation signal leaked through the stray capacitor of the sensor. To improve the signal-to-noise (S/N) ratio in the detected signal, a small capacitor was inserted before the input of an operational (OP) amplifier placed in an UHV chamber, which reduced the output noise from the amplifier. A low-noise, wideband OP amplifier produced a superior S/N ratio, compared with a precision OP amplifier. The thermal vibrational density spectra of the RTF sensors were evaluated using the circuit. The RTF sensor with an effective spring constant value as low as 1000 N/m provided a lower minimum detection limit for force differentiation. A nc-AFM image of a Si(111)-7 × 7 surface was produced with atomic resolution using the RTF sensor in a constant frequency shift mode; tunneling current and energy dissipation images with atomic resolution were also simultaneously produced. The high-Q factor RTF sensor showed potential for the high sensitivity of energy dissipation as small as 1 meV/cycle and the high-resolution analysis of non-conservative force interactions.
Experimental and simulated control of lift using trailing edge devices
NASA Astrophysics Data System (ADS)
Cooperman, A.; Blaylock, M.; van Dam, C. P.
2014-12-01
Two active aerodynamic load control (AALC) devices coupled with a control algorithm are shown to decrease the change in lift force experienced by an airfoil during a change in freestream velocity. Microtabs are small (1% chord) surfaces deployed perpendicular to an airfoil, while microjets are pneumatic jets with flow perpendicular to the surface of the airfoil near the trailing edge. Both devices are capable of producing a rapid change in an airfoil's lift coefficient. A control algorithm for microtabs has been tested in a wind tunnel using a modified S819 airfoil, and a microjet control algorithm has been simulated for a NACA 0012 airfoil using OVERFLOW. In both cases, the AALC devices have shown the ability to mitigate the changes in lift during a gust.
Lifting a large object from an anisotropic porous bed
NASA Astrophysics Data System (ADS)
Karmakar, Timir; Raja Sekhar, G. P.
2016-09-01
An analytical study of two dimensional problem of lifting an object from the top of a fully saturated rigid porous bed is discussed. It is assumed that the porous bed is anisotropic in nature. The flow within the gap region between the object and the porous bed is assumed to be governed by Stokes equation while the flow within the porous bed is governed by Brinkman equation. The breakout phenomenon for different kinds of soil is reported. The effect of mechanical properties like anisotropic permeability, grain diameter size, and porosity on streamlines, velocity, and force is analyzed. Relevant comparison with C. C. Mei, R. W. Yeung, and K. F. Liu ["Lifting a large object from a porous bed," J. Fluid. Mech. 152, 203-215 (1985)] and Y. Chang, L. H. Huang and F. P. Y. Yang ["Two-dimensional lift-up problem for a rigid porous bed," Phys. Fluids, 27, 053101 (2015)] is done.
Burgers, Phillip; Alexander, David E
2012-01-01
For a century, researchers have used the standard lift coefficient C(L) to evaluate the lift, L, generated by fixed wings over an area S against dynamic pressure, ½ρv(2), where v is the effective velocity of the wing. Because the lift coefficient was developed initially for fixed wings in steady flow, its application to other lifting systems requires either simplifying assumptions or complex adjustments as is the case for flapping wings and rotating cylinders.This paper interprets the standard lift coefficient of a fixed wing slightly differently, as the work exerted by the wing on the surrounding flow field (L/ρ·S), compared against the total kinetic energy required for generating said lift, ½v(2). This reinterpreted coefficient, the normalized lift, is derived from the work-energy theorem and compares the lifting capabilities of dissimilar lift systems on a similar energy footing. The normalized lift is the same as the standard lift coefficient for fixed wings, but differs for wings with more complex motions; it also accounts for such complex motions explicitly and without complex modifications or adjustments. We compare the normalized lift with the previously-reported values of lift coefficient for a rotating cylinder in Magnus effect, a bat during hovering and forward flight, and a hovering dipteran.The maximum standard lift coefficient for a fixed wing without flaps in steady flow is around 1.5, yet for a rotating cylinder it may exceed 9.0, a value that implies that a rotating cylinder generates nearly 6 times the maximum lift of a wing. The maximum normalized lift for a rotating cylinder is 1.5. We suggest that the normalized lift can be used to evaluate propellers, rotors, flapping wings of animals and micro air vehicles, and underwater thrust-generating fins in the same way the lift coefficient is currently used to evaluate fixed wings.
Burgers, Phillip; Alexander, David E.
2012-01-01
For a century, researchers have used the standard lift coefficient CL to evaluate the lift, L, generated by fixed wings over an area S against dynamic pressure, ½ρv2, where v is the effective velocity of the wing. Because the lift coefficient was developed initially for fixed wings in steady flow, its application to other lifting systems requires either simplifying assumptions or complex adjustments as is the case for flapping wings and rotating cylinders. This paper interprets the standard lift coefficient of a fixed wing slightly differently, as the work exerted by the wing on the surrounding flow field (L/ρ·S), compared against the total kinetic energy required for generating said lift, ½v2. This reinterpreted coefficient, the normalized lift, is derived from the work-energy theorem and compares the lifting capabilities of dissimilar lift systems on a similar energy footing. The normalized lift is the same as the standard lift coefficient for fixed wings, but differs for wings with more complex motions; it also accounts for such complex motions explicitly and without complex modifications or adjustments. We compare the normalized lift with the previously-reported values of lift coefficient for a rotating cylinder in Magnus effect, a bat during hovering and forward flight, and a hovering dipteran. The maximum standard lift coefficient for a fixed wing without flaps in steady flow is around 1.5, yet for a rotating cylinder it may exceed 9.0, a value that implies that a rotating cylinder generates nearly 6 times the maximum lift of a wing. The maximum normalized lift for a rotating cylinder is 1.5. We suggest that the normalized lift can be used to evaluate propellers, rotors, flapping wings of animals and micro air vehicles, and underwater thrust-generating fins in the same way the lift coefficient is currently used to evaluate fixed wings. PMID:22629326
Mist lift analysis summary report
Davenport, R.L.
1980-09-01
The mist flow open-cycle OTEC concept proposed by S.L. Ridgway has much promise, but the fluid mechanics of the mist flow are not well understood. The creation of the mist and the possibility of droplet growth leading to rainout (when the vapor can no longer support the mist) are particularly troublesome. This report summarizes preliminary results of a numerical analysis initiated at SERI in FY79 to study the mist-lift process. The analysis emphasizes the mass transfer and fluid mechanics of the steady-state mist flow and is based on one-dimensional models of the mist flow developed for SERI by Graham Wallis. One of Wallis's models describes a mist composed of a single size of drops and another considers several drop sizes. The latter model, further developed at SERI, considers a changing spectrum of discrete drop sizes and incorporates the mathematics describing collisions and growth of the droplets by coalescence. The analysis results show that under conditions leading to maximum lift in the single-drop-size model, the multigroup model predicts significantly reduced lift because of the growth of droplets by coalescence. The predicted lift height is sensitive to variations in the mass flow rate and inlet pressure. Inclusion of a coasting section, in which the drops would rise ballistically without change in temperature, may lead to increased lift within the existing range of operation.
Shape memory alloy resetable spring lift for pedestrian protection
NASA Astrophysics Data System (ADS)
Barnes, Brian M.; Brei, Diann E.; Luntz, Jonathan E.; Strom, Kenneth; Browne, Alan L.; Johnson, Nancy
2008-03-01
Pedestrian protection has become an increasingly important aspect of automotive safety with new regulations taking effect around the world. Because it is increasingly difficult to meet these new regulations with traditional passive approaches, active lifts are being explored that increase the "crush zone" between the hood and rigid under-hood components as a means of mitigating the consequences of an impact with a non-occupant. Active lifts, however, are technically challenging because of the simultaneously high forces, stroke and quick timing resulting in most of the current devices being single use. This paper introduces the SMArt (Shape Memory Alloy ReseTable) Spring Lift, an automatically resetable and fully reusable device, which couples conventional standard compression springs to store the energy required for a hood lift, with Shape Memory Alloys actuators to achieve both an ultra high speed release of the spring and automatic reset of the system for multiple uses. Each of the four SMArt Device subsystems, lift, release, lower and reset/dissipate, are individually described. Two identical complete prototypes were fabricated and mounted at the rear corners of the hood, incorporated within a full-scale vehicle testbed at the SMARTT (Smart Material Advanced Research and Technology Transfer) lab at University of Michigan. Full operational cycle testing of a stationary vehicle in a laboratory setting confirms the ultrafast latch release, controlled lift profile, gravity lower to reposition the hood, and spring recompression via the ratchet engine successfully rearming the device for repeat cycles. While this is only a laboratory demonstration and extensive testing and development would be required for transition to a fielded product, this study does indicate that the SMArt Lift has promise as an alternative approach to pedestrian protection.
McKay, J. Lucas; Ting, Lena H.
2012-01-01
Optimality principles have been proposed as a general framework for understanding motor control in animals and humans largely based on their ability to predict general features movement in idealized motor tasks. However, generalizing these concepts past proof-of-principle to understand the neuromechanical transformation from task-level control to detailed execution-level muscle activity and forces during behaviorally-relevant motor tasks has proved difficult. In an unrestrained balance task in cats, we demonstrate that achieving task-level constraints center of mass forces and moments while minimizing control effort predicts detailed patterns of muscle activity and ground reaction forces in an anatomically-realistic musculoskeletal model. Whereas optimization is typically used to resolve redundancy at a single level of the motor hierarchy, we simultaneously resolved redundancy across both muscles and limbs and directly compared predictions to experimental measures across multiple perturbation directions that elicit different intra- and interlimb coordination patterns. Further, although some candidate task-level variables and cost functions generated indistinguishable predictions in a single biomechanical context, we identified a common optimization framework that could predict up to 48 experimental conditions per animal (n = 3) across both perturbation directions and different biomechanical contexts created by altering animals' postural configuration. Predictions were further improved by imposing experimentally-derived muscle synergy constraints, suggesting additional task variables or costs that may be relevant to the neural control of balance. These results suggested that reduced-dimension neural control mechanisms such as muscle synergies can achieve similar kinetics to the optimal solution, but with increased control effort (≈2×) compared to individual muscle control. Our results are consistent with the idea that hierarchical, task-level neural control
Using Simulation and Optimization to Inform Army Force Structure Reduction Decisions
2014-12-01
reductions elsewhere. In recent TAAs, the Army has used output data from the Marathon model to help inform force structure decisions, in particular with...respect to the rotational operating force. This simulation model is described below. The data from Marathon help focus the task on SRCs with...decisions. 2.4 Marathon Marathon is a simulation model that applies ARFORGEN rules to units in order to fill demands. Inputs include demand; supply, or
Astumian, R. Dean
2015-01-01
A simple model for a chemically driven molecular walker shows that the elastic energy stored by the molecule and released during the conformational change known as the power-stroke (i.e., the free-energy difference between the pre- and post-power-stroke states) is irrelevant for determining the directionality, stopping force, and efficiency of the motor. Further, the apportionment of the dependence on the externally applied force between the forward and reverse rate constants of the power-stroke (or indeed among all rate constants) is irrelevant for determining the directionality, stopping force, and efficiency of the motor. Arguments based on the principle of microscopic reversibility demonstrate that this result is general for all chemically driven molecular machines, and even more broadly that the relative energies of the states of the motor have no role in determining the directionality, stopping force, or optimal efficiency of the machine. Instead, the directionality, stopping force, and optimal efficiency are determined solely by the relative heights of the energy barriers between the states. Molecular recognition—the ability of a molecular machine to discriminate between substrate and product depending on the state of the machine—is far more important for determining the intrinsic directionality and thermodynamics of chemo-mechanical coupling than are the details of the internal mechanical conformational motions of the machine. In contrast to the conclusions for chemical driving, a power-stroke is very important for the directionality and efficiency of light-driven molecular machines and for molecular machines driven by external modulation of thermodynamic parameters. PMID:25606678
Astumian, R Dean
2015-01-20
A simple model for a chemically driven molecular walker shows that the elastic energy stored by the molecule and released during the conformational change known as the power-stroke (i.e., the free-energy difference between the pre- and post-power-stroke states) is irrelevant for determining the directionality, stopping force, and efficiency of the motor. Further, the apportionment of the dependence on the externally applied force between the forward and reverse rate constants of the power-stroke (or indeed among all rate constants) is irrelevant for determining the directionality, stopping force, and efficiency of the motor. Arguments based on the principle of microscopic reversibility demonstrate that this result is general for all chemically driven molecular machines, and even more broadly that the relative energies of the states of the motor have no role in determining the directionality, stopping force, or optimal efficiency of the machine. Instead, the directionality, stopping force, and optimal efficiency are determined solely by the relative heights of the energy barriers between the states. Molecular recognition--the ability of a molecular machine to discriminate between substrate and product depending on the state of the machine--is far more important for determining the intrinsic directionality and thermodynamics of chemo-mechanical coupling than are the details of the internal mechanical conformational motions of the machine. In contrast to the conclusions for chemical driving, a power-stroke is very important for the directionality and efficiency of light-driven molecular machines and for molecular machines driven by external modulation of thermodynamic parameters.
Leary, D.A.
1989-06-01
This thesis examines the impact a START agreement might have on the United States and Soviet strategic nuclear forces. It then proposes an optimum post-START force mix for the United States and the Soviet Union. The current, as well as projected, post-START targeting policies are discussed. It is concluded that the impact of a START agreement on the current U.S. strategic targeting policy will be minimal. Although the target data base will not shrink as much as the forces tasked to cover it, a prioritization of targets is all that should be necessary with a post-START force. A START agreement will mean major reductions in U.S. and Soviet strategic nuclear forces. As proposed in this thesis, only the ICBM leg of the Triad will require any major re-structuring. This would include the addition of mobile ICBM systems. The SLBM and bomber legs will feel minimal changes (i.e., retiring POSEIDON SSBNs and retiring or converting some older B-52s). It is recommended that the B-52 program be cancelled, and funding be re-directed into mobile ICBM systems. By doing so the United States could utilize technology available today to strengthen its forces and not gamble on the low-observable technology which a stealth bomber might have.
Serrated-Planform Lifting-Surfaces
NASA Technical Reports Server (NTRS)
McGrath, Brian E. (Inventor); Wood, Richard M. (Inventor)
1999-01-01
A novel set of serrated-planform lifting surfaces produce unexpectedly high lift coefficients at moderate to high angles-of-attack. Each serration, or tooth, is designed to shed a vortex. The interaction of the vortices greatly enhances the lifting capability over an extremely large operating range. Variations of the invention use serrated-planform lifting surfaces in planes different than that of a primary lifting surface. In an alternate embodiment, the individual teeth are controllably retractable and deployable to provide for active control of the vortex system and hence lift coefficient. Differential lift on multiple serrated-planform lifting surfaces provides a means for vehicle control. The important aerodynamic advantages of the serrated-planform lifting surfaces are not limited to aircraft applications but can be used to establish desirable performance characteristics for missiles, land vehicles, and/or watercraft.
Lift crisis of a spinning table tennis ball
NASA Astrophysics Data System (ADS)
Miyazaki, T.; Sakai, W.; Komatsu, T.; Takahashi, N.; Himeno, R.
2017-03-01
The aerodynamic properties of a spinning table tennis ball were investigated using flight experiments. Using high-speed video cameras, the trajectory and rotation of an official ball (Nittaku 3-Star Premium), which was launched by a three rotor machine, were recorded. The drag and lift coefficients (C D and C L) were determined by analysing the video images. The measurements covered the speed and rotation range of typical table tennis shots in the form of the Reynolds number (Re) and dimensionless spin rate (SP), i.e. 3.0 × 104 < Re < 9.0 × 104 and 0 < SP < 1.0, and C D and C L were obtained as functions of Re and SP. We determined that the lift coefficient C L is not a monotonically increasing function of SP. A deep valley of C L was found around SP = 0.5, and the lift force exerted on a spinning ball almost vanished at Re = 9.0 × 104 and 0.48 < SP < 0.5. These results qualitatively agree with the results from recent wind tunnel tests, but quantitative differences owing to the unsteady nature of the flight experiments remain. This anomaly in the lift coefficient should be called the ‘lift crisis’.
Guan, Dabo; Hubacek, Klaus; Tillotson, Martin; Zhao, Hongyan; Liu, Weidong; Liu, Zhu; Liang, Sai
2014-10-07
China is a country with significant but unevenly distributed water resources. The water stressed North stays in contrast to the water abundant and polluted South defining China's current water environment. In this paper we use the latest available data sets and adopt structural decomposition analysis for the years 1992 to 2007 to investigate the driving forces behind the emerging water crisis in China. We employ four water indicators in China, that is, freshwater consumption, discharge of COD (chemical oxygen demand) in effluent water, cumulative COD and dilution water requirements for cumulative pollution, to investigate the driving forces behind the emerging crisis. The paper finds water intensity improvements can effectively offset annual freshwater consumption and COD discharge driven by per capita GDP growth, but that it had failed to eliminate cumulative pollution in water bodies. Between 1992 and 2007, 225 million tones of COD accumulated in Chinese water bodies, which would require 3.2-8.5 trillion m(3) freshwater, depending on the water quality of the recipient water bodies to dilute pollution to a minimum reusable standard. Cumulative water pollution is a key driver to pollution induced water scarcity across China. In addition, urban household consumption, export of goods and services, and infrastructure investment are the main factors contributing to accumulated water pollution since 2000.
Kahlen, Jens; Salimi, Leila; Sulpizi, Marialore; Peter, Christine; Donadio, Davide
2014-04-10
Many well-established classical biomolecular force fields, fitted on the solvation properties of single ions, do not necessarily describe all the details of ion pairing accurately, especially for complex polyatomic ions. Depending on the target application, it might not be sufficient to reproduce the thermodynamics of ion pairing, but it may also be necessary to correctly capture structural details, such as the coordination mode. In this work, we analyzed how classical force fields can be optimized to yield a realistic description of these different aspects of ion pairing. Given the prominent role of the interactions of negatively charged amino-acid side chains and divalent cations in many biomolecular systems, we chose calcium acetate as a benchmark system to devise a general optimization strategy that we applied to two popular force fields, namely, GROMOS and OPLS-AA. Using experimental association constants and first-principles molecular dynamics simulations as a reference, we found that small modifications of the van der Waals ion-ion interaction parameters allow a systematic improvement of the essential thermodynamic and structural properties of ion pairing.
NASA Astrophysics Data System (ADS)
Shamarokov, A. S.; Zorin, V. M.; Dai, Fam Kuang
2016-03-01
At the current stage of development of nuclear power engineering, high demands on nuclear power plants (NPP), including on their economy, are made. In these conditions, improving the quality of NPP means, in particular, the need to reasonably choose the values of numerous managed parameters of technological (heat) scheme. Furthermore, the chosen values should correspond to the economic conditions of NPP operation, which are postponed usually a considerable time interval from the point of time of parameters' choice. The article presents the technique of optimization of controlled parameters of the heat circuit of a steam turbine plant for the future. Its particularity is to obtain the results depending on a complex parameter combining the external economic and operating parameters that are relatively stable under the changing economic environment. The article presents the results of optimization according to this technique of the minimum temperature driving forces in the surface heaters of the heat regeneration system of the steam turbine plant of a K-1200-6.8/50 type. For optimization, the collector-screen heaters of high and low pressure developed at the OAO All-Russia Research and Design Institute of Nuclear Power Machine Building, which, in the authors' opinion, have the certain advantages over other types of heaters, were chosen. The optimality criterion in the task was the change in annual reduced costs for NPP compared to the version accepted as the baseline one. The influence on the decision of the task of independent variables that are not included in the complex parameter was analyzed. An optimization task was decided using the alternating-variable descent method. The obtained values of minimum temperature driving forces can guide the design of new nuclear plants with a heat circuit, similar to that accepted in the considered task.
Endoscopic brow lifts uber alles.
Patel, Bhupendra C K
2006-12-01
Innumerable approaches to the ptotic brow and forehead have been described in the past. Over the last twenty-five years, we have used all these techniques in cosmetic and reconstructive patients. We have used the endoscopic brow lift technique since 1995. While no one technique is applicable to all patients, the endoscopic brow lift, with appropriate modifications for individual patients, can be used effectively for most patients with brow ptosis. We present the nuances of this technique and show several different fixation methods we have found useful.
Flexural Fillet Geometry Optimization for Design of Force Transducers Used in Aeronautics Testing
NASA Technical Reports Server (NTRS)
Lynn, Keith C.; Dixon, Genevieve
2015-01-01
Force transducer designs used in the ground testing aeronautics community have seen minimal change over the last few decades. With increased focus on data quality and long-term performance capabilities over the life of these instruments, it is critical to investigate new methods that improve these designs. One area of focus in the past few years at NASA has been on the design of the flexural elements of traditional force balance transducers. Many of the heritage balances that have been heavily used over the last few decades have started to develop fatigue cracks. The recent focus on the flexural design of traditional single-piece force balances revolves around the design of these elements such that stress concentrations are minimized, with the overall goal of increasing the fatigue life of the balance. Recent research in the area of using conic shaped fillets in the highly stressed regions of traditional force balances will be discussed, with preliminary numerical and experimental data results. A case study will be presented which discusses integration of this knowledge into a new high-capacity semi-span force balance.
Flexural Fillet Geometry Optimization for Design of Force Transducers Used in Aeronautics Testing
NASA Technical Reports Server (NTRS)
Lynn, Keith C.; Dixon, Genevieve
2014-01-01
Force transducer designs used in the ground testing aeronautics community have seen minimal change over the last few decades. With increased focus on data quality and long- term performance capabilities over the life of these instruments, it is critical to investigate new methods that improve these designs. One area of focus in the past few years at NASA has been on the design of the exural elements of traditional force balance transducers. Many of the heritage balances that have been heavily used over the last few decades have started to develop fatigue cracks. The recent focus on the exural design of traditional single-piece force balances revolves around the design of these elements such that stress concentrations are minimized, with the overall goal of increasing the fatigue life of the balance. Recent research in the area of using conic shaped llets in the highly stressed regions of traditional force balances will be discussed, with preliminary numerical and experimental data results. A case study will be presented which discusses integration of this knowledge into a new high-capacity semi-span force balance
Lift mechanics of downhill skiing and snowboarding
NASA Astrophysics Data System (ADS)
Wu, Q.; Igci, Y.; Andreopoulos, Y.; Xanthos, S.; Weinbaum, S.
2004-11-01
In a recent paper, Feng and Weinbaum (2000), hereafter referred to as F, developed a new type of lubrication theory for highly compressible porous media (e. g., snow) where one can generate lift forces that are several orders of magnitude greater than in classical lubrication theory. Herein we report the first measurements of the pore pressures generated on the time scale of skiing or snowboarding to verify the hypothesis in F. We then extend the F theory to long slender planing surfaces which lie outside the range of validity of the lubrication approximation and, include inertia effects. We derive a new simplified equation for downhill skiing or snowboarding which also describes both edging and turning maneuvers. For the case where there is no edging or turning, we obtain numerical solutions of this equation for snowboarding and analytical asymptotic solutions for skiing. The new experimental and theoretical approach presented herein and the previous F theory have laid the foundation for understanding the mechanism of lift generation in downhill skiing and snowboarding on fresh snow.
Optimization of the Chin Bar of a Composite-Shell Helmet to Mitigate the Upper Neck Force
NASA Astrophysics Data System (ADS)
Farajzadeh Khosroshahi, S.; Galvanetto, U.; Ghajari, M.
2016-11-01
The chin bar of motorcycle full-face helmets is the most likely region of the helmet to sustain impacts during accidents, with a large percentage of these impacts leading to basilar skull fracture. Currently, helmet chin bars are designed to mitigate the peak acceleration at the centre of gravity of isolated headforms, as required by standards, but they are not designed to mitigate the neck force, which is probably the cause of basilar skull fracture, a type of head injury that can lead to fatalities. Here we test whether it is possible to increase the protection of helmet chin bars while meeting standard requirements. Fibre-reinforced composite shells are commonly used in helmets due to their lightweight and energy absorption characteristics. We optimize the ply orientation of a chin bar made of fibre-reinforced composite layers for reduction of the neck force in a dummy model using a computational approach. We use the finite element model of a human head/neck surrogate and measure the neck axial force, which has been shown to be correlated with the risk of basilar skull fracture. The results show that by varying the orientation of the chin bar plies, thus keeping the helmet mass constant, the neck axial force can be reduced by approximately 30% while ensuring that the helmet complies with the impact attenuation requirements prescribed in helmet standards.
Makhoul, Paul J; Sinden, Kathryn E; MacPhee, Renée S; Fischer, Steven L
2017-04-01
Paramedics represent a unique occupational group where the nature of their work, providing prehospital emergency care, makes workplace modifications to manage and control injury risks difficult. Therefore, the provision of workplace education and training to support safe lifting remains a viable and important approach. There is, however, a lack of evidence describing movement strategies that may be optimal for paramedic work. The purpose of this study was to determine if a strategy leveraging a greater contribution of work from the lower body relative to the torso was associated with lower biomechanical exposures on the spine. Twenty-five active duty paramedics performed 3 simulated lifting activities common to paramedic work. Ground reaction forces and whole body kinematics were recorded to calculate: peak spine moment and angle about the L4/L5 flexion-extension axis as indicators of biomechanical exposure; and, joint work, integrated from net joint power as a measure of technique inclusive of movement dynamics. Paramedics generating more work from the lower body, relative to the trunk, were more likely to experience lower peak L4/L5 spine moments and angles. These data can inform the development of workplace training and education on safe lifting that focuses on paramedics generating more work from the lower body.
