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Sample records for optimal lift force

  1. 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).

  2. Aerodynamic Lifting Force.

    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)

  3. Aerodynamic Lifting Force.

    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)

  4. Mathematical analysis of actuator forces in a scissor lift

    NASA Astrophysics Data System (ADS)

    Spackman, H.

    1994-05-01

    In 1985, NCCOSC began development of a tele-operated vehicle as part of the U.S. Marine Corps' Ground-Air Tele-Robotics Systems Program. One of the required vehicle components was a rigid, light-weight, and compact lift mechanism capable of deploying a surveillance package 10 feet above the vehicle bed. The lift mechanism that was eventually built and implemented was a 3-level scissor lift. In order to analyze the forces throughout the lift structure, a set of mathematical equations was derived. From these equations it was discovered that prudent placement of a lift's actuator can significantly reduce the forces required of the actuator and the stress levels in the adjacent scissor members. The purpose of this paper is to present the equations that were derived for analyzing the actuator forces. Using these equations, a designer can quickly determine the optimal locations for mounting an actuator and the resulting forces.

  5. Bernoulli's Law and Aerodynamic Lifting Force.

    ERIC Educational Resources Information Center

    Weltner, Klaus

    1990-01-01

    Explains the lifting force based on Bernoulli's law and as a reaction force. Discusses the interrelation of both explanations. Considers accelerations in line with stream lines and perpendicular to stream lines. (YP)

  6. Variational scheme towards an optimal lifting drive in fluid adhesion.

    PubMed

    Dias, Eduardo O; Miranda, José A

    2012-10-01

    One way of determining the adhesive strength of liquids is provided by a probe-tack test, which measures the force or energy required to pull apart two parallel flat plates separated by a thin fluid film. The vast majority of the existing theoretical and experimental works in fluid adhesion use very viscous fluids, and consider a linear drive L(t)∼Vt with constant lifting plate velocity V. This implies a given energy cost and large lifting force magnitude. One challenging question in this field pertains to what would be the optimal time-dependent drive Lopt(t) for which the adhesion energy would be minimized. We use a variational scheme to systematically search for such Lopt(t). By employing an optimal lifting drive, in addition to saving energy, we verify a significant decrease in the adhesion force peak. The effectiveness of the proposed lifting procedure is checked for both Newtonian and power-law fluids.

  7. 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.

  8. Microfluidic particle sorting utilizing inertial lift force.

    PubMed

    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.

  9. Adaptation of lift forces in object manipulation through action observation.

    PubMed

    Reichelt, Andreas F; Ash, Alyssa M; Baugh, Lee A; Johansson, Roland S; Flanagan, J Randall

    2013-07-01

    The ability to predict accurately the weights of objects is essential for skilled and dexterous manipulation. A potentially important source of information about object weight is through the observation of other people lifting objects. Here, we tested the hypothesis that when watching an actor lift an object, people naturally learn the object's weight and use this information to scale forces when they subsequently lift the object themselves. Participants repeatedly lifted an object in turn with an actor. Object weight unpredictably changed between 2 and 7 N every 5th to 9th of the actor's lifts, and the weight lifted by the participant always matched that previously lifted by the actor. Even though the participants were uninformed about the structure of the experiment, they appropriately adapted their lifting force in the first trial after a weight change. Thus, participants updated their internal representation about the object's weight, for use in action, when watching a single lift performed by the actor. This ability presumably involves the comparison of predicted and actual sensory information related to actor's actions, a comparison process that is also fundamental in action.

  10. Lifting a familiar object: visual size analysis, not memory for object weight, scales lift force.

    PubMed

    Cole, Kelly J

    2008-07-01

    The brain can accurately predict the forces needed to efficiently manipulate familiar objects in relation to mechanical properties such as weight. These predictions involve memory or some type of central representation, but visual analysis of size also yields accurate predictions of the needed fingertip forces. This raises the issue of which process (weight memory or visual size analysis) is used during everyday life when handling familiar objects. Our aim was to determine if subjects use a sensorimotor memory of weight, or a visual size analysis, to predictively set their vertical lift force when lifting a recently handled object. Two groups of subjects lifted an opaque brown bottle filled with water (470 g) during the first experimental session, and then rested for 15 min in a different room. Both groups were told that they would lift the same bottle in their next session. However, the experimental group returned to lift a slightly smaller bottle filled with water (360 g) that otherwise was identical in appearance to the first bottle. The control group returned to lift the same bottle from the first session, which was only partially filled with water so that it also weighed 360 g. At the end of the second session subjects were asked if they observed any changes between sessions, but no subject indicated awareness of a specific change. An acceleration ratio was computed by dividing the peak vertical acceleration during the first lift of the second session by the average peak acceleration of the last five lifts during the first session. This ratio was >1 for the control subjects 1.30 (SEM 0.08), indicating that they scaled their lift force for the first lift of the second session based on a memory of the (heavier) bottle from the first session. In contrast, the acceleration ratio was 0.94 (0.10) for the experimental group (P < 0.011). We conclude that the experimental group processed visual cues concerning the size of the bottle. These findings raise the

  11. The effect of a repetitive, fatiguing lifting task on horizontal ground reaction forces.

    PubMed

    Shu, Yu; Southard, Stephanie; Shin, Gwanseob; Mirka, Gary A

    2005-08-01

    There are many outdoor work environments that involve the combination of repetitive, fatiguing lifting tasks and less-than-optimal footing (muddy/slippery ground surfaces). The focus of the current research was to evaluate the effects of lifting-induced fatigue of the low back extensors on lifting kinematics and ground reaction forces. Ten participants performed a repetitive lifting task over a period of 8 minutes. As they performed this task, the ground reaction forces and whole body kinematics were captured using a force platform and magnetic motion tracking system, respectively. Fatigue was verified in this experiment by documenting a decrease in the median frequency of the bilateral erector spinae muscles (pretest-posttest). Results indicate significant (p < 0.05) increases in the magnitude of the peak anterior/posterior (increased by an average of 18.3%) and peak lateral shear forces (increased by an average of 24.3%) with increasing time into the lifting bout. These results have implications for work environments such as agriculture and construction, where poor footing conditions and requirements for considerable manual materials handling may interact to create an occupational scenario with an exceptionally high risk of a slip and fall.

  12. Anticipatory scaling of grip forces when lifting objects of everyday life.

    PubMed

    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.

  13. Calculations and experiments concerning lifting force and power in TEMPUS

    NASA Technical Reports Server (NTRS)

    Zong, J. H.; Szekely, J.; Lohofer, G.

    1993-01-01

    A critical comparison is reported between the theoretically predicted and experimentally measured values for the electromagnetic lifting force and the heating rates which may be achieved, under simulated microgravity conditions, using the TEMPUS electromagnetic levitation device. The experiments involved the suspending of a metallic sample from one arm of a recording balance, such that it was carefully positioned between the heating and the positioning coils of the levitation device. The net force exerted by the sample was measured as a function of position, the coil currents, and the nature of the sample. Some calculations are also reported regarding the power absorption by the sample. The theoretical predictions, based on the numerical solution of Maxwell's equations using the volume integral technique, were found to be in excellent agreement with the measurements. For the idealized case of a spherical sample, analytical solutions describing the lifting force were also found to agree very well with the computed results.

  14. Procedure for utilizing the lift and thrust forces of ornithopters

    NASA Technical Reports Server (NTRS)

    Bezard, C.

    1985-01-01

    This procedure is distinguished by two beating wings which together describe, in space, a succession of interlaced triangles. On these wings, whose incidence varies automatically, identical forces are exerted: simultaneous lift and thrust when they make their descent, which is inclined toward the front of the craft, and lift alone when they make their ascent, which is inclined toward the rear of the craft and follows a slide horizontal movement. A mechanical device makes these movements possible. It includes: two wings with hollow profiles, connected by a framework located above a rigid frame and attached to it by bars with joints. These bars are moved with control rods which gear down the drive force. A mechanism with elastic bands or springs automatically varies the incidence of the wings.

  15. Optimized design for sling of stand up lift

    NASA Astrophysics Data System (ADS)

    Xu, Dongfang; Wang, Yue; Cui, Tengfei; Bao, Xuelian; Duan, Xingguang

    2017-04-01

    Stand up lift is a kind of equipment that assists those with dyskinesia of legs to stand up or move. As an important part of stand up lift, sling concerns the realization of the equipment's function and the safety of users. On the basis of ergonomics theory, this thesis will design and optimize the sling to make it safer and more comfortable and meet demands of different people.

  16. Effects of asymmetric dynamic and isometric liftings on strength/force and rating of perceived exertion.

    PubMed

    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

  17. Displacement-load force-perceived weight relationships in lifting objects with power-assist

    NASA Astrophysics Data System (ADS)

    Rahman, S. M. Mizanoor; Ikeura, Ryojun; Nobe, Masaya; Sawai, Hideki

    2010-01-01

    This paper deals with the design of a 1-DOF power assist system (PAS) for lifting objects in vertical direction based on a hypothesis that pertains to operator's weight perception. We particularly studied the relationships among object's displacement, load force (vertical lifting force) and perceived weight for the objects lifted with the PAS. We also compared the load force features for power-assist-lifted objects to that for manually lifted objects for equal heaviness. Finally, we proposed using the findings to develop human-friendly PASs for lifting heavy objects in industries such as construction, military operations, manufacturing and assembly, logistics and transport, mining etc.

  18. Displacement-load force-perceived weight relationships in lifting objects with power-assist

    NASA Astrophysics Data System (ADS)

    Rahman, S. M. Mizanoor; Ikeura, Ryojun; Nobe, Masaya; Sawai, Hideki

    2009-12-01

    This paper deals with the design of a 1-DOF power assist system (PAS) for lifting objects in vertical direction based on a hypothesis that pertains to operator's weight perception. We particularly studied the relationships among object's displacement, load force (vertical lifting force) and perceived weight for the objects lifted with the PAS. We also compared the load force features for power-assist-lifted objects to that for manually lifted objects for equal heaviness. Finally, we proposed using the findings to develop human-friendly PASs for lifting heavy objects in industries such as construction, military operations, manufacturing and assembly, logistics and transport, mining etc.

  19. Biomechanical simulation of manual lifting using spacetime optimization.

    PubMed

    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.

  20. 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.

  1. Optimization-based Dynamic Human Lifting Prediction

    DTIC Science & Technology

    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

  2. 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.

  3. Prediction of peak back compressive forces as a function of lifting speed and compressive forces at lift origin and destination - a pilot study.

    PubMed

    Greenland, Kasey O; Merryweather, Andrew S; Bloswick, Donald S

    2011-09-01

    To determine the feasibility of predicting static and dynamic peak back-compressive forces based on (1) static back compressive force values at the lift origin and destination and (2) lifting speed. Ten male subjects performed symmetric mid-sagittal floor-to-shoulder, floor-to-waist, and waist-to-shoulder lifts at three different speeds (slow, medium, and fast), and with two different loads (light and heavy). Two-dimensional kinematics and kinetics were captured. Linear regression analyses were used to develop prediction equations, the amount of predictability, and significance for static and dynamic peak back-compressive forces based on a static origin and destination average (SODA) back-compressive force. Static and dynamic peak back-compressive forces were highly predicted by the SODA, with R(2) values ranging from 0.830 to 0.947. Slopes were significantly different between slow and fast lifting speeds (p < 0.05) for the dynamic peak prediction equations. The slope of the regression line for static prediction was significantly greater than one with a significant positive intercept value. SODA under-predict both static and dynamic peak back-compressive force values. Peak values are highly predictable and could be readily determined using back-compressive force assessments at the origin and destination of a lifting task. This could be valuable for enhancing job design and analysis in the workplace and for large-scale studies where a full analysis of each lifting task is not feasible.

  4. Vortex flows impart chirality-specific lift forces

    NASA Astrophysics Data System (ADS)

    Hermans, Thomas M.; Bishop, Kyle J. M.; Stewart, Peter S.; Davis, Stephen H.; Grzybowski, Bartosz A.

    2015-01-01

    Recent reports that macroscopic vortex flows can discriminate between chiral molecules or their assemblies sparked considerable scientific interest both for their implications to separations technologies and for their relevance to the origins of biological homochirality. However, these earlier results are inconclusive due to questions arising from instrumental artifacts and/or insufficient experimental control. After a decade of controversy, the question remains unresolved—how do vortex flows interact with different stereoisomers? Here, we implement a model experimental system to show that chiral objects in a Taylor-Couette cell experience a chirality-specific lift force. This force is directed parallel to the shear plane in contrast to previous studies in which helices, bacteria and chiral cubes experience chirality-specific forces perpendicular to the shear plane. We present a quantitative hydrodynamic model that explains how chirality-specific motions arise in non-linear shear flows through the interplay between the shear-induced rotation of the particle and its orbital translation. The scaling laws derived here suggest that rotating flows can be used to achieve chiral separation at the micro- and nanoscales.

  5. Analysis of squat and stoop dynamic liftings: muscle forces and internal spinal loads

    PubMed Central

    Bazrgari, Babak; Arjmand, Navid

    2006-01-01

    Despite the well-recognized role of lifting in back injuries, the relative biomechanical merits of squat versus stoop lifting remain controversial. In vivo kinematics measurements and model studies are combined to estimate trunk muscle forces and internal spinal loads under dynamic squat and stoop lifts with and without load in hands. Measurements were performed on healthy subjects to collect segmental rotations during lifts needed as input data in subsequent model studies. The model accounted for nonlinear properties of the ligamentous spine, wrapping of thoracic extensor muscles to take curved paths in flexion and trunk dynamic characteristics (inertia and damping) while subject to measured kinematics and gravity/external loads. A dynamic kinematics-driven approach was employed accounting for the spinal synergy by simultaneous consideration of passive structures and muscle forces under given posture and loads. Results satisfied kinematics and dynamic equilibrium conditions at all levels and directions. Net moments, muscle forces at different levels, passive (muscle or ligamentous) forces and internal compression/shear forces were larger in stoop lifts than in squat ones. These were due to significantly larger thorax, lumbar and pelvis rotations in stoop lifts. For the relatively slow lifting tasks performed in this study with the lowering and lifting phases each lasting ∼2 s, the effect of inertia and damping was not, in general, important. Moreover, posterior shift in the position of the external load in stoop lift reaching the same lever arm with respect to the S1 as that in squat lift did not influence the conclusion of this study on the merits of squat lifts over stoop ones. Results, for the tasks considered, advocate squat lifting over stoop lifting as the technique of choice in reducing net moments, muscle forces and internal spinal loads (i.e., moment, compression and shear force). PMID:17103232

  6. Analysis of squat and stoop dynamic liftings: muscle forces and internal spinal loads.

    PubMed

    Bazrgari, Babak; Shirazi-Adl, Aboulfazl; Arjmand, Navid

    2007-05-01

    Despite the well-recognized role of lifting in back injuries, the relative biomechanical merits of squat versus stoop lifting remain controversial. In vivo kinematics measurements and model studies are combined to estimate trunk muscle forces and internal spinal loads under dynamic squat and stoop lifts with and without load in hands. Measurements were performed on healthy subjects to collect segmental rotations during lifts needed as input data in subsequent model studies. The model accounted for nonlinear properties of the ligamentous spine, wrapping of thoracic extensor muscles to take curved paths in flexion and trunk dynamic characteristics (inertia and damping) while subject to measured kinematics and gravity/external loads. A dynamic kinematics-driven approach was employed accounting for the spinal synergy by simultaneous consideration of passive structures and muscle forces under given posture and loads. Results satisfied kinematics and dynamic equilibrium conditions at all levels and directions. Net moments, muscle forces at different levels, passive (muscle or ligamentous) forces and internal compression/shear forces were larger in stoop lifts than in squat ones. These were due to significantly larger thorax, lumbar and pelvis rotations in stoop lifts. For the relatively slow lifting tasks performed in this study with the lowering and lifting phases each lasting approximately 2 s, the effect of inertia and damping was not, in general, important. Moreover, posterior shift in the position of the external load in stoop lift reaching the same lever arm with respect to the S1 as that in squat lift did not influence the conclusion of this study on the merits of squat lifts over stoop ones. Results, for the tasks considered, advocate squat lifting over stoop lifting as the technique of choice in reducing net moments, muscle forces and internal spinal loads (i.e., moment, compression and shear force).

  7. The magnitude of lift forces acting on drops and bubbles in liquids flowing inside microchannels.

    PubMed

    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.

  8. The lift forces acting on a submarine composite pipeline in a wave-current coexisting field

    SciTech Connect

    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.

  9. The control of flight force by a flapping wing: lift and drag production.

    PubMed

    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

  10. Lift-Force-Driven Microfluidic Droplet Sorting Device

    NASA Astrophysics Data System (ADS)

    Nieuwstadt, Harm; Li, David; Seda, Robinson; Fowlkes, J. Brian; Bull, Joseph

    2009-11-01

    A long (˜ 5-7 centimeters) rectangular micro channel is used to sort perfluorcarbon (PFC) droplets by size.This study is motivated by a novel gas embolotherapy technique which aims to treat cancer by infarcting tumors with gas emboli that are formed by selective acoustic vaporization of ˜6 micrometer, intravascular, PFC droplets. Droplets smaller and larger than ˜6-micrometer proved to be less effective, or even detrimental, in the gas embolotherapy. From a suspension of micro PFC droplets, the sorting device designed in this study eliminates droplets with higher and lower diameters than ˜6-micrometer. This is done by the use of a difference in lateral lift force (which depends on droplet diameter) that is exerted on the droplets. When a mixture of droplets is introduced at the entrance of a straight micro channel, larger droplets will tend to move to an equilibrium position at 0.6R, R being the half width of the channel, in shorter time and distance than smaller droplets. When splitting up the end of the channel in two smaller outer channels (which contain the large droplets) and one smaller inner channel (which contains the small droplets), the droplets can, in theory, be sorted with high accuracy. This work is supported by NIH grant R01EB006476.

  11. Measuring lifting forces in rock climbing: effect of hold size and fingertip structure.

    PubMed

    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.

  12. Prediction of Peak Back Compressive Forces as a Function of Lifting Speed and Compressive Forces at Lift Origin and Destination - A Pilot Study

    PubMed Central

    Greenland, Kasey O; Merryweather, Andrew S

    2011-01-01

    Objectives To determine the feasibility of predicting static and dynamic peak back-compressive forces based on (1) static back compressive force values at the lift origin and destination and (2) lifting speed. Methods Ten male subjects performed symmetric mid-sagittal floor-to-shoulder, floor-to-waist, and waist-to-shoulder lifts at three different speeds (slow, medium, and fast), and with two different loads (light and heavy). Two-dimensional kinematics and kinetics were captured. Linear regression analyses were used to develop prediction equations, the amount of predictability, and significance for static and dynamic peak back-compressive forces based on a static origin and destination average (SODA) back-compressive force. Results Static and dynamic peak back-compressive forces were highly predicted by the SODA, with R2 values ranging from 0.830 to 0.947. Slopes were significantly different between slow and fast lifting speeds (p < 0.05) for the dynamic peak prediction equations. The slope of the regression line for static prediction was significantly greater than one with a significant positive intercept value. Conclusion SODA under-predict both static and dynamic peak back-compressive force values. Peak values are highly predictable and could be readily determined using back-compressive force assessments at the origin and destination of a lifting task. This could be valuable for enhancing job design and analysis in the workplace and for large-scale studies where a full analysis of each lifting task is not feasible. PMID:22953207

  13. 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.

  14. Changes in Back Compressive Force When Measuring Maximum Acceptable Weight of Lift in Iranian Male Students

    PubMed Central

    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

  15. Changes in Back Compressive Force When Measuring Maximum Acceptable Weight of Lift in Iranian Male Students.

    PubMed

    Salehi Sahl Abadi, Ali; Nasl Saraji, Gebraeil; Mazloumi, Adel; Zeraati, Hojjat; Hadian, Mohammad Reza; Jafari, Amir Homayoun

    2016-09-01

    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. 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. 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). BCF is affected by box size, lifting frequency and weight of load.

  16. Sensorimotor memory for fingertip forces during object lifting: the role of the primary motor cortex.

    PubMed

    Berner, Julia; Schönfeldt-Lecuona, Carlos; Nowak, Dennis A

    2007-04-09

    When an object is repetitively lifted, the scaling of grip force is influenced by the mechanical properties of the preceding lift, suggesting the formation of a sensorimotor memory. Similar effects on force scaling are observed when the subsequent lift is performed with the hand opposite to the preceding lift. We used neuronavigated rTMS over the hand area of the dominant primary motor cortex to investigate its role in setting up sensorimotor memory. After ten lifts of a novel object with the dominant hand either rTMS or a period of motor rest commenced, until another set of lifts was performed with either the same or opposite hand. Compared to motor rest, rTMS caused underestimation of the object's weight when given 10 or 30s after the previous set of lifts, but overestimation of the object's weight when applied 60 or 120 s after the previous set of lifts, regardless of the hand performing the lift. Our interpretation of the data is that (a) the primary motor cortex is essential for setting up sensorimotor memory related to the mechanical object properties during manipulation and (b) rTMS can induce bidirectional changes of grip efficiency within the dynamics of sensorimotor integration.

  17. Evaluation of postural sway and impact forces during ingress and egress of scissor lifts at elevations.

    PubMed

    Pan, Christopher S; Chiou, Sharon S; Kau, Tsui-Ying; Wimer, Bryan M; Ning, Xiaopeng; Keane, Paul

    2017-11-01

    Workers are at risk when entering (ingress) or exiting (egress) elevated scissor lifts. In this study, we recorded ground impact forces and postural sway from 22 construction workers while they performed ingress and egress between a scissor lift and an adjacent work surface with varying conditions: lift opening designs, horizontal and vertical gaps, and sloped work surfaces. We observed higher peak ground shear forces when using a bar-and-chain opening, with larger horizontal gap, with the lift surface more than 0.2 m below the work surface, and presence of a sloped (26°) work surface. Similar trends were observed for postural sway, except that the influence of vertical distance was not significant. To reduce slip/trip/fall risk and postural sway of workers while ingress or egress of an elevated scissor lift, we suggest scissor lifts be equipped with a gate-type opening instead of a bar-and-chain design. We also suggest the lift surface be placed no more than 0.2 m lower than the work surface and the horizontal gap between lift and work surfaces be as small as possible. Selecting a non-sloped surface to ingress or egress a scissor lift is also preferred to reduce risk. Published by Elsevier Ltd.

  18. 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.

  19. 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

  20. Lumbar compression forces while lifting and carrying with two and four workers.

    PubMed

    Visser, Steven; Faber, Gert S; Hoozemans, Marco J M; van der Molen, Henk F; Kuijer, P Paul F M; Frings-Dresen, Monique H W; van Dieën, Jaap H

    2015-09-01

    Team lifting and carrying is advised when loads exceed 25 kg and mechanical lifting is not feasible. The aim of this study was to assess mean, maximum and variability of peak lumbar compression forces which occur daily at construction sites. Therefore, 12 ironworkers performed 50-kg two-worker and 100-kg four-worker lifting and carrying tasks in a laboratory experiment. The 50-kg two-worker lifts resulted in significantly higher mean (Δ 537 N) and maximum (Δ 586 N) peak lumbar compression forces compared with the 100-kg four-worker lifts. The lowest mean and maximum peak lumbar compression forces were found while carrying on level ground and increased significantly when stepping over obstacles and up platforms. Lifting 100 kg with four workers in a rectangular line up resulted in lower compression forces compared with lifting 50 kg with two workers standing next to each other. When loads are carried manually routes should be free of any obstacles to be overcome. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  1. 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.

  2. Optimizing Security Force Generation

    DTIC Science & Technology

    2009-06-01

    for Operations Research Branch and Cut ELIM-COMPLIM Enlisted Loss Inventory Model –Computation of Manpower Programs using Linear Programs...growth: cohort and 12 renewal. Vadja (1978) discusses the growth of organizations using a cohort model and Markovian transition matrices. Members... model the growth of the force used the Enlisted Loss Inventory Model —Computation of Manpower Programs using Linear Programs (ELIM-COMPLIM). ELIM

  3. Injuries to air force personnel associated with lifting, handling, and carrying objects.

    PubMed

    Kemp, Philip A; Burnham, Bruce R; Copley, G Bruce; Shim, Matthew J

    2010-01-01

    The U.S. Air Force (USAF) active duty and civilian populations experience a substantial number of lost-workday injuries while lifting, handling, and carrying objects. Back injuries are most frequently reported. The purpose of this study is to describe the hazard scenarios of lift-handle-carry injuries to better identify effective countermeasures. The data were derived from safety reports obtained from the USAF Ground Safety Automated System. Lift-handle-carry injuries for the years 1993-2002 that resulted in at least one lost workday were included in the study. A total of 4085 lost-workday injuries resulting in 24,940 lost workdays for USAF military and civilian members met the criteria for inclusion. Objects associated with these injuries were identified and aggregated to determine the most common causes of lift-handle-carry injuries. Twelve distinct objects or type of objects were identified as the most common source of lift-handle-carry injuries. Among the most common sources of injury were lifting aircraft components, boxes, and furniture. Most importantly, lifting one group of objects, aircraft components, was associated with 33% of all lift-handle-carry injuries. Safety report data can be used to identify the most common object or object types causing lift-handle-carry injuries. The information included in this report suggests countermeasures that should be considered for implementation and evaluation studies. Countermeasures to address the most common lift-handle-carry injuries, such as lifting aircraft components among aircraft maintenance workers, are warranted. Published by Elsevier Inc.

  4. Force Method Optimization.

    DTIC Science & Technology

    1980-02-01

    The resulting problem is non-linear, but the use of a linear programming stage is effective in DD IO 1473 EDITION oF I NOV GSIS OSOLETE UNCLASSIFIED...programming techniques reached what was effectively a computational stalemate, the development of optimality criteria methods(’) in the early 70’s appeared to...constraints. In addition, the incorporation of stress and fabricational constraints is effectively based upon the FSD method. Work has been carried on by a

  5. Wind tunnel investigation of rotor lift and propulsive force at high speed: Data analysis

    NASA Technical Reports Server (NTRS)

    Mchugh, F.; Clark, R.; Soloman, M.

    1977-01-01

    The basic test data obtained during the lift-propulsive force limit wind tunnel test conducted on a scale model CH-47b rotor are analyzed. Included are the rotor control positions, blade loads and six components of rotor force and moment, corrected for hub tares. Performance and blade loads are presented as the rotor lift limit is approached at fixed levels of rotor propulsive force coefficients and rotor tip speeds. Performance and blade load trends are documented for fixed levels of rotor lift coefficient as propulsive force is increased to the maximum obtainable by the model rotor. Test data is also included that defines the effect of stall proximity on rotor control power. The basic test data plots are presented in volumes 2 and 3.

  6. Chirality-specific lift forces of helix under shear flows: Helix perpendicular to shear plane.

    PubMed

    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.

  7. 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.

  8. 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.

  9. Independent control of human finger-tip forces at individual digits during precision lifting.

    PubMed Central

    Edin, B B; Westling, G; Johansson, R S

    1992-01-01

    1. Subjects lifted an object with two parallel vertical grip surfaces and a low centre of gravity using the precision grip between the tips of the thumb and index finger. The friction between the object and the digits was varied independently at each digit by changing the contact surfaces between lifts. 2. With equal frictional conditions at the two grip surfaces, the finger-tip forces were about equal at the two digits, i.e. similar vertical lifting forces and grip forces were used. With different frictions, the digit touching the most slippery surface exerted less vertical lifting force than the digit in contact with the rougher surface. Thus, the safety margins against slips were similar at the two digits whether they made contact with surfaces of similar or different friction. 3. During digital nerve block, large and variable safety margins were employed, i.e. the finger-tip forces did not reflect the surface conditions. Slips occurred more frequently than under normal conditions (14% of all trials with nerve block, <5% during normal conditions), and they only occasionally elicited compensatory adjustments of the finger-tip forces and then at prolonged latencies. 4. The partitioning of the vertical lifting force between the digits was thus dependent on digital afferent inputs and resulted from active automatic regulation and not just from the mechanics of the task. 5. The safety margin employed at a particular digit was mainly determined by the frictional conditions encountered by the digit, and to a lesser degree by the surface condition at the same digit in the previous lift (anticipatory control), but was barely influenced by the surface condition at the other digit. 6. It was concluded that the finger-tip forces were independently controlled for each digit according to a 'non-slip strategy'. The findings suggest that the force distribution among the digits represents a digit-specific lower-level neural control establishing a stable grasp. This control

  10. The role of back muscle endurance, maximum force, balance and trunk rotation control regarding lifting capacity.

    PubMed

    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

  11. 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.

  12. Force requirements of observed object lifting are encoded by the observer's motor system: a TMS study.

    PubMed

    Alaerts, Kaat; Senot, Patrice; Swinnen, Stephan P; Craighero, Laila; Wenderoth, Nicole; Fadiga, Luciano

    2010-03-01

    Several transcranial magnetic stimulation (TMS) studies have reported facilitation of the primary motor cortex (M1) during the mere observation of actions. This facilitation was shown to be highly congruent, in terms of somatotopy, with the observed action, even at the level of single muscles. With the present study, we investigated whether this muscle-specific facilitation of the observer's motor system reflects the degree of muscular force that is exerted in an observed action. Two separate TMS experiments are reported in which corticospinal excitability was measured in the hand area of M1 while subjects observed the lifting of objects of different weights. The type of action 'grasping-and-lifting-the-object' was always identical, but the grip force varied according to the object's weight. In accordance to previous findings, excitability of M1 was shown to modulate in a muscle-specific way, such that only the cortical representation areas in M1 that control the specific muscles used in the observed lifting action became increasingly facilitated. Moreover, muscle-specific M1 facilitation was shown to modulate to the force requirements of the observed actions, such that M1 excitability was considerably higher when observing heavy object lifting compared with light object lifting. Overall, these results indicate that different levels of observed grip force are mirrored onto the observer's motor system in a highly muscle-specific manner. The measured force-dependent modulations of corticospinal excitability in M1 are hypothesized to be functionally relevant for scaling the observed grip force in the observer's own motor system. In turn, this mechanism may contribute, at least partly, to the observer's ability to infer the weight of the lifted object.

  13. Force measurements of postural sway and rapid arm lift in seated children with and without MMC.

    PubMed

    Norrlin, Simone; Karlsson, Annica; Ahlsten, Gunnar; Lanshammar, Håkan; Silander, Hans C; Dahl, Margareta

    2002-03-01

    The aim was to investigate the horizontal ground reaction forces of seated postural sway and rapid arm lift in children with and without myelomeningocele. BACKGROUND; It is unclear whether children with myelomeningocele have limited control of body posture entirely caused by the impairment in the legs or also by other dysfunction. 11 children with myelomeningocele, 10-13 years, and 20 children without physical impairment were investigated. Data were collected by force plate measurements during quiet sitting and during rapid arm lift. The forces were expressed as the corresponding acceleration of the centre of mass. The amplitude and the frequency of the centre of mass acceleration quantified the sway. Movement time, onset and anteroposterior peak acceleration were analysed during arm lift. The children with myelomeningocele had a low sway frequency under both conditions: eyes open and eyes closed. The movement time was longer for these children compared to the controls. The onset of initial anteroposterior centre of mass acceleration preceded the arm lift and was directed forward in both groups. The peak centre of mass acceleration was usually directed backward. The control of postural sway was different in children with myelomeningocele compared to children without disabilities and this could not be explained by the cele level. The children with myelomeningocele had a slow motor performance of the seated sway and during arm lift. Slow motor performance involves functional limitations in the individual child and is important for the therapy program.

  14. Lift vs. drag based mechanisms for vertical force production in the smallest flying insects.

    PubMed

    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.

  15. Lift force on an asymmetrical obstacle immersed in a dilute granular flow.

    PubMed

    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.

  16. Influence of the saffman force, lift force, and electric force on sand grain transport in a wind-sand flow

    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.

  17. Weight Lift Capabilities of Air Force Basic Trainees

    DTIC Science & Technology

    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

  18. 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

  19. 3D hydrodynamic lift force model for AREVA fuel assembly in EDF PWRs

    SciTech Connect

    Ekomie, S.; Bigot, J.; Dolleans, Ph.; Vallory, J.

    2007-07-01

    The accurate knowledge of the hydrodynamic lift force acting on a fuel assembly in PWR core is necessary to design the hold-down system of this assembly. This paper presents the model used by AREVA NP and EDF for computing this force. It results from a post-processing of sub-channel thermal-hydraulic codes respectively porous medium approach code THYC (EDF) and sub-channel type code FLICA III-F (AREVA NP). This model is based on the application of the Euler's theorem. Some hypotheses used to simplify the complexity of fuel assembly geometry are supported by CFD calculations. Then the model is compared to some experimental results obtained on a single fuel assembly inserted in the HERMES-T test facility located in CEA - Cadarache. Finally, the model is applied to calculate the lift force for the whole core. Various loading patterns including homogenous and mixed cores have been investigated and compared. (authors)

  20. Impact of Airfoils on Aerodynamic Optimization of Heavy Lift Rotorcraft

    DTIC Science & Technology

    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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Role of the primary motor and dorsal premotor cortices in the anticipation of forces during object lifting.

    PubMed

    Chouinard, Philippe A; Leonard, Gabriel; Paus, Tomás

    2005-03-02

    When lifting small objects, people apply forces that match the expected weight of the object. This expectation relies in part on information acquired during a previous lift and on associating a certain weight with a particular object. Our study examined the role of the primary motor and dorsal premotor cortices in predicting weight based either on information acquired during a previous lift (no-cue experiment) or on arbitrary color cues associated with a particular weight (cue experiment). In the two experiments, subjects used precision grip to lift two different weights in a series of trials both before and after we applied low-frequency repetitive transcranial magnetic stimulation over the primary motor and dorsal premotor cortices. In the no-cue experiment, subjects did not receive any previous information about which of two weights they would have to lift. In the cue experiment, a color cue provided information about which of the two weights subjects would have to lift. Our results demonstrate a double dissociation in the effects induced by repetitive stimulation. When applied over the primary motor cortex, repetitive stimulation disrupted the scaling of forces based on information acquired during a previous lift. In contrast, when applied over the dorsal premotor cortex, repetitive stimulation disrupted the scaling of forces based on arbitrary color cues. We conclude that the primary motor and dorsal premotor cortices have unique roles during the anticipatory scaling of forces associated with the lifting of different weights.

  6. 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.

  7. The impact of unilateral brain damage on anticipatory grip force scaling when lifting everyday objects.

    PubMed

    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

  8. Of Helicopters and Doctrine: A Study of the SOF (Special Operations Forces) Rotary Wing Lift Transfer

    DTIC Science & Technology

    1989-03-01

    AD-A217 615 AIR WAR COLLEGE RESEARCH REPORT ’J OF HELICOPTERS AND DOCTRINE: A STUDY OF THE 00 SOF ROTARY WING LIFT TRANSFER 0 LIEUTENANT COLONEL...KENNETH R. PRIBYLA IDTIC S1989SB AtIR UNIV~MISrr fff4 I UNITED STATE8 AIR FORCE Sam&wa& MAXWELL AIR FORCE BASE. ALABAMA AIR WAR COLLEGE AIR UNIVERSITY OF...This study represents the views of the author and does not necessarily reflect the official opinion of the Air War College ir the Department of the Air

  9. Sharp Transition in the Lift Force of a Fluid Flowing Past Nonsymmetrical Obstacles: Evidence for a Lift Crisis in the Drag Crisis Regime.

    PubMed

    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.

  10. 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.

  11. Effects of different lifting cadences on ground reaction forces during the squat exercise.

    PubMed

    Bentley, Jason R; Amonette, William E; De Witt, John K; Hagan, R Donald

    2010-05-01

    The purpose of this investigation was to determine the effect of different lifting cadences on the ground reaction force (GRF) during the squat exercise. Squats performed with greater acceleration will produce greater inertial forces; however, it is not well understood how different squat cadences affect GRF. The hypotheses were that faster squat cadences would result in greater peak GRF and that the contributions of the body and barbell, both of equivalent mass, to total system inertial force would not be different. Six experienced male subjects (31 +/- 4 years, 180 +/- 9 cm, 88.8 +/- 13.3 kg) performed 3 sets of 3 squats using 3 different cadences (fast cadence [FC] = 1-second descent/1-second ascent; medium cadence [MC] = 3-second descent/1-second ascent; and slow cadence [SC] = 4-second descent/2-second ascent) while lifting a barbell mass equal to their body mass. Ground reaction force and velocity sensor data were used to calculate inertial force contributions of both the body and barbell to total inertial force. Peak GRF were significantly higher in FC squats compared to MC (p = 0.0002) and SC (p = 0.0002). Ranges of GRF were also significantly higher in FC compared to MC (p < 0.05) and higher in MC compared to SC (p < 0.05). The inertial forces associated with the body were larger than those associated with the barbell, regardless of cadence. Faster squat cadences result in significantly greater peak GRF as a result of the inertia of the system. This study demonstrates that GRF was more dependent on descent cadence than on ascent cadence and that researchers should not use a single point on the body to approximate the location of the center of mass during squat exercise analysis.

  12. 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.

  13. Coupled objective function to study the role of abdominal muscle forces in lifting using the kinematics-driven model.

    PubMed

    El Ouaaid, Z; Shirazi-Adl, A; Arjmand, N; Plamondon, A

    2013-01-01

    To circumvent the existing shortcoming of optimisation algorithms in trunk biomechanical models, both agonist and antagonist trunk muscle stresses to different powers are introduced in a novel objective function to evaluate the role of abdominal muscles in trunk stability and spine compression. This coupled objective function is introduced in our kinematics-driven finite element model to estimate muscle forces and to identify the role of abdominal muscles in upright standing while lifting symmetrically a weight at different heights. Predictive equations for the compression and buckling forces are developed. Results are also compared with the conventional objective function that neglects abdominal muscle forces. An overall optimal solution involving smaller spinal compression but higher trunk stability is automatically attained when choosing muscle stress powers at and around 3. Results highlight the internal oblique muscle as the most efficient abdominal muscle during the tasks investigated. The estimated relative forces in abdominal muscles are found to be in good agreement with the respective ratios of recorded electromyography activities.

  14. 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.

  15. Roll Damping Derivatives from Generalized Lifting-Surface Theory and Wind Tunnel Forced-Oscillation Tests

    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.

  16. Continuous focusing of microparticles using inertial lift force and vorticity via multi-orifice microfluidic channels.

    PubMed

    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.

  17. Dynamic Calibration and Validation of an Accelerometer Force Balance for Hypersonic Lifting Models

    PubMed Central

    Singh, Prakash; Trivedi, Sharad

    2014-01-01

    An accelerometer-based force balance was designed and developed for the measurement of drag, lift, and rolling moment on a blunt-nosed, flapped delta wing in a short-duration hypersonic shock tunnel. Calibration and validation of the balance were carried out by a convolution technique using hammer pulse test and surface pressure measurements. In the hammer pulse test, a known impulse was applied to the model in the appropriate direction using an impulse hammer, and the corresponding output of the balance (acceleration) was recorded. Fast Fourier Transform (FFT) was operated on the output of the balance to generate a system response function, relating the signal output to the corresponding load input. Impulse response functions for three components of the balance, namely, axial, normal, and angular, were obtained for a range of input load. The angular system response function was corresponding to rolling of the model. The impulse response functions thus obtained, through dynamic calibration, were operated on the output (signals) of the balance under hypersonic aerodynamic loading conditions in the tunnel to get the time history of the unknown aerodynamic forces and moments acting on the model. Surface pressure measurements were carried out on the model using high frequency pressure transducers, and forces and moments were deduced thereon. Tests were carried out at model angles of incidence of 0, 5, 10, and 15 degrees. A good agreement was observed among the results of different experimental methods. The balance developed is a comprehensive force/moment measurement device that can be used on complex, lifting, aerodynamic geometries in ground-based hypersonic test facilities. PMID:24574921

  18. Dynamic calibration and validation of an accelerometer force balance for hypersonic lifting models.

    PubMed

    Singh, Prakash; Trivedi, Sharad; Menezes, Viren; Hosseini, Hamid

    2014-01-01

    An accelerometer-based force balance was designed and developed for the measurement of drag, lift, and rolling moment on a blunt-nosed, flapped delta wing in a short-duration hypersonic shock tunnel. Calibration and validation of the balance were carried out by a convolution technique using hammer pulse test and surface pressure measurements. In the hammer pulse test, a known impulse was applied to the model in the appropriate direction using an impulse hammer, and the corresponding output of the balance (acceleration) was recorded. Fast Fourier Transform (FFT) was operated on the output of the balance to generate a system response function, relating the signal output to the corresponding load input. Impulse response functions for three components of the balance, namely, axial, normal, and angular, were obtained for a range of input load. The angular system response function was corresponding to rolling of the model. The impulse response functions thus obtained, through dynamic calibration, were operated on the output (signals) of the balance under hypersonic aerodynamic loading conditions in the tunnel to get the time history of the unknown aerodynamic forces and moments acting on the model. Surface pressure measurements were carried out on the model using high frequency pressure transducers, and forces and moments were deduced thereon. Tests were carried out at model angles of incidence of 0, 5, 10, and 15 degrees. A good agreement was observed among the results of different experimental methods. The balance developed is a comprehensive force/moment measurement device that can be used on complex, lifting, aerodynamic geometries in ground-based hypersonic test facilities.

  19. Force optimized recoil control system

    NASA Astrophysics Data System (ADS)

    Townsend, P. E.; Radkiewicz, R. J.; Gartner, R. F.

    1982-05-01

    Reduction of the recoil force of high rate of fire automatic guns was proven effective. This system will allow consideration of more powerful guns for use in both helicopter and armored personnel carrier applications. By substituting the large shock loads of firing guns with a nearly constant force, both vibration and fatigue problems that prevent mounting of powerful automatic guns is eliminated.

  20. Fingertip force control during bimanual object lifting in hemiplegic cerebral palsy

    PubMed Central

    Charles, Jeanne; Gordon, Andrew M.

    2008-01-01

    In the present study we examined unimanual and bimanual fingertip force control during grasping in children with hemiplegic cerebral palsy (CP). Participants lifted, transported and released an object with one hand or both hands together in order to examine the effect on fingertip force control for each hand separately and to determine whether any benefit exists for the affected hand when it performed the task concurrently with the less-affected hand. Seven children with hemiplegic CP performed the task while their movement and fingertip force control were measured. In the bimanual conditions, the weight of the instrumented objects was equal or unequal. The durations of the all temporal phases for the less-affected hand were prolonged during bimanual control compared to unimanual control. We observed close synchrony of both hands when the task was performed with both hands, despite large differences in duration between both hands when they performed separately. There was a marginal benefit for two of the five force related variables for the affected hand (grip force at onset of load force, and peak grip force) when it transported the object simultaneously with the less-affected hand. Collectively, these results corroborate earlier findings of reaching studies that showed slowing down of the less-affected hand when it moved together with the affected hand. A new finding that extends these studies is that bimanual tasks may have the potential to facilitate force control of the affected hand. The implications of these findings for recent rehabilitative therapies in children with CP that make use of bimanual training are discussed. PMID:18224309

  1. Optimization of ski jumper's posture considering lift-to-drag ratio and stability.

    PubMed

    Lee, Ki-Don; Park, Min-Jung; Kim, Kwang-Yong

    2012-08-09

    An optimization analysis of a ski jumper's posture has been performed to improve the lift-to-drag ratio, and to examine aerodynamic stability to ensure flight control and safety. Three-dimensional Reynolds-averaged Navier-Stokes equations were discretized using finite volume approximations for the flow analysis, and the shear stress transport k-ω turbulence model was used for a turbulence closure. The Airfoil theory and principles of aircraft stability were used to examine the stability mechanism. Two ski jumper posture angles were chosen as design variables through a preliminary test, and the lift-to-drag ratio was used as an objective function for the optimization problem. Thirteen design points within design spaces are selected by Latin hypercube sampling. In order to predict the objective function values in the design space, the Kriging model was constructed using the numerical results on the design points. By the sequential quadratic programming, the optimal point was found from the constructed the Kriging model. The Kriging model predicted the objective function value at the optimum point with a 1.1% error compared to the value obtained by numerical analysis. The optimum design showed a considerable lift-to-drag ratio improvement compared to the reference design. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Observing how others lift light or heavy objects: time-dependent encoding of grip force in the primary motor cortex.

    PubMed

    Alaerts, Kaat; de Beukelaar, Toon T; Swinnen, Stephan P; Wenderoth, Nicole

    2012-07-01

    During movement observation, corticomotor excitability of the observer's primary motor cortex (M1) is modulated according to the force requirements of the observed action. Here, we explored the time course of observation-induced force encoding. Force-related changes in M1-excitability were assessed by delivering transcranial magnetic stimulations at distinct temporal phases of an observed reach-grasp-lift action. Temporal changes in force-related electromyographic activity were also assessed during active movement execution. In observation conditions in which a heavy object was lifted, M1-excitability was higher compared to conditions in which a light object was lifted. Both during observation and execution, differential force encoding tended to gradually increase from the grasping phase until the late lift phase. Surprisingly, however, during observation, force encoding was already present at the early reach phase: a time point at which no visual cues on the object's weight were available to the observer. As the observer was aware that the same weight condition was presented repeatedly, this finding may indicate that prior predictions concerning the upcoming weight condition are reflected by M1 excitability. Overall, findings may provide indications that the observer's motor system represents motor predictions as well as muscular requirements to infer the observed movement goal.

  3. 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.

  4. WORK FORCE OPTIMIZATION FOR 2025

    DTIC Science & Technology

    2016-02-08

    assigned duties and are not strong predictors of successful physical performance on the battlefield or in full spectrum operations.38 In 2011, the Army...Optimizing Human Performance . White Paper, Fort Leavenworth: United States Army Combined Arms Center. pg 14. 21 United States Army TRADOC. 2015. Civilian...Center. 2014. A Framework for Optimizing Human Performance . White Paper, Fort Leavenworth: United States Army Combined Arms Center. United States

  5. 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.

  6. Modulation of rotation-induced lift force for cell filtration in a low aspect ratio microchannel

    PubMed Central

    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

  7. 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.

  8. Optimization of a variable-stiffness skin for morphing high-lift devices

    NASA Astrophysics Data System (ADS)

    Thuwis, G. A. A.; Abdalla, M. M.; Gürdal, Z.

    2010-12-01

    One of the possibilities for the next generation of smart high-lift devices is to use a seamless morphing structure. A passive composite variable-stiffness skin as a solution to the dilemma of designing the structure to have high enough stiffness to withstand aerodynamic loading and low stiffness to enable morphing is proposed. The variable-stiffness skin is achieved by allowing for a spatial fibre angle and skin thickness variation on a morphing high-lift system. The stiffness distribution is tailored to influence the deformation of the structure beneficially. To design a realistic stiffness distribution, it is important to take aerodynamic and actuation loads into account during the optimization. A two-dimensional aero-servo-elastic framework is created for this purpose. Skin optimization is performed using a gradient-based optimizer, where sensitivity information is found through application of the adjoint method. The implementation of the aero-servo-elastic environment is addressed and initial optimization results presented. The results indicate that a variable-stiffness skin increases the design space. Moreover, the importance of taking the change in aerodynamic loads due to morphing skin deformation into account during optimization is demonstrated.

  9. Relation of the Vector Force Needed to Lift the Upper Eyelids and the Degree of Exophthalmos.

    PubMed

    Hwang, Kun; Kim, Joo Ho; Kim, Hun; Hwang, Se Won

    2015-07-01

    The aim of this study was to determine the relation of the vector force needed to lift the upper eyelids and the degree of exophthalmos (EX). In the 109 magnetic resonance imaging films, the degree of EX (the shortest distance from the cornea to the line connecting both lateral orbital rims), the anterior angle (θ, an angle formed from the lower margin of the upper eyelid-superior transverse ligament (STL)--with a parallel line connecting the supraorbital rim and the infraorbital rim in the sagittal film), the length from the STL to the upper eyelid margin (levator length [LL]), the thickness of the STL (WT), and the thickness the of levator palpebrae (LT) were measured.The average EX was 14.5 ± 2.35  mm. The average θ was 33.84 ± 2.15 degrees. The vector force needed to lift the upper eyelids (cos θ) was 0.83. The average LL was 21.0 ± 1.54  mm. The average WT was 1.07 ± 0.22  mm. The average LT was 1.69 ± 0.30  mm. There was a significant positive relationship between the EX and age (P = 0.022). The EX in those younger than 20 years (12.8 ± 2.06) was significantly lesser than that of the other age groups. There was no significant relationship between the EX and cos θ. However, there was a significant positive relationship between the EX and the LL. There was a significant positive relationship between LL and LT, and between LL and WT.The farther the eyeball protrudes, the longer the LL is needed. The longer the LL is, the thicker the levator muscle and STL.

  10. Relation Between Lift Force and Ball Spin for Different Baseball Pitches.

    PubMed

    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.

  11. 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 optimization of the lift distribution across the wing of an aircraft in formation flight. The usual elliptical distribution is no longer optimal for the trailing wing in the 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 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.

  12. Predictive force programming in the grip-lift task: the role of memory links between arbitrary cues and object weight.

    PubMed

    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.

  13. 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.

  14. External Hand Forces Exerted by Long-Term Care Staff to Push Floor-Based Lifts: Effects of Flooring System and Resident Weight.