Rengifo, Carlos; Aoustin, Yannick; Plestan, Franck; Chevallereau, Christine
2010-04-01
In this paper, a new neuromusculoskeletal simulation strategy is proposed. It is based on a cascade control approach with an inner muscular-force control loop and an outer joint-position control loop. The originality of the work is located in the optimization criterion used to distribute forces between synergistic and antagonistic muscles. The cost function and the inequality constraints depend on an estimation of the muscle fiber length and its time derivative. The advantages of a such criterion are exposed by theoretical analysis and numerical tests. The simulation model used in the numerical tests consists in an anthropomorphic arm model composed by two joints and six muscles. Each muscle is modeled as a second-order dynamical system including activation and contraction dynamics. Contraction dynamics is represented using a classical Hill's model.
Inducing Lift on Spherical Particles by Traveling Magnetic Fields
NASA Technical Reports Server (NTRS)
Mazuruk, Konstantin; Grugel, Richard N.; Rose, M. Franklin (Technical Monitor)
2001-01-01
Gravity induced sedimentation of suspensions is a serious drawback to many materials and biotechnology processes, a factor that can, in principle, be overcome by utilizing an opposing Lorentz body force. In this work we demonstrate the utility of employing a traveling magnetic field (TMF) to induce a lifting force on particles dispersed in the fluid. Theoretically, a model has been developed to ascertain the net force, induced by TMF, acting on a spherical body as a function of the fluid medium's electrical conductivity and other parameters. Experimentally, the model is compared to optical observations of particle motion in the presence of TMF.
NASA Technical Reports Server (NTRS)
Raiszadeh, Ben; Queen, Eric M.
2002-01-01
A capability to simulate trajectories Of Multiple interacting rigid bodies has been developed. This capability uses the Program to Optimize Simulated Trajectories II (POST II). Previously, POST II had the ability to simulate multiple bodies without interacting forces. The current implementation is used for the Simulation of parachute trajectories, in which the parachute and suspended bodies can be treated as rigid bodies. An arbitrary set of connecting lines can be included in the model and are treated as massless spring-dampers. This paper discusses details of the connection line modeling and results of several test cases used to validate the capability.
Ranganathan, Sridhar; Suthers, Patrick F.; Maranas, Costas D.
2010-01-01
Computational procedures for predicting metabolic interventions leading to the overproduction of biochemicals in microbial strains are widely in use. However, these methods rely on surrogate biological objectives (e.g., maximize growth rate or minimize metabolic adjustments) and do not make use of flux measurements often available for the wild-type strain. In this work, we introduce the OptForce procedure that identifies all possible engineering interventions by classifying reactions in the metabolic model depending upon whether their flux values must increase, decrease or become equal to zero to meet a pre-specified overproduction target. We hierarchically apply this classification rule for pairs, triples, quadruples, etc. of reactions. This leads to the identification of a sufficient and non-redundant set of fluxes that must change (i.e., MUST set) to meet a pre-specified overproduction target. Starting with this set we subsequently extract a minimal set of fluxes that must actively be forced through genetic manipulations (i.e., FORCE set) to ensure that all fluxes in the network are consistent with the overproduction objective. We demonstrate our OptForce framework for succinate production in Escherichia coli using the most recent in silico E. coli model, iAF1260. The method not only recapitulates existing engineering strategies but also reveals non-intuitive ones that boost succinate production by performing coordinated changes on pathways distant from the last steps of succinate synthesis. PMID:20419153
Optimization of Process Parameters of Edge Robotic Deburring with Force Control
NASA Astrophysics Data System (ADS)
Burghardt, A.; Szybicki, D.; Kurc, K.; Muszyńska, M.
2016-12-01
The issues addressed in the paper present a part of the scientific research conducted within the framework of the automation of the aircraft engine part manufacturing processes. The results of the research presented in the article provided information in which tolerances while using a robotic control station with the option of force control we can make edge deburring.
The Operational Role of Army National Guard Special Forces: Optimizing an Underutilized Asset
2013-12-01
John Arquilla Chairman, Department of Defense Analysis iii iv THIS PAGE INTENTIONALLY LEFT BLANK v ABSTRACT The demands of the global...HIERARCHY .........10 F. TITLE 32 COMMAND .................................................................................10 G . TITLE 10 COMMAND...24 G . FORCE GENERATION PLANNING DOES NOT INCLUDE ARNG SF
Prosthetic Hand Lifts Heavy Loads
NASA Technical Reports Server (NTRS)
Carden, James R.; Norton, William; Belcher, Jewell G.; Vest, Thomas W.
1991-01-01
Prosthetic hand designed to enable amputee to lift diverse heavy objects like rocks and logs. Has simple serrated end effector with no moving parts. Prosthesis held on forearm by system of flexible straps. Features include ruggedness, simplicity, and relatively low cost.
Powered-Lift Aerodynamics and Acoustics. [conferences
NASA Technical Reports Server (NTRS)
1976-01-01
Powered lift technology is reviewed. Topics covered include: (1) high lift aerodynamics; (2) high speed and cruise aerodynamics; (3) acoustics; (4) propulsion aerodynamics and acoustics; (5) aerodynamic and acoustic loads; and (6) full-scale and flight research.
Application of pneumatic lift and control surface technology to advanced transport aircraft
NASA Technical Reports Server (NTRS)
Englar, Robert J.
1996-01-01
The application of pneumatic (blown) aerodynamic technology to both the lifting and the control surfaces of advanced transport aircraft can provide revolutionary changes in the performance and operation of these vehicles, ranging in speed regime from Advanced Subsonic Transports to the High Speed Civil Transport, and beyond. This technology, much of it based on the Circulation Control Wing blown concepts, can provide aerodynamic force augmentations of 80 to 100 (i.e., return of 80-100 pounds of force per pound of input momentum from the blowing jet). This can be achieved without use of external mechanical surfaces. Clever application of this technology can provide no-moving-part lifting surfaces (wings/tails) integrated into the control system to greatly simplify aircraft designs while improving their aerodynamic performance. Lift/drag ratio may be pneumatically tailored to fit the current phase of the flight, and takeoff/landing performance can be greatly improved by reducing ground roll distances and liftoff/touchdown speeds. Alternatively, great increases in liftoff weights and payloads are possible, as are great reductions in wing and tail planform size, resulting in optimized cruise wing designs. Furthermore, lift generation independent of angle of attack provides much promise for increased safety of flight in the severe updrafts/downdrafts of microbursts and windshears, which is further augmented by the ability to sustain flight at greatly reduced airspeeds. Load-tailored blown wings can also reduce tip vorticity during highlift operations and the resulting vortex wake hazards near terminal areas. Reduced noise may also be possible as these jets can be made to operate at low pressures. The planned presentation will support the above statements through discussions of recent experimental and numerical (CFD) research and development of these advanced blown aerodynamic surfaces, portions of which have been conducted for NASA. Also to be presented will be
Optimal Force Control of Vibro-Impact Systems for Autonomous Drilling Applications
NASA Technical Reports Server (NTRS)
Aldrich, Jack B.; Okon, Avi B.
2012-01-01
The need to maintain optimal energy efficiency is critical during the drilling operations performed on future and current planetary rover missions (see figure). Specifically, this innovation seeks to solve the following problem. Given a spring-loaded percussive drill driven by a voice-coil motor, one needs to determine the optimal input voltage waveform (periodic function) and the optimal hammering period that minimizes the dissipated energy, while ensuring that the hammer-to-rock impacts are made with sufficient (user-defined) impact velocity (or impact energy). To solve this problem, it was first observed that when voice-coil-actuated percussive drills are driven at high power, it is of paramount importance to ensure that the electrical current of the device remains in phase with the velocity of the hammer. Otherwise, negative work is performed and the drill experiences a loss of performance (i.e., reduced impact energy) and an increase in Joule heating (i.e., reduction in energy efficiency). This observation has motivated many drilling products to incorporate the standard bang-bang control approach for driving their percussive drills. However, the bang-bang control approach is significantly less efficient than the optimal energy-efficient control approach solved herein. To obtain this solution, the standard tools of classical optimal control theory were applied. It is worth noting that these tools inherently require the solution of a two-point boundary value problem (TPBVP), i.e., a system of differential equations where half the equations have unknown boundary conditions. Typically, the TPBVP is impossible to solve analytically for high-dimensional dynamic systems. However, for the case of the spring-loaded vibro-impactor, this approach yields the exact optimal control solution as the sum of four analytic functions whose coefficients are determined using a simple, easy-to-implement algorithm. Once the optimal control waveform is determined, it can be used
Nowak, Dennis A; Rosenkranz, Karin; Hermsdörfer, Joachim; Rothwell, John
2004-06-01
When subjects repetitively lift an object, the grip force they select is influenced by the mechanical object properties of the preceding lift. Similar effects on grip force scaling are observed whether the subsequent lift is performed with the same hand or the hand contralateral to the preceding lift. Here we demonstrate that passive vibration of the hand muscles involved in the generation of grip force in the interval between two blocks of lifting trials interferes with predictive grip force scaling. Following ten trials in which subjects lifted an object with constant mechanical properties with the dominant hand, muscle vibration was given to the first interosseus and adductor pollicis muscles of the dominant hand during a 10-min rest period. Compared with the last lift preceding vibration, peak rates of grip force increase and peak grip forces were scaled too high during the first lift following vibration whether the lift was made with the dominant or non-dominant hand. Subjects scaled grip force accurately to the object properties within three lifts following vibration. If subjects rested for 10 min after the first ten trials and received no vibration, then there was no significant difference in the peak grip force or its rate of increase between the last lift preceding rest and the first lift following it. We suggest that vibration impairs the memory processes responsible for predictive grip force scaling. Our data are consistent with the recent suggestion that these memory processes are neither specific for a certain motor action nor do they reflect internal representations of mechanical object properties.
Xu, Dong; Zhang, Yang
2012-07-01
Ab initio protein folding is one of the major unsolved problems in computational biology owing to the difficulties in force field design and conformational search. We developed a novel program, QUARK, for template-free protein structure prediction. Query sequences are first broken into fragments of 1-20 residues where multiple fragment structures are retrieved at each position from unrelated experimental structures. Full-length structure models are then assembled from fragments using replica-exchange Monte Carlo simulations, which are guided by a composite knowledge-based force field. A number of novel energy terms and Monte Carlo movements are introduced and the particular contributions to enhancing the efficiency of both force field and search engine are analyzed in detail. QUARK prediction procedure is depicted and tested on the structure modeling of 145 nonhomologous proteins. Although no global templates are used and all fragments from experimental structures with template modeling score >0.5 are excluded, QUARK can successfully construct 3D models of correct folds in one-third cases of short proteins up to 100 residues. In the ninth community-wide Critical Assessment of protein Structure Prediction experiment, QUARK server outperformed the second and third best servers by 18 and 47% based on the cumulative Z-score of global distance test-total scores in the FM category. Although ab initio protein folding remains a significant challenge, these data demonstrate new progress toward the solution of the most important problem in the field.
ERIC Educational Resources Information Center
Bogacz, Rafal; Brown, Eric; Moehlis, Jeff; Holmes, Philip; Cohen, Jonathan D.
2006-01-01
In this article, the authors consider optimal decision making in two-alternative forced-choice (TAFC) tasks. They begin by analyzing 6 models of TAFC decision making and show that all but one can be reduced to the drift diffusion model, implementing the statistically optimal algorithm (most accurate for a given speed or fastest for a given…
46 CFR 64.43 - Lifting fittings.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 46 Shipping 2 2010-10-01 2010-10-01 false Lifting fittings. 64.43 Section 64.43 Shipping COAST... HANDLING SYSTEMS Standards for an MPT § 64.43 Lifting fittings. Each MPT must have attached lifting fittings so that the tank remains horizontal and stable while being moved....
Vertical Lift - Not Just For Terrestrial Flight
NASA Technical Reports Server (NTRS)
Young, Larry A
2000-01-01
Autonomous vertical lift vehicles hold considerable potential for supporting planetary science and exploration missions. This paper discusses several technical aspects of vertical lift planetary aerial vehicles in general, and specifically addresses technical challenges and work to date examining notional vertical lift vehicles for Mars, Titan, and Venus exploration.
Protect Your Back: Guidelines for Safer Lifting.
ERIC Educational Resources Information Center
Cantu, Carolyn O.
2002-01-01
Examines back injury in teachers and child care providers; includes statistics, common causes of back pain (improper alignment, improper posture, improper lifting, and carrying), and types of back pain (acute and chronic). Focuses on preventing back injury, body mechanics for lifting and carrying, and proper lifting and carrying of children. (SD)
Project LIFT: Year Three Student Outcomes Memo
ERIC Educational Resources Information Center
Norton, Michael; Kim, Dae Y.; Long, Daniel A.
2016-01-01
Research for Action (RFA) was commissioned to evaluate changes in student outcomes during the first three years of the Project Leadership and Investment for Transformation (LIFT). This report focuses on two questions: (1) how do LIFT students' behavioral and academic performance compare to those of a matched set of non-LIFT comparison students?;…
An Alternative Maxillary Sinus Lift Technique – Sinu Lift System
T, Parthasaradhi; B, Shivakumar; Kumar, T.S.S.; P, Suganya
2015-01-01
Objectives: Maxillary sinus augmentation surgical techniques have evolved greatly allowing successful placement of dental implants in the atrophic posterior maxillary region. The purpose of the present study is to evaluate the clinical and radiological outcomes and postoperative morbidity of sinus floor elevation procedures performed using the minimally invasive surgical technique the Sinu lift system. Materials and Methods: Sinus lift procedure was done using the sinu lift system by a transcrestal approach and bone augmentation was done on ten systemically healthy patients using β- tricalcium phosphate and platelet rich plasma mix. The study was evaluated upto six months period with bone related parameters being assessed at base line using CT scan, OPG and after six months the results were analysed using SPSS Version 18.0 software (p < 0.01 (0.005). Wilcoxson signed rank sum test was used to correlate between preoperative and postoperative measurements. Implant placements were done at the desired area of sinus augmentation with a two year follow up. (Nobel Biocare, Nobel Biocare Holding AG, Zürich-Flughafen, Switzerland) Results: The augmented sites had a significant increase in the bone parameters at the desired grafted region. The mean gain in bone height as observed in CT Scan had revealed increased measurements from 5.80mm±0.98 to 10.20mm±1.68 at the sixth month evaluation. This was statistically significant (0.005). Clinically, no complications were observed during or after the surgical procedure. Conclusion: Within the limitations of this study, the Sinu lift system with a controlled working action resulted in high procedural success and this procedure may be an alternative to the currently used surgical methods. PMID:25954702
NASA Astrophysics Data System (ADS)
Goodarzi, Avesta; Mohammadi, Masoud
2014-04-01
In this paper, vehicle stability control and fuel economy for a 4-wheel-drive hybrid vehicle are investigated. The integrated controller is designed within three layers. The first layer determines the total yaw moment and total lateral force made by using an optimal controller method to follow the desired dynamic behaviour of a vehicle. The second layer determines optimum tyre force distribution in order to optimise tyre usage and find out how the tyres should share longitudinal and lateral forces to achieve a target vehicle response under the assumption that all four wheels can be independently steered, driven, and braked. In the third layer, the active steering, wheel slip, and electrical motor torque controllers are designed. In the front axle, internal combustion engine (ICE) is coupled to an electric motor (EM). The control strategy has to determine the power distribution between ICE and EM to minimise fuel consumption and allowing the vehicle to be charge sustaining. Finally, simulations performed in MATLAB/SIMULINK environment show that the proposed structure could enhance the vehicle stability and fuel economy in different manoeuvres.
Using Future Value Analysis to Select an Optimal Portfolio of Force Protection Initiatives
2003-03-01
Bard, J.F. “A Comparison of the Analytic Hierarchy Process with Multiattribute Utility Theory : A Case Study,” IIE Transactions, 24: 111-121(November...FVA incorporates the ideals of multi-attribute utility theory , specifically using the VFT process, as well as linear programming optimization...objective methodologies in use today are the analytic hierarchy process (AHP) and multi-attribute utility theory (MAUT). These are two distinct approaches
Serrated trailing edges for improving lift and drag characteristics of lifting surfaces
NASA Technical Reports Server (NTRS)
Vijgen, Paul M. H. W. (Inventor); Howard, Floyd G. (Inventor); Bushnell, Dennis M. (Inventor); Holmes, Bruce J. (Inventor)
1992-01-01
An improvement in the lift and drag characteristics of a lifting surface is achieved by attaching a serrated panel to the trailing edge of the lifting surface. The serrations may have a saw-tooth configuration, with a 60 degree included angle between adjacent serrations. The serrations may vary in shape and size over the span-wise length of the lifting surface, and may be positioned at fixed or adjustable deflections relative to the chord of the lifting surface.
Complications of Lower Body Lift Surgery in Postbariatric Patients
van Dijk, Martine M.; Klein, Steven; Hoogbergen, Maarten M.
2016-01-01
Background: There is an exponential rise of patients with massive weight loss because of bariatric surgery or lifestyle changes. The result is an increase of patients with folds of redundant skin that may cause physical and psychological problems. The lower body lift is a procedure to correct deformities in the abdomen, mons, flanks, lateral thighs, and buttocks. Complication rates are quite high and could negatively affect the positive outcomes. The purpose of this study is to assess complication rates and to identify predictors of complications to optimize outcomes for patients after lower body lift surgery. Methods: A retrospective analysis of 100 patients who underwent a lower body lift procedure was performed. The patients were reviewed for complications, demographic data, comorbidities, smoking, highest lifetime body mass index, body mass index before lower body lift surgery, percentage of excess weight loss, and amount of tissue excised. Results: The overall complication rate was 78%. Twenty-two percent of the patients had major complications and 56% had minor complications. There is a linear relationship between body mass index before lower body lift surgery and complications (P = 0.03). The percentage of excess weight loss (odds ratio [OR] 0.97; 95% confidence interval [CI] 0.92–1.00), highest lifetime body mass index (OR 1.08; 95% CI 1.01–1.15), body mass index before lower body lift surgery (OR 1.17; 95% CI 1.02–1.33), and smoking (OR 7.74; CI 0.98–61.16) are significantly associated with the development of complications. Conclusions: This study emphasizes the importance of a good weight status before surgery and cessation of smoking to minimize the risk of complications. PMID:27757346
Use of passively actuated flaps for enhanced lift for pitching and heaving airfoils
NASA Astrophysics Data System (ADS)
Siala, Firas; Planck, Cameron; Liburdy, James
2014-11-01
The enhanced lift and reduced drag obtained by applying passively actuated leading and trailing flaps to a low aspect ratio flat wing during heaving and pitching at moderate Reynolds numbers (104) is demonstrated. Direct force measurements are obtained during the cyclic motion and are synchronized with the tracking of the motion of the passive flaps. The flaps are controlled using torsion springs and their natural frequency is found to play a dominant role in determining the lift enhancement. Results are shown for a range of heaving and pitching conditions of amplitude and frequency, with the pitching phase offset ninety degrees from the heaving. Flow visualization is used to document the transient wake conditions. The lift and drag forces are shown to be enhanced near the peak effective angle of attack during the cycling motion resulting in a net mean lift increase.
Kim, Ju Yaen; Kinoshita, Misaki; Kume, Satoshi; Gt, Hanke; Sugiki, Toshihiko; Ladbury, John E; Kojima, Chojiro; Ikegami, Takahisa; Kurisu, Genji; Goto, Yuji; Hase, Toshiharu; Lee, Young-Ho
2016-11-01
Although electrostatic interactions between negatively charged ferredoxin (Fd) and positively charged sulfite reductase (SiR) have been predominantly highlighted to characterize complex formation, the detailed nature of intermolecular forces remains to be fully elucidated. We investigated interprotein forces for the formation of an electron transfer complex between Fd and SiR and their relationship to SiR activity using various approaches over NaCl concentrations between 0 and 400 mM. Fd-dependent SiR activity assays revealed a bell-shaped activity curve with a maximum ∼40-70 mM NaCl and a reverse bell-shaped dependence of interprotein affinity. Meanwhile, intrinsic SiR activity, as measured in a methyl viologen-dependent assay, exhibited saturation above 100 mM NaCl. Thus, two assays suggested that interprotein interaction is crucial in controlling Fd-dependent SiR activity. Calorimetric analyses showed the monotonic decrease in interprotein affinity on increasing NaCl concentrations, distinguished from a reverse bell-shaped interprotein affinity observed from Fd-dependent SiR activity assay. Furthermore, Fd:SiR complex formation and interprotein affinity were thermodynamically adjusted by both enthalpy and entropy through electrostatic and non-electrostatic interactions. A residue-based NMR investigation on the addition of SiR to (15)N-labeled Fd at the various NaCl concentrations also demonstrated that a combination of electrostatic and non-electrostatic forces stabilized the complex with similar interfaces and modulated the binding affinity and mode. Our findings elucidate that non-electrostatic forces are also essential for the formation and modulation of the Fd:SiR complex. We suggest that a complex configuration optimized for maximum enzymatic activity near physiological salt conditions is achieved by structural rearrangement through controlled non-covalent interprotein interactions.
Stalnov, Oksana; Ben-Gida, Hadar; Kirchhefer, Adam J.; Guglielmo, Christopher G.; Kopp, Gregory A.; Liberzon, Alexander; Gurka, Roi
2015-01-01
We study the role of unsteady lift in the context of flapping wing bird flight. Both aerodynamicists and biologists have attempted to address this subject, yet it seems that the contribution of unsteady lift still holds many open questions. The current study deals with the estimation of unsteady aerodynamic forces on a freely flying bird through analysis of wingbeat kinematics and near wake flow measurements using time resolved particle image velocimetry. The aerodynamic forces are obtained through two approaches, the unsteady thin airfoil theory and using the momentum equation for viscous flows. The unsteady lift is comprised of circulatory and non-circulatory components. Both approaches are presented over the duration of wingbeat cycles. Using long-time sampling data, several wingbeat cycles have been analyzed in order to cover both the downstroke and upstroke phases. It appears that the unsteady lift varies over the wingbeat cycle emphasizing its contribution to the total lift and its role in power estimations. It is suggested that the circulatory lift component cannot assumed to be negligible and should be considered when estimating lift or power of birds in flapping motion. PMID:26394213
Stalnov, Oksana; Ben-Gida, Hadar; Kirchhefer, Adam J; Guglielmo, Christopher G; Kopp, Gregory A; Liberzon, Alexander; Gurka, Roi
2015-01-01
We study the role of unsteady lift in the context of flapping wing bird flight. Both aerodynamicists and biologists have attempted to address this subject, yet it seems that the contribution of unsteady lift still holds many open questions. The current study deals with the estimation of unsteady aerodynamic forces on a freely flying bird through analysis of wingbeat kinematics and near wake flow measurements using time resolved particle image velocimetry. The aerodynamic forces are obtained through two approaches, the unsteady thin airfoil theory and using the momentum equation for viscous flows. The unsteady lift is comprised of circulatory and non-circulatory components. Both approaches are presented over the duration of wingbeat cycles. Using long-time sampling data, several wingbeat cycles have been analyzed in order to cover both the downstroke and upstroke phases. It appears that the unsteady lift varies over the wingbeat cycle emphasizing its contribution to the total lift and its role in power estimations. It is suggested that the circulatory lift component cannot assumed to be negligible and should be considered when estimating lift or power of birds in flapping motion.
Optimized Model Surfaces for Advanced Atomic Force Microscopy Studies of Surface Nanobubbles.
Song, Bo; Zhou, Yi; Schönherr, Holger
2016-11-01
The formation of self-assembled monolayers (SAMs) of binary mixtures of 16-mercaptohexadecanoic acid (MHDA) and 1-octadecanethiol (ODT) on ultraflat template-stripped gold (TSG) surfaces was systematically investigated to clarify the assembly behavior, composition, and degree of possible phase segregation in light of atomic force microscopy (AFM) studies of surface nanobubbles on these substrates. The data for SAMs on TSG were compared to those obtained by adsorption on rough evaporated gold, as reported in a previous study. Quartz crystal microbalance and surface plasmon resonance data acquired in situ on TSG indicate that similar to SAM formation on conventional evaporated gold substrates ODT and MHDA form monolayers and bilayers, respectively. The second layer on MHDA, whose formation is attributed to hydrogen bonding, can be easily removed by adequate rinsing with water. The favorable agreement of the grazing incidence reflection Fourier transform infrared (GIR FTIR) spectroscopy and contact angle data analyzed with the Israelachvili-Gee model suggests that the binary SAMs do not segregate laterally. This conclusion is fully validated by high-resolution friction force AFM observations down to a length scale of 8-10 nm, which is much smaller than the typical observed surface nanobubble radii. Finally, correspondingly functionalized TSG substrates are shown to be valuable supports for studying surface nanobubbles by AFM in water and for addressing the relation between surface functionality and nanobubble formation and properties.
Aerodynamics of Supersonic Lifting Bodies
1981-02-01
verso of front cover. 19 Y WOROS (Continue on rt.’,;erso side i recessary and identily by block number) Theoretical Aerodynamics Lifting Bodies Wind ...waverider solution, developed from the supersonic wedge flow solution, is then i Fused to fashion vertLcal stabilizer-likh control surfaces. Wind ...served as Project Engineers ror thE wind tunnel work. Important contributions were also made bv: Mr. iis±ung Miin; Lee, -M. Beom-Soo Kim, Mtr. Martin Weeks
NASA Astrophysics Data System (ADS)
Lu, Lin; Qin, Jian-Min; Teng, Bin; Li, Yu-Cheng
2011-03-01
This article describes a strategy of active flow control for lift force reduction of circular cylinder subjected to uniform flow at low Reynolds numbers. The flow control is realized by rotationally oscillating the circular cylinder about its axis with ω(t )=-λCL(t), where ω(t ) is the dimensionless angular speed of rotation cylinder, λ is the control parameter and CL(t) is the feedback signal of lift coefficient. The study focuses on seeking optimum λ for the low Reynolds numbers of 60, 80, 100, 150, and 200. The effectiveness of the proposed flow control in suppressing lift force is examined comprehensively by a numerical model based on the finite element solution of two-dimensional Navier-Stokes equations. The dependence of lift reduction on the control parameter λ is investigated. The threshold of λ, denoted by λc, is identified for the Reynolds numbers considered in this work. The numerical results show that the present active rotary oscillation of circular cylinder is able to reduce the amplitude of lift force significantly as long as λ ≤λc, at least 50% for the laminar flow regime. Meanwhile, the present active flow control does not result in the undesirable increase in the drag force. The Strouhal number is observed to decrease slightly with the increase of λ. As for a specific Reynolds number, the larger λ gives rise to the larger amount of lift reduction. The lift reduction reaches the maximum at λ =λc. The mechanism behind the present lift reduction method is revealed by comparing the flow patterns and pressure distributions near the active rotationally oscillating circular cylinder and the stationary circular cylinder. It is found that the critical value λc generally increases with Reynolds number. Two types of lift shift are observed in the numerical results for the cases with λ >λc. The first is characterized by the regular fluctuation of lift coefficient but with nonzero mean value, while the second is associated with the
Overview of Fundamental High-Lift Research for Transport Aircraft at NASA
NASA Technical Reports Server (NTRS)
Leavitt, L. D.; Washburn, A. E.; Wahls, R. A.
2007-01-01
NASA has had a long history in fundamental and applied high lift research. Current programs provide a focus on the validation of technologies and tools that will enable extremely short take off and landing coupled with efficient cruise performance, simple flaps with flow control for improved effectiveness, circulation control wing concepts, some exploration into new aircraft concepts, and partnership with Air Force Research Lab in mobility. Transport high-lift development testing will shift more toward mid and high Rn facilities at least until the question: "How much Rn is required" is answered. This viewgraph presentation provides an overview of High-Lift research at NASA.
Lift enhancement by bats' dynamically changing wingspan
Wang, Shizhao; Zhang, Xing; He, Guowei; Liu, Tianshu
2015-01-01
This paper elucidates the aerodynamic role of the dynamically changing wingspan in bat flight. Based on direct numerical simulations of the flow over a slow-flying bat, it is found that the dynamically changing wingspan can significantly enhance the lift. Further, an analysis of flow structures and lift decomposition reveal that the elevated vortex lift associated with the leading-edge vortices intensified by the dynamically changing wingspan considerably contributed to enhancement of the time-averaged lift. The nonlinear interaction between the dynamically changing wing and the vortical structures plays an important role in the lift enhancement of a flying bat in addition to the geometrical effect of changing the lifting-surface area in a flapping cycle. In addition, the dynamically changing wingspan leads to the higher efficiency in terms of generating lift for a given amount of the mechanical energy consumed in flight. PMID:26701882
Generalised Eisenhart lift of the Toda chain
Cariglia, Marco; Gibbons, Gary
2014-02-15
The Toda chain of nearest neighbour interacting particles on a line can be described both in terms of geodesic motion on a manifold with one extra dimension, the Eisenhart lift, or in terms of geodesic motion in a symmetric space with several extra dimensions. We examine the relationship between these two realisations and discover that the symmetric space is a generalised, multi-particle Eisenhart lift of the original problem that reduces to the standard Eisenhart lift. Such generalised Eisenhart lift acts as an inverse Kaluza-Klein reduction, promoting coupling constants to momenta in higher dimension. In particular, isometries of the generalised lift metric correspond to energy preserving transformations that mix coordinates and coupling constants. A by-product of the analysis is that the lift of the Toda Lax pair can be used to construct higher rank Killing tensors for both the standard and generalised lift metrics.
Optimal output feedback control of linear systems in presence of forcing and measurement noise
NASA Technical Reports Server (NTRS)
Joshi, S. M.
1974-01-01
The problem of obtaining an optimal control law, which is constrained to be a linear feedback of the available measurements, for both continuous and discrete time linear systems subjected to additive white process noise and measurement noise was Necessary conditions are obtained for minimizing a quadratic performance function for both finite and infinite terminal time cases. The feedback gains are constrained to be time invariant for the infinite terminal time cases. For all the cases considered, algorithms are derived for generating sequences of feedback gain matrices which successively improve the performance function. A continuous time numerical example is included for the purpose of demonstration.
Automatic protein design with all atom force-fields by exact and heuristic optimization.
Wernisch, L; Hery, S; Wodak, S J
2000-08-18
A fully automatic procedure for predicting the amino acid sequences compatible with a given target structure is described. It is based on the CHARMM package, and uses an all atom force-field and rotamer libraries to describe and evaluate side-chain types and conformations. Sequences are ranked by a quantity akin to the free energy of folding, which incorporates hydration effects. Exact (Branch and Bound) and heuristic optimisation procedures are used to identifying highly scoring sequences from an astronomical number of possibilities. These sequences include the minimum free energy sequence, as well as all amino acid sequences whose free energy lies within a specified window from the minimum. Several applications of our procedure are illustrated. Prediction of side-chain conformations for a set of ten proteins yields results comparable to those of established side-chain placement programs. Applications to sequence optimisation comprise the re-design of the protein cores of c-Crk SH3 domain, the B1 domain of protein G and Ubiquitin, and of surface residues of the SH3 domain. In all calculations, no restrictions are imposed on the amino acid composition and identical parameter settings are used for core and surface residues. The best scoring sequences for the protein cores are virtually identical to wild-type. They feature no more than one to three mutations in a total of 11-16 variable positions. Tests suggest that this is due to the balance between various contributions in the force-field rather than to overwhelming influence from packing constraints. The effectiveness of our force-field is further supported by the sequence predictions for surface residues of the SH3 domain. More mutations are predicted than in the core, seemingly in order to optimise the network of complementary interactions between polar and charged groups. This appears to be an important energetic requirement in absence of the partner molecules with which the SH3 domain interacts, which were not
Savage, Robert J; Best, Stuart A; Carstairs, Greg L; Ham, Daniel J
2012-07-01
Psychophysical assessments, such as the maximum acceptable lift, have been used to establish worker capability and set safe load limits for manual handling tasks in occupational settings. However, in military settings, in which task demand is set and capable workers must be selected, subjective measurements are inadequate, and maximal capacity testing must be used to assess lifting capability. The aim of this study was to establish and compare the relationship between maximal lifting capacity and a self-determined tolerable lifting limit, maximum acceptable lift, across a range of military-relevant lifting tasks. Seventy male soldiers (age 23.7 ± 6.1 years) from the Australian Army performed 7 strength-based lifting tasks to determine their maximum lifting capacity and maximum acceptable lift. Comparisons were performed to identify maximum acceptable lift relative to maximum lifting capacity for each individual task. Linear regression was used to identify the relationship across all tasks when the data were pooled. Strong correlations existed between all 7 lifting tasks (rrange = 0.87-0.96, p < 0.05). No differences were found in maximum acceptable lift relative to maximum lifting capacity across all tasks (p = 0.46). When data were pooled, maximum acceptable lift was equal to 84 ± 8% of the maximum lifting capacity. This study is the first to illustrate the strong and consistent relationship between maximum lifting capacity and maximum acceptable lift for multiple single lifting tasks. The relationship developed between these indices may be used to help assess self-selected manual handling capability through occupationally relevant maximal performance tests.
Lift generation on a flat plate with unsteady motions
NASA Astrophysics Data System (ADS)
Xia, Xi; Mohseni, Kamran
2013-11-01
The leading edge vortex (LEV) on an airfoil or wing has been considered to be one of the most important sources of lift enhancement according to several previous experimental and theoretical studies. In this work, the unsteady 2D potential flow theory is employed to model the flow field of a flat plate wing undergoing unsteady motions. A multi-vortices model is developed to model both the leading edge and trailing edge vortices (TEVs), which offers improved accuracy compared with using only single vortex at each separation location. The lift prediction is obtained by integrating the unsteady Blasius equation. It is found that the motion of vortices contributes significantly to the overall aerodynamic force on the flat plate. The results of the simulation are then compared with classical numerical, theoretical and experimental data for canonical unsteady flat plat problems. Good agreement with these data is observed. Moreover, these results suggests that the leading edge vortex shedding for small angles of attack should be modeled differently than that for large angles of attack. Finally, the results of vortex motion vs. lift indicate that the lift enhancement during the LEV ``stabilization'' above the wing is a combined effect of both the LEV and TEV motion.
Shape optimization of 3D continuum structures via force approximation techniques
NASA Technical Reports Server (NTRS)
Vanderplaats, Garret N.; Kodiyalam, Srinivas
1988-01-01
The existing need to develop methods whereby the shape design efficiency can be improved through the use of high quality approximation methods is addressed. An efficient approximation method for stress constraints in 3D shape design problems is proposed based on expanding the nodal forces in Taylor series with respect to shape variations. The significance of this new method is shown through elementary beam theory calculations and via numerical computations using 3D solid finite elements. Numerical examples including the classical cantilever beam structure and realistic automotive parts like the engine connecting rod are designed for optimum shape using the proposed method. The numerical results obtained from these methods are compared with other published results, to assess the efficiency and the convergence rate of the proposed method.
Characterization and optimization of scan speed for tapping-mode atomic force microscopy
NASA Astrophysics Data System (ADS)
Sulchek, T.; Yaralioglu, G. G.; Quate, C. F.; Minne, S. C.
2002-08-01
Increasing the imaging speed of tapping mode atomic force microscopy (AFM) has important practical and scientific applications. The scan speed of tapping-mode AFMs is limited by the speed of the feedback loop that maintains a constant tapping amplitude. This article seeks to illuminate these limits to scanning speed. The limits to the feedback loop are: (1) slow transient response of probe; (2) instability limitations of high-quality factor (Q) systems; (3) feedback actuator bandwidth; (4) error signal saturation; and the (5) rms-to-dc converter. The article will also suggest solutions to mitigate these limitations. These limitations can be addressed through integrating a faster feedback actuator as well as active control of the dynamics of the cantilever.
Protein model refinement using an optimized physics-based all-atom force field.
Jagielska, Anna; Wroblewska, Liliana; Skolnick, Jeffrey
2008-06-17
One of the greatest challenges in protein structure prediction is the refinement of low-resolution predicted models to high-resolution structures that are close to the native state. Although contemporary structure prediction methods can assemble the correct topology for a large fraction of protein domains, such approximate models are often not of the resolution required for many important applications, including studies of reaction mechanisms and virtual ligand screening. Thus, the development of a method that could bring those structures closer to the native state is of great importance. We recently optimized the relative weights of the components of the Amber ff03 potential on a large set of decoy structures to create a funnel-shaped energy landscape with the native structure at the global minimum. Such an energy function might be able to drive proteins toward their native structure. In this work, for a test set of 47 proteins, with 100 decoy structures per protein that have a range of structural similarities to the native state, we demonstrate that our optimized potential can drive protein models closer to their native structure. Comparing the lowest-energy structure from each trajectory with the starting decoy, structural improvement is seen for 70% of the models on average. The ability to do such systematic structural refinements by using a physics-based all-atom potential represents a promising approach to high-resolution structure prediction.
Moissenet, Florent; Chèze, Laurence; Dumas, Raphaël
2012-06-01
Inverse dynamics combined with a constrained static optimization analysis has often been proposed to solve the muscular redundancy problem. Typically, the optimization problem consists in a cost function to be minimized and some equality and inequality constraints to be fulfilled. Penalty-based and Lagrange multipliers methods are common optimization methods for the equality constraints management. More recently, the pseudo-inverse method has been introduced in the field of biomechanics. The purpose of this paper is to evaluate the ability and the efficiency of this new method to solve the muscular redundancy problem, by comparing respectively the musculo-tendon forces prediction and its cost-effectiveness against common optimization methods. Since algorithm efficiency and equality constraints fulfillment highly belong to the optimization method, a two-phase procedure is proposed in order to identify and compare the complexity of the cost function, the number of iterations needed to find a solution and the computational time of the penalty-based method, the Lagrange multipliers method and pseudo-inverse method. Using a 2D knee musculo-skeletal model in an isometric context, the study of the cost functions isovalue curves shows that the solution space is 2D with the penalty-based method, 3D with the Lagrange multipliers method and 1D with the pseudo-inverse method. The minimal cost function area (defined as the area corresponding to 5% over the minimal cost) obtained for the pseudo-inverse method is very limited and along the solution space line, whereas the minimal cost function area obtained for other methods are larger or more complex. Moreover, when using a 3D lower limb musculo-skeletal model during a gait cycle simulation, the pseudo-inverse method provides the lowest number of iterations while Lagrange multipliers and pseudo-inverse method have almost the same computational time. The pseudo-inverse method, by providing a better suited cost function and an
Bartolomei, Massimiliano; Carmona-Novillo, Estela; Hernández, Marta I; Campos-Martínez, José; Pirani, Fernando; Giorgi, Giacomo; Yamashita, Koichi
2014-02-20
Graphynes are novel two-dimensional carbon-based materials that have been proposed as molecular filters, especially for water purification technologies. We carry out first-principles electronic structure calculations at the MP2C level of theory to assess the interaction between water and graphyne, graphdiyne, and graphtriyne pores. The computed penetration barriers suggest that water transport is unfeasible through graphyne while being unimpeded for graphtriyne. For graphdiyne, with a pore size almost matching that of water, a low barrier is found that in turn disappears if an active hydrogen bond with an additional water molecule on the opposite side of the opening is considered. Thus, in contrast with previous determinations, our results do not exclude graphdiyne as a promising membrane for water filtration. In fact, present calculations lead to water permeation probabilities that are 2 orders of magnitude larger than estimations based on common force fields. A new pair potential for the water-carbon noncovalent component of the interaction is proposed for molecular dynamics simulations involving graphdiyne and water.
Blaya, Miceli Beck Guimaraes; Westphalen, Graziela Henriques; Guimaraes, Magali Beck; Hirakata, Luciana Mayumi
2009-01-01
The aim of this study was to analyze the mechanical behavior of different orthodontic retraction loops. Two designs of orthodontic loops for closing space were analyzed: teardrop-shaped (T) and circle-shaped loop (C), of two different heights (6 and 8 mm), and two types of orthodontic wires (stainless steel - 0.19' x 0.25'; TMA - titanium molybdenum alloy - 0.016' x 0.016'). The sample consisted of 80 loops, divided into 8 groups determined by the combination shape/height/type of wire, which were submitted to tensile testing at a speed of 2 mm/min., to measure the quantity of force generated when activated in the interval of 0.75 mm and 2.25 mm. The results were submitted to the ANOVA and Tukey statistical tests to compare the groups, and the Student's-t test to compare the means of two groups. Statistically higher values were observed for the size 6 mm, circle shape and stainless steel composition. The group "teardrop-8 mm-TMA" together with the group "circle-8 mm-TMA" presented the lowest mean value, differing statistically from all of the other groups. It was concluded that the alloy of the wire and the height of the loop would be more important than the loop design.
New and expected developments in artificial lift
Lea, J.F.; Winkler, H.W.
1994-12-31
Artificial lift is a broad subject. This paper discusses some of the new developments in the major areas of artificial lift. These are (1) beam lift, (2) electrical submersible pumping, (3) gas lift, (4) hydraulic pumping and (5) miscellaneous topics. The beam lift discussion concerns a new rod material, downhole measurements for rod loading, unit design and some miscellaneous topics. The ESP (Electrical Submersible Pump) section includes a discussion on solids handling, downhole sensor technology, new motor temperature limitations, motor efficiency, and other topics. The gas lift discussion includes mention of coiled tubing with gas lift valves internal, a surface controlled gas lift valve concept, and gas lift valve testing and modeling. Hydraulic pumping is used in many locations with deep pay and fairly small production rates. New hydraulic developments include a wider availability of power fluid pumps other than positive displacement pumps, and small jet pumps specifically designed for de-watering gas wells. Some miscellaneous developments include an insertable PC (progressing cavity) pump and improved plunger lift algorithms and equipment.
Holenstein, Claude N.; Silvan, Unai; Snedeker, Jess G.
2017-01-01
The accurate determination of cellular forces using Traction Force Microscopy at increasingly small focal attachments to the extracellular environment presents an important yet substantial technical challenge. In these measurements, uncertainty regarding accuracy is prominent since experimental calibration frameworks at this size scale are fraught with errors – denying a gold standard against which accuracy of TFM methods can be judged. Therefore, we have developed a simulation platform for generating synthetic traction images that can be used as a benchmark to quantify the influence of critical experimental parameters and the associated errors. Using this approach, we show that TFM accuracy can be improved >35% compared to the standard approach by placing fluorescent beads as densely and closely as possible to the site of applied traction. Moreover, we use the platform to test tracking algorithms based on optical flow that measure deformation directly at the beads and show that these can dramatically outperform classical particle image velocimetry algorithms in terms of noise sensitivity and error. We then report how optimized experimental and numerical strategy can improve traction map accuracy, and further provide the best available benchmark to date for defining practical limits to TFM accuracy as a function of focal adhesion size. PMID:28164999
DWPF Air Lift Pump Life Cycle Evaluation
IMRICH, KENNETH
2004-03-15
The Defense Waste Processing Facility (DWPF) air lift pump was successfully tested at Clemson for 72 days of operation. It provided sufficient flow to pump molten glass without excessive foaming. Slurry feeding also did not reveal any problems with cold cap stability. Metallurgically the Inconel 690 (690) portions of the pump were in excellent condition with no visual evidence of degradation even in high flow regions, i.e., air/melt interface and glass discharge regions. Spinel deposits, which completely covered the air passage on one side, were found at the inlet of each platinum/rhodium (Pt/Rh) nozzle. Although the deposits were extensive, they were porous and did not have an adverse effect on the operation of the pump. The technique used to secure the platinum/rhodium nozzles to the 690 housing appeared to be adequate with only minor oxidation of the 690 threads and glass in-leakage. Galvanic attack was observed where the nozzle formed a seal with the 690. Significant pitting of the 690 was observed around the entire seal. Intergranular cracking of the Pt/Rh alloy was extensive but the cause could not be determined. Testing would be required to evaluate the degradation. Data from the performance test and the metallurgical evaluation are being used to modify the design of the first DWPF production air lift pump. It will be fabricated entirely from 690 and use argon as the purge gas. It is intended to have a service life of 6 months. Recommendations for insertion, operation, and inspection of the pump are also included in this report. Performance data collected from the operation of the production pump will be used to further optimize the design. Laboratory exposure tests should also be performed to evaluate the galvanic effect between platinum/rhodium and 690.
Effect of flap deflection on the lift coefficient of wings operating in a biplane configuration
NASA Technical Reports Server (NTRS)
Stasiak, J.
1977-01-01
Biplane models with a lift flap were tested in a wind tunnel to study the effect of flap deflection on the aerodynamic coefficient of the biplane as well as of the individual wings. Optimization of the position flap was carried out, and the effect of changes in the chord length of the lower wing was determined for the aerodynamic structure of a biplane with a lift flap on the upper wing.
The Effect of Aerodynamic Evaluators on the Multi-Objective Optimization of Flatback Airfoils
NASA Astrophysics Data System (ADS)
Miller, M.; Slew, K. Lee; Matida, E.
2016-09-01
With the long lengths of today's wind turbine rotor blades, there is a need to reduce the mass, thereby requiring stiffer airfoils, while maintaining the aerodynamic efficiency of the airfoils, particularly in the inboard region of the blade where structural demands are highest. Using a genetic algorithm, the multi-objective aero-structural optimization of 30% thick flatback airfoils was systematically performed for a variety of aerodynamic evaluators such as lift-to-drag ratio (Cl/Cd), torque (Ct), and torque-to-thrust ratio (Ct/Cn) to determine their influence on airfoil shape and performance. The airfoil optimized for Ct possessed a 4.8% thick trailing-edge, and a rather blunt leading-edge region which creates high levels of lift and correspondingly, drag. It's ability to maintain similar levels of lift and drag under forced transition conditions proved it's insensitivity to roughness. The airfoil optimized for Cl/Cd displayed relatively poor insensitivity to roughness due to the rather aft-located free transition points. The Ct/Cn optimized airfoil was found to have a very similar shape to that of the Cl/Cd airfoil, with a slightly more blunt leading-edge which aided in providing higher levels of lift and moderate insensitivity to roughness. The influence of the chosen aerodynamic evaluator under the specified conditions and constraints in the optimization of wind turbine airfoils is shown to have a direct impact on the airfoil shape and performance.
Lift enhancement by trapped vortex
NASA Technical Reports Server (NTRS)
Rossow, Vernon J.
1992-01-01
The viewgraphs and discussion of lift enhancement by trapped vortex are provided. Efforts are continuously being made to find simple ways to convert wings of aircraft from an efficient cruise configuration to one that develops the high lift needed during landing and takeoff. The high-lift configurations studied here consist of conventional airfoils with a trapped vortex over the upper surface. The vortex is trapped by one or two vertical fences that serve as barriers to the oncoming stream and as reflection planes for the vortex and the sink that form a separation bubble on top of the airfoil. Since the full three-dimensional unsteady flow problem over the wing of an aircraft is so complicated that it is hard to get an understanding of the principles that govern the vortex trapping process, the analysis is restricted here to the flow field illustrated in the first slide. It is assumed that the flow field between the two end plates approximates a streamwise strip of the flow over a wing. The flow between the endplates and about the airfoil consists of a spanwise vortex located between the suction orifices in the endplates. The spanwise fence or spoiler located near the nose of the airfoil serves to form a separated flow region and a shear layer. The vorticity in the shear layer is concentrated into the vortex by withdrawal of fluid at the suction orifices. As the strength of the vortex increases with time, it eventually dominates the flow in the separated region so that a shear or vertical layer is no longer shed from the tip of the fence. At that point, the vortex strength is fixed and its location is such that all of the velocity contributions at its center sum to zero thereby making it an equilibrium point for the vortex. The results of a theoretical analysis of such an idealized flow field are described.
NASA Astrophysics Data System (ADS)
Fyta, Maria; Netz, Roland R.
2012-03-01
Using molecular dynamics (MD) simulations in conjunction with the SPC/E water model, we optimize ionic force-field parameters for seven different halide and alkali ions, considering a total of eight ion-pairs. Our strategy is based on simultaneous optimizing single-ion and ion-pair properties, i.e., we first fix ion-water parameters based on single-ion solvation free energies, and in a second step determine the cation-anion interaction parameters (traditionally given by mixing or combination rules) based on the Kirkwood-Buff theory without modification of the ion-water interaction parameters. In doing so, we have introduced scaling factors for the cation-anion Lennard-Jones (LJ) interaction that quantify deviations from the standard mixing rules. For the rather size-symmetric salt solutions involving bromide and chloride ions, the standard mixing rules work fine. On the other hand, for the iodide and fluoride solutions, corresponding to the largest and smallest anion considered in this work, a rescaling of the mixing rules was necessary. For iodide, the experimental activities suggest more tightly bound ion pairing than given by the standard mixing rules, which is achieved in simulations by reducing the scaling factor of the cation-anion LJ energy. For fluoride, the situation is different and the simulations show too large attraction between fluoride and cations when compared with experimental data. For NaF, the situation can be rectified by increasing the cation-anion LJ energy. For KF, it proves necessary to increase the effective cation-anion Lennard-Jones diameter. The optimization strategy outlined in this work can be easily adapted to different kinds of ions.
Bensmail, D; Sarfeld, A-S; Ameli, M; Fink, G R; Nowak, D A
2012-05-17
The ability to rapidly establish a memory link between arbitrary sensory cues and goal-directed movements is part of our daily motor repertoire. It is unknown if this ability is affected by middle cerebral artery stroke. Eighteen right-handed subjects with a first unilateral middle cerebral artery stroke were studied while performing a precision grip to lift objects of different weights. In a "no cue" condition, a noninformative neutral visual stimulus was presented before each lift, thereby not allowing any judgment about the object weight. In a "cue" condition arbitrary color cues provided advance information about the weight to be lifted in the subsequent trial. Subjects performed both conditions with either hand. During "no cue" trials subjects scaled their grip force according to the weight of the preceding lift, irrespective of the hand performing the lift or the hemisphere affected. The presentation of color cues allowed patients with right hemispheric stroke, but not those with left hemispheric stroke, to scale their grip force according to the weight in the upcoming lift when lifting the weight with the unaffected hand. Color cues did not allow for a predictive scaling of grip force according to the weight of the object to be lifted when lifting with the affected hand, irrespective of the affected hemisphere. These data imply that the ability of visuomotor mapping in the grip-lift task is selectively impaired in the affected hand after right middle cerebral artery stroke, but in both hands after left middle cerebral artery stroke.