    PubMed

    Lachance, Chantelle C; Korall, Alexandra M B; Russell, Colin M; Feldman, Fabio; Robinovitch, Stephen N; Mackey, Dawn C

    2016-09-01

    The aim of this study was to investigate the effects of flooring type and resident weight on external hand forces required to push floor-based lifts in long-term care (LTC). Novel compliant flooring is designed to reduce fall-related injuries among LTC residents but may increase forces required for staff to perform pushing tasks. A motorized lift may offset the effect of flooring on push forces. Fourteen female LTC staff performed straight-line pushes with two floor-based lifts (conventional, motor driven) loaded with passengers of average and 90th-percentile resident weights over four flooring systems (concrete+vinyl, compliant+vinyl, concrete+carpet, compliant+carpet). Initial and sustained push forces were measured by a handlebar-mounted triaxial load cell and compared to participant-specific tolerance limits. Participants rated pushing difficulty. Novel compliant flooring increased initial and sustained push forces and subjective ratings compared to concrete flooring. Compared to the conventional lift, the motor-driven lift substantially reduced initial and sustained push forces and perceived difficulty of pushing for all four floors and both resident weights. Participants exerted forces above published tolerance limits only when using the conventional lift on the carpet conditions (concrete+carpet, compliant+carpet). With the motor-driven lift only, resident weight did not affect push forces. Novel compliant flooring increased linear push forces generated by LTC staff using floor-based lifts, but forces did not exceed tolerance limits when pushing over compliant+vinyl. The motor-driven lift substantially reduced push forces compared to the conventional lift. Results may help to address risk of work-related musculoskeletal injury, especially in locations with novel compliant flooring. © 2016, Human Factors and Ergonomics Society.

  15. Estimation of lumbar spinal loading and trunk muscle forces during asymmetric lifting tasks: application of whole-body musculoskeletal modelling in OpenSim.

    PubMed

    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.

  16. Attack optimization for unequal moderate forces

    SciTech Connect

    Canavan, G.H.

    1997-06-01

    Attack allocation optimizations produce stability indices for unsymmetrical forces that indicate significant regions of both stability and instability and that have their minimum values roughly when the two sides have equal forces. This note derives combined stability indices for unsymmetrical offensive force configurations. The indices are based on optimal allocations of offensive missiles between vulnerable missiles and value based on the minimization of first strike cost, which is done analytically. Exchanges are modeled probabalistically and their results are converted into first and second strike costs through approximations to the damage to the value target sets held at risk. The stability index is the product of the ratio of first to second strike costs seen by the two sides. Optimal allocations scale directly on the opponent`s vulnerable missiles, inversely on one`s own total weapons, and only logarithmically on the attacker`s damage preference, kill probability, and relative target set. The defender`s allocation scales in a similar manner on the attacker`s parameters. First and second strike magnitudes increase roughly linearly for the side with greater forces and decrease linearly for the side with fewer. Conversely, the first and second strike magnitudes decrease for the side with greater forces and increase for the side with fewer. These trends are derived and discussed analytically. The resulting stability indices exhibit a minimum where the two sides have roughly equal forces. If one side has much larger forces than the other, his costs drop to levels low enough that he is relatively insensitive to whether he strikes first or second. These calculations are performed with the analytic attack allocation appropriate for moderate forces, so some differences could be expected for the largest of the forces considered.

  17. A hydrodynamic focusing microchannel based on micro-weir shear lift force.

    PubMed

    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.

  18. 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.

  19. Mean and fluctuating components of drag and lift forces on an isolated finite-sized particle in turbulence

    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

  20. Combining configurational energies and forces for molecular force field optimization

    NASA Astrophysics Data System (ADS)

    Vlcek, Lukas; Sun, Weiwei; Kent, Paul R. C.

    2017-10-01

    While quantum chemical simulations have been increasingly used as an invaluable source of information for atomistic model development, the high computational expenses typically associated with these techniques often limit thorough sampling of the systems of interest. It is therefore of great practical importance to use all available information as efficiently as possible, and in a way that allows for consistent addition of constraints that may be provided by macroscopic experiments. Here we propose a simple approach that combines information from configurational energies and forces generated in a molecular dynamics simulation to increase the effective number of samples. Subsequently, this information is used to optimize a molecular force field by minimizing the statistical distance similarity metric. We illustrate the methodology on an example of a trajectory of configurations generated in equilibrium molecular dynamics simulations of argon and water and compare the results with those based on the force matching method.

  1. Optimal Balance Between Force and Velocity Differs Among World-Class Athletes.

    PubMed

    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.

  2. Investigation of trunk muscle activities during lifting using a multi-objective optimization-based model and intelligent optimization algorithms.

    PubMed

    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.

  3. A more general Force Balance Model to predict Bubble Departure and Lift-off Diameters in flow boiling

    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.

  4. Lossless image compression based on optimal prediction, adaptive lifting, and conditional arithmetic coding.

    PubMed

    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.

  5. Fabrication of nano-sized magnetic tunnel junctions using lift-off process assisted by atomic force probe tip.

    PubMed

    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.

  6. Lifting speed preferences and their effects on the maximal lifting capacity.

    PubMed

    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.

  7. Lifting speed preferences and their effects on the maximal lifting capacity

    PubMed Central

    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

  8. Inexpensive Dramatic Pneumatic Lift

    ERIC Educational Resources Information Center

    Morse, Robert A.

    Various experiments and demonstrations relate air pressure and air pressure difference to force and area. Carpenter and Minnix describe a large-scale pneumatic lift in which a person sitting on a board atop a plastic garbage bag is lifted when the bag is connected to the exhaustport of a vacuum cleaner, which easily lifts the person. This article…

  9. Inexpensive Dramatic Pneumatic Lift

    NASA Astrophysics Data System (ADS)

    Morse, Robert A.

    2017-09-01

    Various experiments and demonstrations relate air pressure and air pressure difference to force and area. Carpenter and Minnix describe a large-scale pneumatic lift in which a person sitting on a board atop a plastic garbage bag is lifted when the bag is connected to the exhaustport of a vacuum cleaner, which easily lifts the person. This article describes the construction and use of an inexpensive hand-held pneumatic lift to demonstrate the same principle.

  10. 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.

  11. Control of Precision Grip Force in Lifting and Holding of Low-Mass Objects

    PubMed Central

    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

  12. Control of Precision Grip Force in Lifting and Holding of Low-Mass Objects.

    PubMed

    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.

  13. Determining safe limits for significant task parameters during manual lifting.

    PubMed

    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. Copyright 2014, SLACK Incorporated.

  14. Body lift.

    PubMed

    Capella, Joseph F

    2008-01-01

    The body in the patient who has lost a massive amount of weight presents an extreme form of traditional esthetic and functional body contour concerns. Routine body contouring procedures usually produce only suboptimal results in this patient population. The body lift described herein is an excellent alternative to treat the body contour deformity of the patient who has undergone bariatric surgery. As with every technique, careful patient selection, education, and preparation are critical to minimizing complications and optimizing outcome.

  15. 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

  16. Optimal linear prediction of ordered bands and lifting wavelet transform applied to lossless compression of MODIS image

    NASA Astrophysics Data System (ADS)

    Zhang, Xubing; Guan, Zequn; Yu, Xin

    2007-11-01

    The enormous volumes and valuable applications of MODIS (Moderate Resolution Imaging Spectroradiometer) multi-spectral images make it need to be compressed losslessly with effective method. To solve this problem, the optimal linear prediction and band ordering are adopted here to exploit abundant spectral redundancy, lifting wavelet transform and SPIHT algorithm are used to eliminate the spatial redundancy of MODIS data. The optimal inter-band prediction sequence is specified by band ordering, and except the first band, only residual error images of other bands need to be encoded after band prediction. To avoid information loss, the optimal linear predictor is improved by rounding the prediction coefficients into integers, and D5/3 lifting wavelet is used to implement integer-to-integer wavelet transform of the band image, which also accelerate the compression. Finally, some lossless compression methods such as "WinRAR", "3DSPIHT" are compared with this compression method, and the experimental results show that our method has more compression capability.

  17. High lift selected concepts

    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.

  18. Load knowledge reduces rapid force production and muscle activation during maximal-effort concentric lifts.

    PubMed

    Hernández-Davó, J L; Sabido, R; Moya-Ramón, M; Blazevich, A J

    2015-12-01

    Rapid force development is a key factor influencing performance and injury risk in movements where little time is available for force production; thus there is a need to develop interventions that enhance this ability. In the present study, the influence of load knowledge on mechanical output [rate of force development; (RFD) and power] and muscle activation [electromyographic (EMG) responses] in the concentric-only bench press throw exercise was studied. Fifteen strength-trained individuals performed 6 sets of 6 maximal explosive repetitions in a single test session after extensive familiarization. In three of these sets the subjects were given knowledge about the load before each repetition (known condition; KC), whereas in the other three sets they were given no information (unknown condition; UC). In both conditions the loads were 30, 50 and 70 % of maximum, but condition and load orders were randomized. RFD (24-50 %) and power output (20-39 %) were significantly higher in UC in the early time intervals from movement onset (<150 ms). In addition, UC elicited greater EMG amplitudes in anterior deltoid both prior to movement onset (pre50-0 ms) and in the early time intervals (<100 ms) after movement onset, and in pectoralis major after movement onset (<100 ms). UC resulted in a greater initial activation of the muscles and both a higher RFD and mechanical power output in the early phase of the movement under all loading conditions (30-70 % of maximum). UC appears to offer a novel neuromuscular stimulus, and further research on the effects of continued exposure is warranted.

  19. Optimizing Global Force Management for Special Operations Forces

    DTIC Science & Technology

    2016-12-01

    Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN OPERATIONS RESEARCH from the NAVAL POSTGRADUATE...Department of Operations Research iv THIS PAGE INTENTIONALLY LEFT BLANK v ABSTRACT In light of increasing Special Operations Forces (SOF) mission...on to me about life and the Army Operations Research community. This thesis would also not be possible without the help of the dedicated staff of

  20. Observing how others lift light or heavy objects: which visual cues mediate the encoding of muscular force in the primary motor cortex?

    PubMed

    Alaerts, Kaat; Swinnen, Stephan P; Wenderoth, Nicole

    2010-06-01

    Observers are able to judge quite accurately the weights lifted by others. Only recently, neuroscience has focused on the role of the motor system to accomplish this task. In this respect, a previous transcranial magnetic stimulation (TMS) study showed that the muscular force requirements of an observed action are encoded by the primary motor cortex (M1). Overall, three distinct visual sources may provide information on the applied force of an observed lifting action, namely, (i) the perceived kinematics, (ii) the hand contraction state and finally (iii) intrinsic object properties. The principal aim of the present study was to disentangle these three visual sources and to explore their importance in mediating the encoding of muscular force requirements in the observer's motor system. A series of experiments are reported in which TMS was used to measure 'force-related' responses from the hand representation in left M1 while subjects observed distinct action-stimuli. Overall, results indicated that observation-induced activity in M1 reflects the level of observed force when kinematic cues of the lift (exp. 1) or cues on the hand contraction state (exp. 2) are available. Moreover, when kinematic cues and intrinsic object properties provide distinct information on the force requirements of an observed lifting action, results from experiment 3 indicated a strong preference for the use of kinematic features in mapping the force requirements of the observed action. In general, these findings support the hypothesis that the primary motor cortex contributes to action observation by mapping the muscle-related features of observed actions. Copyright 2010 Elsevier Ltd. All rights reserved.

  1. Static optimization of muscle forces during gait in comparison to EMG-to-force processing approach.

    PubMed

    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

  2. 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.

  3. A Mission-Adaptive Variable Camber Flap Control System to Optimize High Lift and Cruise Lift-to-Drag Ratios of Future N+3 Transport Aircraft

    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.

  4. 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.

  5. Breast lift

    MedlinePlus

    ... enable JavaScript. A breast lift, or mastopexy, is cosmetic breast surgery to lift the breasts. The surgery ... the position of the areola and nipple. Description Cosmetic breast surgery can be done at an outpatient ...

  6. Optimization of reproductive management programs using lift chart analysis and cost-sensitive evaluation of classification errors.

    PubMed

    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

  7. A nonlinear programming approach for optimizing two-stage lifting vehicle ascent to orbit

    NASA Technical Reports Server (NTRS)

    Kamm, J. L.; Johnson, I. L.

    1973-01-01

    An optimal atmospheric flight branched trajectory-shaping capability is presented based on the Davidon-Fletcher-Powell variable metric parameter optimization technique. Gradient information is generated using finite difference methods. A typical atmospheric flight branched optimization problem is analyzed which requires the determination of 31 parameters. This parameter set includes the three-dimensional description of vehicle attitude control angles for three branches of flight: first-stage ascent, second-stage ascent, and first-stage flyback. The important inflight inequality contraints required to maintain the integrity of the vehicles are considered. Some of the numerical methods employed are discussed, along with several new auxiliary techniques developed to improve the compatibility of the numerical gradient and iterator.

  8. Optimized free energies from bidirectional single-molecule force spectroscopy.

    PubMed

    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.

  9. Lifting scheme-based method for joint coding 3D stereo digital cinema with luminace correction and optimized prediction

    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.

  10. Lift performance and lumbar loading in standing and seated lifts.

    PubMed

    Middleton, Kane J; Carstairs, Greg L; Ham, Daniel J

    2016-09-01

    This study investigated the effect of posture on lifting performance. Twenty-three male soldiers lifted a loaded box onto a platform in standing and seated postures to determine their maximum lift capacity and maximum acceptable lift. Lift performance, trunk kinematics, lumbar loads, anthropometric and strength data were recorded. There was a significant main effect for lift effort but not for posture or the interaction. Effect sizes showed that lumbar compression forces did not differ between postures at lift initiation (Standing 5566.2 ± 627.8 N; Seated 5584.0 ± 16.0) but were higher in the standing posture (4045.7 ± 408.3 N) when compared with the seated posture (3655.8 ± 225.7 N) at lift completion. Anterior shear forces were higher in the standing posture at both lift initiation (Standing 519.4 ± 104.4 N; Seated 224.2 ± 9.4 N) and completion (Standing 183.3 ± 62.5 N; Seated 71.0 ± 24.2 N) and may have been a result of increased trunk flexion and a larger horizontal distance of the mass from the L5-S1 joint. Practitioner Summary: Differences between lift performance and lumbar forces in standing and seated lifts are unclear. Using a with-in subjects repeated measures design, we found no difference in lifted mass or lumbar compression force at lift initiation between standing and seated lifts.

  11. General Multiobjective Force Field Optimization Framework, with Application to Reactive Force Fields for Silicon Carbide.

    PubMed

    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.

  12. 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.

  13. Hydrodynamic effects of the tip movement on surface nanobubbles: a combined tapping mode, lift mode and force volume mode AFM study.

    PubMed

    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.

  14. Optimal plane changes using third-body forces.

    PubMed

    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.

  15. Optimization of Wastewater Lift Stations for Reduction of Energy Usage and Greenhouse Gas Emissions (WERF Report INFR3R11)

    EPA Science Inventory

    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...

  16. Optimization of Wastewater Lift Stations for Reduction of Energy Usage and Greenhouse Gas Emissions (WERF Report INFR3R11)

    EPA Science Inventory

    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...

  17. Fan and wing force data from wind tunnel investigation of a 0.38 meter (15 inch) diameter VTOL model lift fan installed in a two dimensional wing

    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.

  18. Optimized discrete wavelet transforms in the cubed sphere with the lifting scheme—implications for global finite-frequency tomography

    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.

  19. New mitral annular force transducer optimized to distinguish annular segments and multi-plane forces.

    PubMed

    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.

  20. Wind tower service lift

    DOEpatents

    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.

  1. Final Report of the Simulation Optimization Task Force

    SciTech Connect

    ATLAS Collaboration; Rimoldi, A.; Carli, T.; Dell'Acqua, A.; Froidevaux, D.; Gianotti, F.; Guyot, C.; Hinchliffe, I.; Jakobs, K.; Marshall, Z.; Nisati, A.; Quarrie, D.; Unal, G.; Young, C.

    2008-12-15

    This is the final report of the ATLAS Simulation Optimization Task Force, establishedin June of 2007. This note justifies the selected Geant4 version, physics list, and range cuts to be used by the default ATLAS simulation for initial data taking and beyond. The current status of several projects, including detector description, simulation validation, studies of additional Geant4 parameters, and cavern background, are reported.

  2. Hybrid Airships for Lift: A New Lift Paradigm and a Pragmatic Assessment of the Vehicle’s Key Operational Challenges

    DTIC Science & Technology

    2011-12-01

    required lift for flight, Hybrid Airships use a combination of buoyant lift (provided by a gas such as Helium), aerodynamic lift (generated by airflow...AIR FORCE FELLOWS AIR UNIVERSITY HYBRID AIRSHIPS FOR LIFT: A NEW LIFT PARADIGM AND A PRAGMATIC ASSESSMENT OF THE...00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE Hybrid Airships for Lift: A New Lift Paradigm And A Pragmatic Assessment Of The Vehicle’s Key

  3. 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.

  4. Patient lifts.

    PubMed

    1990-03-01

    In this issue, we evaluate conventional patient lifts that operate by hand cranking, hand pumping, or battery-powered motors and are intended for use in the home or in institutions. We did not evaluate lifts that are designed to be used solely in bathrooms or vehicles or those that permanently affix to walls, floors or ceilings. Some of the evaluated lifts are intended primarily for use in specific environments (e.g., one can be easily disassembled into small components for automobile transport). We evaluated 15 patient lifts from eight manufacturers, basing our ratings on performance, safety, and human factors design. Because different designs make lifts preferable for different environments, we rated the lifts for both home and institutional use based on their size, ruggedness, ease of storage, maneuverability, and cost. Seven units-the Arjo 218150; the Handi-Move 1200; the Hoyer C-CBL; the Invacare 9901, 9916 and 9917; and the Porto-Lift PL-1 are rated Acceptable for both home and institutional use. The Trans-Aid S1-600 and the Versa Lift are rated Acceptable for institutional use and Acceptable-Not Recommended for home use because of their size and cost. The Arjo B and the Hoyer Travel Lift are rated Acceptable for home use and Acceptable-Not Recommended for institutional use because they will not comfortably accommodate patients of all sizes; the Arjo B has additional limitations. The Hoyer C-HLA, the Invacare 9902, and the Trans-Aid LAT-2 are rated Conditionally Acceptable for home use on the condition that they are not used to transfer patients who weigh more than 200 lb; all three units are rated Conditionally Acceptable-Not Recommended for institutional use since there is no reliable way to ensure that they will not be used on heavier patients. The Century C-3 lift is rated Conditionally Acceptable for institutional use on the condition that it is used with the base fully extended; because the fully extended base makes the unit awkward to maneuver in

  5. Lifting Sample Return Capsule

    NASA Technical Reports Server (NTRS)

    2006-01-01

    NASA's Stardust sample return capsule successfully landed at the U.S. Air Force Utah Test and Training Range at 2:10 a.m. Pacific time (3:10 a.m. Mountain time). The capsule contains cometary and interstellar samples gathered by the Stardust spacecraft.

    Here, the capsule is being lifted at the landing site.

  6. Portfolio theory of optimal isometric force production: Variability predictions and nonequilibrium fluctuation dissipation theorem

    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.

  7. A review of a method for dynamic load distribution, dynamical modeling, and explicit internal force control when two manipulators mutually lift and transport a rigid body object

    SciTech Connect

    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.

  8. Forehead lift

    MedlinePlus

    ... 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: ...

  9. Buttock Lift

    MedlinePlus

    ... 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 ...

  10. Rigorous force field optimization principles based on statistical distance minimization

    SciTech Connect

    Vlcek, Lukas; Chialvo, Ariel A.

    2015-10-12

    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. Here 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.

  11. Rigorous force field optimization principles based on statistical distance minimization

    DOE PAGES

    Vlcek, Lukas; Chialvo, Ariel A.

    2015-10-12

    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. Here 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 themore » 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.« less

  12. Rigorous force field optimization principles based on statistical distance minimization

    SciTech Connect

    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.

  13. The association between whole body vibration exposure and musculoskeletal disorders in the Swedish work force is confounded by lifting and posture

    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.

  14. Variations in the normal and tangential momentum accommodation coefficients from analysis of atmospheric lift and drag forces on ANS-1 (1974-70A)

    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.

  15. 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.

  16. Aerodynamic Force Characteristics of a Series of Lifting Cone and Cone-Cylinder Configurations at a Mach Number of 6.83 and Angles of Attack up to 130 Deg

    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.

  17. Active Head Lifting from Supine in Early Infancy: An Indicator for Non-Optimal Cognitive Outcome in Late Infancy

    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…

  18. Active Head Lifting from Supine in Early Infancy: An Indicator for Non-Optimal Cognitive Outcome in Late Infancy

    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…

  19. 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.

  20. 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.

  1. Face Lift.

    PubMed

    Wan, Dinah; Small, Kevin H; Barton, Fritz E

    2015-11-01

    After studying this article, the participant should be able to: 1. Identify the essential anatomy of the aging face and its relationship to face-lift surgery. 2. Understand the common operative approaches to the aging face and a historical perspective. 3. Understand and describe the common complications following face lifting and treatment options. Surgical rejuvenation of the aging face remains one of the most commonly performed plastic surgery procedures. This article reviews the anatomy of the face and its impact on surgical correction. In addition, this review discusses the evolution of various face-lift techniques and the current surgical approach to the aging face. Finally, this article discusses potential postoperative complications after rhytidectomy and management solutions.

  2. 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.

  3. Efficient retrieval of landscape Hessian: forced optimal covariance adaptive learning.

    PubMed

    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.

  4. Lifting Bodies on Lakebed

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The wingless, lifting body aircraft sitting on Rogers Dry Lake at what is now NASA's Dryden Flight Research Center, Edwards, California, from left to right are the X-24A, M2-F3 and the HL-10.The lifting body aircraft studied the feasibility of maneuvering and landing an aerodynamic craft designed for reentry from space. These lifting bodies were air launched by a B-52 mother ship, then flew powered by their own rocket engines before making an unpowered approach and landing. They helped validate the concept that a space shuttle could make accurate landings without power. The X-24A flew from April 17, 1969 to June 4, 1971. The M2-F3 flew from June 2, 1970 until December 21, 1971. The HL-10 flew from December 22, 1966 until July 17, 1970, and logged the highest and fastest records in the lifting body program. The X-24 was one of a group of lifting bodies flown by the NASA Flight Research Center (now Dryden Flight Research Center), Edwards, California, in a joint program with the U.S. Air Force at Edwards Air Force Base from 1963 to 1975. The lifting bodies were used to demonstrate the ability of pilots to maneuver and safely land wingless vehicles designed to fly back to Earth from space and be landed like an airplane at a predetermined site. Lifting bodies' aerodynamic lift, essential to flight in the atmosphere, was obtained from their shape. The addition of fins and control surfaces allowed the pilots to stabilize and control the vehicles and regulate their flight paths. Built by Martin Aircraft Company, Maryland, for the U.S. Air Force, the X-24A was a bulbous vehicle shaped like a teardrop with three vertical fins at the rear for directional control. It weighed 6,270 pounds, was 24.5 feet long and 11.5 feet wide (measuring just the fuselage, not the distance between the tips of the outboard fins). Its first unpowered glide flight was on April 17, 1969, with Air Force Maj. Jerauld Gentry at the controls. Gentry also piloted its first powered flight on March 19

  5. An experimental study of the lift, drag and static longitudinal stability for a three lifting surface configuration

    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.

  6. Face lift.

    PubMed

    Warren, Richard J; Aston, Sherrell J; Mendelson, Bryan C

    2011-12-01

    After reading this article, the participant should be able to: 1. Identify and describe the anatomy of and changes to the aging face, including changes in bone mass and structure and changes to the skin, tissue, and muscles. 2. Assess each individual's unique anatomy before embarking on face-lift surgery and incorporate various surgical techniques, including fat grafting and other corrective procedures in addition to shifting existing fat to a higher position on the face, into discussions with patients. 3. Identify risk factors and potential complications in prospective patients. 4. Describe the benefits and risks of various techniques. The ability to surgically rejuvenate the aging face has progressed in parallel with plastic surgeons' understanding of facial anatomy. In turn, a more clear explanation now exists for the visible changes seen in the aging face. This article and its associated video content review the current understanding of facial anatomy as it relates to facial aging. The standard face-lift techniques are explained and their various features, both good and bad, are reviewed. The objective is for surgeons to make a better aesthetic diagnosis before embarking on face-lift surgery, and to have the ability to use the appropriate technique depending on the clinical situation.

  7. Effects of a Belt on Intra-Abdominal Pressure during Weight Lifting.

    DTIC Science & Technology

    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

  8. The Determination of the Geometries of Multiple-Element Airfoils Optimized for Maximum Lift Coefficient. Ph.D. Thesis - Illinois Univ., Urbana

    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.

  9. High lift wake investigation

    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.

  10. A generalized formula for inertial lift on a sphere in microchannels.

    PubMed

    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.