Maximum isoinertial lifting capabilities for different lifting ranges and container dimensions.
Lee, Tzu-Hsien
2005-05-01
The aim of this study was to examine the effects of lifting range and container dimension on human maximum isoinertial lifting capability in the sagittal plane. Ten young and experienced lifters were tested for their maximum isoinertial lifting capabilities for 12 different lifting conditions (three lifting ranges x four container dimensions). The results showed that lifting range and container dimension significantly affected human maximum isoinertial lifting capability. The order for the highest to lowest lifting capability for the three lifting ranges was FK (from floor to knuckle height, 0-74 cm), FS (from floor to shoulder height, 0-141 cm) and KS (from knuckle height to shoulder height, 74-141 cm) regardless of the container dimension, and for the four container dimensions was 50 x 35 x 15 cm(3), 70 x 35 x 15 cm(3), 50 x 50 x 15 cm(3) and 70 x 50 x 15 cm(3) regardless of the lifting range. The mean(SD) maximum isoinertial lifting capability ranged from 29.3(3.3) kg for the combination of KS range and 70 x 50 x 15 cm(3) container to 53.2(5.7)kg for the combination of FK range and 50 x 35 x 15 cm(3) container. The results of this study can help our knowledge of human maximum isoinertial lifting capability and designing the upper limit of lifting weight.
Training for lifting; an unresolved ergonomic issue?
Sedgwick, A W; Gormley, J T
1998-10-01
The paper describes a nine year project on lifting training which included nine trans-Australia consensus conferences attended by more than 900 health professionals. Major outcomes were: (1) The essence of lifting work is the need for the performer to cope with variability in task, environment, and self, and the essence of lifting skill is therefore adaptability; (2) the semi-squat approach provides the safest and most effective basis for lifting training; (3) for lifting training to be effective, the basic principles of skill learning must be systematically applied, with adaptability as a specific goal; (4) physical work capacity (aerobic power, strength, endurance, joint mobility) is a decisive ingredient of safe and effective lifting and, in addition to skill learning, should be incorporated in the training of people engaging regularly in heavy manual work; (5) if effective compliance with recommended skilled behaviour is to be achieved, then training must apply the principles and methods appropriate to adult learning and behaviour modification.
Qualitative Features of High Lift Hovering Dynamics and Inertial Manifolds
NASA Astrophysics Data System (ADS)
Gustafson, K.; Leben, R.; McArthur, J.; Mundt, M.
1996-03-01
Hovering aerodynamics, such as that practiced by dragonflys, hummingbirds, and certain other small insects, utilizes special patterns of vorticity to generate high lift flows. Such lift as we measure it computationally on the airfoil surface is in good agreement with downstream thrust measured in the physical laboratory. In this paper we examine the qualitative signatures of this dynamical system. A connection to the theory of inertial manifolds, more specifically the instance of time-dependent slow manifolds, is initiated. Additional interest attaches to the fact that in our compact computational domain, the forcing is on the boundary. Because of its highly oscillatory nature, in this dynamics one proceeds rapidly up the bifurcation ladder at relatively low Reynolds numbers. Thus, aside from its intrinsic interest, the hover model provides an attractive vehicle for a better understanding of dynamical system attractor dynamics and inertial manifold theory.
A comparative study of DRL-lift and lift on integrated polyisobutylene polymer matrices
NASA Astrophysics Data System (ADS)
Dinca, V.; Palla Papavlu, A.; Matei, A.; Luculescu, C.; Dinescu, M.; Lippert, T.; di Pietrantonio, F.; Cannata, D.; Benetti, M.; Verona, E.
2010-11-01
This paper presents a comparative study of polymer pixel on sensors obtained by Laser Induced Forward Transfer (LIFT) assisted by a triazene polymer as Dynamic Release Layer (DRL). Polyisobutylene (PIB) was selected as model for chemoselective polymers which could be used as hydrogen-bond acidic polymer for vapor sensors. PIB films deposited on fused silica, respectively, on triazene polymer coated fused silica substrates were used as targets. Both targets were prepared by Matrix Assisted Pulsed Laser Evaporation (MAPLE). The parameters related to a regular, well-defined transfer were analyzed and compared for the substrates with and without the DRL. The morphological characterization of the transferred PIB was performed by Atomic Force Microscopy (AFM), Optical Microscopy, and Scanning Electron Microscopy (SEM). It was found that a minimal thickness of the dynamic release layer, i.e. 100 nm is required to protect the sensitive PIB polymer in a clean laser transfer process.
Fu, Qiushi; Zhang, Wei; Santello, Marco
2010-07-07
Dexterous object manipulation requires anticipatory control of digit positions and forces. Despite extensive studies on sensorimotor learning of digit forces, how humans learn to coordinate digit positions and forces has never been addressed. Furthermore, the functional role of anticipatory modulation of digit placement to object properties remains to be investigated. We addressed these questions by asking human subjects (12 females, 12 males) to grasp and lift an inverted T-shaped object using precision grip at constrained or self-chosen locations. The task requirement was to minimize object roll during lift. When digit position was not constrained, subjects could have implemented many equally valid digit position-force coordination patterns. However, choice of digit placement might also have resulted in large trial-to-trial variability of digit position, hence challenging the extent to which the CNS could have relied on sensorimotor memories for anticipatory control of digit forces. We hypothesized that subjects would modulate digit placement for optimal force distribution and digit forces as a function of variable digit positions. All subjects learned to minimize object roll within the first three trials, and the unconstrained device was associated with significantly smaller grip forces but larger variability of digit positions. Importantly, however, digit load force modulation compensated for position variability, thus ensuring consistent object roll minimization on each trial. This indicates that subjects learned object manipulation by integrating sensorimotor memories with sensory feedback about digit positions. These results are discussed in the context of motor equivalence and sensorimotor integration of grasp kinematics and kinetics.
Lift generation by the avian tail.
Maybury, W J; Rayner, J M; Couldrick, L B
2001-07-22
Variation with tail spread of the lift generated by a bird tail was measured on mounted, frozen European starlings (Sturnus vulgaris) in a wind tunnel at a typical air speed and body and tail angle of attack in order to test predictions of existing aerodynamic theories modelling tail lift. Measured lift at all but the lowest tail spread angles was significantly lower than the predictions of slender wing, leading edge vortex and lifting line models of lift production. Instead, the tail lift coefficient based on tail area was independent of tail spread, tail aspect ratio and maximum tail span. Theoretical models do not predict bird tail lift reliably and, when applied to tail morphology, may underestimate the aerodynamic optimum tail feather length. Flow visualization experiments reveal that an isolated tail generates leading edge vortices as expected for a low-aspect ratio delta wing, but that in the intact bird body-tail interactions are critical in determining tail aerodynamics: lifting vortices shed from the body interact with the tail and degrade tail lift compared with that of an isolated tail.
The lift-fan aircraft: Lessons learned
NASA Technical Reports Server (NTRS)
Deckert, Wallace H.
1995-01-01
This report summarizes the highlights and results of a workshop held at NASA Ames Research Center in October 1992. The objective of the workshop was a thorough review of the lessons learned from past research on lift fans, and lift-fan aircraft, models, designs, and components. The scope included conceptual design studies, wind tunnel investigations, propulsion systems components, piloted simulation, flight of aircraft such as the SV-5A and SV-5B and a recent lift-fan aircraft development project. The report includes a brief summary of five technical presentations that addressed the subject The Lift-Fan Aircraft: Lessons Learned.
Unsteady lift of a flapping rectangular wing with spanwise stretching-and-retracting
NASA Astrophysics Data System (ADS)
Wang, Shizhao; He, Guowei; Liu, Tianshu; Zhang, Xing
2012-11-01
The unsteady lift acting on a bat-inspired flapping wing model at Reynolds number 300 is numerically investigated. The flapping wing model consists of a rectangular flat-plat with a sinusoidally varying wingspan. The wingspan reaches maximum at the middle of the downstroke, and minimum at the middle of upstroke. It is found that the spanwise stretching-and-retracting during the flapping can enhance lift acting on the wing. The enhancement of lift is not only caused by the difference of lift surface area between the downstroke and upstroke, but also benefits from the increase in the lift coefficient. The enhancement of the vortex force is investigated by examining the flow structures. The spanwise stretching-and-retracting during flapping affects the shedding of the tip vortices and evolution of the leading-edge vortex. The interaction between the detached tip vortices and leading-edge vortex causes a weak negative wake capture mechanisms during the upstroke, which results in a decrease in the magnitude of the minus lift and a increase in the average lift coefficient.
Moulden, Steve
2015-08-20
This project, entitled “Recovery Act: Fuel Cell-Powered Lift Truck Sysco (Houston) Fleet Deployment”, was in response to DOE funding opportunity announcement DE-PS36-08GO98009, Topic 7B, which promotes the deployment of fuel cell powered material handling equipment in large, multi-shift distribution centers. This project promoted large-volume commercialdeployments and helped to create a market pull for material handling equipment (MHE) powered fuel cell systems. Specific outcomes and benefits involved the proliferation of fuel cell systems in 5-to 20-kW lift trucks at a high-profile, real-world site that demonstrated the benefits of fuel cell technology and served as a focal point for other nascent customers. The project allowed for the creation of expertise in providing service and support for MHE fuel cell powered systems, growth of existing product manufacturing expertise, and promoted existing fuel cell system and component companies. The project also stimulated other MHE fleet conversions helping to speed the adoption of fuel cell systems and hydrogen fueling technology. This document also contains the lessons learned during the project in order to communicate the successes and difficulties experienced, which could potentially assist others planning similar projects.
Cai, Yongqing; He, Bingwei; Yang, Xiaoxiang; Yao, Jun
2015-01-01
Transparent tooth correction treatment is an esthetic alternative to traditional orthodontic treatment. Recently, attachments were introduced in transparent tooth correction treatments to improve the predictability of orthodontic movement. In order to optimize the attachment configuration, the force delivery system of attachments in orthodontic aligner treatment was analyzed. Based on mechanical principles, such as the synthesis theorem of force system, Varignon theorem, and the theorem of force translation, the force system of attachment was analyzed. How the attachments affected the orthodontic treatment was investigated. The attachments' force system Fr,Ft,Mr and Mt was determined. The optimum attachment for translation and controlled tipping movement was conceived. The attachments can be designed and placed appropriately to improve tooth movement.
Sakata, Kiyoshi; Kogure, Akira; Hosoda, Masataka; Isozaki, Koji; Masuda, Tadashi; Morita, Sadao
2010-01-01
The purpose of this study was to analyze age-related movement smoothness changes in the lower extremity joints during load lifting. A total of 10 young and 13 elderly subjects participated in the study. Infrared reflective markers were attached to body landmarks in each subject. While the subjects stood on force plates and lifted a box, the marker displacements and ground reaction forces were measured using a 3D motion analysis system. The jerk square mean value (JSM) was defined as the lower extremity joint movement smoothness index during lifting. JSM represented the average of the square of the joint angle third derivative value, according to the jerk third derivative of the position data. Each subject's JSM values were calculated for the hip, knee and ankle joints. Movement smoothness appeared to decrease as JSM increased. Multiple regression analyses were performed for dependent variables (hip, knee and ankle joint JSM values) and independent variables (age, hand grip strength, sex difference and lifting duration). The level of significance was set at p<0.05. For the hip joint JSM, the regression coefficient for age was significantly positive and that for lifting duration was significantly negative. For the knee joint JSM, the regression coefficient for lifting duration was significantly negative. For the ankle joint JSM, the regression coefficients for age and hand grip strength were significantly positive and that for lifting duration was significantly negative. These results suggest that movement smoothness in the hip and ankle joints during lifting decreases with advancing age.
NASA Technical Reports Server (NTRS)
Mendenhall, M. R.; Spangler, S. B.
1976-01-01
A theoretical method has been developed to predict the longitudinal aerodynamic characteristics of engine-wing-flap combinations with externally blown flaps (EBF) and upper surface blowing (USB) high lift devices. Potential flow models of the lifting surfaces and the jet wake are combined to calculate the induced interference of the engine wakes on the lifting surfaces. The engine wakes may be circular, elliptic, or rectangular cross-sectional jets, and the lifting surfaces are comprised of a wing with multiple-slotted trailing-edge flaps or a deflected trailing-edge Coanda surface. Results are presented showing comparisons of measured and predicted forces, pitching moments, span-load distributions, and flow fields.
Analysis of Nonplanar Wing-tip-mounted Lifting Surfaces on Low-speed Airplanes
NASA Technical Reports Server (NTRS)
Vandam, C. P.; Roskam, J.
1983-01-01
Nonplanar wing tip mounted lifting surfaces reduce lift induced drag substantially. Winglets, which are small, nearly vertical, winglike surfaces, are an example of these devices. To achieve reduction in lift induced drag, winglets produce significant side forces. Consequently, these surfaces can seriously affect airplane lateral directional aerodynamic characteristics. Therefore, the effects of nonplanar wing tip mounted surfaces on the lateral directional stability and control of low speed general aviation airplanes were studied. The study consists of a theoretical and an experimental, in flight investigation. The experimental investigation involves flight tests of winglets on an agricultural airplane. Results of these tests demonstrate the significant influence of winglets on airplane lateral directional aerodynamic characteristics. It is shown that good correlations exist between experimental data and theoretically predicted results. In addition, a lifting surface method was used to perform a parametric study of the effects of various winglet parameters on lateral directional stability derivatives of general aviation type wings.
33 CFR 118.85 - Lights on vertical lift bridges.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...
33 CFR 118.85 - Lights on vertical lift bridges.
Code of Federal Regulations, 2013 CFR
2013-07-01
... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of the navigable channel under the span will be marked by a range of two green lights when the vertical lift...
Active Tailoring of Lift Distribution to Enhance Cruise Performance
NASA Technical Reports Server (NTRS)
Flamm, Jeffrey D. (Technical Monitor); Pfeiffer, Neal J.; Christians, Joel G.
2005-01-01
During Phase I of this project, Raytheon Aircraft Company (RAC) has analytically and experimentally evaluated key components of a system that could be implemented for active tailoring of wing lift distribution using low-drag, trailing-edge modifications. Simple systems such as those studied by RAC could be used to enhance the cruise performance of a business jet configuration over a range of typical flight conditions. The trailing-edge modifications focus on simple, deployable mechanisms comprised of extendable small flap panels over portions of the span that could be used to subtly but positively optimize the lift and drag characteristics. The report includes results from low speed wind tunnel testing of the trailing-edge devices, descriptions of potential mechanisms for automation, and an assessment of the technology.
A Quasi-Steady Lifting Line Theory for Insect-Like Hovering Flight
Nabawy, Mostafa R. A.; Crowthe, William J.
2015-01-01
A novel lifting line formulation is presented for the quasi-steady aerodynamic evaluation of insect-like wings in hovering flight. The approach allows accurate estimation of aerodynamic forces from geometry and kinematic information alone and provides for the first time quantitative information on the relative contribution of induced and profile drag associated with lift production for insect-like wings in hover. The main adaptation to the existing lifting line theory is the use of an equivalent angle of attack, which enables capture of the steady non-linear aerodynamics at high angles of attack. A simple methodology to include non-ideal induced effects due to wake periodicity and effective actuator disc area within the lifting line theory is included in the model. Low Reynolds number effects as well as the edge velocity correction required to account for different wing planform shapes are incorporated through appropriate modification of the wing section lift curve slope. The model has been successfully validated against measurements from revolving wing experiments and high order computational fluid dynamics simulations. Model predicted mean lift to weight ratio results have an average error of 4% compared to values from computational fluid dynamics for eight different insect cases. Application of an unmodified linear lifting line approach leads on average to a 60% overestimation in the mean lift force required for weight support, with most of the discrepancy due to use of linear aerodynamics. It is shown that on average for the eight insects considered, the induced drag contributes 22% of the total drag based on the mean cycle values and 29% of the total drag based on the mid half-stroke values. PMID:26252657
Mars Reconnaissance Orbiter (MRO) Lifts Off
NASA Technical Reports Server (NTRS)
2005-01-01
At 7:43 a.m. EDT an Atlas V launch vehicle, 19 stories tall, with a two-ton Mars Reconnaissance Orbiter (MRO) on top, lifts off the pad on Launch Complex 41 at Cape Canaveral Air Force Station in Florida. All systems performed nominally for NASA's first launch of an Atlas V on an interplanetary mission. MRO established radio contact with controllers 61 minutes after launch and within four minutes of separation from the upper stage. Initial contact came through an antenna at the Japan Aerospace Exploration Agency's Uchinoura Space Center in southern Japan. Mars is 72 million miles from Earth today, but the spacecraft will travel more than four times that distance on its outbound-arc trajectory to intercept the red planet on March 10, 2006. The orbiter carries six scientific instruments for examining the surface, atmosphere and subsurface of Mars in unprecedented detail from low orbit. NASA expects to get several times more data about Mars from MRO than from all previous Martian missions combined. Researchers will use the instruments to learn more about the history and distribution of Mars' water. That information will improve understanding of planetary climate change and will help guide the quest to answer whether Mars ever supported life. The orbiter will also evaluate potential landing sites for future missions.
Soccer Ball Lift Coefficients via Trajectory Analysis
ERIC Educational Resources Information Center
Goff, John Eric; Carre, Matt J.
2010-01-01
We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin…
49 CFR 37.203 - Lift maintenance.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 49 Transportation 1 2010-10-01 2010-10-01 false Lift maintenance. 37.203 Section 37.203 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Over-the-Road Buses (OTRBs) § 37.203 Lift maintenance. (a) The entity shall establish...
49 CFR 37.203 - Lift maintenance.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 49 Transportation 1 2012-10-01 2012-10-01 false Lift maintenance. 37.203 Section 37.203 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Over-the-Road Buses (OTRBs) § 37.203 Lift maintenance. (a) The entity shall establish...
49 CFR 37.203 - Lift maintenance.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 49 Transportation 1 2014-10-01 2014-10-01 false Lift maintenance. 37.203 Section 37.203 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Over-the-Road Buses (OTRBs) § 37.203 Lift maintenance. (a) The entity shall establish...
49 CFR 37.203 - Lift maintenance.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 49 Transportation 1 2013-10-01 2013-10-01 false Lift maintenance. 37.203 Section 37.203 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Over-the-Road Buses (OTRBs) § 37.203 Lift maintenance. (a) The entity shall establish...
49 CFR 37.203 - Lift maintenance.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 1 2011-10-01 2011-10-01 false Lift maintenance. 37.203 Section 37.203 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Over-the-Road Buses (OTRBs) § 37.203 Lift maintenance. (a) The entity shall establish...
Training Guidelines: Fork Lift Truck Driving.
ERIC Educational Resources Information Center
Ceramics, Glass, and Mineral Products Industry Training Board, Harrow (England).
This manual of operative training guidelines for fork lift truck driving has been developed by the Ceramics, Glass and Mineral Products Industry Training Board (Great Britain) in consultation with a number of firms which manufacture fork lift trucks or which already have training--programs for their use. The purpose of the guidelines is to assist…
Lea, J.F.; Winker, H.W.
1989-05-01
New developments might be expected to decline as oil, and thus equipment and service, prices decrease. However, there is no indication that this is occurring. In fact, several new and innovative developments are covered in this article. Of the more unique are a new geometry pumping unit and a hydraulic powered sucker and rod system. Other items described in this article include: New pump-off controller; Automatic balancing for air balanced pumping units; New rod couplings; New pump plunger; Sucker rod pulsation dampener; Stripper type BOP; Rod coupling tool; ESP cable protectors; New ESP motor; VSD communications interface; ESP gas separator; Portable hydraulic production test unit; Casing gas lift plunger; Production shut-of valve; Ceramic material for pump parts; Pressure transmitter; and New versatile packer.
NASA Technical Reports Server (NTRS)
Tischler, M. B.; Ringland, R. F.; Jex, H. R.
1983-01-01
The basic aerodynamic and dynamic properties of an example heavy-lift airship (HLA) configuration are analyzed using a nonlinear, multibody, 6-degrees-of-freedom digital simulation. The slung-payload model is described, and a preliminary analysis of the coupled vehicle-payload dynamics is presented. Trim calculations show the importance of control mixing selection and suggest performance deficiencies in crosswind stationkeeping for the unloaded example HLA. Numerically linearized dynamics of the unloaded vehicle exhibit a divergent yaw mode and an oscillatory pitch mode whose stability characteristic is sensitive to flight speed. An analysis of the vehicle-payload dynamics shows significant coupling of the payload dynamics with those of the basic HLA. It is shown that significant improvement in the vehicle's dynamic behavior can be achieved with the incorporation of a simple flight controller having proportional, rate, and integral-error feedbacks.
Self-propulsion of a body with rigid surface and variable coefficient of lift in a perfect fluid
NASA Astrophysics Data System (ADS)
Ramodanov, Sergey M.; Tenenev, Valentin A.; Treschev, Dmitry V.
2012-11-01
We study the system of a 2D rigid body moving in an unbounded volume of incompressible, vortex-free perfect fluid which is at rest at infinity. The body is equipped with a gyrostat and a so-called Flettner rotor. Due to the latter the body is subject to a lifting force (Magnus effect). The rotational velocities of the gyrostat and the rotor are assumed to be known functions of time (control inputs). The equations of motion are presented in the form of the Kirchhoff equations. The integrals of motion are given in the case of piecewise continuous control. Using these integrals we obtain a (reduced) system of first-order differential equations on the configuration space. Then an optimal control problem for several types of the inputs is solved using genetic algorithms.
Blade design trade-offs using low-lift airfoils for stall-regulated HAWTs
Giguere, P.; Selig, M.S.; Tangler, J.L.
1999-11-01
A systematic blade design study was conducted to explore the trade-offs in using low-lift airfoils for a 750-kilowatt stall-regulated wind turbine. Tip-region airfoils having a maximum-lift coefficient ranging from 0.7--1.2 were considered in this study, with the main objective of identifying the practical lower limit for the maximum-life coefficient. Blades were optimized for both maximum annual energy production and minimum cost of energy using a method that takes into account aerodynamic and structural considerations. The results indicate that the effect of the maximum-lift coefficient on the cost of energy is small with a slight advantage to the highest maximum lift coefficient airfoils for the tip-region of the blade become more desirable as machine size increases, provided the airfoils yield acceptable stall characteristics. The conclusions are applicable to large wind turbines that use passive or active stall to regulate peak power.
Evidence for a role of antagonistic cocontraction in controlling trunk stiffness during lifting.
van Dieën, Jaap H; Kingma, Idsart; van der Bug, Petra; van der Bug, J C E
2003-12-01
Activity of the abdominal muscles during symmetric lifting has been a consistent finding in many studies. It has been hypothesized that this antagonistic coactivation increases trunk stiffness to provide stability to the spine. To test this, we investigated whether abdominal activity in lifting is increased in response to destabilizing conditions. Ten healthy male subjects lifted 35 l containers containing 15 l of water (unstable condition), or ice (stable condition). 3D-kinematics, ground reaction forces, and EMG of selected trunk muscles were recorded. Euler angles of the thorax relative to the pelvis were determined. Inverse dynamics was used to calculate moments about L5S1. Averaged normalized abdominal EMG activity was calculated to express coactivation and an EMG-driven trunk muscle model was used to estimate the flexor moment produced by these muscles and to estimate the L5S1 compression force. Abdominal coactivation was significantly higher when lifting the unstable load. This coincided with significant increases in estimated moments produced by the antagonist muscles and in estimated compression forces on the L5S1 disc, except at the instant of the peak moment about L5S1. The lifting style was not affected by load instability as evidenced by the absence of effects on moments about L5S1 and angles of the thorax relative to the pelvis. The data support the interpretation of abdominal cocontraction during lifting as subserving spinal stability. An alternative function of the increased trunk stiffness due to cocontraction might be to achieve more precise control over the trajectory of lifted weight in order to avoid sloshing of the water mass in the box and the consequent perturbations.
View of West end of central lift span truss web ...
View of West end of central lift span truss web of Tensaw River Bridge, showing web brace of lift girder superstructure, looking west - Tensaw River Lift Bridge, Spanning Tensaw River at U.S. Highway 90, Mobile, Mobile County, AL
Optimizing Security Force Generation
2009-06-01
following the end of the Cold War and determined the necessary mixture of active duty and reserve soldiers to meet the Army’s strategic objectives...0.15 0.2 0.25 4 5 6 7 8 9 10 11 12 13 14 15 Pe rc en ta ge of R an k Years Officer Seperation Rate over Planning Horizon Rank 7 Rank 8 Rank 9 Rank 10...15 Pe rc en ta ge of R an k Years Officer Seperation Rate over Planning Horizon Rank 7 Rank 8 Rank 9 Rank 10 Rank 11 Figure 11. Scenario 2
Forced Mixer Nozzle Optimization
NASA Technical Reports Server (NTRS)
Sheoran, Yogi; Hoover, Robert; Schuster, William; Anderson, Morris; Weir, Donald S.
1999-01-01
Computational fluid dynamic (CFD) and computational acoustic analyses (CAA) were performed for a TFE731-40 compound nozzle, a TFE731-60 mixer nozzle and an Energy Efficient Engine (E(sup 3)) mixer nozzle for comparison with available data. The CFD analyses were performed with a three dimensional, Navier-Stokes solution of the flowfield on an unstructured grid using the RAMPANT program. The CAA analyses were performed with the NASA Glenn MGB program using a structured grid. A successful aerodynamic solution for the TFE731-40 compound nozzle operating statically was obtained, simulating an engine operating on a test stand. Analysis of the CFD results of the TFE731-40 with the MGB program produced predicted sound power levels that agree quite well with the measured data front full-scale static engine tests. Comparison of the predicted sound pressure with the data show good agreement near the jet axis, but the noise levels are overpredicted at angles closer to the inlet. The predicted sound power level for the TFE731-60 did not agree as well with measured static engine data as the TFE731-40. Although a reduction in the predicted noise level due to the mixed flow was observed, the reduction was not as significant as the measured data. The analysis of the V2 mixer from the E(sup 3) study showed that peak temperatures predicted in the mixer exit flowfield were within 5 percent of the values measured by the exit probes. The noise predictions of the V2 mixer nozzle tended to be 3-5 dB higher in peak noise level than the measurements. In addition, the maximum frequency of the noise was also overpredicted. An analysis of the 3 candidate mixer nozzle configurations demonstrated the feasibility of using centerbody lobes and porosity to improve mixing efficiency. A final configuration was designed with a predicted thermal mixing efficiency that was 5 percent higher than the 3 candidate mixers. The results of the MGB noise calculations show that the final design will exceed the design goal of a 3 dB reduction in noise as compared to the baseline TFE731-40.
Biomechanical comparison of unilateral and bilateral power snatch lifts.
Lauder, Mike A; Lake, Jason P
2008-05-01
Biomechanical characteristics of the one-handed dumbbell power snatch (DBPS) were examined to determine whether significant differences existed between unilateral and bilateral weightlifting movements. Kinetic and kinematic movement data were recorded from 10 male weightlifters (mean +/- SD: age: 30.2 +/- 10.2 years; height: 174.2 +/- 4.4 cm; body mass: 81.5 +/- 14.6 kg) during one-handed dumbbell (DB) and traditional barbell (BBPS) power snatch performance with loads of approximately 80% of respective lift one repetition maximums (1RM) with the use of 2 synchronized Kistler force plates and high-speed 3-dimensional video. Results highlighted asymmetry in the ground reaction force and kinematic profile of the DBPS, which deviated from the observed patterns of the bilateral movement. This study found that the nonlifting side (the side corresponding with the hand that did not hold the DB) tended to generate a greater pull phase peak vertical ground reaction forces significantly faster (p = 0.001) than the lifting side (the side corresponding with the hand that held the DB) during the DBPS. In addition, the DBPS nonlifting side catch phase loading rate was approximately double that of the lifting side loading rate (p < 0.05). These results quantify symmetrical deviations in the movement patterns of the unilateral power snatch movement both during the concentric muscular contraction of load vertical displacement, and the loading implications of unilateral landing. This asymmetry supports the contention that unilateral variations of weightlifting movements may provide a different training stimulus to athletes.
Investigation into Interface Lifting Within FSW Lap Welds
K. S. Miller; C. R. Tolle; D. E. Clark; C. I. Nichol; T. R. McJunkin; H. B. Smartt
2008-06-01
Friction stir welding (FSW) is rapidly penetrating the welding market in many materials and applications, particularly in aluminum alloys for transportation applications. As this expansion outside the research laboratory continues, fitness for service issues will arise, and process control and NDE methods will become important determinants of continued growth. The present paper describes research into FSW weld nugget flaw detection within aluminum alloy lap welds. We present results for two types of FSW tool designs: a smooth pin tool and a threaded pin tool. We show that under certain process parameters (as monitored during welding with a rotating dynamometer that measures x, y, z, and torque forces) and tooling designs, FSW lap welds allow significant nonbonded interface lifting of the lap joint, while forming a metallurgical bond only within the pin region of the weld nugget. These lifted joints are often held very tightly together even though unbonded, and might be expected to pass cursory NDE while representing a substantial compromise in joint mechanical properties. The phenomenon is investigated here via radiographic and ultrasonic NDE techniques, with a copper foil marking insert (as described elsewhere) and by the tensile testing of joints. As one would expect, these results show that tool design and process parameters significantly affect plactic flow and this lifted interface. NDE and mechanical strength ramifications of this defect are discussed.
Automation of Workplace Lifting Hazard Assessment for Musculoskeletal Injury Prevention
2014-01-01
Objectives Existing methods for practically evaluating musculoskeletal exposures such as posture and repetition in workplace settings have limitations. We aimed to automate the estimation of parameters in the revised United States National Institute for Occupational Safety and Health (NIOSH) lifting equation, a standard manual observational tool used to evaluate back injury risk related to lifting in workplace settings, using depth camera (Microsoft Kinect) and skeleton algorithm technology. Methods A large dataset (approximately 22,000 frames, derived from six subjects) of simultaneous lifting and other motions recorded in a laboratory setting using the Kinect (Microsoft Corporation, Redmond, Washington, United States) and a standard optical motion capture system (Qualysis, Qualysis Motion Capture Systems, Qualysis AB, Sweden) was assembled. Error-correction regression models were developed to improve the accuracy of NIOSH lifting equation parameters estimated from the Kinect skeleton. Kinect-Qualysis errors were modelled using gradient boosted regression trees with a Huber loss function. Models were trained on data from all but one subject and tested on the excluded subject. Finally, models were tested on three lifting trials performed by subjects not involved in the generation of the model-building dataset. Results Error-correction appears to produce estimates for NIOSH lifting equation parameters that are more accurate than those derived from the Microsoft Kinect algorithm alone. Our error-correction models substantially decreased the variance of parameter errors. In general, the Kinect underestimated parameters, and modelling reduced this bias, particularly for more biased estimates. Use of the raw Kinect skeleton model tended to result in falsely high safe recommended weight limits of loads, whereas error-corrected models gave more conservative, protective estimates. Conclusions Our results suggest that it may be possible to produce reasonable estimates of
Lumbar spine loads during the lifting of extremely heavy weights.
Cholewicki, J; McGill, S M; Norman, R W
1991-10-01
The reaction moments at the knee, hip, and L4/L5 joints, and the compressive and shearing forces on L4/L5 are documented in powerlifters competing in a national powerlifting championship. Analyses were made of 13 female and 44 male competitors. The joint moments and forces were estimated from a linked segment model (WATBAK) that incorporated functional low back extensor musculature with a moment arm of 6 cm and a line action that was oriented 5 degrees posteriorly to the L4/L5 compression axis. This oblique orientation of the extensor muscles reduced the anterior shearing load on the vertebral motion unit. Average compressive loads on L4/L5 were estimated up to 17,192 N while the highest average L4/L5 and hip moments were 988 and 1047 N.m, respectively. The sumo deadlift style resulted in a 10% reduction in the joint moment and 8% reduction in the load shear force at the L4/L5 level when compared with the conventional lifting style. Formulation of linear regression equations to predict the load lifted using reaction joint moments yielded substantial unexplained variability, though significant relationships were found. This analysis suggested that there is large variability in the pattern of loading joints among national class powerlifters.
Carver, Charles S.; Scheier, Michael F.; Segerstrom, Suzanne C.
2010-01-01
Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from. PMID:20170998
NOAA-L satellite is lifted for mating
NASA Technical Reports Server (NTRS)
2000-01-01
Inside the B16-10 spacecraft processing hangar at Vandenberg Air Force Base, Calif., workers oversee the lifting and rotating of the National Oceanic and Atmospheric Administration (NOAA-L) satellite to allow for mating of the Apogee Kick Motor (AKM). NOAA-L is part of the Polar-Orbiting Operational Environmental Satellite (POES) program that provides atmospheric measurements of temperature, humidity, ozone and cloud images, tracking weather patterns that affect the global weather and climate. The launch of the NOAA-L satellite is scheduled no earlier than Sept. 12 aboard a Lockheed Martin Titan II rocket. Advanced wind turbine with lift cancelling aileron for shutdown
Coleman, Clint; Juengst, Theresa M.; Zuteck, Michael D.
1996-06-18
An advanced aileron configuration for wind turbine rotors featuring an independent, lift generating aileron connected to the rotor blade. The aileron has an airfoil profile which is inverted relative to the airfoil profile of the main section of the rotor blade. The inverted airfoil profile of the aileron allows the aileron to be used for strong positive control of the rotation of the rotor while deflected to angles within a control range of angles. The aileron functions as a separate, lift generating body when deflected to angles within a shutdown range of angles, generating lift with a component acting in the direction opposite the direction of rotation of the rotor. Thus, the aileron can be used to shut down rotation of the rotor. The profile of the aileron further allows the center of rotation to be located within the envelope of the aileron, at or near the centers of pressure and mass of the aileron. The location of the center of rotation optimizes aerodynamically and gyroscopically induced hinge moments and provides a fail safe configuration.
Adaptive directional lifting-based wavelet transform for image coding.
Ding, Wenpeng; Wu, Feng; Wu, Xiaolin; Li, Shipeng; Li, Houqiang
2007-02-01
We present a novel 2-D wavelet transform scheme of adaptive directional lifting (ADL) in image coding. Instead of alternately applying horizontal and vertical lifting, as in present practice, ADL performs lifting-based prediction in local windows in the direction of high pixel correlation. Hence, it adapts far better to the image orientation features in local windows. The ADL transform is achieved by existing 1-D wavelets and is seamlessly integrated into the global wavelet transform. The predicting and updating signals of ADL can be derived even at the fractional pixel precision level to achieve high directional resolution, while still maintaining perfect reconstruction. To enhance the ADL performance, a rate-distortion optimized directional segmentation scheme is also proposed to form and code a hierarchical image partition adapting to local features. Experimental results show that the proposed ADL-based image coding technique outperforms JPEG 2000 in both PSNR and visual quality, with the improvement up to 2.0 dB on images with rich orientation features.
Boyd, Nicola Jane; Wilson, Mark R
2015-10-14
The physical properties and phase transitions of thermotropic liquid crystals are highly sensitive to small changes in chemical structure. However, these changes are challenging to model, as both the phase diagram and mesophase properties obtained from fully atomistic simulations are strongly dependent on the force field model employed, and the current generation of chemical force fields has not proved accurate enough to provide reliable predictions of transition temperatures for many liquid crystals. This paper presents a strategy for improving the nematic clearing point, TNI, in atomistic simulations, by systematic optimization of the General Amber Force Field (GAFF) for key mesogenic fragments. We show that with careful optimization of the parameters describing a series of liquid crystal fragment molecules, it is possible to transfer these parameters to larger liquid crystal molecules and make accurate predictions for nematic mesophase formation. This new force field, GAFF-LCFF, is used to predict the nematic-isotropic clearing point to within 5 °C for the nematogen 1,3-benzenedicarboxylic acid,1,3-bis(4-butylphenyl)ester, an improvement of 60 °C over the standard GAFF force field.
Motor-Evoked Potentials in the Lower Back Are Modulated by Visual Perception of Lifted Weight
Behrendt, Frank; de Lussanet, Marc H. E.; Zentgraf, Karen; Zschorlich, Volker R.
2016-01-01
Facilitation of the primary motor cortex (M1) during the mere observation of an action is highly congruent with the observed action itself. This congruency comprises several features of the executed action such as somatotopy and temporal coding. Studies using reach-grasp-lift paradigms showed that the muscle-specific facilitation of the observer’s motor system reflects the degree of grip force exerted in an observed hand action. The weight judgment of a lifted object during action observation is an easy task which is the case for hand actions as well as for lifting boxes from the ground. Here we investigated whether the cortical representation in M1 for lumbar back muscles is modulated due to the observation of a whole-body lifting movement as it was shown for hand action. We used transcranial magnetic stimulation (TMS) to measure the corticospinal excitability of the m. erector spinae (ES) while subjects visually observed the recorded sequences of a person lifting boxes of different weights from the floor. Consistent with the results regarding hand action the present study reveals a differential modulation of corticospinal excitability despite the relatively small M1 representation of the back also for lifting actions that mainly involve the lower back musculature. PMID:27336751
Bogacz, Rafal; Brown, Eric; Moehlis, Jeff; Holmes, Philip; Cohen, Jonathan D
2006-10-01
In this article, the authors consider optimal decision making in two-alternative forced-choice (TAFC) tasks. They begin by analyzing 6 models of TAFC decision making and show that all but one can be reduced to the drift diffusion model, implementing the statistically optimal algorithm (most accurate for a given speed or fastest for a given accuracy). They prove further that there is always an optimal trade-off between speed and accuracy that maximizes various reward functions, including reward rate (percentage of correct responses per unit time), as well as several other objective functions, including ones weighted for accuracy. They use these findings to address empirical data and make novel predictions about performance under optimality.
Salvage and Recovery Data Book -- Static Lift Forces.
1979-06-01
les eeimts was av i a t i o n gasoline . ‘Fhme e f f e c t i v e h u o v a u m e of a sy s t e m of t h is type is 10 to 20 pounds per cubic foot...a i v , , ’C,’nc r a t i oul mime ch anu ~m ims iii a laboratory status. Hydrog en is time idea l b u o v aulC ,’v u~as hce:u u \\ c it lm:i ~ I...all tIme rea ct ion products go u mi to I hm e pontoon and f u ll t Ime ava i lab le space. In addit ion to Ilk’ n il r ogeu m ami d h ydrogen. I h
Lift-Drag Ratios for an Arrow Wing With Bodies at Mach Number 3
NASA Technical Reports Server (NTRS)
Jorgensen, Leland H.
1959-01-01
Force and moment characteristics, including lift-drag ratios, have been measured for bodies of circular and elliptic cross section alone and combined with a warped arrow wing. The test Mach number was 2.94, and the Reynolds number was 3.5 x 10(exp 6) (based on wing mean aerodynamic chord). The experimental results show that for equal volume the use of an elliptical body can result in a noticeably higher maximum lift-drag ratio than that obtained through use of a circular body. Methods for estimating the aerodynamic characteristics have been assessed by comparing computed with experimental results. Because of good agreement of the predictions with experiment, maximum lift-drag ratios have been computed for the arrow wing in combination with bodies of various sizes. These calculations have shown that, for an efficient wing-body combination, little loss in maximum lift-drag ratio results from considerable extension of afterbody length. For example, for a wing-body configuration having a maximum lift-drag ratio of about 7.1, a loss in maximum lift-drag ratio of less than 0.2 results from a 40-percent increase in body volume by extension of afterbody length. It also appears that with body length fixed, maximum lift-drag ratio decreases almost linearly with increase in body diameter. For a wing- body combination employing a body of circular cross section, a decrease in maximum lift-drag ratio from about 9.1 for zero body diameter to about 4.6 for a body diameter of 13.5 percent of the body length was computed.
Kinematics and kinetics of the dead lift in adolescent power lifters.
Brown, E W; Abani, K
1985-10-01
This study documented characteristics of the dead lift of teenage lifters. Films of 10 "skilled" and 11 "unskilled" contestants in a Michigan Teenage Powerlifting Championship provided data for analysis. Equations of motion, force, and moments were developed for a multisegment model of the lifters' movement in the sagittal plane and applied to the film data. Analysis was limited to 1) body segment orientations, 2) vertical bar accelerations, 3) vertical joint reaction forces, 4) segmental angular accelerations, 5) horizontal moment arms of the bar to selected joints, and 6) intersegmental resultant moments. Significant differences (P less than 0.05) in body segment orientation indicated a more upright posture at lift-off in the skilled group. Maximum vertical bar acceleration and angular acceleration of the trunk tended to occur near lift-off in the skilled lifters. The unskilled subjects demonstrated greater variability and magnitude in linear and angular acceleration parameters. In all lifters, maximum vertical force was experienced at the ankle joint. Within each subject, the hip joint experienced the greatest torque because of the relatively large horizontal moment arm of the bar (dominant mass in the system) to this joint. In all subjects, the magnitude of the mass lifted, and not the technique, was the primary determinant in the intersegmental resultant moment acting at the hip and the vertical force experienced at the ankle, knee, and hip joints.
Two-axis hydraulic joint for high speed, heavy lift robotic operations
Vaughn, M.R.; Robinett, R.D.; Phelan, J.R.; VanZuiden, D.M.
1994-04-01
A hydraulically driven universal joint was developed for a heavy lift, high speed nuclear waste remediation application. Each axis is driven by a simple hydraulic cylinder controlled by a jet pipe servovalve. Servovalve behavior is controlled by a force feedback control system, which damps the hydraulic resonance. A prototype single joint robot was built and tested. A two joint robot is under construction.
Lift and thrust generation by a butterfly-like 3D flapping wing model
NASA Astrophysics Data System (ADS)
Suzuki, Kosuke; Inamuro, Takaji
2013-11-01
The flapping flight of tiny insects such as a butterfly is of fundamental interest not only in biology itself but also in its practical use for the development of micro air vehicles. It is known that a butterfly flaps downward for generating lift force and backward for generating thrust force. In this study, we consider a simple butterfly-like 3D flapping wing model whose body is a thin rod, wings are rigid and rectangular, and wing motion is simplified. We investigate the lift and thrust generation by the butterfly-like flapping wing model by using the immersed boundary-lattice Boltzmann method. Firstly, we compute the lift and thrust forces when the body of the model is fixed for Reynolds numbers in the range of 50 - 1000. In addition, we evaluate the supportable mass for each Reynolds number by using the computed lift force. Secondly, we simulate the free flight where the body can move translationally but cannot rotate. As results, we find that the evaluated supportable mass can be supported even in the free flight, and the wing model with the mass and the Reynolds number of a fruit fly can go upward against the gravity. Finally, we simulate the effect of the rotation of the body. As results, we find that the body has a large pitching motion and consequently gets off-balance.
ERIC Educational Resources Information Center
Ashton, T. Edwin J.; Singh, Mohan
1975-01-01
This study determined the maximal mean values for concentric and eccentric back-lift strength as well as isometric, and examined and compared the relationships between the mean peak voltage of the erectores spinae muscle(s) and maximal force exerted for the three types of muscle contractions. (RC)
A continuous-vorticity panel method for lifting surfaces
NASA Technical Reports Server (NTRS)
Yen, A.; Mook, D. T.; Nayfeh, A. H.
1981-01-01
A continuous-vorticity panel method is developed and utilized to predict the steady aerodynamic loads on lifting surfaces having sharp-edge separation. Triangular panels with linearly varying vorticity are used. The velocity field generated by an individual element is obtained in closed form. An optimization scheme is constructed for finding the vorticity at the nodes of the elements. The method is not restricted by aspect ratios, angles of attack, planforms, or camber. Rectangular and delta wings are presented as numerical examples. The numerical results are in good agreement with the experimental data for incompressible flows.
Scheduling Algorithm for Improving Lift (SAIL): Phase 1, documentation
Hawthorne, J.E.; MeLaren, R.A.
1988-07-01
The Military Sealift Command, a component of the United States Transportational Command, is responsible for the Sealift of military personnel and material during a crisis. Conceptual plans for these complex moves, called ''deliberate plans,'' are continually being prepared. A computer-based scheduling system, the Sealift Strategic Analysis Subsystem (SEASTRAT), is under development for assisting on the production of these plans. The ship scheduling portion of this system, the Scheduling Algorithm foe Improving Lift (SAIL), combines linear optimization and heuristic methods to determine ship routes and cargo loadings which honor a variety of complex operational constraints. 13 refs., 2 figs., 2 tabs.
Three-dimensional flow and lift characteristics of a hovering ruby-throated hummingbird.
Song, Jialei; Luo, Haoxiang; Hedrick, Tyson L
2014-09-06
A three-dimensional computational fluid dynamics simulation is performed for a ruby-throated hummingbird (Archilochus colubris) in hovering flight. Realistic wing kinematics are adopted in the numerical model by reconstructing the wing motion from high-speed imaging data of the bird. Lift history and the three-dimensional flow pattern around the wing in full stroke cycles are captured in the simulation. Significant asymmetry is observed for lift production within a stroke cycle. In particular, the downstroke generates about 2.5 times as much vertical force as the upstroke, a result that confirms the estimate based on the measurement of the circulation in a previous experimental study. Associated with lift production is the similar power imbalance between the two half strokes. Further analysis shows that in addition to the angle of attack, wing velocity and surface area, drag-based force and wing-wake interaction also contribute significantly to the lift asymmetry. Though the wing-wake interaction could be beneficial for lift enhancement, the isolated stroke simulation shows that this benefit is buried by other opposing effects, e.g. presence of downwash. The leading-edge vortex is stable during the downstroke but may shed during the upstroke. Finally, the full-body simulation result shows that the effects of wing-wing interaction and wing-body interaction are small.
Heavy Lift & Propulsion Technology (HL&PT)
Cris Guidi delivers a presentation from the Heavy Lift & Propulsion Technology (HL&PT) study team on May 25, 2010, at the NASA Exploration Enterprise Workshop held in Galveston, TX. The purpose of ...
Denny, M W
2000-09-01
Limpets are commonly found on wave-swept rocky shores, where they may be subjected to water velocities in excess of 20 m s(-1). These extreme flows can impose large forces (lift and drag), challenging the animal's ability to adhere to the substratum. It is commonly thought that the conical shape of limpet shells has evolved in part to reduce these hydrodynamic forces while providing a large aperture for adhesion. This study documents how lift and drag actually vary with the shape of limpet-like models and uses these data to explore the potential of hydrodynamic forces to serve as a selective factor in the evolution of limpet shell morphology. At a low ratio of shell height to shell radius, lift is the dominant force, while at high ratios of height to radius drag is dominant. The risk of dislodgment is minimized when the ratio of height to radius is 1.06 and the apex is in the center of the shell. Real limpets are seldom optimally shaped, however, with a typical height-to-radius ratio of 0.68 and an apex well anterior of the shell's center. The disparity between the actual and the hydrodynamically optimal shape of shells may be due to the high tenacity of limpets' adhesive system. Most limpets adhere to the substratum so strongly that they are unlikely to be dislodged by lift or drag regardless of the shape of their shell. The evolution of a tenacious adhesion system (perhaps in response to predation) has thus preempted selection for a hydrodynamically optimal shell, allowing the shell to respond to alternative selective factors.
Wavelet Kernels on a DSP: A Comparison between Lifting and Filter Banks for Image Coding
NASA Astrophysics Data System (ADS)
Gnavi, Stefano; Penna, Barbara; Grangetto, Marco; Magli, Enrico; Olmo, Gabriella
2002-12-01
We develop wavelet engines on a digital signal processors (DSP) platform, the target application being image and intraframe video compression by means of the forthcoming JPEG2000 and Motion-JPEG2000 standards. We describe two implementations, based on the lifting scheme and the filter bank scheme, respectively, and we present experimental results on code profiling. In particular, we address the following problems: (1) evaluating the execution speed of a wavelet engine on a modern DSP; (2) comparing the actual execution speed of the lifting scheme and the filter bank scheme with the theoretical results; (3) using the on-board direct memory access (DMA) to possibly optimize the execution speed. The results allow to assess the performance of a modern DSP in the image coding task, as well as to compare the lifting and filter bank performance in a realistic application scenario. Finally, guidelines for optimizing the code efficiency are provided by investigating the possible use of the on-board DMA.
Integrated lift/drag controller for aircraft
NASA Technical Reports Server (NTRS)
Olcott, J. W.; Seckel, E.; Ellis, D. R. (Inventor)
1974-01-01
A system for altering the lift/drag characteristics of powered aircraft to provide a safe means of glide path control includes a control device integrated for coordination action with the aircraft throttle. Such lift/drag alteration devices as spoilers, dive brakes, and the like are actuated by manual operation of a single lever coupled with the throttle for integrating, blending or coordinating power control. Improper operation of the controller is inhibited by safety mechanisms.
Liftings and stresses for planar periodic frameworks
Borcea, Ciprian; Streinu, Ileana
2015-01-01
We formulate and prove a periodic analog of Maxwell’s theorem relating stressed planar frameworks and their liftings to polyhedral surfaces with spherical topology. We use our lifting theorem to prove deformation and rigidity-theoretic properties for planar periodic pseudo-triangulations, generalizing features known for their finite counterparts. These properties are then applied to questions originating in mathematical crystallography and materials science, concerning planar periodic auxetic structures and ultrarigid periodic frameworks. PMID:26973370
Liftings and stresses for planar periodic frameworks.
Borcea, Ciprian; Streinu, Ileana
2015-06-01
We formulate and prove a periodic analog of Maxwell's theorem relating stressed planar frameworks and their liftings to polyhedral surfaces with spherical topology. We use our lifting theorem to prove deformation and rigidity-theoretic properties for planar periodic pseudo-triangulations, generalizing features known for their finite counterparts. These properties are then applied to questions originating in mathematical crystallography and materials science, concerning planar periodic auxetic structures and ultrarigid periodic frameworks.
The effect of asymmetry on psychophysical lifting capacity for three lifting types.
Han, B; Stobbe, T J; Hobbs, G R
2005-03-15
The effect of asymmetry on a person's lifting capacity was investigated using the psychophysical approach. Ten male college students lifted a box from pallet height (15 cm) to conveyor height (75 cm) at a frequency of one and five lifts/min. Three types of asymmetric lifting tasks (step-turn, middle twist and twist) were studied using 90 and 180 degrees task angles. Lifting capacity reductions for middle twist and twist at a 90 degrees asymmetric angle were about one-half of the 30% reduction that would be calculated by the 1991 National Institute for Occupational Safety & Health (NIOSH) lifting equation. The lifting capacity reduction for step-turn at 180 degrees was 14.9%, although that reduction cannot be calculated in the NIOSH equation. The middle twist lifting capacity was greatest among the three types at a 90 degrees task angle. The reductions for the middle twist and step-turn were not proportional to the task angle. This is contrary to the proportional reduction in the NIOSH lifting equation. Heart rate did not increase with an increase in task angle. Based on the results of this research, a different approach to assigning the asymmetric multiplier is proposed. This approach includes a task angle (as opposed to asymmetric angle) of up to 180 degrees.