  11. Optimization Case Study: ISR Allocation in the Global Force Management Process

    DTIC Science & Technology

    2016-09-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release. Distribution is unlimited. OPTIMIZATION ...REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE OPTIMIZATION CASE STUDY: ISR ALLOCATION IN THE GLOBAL FORCE MANAGEMENT PROCESS 5...provided by the military services to Geographic Combatant Commander requirements. This thesis is a proof of concept for an optimization model that

  12. Global optimization of parameters in the reactive force field ReaxFF for SiOH.

    PubMed

    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.

  13. Optimizing the post-START US strategic nuclear force mix

    SciTech Connect

    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.

  14. Optimization and parallelization of a force field for silicon using OpenMP*

    NASA Astrophysics Data System (ADS)

    Goedecker, Stefan

    2002-10-01

    The force field by Lenosky and coworkers is the latest force field for silicon which is one of the most studied materials. It has turned out to be highly accurate in a large range of test cases. The optimization and parallelization of this force field using OpenMp and Fortran90 is described here. The optimized program allows us to handle a very large number of silicon atoms in large scale simulations. Since all the parallelization is hidden in a single subroutine that returns the total energies and forces, this subroutine can be called from within a serial program in an user friendly way.

  15. Tissue Contraction Force Microscopy for Optimization of Engineered Cardiac Tissue

    PubMed Central

    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

  16. 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.

  17. Optimal control of an influenza model with seasonal forcing and age-dependent transmission rates.

    PubMed

    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.

  18. Optimizing Long-Term Capital Planning for Special Operations Forces

    DTIC Science & Technology

    2015-06-01

    portfolio . The goal of this thesis is to improve the LRCPT by developing proof-of-principle optimization models for long-range capital planning. We...impacts, but the LRCPT does not provide an optimized program portfolio . The goal of this thesis is to improve the LRCPT by developing proof-of-principle...spending for the WGP model maximizing portfolio value and project procurement

  19. Lifting Bodies on Lakebed

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The wingless, lifting body aircraft sitting on Rogers Dry Lake at what is now NASA's Dryden Flight Research Center, Edwards, California, from left to right are the X-24A, M2-F3 and the HL-10.The lifting body aircraft studied the feasibility of maneuvering and landing an aerodynamic craft designed for reentry from space. These lifting bodies were air launched by a B-52 mother ship, then flew powered by their own rocket engines before making an unpowered approach and landing. They helped validate the concept that a space shuttle could make accurate landings without power. The X-24A flew from April 17, 1969 to June 4, 1971. The M2-F3 flew from June 2, 1970 until December 22, 1972. The HL-10 flew from December 22, 1966 until July 17, 1970, and logged the highest and fastest records in the lifting body program. The X-24 was one of a group of lifting bodies flown by the NASA Flight Research Center (FRC-now Dryden Flight Research Center), Edwards, California, in a joint program with the U.S. Air Force at Edwards Air Force Base from 1963 to 1975. The lifting bodies were used to demonstrate the ability of pilots to maneuver and safely land wingless vehicles designed to fly back to Earth from space and be landed like an airplane at a predetermined site. Lifting bodies' aerodynamic lift, essential to flight in the atmosphere, was obtained from their shape. The addition of fins and control surfaces allowed the pilots to stabilize and control the vehicles and regulate their flight paths. Built by Martin Aircraft Company, Maryland, for the U.S. Air Force, the X-24A was a bulbous vehicle shaped like a teardrop with three vertical fins at the rear for directional control. It weighed 6,270 pounds, was 24.5 feet long and 11.5 feet wide (measuring just the fuselage, not the distance between the tips of the outboard fins). Its first unpowered glide flight was on April 17, 1969, with Air Force Maj. Jerauld Gentry at the controls. Gentry also piloted its first powered flight on March 19

  20. Understanding Force Multipliers: The Key to Optimizing Force Capabilities in Peacetime Contingency Operations

    DTIC Science & Technology

    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

  1. Total facelift: forehead lift, midface lift, and neck lift.

    PubMed

    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.

  2. Total Facelift: Forehead Lift, Midface Lift, and Neck Lift

    PubMed Central

    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

  3. Optimizing the Router Configurations within a Nominal Air Force Base

    DTIC Science & Technology

    2009-09-01

    a separable to a non-separable graph. Thus, removal of any single vertex will not produce a disconnected graph. Frederickson and JaJa showed (non...Force Base Locator, http://www.airforce.com/contact-us/base- locator/, accessed June 1, 2009. [3] G. N. Frederickson and J. JaJa , “On the relationship

  4. Mars Reconnaissance Orbiter MRO Lifts Off

    NASA Image and Video Library

    2005-08-12

    Atlas V launch vehicle, 19 stories tall, with a two-ton NASA Mars Reconnaissance Orbiter MRO on top, lifts off the pad on Launch Complex 41 at Cape Canaveral Air Force Station in Florida on Aug. 12, 2005.

  5. Observation of the Field, Current and Force Distributions in an Optimized Superconducting Levitation with Translational Symmetry

    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.

  6. Interdicting a Force Deployment: Two-Sided Optimization of Asset Selection, Lift Scheduling, and Multi-Commodity Load Planning

    DTIC Science & Technology

    2005-03-01

    2005 Thesis Advisor: Gerald Brown Second Readers: Glenn Lintz Matthew Carlyle...CDR, SC, USN Second Reader Matthew Carlyle Second Reader James N. Eagle Chairman, Department of Operations Research iv...spreadsheet is extracted to a comma- separated value file for direct use by our algebraic modeling language , General Algebraic Modeling System (GAMS

  7. Unsteady Lift Generation for MAVs

    DTIC Science & Technology

    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

  8. 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.

  9. 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.

  10. Optimization of force constants with an Urey-Bradley force field avoiding normal mode crossings.

    PubMed

    Vivoni, A; Birke, R; Lombardi, J

    2001-03-01

    We present a method that simplifies the refinement of force constants in normal mode calculations and makes the results more reliable. The method avoids normal mode crossings by constraining the force constants during refinement. It was tested with pyrrole, imidazole, benzene, pyridine, pyrimidine, aniline and adenine using a Urey-Bradley force field. The global error of the frequency fit for these molecules was 0.61%. The method reproduced with fewer parameters the accuracy of similar calculations of the single ring aromatic compounds. It improved the accuracy and isotopic shifts of previous empirical calculations of adenine by 40%. The C-C and C-N stretchings differed by less than 7% from the values of force constant-bond length empirical relations.

  11. Optimizing the US Navy’s Combat Logistics Force

    DTIC Science & Technology

    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

  12. 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.

  13. Variable Lifting Index (VLI)

    PubMed Central

    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

  14. Muscle Synergies May Improve Optimization Prediction of Knee Contact Forces During Walking

    PubMed Central

    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

  15. Optimizing Structural Active Control Force Using the Exterior Penalty Function Method

    SciTech Connect

    Tavassoli, Mohammad Reza; Amini, Fereidoun

    2008-07-08

    A new method for optimizing the control force in a closed-open loop control system has been developed. In this method which applies the complete feedback, structural responses including displacement, velocity, acceleration and also the excitation forces are used to determine the required control forces. In a closed-open loop control system, applying control force is equivalent to making changes in the mass, damping and stiffness matrices of the structure and the external force vector. Assuming these changes are linear and proportional to their initial values, the minimization of control force depends on the optimal values of the proportion coefficients. This idea leads to a constrained optimization problem of n-variable, which has been solved by using the exterior penalty function method and the Powell's search algorithm. The peak control force is the objective function of this optimization problem and the proportion coefficients are the design variables. The supposed limitation of the structural responses comprises the constraints of the problem. The effectiveness of the proposed method is demonstrated by some numerical examples.

  16. 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.

  17. 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.

  18. Theoretical study of enhancing the piezoelectric nanogenerator's output power by optimizing the external force's shape

    NASA Astrophysics Data System (ADS)

    Xu, Qi; Qin, Yong

    2017-07-01

    The average power is one of the key parameters of piezoelectric nanogenerators (PENGs). In this paper, we demonstrate that the PENG's output can be gigantically improved by choosing driving force with an appropriate shape. When the load resistance is 100 MΩ and the driven forces have a magnitude of 19.6 nN, frequency of 10 Hz, the average power of PENG driven by square shaped force is six orders of magnitude higher than that driven by triangular shaped and sinusoidal shaped forces. These results are of importance for optimizing the average power of the PENGs in practical applications.

  19. The protein folding problem: global optimization of the force fields.

    PubMed

    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.

  20. Lift truck safety review

    SciTech Connect

    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.

  1. A COMPARISON OF STATIC AND DYNAMIC OPTIMIZATION MUSCLE FORCE PREDICTIONS DURING WHEELCHAIR PROPULSION

    PubMed Central

    Morrow, Melissa M.; Rankin, Jeffery W.; Neptune, Richard R.; Kaufman, Kenton R.

    2014-01-01

    The primary purpose of this study was to compare static and dynamic optimization muscle force and work predictions during the push phase of wheelchair propulsion. A secondary purpose was to compare the differences in predicted shoulder and elbow kinetics and kinematics and handrim forces. The forward dynamics simulation minimized differences between simulated and experimental data (obtained from 10 manual wheelchair users) and muscle co-contraction. For direct comparison between models, the shoulder and elbow muscle moment arms and net joint moments from the dynamic optimization were used as inputs into the static optimization routine. RMS errors between model predictions were calculated to quantify model agreement. There was a wide range of individual muscle force agreement that spanned from poor (26.4 % Fmax error in the middle deltoid) to good (6.4 % Fmax error in the anterior deltoid) in the prime movers of the shoulder. The predicted muscle forces from the static optimization were sufficient to create the appropriate motion and joint moments at the shoulder for the push phase of wheelchair propulsion, but showed deviations in the elbow moment, pronation-supination motion and hand rim forces. These results suggest the static approach does not produce results similar enough to be a replacement for forward dynamics simulations, and care should be taken in choosing the appropriate method for a specific task and set of constraints. Dynamic optimization modeling approaches may be required for motions that are greatly influenced by muscle activation dynamics or that require significant co-contraction. PMID:25282075

  2. The Cost of Leg Forces in Bipedal Locomotion: A Simple Optimization Study

    PubMed Central

    Rebula, John R.; Kuo, Arthur D.

    2015-01-01

    Simple optimization models show that bipedal locomotion may largely be governed by the mechanical work performed by the legs, minimization of which can automatically discover walking and running gaits. Work minimization can reproduce broad aspects of human ground reaction forces, such as a double-peaked profile for walking and a single peak for running, but the predicted peaks are unrealistically high and impulsive compared to the much smoother forces produced by humans. The smoothness might be explained better by a cost for the force rather than work produced by the legs, but it is unclear what features of force might be most relevant. We therefore tested a generalized force cost that can penalize force amplitude or its n-th time derivative, raised to the p-th power (or p-norm), across a variety of combinations for n and p. A simple model shows that this generalized force cost only produces smoother, human-like forces if it penalizes the rate rather than amplitude of force production, and only in combination with a work cost. Such a combined objective reproduces the characteristic profiles of human walking (R2 = 0.96) and running (R2 = 0.92), more so than minimization of either work or force amplitude alone (R2 = −0.79 and R2 = 0.22, respectively, for walking). Humans might find it preferable to avoid rapid force production, which may be mechanically and physiologically costly. PMID:25707000

  3. 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.

  4. Muscle optimization techniques impact the magnitude of calculated hip joint contact forces.

    PubMed

    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.

  5. Use of Decoys to Optimize an All-Atom Force Field Including Hydration

    PubMed Central

    Arnautova, Yelena A.; Scheraga, Harold A.

    2008-01-01

    A novel method of parameter optimization is proposed. It makes use of large sets of decoys generated for six nonhomologous proteins with different architecture. Parameter optimization is achieved by creating a free energy gap between sets of nativelike and nonnative conformations. The method is applied to optimize the parameters of a physics-based scoring function consisting of the all-atom ECEPP05 force field coupled with an implicit solvent model (a solvent-accessible surface area model). The optimized force field is able to discriminate near-native from nonnative conformations of the six training proteins when used either for local energy minimization or for short Monte Carlo simulated annealing runs after local energy minimization. The resulting force field is validated with an independent set of six nonhomologous proteins, and appears to be transferable to proteins not included in the optimization; i.e., for five out of the six test proteins, decoys with 1.7- to 4.0-Å all-heavy-atom root mean-square deviations emerge as those with the lowest energy. In addition, we examined the set of misfolded structures created by Park and Levitt using a four-state reduced model. The results from these additional calculations confirm the good discriminative ability of the optimized force field obtained with our decoy sets. PMID:18502794

  6. SMAP Lift to CR

    NASA Image and Video Library

    2014-10-16

    Inside the Astrotech payload processing facility on Vandenberg Air Force Base in California, engineers and technicians use a crane to move a component of NASA's Soil Moisture Active Passive, or SMAP, spacecraft for a lift by a crane. SMAP will launch on a Delta II 7320 configuration vehicle featuring a United Launch Alliance first stage booster powered by an Aerojet Rocketdyne RS-27A main engine and three Alliant Techsystems, or ATK, strap-on solid rocket motors. Once on station in Earth orbit, SMAP will provide global measurements of soil moisture and its freeze/thaw state. These measurements will be used to enhance understanding of processes that link the water, energy and carbon cycles, and to extend the capabilities of weather and climate prediction models. SMAP data also will be used to quantify net carbon flux in boreal landscapes and to develop improved flood prediction and drought monitoring capabilities. Launch from Space Launch Complex 2 is targeted for Jan. 29, 2015.

  7. Breast lift (mastopexy) - slideshow

    MedlinePlus

    ... page: //medlineplus.gov/ency/presentations/100188.htm Breast lift (mastopexy) - series—Incisions To use the sharing features ... to slide 3 out of 3 Overview Breast lift (mastopexy) is usually performed for drooping breasts, which ...

  8. Forehead lift - slideshow

    MedlinePlus

    ... page: //medlineplus.gov/ency/presentations/100020.htm Forehead lift - series—Indications To use the sharing features on ... to slide 3 out of 3 Overview Forehead lifts are most commonly done for people in their ...

  9. 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).

  10. Biomechanical comparison of isokinetic lifting and free lifting when applied to chronic low back pain rehabilitation.

    PubMed

    Bouilland, S; Loslever, P; Lepoutre, F X

    2002-03-01

    The study compares free and isokinetic lifting using a multivariate statistical analysis. Each of the 13 male subjects performed three free lifts and three isokinetic lifts using a CYBEX LIFTASK. The measurement variables were obtained from a 3D video system, two force plates and two strain-gauge transducers. Coupling of fuzzy space-time windowing and multiple correspondence analysis was used to show the links between the variables and the differences between the experimental situations. Isokinetic lifting had almost no points in common with free-lifting, but there was a similar range of extension for the different joints. Most free-lifting strategies could not be used in isokinetic lifting, as constraints between the subject and his environment were different. The main drawback of the isokinetic lifting was due to the necessity for individuals to reach the machine speed, yielding high transient efforts. The maximum vertical effort at the L5/S1 joint was about 1600, 1500 and 1400N for low, medium and high speed, whereas it was lower than 1300N, irrespective of the load, during free lifting. In the context of chronic low back pain rehabilitation, movement strategies used in free lifting could not be relearnt using an isokinetic machine. A better understanding of the common points and differences between isokinetic movement and free movement could help rehabilitation physicians to plan rehabilitation programmes, taking advantage of each kind of movement.

  11. NCCN Task Force Report: Optimizing Treatment of Advanced Renal Cell Carcinoma With Molecular Targeted Therapy

    PubMed Central

    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

  12. Optimal Shape for Forces and Moments on a Multi-Element Hydrofoil

    DTIC Science & Technology

    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

  13. 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.

  14. Optimization of force in the Wingate Test for children with a neuromuscular disease.

    PubMed

    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.

  15. Design optimization of piezoresistive cantilevers for force sensing in air and water

    PubMed Central

    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

  16. Quiet powered-lift propulsion

    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.

  17. 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.

  18. Combining spanwise morphing, inline motion and model based optimization for force magnitude and direction control

    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.

  19. 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%.

  20. 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.

  1. 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…

  2. 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…

  3. Molecular simulations of imidazolium-based tricyanomethanide ionic liquids using an optimized classical force field.

    PubMed

    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.

  4. Parameterization and optimization of the menthol force field for molecular dynamics simulations.

    PubMed

    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.

  5. 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.

  6. A review of a method for dynamic load distribution, dynamic modeling, and explicit internal force control when two serial link manipulators mutually lift and transport a rigid body object

    SciTech Connect

    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.

  7. 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.

  8. EMG assisted optimization: a hybrid approach for estimating muscle forces in an indeterminate biomechanical model.

    PubMed

    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.

  9. Pig lift: A new artifical lift method

    SciTech Connect

    Lima, P.C.R.

    1996-12-31

    Artificial lift of oil wells is a fairly broad subject. There are many different methods available but in a few cases none of them turns out to be a fit option. Some specific situation such as high viscosity or waxy oil, high gas-to-liquid ratio (GLR), horizontal and/or very deep well generate artificial lift problems that causes high reservoir back pressure, and, consequently, low production rates. Pig lift is a new novel artificial lift method developed to solve some of these problems. It uses a U-shaped double completion string in the wellbore, with a full bore bottom hole connector, and a surface piping and control system. This physical arrangement is put together to allow the cyclic and automated launching of a low density foam pig from the surface, pushing along with it the liquid phase accumulated into the tubing string. The method is, therefore, cyclic. High pressure gas is used to displace the pig. The system was successfully installed in five wells in Brazil, increasing the production flow rate significantly, as compared to conventional artificial lift methods. This paper presents the description of the pig lift method, and reports the results obtained in these field trials. Discussions of its technical and economical advantages and potential areas of application is also given.

  10. Flow effects with cross-blown lifting jets of V/STOL aircraft and their reactions on aerodynamical forces and moments of the airframe

    NASA Technical Reports Server (NTRS)

    Viehweger, G.

    1977-01-01

    Systematic basic studies on the close and distant effects of cross blown single and twin lifting jets were performed with the aid of a principle model. The different effects are described in detail. The number of the experimental parameters is reduced to the most essential ones: (1) the angle of attack, (2) the flight and the jet velocities as well as the jet diameter, (3) the distance between the twin jets, (4) the location of the wing relative to the jets and the fuselage, and (5) the ground distance. The results of systematic pressure distribution measurements on the fuselage surface are studied, especially in the close vicinity of the jet exits. From these results, functions on the influence of the parameters are deduced.

  11. An optimized intermolecular force field for hydrogen-bonded organic molecular crystals using atomic multipole electrostatics.

    PubMed

    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%.

  12. Cost function tuning improves muscle force estimation computed by static optimization during walking.

    PubMed

    Monaco, V; Coscia, M; Micera, S

    2011-01-01

    Muscle force estimation while a dynamic motor task is carried out still presents open questions. In particular, concerning locomotion, although the inverse dynamic based static optimization has been widely accepted as a suitable method to obtain reliable results, appropriate modifications of the object function may improve results. This paper was aimed at analyzing the sensitivity of estimated muscle forces when modifications of the objective function are adopted to better fit EMG signals of healthy subjects. A 7 links and 9 degrees of freedom biomechanical model accounting for 14 lower limb muscles, grouped in 9 equivalent actuators, was developed. Muscle forces were estimated by using the inverse dynamic based static optimization in which the performance criteria was the sum of muscle stresses raised to a certain n power. This exponent was gradually changed (from 2 to 100) and the agreement between force patterns and EMG signals was estimated by both the correlation coefficient and the Coactivation Index. Results suggested that force estimation can be improved by slightly modifying the cost function. In particular, with respect to adopted data, when the exponent belong to the interval between 2.75 and 4, estimated forces better captured general features of EMG signals. Concluding, a more reliable solution can be obtained by suitably tuning the cost function in order to fit EMG signals.

  13. An optimized intermolecular force field for hydrogen-bonded organic molecular crystals using atomic multipole electrostatics

    PubMed Central

    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

  14. Secondary lift for magnetically levitated vehicles

    DOEpatents

    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.

  15. HSCT high-lift technology requirements

    NASA Technical Reports Server (NTRS)

    Antani, D. L.; Morgenstern, J. M.

    1992-01-01

    The viewgraphs and discussion of high lift needs and related aerodynamic goals established in system studies are described. The goals are presented for the takeoff, approach, and subsonic climb and cruise modes. The status of the related high lift databases and available design and analysis methods are described. Various high lift research and technology areas for future work including innovative concepts verification, flap design, computational fluid dynamics (CFD) calibration and application, high Reynolds number testing, subsonic/transonic flap optimization, and flight testing are described.

  16. The Effect of Lifting Speed on Cumulative and Peak Biomechanical Loading for Symmetric Lifting Tasks

    PubMed Central

    Greenland, Kasey O.; Merryweather, Andrew S.; Bloswick, Donald S.

    2013-01-01

    Background To determine the influence of lifting speed and type on peak and cumulative back compressive force (BCF) and shoulder moment (SM) loads during symmetric lifting. Another aim of the study was to compare static and dynamic lifting models. Methods Ten male participants performed a floor-to-shoulder, floor-to-waist, and waist-to-shoulder lift at three different speeds [slow (0.34 m/s), medium (0.44 m/s), and fast (0.64 m/s)], and with two different loads [light (2.25 kg) and heavy (9 kg)]. Two-dimensional kinematics and kinetics were determined. A three-way repeated measures analysis of variance was used to calculate peak and cumulative loading of BCF and SM for light and heavy loads. Results Peak BCF was significantly different between slow and fast lifting speeds (p < 0.001), with a mean difference of 20% between fast and slow lifts. The cumulative loading of BCF and SM was significantly different between fast and slow lifting speeds (p < 0.001), with mean differences ≥80%. Conclusion Based on peak values, BCF is highest for fast speeds, but the BCF cumulative loading is highest for slow speeds, with the largest difference between fast and slow lifts. This may imply that a slow lifting speed is at least as hazardous as a fast lifting speed. It is important to consider the duration of lift when determining risks for back and shoulder injuries due to lifting and that peak values alone are likely not sufficient. PMID:23961334

  17. Sensorimotor Memory Biases Weight Perception During Object Lifting

    PubMed Central

    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

  18. Optimization of the OPLS-AA Force Field for Long Hydrocarbons.

    PubMed

    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.

  19. Optimization of Active Muscle Force-Length Models Using Least Squares Curve Fitting.

    PubMed

    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.

  20. Lifting BLS Power Supplies

    SciTech Connect

    Sarychev, Michael

    2007-08-01

    This note describes BLS power supplies lifting techniques and provides stress calculations for lifting plate and handles bolts. BLS power supply weight is about 120 Lbs, with the center of gravity shifted toward the right front side. A lifting plate is used to attach a power supply to a crane or a hoist. Stress calculations show that safety factors for lifting plate are 12.9 (vs. 5 required) for ultimate stress and 5.7 (vs. 3 required) for yield stress. Safety factor for shackle bolt thread shear load is 37, and safety factor for bolts that attach handles is 12.8.

  1. Multidisciplinary Design Optimization for Aeropropulsion Engines and Solid Modeling/Animation via the Integrated Forced Methods

    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.

  2. Fast force field-based optimization of protein-ligand complexes with graphics processor.

    PubMed

    Heinzerling, Lennart; Klein, Robert; Rarey, Matthias

    2012-12-15

    Usually based on molecular mechanics force fields, the post-optimization of ligand poses is typically the most time-consuming step in protein-ligand docking procedures. In return, it bears the potential to overcome the limitations of discretized conformation models. Because of the parallel nature of the problem, recent graphics processing units (GPUs) can be applied to address this dilemma. We present a novel algorithmic approach for parallelizing and thus massively speeding up protein-ligand complex optimizations with GPUs. The method, customized to pose-optimization, performs at least 100 times faster than widely used CPU-based optimization tools. An improvement in Root-Mean-Square Distance (RMSD) compared to the original docking pose of up to 42% can be achieved. Copyright © 2012 Wiley Periodicals, Inc.

  3. Validation of Multibody Program to Optimize Simulated Trajectories II Parachute Simulation with Interacting Forces

    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.

  4. Performance Optimization of Force Feedback Control System in Virtual Vascular Intervention Surgery

    PubMed Central

    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

  5. 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.

  6. Experimental Analysis of Mast Lifting and Bending Forces on Vibration Patterns Before and After Pinion Reinstallation in an OH-58 Transmission Test Rig

    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.

  7. Experimental Analysis of Mast Lifting and Bending Forces on Vibration Patterns Before and After Pinion Reinstallation in an OH-58 Transmission Test Rig

    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.

  8. 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.

  9. Experimental determination of baseball spin and lift.

    PubMed

    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.

  10. 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.

  11. External force back-projective composition and globally deformable optimization for 3-D coronary artery reconstruction

    NASA Astrophysics Data System (ADS)

    Yang, Jian; Cong, Weijian; Chen, Yang; Fan, Jingfan; Liu, Yue; Wang, Yongtian

    2014-02-01

    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.

  12. External force back-projective composition and globally deformable optimization for 3-D coronary artery reconstruction.

    PubMed

    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.

  13. Comparison of joint space versus task force load distribution optimization for a multiarm manipulator system

    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.

  14. 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.

  15. Optimizing 1-μs-Resolution Single-Molecule Force Spectroscopy on a Commercial Atomic Force Microscope.

    PubMed

    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.

  16. Force.

    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)

  17. Force.

    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)

  18. Catwalk grate lifting tool

    DOEpatents

    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.

  19. Portable Lifting Seat

    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.

  20. Catwalk grate lifting tool

    DOEpatents

    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.

  1. Understanding Wing Lift

    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…

  2. Portable Lifting Seat

    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.

  3. High lift aerodynamics

    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.

  4. Understanding Wing Lift

    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…

  5. Portable seat lift

    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.

  6. Optimal design of thrust force in vertical-type HTS bulk LRM

    NASA Astrophysics Data System (ADS)

    Yoshida, K.; Matsumoto, H.; Eguchi, M.

    2005-10-01

    We proposed the vertical-type linear reluctance motor (LRM) with HTS bulks cooled in zero-field. The double-sided HTS bulk LRM is propelled contactlessly only by electromagnetic repulsive force from both sides of a double-sided armature guideway. This paper presents optimal thrust force design based on the dependence of thrust on the size of HTS bulk attached to the cage in vertical-type HTS bulk LRM. The thrust force is calculated by Finite Element Method (FEM), taking into account the E-J characteristic. Improved HTS bulk LRM which is 1.5 times heavier than the previous cage can be propelled contactlessly in propulsion and guidance simulation.

  7. 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.

  8. Production automation system for gas lift wells

    SciTech Connect

    Cooksey, A.; Pool, M.

    1995-12-31

    Economic conditions in the gas and oil industry have necessitated not only reductions in manpower and capital expenditure but also optimization of existing facilities. The approach that appears to offer the most viability for satisfying these needs is system automation. For this reason, technology in gas lift operation has directed its attention toward the development of modular systems that can automate operations at each wellhead and platform. Intelligent controllers can be used (1) with centralized master station direction or (2) as stand-alone products for automating immediate response to preset conditional parameters. In addition to reducing manpower requirements, intelligent controllers will further enhance gas lift operation by helping to increase the efficiency of continuous-flow gas lift operations. In addition, they can be used to automate load shedding that results from lift gas fluctuations. With automated systems, operators can now set up field-wide programs that provide optimum use of available lift gas with minimal manpower; this supports the operational direction encouraged by the economic climate of today`s oilfield. Production rates increase when normal gas lift flow rate set-point control is maintained at each well. In the optimization system described in this paper, the set point changes can be manually entered at the wellhead controller or from a central master station.

  9. Samus Counter Lifting Fixture

    SciTech Connect

    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.

  10. 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.

  11. Allometry of hummingbird lifting performance

    PubMed Central

    Altshuler, D. L.; Dudley, R.; Heredia, S. M.; McGuire, J. A.

    2010-01-01

    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. PMID:20154187

  12. Allometry of hummingbird lifting performance.

    PubMed

    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.

  13. 1Hz rTMS preconditioned by tDCS over the primary motor cortex in Parkinson's disease: absence of effect on arm lift and hand grip force control.

    PubMed

    Eggers, Carsten; Grüner, Ulrike; Ameli, Mitra; Sarfeld, Anna-Sophia; Nowak, Dennis A

    2012-04-01

    This study investigated whether a period of low frequency rTMS preconditioned by tDCS over the primary motor cortex modulates control of grip force in Parkinson's disease. The presented results are from the same patient cohort tested in an earlier study (Gruner et al. J Neural Transm 2010: 117: 207-216). 15 patients with Parkinson's disease (mean age: 69 ± 8 years; average disease duration: 5 ± 3 years) on dopaminergic drugs performed a grasp-lift task with either hand before (baseline) and after a period of 1Hz rTMS (90% of the resting motor threshold; 900 pulses) preconditioned by sham, anodal or cathodal tDCS (1mA, 10 min) over the primary motor cortex. We found that compared with baseline, none of the grip force parameters was significantly influenced by either stimulation session and concluded that grasping is a higher order motor skill, which cannot be modulated by tDCS preconditioned 1Hz rTMS in PD.

  14. Paramfit: automated optimization of force field parameters for molecular dynamics simulations.

    PubMed

    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.

  15. Measuring Lift with the Wright Airfoils

    NASA Astrophysics Data System (ADS)

    Heavers, Richard M.; Soleymanloo, Arianne

    2011-11-01

    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 blower2 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 (the measured values of L) to the lower end of a string passing over a pulley and connected to the other end of the rotating platform (Fig. 2). Our homemade airfoils are similar to those tested by the Wright brothers in 1901. From our lift plots in Fig. 3, we can draw the same conclusions as the Wrights about the influence of an airfoil's curvature and shape on lift.

  16. 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.

  17. 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).

  18. Genetic algorithm optimization of point charges in force field development: challenges and insights.

    PubMed

    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.

  19. Anticipatory Control of Motion-to-Force Transitions With the Fingertips Adapts Optimally to Task Difficulty

    PubMed Central

    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

  20. Influence of model complexity and problem formulation on the forces in the knee calculated using optimization methods

    PubMed Central

    2013-01-01

    Background Predictions of the forces transmitted by the redundant force-bearing structures in the knee are often performed using optimization methods considering only moment equipollence as a result of simplified knee modeling without ligament contributions. The current study aimed to investigate the influence of model complexity (with or without ligaments), problem formulation (moment equipollence with or without force equipollence) and optimization criteria on the prediction of the forces transmitted by the force-bearing structures in the knee. Methods Ten healthy young male adults walked in a gait laboratory while their kinematic and ground reaction forces were measured simultaneously. A validated 3D musculoskeletal model of the locomotor system with a knee model that included muscles, ligaments and articular surfaces was used to calculate the joint resultant forces and moments, and subsequently the forces transmitted in the considered force-bearing structures via optimization methods. Three problem formulations with eight optimization criteria were evaluated. Results Among the three problem formulations, simultaneous consideration of moment and force equipollence for the knee model with ligaments and articular contacts predicted contact forces (first peak: 3.3-3.5 BW; second peak: 3.2-4.2 BW; swing: 0.3 BW) that were closest to previously reported theoretical values (2.0-4.0 BW) and in vivo data telemetered from older adults with total knee replacements (about 2.8 BW during stance; 0.5 BW during swing). Simultaneous consideration of moment and force equipollence also predicted more physiological ligament forces (< 1.0 BW), which appeared to be independent of the objective functions used. Without considering force equipollence, the calculated contact forces varied from 1.0 to 4.5 BW and were as large as 2.5 BW during swing phase; the calculated ACL forces ranged from 1 BW to 3.7 BW, and those of the PCL from 3 BW to 7 BW. Conclusions Model complexity and problem

  1. Optimization and calibration of atomic force microscopy sensitivity in terms of tip-sample interactions in high-order dynamic atomic force microscopy

    SciTech Connect

    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.

  2. A fast procedure for optimizing dynamic force distribution in multifingered grasping.

    PubMed

    Zheng, Yu; Qian, Wen-Han

    2006-12-01

    This correspondence deals with the dynamic force distribution (DFD) problem, i.e., computing the contact forces to equilibrate a dynamic external wrench on the grasped object. The sum of the normal force components is minimized for enhancing safety and saving energy. By this optimality criterion, the DFD problem can be transformed into a linear programming (LP) problem. Its objective function is the inner product of the dynamic external wrench and a vector, and the constraints on the vector, given by a set of linear inequalities, define a polytope. The solution to the LP problem can always be attained at the vertex of the polytope called the solution vertex. We notice that the polytope is determined by the grasp configuration. Along with the direction change of the dynamic external wrench, only the solution vertex moves to an adjacent vertex sequentially, whereas the polytope with all its vertices remains unchanged. Therefore, the polytope and the adjacencies of each vertex can be computed in the offline phase. Then, in the online phase, simply search the adjacencies of the old solution vertex for the new one. Without lost of optimality, such a DFD algorithm runs a thousandfold faster than solving the LP problem by the simplex method in real time.

  3. Optimized atomistic force fields for aqueous solutions of Magnesium and Calcium Chloride: Analysis, achievements and limitations

    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.

  4. Muscle force regulates bone shaping for optimal load-bearing capacity during embryogenesis.

    PubMed

    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.

  5. Optimization of a hybrid vibration absorber for vibration control of structures under random force excitation

    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.

  6. The vertical medial thigh lift.

    PubMed

    Capella, Joseph F

    2014-10-01

    This article discusses management of the post-weight loss thigh deformity. Beginning with an explanation of the soft tissue variables contributing to the thigh and medial thigh deformity in the postbariatric individual, the article describes the important elements of selecting and screening candidates for surgery and the ideal sequence of procedures that should be followed to optimize results in this patient population. A detailed step-by-step description of the author's technique for medial thigh lift is provided along with multiple examples of outcomes. Aftercare is reviewed along with potential complications and their management. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Forced sustained swimming exercise at optimal speed enhances growth of juvenile yellowtail kingfish (Seriola lalandi)

    PubMed Central

    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

  8. Forced sustained swimming exercise at optimal speed enhances growth of juvenile yellowtail kingfish (Seriola lalandi).

    PubMed

    Palstra, Arjan P; Mes, Daan; Kusters, Kasper; Roques, Jonathan A C; Flik, Gert; Kloet, Kees; Blonk, Robbert J W

    2014-01-01

    Swimming exercise at optimal speed may optimize growth performance of yellowtail kingfish in a recirculating aquaculture system. Therefore, optimal swimming speeds (U opt 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 U opt on growth performance of juvenile yellowtail kingfish. U opt 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 U opt (BL s(-1)) = 234.07(BL)(-0.779) (R (2) = 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.

  9. 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.

  10. Three Lifting Bodies on Lakebed

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The wingless, lifting body aircraft sitting on Rogers Dry Lake at what is now NASA's Dryden Flight Research Center, Edwards, California, from left to right are the X-24A, M2-F3 and the HL-10.The lifting body aircraft studied the feasibility of maneuvering and landing an aerodynamic craft designed for reentry from space. These lifting bodies were air launched by a B-52 mother ship, then flew powered by their own rocket engines before making an unpowered approach and landing. They helped validate the concept that a space shuttle could make accurate landings without power. The X-24A flew from April 17, 1969 to June 4, 1971. The M2-F3 flew from June 2, 1970 until December 20, 1972. The HL-10 flew from December 22, 1966 until July 17, 1970 and logged the highest and fastest records in the lifting body program. The X-24 was one of a group of lifting bodies flown by the NASA Flight Research Center (FRC--now Dryden Flight Research Center), Edwards, California, in a joint program with the U.S. Air Force at Edwards Air Force Base from 1963 to 1975. The lifting bodies were used to demonstrate the ability of pilots to maneuver and safely land wingless vehicles designed to fly back to Earth from space and be landed like an airplane at a predetermined site. Lifting bodies' aerodynamic lift, essential to flight in the atmosphere, was obtained from their shape. The addition of fins and control surfaces allowed the pilots to stabilize and control the vehicles and regulate their flight paths. Built by Martin Aircraft Company, Maryland, for the U.S. Air Force, the X-24A was a bulbous vehicle shaped like a teardrop with three vertical fins at the rear for directional control. It weighed 6,270 pounds, was 24.5 feet long and 11.5 feet wide (measuring just the fuselage, not the distance between the tips of the outboard fins). Its first unpowered glide flight was on April 17, 1969, with Air Force Maj. Jerauld Gentry at the controls. Gentry also piloted its first powered flight on March 19

  11. 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.

  12. Lifting the Runners

    NASA Image and Video Library

    2010-08-25

    Under the unflinching summer sun, workers at NASA Deep Space Network complex in Goldstone, Calif., use a crane to lift a runner segment that is part of major surgery on a giant, 70-meter-wide antenna.

  13. FREIGHT CONTAINER LIFTING STANDARD

    SciTech Connect

    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.

  14. 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.

  15. Nonlinear-programming optimized fiber Bragg grating based force-torque-sensor with six degrees of freedom

    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.

  16. Controlling the 3D architecture of Self-Lifting Auto-generated Tissue Equivalents (SLATEs) for optimized corneal graft composition and stability.

    PubMed

    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

  17. Observing object lifting errors modulates cortico-spinal excitability and improves object lifting performance.

    PubMed

    Buckingham, Gavin; Wong, Jeremy D; Tang, Minnie; Gribble, Paul L; Goodale, Melvyn A

    2014-01-01

    Observing the actions of others has been shown to modulate cortico-spinal excitability and affect behaviour. However, the sensorimotor consequences of observing errors are not well understood. Here, participants watched actors lift identically weighted large and small cubes which typically elicit expectation-based fingertip force errors. One group of participants observed the standard overestimation and underestimation-style errors that characterise early lifts with these cubes (Error video--EV). Another group watched the same actors performing the well-adapted error-free lifts that characterise later, well-practiced lifts with these cubes (No error video--NEV). We then examined actual object lifting performance in the subjects who watched the EV and NEV. Despite having similar cognitive expectations and perceptions of heaviness, the group that watched novice lifters making errors themselves made fewer overestimation-style errors than those who watched the expert lifts. To determine how the observation of errors alters cortico-spinal excitability, we measured motor evoked potentials in separate group of participants while they passively observed these EV and NEV. Here, we noted a novel size-based modulation of cortico-spinal excitability when observing the expert lifts, which was eradicated when watching errors. Together, these findings suggest that individuals' sensorimotor systems are sensitive to the subtle visual differences between observing novice and expert performance. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Design and optimization of a harmonic probe with step cross section in multifrequency atomic force microscopy.

    PubMed

    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.

  19. Design and optimization of a harmonic probe with step cross section in multifrequency atomic force microscopy

    SciTech Connect

    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.

  20. Specialty Task Force: A Strategic Component to Electronic Health Record (EHR) Optimization.

    PubMed

    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.

  1. Optimal ferromagnetically-coated carbon nanotube tips for ultra-high resolution magnetic force microscopy.

    PubMed

    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.

  2. Lifting of NASA OCO-2 Delta II Launch Vehicle

    NASA Image and Video Library

    2014-04-15

    The Delta II second stage for NASA Orbiting Carbon Observatory-2 mission, or OCO-2, is lifted to the top of the mobile service tower at Space Launch Complex 2 on Vandenberg Air Force Base in California.

  3. DETAIL VIEW OF BRIDGE CRANE USED TO LIFT DOMED LIDS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    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

  4. 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.

  5. Optimal force-velocity profile in ballistic movements--altius: citius or fortius?.

    PubMed

    Samozino, Pierre; Rejc, Enrico; Di Prampero, Pietro Enrico; Belli, Alain; Morin, Jean-Benoît

    2012-02-01

    The study's purpose was to determine the respective influences of the maximal power (Pmax) and the force-velocity (F-v) mechanical profile of the lower limb neuromuscular system on performance in ballistic movements. A theoretical integrative approach was proposed to express ballistic performance as a mathematical function of Pmax and F-v profile. This equation was (i) validated from experimental data obtained on 14 subjects during lower limb ballistic inclined push-offs and (ii) simulated to quantify the respective influence of Pmax and F-v profile on performance. The bias between performances predicted and obtained from experimental measurements was 4%-7%, confirming the validity of the proposed theoretical approach. Simulations showed that ballistic performance was mostly influenced not only by Pmax but also by the balance between force and velocity capabilities as described by the F-v profile. For each individual, there is an optimal F-v profile that maximizes performance, whereas unfavorable F-v balances lead to differences in performance up to 30% for a given Pmax. This optimal F-v profile, which can be accurately determined, depends on some individual characteristics (limb extension range, Pmax) and on the afterload involved in the movement (inertia, inclination). The lower the afterload, the more the optimal F-v profile is oriented toward velocity capabilities and the greater the limitation of performance imposed by the maximal velocity of lower limb extension. High ballistic performances are determined by both maximization of the power output capabilities and optimization of the F-v mechanical profile of the lower limb neuromuscular system.

  6. An automated analysis workflow for optimization of force-field parameters using neutron scattering data

    DOE PAGES

    Lynch, Vickie E.; Borreguero, Jose M.; Bhowmik, Debsindhu; ...

    2017-03-27

    Large-scale simulations and data analysis are often required to explain neutron scattering experiments to establish a connection between the fundamental physics at the nanoscale and data probed by neutrons. In order to perform simulations at experimental conditions it is critical to use correct force-field (FF) parameters which are unfortunately not available for most complex experimental systems. In this work, we have developed a workflow optimization technique to provide optimized FF parameters by comparing molecular dynamics (MD) to neutron scattering data. Here, we describe the workflow in detail by using an example system consisting of tRNA and hydrophilic nanodiamonds in amore » deuterated water (D2O) environment. Quasi-elastic neutron scattering (QENS) data show a faster motion of the tRNA in the presence of nanodiamond than without the ND. In order to compare the QENS and MD results quantitatively, a proper choice of FF parameters is necessary. We use an efficient workflow to optimize the FF parameters between the hydrophilic nanodiamond and water by comparing to the QENS data. Our results show that we can obtain accurate FF parameters by using this technique. The workflow can be generalized to other types of neutron data for FF optimization, such as vibrational spectroscopy and spin echo.« less

  7. An automated analysis workflow for optimization of force-field parameters using neutron scattering data

    NASA Astrophysics Data System (ADS)

    Lynch, Vickie E.; Borreguero, Jose M.; Bhowmik, Debsindhu; Ganesh, Panchapakesan; Sumpter, Bobby G.; Proffen, Thomas E.; Goswami, Monojoy

    2017-07-01

    Large-scale simulations and data analysis are often required to explain neutron scattering experiments to establish a connection between the fundamental physics at the nanoscale and data probed by neutrons. However, to perform simulations at experimental conditions it is critical to use correct force-field (FF) parameters which are unfortunately not available for most complex experimental systems. In this work, we have developed a workflow optimization technique to provide optimized FF parameters by comparing molecular dynamics (MD) to neutron scattering data. We describe the workflow in detail by using an example system consisting of tRNA and hydrophilic nanodiamonds in a deuterated water (D2O) environment. Quasi-elastic neutron scattering (QENS) data show a faster motion of the tRNA in the presence of nanodiamond than without the ND. To compare the QENS and MD results quantitatively, a proper choice of FF parameters is necessary. We use an efficient workflow to optimize the FF parameters between the hydrophilic nanodiamond and water by comparing to the QENS data. Our results show that we can obtain accurate FF parameters by using this technique. The workflow can be generalized to other types of neutron data for FF optimization, such as vibrational spectroscopy and spin echo.

  8. Design optimization and uncertainty quantification for aeromechanics forced response of a turbomachinery blade

    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

  9. Optimizing Solute-Solute Interactions in the GLYCAM06 and CHARMM36 Carbohydrate Force Fields Using Osmotic Pressure Measurements.

    PubMed

    Lay, Wesley K; Miller, Mark S; Elcock, Adrian H

    2016-04-12

    GLYCAM06 and CHARMM36 are successful force fields for modeling carbohydrates. To correct recently identified deficiencies with both force fields, we adjusted intersolute nonbonded parameters to reproduce the experimental osmotic coefficient of glucose at 1 M. The modified parameters improve behavior of glucose and sucrose up to 4 M and improve modeling of a dextran 55-mer. While the modified parameters may not be applicable to all carbohydrates, they highlight the use of osmotic simulations to optimize force fields.

  10. 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

  11. Evaluating dispersion forces for optimization of van der Waals complexes using a non-empirical functional

    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'.

  12. Evaluating dispersion forces for optimization of van der Waals complexes using a non-empirical functional.

    PubMed

    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'. © 2016 The Author(s).

  13. 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.

  14. Structure Optimization of Wheel Force Transducer Based on Natural Frequency and Comprehensive Sensitivity

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Long; Wu, Ti; Shao, Yan; Song, Jian

    2017-07-01

    The current research of wheel force transducer (WFT) mainly focuses on test signal processing and decoupling methods based on signal itself, while the WFT structure optimization research related to decreasing the mass and increase the natural frequency and comprehensive sensitivity is not enough. In order to improve the WFT test accuracy, a structure optimization method based on natural frequency and comprehensive sensitivity indicators is put forward. The WFT with 8-beam elastic body is used for the finite element modeling (FEM), in which the following variations are taken into consideration: the connection type of elastic body with modified rim, the number of connection holes, and the respects of strain beam including the shape, the cross sectional area and the length, etc.. The test results shows that the natural frequency of the connecting block type is increased by 65.5% compared with the connecting seat type of elastic body & modified rim, and the main channel sensitivity is improved as well. The results show that the connecting block type will achieve the best comprehensive performance when the number of connecting holes between the elastic body and the modified rim is 20. And the thinner and longer strain beam with smaller cross section area is preferable within the scope of elastic body mechanical strength. This research proposes a novel structure optimization method for WFT which contributes to improve the measurement performance of WFT.

  15. Optimal forcing perturbations for regional flow patterns conditioning polar low development

    NASA Astrophysics Data System (ADS)

    Kristiansen, Jørn; Iversen, Trond; Jung, Thomas; Barkmeijer, Jan

    2013-04-01

    olar lows are short lived maritime mesoscale cyclones that develop because of processes unique to the Polar Regions. In the ice-free Nordic and Barents Seas they are associated with violent weather during wintertime and form in cold air outbreaks underneath a cold through. The longer predictability of the large-scales may provide early warnings of the potential for polar lows. We investigate the rare events when the atmosphere is highly sensitive to small external forcings that excite changes in the variability of the North Atlantic Oscillation (NAO). Employing a numerical weather prediction model, the period 1957-2002 is sampled for 4-day optimal forcing sensitivity patterns (FSPs). The highly sensitive events are relatively well-defined. A flow pattern resembling the negative-phase NAO is identified as a potential precursor of the most unpredictable transitions in the NAO. The least sensitive events are dominated by a coinciding cyclonic circulation. In the former there is high polar low potential (40-45%) in the northern North Atlantic but it is low south of Iceland. The least sensitive events display high potential along the storm track reaching 80% south of Iceland. The FSPs tend to either strengthen or hamper the transition toward the negative-phase NAO. The strengthened circulation makes the atmosphere favourable in 70% of the events for the formation of polar lows in the Nordic and Barents Seas with high potentials also in the North Sea. From the hampered transition we learn that in the Nordic Seas high- and low-pressure systems can produce similar levels of polar low potential. Temperature and momentum are equally important forcing variables and there are positive feedbacks between them. The forcing is dominantly in-situ and strongest in mid-troposphere. The variability is more localized and larger than the average. Close to the surface the FSPs appear influenced by the Norwegian current.

  16. Regional changes in spine posture at lift onset with changes in lift distance and lift style.

    PubMed

    Gill, K Peter; Bennett, Simon J; Savelsbergh, Geert J P; van Dieën, Jaap H

    2007-07-01

    Repeated measures experiment. To determine the effect of changes in horizontal lift distance on the amount of flexion, at lift onset, in different spine regions when using different lift styles. By approximating spine bending during lifting as a pure rotation about a single revolute joint, the differential effects of task constraints and instructions on motions of different spine levels will be obscured. Eight participants lifted a 10-kg crate from the floor, 10 times at each of five distances. Participants were instructed to use freestyle (a participant's preferred lift style), squat, or stoop lift styles. Kinematic data were collected from the mid thoracic spine, lower thoracic/upper lumbar spine, mid lumbar spine, and the lower lumbar spine at lift onset. A whole spine angle was also calculated. Flexion of the lower lumbar spine was not affected by lift distance and style. Differences between lift styles occurred mainly in the mid thoracic and the lower thoracic/upper lumbar regions. With increasing horizontal distance, changes in lift style occurred in the upper three spine regions. These results suggest that the tensile strain on tissues in the lower lumbar spine, which can be a cause of injury in lifting, was not affected by lift style or horizontal lift distance when lifting from floor level.

  17. Precision markedly attenuates repetitive lift capacity.

    PubMed

    Collier, Brooke R; Holland, Laura; McGhee, Deirdre; Sampson, John A; Bell, Alison; Stapley, Paul J; Groeller, Herbert

    2014-01-01

    This study investigated the effect of precision on time to task failure in a repetitive whole-body manual handling task. Twelve participants were required to repetitively lift a box weighing 65% of their single repetition maximum to shoulder height using either precise or unconstrained box placement. Muscle activity, forces exerted at the ground, 2D body kinematics, box acceleration and psychophysical measures of performance were recorded until task failure was reached. With precision, time to task failure for repetitive lifting was reduced by 72%, whereas the duration taken to complete a single lift and anterior deltoid muscle activation increased by 39% and 25%, respectively. Yet, no significant difference was observed in ratings of perceived exertion or heart rate at task failure. In conclusion, our results suggest that when accuracy is a characteristic of a repetitive manual handling task, physical work capacity will decline markedly. The capacity to lift repetitively to shoulder height was reduced by 72% when increased accuracy was required to place a box upon a shelf. Lifting strategy and muscle activity were also modified, confirming practitioners should take into consideration movement precision when evaluating the demands of repetitive manual handling tasks.