Riley, A.E.; Craig, T.D.; Sharma, N.K.; Billinger, S.A.; Wilson, S.E.
2015-01-01
As torso flexion and repetitive lifting are known risk factors for low back pain and injury, it is important to investigate lifting techniques that might reduce injury during repetitive lifting. By normalizing lumbar posture to a subject’s range of motion (ROM), as a function of torso flexion, this research examined when subjects approached their range of motion limits during dynamic lifting tasks. For this study, it was hypothesized that experienced lifters would maintain a more neutral lumbar angle relative to their range of motion, while novice lifters would approach the limits of their lumbar ROM during the extension phase of a straight-leg lift. The results show a statistically significant difference in lifting patterns for these two groups supporting this hypothesis. The novice group maintained a much more kyphotic lumbar angle for both the flexion (74% of the lumbar angle ROM) and extension phases (86% of the lumbar angle ROM) of the lifting cycle, while the experienced group retained a more neutral curvature throughout the entire lifting cycle (37% of lumbar angle ROM in flexion and 48% of lumbar angle ROM in extension). By approaching the limits of their range of motion, the novice lifters could be at greater risk of injury by placing greater loads on the supporting soft tissues of the spine. Future research should examine whether training subjects to assume more neutral postures during lifting could indeed lower injury risks. PMID:26077846
Experiments to investigate lift production mechanisms on pitching flat plates
NASA Astrophysics Data System (ADS)
Stevens, P. R. R. J.; Babinsky, H.
2017-01-01
Pitching flat plates are a useful simplification of flapping wings, and their study can provide useful insights into unsteady force generation. Non-circulatory and circulatory lift producing mechanisms for low Reynolds number pitching flat plates are investigated. A series of experiments are designed to measure forces and study the unsteady flowfield development. Two pitch axis positions are investigated, namely a leading edge and a mid-chord pitch axis. A novel PIV approach using twin laser lightsheets is shown to be effective at acquiring full field of view velocity data when an opaque wing model is used. Leading-edge vortex (LEV) circulations are extracted from velocity field data, using a Lamb-Oseen vortex fitting algorithm. LEV and trailing-edge vortex positions are also extracted. It is shown that the circulation of the LEV, as determined from PIV data, approximately matches the general trend of an unmodified Wagner function for a leading edge pitch axis and a modified Wagner function for a mid-chord pitch axis. Comparison of experimentally measured lift correlates well with the prediction of a reduced-order model for a LE pitch axis.
Martinez-Tossas, Luis A.; Churchfield, Matthew J.; Meneveau, Charles
2016-10-03
When representing the blade aerodynamics with rotating actuator lines, the computed forces have to be projected back to the CFD flow field as a volumetric body force. That has been done in the past with a geometrically simple uniform three-dimensional Gaussian at each point along the blade. Here, we argue that the body force can be shaped in a way that better predicts the blade local flow field, the blade load distribution, and the formation of the tip/root vortices. In previous work, we have determined the optimal scales of circular and elliptical Gaussian kernels that best reproduce the local flow field in two-dimensions. Lastly, in this work we extend the analysis and applications by considering the full three-dimensional blade to test our hypothesis in a highly resolved Large Eddy Simulation.
NASA Astrophysics Data System (ADS)
Martínez-Tossas, Luis A.; Churchfield, Matthew J.; Meneveau, Charles
2016-09-01
When representing the blade aerodynamics with rotating actuator lines, the computed forces have to be projected back to the CFD flow field as a volumetric body force. That has been done in the past with a geometrically simple uniform three-dimensional Gaussian at each point along the blade. We argue that the body force can be shaped in a way that better predicts the blade local flow field, the blade load distribution, and the formation of the tip/root vortices. In previous work, we have determined the optimal scales of circular and elliptical Gaussian kernels that best reproduce the local flow field in two-dimensions. In this work we extend the analysis and applications by considering the full three-dimensional blade to test our hypothesis in a highly resolved Large Eddy Simulation.
Martinez-Tossas, Luis A.; Churchfield, Matthew J.; Meneveau, Charles
2016-10-03
When representing the blade aerodynamics with rotating actuator lines, the computed forces have to be projected back to the CFD flow field as a volumetric body force. That has been done in the past with a geometrically simple uniform three-dimensional Gaussian at each point along the blade. Here, we argue that the body force can be shaped in a way that better predicts the blade local flow field, the blade load distribution, and the formation of the tip/root vortices. In previous work, we have determined the optimal scales of circular and elliptical Gaussian kernels that best reproduce the local flowmore » field in two-dimensions. Lastly, in this work we extend the analysis and applications by considering the full three-dimensional blade to test our hypothesis in a highly resolved Large Eddy Simulation.« less
Effects of a Belt on Intra-Abdominal Pressure during Weight Lifting
1989-01-01
effective for increasing lAP, reducing to reduce potentially injurious compressive forces on spinal discs during lifting. To investigate the effects of a...earlier with than without the belt. When the belt was worn, IAP rose significantly earlier than did GRF. Both with and possibly reducing spinal disc ... spinal disc com- plates at either end of the bar rested on surfaces adjacent pressive forces by up to 40% (6,10,12,14). to and level with the top of the
49 CFR 178.812 - Top lift test.
Code of Federal Regulations, 2010 CFR
2010-10-01
.... (b) Special preparation for the top lift test. (1) Metal, rigid plastic, and composite IBC design... 49 Transportation 2 2010-10-01 2010-10-01 false Top lift test. 178.812 Section 178.812... Testing of IBCs § 178.812 Top lift test. (a) General. The top lift test must be conducted for...
49 CFR 178.975 - Top lift test.
Code of Federal Regulations, 2010 CFR
2010-10-01
... Large Packagings, from the side. (b) Special preparation for the top lift test. (1) Metal and rigid... 49 Transportation 2 2010-10-01 2010-10-01 false Top lift test. 178.975 Section 178.975... Testing of Large Packagings § 178.975 Top lift test. (a) General. The top lift test must be conducted...
49 CFR 178.812 - Top lift test.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 3 2011-10-01 2011-10-01 false Top lift test. 178.812 Section 178.812... Top lift test. (a) General. The top lift test must be conducted for the qualification of all IBC design types designed to be lifted from the top or, for flexible IBCs, from the side. (b)...
49 CFR 178.975 - Top lift test.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 3 2011-10-01 2011-10-01 false Top lift test. 178.975 Section 178.975... Packagings § 178.975 Top lift test. (a) General. The top lift test must be conducted for the qualification of all of Large Packagings design types to be lifted from the top or, for flexible Large Packagings,...
49 CFR 178.812 - Top lift test.
Code of Federal Regulations, 2013 CFR
2013-10-01
... preparation for the top lift test. (1) Metal, rigid plastic, and composite IBC design types must be loaded to... 49 Transportation 3 2013-10-01 2013-10-01 false Top lift test. 178.812 Section 178.812... Top lift test. (a) General. The top lift test must be conducted for the qualification of all...
49 CFR 178.811 - Bottom lift test.
Code of Federal Regulations, 2011 CFR
2011-10-01
... Bottom lift test. (a) General. The bottom lift test must be conducted for the qualification of all IBC.... (c) Test method. All IBC design types must be raised and lowered twice by a lift truck with the forks... 49 Transportation 3 2011-10-01 2011-10-01 false Bottom lift test. 178.811 Section...
49 CFR 178.975 - Top lift test.
Code of Federal Regulations, 2013 CFR
2013-10-01
... Packagings § 178.975 Top lift test. (a) General. The top lift test must be conducted for the qualification of... distributed. (c) Test method. (1) A Large Packaging must be lifted in the manner for which it is designed... 49 Transportation 3 2013-10-01 2013-10-01 false Top lift test. 178.975 Section...
49 CFR 178.811 - Bottom lift test.
Code of Federal Regulations, 2010 CFR
2010-10-01
... evenly distributed. (c) Test method. All IBC design types must be raised and lowered twice by a lift... 49 Transportation 2 2010-10-01 2010-10-01 false Bottom lift test. 178.811 Section 178.811... Testing of IBCs § 178.811 Bottom lift test. (a) General. The bottom lift test must be conducted for...
49 CFR 178.811 - Bottom lift test.
Code of Federal Regulations, 2013 CFR
2013-10-01
... Bottom lift test. (a) General. The bottom lift test must be conducted for the qualification of all IBC.... (c) Test method. All IBC design types must be raised and lowered twice by a lift truck with the forks... 49 Transportation 3 2013-10-01 2013-10-01 false Bottom lift test. 178.811 Section...
The Selection of a Van Lift or a Scooter.
ERIC Educational Resources Information Center
Stevens, John H.
1990-01-01
This newsletter issue describes 3-wheeled scooters and van lifts that can assist a person with a disability to drive independently or have access to transportation. The section on van lifts compares hydraulic lifts and electric lifts, lists manufacturers, and offers an "assessment quiz" outlining factors to consider in selecting a van…
Li, Yong; Randerath, Jennifer; Bauer, Hans; Marquardt, Christian; Goldenberg, Georg; Hermsdörfer, Joachim
2009-01-03
When we manipulate familiar objects in our daily life, our grip force anticipates the physical demands right from the moment of contact with the object, indicating the existence of a memory for relevant object properties. This study explores the formation and consolidation of the memory processes that associate either familiar (size) or arbitrary object features (color) with object weight. In the general task, participants repetitively lifted two differently weighted objects (580 and 280 g) in a pseudo-random order. Forty young healthy adults participated in this study and were randomly distributed into four groups: Color Cue Single task (CCS, blue and red, 9.8(3)cm(3)), Color Cue Dual task (CCD), No Cue (NC) and Size Cue (SC, 9.8(3) and 6(3)cm(3)) group. All groups performed a repetitive precision grasp-lift task and were retested with the same protocol after a 5-min pause. The CCD group was also required to simultaneously perform a memory task during each lift of differently weighted objects coded by color. The results show that groups lifting objects with arbitrary or familiar features successfully formed the association between object weight and manipulated object features and incorporated this into grip force programming, as observed in the different scaling of grip force and grip force rate for different object weights. An arbitrary feature, i.e., color, can be sufficiently associated with object weight, however with less strength than the familiar feature of size. The simultaneous memory task impaired anticipatory force scaling during repetitive object lifting but did not jeopardize the learning process and the consolidation of the associative memory.
NASA Technical Reports Server (NTRS)
Roskam, J.; Williams, M.
1981-01-01
All calculations were done in the stability axes system. The winglets used were constructed of modified GA(w)-2 airfoils. Aerodynamic characteristics discussed include: angle of attack; lift-curve slope; side force; yawing moments; rolling moments.
Lifting teams in health care facilities: a literature review.
Haiduven, Donna
2003-05-01
1. Manual lifting and transfer activities are job tasks frequently associated with back injuries in nursing personnel. One approach with potential to decrease these injuries is the lifting team. 2. In program evaluations completed to date, there have been numerous benefits and several limitations attributed to use of lifting teams in health care facilities. 3. Benefits of lifting teams include reductions in lost time workdays, restricted workdays, workers' compensation claims, and injuries to lifting team members; satisfaction of patients, staff, and lifting team members; and capacity of the lifting team to absorb the majority of high risk lifts and transfers on shifts in which they operate. 4. Lifting teams may not be appropriate for all settings, require infrastructure and lifting team equipment to support their use, and require careful consideration related to staffing. However, when their use is appropriate, efforts to overcome their limitations can be accomplished with careful evaluation of outcome measures and indicators.
Gutierrez, Eric; Quinn, Daniel B; Chin, Diana D; Lentink, David
2016-12-06
There are three common methods for calculating the lift generated by a flying animal based on the measured airflow in the wake. However, these methods might not be accurate according to computational and robot-based studies of flapping wings. Here we test this hypothesis for the first time for a slowly flying Pacific parrotlet in still air using stereo particle image velocimetry recorded at 1000 Hz. The bird was trained to fly between two perches through a laser sheet wearing laser safety goggles. We found that the wingtip vortices generated during mid-downstroke advected down and broke up quickly, contradicting the frozen turbulence hypothesis typically assumed in animal flight experiments. The quasi-steady lift at mid-downstroke was estimated based on the velocity field by applying the widely used Kutta-Joukowski theorem, vortex ring model, and actuator disk model. The calculated lift was found to be sensitive to the applied model and its different parameters, including vortex span and distance between the bird and laser sheet-rendering these three accepted ways of calculating weight support inconsistent. The three models predict different aerodynamic force values mid-downstroke compared to independent direct measurements with an aerodynamic force platform that we had available for the same species flying over a similar distance. Whereas the lift predictions of the Kutta-Joukowski theorem and the vortex ring model stayed relatively constant despite vortex breakdown, their values were too low. In contrast, the actuator disk model predicted lift reasonably accurately before vortex breakdown, but predicted almost no lift during and after vortex breakdown. Some of these limitations might be better understood, and partially reconciled, if future animal flight studies report lift calculations based on all three quasi-steady lift models instead. This would also enable much needed meta studies of animal flight to derive bioinspired design principles for quasi-steady lift
NASA Technical Reports Server (NTRS)
Lehman, L. L.
1981-01-01
A computational technique has been developed for performing preliminary design aeroelastic analyses of large aspect ratio lifting surfaces. This technique, applicable to both fixed and rotating wing configurations, is based upon a formulation of the structural equilibrium equations in terms of a hybrid state vector containing generalized force and displacement variables. An integrating matrix is employed to solve these equations for divergence and flutter eigenvalues and steady aeroelastic deformation. Results are presented for simple examples which verify the technique and demonstrate how it can be applied to analyze lifting surfaces, including those constructed from composite materials.
Omelyan, Igor E-mail: omelyan@icmp.lviv.ua; Kovalenko, Andriy
2013-12-28
We develop efficient handling of solvation forces in the multiscale method of multiple time step molecular dynamics (MTS-MD) of a biomolecule steered by the solvation free energy (effective solvation forces) obtained from the 3D-RISM-KH molecular theory of solvation (three-dimensional reference interaction site model complemented with the Kovalenko-Hirata closure approximation). To reduce the computational expenses, we calculate the effective solvation forces acting on the biomolecule by using advanced solvation force extrapolation (ASFE) at inner time steps while converging the 3D-RISM-KH integral equations only at large outer time steps. The idea of ASFE consists in developing a discrete non-Eckart rotational transformation of atomic coordinates that minimizes the distances between the atomic positions of the biomolecule at different time moments. The effective solvation forces for the biomolecule in a current conformation at an inner time step are then extrapolated in the transformed subspace of those at outer time steps by using a modified least square fit approach applied to a relatively small number of the best force-coordinate pairs. The latter are selected from an extended set collecting the effective solvation forces obtained from 3D-RISM-KH at outer time steps over a broad time interval. The MTS-MD integration with effective solvation forces obtained by converging 3D-RISM-KH at outer time steps and applying ASFE at inner time steps is stabilized by employing the optimized isokinetic Nosé-Hoover chain (OIN) ensemble. Compared to the previous extrapolation schemes used in combination with the Langevin thermostat, the ASFE approach substantially improves the accuracy of evaluation of effective solvation forces and in combination with the OIN thermostat enables a dramatic increase of outer time steps. We demonstrate on a fully flexible model of alanine dipeptide in aqueous solution that the MTS-MD/OIN/ASFE/3D-RISM-KH multiscale method of molecular dynamics
NASA Astrophysics Data System (ADS)
Omelyan, Igor; Kovalenko, Andriy
2013-12-01
We develop efficient handling of solvation forces in the multiscale method of multiple time step molecular dynamics (MTS-MD) of a biomolecule steered by the solvation free energy (effective solvation forces) obtained from the 3D-RISM-KH molecular theory of solvation (three-dimensional reference interaction site model complemented with the Kovalenko-Hirata closure approximation). To reduce the computational expenses, we calculate the effective solvation forces acting on the biomolecule by using advanced solvation force extrapolation (ASFE) at inner time steps while converging the 3D-RISM-KH integral equations only at large outer time steps. The idea of ASFE consists in developing a discrete non-Eckart rotational transformation of atomic coordinates that minimizes the distances between the atomic positions of the biomolecule at different time moments. The effective solvation forces for the biomolecule in a current conformation at an inner time step are then extrapolated in the transformed subspace of those at outer time steps by using a modified least square fit approach applied to a relatively small number of the best force-coordinate pairs. The latter are selected from an extended set collecting the effective solvation forces obtained from 3D-RISM-KH at outer time steps over a broad time interval. The MTS-MD integration with effective solvation forces obtained by converging 3D-RISM-KH at outer time steps and applying ASFE at inner time steps is stabilized by employing the optimized isokinetic Nosé-Hoover chain (OIN) ensemble. Compared to the previous extrapolation schemes used in combination with the Langevin thermostat, the ASFE approach substantially improves the accuracy of evaluation of effective solvation forces and in combination with the OIN thermostat enables a dramatic increase of outer time steps. We demonstrate on a fully flexible model of alanine dipeptide in aqueous solution that the MTS-MD/OIN/ASFE/3D-RISM-KH multiscale method of molecular dynamics
Influence of vision and posture on grip-lift task parameters in healthy adults.
Dispa, Delphine; Tourbach, Catherine; Thonnard, Jean-Louis; Lejeune, Thierry
2014-12-01
The grip-lift task enables a quantitative assessment of grasping ability. Patients are regularly assessed in a supine position, which offers a different view of the grasped object from that in the sitting position. To our knowledge, no data are currently available on the influence of posture and vision on grip-lift task parameters. We therefore aimed to determine the effects of posture and vision on these parameters. Twenty-six healthy right-handed adults performed grip-lift tasks with a manipulandum that measured different temporal and dynamic parameters in four conditions: sitting eyes open, sitting blindfolded, lying down eyes open and lying down blindfolded. A repeated-measures analysis of variance with two factors (vision and position) showed that the absence of vision affected all the parameters measured. The lying down position increased the time between the first contact with the object and the modification of the vertical force as well as the delay between the first increase of the horizontal force and the increase of the vertical force. In addition, there was a lower adaption of the horizontal force, required to squeeze the object, to the vertical force. Finally, the interaction of position and vision was associated with significant differences in the delay between the contact of each digit with the object, the maximum horizontal force and the ratio between the horizontal and vertical force during a static holding period. Both position and vision appear to affect the grip-lift task. Consequently, sequential assessments should be performed in the same condition to obtain reliable data.
2007-11-02
The United States Air Force has recently defined three objectives in developing strategies regarding the management of municipal solid waste at the...insight concerning the selection and implementation of a municipal solid waste management policy.
1997-03-03
The United States Air Force has recently defined three objectives in developing strategies regarding the management of municipal solid waste at the...insight concerning the selection and implementation of a municipal solid waste management policy.
Evaluation of an optimal aerocapture guidance algorithm for human Mars missions
NASA Astrophysics Data System (ADS)
Webb, Kyle
Aeroassist guidance is concerned with providing steering commands to a vehicle flying through a planetary atmosphere in the form of an aerodynamic roll angle, or bank angle, which results in appropriate direction of the aerodynamic lift force so that the vehicle will safely and accurately reach its designated final condition. Aerocapture guidance is a particular subcategory of aeroassist guidance that involves atmospheric entry from an interplanetary transfer orbit, a guided flight through the atmosphere, and a final condition consisting of a post-atmospheric exit target orbit around the planet. Using aerocapture guidance to establish this target orbit can provide significant propellant mass savings when compared to traditional propulsive maneuvers. No current aerocapture guidance algorithms can ensure truly optimal performance in minimizing post-exit orbit insertion ?V requirements. This thesis investigates the development of a two-phase optimal aerocapture guidance algorithm. This closed-loop guidance algorithm uses a mathematically optimal bang-bang bank angle profile structure, in which a vehicle first flies with the lift vector pointed straight up, and then flies full lift-down until atmospheric exit. The optimal trajectory is found by determining the switching time between full lift-up and full lift-down flight. Results from testing the algorithm in a high-fidelity NASA simulation environment are presented and compared with results from existing state-of-the-art aerocapture guidance algorithms. These results show that the developed algorithm provides the robustness and adaptability of a numerical predictor-corrector guidance algorithm while demonstrating a significant reduction in ?V requirements compared to other existing algorithms.
NASA Technical Reports Server (NTRS)
Carlson, H. W.; Walkley, K. B.
1982-01-01
Numerical methods incorporated into a computer program to provide estimates of the subsonic aerodynamic performance of twisted and cambered wings of arbitrary planform with attainable thrust and vortex lift considerations are described. The computational system is based on a linearized theory lifting surface solution which provides a spanwise distribution of theoretical leading edge thrust in addition to the surface distribution of perturbation velocities. The approach used relies on a solution by iteration. The method also features a superposition of independent solutions for a cambered and twisted wing and a flat wing of the same planform to provide, at little additional expense, results for a large number of angles of attack or lift coefficients. A previously developed method is employed to assess the portion of the theoretical thrust actually attainable and the portion that is felt as a vortex normal force.
The effect of a lower extremity kinematic constraint on lifting biomechanics.
Jin, Sangeun; Mirka, Gary A
2011-11-01
Leaning against a stationary barrier during manual materials handling tasks is observed in many industrial environments, but the effects of this kinematic constraint on low back mechanics are unknown. Thirteen participants performed two-handed lifting tasks using both a leaning posture and no leaning posture while trunk kinematics, muscle activity and ground reaction force were monitored. Results revealed that lifting with the leaning posture required significantly less activity in erector spinae (26% vs. 36% MVC) and latissimus dorsi (8% vs. 14% MVC), and less passive tissue moment compared with the no leaning posture. Peak sagittal accelerations were lower when leaning, but the leaning posture also had significantly higher slip potential as measured by required coefficient of friction (0.05 vs. 0.36). The results suggested that the leaning lifting strategy provides reduced low back stress, but does so at the cost of increased slip potential.
Design of a portable powered seat lift
NASA Technical Reports Server (NTRS)
Weddendorf, Bruce
1993-01-01
People suffering from degenerative hip or knee joints find sitting and rising from a seated position very difficult. These people can rely on large stationary chairs at home, but must ask others for assistance when rising from any other chair. An orthopedic surgeon identified to the MSFC Technology Utilization Office the need for development of a portable device that could perform a similar function to the stationary lift chairs. The MSFC Structural Development Branch answered the Technology Utilization Office's request for design of a portable powered seat lift. The device is a seat cushion that opens under power, lifting the user to near-standing positions. The largest challenge was developing a mechanism to provide a stable lift over the large range of motion needed, and fold flat enough to be comfortable to sit on. CAD 3-D modeling was used to generate complete drawings for the prototype, and a full-scale working model of the Seat lift was made based on the drawings. The working model is of low strength, but proves the function of the mechanism and the concept.
Lifting device for nuclear power plants
Krieger, F.
1984-07-17
A lifting device for lifting and transporting nuclear fuel elements. This device comprises a mast-like support on the lower end of which automatically operated and locked gripping pawls are provided. The support has a considerable height and may be referred to as lifting mast. The gripping pawls and their operating mechanism are referred to as gripping-head. The gripping-head and the lifting mast are telescopically movable relative to each other. To this end guide rods and compression springs are interposed between the lower end of the lifting mast and the gripping-head. The gripping-head comprises two concentric annular members which are relatively movable or rotatable about their common geometrical axis. One of the annular members supports the gripping pawls are T-shaped. One of their transverse ends is adapted to engage the fuel rods, and the other of their transverse ends is adapted to engage curved grooves in the other annular member. The rotary motion of one annular member relative to the other gripping pawls. In their limit positions the two annular members are blocked by a safety lever engaging slits or slots.
Noise impact of advanced high lift systems
NASA Technical Reports Server (NTRS)
Elmer, Kevin R.; Joshi, Mahendra C.
1995-01-01
The impact of advanced high lift systems on aircraft size, performance, direct operating cost and noise were evaluated for short-to-medium and medium-to-long range aircraft with high bypass ratio and very high bypass ratio engines. The benefit of advanced high lift systems in reducing noise was found to be less than 1 effective-perceived-noise decibel level (EPNdB) when the aircraft were sized to minimize takeoff gross weight. These aircraft did, however, have smaller wings and lower engine thrusts for the same mission than aircraft with conventional high lift systems. When the advanced high lift system was implemented without reducing wing size and simultaneously using lower flap angles that provide higher L/D at approach a cumulative noise reduction of as much as 4 EPNdB was obtained. Comparison of aircraft configurations that have similar approach speeds showed cumulative noise reduction of 2.6 EPNdB that is purely the result of incorporating advanced high lift system in the aircraft design.