  18. [Modern face lift surgery].

    PubMed

    von Gregory, H F; Gubisch, W

    2011-09-01

    Face lift surgery is generally considered the classical surgical procedure of plastic surgery. This is an extensive operation which has undergone a huge development since its first implementation more than 100 years ago. What began as a simple skin tightening procedure is today a sophisticated and complex technique which ideally combines different treatment methods planned with surgical precision. This article provides an overview of the history of the procedure to the present state of the art concept of pairing biplanar and bivectorial face-neck lifts with autologous fat transfer and dermabrasion.

  19. [Endoscopy and face-lift].

    PubMed

    Dardour, J C; Abbou, R

    2017-08-02

    For many years, the face-lift has not been the only intervention for facial rejuvenation. It is necessary today to specify the type of face-lift, cervico-facial lifting, frontal lifting or facelift. We will consider in this article the frontal lift and centro-facial lift and its possible execution assisted by endoscopy with therefore minimal scars, hidden in the scalp. We will consider successively its technique, its indications and its results highlighting a very long hold over time. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  20. Ergonomic Assessment of Floor-based and Overhead Lifts

    PubMed Central

    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

  1. The personal lift-assist device and lifting technique: a principal component analysis.

    PubMed

    Sadler, Erin M; Graham, Ryan B; Stevenson, Joan M

    2011-04-01

    The personal lift-assist device (PLAD) is a non-motorised, on-body device that acts as an external force generator using the concept of stored elastic energy. In this study, the effect of the PLAD on the lifting kinematics of male and female lifters was investigated using principal component analysis. Joint kinematic data of 15 males and 15 females were collected using an opto-electronic system during a freestyle, symmetrical-lifting protocol with and without wearing the PLAD. Of the 31 Principal Components (PCs) retained in the models, eight scores were significantly different between the PLAD and no-PLAD conditions. There were no main effects for gender and no significant interactions. Results indicated that the PLAD similarly affected the lifting kinematics of males and females; demonstrating significantly less lumbar and thoracic flexion and significantly greater hip and ankle flexion when wearing the PLAD. These findings add to the body of work that suggest the PLAD may be a safe and effective ergonomic aid. STATEMENT OF RELEVANCE: The PLAD is an ergonomic aid that has been shown to be effective at reducing low back demands during manual materials handling tasks. This body of work establishes that the PLAD encourages safe lifting practices without adversely affecting lifting technique.

  2. bOptimizing atomic force microscopy for characterization of diamond-protein interfaces

    PubMed Central

    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

  3. Quantifying feedforward control: a linear scaling model for fingertip forces and object weight

    PubMed Central

    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

  4. Control optimization of a lifting body entry problem by an improved and a modified method of perturbation function. Ph.D. Thesis - Houston Univ.

    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.

  5. Utilization of efficient gradient and Hessian computations in the force field optimization process of molecular simulations

    NASA Astrophysics Data System (ADS)

    Hülsmann, Marco; Kopp, Sonja; Huber, Markus; Reith, Dirk

    2013-01-01

    Computer simulations of chemical systems, especially systems of condensed matter, are highly important for both scientific and industrial applications. Thereby, molecular interactions are modeled on a microscopic level in order to study their impact on macroscopic phenomena. To be capable of predicting physical properties quantitatively, accurate molecular models are indispensable. Molecular interactions are described mathematically by force fields, which have to be parameterized. Recently, an automated gradient-based optimization procedure was published by the authors based on the minimization of a loss function between simulated and experimental physical properties. The applicability of gradient-based procedures is not trivial at all because of two reasons: firstly, simulation data are affected by statistical noise, and secondly, the molecular simulations required for the loss function evaluations are extremely time-consuming. Within the optimization process, gradients and Hessians were approximated by finite differences so that additional simulations for the respective modified parameter sets were required. Hence, a more efficient approach to computing gradients and Hessians is presented in this work. The method developed here is based on directional instead of partial derivatives. It is compared with the classical computations with respect to computation time. Firstly, molecular simulations are replaced by fit functions that define a functional dependence between specific physical observables and force field parameters. The goal of these simulated simulations is to assess the new methodology without much computational effort. Secondly, it is applied to real molecular simulations of the three chemical substances phosgene, methanol and ethylene oxide. It is shown that up to 75% of the simulations can be avoided using the new algorithm.

  6. Convergence behavior of multireference perturbation theory: Forced degeneracy and optimization partitioning applied to the beryllium atom

    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.

  7. JWST Lifting System

    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.

  8. Lifting as You Climb

    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…

  9. Hydraulic lifting device

    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.

  10. Lifting as You Climb

    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…

  11. Development and Optimization of Dynamic Atomic Force Microscopy Techniques with Applications in Soft Matter Characterization

    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.

  12. Development and implementation of a coupled computational muscle force optimization bone shape adaptation modeling method.

    PubMed

    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.

  13. An optimized charge penetration model for use with the AMOEBA force field.

    PubMed

    Rackers, Joshua A; Wang, Qiantao; Liu, Chengwen; Piquemal, Jean-Philip; Ren, Pengyu; Ponder, Jay W

    2016-12-21

    The principal challenge of using classical physics to model biomolecular interactions is capturing the nature of short-range interactions that drive biological processes from nucleic acid base stacking to protein-ligand binding. In particular most classical force fields suffer from an error in their electrostatic models that arises from an ability to account for the overlap between charge distributions occurring when molecules get close to each other, known as charge penetration. In this work we present a simple, physically motivated model for including charge penetration in the AMOEBA (Atomic Multipole Optimized Energetics for Biomolecular Applications) force field. With a function derived from the charge distribution of a hydrogen-like atom and a limited number of parameters, our charge penetration model dramatically improves the description of electrostatics at short range. On a database of 101 biomolecular dimers, the charge penetration model brings the error in the electrostatic interaction energy relative to the ab initio SAPT electrostatic interaction energy from 13.4 kcal mol(-1) to 1.3 kcal mol(-1). The model is shown not only to be robust and transferable for the AMOEBA model, but also physically meaningful as it universally improves the description of the electrostatic potential around a given molecule.

  14. Experimental and Numerical Optimization of a High-Lift System to Improve Low-Speed Performance, Stability, and Control of an Arrow-Wing Supersonic Transport

    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.

  15. Development of devices for self-injection: using tribological analysis to optimize injection force.

    PubMed

    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.

  16. Development of devices for self-injection: using tribological analysis to optimize injection force

    PubMed Central

    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

  17. In vivo loads on a vertebral body replacement during different lifting techniques.

    PubMed

    Dreischarf, Marcel; Rohlmann, Antonius; Graichen, Friedmar; Bergmann, Georg; Schmidt, Hendrik

    2016-04-11

    The repeated lifting of heavy weights has been identified as a risk factor for low back pain (LBP). Whether squat lifting leads to lower spinal loads than stoop lifting and whether lifting a weight laterally results in smaller forces than lifting the same weight in front of the body remain matters of debate. Instrumented vertebral body replacements (VBRs) were used to measure the in vivo load in the lumbar spine in three patients at level L1 and in one patient at level L3. Stoop lifting and squat lifting were compared in 17 measuring sessions, in which both techniques were performed a total of 104 times. The trunk inclination and amount of knee bending were simultaneously estimated from recorded images. Compared with the aforementioned lifting tasks, the patients additionally lifted a weight laterally with one hand 26 times. Only a small difference (4%) in the measured resultant force was observed between stoop lifting and squat lifting, although the knee-bending angle (stoop 10°, squat 45°) and trunk inclination (stoop 52°, squat 39°) differed considerably at the time points of maximal resultant forces. Lifting a weight laterally caused 14% less implant force on average than lifting the same weight in front of the body. The current in vivo biomechanical study does not provide evidence that spinal loads differ substantially between stoop and squat lifting. The anterior-posterior position of the lifted weight relative to the spine appears to be crucial for spinal loading. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Optimizing the utility of military injury surveillance systems: a qualitative study within the Australian Defence Force.

    PubMed

    McKinnon, Adam D; Ozanne-Smith, Joan; Pope, Rodney

    2009-05-01

    Injury prevention guided by robust injury surveillance systems (ISS's) can effectively reduce military injury rates, but ISS's depend on human interaction. This study examined experiences and requirements of key users of the Australian Defence Force (ADF) ISS to determine whether the operation of the ISS was optimal, whether there were any shortcomings, and if so, how these shortcomings might be addressed. Semistructured interviews were conducted with 18 Australian Defence Department participants located throughout Australia. Grounded theory methods were used to analyze data by developing an understanding of processes and social phenomena related to injury surveillance systems within the military context. Interviews were recorded and professionally transcribed and information contained in the transcripts was analyzed using NVivo. Key themes relating to the components of an injury surveillance system were identified from the analysis. A range of processes and sociocultural factors influence the utility of military ISS's. These are discussed in detail and should be considered in the future design and operation of military ISS's to facilitate optimal outcomes for injury prevention.

  19. 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

  20. [Maximum acceptable weight of lift for manual lifting tasks].

    PubMed

    Chen, Jing; Yang, Lei

    2006-04-01

    To explore the maximum acceptable weight of lift (MAWL) in different lifting conditions and the suitable lifting equation for the stipulation of occupational health standard of manual lifting tasks in China. The MAWL was investigated among the thirteen male and ten female students using psychophysical methodology and the recommended weight of limit (RWL) was compared. The MAWL of male and female subjects was decreased gradually with the increase of lifting height. Once the height of lifting was over shoulder, the MAWL was decreased dramatically. The RWL was greater than the MAWL at 25 cm horizontal distance in male subjects, but the RWL was smaller than the MAWL at the distance of 45 cm and 63 cm. The average MAWL of male subjects was 30.8% greater than that of female subjects. The MAWL was decreased gradually with increase of the horizontal distance at the same height of lifting. The result of the male subjects was consistent with that of the female subjects. For the asymmetric lifting tasks of the male subjects, the bigger the angle of rotation was, the less the MAWL became. The angle of rotation had negative correlation with the capability of lifting (r = -0.996 6, P < 0.01). When the subjects performed asymmetric lifting tasks, the RWL was smaller than the MAWL and the difference was significant. The revision is sufficient for the horizontal distance and asymmetric lifting in the NIOSH lifting equation, but it is not suitable for height, especially for the task of lifting over shoulder. The RWL for the task of lifting over shoulder should be lowered. The factor of gender should be taken into account in the lifting equation and the constant of gender S can be added. Then S = 1 for male while S = 0.692 for female.

  1. 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.

  2. 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.)

  3. 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.)

  4. Optimizing the gas distributor based on CO2 bubble dynamic behaviors to improve microalgal biomass production in an air-lift photo-bioreactor.

    PubMed

    Huang, Yun; Zhao, Sha; Ding, Yu-Dong; Liao, Qiang; Huang, Yong; Zhu, Xun

    2017-06-01

    Dynamic behavior of bubbles would significantly affect CO2 mass transfer and may cause microalgae cells uneven distribution due to the bubble carrying effect. To improve microalgae growth, the gas distributor and aeration conditions was optimized according to the bubble rising behavior. The CO2 bubble rising trajectory is similar to a Zigzag. The amplitude and wavelength of the Zigzag, which reflected the influenced zone of microalgae suspension in horizontal direction and disturbance intensity on culture, respectively, was controlled by the structure of gas distributor and aeration conditions. An optimized round gas distributor that full of holes with an inner diameter of 0.5mm and spacing of 1.5mm was designed. When cultivated with the optimized gas distributor aerating 5% CO2 gas at 0.250vvm, the maximum biomass concentration of Chlorella pyrenoidosa achieved 2.88gL(-1), increased by 83.44% compared to that of 1.57gL(-1)cultivated with the commercial micro-bubbles aerator. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Lip Lifting: Unveiling Dental Beauty.

    PubMed

    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.

  6. Optimal design of high damping force engine mount featuring MR valve structure with both annular and radial flow paths

    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.

  7. Delta II JPSS-1 Interstage Lift & Mate

    NASA Image and Video Library

    2016-07-13

    The interstage of the United Launch Alliance Delta II rocket that will launch the Joint Polar Satellite System-1 (JPSS-1) is lifted at Space Launch Complex 2 on Vandenberg Air Force Base in California. JPSS, a next-generation environmental satellite system, is a collaborative program between the National Oceanic and Atmospheric Administration (NOAA) and NASA. To learn more about JPSS-1, visit www.jpss.noaa.gov.

  8. GOES-R Lift and Mate

    NASA Image and Video Library

    2016-11-09

    Preparations are underway to lift NOAA's Geostationary Operational Environmental Satellite (GOES-R), enclosed in its payload fairing at the Vertical Integration Facility at Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida. GOES-R will be mated to the United Launch Alliance Atlas V Centaur upper stage in preparation for launch in November. GOES-R is the first satellite in a series of next-generation NOAA GOES Satellites.

  9. GOES-R Lift and Mate

    NASA Image and Video Library

    2016-11-09

    A view from high up inside the Vertical Integration Facility at Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida. A crane lifts the payload fairing containing NOAA's Geostationary Operational Environmental Satellite (GOES-R) for mating to the United Launch Alliance Atlas V Centaur upper stage. The satellite will launch aboard the Atlas V rocket in November. GOES-R is the first satellite in a series of next-generation NOAA GOES Satellites.

  10. GOES-R Lift and Mate

    NASA Image and Video Library

    2016-11-09

    A crane is used to lift the payload fairing containing NOAA's Geostationary Operational Environmental Satellite (GOES-R) at the Vertical Integration Facility at Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida. GOES-R will be mated to the United Launch Alliance Atlas V Centaur upper stage in preparation for launch in November. GOES-R is the first satellite in a series of next-generation NOAA GOES Satellites.

  11. GOES-R Lift and Mate

    NASA Image and Video Library

    2016-11-09

    A crane begins to lift the payload fairing containing NOAA's Geostationary Operational Environmental Satellite (GOES-R) at the Vertical Integration Facility at Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida. GOES-R will be mated to the United Launch Alliance Atlas V Centaur upper stage in preparation for launch in November. GOES-R is the first satellite in a series of next-generation NOAA GOES Satellites.

  12. GOES-R Lift and Mate

    NASA Image and Video Library

    2016-11-09

    Enclosed in its payload fairing, NOAA's Geostationary Operational Environmental Satellite (GOES-R) is lifted into the Vertical Integration Facility at Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida. GOES-R will be mated to the United Launch Alliance Atlas V Centaur upper stage in preparation for launch aboard the rocket in November. GOES-R is the first satellite in a series of next-generation NOAA GOES Satellites.

  13. How to lift a box that is too large to fit between the knees.

    PubMed

    Kingma, Idsart; Faber, Gert S; van Dieën, Jaap H

    2010-10-01

    Many studies compared lifting techniques such as stoop and squat lifting. Results thus far show that when lifting a wide load, high back loads result, irrespective of the lifting technique applied. This study compared four lifting techniques in 11 male subjects lifting wide loads. One of these techniques, denoted as the weight lifters' technique (WLT), is characterised by a wide foot placement, moderate knee flexion and a straight but not upright trunk. Net moments were calculated with a 3-D linked segment model and spinal forces with an electromyographic-driven trunk model. When lifting the wide box at handles that allow a high grip position, the WLT resulted in over 20% lower compression forces than the free, squat and stoop lifting technique, mainly due to a smaller horizontal distance between the l5S1 joint and the load. When lifting the wide box at the bottom, none of the lifting techniques was clearly superior to the others. STATEMENT OF RELEVANCE: Lifting low-lying and large objects results in high back loads and may therefore result in a high risk of developing low back pain. This study compares the utility of a WLT, in terms of back load and lumbar flexion, to more familiar techniques in these high-risk lifting tasks.

  14. 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.

  15. ESB Heavy Lift Requirements

    DTIC Science & Technology

    2006-01-01

    capacity, cross-country travel ability, and redundancy than the three axles and twelve tires found on the M870 trailer.13,14 In fact, this...equates to an organic ability to move approximately twenty- three percent of the battalion’s heavy equipment that requires prime movers in one lift...Truck Tractor manufactured by Oshkosh Truck Corporation and the M1000 Heavy Equipment Transporter semi-trailer manufactured by Systems

  16. Lifting liquid from boreholes

    SciTech Connect

    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.

  17. 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.

  18. Breath control during manual free-style lifting of a maximally tolerated load

    PubMed Central

    Lamberg, Eric M.; Hagins, Marshall

    2010-01-01

    Clear evidence links voluntary breath control, intra-abdominal pressure, and lumbar stability. However, little is known regarding optimal breath control during manual materials handling. No studies have examined natural breath control while lifting a maximal load. Fourteen healthy subjects lifted a loaded crate from the floor to a table while respiratory flow data were collected. The loads lifted began at 10% of body weight and increased up to 50% (if tolerated) by 5% increments. Data from the minimum, moderate and maximum loads were analyzed. Uniform and consistent breath holding during lifting of a maximally-tolerated load did not occur. Across all three loads frequency of inspiration was highest immediately prior to lift-off and significantly higher inspired volume occurred at lift-off of the load compared with preparation for lifting. Holding the breath does not appear to be related to lifting of a maximally tolerated load from floor to table. PMID:20191413

  19. Effect of a stiff lifting belt on spine compression during lifting.

    PubMed

    Kingma, Idsart; Faber, Gert S; Suwarganda, Edin K; Bruijnen, Tom B M; Peters, Rob J A; van Dieën, Jaap H

    2006-10-15

    An in vivo study on weightlifters. To determine if and how a stiff back belt affects spinal compression forces in weightlifting. In weightlifting, a back belt has been reported to enhance intraabdominal pressure (IAP) and to reduce back muscle EMG and spinal compression forces. Nine experienced weightlifters lifted barbells up to 75% body weight while inhaling and wearing a belt, inhaling and not wearing a belt, and exhaling and wearing a belt. IAP, trunk muscle EMG, ground reaction forces, and kinematics were measured. An EMG-assisted trunk model, including IAP effects, was used to calculate spinal compression and shear forces and to reveal the contribution of back muscles, abdominal muscles, and IAP to moment generation. The belt reduced compression forces by about 10%, but only when inhaling before lifting. The moment generated by IAP increased when wearing a belt and inhaling, but this moment was small and the increase was largely negated by the flexing moment generated by abdominal muscles. Wearing a tight and stiff back belt while inhaling before lifting reduces spine loading. This is caused by a moment generated by the belt rather than by the IAP.

  20. Lift, drag and flow-field measurements around a small ornithopter

    SciTech Connect

    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.

  1. Optimizing the inner loop of the gravitational force interaction on modern processors

    SciTech Connect

    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.

  2. Chemical shift prediction for protein structure calculation and quality assessment using an optimally parameterized force field

    PubMed Central

    Nielsen, Jakob T.; Eghbalnia, Hamid R.; Nielsen, Niels Chr.

    2011-01-01

    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. PMID:22293396

  3. Chemical shift prediction for protein structure calculation and quality assessment using an optimally parameterized force field.

    PubMed

    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.

  4. Innovative design of closing loops producing an optimal force system applicable in the 0.022-in bracket slot system.

    PubMed

    Sumi, Mayumi; Koga, Yoshiyuki; Tominaga, Jun-Ya; Hamanaka, Ryo; Ozaki, Hiroya; Chiang, Pao-Chang; Yoshida, Noriaki

    2016-12-01

    Most closing loops designed for producing higher moment-to-force (M/F) ratios require complex wire bending and are likely to cause hygiene problems and discomfort because of their complicated configurations. We aimed to develop a simple loop design that can produce optimal force and M/F ratio. A loop design that can generate a high M/F ratio and the ideal force level was investigated by varying the portion and length of the cross-sectional reduction of a teardrop loop and the loop position. The forces and moments acting on closing loops were calculated using structural analysis based on the tangent stiffness method. An M/F ratio of 9.3 (high enough to achieve controlled movement of the anterior teeth) and an optimal force level of approximately 250 g of force can be generated by activation of a 10-mm-high teardrop loop whose cross-section of 0.019 × 0.025 or 0.021 × 0.025 in was reduced in thickness by 50% for a distance of 3 mm from the apex, located between a quarter and a third of the interbracket distance from the canine bracket. The simple loop design that we developed delivers an optimal force and an M/F ratio for the retraction of anterior teeth, and is applicable in a 0.022-in slot system. Copyright © 2016 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  5. Detail of lift wire rope attachment to lift span at ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    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

  6. The effects of obesity on lifting performance.

    PubMed

    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.

  7. Anatomic concepts for brow lift procedures.

    PubMed

    Knize, David M

    2009-12-01

    Brow lifting became a component of the facialplasty procedure 45 years ago, and the original brow-lifting technique incorporating a coronal incision approach is still practiced by many surgeons today. Over the past 15 years, however, the endoscope-assisted procedure and the limited incision, nonendoscopic techniques have evolved as alternate procedures for brow lifting. The level of artistry in performing any brow lift technique is raised when the surgeon acquires knowledge of upper facial anatomy and integrates that knowledge into a working concept of the aging process of the upper face. This article presents one surgeon's concepts of the process that culminate in the typical appearance of the aged upper face. The same understanding of upper facial anatomy that can be called upon to explain the steps in this aging process can also be applied to the technical steps of any foreheadplasty procedure. Those anatomic structures that play a role in this process are examined here. The typical appearance of the aged upper face is the product of muscle action and gravitational forces acting on the unique anatomy of the human face. Interestingly, the appearance of the typical aged upper face exhibits much the same characteristics as one might observe in the face of an individual experiencing the emotions of sadness or grief. It is an inappropriate facial expression of sadness or grief that most often motivates the patient to schedule a consultation with the plastic surgeon. Any of the brow lift procedures used in current clinical practice can provide a successful cosmetic result in selected patients if the procedure incorporates technical steps based on sound anatomic principles.

  8. 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.

  9. Investigation, sensitivity analysis, and multi-objective optimization of effective parameters on temperature and force in robotic drilling cortical bone.

    PubMed

    Tahmasbi, Vahid; Ghoreishi, Majid; Zolfaghari, Mojtaba

    2017-11-01

    The bone drilling process is very prominent in orthopedic surgeries and in the repair of bone fractures. It is also very common in dentistry and bone sampling operations. Due to the complexity of bone and the sensitivity of the process, bone drilling is one of the most important and sensitive processes in biomedical engineering. Orthopedic surgeries can be improved using robotic systems and mechatronic tools. The most crucial problem during drilling is an unwanted increase in process temperature (higher than 47 °C), which causes thermal osteonecrosis or cell death and local burning of the bone tissue. Moreover, imposing higher forces to the bone may lead to breaking or cracking and consequently cause serious damage. In this study, a mathematical second-order linear regression model as a function of tool drilling speed, feed rate, tool diameter, and their effective interactions is introduced to predict temperature and force during the bone drilling process. This model can determine the maximum speed of surgery that remains within an acceptable temperature range. Moreover, for the first time, using designed experiments, the bone drilling process was modeled, and the drilling speed, feed rate, and tool diameter were optimized. Then, using response surface methodology and applying a multi-objective optimization, drilling force was minimized to sustain an acceptable temperature range without damaging the bone or the surrounding tissue. In addition, for the first time, Sobol statistical sensitivity analysis is used to ascertain the effect of process input parameters on process temperature and force. The results show that among all effective input parameters, tool rotational speed, feed rate, and tool diameter have the highest influence on process temperature and force, respectively. The behavior of each output parameters with variation in each input parameter is further investigated. Finally, a multi-objective optimization has been performed considering all the

  10. A magnetic-piezoelectric smart material-structure utilizing magnetic force interaction to optimize the sensitivity of current sensing

    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.

  11. Optimization of Kinematics of a Flapping Wing Mechanism

    NASA Astrophysics Data System (ADS)

    George, Ryan; Thomson, Scott; Mattson, Christopher; Colton, Mark; Tree, Mike

    2010-11-01

    Flapping flight offers several potential advantages over conventional fixed wing flight, such as agility and maneuverability in confined spaces, potentially decreased noise and detectability, and hovering capability. In this presentation, a water tunnel-based flapping wing apparatus is introduced that allows for arbitrary wing trajectories in three rotational degrees of freedom and simultaneous measurements of lift and thrust production. An optimal flapping trajectory for takeoff is found using hardware-in-the-loop optimization methodology. Wing motion derived from high-speed imaging of a ladybug during takeoff is used as a first iteration of the hardware-in-the-loop optimization. Using real-time force measurements and a gradient-based optimization approach, the algorithm searches for the optimal trajectory for a variety of parameters such as lift or efficiency. Hardware performance is assessed. Results from the optimization routine, including the final flapping trajectory are reported for both rigid and compliant wings.

  12. Effects of height and load weight on shoulder muscle work during overhead lifting task.

    PubMed

    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.

  13. 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.

  14. 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.

  15. Using EMG data to constrain optimization procedure improves finger tendon tension estimations during static fingertip force production.

    PubMed

    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.

  16. 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.

  17. Optimizing an F-16 Squadron Weekly Pilot Schedule for the Turkish Air Force

    DTIC Science & Technology

    2010-03-01

    implementation of Construction Heuristic (Aslan 2003) ................................ 13 Figure 3. Monday AM Network Flow Model (Boyd et al., 2006...author claims that a weekly schedule can be created using the heuristic (Aslan,2003). 13 . Figure 2. Software implementation of Construction...FORCE THESIS Murat Yavuz, First Lieutenant, TUAF AFIT-OR-MS-ENS-10-11 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF

  18. Fitting aerodynamic forces in the Laplace domain: An application of a nonlinear nongradient technique to multilevel constrained optimization

    NASA Technical Reports Server (NTRS)

    Tiffany, S. H.; Adams, W. M., Jr.

    1984-01-01

    A technique which employs both linear and nonlinear methods in a multilevel optimization structure to best approximate generalized unsteady aerodynamic forces for arbitrary motion is described. Optimum selection of free parameters is made in a rational function approximation of the aerodynamic forces in the Laplace domain such that a best fit is obtained, in a least squares sense, to tabular data for purely oscillatory motion. The multilevel structure and the corresponding formulation of the objective models are presented which separate the reduction of the fit error into linear and nonlinear problems, thus enabling the use of linear methods where practical. Certain equality and inequality constraints that may be imposed are identified; a brief description of the nongradient, nonlinear optimizer which is used is given; and results which illustrate application of the method are presented.

  19. Effects of range and mode on lifting capability and lifting time.

    PubMed

    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.

  20. 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

  1. Linearized Lifting-Surface and Lifting-line Evaluations of Sidewash Behind Rolling Triangular Wings at Supersonic Speeds

    NASA Technical Reports Server (NTRS)

    Bobbitt, Percy J

    1957-01-01

    The lifting-surface sidewash behind rolling triangular wings has been derived for a range of supersonic Mach numbers for which the wing leading edges remain swept behind the mark cone emanating from the wing apex. Variations of the sidewash with longitudinal distance in the vertical plane of symmetry are presented in graphical form. An approximate expression for the sidewash has been developed by means of an approach using a horseshoe-vortex approximate-lifting-line theory. By use of this approximate expression, sidewash may be computed for wings of arbitrary plan form and span loading. A comparison of the sidewash computed by lifting-surface and lifting-line expressions for the triangular wing showed good agreement except in the vicinity of the trailing edge when the leading edge approached the sonic condition. An illustrative calculation has been made of the force induced by the wing sidewash on a vertical tail located in various longitudinal positions.

  2. What is a safe lift?

    PubMed

    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.

  3. 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.

  4. Project LIFT: Year Two Report

    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,…

  5. Project LIFT: Year 1 Report

    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,…

  6. 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.

  7. Feasibility study of modern airships, phase 1. Volume 2: Parametric analysis (task 3). [lift, weight (mass)

    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.

  8. 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

  9. Supporting the upper body with the hand on the thigh reduces back loading during lifting.

    PubMed

    Kingma, Idsart; Faber, Gert S; van Dieën, Jaap H

    2016-04-11

    When picking objects from the floor, low back pain patients often tend to support the upper body by leaning with one hand on a thigh. While this strategy may reduce back load, this has not yet been assessed, probably due to the difficulty of measuring the forces between hand and thigh. Ten healthy male subjects lifted a pencil and a crate from the floor, with four lifting techniques (free, squat, stoop and a Weight Lifters Technique (WLT)), each of which was performed with and without supporting with one hand on the thigh. A six Degrees of Freedom force transducer, with a comfortable surface to support the hand on, was mounted just above the subject׳s left knee. Hand forces, ground reaction forces, full body kinematics, and trunk EMG were measured. Using inverse dynamics and taking the forces between hand and thigh into account, we calculated 3D L5S1 joint moments, and subsequently estimated spine forces using an EMG-assisted trunk model. For lifting a pencil, hand support reduced average peak total moments by 17-25%, dependent on lifting technique. For crate lifting, hand support reduced total moments by 13-19% compared with one-handed lifting and by 14-26% compared to two-handed lifting. Hand support slightly increased asymmetric motions and caused a substantial increase in asymmetric moments in crate lifting. For compression forces, reductions (up to 28%) were seen in all techniques except in stoop lifts. It is concluded that leaning with a hand on the thigh can lead to substantial reductions of low back loading during lifting. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Wing flexibility enhances load-lifting capacity in bumblebees

    PubMed Central

    Mountcastle, Andrew M.; Combes, Stacey A.

    2013-01-01

    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. PMID:23536604

  11. Wing flexibility enhances load-lifting capacity in bumblebees.

    PubMed

    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.

  12. Dragonfly flight. III. Lift and power requirements.

    PubMed

    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.

  13. Lift Fan Nozzle for Joint Strike Fighter Tested in NASA Lewis' Powered Lift Rig

    NASA Technical Reports Server (NTRS)

    Lam, David W.

    1998-01-01

    Under a nonreimbursable space act agreement between the NASA Lewis Research Center and the Allison Advanced Development Company, Allison tested a lift fan nozzle in Lewis' Powered Lift Rig. This test was in support of the Joint Strike Fighter program (formerly the Joint Advanced Strike Technology) sponsored by the Department of Defense, which will develop and field an affordable, multirole, next-generation, strike fighter aircraft for the Navy, Air Force, Marine Corps, and foreign allies. Allison, along with Pratt & Whitney Company, is part of the Lockheed Martin Corporation team that is scheduled to build a concept demonstrator aircraft by fiscal year 2001. The test was initiated in April and successfully completed in mid-July of 1997. Allison supplied a one-third-scale model of the lift fan nozzle, and Lewis provided the facility and the necessary support team. Various configurations, including pitching vectored angles ranging from 15deg forward to 60deg backward, were tested over a range of nozzle pressure ratios. Nozzle flow rates, thrust, and static pressures were measured for each of the configurations. Results from the test met the design requirements for the Joint Strike Fighter program and were in agreement with Allison's internal computational fluid dynamics (CFD) analyses. Data obtained from this test will also be used in the full-scale design of the lift fan system.

  14. Crossflow force transducer. [LMFBR

    SciTech Connect

    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.

  15. 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.

  16. Evaluation and optimization of quartz resonant-frequency retuned fork force sensors with high Q factors, and the associated electric circuits, for non-contact atomic force microscopy

    NASA Astrophysics Data System (ADS)

    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.

  17. Evaluation and optimization of quartz resonant-frequency retuned fork force sensors with high Q factors, and the associated electric circuits, for non-contact atomic force microscopy.

    PubMed

    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.

  18. OA-7 Lift to Stand inside PHSF

    NASA Image and Video Library

    2017-02-24

    A crane lifts Orbital ATK's CYGNUS pressurized cargo module up and away from the KAMAG transporter inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida. CYGNUS will be lowered onto a work stand for final propellant loading and late cargo stowage. The Orbital ATK CRS-7 commercial resupply services mission to the International Space Station is scheduled to launch atop a United Launch Alliance Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station on March 19, 2017. CYGNUS will deliver thousands of pounds of supplies, equipment and scientific research materials to the space station.

  19. OA-7 Cargo Module Lift to KAMAG

    NASA Image and Video Library

    2017-03-15

    Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, technicians assist as a crane is used to lift the Orbital ATK Cygnus pressurized cargo module, enclosed in its payload fairing, for transfer to a KAMAG transporter. The Orbital ATK CRS-7 commercial resupply services mission to the International Space Station is scheduled to launch atop a United Launch Alliance Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station. Cygnus will deliver 7,600 pounds of supplies, equipment and scientific research materials to the space station.

  20. OA-7 Lift to Stand inside PHSF

    NASA Image and Video Library

    2017-02-24

    A crane lifts Orbital ATK's CYGNUS pressurized cargo module up from the KAMAG transporter inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida. CYGNUS will be lowered onto a work stand for final propellant loading and late cargo stowage. The Orbital ATK CRS-7 commercial resupply services mission to the International Space Station is scheduled to launch atop a United Launch Alliance Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station on March 19, 2017. CYGNUS will deliver thousands of pounds of supplies, equipment and scientific research materials to the space station.

  1. OA-7 Cargo Module Lift to KAMAG

    NASA Image and Video Library

    2017-03-15

    Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, technicians monitor the progress as a crane is used to lift the Orbital ATK Cygnus pressurized cargo module, enclosed in its payload fairing, for transfer to a KAMAG transporter. The Orbital ATK CRS-7 commercial resupply services mission to the International Space Station is scheduled to launch atop a United Launch Alliance Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station. Cygnus will deliver 7,600 pounds of supplies, equipment and scientific research materials to the space station.

  2. OA-7 Lift to Stand inside PHSF

    NASA Image and Video Library

    2017-02-24

    A crane is attached to Orbital ATK's CYGNUS pressurized cargo module to lift it up from the KAMAG transporter inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida. CYGNUS will be lowered onto a work stand for final propellant loading and late cargo stowage. The Orbital ATK CRS-7 commercial resupply services mission to the International Space Station is scheduled to launch atop a United Launch Alliance Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station on March 19, 2017. CYGNUS will deliver thousands of pounds of supplies, equipment and scientific research materials to the space station.

  3. Lift Recovery for AFC-Enabled High Lift System

    NASA Technical Reports Server (NTRS)

    Shmilovich, Arvin; Yadlin, Yoram; Dickey, Eric D.; Gissen, Abraham N.; Whalen, Edward A.

    2017-01-01

    This project is a continuation of the NASA AFC-Enabled Simplified High-Lift System Integration Study contract (NNL10AA05B) performed by Boeing under the Fixed Wing Project. This task is motivated by the simplified high-lift system, which is advantageous due to the simpler mechanical system, reduced actuation power and lower maintenance costs. Additionally, the removal of the flap track fairings associated with conventional high-lift systems renders a more efficient aerodynamic configuration. Potentially, these benefits translate to a approx. 2.25% net reduction in fuel burn for a twin-engine, long-range airplane.

  4. 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.

  5. Swing and Lift

    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)

  6. Swing and Lift

    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)

  7. Optimization of Muscle Activity for Task-Level Goals Predicts Complex Changes in Limb Forces across Biomechanical Contexts

    PubMed Central

    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

  8. Optimizing the post-START (Strategic Arms Reduction Treaty) US strategic nuclear force mix. Master's thesis

    SciTech Connect

    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.

  9. Optimal radial force and size for palliation in gastroesophageal adenocarcinoma: a comparative analysis of current stent technology.

    PubMed

    Mbah, Nsehniitooh; Philips, Prejesh; Voor, Michael J; Martin, Robert C G

    2017-04-25

    The optimal use of esophageal stents for malignant and benign esophageal strictures continues to be plagued with variability in pain tolerance, migration rates, and reflux-related symptoms. The aim of this study was to evaluate the differences in radial force exhibited by a variety of esophageal stents with respect to the patient's esophageal stricture. Radial force testing was performed on eight stents manufactured by four different companies using a hydraulic press and a 5000 N force gage. Radial force was measured using three different tests: transverse compression, circumferential compression, and a three-point bending test. Esophageal stricture composition and diameters were measured to assess maximum diameter, length, and proximal esophageal diameter among 15 patients prior to stenting. There was a statistically significant difference in mean radial force for transverse compression tests at the middle (range 4.25-0.66 newtons/millimeter N/mm) and at the flange (range 3.32-0.48 N/mm). There were also statistical differences in mean radial force for circumferential test (ranged from 1.19 to 10.50 N/mm, p < 0.001) and the three-point bending test (range 0.08-0.28 N/mm, p < 0.001). In an evaluation of esophageal stricture diameters and lengths, the smallest median diameter of the stricture was 10 mm (range 5-16 mm) and the median proximal diameter normal esophagus was 25 mm (range 22-33 mm), which is currently outside of the range of stent diameters. Tested stents demonstrated significant differences in radial force, which provides further clarification of stent pain and intolerance in certain patients, with either benign or malignant disease. Similarly, current stent diameters do not successfully exclude the proximal esophagus, which can lead to obstructive-type symptoms. Awareness of radial force, esophageal stricture composition, and proximal esophageal diameter must be known and understood for optimal stent tolerance.

  10. Formation and decay of sensorimotor and associative memory in object lifting.

    PubMed

    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.

  11. Irrelevance of the power stroke for the directionality, stopping force, and optimal efficiency of chemically driven molecular machines.

    PubMed

    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.

  12. Irrelevance of the Power Stroke for the Directionality, Stopping Force, and Optimal Efficiency of Chemically Driven Molecular Machines

    PubMed Central

    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

  13. The effect of fatigue on multijoint kinematics and load sharing during a repetitive lifting test.

    PubMed

    Sparto, P J; Parnianpour, M; Reinsel, T E; Simon, S

    1997-11-15

    A repetitive lifting test in the sagittal plane was performed with a submaximal load at a maximal lifting rate to understand the effects of fatigue on kinematic and kinetic measures of performance. To quantify the effect of fatigue during a highly repetitive lifting task, in terms of lifting force transmitted to the load, joint motion patterns, and internal joint load sharing. Industrial surveillance and epidemiologic data suggest that repetitive lifting is a risk factor for low back pain. Previous studies examining the effect of fatigue have either been constrained to isolated trunk movement, or have not explored the internal load distribution and potential alteration in the loading patterns. Sixteen healthy male subjects performed repetitive lifting in the sagittal plane with a load equal to 25% of their maximal lifting capacity, at a maximal lifting rate. Changes in lifting performance were determined from the power transferred to the box, joint kinematics, and joint kinetics. Data from three cycles at the start and end of the exercise were tested for the effect of fatigue using repeated-measures analysis of variance. Fatigue was documented by a reduction in average lifting force and hip and spine torque generation, whereas internal joint load sharing was relatively unchanged. The fatigue was associated with decreased knee and hip motion, and increased lumbar flexion. Decreased postural stability also was evident. The significant decrease in postural stability and force generation capability because of the repetitive lifting task indicated a higher risk of injury in the presence of unexpected perturbation. Multijoint coordinated lifting tasks provide a more realistic protocol to study neuromuscular fatigue.

  14. 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.

  15. Maximum isometric lifting strengths of men in teamwork.

    PubMed

    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.

  16. Development lifts Egyptian output

    SciTech Connect

    Not Available

    1981-08-01

    Oil revenue is now the largest source of foreign exchange for the Arab Republic of Egypt, and, as such, is of vital importance to the country's plans for industrial and social development. Last year oil exports earned Egypt $2.9 billion, playing a key role in keeping the nation's economy in the black. Oil production in 1980 averaged 585,000 bpd, up from 510,000 bpd in 1979. This year oil output should average 650,000 bpd. While output is increasing, it does not appear to be doing so at a sufficient rate to meet the 1984 government target of 1 million bpd. However, the oil industry view in Egypt is that this target is achievable, though not until the mid to late 1980s. Development work scheduled for completion by 1984 only seems set to lift output to between 750,000 and 800,000 bpd. At the same time, if expansions plans for gas production are taken into account, then total hydrocarbon output measured in oil equivalents will not be too far short of the 1-million-bpd figure.

  17. Interaction of charged amino-acid side chains with ions: an optimization strategy for classical force fields.

    PubMed

    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.

  18. Lifting strength in two-person teamwork.

    PubMed

    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.

  19. 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.

  20. Hydro-resistive measurement of dynamic lifting strength.

    PubMed

    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.

  1. Detail of counterweight wire rope attachment to lift span at ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    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

  2. 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.

  3. Dynamical regimes and hydrodynamic lift of viscous vesicles under shear

    NASA Astrophysics Data System (ADS)

    Meßlinger, Sebastian; Schmidt, Benjamin; Noguchi, Hiroshi; Gompper, Gerhard

    2009-07-01

    The dynamics of two-dimensional viscous vesicles in shear flow, with different fluid viscosities ηin and ηout inside and outside, respectively, is studied using mesoscale simulation techniques. Besides the well-known tank-treading and tumbling motions, an oscillatory swinging motion is observed in the simulations for large shear rate. The existence of this swinging motion requires the excitation of higher-order undulation modes (beyond elliptical deformations) in two dimensions. Keller-Skalak theory is extended to deformable two-dimensional vesicles, such that a dynamical phase diagram can be predicted for the reduced shear rate and the viscosity contrast ηin/ηout . The simulation results are found to be in good agreement with the theoretical predictions, when thermal fluctuations are incorporated in the theory. Moreover, the hydrodynamic lift force, acting on vesicles under shear close to a wall, is determined from simulations for various viscosity contrasts. For comparison, the lift force is calculated numerically in the absence of thermal fluctuations using the boundary-integral method for equal inside and outside viscosities. Both methods show that the dependence of the lift force on the distance ycm of the vesicle center of mass from the wall is well described by an effective power law ycm-2 for intermediate distances 0.8Rp≲ycm≲3Rp with vesicle radius Rp . The boundary-integral calculation indicates that the lift force decays asymptotically as 1/[ycmln(ycm)] far from the wall.

  4. 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.

  5. Ignitability analysis using the cone calorimeter and lift apparatus

    Treesearch

    Mark A. Dietenberger

    1996-01-01

    The irradiance plotted as function of time to ignition for wood materials tested in the Cone Calorimeter (ASTM E1354) differs signiticantly from that tested in the Lateral Ignition and Flame spread Test (LIFT) apparatus (ASTM E1321). This difference in piloted ignitabilty is primarily due to the difference in forced convective cooling of the specimen tested in both...

  6. Technique of optimization of minimum temperature driving forces in the heaters of regeneration system of a steam turbine unit

    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.

  7. Outcomes of Optimal Distraction Forces and Frequencies in Growth Rod Surgery for Different Types of Scoliotic Curves: An In Silico and In vitro Study.

    PubMed

    Agarwal, Aakash; Agarwal, Anand K; Jayaswal, Arvind; Goel, Vijay K

    2017-01-01

    Analyze the effects of the distraction forces and frequencies on multiple representative scoliotic curves and to establish a relationship between high distraction forces and screw loosening. Multiple representative finite-element models of a juvenile scoliotic spine were used to study the effects of the magnitude and frequency of distraction on growth rods. Simulation of 6 months of growth under various distraction forces to analyze the effects of distraction forces on the biomechanics of the scoliotic spine and growth rod instrumentation; simulation of 24 months of growth under various intervals of distraction to analyze the effects of the distraction interval on the propensity for rod fracture; in vitro study to assess screw loosening after 6 months. For all scoliotic spine model instrumented with growth rods, an optimal distraction force existed at which normal T1-S1 growth was sustained, along with minimum stresses on the rods, the lowest load at the screw-bone interface, and the least alteration in the sagittal contour. The results followed similar trends for each model, with the numerical values of optimal distraction forces in proximity for all representative scoliotic spine models. The in vitro study proved that the pullout strength of pedicle screws reduced significantly after 6 months of fatigue at higher distraction forces (in comparison with optimal distraction forces). This corroborated the finite-element findings for lower loads at the screw-bone interface with optimal distraction forces. This study concludes that the optimal distraction forces exists for all types of scoliotic curves that have been instrumented with growth rods, which exhibits reduction of stresses on the rods with frequent distractions. This study also links the second most common complication, screw loosening, with high distraction forces. Therefore, optimizing the biomechanical environment of the dual growth rods could drastically reduce the biomechanical complications

  8. 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.

  9. 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

  10. The mechanisms of lift enhancement in insect flight.

    PubMed

    Lehmann, Fritz-Olaf

    2004-03-01

    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.

  11. Unsuccessful vs. successful performance in snatch lifts: a kinematic approach.

    PubMed

    Gourgoulis, Vassilios; Aggeloussis, Nikolaos; Garas, Athanasios; Mavromatis, Georgios

    2009-03-01

    The purpose of the present study was to determine the kinematic characteristics of snatch movements that result in an unsuccessful performance, involving the barbell's drop in front of the weightlifter. The sample comprised 7 high-level men weightlifters competing at the international level. Their successful and unsuccessful snatch lifts with the same load were recorded with 2 S-VHS camcorders (60 Hz), and selected points onto the body and the barbell were digitized manually using the Ariel Performance Analysis System. The statistical treatment of the data showed no significant differences (p > 0.05) between successful and unsuccessful lifts in the angular displacement and velocity data of the lower-limb joints, the trajectory and vertical linear velocity of the barbell, or the generated work and power output during the first and second pulls of the lift. Consequently, the general movement pattern of the limbs and the barbell was not modified in unsuccessful lifts in relation to the successful ones. However, significant differences (p < 0.05) were found in the direction of the barbell's resultant acceleration vector, suggesting that proper direction of force application onto the barbell is crucial for a successful performance in snatch lifts. Thus, coaches should pay particular attention to the applied force onto the barbell from the first pull.

  12. 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.

  13. Disturbance and recovery of trunk mechanical and neuromuscular behaviours following repetitive lifting: influences of flexion angle and lift rate on creep-induced effects.

    PubMed

    Toosizadeh, Nima; Bazrgari, Babak; Hendershot, Brad; Muslim, Khoirul; Nussbaum, Maury A; Madigan, Michael L

    2013-01-01

    Repetitive lifting is associated with an increased risk of occupational low back disorders, yet potential adverse effects of such exposure on trunk mechanical and neuromuscular behaviours were not well described. Here, 12 participants, gender balanced, completed 40 min of repetitive lifting in all combinations of three flexion angles (33, 66, and 100% of each participant's full flexion angle) and two lift rates (2 and 4 lifts/min). Trunk behaviours were obtained pre- and post-exposure and during recovery using sudden perturbations. Intrinsic trunk stiffness and reflexive responses were compromised after lifting exposures, with larger decreases in stiffness and reflexive force caused by larger flexion angles, which also delayed reflexive responses. Consistent effects of lift rate were not found. Except for reflex delay no measures returned to pre-exposure values after 20 min of recovery. Simultaneous changes in both trunk stiffness and neuromuscular behaviours may impose an increased risk of trunk instability and low back injury. An elevated risk of low back disorders is attributed to repetitive lifting. Here, the effects of flexion angle and lift rate on trunk mechanical and neuromuscular behaviours were investigated. Increasing flexion angle had adverse effects on these outcomes, although lift rate had inconsistent effects and recovery time was more than 20 min.

  14. 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.

  15. 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.

  16. Towards optimal multi-channel EMG electrode configurations in muscle force estimation: a high density EMG study.

    PubMed

    Staudenmann, Didier; Kingma, Idsart; Stegeman, Dick F; van Dieën, Jaap H

    2005-02-01

    Surface EMG is an important tool in biomechanics, kinesiology and neurophysiology. In neurophysiology the concept of high-density EMG (HD-EMG), using two dimensional electrode grids, was developed for the measurement of spatiotemporal activation patterns of the underlying muscle and its motor units (MU). The aim of this paper was to determine, with the aid of a HD-EMG grid, the relative importance of a number of electrode sensor configurations for optimizing muscle force estimation. Sensor configurations are distinguished in two categories. The first category concerns dimensions: the size of a single electrode and the inter electrode distance (IED). The second category concerns the sensor's spatial distribution: the total area from which signals are obtained (collection surface) and the number of electrodes per cm(2) (collection density). Eleven subjects performed isometric arm extensions at three elbow angles and three contraction levels. Surface-EMG from the triceps brachii muscle and the external force at the wrist were measured. Compared to a single conventional bipolar electrode pair, the force estimation quality improved by about 30% when using HD-EMG. Among the sensor configurations, the collection surface alone appeared to be responsible for the major part of the EMG based force estimation quality by improving it with 25%.

  17. 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.

    2017-08-01

    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.

  18. Distribution of forces between synergistics and antagonistics muscles using an optimization criterion depending on muscle contraction behavior.

    PubMed

    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.

  19. Null lifts and projective dynamics

    SciTech Connect

    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.

  20. 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.

  1. The Future of Heavy Lift

    DTIC Science & Technology

    2002-03-01

    Future of Heavy Lift. MAWTS-1 Memo, 2001. Osprey On-Line. Home Page. <http://www.navair.navy.mil/ v22 />. Overarching Commonality Assessment...logistics tails grow. While the MV-22 Osprey will provide this "Over the Horizon" (OTH) capability, it is strictly a medium lift aircraft. It will never...territory. The MV-22 is the Marine Corps’ current answer to implementing OMFTS/STOM from an aviation perspective. 3 The Osprey will eventually

  2. 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.

  3. 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.

  4. OptForce: An Optimization Procedure for Identifying All Genetic Manipulations Leading to Targeted Overproductions

    PubMed Central

    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

  5. 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.