NASA Astrophysics Data System (ADS)
Almer, Alexander; Schnabel, Thomas; Perko, Roland; Raggam, Johann; Köfler, Armin; Feischl, Richard
2016-04-01
Climate change will lead to a dramatic increase in damage from forest fires in Europe by the end of this century. In the Mediterranean region, the average annual area affected by forest fires has quadrupled since the 1960s (WWF, 2012). The number of forest fires is also on the increase in Central and Northern Europe. The Austrian forest fire database shows a total of 584 fires for the period 2012 to 2014, while even large areas of Sweden were hit by forest fires in August 2014, which were brought under control only after two weeks of intense fire-fighting efforts supported by European civil protection modules. Based on these facts, the improvements in forest fire control are a major international issue in the quest to protect human lives and resources as well as to reduce the negative environmental impact of these fires to a minimum. Within this paper the development of a multi-functional airborne management support system within the frame of the Austrian national safety and security research programme (KIRAS) is described. The main goal of the developments is to assist crisis management tasks of civil emergency teams and armed forces in disaster management by providing multi spectral, near real-time airborne image data products. As time, flexibility and reliability as well as objective information are crucial aspects in emergency management, the used components are tailored to meet these requirements. An airborne multi-functional management support system was developed as part of the national funded project AIRWATCH, which enables real-time monitoring of natural disasters based on optical and thermal images. Airborne image acquisition, a broadband line of sight downlink and near real-time processing solutions allow the generation of an up-to-date geo-referenced situation map. Furthermore, this paper presents ongoing developments for innovative extensions and research activities designed to optimize command operations in national and international fire
Lake, Jason; Lauder, Mike; Smith, Neal; Shorter, Kathleen
2012-08-01
This study compared differences between ballistic jump squat (B) and nonballistic back squat (NB) force, velocity, power, and relative acceleration duration, and the effect that the method used to identify the positive lifting phase had on these parameters. Ground reaction force and barbell kinematics were recorded from 30 resistance trained men during B and NB performance with 45% 1RM. Force, velocity, and power was averaged over positive lifting phases identified using the traditional peak barbell displacement (PD) and positive impulse method. No significant differences were found between B and NB mean force, and mean power, but B mean velocity was 14% greater than the NB equivalent. Positive impulse mean force was 24% greater than PD mean force, and B relative acceleration duration was 8.6% greater than the NB equivalent when PD was used to identify the end of the positive lifting phase. These results challenge common perceptions of B superiority for power development.
Wind Tunnel Testing of Powered Lift, All-Wing STOL Model
NASA Technical Reports Server (NTRS)
Collins, Scott W.; Westra, Bryan W.; Lin, John C.; Jones, Gregory S.; Zeune, Cal H.
2008-01-01
Short take-off and landing (STOL) systems can offer significant capabilities to warfighters and, for civil operators thriving on maximizing efficiencies they can improve airspace use while containing noise within airport environments. In order to provide data for next generation systems, a wind tunnel test of an all-wing cruise efficient, short take-off and landing (CE STOL) configuration was conducted in the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) 14- by 22-foot Subsonic Wind Tunnel. The test s purpose was to mature the aerodynamic aspects of an integrated powered lift system within an advanced mobility configuration capable of CE STOL. The full-span model made use of steady flap blowing and a lifting centerbody to achieve high lift coefficients. The test occurred during April through June of 2007 and included objectives for advancing the state-of-the-art of powered lift testing through gathering force and moment data, on-body pressure data, and off-body flow field measurements during automatically controlled blowing conditions. Data were obtained for variations in model configuration, angles of attack and sideslip, blowing coefficient, and height above ground. The database produced by this effort is being used to advance design techniques and computational tools for developing systems with integrated powered lift technologies.
NASA Astrophysics Data System (ADS)
Junkai, YAO; Danjie, ZHOU; Haibo, HE; Chengjun, HE; Zhiwei, SHI; Hai, DU
2017-04-01
The effects of the arrangement position and control parameters of nanosecond dielectric barrier discharge (NS-DBD) plasma actuators on lift enhancement for flying wing aircraft were investigated through wind tunnel experiments at a flow speed of 25 m s‑1. The aerodynamic forces and moments were obtained by a six-component balance at angles of attack ranging from ‑4° to 28°. The lift, drag and pitching moment coefficients were compared for the cases with and without plasma control. The results revealed that the maximum control effect was achieved by placing the actuator at the leading edge of the inner and middle wing, for which the maximum lift coefficient increased by 37.8% and the stall angle of attack was postponed by 8° compared with the plasma-off case. The effects of modulation frequency and discharge voltage were also investigated. The results revealed that the lift enhancement effect of the NS-DBD plasma actuators was strongly influenced by the modulation frequency. Significant control effects were obtained at f = 70 Hz, corresponding to F + ≈ 1. The result for the pitching moment coefficient demonstrated that the plasma actuator can induce the reattachment of the separation flows when it is actuated. However, the results indicated that the discharge voltage had a negligible influence on the lift enhancement effect.
NASA Heavy Lift Rotorcraft Systems Investigation
NASA Technical Reports Server (NTRS)
Johnson, Wayne; Yamauchi, Gloria K.; Watts, Michael E.
2005-01-01
The NASA Heavy Lift Rotorcraft Systems Investigation examined in depth several rotorcraft configurations for large civil transport, designed to meet the technology goals of the NASA Vehicle Systems Program. The investigation identified the Large Civil Tiltrotor as the configuration with the best potential to meet the technology goals. The design presented was economically competitive, with the potential for substantial impact on the air transportation system. The keys to achieving a competitive aircraft were low drag airframe and low disk loading rotors; structural weight reduction, for both airframe and rotors; drive system weight reduction; improved engine efficiency; low maintenance design; and manufacturing cost comparable to fixed-wing aircraft. Risk reduction plans were developed to provide the strategic direction to support a heavy-lift rotorcraft development. The following high risk areas were identified for heavy lift rotorcraft: high torque, light weight drive system; high performance, structurally efficient rotor/wing system; low noise aircraft; and super-integrated vehicle management system.
TMI-2 reactor vessel plenum final lift
Wilson, D C
1986-01-01
Removal of the plenum assembly from the TMI-2 reactor vessel was necessary to gain access to the core region for defueling. The plenum was lifted from the reactor vessel by the polar crane using three specially designed pendant assemblies. It was then transferred in air to the flooded deep end of the refueling canal and lowered onto a storage stand where it will remain throughout the defueling effort. The lift and transfer were successfully accomplished on May 15, 1985 in just under three hours by a lift team located in a shielded area within the reactor building. The success of the program is attributed to extensive mockup and training activities plus thorough preparations to address potential problems. 54 refs.
Unsteady lifting-line theory with applications
NASA Technical Reports Server (NTRS)
Ahmadi, A. R.; Widnall, S. E.
1982-01-01
Unsteady lifting-line theory is developed for a flexible unswept wing of large aspect ratio oscillating at low frequency in inviscid incompressible flow. The theory is formulated in terms of the acceleration potential and treated by the method of matched asymptotic expansions. The wing displacements are prescribed and the pressure field, airloads, and unsteady induced downwash are obtained in closed form. Sample numerical calculations are presented. The present work identifies and resolves errors in the unsteady lifting-line theory of James and points out a limitation in that of Van Holten. Comparison of the results of Reissner's approximate unsteady lifting-surface theory with those of the present work shows favorable agreement. The present work thus provides some formal justification for Reissner's ad hoc theory. For engineering purposes, the region of applicability of the theory in the reduced frequency-aspect ratio domain is identified approximately and found to cover most cases of practical interest.
Coriolis effects enhance lift on revolving wings.
Jardin, T; David, L
2015-03-01
At high angles of attack, an aircraft wing stalls. This dreaded event is characterized by the development of a leading edge vortex on the upper surface of the wing, followed by its shedding which causes a drastic drop in the aerodynamic lift. At similar angles of attack, the leading edge vortex on an insect wing or an autorotating seed membrane remains robustly attached, ensuring high sustained lift. What are the mechanisms responsible for both leading edge vortex attachment and high lift generation on revolving wings? We review the three main hypotheses that attempt to explain this specificity and, using direct numerical simulations of the Navier-Stokes equations, we show that the latter originates in Coriolis effects.
Kumar, S
1994-12-01
Nine normal male subjects (mean age 28.2 years and mean weight 72.6 kg) performed 20 standardized maximal effort lifting tasks. They were asked to perform stoop and squat lifts at half, three-quarters and full individual horizontal reach distances in mid-sagittal plane in isometric and isokinetic modes (fixed velocity 60 cm/s). Both stoop and squat lifts were initiated at the floor level and terminated at the individual's knuckle height keeping the horizontal distance constant throughout the lift. The isometric stoop lifts were performed with hip at 60 degrees and 90 degrees of flexion with hands at preselected reach distances. The isometric squat lifts were performed with knees at 90 degrees and 135 degrees of flexion with hands at similarly preselected reach distances. The force was measured using a Static Dynamic Strength Tester with load cell (SM 1000). The postures were recorded using a two-dimensional Peak Performance System with an event synchronizing unit. The load cell was sampled at 60 Hz and the video filming was done at 60 frames per second. The force and postural data were fed to a biomechanical model (Cheng and Kumar 1991) to extract external moment and lumbosacral compression. The strengths generated in different conditions were significantly different (p < 0.01). The strength variation ranged by up to 73% whereas the lumbosacral compression varied by only up to 15%. A high level of lumbosacral compression was maintained in all conditions.
Soccer ball lift coefficients via trajectory analysis
NASA Astrophysics Data System (ADS)
Goff, John Eric; Carré, Matt J.
2010-07-01
We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin parameters that have not been obtained by today's wind tunnels. Our trajectory analysis technique is not only a valuable tool for professional sports scientists, it is also accessible to students with a background in undergraduate-level classical mechanics.
Design of signal-adapted multidimensional lifting scheme for lossy coding.
Gouze, Annabelle; Antonini, Marc; Barlaud, Michel; Macq, Benoît
2004-12-01
This paper proposes a new method for the design of lifting filters to compute a multidimensional nonseparable wavelet transform. Our approach is stated in the general case, and is illustrated for the 2-D separable and for the quincunx images. Results are shown for the JPEG2000 database and for satellite images acquired on a quincunx sampling grid. The design of efficient quincunx filters is a difficult challenge which has already been addressed for specific cases. Our approach enables the design of less expensive filters adapted to the signal statistics to enhance the compression efficiency in a more general case. It is based on a two-step lifting scheme and joins the lifting theory with Wiener's optimization. The prediction step is designed in order to minimize the variance of the signal, and the update step is designed in order to minimize a reconstruction error. Application for lossy compression shows the performances of the method.
Performance of Advanced Heavy-Lift, High-Speed Rotorcraft Configurations
NASA Technical Reports Server (NTRS)
Johnson, Wayne; Yeo, Hyeonsoo; Acree, C. W., Jr.
2007-01-01
The aerodynamic performance of rotorcraft designed for heavy-lift and high-speed cruise is examined. Configurations considered include the tiltrotor, the compound helicopter, and the lift-offset rotor. Design conditions are hover and 250-350 knot cruise, at 5k/ISA+20oC (civil) or 4k/95oF (military); with cruise conditions at 4000 or 30,000 ft. The performance was calculated using the comprehensive analysis CAMRAD II, emphasizing rotor optimization and performance, including wing-rotor interference. Aircraft performance was calculated using estimates of the aircraft drag and auxiliary propulsion efficiency. The performance metric is total power, in terms of equivalent aircraft lift-to-drag ratio L/D = WV/P for cruise, and figure of merit for hover.
Aerostructural Level Set Topology Optimization for a Common Research Model Wing
NASA Technical Reports Server (NTRS)
Dunning, Peter D.; Stanford, Bret K.; Kim, H. Alicia
2014-01-01
The purpose of this work is to use level set topology optimization to improve the design of a representative wing box structure for the NASA common research model. The objective is to minimize the total compliance of the structure under aerodynamic and body force loading, where the aerodynamic loading is coupled to the structural deformation. A taxi bump case was also considered, where only body force loads were applied. The trim condition that aerodynamic lift must balance the total weight of the aircraft is enforced by allowing the root angle of attack to change. The level set optimization method is implemented on an unstructured three-dimensional grid, so that the method can optimize a wing box with arbitrary geometry. Fast matching and upwind schemes are developed for an unstructured grid, which make the level set method robust and efficient. The adjoint method is used to obtain the coupled shape sensitivities required to perform aerostructural optimization of the wing box structure.
Lift-off dynamics in a simple jumping robot
NASA Astrophysics Data System (ADS)
Aguilar, Jeffrey; Lesov, Alex; Wiesenfeld, Kurt; Goldman, Daniel I.
2013-03-01
Jumping is an important behavior utilized by animals to escape predation, hunt, reach higher ground, and as a primary mode of locomotion. Many mathematical and physical robot models use numerous parameters and multi-link legs to accurately model jumping dynamics. However, a simple robot model can reveal important principles of high performance jumping. We study vertical jumping in a simple robot comprising an actuated mass-spring arrangement. The actuator frequency and phase are systematically varied to find optimal performance. Optimal jumps occur above and below (but not at) the robot's resonant frequency f0. Two distinct jumping modes emerge: a simple jump which is optimal above f0 is achievable with a squat maneuver, and a peculiar stutter jump which is optimal below f0 is generated with a counter-movement. A simple dynamical model reveals how optimal lift-off results from non-resonant transient dynamics. An expanded explanation of this work is provided at http://crablab.gatech.edu/pages/jumpingrobot/index.html This work was supported by the GEM Consortium, Burroughs Wellcome Fund, ARL MAST CTA, and NSF PoLS.
Blade Design Trade-Offs Using Low-Lift Airfoils for Stall-Regulated HAWTs
Giguere, P.; Selig, M. S.; Tangler, J. L.
1999-04-08
A systematic blade design study was conducted to explore the trade-offs in using low-lift airfoils for a 750-kilowatt stall-regulated wind turbine. Tip-region airfoils having a maximum lift coefficient ranging from 0.7-1.2 were considered in this study, with the main objective of identifying the practical lower limit for the maximum lift coefficient. Blades were optimized for both maximum annual energy production and minimum cost of energy using a method that takes into account aerodynamic and structural considerations. The results indicate that reducing the maximum lift coefficient below the upper limit considered in this study increases the cost of energy independently of the wind regime. As a consequence, higher maximum lift coefficient airfoils for the tip-region of the blade become more desirable as machine size increases, as long as they provide gentle stall characteristics. The conclusions are applicable to large wind turbines that use passive or active stall to regulate peak power.
Bano, Farheen; Mallick, Zulqernian; Ali Khan, Abid
2015-01-01
This study was to investigate the effects of grip force, frequency, stroke rotation and grip-span on discomfort and obtain best posture for hand tool users. Fifteen male participants volunteered in this study. Participants performed combined gripping with torqueing exertions for 5 min for two levels of frequency (10 and 20 exertions/min) at two levels of grip force (50 and 70 N), two levels of stroke rotation (30(○) and 60(○)) and three levels of grip-span (4.7, 6 and 7.3 cm). Therefore, a 2×2×2×3 full factorial design was used. The analysis of variance (ANOVA) showed that frequency, stroke rotation and grip-span were significant on discomfort score. Minimum discomfort and comfortable posture was found to be 90 N grip force with 10 exertions/min for 60° stroke rotation at 6-cm grip-span. The grip force, frequency and stroke rotation were found significant on EMG activity of forearm muscles using multivariate analysis of variance (MANOVA). The extensor muscles were found more activated than flexor muscles during the given task.
The lift-fan powered-lift aircraft concept: Lessons learned
NASA Technical Reports Server (NTRS)
Deckert, Wallace H.
1993-01-01
This is one of a series of reports on the lessons learned from past research related to lift-fan aircraft concepts. An extensive review is presented of the many lift-fan aircraft design studies conducted by both government and industry over the past 45 years. Mission applications and design integration including discussions on manifolding hot gas generators, hot gas dusting, and energy transfer control are addressed. Past lift-fan evaluations of the Avrocar are discussed. Lessons learned from these past efforts are identified.
NASA Astrophysics Data System (ADS)
Sato, Taichi; Oyama, Keiichi; Iimura, Miki; Kobayashi, Harumi; Tanaka, Kihachiro
We have performed basic experiments for the purpose of applying onomatopoeia to engineering problems. In these experiments, test subjects were made to perform lifting actions while listening to onomatopoeic utterances. We thereby demonstrated that there is a relationship between the onomatopoeic utterances and the lifting forces exerted by the test subjects. We examined how the lifting forces are related to the envelope of onomatopoeic utterances. Furthermore, we investigated how the lifting force is affected depending on whether or not emotion is expressed when uttering the onomatopoeia.
Experimental Investigation of a Point Design Optimized Arrow Wing HSCT Configuration
NASA Technical Reports Server (NTRS)
Narducci, Robert P.; Sundaram, P.; Agrawal, Shreekant; Cheung, S.; Arslan, A. E.; Martin, G. L.
1999-01-01
The M2.4-7A Arrow Wing HSCT configuration was optimized for straight and level cruise at a Mach number of 2.4 and a lift coefficient of 0.10. A quasi-Newton optimization scheme maximized the lift-to-drag ratio (by minimizing drag-to-lift) using Euler solutions from FL067 to estimate the lift and drag forces. A 1.675% wind-tunnel model of the Opt5 HSCT configuration was built to validate the design methodology. Experimental data gathered at the NASA Langley Unitary Plan Wind Tunnel (UPWT) section #2 facility verified CFL3D Euler and Navier-Stokes predictions of the Opt5 performance at the design point. In turn, CFL3D confirmed the improvement in the lift-to-drag ratio obtained during the optimization, thus validating the design procedure. A data base at off-design conditions was obtained during three wind-tunnel tests. The entry into NASA Langley UPWT section #2 obtained data at a free stream Mach number, M(sub infinity), of 2.55 as well as the design Mach number, M(sub infinity)=2.4. Data from a Mach number range of 1.8 to 2.4 was taken at UPWT section #1. Transonic and low supersonic Mach numbers, M(sub infinity)=0.6 to 1.2, was gathered at the NASA Langley 16 ft. Transonic Wind Tunnel (TWT). In addition to good agreement between CFD and experimental data, highlights from the wind-tunnel tests include a trip dot study suggesting a linear relationship between trip dot drag and Mach number, an aeroelastic study that measured the outboard wing deflection and twist, and a flap scheduling study that identifies the possibility of only one leading-edge and trailing-edge flap setting for transonic cruise and another for low supersonic acceleration.
Effect of outer wing separation on lift and thrust generation in a flapping wing system.
Mahardika, Nanang; Viet, Nguyen Quoc; Park, Hoon Cheol
2011-09-01
We explore the implementation of wing feather separation and lead-lagging motion to a flapping wing. A biomimetic flapping wing system with separated outer wings is designed and demonstrated. The artificial wing feather separation is implemented in the biomimetic wing by dividing the wing into inner and outer wings. The features of flapping, lead-lagging, and outer wing separation of the flapping wing system are captured by a high-speed camera for evaluation. The performance of the flapping wing system with separated outer wings is compared to that of a flapping wing system with closed outer wings in terms of forward force and downward force production. For a low flapping frequency ranging from 2.47 to 3.90 Hz, the proposed biomimetic flapping wing system shows a higher thrust and lift generation capability as demonstrated by a series of experiments. For 1.6 V application (lower frequency operation), the flapping wing system with separated wings could generate about 56% higher forward force and about 61% less downward force compared to that with closed wings, which is enough to demonstrate larger thrust and lift production capability of the separated outer wings. The experiments show that the outer parts of the separated wings are able to deform, resulting in a smaller amount of drag production during the upstroke, while still producing relatively greater lift and thrust during the downstroke.
Compound Channels, Transition Expectations, and Liftings
Accardi, L.; Ohya, M.
1999-01-15
In Section 1 we introduce the notion of lifting as a generalization of the notion of compound state introduced in [21] and [22] and we show that this notion allows a unified approach to the problems of quantum measurement and of signal transmission through quantum channels. The dual of a linear lifting is a transition expectation in the sense of [3] and we characterize those transition expectations which arise from compound states in the sense of [22]. In Section 2 we characterize those liftings whose range is contained in the closed convex hull of product states and we prove that the corresponding quantum Markov chains [2] are uniquely determined by a classical generalization of both the quantum random walks of [4] and the locally diagonalizable states considered in [3]. In Section 4, as a first application of the above results, we prove that the attenuation (beam splitting) process for optical communication treated in [21] can be described in a simpler and more general way in terms of liftings and of transition expectations. The error probabilty of information transmission in the attenuation process is rederived from our new description. We also obtain some new results concerning the explicit computation of error probabilities in the squeezing case.
Effects of Mach Number on Maximum Lift
1947-01-01
raAruaKJ tablo, grapho Haeh nunber effect on r»\\irirmr> lift is datomlncd for unsuopt end onopt-back Dingo . Suopt-back ulngo oboa tho oarx> early tip...ulngo. &7opt-toack uingo ahan tho anm early tip stalling tondancioa at high opoede ae they do at leu opoede. For unsnopt Dingo tho Cj p^ of
High gantry for lifting and handling
NASA Technical Reports Server (NTRS)
Kerley, J. J., Jr.; Tereniak, W. T.
1977-01-01
Standard gantry has been inexpensively modified with standard pipes to allow lifting of heavy loads to distances between 14 and 30 ft. Addition of air mounts permits extensive and sensitive equipment to be moved smoothly and safely over smooth or moderately rough surfaces. Unit has been tested at 6000 pounds without yielding.
The Monoplane as a Lifting Vortex Surface
NASA Technical Reports Server (NTRS)
Blenk, Hermann
1947-01-01
In Prandtl's airfoil theory the monoplane was replaced by a single lifting vortex line and yielded fairly practical results. However, the theory remained restricted to the straight wing. Yawed wings and those curved in flight direction could not be computed with this first approximation; for these the chordwise lift distribution must be taken into consideration. For the two-dimensional problem the transition from the lifting line to the lifting surface has been explained by Birnbaum. In the present report the transition to the three-dimensional problem is undertaken. The first fundamental problem involves the prediction of flow, profile, and drag for prescribed circulation distribution on the straight rectangular wing, the yawed wing for lateral boundaries parallel to the direction of flight, the swept-back wing, and the rectangular wing in slipping, with the necessary series developments for carrying through the calculations, the practical range of convergence of which does not comprise the wing tips or the break point of the swept-back wing. The second problem concerns the calculation of the circulation distribution with given profile for a slipping rectangular monoplane with flat profile and aspect ratio 6, and a rectangular wing with cambered profile and variable aspect ratio-the latter serving as check of the so-called conversion formulas of the airfoil theory.
O.H. Module Vacuum Lifting Fixture
McGivern, Paul; /Fermilab
1987-12-31
In order to move the 800 lb. copper plates that make up the O.H. modules a vacuum lifting device has been made that will lift the plates safely. The purpose of this report is to provide documentation for the structural integrity of the system and to make sure that it passes all of the safety requirements that have been established for a system of this nature. The vacuum system is composed of a PIAB model M125 vacuum pump that has the pumping capacity of 27 in. Hg. This pump will produce vacuum for three 8 1/2 in. diameter suction cups or pads. A pressure gauge is fixed on the unit to allow the operator to continually monitor the pressure during all lifts. An additional safety feature is a mechanical vacuum monitoring device that is set to emit a shrill tone if the system vacuum falls below 24 in. Hg. A 'bleed' valve fixed on the unit will be used to let the system go to atmospheric pressure once the lift is complete. A 3 psi. check valve and a vacuum reserve of 384 in. is used to insure that the device will not just drop the object if the pump fails. A schematic for the pumping system is given in Figure 1.
NASA HL-20 PLS Lifting Body (Mockup)
NASA Technical Reports Server (NTRS)
1991-01-01
NASA HL-20 PLS Lifting Body (Mockup): The HL-20 came into use at Langley in October 1990 and is a full-scale non-flying mockup. This mockup was used for engineering studies of maintainability of the vehicle, as testing crew positions, pilot visibility and other human factors considerations.
Image compression with directional lifting on separated sections
NASA Astrophysics Data System (ADS)
Zhu, Jieying; Wang, Nengchao
2007-11-01
A novel image compression scheme is presented that the directional sections are separated and transformed differently from the rest of image. The discrete directions of anisotropic pixels are calculated and then grouped to compact directional sections. One dimensional (1-D) adaptive directional lifting is continuously applied along orientations of direction sections other than applying 1-D wavelet transform alternately in two dimensions for the whole image. For the rest sections, 2-D adaptive lifting filters are applied according to pixels' positions. Our single embedded coding stream can be truncated exactly for any bit rate. Experiments have showed that large coefficients can be significantly reduced along directional sections by our transform which makes energy more compact than traditional wavelet transform. Though rate-distortion (R-D) optimization isn't exploited, the PSNR is still comparable to that of JPEG-2000 with 9/7 filters at high bit rates. And at low bit rates, the visual quality is better than that of JPEG-2000 for along directional sections both blurring and ringing artifacts can be avoided and edge preservation is good.
Some measurements of an EBF powered-lift wake
NASA Technical Reports Server (NTRS)
Johnson, W. G., Jr.
1976-01-01
Results from a wind tunnel investigation in which velocity vector measurements were obtained in the near wake of an externally blown flap powered lift configuration were analyzed. These measurements were used to develop spanwise distributions for the momentum strength and location of the engine exhaust stream tube with the results used as input parameters to one jet flap analytical method. It is shown that a comparison of the momentum coefficients obtained from forward speed wake surveys with the predicted values from static force data results in a good correlation, which verifies the use of the flap thrust recovery factor as a means of predicting the momentum strength at the flap trailing edge. Also, when wake survey distributions of momentum strength and direction are used as input parameters to one analytical jet flap method, the results show reasonable agreement between the experimental data and analytical results.
View of lifting girder and tower support superstructure on Tensaw ...
View of lifting girder and tower support superstructure on Tensaw River Bridge truss No. 2, looking northwest. Showing rope connectors and deflector sheaves. - Tensaw River Lift Bridge, Spanning Tensaw River at U.S. Highway 90, Mobile, Mobile County, AL
View of central lift span truss web of Tensaw River ...
View of central lift span truss web of Tensaw River Bridge, showing support girders for life house, looking east - Tensaw River Lift Bridge, Spanning Tensaw River at U.S. Highway 90, Mobile, Mobile County, AL
39. DETAIL AERIAL VIEW LOOKING AT 210' 9' LIFT SPAN ...
39. DETAIL AERIAL VIEW LOOKING AT 210' 9' LIFT SPAN TOWER SHEAVES SHOWING 1 SET WITH AND 1 SET WITHOUT SHEAVE HOODS - Central Railroad of New Jersey, Newark Bay Lift Bridge, Spanning Newark Bay, Newark, Essex County, NJ
Lift estimation of Half-Rotating Wing in hovering flight
NASA Astrophysics Data System (ADS)
Wang, X. Y.; Dong, Y. P.; Qiu, Z. Z.; Zhang, Y. Q.; Shan, J. H.
2016-11-01
Half-Rotating Wing (HRW) is a new kind of flapping wing system with rotating flapping instead of oscillating flapping. Estimating approach of hovering lift which generated in hovering flight was important theoretical foundation to design aircraft using HRW. The working principle of HRW based on Half-Rotating Mechanism (HRM) was firstly introduced in this paper. Generating process of lift by HRW was also given. The calculating models of two lift mechanisms for HRW, including Lift of Flow Around Wing (LFAW) and Lift of Flow Dragging Wing (LFDW), were respectively established. The lift estimating model of HRW was further deduced, by which hovering lift for HRW with different angular velocity could be calculated. Case study using XFLOW software simulation indicates that the above estimating method was effective and feasible to predict roughly the hovering lift for a new HRW system.
NASA Astrophysics Data System (ADS)
Foley, Jonathan J.; Mazziotti, David A.
2010-10-01
An efficient method for geometry optimization based on solving the anti-Hermitian contracted Schrödinger equation (ACSE) is presented. We formulate a reduced version of the Hellmann-Feynman theorem (HFT) in terms of the two-electron reduced Hamiltonian operator and the two-electron reduced density matrix (2-RDM). The HFT offers a considerable reduction in computational cost over methods which rely on numerical derivatives. While previous geometry optimizations with numerical gradients required 2M evaluations of the ACSE where M is the number of nuclear degrees of freedom, the HFT requires only a single ACSE calculation of the 2-RDM per gradient. Synthesizing geometry optimization techniques with recent extensions of the ACSE theory to arbitrary electronic and spin states provides an important suite of tools for accurately determining equilibrium and transition-state structures of ground- and excited-state molecules in closed- and open-shell configurations. The ability of the ACSE to balance single- and multi-reference correlation is particularly advantageous in the determination of excited-state geometries where the electronic configurations differ greatly from the ground-state reference. Applications are made to closed-shell molecules N2, CO, H2O, the open-shell molecules B2 and CH, and the excited state molecules N2, B2, and BH. We also study the HCN ↔ HNC isomerization and the geometry optimization of hydroxyurea, a molecule which has a significant role in the treatment of sickle-cell anaemia.
Ontogeny of lift and drag production in ground birds
Heers, Ashley M.; Tobalske, Bret W.; Dial, Kenneth P.
2011-01-01
The juvenile period is often a crucial interval for selective pressure on locomotor ability. Although flight is central to avian biology, little is known about factors that limit flight performance during development. To improve understanding of flight ontogeny, we used a propeller (revolving wing) model to test how wing shape and feather structure influence aerodynamic performance during development in the precocial chukar partridge (Alectoris chukar, 4 to >100 days post hatching). We spun wings in mid-downstroke posture and measured lift (L) and drag (D) using a force plate upon which the propeller assembly was mounted. Our findings demonstrate a clear relationship between feather morphology and aerodynamic performance. Independent of size and velocity, older wings with stiffer and more asymmetrical feathers, high numbers of barbicels and a high degree of overlap between barbules generate greater L and L:D ratios than younger wings with flexible, relatively symmetrical and less cohesive feathers. The gradual transition from immature feathers and drag-based performance to more mature feathers and lift-based performance appears to coincide with ontogenetic transitions in locomotor capacity. Younger birds engage in behaviors that require little aerodynamic force and that allow D to contribute to weight support, whereas older birds may expand their behavioral repertoire by flapping with higher tip velocities and generating greater L. Incipient wings are, therefore, uniquely but immediately functional and provide flight-incapable juveniles with access to three-dimensional environments and refugia. Such access may have conferred selective advantages to theropods with protowings during the evolution of avian flight. PMID:21307057
NASA Astrophysics Data System (ADS)
Merrett, Craig G.
-partial differential equations. The spatial component of the governing equations is eliminated using a series expansion of basis functions and by applying Galerkin's method. The number of terms in the series expansion affects the convergence of the spatial component, and convergence is best determined by the von Koch rules that previously appeared for column buckling problems. After elimination of the spatial component, an ordinary integral-differential equation in time remains. The dynamic stability of elastic and viscoelastic problems is assessed using the determinant of the governing system of equations and the time component of the solution in the form exp (lambda t). The determinant is in terms of lambda where the values of lambda are the latent roots of the aero-servo-viscoelastic system. The real component of lambda dictates the stability of the system. If all the real components are negative, the system is stable. If at least one real component is zero and all others are negative, the system is neutrally stable. If one or more real components are positive, the system is unstable. In aero-servo-viscoelasticity, the neutrally stable condition is termed flutter. For an aero-servo-viscoelastic lifting surface, the unstable condition is historically termed torsional divergence. The more general aero-servo-viscoelastic theory has produced a number of important results, enumerated in the following list: 1. Subsonic panel flutter can occur before panel instability. This result overturned a long held assumption in aeroelasticity, and was produced by the novel application of the von Koch rules for convergence. Further, experimental results from the 1950s by the Air Force were retrieved to provide additional proof. 2. An expanded definition for flutter of a lifting surface. The legacy definition is that flutter is the first occurrence of simple harmonic motion of a structure, and the flight velocity at which this motion occurs is taken as the flutter speed. The expanded definition
Yamada, Kenji; Kido, Michiko; Okada, Shima; Nomura, Taishin; Ohno, Yuko
2016-01-01
Although numerous studies have analyzed the relationship between manual material handling (MMH) and the forces acting on the lumbar spine, the difference in the MMH between experts and novices through the analysis of measured data has not been well studied. The purpose of this paper was to analyze the difference in the MMH positions between ten skilled experts working at a freight transport company (Group 1) and five unskilled novices without any experience (Group 2) during asymmetric lifting. All the human subjects performed asymmetric lifting experiments with closed eyes; the experiments involved moving loads (6 and 18 kg) to the left side. Time series data of the vertical ground reaction force were measured, using a Wii Balance Board, and then, the center-of-pressure (CoP) trajectories were calculated. The balance board was used for the measurement, because it was reliable, inexpensive, and portable and provided good repeatability even on rough surfaces, and all the information pertaining to the load and worker under various conditions was captured without any omissions. Under the 18 kg load condition, the CoP positions for Group 2 were located on the same side during left asymmetric lifting; however, those for Group 1 were located on the opposite side during left asymmetric lifting (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$P <0.001$ \\end{document}). Furthermore, under the 6 kg load condition, the load weight influenced asymmetric lifting for most subjects of Group 2 such that the CoP positions were located on the opposite side (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin
Abadi, Ali Salehi Sahl; Mazlomi, Adel; Saraji, Gebraeil Nasl; Zeraati, Hojjat; Hadian, Mohammad Reza; Jafari, Amir Homayoun
2015-01-01
Introduction In spite of the widespread use of automation in industry, manual material handling (MMH) is still performed in many occupational settings. The emphasis on ergonomics in MMH tasks is due to the potential risks of workplace accidents and injuries. This study aimed to assess the effect of box size, frequency of lift, and height of lift on maximum acceptable weight of lift (MAWL) on the heart rates of male university students in Iran. Methods This experimental study was conducted in 2015 with 15 male students recruited from Tehran University of Medical Sciences. Each participant performed 18 different lifting tasks that involved three lifting frequencies (1lift/min, 4.3 lifts/min and 6.67 lifts/min), three lifting heights (floor to knuckle, knuckle to shoulder, and shoulder to arm reach), and two box sizes. Each set of experiments was conducted during the 20 min work period using the free-style lifting technique. The working heart rates (WHR) were recorded for the entire duration. In this study, we used SPSS version 18 software and descriptive statistical methods, analysis of variance (ANOVA), and the t-test for data analysis. Results The results of the ANOVA showed that there was a significant difference between the mean of MAWL in terms of frequencies of lifts (p = 0.02). Tukey’s post hoc test indicated that there was a significant difference between the frequencies of 1 lift/minute and 6.67 lifts/minute (p = 0. 01). There was a significant difference between the mean heart rates in terms of frequencies of lifts (p = 0.006), and Tukey’s post hoc test indicated a significant difference between the frequencies of 1 lift/minute and 6.67 lifts/minute (p = 0.004). But, there was no significant difference between the mean of MAWL and the mean heart rate in terms of lifting heights (p > 0.05). The results of the t-test showed that there was a significant difference between the mean of MAWL and the mean heart rate in terms of the sizes of the two boxes (p
21 CFR 880.5500 - AC-powered patient lift.
Code of Federal Regulations, 2010 CFR
2010-04-01
...) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Therapeutic Devices § 880.5500 AC-powered patient lift. (a) Identification. An AC-powered lift is an electrically powered device either fixed or mobile, used to lift and transport patients in the horizontal or...
21 CFR 880.5500 - AC-powered patient lift.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 21 Food and Drugs 8 2011-04-01 2011-04-01 false AC-powered patient lift. 880.5500 Section 880.5500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Devices § 880.5500 AC-powered patient lift. (a) Identification. An AC-powered lift is an...
33 CFR 118.85 - Lights on vertical lift bridges.
Code of Federal Regulations, 2011 CFR
2011-07-01
... below the outermost edge of the bridge span structure so as to be visible from an approaching vessel... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span...
33 CFR 118.85 - Lights on vertical lift bridges.
Code of Federal Regulations, 2012 CFR
2012-07-01
... below the outermost edge of the bridge span structure so as to be visible from an approaching vessel... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span...
33 CFR 118.85 - Lights on vertical lift bridges.
Code of Federal Regulations, 2010 CFR
2010-07-01
... below the outermost edge of the bridge span structure so as to be visible from an approaching vessel... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span...
14 CFR 29.551 - Auxiliary lifting surfaces.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Auxiliary lifting surfaces. 29.551 Section 29.551 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT....551 Auxiliary lifting surfaces. Each auxiliary lifting surface must be designed to withstand— (a)...
49 CFR 178.970 - Bottom lift test.
Code of Federal Regulations, 2013 CFR
2013-10-01
... gross mass, the load being evenly distributed. (c) Test method. All Large Packaging design types must be... 49 Transportation 3 2013-10-01 2013-10-01 false Bottom lift test. 178.970 Section 178.970... Packagings § 178.970 Bottom lift test. (a) General. The bottom lift test must be conducted for...
49 CFR 178.1050 - Top lift test.
Code of Federal Regulations, 2013 CFR
2013-10-01
... Containers § 178.1050 Top lift test. (a) General. The top lift test must be conducted for the qualification... permissible gross mass, the load being evenly distributed. (c) Test method. (1) A Flexible Bulk Container must... 49 Transportation 3 2013-10-01 2013-10-01 false Top lift test. 178.1050 Section...
Waddell, Morgan L; Fine, Justin M; Likens, Aaron D; Amazeen, Eric L; Amazeen, Polemnia G
2016-03-01
Researchers generally agree that perceived heaviness is based on the actions associated with unsupported holding. Psychophysical research has supported this idea, as has psychophysiological research connecting muscle activity to the perceptions of heaviness and effort. However, the role of muscle activity in the context of the resulting motions has not been investigated. In the present study, perceptions of heaviness were recorded along with the electromyogram (EMG) of the lifting muscle and peak acceleration of the lift. Consistent with predictions derived from Newton's Second Law of motion (Force=Mass × Acceleration), normal and illusory perceptions of heaviness were a function of the ratio of muscle activity to lifting acceleration. These results identify a psychophysiological mechanism for heaviness perception based on the forces and motions associated with unsupported holding.
General equilibrium characteristics of a dual-lift helicopter system
NASA Technical Reports Server (NTRS)
Cicolani, L. S.; Kanning, G.
1986-01-01
The equilibrium characteristics of a dual-lift helicopter system are examined. The system consists of the cargo attached by cables to the endpoints of a spreader bar which is suspended by cables below two helicopters. Results are given for the orientation angles of the suspension system and its internal forces, and for the helicopter thrust vector requirements under general circumstances, including nonidentical helicopters, any accelerating or static equilibrium reference flight condition, any system heading relative to the flight direction, and any distribution of the load to the two helicopters. Optimum tether angles which minimize the sum of the required thrust magnitudes are also determined. The analysis does not consider the attitude degrees of freedom of the load and helicopters in detail, but assumes that these bodies are stable, and that their aerodynamic forces in equilibrium flight can be determined independently as functions of the reference trajectory. The ranges of these forces for sample helicopters and loads are examined and their effects on the equilibrium characteristics are given parametrically in the results.
Aft-End Flow of a Large-Scale Lifting Body During Free-Flight Tests
NASA Technical Reports Server (NTRS)
Banks, Daniel W.; Fisher, David F.
2006-01-01
Free-flight tests of a large-scale lifting-body configuration, the X-38 aircraft, were conducted using tufts to characterize the flow on the aft end, specifically in the inboard region of the vertical fins. Pressure data was collected on the fins and base. Flow direction and movement were correlated with surface pressure and flight condition. The X-38 was conceived to be a rescue vehicle for the International Space Station. The vehicle shape was derived from the U.S. Air Force X-24 lifting body. Free-flight tests of the X-38 configuration were conducted at the NASA Dryden Flight Research Center at Edwards Air Force Base, California from 1997 to 2001.
Anticipatory Planning and Control of Grasp Positions and Forces for Dexterous Two-Digit Manipulation
Fu, Qiushi; Zhang, Wei; Santello, Marco
2010-01-01
Dexterous object manipulation requires anticipatory control of digit positions and forces. Despite extensive studies on sensorimotor learning of digit forces, how humans learn to coordinate digit positions and forces has never been addressed. Furthermore, the functional role of anticipatory modulation of digit placement to object properties remains to be investigated. We addressed these questions by asking human subjects (12 females, 12 males) to grasp and lift an inverted T-shaped object using precision grip at constrained or self-chosen locations. The task requirement was to minimize object roll during lift. When digit position was not constrained, subjects could have implemented many equally valid digit position-force coordination patterns. However, choice of digit placement might also have resulted in large trial-to-trial variability of digit position, hence challenging the extent to which the Central Nervous System could have relied on sensorimotor memories for anticipatory control of digit forces. We hypothesized that subjects would modulate (1) digit placement for optimal force distribution and (2) digit forces as a function of variable digit positions. While all subjects learned to minimize object roll within the first three trials, the unconstrained device was associated with significantly smaller grip forces but larger variability of digit positions. Importantly, however, digit load force modulation compensated for position variability, thus ensuring consistent object roll minimization on each trial. This indicates that subjects learned object manipulation by integrating sensorimotor memories with sensory feedback about digit positions. These results are discussed in the context of motor equivalence and sensorimotor integration of grasp kinematics and kinetics. PMID:20610745
Launch pad abort of the HL-20 lifting body
NASA Astrophysics Data System (ADS)
Jackson, E. Bruce; Rivers, Robert A.; Chowdhry, Rajiv S.; Ragsdale, W. A.; Geyer, David W.
1994-11-01
The capability of the HL-20 lifting-body spacecraft to perform an abort maneuver from the launch pad to a horizontal landing was studied. This study involved both piloted and batch simulation models of the vehicle. A point-mass model of the vehicle was used for trajectory optimization studies. The piloted simulation was performed in a fixed-base simulator. A candidate maneuver was developed and refined for the worst-case launch-pad-to-landing-site geometry using an iterative procedure of off-line maneuver analysis followed by piloted evaluations and heuristic improvements to the candidate maneuver. The resulting maneuver demonstrates the launch site abort capability of the HL-20 and dictates requirements for nominal abort motor performance. The sensitivity of the maneuver to variations in several design parameters was documented.
Technology Assessment for Large Vertical-Lift Transport Tiltrotors
NASA Technical Reports Server (NTRS)
Germanowski, Peter J.; Stille, Brandon L.; Strauss, Michael P.
2010-01-01
The technical community has identified rotor efficiency as a critical enabling technology for large vertical-lift transport (LVLT) rotorcraft. The size and performance of LVLT aircraft will be far beyond current aircraft capabilities, enabling a transformational change in cargo transport effectiveness. Two candidate approaches for achieving high efficiency were considered for LVLT applications: a variable-diameter tiltrotor (VDTR) and a variable-speed tiltrotor (VSTR); the former utilizes variable-rotor geometry and the latter utilizes variable-rotor speed. Conceptual aircraft designs were synthesized for the VDTR and VSTR and compared to a conventional tiltrotor (CTR). The aircraft were optimized to a common objective function and bounded by a set of physical- and requirements-driven constraints. The resulting aircraft were compared for weight, size, performance, handling qualities, and other attributes. These comparisons established a measure of the relative merits of the variable-diameter and -speed rotor systems as enabling technologies for LVLT capability.
Human Factors Lessons Learned from Flight Testing Wingless Lifting Body Vehicles
NASA Technical Reports Server (NTRS)
Merlin, Peter William
2014-01-01
Since the 1960s, NASA, the Air Force, and now private industry have attempted to develop an operational human crewed reusable spacecraft with a wingless, lifting body configuration. This type of vehicle offers increased mission flexibility and greater reentry cross range than capsule type craft, and is particularly attractive due to the capability to land on a runway. That capability, however, adds complexity to the human factors engineering requirements of developing such aircraft.
A CFD Assessment of Several High-Lift Reference H Configuration Using Structured Grids
NASA Technical Reports Server (NTRS)
Lessard, Wendy B.
1999-01-01
The objective of this study is to calibrate a Navier-Stokes code for a high-lift Reference H configuration using structured grids. The outline of this presentation will first include a brief description of the grids used and the flow solver. Next the results will be presented in terms of convergence and resources used on the C-90. Predicted force and moment and surface pressure results are compared to experiment and off- and on-surface flow viz. is discussed.
Federal Register 2010, 2011, 2012, 2013, 2014
2010-06-11
... notice that it had issued a final determination concerning the country of origin of a lift unit for an... Code of Federal Regulations (CFR) concerning the country of origin of a lift unit for an overhead... determination concerning the country of origin of the lift unit which may be offered to the U.S....
NASA Technical Reports Server (NTRS)
Akaydin, H. Dogus; Moini-Yekta, Shayan; Housman, Jeffrey A.; Nguyen, Nhan
2015-01-01
In this paper, we present a static aeroelastic analysis of a wind tunnel test model of a wing in high-lift configuration using a viscous flow simulation code. The model wing was tailored to deform during the tests by amounts similar to a composite airliner wing in highlift conditions. This required use of a viscous flow analysis to predict the lift coefficient of the deformed wing accurately. We thus utilized an existing static aeroelastic analysis framework that involves an inviscid flow code (Cart3d) to predict the deformed shape of the wing, then utilized a viscous flow code (Overflow) to compute the aerodynamic loads on the deformed wing. This way, we reduced the cost of flow simulations needed for this analysis while still being able to predict the aerodynamic forces with reasonable accuracy. Our results suggest that the lift of the deformed wing may be higher or lower than that of the non-deformed wing, and the washout deformation of the wing is the key factor that changes the lift of the deformed wing in two distinct ways: while it decreases the lift at low to moderate angles of attack simply by lowering local angles of attack along the span, it increases the lift at high angles of attack by alleviating separation.
Ferritin protein imaging and detection by magnetic force microscopy.
Hsieh, Chiung-Wen; Zheng, Bin; Hsieh, Shuchen
2010-03-14
Magnetic force microscopy was used to image and detect ferritin proteins and the strength of the magnetic signal is discussed, revealing a large workable lift height between the magnetic tip and the ferritin sample.
On the Study of Lifting Mechanism of a Soft Porous Media under Fast Compression
NASA Astrophysics Data System (ADS)
Wu, Qianhong; Santhanam, S.; Nathan, R.; Vucbmss Team
2015-11-01
Fluid flow in a soft porous media under fast compressions is widely observed in biological systems and industrial applications. Despite of much progress, it remains unclear for the lifting mechanisms of the porous media due to the lack of complete experimental verifications of theoretical models. We report herein a unique approach to treat the limitation. The permeability of a synthetic fibrous porous media as a function of its compression was first measured. The material was then employed in a dynamic compression experiment using a porous-walled cylinder piston apparatus. The obtained transient compression of the porous media and the aforementioned permeability data were applied in different theoretical models for the pore pressure generation, which conclusively proved the validity of the consolidation theory developed by Wu et al. (JFM, 542, 281, 2005). Furthermore, the solid phase lifting force was separated from the total reaction force and was characterized by a new viscoelastic model, containing a nonlinear spring in conjunction with a linear viscoelastic Generalized Maxwell mechanical module. Excellent agreement was obtained between the experiment and the theory. Thus, the lifting forces from both the fluid and the solid were determined. This project is supported by NSF Grant 1511096.
LIFT Tenant Is Off and Running
NASA Technical Reports Server (NTRS)
Steele, Gynelle C.
2001-01-01
Lewis Incubator for Technology (LIFT) tenant, Analiza Inc., graduated from the incubator July 2000. Analiza develops technology and products for the early diagnosis of diseases, quality control of bio-pharmaceutical therapeutics, and other applications involving protein analyses. Technology links with NASA from existing and planned work are in areas of microfluidics and laser light scattering. Since their entry in LIFT in May, 1997, Analiza has: Received a $750,000 grant from the National Institutes of Health. Collaborated with a Nobel Prize winner on drug design. Collaborated with Bristol-Myers Squibb on the characterization of biological therapeutics. Added a Ph.D. senior scientist and several technicians. Received significant interest from major pharmaceutical companies about collaborating and acquiring Analiza technology.
Particle Lifting Processes in Dust Devils
NASA Astrophysics Data System (ADS)
Neakrase, L. D. V.; Balme, M. R.; Esposito, F.; Kelling, T.; Klose, M.; Kok, J. F.; Marticorena, B.; Merrison, J.; Patel, M.; Wurm, G.
2016-11-01
Particle lifting in dust devils on both Earth and Mars has been studied from many different perspectives, including how dust devils could influence the dust cycles of both planets. Here we review our current understanding of particle entrainment by dust devils by examining results from field observations on Earth and Mars, laboratory experiments (at terrestrial ambient and Mars-analog conditions), and analytical modeling. By combining insights obtained from these three methodologies, we provide a detailed overview on interactions between particle lifting processes due to mechanical, thermal, electrodynamical and pressure effects, and how these processes apply to dust devils on Earth and Mars. Experiments and observations have shown dust devils to be effective lifters of dust given the proper conditions on Earth and Mars. However, dust devil studies have yet to determine the individual roles of each of the component processes acting at any given time in dust devils.
Closed, nonendoscopic, small-incision forehead lift.
Marten, Timothy J
2008-07-01
As endoscopic techniques made inroads into surgery, one of the first procedures they were adapted to by plastic surgeons was the forehead lift. The "closed" forehead lift procedure has since achieved wide acceptance and exists as a viable alternative to open procedures for many patients. Experience has shown, however, that it is not necessary to use an endoscope to mobilize and release the forehead and modify the corrugator supercilii muscles in "closed" procedures if the anatomy is understood, the operation is appropriately planned, and the corrugator muscles are modified using a transpalpebral approach. In addition, transpalpebral corrugator myectomy, when used in conjunction with closed mobilization and resuspension of the forehead, provides not only a scheme for the performance of closed foreheadplasty without the need for an endoscope, but a method by which medial brow elevation can be minimized or avoided. This may, indeed, be one the procedure's most important advantages over the endoscopic technique.
Lift and drag of cetacean flippers
NASA Astrophysics Data System (ADS)
Murray, Mark; Weber, Paul; Howle, Laurens; Fish, Frank
2008-11-01
Field observation and collection of biological samples has resulted in cetacean (whales, dolphins and porpoises) flipper geometry being known for most species. However, the hydrodynamic properties of cetacean flippers have not been rigorously tested and thus their performance characteristics are unknown. Here, conducting water tunnel testing using scale models of cetacean flippers derived via computed tomography (CT) scans, as well as computational fluid dynamic (CFD) simulations, we present a baseline work to determine the hydrodynamic characteristics of cetacean flippers. We found that flippers of similar planform shape had similar hydrodynamic performance characteristics. Furthermore, one group of flippers of planform shape similar to a modern swept wing was found to have lift coefficient versus angle of attack curves that were biphasic rather than linear in nature, which was caused by the onset of vortex-dominated lift. Drag coefficient versus angle of attack curves were found to be less dependant on planform shape.