  6. Optimizing Army Special Forces Leaders in a Global Counter-Insurgent Network

    DTIC Science & Technology

    2007-03-01

    network , topographically, is a system in which everyone is connected to everyone else with the authority to move information or goods in any direction.23...ARMY SPECIAL FORCES LEADERS IN A GLOBAL COUNTER-INSURGENT NETWORK by Joshua H. Walker Eric J. Deal March 2007 Thesis Advisor: John...Arquilla Second Readers: Peter Gustaitis Wayne Hughes THIS PAGE INTENTIONALLY LEFT BLANK i REPORT

  7. Delta II Second stage lift and mate

    NASA Image and Video Library

    2007-01-19

    On Pad 17-B at Cape Canaveral Air Force Station, the Delta II second stage is lifted toward the mobile service tower. Once inside, it will be mated with the first stage already in place. The Delta II is the launch vehicle for the THEMIS spacecraft. THEMIS consists of five identical probes, the largest number of scientific satellites ever launched into orbit aboard a single rocket. This unique constellation of satellites will resolve the tantalizing mystery of what causes the spectacular sudden brightening of the aurora borealis and aurora australis - the fiery skies over the Earth's northern and southern polar regions. THEMIS is scheduled to launch Feb. 15 from Cape Canaveral Air Force Station.

  8. Delta II Second stage lift and mate

    NASA Image and Video Library

    2007-01-19

    On Pad 17-B at Cape Canaveral Air Force Station, the Delta II second stage is being lifted alongside the mobile service tower. Once inside, it will be mated with the first stage already in place. The Delta II is the launch vehicle for the THEMIS spacecraft. THEMIS consists of five identical probes, the largest number of scientific satellites ever launched into orbit aboard a single rocket. This unique constellation of satellites will resolve the tantalizing mystery of what causes the spectacular sudden brightening of the aurora borealis and aurora australis - the fiery skies over the Earth's northern and southern polar regions. THEMIS is scheduled to launch Feb. 15 from Cape Canaveral Air Force Station.

  9. Delta II Second stage lift and mate

    NASA Image and Video Library

    2007-01-19

    On Pad 17-B at Cape Canaveral Air Force Station, workers attach an overhead crane to the Delta II second stage in order to raise it to vertical. It will be lifted into the mobile service tower and mated with the first stage already in place. The Delta II is the launch vehicle for the THEMIS spacecraft. THEMIS consists of five identical probes, the largest number of scientific satellites ever launched into orbit aboard a single rocket. This unique constellation of satellites will resolve the tantalizing mystery of what causes the spectacular sudden brightening of the aurora borealis and aurora australis - the fiery skies over the Earth's northern and southern polar regions. THEMIS is scheduled to launch Feb. 15 from Cape Canaveral Air Force Station.

  10. Isokinetic and isometric lifting capacity of Chinese in relation to the physical demand of job.

    PubMed

    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.

  11. Partial Validation of Multibody Program to Optimize Simulated Trajectories II (POST II) Parachute Simulation With Interacting Forces

    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.

  12. Measurements of drag and lift on smooth balls in flight

    NASA Astrophysics Data System (ADS)

    Cross, Rod; Lindsey, Crawford

    2017-07-01

    Measurements are presented on the drag and lift coefficients for three relatively smooth balls launched in air and tracked with two cameras separated horizontally by 6.4 m. The ball spin was varied in order to investigate whether the Magnus force would increase or decrease when the ball spin was increased. For one ball, the Magnus force increased. For another ball, the Magnus force decreased almost to zero after reaching a maximum. For the third ball, the Magnus force was negative at low ball spins and positive at high ball spins. For one of the balls, the ball spin increased with time as it travelled through the air.

  13. Severe obesity effect on low back biomechanical stress of manual load lifting.

    PubMed

    Singh, Devender; Park, Woojin; Hwang, Dongwook; Levy, Martin S

    2015-06-05

    Little research is available on low back biomechanical stresses that obese and overweight workers experience from manual load lifting. The study objective was to quantitatively evaluate low back biomechanical stresses of severely obese (BMI≥35 kg/m2) workers during manual lifts of moderate load weights. Twenty severely obese and 20 normal weight participants performed infrequent lifting in 16 task conditions. In each task condition, NIOSH recommended load weights were computed for the origin and destination of lift and were employed as the load weights. Optical motion capture was performed to collect lifting posture data. For each participant and each lifting condition, L5/S1 disc compression forces were computed at the origin and destination of lift using a static low back biomechanical model. The L5/S1 disc compression forces estimated for the severely obese participants ranged from 3000N to 8500N and many exceeded the 3400N NIOSH action limit by large margins. Group mean disc compression force was significantly larger for the severely obese than the normal weight group. In light of previous research on spine, bone and obesity, the study results seem to suggest that severely obese individuals are likely at an increased risk of lifting-related low back pain compared with normal weight individuals.

  14. 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.

  15. 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

  16. An experimental study of spanwise flow effects on lift generation in flapping wings

    NASA Astrophysics Data System (ADS)

    Hong, Youngsun

    Using a combination of force transducer measurement to quantify net lift force, a high frame rate camera to quantify and subtract inertial contributions, and Digital Particle Image Velocimetry (DPIV) to calculate aerodynamic contributions in the spanwise plane, the contribution of spanwise flow to the generation of lift force in wings undergoing a pure flapping motion in hover is shown as a function of flapping angle throughout the flapping cycle. When flapping a flat plate wing and a wing of identical wing area and aspect ratio, but cambered in span (both wings in hover with no change in pitch), the spanwise cambered wing was found to generate a greater mean lift force through the whole flap cycle under the same acceleration. However, depending on the angle in flapping arc, the spanwise cambered wing can generate less lift than the flat wing. Additionally, since the lift force generated by the wingtip vortex in the spanwise plane resulting from the flapping motion has yet to be directly quantified, the wingtip vortex is investigated to determine precisely how it augments the lift force through the various phases in the flapping motion. Vortices in the vicinity of the wingtip generate lift force in the spanwise plane of flapping wings. In classical fixed wing aerodynamics, the presence of wing tip vortices has been shown to increase the lift locally near the tip. Also, the impingement of large vortices on the upper surface of delta wings is considered to contribute largely to the lift force at higher angles of attack. This study determined that vortices in the spanwise plane (streamwise vorticity) generate lift in a similar manner in flapping wings. Using a mechanical ornithopter with wings fabricated in-house, vortices were identified at several different locations along the span of the wing, and at numerous different points throughout the flapping cycle under a variety of operating conditions. The lift generated by these spanwise planar oriented vortices was

  17. 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.

  18. 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.

  19. 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.

  20. Material evidence: interaction of well-learned priors and sensorimotor memory when lifting objects.

    PubMed

    Baugh, Lee A; Kao, Michelle; Johansson, Roland S; Flanagan, J Randall

    2012-09-01

    Skilled object lifting requires the prediction of object weight. When lifting new objects, such prediction is based on well-learned size-weight and material-density correlations, or priors. However, if the prediction is erroneous, people quickly learn the weight of the particular object and can use this knowledge, referred to as sensorimotor memory, when lifting the object again. In the present study, we explored how sensorimotor memory, gained when lifting a given object, interacts with well-learned material-density priors when predicting the weight of a larger but otherwise similar-looking object. Different groups of participants 1st lifted 1 of 4 small objects 10 times. These included a pair of wood-filled objects and a pair of brass-filled objects where 1 of each pair was covered in a wood veneer and the other was covered in a brass veneer. All groups then lifted a larger, brass-filled object with the same covering as the small object they had lifted. For each lift, we determined the initial peak rate of change of vertical load-force rate and the load-phase duration, which provide estimates of predicted object weight. Analysis of the 10th lift of the small cube revealed no effects of surface material, indicating participants learned the appropriate forces required to lift the small cube regardless of object appearance. However, both surface material and core material of the small cube affected the 1st lift of the large block. We conclude that sensorimotor memory related to object density can contribute to weight prediction when lifting novel objects but also that long-term priors related to material properties can influence the prediction.

  1. Computational Analysis of Powered Lift Augmentation for the LEAPTech Distributed Electric Propulsion Wing

    NASA Technical Reports Server (NTRS)

    Deere, Karen A.; Viken, Sally A.; Carter, Melissa B.; Viken, Jeffrey K.; Wiese, Michael R.; Farr, Norma L.

    2017-01-01

    A computational study of a distributed electric propulsion wing with a 40deg flap deflection has been completed using FUN3D. Two lift-augmentation power conditions were compared with the power-off configuration on the high-lift wing (40deg flap) at a 73 mph freestream flow and for a range of angles of attack from -5 degrees to 14 degrees. The computational study also included investigating the benefit of corotating versus counter-rotating propeller spin direction to powered-lift performance. The results indicate a large benefit in lift coefficient, over the entire range of angle of attack studied, by using corotating propellers that all spin counter to the wingtip vortex. For the landing condition, 73 mph, the unpowered 40deg flap configuration achieved a maximum lift coefficient of 2.3. With high-lift blowing the maximum lift coefficient increased to 5.61. Therefore, the lift augmentation is a factor of 2.4. Taking advantage of the fullspan lift augmentation at similar performance means that a wing powered with the distributed electric propulsion system requires only 42 percent of the wing area of the unpowered wing. This technology will allow wings to be 'cruise optimized', meaning that they will be able to fly closer to maximum lift over drag conditions at the design cruise speed of the aircraft.

  2. Development of a Low-Lift Chiller Controller and Simplified Precooling Control Algorithm - Final Report

    SciTech Connect

    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.

  3. Controlled DNA Patterning by Chemical Lift-Off Lithography: Matrix Matters.

    PubMed

    Cao, Huan H; Nakatsuka, Nako; Serino, Andrew C; Liao, Wei-Ssu; Cheunkar, Sarawut; Yang, Hongyan; Weiss, Paul S; Andrews, Anne M

    2015-11-24

    Nucleotide arrays require controlled surface densities and minimal nucleotide-substrate interactions to enable highly specific and efficient recognition by corresponding targets. We investigated chemical lift-off lithography with hydroxyl- and oligo(ethylene glycol)-terminated alkanethiol self-assembled monolayers as a means to produce substrates optimized for tethered DNA insertion into post-lift-off regions. Residual alkanethiols in the patterned regions after lift-off lithography enabled the formation of patterned DNA monolayers that favored hybridization with target DNA. Nucleotide densities were tunable by altering surface chemistries and alkanethiol ratios prior to lift-off. Lithography-induced conformational changes in oligo(ethylene glycol)-terminated monolayers hindered nucleotide insertion but could be used to advantage via mixed monolayers or double-lift-off lithography. Compared to thiolated DNA self-assembly alone or with alkanethiol backfilling, preparation of functional nucleotide arrays by chemical lift-off lithography enables superior hybridization efficiency and tunability.

  4. Ab initio protein structure assembly using continuous structure fragments and optimized knowledge-based force field.

    PubMed

    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.

  5. The Physics of Optimal Decision Making: A Formal Analysis of Models of Performance in Two-Alternative Forced-Choice Tasks

    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…

  6. The Physics of Optimal Decision Making: A Formal Analysis of Models of Performance in Two-Alternative Forced-Choice Tasks

    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…

  7. Stability enhancement and fuel economy of the 4-wheel-drive hybrid electric vehicles by optimal tyre force distribution

    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.

  8. Strike a Balance: Optimization of Backbone Torsion Parameters of AMBER Polarizable Force Field for Simulations of Proteins and Peptides

    PubMed Central

    WANG, ZHI-XIANG; ZHANG, WEI; WU, CHUN; LEI, HONGXING; CIEPLAK, PIOTR; DUAN, YONG

    2014-01-01

    Based on the AMBER polarizable model (ff02), we have reoptimized the parameters related to the main-chain (Φ, Ψ) torsion angles by fitting to the Boltzmann-weighted average quantum mechanical (QM) energies of the important regions (i.e., β, PII, αR, and αL regions). Following the naming convention of the AMBER force field series, this release will be called ff02pol.rl The force field has been assessed both by energetic comparison against the QM data and by the replica exchange molecular dynamics simulations of short alanine peptides in water. For Ace-Ala-Nme, the simulated populations in the β, PII and αR regions were approximately 30, 43, and 26%, respectively. For Ace-(Ala)7-Nme, the populations in these three regions were approximately 24, 49, and 26%. Both were in qualitative agreement with the NMR and CD experimental conclusions. In comparison with the previous force field, ff02pol.rl demonstrated good balance among these three important regions. The optimized torsion parameters, together with those in ff02, allow us to carry out simulations on proteins and peptides with the consideration of polarization. PMID:16526038

  9. Using Future Value Analysis to Select an Optimal Portfolio of Force Protection Initiatives

    DTIC Science & Technology

    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

  10. 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.

  11. 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.

  12. Ab Initio Protein Structure Assembly Using Continuous Structure Fragments and Optimized Knowledge-based Force Field

    PubMed Central

    Xu, Dong; Zhang, Yang

    2012-01-01

    Ab initio protein folding is one of the major unsolved problems in computational biology due 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 non-homologous proteins. Although no global templates are used and all fragments from experimental structures with template modeling score (TM-score) >0.5 are excluded, QUARK can successfully construct 3D models of correct folds in 1/3 cases of short proteins up to 100 residues. In the ninth community-wide Critical Assessment of protein Structure Prediction (CASP9) 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 (GDT-TS) scores in the free modeling (FM) category. Although ab initio protein folding remains a significant challenge, these data demonstrate new progress towards the solution of the most important problem in the field. PMID:22411565

  13. Mist lift analysis summary report

    SciTech Connect

    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.

  14. Normalized lift: an energy interpretation of the lift coefficient simplifies comparisons of the lifting ability of rotating and flapping surfaces.

    PubMed

    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.

  15. Normalized Lift: An Energy Interpretation of the Lift Coefficient Simplifies Comparisons of the Lifting Ability of Rotating and Flapping Surfaces

    PubMed Central

    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

  16. 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.

  17. Optimized Model Surfaces for Advanced Atomic Force Microscopy Studies of Surface Nanobubbles.

    PubMed

    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.

  18. Minimizing Energy Use and GHG Emissions of Lift Stations Utilizing Real-Time Pump Control Strategies.

    PubMed

    Badruzzaman, Mohammad; Crane, Travis; Hollifield, Darren; Wilcoxson, David; Jacangelo, Joseph G

    2016-11-01

      Wastewater collection system lift station operations require a substantial amount of energy, and can be as a major source of greenhouse gas (GHG) emissions for wastewater utilities. Many lift stations operate with local or basic controls that have no hydraulic relationship with other collection system lift stations. This study demonstrated a unique energy-efficient control method of lift station operation that utilizes hydraulic modeling results generated from site-specific conditions to optimize the pumping units and reduce simultaneous running cycles on a real time basis. The pilot tests conducted at two pilot areas of the wastewater collection system of a utility in Florida demonstrated that the energy savings obtained through such operational optimization was 14 to 17% for the two pilot areas investigated. The study demonstrated that substantial annual energy costs and GHG emissions reduction could be achieved utilizing this method, particularly for utilities located in flat geographic locations where hundreds of lift stations are required to transfer wastewater.

  19. Lifting without Seeing: The Role of Vision in Perceiving and Acting upon the Size Weight Illusion

    PubMed Central

    Buckingham, Gavin; Goodale, Melvyn A.

    2010-01-01

    Background Our expectations of an object's heaviness not only drive our fingertip forces, but also our perception of heaviness. This effect is highlighted by the classic size-weight illusion (SWI), where different-sized objects of identical mass feel different weights. Here, we examined whether these expectations are sufficient to induce the SWI in a single wooden cube when lifted without visual feedback, by varying the size of the object seen prior to the lift. Methodology/Principal Findings Participants, who believed that they were lifting the same object that they had just seen, reported that the weight of the single, standard-sized cube that they lifted on every trial varied as a function of the size of object they had just seen. Seeing the small object before the lift made the cube feel heavier than it did after seeing the large object. These expectations also affected the fingertip forces that were used to lift the object when vision was not permitted. The expectation-driven errors made in early trials were not corrected with repeated lifting, and participants failed to adapt their grip and load forces from the expected weight to the object's actual mass in the same way that they could when lifting with vision. Conclusions/Significance Vision appears to be crucial for the detection, and subsequent correction, of the ostensibly non-visual grip and load force errors that are a common feature of this type of object interaction. Expectations of heaviness are not only powerful enough to alter the perception of a single object's weight, but also continually drive the forces we use to lift the object when vision is unavailable. PMID:20300575

  20. Lifting China's water spell.

    PubMed

    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.

  1. Non-covalent forces tune the electron transfer complex between ferredoxin and sulfite reductase to optimize enzymatic activity.

    PubMed

    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.

  2. 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’.

  3. 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.

  4. 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.

  5. Automatic protein design with all atom force-fields by exact and heuristic optimization.

    PubMed

    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

  6. Protein model refinement using an optimized physics-based all-atom force field.

    PubMed

    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.

  7. 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.

  8. 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.

  9. An optimal pole-matching observer design for estimating tyre-road friction force

    NASA Astrophysics Data System (ADS)

    Faraji, Mohammad; Johari Majd, Vahid; Saghafi, Behrooz; Sojoodi, Mahdi

    2010-10-01

    In this paper, considering the dynamical model of tyre-road contacts, we design a nonlinear observer for the on-line estimation of tyre-road friction force using the average lumped LuGre model without any simplification. The design is the extension of a previously offered observer to allow a muchmore realistic estimation by considering the effect of the rolling resistance and a term related to the relative velocity in the observer. Our aim is not to introduce a new friction model, but to present a more accurate nonlinear observer for the assumed model. We derive linear matrix equality conditions to obtain an observer gain with minimum pole mismatch for the desired observer error dynamic system. We prove the convergence of the observer for the non-simplified model. Finally, we compare the performance of the proposed observer with that of the previously mentioned nonlinear observer, which shows significant improvement in the accuracy of estimation.

  10. Integral lift engine preliminary design

    NASA Technical Reports Server (NTRS)

    Pratt, W.; Leto, A.; Schaefer, R.

    1971-01-01

    A preliminary mechanical design of a complete lift fan engine system is reported. A description of the lift fan engine, layout drawings of the components and complete engine, and a discussion of the design analyses and results are presented. The design features and areas of analysis include fan and compressor rotor blades of composite construction, a combustor folded over the compressor, relatively high-temperature blades in the high-pressure turbine, the first stage of the low-pressure turbine used for bearing support and ducting of lubricant to the bearings, a complete lubrication system, critical speeds of the shafting, and vibration and flutter of the blading.

  11. Endoscopic brow lifts uber alles.

    PubMed

    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.

  12. SMAP Lift to CR

    NASA Image and Video Library

    2014-10-16

    Inside the Astrotech payload processing facility on Vandenberg Air Force Base in California, engineers and technicians rotate NASA's Soil Moisture Active Passive, or SMAP, spacecraft to begin processing. SMAP will launch on a Delta II 7320 configuration vehicle featuring a United Launch Alliance first stage booster powered by an Aerojet Rocketdyne RS-27A main engine and three Alliant Techsystems, or ATK, strap-on solid rocket motors. Once on station in Earth orbit, SMAP will provide global measurements of soil moisture and its freeze/thaw state. These measurements will be used to enhance understanding of processes that link the water, energy and carbon cycles, and to extend the capabilities of weather and climate prediction models. SMAP data also will be used to quantify net carbon flux in boreal landscapes and to develop improved flood prediction and drought monitoring capabilities. Launch from Space Launch Complex 2 is targeted for Jan. 29, 2015.

  13. SMAP Lift to CR

    NASA Image and Video Library

    2014-10-16

    Inside the Astrotech payload processing facility on Vandenberg Air Force Base in California, engineers and technicians inspect NASA's Soil Moisture Active Passive, or SMAP, spacecraft. SMAP will launch on a Delta II 7320 configuration vehicle featuring a United Launch Alliance first stage booster powered by an Aerojet Rocketdyne RS-27A main engine and three Alliant Techsystems, or ATK, strap-on solid rocket motors. Once on station in Earth orbit, SMAP will provide global measurements of soil moisture and its freeze/thaw state. These measurements will be used to enhance understanding of processes that link the water, energy and carbon cycles, and to extend the capabilities of weather and climate prediction models. SMAP data also will be used to quantify net carbon flux in boreal landscapes and to develop improved flood prediction and drought monitoring capabilities. Launch from Space Launch Complex 2 is targeted for Jan. 29, 2015.

  14. SMAP Lift to CR

    NASA Image and Video Library

    2014-10-16

    Inside the Astrotech payload processing facility on Vandenberg Air Force Base in California, engineers and technicians remove a protective covering from NASA's Soil Moisture Active Passive, or SMAP, spacecraft. SMAP will launch on a Delta II 7320 configuration vehicle featuring a United Launch Alliance first stage booster powered by an Aerojet Rocketdyne RS-27A main engine and three Alliant Techsystems, or ATK, strap-on solid rocket motors. Once on station in Earth orbit, SMAP will provide global measurements of soil moisture and its freeze/thaw state. These measurements will be used to enhance understanding of processes that link the water, energy and carbon cycles, and to extend the capabilities of weather and climate prediction models. SMAP data also will be used to quantify net carbon flux in boreal landscapes and to develop improved flood prediction and drought monitoring capabilities. Launch from Space Launch Complex 2 is targeted for Jan. 29, 2015.

  15. SMAP Lift to CR

    NASA Image and Video Library

    2014-10-16

    Inside the Astrotech payload processing facility on Vandenberg Air Force Base in California, engineers and technicians begin processing of NASA's Soil Moisture Active Passive, or SMAP, spacecraft. SMAP will launch on a Delta II 7320 configuration vehicle featuring a United Launch Alliance first stage booster powered by an Aerojet Rocketdyne RS-27A main engine and three Alliant Techsystems, or ATK, strap-on solid rocket motors. Once on station in Earth orbit, SMAP will provide global measurements of soil moisture and its freeze/thaw state. These measurements will be used to enhance understanding of processes that link the water, energy and carbon cycles, and to extend the capabilities of weather and climate prediction models. SMAP data also will be used to quantify net carbon flux in boreal landscapes and to develop improved flood prediction and drought monitoring capabilities. Launch from Space Launch Complex 2 is targeted for Jan. 29, 2015.

  16. Improvements in linked-spar motion-compensated lifting system

    NASA Astrophysics Data System (ADS)

    Olsen, R. A.; Cuthbertson, R. A.

    1984-10-01

    An improved system for operating a lifting cable over the side of a ship at sea in which a spar buoy having an adjustable lifting capacity is coupled to the shop by a rigid linkage which is free to pivot on an axis attached to the ship deck, and operates to decouple the motion of the ship from lifting cable. The spar buoy is attached to a gimbal sheave assembly having a disengageable connector and tension line for drawing the connector into engagement with a mating socket at the outward end of a linkage boom. A narrow upper section of the spar buoy is provided with a plurality of vertical tubes and valves which by flooding or evacuation operate to vary the effective water plane area of the buoy for continual fine tuning and optimally adjusting of its natural heave mode characteristic frequency.

  17. 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.

  18. Relative Contribution of Lower Body Work as a Biomechanical Determinant of Spine Sparing Technique During Common Paramedic Lifting Tasks.

    PubMed

    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.

  19. Effect of mental processing on low back load while lifting an object.

    PubMed

    Katsuhira, Junji; Matsudaira, Ko; Iwakiri, Kazuyuki; Kimura, Yoshiki; Ohashi, Tsukasa; Ono, Ryosuke; Sugita, Sho; Fukuda, Keisuke; Abe, Soyoka; Maruyama, Hitoshi

    2013-06-01

    Biomechanical study using a 3D motion analysis system conducted in a laboratory setting. To determine the effect of mental processing on low back load during lifting. In addition to ergonomic factors such as frequent lifting, work-related psychosocial factors are significant in the onset of disabling back pain. Although the ergonomic effects on low back load while lifting have been investigated and are widely accepted in the workplace, few studies have investigated the effect of psychosocial factors on low back load while lifting. Thirteen healthy subjects lifted a box from the ground in 4 different lifting tasks in randomized order: (1) squat posture with knees flexed; (2) stoop posture with knees extended; (3) squat posture with mental processing using arithmetic tasks; and (4) stoop posture with mental processing using arithmetic tasks. We used a 3D motion analysis system and 4 force plates to record kinematic and kinetic data. We calculated dynamic triaxial low back joint moments and low back compression force as index parameters of low back load under these experimental conditions. Mental processing significantly increased peak low back compression force and low back extension moment, but not lateral flexion or rotation moment, while lifting in both lifting postures. Also, mental processing increased trunk bending angles in the squat posture. Although a tendency for decreased pelvic forward tilt was observed, mental processing did not significantly decrease forward pelvic tilt in the stoop posture. Mental processing during lifting tasks seems to affect both trunk and pelvis angles in the sagittal plane for squat and stoop postures, resulting in increased low back load. The present findings might help explain the effect of ergonomic demands of lifting tasks as well as psychosocial factors responsible for the onset of disabling back pain. 2.

  20. 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.